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PubMed2003

Sex determination in crayfish: are intersex Cherax quadricarinatus (Decapoda, Parastacidae) genetically females?

In the Australian red-claw crayfish Cherax quadricarinatus (von Martens) (Decapoda, Parastacidae), a gonochoristic species, seven different combinations of intersex individuals (with both male and female genital openings) have been described. However, to date, the genetic basis for this phenomenon has not been investigated. This study was designed to test a simple chromosome-based sex-determination model for C. quadricarinatus that assumes the male to be the homogametic (ZZ) sex. According to our model, intersex individuals that are functionally males are genetically females (WZ). Individual crosses were performed between intersex and female crayfish, with control crosses being performed between normal males and females. The control crosses yielded, in most cases, the expected 1:1 sex ratio in the F1 progeny. Crosses between intersex individuals and females yielded a 1:3 (male:female) sex ratio in most crosses. According to our hypothesis, one-third of the females produced in a cross of a female with an intersex animal should be WW females. The hypothesis was tested by crossing normal males with F1 females, which were progeny of intersex fathers. These crosses yielded almost 100% females, a finding that conforms to the above-suggested sex determination model for C. quadricarinatus and the female WZ genotype of intersex individuals.

Animals↗
PubMed2004

Population structure of Macrobrachium australiense (Decapoda: Palaemonidae) in Western Queensland, Australia: the role of contemporary and historical processes.

Rivers of Western Queensland, Australia, represent a discontinuous and variable aquatic habitat for the freshwater fauna of the region. Rivers periodically fluctuate between being highly fragmented, with numerous disconnected waterholes and ephemeral channels, and being highly connected by a dominant system of anastomosing channels. We used mitochondrial sequences to investigate the genetic structure and inferred patterns of dispersal associated with this flow regime for the freshwater prawn, Macrobrachium australiense (Decapoda: Palaemonidae), sampling 28 localities throughout eight catchments. Based on a 505 base pair fragment of mitochondrial cytochrome c oxidase subunit I, we identified 98 haplotypes in a sample of 402 individuals. The haplotypes clustered into two main clades corresponding geographically to the major drainages: the Lake Eyre and Murray-Darling basins. Populations of M. australiense inhabiting the two basins appear to have diverged around 800,000 years ago (estimated sequence divergence of 1.6%). Analysis of population differentiation indicated contemporary high levels of genetic subdivision and restricted gene flow among populations within and among catchments. Phylogenetic analysis detected a series of historical range expansions in the region and we suggest that climate fluctuations during the Pleistocene have resulted in extensive floods that have promoted historical movements of aquatic organisms across catchment boundaries.

Animals↗
PubMedDate not supplied

Embryonic expression patterns of the Hox genes of the crayfish Procambarus clarkii (Crustacea, Decapoda).

Higher crustaceans (class Malacostraca) represent the most species-rich and morphologically diverse group of non-insect arthropods. The superorders Eucarida and Peracarida, two large groups that separated over 350 million years ago, encompass most malacostracan diversity. Recently, the Hox genes of the peracarid woodlouse Porcellio scaber(Isopoda) were shown to be expressed in domains that coincide with morphological boundaries of body tagmata, which differ from those in insects (Abzhanov and Kaufman 1999a,b). Moreover, observed changes in Hox expression domains during ontogeny correlate with morphological remodeling, such as a transformation of the first thoracic leg into mouthpart maxillipeds, which occurs in the trunk of the embryo. Decapods have a different modification of the malacostracan bodyplan, with up to three pairs of maxillipeds and extensive fusion and cephalization of the thorax. Here we describe expression patterns of the trunk Hox genes Scr, Antp, Ubx, abd-A and cad in the eucarid crayfish Procambarus clarkii (Decapoda). We find that the crayfish expression patterns, for the most part, resemble those of the woodlouse Porcellio scaber(Isopoda), but are more modulated and complex. Nevertheless, as in Porcellio the boundaries of the Hox expression domains do correlate with morphological features and their modulations to transformations in the embryo. Thus we propose that the trunk Hox genes were likely important in the evolution of and currently play an essential role in the development of the complex decapod bodyplan.

