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讨论了菌物、真菌和地衣的概念,它们的生物多样性,地衣型真菌的系统生物学及其三大存取系统.同时,对地衣资源研究进行了展望. 相似文献
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讨论了菌物、真菌和地衣的概念,它们的生物多样性,地衣型真菌的系统生物学及其三大存取系统。同时,对地衣资源研究进行了展望。 相似文献
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地衣是一种传统的民族药物,能产生多种具有活性的物质。该研究对地衣型真菌(Xanthoria elegans,Myelochroa indica,Ramalina peruviana,Cladonia macilenta,Nephromopsis pallescens,Cladonia coccifera)进行液体培养,2个月后,培养液用乙酸乙酯萃取后获得初提物。该研究采用抑菌圈法评价地衣型真菌初提物对7种致病细菌(Bacillus subtilis,Bacillus cereus,Vibrio parahaemolyticus,Straphylococcus haemolyticus,Pseudomonas aeruginosa,Staphylococcus aureus,Micrococcus luteus)的抗菌活性,并测定最低抑菌浓度(MIC)。结果表明:6种地衣型真菌的初提物均具有一定的抗菌活性,且不同培养基对地衣型真菌产生抗菌物质有显著影响。其中,R.peruviana在MY液体培养基中所产生的次级代谢产物对金黄色葡萄球菌、藤黄微球菌、溶血性葡萄球菌、铜尿假单胞菌具有抑制效果,但在YMG培养基中所得初提物对供试7种致病细菌不具有抑菌效果。X.elegans在YMG培养基中所得初提物对枯草芽孢杆菌具有明显抗菌活性,其抑菌圈直径可达17.77 mm。该研究证实不同地衣型真菌液体培养初提物具有抗菌活性,不同的培养基也直接影响地衣型真菌抗菌效果。该研究结果为地衣型真菌的进一步研究及民族药的开发利用奠定了基础。 相似文献
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从沙漠地区地衣石果衣中分离得到的地衣型真菌(Endocarpon pusillum)具有极强的抗旱能力.为了研究石果衣真菌的抗旱机制,本研究利用转录组测序和荧光定量的方法分别对纯培养和共生状态的真菌进行分析和比较.比较转录组分析是针对纯培养的石果衣真菌,比较其在正常培养和胁迫培养条件下的2个样品,得到1781个差异表达基因.以抗旱植物和非地衣型真菌的抗旱机制作为参照,一些普遍存在机制中所涉及的基因在石果衣真菌中也是差异表达的.然而不同的是,石果衣真菌的抗旱机制中不涉及有关渗透压调节基因的差异表达,这一特点为揭示石果衣真菌为干旱适应物种提供了证据.此外,石果衣真菌不同于其他生物,还有一系列差异基因被归类于其特有的干旱适应机制.为了确定共生与纯培养状态下的石果衣真菌的抗旱机制是否一致,本研究挑选了23个候选基因,利用荧光定量的方法在脱水地衣体中进行验证.本研究为下一步地衣型真菌的研究提供有价值的数据支持,同时也会有助于抗旱基因的功能研究. 相似文献
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《植物分类与资源学报》2015,(6)
大团囊虫草是一类寄生型真菌,绝大多数以大团囊菌为宿主,只有3个种寄生在甲虫和蝉的幼虫体内。我们从采集自中国五个省份和南极长城站的42份地衣标本中分离得到了64株大团囊虫草属真菌菌株,系统发育学分析表明,这些真菌可能不是相同的种类,显示有多个种类的大团囊虫草属真菌广泛定植于地衣体中。与高等植物共生的内生真菌通常对宿主的生长起到促进作用,然而,由于地衣内生真菌生长所需营养物质来源于地衣共生真菌或光合共生物,因此地衣内生真菌与共生真菌之间很有可能是寄生关系或竞争关系。本研究发现大团囊虫草广泛伴生在地衣体内,部分证实了这一假说的正确性。 相似文献
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《热带亚热带植物学报》2018,(4)
绒衣属(Coenogonium)地衣属于真菌界(Fungi)子囊菌门(Ascomycota)茶渍纲(Lecanoromycetes)厚顶盘亚纲(Ostropomycetidae)厚顶盘目(Ostropales)绒衣科(Coenogoniaceae),主要分布于热带和亚热带地区。综述了绒衣属地衣研究简史和中国研究概况;报道了中国该属10种地衣,其中1种为中国新记录种:疏羽绒衣(Coenogonium disjunctum)。对各种进行了描述和讨论,并给出了中国绒衣属的检索表和新记录种的图片。这是首次对中国绒衣属地衣的系统研究,为地衣型真菌分类学研究提供了基础资料。 相似文献
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绒衣属(Coenogonium)地衣属于真菌界(Fungi)子囊菌门(Ascomycota)茶渍纲(Lecanoromycetes)厚顶盘亚纲(Ostropomycetidae)厚顶盘目(Ostropales)绒衣科(Coenogoniaceae),主要分布于热带和亚热带地区。综述了绒衣属地衣研究简史和中国研究概况;报道了中国该属10种地衣,其中1种为中国新记录种:疏羽绒衣(Coenogonium disjunctum)。对各种进行了描述和讨论,并给出了中国绒衣属的检索表和新记录种的图片。这是首次对中国绒衣属地衣的系统研究,为地衣型真菌分类学研究提供了基础资料。 相似文献
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Previous studies on calcitonin gene related peptide (CGRP) have demonstrated that it has the characteristics of an amphiphilic peptide, and from an examination of the sequence, we have proposed that it contains an amphiphilic alpha-helix. We have synthesized two analogues of CGRP which have different lengths of idealized amphiphilic alpha-helical secondary structure. The first model, CGRM-1, has been substituted with residues generating an idealized amphiphilic alpha-helix in the region between residues 8 and 25, equivalent to approximately five turns of an alpha-helix. This peptide is not an agonist in any of our bioassays, but it does bind with low affinity to rCGRP receptors in crude liver membranes. Our second model, CGRM-2, has an idealized amphiphilic alpha-helix between residues 8 and 18, which is equivalent to approximately three turns of an alpha-helix. In an in vitro rat vas deferens assay, this peptide is an agonist with a potency one-fourth that of the native hormone. However, the potency of CGRM-2 in an adenylate cyclase assay is much lower, only 1/140th the potency of CGRP. Both model peptides display amphiphilic characteristics commensurate with their design. We conclude that there is an amphiphilic alpha-helix in rCGRP between residues 8 and 18 and that this helix terminates in the vicinity of residue 18. 相似文献
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Jennifer E. Seedorff Michael E. Rodgers Robert Schleif 《Protein science : a publication of the Protein Society》2009,18(4):775-781
