Effects of nitrogen specification and culture method on growth of Enteromorpha prolifera

Eutrophication, which is the enrichment of a water mass with inorganic and organic nutrients that support plant growth, is a key factor in stimulating phytoplankton growth. In this study, we determined the effects of various nitrogen sources, different nitrogen concentrations in the culture medium, and two culture methods on the growth of the green alga, Enteromorpha prolifera. The relationship between the specific growth rate of E. prolifera and NO3-N concentration was consistent with that estimated using the Monod equation （R2=0.9713, P〈0.01）. In the N O3-N medium, the maximum specific growth rate was calculated to be 0.1634/d and the semi-saturation constant was calculated to be 16.86 μmol/L. Our results show that E. prolijkra can effectively utilize NH4^＋-N, NO3^-N, and NO^2-N and urea-N in the range of 5 to 50 μmol/L. NH4^＋-N was preferentially assimilated by E. prolifera, and urea-N was favorable for long-term growth.

Effect of culture methods on individual variation in the growth of sea cucumber Apostichopus japonicus within a cohort and family

There is substantial individual variation in the growth rates of sea cucumber Apostiehopus japonicus individuals. This necessitates additional work to grade the seed stock and lengthens the production period. We evaluated the influence of three culture methods （free-mixed, isolated-mixed, isolated-alone） on individual variation in growth and assessed the relationship between feeding, energy conversion efficiency, and individual growth variation in individually cultured sea cucumbers. Of the different culture methods, animals grew best when reared in the isolated-mixed treatment （i.e., size classes were held separately）, though there was no difference in individual variation in growth between rearing treatment groups. The individual variation in growth was primarily attributed to genetic factors. The difference in food conversion efficiency caused by genetic differences among individuals was thought to be the origin of the variance. The level of individual growth variation may be altered by interactions among individuals and environmental heterogeneity. Our results suggest that, in addition to traditional seed grading, design of a new kind of substrate that changes the spatial distribution of sea cucumbers would effectively enhance growth and reduce individual variation in growth of sea cucumbers in culture.

The Effect of Three Culture Methods on Intensive Culture System of Pacific White Shrimp (Litopenaeus vannamei)

Different culture methods may affect the intensive culture system of Pacific white shrimp(Litopenaeus vannamei) regarding water quality and growth and economic performance.This study evaluated the potential effects of three culture methods through cultivation of juvenile shrimps under consistent tank management conditions for 84 d.The three methods involved shrimp cultivation in different tanks,i.e.,outdoor tanks with cement bottom(mode-C),greenhouse tanks with cement bottom(mode-G) and outdoor tanks with mud-substrate(mode-M).Results showed that water temperature was significantly higher in mode-G than that in mode-C(P < 0.05).In contrast to the other two treatments,mode-M had stable pH after 50 d cultivation of shrimps.In the mid-late period,the average concentrations of TAN,NO2-N,DIP and COD were significantly lower in mode-M and mode-G compared with those in mode-C(P < 0.05).Despite lack of differences in the final shrimp weight among different treatments(P > 0.05),mode-M had significantly higher shrimp yield,survival rate and feed conversion rate(P < 0.05) than other modes.There were significant differences in revenue and net return among different treatments(P < 0.05).These demonstrated that the treatments of mode-G and mode-M were conductive to the intensive culture system of L.vannamei.

Gut bacteria alteration in obese people and its relationshipwith gene polymorphism

