The mitochondrial genome of Bottapotamon fukienense (Brachiura: Potamidae) is fragmented into two chromosomes.

BACKGROUND: China is the hotspot of global freshwater crab diversity, but their wild populations are facing severe pressures associated with anthropogenic factors, necessitating the need to map their taxonomic and genetic diversity and design conservation policies. RESULTS: Herein, we sequenced the mitochondrial genome of a Chinese freshwater crab species Bottapotamon fukienense, and found that it is fragmented into two chromosomes. We confirmed that fragmentation was not limited to a single specimen or population. Chromosome 1 comprised 15,111 base pairs (bp) and there were 26 genes and one pseudogene (pseudo-nad1) encoded on it. Chromosome 2 comprised 8,173 bp and there were 12 genes and two pseudogenes (pseudo-trnL2 and pseudo-rrnL) encoded on it. Combined, they comprise the largest mitogenome (23,284 bp) among the Potamidae. Bottapotamon was the only genus in the Potamidae dataset exhibiting rearrangements of protein-coding genes. Bottapotamon fukienense exhibited average rates of sequence evolution in the dataset and did not differ in selection pressures from the remaining Potamidae. CONCLUSIONS: This is the first experimentally confirmed fragmentation of a mitogenome in crustaceans. While the mitogenome of B. fukienense exhibited multiple signs of elevated mitogenomic architecture evolution rates, including the exceptionally large size, duplicated genes, pseudogenisation, rearrangements of protein-coding genes, and fragmentation, there is no evidence that this is matched by elevated sequence evolutionary rates or changes in selection pressures.

Mangrovimonas cancribranchiae sp. nov., a novel bacterial species associated with the gills of the fiddler crab Cranuca inversa (Brachyura, Ocypodidae) from Red Sea mangroves.

Two bacteria, UG2_1T and UG2_2, were isolated from the gill tissues of the mangrove fiddler crab Cranuca inversa collected on the east coast of the Red Sea (Thuwal, Saudi Arabia). The cells are Gram-negative, rod-shaped, orange-pigmented, motile by gliding with no flagella, strictly aerobic, and grow at 20-37 °C (optimum, 28-35 °C), at pH 5.0-9.0 (optimum, pH 6.0-7.0), and with 1-11 % (w/v) NaCl (optimum, 2-4 %). They were positive for oxidase and catalase activity. Phylogenetic analysis based on 16S rRNA gene sequences indicated that isolates UG2_1T and UG2_2 belong to the genus Mangrovimonas, showing the highest similarity to Mangrovimonas spongiae HN-E26T (99.4 %). Phylogenomic analysis based on the whole genomes, independently using 49 and 120 concatenated genes, showed that strains UG2_1T and UG2_2 formed a monophyletic lineage in a different cluster from other type strain species within the genus Mangrovimonas. The genome sizes were 3.08 and 3.07 Mbp for UG2_1T and UG2_2, respectively, with a G+C content of 33.8 mol% for both strains. Values of average nucleotide identity and digital DNA-DNA hybridization between the strains and closely related species were 91.0 and 43.5 %, respectively. Chemotaxonomic analysis indicated that both strains had iso-C15 : 0 and iso-C15 : 1 G as dominant fatty acids, and the primary respiratory quinone was identified as MK-6. The major polar lipids comprised phosphatidylethanolamine, one unidentified glycolipid, one unidentified phospholipid, two unidentified aminolipids, and four unidentified lipids. Based on phylogenetic, phylogenomic, genome relatedness, phenotypic, and chemotaxonomical data, the two isolates represent a novel species within the genus Mangrovimonas, with the proposed name Mangrovimonas cancribranchiae sp. nov., and the type strain UG2_1T (=KCTC 102158T=DSM 117025T).

Biological and physiological responses of marine crabs to ocean acidification: A review.

Marine crabs play an integral role in the food chain and scavenge the debris in the ecosystem. Gradual increases in global atmospheric carbon dioxide cause ocean acidification (OA) and global warming that leads to severe consequences for marine organisms including crabs. Also, OA combined with other stressors like temperature, hypoxia, and heavy metals causes more severe adverse effects in marine crabs. The present review was made holistic discussion of information from 111 articles, of which 37 peer-reviewed original research papers reported on the effect of OA experiments and its combination with other stressors like heavy metals, temperature, and hypoxia on growth, survival, molting, chitin quality, food indices, tissue biochemical constituents, hemocytes population, and biomarker enzymes of marine crabs. Nevertheless, the available reports are still in the infancy of marine crabs, hence, this review depicts the possible gaps and future research needs on the impact of OA on marine crabs.

