木霉分子生物学研究进展

木霉Trichoderma spp.是普遍存在并具有重要经济意义的一类真菌。本文试从木霉大分子;基因克隆;转化系统;外源基因表达;在工农业生产中的应用等方面对木霉分子生物学研究进展进行综述。     

MOLECULAR SYSTEMATICS OF THE XANTHOPHYCEAE

The Corallinales includes ca. 40 genera of calcified red seaweeds. Species are of two distinct morphotypes; those that possess genicula (uncalcified nodes) and those that lack genicula. Most nongeniculate species take the form of crusts. The presence (or absence) of genicula, secondary pit connections, and tetrasporangial conceptacle features have traditionally been used as key characters for delimiting coralline subfamilies. In this study, nuclear encoded 18S and 26S r RNA gene sequences were determined and used to reexamine relationships among coralline taxa. Separate and combined phylogenetic analyses of these data yielded similar trees in which four major lineages are resolved. Heydrichia and Sporolithon (Sporolithaceae) are positioned at the base of the tree and appear to be distantly related to other species examined. Within the Corallinaceae, the nongeniculate Melobesioideae is resolved as a monophyletic group. All members of this subfamily produce mutiporate tetraspoangial conceptacles. The Corallinoideae, which are characterized by unizonate genicula, are resolved as sister to a clade containing species placed in the Lithophylloideae, Mastophoroideae and Metagoniolithoideae. The molecular data indicate that geniculate and nongeniculate species characterized by the presence of secondary pit connections are closely related. For example, both data sets robustly support a sister taxon relationship between Amphiroa and Titanoderma. Our results indicate that: 1) all taxa in which secondary pit connections are present should be referred to the Lithophylloideae and, 2) genicula are nonhomologous structures that are independently derived in Amphiroa, Lithothrix, Metagoniolithon and the last common ancestor of the Corallinoideae.     

瑞氏木霉分子生物学研究进展

瑞氏木霉（Ｔｒｉｃｈｏｄｅｒｍａ　ｒｅｅｓｅｉ）是自然界中普遍存在并有重要经济意义的一种丝状真菌。从瑞氏木霉的转化系统、基因克隆、基因表达调控、过量产生同源和异源重组蛋白等方面对瑞氏木霉分子生物学研究进展情况进行了综述。     

昆虫分子生物学的一些进展：杀虫剂抗性的分子基础

昆虫分子生物学的一些进展：杀虫剂抗性的分子基础翟启慧（中国科学院动物研究所北京１０００８０）昆虫对杀虫剂的中毒,在药物动力学上包括三种不同水平上的作用：穿透表皮组织,在体内组织中的分布、贮存和代谢,以及对最终靶部位的作用。因此,已经公认的抗性机理包括...     

菊花矮化类病毒cDNA的分子克隆

菊花是世界上重要花卉品种之一,由菊花矮化类病毒(Chrysanthemum stunt viroid,CSV)引起的矮化病,近些年来在一些国家中有不断扩展的趋势。由于类病毒感染的潜伏期较长,所以早期诊断十分重要。我们曾用互补DNA(cDNA)探针和聚丙烯酰胺凝胶电泳检测我国的菊花矮化类病毒。分子杂交技术检测类病毒比生物学方法快速,较电泳方     

胚珠发育的分子基础

胚珠作为胚囊的携带者,在植物的生殖过程中起重要作用。胚珠是种子的前身,它在受精后发育成种子。近年来通过诱变已创造出一些胚珠和胚囊发育异常的突变体,如ｓｉｎ１,ｂｅｌ,ｏｖｍ２,ｏｖｍ３。这几个突变体的表现型不但是珠被发育异常,而且胚囊不能形成或发育异常,最终结果是雌性不育。同时,已分别从蝶兰和矮牵牛的胚珠中分离出一批胚珠发育特异的基因,其中有关ＭＡＤＳＢｏｘ基因在胚珠形成和发育中的作用研究得比较清楚,基因转化工作证实胚珠的分化和形成受一类新的ＭＡＤＳＢｏｘ基因控制。     

