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Sperm morphology provides an abundant source of potentially informative characters for gastropod taxonomy. In the present study, this character was used to offer additional information concerning the genus Babylonia (Mollusca, Gastropoda), the most promising economic marine gastropods of the present century. Light and transmission electron microscopy was used to study the ultrastructure of spermatozoa in five groups of Babylonia, including B. areolata populations from Hainan, China, from Thailand, and the reciprocal hybrid offspring of these two populations and B. lutosa. Principal component analysis was conducted to examine morphological differences of spermatozoa. The results showed that morphology can contribute to the classification of the two species B. areolata and B. lutosa. The reciprocal hybrid offspring of the two B. areolata varieties exhibited ultrastructure of spermatozoa similar to that of their male parents, and each showed greater similarity to the male parent in the fine structural details. This study aimed to compare the ultrastructure of sperm in five groups of Babylonia and to compare the differences between the parents and the hybrids to provide basic information for genetic studies of Babylonia. [ABSTRACT FROM AUTHOR]

Increases in atmospheric CO2 partial pressure have lowered seawater pH in marine ecosystems, a process called ocean acidification (OA). The effects of OA during the critical stages of larval development may have disastrous consequences for some marine species, including Babylonia areolata (Link 1807), a commercially important sea snail in China and South East Asia. To investigate how OA affects the proteome of Babylonia areolata, here we used label‐free proteomics to study protein changes in response to acidified (pH 7.6) or ambient seawater (pH 8.1) during three larvae developmental stages of B. areolata, namely, the veliger larvae before attachment (E1), veliger larvae after attachment (E2), and carnivorous juvenile snail (E3). In total, we identified 720 proteins. This result suggested that acidification seriously affects late veliger stage after attachment (E2). Further examination of the roles of differentially expressed proteins, which include glutaredoxin, heat‐shock protein 70, thioredoxin, catalase, cytochrome‐c‐oxidase, peroxiredoxin 6, troponin T, CaM kinase II alpha, proteasome subunit N3 and cathepsin L, will be important for understanding the molecular mechanisms underlying pH reduction. [ABSTRACT FROM AUTHOR]

Assessing the responses of lysozyme activity and antioxidant defences to hypoxia is important to understand the adaptation and tolerance strategies of fish under hypoxia. This study investigated the effects of different dissolved oxygen ( DO) levels on Carassius auratus, a natural triploid fish, from Qihe River. The content of malondialdehyde (MDA) and the activities of lysozyme and antioxidant enzymes were measured in the kidney and spleen after hypoxic exposure. At the DO concentrations of 1 and 2 mg L−1, the activities of antioxidant enzymes and lysozyme significantly decreased and the content of MDA significantly increased ( P < 0.01). This result suggests that hypoxia decreased antioxidant enzyme and lysozyme activities and caused MDA accumulation in a concentration-dependent manner. The DO level of 4 mg L−1 increased the activities of superoxide dismutase and catalase in the kidney and the activities of glutathione peroxidase and catalase in the spleen ( P < 0.05). This result implies that slight hypoxic stress can enhance antioxidant defences to alleviate the damage of oxidative stress. The reduced activities of antioxidant enzymes and the accumulation of MDA at the DO level of ≤2 mg L−1 implied the decrease in antioxidative ability and the occurrence of oxidative stress. The decrement in lysozyme activity indicated that the antibacterial ability was weakened to some degree. Therefore, hypoxic stress at DO levels ≤2 mg L−1 should be removed by aeration to avoid the oxidative damage resulting from the reduced antioxidative ability and prevent the outbreak of diseases caused by weakened antibacterial effects. [ABSTRACT FROM AUTHOR]

Using two-dimensional gel electrophoresis, the foot muscle proteome of three geographical populations of Haliotis diversicolor were examined, with a total of 922 ± 21 protein spots detected in the Japanese population ( JJ), 904 ± 25.6 in the Taiwanese population ( TT), and 936 ± 16.2 in the Vietnamese population ( VV). Of these, 254 spots showed differential expression and 85 protein spots percentage volumes varied more than twofold. Both 'genotype' and 'spot' analysis of variance approaches significantly showed differences among the three populations. Hierarchical clustering analysis showed that TT and VV clustered together followed by clustering with JJ, which is consistent with their geographical location. Following matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, 30 differentially expressed proteins involved in major biological processes including energy production and storage and stress response were identified. Of these proteins, proteins pertaining to muscle contraction and muscle protein regulation showed highest expression levels in VV samples. Proteins involved in energy production and storage, including ATP synthase beta subunit, fructose-1,6-bisphosphate aldolase, arginine kinase, enolase, triosephosphate isomerase, and tauropine dehydrogenase, showed diverse expression patterns among the three populations. For stress-responsive proteins, the expression of heat shock protein 70 was JJ > VV > TT. The expression pattern of Cu/Zn-superoxide dismutase was JJ > VV > TT. Overall, these results may aid in the detection of new differentially expressed proteins within three different abalone populations. [ABSTRACT FROM AUTHOR]

In recent years, the abalone aquaculture industry has been threatened by the bacterial pathogens. The immune responses mechanisms underlying the phagocytosis of haemocytes remain unclear in Haliotis discus hannai . It is necessary to investigate the immune mechanism in response to these bacterial pathogens challenges. In this study, the phagocytic activities of haemocytes in H. discus hannai were examined by flow cytometry combined with electron microscopy and transcriptomic analyses. The results of Vibrio parahaemolyticus , Vibrio alginolyticus and Staphylococcus aureu challenge using electron microscopy showed a process during phagosome formation in haemocytes. The phagocytic rate (PP) of S. aureus was higher than the other five foreign particles, which was about 63%. The PP of Vibrio harveyi was about 43%, the PP peak of V. alginolyticus in haemocyte was 63.7% at 1.5 h. After V. parahaemolyticus and V. alginolyticus challenge, acid phosphatase, alkaline phosphatase, total superoxide dismutase, lysozyme, total antioxidant capacity, catalase, nitric oxide synthase and glutathione peroxidase activities in haemocytes were measured at different times, differentially expressed genes (DEGs) were identified by quantitative transcriptomic analysis. The identified DEGs after V. parahaemolyticus challenge included haemagglutinin/amebocyte aggregation factor-like, supervillin-like isoform X4, calmodulin-like and kyphoscoliosis peptidase-like; the identified DEGs after V. alginolyticus challenge included interleukin-6 receptor subunit beta-like, protein turtle homolog B-like, rho GTPase-activating protein 6-like isoform X2, leukocyte surface antigen CD53-like, calponin-1-like, calmodulin-like, troponin C, troponin I-like isoform X4, troponin T-like isoform X18, tumor necrosis factor ligand superfamily member 10-like, rho-related protein racA-like and haemagglutinin/amebocyte aggregation factor-like. Some immune-related KEGG pathways were significantly up-regulated or down-regulated after challenge, including thyroid hormone synthesis, Th17 cell differentiation signalling pathway, focal adhesion, melanogenesis, leukocyte transendothelial migration, inflammatory mediator regulation of TRP channels, ras signalling pathway, rap1 signalling pathway. This study is the first step towards understanding the H. discus hannai immune system by adapting several tools to gastropods and providing a first detailed morpho-functional study of their haemocytes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Ma, Wu, Zhang, Zhang, Jiang, Shen, Wu, Chen and Di.)