To identify quantitative trait loci (QTL) that affect body shape in common carp Cyprinus carpio, a linkage map, 2159·23 cM long, was constructed with a total of 307 markers covering 51 linkage groups (LG). The map included 167 new single nucleotide polymorphism (SNP) markers derived from expressed sequence tags (EST) together with 140 microsatellite markers reported earlier. A primary genome scan was conducted for QTL for standard length (L(S)), head length (L(H)), body height (H(B)), body width (W(B)) and tail length (L(TAIL)) in an F1 line containing 92 offspring. A total of 15 suggestive QTL on six LGs were found to associate with L(S), L(H), H(B), W(B) and L(TAIL) which explained 10·7-17·4% of the variance. Five significant QTL were detected for body-shape related traits and located for LGs (lg1, 12 and 20). These QTL included: one associated with L(S) (21·1% variance explained), three for H(B) (almost 20% variance explained) and one for W(B) (20·7% variance explained).

The objective of the study was to assess the changes of vitellogenin (Vg) during the course of the reproductive cycle in Amur sturgeon (Acipenser schrenckii). Vg was purified from the serum of vitellogenic female Amur sturgeon by distilled water and gel filtration. Vg had an apparent molecular mass of 410 kDa and appeared as one band corresponding to 205 kDa after SDS-PAGE under reducing conditions. These bands were immunoreacted in Western blotting using antiserum against amur sturgeon lipovitellin (anti-Lv) which is an egg yolk protein derived from Vg. Lv was purified from egg extracts by ammonium sulfate solution and gel filtration. Vg was confirmed to be a lipoglycophosphoprotein by staining with Red oil, Molecular ProesÕ Pro-Q Ò Emerald 300 Glycoprotein Gel stain and Pro-Q Ò Diamond Phosphoprotein Gel Stain. Vg induction was detected after injection of E 2 at a concentration of at least 0.5 mg kg )1 , and the plasma Vg concentration was increased by injection of the animals to 0.5 mg kg )1 for 5 day late. Immature sturgeons at 1015 g weight do not naturally synthesize Vg, but strongly responded to exogenously added E 2 . In addition, if they were not stimulated with exogenous E 2 , the youngest sturgeons did not show any detectable amount of Vg in their plasma, suggesting that Amur sturgeons with a body mass range of 903-1015 g could be used for the induction test, irrespective of their sex. The Enzyme-linked immunosorbant assay for sturgeon vg was developed to quantify serum Vg, using purified sturgeon Vg and anti-Vg. The measurable range was from 16.25 to 1000 ng ml )1 . The dilution curve in ELISA of vitellogenic female serum was parallel to the standard curve of purified Vg. The coefficient variations of intra-and inter-assay were less than 5%, respectively. Vg levels varied throughout natural vitellogenesis from 0 lg ml )1 (1-3 years old) to approximately 200 lg ml )1 (7-8 years old). We observed an early transitory peak of serum Vg levels 200 lg ml )1 (for 10 months) at the time of early vitellogenesis and high Vg levels 218 lg ml )1 (for 3 months) in spring period before ovulation. It appears that the duration of vitellogenesis in Amur sturgeon is lasting more than 2 years.

Two populations of Przewalski's naked carp Gymnocypris przewalskii, 30 individuals per population, were screened for 10 microsatellite loci. Moderate allele variation was found in these loci with two to eight alleles per locus. The expected and observed heterozygosity ranged from 0.019 to 0.805 and from 0.160 to 0.575, respectively.

In this study, we investigated the bacterial communities in the shrimp and sea cucumber culture environment, including shrimp ponds (SP), sea cucumber ponds (SCP), mixed-culture ponds (MCP) and the effluent channel (EC) in Qingdao, China. Bacteria cultivation showed that the counts of heterotrophic, nitrate-reducing and sulfate-reducing bacteria in the sediment of SP were higher than that in the sediment of SCP and MCP, varying between 8.7 9 10 4 and 1.86 9 10 6 ,2.1 9 10 4 and 1.1 9 10 5 ,and9.3 9 10 1 and 1.1 9 10 4 CFU g -1 , respectively. In contrast, the counts of ammonium-oxidizing and nitrifying bacteria in the sediment of SP was lower than that in the sediment of SCP and MCP. Denaturing gradient gel electrophoresis (DGGE) of 16S rDNA gene and dendrogram analyses showed that bacterial diversity in the mixed-culture environment was higher than that in the monocultures. The similarity of bacterial community between EC and SCP or MCP was higher than that between EC and SP. These results indicated that sea cucumber culture played a significant role in influencing the environmental bacterial communities that were composed mainly of Flavobacteriaceae (64.3%), Bacteriodetes (21%) and delta proteobacteria (14.7%), including the genera of Croceimarina, Lutibacter, Psychroserpens and so on. The results explained the benefit of sea cucumber culture in shrimp ponds at the level of microbial ecology.

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