Genome assembly of the Korean intertidal mud-creeper Batillaria attramentaria.

Batillaridae is a common gastropod family that occurs abundantly in the shallow coastal zone of the intertidal mudflats of the northwest Pacific Ocean, Australasia, and North America. In this family, Batillaria attramentaria is known for its biological invasion and colonization in estuarine and intertidal zones. It can endure and adapt the harsh intertidal conditions such as frequent temperature alteration, salinity, and air exposure. Therefore, we sequenced and assembled this Korean batillariid genome to get insight into its intertidal adaptive features. Approximately 53 Gb of DNA sequences were generated, and 863 scaffolds were assembled into a draft genome of 0.715 Gb with 97.1% BUSCO completeness value. A total of 40,596 genes were predicted. We estimated that B. attramentaria and Conus consors diverged about 230 million years ago (MYA) based on the phylogenetic analysis of closely related gastropod species. This genome study sets the footstep for genomics studies among native and introduced Batillaria populations and the Batillaridae family members.

A time-calibrated mitogenomic phylogeny suggests that Korean Hyalessa fuscata is a bridge between Chinese and Japanese H.maculaticollis.

The cicada species, Hyalessa fuscata and H. maculaticollis(Hemiptera: Cicadidae), share numerous morphological characters, and their status as distinct species remains controversial. We reconstructed a phylogeny based on two new mitogenomes of H. fuscata from Korea and H. maculaticollis from Japan, in combination with GenBank sequences of H. maculaticollis from China and Japan, and other closely related cicada species. Maximum likelihood and Bayesian inference phylogenies showed that H. fuscata from Korea is more closely related to H. maculaticollis from China than either is to H. maculaticollis from Japan. The time-calibrated Bayesian evolutionary analysis by sampling trees (BEAST) phylogeny indicated that the mainland and insular forms diverged approximately 1.7-2.6 million years ago. This coincides with the formation of the East China Sea land bridge between East Asia and the Japanese archipelago, which would provide a dispersal corridor for Hyalessa from the mainland via the Korean peninsula southeastward to Japan. East Asian H. fuscata is a geographic variant that may be considered synonymous with H. maculaticollis.

Experimental data supporting adaptive locomotor responses to salt stress in the mud-tidal gastropod populations (Batillaria).

This article describes the experimental locomotor data used to study the general and adaptive responses to salt stress of the northern Pacific intertidal gastropod Batillaria attramentaria. The data were obtained from a series of 30-day experiments on snails acclimated to different salinity regimes. Snails were collected from coastal areas on the eastern and western sides of the North Pacific Ocean. The data consist of three parts: 1) raw videos recording the locomotion of the snails when exposed to novel artificial salinity regimes in laboratory settings, 2) Spectral Time-Lapse results of movement distance of the snails extracted from the recorded videos, and 3) CO1-gene sequences isolated from individuals collected from four sampling sites. A Linear Mixed-effect Model inference procedure was applied in an attempt to assess the impacts of geographic distribution and genetic composition on the locomotor response to salt stress in the snail B. attramentaria. The locomotor dataset we present are the first reports of locomotor response to salt stress of the snail B. attramentaria, that is valuable for further exploration and understanding of the impacts of environmental changes on the physiology and adaptive capacity of living marine molluscs.

Locomotor responses to salt stress in native and invasive mud-tidal gastropod populations (Batillaria).

Plasticity in salt tolerance can be crucial for successful biological invasions of novel habitats by marine gastropods. The intertidal snail Batillaria attramentaria, which is native to East Asia but invaded the western shores of North America from Japan 80 years ago, provides an opportunity to examine how environmental salinity may shape behavioral and morphological traits. In this study, we compared the movement distance of four B. attramentaria populations from native (Korea and Japan) and introduced (United States) habitats under various salinity levels (13, 23, 33, and 43 PSU) during 30 days of exposure in the lab. We sequenced a partial mitochondrial CO1 gene to infer phylogenetic relationships among populations and confirmed two divergent mitochondrial lineages constituting our sample sets. Using a statistical model-selection approach, we investigated the effects of geographic distribution and genetic composition on locomotor performance in response to salt stress. Snails exposed to acute low salinity (13 PSU) reduced their locomotion and were unable to perform at their normal level (the moving pace of snails exposed to 33 PSU). We did not detect any meaningful differences in locomotor response to salt stress between the two genetic lineages or between the native snails (Japan vs. Korea populations), but we found significant locomotor differences between the native and introduced groups (Japan or Korea vs. the United States). We suggest that the greater magnitude of tidal salinity fluctuation at the US location may have influenced locomotor responses to salt stress in introduced snails.

