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The impact of low salinity on morphology and function of hemocytes in ark clam species Anadara kagoshimensis was investigated using light microscopy and flow cytometry. In the control group, the water salinity was adjusted to 19.6‰, and the experimental group was maintained at 14.8 and 8.8‰. Two cell types, amebocytes and erythrocytes, were identified in control group of ark clams. Erythrocytes constituted the main type of the cells; their share was 92.3 ± 3.9%. Hyposalinity changed that proportion: the number of amebocytes decreased by 2.7 times and number of erythrocytes increased by 7.6 times. Morphometric characteristics of hemocytes did not show statistically significant changes. As the salinity decreased, the number of erythrocyte ghosts in hemolymph increased (by 3.5 times at salinity of 8.8‰) and, in hemocytes, the reactive oxygen species (ROS) production grew (by 3.5 times at salinity of 8.8‰). [ABSTRACT FROM AUTHOR]

Endothelial dysfunction is directly involved in consequence of various metabolic syndromes such as diabetes and hypertension. In this study, we investigated the preventive effects of two ark clams [ark shell (AS, Scapharca subcrenata) and granular ark (GA, Tegillarca granosa)] on endothelial dysfunction induced by a high-fat diet. Wistar rats were divided into four groups as follows: control (normal diet), HF (high-fat diet), AS (high-fat diet + 5% AS powder), and GA (high-fat diet + 5% GA powder) for 12 weeks. AS and GA diets enhanced vascular reactivity of the rat thoracic aorta and significantly increased expression levels of vascular relaxation-related proteins (p-Akt-ser473 and p-eNOS-ser1177). Ark clam supplement reduced endothelin-1 expression level, as compared to the HF group. Additionally, AS and GA showed a trend of improving insulin sensitivity compared to HF. Our results suggest that AS and GA enhance vascular reactivity and ameliorated endothelial dysfunction induced by a high-fat diet. [ABSTRACT FROM AUTHOR]

Filter-feeding shellfish are common benthos and significantly affect the biogeochemical cycle in the shallow coastal ecosystems. Ark clam Scapharca subcrenata is one of the widely cultured bivalve species in many coastal areas owing to its tremendous economic value. However, there is little information regarding the effects of the bioturbation of S. subcrenata on the fluxes of nutrient exchange in the sediment-water interface (SWI). In this regard, S subcrenata was sampled during October 2016 to determine the effects of its bioturbation activity on the nutrient exchange flux of the SWI. The results showed that the biological activity of S. subcrenata could increase the diffusion depth and the rate of the nutrients exchange in the sediments. The bioturbation of S. subcrenata could allow the nutrients to permeate into the surface sediments at 6−10 cm and increase the release rate of nutrients at the SWI. The releasing fluxes of DIN and PO43−-P in the culture area were found to be around three times higher than that in the non-cultured region. The culture of S subcrenata has been proved to be an important contributor to nutrient exchange across the SWI in the farming area of Haizhou Bay. Nutrients exchange in the SWI contributes a part of 86% DIN, 71% PO43−-P and 18% SiO32−-Si for the aquaculture farm. [ABSTRACT FROM AUTHOR]

A novel Gram-positive, aerobic, motile, hemolytic, endospore-forming and rod-shaped bacterium TW25 was isolated from a dead ark clam during a mass mortality event on the South coast of Korea. The strain grew optimally at 30°C, at pH 8-9, and with 1% (w/v) NaCl. The 16S rRNA gene sequence analysis indicated that strain TW25 was associated with the genus Ornithinibacillus and that it was most closely related to the type strain of Ornithinibacillus californiensis (98.5% similarity). The dominant cellular fatty acids were iso-C15:0, anteiso-C15:0 and C16:0. The peptidoglycan amino acid type was A4 β, containing l-ornithine and d-aspartic acid. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, four unidentified phospholipids, two unidentified aminolipids and two unidentified lipids. The major respiratory quinone was menaquinone-7 (MK-7). The G + C content of genomic DNA was 36.7 mol%. DNA-DNA hybridization experiments with related strains revealed lower than 11 ± 3% relatedness. Based on this polyphasic taxonomic study, strain TW25 represents a novel species in the genus Ornithinibacillus, for which the name Ornithinibacillus scapharcae sp. nov. is proposed. The type strain is TW25 (=KACC 15116 = JCM 17314). [ABSTRACT FROM AUTHOR]