Archive for November, 2006
guardian.co.uk
Topsy-turvy weather upsets people as well as birds and bees
John Vidal, environment editor
Saturday February 21, 2004
The Guardian
Britain is experiencing one of its weirdest-ever Februaries. Tulips were reported to be in full flower in Bedfordshire yesterday, swallows were nesting in Kent, frogs were mating furiously in Shropshire and bumblebees were flying around Scotland - even as forecasters predicted more freezing weather.
This year’s topsy-turvy weather, which has seen bitter arctic weather mixed up with record high February temperatures, is as confusing to people as to the birds and bees.
“It’s almost as likely that we’ll get sunbathing weather in February now as snow,” a Met office spokesman said yesterday. “This month we’ve had girls in bikinis at Bournemouth and heavy snow.”
Most unusual this year has been the arrival of very unseasonal birds. To the astonishment of migration experts, more than 30 house martins - usually early summer visitors - have already been logged in Kent, the Isle of Wight and the Isles of Scilly, and there have been at least three swallow sightings.
“Normally such events don’t occur before late March,” the British Trust for Ornithology said. “Such a widespread arrival, involving so many birds so early in the year is unprecedented. Something very unusual is happening,” its spokeswoman Dawn Balmer said.
“When a few birds appear it seemed like an isolated occurrence, then more were reported and a remarkable picture is building up and it’s fascinating waiting to see what happens next.”
What influenced the arrival of some birds more than six weeks early was the surge of mild air from the south-west immediately after the cold snap earlier this month.
This even attracted a rare red-rumped swallow to Cornwall. Not only a summer bird showing up in winter, it had flown hundreds of miles beyond its normal northern limit.
The UK Phenology Network, which links up more than 13,000 amateur nature watchers and records the arrival of the seasons, has reported lawns being cut at Christmas, primroses in November and snowdrops in December.
A combination of very warm temperatures and wet weather since mid-January has caused most flowers to blossom early.
What used to be called “winter” has for several years now been effectively banished or reduced to short, sharp spells, say some weather watchers.
“Even before Christmas we had reports of snowdrops and frogspawn appearing in the west country, and people mowing their lawns over the festive season,” a spokesman for the Phenology Network said.
“By January 24 we had had more than 24 observations of primroses and frogspawn, and 72 people had cut their lawns”.
But the danger is that earlier-flowering plants and nesting birds can be catastrophically hit by severe weather.
“It’s clear that plants which flower precociously and then are shocked by low temperatures have their ability to produce seeds severely limited,” said Phil Gates, a botany lecturer at Durham University.
US studies, he said, had found that tree growth could be curtailed and fruit trees especially could be seriously damaged.
“The problem for fruit trees is that when they blossom early they are not synchronised with pollinators, like bees.”
There are worries, too, for many birds. Bird nesting is timed to coincide with the emergence of caterpillars to feed the birds’ young. But with young leaves appearing earlier, this could undermine the caterpillars’ food supply, Dr Gates said. “It could have a catastrophic effect on their breeding success.”
November 16th, 2006
scielo.br
ONIKI, Y. and WILLIS, E. O.
Departamento de Zoologia, Unesp, CEP 13506-900, Rio Claro, SP, Brazil
Correspondence to: Yoshika Oniki, Departamento de Zoologia, Unesp, CEP 13506-900, Rio Claro, SP, Brazil, e-mail: ewillis@rc.unesp.br
Received May 3, 1999 ¾ Accepted March 16, 2000 ¾ Distributed November 30, 2000
(With 5 figures)
ABSTRACT
An August or winter nestling of Eupetomena macroura was fed only every 40-50 min for at least 24 days in the nest, with fewer feedings at midday. As in other hummingbirds, it was brooded only the first week or two, and left alone even on cool nights after 12 days, probably due to the small nest size. The female attacked birds of many non-nectarivore species near the nest, in part probably to avoid predation. Botfly parasitism was extremely high, as in some other forest-edge birds.
Key words: nesting, hummingbird, Eupetomena macroura, parasitism, predation.
RESUMO
Comportamento reprodutivo do beija-flor-tesoura, Eupetomena macroura (Trochilidae, Aves)
Um jovem, de agosto ou inverno, de Eupetomena macroura foi alimentado somente a cada 40-50 min., com menos alimentações no meio do dia. Ficou, pelo menos, 24 dias no ninho. Como em outros beija-flores, a fêmea permaneceu no ninho à noite somente na primeira ou segunda semana e deixou o jovem sozinho mesmo em noites mais frias após 12 dias, provavelmente devido ao tamanho pequeno do ninho. A fêmea atacou aves de muitas espécies não-nectarívoras nas proximidades do ninho, em parte provavelmente para evitar a predação. O parasitismo por larvas de dípteros foi extremamente alto, como em algumas outras espécies de aves de borda.
Palavras-chave: nidificação, beija-flor, Eupetomena macroura, parasitismo, predação.
INTRODUCTION
The Swallow-tailed Hummingbird (Eupetomena macroura, Trochilidae) is the best known hummingbird to Brazilians, because it is rather large (9.01 ± 0.90 g, n = 478), has a conspicuously forked tail and is commonly found in back yards and gardens where flowering plants are available. In 1993, students helped us watch a nest from which a first brood had departed in July (G. A. Bencke, pers. comm.), to determine patterns of activity.
MATERIAL, STUDY SITE AND METHODS
The nest, on lawns of the Universidade Estadual Paulista campus (22o23′S, 47o33′W, 620 m elevation) in Rio Claro, São Paulo State, Brazil was studied with binoculars Nikon 9 × 23 and Zeiss 8 × 30, for 203.3 hours.
One to three persons watched quietly, 10 or so meters away, to avoid disturbing the female.
RESULTS
Nest and breeding period
The cup nest was 2.3 m in a 6 m small tree, on a branch 1 m from the 13 cm diameter trunk. It was 44 mm external diameter, 32 internal, 48 external height and 18 internal. One young was present, 13 August to 6 September when it left; we watched it in a few nearby trees that day and the next.
