Manuel Malaquias (back left in blue shirt), Alex Ball (extreme right) and Georges Dussart (addressing the Forum) are to be congratulated on a successful Molluscan Forum, on November 2nd in the Palaeontology Demonstration Room of the Natural History Museum. Abstracts of the 15 talks and 10 posters follow in alphabetical order of first presenter.
of species diversity on resource partitioning in intertidal gastropods
as revealed by stable isotopes
Pallet structure of wood borers of the family Teredinidae (Bivalvia)
Geometric morphometric analysis of geographic variation in four endemic gastropod species from Lake Tanganyika
Species-area relationships in the spring fen mollusc communities
Co-evolution or easy exploitation? Trematode prevalence, diversity and lifecycles in endemic gastropods of Lake Tanganyika, East Africa
Seasonal variation of zebra mussel tolerance to toxins
Achatina fulica: its molecular phylogeny and genetic variations in global populations
Evolutionary history of molluscs from deep-sea chemosynthetic ecosystems
Interaction between environmental factors and life history variables in determining recruitment of the Manila clam
Niche creation for cryptofauna by teredinid bivalves in Mangroves
Taxonomy of the genus Trochulus (Gastropoda: Hygromiidae) in the Czech Republic
Researching Limax maximus: Old literature and new sequences
Land snail distribution patterns within a site: the role of different calcium sources
Towards a phylogeny of Limax (Gastropoda: Stylommatophora)
Sphaerium corneum / nucleus (Bivalvia: Veneroida: Sphaeriidae) is a complex of several cryptic species
Release of reactive oxygen intermediates by Lymnaea stagnalis haemocytes: a pivotal role for Protein Kinase C
Mobility of Bulgarica cana in a natural habitat
The phylogeny of molluscs and their relatives within the Lophotrochozoans
Cryoelectron microscopy and single particle analysis of Nautilus pompilius hemocyanin under different oxygenation states
The molluscan collection of the National Museums Scotland (Royal Museum); significance, value and potential
The land-snail fauna of fragmented Sri Lankan lowland rainforest and village home gardens
Is this a sacoglossan? Computer-based 3D anatomical visualisation of the mesopsammic Platyhedyle denudata Salvini-Plawen, 1973 (Opisthobranchia, Sacoglossa)
Comparative morphology of the Thraciidae
Combining confocal laser scanning microscopy and electron microscopy to investigate the mantle and velar ciliature of larval bivalves
Hemocyanin: an appropriate new marker. Phylogeny of polyplacophorans resolved by hemocyanin genes
Morphological differences between Trochulus hispidus from Bohemia and Moravia.
Ian K. Fontanilla1, Cendrine Hudelot1, Fred Naggs2 and Christopher M Wade1
Genetics, University of Nottingham, Queen’s Medical Centre, Clifton
Boulevard, Nottingham NG7 2UH, UK
2Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
The giant African land snail, Achatina (=Lissachatina) fulica (Bowdich, 1822), is a tropical crop pest species with a widespread distribution across East Africa, the Indo-Pacific and the Caribbean. The phylogenetic position of A. fulica within the Family Achatinidae and Superfamily Achatinoidea was investigated using segments of the nuclear large subunit (LSU) ribosomal (r) RNA, actin and histone 3 genes as well as the mitochondrial 16S rRNA and cytochrome oxidase I genes. Results support the monophyly of the Family Achatinidae as well as the taxonomic designation of A. fulica as Lissachatina fulica in order to distinguish it from the Western and Central Achatina species as proposed by Bequert (1950) and Mead (1995). The extent of genetic diversity in A. fulica populations was also investigated using a molecular marker developed from the 16S rRNA gene. Preliminary results indicate that the snails which spread across the globe were derived from a single haplotype.
The influence of species diversity on resource partitioning in intertidal gastropods as revealed by stable isotopes
G. M. ANDREW1, M. T. BURROWS1, S. J. HAWKINS2 AND R. A. R. MCGILL3
1Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll, PA37 lQA.
2The Laboratory, Citadel Hill, Plymouth, PLl 2PB.
3Scottish Universities Environmental Research Centre, Rankine Avenue, Scottish Enterprise Technology Park, East Kilbride, G75 OQE.
