RESUMEN

The family Diogenidae Ortmann, 1892 is a diverse and abundance group of hermit crabs, but their systematics and phylogenetic relationships are highly complex and unresolved. Herein, we gathered nucleotide sequence data from two mitochondrial (16S rRNA and COI) and two nuclear (NaK and PEPCK) genes for a total of 2,308 bp in length across 38 species from six extant diogenid genera. Molecular data were combined with 41 morphological characters to estimate the largest phylogeny of diogenid hermit crabs to date with the aim of testing the proposed taxonomic scheme of Diogenidae and addressing intergeneric relationships within this family. Despite conflicts between mitochondrial and nuclear DNA trees, the combined-data tree reflects the contributions of each dataset, and improves tree resolution and support for internal nodes. Contrary to traditional classification, our total evidence revealed a paraphyletic Diogenidae based on internally nested representatives of Coenobitidae Dana, 1851. Within Diogenidae, the studied diogenid hermit crabs were split between two clades with high support, which contradicts recent morphological classification scheme for Diogenidae sensu lato based on fossil records. The genus Diogenes Dana, 1851 was found nested inside Paguristes Dana, 1851, which formed a clade being separated from the remainder, pointing towards paraphyly in Paguristes. In another clade, Dardanus Paulson, 1875 occupied a basal position relative to the other diogenids, while Calcinus Dana, 1851 and Clibanarius Dana, 1852 showed sister relationships and formed a cluster with Ciliopagurus Forest, 1995. Among the morphological characters examined, carapace shield and telson were identified as phylogenetically significant for grouping diogenid genera, while phylogenetic insignificance of gill number was evidenced by its mosaic pattern in diogenid phylogeny. The present study sheds light on the controversial generic phylogeny of Diogenidae and highlights the necessity for thorough taxonomic revisions of this family as well as some genera (e.g., Paguristes) to reconcile current classifications with phylogenetic relationships.

Asunto(s)

RESUMEN

A green protocol to extract chitin from crab shells using water soluble ionic liquids (ILs) is here reported. Compared to conventional multistep acid-base extraction methods, this one-pot procedure achieves pulping of recalcitrant crustacean waste shells by employing ammonium acetate, ammonium formate and hydroxylammonium acetate as water-soluble, low-cost and easy to prepare ILs. An extensive parametric analysis of the pulping process has been carried out with different ILs, different ratios, temperature and time. The optimized protocol provides a high-quality chitin comparable, if not better, to commercial chitin. The best results were obtained at 150 °C with ammonium formate prepared in-situ from aqueous ammonia and formic acid: chitin was isolated in a 17 wt% yield (based on dried crab shells as starting biowaste), a degree of acetylation (DA) > 94 %, a crystallinity index of 39-46 %, a molecular weight up to 6.6 × 105 g/mol and a polydispersity of ca 2.0.

Asunto(s)

RESUMEN

Spiroplasma eriocheiris is a kind of intracellular pathogen without cell wall and the causative agent of Chinese mitten crab Eriocheir sinensis "tremor disease", which causes significant economic losses in the crustacean aquaculture. However, little is known about the intracellular transport of this pathogen and host innate immune response to this pathogen. Rab GTPases are key regulators for endocytosis and intracellular pathogen trafficking. In this study, we showed that S. eriocheiris infection upregulated the transcription of Rab7 through the downregulation of miR-131-3p. Subsequently, both hemocytes transfected with miR-131-3p mimics and hemocytes derived from Rab7 knockdown crabs exhibited reduced phagocytic activities and increased susceptibility to S. eriocheiris infection. Additionally, Rab7 could interact with the cell shape-determining protein MreB3 of S. eriocheiris, and its overexpression promoted S. eriocheiris internalization and fusion with lysosomes, thereby limiting S. eriocheiris replication in Drosophila S2 cells. Overall, these results demonstrated that Rab7 facilitated host cell phagocytosis and interacted with MreB3 of S. eriocheiris to prevent S. eriocheiris infection. Moreover, miR-131-3p was identified as a negative regulator of this process through its targeting of Rab7. Therefore, targeting miR-131-3p might be an effective strategy for controlling S. eriocheiris in crab aquaculture.

