Browsing by Author "Dorafshan, Salar"
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- Comparative ontogeny of the digestive tract of Oncorhynchus mykiss female x Salmo trutta caspius male triploid hybrids to their parental speciesPublication . Najafpour, Babak; Dorafshan, Salar; Paykan Heyrati, Fatemeh; Canario, Adelino; Power, Deborahthe ontogeny of the gastrointestinal tract of the hybrid between female rainbow trout, RT (Oncorhynchus mykiss) and male Caspian brown trout, CBT (Salmo trutta caspius) was compared to the parental species. Larvae were collected for histology and enzymatic assays (amylase, lipase and trypsin) at 3, 6, 9, 12, 15, 18, 21, 26, 31, 35, 40 and 45 days post-hatch (dph). the development of the gastrointestinal tract (GI-tract) and the onset of digestive enzyme production was variable between groups. the GI-tract post-hatch was a relatively simple tubular structure, and a rudimentary oesophagus was differentiated from other regions at 3 dph in all studied groups. the pyloric caeca and the U-shaped stomach were clearly visible at 26, 35 and 40 dph in RT, triploid hybrid and CBT, respectively. An abrupt increase in trypsin activity at 31, 35 and 45 dph was identified in CBT, RT and the triploid hybrid, respectively. the increasing activity of trypsin and decreasing activity of lipase during larval development suggests that the CBT, RT and triploid hybrid rely more on dietary proteins than lipids with increasing age. the hybrid grew better and had a faster GI-tract development than CBT, while RT performed best overall.
- Embryonic development of the endangered Caspian brown trout, Salmo trutta caspius (Kessler, 1877)Publication . Najafpour, Babak; Dorafshan, Salar; Heyrati, Fatemeh Paykan; Power, DeborahThe Caspian brown trout, Salmo trutta caspius is an endangered species of economic value and better knowledge of its biology will contribute to conservation measures. In the present study we characterized its early development to identify critical embryonic stages, by observing embryos and larvae from a broodstock maintained in captivity incubated at 9 +/- 1 degrees C. Morphological analysis of landmark stages of embryonic development revealed that first cleavage occurred at 189 degree-h, a many-celled blastoderm formed at 62 degree-days (dd), a germ ring at 72 dd, the neural keel stage at 88 dd, the blastopore closed at 137 dd, the eye became pigmented at 188 dd and the larvae hatched at 373 dd. The detailed timing of these landmark features will help development of strategies aiming at increased aquaculture production of this species.