Project description:The circadian rhythm is the most general and important rhythm in biological organisms. In this study, continuous 24 h video recordings showed that the cumulative movement distance and duration of the abalone, Haliotis discus hannai reached their maximum values between 20:00–00:00, but both were significantly lower between 08:00–12:00 than at any other time of day or night (P < 0.05). To investigate the causes of these diel differences in abalone movement behavior, their cerebral ganglia were harvested at 00:00 (group D) and 12:00 (group L) to screen for differentially expressed proteins using tandem mass tagging (TMT) quantitative proteomics. Seventy-five significantly different proteins were identified in group D vs. group L. Acetylcholinesterase (AChE) was found three times, and its expression levels differed significantly between day and night (P < 0.05). A cosine rhythm analysis found that the concentration of acetylcholine (Ach) and the expression levels of AchE tended to be low during the day and high at night, and high during the day and low at night, respectively.
Project description:Abalone amyotrophia is a viral disease that causes mass mortality of juvenile Haliotis discus and H. madaka. Although the cause of this disease has yet to be identified, we had previously postulated a novel virus with partial genome sequence similarity to that of African swine fever virus is the causative agent and proposed abalone asfa-like virus (AbALV) as a provisional name. In this study, three species of juvenile abalone (H. gigantea, H. discus discus, and H. diversicolor) and four species of adult abalone (the above three species plus H. discus hannai) were experimentally infected, and their susceptibility to AbALV was investigated by recording mortality, quantitatively determining viral load by PCR, and conducting immunohistological studies. In the infection test using 7-month-old animals, H. gigantea, which was previously reported to be insusceptible to the disease, showed multiplication of the virus to the same extent as in H. discus discus, resulting in mass mortality. H. discus discus at 7 months old showed abnormal cell masses, notches in the edge of the shell and brown pigmentation inside of the shell, which are histopathological and external features of this disease, while H. gigantea did not show any of these characteristics despite suffering high mortality. Adult abalones had low mortality and viral replication in all species; however, all three species, except H. diversicolor, became carriers of the virus. In immunohistological observations, cells positive for viral antigens were detected predominantly in the gills of juvenile H. discus discus and H. gigantea, and mass mortality was observed in these species. In H. diversicolor, neither juvenile nor adult mortality from infection occurred, and the AbALV genome was not increased by experimental infection through cohabitation or injection. Our results suggest that H. gigantea, H. discus discus and H. discus hannai are susceptible to AbALV, while H. diversicolor is not. These results confirmed that AbALV is the etiological agent of abalone amyotrophia.
Project description:Asymmetric development, in which functional differences occur between left-right symmetrical organs, is widespread in organisms, including fish and mollusks. However, the asymmetry of symmetrical sensory structures in Haliotis discus hannai, a gastropod with a sensitive sensory system, remains unknown. This study analyzed the transcriptomes of three sensory structures (eyestalks, cephalic tentacles, and epipodial tentacles) to explore potential asymmetries in this species. RNA-seq revealed functional differences in sensory ability and sperm-egg recognition between right and left eyestalks, with cephalic tentacles displaying asymmetry in cytoskeletal organization and cell cycle regulation. Epipodial tentacles showed similar asymmetries, including immune response differences. Moreover, the cAMP-protein kinase A (PKA)-CREB-binding protein (CBP) signaling pathway responded asymmetrically, with PKA responding to activators and inhibitors on both sides and CBP showing a stronger response on the right. These findings provide insights into sensory asymmetry in mollusks and guidance for further investigations of the molecular mechanisms underlying asymmetry in symmetrical organs.