Isolation and Identification of Bacterial Pathogens of Proteus vulgaris and Chryseobacterium meningosepticum from Peodiscus sinensis and Observation on the Histopathology

Two dominant strains of bacteria Lb18-01 and Lb18-02 were isolated and purified from scabies,liver and intestine of diseased Peodiscus sinensis.By artificial infection test,the two strains were verified as pathogenic strains with similar characters to that of natural infectious cases.The strains Lb18-01 and Lb18-02 showed strong pathogenicity to healthy P.sinensis in the artificial infection experiment,so they were the pathogenic strain of the disease.According to the morphology,physicochemical characteristics,16 S rDNA sequence analysis and phylogenetic tree clustering,the pathogenic strains Lb18-01 and Lb18-02 were identified as Proteus vulgaris and Chryseobacterium meningosepticum which were tolerant to 20 drugs such as penicillin,tetracycline and ampicillin.Histopathological observation on diseased P.sinensis showed the pathological symptoms of sepsis such as hemorrhage and congestion of liver,spleen and intestine,and glomerular disintegration.

Strong Genetic Differentiation of <i>Glytothorax zanaensis</i>(Wu et al. 1981) in Nu River, China

The Nu River Project comprised of 13-dam cascade is one of the biggest hydropower development projects yet conceived in China. However, hydropower development will inevitably result in the local ecological environment and biological material impact, particularly the effects on fish. Glyptothorax zainaensis is weak in swimming with suction cup and is extremely sensitive in the hydrological characteristics and water quality changes, so that it can be considered as a water quality monitor of indicator organism. Currently, with the need for conservation, fishery restoration and so on, there is a great demand for genetic information on Glyptothorax zainaensis. Fourty microsatellite loci were isolated, characterized and evaluated from Glyptothorax zainaensis. A total of 91 different alleles were observed in the 303 wild Glyptothorax zainaensis, and the percentage of polymorphic bands ranged from 41.8% to 66.7%, with an average of 90.1%. The genetic diversity value was significantly huge with the expected heterozygosity ranging from 0.578 to 0.706, the observed heterozygosity value ranging from 0.923 to 0.980 and PIC value ranging from 0.418 to 0.644, which showed that the wild Glyptothorax zainaensis population had a high level of genetic diversity. Analysis of molecular variance (AMOVA) and pairwise Fst showed a significant level of genetic differentiation (P < 0.01) among the populations accounting for 40.2% of the total variance. Additionally, results derived from different statistical techniques with different software packages included cluster analysis on NJ tree. Apart from such molecular approaches, we opposed four ways to strengthen the effective resources protection.

DNA Extraction from Formalin Fixed <i>Coilia macrognathos</i>Fin Tissues

Approximately 200 mg of fin tissue from each specimen was cut into pieces and treated with a gradient of ethanol (65%, 70%, 75%, 80%, 85%, 90%, 95% and 100%) and then DNA was extracted from formalin fish fin tissues. Agarose gel visualization of the DNA confirmed DNA extracted. MtDNA cyt b gene banding pattern of samples with agarose gel was clearly visible and could be used to be sequenced. In terms of DNA purity, the 260/280 ratio of 87.5% samples ranged between 1.8 and 2.0, indicating that DNA of the majority of the samples was pure. The developed DNA extraction procedure from formalin fish fin tissues by pretreatment with a gradient of ethanol system will be a useful tool to study the genetic structure and phylogenesis of endangered fish, by specimens preserved formalin-fixed in museum and herbarium.

Genetic diversity and population structure of the Chinese lake gudgeon (Sarcocheilichthys sinensis) using microsatellite markers

The Chinese lake gudgeon is a small benthopelagic freshwater fish.It is presently threatened by human activities and environmental factors in China.Understanding the genetic diversity and population structure is fundamental for implementation of appropriate conservation measures and a sustainable management program.However,little is reported about the current genetic diversity and population structure.Here,we used ten microsatellite markers to genotype 175 individuals from six populations.Low levels of genetic diversity were found in all six tested populations.The Xiang river population showed the highest level of genetic diversity.Genetic differentiation was very low but significant among the Changyang,Changqidang and Mayang populations,but the Qiandao lake,Gan river,Xiang river populations all showed significant and strong differentiation from the other three populations.Contemporary gene flow was observed in among Changyang,Changqidang and Mayang populations and between Gan and Xiang river populations,respectively.This is the first genetic study to report the genetic diversity and population structure of S.sinensis and the results will be used to develop management and conservation strategies.