Willis found four other nests 1.5-2.5 m up in Rio Claro, with young Sept. (2 nests) and Oct. (2). A. Z. Antunes (pers. comm.) found a nest with two eggs 19 August in a Cochlospermum sp. (Cochlospermaceae). Young disappeared between 25 and 28 Sept. The Forest Police brought one large young on 2 June 1997; apparently it had fallen from a nest. In Campinas, nestlings were fed 5 m up in Aug. In Santa Teresa, Espírito Santo, Willis found nests 2 and 3 m up in Feb. and Sept., the latter with young. He noted large young fed out of the nest in April at Santa Teresa and 3 Jan. at Araçatuba (SP), and adults carrying plant down at Itirapina (SP) in Sept., Águas de Santa Bárbara (SP) in Aug., and Barrolândia (BA) in July.
Reiser (in Snethlage, 1928) reported a young out of the nest in March. Two eggs were reported in June; nestlings in another nest, July; young out in Aug.; carrying material in December (Erickson & Mumford, 1976). Ruschi (1986) reports nests, giving “22″ days as the nestling period, but does not present data. Nests reported by Grantsau (1988) were cup-shaped structures on forks or branches, of soft plant down, the external wall with mosses and lichens tightly woven with cob webs. Measurements were external height 40 mm, depth 20 mm, external diameter 54 mm and internal diameter 34 mm. He found nests or incubating birds in February, March and June.
Brooding
Until 19 August, the young was brooded several minutes on every visit, for about half (36%-58%) of the day (Fig. 1). On 19 August, brooding periods were shorter than usual (4-13 min, X = 8.9, n = 10; once 26 min with a brief flight off, during wind and rain). On preceding days, brooding was 2-60 min, with peaks of 25 records of 7-11 min and 24 from 17-21 min (X = 14.5 min, n = 77). On 20 August at 17:02 and 17:54 the first two visits without brooding were noted; and brooding was only 9.9% of the afternoon. The next two days, brooding was regular after morning visits but infrequent after 15:00 (about 18% each day). Most brooding was 3-11 min on these two days (n = 30, plus visits of 13, 14, 19, 25 and 25 min; X = 7.9). On 25 August (only checked midday 24 August, with one 11 min brooding in 170 min) the female no longer went on the nest in the evening, and she brooded only 1% of the afternoon. She did not brood at night after 25 August. However, she was brooding 5:54 to 6:06 the morning of 3 Sept., and perhaps brooded the nestling at dawn other days (not checked).
Earlier she went on for the night 17:51-18:08, except 18:15 and 18:13 on 21-22 August when sunset was later. On these two days, unlike 6 earlier ones when we saw her go on, she did not feed the young on her last visit of the day; but she had fed 1-5 min earlier in both cases.
On the nest (Fig. 5a), she at times pecked the outside of the nest (for insects?), wiped her bill on its edge, or scratched her head over the wing. She could preen breast and wings; once she opened her tail as the wind blew. She could stick her tongue out briefly a few times (3x), or yawn. To leave, she looked about before spreading her wings, hovering forward or (a few times) backward. She could stop briefly in nearby trees on approach or departure.
Feedings
Feedings were about every 40-50 min, on average (Fig. 2), but intervals varied greatly. The figure indicates average time away from nest (lower line), average time between arrivals at nest (middle line), and average time between feedings (upper line). On 31 Aug., 186 min elapsed between feedings at 12:33 and 15:39 but only 4 min at 15:55-15:59 on 22 August. With short intervals, the second visit was usually to brood rather than to feed. Fig. 3 shows that feedings (per hour watched at a given hour on several days, for instance between 6 and 7 am) were slightly over 2 per hour at 6-8 am and near 2 per hour at dusk, dropping to near 1 per hour 13:00-16:00 during the warmest hours of the day.
After the female stopped brooding at night, she fed less often after 6 pm (4 vs. 7 visits in 8/8 days after/before 23-24 Aug.). On 30 Aug., her last feeding was 17:15; she fed other days to 17:56 or so. She did feed more after 4 pm (3-6 visits, X = 4.4) 25 Aug. on (X = 3.4, or 2-5 visits, earlier), despite the drop from 6 pm on.
At times, the female waited 3-27 sec on the nest rim before starting to feed, but she usually fed quickly. She fed by regurgitating several times on each visit (Fig. 5b), into the open beak of the young bird. It usually turned its beak backward to feed. She often looked to the left between regurgitations; once she wiped her beak on the nest edge. Three regurgitations per visit (n = 80 of 212) were most frequent, with two as frequent the last full day in the nest (n = 7 each) and more frequent after departure (n = 12 of 23 cases versus 7 cases of 3). Of 19 cases of 6-8 regurgitations, only one (of 7) was recorded after 28 August. Half the 26 cases of 5 regurgitations were after that date, so the young may have been more able to swallow after the 28th. Feedings took 9-80 seconds. Once, after the young left, she hovered while regurgitating twice into its beak. In several cases, she foraged for insects in nearby small trees before feeding young. Once she fed briefly, sat, then fed once while sitting (8:01 on 15 Aug.). The young refused two early feedings on 5 Sept. and one at 11:40 on 29 Aug., indicating that the female could easily have fed another nestling, at least after Oniki removed fly larvae (see below). The female often sat and preened in a nearby tree after she stopped brooding, indicating she was not working hard. She scratched her head over the wing, but once scratched her neck under the wing.
Young
Growth of bill, tarsus and wing (Fig. 4) and in weight (Table 1) were regular, since we removed parasite fly larvae. The sharp claws held on to the nest lining 18 Aug. on. Commonly, the young defecated when removed. The eyes were open 22 Aug., when handled; it was raising the tail to defecate outside the nest. 29 Aug. the pinfeathers were 1 mm; 24 Aug. ones on the back were opening but seemed dull in color. The head was blue and back green by 29 Aug. 26 Aug. on, the upper mandible was getting dark. A buff spot was visible behind the eye by 4 Sept. Occasional movements were visible 22 Aug., though only the bill and top of head were visible (Figs. 5c, d); in one case, the female left the nest because the young was moving after feeding; she returned a few seconds later to sit. Once it moved because of a fly. Preening, mostly in heat 11-16 h, was noted 26 Aug. on. Occasionally it yawned or stuck the tongue out, mostly when hot (Fig. 5c); later, it kept the beak open for long periods, closing it briefly now and then (Fig. 5d). It could champ the beak or turn in the nest. The bill could be raised or not (Figs. 5e, f).
Stretching both wings was first noted 29 Aug., but was infrequent until 4 Sept., the day after a couple of cases of beating wings high in the nest (Figs. 5g, h). Once, on 2 Sept., it beat its wings perched on the nest edge (Fig. 5j) but soon returned to the nest.