Incidence of mud crab reovirus (MCRV) outbreak in polyculture ponds of Andhra Pradesh, south east coast of India.

Reovirus designated as Mud crab reovirus (MCRV) is associated with the mass mortalities of mud crabs resulting in significant economic loss to crab and shrimp-mud crab polyculture farmers in the Nagayalanka, Krishna district, Andhra Pradesh. The 100 % chronic mass mortalities have been attributed to the outbreak of Mud crab reovirus (MCRV) in the polyculture farms. The moribund crabs showed autotomy, discoloration of carapace, loss of appetite, slow movement and loose gills. Histopathological observations of the infected mud crabs showed an atrophied hepatopancreas, complete degeneration of tissues along with viral inclusions in hepatopancreas, gills and muscles. Further analysis using Transmission electron microscopy (TEM), showed that the viral particles had a diameter of 70 nm and exhibited a non-enveloped, icosahedral shape arranged in a crystalline manner. The virus mainly infects the connective tissue of hepatopancreas, gills, muscle and develops in the cytoplasm. RT-PCR reconfirmed the presence of reovirus in the hepatopancreas of spontaneously infected mud crab Scylla serrata. The current study shows the importance of monitoring the MCRV prevalence in polyculture farms to minimize its spread and precautionary measures can be taken by screening the brooders from the crab hatchery and stocking of wild crabs without screening should be avoided in order to prevent MCRV outbreak.

Overcoming research challenges: In vitro cultivation of Ameson portunus (Phylum Microsporidia).

Ameson portunus is an intracellular pathogen that infects marine crabs Portunus trituberculatus and Scylla paramamosain, causing significant economic losses. However, research into this important parasite has been limited due to the absence of an in vitro culture system. To address this challenge, we developed an in vitro cultivation model of A. portunus using RK13 cell line in this study. The fluorescent labeling assay indicated a high infection rate (∼60 %) on the first day post-infection and quantitative PCR (qPCR) detection demonstrated successful infection as early as six hours post-inoculation. Fluorescence in situ hybridization (FISH) and qPCR were used for the detection of A. portunus infected cells. The FISH probe we designed allowed detection of A. portunus in infected cells and qPCR assay provided accurate quantification of A. portunus in the samples. Transmission electron microscopy (TEM) images revealed that A. portunus could complete its entire life cycle and produce mature spores in RK13 cells. Additionally, we have identified novel life cycle characteristics during the development of A. portunus in RK 13 cells using TEM. These findings contribute to our understanding of new life cycle pathways of A. portunus. The establishment of an in vitro culture model for A. portunus is critical as it provides a valuable tool for understanding the molecular and immunological events that occur during infection. Furthermore, it will facilitate the development of effective treatment strategies for this intracellular pathogen.

Paragonimiasis.

Paragonimiasis is a zoonotic disease caused by lung flukes of the genus Paragonimus. Humans usually become infected by eating freshwater crabs or crayfish containing encysted metacercariae of these worms. However, an alternative route of infection exists: ingestion of raw meat from a mammalian paratenic host. Adult worms normally occur in pairs in cysts in the lungs from which they void their eggs via air passages. The pulmonary form is typical in cases of human infection due to P. westermani, P. heterotremus, and a few other species. Worms may occupy other sites in the body, notably the brain, but lung flukes have made their presence felt in almost every organ. Ectopic paragonimiasis is particularly common when infection is due to members of the P. skrjabini complex. Human paragonimiasis occurs primarily in the tropics and subtropics of Asia, Africa, and the Americas, with different species being responsible in different areas (Table 6.1).

BnaCRCs with domestication preference positively correlate with the seed-setting rate of canola.

