裂褶多糖的羧甲基化

采用氢氧化钠-氯乙酸反应体系,以异丙醇为溶剂,利用L9(34)正交试验合成mg级的不同取代度(DS)的羧甲基化裂褶多糖。研究表明试验条件下各因素对DS值影响由大到小的顺序为:氯乙酸/裂褶多糖(g/g)>氢氧化钠/裂褶多糖(g/g)>反应时间>反应温度。其红外光谱在1600 cm-1出现-COO-特征吸收;其紫外光谱在200~300 nm没有明显的吸收峰。对其13C NMR化学位移进行了归属。     

红松天然种群邻体影响半径

以天然红松种群为研究对象,采用生长方程回归分析、分段拟合判定的方法,探讨不同坡位红松邻体影响半径的变化．结果表明,红松树种邻体干扰指数与生长量呈显著负相关（R^2为0．61～0．89）,相关程度因邻体影响范围和坡位而异,R^2达到最大值所对应的影响范围即为邻体影响半径;对红松树种进行邻体干扰指数与影响范围的线性分段拟合,邻体干扰指数随影响范围的增加而增加,其在一定的范围内上升较快,而超出该范围则上升幅度变缓,其转折点所对应的影响范围即为邻体影响半径,线性回归显著（R^2为0．41～0．55）;不同坡位的邻体影响半径有一定的差异,表现为下坡位=上坡位〉中坡位．     

江西桃红岭自然保护区夏季梅花鹿对生境的选择性

2005年6-8月在江西桃红岭自然保护区对夏季梅花鹿的生境选择性进行了初步研究。结果表明：梅花鹿选择灌丛和灌草丛、郁闭度较低、灌木盖度较小、食物丰富度高、阴坡、中上坡位、坡度平缓、水源距离在100-400m、人为干扰距离〉800m和海拔高度〉300m的环境;对郁闭度〉80％和水源距离≤100m的环境表现为随机选择。     

不同特性粘数壳聚糖降血浆胆固醇、甘油三酯及抗氧化活性研究

通过醋酸-H2O2氧化降解法制备三种不同特性粘数（50℃时,η=4．76mL／g,29．39mL／g和54．93mL／g）的壳聚糖。以小鼠为实验对象,采取灌胃给药方式,考察其降低血浆TCH、TG的能力,并以血浆SOD酶活及MDA含量为指标,进行抗氧化药效学评价。结果显示,给药21d后,三种壳聚糖均能显著降低小鼠血浆TCH和TG含量,降幅分别大于28．2％和22．5％;且三种壳聚糖也能显著降低小鼠血浆MDA含量,降幅大于30．0％,但对小鼠血浆SOD酶活则无显著影响。     

天然产物在新药开发中的应用--HMG-CoA还原酶抑制剂新药的发现对天然产物研究与开发的启示

自1973年发现第一个作用于HMG-CoA还原酶的化合物mevastatin以来,多个具有HMG-CoA还原酶抑制活性的抗高血脂新药被开发成功,并成为治疗高血脂症的首选药物。在此简单介绍该类新药的发现与开发过程,并就天然产物的研究与开发提出一点个人见解。     

用RACE技术扩增并克隆牛BMP4基因3′端序列

RACE技术是一项扩增基因末端序列的新技术。该研究从牛BMP4基因出发,以牛软骨的RNA为模板,按照不同物种BMP4基因的相似性设计特异引物,运用PCR和RACE技术扩增并获得了特异片段,该片段经PCR、酶切和测序验证,证实所克隆序列为牛BMP4的3′端序列,包含有1170bp组成的开放读码框(ORF),编码389个氨基酸,3′非编码区121bp个核苷酸和poly(A)15。同源性分析结果表明,牛BMP4 cDNA最大开放读码框所推测的氨基酸序列与已知人、小鼠、大鼠、狗、羊和鸡等真核生物BMP4氨基酸序列进行比较,分别有94.5%、93.1%、91.9%、87.4%、94.2%、79%的同源性。这为克隆其他物种的BMP4基因提供了依据,同时牛骨形态发生蛋白的测序为我们更好的理解牛的生骨机理提供帮助。     

蛹虫草固体发酵大豆基质的成分及抗氧化活性变化研究

以大豆为培养基质,对蛹虫草固体发酵过程中的pH值、淀粉酶、蛋白酶、总糖、还原糖、总酚、ABTS自由基清除率和FRAP进行测定,分析各种物质含量及抗氧化活性变化。结果表明,发酵过程中pH值、淀粉酶和蛋白酶先增加后减少,还原糖含量随着发酵时间延长不断下降,可溶性总糖先减少后增加。总酚含量、ABTS自由基清除率和FRAP值随着发酵时间延长先减少后增加,22d达最大值。发酵成品有望开发成为食品基料及抗氧化食品。     

Application of DNA barcodes in Hedyotis L. (Spermacoceae,Rubiaceae)

The potential application of DNA barcodes of plastid (matK, trnH–psbA, petD, and rbcL) and nuclear (internal transcribed spacer (ITS) of rDNA) DNA regions was investigated for 25 Hedyotis taxa. The ITS showed the best species discrimination by resolving 23 of the species as exclusive lineages with no shared alleles between any of the 24 distinct species (H. assimilis and H. mellii are not supported as distinct species based on our molecular and morphological data). Conversely, rbcL performed the worst and only resolved 10 of the species as exclusive lineages, and 10 species with shared alleles. Using ITS has the advantage of high PCR amplification success and it provides good intra- and interspecific variation distribution patterns. The most powerful plastid markers were petD and trnH–psbA, but we could amplify and sequence trnH–psbA for only 83% of the accessions sampled. Combination of ITS and petD performed extremely well, with all 24 of the distinct species resolved as exclusive lineages and no shared alleles between any of the distinct species. We therefore recommend ITS, or a combination of ITS and petD, as the standard DNA barcode in Hedyotis, but acknowledge that there are no shared alleles between distinct species for matK and rbcL combined.     

Anatomical reinvestigation of Archaeopteris macilenta from the Upper Devonian (Frasnian) of South China

Abstract Archaeopteris macilenta is one of the most widespread plants in the Late Devonian. Based on fossils from the Frasnian Huangjiadeng Formation, Yichang District of Hubei Province, for the first time we study in detail the anatomy of this progymnosperm plant in South China. Ultimate axes are protostelic with three xylem sympodia and lack secondary tissue. Penultimate axes are eustelic, bearing eight sympodia and a thin band of secondary xylem. Radially symmetrical sympodia of mesarch primary xylem produce traces of appendages in a spiral arrangement. Archaeopteris macilenta and A. halliana (A. roemeriana) are dominant in the Frasnian and Famennian, respectively. Comparisons with these two species from other tectonic plates indicate consistent stelar architectures. Global spread, continuous occurrence, and identical anatomy during the Late Devonian indicate that Archaeopteris survived the Frasnian–Famennian extinction event. In this time, endemic genera and cosmopolitan taxa, including Archaeopteris, suggest the palaeogeographic isolation of South China and certain associations with other plates.