Scott Sturgeon has recently challenged Pollock’s account of undercutting defeaters. The challenge involves three primary contentions: (1) the account is both too strong and too weak, (2) undercutting defeaters exercise their power to defeat only in conjunction with higher-order beliefs about the basis of the lower-order beliefs whose justification they target, and (3) since rebutting defeaters ...

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 ...

lactic acid bacteria are characterized as gram-positive, usually non-motile, non-sporulating bacteria that produce lactic acid as a major or sole product of their fermentative metabolism. in this study, the presence of lactobacilli were investigated in the intestines of beluga ( huso huso) and persian sturgeon ( acipenser persicus ), inhabiting caspian sea. the obtained data showed that various...

In the present study, we examined the insulin-like growth factor receptor 1(IGF-1R) transcription using real-time PCR at different stages of oocytes of Russian sturgeon (Acipenser gueldenstaedtii) at age 8-9 years and weight 25 kg that were grown under aquaculture conditions. Compare to the pre-vitellogenesis stage, the transcription of IGF-1R increased at the vitellogenesis stages (yellow, gra...

world production of caviar from the farmed sturgeon has recently so increased that in addition to compensate reduction of natural resources of sturgeon, it has also increased its share in the world market for caviar and its substitutes. although belarus, china and norway are currently considered as the main exporting countries of caviar and its substitutes but, iran solely exports caviar from s...

 In order to have a sustainable management on Persian sturgeon as a highly commercial species in the South Caspian Sea, we need to identify its population structure and the level as well as its conservation status in their natural habitat. To develop a conservation program for this all Caspian Sea' sturgeon species it requires knowledge of its genetic diversity using reliable molecular marker t...

Historically, the ship sturgeon (Acipenser nudiventris) occurred in Aral, Caspian, Azov, and Black Sea basins. However, its numbers decreased dramatically during 20th century. It is now considered extirpated from Seas, has almost disappeared Caspian Sea. A. nudiventris listed as Critically Endangered on IUCN Red List and, Georgia, species been undetected for last three decades. We collected 22 ...

The objective of this study was to compare the biological parameters such as length, weight, age, caviar production indices, caviar/weight, condition factor and sex ratio of Persian sturgeon (Acipenser persicus Borodin, 1897) and Russian sturgeon (A. gueldenstaedtii Brandt & Ratzeburg, 1833) in the Caspian Sea during 1990-2014. All these characteristics (except condition factor) of Persian stur...