Canola (Brassica napus) is an important oil crop worldwide. The seed-setting rate (SS) is a critical factor in determining its yield, and the development of pistils affects pollination and seed sets. However, research on seed-setting defects has been limited owing to difficulties in the identification of phenotypes, mutations, and complex genetic mechanisms. In this study, we found a stigma defect (sd) mutant in B. napus, which had no nectary. The SS of sd mutants in the field was approximately 93.4% lower than that of the wild type. Scanning and transmission electron microscopy imaging of sd mutants showed a low density of stigma papillary cells and stigma papillary cell vacuoles that disappeared 16 h after flowering. Genetic analysis of segregated populations showed that two recessive nuclear genes are responsible for the mutant phenotype of sd. Based on re-sequencing and map-based cloning, we reduced the candidate sites on ChrA07 (BnaSSA07) and ChrC06 (BnaSSC06) to 30 and 67 kb, including six and eight predicted genes, respectively. Gene analyses showed that a pair of CRABS CLAW (CRC) homeologous genes at BnaSSA07 and BnaSSC06 were associated with the development of carpel and nectary. BnaSSA07.CRC and BnaSSC06.CRC candidate genes were found to be expressed in flower organs only, with significant differences in their expression in the pistils of the near-isogenic lines. DNA sequencing showed transposon insertions in the upstream region and intron of the candidate gene BnaSSA07.crc. We also found that BnaSSC06.crc exists widely in the natural population and we give possible reasons for its widespread existence.

Identifying the genes involved in the egg-carrying ovigerous hair development of the female blue crab Callinectes sapidus: transcriptomic and genomic expression analyses.

BACKGROUND: Crustacean female sex hormone (CFSH) controls gradually developing adult female-specific morphological features essential for mating and brood care. Specifically, ovigerous hairs are developed during the prepuberty molt cycle of the blue crab Callinectes sapidus that are essential for carrying the eggs until they finish development. Reduced CFSH transcripts by CFSH-dsRNA injections result in fewer and shorter ovigerous hairs than the control. This study aimed to identify the specific genes responsible for ovigerous hair formation using transcriptomic, genomic and expression analyses of the ovigerous setae at three stages: prepuberty at early (OE) and late premolt (OL), and adult (AO) stages. RESULTS: The de novo Trinity assembly on filtered sequence reads produced 96,684 Trinity genes and 124,128 transcripts with an N50 of 1,615 bp. About 27.3% of the assembled Trinity genes are annotated to the public protein sequence databases (i.e., NR, Swiss-Prot, COG, KEGG, and GO databases). The OE vs. OL, OL vs. AO, and OE vs. AO comparisons resulted in 6,547, 7,793, and 7,481 differentially expressed genes, respectively, at a log2-fold difference. Specifically, the genes involved in the Wnt signaling and cell cycle pathways are positively associated with ovigerous hair development. Moreover, the transcripts of ten cuticle protein genes containing chitin-binding domains are most significantly changed by transcriptomic analysis and RT-qPCR assays, which shows a molt-stage specific, down-up-down mode across the OE-OL-AO stages. Furthermore, the expression of the cuticle genes with the chitin-binding domain, Rebers and Riddiford domain (RR)-1 appears at early premolt, followed by RR-2 at late premolt stage. Mapping these 10 cuticle protein sequences to the C. sapidus genome reveals that two scaffolds with a 549.5Kb region and 35 with a 1.19 Mb region harbor 21 RR1 and 20 RR2 cuticle protein genes, respectively. With these findings, a putative mode of CFSH action in decapod crustaceans is proposed. CONCLUSIONS: The present study describes a first step in understanding the mechanism underlying ovigerous hair formation in C. sapidus at the molecular level. Overall, demonstrating the first transcriptome analysis of crustacean ovigerous setae, our results may facilitate future studies into the decapod female reproduction belonging to the suborder Pleocyemata.

Views from 'crabworld': the spatial distribution of light in a tropical mudflat.

Natural scene analysis has been extensively used to understand how the invariant structure of the visual environment may have shaped biological image processing strategies. This paper deals with four crucial, but hitherto largely neglected aspects of natural scenes: (1) the viewpoint of specific animals; (2) the fact that image statistics are not independent of the position within the visual field; (3) the influence of the direction of illumination on luminance, spectral and polarization contrast in a scene; and (4) the biologically relevant information content of natural scenes. To address these issues, I recorded the spatial distribution of light in a tropical mudflat with a spectrographic imager equipped with a polarizing filter in an attempt to describe quantitatively the visual environment of fiddler crabs. The environment viewed by the crabs has a distinct structure. Depending on the position of the sun, the luminance, the spectral composition, and the polarization characteristics of horizontal light distribution are not uniform. This is true for both skylight and for reflections from the mudflat surface. The high-contrast feature of the line of horizon dominates the vertical distribution of light and is a discontinuity in terms of luminance, spectral distribution and of image statistics. On a clear day, skylight intensity increases towards the horizon due to multiple scattering, and its spectral composition increasingly resembles that of sunlight. Sky-substratum contrast is highest at short wavelengths. I discuss the consequences of this extreme example of the topography of vision for extracting biologically relevant information from natural scenes.

