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In caridean shrimps, sexual systems vary from gonochorism to various forms of hermaphroditism. The shrimp Salmoneus carvachoi has been reported to exhibit both male (appendix masculina) and female (brooding embryos) anatomical characteristics simultaneously. Our aim was to examine the sexual system of S. carvachoi and to test the hypothesis of protandric simultaneous hermaphroditism (PSH) in this species. We analysed internal and external features using microscopy and histology techniques. Our analyses support the hypothesis of PSH in S. carvachoi and enabled the identification of male-phase and hermaphroditic individuals. All individuals exhibit a well-developed appendix masculina on the endopods of the second pleopods; however, small male-phase individuals possess only male gonopores, whereas larger hermaphroditic individuals possess both female and male gonopores. Hermaphrodites exhibit both male and female germinative cells in various stages of development, as well as an androgenic gland. Our study describes a novel sexual system for alpheids and provides a detailed description of anatomical traits in S. carvachoi. Studies that describe sexual systems in Alpheidae may shed light on the evolutionary history of gender expression in carideans and how environmental conditions favour sex allocation in decapods and other invertebrates. [ABSTRACT FROM AUTHOR]

BACKGROUND: The anode material of bioelectrochemical systems (BES) is crucial because its characteristics directly affect electron transfer from the bacteria to the anode. To assess its usefulness, each material must undergo evaluation under relevant operating conditions, as well as a complete electrochemical characterization. RESULTS: Five carbonaceous materials – carbon brush (CB), carbon granules (CG), thicker carbon felt (CF1), high‐conductivity carbon felt (CF2), and high‐active‐area carbon felt (CF3) – anodes were tested in this work. The current generation with each anode material was studied, operating as a microbial fuel cell (MFC) and microbial electrolysis cell (MEC). Two MFC inoculation strategies were tested: (i) fixed 10 Ω external resistance (ER) and (ii) poised anode potential (PA) of 200 mV versus Ag/AgCl. Once reproducible cycles were obtained in MFC operation, CB yielded the highest maximum current density, amounting to 15.9 A m−2. A slightly reduced start‐up time was observed for each anode with PA than ER. When the anodes were transferred to MEC operation, the maximum hydrogen production rate of 1.04 m3 H2 m−3 d−1 was obtained for CB. CONCLUSION: This study helps in selecting anode material for BES, allowing a shortening of the start‐up time and improving its performance using different inoculation strategies and anode materials. Among all the anode materials employed in this study, CB and CF3 electrodes presented the best overall performance. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The boring giant clam Tridacna crocea is an evolutionary, ecologically, economically, and culturally important reef-dwelling bivalve targeted by a profitable ornamental fishery in the Indo-Pacific Ocean. In this study, we developed genomic resources for T. crocea. Using low-pass (=low-coverage, ~6×) short read sequencing, this study, for the first time, estimated the genome size, unique genome content, and nuclear repetitive elements, including the 45S rRNA DNA operon, in T. crocea. Furthermore, we tested if the mitochondrial genome can be assembled from RNA sequencing data. The haploid genome size estimated using a k-mer strategy was 1.31–1.39 Gbp, which is well within the range reported before for other members of the family Cardiidae. Unique genome content estimates using different k-mers indicated that nearly a third and probably at least 50% of the genome of T. crocea was composed of repetitive elements. A large portion of repetitive sequences could not be assigned to known repeat element families. Taking into consideration only annotated repetitive elements, the most common were classified as Satellite DNA which were more common than Class I-LINE and Class I-LTR Ty3-gypsy retrotransposon elements. The nuclear ribosomal operon in T. crocea was partially assembled into two contigs, one encoding the complete ssrDNA and 5.8S rDNA unit and a second comprising a partial lsrDNA. A nearly complete mitochondrial genome (92%) was assembled from RNA-seq. These newly developed genomic resources are highly relevant for improving our understanding of the biology of T. crocea and for the development of conservation plans and the fisheries management of this iconic reef-dwelling invertebrate. [ABSTRACT FROM AUTHOR]