RESUMEN

Scylla paramamosain, an economically significant crab, is widely cultivated worldwide. In recent years, S. paramamosain has faced a serious threat from viral diseases due to the expansion of culture scale and increased culture density. Among these, mud crab dicistrovirus-1 (MCDV-1) stands out as highly pathogenic, presenting substantial challenges to the healthy development of mud crab aquaculture. Therefore, a comprehensive understanding of the mud crab immune response to MCDV-1 infection is imperative for devising effective disease prevention strategies. In this study, transcriptomic analyses were conducted on the hepatopancreas of mud crabs infected with MCDV-1. The findings revealed a total of 5139 differentially expressed genes (DEGs) between healthy and MCDV-1 infected mud crabs, including 3327 upregulated and 1812 downregulated DEGs. Further analysis showed that mud crabs resist MCDV-1 infection by activating humoral immune-related pathways, including the MAPK signaling pathway, MAPK signaling pathway-fly, and Toll and Imd signaling pathway. In contrast, MCDV-1 infection triggers host metabolic disorders. Several immune-related vitamin metabolism pathways (ascorbate and aldarate metabolism, retinol metabolism, and nicotinate and nicotinamide metabolism) were significantly inhibited, which may create favorable conditions for the virus's self-replication. Notably, endocytosis emerged as significantly upregulated both in GO terms and KEGG pathways, with several viral endocytosis-related pathways showing significant activation. PPI network analysis identified 9 hub genes associated with viral endocytosis within the endocytosis. Subsequent GeneMANIA analysis confirmed the association of these hub genes with viral endocytosis. Both transcriptome data and qPCR analysis revealed a significant upregulation of these hub genes post MCDV-1 infection, suggesting MCDV-1 may use viral endocytosis to enter cells and facilitate replication. This study represents the first comprehensive report on the transcriptomic profile of mud crab hepatopancreas response to MCDV-1 infection. Future investigations should focus on elucidating the mechanisms through which MCDV-1 enters cells via endocytosis, as this may holds critical implications for the development of vaccine targets.

RESUMEN

Fuel spills in marine environments pose significant threats to aquatic ecosystems, evidencing the intricate relationship between fuel utilization and its impact on benthic species of commercial value for human consumption. This interconnectedness of human, animal and environmental welfare falls within the One Health framework. The aim of the present study was to evaluate the toxicological effects of diesel oil on the green crab Carcinus maenas, and make a parallelism between tested concentrations and petrogenic hydrocarbon levels in natural environments. Mortality, locomotion and feeding behavior, molting, somatic growth, morphological malformations, stress biomarkers, and nutritional variables were analyzed in three different bioassays. In Bioassay 1, prepuberal females were exposed to diesel oil water accommodated fraction (WAF) to determine the median lethal concentration (LC50) at different periods. In Bioassay 2, prepuberal females were exposed to 168 h LC50 and LC25 of diesel oil WAF for 7 days, and were subsequently exposed to clean water. In Bioassay 3, prepuberal females were exposed to 168 h LC12 and LC6 of diesel oil WAF for 30 days. Petrogenic hydrocarbon levels in the field were quantified at a port and a nature reserve, with concentrations of aromatic hydrocarbons being 1.92 µg/g in the former and below 0.01 µg/g in the latter. In Bioassay 1, the 168 h LC50 was estimated to be 1.04 % of diesel oil. The results obtained in Bioassays 2 (LC50 and LC25) and Bioassays 3 (LC12 and LC6) suggest that environmental exposure to petrogenic hydrocarbons produces high mortality or interferes with the molting process of crabs, leading to reduced growth and developmental abnormalities. Such malformations were observed in chelipeds, pereiopods, gills chambers and eye peduncles, and affected feeding and locomotion behaviors. Overall, this could impact on population size and health, and consequently alter the ecological role and commercial exploitation of economically important species like C. maenas.

RESUMEN

Female Scylla olivacea has become more popular in Malaysia as emerging species mainly for soft-shell crabs and crab fattening (to increase weight, size and ovary maturation so that they can be sold at a higher price). To harvest crabs in soft-shell conditions and fattening, both conditions depend mostly on moulting events. To accelerate the moulting process, the manipulation of water parameter (salinity) and autotomy of the limb is commonly used. In this study, the evaluation of the moulting performances of full limb autotomy (the removal of all the appendages except for the swimming legs) and non-ablated (control) using immature S. olivacea cultured in three different salinity treatments (10 ppt, 20 ppt and 30 ppt) were performed. Results indicate there were significant differences between mud crab's culture duration, BW increments, growth performances and feeding efficiency with salinity. However, CW increments and survival indicate no significant effect with salinity. Meanwhile, limb autotomy proved to affect the culture duration, BW increments, survival and feeding efficiency of S. olivacea. The study concludes that both salinity and limb autotomy play significant roles in moulting performances of S. olivacea, with 20 ppt being the best salinity to stimulate S. olivacea moulting and development compared with the other two treatments (10 ppt and 30 ppt). Limb autotomy also indicates promising results as this technique proved to accelerate the moulting duration of S. olivacea with a 100% moulting percentage within 30 days. Therefore, the outcome would certainly benefit in the aquaculture production of this species of commercial importance mainly on soft-shell crabs production and also emerge as crabs fattening technique.

