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[Laurentaeglyphea, a new genus for the second recent species of Glypheid recently discovered. (Crustacea Decapoda Glypheidae)].

In 1975, a recent member of a large group of Crustacea Decapoda was described as Neoglyphea inopinata Forest & de Saint Laurent, until now only known as fossils and presumed extinct since the Eocene. The only known specimen had been collected in the Philippine waters, in 1908, at a depth of 200 m. During the next years, three oceanographical expeditions gave more adult specimens, allowing complete study of the species. From its morphology, it appeared that the status attributed to glypheids in the past in the classification of Decapoda Crustacea was quite erroneous. This group, until then considered as related to Palinurids (rock lobsters) was in fact much closer to Astacids (lobster, crayfish, etc.). In 1982, N. inopinata was recorded from the other side of Equator, from the Timor Sea. In October 2005, a second living species of glypheid was discovered southwest of New Caledonia. It was named Neoglyphea neocaledonica B. Richer de Forges, 2006. However, important and significant differences set apart the two species, especially the ornamentation of the cephalothorax, the conformation of the cephalic part and the proportions of epistom and thoracic appendages, being much more robust. It seems justified to establish, for the more recently described species, a new genus, Laurentaeglyphea, much closer to fossil forms.

Animals↗

Ducts of the labral glands of Leptestheria dahalacensis (Crustacea: Branchiopoda: Spinicaudata).

Inside the labrum of Leptestheria dahalacensis are situated three types of large epidermal gland cells, whose ducts open onto the outer dorsal surface of the labrum. SEM revealed that the thin ducts of the A-type gland cells open out behind the epipharynx at the end of small, conically shaped protuberances, the two paired ducts of the B-type gland cells lead into the distal portion of the labrum, and the external opening of the single duct of the C-type gland cells lies on the dorsal lobe of the labrum. The ducts of the three different gland cell types have the same fundamental constitution, but vary in diameter. Each secretory unit consists of a pair of gland cells (A, B, or C) and a secretory duct. The duct is formed by ring-shaped folding of one anteroposteriorly elongated epidermal cell (duct cell), whose ends adhere closely to one another. A further ring-folded epidermal cell (accessory cell), but flattened in shape, is interposed, like a sleeve-connection, between the gland cells and the duct cell. The reservoirs of gland cells open into the lumen of the duct. Discontinuous deposits of highly electron-dense matter are present on the plasma membrane of the accessory cell delimiting the initial part of the duct lumen, while the plasma membrane of the duct cell facing the lumen is cuticularized. The cytoplasm of the accessory cell, on examination by TEM, appears quite similar to that of the duct cell, except for the different distribution and greater abundance of microtubules. Similarly organized tricellular tegumental glands also commonly occur in other Crustacea, both Malacostraca and non-Malacostraca. Possible functions of secretions from the three different types of gland cells present in the labrum of L. dahalacensis are discussed.

Animals↗

Fertilization envelope in diapause eggs of Pontella mediterranea (Crustacea, Copepoda).

The sequence and timing of morphological changes during envelope formation was followed in diapause eggs of Pontella mediterranea (Crustacea, Copepoda). The multilayer coat enveloping these eggs resulted from the exocytosis of 4 types of cortical vesicles that sequentially released their contents in the perivitelline space. These included small high-density vesicles (hDV) with electron-dense material, vesicles (V) with dense ring granules and a uniform matrix contained within the same compartment, large high-density (HDV) vesicles, and large moderately dense (MDV) vesicles. All of these cortical vesicles were present in newly spawned, fertilized eggs. Their exocytosis resulted from egg activation. One of these cortical vesicles (V) was similar in morphology to the intracisternal granules precursors of endogenous yolk. Intracisternal granules, characteristic of previtellogenic oocytes of many crustaceans, were present in previtellogenic oocytes of P. mediterranea but disappeared in later stages of oocyte development once yolk formation was completed. We discuss the role of cortical vesicles in the formation of the complex extracellular coat enveloping copepod diapause eggs.

Adaptation, Physiological↗

Toxicity of vegetable tannins on crustacea associated with alpine mosquito breeding sites.