Air‐cathode microbial fuel cells (AC‐MFC) use a gas‐diffusion‐layer (GDL) coating based on polytetrafluoroethylene applied to the cathode to prevent electrolyte leakage. However, this type of GDL can also lead to a decrease in MFC performance due to electron‐transfer limitation, mass‐transfer limitation or catalyst availability. This study provides a comprehensive understanding of the significance of the GDL coating, demonstrating the interaction between the number of GDL coatings and the external resistance (Rext) used. An experimental design in 28 mL AC‐MFCs was prepared and conducted using two different Rext (10 and 249 Ω) and four different GDL coatings (1 to 4 layers). The coating effect was not significant when operating with a high Rext, where the electron transfer was the limiting process. However, when the Rext was low, the amount of polytetrafluoroethylene limited the cathode performance due to a significant decrease in the Pt availability on the catalytic surface. Thus, GDL‐1 with 10 Ω as Rext reached 0.96 mA/cm2, 3‐fold higher than that obtained with 249 Ω as Rext (ca. 0.30 mA/cm2). Besides, the current density did not vary noticeably in the other cathodes with 249 Ω as Rext. Contrarily, the current density with 10 Ω as Rext decreased as the number of GDL increased (0.74, 0.57 and 0.37 for GDL‐2, GDL‐3 and GDL‐4 respectively). These values agreed with those of the polarization curve. Furthermore, limitations were also observed in electrochemical impedance spectroscopy measurements: the charge resistance increased with the number of GDL, related to the ease of electron flow. These values were18 Ω, 22 Ω, 53 Ω and 58 Ω for GDL‐1, GDL‐2, GDL‐3 and GDL‐4, respectively, for both 10 and 249 Ω cathodes. [ABSTRACT FROM AUTHOR]

The sea louse Caligus rogercresseyi is the most important pathogen causing "caligidosis" in the Chilean salmon industry. In this study, using cox1 gene, we evaluate the genetic variation of C. rogercresseyi from farmed Salmo salar along a latitudinal range (40°–52°S) in south Chile to determine whether morphological differences are explained by genetic or environmental factors. Female parasites were randomly collected from S. salar at five farms. Body variation was examined using multivariate analyses and genetic heterogeneity was explored with AMOVA. C. rogercresseyi exhibited significant morphometric variability among sites and parasites collected from >54°S were the longest ones. Parasites did not show genetic structure among farms. Thus, C. rogercresseyi infesting salmons is panmictic along an extensive latitudinal range in south Chile. The same genetic pattern can be explained by the frequent movement of parasitized S. salar among farms in that region. Phenotypic plasticity in parasites could be explained by natural or aquaculture‐mediated environment variability. C. rogercreseyi from 54°S could favor the local spread of this disease, suggesting an immediate health risk for the recent salmon industry in that region. Further research is required to confirm genetic homogeneity of this parasite along its geographical distribution using more powerful markers (e.g. SNPs). [ABSTRACT FROM AUTHOR]

The complete larval development of the spider crab Maguimithrax spinosissimus (Lamarck, 1818) is re-described and illustrated in detail from laboratory-reared material. The development consisted of the typical pattern reported for the Majoidea, two zoeal stages and one megalopa. The complete larval development from hatching to first crab lasted 5–6 days at temperatures that ranged between 24–28 °C. Both zoeal stages of M. spinosissimus exhibited moderate reduction in the number of setae in the maxilla and maxillipeds, from the first to the second zoeal stage, when compared with other closely related species. Maguimithrax spinosissimus can be easily distinguished from other species belonging to the closely related genus Mithrax by the (i) setation of the endopod of the maxillule, maxilla and second maxilliped in both zoeal stages; (ii) setation of the scaphognathite of the maxilla in the first zoeal stage; (iii) setation of the basis of maxilliped I in the second zoeal stage and megalopa; (iv) morphology of the antennule and antenna in the second zoeal stage; and (v) setation of the antennule, coxal endite of maxilla, and exopod of second maxilliped in the megalopa. All these characters support the recent generic status of Maguimithrax within the Mithracidae. Additional morphological details, not available previously, are provided. This study will provide support for conservation strategies in this species. [ABSTRACT FROM AUTHOR]