RESUMEN

BACKGROUND: There are multiple antibiotic regimens for the treatment of carbapenem-resistant Acinetobacter baumannii (CRAB) in clinical practice. We conducted this meta-analysis to compare the efficacy and safety of cefiderocol-based regimens and colistin-based regimens in the treatment of CRAB infections. METHODS: Two authors independently searched the PubMed, Web of Science, Embase, and Cochrane databases from their establishment to April 15, 2024, to search for randomized controlled trials (RCTs) or cohort studies, and compared the clinical efficacy and safety of cefiderocol-based regimens and colistin-based regimens in the treatment of CRAB infections. The Newcastle Ottawa Scale (NOS) checklist was used to evaluate the quality of the included studies. The primary outcome was all-cause mortality, and subgroup analysis was conducted on the basis of the site of infection and the risk of bias in the studies. Trial sequential analysis (TSA) was then conducted. RESULTS: Six observational studies were included, with 251 cases in the cefiderocol-based group and 372 cases in the colistin-based group. Compared to the colistin-based group, the cefiderocol-based group had lower all-cause mortality (RR = 0.71, 95% CI: 0.54-0.92, P = 0.01) and 30-day mortality (RR = 0.64, 95% CI: 0.43-0.95, P = 0.03). However, for the 14-day and 28-day mortality rates, there was no statistically significant difference between two groups. According to the subgroup analysis, among patients with bloodstream infection (BSI), the cefiderocol-based group had lower all-cause mortality, but it did not reduce the mortality of ventilator-associated pneumonia (VAP) patients. The result of TSA showed that our conclusions are reliable. There was no significant statistical difference in the microbiological cure rate, clinical cure rate, or duration of hospitalization. In addition, the cefiderocol-based group did not have an increased incidence of acute kidney injury (AKI). CONCLUSIONS: Compared with the colistin-based regimens, the cefiderocol-based regimens were significantly associated with a lower risk of mortality in CRAB-infected patients, especially for patients with BSI. However, they did not show any advantages in terms of the clinical cure rate or microbiological cure rate, nor did they reduce the incidence of AKI. PROSPERO REGISTRATION NUMBER: CRD42023487213.

Asunto(s)

RESUMEN

Introduction: Vibrio alginolyticus is a Gram-negative, rod-shaped bacterium belonging to the family of Vibrionaceae, a common pathogen in aquaculture animals, However, studies on its impact on Scylla serrata (mud crabs) are limited. In this study, we isolated V. alginolyticus SWS from dead mud crab during a disease outbreak in a Hong Kong aquaculture farm, which caused up to 70% mortality during summer. Methods: Experimental infection and histopathology were used to investigate the pathogenicity of V. alginolyticus SWS in S. serrata and validate Koch's postulates. Comprehensive whole-genome analysis and phylogenetic analysis antimicrobial susceptibility testing, and biochemical characterization were also performed. Results: Our findings showed that V. alginolyticus SWS caused high mortality (75%) in S. serrata with infected individuals exhibiting inactivity, loss of appetite, decolored and darkened hepatopancreas, gills, and opaque muscle in the claw. Histopathological analysis revealed tissue damage and degeneration in the hepatopancreas, gills, and claw muscle suggesting direct and indirect impacts of V. alginolyticus SWS infection. Conclusions: This study provides a comprehensive characterization of V. alginolyticus SWS as an emerging pathogen in S. serrata aquaculture. Our findings underscore the importance of ongoing surveillance, early detection, and the development of targeted disease management strategies to mitigate the economic impact of vibriosis outbreaks in mud crab aquaculture.

