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Hydrological conditions are responsible for the changes in lateral connectivity between the main river channel and the floodplain lakes, a factor controlling zooplankton abundance and diversity. We tested the hypothesis that the degree of connectivity between the aquatic habitats and the river channel governs the zooplankton densities and community(More)
This study analyzed the influence of temperature on the rearing of sichel Pelecus cultratus larvae under controlled conditions. Five constant temperature regimes were tested: 14 °C, 18 °C, 22 °C, 26 °C and 30 °C. The larvae were reared for 30 days in aquaria with 50 dm3 working capacities. The larvae density was 40 individuals/dm3 and the fish larvae were(More)
β-N-Acetylglucosaminidase (β-NAGase) is an enzyme found in the sperm acrosome of numerous animal species including fish. Fish spermatozoa differ in their morphology including acrosome or acrosomeless aquasperm in chondrostean (e.g., sturgeon) and teleostean (e.g., rainbow trout). It has been shown that β-NAGase exists with high activity in both eggs and(More)
Crosses between 21 triploid hybrid Cobitis females and 19 C. taenia (2n = 48) males led to viable progeny; whereas no embryonic development was observed in crosses with tetraploid males (4n = 98). The ploidy status of 491 progenies randomly selected with flow cytometry (316) or chromosome analysis (175) revealed an average of 55.2 % triploids and 44.8 %(More)
The aim of the study was to determine the optimum temperature shock timing to induce androgenetic and gynogenetic growth in common tench (Tinca tinca L.). UV radiation at the dose of 3,456 J m−2 was used to inactivate the genome of oocytes (androgenesis) and sperm (gynogenesis). In each case, the optimum timing was sought (between 20 and 60 min) before the(More)
The ontogeny of the digestive tract was studied histologically in burbot, Lota lota L., from hatching to 42 days post-hatch (dph). At hatching, the digestive tract consisted of a straight tube with discernible digestive accessory glands (the liver and the pancreas) dorsally attached to the yolk sac. Most of the yolk sac reserves were consumed during the(More)
Diploid and triploid hybrid females of Cobitis as a rule produce unreduced eggs which mainly develop gynogenetically, but some of the eggs incorporate sperm genome and develop into triploids and tetraploids, respectively. Here, we observed for the first time the meiotic chromosomes in the germinal vesicles (GVs) of mature oocytes of three diploid C. taenia(More)