In recent years stable isotope techniques have emerged as powerful tools in trophic ecology. The ratio of 13C to 12C in animal tissue, measured relative to a standard, provides a d13C value which gives information on the sources of organic carbon in the diet of the animal; the d15N value of the tissue provides information on trophic level. This work uses such isotopic 'signatures' to look at how species diversity influences resource partitioning within the guild of intertidal grazing gastropods found on British rocky shores. Intertidal gastropod species diversity varies with latitude, with more diverse assemblages present on southern shores than those in the north. Such natural variations have been used in this study to examine whether sympatric grazers show increased dietary specialisation and niche differentiation under conditions of different diversity.
Species of wood boring bivalves present in Norwegian waters were investigated with the collaboration of Dr Arne Sneli in the Trondheim Biological Station. Six panels of Pinus sylvestris were deployed in Trondheim Fjord for one year, acting as baits to recruit wood borers. Two bivalve species, family Teredinidae, Psiloteredo megotara and Nototeredo norvagica, were identified using the key in Turner (1966). However, discrepancies found in the literature (Turner, 1966; Nair, 1971) posed doubts about the initial identification of the species based on the pallets. The external shape, form and colour of the pallets were different when observed under the light microscope. The pallets thought to belong to Nototeredo norvagica showed an internal segmented structure, viewed with transmitted light, matching Turner's (1966) description of the pallets of this species. On the other hand, pallets which were identified as belonging to Psiloteredo megotara did not show signs of segmentation when viewed under the stereomicroscope. Furthermore, Turner (1966) proposed that Psiloteredo megotara belongs to the evolutionary line of species with non-segmented pallet whereas Nototeredo norvagica belongs to the evolutionary line of segmented pallet. Thus, it was decided to investigate further the internal structure of the two different types of pallets under the scanning electron microscope. Initially, pellets of P. megotara from Norway and N. norvagica from Norway, Croatia and Turkey were cut at the blade level and observed under the SEM. The pallets of N. norvagica from all sites had a similar structure, but the P. megotara pallets had a clearly different structure. Pallets of P. megotara and N. norvagica were embedded in resin and then ground in the transverse plane at intervals of 250 and 500 mm to show cross sections at different levels. After each grinding they were observed under the SEM. The pallets from Norway identified as Psiloteredo megotara showed a different internal structure to the pallets of Nototeredo norvagica but, surprisingly, also showed internal segments surrounded by a solid non-segmented calcareous layer. It seems, therefore, that although the pallets belong to different species, the genera are more closely related than has been thought until now. This finding has implications in the model of the relationship between genera proposed by Turner (1966).
VIVIANE CALLIER1, CATHERINE E. WAGNER2, ELLINOR MICHEL3 AND JONATHAN TODD4
1Department of Biological Sciences, Mount Holyoke College, South Hadley, MA;
2Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY ;
3Department of Zoology and
4Department of Palaeontology, Natural History Museum, London, UK.
Lake Tanganyika is the largest of the East African rift lakes and home to the endemic gastropod genus Lavigeria, a species flock which contains approximately 45 patchily distributed species (Michel and Todd, 2003). We used a detailed landmark-based geometric morphometric approach on four species to examine the following questions:
1. Are geographically separated populations morphologically distinct? If so, what shell features differentiate the populations?
2. Do closely related species exhibit similar patterns of morphological differentiation geographically?
3. Do these species exhibit sexual dimorphism? If so, what differences in shell morphology characterize these groups?
Our results indicate that there are different patterns of morphological variation among these species, despite their sympatric distributions (and thus likely similar ecological pressures). In some species, geographically separate populations of the same species may differ greatly (L. grandis), or subtly (L. nassa). In all species, adult females are on average larger in size than adult males, but dimorphism in shape differs in character between species, with clear differences within L. sp. J and L. sp. W, and only very subtle differences for L. grandis and L. nassa.
We conclude that divergence between populations may be the result of drift or of local adaptation to heterogeneous environments. Geometric morphometrics is a powerful tool for detecting fine-scale morphological differences within and among species.
relationships in the spring fen mollusc communities
Institute of Botany and Zoology, Masaryk University, Kotlárská 2, 611 37 Brno, Czech Republic
We studied species-area relationships at nine Western Carpathian spring fens (differing in mineral richness), sampling a set of three nested quadrats in each site. When considering only live molluscs or all shells, principal differences in the numbers of species as well as individuals were found. Differences were also found among the mineral fen types. In mineral-poor fens, the smallest plot (25 cm2), contained a significantly smaller part of the site's species richness than the. mineral-rich, and tufa forming fens, due to the sites' lower abundances and higher heterogeneity. The species accumulation curve was therefore steep for mineral-poor sites (especially from the 25 cm2 to 50 cm2 plots) and became more shallow towards the mineral-richer fens. However at all sites, regardless of mineral type, the largest plot (75 cm2) plot contained 84% of the site's richness (only 2 species short of the total for the whole site). This demonstrates that the 75 cm2 plot fairly reflects the site's species richness.
