白刺不同自由授粉家系的生长变异性研究

反映甘肃民勤县白刺分布区生态变化特征信息的55个白刺自由授粉家系,一、二、三年生植株的生长均存在极显著差异,说明这些家系可能属于不同的遗传变异群体。白刺生长的家系间变异较大,且变异性有逐年增大的趋势;不同生长指标间的同一指标上下年度间的生长变异有很大相关性。家系内变异与家系的个体生长状态呈极显著的负相关,生长越好的家系,变异越小,且变异与母株果实和种子特征无关。研究结果为优良生长家系选择奠定了基础。     

水稻田土-水系统中磷素行为及其环境影响研究

土壤测试表明供试土壤已富P.大田试验结果表明,P肥投入提高了土壤树脂P和田面水总P水平,且两者随着时间的推移而下降.但施P后的20d内,有机无机配施P肥对土壤有效P的贡献大于单施化肥P.在施P第7d时,有机无机配施P的田面水总P水平是单施化肥P的3.4倍,是施P量2倍的处理Ⅲ的2.8倍.与有机肥配施的处理,其田表水P素流失潜能较单施化肥大.经33d后,P肥结构对田面水P素的影响不明显.两次水稻季节性排水而导致的P素净流失负荷和P素表观流失率变幅分别为-0.038～0.076kg·hm^-2和0.034～0.100%.从减少水稻田排水P素流失角度考虑,可以认为,施P或土层被搅动后1周内是控制P素流失的主要环节.     

SPATIOTEMPORAL VARIATION OF THE ABUNDANCE OF CALCAREOUS GREEN MACROALGAE IN THE FLORIDA KEYS: A STUDY OF SYNCHRONY WITHIN A MACROALGAL FUNCTIONAL‐FORM GROUP1

The abundance of calcareous green algae was recorded quarterly at 28 sites within the Florida Keys National Marine Sanctuary (FKNMS) for a period of 7 years as part of a sea grass monitoring program. To evaluate the validity of using the functional‐form group approach, we designed a sampling method that included the functional‐form group and the component genera. This strategy enabled us to analyze the spatiotemporal patterns in the abundance of calcareous green algae as a group and to describe synchronous behavior among its genera through the application of a nonlinear regression model to both categories of data. Spatial analyses revealed that, in general, all genera displayed long‐term trends of increasing abundance at most sites; however, at some sites the long‐term trends for genera opposed one another. Strong synchrony in the timing of seasonal changes was found among all genera, possibly reflecting similar reproductive and seasonal growth pattern, but the variability in the magnitude of seasonal changes was very high among genera and sites. No spatial patterns were found in long‐term or seasonal changes; the only significant relation detected was for slope, with sites closer to land showing higher values, suggesting that some factors associated with land proximity are affecting this increase. We conclude that the abundances of genera behaved differently from the functional‐form group, indicating that the use of the functional‐form group approach may be unsuitable to detect changes in sea grass community structure in the FKNMS at the existing temporal and spatial scale of the monitoring program.     

丙型肝炎病毒基因变异及候选保守表位分析

HCV分离株主要分为4个基因型(HCV Ⅰ～Ⅳ),各型间的氨基酸及核苷酸组成同源性均小于80％, 氨基酸变异率分别为C 8%,E1 35%,E2/NS1 53%,NS3 27%,NS4 35%,NS5 39%.不同型别的HCV有不同的地区分布特征.根据HCV表达产物多肽的保守性、亲水性、抗原性及空间构型等特性,已在HCV表达产物中鉴定出一些高度保守的候选B细胞表位及T细胞表位, 其中B细胞表位一般为12～40肽, T细胞表位一般为7～9肽, 这些B/T细胞保守表位的鉴定, 将有助于推动HCV的免疫治疗及疫苗研究的发展.     

亚洲玉米螟体重和体型的地理变异

为探明亚洲玉米螟Ostrinia furnacalis体重和体型地理变异,我们详细比较了来自4个不同地理种群（海南乐东18.8°N, 109.2°E),广西阳朔24.8°N, 110.5°E),江西南昌28.8°N, 115.9°E)和河北廊坊39.5°N, 116.7°E)）亚洲玉米螟的体重、体型大小及其与采集地纬度的关系。结果表明：不同地理种群的亚洲玉米螟卵重随纬度的升高而逐渐增大,符合贝格曼法则(Bergmann’s law), 而雌雄蛹重及成虫体长、后足腿节长和前翅长均随纬度的升高而逐渐减小, 符合反贝格曼法则(Converse Bergmann’s law)。雌虫的前翅显著长于雄虫, 其性体型二型性符合任希法则(Rensch’s rule),即在雌虫体型较大的种群中,雄虫前翅比雌虫前翅增长幅度相对较大。本文结果进一步揭示了即使在同一种类昆虫中,其各个虫态体重和体型的地理变异也可能不同。     

