基因系统生态及其应用

运用基因生态系统观点,探讨了基因的行为生态,提出了基因具有整体性、联系性、有序性和平衡性等特性．还讨论了基因生态的应用及其发展前景．     

基因概念的发展

１９０９年,约翰逊（Ｊｏｈａｎｎｓｅｎ）首次提出了基因（ｇｅｎｅ）的概念,用以替代孟德尔（Ｍｅｎｄｅｌ）早年所提出的遗传因子（ｇｅｎｅｔｉｃｆａｃｔｏｒ）一词,并创立了基因型（ｇｅｎｏ－ｔｙｐｅ）和表现型（ｐｈｅｎｏｔｙｐｅ）的概念,把遗传基础和表现...     

脊椎动物趋化因子受体CXCR基因分化研究

为了探讨脊椎动物CXCR(CXC chemokine receptor)在基因组上进化和分化的规律,采用生物信息学软件绘制了脊椎动物7个CXCR的基因结构图,分析了它们的系统进化关系,研究这些受体在不同物种基因同源性.结果表明,脊椎动物CXCR 7个成员在进化上发生了不同程度地分化.人、鼠、蜥蜴CXCR1和CXCR2在同一条染色体上,蛋白相似率很高,在进化树上混杂聚集在一起,形成CXCR1/2;而硬骨鱼类CXCR1和CXCR2发生了分化,形成了单独的CXCR1和CXCR2.鱼类CXCR3分化为3个基因,其中CXCR3b1、CXCR3b2与其他脊椎动物CXCR3同源性较高,聚集在一起,而CXCR3a分化较大.脊椎动物CXCR5和CXCR6基因较保守,基因同源性高.CXCR4和CXCR7在哺乳类、鸟类、爬行类和两栖类均仅一个基因,但在硬骨鱼类中它们各自分化为2个基因.CXCR4和CXCR7位于同一条染色体上.鱼类CXCR4a和CXCR7a与其他脊椎动物CXCR4和CXCR7基因同源性较高.而CXCR4b和CXCR7b这两个基因无论是从基因结构还是基因同源性上都发生了一定程度的分化.     

浅谈基因符号的使用

现代遗传学以孟德尔定律重被发现和证实为纪元。开头的10年间,不仅提出基因的名称,而且建立了基因型和表型等概念。从而有了特定基因和个体基因型的表征性符号。见基因符号标志着相应的个体性状孟德尔的研究是从豌豆的相对性状入手的,他用大写字母A、B等代表显性性状,如圆粒、黄子叶;相应的小写字母a、o代表相对的隐性性状皱粒和绿子叶,如此等等。从其用这些符号代表的杂交结果来看,正是在形式上代表着基因。此后,在遗传分析中,例如用棋盘式作配子随机交配分析,一直沿用大写字母代表显性基因,小写字母代表隐性基因。不过,由于…     

癫痫基因研究进展

本综述了癫痫基因的定位,癫痫候选基因的筛查和癫痫相关基因的寻找及其进展。     

抗旱相关基因在烟草中的应用研究进展

干旱是影响烟草正常生长、发育、产量和烟叶品质的一个重要逆境因子。在干旱胁迫下,植物体内会通过激发一些抗旱基因的表达来增强植物的抗旱能力。目前,很多抗旱相关的功能蛋白基因和调控蛋白基因已被克隆并在烟草中实现了遗传转化,外源抗旱基因的表达提高了转基因烟草的抗旱能力。抗旱基因的克隆为烟草抗旱新品种的培育奠定了良好的分子基础,系统深入地研究抗旱相关基因在干旱胁迫条件下的表达与调控,可为通过基因工程手段提高烟草的抗旱能力开辟新途径,同时也能为其他农作物的抗旱分子育种和品种改良提供基因资源。     

幽门螺杆菌尿素酶基因的研究进展

近年来,幽门螺杆菌的分子生物学研究取得了很大进展,而既是定植因子、又是毒力因子的幽门螺杆菌尿素酶也得到了更加深入的研究。本文就近年来幽门螺杆菌尿素酶基因的结构、转录、表达调控等方面一些新的研究进展作一综述。     

基因是什么? 分子遗传学教学中的体会和理解

随着分子遗传学的飞速发展,基因概念也在不断更新。笔者从事分子遗传学、分子生物学、遗传学教学以及基因与基因表达调控方面研究多年,对基因的本质和概念有较深的理解和认识。回顾了经典基因概念的形成和发展过程,并讨论了真核生物中的RNA遗传和朊病毒复制现象,提出了新的基因概念。认为基因是携带遗传信息的、可遗传的核酸片段或者多肽分子,它们可以编码具功能的RNA分子或多肽分子。     