AIM:To investigate the differences in cultivable gut bacteria and peroxisome proliferator-activated receptor γ2(PPAR-γ2) gene Pro12Ala variation in obese and normal-weight Chinese people.METHODS:Using culture methods,the amounts of Escherichia coli,Enterococci,Bacteroides,Lactobacilli,Bif idobacteria and Clostridium perfringens(C.perfringens) in the feces of 52 obese participants [body mass index(BMI):≥ 28 kg/m2] and 52 participants of normalweight(BMI:18.5-24 kg/m2) were obtained.Study participants completed comprehensive questionnaires and underwent clinical laboratory tests.The polymerase chain reaction-restriction fragment length polymorphism(PCR-PFLP) assay was used to analyze PPAR-γ2 gene Pro12Ala variation.RESULTS:The obese group exhibited a lower amount of C.perfringens(6.54 ± 0.65 vs 6.94 ± 0.57,P = 0.001)and Bacteroides(9.81 ± 0.58 vs 10.06 ± 0.39,P = 0.012) than their normal-weight counterparts.No major differences were observed in Pro12Ala genotype distribution between the two groups;however,obese individuals with a Pro/Ala genotype had a signif icantly lower level of Bacteroides(9.45 ± 0.62 vs 9.93 ± 0.51,P = 0.027) than those with a Pro/Pro genotype.In addition,the obese group demonstrated a higher stool frequency(U = 975,P < 0.001) and a looser stool(U = 1062,P = 0.015) than the normal-weight group.CONCLUSION:Our results indicated interactions among cultivable gut flora,host genetic factors and obese phenotype and this might be helpful for obesity prevention.

IPM Strategies and Their Dilemmas Including an Introduction to www. eurowheat.org

Information about disease management in winter wheat （Triticum aestiva） in eight European countries was collated and analysed by scientists and extension workers within the European Network for the Durable Exploitation of Crop Protection Strategies （ENDURE）. This included information about specific disease thresholds, decision support systems, host varieties, disease prevalence and pathogen virulence. Major differences in disease prevalence and economic importance were observed. Septoria tritici blotch （Mycosphaerella graminicola） was recognized as the most yield reducing disease in countries with intensive wheat production, but also rust diseases （Puccinia striiformis and Puccinia triticina）, powdery mildew （Blumeria graminis） and Fusarium head blight （Fusarium spp.） were seen as serious disease problems. Examples of current integrated pest management （IPM） strategies in different countries have been reported. Disease management and fungicide use patterns showed major differences, with an average input equivalent to 2.3 full dose rates （TFI） in the UK and a TFI of 0.6 in Denmark. These differences are most likely due to a combination of different cropping systems, climatic differences, disease prevalence, and socio-economic factors. The web based information platform www.eurowheat.org was used for dissemination of information and results including information on control thresholds, cultural practices which can influence disease attack, fungicide efficacy, fungicide resistance, and pathogen virulence, which are all elements supporting 1PM for disease control in wheat. The platform is open to all users. The target groups of EuroWheat information are researchers, advisors, breeders, and similar partners dealing with disease management in wheat.

Inhibition of Aspergillus parasiticus and Cancer Cells by Marine Actinomycete Strains

Ten actinomycete strains isolated from the Yellow Sea off China＇s coasts were identified as belonging to two genera by 16S rDNA phylogenetic analysis： Streptomyces and Nocardiopsis. Six Streptomyces strains （MA10, 2SHXF01-3, MA35, MA05-2, MA05-2-1 and MA08-1） and one Nocardiopsis strain （MA03） were predicted to have the potential to produce aromatic polyketides based on the analysis of the KSa （ketoacyl-synthase） gene in the type II PKS （polyketides synthase） gene cluster. Four strains （MA03, MA01, MA10 and MA05-2） exhibited significant inhibitory effects on mycelia growth （inhibition rate 〉50%） and subsequent aria- toxin production （inhibition rate 〉75%） of the mutant aflatoxigenic Aspergillus parasiticus NFRI-95. The ethyl acetate extracts of the broth of these four strains displayed significant inhibitory effects on mycelia growth, and the IC50 values were calculated （MA03： 0.275 mg mL-1, MA01：0.106 mg mL-1, MA10：1.345 mg mL-1 and MA05-2：1.362 mg mL-1）. Five strains （2SHXF01-3, MA03, MA05-2, MA01 and MA08-1） were selected based on their high cytotoxic activities. The ethyl acetate extract of the Nocardiopsis strain MA03 was particularly noted for its high antitumor activity against human carcinomas of the cervix （HeLa）, lung （A549）, kidney （Caki-1） and liver （HepG2） （IC50： 2.890, 1.981, 3.032 and 2.603 μgmL-1, respectively）. The extract also remarkably inhibited colony formation of HeLa cells at an extremely low concentration （0.5μgmL 1）. This study highlights that marine-derived actinomycetes are a huge resource of compounds for the biological control of aflatoxin contamination and the development of novel drugs for human carcinomas.