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PubMed2000

The monophyletic origin of freshwater crayfish estimated from nuclear and mitochondrial DNA sequences.

Despite their widespread use as model organisms, the phylogenetic status of the around 520 species of freshwater crayfish is still in doubt. One hypothesis suggests two distinct origins of freshwater crayfish as indicated by their geographical distribution, with two centres of origin near the two present centres of diversity; one in south-eastern United States and the other in Victoria, Australia. An alternative theory proposes a single (monophyletic) origin of freshwater crayfish. Here we use over 3000 nucleotides from three different gene regions in estimating phylogenetic relationships among freshwater crayfish and related Crustacea. We show clear evidence for monophyly of freshwater crayfish and for the sister-group relationship between crayfish and clawed lobsters. Monophyly of the superfamilies Astacoidea and Parastacoidea is also supported. However, the monophyly of the family Cambaridae is questioned with the genus Cambaroides being associated with the Astacidae.

Animals↗
PubMed2006

Hormonal induction of undescribed males resolves cryptic species of cladocerans.

Cyclic parthenogens have a mixed breeding system with both meiotic and ameiotic eggs. Although investment in sexual stages is often synchronized with seasonal cycles, the degree of investment is a quantitative trait associated with habitat instability. Populations of cyclic parthenogens from stable environments, such as large lakes and oceans, generally show reduced or undetectable investment in males. Indeed, males of many species of lacustrine cyclic parthenogens are unknown to science. Methyl farnesoate (MF), a crustacean juvenile hormone, has been implicated as an inducer of male formation in Daphnia magna (Crustacea: Cladocera), a denizen of unstable habitats with marked sexual recruitment. Here, we show experimentally that MF induces male production in four distantly related lacustrine species of cladocerans under growth conditions unfavourable for male production. The males of three species are new to science. Unlike females, the anatomy of the previously unknown males of Bosmina (Lunobosmina) oriens permitted ready morphological diagnosis of sibling species and subfossils. The results suggest that the role for MF in the sex determination of cladocerans is general.

Animals↗
PubMed2006

Do distantly related parasites rely on the same proximate factors to alter the behaviour of their hosts?

Phylogenetically unrelated parasites often increase the chances of their transmission by inducing similar phenotypic changes in their hosts. However, it is not known whether these convergent strategies rely on the same biochemical precursors. In this paper, we explored such aspects by studying two gammarid species (Gammarus insensibilis and Gammarus pulex; Crustacea: Amphipoda: Gammaridae) serving as intermediate hosts in the life cycle of two distantly related parasites: the trematode, Microphallus papillorobustus and the acanthocephalan, Polymorphus minutus. Both these parasite species are known to manipulate the behaviour of their amphipod hosts, bringing them towards the water surface, where they are preferentially eaten by aquatic birds (definitive hosts). By studying and comparing the brains of infected G. insensibilis and G. pulex with proteomics tools, we have elucidated some of the proximate causes involved in the parasite-induced alterations of host behaviour for each system. Protein identifications suggest that altered physiological compartments in hosts can be similar (e.g. immunoneural connexions) or different (e.g. vision process), and hence specific to the host-parasite association considered. Moreover, proteins required to alter the same physiological compartment can be specific or conversely common in both systems, illustrating in the latter case a molecular convergence in the proximate mechanisms of manipulation.

Acanthocephala↗
PubMed2006

Species preferentiality of the pollen tube attractant derived from the synergid cell of Torenia fournieri.