Wing-beating sessions were also frequent 4-5 Sept., occasionally just after a feeding (Figs. 5k, l). At 16:54 on the 4th, the young was beating wings on the nest edge (Fig. 5g). Four times the next day the young practiced on the nest rim (almost falling from the outside of the nest once, Fig. 5m), once on a nearby branch, but returned inside the nest. Once it slid up on the nest edge, returning. It gave brief call notes during some sessions on the 5th; at 08:43, it exercised wings while the female hovered over, both vocalizing; soon the female perched on a nearby perch (Figs. 5k, l). On the 4th and 5th, it watched nearby wasps (Figs. 5o, p) or pecked at lichens on the outside of the nest, the latter also recorded 2 Sept.
On 6 Sept., it fluttered wings at 7:00 and 7:01, almost falling out the second time. At 7:03, it flew to a nearby twig (Figs. 5q, r, s). The female returned to the empty nest 7:11, pecked inside, then hovered chipping nervously; when the young called, she flew to it and fed it, almost knocking it pendent on the perch (Fig. 5t). Later feedings were less agitated, the young often turning along the twig to be fed (Figs. 5, u, v, w). 8:11 it fluttered, then 8:13 flew to another twig, and 8:26 to a third one.
It was still preening and scratching neck or head over the wing frequently, or stretching the wings; and it practised fluttering without leaving the perch repeatedly in the morning. After noon, short flights replaced most of the fluttering or preening sessions; but it was a windy day, which may have reduced overheating. It pecked nearby leaves twice near mid-day, perhaps after small insects. The young was left alone after a feeding at 17:58. It was not on that branch at 7:00 on 7 Sept., and 7:25 on it was being fed 7 m up in a nearby tree. By 11:20 it was 10.5 m in another tree, still fed occasionally (3 times by 8 am, 3 more by 11:20).
The young brought by Forest Police fed well on sugar water, spiders and flies captured around the house. Although well feathered and with tail half the adult size, it did not preen actively, became flat chested, and did not survive.
Interactions with other birds
The female sometimes fled the nest when students passed or raised her head when a student or bicyclist passed. Other birds in or below the nest tree or nearby trees could be attacked (12 records Mimus saturninus, 7 Columbina talpacoti, 6 Machetornis rixosus; 5 each Crotophaga ani, Zonotrichia capensis, Molothrus bonariensis; 4 Pitangus sulphuratus; 2 each Elaenia flavogaster, Cyanocorax cristatellus, Thraupis sayaca; once Gampsonyx swainsoni (when it flew), Colaptes campestris, Furnarius rufus, Satrapa icterophrys, Pyrocephalus rubinus, Tyrannus melancholicus). Twice she attacked a Polystes wasp near the nest. The female off the nest was alert or gave “tik” notes toward Buteo magnirostris, Guira guira (4 times), Pitangus (3), Tyrannus (1), and Cyanocorax (1), or to dogs and humans. Often the object of her “tik” notes was not evident, or several other birds were in trees near the nest tree.
Chases of other Eupetomena were frequent, some probably of a juvenile or two in the area: there were 47 cases plus 6 of 3-bird chases. One to 4 Eupetomena could “tik” in the area in the evening, especially when the nestling was older. Eleven cases of hovering over or in front of a sitting bird, possibly courtship, were also noted. It was not possible to verify activity, normally; the female may not even have been involved in several cases. Hovering courtship was 7-11 and 15-18:15 h, chases mostly at the same hours (the latter especially common at dusk, after 18 h).
Attacks on larger birds were never after 18 h, but were unusually common (18 cases) 17-18 h; they were fairly common 10-17 h too, less common early in the day. Several late-day cases were related to swarming termites, attracting many birds. Other cases involved C. talpacoti pairs starting to roost in the nest tree, which the female Eupetomena never allowed (Fig. 5n), perhaps because they could attract owls or other predators. Another reason for interactions with other species could be that the small nest tree and nearby trees were at the edge of a large grassy lawn and several breeding species were collecting sticks for nests (Columbina talpacoti, Columba picazuro) or food for nestlings (Machetornis rixosus, Mimus saturninus). M. saturninus and C. picazuro nests were in trees we could watch from our observation position, while activity of adults was watched as well.
Parasites
On 15 August at 08:28, the female was itchy and scratched the head over the wing with the right foot. This kind of preening, while sitting on the nest, was also observed on 17 Aug. (09:23, 10:44). At 11:49, the female made movements like she was feeding the young, turned about and pecked inside the nest several times as if catching something. As the nestling grew, it was difficult for her to clean inside the nest but she pecked inside sometimes after feeding while standing on the nest rim.
On 15 Aug., the young was weighed and handled for the first time. Oniki collected 8 larvae of Diptera flies (Philornis sp.): one large on the belly, one medium on the back and six small ones scattered on the body (see Table 1). The differences in size and Table 1 confirm repeated infestation observed by Oniki (1983) in other species. Later, other larvae were removed, for a total of 58. The total mass of larvae removed was over 6.9 gms, equal to the mass of a young bird 8-9 days old. When weighed with larvae, the young was heavier than after removal (Table 1).
The entrance wound of the larva was different from ones observed in Passeriformes: a dot in the center with the surrounding skin encircling it, looking like a “flower”. Larvae considered large enough to pupate were removed with a forceps and placed in a jar with wet sand and covered with cloth (Oniki, 1983). Eclosion of pupae was 9-12 days after larvae were placed in the jar (4 cases). After removal of the larva, scars healed well but when the larva was large a small dot of dried blood could remain at the entrance hole, dropping in a few days.
The feces ejected by young, glued to surrounding leaves, attracted adult Diptera: 22 Aug., 16:30, one fly seen; also at 16:56, when it walked inside the nest rather than flee when Oniki tried to catch it; 24 Aug., 1 adult collected; 27 Aug., 11:22 and 15:10, 1 fly collected at each hour: 31 Aug., 10:34 (1 fly seen); 5 Sept., 10:57 (2 flies seen) and 12:41 (1 fly seen). Adult flies were not detected before 10:30 am.
DISCUSSION
Nesting of this open-area species includes the winter months, perhaps because the nest is somewhat exposed and heated by the sun. Midday and afternoon heat seemed to reduce brooding time and feeding by the female, but did bother the young as it got older ¾ beak opening, preening and stretching wings, turning on the nest.
