Ploidy levels in the kaluga, Huso dauricus and Sakhalin sturgeon Acipenser mikadoi (Acipenseridae, Pisces)

Application of interspecific Somatic Cell Nuclear Transfer (iSCNT) in sturgeons and an unexpectedly produced gynogenetic sterlet with homozygous quadruple haploid

Somatic cell nuclear transfer (SCNT) is a very promising cloning technique for reconstruction of endangered animals. The aim of the present research is to implement the interspecific SCNT (iSCNT) technique to sturgeon; one fish family bearing some of the most critically endangered species. We transplanted single cells enzymatically isolated from a dissociated fin-fragment of the Russian sturgeon (Acipenser gueldenstaedtii) into non-enucleated eggs of the sterlet (Acipenser ruthenus), two species bearing different ploidy (4n and 2n, respectively). Up to 6.7% of the transplanted eggs underwent early development, and one feeding larva (0.5%) was successfully produced. Interestingly, although this transplant displayed tetraploidism (4n) as the donor species, the microsatellite and species-specific analysis showed recipient-exclusive homozygosis without any donor markers. Namely, with regards to this viable larva, host genome duplication occurred twice to form tetraploidism during its early development, probably due to iSCNT manipulation. The importance of this first attempt is to apply iSCNT in sturgeon species, establishing the crucial first steps by adjusting the cloning-methodology in sturgeon's biology. Future improvements in sturgeon's cloning are necessary for providing with great hope in sturgeon's reproduction.

Cloning HSP70 and HSP90 genes of kaluga (Huso dauricus) and the effects of temperature and salinity stress on their gene expression

The genes encoding HSP70 and HSP90 proteins were isolated from kaluga by homologous cloning and rapid amplification of complementary DNA (cDNA) ends (RACE). HSP70 (GenBank accession no. KP050541) and HSP90 (GenBank accession no. KP050542) cDNAs were composed of 2275 and 2718 bp and encoded polypeptides of 650 and 725 amino acids, respectively. Basic Local Alignment Search Tool (BLAST) analysis showed that HSP70 and HSP90 of kaluga shared high identities with those of Acipenser ruthenus, Acipenser schrenckii, and Acipenser baerii (98-99 %). Fluorescent real-time RT-PCR under unstressed conditions revealed that HSP70 and HSP90 were expressed in 11 different tissues of kaluga. Messenger RNA (mRNA) expressions of both HSP70 and HSP90 were highest in the intestine and lowest in the muscle. In addition, the patterns of mRNA expression of HSP70 and HSP90 were similar, although the level of expression was more in HSP90 than in HSP70 (P < 0.05).We also analyzed patterns of HSP70 and HSP90 expression in the muscle, gill, and liver of kaluga under different combinations of temperature and salinity stress, including temperatures of 4,10, 25, and 28 °C at 0 ppt salinity, and salinities of 10, 20, 30, and 40 ppt at 16 °C, where 16 °C at 0 ppt (parts per thousand) served as the control. We found that levels of mRNA expression of both HSP70 and HSP90 were highest at 4 °C in the muscle, gill, and liver and changed little with salinity stress. These results increase understanding of the mechanisms of stress response of cold freshwater fish.