Asunto(s)

RESUMEN

Nitrite is a common environmental pollutant in intensive aquaculture systems. In this study, physiological and transcriptomic analyses were performed to investigate nitrite stress responses in the swimming crab Portunus trituberculatus, an important aquaculture species in China. The results revealed that nitrite can affect neurotransmitter signaling via the expression of neurotransmitter receptors such as octopamine receptor (OAR) and 5-hydroxytryptamine receptor (5-HTR), and depress ecdysteroid signaling by downregulating ecdysteroid receptor (EcR) as well as its downstream transcription factors in hepatopancreas. In addition, nitrite suppressed the expression of hemocyanins, the oxygen-transporting protein, which at least partly contributed to tissue hypoxia, resulting in a switchover of energy metabolism from aerobic to anaerobic pathway. To meet the energy demand, glycogens and lipids were mobilized and transported to the hemolymph, and the catabolism of amino acids and fatty acids was enhanced to provide energy for hepatopancreas. ß-oxidation of fatty acids, the major process by which fatty acids are oxidized to generate energy, seems to occur mainly not in mitochondria but in peroxisomes. Although the cellular protective mechanisms, including antioxidant defense, heat shock response (HSR), unfolded protein response (UPR), and autophagy, were activated, nitrite-induced cellular stress overwhelmed the repairing capacity and caused significant increase in the levels of apoptosis. These results indicated that nitrite stress influences neurotransmitter and endocrine signaling, disturbs energy metabolism, damages cellular components, and induces apoptosis in P. trituberculatus. The findings of this study provide new insights into nitrite stress response in the swimming crab and provide valuable information for aquaculture management of this species.

RESUMEN

BACKGROUND: The Infectious Diseases Society of America (IDSA) is committed to providing up-to-date guidance on the treatment of antimicrobial-resistant (AMR) infections. This guidance document focuses on infections caused by extended-spectrum ß-lactamase-producing Enterobacterales (ESBL-E), AmpC ß- lactamase-producing Enterobacterales (AmpC-E), carbapenem-resistant Enterobacterales (CRE), Pseudomonas aeruginosa with difficult-to-treat resistance (DTR P. aeruginosa), carbapenem-resistant Acinetobacter baumannii (CRAB), and Stenotrophomonas maltophilia. This updated document replaces previous versions of the guidance document. METHODS: A panel of six infectious diseases specialists with expertise in managing antimicrobial- resistant infections formulated questions about the treatment of infections caused by ESBL-E, AmpC-E, CRE, DTR P. aeruginosa, CRAB, and S. maltophilia. Because of differences in the epidemiology of AMR and availability of specific anti-infectives internationally, this document focuses on the treatment of AMR infections in the United States. RESULTS: Preferred and alternative suggested treatment approaches are provided with accompanying rationales, assuming the causative organism has been identified and antibiotic susceptibility results are known. Approaches to empiric treatment, transitioning to oral therapy, duration of therapy, and other management considerations are discussed briefly. Suggested approaches apply for both adult and pediatric populations, although suggested antibiotic dosages are provided only for adults. CONCLUSIONS: The field of AMR is highly dynamic. Consultation with an infectious diseases specialist is recommended for the treatment of AMR infections. This document is current as of December 31, 2023 and will be updated periodically. The most current version of this document, including date of publication, is available at www.idsociety.org/practice-guideline/amr-guidance/.

RESUMEN

The diagnosis of multiple myeloma (MM) is made based on the presence of either marrow clonal plasma cells > 10% or an extramedullary or bony plasmacytoma confirmed by biopsy. Additionally, at least one of the SLiM (sixty years, light chain ratio, magnetic resonance imaging)-CRAB (calcium elevation, renal insufficiency, anemia, and bone lesions) myeloma-defining events must be present. MM typically presents with symptoms such as fatigue due to anemia, kidney failure, hypercalcemia, and bone pain. It is uncommon, though, for MM to manifest as a single bone mass. We report the case of a 65-year-old male who did not fit the criteria for solitary bone plasmacytoma and presented with an unusual sternal tumor. The patient was diagnosed with MM despite not having any of the traditional symptoms such as low back pain, weight loss, anemia, or hypercalcemia. The diagnosis was based on a bone marrow examination, which showed 50% plasma cells. Radiation therapy and systemic chemotherapy were then used to treat him. The patient's symptoms, radiological findings, and biopsy results are described in detail, emphasizing the difficulty and intricacy of correctly diagnosing this uncommon manifestation of MM. This case highlights the need for a comprehensive and multidisciplinary strategy to diagnose and treat atypical presentations of MM, making sure that all possible diagnostic pathways are investigated in order to achieve accurate and timely diagnosis and treatment.