Evolutionary trade-offs in osmotic and ionic regulation and expression of gill ion transporter genes in high latitude, cold clime Neotropical crabs from the 'end of the world'.

Osmoregulatory findings on crabs from high Neotropical latitudes are entirely lacking. Seeking to identify the consequences of evolution at low temperature, we examined hyperosmotic/hypo-osmotic and ionic regulation and gill ion transporter gene expression in two sub-Antarctic Eubrachyura from the Beagle Channel, Tierra del Fuego. Despite sharing the same osmotic niche, Acanthocyclus albatrossis tolerates a wider salinity range (2-65‰ S) than Halicarcinus planatus (5-60‰ S); their respective lower and upper critical salinities are 4‰ and 12‰ S, and 63‰ and 50‰ S. Acanthocyclus albatrossis is a weak hyperosmotic regulator, while H. planatus hyperosmoconforms; isosmotic points are 1380 and ∼1340 mOsm kg-1 H2O, respectively. Both crabs hyper/hypo-regulate [Cl-] well with iso-chloride points at 452 and 316 mmol l-1 Cl-, respectively. [Na+] is hyper-regulated at all salinities. mRNA expression of gill Na+/K+-ATPase is salinity sensitive in A. albatrossis, increasing ∼1.9-fold at 5‰ compared with 30‰ S, decreasing at 40-60‰ S. Expression in H. planatus is very low salinity sensitive, increasing ∼4.7-fold over 30‰ S, but decreasing at 50‰ S. V-ATPase expression decreases in A. albatrossis at low and high salinities as in H. planatus. Na+/K+/2Cl- symporter expression in A. albatrossis increases 2.6-fold at 5‰ S, but decreases at 60‰ S versus 30‰ S. Chloride uptake may be mediated by increased Na+/K+/2Cl- expression but Cl- secretion is independent of symporter expression. These unrelated eubrachyurans exhibit similar systemic osmoregulatory characteristics and are better adapted to dilute media; however, the expression of genes underlying ion uptake and secretion shows marked interspecific divergence. Cold clime crabs may limit osmoregulatory energy expenditure by hyper/hypo-regulating hemolymph [Cl-] alone, apportioning resources for other energy-demanding processes.

Common fear molecules induce defensive responses in marine prey across trophic levels.

Predator-prey interactions are a key feature of ecosystems and often chemically mediated, whereby individuals detect molecules in their environment that inform whether they should attack or defend. These molecules are largely unidentified, and their discovery is important for determining their ecological role in complex trophic systems. Homarine and trigonelline are two previously identified blue crab (Callinectes sapidus) urinary metabolites that cause mud crabs (Panopeus herbstii) to seek refuge, but it was unknown whether these molecules influence other species within this oyster reef system. In the current study, homarine, trigonelline, and blue crab urine were tested on juvenile oysters (Crassostrea virginica) to ascertain if the same molecules known to alter mud crab behavior also affect juvenile oyster morphology, thus mediating interactions between a generalist predator, a mesopredator, and a basal prey species. Oyster juveniles strengthened their shells in response to blue crab urine and when exposed to homarine and trigonelline in combination, especially at higher concentrations. This study builds upon previous work to pinpoint specific molecules from a generalist predator's urine that induce defensive responses in two marine prey from different taxa and trophic levels, supporting the hypothesis that common fear molecules exist in ecological systems.

Molecular Phylogeny of Thoracotreme Crabs Including Nine Newly Determined Mitochondrial Genomes.