Lack of brooding after the first week or so, plus lack of brooding at night, is common in hummingbirds and may be necessary because of the small nest. When there are two young, there is little room for the female to brood. Even here, with one young, it occupied much of the nest interior after 10 days. It may be that young have to grow feathers rapidly to become endothermic early, due to small nests. These are probably necessary to avoid predation.
The extreme botfly parasitism here probably would have killed the young if Oniki had not collected the larvae.
Their total weight, at collection, was that of another young bird. These flies attack mostly at forest edges (Oniki, 1983), and may be especially dangerous at edges of towns. However, Eupetomena seems common in suburban zones, and sometimes fledges young. Possibly, flies are less common far from the forest edges about 1 km east of the present site.
Attacks on local birds were mostly of noncompetitors. Avoiding possible predator attraction is the most probable reason, notably in attacking ground-doves that started to roost in the nest tree.
Acknowledgments — We appreciate the help of students A. Z. Antunes, V. M. Borges, E. L. Gomes, R. Paiva Sobrinho, and C. C. C. Ruivo, learning how to study nests. G. A. Bencke showed us the nest. Oniki appreciates a fellowship from CNPq (Conselho Nacional de Pesquisa e Desenvolvimento Tecnólogico) while she was associate researcher at the Zoology Department (UNESP). Publication n. 13 of the Institute for Studies of Nature.
REFERENCES
ERICKSON, H. T. & MUMFORD, R. E., 1976, Notes on birds of the Viçosa, Brazil region. Dept. Forest. and Nat. Resources. Agric. Exp. Sta., Purdue Univ., Bull., (131): 1-29.
GRANTSAU, R., 1988, Os beija-flores do Brasil. Expressão e Cultura, Rio de Janeiro.
MEYER DE SCHAUENSEE, R., 1970, A guide to the birds of South America. Wynnewood, Pennsylvania, 470p.
ONIKI, Y., 1983, Notes on fly (Muscidae) parasitism of nestlings of South American birds. Gerfaut, 73: 281-286.
ONIKI, Y., 1996, Band sizes of south-eastern Brazilian hummingbirds. J. Field Ornithol., 67(3): 387-391.
RUSCHI, A., 1986, Aves do Brasil. Vols. 4 e 5. Expressão e Cultura, Rio de Janeiro, 482p.
SNETHLAGE, H., 1928, Meine Reise durch Nordostbrasilien. III. Bausteine zur Biologie der angetroffenen Arten. J. Ornithol., 76: 668-738.
November 15th, 2006
glycob.oxfordjournals.org
Dietmar Gundacker, Sally P. Leys2, Heinz C. Schröder, Isabel M. Müller and Werner E.G. Müller1
Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Universität, Duesbergweg 6, D-55099 Mainz, Germany, and 2Department of Biology, University of Victoria, British Columbia V8W 3N5, Canada
Received on April 25, 2000; revised on July 20, 2000; accepted on September 12, 2000.
Abstract
Among the sponges (Porifera), the oldest group of metazoans in phylogenetic terms, the Hexactinellida is considered to have diverged earliest from the two other sponge classes, the Demospongiae and Calcarea. The Hexactinellida are unusual among all Metazoa in possessing mostly syncytial rather than cellular tissues. Here we describe the purification of a cell adhesion molecule with a size of 34 kDa (in its native form; 24 kDa after deglycosylation) from the hexactinellid sponge Aphrocallistes vastus. This adhesion molecule was previously found to agglutinate preserved cells and membranes in a non–species-specific manner (Müller, W. E. G., Zahn, R. K, Conrad, J., Kurelec, B., and Uhlenbruck, G. [1984] Cell adhesion molecules in the haxactinellid Aphrocallistes vastus: species-unspecific aggregationfactor. Differentiation, 26, 30–35). The fact that the aggregation process required Ca2+ and was inhibited by bird’s nest glycoprotein and D-galactose but not by D-mannose or N-acetyl-D-galactosamine suggests that this cell adhesion molecule is a C-type lectin. To test this assumption, two highly similar C-type lectins were cloned from A.vastus. The deduced polypeptides of the two cDNA species isolated classified these molecules as C-type lectins. The calculated Mr of the 191 aa long sequences were 22,022 and 22,064, respectively. The C-type lectins showed highest similarity to C-type lectins (type-II membrane proteins) from higher metazoan phyla; these molecules are absent in non-Metazoa. The two sponge C-type lectins contain the conserved domains known from other C-type lectins (e.g., disulfide bonds, the amino acids known to be involved in Ca2+-binding, as well as the amino acids involved in the specificity of binding to D-galactose) and a hydrophobic N-terminal region. The N-terminal part of the purified C-type lectin was identical with the corresponding region of the deduced polypeptide from the cDNA. It is proposed that the A.vastus lectins might bind to the cell membrane by their hydrophobic segment and might interact with carbohydrate units on the surface of the other cells/syncytia.
Key words: sponges/Hexactinellida/Aphrocallistes vastus/aggregation factor/lectin/C-type lectin/evolution/cell adhesion
Introduction
Multicellularity has arisen several times in evolution and in all major kingdoms (prokaryotes, plants, fungi, and animals; Schopf, 1993). It is generally agreed that multicellular plants, the red algae, the brown algae, the land plants and the fungi arose separately from unicellular ancestors (Devereux et al., 1990; Kirk, 1997). Molecular (Müller, 1995) and morphological (Müller, 1997; Wimmer et al., 1999) data indicate that the transition from the Protozoa to the Metazoa occurred only once in evolution. Sequence data from a variety of proteins involved in cell–cell interactions indicate that all animals, including sponges, are of monophyletic origin (Müller, 1995).
The phylum Porifera, the oldest group of multicellular animals, includes three classes: the Demospongiae, the Calcarea, and the Hexactinellida. The Hexactinellida differ substantially from the other two sponge classes in having largely syncytial tissues (Reiswig, 1979; Mackie and Singla, 1983; Leys, 1995, 1999). The majority (75%) of the sponge constitutes a multinucleated syncytium; the remaining portions of the sponge function independently as cells but are still connected to the whole by open or plugged cytoplasmic bridges (Leys, 1999). Knowledge of hexactinellid embryology is still very limited, as for the most part these sponges inhabit deep waters accessible only by submersible or dredge. Early descriptions of hexactinellid embryos obtained from dredged specimens (Ijima, 1901; Okada, 1928) and an examination of embryos from a population of hexactinellids recently discovered (Boury-Esnault et al., 1999) suggest that the embryo is “cellular” but that the larva is clearly syncytial. How the syncytial tissue arises remains unclear.
