Determination of Content of Amino Acid in Abalone by Precolumn Derivatization and its Nutritional Value Evaluation

[Objectives] This study was conducted to optimize the determination conditions of amino acids from abalone. [Methods] The sample was treated by acid hydrolysis method and subjected to 2,4-2 nitro fluorobenzene column derivatization. The amino acid content in abalone was determined by HLPC,and the nutritional value of the amino acids was evaluated with egg protein model put forward by Institute of Nutrition and Food Hygiene,Chinese Academy of Preventive Medicine. [Results] Abalone contains full amino acids. According to the FAO/WHO ideal,it is a high-quality protein source and suitable for supplement of protein source for human body. [Conclusions]The experimental method has simple operation and could achieve a good effect with wide linear range and correlation coefficient over 0. 999 8,and the obtained results are satisfactory.

The Optimization of Ultrasonic-assisted Extraction of Polysaccharide from Sipunculus nudus by Response Surface Methodology and Study on Antioxidant Activity

[Objectives]This study was conducted to optimize the extraction process of Sipunculus nudus polysaccharide and study the antioxidant activity of S. nudus polysaccharide. [Methods] S. nudus polysaccharide was extracted by ultrasonic microwave assisted method,during which univariate factors including solidliquid ratio,time,temperature,ultrasonic power,microwave power were investigated,to select optimal extracting conditions,which were also verified by an response surface optimization experiment( an four-factor three-level test); and the antioxidant activity of S. nudus polysaccharide was studied by determining its DPPH radical scavenging capacity. [Results]Through univariate factor investigation and response surface optimization test,it was found that the response surface results were consistent with univariate results. The optimized conditions were as follows: solid-liquid ratio at 1∶ 15,ultrasonic temperature at 60 ℃,ultrasonic power of 360 W and microwave power of 200 W,and the predicted polysaccharide extracting amount was 4. 35 mg/g. Under the optimized extracting conditions,the average extracting amount of S. nudus polysaccharide was 4. 38 mg/g,which is close to the theoretical predicted value( 4. 35 mg/g). And the results of this study also showed that different concentrations of polysaccharide solutions have different scavenging effects on DPPH free radical. At the polysaccharide concentration of0. 16 mg/ml,the maximum value of DPPH radical scavenging rate was 7. 22%,indicating that polysaccharide has certain antioxidant capacity. [Conclusions]This method is a new trial with satisfactory results.

DNA Barcode Screening and Preliminary Study on Phylogeny of Sea Snake Based on Genes COI and cytb

[Objectives]The most common gene fragment used in animal DNA barcode technology is COI,but it is not necessarily suitable for all species.This study was conducted to screen genes suitable for the DNA barcode of sea snakes.[Methods]All COI and cytb gene sequences on GenBank were searched and downloaded.After the comparison with Mega software,clustering trees of MrBayes system were established.[Results]Interspecies distances were greater than intraspecies distances for the two genes.The topological structures of their molecular hierarchical clustering trees were clear,and the support rates were high.[Conclusions]Therefore,it is concluded that not the DNA barcode of each species must be gene COI.Cytb is more suitable in terms of the mitochondrial gene of sea snakes.

Study on Extraction Process of Sipunculus nudus Polysaccharide and Its Antioxidant Activity

[Objectives] This study was conducted to optimize the extraction process of Sipunculus nudus polysaccharide. [Methods]S. nudus polysaccharide was extracted by ultrasonic water extraction,with the marine S. nudus as a raw material from Sanya City,Hainan Province,by single factor variable method,to find the optimal extraction conditions including ultrasonic power,solid-liquid ratio,ultrasonic extraction temperature,ultrasonic extraction time,ultrasonic extraction times and lye concentration. The absorbance of the polysaccharide was determined by an ultraviolet spectrophotometer,and polysaccharide yield were calculated. The antioxidant activity of scavenging hydroxyl and DPPH radicals was measured at different concentrations. [Results]The optimal extraction conditions for S. nudus polysaccharide were as follows： solid-liquid ratio at 1∶11 mg/ml,extraction temperature at 60 ℃,three times of ultrasonic extraction,ultrasonic power of 960 W,extraction time of 1. 5 h,and lye concentration of 5%,under which the polysaccharide yield was 3. 21%. The scavenging rates of hydroxyl radical and DPPH radical were 12. 58% at the concentration of 0. 20 mg/ml. Moreover,the scavenging rates increased significantly with the increase of concentration. [Conclusions] This method is a new trial with satisfactory results.

The critical stage for inducing oviparity and embryonic diapause in parthenogenetic Artemia(Crustacea: Anostraca): an experimental study

The brine shrimp Artemia exhibits two reproductive modes: 1) oviparity, producing diapause embryos;and 2) ovoviviparity, producing free-swimming nauplii. Previous studies have suggested the existence of a critical stage that determines the reproductive mode. Physicochemical factors, such as photoperiod, temperature, and salinity, have been suggested to irreversibly aff ect the reproductive mode of oocytes during this critical stage. In this study, experiments were carried out using a photoperiod and temperature-sensitive parthenogenetic Artemia clone where maternal Artemia were shifted bidirectionally between ovoviviparity (18 h L:6 h D, 27℃) and oviparity (6 h L:18 h D, 19℃) culture conditions. In the main experiment ( Artemia shifted at six diff erent stages including the post-larva Ⅱ to adult Ⅱ), the reproductive mode of fi rst brood was converted when shifting was performed on post-larva Ⅱ and Ⅲ but was not converted when females were shifted after post-larva Ⅲ. A supplementary experiment further revealed that the reproductive mode of fi rst brood could be altered when shifting females at an "early phase of postlarva Ⅳ", characterized by a developing ovisac reaching the middle of the third abdominal segment, ventral spines, and some oocytes growing larger than the others. In both experiments, reproductive modes of the second brood were signifi cantly aff ected when the shifting was performed on post-larva Ⅳ. These results suggest that the critical stage for inducing oviparity and embryonic diapause is at the previtellogenic stage of oocytes, or at maternal "early phase of post-larva Ⅳ" for the first-brood off spring. During this stage, diff erential gene expression patterns of the two destined oocytes may be triggered by the token stimuli signals received by the oocytes.

The Exploration of Trimeresurus Divided to Multiple Genera Based on Molecular Systematics

According to the contradictions about classification on Trimeresurus between ＂China＇s Fauna＂ and international database, the rationality about Trimeresurus divided to multiple genera based on molecular systematies was discussed. The genetic distance was calculated by sequencing 12S gene of the original Trimeresurus snakes, including 80 individuals of 33 species ; and the molecular phylogenetie tree was established by taking Hypnale hypnale as the outgroup. The results showed that the topological structures of ME tree and ML tree were basically consistent, and all of the species in the molecular trees were divided into 8 branches; and the difference of T. albolabris between Hainan and other locations is not obvious. The viewpoint that original Trimeresurus genera subdivided into 8 genera was more rational, and new authoritative reference books are expected to be published in China.