or easy exploitation? Trematode prevalence, diversity and lifecycles
in endemic gastropods of Lake Tanganyika, East Africa
SARAH M. COLLINS1, JULIA HOOPER2 AND ELLINOR MICHEL3
1Lewis & Clark College, Portland OR, USA (sara...@gmail.com);
2University of California Santa Barbara, CA, USA;
3Natural History Museum, London, UK.
Lake Tanganyika's ancient age (14 MY) and remarkably diverse array of endemic flora and fauna are reasons to expect numerous co-evolutionary developments among its inhabitants. Interactions between host gastropods and trematode parasites remain relatively unstudied in the lake despite potential impacts on evolution of endemic species, and ecosystem function. In this study, we aimed to relate trematode prevalence and diversity in Lavigeria nassa, a 'thiarid' gastropod commonly found throughout the littoral zone of the lake, to depth, site characteristics, brood size, and shell morphometric variables. We examined approximately 1200 L. nassa at four depths and three sites in the Kigoma, Tanzania area for parasite infection. Smaller samples of Paramelania damoni and Vinundu guillemei were also surveyed. For each gastropod we measured shell height, width, lip thickness, and scarring due to attempted crab predation. Five morphotypes of trematodes were identified. Parasite prevalence and diversity differed across depths and sites. Shell size was also highly variable, but no apparent connection existed between morphometric data and parasite prevalence. Ongoing work aims to correlate reproductive strategy of brooding females with parasite prevalence in the maternal population, and molecular profiling of the parasites is underway.
variation of zebra mussel tolerance to toxins
R. COSTA 1AND G. D. MOGGRIDGE2
1Structured Materials Group, Department of Chemical Engineering, University of Cambridge, UK
2Aquatic Ecology Group, Department of Zoology, University of Cambridge, UK
The zebra mussel, Dreissena polymorpha, is an invasive species whose biofouling activity has major impacts on freshwater-dependent industries. A common approach for controlling this pest is to apply suitable biocides at the end of the breeding season in late autumn. The assumption behind this practice is that adult mussels are more sensitive to toxins after spawning when their condition is at its weakest. However, the tolerance of bivalves to biocides is dictated not only by their body condition, but also by other factors, amongst which is their filtration rate. Both body condition and filtration rate undergo seasonal variation related to the species' reproductive cycle and the annual variation of environmental conditions. The seasonal variations of these two factors tend to have opposing effects on the susceptibility of mussels to biocides. In this study, it is hypothesised that the lowest tolerance of the species to toxicants occurs when an optimal combination of body condition and filtration rate is reached, not necessarily when the former is at its lowest or the latter is at its highest. To test this hypothesis, the tolerance of zebra mussels to three reference toxicants, with distinct modes of action, is being tracked by monthly measurements for one year. Results of this study may have implications for the appropriate timing of control treatments, as well as for the setting of protocols for conducting toxicological studies with the species.
history of molluscs from deep-sea chemosynthetic ecosystems
LUCIANA GENIO1, STEFFEN KIEL1, CRISPIN LITTLE1, JOHN GRAHAME2 AND MARINA RIBIERO CUNHA3
1School of Earth and Environment, University of Leeds, UK
2Faculty of Biological Sciences, University of Leeds, UK
3Centro de Estudos do Ambiente e do Mar, University of Aveiro, Portugal
The bivalve family Mytilidae has representative genera and species in both recent and fossil deep-sea chemosynthetic communities. The phylogenetic relationships among these taxa and their relation to other mytilids are, however, not yet fully resolved. Molecular phylogenetic data suggest that modern mytilid genera from hydrothermal vents, cold seeps, sunken whales, and wood form one monophyletic group, and should be included in the subfamily Bathymodiolinae. This hypothesis remains untested using morphological data.