Hox 基因与昆虫体躯决定

本综述了Hox基因的组成与功能,及Hox基因决定昆虫形态进化的作用机制。     

新基因从哪里来?(基因的发生、选择和进化)

《物种起源》问世时 ,曾有激烈争论。作者在第６版（１８７２）记载了“一位练达的自然学者仔细挑选了一些情况来证明自然选择不足以解释有用构造的初期阶段。现在我对他提出的这些情形已作了足够的讨论 ,或者已经讨论得过多了 ;并且我已指出 :如我所希望的 ,在这个问题上并没有什么大的难点。”读完全章（第７章） ,可以明白达尔文信心所在 :他是从极微细但已能从表象察觉的构造和功能起步 ,排出从简单到复杂、从低级到高级的梯阶 ,用自然选择贯串起来。以今天知识看 :这种极微细的表型必已有某个基因支持着。有基因在 ,自然选择是能够（一…     

静态荧光光谱法研究杜氏盐藻的生长规律

测量了杜氏盐藻不同生长期的静态荧光光谱,得出了杜氏盐藻生长规律曲线。通过与传统的分光光度计法和血球计数板法研究盐藻生长规律的比较发现,该方法反映的是活盐藻细胞浓度的变化情况,更能反映盐藻实际生长规律;不仅操作简便,灵敏度高,而且可以实现远距离非接触测量。     

Electron microscope study of the effect of temperature on the length of the tail of the myosin molecule

The effect of temperature on the length of the tail of the myosin molecule has been studied by negative staining of molecules immobilized on carbon substrates at different temperatures. In buffers containing chloride as the principal anion, tail length was approximately constant up to 25 degrees C. Above this temperature, it shortened linearly with increasing temperature up to 42 degrees C, the highest temperature studied in this solvent. The amount of shortening per degree C was about 1.2 nm. A similar amount of shortening per degree C was seen in acetate-containing buffers up to 50 degrees C, but in this case it did not begin until the temperature exceeded about 40 degrees C. A large fraction of the observed shortening was localized in a region that lies roughly between the two positions in the tail where proteolysis results in production of short or long subfragment-2. Frequently, the tail had a different appearance in this region from elsewhere and could sometimes be seen to split into two strands that were separate but coiled around one another.     

Immunolocalization of the protease kallikrein in the colon

Colon kallikrein was localized in the goblet cells of cat and man by a variety of immunocytochemical techniques. No evidence of this enzyme was found in other sites in this organ. The possible physiological significance of kallikrein in the gastrointestinal tract and of the many related serine proteases is discussed.     

Studies on the Tissue Distribution of the Puromycin-Sensitive Enkephalin-Degrading Aminopeptidases

An antiserum generated to the soluble form of the rat brain puromycin-sensitive enkephalin-degrading aminopeptidase was used to determine the tissue distribution of the soluble and membrane-associated forms of this enzyme. All tissues examined contained significant levels of the soluble enzyme form, with this enzyme accounting for greater than 90% of the arylamidase activity in brain, heart, and skeletal muscle. Native gel electrophoresis coupled with activity staining as well as inhibition studies were used to confirm the presence of this enzyme in various tissues. Serum was found not to contain this particular aminopeptidase. In contrast to the results obtained with the soluble enzyme form, brain was the only tissue found to contain the membrane-associated enzyme form. Although all tissues contained membrane-associated aminopeptidase activity only the brain enzyme could be maintained in solution in the absence of detergent. In addition, the brain membrane-associated enzyme could be distinguished from the membrane-associated aminopeptidase activity in other tissues on the basis of its sensitivity to inhibition by puromycin.     

An analysis of the behavioral effects of stimulation of the dopamine D2 receptors at the level of the ventral tegmental area in the rat brain]

It was shown that intracerebral injections of D2 dopamine receptor agonist quinpirol after systemic administration of D2 antagonist sulpiride inhibited both locomotor and food-procuring activity in rats. It was concluded that this effect is connected with involvement of the negative feedback mechanisms of dopaminergic neurons. The involvement of this mechanism into the regulation of the motivated behavior seems to require the definite level of dopaminergic structures.     

Juvenile hormone stimulated tyrosine kinase-mediated protein phosphorylation in the CNS of the silk worm,Bombyx mori

In vitro studies with the larval CNS of the silkworm, Bombyx mori revealed the phosphorylation of a 48-kDa protein, which was not dependent on cyclic nucleotides. Studies also revealed modest phosphorylation of this protein by a calcium-dependent but calmodulin-independent mechanism. However, phosphorylation of this protein was greatly enhanced in the presence of juvenile hormone (JH) I by a calcium-independent mechanism. This stimulatory effect of JH was seen in both homogenates as well as in intact CNS of Bombyx. Immunoblotting studies revealed the cross-reaction of this 48-kDa protein with phosphotyrosine monoclonal antibody and the phosphorylation of this protein was inhibited by genistein. This study suggests that the 48-kDa protein is a substrate for tyrosine kinase. The phosphorylation of this protein was also observed in other larval tissues such as salivary gland, fat body, and epidermis of Bombyx.     

