A geomorphic template for the analysis of lake districts applied to the Northern Highland Lake District, Wisconsin, U.S.A.

1. We tested the degree to which a lake's landscape position constrains the expression of limnological features and imposes a characteristic spatial pattern in a glacial lake district, the Northern Highland Lake District in north‐central Wisconsin. 2. We defined lake order as a metric to analyze the effect of landscape position on limnological features. Lake order, analogous to stream order, is based solely on geographical information and is simple to measure. 3. We examined the strength of the relationship between lake order and a set of 25 variables, which included measures of lake morphometry, water optical properties, major ions, nutrients, biology, and human settlement patterns. 4. Lake order explained a significant fraction of the variance of 21 of the 25 variables tested with ANOVA. The fraction of variance explained varied from 12% (maximum depth) to 56% (calcium concentration). The variables most strongly related to lake order were: measures of lake size and shape, concentrations of major ions (except sulfate) and silica, biological variables (chlorophyll concentration, crayfish abundance, and fish species richness), and human‐use variables (density of cottages and resorts). Lake depth, water optical properties, and nutrient concentrations (other than silica) were poorly associated with lake order. 5. Potential explanations for a relationship with lake order differed among variables. In some cases, we could hypothesize a direct link. For example, major ion concentration is a function of groundwater input, which is directly related to lake order. We see these as a direct influence of the geomorphic template left by the retreat of the glacier that led to the formation of this lake district. 6. In other cases, a set of indirect links was hypothesized. For example, the effect of lake order on lake size, water chemistry, and lake connectivity may ultimately explain the relation between lake order and fish species richness. We interpret these relationships as the result of constraints imposed by the geomorphic template on lake development over the last 12 000 years. 7. By identifying relationships between lake characteristics and a measure of landscape position, and by identifying geomorphologic constraints on lake features and lake evolution, our analysis explains an important aspect of the spatial organization of a lake district.     

黑曲霉单宁酶高活性菌株的诱变选育*

以黑曲霉（Ａｓｐｅｒｇｉｌｌｕｓ ｎｈｉｇｅｒ）Ｎｏ．１３为出发菌株,经紫外线诱变处理,获得一株制备原生质体的起始菌,该菌株单宁酶活性比Ｎｏ．１３提高５５％,并对其制备原生质体的条件进行了研究,在优化方案基础上,紫外诱变原生质体,诱变株经筛选,最后得到一株具有稳定遗传性的单宁酶高活性菌株,在摇瓶培养基中进行生物转化实验,连续传代１０次,结果显示发酵液中没食子酸浓度始 维持在２２．８－２３．９ｍｇ／     

芸苔属植物CAL基因的结构特征与花球的形态遗传

从花椰菜变种（Ｂｒａｓｓｉｃａ ｏｌｅｒａｃｅａ Ｌ．ｖａｒ．ｂｏｔｒｙｔｉｓ）中分离出４种花球类型的纯合株系：光滑型花球ｃｕｒｄ－ｓ、毛状物花球ｃｕｒｄ－ｈ、颗粒状花球ｃｕｒｄ－ｃ和刺状物花球ｃｕｒｄ－ｔ。用ＰＣＲ方法分别扩增各株系的ＢｏｂＣＡＬ基因并分析其中的部分序列,发现４种株系的ＣＡＬ基因在第五个外显子中都有ＡＡＧ向ＴＡＧ的终止突变,而且该终止密码子上游６３８ｂｐ的ＤＮＡ序列完全一致,说明     

Agrobacterium-mediated transformation of cotyledonary explants of Chinese cabbage (Brassica campestris L. ssp. pekinensis)

 A procedure for producing transgenic Chinese cabbage plants by inoculating cotyledonary explants with Agrobacterium tumefaciens strain EHA101 carrying a binary vector pIG121Hm, which contains kanamycin-resistance and hygromycin-resistance genes and the GUS reporter gene, is described. Infection was most effective (highest infection frequency) when explants were infected with Agrobacterium for 15 min and co-cultivated for 3 days in co-cultivation medium at pH 5.2 supplemented with 10 mg/l acetosyringone. Transgenic plants of all three cultivars used were obtained with frequencies of 1.6–2.7% when the explants were regenerated in shoot regeneration medium solidified with 1.6% agar. A histochemical GUS assay and PCR and Southern blot analyses confirmed that transformation had occurred. Genetic analysis of T1 progeny showed that the transgenes were inherited in a Mendelian fashion. Received: 15 December 1998 / Revision received: 2 July 1999 · Accepted: 8 July 1999     