Our research aims to identify phylogenetic relationships of the Mytilidae using early ontogenetic shells and shell microstructure characters. Different structures may occur in the outer shell, which can be entirely aragonitic or composed of an outer calcitic and inner aragonitic sublayer. Preliminary results indicate that mytilids inhabiting chemosynthetic environments show considerable differences in shell microstructural details, as well as in larval and juvenile shell morphology. Future investigation will evaluate whether those characters can indeed be used for phylogenetic analyses.
|Simple prismatic||Crossed lamellae|
between environmental factors and life history variables in determining
recruitment of the Manila clam
69 Esslemont Road, Southsea, Hants, P04 DES; Matt...@hotmail.com
Ruditapes philippinarium is a bivalve mollusc that has become established far outside its traditional range in South East Asia. A breeding population has become established in Poole harbour. There are also reports of populations in the Thames Estuary and Southampton water. In a recent benthos survey of Langstone harbour Ruditapes was not found, but conditions are similar to Poole harbour. The mud flats offer a potentially suitable environment for Ruditapes to settle. The study's aims are to determine whether Ruditapes could settle in Langstone harbour by investigating its life history strategies. The Poole population will be sampled throughout the year to determine the time of spawning. Subject to clearance, a population will be kept adjacent to the institute of marine sciences to compare cycles with the Poole population. Molecular phylogeny will be used to determine whether the south coast populations are separate from one another.
Teredinids (Family Teredinidae) are an intriguing collection of morphologically and physiologically diverse assortment of animals. The cosmopolitan diversity observed within this family is facilitated by the myriad of various life histories adopted by these animals. The initial stimulus, which facilitates settlement of planktonic teredinid larvae, remains ambiguous. These animals are able to process the available carbon provided by the high abundance of dead woody substratum. However, the burrows facilitated by the vivacious feeding activity of the. teredinids may magnify potential niche creation for mangrove cryptofauna. This research will focus therefore upon the factors responsible for pediveliger settlement, thereby underlining ecologically important questions such as what factors control the settlement and initial penetration of the wood by the larvae. Furthermore this research will also investigate the potential cryptofaunal diversity facilitated by shipworms in mangrove ecosystems, with the intention of highlighting the ecological role of cryptofaunal populations.
of the genus Trochulus (Gastropoda: Hygromiidae) in the Czech
M. HRABAKOVA1, L. JURICKOVÁ1 AND A. PETRUSEK 2
1Department of Zoology, and
2Department of Ecology, Faculty of Science, Charles University, Vinicna 7, 12844 Praha 2, Czech Republic
The genus Trochulus (formerly Trichia) was always considered to be taxonomic ally problematic. Previous research revealed substantial cryptic diversity in this genus in the surroundings of the Alps. Little is known however, about the situation in other Central European regions. Our study focuses on whether the observed morphological differences of populations in the Czech Republic can be explained by the presence of cryptic species, or by intraspecific variation. We analysed 14 populations of two species of the genus - Trochulus plebeius and T. hispidus. Karyotype analysis revealed that all the studied populations have identical number of chromosomes (n = 23) of similar morphology. Sequence analysis of 16S rDNA and COl showed two divergent groups of T. hispidus populations, differing in geographic distribution (north-western versus eastern) but with overlapping morphology. To clarify the status of the two clades, we are conducting breeding experiments to test for potential reproductive isolation.
The research was supported by grant GAUK 183/2005/B-BIO/PrF. Morphological differences between Trochulus hispidus from Bohemia and Moravia.
Limax maximus is a terrestrial slug belonging to the family Limacidae (Mollusca, Gastropoda, Pulmonata). This species is one of the most widespread and morphologically variable species in the genus Limax. In addition, L. maximus has been introduced throughout the world. Before any biological control can be considered, L. maximus needs to be well understood in its natural environment. An important first step in understanding the true identity of this species involves the sourcing, translation and interpretation of old publications, since L. maximus has been described by many early authors. Other important datasets include anatomy, copulation behaviour and molecular data. Preliminary molecular data is based on 613 nucleotides of the mitochondrial gene cytochrome c oxidase subunit I (COI) for specimens from Europe, Australia and America. Current work includes the sequencing of additional specimens and a second gene, the nuclear internal transcribed spacer 2 (ITS2) from the ribosomal gene cluster.