Two alternative hypotheses have been proposed to explain relationships between the major sponge classes. One suggests that the Demospongiae are more closely related to Hexactinellida based on presumed larval similarities (Böger, 1988). The other divides the Porifera into the adelphotaxa of the Hexactinellida and the Demospongiae/Calcarea based on the gross difference in tissue structure (Reiswig and Mackie, 1983; Leys, 1999). Recent molecular evidence supports the latter view (Koziol et al., 1997; Kruse et al., 1998; Skorokhod et al., 1999) suggesting that Calcarea are most closely related to other diploblasts and form a clade with the Demospongiae. The Hexactinellida are thought to have diverged first from a common ancestor of the Metazoa (Müller et al., 1998; Müller and Müller, 1999).
There is now a wealth of cellular and molecular evidence to suggest that the Demospongiae have many of the features characteristic of much evolutionarily younger metazoan taxa (e.g., the receptor tyrosine kinases (Müller and Schäcke, 1996), integrins (Pancer et al., 1997; Wimmer et al., 1999), collagen (Exposito et al., 1991), and the metabotropic glutamate/GABA-like receptor (Perovic et al., 1999)).
The role of the aggregation factor (AF) in sponges has been studied in detail (reviewed in Müller, 1982, and Fernàndez-Busquets and Burger, 1999). The AF isolated from demosponges has been shown to function in a species-specific manner (Moscona, 1968; Müller et al., 1979a). Furthermore, in the Demospongiae a lectin belonging to the S-type lectins (Pfeifer et al., 1993) has been found to be involved in a species-specific aggregation complex (Wagner-Hülsmann et al., 1996). A similar “factor” isolated from the hexactinellid Aphrocallistes vastus aggregated cells in the presence of Ca2+ non-species-specifically (Müller et al., 1984). The preparation contained several fractions with one dominant protein species of 34,000 kDa. Sugar analysis revealed that the A. vastus AF was a glycoprotein consisting of 55% (w/w) protein, 40% neutral carbohydrate and 2% hexuronic acid (Müller et al., 1984). The experiments also showed that the A. vastus AF “agglutinated” the cells by interacting in a homo- or heterophilic manner of the second order.
Until now no cell adhesion molecules have been cloned from hexactinellid sponges. However, the syncytial nature of hexactinellid tissue, namely, its ability to fuse to form a syncytium after dissociation through fine mesh, and the evidence that hexactinellid sponges may have been the earliest multicellular animals to have evolved on earth, suggest that a study of cell adhesion molecules in hexactinellid sponges may reveal new mechanisms of cell–cell recognition within the Metazoa.
In the present study, the previously isolated AF was purified and shown to have a size of 34 kDa (24 kDa after deglycosylation). The factor caused aggregation in the presence of Ca2+ and this function was inhibited by D-galactose. These properties—Ca2+-dependency and sugar specificity—suggest that the previously termed AF is in fact a Ca2+-dependent lectin. To test this assumption, two highly similar Ca2+-dependent lectins (C-type lectin) have been cloned from A.vastus. Phylogenetic analysis revealed that the cloned putative C-type lectin represents the oldest (phylogenetic) member of this class within the Metazoa.
The sequences reported here are deposited in the EMBL/GenBank data base under the accession no. AJ276450 (APHRLECC1) and AJ276451 (APHRLECC2) as Aphrocallistes vastus C-type lectins.
Results
Aggregation-promoting activity of an extract from A.vastus
It was previously found that the partially enriched fraction of the A.vastus extract (formerly termed AF) caused aggregation of preserved cells and syncytia at Ca2+ concentrations greater than 1 mM (Müller et al., 1984). By applying the enrichment procedure described previously, aggregates larger than 500 µm diameter (Figure 1B,C) were obtained from single cells/membranes (Figure 1A). The size of the aggregates increased with increasing concentration of the extract: at 5 units of extract the diameter of aggregates was approximately 500 µm (Figure 1B); at 20 units of extract they were larger than 4 mm (Figure 1 C).
PAGE revealed several protein bands in the fraction described previously by Müller et al. (1984). In order to select an affinity resin suitable for final purification of the extract, inhibition was performed using bird’s nest glycoprotein, which was found to potently inhibit extract-mediated aggregation. If 5 µg/ml of this glycoprotein was added together with the purified extract (Fraction V, Table I; see Materials and methods) the size of the aggregates was greatly reduced (Figure 1D). Consequently this glycoprotein was used for further purification (see below). Other carbohydrates were tested for their inhibition potential; neither D-mannose nor N-acetyl-D-galactosamine (5 mM) had any effect on aggregation of A.vastus syncytia/cells, while D-galactose significantly inhibited cell–cell interactions at a concentration of >0.1 mM. In one series of experiments, the cells/membranes were pretreated with -galactosidase as described in Materials and methods. Addition of lectin to these galactosidase-pretreated cells/membranes reduced the aggregation-promoting activity of the lectin (data not shown). All cell agglutination studies were performed in ASW containing 10 mM of CaCl2.
Purification of the extract
In a previous study it was shown that the extract from A.vastus can be highly enriched by the following steps (Fractions): (1) crude extract preparation, (2) Ca2+ precipitation, (3) Biogel P300 gel filtration, (4) sucrose gradient centrifugation, and (5) CsCl gradient centrifugation (Müller et al., 1984; Table I , Fractions I–V). By applying this procedure an increase in the specific activity (units/mg protein) from 18 (crude extract; Fraction I) to 690 (CsCl gradient centrifugation; Fraction VI) was achieved. It is interesting to note that purification with CaCl2 (Fraction II) resulted in a more than 10-fold enrichment (Table I), which contained three major protein species with sizes of 130, 81, and 34 kDa, as shown by PAGE analysis (Figure 2A).
For further purification, Fraction V was loaded onto the affinity column (bird’s nest glycoprotein-Sepharose 4B), which had been equilibrated with Ca2+-containing ASW, and the purified extract was eluted from the column using CMFSW-E. This procedure increased the specific activity from 690 to 1230 (units/mg); Table I. After this purification step only a single protein band with a size of 34 kDa was detected (Figure 2B, lane a).
