Biochemical, histological, and gene expression analysis in brain and heart in Phoxinus lagowskii under sustained and diel‐cycling hypoxia

Abstract

Sustained and diel-cycling hypoxia frequently occurs in high-latitude environments; however, fish's biochemical, physiological, and histological responses to these two conditions remain unknown. Current hypotheses posit that the heart and the brain of fish from high latitudes are integral to their hypoxia tolerance and that fish exhibit different response mechanisms to cope with sustained and dielcycling hypoxic conditions. To test this, we acclimated Phoxinus lagowskii, a high-latitude fish, to ecologically relevant sustained and diel-cycling hypoxia conditions over 28 days. Histological analysis revealed changes in the relative thickness of the layers in the midbrain. There was a prominent upsurge of oxidative stress biomarkers in dielcycling hypoxia (DCH) treatments, with superoxide dismutase and catalase activity. Our data suggested that triglycerides in the heart were elevated in DCH groups but remained unchanged regardless of sustained hypoxia (SH) treatments. The majority of enzyme activities (LDH, PK, PFK, and HK) increased in DCH groups, especially at day 28. The gene expression results indicated that HIF mainly regulated long-term DCH in the heart and regulated SH in the brain. Collectively, these findings reveal that

A chromosome-level, haplotype-resolved genome assembly and annotation for the Eurasian minnow (Leuciscidae: Phoxinus phoxinus) provide evidence of haplotype diversity

“…Cyprinoidea in general have been thought to be sensitive to oxidative stress, demonstrated in Amur minnow ( Phoxinus lagowskii ) (Q. Wang et al, 2019; Yao et al, 2022) and Chinese rare minnow ( Gobiocypris rarus ) (Z.-H. Li et al, 2014), while the fathead minnow ( Pimephales promelas ) has been used as a bioindicator of water quality (Elizalde-Velázquez et al, 2020).…”

Presentations by young Chinese aquaculture scientists: From the 2021 China Society of Fisheries—Annual Conference of Youth Scholars

“…Fish in high‐latitude regions suffer from sustained hypoxia in winter and diel‐cycling hypoxia in summer. Phoxinus lagowskii , a high‐latitude fish distributed and mainly cultured in northeast China, was chosen to determine the biochemical, physiological, and histological responses to these two conditions (Yao et al, 2022). Histological analysis revealed changes in the relative thickness of the layers in the midbrain under hypoxia.…”