藤本植物生活型系统的修订及中国亚热带东部藤本植物的生活型分析

根据中国亚热带东部藤本植物的特征,修订并扩充了Ｍｕｅｌｌｅｒ－Ｄｏｍｂｏｉｓ和Ｅｌｌｅｎｂｅｒｇ生活型系统中藤本植物分类部分。对本区生活型分析的结果表明,中国亚热带东部藤本植物的生活型谱是以高位芽藤本占绝对优势（７２．７％）其次为地下芽藤本（１７．５％）、地面芽藤本（６．２％）、１年生藤本（２．７％）和地上芽藤本（１．５％）,除地下芽藤本比例略高外,与亚热带常绿阔叶林生活型谱十分接近,具有比较明确     

利用固定化黑曲霉单宁酶制备没食子酸的研究

用海藻酸钙载体包埋单宁酶,制备出转化五倍子单宁成没食子酸能力较好的固定化酶。研究了固定化条件和固定化单宁酶的部分性质,结果表明：最佳固定化条件为海藻酸钠90mg包埋单宁酶546u(3mL,182u/Ml),在1%～2%CaCl₂中作硬化处理;固定化单宁酶的最适温度为45℃,在10～50℃范围内稳定;其最适Ph值为6.5,在Ph5～7之间基本稳定;在此基础上,进行了没食子酸实验室克量级酶法制备实验,3次实验没食子酸产品的平均产率达到61%。和目前所用工业生产没食子酸的硫酸水解法相当,具有潜在的工业开发价值。     

中国人群中微卫星位点DXYS156的多态研究

以中国２个汉族群体和８个少数民族群体的Ｓ２０名个体为研究,采用ＰＣＲ扩增后案丙烯酰胺凝胶电泳分离的方法,分析了Ｙ染色体上ＤＸＹＳ１５６Ｙ和Ｘ染色体上ＸＹＳ１５６Ｘ这两个微卫星位点的遗传多态性。结果表明,在所研究的１０个中国人群中,共观察到１０个不同长度片段的等位基因,在Ｘ染色体上的５个闰基因是：１３０ｂｐ、１３５ｂｐ、１４０ｂｐ、１４５ｂｐ、１５０ｂｐ,在Ｙ染色体上的五个等位基因晃：１６０ｂｐ、１     

出生性比研究

对 1971— 1993年云南昆明、玉溪、红河、思茅、西双版纳、大理、楚雄、丽江等 8地、州、市 66个医疗单位接生的新生儿资料进行调查 ,获取401454例新生儿性别等有关资料。发现 :( 1 )出生性比在上升 ,由 1971年的 104 .06上升到 1993年的 108.57;1974年最低 ,为 101 .11 ,1991年最高 ,为 111 .87。 23年中 ,平均每年上升 0 .47。 ( 2 )一年之中 ,新生儿出生人数的高峰期为 10、 11、 12等 3个月 ,峰顶为 11月 ,占 11 .01% ;出生性比的峰顶为 3、4、6、7、9等5个月 ,最高为 9月 ,达 109.47。 ( 3)城、乡出生性比差异显著。不论胎次 (一、二胎 )和月份 ( 8、 9两月除外 ) ,市、县城区 ,出生性比均显著高于农村。 ( 4) 1 979年以前的出生性比在101 .11— 105 .67之间 ,1980年以后的出生性比在 104 .17— 111 .87之间。 ( 5 )提出了维持性平衡的6点对策。     

植物生态学方法在中药材质量研究中的应用与展望

中药材是植物在长期进化过程中 ,通过对环境的不断适应而形成的较为稳定的品系。由于气候、土壤、地形等的不同 ,一些地区非常适应某些药材生长 ,形成了传统的道地药材 ,如河南的怀地黄 ,四川的川连、川贝 ,宁夏的枸杞 ,广西的三七 ,甘肃的当归 ,吉林的人参等。随着中医药的不断发展 ,人们对中药材的质量问题越来越重视 ,其药材质量的生物学本质问题成为药材学研究的热点之一。在这一研究中 ,植物生态学的理论和方法 ,在药材研究的不同历史时期几乎都有渗透 ,格外引起人们的关注。本文将对此进行三个研究阶段的综述。1　朴素的本草描述研究…     

猪伪狂犬病毒蛋白激酶基因的序列测定与分析

对伪狂犬病毒湖北株（ＰＲＶ ＨＢ株）蛋白激酶（ＰＫ）基因进行了克隆和序列测定。分析比较了该序列与ＰＲＶＮＩＡ－３株、Ｋａ株以及ＨＳＶ－１、ＶＺＶ ＰＫ基因的同源性。结果显示,在测定全长１３１２ｂｐ的ＤＮＡ序列中,包括着一个１００２核苷酸的开放读框,可编码３３４个氨基酸组成的多肽。ＰＲＶ－ＨＢ株ＰＫ与ＰＲＶ－ＮＩＡ３、ＰＲＶ－Ｋａ、ＨＳＶ－１、ＶＺＶ ＰＫ基因比较,核苷酸的同源性分别为９８．７％、９