The impact of tannins from the environmental vegetation naturally polluting Alpine mosquito breeding sites was experimentally investigated by studying the toxicity of tannic acid, a natural hydrolyzable tannin, on the nontarget crustacean fauna associated with culicine populations. Bioassays indicate that exposure to tannic acid at concentrations from 0.06 to 2.0 mM is more deleterious to Chydorus sphaericus, Diaptomus castor, and Eucypris fuscata, than to Daphnia pulex, Acanthocyclops robustus, and Eucypris virens. Histopathological investigations after treatment with tannic acid at concentrations from 0.125 to 0.500 mM reveal sequential degenerative patterns of the midgut epithelium depending on the taxon, duration of the treatment, and concentrations assayed. These differential toxic effects on Crustacea are compared with those previously observed in larval Diptera, in order to evaluate the plant tannins as potentially useful products in integrated mosquito management programs.

Animals↗

Testosterone metabolism in the estuarine mysid neomysis integer (Crustacea; Mysidacea): identification of testosterone metabolites and endogenous vertebrate-type steroids.

Testosterone metabolism by Neomysis integer (Crustacea; Mysidacea) was assessed to obtain initial data on its metabolic capacity. N. integer were exposed to both testosterone and [(14)C]testosterone. Identification of testosterone metabolites and endogenous steroids was performed using thin-layer chromatography and liquid chromatography with multiple mass spectrometry. Endogenous production of testosterone in mysids was detected for the first time. N. integer were exposed to testosterone and metabolized administered testosterone extensively. At least 11 polar testosterone metabolites (R(f,metabolite) < R(f,testosterone)), androstenedione, dihydrotestosterone, and testosterone were produced in vivo by N. integer. A sex-specific testosterone metabolism was also observed, although this observation requires further confirmation. The anabolic steroid beta-boldenone was also identified for the first time in invertebrates. The metabolic pathway leading to the formation of beta-boldenone remains unknown, since the steroidal precursor androstadienedione could not be detected. These results reveal interesting similarities in enzyme systems in invertebrate and vertebrate species. Alterations in steroid hormone metabolism may be used as a new biomarker for the effects of endocrine disruptors in invertebrates.

Anabolic Agents↗

Taxonomic status and phylogenetic relationships of some species of the genus Gammarus (Crustacea, Amphipoda) deduced from mitochondrial DNA sequences.

Mitochondrial DNA nucleotide sequence analysis was used to determine the extent of genetic differentiation among six species of the genus Gammarus (Crustacea, Amphipoda) common in France (G. fossarum, G. pulex, G. lacustris, G. wautieri, G. roeseli, G. marinus). From 23 different populations, 104 specimens were compared to examine their taxonomic status and their phylogenetic relationships. Nucleotide sequences for a 376-base segment of the cytochrome c oxidase subunit I (COI) gene were obtained through direct sequencing of amplified DNA. The strong sequence variability found at the interspecific level, generally masked by morphological or ecological similarities, is consistent with that observed for other crustaceans and supports existing species classifications. A high level of genetic variation was observed at the intraspecific level, suggesting that the COI gene will be a powerful marker for amphipod population biology. Based on the mitochondrial population biology. Based on the mitochondrial DNA results, we propose a phylogenetic hypothesis of the relationships among the six studied species, which is discussed in biogeographic and evolutionary terms.

Animals↗

Patterns of evolutionary change in Baikalian gammarids inferred from DNA sequences (Crustacea, Amphipoda).

The Baikalian gammarids (Crustacea, Amphipoda) are the most widely known and most spectacular example of an adaptive radiation among contemporary freshwater invertebrates. To study the phylogeny of the Baikalian gammarids we sequenced a 622-bp-long fragment of the nuclear gene coding for 18S rRNA from species of 18 endemic Baikalian genera and Gammarus pulex-a non-Baikalian taxon. Some important morphological characters appear independently in both lineages and suggest parallelism in the development of gigantism and body armament. The first lineage comprises benthic, mostly unarmed taxa. The second lineage contains predominantly armed taxa, most of which are detrivorous or carnivorous.

Animals↗

Phylogeny and biogeography of serolid isopods (Crustacea, Isopoda, Serolidae) and the use of ribosomal expansion segments in molecular systematics.