snail distribution patterns within a site: the role of different calcium
LUCIE JURICKOVÁ, MICHAL HORSÁK, ALENA MÍKOVCOVÁ, JAROSLAV C. HLAVÁC AND JAN ROHOVEC
Department of Zoology, Charles University, Prague, Czech Republic
The aim of this study was to analyse whether land snail assemblage patterns reflect gradients of calcium content on a very small scale. We chose two sites differing in their calcium richness and source of the calcium ("Tufa site" and "Boulder site"). We tested the predictive power of different sources of calcium (from topsoil, vegetation and leaf litter). At both sites, the main variability in species composition was explained by the calcium gradient. For the "Tufa site", calcium content was a strong controller of species composition and also species richness, total abundances and abundance of almost all species. At the "Boulder site" only species composition was significantly driven by calcium. Content of calcium carbonate was the best predictor of species composition. No significant correlation was observed for leaf litter calcium. Topsoil pH did not explain the observed clear pattern of land snail composition along the calcium gradient.
|The terrestrial slug genus Limax is distributed mainly in Europe (and introduced worldwide) and includes 20 to 30 currently accepted species, which are usually (often poorly) defined by external morphology and genital characters. A phylogeny is entirely lacking. A molecular dataset has been generated for more than 200 specimens of Limax and other Limacidae based on 613 nucleotides of the mitochondrial gene cytochrome oxidase subunit I (COI). Initial tree reconstructions show that the genus Limax (s. str.) is probably monophlyletic within monophyletic Limacidae. Limax itself splits into multiple groups. Each of these groups contains one or several species already defined by morphological characters, but also several still undescribed taxa. These findings indicate that COl-sequences are mostly suitable for the problem, but also indicate the need for wider biogeographic and taxonomic sampling. Future improvement and confirmation are planned by further taxon sampling and AFLP-fingerprinting.|
corneum / nucleus (Bivalvia: Veneroida: Sphaeriidae) is a
complex of several cryptic species
TEREZA KORÍNKOVÁ1, ADAM PETRUSEK2 AND LUCIE JURICKOVÁ1
1Dept. of Zoology, Charles University, Vinicná 7, 128 00 Praha 2, Czech Republic,
2Dept. of Ecology, Charles University, Vinicná 7, 12800 Praha 2, Czech Republic
Distinction between cryptic species often depends on the different concepts of species adopted by the respective authors. Combinations of different methods and approaches are therefore needed to reach conclusions about the status of similar forms. A good example is Sphaerium nucleus, described by Studer in 1820, regarded as a subspecies of S. corneum for many subsequent decades, and revised and considered a good species by Korniushin in the 1990s.
We analysed a number of populations putatively identified as either S. corneum or S. nucleus from the Czech Republic, comparing anatomy, ecology, karyotypes and sequences of mitochondrial gene for 16S rRNA. Whereas the karyotypes differ only slightly and are difficult to compare because of frequent presence of abnormalities (aneuploidy, additional chromosomes), the different habitat preferences and functional a daptations of the latter species to extreme habitats support its distinctness from the former. The analysis of available sequence data suggests that "S. nucleus" forms more than one clade of the same rank as S. corneum. Thus, the redescription of both species is needed for any potential revision of this complex.
of reactive oxygen intermediates by Lymnaea stagnalis haemocytes:
a pivotal role for Protein Kinase C
AUDREY H. LACCHINI, ANGELA J. DAVIES, DAVID MACKINTOSH AND ANTHONY J. WALKER
School of Life Sciences, Kingston University, Kingston upon Thames, KTl 2EE
In molluscs, Reactive Oxygen Intermediates (ROI), produced by macrophage-like cells called haemocytes, play a major role in innate immune defence and participate in the elimination of pathogens such as parasites. The NADPH oxidase enzyme, responsible for the successive formation of cytotoxic oxidative molecules including hydrogen peroxide (H202), is in part activated by Protein Kinase C (PKC) in mammalian phagocytes (El Benna et a1, 2005). We have reported the existence of PKC-like protein(s) in haemocytes from the freshwater snail L. stagnalis, host for the avian schistosome Trichobilharzia ocellata (Walker and Plows, 2003) and have found that the activity of this signalling enzyme is modulated following challenge with lipopolysaccharide (LPS) and laminarin, a b-1,3-glucan that occurs in fungal cell walls. The purpose of the present study was to investigate the generation of H202 by L. stagnalis haemocytes, and to determine whether or not the molecular mechanisms underlying "the respiratory burst" involve the PKC pathway. Laminarin promoted extracellular H202 output by L. stagnalis haemocytes in a dose and time-dependent manner, with 10 mg/ml laminarin stimulating H2O2 production approximately 9-fold. The PKC inhibitor, GF109203X (10 mM), significantly attenuated laminarin-dependent H2O2 production by 65% (p~0.001); moreover, the NADPH oxidase inhibitor, apocynin (500 mM), reduced stimulated H2O2 levels by 57% (P<0.001). These results demonstrate that PKC is at least in part responsible for the synthesis of ROI by molluscan haemocytes following immunological challenge and is therefore likely to be important in snail anti-parasite responses.