Mitochondrial genomes are used widely for the molecular phylogenetic analysis of animals. Although phylogenetic analyses based on the mitogenomes of brachyurans often yield well-resolved phylogenies, most interfamilial phylogenetic relationships in Thoracotremata remain unclear. We determined nine new mitogenomes of Thoracotremata, including mitogenomes of Camptandriidae (Deiratonotus japonicus), Dotillidae (Ilyoplax integra, Ilyoplax pusilla, and Tmethypocoelis choreutes), Macrophthalmidae (Ilyograpsus nodulosus), Pinnotheridae (Arcotheres sp. and Indopinnixa haematosticta), Plagusiidae (Guinusia dentipes), and Percnidae (Percnon planissimum). Interestingly, Percnon planissimum (Percnidae) was found to possess ≥ 19 repeated sequences in the control region. The gene orders of Il. nodulosus, Arcotheres sp., and In. haematosticta were revealed to be unique among thoracotreme crabs. Although the results of Bayesian and maximum likelihood (ML) phylogenetic analyses of three datasets were incongruent, highly supported clades (PP ≥ 0.99 or BS ≥ 99%) were not contradictory among the analyses. All analyses suggested the paraphyly of Grapsoidea and Ocypodoidea, corroborating the findings of previous studies based on molecular phylogenies of thoracotreme crabs. The phylogenetic positions of symbiotic thoracotreme crabs, Pinnotheridae and Cryptochiridae, were highly supported (Pinnotheridae + Ocypodidae and Cryptochiridae + Grapsidae, respectively) for the Bayesian analyses but not for the ML analyses. Analyses of more thoracotreme species' mitogenome sequences in additional studies will further strengthen the framework for thoracotreme evolution.

Eyestalk neuropeptide identification in the female red deep-sea crab, Chaceon quinquedens.

Eyestalk-derived neuropeptides, primarily the crustacean hyperglycemic hormone (CHH) neuropeptide family, regulate vitellogenesis in decapod crustaceans. The red deep-sea crab, Chaceon quinquedens, a cold-water species inhabiting depths between 200 and 1800 m, has supported a small fishery, mainly harvesting adult males in the eastern US for over 40 years. This study aimed to understand the role of eyestalk-neuropeptides in vitellogenesis in C. quinquedens with an extended intermolt stage. Chromatography shows two CHH and one MIH peak in the sinus gland, with a CHH2 peak area four times larger than CHH1. The cDNA sequence of MIH and CHH of C. quinquedens is isolated from the eyestalk ganglia, and the qPCR assay shows MIH is significantly higher only at ovarian stages 3 than 4 and 5. However, MIH transcript and its neuropeptides do differ between stages 1 and 3. While CHH transcripts remain constant, its neuropeptide levels are higher at stages 3 than 1. Additionally, transcriptomic analysis of the de novo eyestalk ganglia assembly at ovarian stages 1 and 3 found 28 eyestalk neuropeptides. A GIH/VIH or GSH/VSH belonging to the CHH family is absent in the transcriptome. Transcripts per million (TPM) values of ten neuropeptides increase by 1.3 to 2.0-fold at stage 3 compared to stage 1: twofold for Bursicon α, followed by CHH, AKH/corazonin-like, Pyrokinin, CCAP, Glycoprotein B, PDH1, and IDLSRF-like peptide, and 1.3-fold of allatostatin A and short NP-F. WXXXRamide, the only downregulated neuropeptide, decreases TPM by âˆ¼ 2-fold at stage 3, compared to stage 1. Interestingly, neuroparsin with the highest TPM values remains the same in stages 1 and 3. The mandibular organ-inhibiting hormone is not found in de novo assembly. We report that CHH, MIH, and eight other neuropeptides may play a role in vitellogenesis in this species.

Investigating conspecific CsRV1 transmission in Callinectes sapidus.

A reo-like virus, CsRV1, is found in blue crabs, Callinectes sapidus, from every North American location assessed, including Chesapeake Bay and the Atlantic and Gulf coasts, USA and associated with blue crabs in softshell production. CsRV1-associated crab mortality is prevalent in captive crabs, but it is still unknown how CsRV1 is transmitted. The purpose of this study was to examine the role that conspecific predation or scavenging may play in per os transmission in single exposure and repeated exposure experiments. For viruses without cell culture propagation, repeated exposure experiments have the challenge of presenting the virus consistently during the experiment and across time replicates. In a single-exposure experiment, none of the crabs fed muscle tissue of crabs carrying intense infections of CsRV1 developed CsRV1 infections. In a repeated-exposure trial, using infected muscle tissue prepared in alginate blocks, CsRV1 was detected in 11% of the crabs fed infected tissue but was not significantly different from the control group fed alginate lacking CsRV1. For repeated per os exposure experiments, the study demonstrated the utility of using alginate to present the same homogenous sample of virus, both injected and per os, over time for oral challenge experiments. Conspecific predation and scavenging could be a transmission route, but future work into this and other possible routes of transmission for CsRV1 is important to better understand the role this virus plays in wild crab populations and the soft-shell crab industry.