In this study, a molecular phylogenetic hypothesis for 16 species of serolid isopods (Crustacea, Isopoda, Serolidae) from Antarctic waters, the deep sea, South America, and Australia is presented. The genes used are a 500-bp fragment of the mitochondrial LSU rRNA gene and a 700-bp fragment located in the variable region V4 of the nuclear SSU rRNA gene. The species composition and monophyly of morphologically defined genera of which several members were available are confirmed by the molecular data (Ceratoserolis, Spinoserolis, and Cuspidoserolis). The molecular data also support the redefinition of Frontoserolis s.l. and Serolella and the erection of the new genera Septemserolis and Paraserolis, as proposed by W]agele. The relationship among several genera is resolved differently in the molecular hypothesis than in the two existing morphological hypotheses, however. The molecular phylogeny may have important consequences for understanding the biogeography of the Serolidae, indicating that all Antarctic species in this study form a monophyletic group which has probably derived from species with closest extant relatives in South America. All 3 species included in this study living today in deep waters (>2000 m) of the Southern Ocean are most closely related to species living on the Antarctic shelf, so that parallel colonization of the deep sea by way of polar submergence can be reconstructed. In this study, a V4 expansion segment is reported which exceeds the longest crustacean sequences known until now by more than 270 bp. Although the V4 expansion segment has proven useful for phylogenetic purposes in this study, there is circumstantial evidence that its mechanism of evolution may depend not only on inheritance of single-site substitutions, making its routine use in phylogenetic studies potentially dangerous.

Animals↗

The fine structure of the compound eyes of mysids (crustacea: mysidacea).

The ultrastructure of the compound eyes of five species of mysids (Crustacea: Mysidacea), Praunus flexuosus, Siriella norvegica, Mysidopsis gibbosa, Neomysis integer and Erythrops serrata, is described. The ommatidia are constructed on a common plan, but there are considerable differences in detail. Common features include the arrangement of the cornea, crystalline cone and the basement membrane. The number of retinular cells differ: in Neomysis and Erythrops there are seven, whereas in the other species there are eight, the eighth cell forming a distal rhabdom, which consequently is lacking in the ommatidia of Neomysis and Erythrops. Another difference is the epirhabdom, which is lacking in Erythrops, but present in the other species. The epirhabdom is an extracellular structure, probably serving as a dioptric element. The pigment arrangement is similar in the first four species. The pigment shield consists of the distal pigment, distal reflecting pigment, proximal pigment (in the retinular cells) and the proximal reflecting pigment. The distal and proximal pigments are dark screening pigments. In addition to these, there are basal red pigment cells, which are mainly located below the basement membrane. In Erythrops there are three kinds of pigment cells: distal pigment cells, distal reflecting pigment cells and basal red pigment cells. Besides the basal red pigment cells, the distal pigment cells contain red pigment granules.

Animals↗

Cell lineage of the midline cells in the amphipod crustacean Orchestia cavimana (Crustacea, Malacostraca) during formation and separation of the germ band.

Cell lineages of identified midline cells were traced in the amphipod Orchestia cavimana (Crustacea, Malacostraca) by in vivo labelling. Midline cells are a common phenomenon in the germ band of crustaceans and insects. Studies in midline cells of Drosophila showed an origin from separate, paired anlagen and a differentiation into three types of cells. The in vivo labelling of midline cells of Orchestia demonstrates that they originate from the same material as the neural and epidermal ectoderm, divide in a stereotyped cell division pattern and give rise to at least two different types of cells. During the following evolutionarily derived mode of germ band elongation in Orchestia, a morphogenetic process is intercalated that separates germ band halves. On the level of single cells, it can be shown that midline cells are the only ectodermal cells that bridge the large distance between the separated parts. The cells are stretched extensively but do not proliferate. Comparing the midline cells of Orchestia with non-malacostracan crustaceans and insects, the results favour the hypothesis that midline cells are a distinct population of cells homologous in crustaceans and insects.

Animals↗

Evidence for the presence of serotonin in Mysidacea (Crustacea, Peracarida) as revealed by fluorescence immunohistochemistry.

