Transgenerational effects of ß-glucan on thermal tolerance, growth performance, and immune gene expression of endangered cyprinid Tor putitora progeny.

Nutritional programming signifies a process in which broodstock feeding approaches have long-term effects on the subsequent progeny. The present study aimed to elucidate whether supplementing golden mahseer, Tor putitora broodstock diets with ß-glucan affects progeny growth performance, survival, thermal tolerance, and non-specific immunity. Initially, the growth performance of progeny produced from brooders fed with different levels of ß-glucan was non-significant. However, on the 15th and 35th DPH, the maximum weight was observed in fry obtained from the brooders fed with 0.5% followed by 1.0% ß-glucan. Furthermore, on 50th DPH, significantly higher weight was registered in the fry from the 0.5% ß-glucan fed group while 1.0% ß-glucan group had no transgenerational effect on growth. The condition factor of fry obtained from golden mahseer brooders fed with a 0.5% ß-glucan diet was greater than the control and 1.0% ß-glucan fed group. On the other hand, we did not find any significant transgenerational influence of ß-glucan on the survival of the progeny. The thermal tolerance of fry produced from brooders fed with ß-glucan was significantly modulated at both end-points (CTmax and CTmin). Expression of interleukin-1ß was significantly up-regulated in fry obtained from ß-glucan fed brooders. In contrast, the expression level of tumor necrosis factor-α was significantly higher only in fry produced from 1.0% ß-glucan fed brooders. The expression of immunoglobulin light chain and serum amyloid A gene was significantly higher in fry produced from 0.5% ß-glucan fed brooders. Overall results suggest that the dietary provisioning of ß-glucan in golden mahseer brooders can be a strategy to produce healthy and robust fry in captivity for stock enhancement and conservation programs.

Dietary ß-glucan influences the expression of testicular aquaporins, antioxidative defence genes and sperm quality traits in endangered golden mahseer, Tor putitora (Hamilton, 1822).

The effect of dietary ß-glucan on seminal plasma composition, sperm characteristics, expression of aquaporins, and antioxidative defence genes of golden mahseer was evaluated. For that, four experimental diets containing 0 (control), 0.5, 1, and 1.5% ß-glucan were fed to male golden mahseer brooders for 130 days. Feeding of 0.5% ß-glucan was found to improve sperm characteristics, viz. sperm count, motility, viability, and morphology with no effect on gonadosomatic index and seminal plasma energy resources. The marked down-regulation in the transcript abundance of testicular aqp3a noticed in 1.5% ß-glucan fed brooders corresponds to their poor sperm quality. Further, the mRNA expression of genes encoding antioxidant enzymes, namely gst and sod1, was lowest in 0.5% ß-glucan fed brooders. In contrast, control and higher ß-glucan (1 and 1.5%) groups displayed relatively higher expression levels of testicular gst and sod1. On the other hand, the higher seminal plasma total antioxidant capacity observed in 0.5 and 1% ß-glucan fed brooders indicated increased scavenging ability of reactive oxygen species. Overall, supplementation of 0.5% ß-glucan improved sperm quality and antioxidative potential, but the higher inclusion (1.5%) negatively affected sperm characteristics. Collectively, dietary ß-glucan (0.5%) can be a practical approach to developing quality broodstock of golden mahseer.

Dietary soy lecithin augments antioxidative defense and thermal tolerance but fails to modulate non-specific immune genes in endangered golden mahseer (Tor putitora) fry.

A 70-day experiment was carried out to assess the effect of different levels (0, 1 and 2%) of soy lecithin in the diet on growth, survival, antioxidant defense markers, immune gene expression and thermal tolerance limits of golden mahseer, Tor putitora fry. Percentage weight gain, specific growth rate (SGR %) and survival of mahseer fed lecithin supplemented diets were not significantly different from those of the control group. Also, the mRNA expression levels of different immune related genes such as tnfα, il-1ß, il-10, complement-3, interferon-gamma (ifnγ) and tlr4 were unaffected by dietary lecithin supplementation. Nevertheless, superoxide dismutase (SOD) activity was significantly greater in the lecithin-fed groups than the control fish. The glutathione-S-transferase (GST) activity was exceptionally high in the 2% lecithin supplemented group compared to the rest two groups. This increase in antioxidant status with dietary lecithin supplementation, however, was not reflected in the whole body malonaldehyde (MDA) levels, as it did not vary significantly among the dietary groups. Importantly, dietary inclusion of soy lecithin significantly increased upper thermal tolerance limits as evidenced by higher CTmax and LTmax values. Likewise, golden mahseer fry fed with lecithin supplemented diets (both 1 and 2%) registered significantly lower critical and lethal thermal minimum (CTmin and LTmin) values than the control group, indicating higher cold tolerance capacity. Our results thus demonstrate that the dietary inclusion of soy lecithin could enhance the upper and lower thermal tolerance limits and antioxidant status of golden mahseer fry and failed to enhance immune related gene expression.