The synergid cell of Torenia fournieri attracts pollen tubes by a diffusible but yet unknown chemical attractant. Here we investigated the species difference of the attractant using five closely related species in two genera, namely T. fournieri, Torenia baillonii, Torenia concolor, Lindernia (Vandellia) crustacea, and Lindernia micrantha. These five species have an exserted embryo sac, and ablation experiments confirmed that their synergid cells attracted the pollen tube. When ovules of T. fournieri and one of the other species were cultivated together with pollen tubes of each species, pollen tubes were significantly more attracted to synergid cells of the corresponding species. The attraction was not affected by the close proximity of embryo sacs of different species. This suggests that the attractant is a species-preferential molecule that is likely synthesized in the synergid cell. The calcium ion, long considered a potential attractant, could not serve as the sole attractant in these species, because elevation of the calcium ion concentration did not affect the observed attraction. In vivo crossing experiments also showed that the attraction of the pollen tube to the embryo sac was impaired when pollen tubes of different species arrived around the embryo sac, suggesting that the species preferentiality of the attractant may serve as a reproductive barrier in the final step of directional control of the pollen tube.

Biological Factors↗
PubMed2001

Structure of lobster apocrustacyanin A1 using softer X-rays.

The molecular basis of the camouflage colouration of marine crustacea is often provided by carotenoproteins. The blue colour of the lobster carapace, for example, is intricately associated with a multimacromolecular 16-mer complex of protein subunits each with a bound astaxanthin molecule. The protein subunits of crustacyanin fall into two distinct subfamilies, CRTC and CRTA. Here, the crystal structure solution of the A(1) protein of the CRTC subfamily is reported. The problematic nature of the structure solution of the CRTC proteins (both C(1) and A(1)) warranted consideration and the development of new approaches. Three putative disulfides per protein subunit were likely to exist based on molecular-homology modelling against known lipocalin protein structures. With two such subunits per crystallographic asymmetric unit, this direct approach was still difficult as it involved detecting a weak signal from these sulfurs and suggested the use of softer X-rays, combined with high data multiplicity, as reported previously [Chayen et al. (2000), Acta Cryst. D56, 1064-1066]. This paper now describes the structure solution of CRTC in the form of the A(1) dimer based on use of softer X-rays (2 A wavelength). The structure solution involved a xenon derivative with an optimized xenon L(I) edge f" signal and a native data set. The hand of the xenon SIROAS phases was determined by using the sulfur anomalous signal from a high-multiplicity native data set also recorded at 2 A wavelength. For refinement, a high-resolution data set was measured at short wavelength. All four data sets were collected at 100 K. The refined structure to 1.4 A resolution based on 60 276 reflections has an R factor of 17.7% and an R(free) of 22.9% (3137 reflections). The structure is that of a typical lipocalin, being closely related to insecticyanin, to bilin-binding protein and to retinol-binding protein. This A(1) monomer or dimer can now be used as a search motif in the structural studies of the oligomeric forms alpha- and beta-crustacyanins, which contain bound astaxanthin molecules.

Amino Acid Sequence↗
PubMed2003

Geographic and genetic variation in feeding preference for chemically defended seaweeds.

Genetic variation in tolerance for seaweed chemical defenses among populations of marine herbivores is poorly described, either because few marine studies have addressed the issue or because the feeding preferences of populations of marine herbivores rarely differentiate. We address this using the polyphagous amphipod Ampithoe longimana (Crustacea), which commonly consumes, and lives on, terpene-rich brown seaweeds in the tropical genus Dictyota. Previous work demonstrated that in areas where the amphipod and seaweeds overlap geographically, these chemically deterrent seaweeds provide the amphipod with spatial refuges from predation by omnivorous fishes that avoid consuming Dictyota. However, the amphipod's distribution extends northward of the seaweed's distribution, making this benefit of association unavailable to more northerly populations of amphipods. On average, populations sympatric with Dictyota have stronger feeding preference for Dictyota species and greater fitness when raised on Dictyota than do populations that are outside Dictyota's geographic endpoint. These results are consistent with the hypothesis that in areas where the amphipods co-exist with Dictyota, selection favors amphipods that tolerate Dictyota's chemical defenses and thereby access its enemy-free space. Amphipods allopatric with Dictyota are unable to tolerate Dictyota's chemical defenses, either because of selection, drift, or some mix of both forces. A trade-off between preference for Dictyota and for the chemically distinct seaweed Hypnea musciformis is suggested by the finding that populations with high preference for Dictyota tended to have lower preference for Hypnea. However, this population-level pattern appears to be the result of independent evolution and not a genetic trade-off: an analysis of full-sib families within a single population detected heritable variation in preferences for Dictyota and suggested this for Hypnea (although the latter was not statistically significant), yet no family-level covariation was detected. Phylogeographic analysis of mitocondrial DNA and nuclear sequences indicates a strong historical break between populations sympatric with Dictyota and populations more than 500 km beyond Dictyota's geographic endpoint. The historical separation of these most northerly populations could have allowed a random accumulation of alleles to effectively degrade tolerance for Dictyota, although selection may also be responsible for the degradation.