RESUMEN

Acinetobacter baumannii is an ESKAPE pathogen and threatens human health by generating infections with high fatality rates. A. baumannii leads to a spectrum of infections such as skin and wound infections, endocarditis, meningitis pneumonia, septicaemia and urinary tract infections. Recently, strains of A. baumannii have emerged as multidrug-resistant (MDR), meaning they are resistant to at least three different classes of antibiotics. MDR development is primarily intensified by widespread antibiotic misuse and inadequate stewardship. The World Health Organization (WHO) declared A. baumannii a precarious MDR species. A. baumannii maintains the MDR phenotype via a diverse array of antimicrobial metabolite-hydrolysing enzymes, efflux of antibiotics, impermeability and antibiotic target modification, thereby complicating treatment. Hence, a deeper understanding of the resistance mechanisms employed by MDR A. baumannii can give possible approaches to treat antimicrobial resistance. Resistance-nodulation-cell division (RND) efflux pumps have been identified as the key contributors to MDR determinants, owing to their capacity to force a broad spectrum of chemical substances out of the bacterial cell. Though synthetic inhibitors have been reported previously, their efficacy and safety are of debate. As resistance-modifying agents, phytochemicals are ideal choices. These natural compounds could eliminate the bacteria or interact with pathogenicity events and reduce the bacteria's ability to evolve resistance. This review aims to highlight the mechanism behind the multidrug resistance in A. baumannii and elucidate the utility of natural compounds as efflux pump inhibitors to deal with the infections caused by A. baumannii.

Asunto(s)

RESUMEN

Aquatic animals frequently undergo feed deprivation and starvation stress. It is well-known that the gut microbiota and the gut-brain short neuropeptide F (sNPF) play essential roles in diet restriction. Therefore, investigating the responses of the gut microbiota and sNPF can enhance our understanding of physiological adaptations to feed deprivation and starvation stress. In this study, we examined the alterations in the gut microbiota of juvenile mud crabs under feed deprivation and starvation conditions. The results reveal differences in the richness and diversity of gut microbiota among the satisfied, half food, and starvation groups. Moreover, the microbial composition was affected by starvation stress, and more than 30 bacterial taxa exhibited significantly different abundances among the three feeding conditions. These results indicate that the diversity and composition of the gut microbiota are influenced by diet restriction, potentially involving interactions with the gut-brain sNPF. Subsequently, we detected the location of sNPF in the brains and guts of mud crabs through immunofluorescence and investigated the expression profile of sNPF under different feeding conditions. The results suggest that sNPF is located in both the brains and guts of mud crabs and shows increased expression levels among different degrees of diet restriction during a 96 h period. This study suggested a potential role for sNPF in regulating digestive activities and immunity through interactions with the gut microbiota. In conclusion, these findings significantly contribute to our understanding of the dynamic changes in gut microbiota and sNPF, highlighting their interplay in response to diet restriction.

RESUMEN

Blood culture (BC) remains the reference diagnostic tool for bloodstream infections but is hampered by long turn-around time (TAT). This study evaluated the Vitek® Reveal™ (VR) system for rapid antimicrobial susceptibility testing (AST) with 72 cases of monomicrobial BCs (55 Enterobacterales, 12 Pseudomonas aeruginosa and 5 Acinetobacter baumannii), including isolates producing carbapenemases and/or extended-spectrum ß-lactamases. VR returned AST results with a mean TAT of 5.4 h. Compared to a conventional workflow based on broth microdilution, VR exhibited essential agreement (EA) and category agreement (CA) >90 % in most cases, except with meropenem for Enterobacterales (CA, 85.5 %), piperacillin/tazobactam for P. aeruginosa (EA, 83.3 %), and trimethoprim/sulfamethoxazole for A. baumannii (CA and EA, 80 %). Bias exhibited an underestimation trend with ceftazidime/avibactam (-78.9 %) and ceftazidime (-50 %) for Enterobacterales and P. aeruginosa, respectively. Overall, VR appears an interesting tool to decrease TAT of the BC workflow, although further evaluation with some antibiotic-pathogen combinations would be warranted.

