Studies on Models,Patterns and Require-ments of Digestible Amino Acids for Layers by Nitrogen Metabolism

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桩景造型的快速可塑性

笔者1994年获得一蔸细叶榕树桩,主干高40厘米,上粗15厘米,下粗11厘米,共有6条丛生枝在主干上端水平线上,粗度相似,不分主次(见墨图1),粗一看是低劣桩材。其实细叶榕树种,生长快,易成型,愈合力强,且不见人工痕迹。又是黑树皮,生气根多,可快速改变主干的不足。同时树龄不老,枝干     

Ultrastructural Changes of Sphaerotheca fuliginea （Schlechtend.：Fr.） Pollacci in Cucumber After Treated by Chrysophanol

Chrysophanol (1,8-dihydroxy-3-methylanthraquinone) is a free anthraquinone compound and a secondary metabolite of medicinal plant rhubarb.Chrysophanol has been reported to have both protective and cura...     

Vertical patterns of the flora of seed plants in Dawei Mountain in Yunnan Province, Southwest China

Vertical gradients incorporate multiple resources gradients which vary continuously. Therefore, research on mountain flo-ristic patterns along vertical gradients is important to reveal regular patterns of the flora along environmental gradients and to under-stand the changes in biodiversity along these gradients and their biological fitness. This study was designed to explore the character-istics of the floral compositions and ecological significance of floristic patterns along the vertical gradients of the National Nature Reserve of Dawei Mountain, located in the southeast of Yunnan Province. We analyzed the structural characteristics of the flora and the distribution patterns of its floristic components as a function of elevation on the basis of our field investigations along vertical vegetation transects. We carried out a systematic cluster analysis in order to determine the dividing line of floristic changes by eleva-tion along gradients and studied the effects of mountain climate on the vertical variation of floristic composition. The study shows: 1) that the obvious boundary, which differentiates tropical distribution, is located at an elevation of approximately 1,500 m, which separates the tropical rain forests from the evergreen broad-leaved forests; 2) that humid rain forests are found below 700 m elevation, mountain rain forests between 700 and 1,500 m, monsoon evergreen broad-leaved forests between 1,300 and 1,800 m and mountain mossy evergreen broad-leaved forests above 1,800 m. Non-representative mountain mossy dwarf forests (above 2,100 m) in the area are found on the windward sides and barren lands on mountain slopes; 3) that Hopea mollissima is one of the major component species of mountain rain forests, but it should not be considered as the major indicator species in humid rain forests as is generally accepted.     

Insect resistance to Nilaparvata lugens and Cnaphalocrocis medinalis in transgenic indica rice and the inheritance of gna+sbti transgenes

Molecular genetic analysis and insect bioassay of transgenic indica rice 'Zhuxian B' plants carrying snowdrop lectin gene (gna) and soybean trypsin inhibitor gene (sbti) were investigated in detail. PCR, 'dot' blot and PCR-Southern blot analysis showed that both transgenes had been incorporated into the rice genome and transmitted up to R3 progeny in most lines tested. Some transgenic lines exhibited Mendelian segregation, but the other showed either 1:1 (positive: negative for the transgenes) or other aberrant segregation patterns. The segregation patterns of gna gene crossed between R2 and R3 progeny. In half of transgenic R3 lines, gna and sbti transgenes co-segregated. Two independent homozygous lines expressing double transgenes were identified in R3 progeny. Southern blot analysis demonstrated that the copy numbers of integrated gna and sbti transgenes varied from one to ten in different lines. Insect bioassay data showed that most transgenic plants had better resistance to both Nilaparvata lugens (Stahl) and Cnaphalocrocis medinalis (Guenee) than wild-type plants. The insect resistance of transgenic lines increased with the increase in transgene positive ratio in most of the transgenic lines. In all, we obtained nine lines of R3 transgenic plants, including one pure line, which had better resistance to both N lugens and C medinalis than wild-type plants.