Effect of Heat Stress on Grain Growth, Starch Synthesis and Protein Synthesis in Grains of Wheat (Triticum aestivum L.) Varieties Differing in Grain Weight Stability

The effect of heat stress on the components of grain weight was analysed in wheat ( Triticum aestivum L.) varieties differing in grain weight stability. The wheat varieties PBW154, Sonalika and Hindi62 were raised in the field (New Delhi, India; 77°12' E, 28°40' N, 228.6 m a.s.l.) at three dates of sowing: 19 November 1992 (DOS I), 14 December 1992 (DOS II) and 18 January 1993 (DOS III). The late-sown crop (DOS III) experienced 6–8 °C warmer temperatures during grain development than the crop sown at the normal time (DOS I). The heat susceptibility index (S) revealed that grain weight was less susceptible to heat in Sonalika and PBW154 than in Hindi62. Heat stress reduced both the grain growth duration (GGD) and the grain growth rate (GGR). The grain weight reduction in PBW154 and Sonalika was mainly due to a reduction in GGR, while that of Hindi62 was due to a reduction in GGD. In vivo studies on starch and protein synthesis in excised endosperm at 15, 25 and 35 °C revealed that both processes were more thermotolerant in Hindi62 than in PBW154. The grain starch content was stable in Hindi62 while that in PBW154 was significantly reduced under heat stress. The grain nitrogen content at maturity increased in both varieties under heat stress. It was concluded that the heat susceptibility of grain weight in Hindi62 was mainly due to a reduction in GGD, although GGR, starch and protein synthesis were more thermotolerant in developing grains of Hindi62 than in those of PBW154.     

猪血浆转铁蛋白与部分经济性状关系的研究——Ⅰ. 多态性与产仔数和日增重的关系

用经改进的聚丙烯酰胺凝胶电泳铁染法,测定了二花脸猪血浆转铁蛋白多态类型,分析了其基因型频率和基因频率,并探讨了猪血浆转铁蛋白多态性与产仔性能和增重速度的相关性。     

Reproductive roles predict sexual dimorphism in internal and external morphology of lake whitefish,Coregonus clupeaformis

Abstract – The different reproductive roles of the sexes can predict the direction and magnitude of sexual dimorphism of external and internal morphology. Males should have enlarged structures that enhance the acquisition of mating opportunities, whereas females are predicted to have enlarged organs that are associated with the production of eggs. We tested these predictions in male and female lake whitefish, a species in which both sexes have similar overall body size and shape. After controlling for body size, male lake whitefish had significantly longer jaws and pectoral and pelvic fins, larger hearts, and more muscle than females. Sexual dimorphism in relative muscle mass may be one of the most fundamental morphological differences between males and females. Females had relatively heavier livers than males. Because the liver is important for the breakdown of fats and vitellogenesis, selection should favour an enlarged liver in females for the processing of energy and the production of large numbers of eggs.     

农业土地规模经营的理论探讨

实现农业土地规模经营,有利于生产力有效运转并取得最佳的规模效益。其适度性受各种因素的影响,具有区域性和动态性。规模经营与劳动生产率有着密切的关系,应该在确保提高土地生产率的基础上来提高劳动生产和土地规模经营的效益。土地适当集中、土地经营主体的总人数尽量精简和劳动组合的优化是优化土地经营规模的三个相互制约的因素。要采取积极的措施逐步实现土地的规模经营。对现有土地经营形式要做具体分析,其调整应从有利于生产力发展出发,在尊重群众意愿的基础上稳步进行。     

Evaluation of sampling methods and assessment of the sample size to estimate the weed seedbank in soil, taking into account spatial variability

As field sampling is time consuming, it is necessary to develop efficient sampling techniques to obtain accurate estimates of the weed seedbank in soil. The relative efficiency between sampling schemes depends on the spatial variability in weed seed density across agricultural fields. Spatial variability of the weed seed density was characterized by theoretical correlograms. A systematic sampling (square grill) scheme was considered and it was found that, taking into account spatial variability, this sampling scheme was more efficient than simple random sampling. As a result, the sample size can be reduced in comparison with that given in previous studies, where spatial correlation was ignored. The reduction depends on the correlation structure defined as a function of the ratio, τ, between the nugget effect and the sill of the variogram. The maximum reduction of the sample size, without loss of either precision or confidence level corresponds to the case where there is no nugget effect, τ = 0. The opposite extreme case, where the reduction is nil, corresponds to the case of a pure nugget effect τ = 1. The abaci based on given expressions are provided to determine the sample size in species whose spatial pattern can be fitted either to a Poisson or to a negative binomial distribution.     