Movements of Bulgarica cana (Held, 1836) (Gastropoda: Pulmonata: Clausiliidae) were observed in its natural habitat in a riparian forest in the valley of a small stream (Romincka Forest, NE Poland). From June to September 2006, 310 individuals of B. cana were individually marked and 57 individuals was re-trapped. Most snails (75% - 43 individuals) stayed on the same tree during the whole investigation period. Only 12 individuals moved to another tree and the distance was approx. between 1 to 5 m (measured from tree to tree). The longest distance was 20 m (made during 1 month). Additionally, for four successive days, movements of B. cana were observed every 12 hours. Snails moved from 10 cm to more than 150 cm within the same tree per day. Some specimens stayed inactive for 2-3 days.
The phylogeny of the Bilaterians and more primitive taxa is partially a still unresolved enigma. To address this question a project called the "Deep Metazoan Phylogeny project" was initiated by thirteen different German scientific groups. As members of this project, we will try to unravel the mystery of the phylogenetic relationship of all metazoan groups using a large data set of protein sequences of nuclear encoded genes, which derive from both comparative EST (expressed sequence tags) analyses and the amplification of selected, phylogenetically informative genes. The main tasks of our investigations are both to resolve the phylogenetic relationship of the main groups within the molluscs and the positioning of this phylum within the higher order of the Lophotrochozoans, with special respect to the Sipunculida and the Kamptozoa as a potential sister group of the Mollusca. However, the preparation and the analyses of the EST data and some specifically selected "house keeping genes", also known from analyses of Peterson et al. (2004) are still in progress and therefore cannot be used for further analyses. We therefore started to generate and analyse five other genes, the 16S, 18S, 28S, COI and H3 respectively, to reconstruct a molecular tree including most of the Lophotrochozoan taxa.
microscopy and single particle analysis of Nautilus pompilius hemocyanin
under different oxygenation states
ARNE MOELLER, CHRISTOS GATSOGIANNIS, FRANK DEPOIX, ULRICH MEISSNER AND JUERGEN MARKL*
Institute of Zoology, Johannes Gutenberg University, Mainz, Germany *mar...@uni-mainz.de
Hemocyanins are the copper-containing respiratory proteins of many molluscs. They are basically composed of ten copies of an elongated 350 to 400 kda polypeptide subunit. This subunit consists of seven or eight O2-binding functional units (FUs) termed FU-a to FU-h. The ten subunits form a hollow cylinder (the decamer) of ca. 35 nm in diameter, with an internal collar structure. In gastropods, two decamers assemble face-to-face, comprising a didecamer of 8 Mda (for details, see Meissner et al. 2000, J. Mol. Biol. 298, 21-34). In the cephalopod Nautilus pompilius, single decamers are present, based on a subunit comprising only seven FUs; its complete primary structure has recently been published (Bergmann et al. 2006, J. Mol. Evol. 62, 362-374). Although X-ray analysis of single FUs are available that provide near-atomic resolution, the exact path of the elongated subunit within the decamer, respectively didecamer, as well as details of the collar structure are still obscure. Notably, information about possible structural movements within the molecule during cooperative oxygen binding is scarce. According to SAXS analyses (Hartmann et al. 2004, Micron 6:11-13), such conformational changes should be directly visible at a resolution between 10 and 20 Å. Computer aided processing of data obtained by cryo-electron microscopy should allow to directly visualize the quarternary structure of different native states. Therefore, we developed a preparation method for respiratory proteins that allows their incubation in different gaseous environments and their subsequent shock-freezing in liquid ethane. To visualize conformational changes during oxygenation, we choose Nautilus hemocyanin because of its simpler construction and higher symmetry compared to gastropod hemocyanin. We freshly purified the hemocyanin from Nautilus hemolymph and exposed aliquots to two different atmospheres: deoxy (100% N2) and oxy (25% O2, 75% N2). Subsequent high-resolution cryo-electron microscopy, digital image processing, and 3D reconstruction allowed a comparison of both structures at ca. 10 Å resolution which revealed significant structural differences between the putative oxy and the putative deoxy form. The clues of these results, and possible pitfalls such as artifacts will be discussed.