Amino Acid Sequence↗
PubMed1997

Digging in sand crabs (Decapoda, Anomura, Hippoidea): interleg coordination

Sand crabs (Decapoda, Anomura, Hippoidea) are highly specialised for digging into sand using their thoracic legs. Using video-recording and electromyography, we examined the digging leg movements of three species of sand crabs belonging to two families: Blepharipoda occidentalis (Albuneidae), Lepidopa californica (Albuneidae) and Emerita analoga (Hippidae). The digging patterns of all three species are similar. The ipsilateral legs 2 and 3 are tightly coupled and shovel sand forward from underneath the animal, whereas the movements of leg 4 are more variable, apparently stirring up sand and providing the purchase for rearward descent into the sand. The digging patterns of B. occidentalis and L. californica resemble each other more than either resembles that of E. analoga. In the albuneids, leg 4 cycles at the same frequency as legs 2 and 3, and both albuneid species switch gait from bilateral alternation to synchrony midway through digging. In E. analoga, right and left legs 2 and 3 always alternate. Legs 4 can cycle at about twice the frequency of legs 2 and 3, and they tend to move in bilateral synchrony during high-frequency leg movements (e.g. at the start of digging); their bilateral coupling becomes variable during low-frequency movements. Sand crab digging may have originated as a modified form of walking, but this behavioural innovation subsequently diverged in the sand crab superfamily.

Journal Article↗
PubMed1983

[Immunochemical study of the proteins of various tissues in Crustacea (Decapoda): nature, role, origin].

The main proteins of the haemolymph of Crustacea Decapoda have been identified and analysed: haemocyanin, plasma coagulogen, heteroagglutinins, vitellogenins, and molt-related proteins. All these complex components exhibit a high molecular weight and as oligomeric fractions are able to aggregate or dissociate in subunits according to the composition of medium and experimental procedures. Besides their important rôle in the defense mechanism, some proteins are involved in the edification of diverse tissues. They are detected within different compartments: soft integument, calcified carapace and hepatopancreas. They are either in transit or sequestered or synthetized within these tissues. In the crayfish Astacus leptodactylus, some components have been identified in different compartments: --in aqueous extracts from soft integument: the haemocyanin, coagulogen and both fraction F1 (lipoprotein with an approximate molecular weight of 45 kdal) and fraction F2 related to the molt. Both coagulogen and fraction F2 appear sometimes as melanized. These two latter fractions exhibit some glucose-mannose residues and they occur with a higher relative amount than in the blood. --in soluble extracts from calcified cuticle: among the numerous fractions showing a high molecular weight, the haemocyanin and coagulogen are detected. --in aqueous extracts from hepatopancreas: both haemocyanin and coagulogen appear with a little relative amount. Components termed as Fa and Fb are found with a high concentration. One minor fraction is also detected. --in aqueous extracts from eggs: the haemocyanin and fraction Fb are present. Other proteins showing only some antigenic identities with those of the haemolymph are also detected in all these tissues. The haemolymph proteins are not present within these compartments following a passive diffusion. Indeed, their relative amount varies according to the tissue investigated and is different from that found in the blood. Except the haemocyanin detected in all tissues with different aggregation states, the haemolymph proteins identified vary in the organs studied. A qualitative and quantitative selection occurs when the blood proteins enter the other compartments. Perhaps some other proteins are not detected following alterations underwent either in the epithelial barriers or during the tannage process or the chitino-proteic complex formation or due to experimental procedures. On the other hand, each tissue has its own proteins. The integument contains crustacyanins alpha, beta, gamma; the eggs are mainly constituted of lipovitellins and the hepatopancreas is rich in small molecular weight proteins and digestive enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2003

Autapomorphies of the endophragmal system in trichodactylid freshwater crabs (Crustacea: Decapoda: Eubrachyura).