Regulation of the DNA binding affinity of an oligomeric protein can be considered to consist of an intrinsic component, in which the affinity of an individual DNA‐binding domain is modulated in response to effector binding, and an extrinsic component, in which the relative position of the protein's two DNA‐binding domains are altered so that they can or cannot contact both half‐site operators simultaneously. We demonstrated directly that the TetR repressor utilizes an extrinsic mechanism and CAP, the catabolite activator protein, utilizes an intrinsic mechanism. 相似文献
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In healthy humans after overnight fasting, an oral administration of ornithine induced a new steady state: an accumulation of serum alanine and proline, a decrease in serum valine concentration, transient reductions in serum urea and urinary urea contents, and then an increased urea excretion. On the other hand, an oral administration of arginine resulted in an anabolic state: decreases in serum leucine and isoleucine concentrations, reductions in serum glucose and free fatty acid contents and a rapid increase in serum insulin level. It was assumed that the effect of ornithine administration may be exerted through an activation of hepatic System A transport and that of arginine is an insulin-mediated action. 相似文献
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Pleiotropic effects on germ cell number, hematologic status, and body size are described in 12- to 15-day WBB6F1 normal (+/-) and defective (an/an) mouse fetuses, with special emphasis on gametogenesis. Differences between genotypes were apparent by Day 12. At 12 days, normal testes contained many germ cells and frequent normal mitoses, and the number of germ cells increased rapidly from Day 12 to Day 15. By contrast, 12-day an/an testes contained fewer germ cells, frequently degenerating, and many abnormal mitoses. Their number of germ cells decreased rapidly, so that almost none persisted to Day 15. Normal ovaries contained many germ cells, with much normal mitosis on Day 12 and 13, followed by meioses, but the smaller an/an ovaries contained few germ cells, with little mitosis, some meiosis, and very much degeneration. The erythrocyte counts of both normal and anemic fetuses increased approximately fourfold between 12 and 15 days, but at comparable ages, total counts were always lower in an/an fetuses than in normal littermates. At all ages, Hertwig's anemic (an/an) fetuses were somewhat smaller than their normal littermates. Although both W/Wv and Sl/Sld mice also show macrocytic anemia and germ cell failure, the great difference in etiology of their germ cell defects indicates that an/an gene action must be qualitatively different from that in either W/Wv or Sl/Sld mice. 相似文献
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Bernhard Thomas 《Theoretical population biology》1984,26(1):49-67
Different aspects and modifications of the definition of an evolutionarily stable (ES) strategy that have been considered in the literature can be incorporated in a unifying concept which regards the population context. This concept of evolutionary stability will generally characterize population states in both pure- and mixed-strategist models. In particular, it includes ES strategies, represented as a phenotype unique in an ES population. For an important class of mixed-strategist models, no strict ESS can exist. This will be the case whenever the success of an individual strategy is considered to follow as an average from the successes of its behavioural components. Instead, ESS results may be obtained from what will be called a “degenerate” form of the model, which is simply an ESS model on the level of elementary actions. Then, however, the correct interpretation of an ESS is not an individual phenotype but rather a population mixture of elementary actions. If an ES state exists in a mixed-strategist model it may be determined by an equilibrium condition; if there is an ES strategy, a different approach—mainly maximum considerations—is needed for finding it. An equilibrium condition does not hold for the components of an ES strategy straightforwardly; but it can be derived in terms of an auxiliary ESS model that considers first-order effects of the components. Several examples illustrate the significance of these results. Particularly, two models on “Games between Relatives” are reconsidered in order to display both their formal interrelation and the different meaning of their results in the context of mixed-strategist models. 相似文献