[Supported by the DFG (Ma843), the Stiftung Rheinland-Pfalz für Innovation (15202386261548), the Landesexzellenzcluster "Immunointervention" and the Elektronenmikroskopiezentrum Mainz.]
molluscan collection of the National Museums Scotland (Royal Museum);
significance, value and potential
Acting Curator - Mollusca Department of Natural Sciences, National Museums of Scotland, Chambers Street, Edinburgh
The mollusc collection of the National Museums Scotland is the third largest in the U.K. and is of global significance. Holdings include: type specimens of W.S.Bruce's Scottish National Antarctic Expedition (1902 - 1904); deep-water species from the Rockall Trough and the Portuguese coast from the British Atlantic Benthos Survey (1973); and comprehensive series of land and freshwater molluscs, including the A. E. Salisbury collection (acquired 1961), being the largest private collection of exotics in the U. K. Our new storage facilities provide ample bench space. NMS seeks to maximise the usage of its collection and offers opportunities for research in, but not only, the areas of taxonomy, morphometrics, isotopic analyses and biogeography. There are further opportunities for public dissemination of research, given the special museum combination of research with a public interface. NMS encourages inquiries from interested visitors and collaborators, both for short visits, loans and longer term projects.
Habitat fragmentation is one of the major threats to the Earth's biodiversity. Global biodiversity is concentrated in tropical forests, but nowhere in the world is the rate of habitat fragmentation so high as in tropics. In many parts of the tropics, modified habitats increasingly dominate the landscape and it is vital to understand the significance of such habitats to the survival and conservation of tropical forest species. This talk focuses on the structure of the land -snail communities of fragmented rainforest and village home gardens in southwestern Sri Lanka. Home gardens are an important type of modified, agricultural habitat in Sri Lanka. Having evaluated the capacity of rainforest snails to persist in home gardens and explore the ecological and conservation implications of this, I show that although a substantial part of the rainforest fauna is restricted to forest, a significant number of both widespread and localized rainforest species can persist in home gardens. Home gardens, therefore, have potential as refugia for Sri Lankan rainforest snails and may have a key part to play in the re-establishment of connectivity in Sri Lanka's fragmented rainforest landscapes.
this a sacoglossan? Computer-based 3D anatomical visualisation of the
mesopsammic Platyhedyle denudata Salvini-Plawen, 1973 (Opisthobranchia,
INA-MARIA RÜCKERT, GERHARD HASZPRUNAR AND MICHAEL SCHRÖDL
Zoologische Staatssammlung München, Munich, Germany
The tiny marine interstitial species Platyhedyle denudata Salvini-Plawen, 1973 has a dorsoventrally flattened, wormlike body which lacks a shell and any tentacles. Initially it was included in the opisthobranch taxon Acochlidiacea as an own-family Platyhedylidae by Salvini-Plawen (1973). However, the postpharyngeal central nervous system and the monostichoglossan radula pointed towards a sacoglossan relationship. Wawra (1979, 1988, 1991) corrected the original description regarding several aspects: P. denudata is hermaphroditic rather than dioecious, a copulatory organ is present, the cerebral and the pleural ganglia are fused instead of being separate, an ascus for storage of worn radula teeth is present, cuticular jaws appear absent, and the digestive gland is not an acochlidian-like single U-shaped duct but is comprised of two separate glandular ducts which are fused anteriorly and posteriorly. Wawra (1979) had already transferred Platyhedyle to the Sacoglossa. A cladistic analysis of Sacoglossa by Jensen (1996) placed Platyhedyle as the sister group of the evenly aberrant elysioidean Gascoignella aprica Jensen, 1983.
Computer-based three-dimensional visualisation is an ideal tool to analyse and document the anatomy of tiny opisthobranchs, and has thus been applied to critically review the data formerly obtained on P. denudata. Several specimens were extracted from subtidal sands of the Mediterranean type locality, Secce della Meloria, and observed alive. Fixed specimens were embedded in Spurr' s resin and serial histological sections (1.5 mm) were made. One subadult individual was completely reconstructed using AMIRA software, mature gametes were studied in a second individual. Our results confirm and supplement Wawra' s observations and leave no doubts on the sacoglossan nature of P. denudata.