Our earlier study (Müller et al., 1984) showed that the A. vastus extract contained a high percentage of neutral carbohydrates. As other C-type lectins are known to contain N-glycosylated side chains (Arai et al., 1998), the purified A. vastus lectin was incubated with endoglycosidase H to remove oligosaccharide side chains. Two protocols for the digestion were used: the first without pretreatment of the lectin with 1 M NaCl and bird’s nest glycoprotein and the second after inclusion of these two components as described in Materials and methods. Without the preincubation step PAGE analysis of the extract revealed a band of 24 kDa in addition to the 34 kDa band (Figure 2B, lane c). This result already suggests that the purified extract from A. vastus is a glycoprotein possessing at least one 10 kDa carbohydrate side chain. However, an analysis of the deduced polypeptide sequence of the cDNA encoding the A.vastus lectin revealed only one N-glycosylation site. Complete deglycosylation with this endoglycosidase was achieved after preincubation of the lectin sample at higher ionic strength (1 M NaCl) in the presence of bird’s nest glycoprotein. The rational was to allow the endoglycosidase to reach all potential cleaving sites of the lectin. Again the digested sample was analyzed by PAGE; the data show that under those conditions the size of the lectin dropped from 34 kDa (Figure 2C, lane a) to 24 kDa (lane b), suggesting that the lectin was completely hydrolyzed. The glycosidase itself has a Mr of 29,000 (Trimble and Maley, 1984), which could not be identified on the gel by staining with Coomassie brilliant blue (Figure 2 B, lane b).
The final purified extract (Fraction VI) caused strong aggregation-promoting activity of A. vastus syncytia and cells. In the presence of 5 units or 20 units of A. vastus extract, the sizes of the aggregates were almost identical to those observed after incubation of the cells with Fraction V. In addition, after complete deglycosylation of the lectin, no aggregation-promoting activity of the lectin could be detected in assays with A. vastus syncytia/cells (data not shown).
Cloning of cDNA encoding the A. vastus C-type lectin
A degenerate primer, designed against a conserved pattern within the large conserved disulfide bond terminal of Hydra C-type lectin was used to screen an A. vastus cDNA library. Two different clones were obtained and termed APHRLECC1 (size 899 nt) and APHRLECC2 (814 nt). The potential open reading frames of both start with the Met residue, found between nt134 to nt136 (APHRLECC1)and nt49 to nt51 (APHRLECC2). Northern blot analysis performed with the sponge APHRLECC1 clone as a probe yielded one broad band of 1.0 kb, confirming that full length cDNA was isolated (data not shown).
Analysis of the deduced polypeptides of the C-type lectins
The protein sequences deduced from the cDNA clones APHRLECC1 (LECC1_APHR) and APHRLECC2 (LECC2_APHR) are both 191 aa in length (Figure 3 B). The calculated molecular weight for LECC1_APHR is 22,022, and 22,064 for LECC2_APHR. In the alignment shown (Figure 3B) these two sponge sequences were compared with the protein sequence for C-type lectin from chicken (Bezouska et al., 1991). The N-terminus of the purified A. vastus lectin was sequenced; and the first 11 aa, ALLILIGGLAM, were found to be identical with the aa moieties, aa3 to aa13, in the polypeptide deduced from the cDNA.
The two sponge C-type lectins comprise the most conserved domain which was first characterized in some animal lectins and which seems to function as a calcium-dependent carbohydrate-recognition domain (Drickamer, 1993). This domain is known as the C-type lectin domain (CTL) or as the carbohydrate-recognition domain that comprises 130 residues (PC/GENE-Prosite, 1995); Figure 3B. There are four Cys residues that are perfectly conserved, and which are involved in two disulfide bonds (Drickamer, 1988, 1993). They are found in the A.vastus lectins at aa94 and aa185 forming the long-range disulfide bond, and at aa162 and aa177, which putatively form the internal disulfide bond (Figure 3B). The C-type lectin consensus pattern—C-[LIVMFATG]-x(5,12)-[WL]-x-[DNS]-x(2)-C-x(5,6)-[FYWLIVSTA]-[LIVAT]-C (the residues found in the A.vastus lectins are underlined)—is found between aa162 and aa185 (Figure 3B; PC/GENE-Prosite, 1995). This pattern encompasses three Cys residues that are involved in disulfide bond formation. In addition to the two conserved disulfide bonds, another disulfide bond is present in some C-type lectins, which spans aa69 to aa78 in the A.vastus lectins.
The amino acids involved in the Ca2+ -binding of C-type lectins have been identified by Weis et al. (1991) and are marked in Figure 3 B. It is noteworthy that there is an N-glycosylation site at Asn51 (Figure 3 B). Furthermore, the N-terminal end of the A. vastus lectins shows one putative transmembrane segment, as calculated by the method described by Kyte and Doolittle (1982), that ranges from aa2 to aa17 (Figure 3A,B).
Some predictions about the potential carbohydrate binding site of C-type lectins comes from crystal structure analysis and mutagenicity experiments (Weis et al., 1991; reviewed in Hansen and Holmskov, 1998), using the rat mannose-binding lectin A (Drickamer et al., 1986). If the CTL-domain contains a Glu residue at aa185 and Asn at aa187, the C-type lectin preferentially binds mannose/glucose. However, if aa185 has Gln and aa187 an Asp then the lectin becomes galactose specific (Hansen and Holmskov, 1998). In the A. vastus C-type lectins those positions are occupied by Gln (aa153) and Asp (aa155), which suggests they have galactose specificity. Interestingly, the purified sponge extract cell agglutinating activity is inhibited by galactose and not by mannose.
Phylogenetic analysis of A.vastus C-type lectins
The C-type lectin domain signature has been found in a series of molecules that have been grouped into the following classes based on the location of the functional domains (Drickamer, 1988, 1993): (1) the type-II membrane proteins where the CTL domain is located at the C-terminal extremity of the proteins—these include the asialoglycoprotein receptors (known as hepatic lectins; Spiess, 1990) and the Kupffer cell receptor (Hoyle and Hill, 1988); (2) proteins that consist of an N-terminal collagenous domain followed by a CTL-domain (Weis et al., 1991)—these proteins are also called collectins; (3) the cell adhesion molecules “selectins” (Lasky, 1991); (4) type-I membrane proteins, for example, the 180 kDa secretory phospholipase A2 receptor (Lambeau et al., 1994); and (5) some invertebrate soluble galactose-binding lectins, for example, echinoidin (Giga et al., 1987), a lectin from the coelomic fluid of a sea urchin, as well as BRA-2 and BRA-3, two lectins from the coelomic fluid of a barnacle.
