云南普通马矮型马蛋白多态性及其品种分化关系

本文运用蛋白电泳技术对来自云南省文山州马关县和麻栗坡县的２１匹普通马和１４匹矮型马进行了分析。共分析遗传座位４４个,其中有１０个座位检测到多态性。根据分子钟假说和相应的公式,推算两者的分歧时间约为１８．５万年。     

Identification and analysis of a retinoblastoma binding motif in the replication protein of a plant DNA virus: requirement for efficient viral DNA replication.

Geminiviruses are plant DNA viruses with small genomes whose replication, except for the viral replication protein (Rep), depends on host proteins and, in this respect, are analogous to animal DNA tumor viruses, e.g. SV40. The mechanism by which these animal viruses create a cellular environment permissive for viral DNA replication involves the binding of a virally encoded oncoprotein, through its LXCXE motif, to the retinoblastoma protein (Rb). We have identified such a LXCXE motif in the Rep protein of wheat dwarf geminivirus (WDV) and we show its functional importance during viral DNA replication. Using a yeast two-hybrid system we have demonstrated that WDV Rep forms stable complexes with p130Rbr2, a member of the Rb family of proteins, and single amino acid changes within the LXCXE motif abolish the ability of WDV Rep to bind to p130Rbr2. The LXCXE motif is conserved in other members of the same geminivirus subgroup. The presence of an intact Rb binding motif is required for efficient WDV DNA replication in cultured wheat cells, strongly suggesting that one of the functions of WDV Rep may be the linking between viral and cellular DNA replication cycles. Our results point to the existence of a Rb-like protein(s) in plant cells playing regulatory roles during the cell cycle.     

Inhibition of Taq DNA polymerase by seaweed extracts from British Columbia, Canada and Korea

Fifty-nine species of marine macrophytes from the coasts of British Columbia, Canada and Korea have been screened for the presence of PCR inhibitors, namely inhibitors of Taq DNA polymerase. Eleven of the species displayed some inhibitor activity. At the concentration of 5 μg of methanol extract in 25μL reaction mixture of PCR containing 1.5 unit of Taq DNA polymerase, one (Ulva sp.) of 8 Chlorophyta, eight (Colpomenia bullosa, Ecklonia cava, Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, and Sargassum thunbergii) of 28 Phaeophyta, and one (Symphyocladia latiuscula) of 34 Rhodophyta showed inhibition in PCR amplification. In the case of the water extract, two (Cladophora columbiana, Ulva sp.) Chlorophyta, seven (Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, Sargassum horneri, Scytosiphon dotyi) Phaeophyta, no Rhodophyta and one (Phyllospadix scouleri) seagrass showed inhibition in PCR amplification. the methanol fraction of Sargassum confusum and the water fraction of Fucus gardneri (mid–intertidal) have been found to inhibit PCR at level as low as 0.5 μg in 25μL of PCR reaction mixture. This revised version was published online in August 2006 with corrections to the Cover Date.     

Allergenic and antigenic proteins released in the apertural sporoderm during the activation process in grass pollen grains

A combination of transmission electron microscopy with immunocytochemical methods was used to localize antigenic and allergenic proteins during the maturation and activation processes of Poaceae pollen grains. The intine undergoes a series of modifications that play a decisive role in these processes. Allergenic and antigenic proteins were detected particularly in the intine of activated in vitro grass pollen grains. Labelling of antigenic proteins was more abundant and less specific than that of allergenic proteins. At the time of hydration, the operculum was lifted up, the intine was swollen and labelling of allergenic proteins appeared highly localized in the Zwischenkörper. No significant labelling was observed when the Zwischenkörper gelatinized. Immunolocalization of allergenic proteins in the activated Zwischenkörper indicated the presence of proteins related to activation of the pollen grains. This confirms that the intine function is involved in the processes of pollen tube formation and fertilization, and also suggests the possible mechanism activated in the pollen grains when allergenic proteins reach the mucosa of sensitive subjects.     

Efficient enzymatic synthesis of 13 C,15N-labeled DNA for NMR studies

The power of heteronuclear NMR spectroscopy to study macromoleculesand their complexes has been amply demonstrated over the last decade. Theobstacle to routinely applying these techniques to the study of DNA has beenthe synthesis of ¹³C,¹⁵N-labeled DNA. Here wepresent a simple and efficient method to generate isotope-labeled DNA forNMR studies that is as easy as that for isotope labeling of RNA. The methodwas used to synthesize a uniformly¹³ C,¹⁵N-labeled 32-nucleotide DNA that binds tohuman basic fibroblast growth factor with high affinity and specificity.Isotope-edited experiments were applied to the¹³ C,¹⁵N-labeled DNA bound to unlabeled protein,and the ¹³ C,¹⁵N-labeled DNA was also examined incomplex with ¹⁵N-labeled protein. The NMR experiments showthat the DNA adopts a well-defined stable structure when bound to theprotein, and illustrate the potential of¹³ C,¹⁵N-labeled DNA for structural studies ofDNA–protein complexes.     

四川自贡大山铺成渝龟科—新属

描述了产自四川自贡大山铺恐龙化石坑中的三件龟甲标本,命名为一新属新种—周氏四川龟（Sichuanchelyschowigen．etsp．nov．）。该属以椎盾极横宽,中部缘盾极狭长为主要特征,它代表了成渝龟科中一类较特别的类型。     

赤霉素与脱落酸对番茄种子萌发中细胞周期的调控

利用细胞流检仪检测番茄（Ｌｙｃｏｐｅｒｓｉｃｏｎ ｅｓｃｕｌｅｎｔｕｍ Ｍｉｌｌ．） ＧＡ－缺陷型、ＡＢＡ－缺陷型和相应的正常品种（野生型）成熟种子胚根尖细胞倍性水平时发现：ＧＡ－缺陷型和野生型种子绝大多数细胞ＤＮＡ 水平为２Ｃ,而ＡＢＡ－缺陷型种子则含有较多的４Ｃ细胞。在标准发芽条件下,ＡＢＡ－缺陷型和野生型种子浸种１ ｄ 后胚根尖细胞ＤＮＡ 开始复制,随后胚根突破种皮而发芽。然而ＧＡ－缺陷型种子除非加入外源ＧＡ,否则既不发生细胞ＤＮＡ 复制,也不发芽。这说明内源ＧＡ 是启动番茄种子胚根尖细胞ＤＮＡ 复制的关键因素,同时也说明番茄根尖细胞ＤＮＡ 复制是种子发芽的必要条件。实验证明：ＡＢＡ 不抑制细胞ＤＮＡ 合成,但阻止Ｇ２ 细胞进入到Ｍ 期。外源ＡＢＡ处理野生型种子与渗控处理结果相似,可以大幅度提高胚根尖４Ｃ／２Ｃ细胞的比例,但抑制种子的最终发芽