Dataset supporting description of the new mussel species of genus Gigantidas (Bivalvia: Mytilidae) and metagenomic data of bacterial community in the host mussel gill tissue.

This article contains supplementary data from the research paper entitled "A newly discovered Gigantidas bivalve mussel from the Onnuri Vent Field on the northern Central Indian Ridge" [1], describes a new mussel species within the subfamily Bathymodiolinae named Gigantidas vrijenhoeki. Data are comprised of two parts: 1) shell image and molecular analyses of G. vrijenhoeki and 2) metagenomic community analyses of gill-associated symbiotic bacteria on G. vrijenhoeki. G. vrijenhoeki data were obtained from type specimens described in Jang et al. 2020 [1]. The molecular analysis was conducted by calculating genetic distance at intra- and inter-specific level within genus Gigantidas based on the sequence data of two mitochondrial genes (COI and ND4). The metagenomic dataset of gill-associated symbionts were generated by Illumina Miseq sequencing of the V3-V4 region of 16S rRNA from 12 specimens of G. vrijenhoeki collected from the same vent site, Onnuri Vent Field.

Impacts of Salt Stress on Locomotor and Transcriptomic Responses in the Intertidal Gastropod Batillaria attramentaria.

Salinity is one of the most crucial environmental factors that structures biogeographic boundaries of aquatic organisms, affecting distribution, abundance, and behavior. However, the association between behavior and gene regulation underlying acclimation to changes in salinity remains poorly understood. In this study, we investigated the effects of salinity stress on behavior (movement distance) and patterns of gene expression (using RNA sequencing) of the intertidal gastropod Batillaria attramentaria. We examined responses to short-term (1-hour) and long-term (30-day) acclimation to a range of salinities (43, 33 [control], 23, 13, and 3 psu). We found that the intertidal B. attramentaria is able to tolerate a broad range of salinity from 13 to 43 psu but not the acute low salinity of 3 psu. Behavioral experiments showed that salt stress significantly influenced snails' movement, with lower salinity resulting in shorter movement distance. Transcriptomic analyses revealed critical metabolic pathways and genes potentially involved in acclimation to salinity stress, including ionic and osmotic regulation, signal and hormonal transduction pathways, water exchange, cell protection, and gene regulation or epigenetic modification. In general, our study presents a robust, integrative laboratory-based approach to investigate the effects of salt stress on a nonmodel gastropod facing detrimental consequences of environmental change. The current genetic results provide a wealth of reference data for further research on mechanisms of ionic and osmotic regulation and adaptive evolution of this coastal gastropod.

Encapsulation of Hibiscus sabdariffa L. anthocyanins as natural colours in yeast.

Hibiscus sabdariffa extracts, a rich source of anthocyanin, were subjected to encapsulation in yeast cells. An encapsulation yield (EY) of 208 µg/100 mg of cells and an encapsulation efficiency (EE) of 27%, were reached after optimisation of the ratios (0.5 g wet yeast cells for 5 ml of anthocyanin extracts at 1 g·L-1) and with 10% of ethanol. The storage stability of encapsulated pigments was investigated in water and buffer pH 1.5 at 5 & 37 °C for 10 days and 90 °C for 30 min. The percentage of loss of colour was determined by colourimetry assays. The microparticles made of yeast with or without heat treatment exhibited different protecting effects (P < 0.01). At 37 °C, the percentage of loss of colour in water was of 2.5% for heat-treated and 36.5% for non-treated yeast microparticles, suggesting that yeast enzymes would be responsible for the loss of anthocyanin during storage. These results are confirmed by the percentage of loss of colour which was far lower in conditions of low enzymatic activity: 3.1% at 5 °C for non-heat-treated cells in water. The pH of solvent had also an important effect on the degradation of encapsulated anthocyanin; in buffer at pH 1.5 and 37 °C with the non-heat-treated cells, the degradation decreased strongly to 9.4% compared with 36.5% in water. These results show that yeast cells are a good mean of encapsulation of pigments for a colouring purpose and that they provide anthocyanins a good protection as long as their enzymes are inactivated.