The origin and evolution of carpels and fruits from an evo-devo perspective.

The flower is an evolutionary innovation in angiosperms that drives the evolution of biodiversity. The carpel is integral to a flower and develops into fruits after fertilization, while the perianth, consisting of the calyx and corolla, is decorative to facilitate pollination and protect the internal organs, including the carpels and stamens. Therefore, the nature of flower origin is carpel and stamen origin, which represents one of the greatest and fundamental unresolved issues in plant evolutionary biology. Here, we briefly summarize the main progress and key genes identified for understanding floral development, focusing on the origin and development of the carpels. Floral ABC models have played pioneering roles in elucidating flower development, but remain insufficient for resolving flower and carpel origin. The genetic basis for carpel origin and subsequent diversification leading to fruit diversity also remains elusive. Based on current research progress and technological advances, simplified floral models and integrative evolutionary-developmental (evo-devo) strategies are proposed for elucidating the genetics of carpel origin and fruit evolution. Stepwise birth of a few master regulatory genes and subsequent functional diversification might play a pivotal role in these evolutionary processes. Among the identified transcription factors, AGAMOUS (AG) and CRABS CLAW (CRC) may be the two core regulatory genes for carpel origin as they determine carpel organ identity, determinacy, and functionality. Therefore, a comparative identification of their protein-protein interactions and downstream target genes between flowering and non-flowering plants from an evo-devo perspective may be primary projects for elucidating carpel origin and development.

Tomato CRABS CLAW paralogues interact with chromatin remodelling factors to mediate carpel development and floral determinacy.

CRABS CLAW (CRC) orthologues play a crucial role in floral meristem (FM) determinacy and gynoecium formation across angiosperms, the key developmental processes for ensuring successful plant reproduction and crop production. However, the mechanisms behind CRC mediated FM termination are far from fully understood. Here, we addressed the functional characterization of tomato (Solanum lycopersicum) paralogous CRC genes. Using mapping-by-sequencing, RNA interference and CRISPR/Cas9 techniques, expression analyses, protein-protein interaction assays and Arabidopsis complementation experiments, we examined their potential roles in FM determinacy and carpel formation. We revealed that the incomplete penetrance and variable expressivity of the indeterminate carpel-inside-carpel phenotype observed in fruit iterative growth (fig) mutant plants are due to the lack of function of the S. lycopersicum CRC homologue SlCRCa. Furthermore, a detailed functional analysis of tomato CRC paralogues, SlCRCa and SlCRCb, allowed us to propose that they operate as positive regulators of FM determinacy by acting in a compensatory and partially redundant manner to safeguard the proper formation of flowers and fruits. Our results uncover for the first time the physical interaction of putative CRC orthologues with members of the chromatin remodelling complex that epigenetically represses WUSCHEL expression through histone deacetylation to ensure the proper termination of floral stem cell activity.

Experimental infection of Enterocytozoon hepatopanaei parasite (EHP) of penaeid shrimp in Indian marine crabs.

Enterocytozoon hepatopanaei parasite (EHP) is identified as an emerging pathogenic microsporidium parasite in shrimp culture industry. Though the etiology, disease pattern and sustainability of shrimp are well known, significantly less research has been carried out about the disease transmission and symptoms of infected aquatic animals. The present study aims is to determine the disease carrier status of five different species of Indian marine crabs (Scylla olivacea, Scylla serrata, Portunus pelagicus, Ocypode quadrata and Portunus sanquinolentus) using EHP. At the first instance, oral infection and intramuscular injection were performed to determine the susceptibility of the parasite at 50 days post-infection and it was observed that there was no mortality. The experimental infected crabs were confirmed by polymerase chain reaction, bioassay and histopathology. The crabs were EHP-PCR positive at 5th day post-infection (d.p.i) in gills, heart, hepatopancreas, haemolymph and muscle tissue. However, after 5th d.p.i EHP was PCR negative in all the tissue samples. There were no mortalities and histological changes in the negative group and experimental group. Therefore, marine crabs are found to be not suitable hosts for replicating EHP spores but crabs fecal matters are PCR positive till 5th d.p.i. Therefore, marine crabs are having the possibilities of acceptance as a vector for Enterocytozoon hepatopanaei in shrimp. Shrimp farmers need to take necessary action to control this deadly infection in shrimp ponds.

