Kurata, O. | bioRxiv Science

bioRxiv2022

A case of mycobacteriosis associated with Mycobacterium pseudoshottsii in aquarium-reared fish in Japan

In 2019, several aquarium-reared fish died at a sea life park in Japan. Necropsy revealed micronodules on the spleen in the dotted gizzard shad (Konosirus punctatus). Seven of 16 fish exhibited microscopic multifocal granulomas associated with acid-fast bacilli in the spleen, kidney, liver, alimentary tract, mesentery, gills, and/or heart. Bacterial cultures yielded isolates from the dotted gizzard shad and a Japanese sardine (Sardinops melanostictus). Microbiological examination, multilocus sequence typing analysis, and variable number of tandem repeats analysis with a newly proposed 6-loci set revealed the isolates as Mycobacterium pseudoshottsii. To our knowledge, this is the first isolation of M. pseudoshottsii from aquarium-reared fish.

microbiology↗

bioRxiv2022

Estimation of the reference lead (Pb) concentration levels affecting immune cells in the blood of Black-headed Gulls (Chroicocephalus ridibundus, Laridae)

The biological effects of lead (Pb) contamination have been reported in various species. There are no restrictions on the use of Pb products, including bullets, in the areas south of Hokkaido, Japan. Local governments have announced the presence of some Pb in the soil sediments of water bodies. Previous studies have confirmed the relationship between blood Pb level (BLL) and immune cells. This study was performed with the aim of clarifying the effect of Pb contamination on immune cells. In total, 170 Black-headed Gulls (Chroicocephalus ridibundus) were captured, including a population in Tokyo Bay between November 2018 and April 2021 and a population in Mikawa Bay between January 2019 and April 2021. Linear regression analysis was performed with the white blood cell count (WBC), proportion of heterophils (Het), proportion of lymphocytes (Lym), ratio of heterophils and lymphocytes (H/L ratio), copy number of CD4 messenger RNA, and copy number of CD8 messenger RNA as the objective variables, and the BLL as the explanatory variable. The group with BLL < 1.0 g/dL had a significantly lower Het and higher Lym than that with BLL > 3.5 g/dL (P < 0.05). In addition, the group with BLL < 1.0 g/dL had a significantly lower H/L ratio than that with BLL > 3.5 g/dL. CD8 and WBC were higher in the group with the group with BLL range, from 1.0 to 3.5 g/dL than those in the group with BLL < 1.0 g/dL. This study suggests that the effect of Pb pollution on the immune cells of Black-headed Gulls is lower than some previous criteria values.

ecology↗