An examination of the thoracic endophragmal system in trichodactylid freshwater crabs revealed several derived features that appear restricted to this family. Trichodactylids have a highly reduced sella turcica with a rim-like overall configuration; as a consequence of sella turcica reduction the median septum is dorsoventrally diminished and exposed along its length. In addition, interosternite 7/8 is medially erased with the remnants restricted to the lateral regions of the sternum. The configurations of the sella turcica and interosternite 7/8 in trichodactylids underscore the monophyly of this family. The Dilocarcininae is characterized by having interosternites 5/6 through 7/8 restricted to the lateral sectors of the sternum, the lateral remnants of interosternite 4/5 forming prominent, rib-like ridges oriented diagonally to the longitudinal axis of the crab, and the median septum forming with interosternite 4/5 a Y-shaped pattern. These autapomorphies of the endophragmal system separate the trichodactylids from all other eubrachyurans and emphasize the morphological distinctness of the group. A description of the trichodactylid endophragmal junction plate is also provided.

Animals↗
PubMed2006

Spermatozoal ultrastructure in three Atlantic solenocerid shrimps (Decapoda, Dendrobranchiata).

The spermatozoal ultrastructure in three solenocerid shrimps (Solenocera membranacea, S. africana, and Pleoticus muelleri) from different Atlantic locations was examined with the aim of increasing understanding of the phylogenetic relationships in the Dendrobranchiata. A considerable structural similarity between the sperm of these species and those of penaeid shrimps supports a close affinity between the Penaeidae and Solenoceridae. However, significant differences in the sperm morphology of the previously investigated sicyoniids (namely, a greater complexity of the acrosomal complex) suggest evolutionary separation of the Sicyoniidae from the assemblage Penaeidae-Solenoceridae. Two ultrastructural features distinguish the spermatozoa of the three studied solenocerids from penaeid sperm: 1) separation of the plasma and acrosome membranes at the base of the spike and anterior region of the cap, and 2) asymmetry of the acrosomal cap, which appears to be a synapomorphy of the group. No striking ultrastructural differences were found between the spermatozoa of the closely related species S. membranacea and S. africana, whereas a great number of morphological differences separate the spermatozoa of Pleoticus from those of Solenocera (e.g., shape of the acrosomal cap, structural arrangement of the contents of the whole acrosome vesicle, thickness and distribution of the cytoplasm, and external shape of the spike).

Animals↗
PubMed2000

Penaeidins, a family of antimicrobial peptides from penaeid shrimp (Crustacea, Decapoda).

The production of antimicrobial peptides represents a first-line host defense mechanism of innate immunity that is widespread in nature. Only recently such effectors were isolated in crustacean species, whereas numerous antimicrobial peptides have been characterized from other arthropods, both insects and chelicerates. This review presents findings on a family of antimicrobial peptides, named penaeidins, isolated from the shrimp Penaeus vannamei. Their structure and antimicrobial properties as well as their immune function will be discussed through analyses of penaeidin gene expression and peptide distribution upon microbial challenge.

Amino Acid Sequence↗
PubMed2006

Impact of waterborne copper on the structure of gills and hepatopancreas and its impact on the content of metallothionein in juvenile giant freshwater prawn Macrobrachium rosenbergii (Crustacea: Decapoda).

This study aims to elucidate both the impact of copper on the structure of the gills and hepatopancreas and the induction of metallothionein (MT) during waterborne copper exposure in juvenile Macrobrachium rosenbergii. Structural observations were performed with light microscopy, and the MT titrations were performed with the cadmium saturation assay. The structural changes that occurred in the gills and hepatopancreas appeared to result from copper accumulation, and the degree of damage observed in both tissues was relevant to the elevated waterborne copper concentration. Exposure to copper concentrations ranging from 0.01 mg/L to 0.4 mg/L for 7 days resulted in profound structural changes including the accumulation of hemocytes in the hemocoelic space; swelling and fusion of the lamellae; abnormal gill tips; and hyperplastic, necrotic, and clavate-globate lamellae in the gills. Similarly, hemocytic infiltration in the interstitial sinuses, an increased number of hemocytes, thickening and ruptures of the basal laminae, and necrosis of the tubules were observed in the hepatopancreas. The MT measurements showed no significant differences in MT contents between the control group and the group treated with 0.01 mg/L waterborne copper. The maximum MT content was observed at the level of 0.4 mg/L waterborne copper.

