Evolution of the nucleoli has been followed during oogenesis in the Acipenserid fishes, Acipenser ruthenus (the sterlet) and A. guidenstadti (the sturgeon) using light and electron microscopes. In the ovaries of adults, the oogonial nuclei usually have a single nucleolus with an adjacent mass of paranucleolar fibrillar material. The cytoplasm of the oogonia contains two dense bodies peculiar on...

   Stability of bacterial flora in fish intestine is very important, because the intestine is an important organ for outbreak of microbial infections and other fish diseases especially when the fish have not been vaccinated. The aim of this study was to determine the bacterial flora of intestine in sturgeon juvenile in earthen ponds. The results can be applied to prevent the diseases occurren...

cadmium is considered as a common residue in water and sediments which could readily enter aquatic organisms. the aim of this study was to evaluate the time- and concentration-dependent changes in antioxidant enzymes (sod and cat) activities as well as concentration of mda as a bi- product of lipid peroxidation in the liver of persian sturgeon, acipenser persicus , following cdcl 2 exposure at ...

Induction of heat shock proteins (hsps) is considered as an important protective, ecophysiologically adaptive, and genetically conserved response to environmental stress in all organisms. The effects of exposure to sublethal doses of CdCl2 (0.05, 0.1 and 0.2 LC50) during 14 days on mRNA-hsp70 expression in liver and gillwere investigated in juveniles of Persian sturgeon (Acipenser persicus). Fi...

This study was carried out in a completely randomized design 3×3×4 factorial arrangement in three periods of rearing in spring 1997. Density of 300 larvae was assigned for each oval tank with 0.1m2 surface area, 30cm deep, a volume of 20lit and 0.25 lit/min of water flow per minute at Shahid Rajaie fish breeding and culture center in Sari, north of Iran. The fries were divided into ...

The present study was conducted to determine the best feeding rates expressed as percent of body weight in Persian sturgeon fingerlings at different body weights. Eighteen fiberglass tanks each holding 30 fingerlings with an average initial body weight of 19.45 ± 0.5 g were used in this experiment. Six different feeding trials (1, 2, 3, 4, 5 and 6 percent of body weight) were employed an...

Water diversions that extract fresh water for urban, industrial, and agricultural uses, as well as export to southern California, are prevalent throughout the Sacramento–San Joaquin watershed. Many water diversions are fitted with fishexclusion screens designed to prevent fish from entrainment (i.e., being drawn in). The impact of fish screens on the behavior of migrating juvenile fishes remain...

Newly hatched white sturgeon (Acipenser transmontanus) yolk-sac larvae are negatively phototactic, photokinetic and geotactic--seeking cover in the substrate during daylight hours. If cover is unavailable and the light intensity is low, they move into the water column and alternate periods of rapid, upward swimming with periods of quiescence during which they sink. In the dark they swim almost ...

This study quantified the effects of temperature and fish mass on routine metabolism of the American paddlefish Polyodon spathula. Thermal sensitivity, as measured by Q(10) value, was low in P. spathula. Mean Q(10) was 1·78 while poikilotherms are generally expected to have Q(10) values in the 2·00-2·50 range. Mass-specific metabolism did not decrease with increased fish size to the extent that...