A databank search with the two deduced hexactinellid C-type lectins, LECC1_APHR and LECC2_APHR, revealed highest identity (similarity) to the C-type lectin from chicken (hepatic lectin; Bezouska et al., 1991). The sponge sequences share 18% identical and 33% similar aa with this lectin. Since this lectin has the same overall structure with respect to the CTL domain, the sponge lectins might be grouped with the type-II membrane proteins.
A phylogenetic analysis of the two sponge C-type lectins was performed with the most closely related sequences listed in the databanks. A radial unrooted phylogenetic tree revealed that the A. vastus lectins group in the same branch as the mouse and human C-type lectins (type-II membrane proteins; Richard and Beaulieu, 1998; Bates et al., 1999; Figure 4A). However, as the significance of the branching order is low, as seen from the low bootstrap values, the tree was rooted (operatively) using the Geodia cydonium S-type lectin (Wagner-Hülsmann et al., 1996) as an outgroup; Figure 4B. The resulting tree suggests that the A. vastus C-type lectins diverged first from a common ancestor, while the type-II membrane lectins from the sea urchin (Giga et al., 1987) and the Kupffer cells receptor (Hoyle and Hill, 1988) are the next most closely related molecules.
November 14th, 2006
medscape.com
J Allergy Clin Immunol. 2001; 107(6):1082-7 (ISSN: 0091-6749)
Goh DL; Chua KY; Chew FT; Liang RC; Seow TK; Ou KL; Yi FC; Lee BW
Department of Paediatrics, National University of Singapore, 5 Lower Kent Ridge Road, S(119074)Singapore.
BACKGROUND: We have previously described anaphylaxis induced by edible bird’s nest (BN) and demonstrated that this condition is IgE mediated. OBJECTIVES: This study aimed at describing the immunochemical properties of the BN allergens. Comparative studies between 3 commercially available sources (according to the country of origin) of BN were also made. METHODS: Crude extracts of commercially available processed BN from Sarawak (Malaysia), Thailand, and Indonesia and fresh unprocessed BN from the caves of Sarawak were obtained by means of aqueous extraction. Specific IgE toward these sources were determined by using fluorescence allergosorbent tests (FASTs). Cross-reactivity studies between the 3 sources of commercially available processed BN were carried out by means of FAST inhibition. Immunochemical characterization by means of IgE immunoblot, periodate treatment, and heat stability studies were carried out on fresh unprocessed BN from Sarawak. RESULTS: Serum from allergic patients showed differences in IgE binding to the 3 sources of commercially available BN, with the highest levels of specific IgE recorded with the Sarawak source (P <.0001). Of these, only the Sarawak and Thailand sources showed considerable cross-reactivity. Further work on the unprocessed fresh Sarawak source identified a putative 66-kd major allergen containing several isoforms. Periodate treatment resulted in loss of IgE binding. Despite a progressive decline in the molecular weights of allergens on SDS-PAGE with increasing periods of boiling, IgE binding, as assessed by means of FAST, was not affected. N-terminal sequence of the major putative allergen (66 kd) showed homology to a domain of an ovoinhibitor precursor in chicken (SWISS-PROT accession No. P10184). CONCLUSIONS: We have described the immunochemical properties of BN allergens. Edible BN from different sources are allergenically dissimilar. The putative major allergen is a 66-kd protein.
November 13th, 2006
imperialnest.com
Edible bird’s nest is well known and popular amongst Asian consumers, especially Chinese, Japanese and Vietnamese for century. Many Asian people who live in Europe, USA, Canada, Australia have earned a good living with good incomes. They could afford to pay for high price Bird’s Nest.
Swiftlet Feeding Seminar will be held in Bangkok in August in order to exchange their experiences of Bird’s nest housing farms (mostly the gulf provinces of Southern and Eastern parts of Thailand). Other main topic is to discuss of the possibilities of set up the grading standard of Bird’s Nest. There is still no any association of this business yet. The key person who has strong will in setting up the stable base on this trade, Mr. Waratheb Choom said, he would like to see the prosperous and stable bird’s nest farming in Thailand, we are very behind Indonesia in this business in terms of marketing and technologies.
November 10th, 2006
aikoediblebirdnest.com
A few species of swift, namely cave swifts, are renowned for building the nests used to produce the soup’s unique texture. Such edible bird’s nests are among the most expensive animal products consumed by humans. The nests have been traditionally consumed in China for over four-hundred years.
The most heavily harvested nests are from the Whit-nest swiftlet (Aerodramus fuciphogus ) and the Black nest swiftlet (Aerodramus maximus) (Gausset, 2004). The white nests and the “red blood” nests are supposedly rich in nutrients which are traditionally believed to provide health benefits, such as aiding digestion, raising libido, improving the voice, alleviating asthma, increasing conccentration, and an overall benefit to the immune system. However, Many researchers has study nutrients value of Edible bird’s nest as following.
Sources:
http://www.pubmed.gov
Articles
Edible bird’s nest extract inhibits influenza virus infection.
Edible bird’s nest (EBN) is the nest of the swift that is made from is saliva. Although EBN has been widely used for enhancing immunocompetence, its antiviral efficacy has not been studied in detail. We found that EBN extract could strongly inhibit infection with influenza virused in a host range-independent manner when it was hydrolyzed with Pancreatin F. Western blotting assay showed that the EBN extract bound to influenza virus. Furthermore, EBN extract could neutralize the infection of MDCK cells with influenza viruses and inhibit hemagglutination of influenza viruses to erythrocytes but it could not inhibit the activity of influenza virus sialidase. Fluorometric HPLC indicated that the major molecular species of sialic acid in EBN is N-acetylneuraminic acid. The results suggest that EBN is a safe and valid natural source for the prevention of influenza viruses.
PMID: 16581142 [PubMed - as supplied by publisher]
Researchers:
Guo CT, Takahashi T,
Bukawa W,
Takahashi N, Yagi H,
Kato K,
Hidari KI,
Miyamoto D,
Suzuki Y.
http://www.pubmed.gov
Articles
Purification and chemical study of a Collocalia glycoprotein.