In crustaceans, serotonin (5-HT) exerts a wide range of physiological actions on many tissues. However, 5-HT has not been detected to date in Mysidacea (Crustacea, Peracarida). We have investigated the presence of 5-HT in the brain and the eyestalks of two Mysida (Leptomysis lingvura, Hemimysis margalefi) and one Lophogastrida (Lophogaster typicus) species by using the immunohistofluorescence technique. 5-HT-like immunopositive areas exhibit a similar pattern in the three species. 5-HT-like immunostaining is present in the retinular photosensitive cells, except in the deep-living species L. typicus. 5-HT-like cell bodies and fibres are observed in the lamina ganglionaris and in the three medullae. In the sinus gland, only 5-HT-like endings are detected. In the eyestalks, 5-HT-like fibres detected in the optic tract link with the protocerebrum, in which 5-HT-like somata and their extensions are found. Some neurones are detected in the anterior median cell cluster, in the protocerebral bridge and in the central body. In the deutocerebrum, the paracentral lobes are connected by immunoreactive fibres that run along the deutocerebral commissure. The glomeruli of the olfactory lobes exhibit strong diffuse immunostaining. Beside and in the median part of the deutocerebrum, at least two large serotoninergic neurones project their axons into the olfactory lobe cell cluster. Immunoreactive fibres are also found in the antennular neuropiles. Our results demonstrate the presence of 5-HT-like cell bodies and fibres in Mysidacea. The distribution patterns of the 5-HT immunoreactivity found herein are compared with those of other peracarids and decapods.

Animals↗

Organization of the mitochondrial genome of mantis shrimp Pseudosquilla ciliata (Crustacea: Stomatopoda).

We determined the nearly complete mitochondrial genome of Pseudosquilla ciliata (Crustacea, Stomatopoda), including all protein-coding genes and all but one of the transfer RNAs. There were no gene rearrangements relative to the pattern shared by crustaceans and hexapods. Phylogenetic analysis using concatenated amino acid sequences of the mitochondrial protein-coding genes confirmed a basal position of Stomatopoda among Eumalacostraca. Pancrustacean relationships based on mitogenomic data were analyzed and are discussed in relation to crustacean and hexapod monophyly and hexapod affinities to crustacean subtaxa.

Animals↗

Metaprotella sandalensis (Crustacea: Amphipoda: Caprellidae): a bioindicator of nutrient enrichment on coral reefs? A preliminary study at Mauritius island.

The population of the caprellid Metaprotella sandalensis Mayer (Crustacea: Amphipoda) associated with the seaweed Turbinaria ornata (Turner) J. Agardh was studied on a spatial scale in relation to the influence of physico-chemical factors on the coral reef system at Mauritius Island. Some areas of the coast of Mauritius are currently subject to disturbance due to industrialisation and rapidly growing tourist development programmes, meanwhile other sites of the island are still unaltered. T. ornata was sampled at 12 stations, distributed around the whole island to represent the heterogeneous conditions. The density of Metaprotella sandalensis living on T. ornata was measured. The linear regression and the multivariate analysis showed a strong correlation between the densities of the caprellid and the physico-chemical parameters. The highest densities of M. sandalensis were found in the most stressed sites characterised by the highest values of nitrate, phosphate, chemical oxygen demand and silting. According to these results and taking into account that M. sandalensis and T. ornata are widely distributed in most of the tropical ecosystems, we preliminarily propose usage of the density of this caprellid as a new monitoring tool on coral reefs or, at least, as a first diagnosis for the detection of nutrient enrichment on these ecosystems.

Animals↗

Toxicity to crustacea due to polypeptide-phospholipase interaction in the venom of a chactoid scorpion.

The toxic factors to isopods (crustacea) were isolated from the venom of the chactoid scorpion Scorpio maurus palmatus (Scorpionidae) by the aid of column chromatography, and their purity was assessed by disc electrophoresis, analytical ultracentrifugation, isoelectrofocusing, and amino acid analysis. The toxicity to isopods is attributed to two groups of components: (a) Low-molecular-weight basic polypeptides possessing about 3 and 8% of the crude venom lethality and paralytic potency to isopods, respectively. These components are characterized by very similar and unique amino acid compositions of 31 to 34 amino acids with molecular mass of about 3.5 kDa and a deficiency in methionine, leucine, phenylalanine, histidine, and tryptophan. (b) Toxic phospholipases are also toxic to insect but not to mammals. A lethal phospholipase which contained 37% of the total venom phospholipase activity and 11% of its toxicity to isopods was purified. This phospholipase consists of 125 amino acids (Mr 14,581) and is a hydrophobic, acidic protein composed of two isoenzymes (pI 4.7 and 4.9). This enzyme demonstrates an A2-type positional specificity (EC 3.1.1.4) with pH and temperature optima of 7.5-8.0 and 40-50 degrees C, respectively, and high calcium requirements. The lethal potency of the basic polypeptides is evidently increased by the addition of low, sublethal doses of the pure phospholipase. Such synergism was not observed with regards to their paralytic activity. The pharmacological significance of these data is discussed.

Amino Acids↗

Molecular biology of neurohormone precursors in the eyestalk of Crustacea.

