Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 219-232). Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2009. / Includes bibliographical references. Also available in PDF format via the Internet.

Astragalus diaphanus is a rare plant endemic to the John Day River drainage of north-central Oregon. This species has several interesting features, including the dimorphism of its fruit and its geographical isolation from the two nearest taxonomically related species, which occur in Colorado. This study addressed the species' distribution and habitat, the taxonomic relationships between the varieties of A. diaphanus, certain morphological comparisons among the species, possible reasons for the rarity of A. diaphanus, and the population biology of this taxon. Astragalus diaphanus was found to be more widespread in the John Day drainage than was previously known, but its range has shrunk due to habitat loss along the Columbia River. In this study, two varieties are recognized within a single species, based on striking morphological differences in pod forms which correspond to a break in geographical distribution. Other morphological characters are similar between the varieties. Flavonoid analysis and chromosome counts support this taxonomic treatment. Further study is needed to elucidate the relationships of A. diaphanus and its taxonomic relatives in Colorado. A low reproductive rate in A. diaphanus appears to be a potential problem, possibly contributing to its rarity. The species exhibits a combination of annual and biennial lifecycles. Many annual individuals of A. diaphanus perish without reproducing. This may be off-set by a large seedbank, which is replenished sporadically by high production in robust biennials. There is not a need at the present time to provide legal protection to var. diaphanus, the more widespread and common taxon. However, var. diurnus has a very limited distribution along the South Fork of the John Day River and is represented by few populations. Many of these are marginally viable, and there are active threats to the existence of the latter variety. Astragalus diaphanus var. diurnus should be afforded legal protection as an endangered species. / Graduation date: 1991

No description available.

Thesis (M.S.)--Brigham Young University. Dept. of Plant and Wildlife Sciences, 2007. / Includes bibliographical references.

No description available.

背景黃芪是中醫藥中最常用的補益藥之一，現代研究發現其多糖類成分具有抗疲勞、抗氧他和免疫調節等作用，因此研究黃芪多糖的生理活性已成為研究黃芪藥理作用新的主流方向。由於多糖類物質分子量較大，單糖組成及組成方式多樣，所以對多糖的研究除生理活性外還需探討解析其他學特征。目的初步驗證黃芪多糖對免疫系統的生理活性及其自身他學組成，探討展望未來對黃芪多糖研究的新方向。方法本實驗採用水提醇沉法提取分離除黃芪粗多糖，經除蛋白及透析等操作純忙得到黃百多糖。採用高效凝膠色譜分離法及超高效液相色譜法分別求得黃芪多糖相對分子量大小及其單糖組成成分免疫活性探究使用RAW264.7 細胞系巨噬細胞，以脂多糖為陽性對照，採用MTT 法測試細胞毒性，計算加藥后一氧化氮及細胞因子IL-6 和TNF－α 生成量，評價黃芪多糖的免疫調節作用。結果黃芪多糖相對分子量為108.02kDa(±2.73kDa），由阿拉伯糖、葡萄糖、半乳糖、葡萄糖醛酸和半乳糖醛酸組成。MTT 實驗表明黃芪多糖對細胞無明顯毒性﹔ NO 及細胞因子IL-6 和TNF－α 生成量表明其具有免疫調節功能，且作用強度與黃芪多糖濃度在一定範圍內呈正相關。結論黃芪多糖具有免疫調節活性，但其組成成分較多，他學結構複雜，仍需要進行更多研究探討其作用機制及其他學結構與免疫調節機制的關係。【關鍵詞】黃芪多糖﹔化學組成﹔免疫活性

This investigation was concerned with the taxonomic relationship between Astragalus beckwithii (Torr. & Gray) var. beckwithii, Astragalus oophorus (S. Wats) var. caulescens (Jones) Jones, and Astragalus megacarpus (A. Gray). An attempt was made to relate some chemical constituents and the toxic effects on rats to the taxonomy. A number of parameters were used; rat toxicity, lipid analysis, selenium atomic absorption, various salts and glucose percentages, as well as the usual morphological measurements taken from herbarium specimens, field observations, and pollen measurements. While the weight of the data indicates that A. beckwithii is a type of intermediary or intergressory product of A. oophorus and A. megacarpus, and that it very closely resembles A. oophorus, it would be premature to suggest combining A. beckwithii and A. oophorus until the related varieties in each species are also studied. Evidence shows definite symptoms of locoism in the white rats tested. A hypothesis was made that the toxic principles in these plants are associated with the nitrile compounds.

The purpose of this study is to investigate the level and distribution of genetic variation in Astragalus jaegerianus by using molecular markers. The objectives of the study are: to estimate levels of genetic variation within and among populations of Astragalus jaegerianus; to test the hypothesis that levels and patterns of genetic variation in species of restricted ranges and few individuals is low and partitioned at the population level; and to discern whether, or how well, genetic partitioning of Lane Mountain milk vetch correlates with its geographic partitioning in the field.