A glycoprotein was purified from the aqueous extract of “edible bird’s nest” (Collocallia) using free flow preparative electrophoresis and represented the main fraction of Collocalia glycoproteins. This glycoprotein is homogeneous upon agarose electrophoresis and slightly polydisperse upon ultracentrifugation (S So 20w = 3,0). The carbohydrate moiety contains galactose, mannose, glucosamine, galactosamine and sialic acid, which is completely released by Clostridium Perfringens or Diplococcus pneumoniae neuraminidases and has the same chromatographic behaviour as N-acetyl-neuraminic acid. The peptide part of the glycoprotein is rich in serine, threonine and proline. About 40 p. cent of the hydroxyaminoacids are involved in carbohydrate-peptide linkages.
PMID: 1182216 [PubMed - indexed for MEDLINE]
Researchers:
Houdret N, Lhermitte M, Degand P, Roussel P.
November 9th, 2006
The Mercury (subscription), South Africa - Oct 25, 2006
October 25, 2006 Edition 1
At last people are talking sense about the plight of the barn swallows at the Mount Moreland roosts (The Mercury October 19).
In the past even some ornithologists have been heard to say that the swallows don’t matter, but put in the context that the roost accommodates at least 13% of the known population makes the threat to the roost, if Dube Tradeport goes ahead, an international crisis.
I have been monitoring the swallows since 1992. There are two roost sites at Mount Moreland, one on each side of the village. The mitigation for phase one of the tradeport was that the majority of any storm water run-off would go through the smaller wetland, but nobody from the Institute of Natural Resources, who are meant to be doing the EIA, had checked whether any swallows roost there. They do.
I think the estimate of three million birds could be very low. We know that between 700 000 and two million birds come in to roost on any one night (and that does not include the birds on the other side of the village). What we don’t know is how many of these are resident or just passing through.
My hypothesis is that the roost is more a “motel” than a residential hotel. If my thoughts are correct, and I base them on the fact that the numbers each night vary greatly, then the actual number passing through the roosts each year could be 10 times higher than the three million suggested.
With regard to air strikes, I don’t think that 18gm of barn swallow, even if consumed in large numbers, is going to have much effect on a modern jet engine which is designed to withstand much larger birds.
November 8th, 2006
Saturday, October 28, 2006
Republican American - Oct 28 2:16 AM
Copyright © 2006 Republican-American
Tree swallows were streaming by at a brisk pace. I estimated more than 4,000 over the first few hours after dawn on Monday, clearing out of New England on a brisk northwest wind.
My primary task was counting migrant hawks at Lighthouse Point in New Haven, and there were plenty of them, too. The day’s tally topped 600.
I wasn’t watching the swallows too closely, since at this time of year every one was likely to be a tree swallow. But I happened to be looking in the right place at the right time when one of Connecticut’s most interesting bird stories flashed before my eyes.
The light was just right and the binoculars in the right position to get a quick but good look at a single cave swallow with all those tree swallows.
Less than 30 years ago, the cave swallow was unknown in Connecticut and almost non-existent north of Mexico or the Caribbean. If you wanted to see one you had to go to Carlsbad Caverns in New Mexico or a few limestone caves in west Texas. They really were cave swallows.
Then something unusual happened. The southwestern race somehow figured out how to exploit man-made culverts as nest sites, and the Texas population exploded. In the 1980s a few cave swallows were seen at Cape May, N.J., and since then a pattern of late fall appearances in the Midwest and Northeast has developed.
Each year now, usually in November, a weather system sweeping from the southwest to the northeast deposits cave swallows around the Great Lakes. From there the next strong cold front sends them hurtling southward.
This mechanism has become so reliable that Connecticut birders can just about predict to the day when a noticeable flight of cave swallows will hit places such as Lighthouse Point or Hammonasset Beach State Park in Madison.
The bird I saw Monday was a little ahead of the curve, but we’ll probably get cave swallow flight sometime between now and the middle of November.
Reach Greg Hanisek at ghanisekrep-am.com
November 7th, 2006
ecologyasia.com
PUTRAJAYA: Swiftlet nests, reportedly reaping RM1.5mil a month, will not be allowed to be cultivated in housing as well as in public and recreational areas under guidelines issued by the Government yesterday.
The guidelines, however, are only applicable to birdhouse operators in the peninsula.
“Sabah and Sarawak have their own state provisions governing the industry and their bird nests are harvested from the wild,” said Science, Technology and Environment Minister Datuk Seri Law Hieng Ding.
Birdhouses must only be built on agricultural land or in light industrial areas and the use of loudspeakers to lure the birds is also prohibited, according to the new Guidelines on Swiftlets’ Nest Industry.
Law said the guidelines was to ensure the farming and collection of edible swiftlets’ nests from buildings do not become a nuisance and a health hazard.
“It is also to ensure that the collection and farming do not jeopardise or reduce the species’ population,’” he told reporters after launching the guidelines at his office here.
Law said the guidelines were, however, voluntary in nature. But the authorities could still act against errant operators because the swiftlets, of the white nest and black nest species, were protected under the Wildlife Protection Act.
“The industry is also subjected to the Uniform Building Bylaws 1986, the Destruction of Disease Bearing Insects Act 1975 and Health Department regulations.
“Birdhouse operators must get premise licence from their local authorities, a collection of birds nest license and a trading of birds nest license from the Department of Wildlife and National Parks,” he said.
Malaysia Bird’s Nests Merchants Association president John Chen said: ”Our production is around 200kg to 300kg per month.”
November 6th, 2006
ncbi.nlm.nih.gov
Ng MH,
Chan KH,
Kong YC.
The edible bird’s nest extract from Collocalia spp. was found to contain a glycoprotein which could potentiate mitogenic response of human peripheral blood monocytes to stimulation with Concanavalin A or Phytohemagglutinin A. The potentiating effect of the extract was most marked at suboptimal mitogenic concentrations of these lectins, decreasing the 50% optimal concentration of Con A and PHA by 6- and 2.5- folds respectively. The potentiating effect was exerted early during the first 10 hours following stimulation with Con A. This potentiation activity was not dialysable, but it was stable to limited digestion with trypsin, alkaline pH and extraction with ether.
PMID: 3790144 [PubMed - indexed for MEDLINE]
November 3rd, 2006
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