Amphipoda↗
PubMed2004

Habitat-specific pigmentation in a freshwater isopod: adaptive evolution over a small spatiotemporal scale.

Pigmentation in the freshwater isopod Asellus aquaticus (Crustacea) differed between habitats in two Swedish lakes. In both lakes, isopods had lighter pigmentation in stands of submerged vegetation, consisting of stoneworts (Chara spp.), than in nearby stands of reed (Phragmites australis). Experimental crossings of light and dark isopods in a common environment showed that pigmentation had a genetic basis and that genetic variance was additive. Environmental effects of diet or chromatophore adjustment to the background had minor influence on pigmentation, as shown by laboratory rearing of isopods on stonewort or reed substrates, as well as analyses of stable isotope ratios for isopods collected in the field. In both study lakes, the average phenotype became lighter with time (across generations) in recently established stonewort stands. Taken together, these results indicate that altered phenotype pigmentation result from evolutionary responses to local differences in natural selection. Based on the assumption of two generations per year, the evolutionary rate of change in pigmentation was 0.08 standard deviations per generation (haldanes) over 20 generations in one lake and 0.22 haldanes over two generations in the other lake. This genetic change occurred during an episode of population growth in a novel habitat, a situation known to promote adaptive evolution. In addition, stonewort stands constitute large and persistent patches, characteristics that tend to preserve local adaptations produced by natural selection. Results from studies on selective forces behind the adaptive divergence suggest that selective predation from visually oriented predators is a possible selective agent. We found no indications of phenotype-specific movements between habitats. Mating within stonewort stands was random with respect to pigmentation, but on a whole-lake scale it is likely that mating is assortative, as a result of local differences in phenotype distribution.

Adaptation, Physiological↗
PubMed2005

Electron and ion imaging of gland cells using the FIB/SEM system.

The FIB/SEM system was satisfactorily used for scanning ion (SIM) and scanning electron microscopy (SEM) of gland epithelial cells of a terrestrial isopod Porcellio scaber (Isopoda, Crustacea). The interior of cells was exposed by site-specific in situ focused ion beam (FIB) milling. Scanning ion (SI) imaging was an adequate substitution for scanning electron (SE) imaging when charging rendered SE imaging impossible. No significant differences in resolution between the SI and SE images were observed. The contrast on both the SI and SE images is a topographic. The consequences of SI imaging are, among others, introduction of Ga(+) ions on/into the samples and destruction of the imaged surface. These two characteristics of SI imaging can be used advantageously. Introduction of Ga(+) ions onto the specimen neutralizes the charge effect in the subsequent SE imaging. In addition, the destructive nature of SI imaging can be used as a tool for the gradual removal of the exposed layer of the imaged surface, uncovering the structures lying beneath. Alternative SEM and SIM in combination with site-specific in situ FIB sample sectioning made it possible to image the submicrometre structures of gland epithelium cells with reproducibility, repeatability and in the same range of magnifications as in transmission electron microscopy (TEM). At the present state of technology, ultrastructural elements imaged by the FIB/SEM system cannot be directly identified by comparison with TEM images.