Our knowledge concerning the primary structures of crustacean neuropeptides has been broadened considerably during the last few years and has greatly contributed to the successful application of molecular biological techniques to crustacean neuroendocrine research. In this review, we compare and discuss the preprohormones of the Red Pigment Concentrating Hormone (RPCH), the Pigment-Dispersing Hormone (PDH) and the different members of the Crustacean Hyperglycemic Hormone, Molt-Inhibiting and Gonad-Inhibiting Hormone family (CHH/MIH/GIH peptide family), recently elucidated by cloning and sequencing of the respective cDNAs. Expression studies, using in situ hybridization, Northern blots and RNase protection assays, have demonstrated that the mRNAs encoding some of the aforementioned preprohormones (for example, preproPDH and preproCHH) are not only expressed in the eyestalk but also in other parts of the central nervous system. The combination of molecular biological techniques with (bio)chemical and immunochemical methods provides elegant tools to study neuropeptides at the level of mRNA and peptide in individual animals during different physiological conditions. The fundamental knowledge obtained by such a combined approach will give detailed insight into how neuropeptides are involved in the adaptation of Crustacea to a broad spectrum of natural and aquacultural conditions.

Amino Acid Sequence↗

State-dependent pairing behaviour in male Gammarus pulex (L.) (Crustacea, Amphipoda): effects of time left to moult and prior pairing status.

Because mating can be costly in terms of time and energy, an individual's propensity to engage in courtship and mating activities might be modulated by its physiological state. However, so far, state-dependent mate choice has received little attention The present study examined the effect of both prior pairing status and time left to the moult on the ability of male Gammarus pulex (Crustacea, Amphipoda) to enter in precopula with receptive females. In the lab, males that were freshly collected in precopula pairs in the field had a higher probability of re-pairing and were quicker to enter in precopula with receptive females compared to males of similar size that were freshly collected unpaired. In addition, unpaired males found in the field were closer to their moult than paired males. Considered together, our results strongly suggest that time left to the moult and prior mating status directly influence male propensity to pair in G. pulex.

Amphipoda↗

TMAO and other organic osmolytes in the muscles of amphipods (Crustacea) from shallow and deep water of Lake Baikal.

Concentrations of trimethylamine oxide (TMAO) and other 'compatible' osmolytes were analyzed in the muscle tissue of Lake Baikal amphipods (Crustacea) in relation to water depth of the freshwater Lake Baikal. Using HPLC and mass spectrometry, glycerophosphoryl choline (GPC), betaine, S-methyl-cysteine, sarcosine, and taurine were detected for the first time in freshwater amphipods. These osmolytes were frequently found in the five species studied but mixtures were too complex to be quantified. The pattern of these osmolytes did not change with respect to water depth. The TMAO concentration, however, was significantly higher in the muscle tissue of amphipods living in deep water than of those living in shallow water, which supports the hypothesis that TMAO acts as a protective osmolyte at increased hydrostatic pressure. We propose that eurybathic amphipods, exposed to raised hydrostatic pressure in the extremely deep freshwater Lake Baikal, have elevated TMAO levels to counteract the adverse effect of high pressure on protein structure. The elevated intracellular osmotic pressure is balanced by upregulating the extracellular hemolymph NaCl concentration.

Animals↗

Purification and characterization of vitellin from the estuarine mysid Neomysis integer (Crustacea; Mysidacea).

Invertebrates account for roughly 95% of all animals, yet surprisingly, little effort has been invested to understand their value in signaling potential environmental endocrine disruption. There has been, however, much recent attention on vitellogenin induction in egg-laying invertebrates and vertebrates as indicators of exposure to estrogenic xenobiotics. Mysid shrimp (Crustacea: Mysidacea) have been put forward by several researchers and regulatory bodies (e.g., US-EPA) as suitable test organisms for the evaluation of environmental endocrine disruption. In view of developing sensitive assays to study endocrine disruption in the estuarine mysid Neomysis integer, we isolated and characterized vitellin, the major yolk protein in eggs. Vitellin was purified using gel filtration and characterized by electrophoresis using different staining procedures. Specific (as shown by Western blotting) polyclonal antibodies were produced in rabbit against the purified vitellin of N. integer. These antisera will be used to develop immunoassays to study vitellogenesis in mysids and to detect potential stimulatory or inhibitory effects of endocrine disruptors on the production of vitellin.

Animals↗