速足目主要类群系统发育的分子证据

文章基于速足目现生主要类群18S rDNA、28S rDNA和COI基因序列,采用贝叶斯法、邻接法和最大简约法,尝试构建速足目的分子系统树;结合形态特征和化石记录,主要对速足目各超科级分类阶元的系统发育关系进行探讨。结果表明,速足目现生超科Bairdiacea、Darwinulacea、Cypridacea和Cytheracea均为单系群,支持形态学上关于上述4个超科的的界定;3种基因均支持形态学上Darwinulacea和Cypridacea具有较近的亲缘关系的观点。18S rDNA序列分析在较显著水平上支持Darwinulacea和Bairdiacea为姐妹群,Darwinulacea可能从Bairdia-cea中的一支演化而来;Bairdiacea和Darwinulacea组成的分支是Cypridacea的姐妹群,支持将三者合并为Bairdio-copina亚目的观点;Cytheracea是Cypridacea(Darwinulacea Bairdiacea)的姐妹群,可提升为Cytheracopina亚目。     

镰孢属几种植物病原真菌分子核型的研究

利用脉冲电场凝胶电泳（ｐｕｌｓｅｄ－ｆｉｅｌｄｇｅｌｅｌｅｃｔｒｏｐｈｏｒｅｓｉｓ,ＰＦＧＥ）,研究了４株串珠镰孢（Ｆｕｓａｒｉｕｍ　ｍｏｎｉｌｉｆｏｒｍｅ）、１株尖镰孢（F．ｏｘｙｓｐｏｒｕｍ）、１株茄镰孢（Ｆ．ｓｏｌａｎｉ）和１株Ｆｕｓａｒｉｕｍｓｐ．的分子核型以及不同地域和寄主来源的串珠镰孢种内菌株间的分子核型差异。以凝胶包埋法（不破除分生孢子细胞壁）制备供试菌株电泳样本,采用３组条件组合进行电泳,分离出供试串珠镰孢完整染色体ＤＮＡ１０～１３条,分子量分布范围０．７Ｍｂ～６．９Ｍｂ,基因组大小为４２．２６Ｍｂ～４７．７５Ｍｂ;尖镰孢８条,分子量分布范围１．２Ｍｂ～６．７Ｍｂ,基因组大小为３２．２５Ｍｂ;茄镰孢６条,分子量分布范围２．４Ｍｂ～６．３Ｍｂ,基因组大小为２５．２Ｍｂ;Ｆｕｓａｒｉｕｍｓｐ．９条,分子量分布范围０．８Ｍｂ～６．８Ｍｂ,基因组大小为３６．４５Ｍｂ。结果表明,供试４种镰孢菌染色体数目、ＤＮＡ分子量及基因组大小都有较大不同,分子核型差异较大。不同来源的串珠镰孢种内菌株间分子核型亦有明显差异。     

镰孢属几种植物病原真菌分子核型的研究*

利用脉冲电场凝胶电泳（ｐｕｌｓｅｄ－ｆｉｅｌｄｇｅｌｅｌｅｃｔｒｏｐｈｏｒｅｓｉｓ,ＰＦＧＥ）,研究了４株串珠镰孢（Ｆｕｓａｒｉｕｍ　ｍｏｎｉｌｉｆｏｒｍｅ）、１株尖镰孢（F．ｏｘｙｓｐｏｒｕｍ）、１株茄镰孢（Ｆ．ｓｏｌａｎｉ）和１株Ｆｕｓａｒｉｕｍｓｐ．的分子核型以及不同地域和寄主来源的串珠镰孢种内菌株间的分子核型差异。以凝胶包埋法（不破除分生孢子细胞壁）制备供试菌株电泳样本,采用３组条件组合进行电泳,分离出供试串珠镰孢完整染色体ＤＮＡ１０～１３条,分子量分布范围０．７Ｍｂ～６．９Ｍｂ,基因组大小为４２．２６Ｍｂ～４７．７５Ｍｂ;尖镰孢８条,分子量分布范围１．２Ｍｂ～６．７Ｍｂ,基因组大小为３２．２５Ｍｂ;茄镰孢６条,分子量分布范围２．４Ｍｂ～６．３Ｍｂ,基因组大小为２５．２Ｍｂ;Ｆｕｓａｒｉｕｍｓｐ．９条,分子量分布范围０．８Ｍｂ～６．８Ｍｂ,基因组大小为３６．４５Ｍｂ。结果表明,供试４种镰孢菌染色体数目、ＤＮＡ分子量及基因组大小都有较大不同,分子核型差异较大。不同来源的串珠镰孢种内菌株间分子核型亦有明显差异。     