Would Antarctic Marine Benthos Survive Alien Species Invasions? What Chemical Ecology May Tell Us.

Many Antarctic marine benthic macroinvertebrates are chemically protected against predation by marine natural products of different types. Antarctic potential predators mostly include sea stars (macropredators) and amphipod crustaceans (micropredators) living in the same areas (sympatric). Recently, alien species (allopatric) have been reported to reach the Antarctic coasts, while deep-water crabs are suggested to be more often present in shallower waters. We decided to investigate the effect of the chemical defenses of 29 representative Antarctic marine benthic macroinvertebrates from seven different phyla against predation by using non-native allopatric generalist predators as a proxy for potential alien species. The Antarctic species tested included 14 Porifera, two Cnidaria, two Annelida, one Nemertea, two Bryozooa, three Echinodermata, and five Chordata (Tunicata). Most of these Antarctic marine benthic macroinvertebrates were chemically protected against an allopatric generalist amphipod but not against an allopatric generalist crab from temperate waters. Therefore, both a possible recolonization of large crabs from deep waters or an invasion of non-native generalist crab species could potentially alter the fundamental nature of these communities forever since chemical defenses would not be effective against them. This, together with the increasing temperatures that elevate the probability of alien species surviving, is a huge threat to Antarctic marine benthos.

Temnosewellia aff. vietnamensis (Platyhelminthes: Rhabdocoela: Temnocephalidae) associated with freshwater crabs from Kagoshima, southern Japan, with review of records of the genus from East to South Asian countries.

Temnocephalids are ectosymbionts of various freshwater animals. A species tentatively identified as Temnosewellia aff. vietnamensis (Platyhelminthes: Rhabdocoela: Temnocephalidae) is reported based on materials collected from the body surface of the freshwater crabs Eriocheir japonica (Brachyura: Varunidae) and Geothelphusa exigua (Potamidae) in Kagoshima, southern Japan. The temnocephalid is characterized as follows: the cirrus composed of a cone-shaped shaft and a cylindrical introvert 42-77 µm long; the introvert covered with approximately 30 vertical rows of fine sharp spines; the four seminal receptacles; and a long, curved oviduct with vaginal gland; a pair of gland cells (Haswell's cells) present anterior to the excretory ampullae. Bayesian inference trees using partial nuclear 28S rDNA (28S) and mitochondrial cytochrome c oxidase subunit I (COI) genes supported that the specimens collected from both crab species are conspecific but these also showed the geographical variations among them on both 28S and COI. The previous records of the genus Temnosewellia in East to South Asian countries are assembled and shown on the map (fig.7, this paper).

Inhibition of Oocyte Maturation in the Estuarine Crab Neohelice Granulata, by the Effect of Anti-Inflammatory Drugs.

The drugs ibuprofen and diclofenac were assessed in vivo on adult females of the estuarine crab Neohelice granulata. In a first, preliminary assay comprising 60-d, a significant (p < 0.05) lower content of total vitellogenic proteins was detected in the ovary at 10 mg/L of each drug. In a second 90-d assay, comprising the exposure of crabs to 5 mg/L of each drug during the entire pre-reproductive period, a significant (p < 0.05) decrease in the proportion of vitellogenic oocytes was observed by effect of diclofenac. The same effect was also observed in a third assay only comprising the last month of the pre-reproductive period, at 5 mg/L of diclofenac, and also at a mixture of both drugs; besides, this mixture significantly (p < 0.05) increased the proportion of reabsorbed vitellogenic oocytes. The obtained results indicate that the effect of diclofenac is critical at the final stage of ovarian maturation, when the participation of prostaglandins is relevant.