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Animals observing conspecifics during mate choice can gain additional information about potential mates. However, the presence of an observer, if detected by the observed individuals, can influence the nature of the behavior of the observed individuals, called audience effect. In zebra finches (Taeniopygia guttata castanotis), domesticated males show an audience effect during mate choice. However, whether male and female descendants of the wild form show an audience effect during mate choice is unknown. Therefore, we conducted an experiment where male and female focal birds could choose between two distinctive phenotypes of the opposite sex, an artificially adorned stimulus bird with a red feather on the forehead and an unadorned stimulus bird, two times consecutively, once without an audience and once with an audience bird (same sex as test bird). Males showed an audience effect when an audience male was present and spent more time with adorned and less time with unadorned females compared to when there was no audience present. The change in time spent with the respective stimulus females was positively correlated with the time that the audience male spent in front of its cage close to the focal male. Females showed no change in mate choice when an audience female was present, but their motivation to associate with both stimulus males decreased. In a control for mate-choice consistency there was no audience in either test. Here, both focal females and focal males chose consistently without a change in choosing motivation. Our results showed that there is an audience effect on mate choice in zebra finches and that the response to a same-sex audience was sex-specific. 相似文献
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Mice homozygous for the gene, an, have a macrocytic, normochromic anemia. In this report, attempts have been made to cure Hertwig's anemia (an/an) by injecting genetically normal (+/+) stem cells. The anemia of unirradiated an/an mice was alleviated but not completely cured by injection of as many as 3 X 10(7) +/+ bone marrow cells. Lethal irradiation of the an/an recipients was necessary before injections of 10(7) +/+ marrow cells were effective in normalizing the blood parameters. The inability to achieve normal blood values without first destroying the host's own stem cells suggested that the indigenous an/an cells compete effectively with injected +/+ cells. This hypothesis was tested by injecting varying numbers of stem cells from C57BL/6J-+/+ mice, together with stem cells from either WBB6F1-an/an or, as controls, from their WBB6F1-+/+ littermates, into lethally irradiated hosts. The C57BL/6J and WBB6F1 mice have electrophoretically distinguishable hemoglobins. The an/an cells are able to compete in the repopulation of the host hematopoietic tissue as shown by the presence of WBB6F1 hemoglobin in the recipients. The cells from mice with Hertwig's anemia, however, do not compete as effectively as do the same number of cells from the +/+ littermates. These results indicate that the pluripotent hematopoietic stem cells of an/an mice are reduced in number, seeding capacity, or proliferative potential. 相似文献
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Limiting Factors Impacting on Voluntary First Person Informed Consent in the Philippines 总被引:1,自引:0,他引:1
Fatima Alvarez Castillo 《Developing world bioethics》2002,2(1):21-27
How well can institutional guidelines help ensure the dignity, rights, safety and well being of research participants in an underdeveloped country? In this paper I describe the limits of informed consent as an instrument for the protection of participants in the context of the Philippines. I bring to this paper my experiences as an advocate of rights, a member of an ethics review board, a researcher on the ethics of research and as an observer of the dynamics of clinical practice in an academic public teaching hospital of the University of the Philippines where I am professor. 相似文献