颈槽蛇的地理变异

地理变异是蛇类中较为常见的现象。颈槽蛇Rhabdophis nuchalis在中国具有广泛的地理分布,是研究地理变异的理想物种。统计分析采自中国各地的61号颈槽蛇标本外部形态特征,对其地理变异模式进行了研究。结果表明:来自云南省高黎贡山的种群与其他种群在眶后鳞数、腹鳞数、上唇鳞黑纹的数量和后颔片间是否有小鳞等形态特征上的差异有统计学意义。     

香椿种质生长及叶部表型性状的遗传变异分析

以84个香椿(Toona sinensis(A.Juss.)Roem.)种质为材料,对其2个生长性状和18个叶部性状(包含6个质量性状和12个数量性状)进行测定。结果显示,香椿6个叶部质量性状变异类型丰富,呈现出多态化特点,单一性状的主要表型多为1~2个。苗高、地径及叶部表型等14个数量性状在种质间的差异均达到极显著水平,且除地径外,其他性状的遗传方差分量均大于环境方差分量,表明此类性状主要受遗传控制。参试的14个数量性状的平均表型变异系数为20.35%,平均遗传变异系数为16.36%;综合表型和遗传变异系数,叶柄长度较其他性状变异大,而叶片夹角稳定性最高,各数量性状(除地径外)遗传变异系数与表型变异系数之差小于7%。香椿种质各性状间Shannon-Weaver遗传多样性指数相差不大(1.892~2.069),遗传多样性水平高,具有良好的遗传改良基础。聚类分析可将84个香椿种质分为5类,类群Ⅰ表现为生长旺盛、小比叶重型;类群Ⅱ生长较快、叶片较大;类群Ⅲ种质数量最多,属生长缓慢、大比叶重型;类群Ⅳ特征为大叶片、多叶型;类群Ⅴ为小叶片、稀叶型。研究结果表明参试香椿种质变异丰富,遗传多样性水平高,能为良种选育、遗传改良等研究提供丰富的遗传材料。     

Nitrate uptake,nitrate reductase distribution and their relation to proton release in five nodulated grain legumes

Nitrate uptake, nitrate reductase activity (NRA) and net proton release were compared in five grain legumes grown at 0.2 and 2 mM nitrate in nutrient solution. Nitrate treatments, imposed on 22-d-old, fully nodulated plants, lasted for 21 d. Increasing nitrate supply did not significantly influence the growth of any of the species during the treatment, but yellow lupin (Lupinus luteus) had a higher growth rate than the other species examined. At 0.2 mM nitrate supply, nitrate uptake rates ranged from 0.6 to 1.5 mg N g(-1) d(-1) in the order: yellow lupin > field pea (Pisum sativum) > chickpea (Cicer arietinum) > narrow-leafed lupin (L angustifolius) > white lupin (L albus). At 2 mM nitrate supply, nitrate uptake ranged from 1.7 to 8.2 mg N g(-1) d(-1) in the order: field pea > chickpea > white lupin > yellow lupin > narrow-leafed lupin. Nitrate reductase activity increased with increased nitrate supply, with the majority of NRA being present in shoots. Field pea and chickpea had much higher shoot NRA than the three lupin species. When 0.2 mM nitrate was supplied, narrow-leafed lupinreleased the most H+ per unit root biomass per day, followed by yellow lupin, white lupin, field pea and chickpea. At 2 mM nitrate, narrow-leafed lupin and yellow lupin showed net proton release, whereas the other species, especially field pea, showed net OH- release. Irrespective of legume species and nitrate supply, proton release was negatively correlated with nitrate uptake and NRA in shoots, but not with NRA in roots.     

Patterns of DNA and chromosome variation during in vitro growth in various genotypes of potato

Patterns of variation in nuclear DNA content and chromosome number were analysed in a temporal sequence, during in vitro growth of calli and cell suspensions in two monohaploids, a dihaploid and a tetraploid of potato (Solanum tuberosum). The results showed that both polyploidization and aneuploidy occurred during the initial stages of callus induction in all the genotypes. With further growth of callus, the frequency and extent of polyploidy and aneuploidy increased. In addition, the patterns of DNA and chromosome variation in cell suspension cultures revealed continued mitotic activity and transmission of cells with higher ploidy levels and aneuploidy. The results suggest that endoreduplication as well as endomitosis are important mechanisms of polyploidization, and that chromosome lagging and non-disjunction contribute to the production of aneuploidy.The various genotypes cultured under the same in vitro growth conditions differed in genetic instability, as assessed from the rate and degree of polyploidization and aneuploidy. Monohaploids showed more rapid rate of polyploidization than the dihaploid and tetraploid potatoes. It was concluded that the differences in genetic stability were due to different ploidy levels and genetic make-up of the genotypes.