营养分型法对淋球菌流行菌株的监测

对１９９３～１９９４年南京地区分离的淋球菌菌株进行营养分型研究，发现Ｐｒｏ－和Ｐｒｏｔｏ占绝大多数，达９５％以上。营养型的构成与１９８９～１９９０年分离的菌株是一致的。这表明当前本地流行株的特点与几年前相同。

淋球菌营养分型的研究进展

营养分型是淋球菌最常见的分型方法之一,它是根据菌株对氨基酸等营养物质的需求不同而进行分类,其遗传学基础是菌株某一特殊生物合成途径中编码酶的基因缺陷。营养分型与血清分型、耐药性、质粒、临床特征均有一定关系,不同地区、时间、性别,营养型可不相同。这种分型方法稳定,重复性好,可用于监测疫情,追溯传染源及疗效评估,具有重要的流行病学意义。

广州地区淋球菌血清学和营养分型研究

目的 确定广州地区淋球菌血清型和营养型流行特点。方法 采用乳胶凝集法对 131株淋球菌进行血清学分型和 La Scolea法分析 108株淋球菌营养型。结果 血清学分型以 WⅡ /WⅢ为主，占 87.8％ (115/131), WⅠ 型仅为 9.9％ (13/131)；营养型则以 Proto、 Proˉ和 ILeˉ 3种营养型为主，分别占 42.6％、 21.3％和 12.0％；另外 WⅠ 仅见于 Proto和 Proˉ营养型， WⅡ /WⅢ可见于所有营养型。结论 血清型 WⅡ /WⅢ的优势群和营养型中 ILeˉ型明显高于其它省份是广州地区淋球菌流行的两大特点。

淋病奈瑟菌分型的研究进展

淋病奈瑟菌(淋球菌)分型可追溯细菌的来源,了解其地域分布和流行情况,对淋病的防治具有重要意义。常用的淋球菌分型方法有:营养、血清学、营养/血清学双重、植物凝集素、基因、耐药谱和质粒分型等。本文就当前的分型概况予以介绍。

Effects of Different Types of Chinese Fir Stands on Nu－trient Status of Soils

The effects of different types of Chinese fir stand, including those with various composition (pure andmixed), in various cropping systems (first and continuous cropping system) and at different ages, on thenutrient status of soils in the hilly regions of southern Anhui Province were studied by means of ecologicalsequential comparison on the basis of similar climate and soil type. The work was carried out in the XiaoxiForest Farm of Jingxian County and the Caijiaqiao Forest Farm of Jingde County, where the soil is parayellowsoil derived from phyllite and sandstone. The results revealed that with the increase of age, Chinese fir purestand could accumulate organic matter and nitrogen in the soil but it resulted in decreasing of soil PH and baseions (especially Ca￣(2+)) compared to its mixed stand with broad-leaf trees such as Chinese sassafra.s. In orderto improve the soil fertility, it would be better to mix Chinese fir with broad-leaf trees when afforestation.In the management of Chinese fir pure stand, base compounds and phosphates should be added to the soilfor maintaining soil fertility and raising forest productivity.

Effect of Nutrient Type on Chemical Composition and Dry Matter Partitioning of Cassava （Manihot esculenta Crantz）

The objective of our study was to determine the effects of four types of fertilisers enrichments （manure potassic （K）, phosphatic （P）, phosphatic and potassic （PK） and nitrogenized, phosphated and potassic （NPK）） on chemical composition and dry matter in cassava （Manihot esculenta） organs （clone 1171） during harvest period. The pots experiment was laid out in randomised complete bloc design with five treatments and four replications. Water, nitrogen, potassium, phosphorus, sodium, total proteins and total lipids contents of the leaves, shoots and tubers were determined. After 9 months growing period, results showed that fertilizer types enriched with K, PK and NPK significantly increased the organic compounds contents of the leaves （P〈0.05）. Furthermore, fertilizers with high phosphorus content significantly increased the lipid contents of the leaves （25%）. Fertilizers enriched with NPK positively influenced the biomass partitioning in Manihot esculenta. Application of fertilizers enriched with NPK led to higher levels of total proteins in the leaves and tubers （70 mg g DM^-1 and 30 mg g DM^-1 respectively） compared to control （17 mg g DM^-1 and 9 mg g DM^-1 respectively）. These results help to demonstrate the value of these fertilizers enrichment to improve the chemical composition and dry matter partitioning of cassava.