马铃薯块茎淀粉组分高效检测体系的建立及应用

马铃薯块茎淀粉组分(直链/支链淀粉比AM/AP)影响淀粉特性以及决定其在食品和其他工业上的应用。AM/AP的测定对其合理利用以及选育特异淀粉组分的专用品种等具有重要意义。采用96孔板双波长法对马铃薯不同AM/AP比率标准样品进行测试,发现当测试样品AM/AP比率超过制作标准曲线的AM/AP比率(33.3%)时,测试结果明显高估直链淀粉含量。基于96孔板的碘染分析,建立了马铃薯AM/AP比率和最大吸收峰下波长的标准曲线:y=601.88x^0.0215,R²=0.9999。该方法进一步提高了测试准确度和应用范围。利用该方法测试了198个马铃薯品种(系)以及高直链淀粉组分的转基因块茎,明确了收集的马铃薯品种(系)的直链淀粉组成范围为17.4%～33.3%。新建立的马铃薯淀粉组分测试方法为高效准确筛选遗传育种材料以及改良淀粉组分株系提供了方便。     

Identification,Characteristics and Function of Phosphoglucomutase (PGM) in the Agar Biosynthesis and Carbon Flux in the Agarophyte Gracilariopsis lemaneiformis (Rhodophyta)

Agar is widely applied across the food, pharmaceutical and biotechnology industries, owing to its various bioactive functions. To better understand the agar biosynthesis in commercial seaweed Gracilariopsis lemaneiformis, the activities of four enzymes participating in the agar biosynthesis were detected, and phosphoglucomutase (PGM) was confirmed as highly correlated with agar accumulation. Three genes of PGM (GlPGM1, GlPGM2 and GlPGM3) were identified from the G. lemaneiformis genome. The subcellular localization analysis validated that GlPGM1 was located in the chloroplast and GlPGM3 was not significantly distributed in the organelles. Both the GlPGM1 and GlPGM3 protein levels showed a remarkable consistency with the agar variations, and GlPGM3 may participate in the carbon flux between (iso)floridoside, floridean starch and agar synthesis. After treatment with the PGM inhibitor, the agar and floridean starch contents and the activities of floridean starch synthase were significantly decreased; products identified in the Calvin cycle, the pentose phosphate pathway, the Embden-Meyerhof-Parnas pathway and the tricarboxylic acid cycle were depressed; however, lipids, phenolic acids and the intermediate metabolites, fructose-1,6-phosphate were upregulated. These findings reveal the essential role of PGM in regulating the carbon flux between agar and other carbohydrates in G. lemaneiformis, providing a guide for the artificial regulation of agar accumulation.     

乳化剂对4.5%高效氯氰菊酯水乳剂 物理稳定性的影响

以4.5%高效氯氰菊酯水乳剂为研究对象,探讨了乳化剂的种类、用量、亲水亲油平衡值(HLB值)和结构对水乳剂物理稳定性的影响。结果表明:当乳化剂种类选定后,在一定用量范围内,水乳剂的粒径随着乳化剂用量的增加而变小,粒径分布范围变窄,稳定性增强,粒径大小可作为筛选乳化剂最佳用量的指标;乳化剂的HLB值与水乳剂的粒径及粒径分布范围关系密切;乳化剂的结构和水乳剂的乳液抗聚并性存在相关性,适当增加亲油性的饱和碳链长度,有助于提高水乳剂的乳液抗聚并性,进而获得稳定的水乳剂配方。