Animals↗
PubMed2006

Cannabinoid receptors in invertebrates.

Two cannabinoid receptors, CB1 and CB2, are expressed in mammals, birds, reptiles, and fish. The presence of cannabinoid receptors in invertebrates has been controversial, due to conflicting evidence. We conducted a systematic review of the literature, using expanded search parameters. Evidence presented in the literature varied in validity, ranging from crude in vivo behavioural assays to robust in silico ortholog discovery. No research existed for several clades of invertebrates; we therefore tested for cannabinoid receptors in seven representative species, using tritiated ligand binding assays with [3H]CP55,940 displaced by the CB1-selective antagonist SR141716A. Specific binding of [3H]CP55,940 was found in neural membranes of Ciona intestinalis (Deuterstoma, a positive control), Lumbricusterrestris (Lophotrochozoa), and three ecdysozoans: Peripatoides novae-zealandiae (Onychophora), Jasus edwardi (Crustacea) and Panagrellus redivivus (Nematoda); the potency of displacement by SR141716A was comparable to measurements on rat cerebellum. No specific binding was observed in Actinothoe albocincta (Cnidaria) or Tethya aurantium (Porifera). The phylogenetic distribution of cannabinoid receptors may address taxonomic questions; previous studies suggested that the loss of CB1 was a synapomorphy shared by ecdysozoans. Our discovery of cannabinoid receptors in some nematodes, onychophorans, and crustaceans does not contradict the Ecdysozoa hypothesis, but gives it no support. We hypothesize that cannabinoid receptors evolved in the last common ancestor of bilaterians, with secondary loss occurring in insects and other clades. Conflicting data regarding Cnidarians precludes hypotheses regarding the last common ancestor of eumetazoans. No cannabinoid receptors are expressed in sponges, which probably diverged before the origin of the eumetazoan ancestor.

Animals↗
PubMed1996

Purification and cDNA cloning of ferritin from the hepatopancreas of the freshwater crayfish Pacifastacus leniusculus.

Ferritin was purified from the hepatopancreas of the freshwater crayfish Pacifastacus leniusculus after injection of iron. It has the same size as horse spleen ferritin (440 kDa) and migrates as two bands, 19 kDa and 20 kDa, respectively, in SDS/PAGE under reducing conditions. Crayfish ferritin (20 kDa) was cloned from a hepatopancreas cDNA library. The deduced amino acid sequence of the crayfish ferritin shows a closer relationship to vertebrate ferritin heavy chains than to insect ferritin and contains the conserved H-specific residues for the ferroxidase centre found in vertebrate ferritin heavy chain. An IRE(iron-responsive element)-like sequence with a predicted stem-loop structure was present in the 5' untranslated region of the crayfish ferritin mRNA. Crayfish ferritin does not share the atypical properties of insect ferritins, such as high molecular mass of intact protein, abundance in hemolymph, and export into vacuoles. We suggest that there are two different types of ferritins distributed in different species: insect-type or secretory ferritins which are predominant in the snail oocyte and insects, and vertebrate (crustacean)-type or cytosolic ferritins which are predominant in vertebrates and crustacea.

Animals↗
PubMed2005

Pathogenicity of vibrios to rainbow trout (Oncorhynchus mykiss, Walbaum) and Artemia nauplii.