THE MOLECULAR ORGANIZATION OF CHLOROPLAST MEMBRANES

The presence of subunits in chloroplast membranes is suggested by polarization, fluorescence, and X-ray studies. Subunits (quantasomes) may be observed in the electron microscope on dried shadowed membranes and in replicas of membranes produced by the freeze-etching technique. Regular subunits are also observed with the electron microscope in thin sections of chloroplast membranes. Chemical considerations suggest that many membranes are composed of lipoprotein subunits. Thin sections reveal two types of chloroplast membranes, the fret membranes composed of one layer of subunits, and the partitions composed of two layers of subunits. Chloroplast membranes consist of about 45% protein and 55% lipid. Some 80% of the lipids are the highly surfactant glycolipids. In this paper the subunits are visualized as assymetric lipoproteins, probably having a protein core surrounded by components determined by the nature and environment of the membrane. Since the stroma, fret channels, and loculi contain aqueous materials, it is further postulated that the membranes bordering these spaces bind the highly surfactant glycolipids. The region between the two rows of subunits in the partition appears to be highly hydrophobic, rich in chlorophyll, and low in glycolipids. Some chlorophyll also may occur within the subunits both in the partitions and in the fret membranes. Since four subunits appear to comprise a quantasome, at least two types of forces, inter- and intra-quantasome forces, bind the subunits together in sheets. Chloroplast membranes thus differ from a “unit membrane” in two important respects: (1) they must be an aggregate of globular subunits, and (2) the lipoprotein subunits consist of a protein matrix which binds the chlorophylls and lipids by hydrophobic association with their hydrocarbon moieties.     

MOLECULAR WEIGHT,MOLECULAR VOLUME,AND HYDRATION OF PROTEINS IN SOLUTION

1. The gram molecular weight of a substance may be calculated from the osmotic pressure of its solution. 2. The radius of the hydrated molecule and, hence, the gram molecular volume of the hydrated solute may be determined from diffusion measurements. The hydration of the molecules may, therefore, be calculated from osmotic pressure and diffusion measurements. 3. Hydration may also be determined by viscosity measurements. Hydration of crystalline hemoglobin, crystalline trypsin, and gelatin have been determined by these methods and found to be as follows: See PDF for Structure     

