SPORELING COALESCENCE AND INTRACLONAL VARIATION IN GRACILARIA CHILENSIS (GRACILARIALES,RHODOPHYTA)1

This study evaluates the hypothesis that spore coalescence may cause intraclonal variation. Spore coalescence might allow the occurrence of unitary thalli that in fact correspond to genetically different, coalesced individuals. Plant portions simultaneously derived from these chimeric individuals may exhibit dissimilar growth responses even when incubated under similar abiotic conditions. Testing of the hypothesis included various approaches. Transmission electron microscopy observations of early stages of sporeling coalescence indicated that polysporic plantlets were formed by groups of spores and their derivatives. Even though adjacent cells in two different groups may fuse, these groups maintained an independent capacity to grow and form uprights. Laboratory-grown plantlets showed a significant correlation between the initial number of spores and the total number of erect axes differentiated from the sporeling. Construction and growth of bicolor individuals indicated the chimeric nature of the coalesced individuals. Coalesced, bicolor holdfasts had green and red cells, which subsequently produced green and red uprights, respectively. Individuals fronds were also chimeric, as indicated by the production of green and red branchlets from single, red uprights. The existence of mixed tissues was further substantiated by random amplified polymorphic DNA analysis. The banding pattern produced by branchlets of a unisporic thallus was consistently monomorphic, whereas the patterns produced by the polysporic thallus were polymorphic. Growth rates of polysporic thalli had larger data dispersal and variation coefficients than oligosporic or monosporic thalli. Therefore, all results support the original hypothesis and suggest that coalescence might be ecologically more important than previously thought.     

紫背菜的食用价值及其开发利用前景

紫背菜的生物学与生态学特性、病虫害防治、营养成分、药用价值及其综合开发利用方面的研究表明:紫背菜及其色素提取物等营养成分在治疗糖尿病等人类疾病及食品加工等领域的综合开发利用前景广阔。     

Repeatability of extra-pair mating in tree swallows

Models of sexual selection assume that female mating preferences are heritable and, thus, repeatable for individual females across multiple mating episodes. Previous studies of the repeatability of female preference have examined individuals in captivity and focused presumably on social mate choice. However, extra-pair mating is widespread and can also influence sexual selection. We examined the repeatability of extra-pair mating in a wild population of tree swallows (Tachycineta bicolor) by experimentally inducing females to lay two clutches in rapid succession within the same season. We found that the proportion of extra-pair young and the number of extra-pair sires were highly repeatable for individual females. However, the repeatability of specific extra-pair sires was low. We suggest that this unusual pattern of mating may be due to females maximizing the heterozygosity of their offspring.     

Genetic transformation of Sorghum bicolor

Great millet (Sorghum bicolor (L.) Moench) is cultivated across the world for food and fodder. It is typically grown in semiarid regions that are not suitable for cultivation of other major cereals. Sexual incompatibility and shortage of available genes in germplasm to combat biotic and abiotic stresses resulted in marginalized yields of this crop. Genetic modification of sorghum with agronomically useful genes can address this problem. Here, we tried to review and summarize the key aspects of sorghum transformation work being carried out so far by various research groups across the world. The approaches used and the obstacles in generating transgenic sorghum are also pointed out and discussed.     

不同来源牛枝子种子硬实破除方法的研究

采用浓硫酸、热水和液氮3种人工破除硬实技术,在室内模拟牛枝子适生地水热条件,对2007、2008年采自内蒙古阿拉善左旗和2008年甘肃榆中栽培的牛枝子种子进行处理,以探讨同一种群不同年份和非种源地栽培一年后的牛枝子种子的硬实程度及其破除的最佳方式.结果发现:(1)采自阿拉善左旗(2007、2008年)和甘肃榆中的牛枝子初始硬实率存在显著差异,分别为98%、93%和86%.(2)阿拉善左旗和甘肃榆中的牛枝子种子对硫酸、热水和液氮处理的响应不同,浓硫酸处理的效果显著优于其它2种方法,普遍适宜于所有种批的最佳浓硫酸处理时间为25～30 min.(3)模拟温度和湿度处理表明,高温(60℃,60/20℃)和5%湿度的环境是牛枝子种子硬实破除的关键环境因素.     

黄土丘陵区不同立地达乌里胡枝子群落水分特征及生物量研究

对黄土高原丘陵沟壑区不同立地条件下的达乌里胡枝子群落水分特征及生物量进行了研究.结果表明:(1)不同立地下的达乌里胡枝子蒸腾日变化均呈单峰型,上午呈上升趋势,于13:00达到峰值,之后均呈不同程度下降趋势.(2)不同立地达乌里胡枝子群落0～200 cm土层平均含水量为阴坡12.34%,半阳坡11.29%,半阴坡11.15%,阳坡8.96%.不同立地达乌里胡枝子叶片相对含水量和饱和亏与各立地土壤含水量关系密切.(3)不同立地下各个时期的达乌里胡枝子群落的地上生物量表现为阴坡＞半阴坡＞半阳坡＞阳坡,地下生物量则表现为阳坡(447.39 g/m2)＞半阳坡(409.12 g/m2)＞半阴坡(344.92 g/m2)＞阴坡(217.01 g/m2).可见,达乌里胡枝子群落的水分生理特性及生物量的积累与立地条件密切相关.     

蓝光调节高粱突变体har1幼苗的去黄化反应

以航空诱变高粱突变体har1为材料,对其幼苗去黄化过程进行研究。萌发的种子在远红光下预培养6小时后,置于12小时蓝光/2小时黑暗条件下培养。测量幼苗的各器官伸长,结果表明,与野生型R111相比,harl的胚芽鞘、中胚轴、第一叶鞘以及第二叶鞘的伸长均受到蓝光的明显抑制,而蓝光对叶片生长影响不明显。3天龄har1黄化苗在连续蓝光下中胚轴花色素苷的积累明显增高,红光和远红光无此效应。此外,蓝光促进har1叶片叶绿体发育,且在蓝光照射24小时后叶片中叶绿素含量升高。Westernblot检测结果显示,7天龄R111和har1幼苗隐花色素SbCRY1b蛋白水平呈现蓝光下低、黑暗中高的变化趋势,har1的SbCRY1b蛋白水平在黑暗中高于R111。研究结果表明,高粱har1在去黄化过程中具有蓝光超敏感表型,SbCRY1b的作用值得进一步深入研究。