Geographical structure of endosymbiotic bacteria hosted by Bathymodiolus mussels at eastern Pacific hydrothermal vents.

BACKGROUND: Chemolithoautotrophic primary production sustains dense invertebrate communities at deep-sea hydrothermal vents and hydrocarbon seeps. Symbiotic bacteria that oxidize dissolved sulfur, methane, and hydrogen gases nourish bathymodiolin mussels that thrive in these environments worldwide. The mussel symbionts are newly acquired in each generation via infection by free-living forms. This study examined geographical subdivision of the thiotrophic endosymbionts hosted by Bathymodiolus mussels living along the eastern Pacific hydrothermal vents. High-throughput sequencing data of 16S ribosomal RNA encoding gene and fragments of six protein-coding genes of symbionts were examined in the samples collected from nine vent localities at the East Pacific Rise, Galápagos Rift, and Pacific-Antarctic Ridge. RESULTS: Both of the parapatric sister-species, B. thermophilus and B. antarcticus, hosted the same numerically dominant phylotype of thiotrophic Gammaproteobacteria. However, sequences from six protein-coding genes revealed highly divergent symbiont lineages living north and south of the Easter Microplate and hosted by these two Bathymodiolus mussel species. High heterogeneity of symbiont haplotypes among host individuals sampled from the same location suggested that stochasticity associated with initial infections was amplified as symbionts proliferated within the host individuals. The mussel species presently contact one another and hybridize along the Easter Microplate, but the northern and southern symbionts appear to be completely isolated. Vicariance associated with orogeny of the Easter Microplate region, 2.5-5.3 million years ago, may have initiated isolation of the symbiont and host populations. Estimates of synonymous substitution rates for the protein-coding bacterial genes examined in this study were 0.77-1.62%/nucleotide/million years. CONCLUSIONS: Our present study reports the most comprehensive population genetic analyses of the chemosynthetic endosymbiotic bacteria based on high-throughput genetic data and extensive geographical sampling to date, and demonstrates the role of the geographical features, the Easter Microplate and geographical distance, in the intraspecific divergence of this bacterial species along the mid-ocean ridge axes in the eastern Pacific. Altogether, our results provide insights into extrinsic and intrinsic factors affecting the dispersal and evolution of chemosynthetic symbiotic partners in the hydrothermal vents along the eastern Pacific Ocean.

Postglacial range shift and demographic expansion of the marine intertidal snail Batillaria attramentaria.

To address the impacts of past climate changes, particularly since the last glacial period, on the history of the distribution and demography of marine species, we investigated the evolutionary and demographic responses of the intertidal batillariid gastropod, Batillaria attramentaria, to these changes, using the snail as a model species in the northwest Pacific. We applied phylogeographic and divergence population genetic approaches to mitochondrial COI sequences from B. attramentaria. To cover much of its distributional range, 197 individuals collected throughout Korea and 507 publically available sequences (mostly from Japan) were used. Finally, a Bayesian skyline plot (BSP) method was applied to reconstruct the demographic history of this species. We found four differentiated geographic groups around Korea, confirming the presence of two distinct, geographically subdivided haplogroups on the Japanese coastlines along the bifurcated routes of the warm Tsushima and Kuroshio Currents. These two haplogroups were estimated to have begun to split approximately 400,000 years ago. Population divergence analysis supported the hypothesis that the Yellow Sea was populated by a northward range expansion of a small fraction of founders that split from a southern ancestral population since the last glacial maximum (LGM: 26,000-19,000 years ago), when the southern area became re-submerged. BSP analyses on six geographically and genetically defined groups in Korea and Japan consistently demonstrated that each group has exponentially increased approximately since the LGM. This study resolved the phylogeography of B. attramentaria as a series of events connected over space and time; while paleoceanographic conditions determining the connectivity of neighboring seas in East Asia are responsible for the vicariance of this species, the postglacial sea-level rise and warming temperatures have played a crucial role in rapid range shifts and broad demographic expansions of its populations.