|Jensen KR. 1996. Phylogenetic systematics and classification of the Sacoglossa (Mollusca, Gastropoda,|
|Opisthobranchia). Phil Trans Roy Soc London B 351: 91-122.|
|Salvini-Pawen Lv. 1973. Zur Kenntnis der Philinoglossacea und der Acochlidiacea mit Platyhedylidce fam. novo|
|(Gastropoda, Cephalaspidea). Z zool Syst Evol forsch 11: 110-133.|
|Wawra E. 1979. Zur systematischen Stellung von Platyhedyle denudata Salvini-Plawen, 1973 (Oposthobranchia|
|Gastropoda). Z zool Syst Evol forsch 17: 221-225.|
|Wawra E. 1988. Beitrag zur Kenntnis des Zentralnervensystems von Platyhedyle denudata Salvini-Plawen, 1973|
|(Ascoglossa, Gastropoda). Ann Naturhist Mus Wien 90: 401-406.|
|Wawra E. 1991. Beitrag zur Kenntnis des Genitaltraktes von Platyhedyle denudata Salvini-Plawen, 1973 (Mollusca:|
|Gastropoda. Ascoglossa). Ann Naturhist Mus Wien 92: 269-275.|
morphology of the Thraciidae
A. F. SARTORI AND E. M. HARPER
Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, U.K. andr...@yahoo.com.br
Thraciidae Stoliczka, 1870 (Bivalvia: Anomalodesmata) is a cosmopolitan family of marine burrowers, generally regarded to comprise eight extant genera. An analysis of diagnostic characters for the family reveals that most are solely based on the shell, many are rather variable throughout the constituent species, none occur exclusively in thraciids, and several are likely to be plesiomorphies. Monophyly of the taxon is thus questionable. Although recent molecular investigations provided evidence that the family is indeed non-monophyletic, formal taxonomic treatment is hindered by lack of knowledge of the morphology of most genera. In the present study, the biology, shell structure and anatomy of previously unsurveyed thraciids are investigated by dissections, serial histological sections and scanning electron microscopy. Not only will the results broaden our knowledge of this poorly understood group but hopefully they will form the required morphological basis for a revision of the family.
Financial support: ORSAS; Gates Cambridge Trusts; Emmanuel College.
confocal laser scanning microscopy and electron microscopy to investigate
the mantle and velar ciliature of larval bivalves
Institute of Marine Sciences, School of Biological Sciences, University of Portsmouth, Ferry Road, Portsmouth P04 9LY, UK
The planktotrophic larva Crassostrea gigas, has organised ciliation on the mantle and velum that increases in complexity during larval development. Serotonin and catecholamines have been implicated in the control of ciliary activity, as early morphogens, and as triggers in metamorphosis. General catecholamines were imaged with aldehyde-induced fluorescence, while serotonin was localised using immunohistochemistry. The current study aims to clarify the localisation of these compounds in specific larval structures through the novel integration of observations from fluorescence microscopy with anatomical information from scanning electron microscopy. SEM has been used to examine the distribution and morphology of the ciliation found on the larvae, and discrete cilia groups were identified and 'mapped' throughout larval ontogeny. SEM and traditional LM sectioning has also indicated the presence of a previously unrecorded row of compound cilia on the velar rim. [see also reserch grant report]
an appropriate new marker. Phylogeny of polyplacophorans resolved by
KLAUS STREIT1, DOUGLAS J. EERNISSE2 AND BERNHARD LIEB1*
1Johannes Gutenberg University, Mainz, Germany, *lie...@uni-mainz.de
2California State University, Fullerton, California USA
Molluscan hemocyanins are ancient respiratory proteins estimated to have evolved -700-800 MYA. The native molecules are formed from 10, 20 or more identical subunits of which each possesses a molecular mass of 350 - 400 kda. The subunits show a repetitive structure of 7 (a-g) to 8 (a-h) functional units. Each domain-coding exon is separated from a paralogous neighboring exon by an intron of variable size. These introns are probably as ancient as the Precambrian duplication events that led to the repeated exons, because all these introns are in phase 1 and are also located at the same positions within the orthologous hemocyanin genes across Mollusca. In contrast to the case of gastropods, bivalves and cephalopods, in which paralogs of the entire hemocyanin gene region can be observed, chitons possess only one type of hemocyanin, and this forms ~4,000 kda homodecamers.
We assessed the phylogenetic utility of hemocyanin for selected chitons. Particular hemocyanin coding regions were compared across diverse chitons and results were consistent with expectations for high-level relationships based on recent morphological and molecular studies. In particular, Chitonida was robustly subdivided into two clades, Acanthochitonina and Chitonina, although these results are preliminary due to still limited taxonomic sampling.