Eusociality is a highly conspicuous and ecologically impactful behavioral syndrome that has evolved independently across multiple animal lineages. So far, comparative genomic analyses of advanced sociality have been mostly limited to insects. Here, we study the only clade of animals known to exhibit eusociality in the marine realm—lineages of socially diverse snapping shrimps in the genus Synalpheus. To investigate the molecular impact of sociality, we assembled the mitochondrial genomes of eight Synalpheus species that represent three independent origins of eusociality and analyzed patterns of molecular evolution in protein-coding genes. Synonymous substitution rates are lower and potential signals of relaxed purifying selection are higher in eusocial relative to noneusocial taxa. Our results suggest that mitochondrial genome evolution was shaped by eusociality-linked traits—extended generation times and reduced effective population sizes that are hallmarks of advanced animal societies. This is the first direct evidence of eusociality impacting genome evolution in marine taxa. Our results also strongly support the idea that eusociality can shape genome evolution through profound changes in life history and demography. [ABSTRACT FROM AUTHOR]

Robinione overstreeti is a bopyrid isopod endemic to the Gulf of Mexico that inhabits the branchial chamber of the ghost shrimp Callichirus islagrande. Information on this host–parasite association is scant. This study describes population and reproductive features of R. overstreeti and its host. A total of 90 (9.97%) out of 903 individuals of C. islagrande collected from Tamiahua lagoon, Veracruz, Mexico, between April 2012 and October 2013, were parasitized by R. overstreeti. Parasite prevalence in male and female ghost shrimps was similar. However, no parasitized ovigerous females of C. islagrande were recorded, suggesting that R. overstreeti is a parasitic castrator. Host and parasite body sizes were positively correlated suggesting early host infestation by parasites and simultaneous growth of the host and parasite. Parasitic isopods frequently inhabited the same branchial chamber (n = 77) of ghost shrimps as adult male-female pairs. Females were occasionally found with supernumerary juveniles and cryptoniscus larvae in the same host individual, and rarely solitarily. Furthermore, the body size of paired adult male and female parasites was tightly correlated suggesting long-term 'social' monogamy in R. overstreeti. Fecundity in R. overstreeti varied between 1668 and 9884 embryos female−1 and increased with female body size. [ABSTRACT FROM AUTHOR]

Abstract Sulfur oxide emissions can lead to acidic precipitation and health concerns. Flue gas desulfurization (FGD) systems treat these emissions generating a wastewater with high-sulfate content. This work is the first attempt to treat this effluent with bioelectrochemical systems (BES) in order to recover elemental sulfur, a technology that allows the treatment of several wastewaters that lack of electron donor. The sulfate treatment and elemental sulfur recovery have been studied in a biocathode with simultaneous sulfate reduction to sulfide and partial sulfide oxidation, comparing the performance obtained with synthetic and real wastewater. A decrease of the sulfate removal rate (SRR) from 108 to 73 mg S-SO 4 2− L−1 d−1 was observed coupled to an increase in the elemental sulfur recovery from 1.4 to 27 mg S-S0 L−1 d−1. This elemental sulfur recovered as a solid from the real wastewater represented a 64% of the theoretical elemental sulfur produced (the elemental sulfur corresponded to a 72% of the solid weight). In addition, microbial communities analysis of the membrane and cathode biofilms and planktonic biomass showed that the real wastewater allowed a higher growth of sulfur oxidizing bacteria (SOB) adapted to more complex waters as Halothiobacillus sp. while decreasing the relative abundance of sulfate reducing bacteria (SRB). Graphical abstract Unlabelled Image Highlights • Treatment of sulfate from real flue gas desulfurization wastewater in a biocathode • Slight decrease of sulfate removal rate from synthetic to real wastewater • 64% of sulfate removed was recovered as elemental sulfur with a purity of 71.8%. • Simultaneous growth of SRB and SOB allows high elemental sulfur production from sulfate. [ABSTRACT FROM AUTHOR]