RESUMEN

Freshwater crabs play essential roles in the well-functioning of the inland aquatic ecosystems. However, due to the lack of sufficient molecular resources, the study of freshwater crabs has been greatly hindered. In this study, the mitochondrial genome of Huananpotamon koatenense, a freshwater crab endemic to China, was sequenced for the first time. This mitogenome sequence is 15,528 bp long, and contains 13 protein-coding genes, 2 rRNA genes and 22 tRNA genes. Phylogenetic analyses based on 25 mitogenomes showed that H. koatenense was clustered with the known congeneric species of H. lichuanense.

RESUMEN

The sex-specific differences in the growth and population characteristics of the high-commercial-value sand crab Ovalipes punctatus were investigated in Korea. The estimated allometric growth between the sexes showed significant differences in all morphometric measurements. In the classification of growth types, carapace width-chela length exhibited positive and negative allometric growth in males and females, respectively. Carapace width-abdominal width showed positive relative growth in both sexes, and orbital spine width exhibited negative relative growth in both sexes. Consequently, sexual dimorphism was evident in all measured traits. Growth parameters estimated using the ELEFAN function of the FiSAT II program indicated higher values in males compared to females. Asymptotic length (CW∞) for males was estimated at 139.2 mm, whereas for females it was 116.6 mm. Additionally, the growth coefficient (K) was higher in males (0.65) than in females (0.54), suggesting faster growth in males. The winter point (WP) was 1 for males and 0.7 for females, indicating slower growth in males during the colder December and slower growth in females during the spawning period in August. The modified von Bertalanffy growth curves indicated asymptotic growth in all sexes, and the growth performance index (φ') showed higher values in males (4.10) compared to females (3.87), reflecting differences in growth curves. The steady increase in recruitment rates from July to September was associated with the appearance of larvae and their subsequent growth into juveniles, leading to their recruitment into the population during this period. Therefore, O. punctatus exhibited sex-specific differences in growth parameters, suggesting distinct growth strategies between the sexes.

Asunto(s)

RESUMEN

Environmental cues such as temperature induce macroscopic changes in the molting cycle of crustaceans, however, the physiological mechanisms behind these changes remain unclearWe aimed to investigate the regulatory mechanisms in the intermolt and premolt stages of the Callinectes sapidus molt cycle in response to thermal stimuli. The concentration of ecdysteroids and lipids in the hemolymph, and the expression of heat shock proteins (HSPs) and molt key genes were assessed at 19 °C, 24 °C and 29 °C. The premolt animals exhibited a much larger response to the colder temperature than intermolt animals. Ecdysteroids decreased drastically in premolt animals, whereas the expression of their hepatopancreas receptor (CasEcR) increased, possibly compensating for the low hemolymphatic levels at 19 °C. This decrease might be due to increased HSPs and inhibited ecdysteroidogenesis in the Y-organ. In addition, the molting-inhibiting hormone expression in the X-organ/sinus gland (XO/SG) remained constant between temperatures and stages, suggesting it is constitutive in this species. Lipid concentration in the hemolymph, and the expression of CasEcR and CasHSP90 in the XO/SG were influenced by the molting stage, not temperature. On the other hand, the expression of HSPs in the hepatopancreas is the result of the interaction between the two factors evaluated in the study. Our results demonstrated that temperature is an effective modulator of responses related to the molting cycle at the endocrine level and that temperature below the control condition caused a greater effect on the evaluated responses compared to the thermostable condition, especially when the animal was in the premolt stage.

Asunto(s)

RESUMEN

Offshore ocean aquaculture is expanding globally to meet the growing demand for sustainable food production. At the United Kingdom's largest longline mussel farm, we assessed the potential for the farm to improve the habitat suitability for commercially important crustaceans. Modelled distribution patterns (GAM & GLM) predicted the low complexity seabed beneath the mussel farm was 34-94 % less suitable for European lobster (Homarus gammarus) and brown crab (Cancer pagurus) than nearby rocky reefs. The mussel farm operations, however, contributed large amounts of living mussels and shell material to the seabed. Acoustic telemetry revealed that H.gammarus remained within the farm for between 2 and 283 days using both the farm anchors and areas of seabed dominated by fallen mussels for refuge. In contrast, C. pagurus movements showed no affinity to either the farm infrastructure or benthic habitat under the farm. Stable isotope analysis indicated a high dietary niche overlap in C. pagurus and H. gammarus (67.8 and 84.6 %) between the mussel farm (mixed muddy sediment) and nearby rocky reef. Our mixed-methods suggest that the mussel farm augments structural complexity on the seabed providing refuge and similar feeding opportunities for lobster and crab as their typical habitat on rocky reefs. Longline mussel farms can deliver profound biodiversity-positive effects through biogenic augmentation of degraded habitat for commercial species and potential for co-benefits to local fisheries.

