How Cold Shock Affects Ploidy Level and Early Ontogenetic Development of the Sterlet, A. ruthenus L.

Abstract

The objective of the present research was to study the effect of cold shock (3 °C and 6 °C) on fertilized eggs of the sterlet, Acipenser ruthenus L. Cold shock was applied for various durations (30, 60 and 90 min) and the ploidy levels, survival, and genotypes of the treated embryos/larvae were recorded. Analysis of ploidy levels confirmed the presence of diploid, triploid, and mosaic (1n/2n, 2n/3n, and 1n/2n/3n) genotypes in experimental groups, while it was strictly diploid in control groups. Microsatellite genotyping confirmed both the incidence of polyspermy and retention of the 2nd polar body in experimental groups. However, patterns of inheritance in all diploid offspring in experimental and control groups revealed classical Mendelian disomic inheritance. Interestingly, the observed mosaic sterlets had normal morphology and were alive. However, some larvae had abnormal morphology which may be due to haploid syndrome. In all treatment groups (treatments: 3 °C–30 min; 3 °C–60 min; 3 °C–90 min; 6 °C–60 min), where the percentage of polyploid/mosaic larvae were high, the mortality was also high. Whereas, in the control groups (where there were only diploid (2n) larvae), the mortality was relatively low.

Deformities in fish: A barrier for responsible aquaculture and sustainable fisheries

“…[91][92][93] Furthermore, temperature also alters ploidy level, body deformities, ontogenetic development and disturbance in the growth and survival of fish, especially at the early stage of embryonic development. 1,5,94 Increasing water temperature is an efficient way of increasing the growth rate and production in cold water aquaculture, but elevated temperature increases the frequency of skeletal deformities. 44 The findings suggest that 10 C is the most suitable temperature, while 14 C is too high and 6 C is too low for rainbow trout, O. mykiss; fused or compressed vertebrae are the most common skeletal malformations in rainbow trout, O. mykiss.…”

“…Fish live in aquatic environments that are very dynamic; the early embryonic and larval stages of fish may encounter hazardous substances, including the factors that cause deformities in fish. Several abiotic factors, such as temperature, pH, salinity, water current velocity and water pollution, affect embryonic and larval development and cause deformities in fish 5–7 . Thus, information about the optimal range of abiotic factors is essential in preventing deformities in fish.…”

“…Thus, it is known as an ‘abiotic master factor’ for fishes 91–93 . Furthermore, temperature also alters ploidy level, body deformities, ontogenetic development and disturbance in the growth and survival of fish, especially at the early stage of embryonic development 1,5,94 . Increasing water temperature is an efficient way of increasing the growth rate and production in cold water aquaculture, but elevated temperature increases the frequency of skeletal deformities 44 .…”

“…1,2 Deformities affect not only aquaculture activities but also the conservation of vulnerable fisheries resources around the globe. [3][4][5] (Figure 1). Several factors, such as physicochemical characteristics of water (temperature, water current velocity, salinity and pH), pollution, nutrition, genetic factors and farming infrastructure, have been identified for inducing deformities in fish.…”

“…[5][6][7] Furthermore, induced breeding in the hatchery, temperature shock during embryonic and larval development and genome manipulations during polyploidy induction escalate the incidence of deformities. 5,8 Deformities occasionally occur in the natural world but are more common in polluted and stressed environments. 9 Despite significant progress in identifying various causative factors that cause deformities in fish, our current knowledge about this complex issue is still limited.…”