Role of GABA within the nucleus tractus solitarii in the hypoxic ventilatory decline of awake rats

The purpose of this study was to examine our hypothesis that gamma-aminobutyric acid (GABA) in the nucleus tractus solitarii (NTS) may be related to the hypoxic ventilatory decline (HVD) and that chemoreceptor stimulation was essential to activate this mechanism. We used unanesthetized, freely moving rats in this study. An in vivo microdialysis technique was used to measure the extracellular GABA concentration ([GABA]o), and an in vivo microinjection technique was used to examine the effects of the GABA agonists and antagonists on the ventilation during hypoxia. The GABA agonists injected into the NTS attenuated the ventilation during hypoxia. By hypoxic exposure, [GABA]o was increased during the HVD. However, by carotid body denervation (CBD), this GABA increase was abolished. Although GABA antagonists microinjected into the NTS during the HVD phase significantly increased the depressed ventilation, this effect on the ventilation was abolished by CBD. These results suggest that the GABA in the NTS has a pivotal role in the HVD and that this mechanism is not activated without chemoreceptor stimulation.     

Nucleotide sequence of the gene encoding the repressor for the histidine utilization genes of Klebsiella aerogenes.

The hutC gene of Klebsiella aerogenes encodes a repressor that regulates expression of the histidine utilization (hut) operons. The DNA sequence of a region known to contain hutC was determined and shown to contain two long rightward-reading open reading frames (ORFs). One of these ORFs was identified as the 3' portion of the hutG gene. The other ORF was the hutC gene. The repressor predicted from the hutC sequence contained a helix-turn-helix motif strongly similar to that seen in other DNA-binding proteins, such as lac repressor and the catabolite gene activator protein. This motif was located in the N-terminal portion of the protein, and this portion of the protein seemed to be sufficient to allow repression of the hutUH operon but insufficient to allow interaction with the inducer. The presence of a promoterlike sequence and a ribosome-binding site immediately upstream of the hutC gene explained the earlier observation that hutC can be transcribed independently of the other hut operon genes. The predicted amino acid sequence of hut repressor strongly resembled that of the corresponding protein from Pseudomonas putida (S. L. Allison and A. T. Phillips, J. Bacteriol. 172:5470-5476, 1990). An unexpected, leftward-reading ORF extending from about the middle of hutC into the preceding (hutG) gene was also detected. The deduced amino acid sequence of this leftward ORF was quite distinct from that of an unexpected ORF of similar size found immediately downstream of the P. putida hutC gene. The nonstandard codon usage of this leftward ORF and the expression of repressor activity from plasmids with deletions in this region made it unlikely that this ORF was necessary for repressor activity.     

Expression of Transferrin Binding Protein in the Capillaries of the Brain in the Developing Chick Embryo

Transferrin-binding protein (TfBP) has been shown to be a novel protein, structurally related to the chicken heat shock protein 108. The physiological function of this protein, however, has not yet been established. Antiserum to TfBP selectively stains transferrin- and iron-rich oligodendrocytes and choroidal epithelium in the adult and embryonic chick brain, suggesting a role for this protein in transferrin and iron storage in these cells. In this study, we further demonstrate TfBP-immunoreactivity (IR) in the blood vessels of the embryonic chick central nervous system. A strong TfBP-IR was present in blood vessels from E6, declined from E10 and was absent by E18. Thus, the expression of the TfBP in the blood vessels precedes its expression in the oligodendrocytes. At the subcellular level, TfBP-IR was confined to the cytoplasm of capillary pericytes while the Tf-receptor IR was associated with the capillary endothelium of the brain. The up-regulated expression of TfBP, together with the Tf-receptor of the brain capillaries, suggests that pericytes may be associated with the high iron uptake required for the metabolic demands of the developing brain. D. W. Kim and H. N. Lee contributed equally to this work.     

Horticulture: the font for the baptism of genetics

This year marks the centenary of the rediscovery of the laws of heredity, and their introduction to the English-speaking world. Here I introduce the main events and the characters who figure in this story before turning to the task of this essay--to ask why it was that support in England for the emerging science of genetics, or Mendelism as it was then called, came chiefly from horticulture, and was only belatedly accepted into the mainstream of British academic biology.