Asunto(s)

RESUMEN

The genome of a new member of the Nimaviridae family has been sequenced. The Chionoecetes bairdi bacilliform virus (CbBV) causes Milky Hemolymph Syndrome (MHS) in Chionoecetes bairdi populations of the Pacific coast of Kamchatka. The CbBV genome is represented by double-stranded DNA with a length of 245,567 nucleotides containing 120 ORFs. Of these, 85 proteins had significant matches in the NCBI database, and 57 genes encoded capsid, envelope, tegument and nonstructural proteins. Comparative analysis of the genomes of CbBV and a number of representatives of the class nuclear arthropod large DNA viruses (NALDVs) made it possible to isolate 49 evolutionarily conserved orthologue core genes. Among them, 5 were multicopy genes, and 44 were single-copy genes. There were ancestral genes characteristic of all Naldaviricetes - per os infectivity complex genes, one DNA polymerase gene and one thymidylate synthase gene. Phylogenetic analysis of representatives of the Nimaviridae family revealed that the CbBV and Chionoecetes opilio bacilliform virus (CoBV) form an independent clade within the family separate from the clade containing WSSV strains. This is supported by data on the order and arrangement of genes in the genomes of nimaviruses that were identical within each clade but differed between them. In addition, a high identity of the genomes and proteomes of CbBV and CoBV (approximately 99%) was shown, and their identity with WSSV strains was no more than 33%. The data on the structure of the genome of the new virus that causes MHS in C. bairdi indicate that it belongs to the family Nimaviridae, genus Whispovirus. Thus, the CbBV infecting the commercially important species of Tanner crab in populations of the Pacific coast of Kamchatka is the second "wild" representative of replicating nimaviruses whose genome has been characterized after the CoBV that causes MHS in C. opilio in populations of the Sea of Japan. The discovery of a new member of the family that infects decapods indicates the prevalence of nimaviruses in marine ecosystems. The information obtained is important for understanding the evolution of representatives of the class of nuclear arthropod large DNA viruses. The discovery of a new nimavirus that causes MHS in Chionoecetes crabs, in contrast to the white spot syndrome (WSS) caused by WSSV strains, makes it relevant to identify two variants and possibly species within the family, namely, WSSV and Milky Hemolymph Syndrome virus (MHSV).

Asunto(s)

RESUMEN

Vibrio parahaemolyticus (V. parahaemolyticus) is a major bacterial pathogen found in brackish environments, leading to disease outbreaks and great economic losses in the mud crab industry. This study investigated the molecular mechanism of V. parahaemolyticus infecting mud crabs through genome sequencing analysis, survival experiments, and the expression patterns of related functional genes. A strain of V. parahaemolyticus with high pathogenicity and lethality was isolated from diseased mud crab in South China. The genome sequencing results showed that the genome size of V. parahaemolyticus was a circular chromosome of 3,357,271 bp, with a GC content of 45 %, containing 2985 protein-coding genes, denoted as V. parahaemolyticus LG2206. Genome analysis data revealed that a total of 113 adherence coding genes were obtained, including 120 virulence factor coding genes, 37 type III secretion system (T3SS) coding genes, and 277 sequences of T3SS effectors. Survival experiments showed that the mortality was 20 % within 96 h in the 1 × 104 CFU/mL infection group, 90 % in the 3.2 × 105 CFU/mL treatment group, and 100 % in the 1 × 106 CFU/mL treatment group. The LD50 of V. parahaemolyticus LG2206 was determined as 4.6 × 104 CFU/mL. Six genes of znuA and fliD (flagellin encoding genes), yscE and yscR (T3SS encoding genes), and nfuA and htpX (virulence factor encoding genes) were selected and validated by quantitative real-time PCR analysis after infection with 4.6 × 104 CFU/mL of V. parahaemolyticus LG2206 for 96 h. The expression of the six genes exhibited a significant up-regulation trend at all tested time points. The results indicated that the infestation-related genes screened in the experiment play important roles in the infestation process. This study provides timely and effective information to further analyze the molecular mechanism of V. parahaemolyticus infection and develop comprehensive measures for disease prevention and control.

Asunto(s)