Animals↗
PubMed2002

Genetic diversity of attached bacteria in the hindgut of the deposit-feeding shrimp Neotrypaea (formerly Callianassa) californiensis (decapoda: thalassinidae).

Microbial colonization of marine invertebrate guts is widespread, but in general the roles that these bacteria play in the nutrition of their hosts are unknown. To examine the diversity and potential nutritional roles of hindgut microbiota in a deposit feeder, PCR-amplified 16S rRNA genes were cloned from the bacterial community attached to the hindguts of the thalassinid shrimp Neotrypaea californiensis exposed to different feeding treatments. Partial 16S rDNA sequences were analyzed for 30 clones for three shrimp per treatment for a total of 270 clones. No effects of host starvation or high-protein diets were apparent on hindgut bacterial community composition. Diversity analyses indicated high variability between bacterial communities in individual shrimp hindguts, but partial 16S rDNA sequences revealed remarkable species-level similarity (>98%) within clusters of sequences from the different shrimp hindguts, and many sequences from different shrimp hindguts were identical. Sequences belonged to three main groups of bacteria: Cytophaga-Flavobacteria-Bacteroides (CFB), proteobacteria, and gram-positives. Of the 270 sequences, 40% belonged to the alpha-proteobacteria, > or = 5% each to the gamma- and epsilon -proteobacteria, and > or =20% each to the gram-positive and CFB groups. All except one sequence are novel with < or = 95% sequence similarity to known genes. Despite weak similarity to known taxa,about 75% of the sequences were most closely related to known symbiotic and sedimentary bacteria. The bacteria in shrimp hindguts represent new species that have not yet been en-countered in other environments, and gut environments may be a rich source of the difficult-to-culture and novel components of marine bacterial diversity.

Animals↗
PubMed2006

Stages and other aspects of the embryology of the parthenogenetic Marmorkrebs (Decapoda, Reptantia, Astacida).

The early development of the parthenogenetic Marmorkrebs (marbled crayfish) is described with respect to external morphology, cell lineage, and segment formation. Due to its parthenogenetic reproduction mode, the question arises whether or not the marbled crayfish is a suitable model organism for developmental approaches. To address this question, we describe several aspects of the embryonic development until hatching. We establish ten stages based on characteristic external changes in the living eggs such as blastoderm formation, gastrulation process, formation and differentiation of the naupliar and post-naupliar segments, limb bud differentiation, and eye differentiation. The study of the post-naupliar cell division patterns, segment formation, and engrailed expression reveals distinct similarities to that of other freshwater crayfish. On this basis, we evaluate the possibility of a generalization of ontogenetic processes in the Marmorkrebs for either freshwater crayfish or other crustacean developmental systems.

Animals↗
PubMed2004

Ontogeny of the antennal glands in the crayfish Astacus leptodactylus (Crustacea, Decapoda): immunolocalization of Na+,K+-ATPase.

The involvement of the antennal urinary glands in the ontogeny of osmoregulatory functions was investigated during the development of Astacus leptodactylus by measurements of hemolymph and urine osmolality in juvenile and adult crayfish and by the immunodetection of the enzyme Na+,K+-ATPase. In stage II juveniles, 1-year-old juveniles, and adults, all of which were maintained in freshwater, urine was significantly hypotonic to hemolymph. In adults, chloride and sodium concentrations were much lower in urine than in hemolymph. During embryonic development, Na+,K+-ATPase was detected by immunocytochemistry in ionocytes lining the tubule and the bladder, at an eye index (EI) of 220-250 microm, and in the labyrinth, at EI 350 microm. In all regions, immunofluorescence was mainly located at the basolateral side of the cells. No immunofluorescence was detected at any stage in the coelomosac. In late embryonic stages (EI 410-440 microm), in stage I juveniles, and in adults, strong positive immunofluorescence was found from the labyrinth up to and including the bladder. These results show that, as early as hatching, juvenile crayfish are able to produce dilute urine hypotonic to hemolymph. This ability originates from the presence of Na+,K+-ATPase in ion-transporting cells located in the labyrinth, the tubule, and the bladder of the antennal glands and constitutes one of the main adaptations of crayfish to freshwater.

Animals↗