The taxonomy of marine vibrios has changed rapidly over the last two decades, and a wealth of new species have been identified. Many Vibrio species are pathogenic to fish and crustaceans; however, little is known about the virulence of many of the novel species. The purpose of this study was to determine the ability of various recent isolates of vibrios to cause disease in rainbow trout (Oncorhynchus mykiss, Walbaum) and crustacea, i.e. Artemia nauplii. Of 56 isolates, representing 26 species of Enterovibrio, Photobacterium and Vibrio, obtained from a diversity of healthy and diseased aquatic animal hosts and water samples from many geographical locations, Vibrio brasiliensis, V. coralliilyticus, V. ezurae, V. fortis, V. kanaloaei, V. neptunius, V. rotiferianus and V. tubiashii were pathogenic to rainbow trout and Artemia nauplii with mortalities of up to 100%. The extracellular products of these pathogenic isolates were harmful to the animal models. In contrast, cultures of Enterovibrio norvegicus, E. coralii, Photobacterium rosenbergii, Vibrio campbellii, V. chagasii, V. cyclitrophicus, V. gallicus, V. gigasii, V. hepatarius, V. hispanicus, V. lentus, V. nereis, V. pacini, V. pomeroyi, V. shilonii, V. superstes, V. tasmaniensis and V. xuii demonstrated either non- or low virulence in the animal models.

Animals↗
PubMed2006

Identification of peptide metabolites of Microcystis (Cyanobacteria) that inhibit trypsin-like activity in planktonic herbivorous Daphnia (Cladocera).

Cyanobacteria are recognized as producers of a broad variety of bioactive metabolites. Among these, the peptides synthesized by the non-ribosomal peptide synthetase pathway occur in high structural variability. One class of cyanobacterial peptides, the cyanopeptolins or micropeptins, have been shown to be strong inhibitors of vertebrate serine proteases, like trypsin. In the present study we screened extracts of ten strains of the unicellular cyanobacterium Microcystis sp. for their potential to inhibit trypsin-like activity in the planktonic crustacea Daphnia, the main herbivores in freshwater ecosystem. Respective standardized IC(50)'s varied for nearly two orders of magnitude. In HPLC fractions we could identify mainly cyanopeptolins as active compounds by MALDI-TOF mass spectrometry. Cyanopeptolins were found in 22 structural variants with 13 variants produced by one strain alone. Peptides of the microviridin class were moderately active while no activity was evident for microginins and microcystins. Among the cyanopeptolins only those were active that had an arginine or lysine residue N-terminal to the modified amino acid 3-amino-6-hydroxy-piperidone. Structural variants that had a tyrosine residue at this particular position did not inhibit trypsin-like activity. The highly variable composition of the side chain of cyanopeptolins had no marked effect on the activity. Among the six cyanobacterial strains we tested intensively two did not produce any cyanopeptolins and were accordingly less active as crude extracts. The present study underlines the potential importance of the biochemistry of cyanobacteria for the feeding ecology of a planktonic herbivore.

Animals↗
PubMed1989

The spermatozoa of the polychaeta (Annelida): an ultrastructural review.

1. Polychaete sperm are divisible into ect-aquasperm, ent-aquasperm, and introsperm. 2. Ect-aquasperm are the commonest type of polychaete sperm and are considered plesiomorphic for the Polychaeta. Re-evolution of ect-aquasperm (as neo-aquasperm) is, nevertheless, tentatively hypothesized for some Sabellida. 3. In terms of ultrastructural studies of sperm in the investigated polychaete families, only ect-aquasperm have been demonstrated for 16 families; only ent-aquasperm for 3 families; ect- and ent-aquasperm for 3; ect- and intro-sperm for 2; ect-, ent- and intro-sperm for 1 family; and only introsperm for 11 families but investigations can only be regarded as preliminary. To date no family is known to have ent- and intro-sperm only. Sperm ultrastructure has yet to be examined in the orders Magelonida, Psammodrilida, Cossurida, Spintherida, Sternapsida, Flabelligerida and Fauvelopsida. 4. Much variation occurs in gross morphology, ultrastructure and configuration of the several components of ect-aquasperm: acrosome, nucleus, mitochondria, and centrioles and associated anchoring apparatus. A 9 + 2 axoneme is constant. 5. Group-specific sperm structure has been demonstrated for the Nereidae (chiefly ect-aquasperm), and for introsperm of the families Histriobdellidae, Questidae; Capitellidae, Spionidae and Protodrilidae. Species-specificity of all classes of spermatozoa is well established. 6. The very small size of ect-aquasperm is correlated with production of large numbers of sperm as an adaptation to broadcast spawning. Simplicity of structure may relate more to conservation of materials than to hydrodynamics. 7. Fertilization by ent-aquasperm requires fewer eggs than in external fertilization and is accompanied by a tendency to lecithotrophy. Elongation of the nucleus and development of asymmetry are seen in several of the few known examples of ent-aquasperm. Whether modifications are related to transfer or to other features, such as lecithotrophy, is uncertain. 8. Evident multiple origins of polychaete introsperm contraindicate their value in establishing relationship between families, in contrast with their utility in groups such as decapod crustacea. 9. At the intrafamilial level polychaete introsperm have taxonomic and phylogenetic value, as seen in the Spionidae, Capitellidae, and Histriobdellidae, and are distinctive of each of these and other families. 10. At higher taxonomic levels, the ultrastructure of the sperm of the oligochaetoid Questidae distinguishes this family from euclitellates, each class of which has its own distinctive subtype of the euclitellate introsperm. 11.(ABSTRACT TRUNCATED AT 400 WORDS)