Factors Influencing Breast-Feeding Among Women in China

Although a well-established association between breast-feeding and a range of positive health outcomes in children has been demonstrated, less attention has been paid under China circumstance, especially what factors will influence breast-feeding behavior among Chinese women from empirical perspective has not been explored yet. In this paper, survival analysis with duration model is applied to find out the main determinants. The well-known China Health and Nutrition Survey （CHNS） dataset fits for this study since it has plenty information about breast-feeding and children. Family income, age, education level, and maternity leave are found to he the main determinants which have significant effects on the breast-feeding behavior, also the gender of infant plays an important role which is for Chinese-specific cases. The opportunity cost for women with higher education level and higher income, especially in urban areas is so high that they have to shorten the duration of breastfeeding their children. The probability of breast-feeding her child is decreasing with the aging of mother.

Fruit Nutritional Value of Cornelian Cherry Genotypes （Comus mas L.） Selected in the Vojvodina Province

This paper reviews results of some morphometric properties and chemical analyses of natural populations of the Cornelian cherry collected in the Vojvodina Province in 2008. Purpose of this study was the selection of the best genotypes for future breeding program until the final goal and that is standardizing Cornelian cherry cultivars. Chemical content has been found to depend on the genotype. Total sugar content in fruits ranged from 11.77% （CPC16） to 41.62% （BPC7）, vitamin C from 17.15 mg/100 g （APC8） to 42.30 rag/100 g of fresh fruit （APC2）, Ca pectat from 0.17% （APC6） to 2.52% （KC 1 ） and anthocyanin from 22.65 mg/100 g （APC4）to 96.30 rag/100 g of fresh fruit （BPC1）. Cornelian cherry fruits have an especially high content of minerals compared with other fruit species： the potassium content （in ppm） ranges from 2330 （APC6） to 11487 （APC4）, the calcium content from 33.80 （APC6） to 1307.70 （BPC1）, the sodium content from 22.82 （BPC8） to 273.48 （APC8）, the magnesium content from 10.20 （APC6） to 372.80 （APC8） and the iron content from 2.38 （KC2） to 14.40 （APCS）. The balanced content of nutrients, a wide range of food products made from the Cornelian cherry and an extremely high nutritional value make this fruit species a highly recommendable food item, especially if it comes from organic production.

Silicon Affects Transcellular and Apoplastic Uptake of Some Nutrients in Plants

The positive effects of silicon(Si) on growth of plants have been well documented;however,the impact of Si on plant nutrient uptake remains unclear.The growth,nutrient content and uptake of wheat(Triticum aestivum L.),canola(Brassica napus L.) and cotton(Gossypium hirsutum L.) plants were evaluated with or without application of 1.5 mmol L^(-1) Si.Application of Si increased dry weights by 8%,30%and 30%and relative growth rate(RGR) by 10%,13%and 17%in the cotton,canola and wheat plants,respectively.The plant relative water content(RWC) was also increased,but the plant transpiration was decreased by Si application.The uptake and content of Ca^(2+) were 19%and 21%lower in the cotton and wheat plants with Si than those without Si,respectively;however,Si application increased both K^+ and Fe uptake and contents in all plant species.Silicon application reduced B uptake and content only in cotton and increased P and Zn^(2+) contents in all three plant species.The decrease in Ca^(2+) uptake by Si application was sustained even in the presence of metabolic inhibitors 2,4-dinitrophenol and sodium cyanide.Uptake of Ca^(2+) by Si application was enhanced or did not change when plant shoots were saturated with water vapor or their roots were exposed to low temperature.Thus,Si application increased the uptake of transcellularly transported elements like K^+,P,Zn^(2+) and Fe.In contrast,Ca2+ uptake which occurred via both apoplastic and transcellular pathways was decreased by Si application,possibly through reduction of apoplastic uptake.More efficient nutrient uptake might be another promoting effect of Si on plant growth.

Analysis of a stochastic model for algal bloom with nutrient recycling

In this paper, the dynamics of a stochastic model for algal bloom with nutrient recy- cling is investigated. The model incorporates a white noise term in the growth equation of algae population to describe the effects of random fluctuations in the environment, and a nutrient recycling term in the nutrient equation to account for the conversion of detritus into nutrient. The existence and uniqueness of the global positive solution of the model is first proved. Then we study the long-time behavior of the model. Conditions for the extinction and persistence in the mean of the algae population are established. By using the theory of integral Markov semigroups, we show that the model has an invari- ant and asymptotically stable density. Numerical simulations illustrate our theoretical results.

BIFURCATION CONTROL OF A PREDATOR-PREY MODEL BASED ON NUTRITION KINETICS

The existence conditions of Hopf bifurcation for a predator prey model based on nutri- tion kinetics are given. The two results may appear as follows： one is that the model has a stable periodic trajectory from Hopf bifurcation, which shows the system is in an eco- logical balance; the other is that periodic trajectory from Hopf bifurcation is unstable, which indicates the system is in a sharp or catastrophic loss of stability. For the latter, a bifurcation controller is designed to make the periodic trajectory stable. Finally, some simulations are carried out to prove the results.