TYR 基因外显子1 的序列变异与家猪的起源研究

为了分析家猪与野猪的遗传多样性及起源, 测定了来自12 个中国地方家猪品种、3 个欧洲引进猪品种以 及8 个中国野猪和2 个越南野猪共36 个个体的酪氨酸酶基因( T YR) 外显子1 的序列,共检出6 个单核苷酸多态性 位点(SNPs) ,且这6 个位点的变异均为同义突变,根据这些变异可将酪氨酸酶基因DNA 序列归结为4 种单倍型。 结合已发表的数据,构建了简约中介网络图。在网络图中,单倍型T YR 3 2 主要为欧洲家猪与欧洲野猪和3 条亚洲 家猪染色体。大部分亚洲家猪和野猪共享单倍型T YR 3 1 ,表明这是1 个亚洲类型的单倍型;同时也有部分欧洲家 猪与野猪携带这一单倍型。而单倍型T YR 3 3 和T YR 3 4 为本研究检测到的稀有单倍型,这两种单倍型主要由中 国家猪与亚洲野猪组成。这种网络图结构支持家猪的欧洲和亚洲独立起源学说,同时也表明,相当部分的欧洲家 猪品种受到亚洲猪的基因渗透,而少量中国家猪和日本野猪也受到了欧洲猪的基因渗透。

宁夏新建二代防护林网蛀干害虫发生特点和危害特性

本文以宁夏银川二代林网中林分和害虫调查资料为基础 ,研究了二代林网主要蛀干害虫——光肩星天牛 (Anoplophora glabripennis Mostch)和木蠹蛾 [Cossus cossus ori-entalis Gaede &H olcocerus vicarius(Walker) ]分别在新疆杨林和刺槐林中因不同的树龄、径粗、林向、郁闭度、林地类型 (林缘和林内 )而呈现出的相应发生特点和为害特性。结果显示 ,新疆杨大于 6年生、胸径超过 1 2 cm径阶受光肩星天牛危害频率高 ;实验用片林林缘到林内 2 m范围内新疆杨受光肩星天牛危害显著高于林内 ,而东、西、南、北 4个方向 ,以东边受害最轻 ;与其它树种组成的混交林林缘同样重于林内。刺槐易受木蠹蛾危害的树龄和径节分别是 6 a～ 1 2 a和 1 2 cm～ 2 0 cm;刺槐片林无论是纯林还是混交林均为林缘重于林内。以上蛀干害虫对树龄和径粗均有较强的一致性选择

On the relationships between the radial tidal current field and the radial sand ridges in the southern Yellow Sea: a numerical simulation

The ori-in of the radial sand ridges (RSRs) in the southern Yellow Sea has been a controversial problem since they were discovered in the early 1960s. To resolve the problem, two key questions need to be answered: (1) was the radial tidal current field in the RSR area generated by the submarine topography, or (2) did it exist before the RSRs occurred? In this study, the M-2 tide and tidal currents in the RSR area were simulated with a two-dimensional tidal model using a flat bottom and a shelving slope topography, the results being then compared with the field data. It is demonstrated that the radial tidal current field in the southern Yellow Sea is independent of bottom topography, and may thus be the controlling factor generating the RSRs. The radial tidal current field probably existed before the RSRs were formed.