Acrosome↗
PubMed1987

Amino acid sequences of neuropeptides in the sinus gland of the land crab Cardisoma carnifex: a novel neuropeptide proteolysis site.

The sinus gland is a major neurosecretory structure in Crustacea. Five peptides, labeled C, D, E, F, and I, isolated from the sinus gland of the land crab have been hypothesized to arise from the incomplete proteolysis at two internal sites on a single biosynthetic intermediate peptide "H", based on amino acid composition additivities and pulse-chase radiolabeling studies. The presence of only a single major precursor for the sinus gland peptides implies that peptide H may be synthesized on a common precursor with crustacean hyperglycemic hormone forms, "J" and "L," and a peptide, "K," similar to peptides with molt inhibiting activity. Here I report amino acid sequences of these peptides. The amino terminal sequence of the parent peptide, H, (and the homologous fragments) proved refractory to Edman degradation. Data from amino acid analysis and carboxypeptidase digestion of the naturally occurring fragments and of fragments produced by endopeptidase digestion were used together with Edman degradation to obtain the sequences. Amino acid analysis of fragments of the naturally occurring "overlap" peptides (those produced by internal cleavage at one site on H) was used to obtain the sequences across the cleavage sites. The amino acid sequence of the land crab peptide H is Arg-Ser-Ala-Asp-Gly-Phe-Gly-Arg-Met-Glu-Ser-Leu-Leu-Thr-Ser-Leu-Arg-Gly- Ser-Ala-Glu- Ser-Pro-Ala-Ala-Leu-Gly-Glu-Ala-Ser-Ala-Ala-His-Pro-Leu-Glu. In vivo cleavage at one site involves excision of arginine from the sequence Leu-Arg-Gly, whereas cleavage at the other site involves excision of serine from the sequence Glu-Ser-Leu. Proteolysis at the latter sequence has not been previously reported in intact secretory granules. The aspartate at position 4 is possibly covalently modified.

Amino Acid Sequence↗
PubMed1998

Olfactory development in invertebrates. On the scent of central developmental issues.