THE MOLECULAR EVOLUTION OF PITUITARY HORMONES

1. The pituitary hormones can be divided into 4 families; within each the members are structurally related and have probably evolved from a common ancestor by a process of gene duplication and divergence. 2. Recent structural studies have revealed much about the evolution of proteins. The roles of point mutation, gene duplication and partial gene duplication in molecular evolution have been highlighted, and the nature of the evolutionary forces involved has been extensively debated. The information available about the evolution of proteins in general provides a background for consideration of pituitary hormone evolution. 3. The structure and function of the mammalian neurohypophysial hormones (oxytocin and vasopressin) has been studied in detail. Related (structurally similar) peptides have been found in the neurohypophyses of lower vertebrates and have been Characterized in many instances. Several schemes have been proposed for the evolution of these hormones. 4. The vasopressins of the pig and its relatives show a genetic polymorphism. The roles of neurohypophysial hormones in lower vertebrates are very varied and not fully understood. 5. The ACTHs and MSHs are members of a second family of pituitary hormones. They are polypeptides of moderate size. Studies on amino-acid sequences have been carried out for ACTHs and MSHs from several mammals. α-MSH is identical in all cases studied in detail, but β-MSH and ACTH vary to some extent. There is considerable sequence homology between the hormones in this family - indicating a common phylogenetic origin and several gene duplications. 6. Dogfish MSH is the only non-mammalian hormone of the ACTH-MSH family to have been studied in detail. Two MSHs have been isolated from this species; both resemble the a-MSH of mammals in amino-acid sequence. ACTH-like and MSH-like hormones exist in many other vertebrate groups, but have not been characterized fully. 7. Structure-function relationships have been widely studied in the ACTH-MSH family, and have some interesting evolutionary implications. Polymorphism of P-MSHs is found in some mammals. 8. A third family of protein hormones includes pituitary prolactin and growth hormone, and placental lactogen. These are proteins of moderate size which have been shown to be widely distributed among the vertebrates. Species specificity can be recognized with regard to biological, immunological and structural properties. 9. Amino-acid sequences have been determined for growth hormones and prolactins from several mammals. There is sequence homology between growth hormone and prolactin. Human placental lactogen closely resembles human growth hormone. A phylogenetic tree has been constructed for this protein family. Rates of evolution within the group are rather variable. 10. The fourth family of pituitary hormones (FSH, LH, TSH and some related placental hormones) are all glycoproteins and have a subunit structure. Extensive sequence studies have been carried out on the hormones from some mammals, and show that there is considerable homology between the various subunits. The α-subunits of human TSH, LH and HCG (and probably FSH) are very similar. The β-subunits are different, but homologous. Evolution of this family clearly took place by a series of gene duplications followed by gene divergence. Schemes whereby this could have occurred have been discussed. Related hormones occur in lower vertebrates, but have not been fully characterized. Some lower vertebrates may possess only one gonado-trophin. 11. The pituitary hormones provide an interesting range of evolutionary problems, and are useful models for the study of molecular evolution. The evolutionary processes involved in their diversification have been discussed, with particular reference to the co-evolution of hormones and their receptors. Neutral mutations and gene duplications may have played a role in providing co-existing variation of hormones and receptors. 12. A speculative model for the evolution of neurohypophysial hormones is proposed, as an example of how molecular evolution may have operated in this and other hormone groups. 13. Homologies have been proposed between the various families of pituitary hormones, and between pituitary proteins and other entero-secretory proteins. The pituitary protein hormones were probably elaborated from smaller molecules by a process of partial gene duplication.     

分子伴娘60类群的系统发育学分析

有充分的证据支持线粒体和叶绿体起源的内共生假说,即:紫色细菌、α—类群的成员是线粒体的祖先,而蓝细菌的成员是叶绿体的祖先。这一证据来自分子伴娘60蛋白为基础的系统发育学分析,并且与16S rRNA序列为基础的分析结果是完全一致的。这一结果还说明,嗜碱芽胞杆菌C-125菌株在系统发育地位上更接近枯草芽孢杆菌。     

纳他霉素的分子生物学研究进展*

纳他霉素是一种多烯大环内酯类抗真菌抗生素,广泛用于食品防腐。通过综述纳他霉素分子生物学的研究进展,揭示了纳他霉素的生物合成基因簇,包括纳他霉素26元环的形成基因(pimSO-pimS4)和修饰基因共16个可读框架,并对其编码的蛋白质PKS、PimD、PimJ、PimK的功能作了较为详细的论述。     

人工栽培蛹虫草退化现象的分子分析*

利用PCR-RFLP和RAPD方法对野生驯化蛹虫草及其退化菌种进行了基因水平的分析。PCR-RFLP实验,采用真菌通用引物ITS1和ITS4,扩增出5.8S和其两端的两个转录间隔区(ITS),选用5种识别四个碱基的内切酶(HaeIII、AfaI、TagI、AluI和XspI),其中只XspI酶切结果在两个菌种中存在差异,进一步测序表明,整个片段全长534bp,共有13个位点发生碱基突变,且都为c转换为t。RAPD实验,选用4组计80个随机引物进行PCR扩增,共筛选出9个对所有供试个体均存在明显差异的引物。结果表明了退化菌株较野生驯化菌株在DNA水平上发生了频率较高的突变,这些突变可能直接与导致菌种退化的基因相关联。