Search

ABSTRACT In this study, shell length, shell width, shell height, apex height, and body weight of reciprocal hybrid abalone (Haliotis discus hannai [female] x H. gigantea [male] (DG) and H. [...]

ABSTRACT Amplified fragment length polymorphism (AFLP) analysis of the population genetic structure and genetic diversity of Haliotis discus hannai (D), Haliotis gigantea (G), and their reciprocal hybrids D ♀ X [...]

ABSTRACT Interspecific hybrid families of female Haliotis diversicolor x male H. discus discus were produced and analyzed using amplified fragment length polymorphism (AFLP) technology to reveal the genetic makeup of [...]

ABSTRACT Twelve half-sib groups and 36 full-sib groups of small abalone Haliotis diversicolor were obtained by the unbalanced nest design using artificial fertilization of 3 females by each male. Heritabilities [...]

ABSTRACT A total of 241 samples of small abalone (Haliotis diversicolor) from 8 full-sib families of market size were used in this experiment. Shell length ([X.sub.1]), shell width ([X.sub.2]), shell [...]

ABSTRACT In this study, effects of sperm concentration and gamete age on fertilization success of Haliotis discus hannai (D) x H. gigantea (G) were investigated. Results showed that the fertilization [...]

Settlement and metamorphosis is the key stage during which Haliotis discus hannai larvae change from planktonic to benthic life. Larvae tend to be highly sensitive to changes in the external environment, which can result in increased mortality. In the aquaculture industry, increasing the metamorphosis rate of larvae is considered to be a critical factor for increasing yield. In this study, we modified a recirculating aquaculture system (RAS) for dense rearing of abalone larvae. We set up five density groups (1, 5, 10, 20 and 40 ind/ml) and compared the effects of traditional aquaculture (TA) and the RAS on the hatching success rate, metamorphosis rate and the expression levels of metamorphosis‐related genes. At stocking densities of 1, 5 and 10 ind/ml, the survival rate, metamorphosis rate and expression levels of MIRP, α2ADR and DopR2 in both culture modes were significantly higher than those in the 20 and 40 ind/ml densities (p < 0.05). The metamorphosis rate and survival rate of larvae in the RAS groups were significantly higher than those in the TA groups (p < 0.05). Under TA at the 40 ind/ml stocking density, the dissolved oxygen concentration in the water declined and the TAN concentration significantly increased (p < 0.05). As the stocking density increased, the size of metamorphosed larvae under each mode tended to increase in both culture modes. In particular, when the density was highest, the time required for metamorphosis was significantly extended (p < 0.05). Based these results, use of the RAS with stocking density of 10 ind/ml would maintain a stable aquaculture water environment, prevent fertilized eggs from hatching or becoming densely aggregated before larval metamorphosis, and significantly increase the stocking density per unit water. These results provide an important reference for scaling up reproduction of larval abalone and further developing the culture mode for this economically important shellfish. [ABSTRACT FROM AUTHOR]

The nautilus, commonly known as a "living fossil," is endangered and may be at risk of extinction. The lack of genomic information hinders a thorough understanding of its biology and evolution, which can shed light on the conservation of this endangered species. Here, we report the first high‐quality chromosome‐level genome assembly of Nautiluspompilius. The assembled genome size comprised 785.15 Mb. Comparative genomic analyses indicated that transposable elements (TEs) and large‐scale genome reorganizations may have driven lineage‐specific evolution in the cephalopods. Remarkably, evolving conserved genes and recent TE insertion activities were identified in N. pompilius, and we speculate that these findings reflect the strong adaptability and long‐term survival of the nautilus. We also identified gene families that are potentially responsible for specific adaptation and evolution events. Our study provides unprecedented insights into the specialized biology and evolution of N. pompilius, and the results serve as an important resource for future conservation genomics of the nautilus and closely related species. see also the Perspective by Gustavo Sanchez, Oleg Simakov and Daniel S. Rokhsar. [ABSTRACT FROM AUTHOR]

Bacteria affiliated to the Deltaproteobacteria dominate intestinal microbial communities in the abalone, Haliotis diversicolor, and may colonize the host's digestive gland, raising the possibility that they contribute to digestion of macroalgae. However, the phylogenetic, and genomic and metabolic characteristics of these Deltaproteobacteria, and the nature of their relationship to abalone host remain elusive. Here, we examined the intestinal microbial composition of H. diversicolor using high‐throughput sequencing and described the genomic characteristics of the Deltaproteobacteria phylotype using genome‐centric metagenomics. High‐throughput sequencing confirmed that one Deltaproteobacteria phylotype was predominant in intestinal microbiota of H. diversicolor. Phylogeny analysis based on full‐length 16S rRNA gene allocated this bacterium to a distinct and unique cluster within SAR324. It possessed a genome of at least 1.59 Mb with 35.15 mol% GC content, much smaller than other sequenced free‐living SAR324 bacteria. According to genome annotation and metabolic reconstruction, ATP binding cassette transporters for sugars and carbohydrate metabolism pathways indicated heterotrophic potential. Interestingly, it encoded polysaccharide lyases, which, if expressed, could help the host to digest its macroalgae diet. In contrast to the known SAR324, no sulphur oxidation or carbon fixation pathways were predicted. We propose that this is a unique and specific SAR324 bacterium in symbiosis with Haliotis. [ABSTRACT FROM AUTHOR]

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]