Invertebrate olfactory systems offer many advantages for cellular and molecular studies of development and for functional studies of developmental plasticity. For example, nematodes have chemical senses that can be studied using genetic approaches. Arthropods, which include insects and crustacea, have the advantages that certain neurons can be reliably identified from one individual to another, and that olfactory receptor neurons are located on peripheral appendages and thus can be manipulated independently of their brain targets even very early in development. Among the insects, olfactory learning can be displayed and used as a basis for studying olfactory plasticity in bees; genes are especially tractable in flies; individual growth cones can be visualized in the grasshopper embryo; and receptor neurons and glomeruli of known olfactory specificity and behavioral significance can be followed during early development in moths. In addition, many insect nervous systems are amenable to organ culture and dissociated-cell culture, opening the door to experimental studies of cellular interactions that can not be performed in situ. Recent research in the moth Manduca sexta attempts to identify the nature of the interactions between olfactory sensory axons, olfactory neurons of the brain, and glial cells in the creation of the array of glomeruli that underlie olfaction in the adult. Results indicate that timing of the ingrowth of olfactory receptor axons is critical for normal glomerulus development, that a subset of axons expresses a fasciclin II-like molecule that may play a role in guidance of their growth, and that glial cells must surround developing glomeruli in order to stabilize the 'protoglomerular' template made by receptor axon terminals. Moreover, glial cells are dye-coupled to each other early in glomerulus development and gradually become uncoupled. Electrical activity in neurons is not necessary for glomerulus formation; and some intercellular interactions, perhaps involving soluble factors, appear to involve tyrosine phosphorylation. In sum, a detailed picture is emerging of the cellular interactions that lead to the formation of glomeruli.

Animals↗
PubMed1999

The regulation of juvenile hormone production in arthropods. Functional and evolutionary perspectives.

Although sesquiterpenoids are probably the ancestral regulators of reproduction and secondarily of metamorphosis in arthropods, our discussion suggests that the neuropeptides that regulate the biosynthesis of these compounds have arisen on several distinct occasions. These peptides probably occurred originally as regulators of other physiological processes and were subsequently co-opted for the regulation of sesquiterpenoid biosynthesis, perhaps first in adult forms and thereafter in larval forms. The evolution of peptides to assume additional physiological functions probably occurred as a result of gene duplication, both at the peptide level and at the receptor level. There are likely to be numerous regulators of sesquiterpenoid biosynthesis in both Insecta and Crustacea, and investigations to date have only begun to reveal the host of peptide families involved in the regulation of juvenile hormone-related biosynthesis across the arthropods.

Amino Acid Sequence↗
PubMed1999

The kinin peptide family in invertebrates.

Kinins comprise a family of peptides that were first found in the central nervous system of insects and recently also in mollusks and crustaceans. After the isolation of the first members of the kinin family, the leukokinins from Leucophaea maderae, leukokinin-related peptides were found in the cricket Acheta domesticus and the locust Locusta migratoria, all through their ability to induce Leucophaea maderae hindgut contraction. Subsequently, kinins were found in the mosquitoes Culex salinarius and Aedes aegypti and in the earworm Helicoverpa zea. The first noninsect member of this family was isolated from a mollusk, the pond snail Lymnaea stagnalis. Most recently our group has isolated the first kinins from crustaceans. Six kinins were isolated from the white shrimp Penaeus vannamei. To date, 35 members of this family have been isolated. The first relatively small family of insect kinins has grown into an expanding and rather large family with members in insects, crustaceans, and mollusks. In this paper we discuss the kinin family in terms of method of isolation, structure, in vitro and in vivo activity, distribution, receptors, and signal transduction. We will compare the crustacean and insect members of the kinin family, using the data available on crustacea.

Amino Acid Sequence↗
PubMed1973

The effect of glycerol treatment on crab muscle fibres.

1. Membrane constants of the closer muscle of the ghost crab, Ocypoda cursor, were determined before and after treatment in hypertonic glycerol solution and return to an artificial sea-water (A.S.W.) solution.2. Muscle contraction was abolished after return of the muscle to A.S.W.3. The membrane capacitance was reduced from 29.0 muF/cm(2) to 10.5 muF/cm(2).4. Other passive properties of the muscle membrane, not dependent on capacitance, were not changed.5. The presynaptic nerve, transmitter release, post-synaptic sensitivity to transmitter and ionic mechanisms of synaptic action were unaffected by glycerol treatment.6. More than 60% of the membrane capacitance/unit area is contributed by the complex tubular system.7. The tubular system in crustacea is necessary for excitation-contraction coupling.

Animals↗