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1.
F. Gabrielli 《Life sciences》1983,33(9):805-816
Macromolecules and supramolecular structural components that are incorrectly synthesized or are damaged by radiation or by reactive chemicals are either repaired or selectively degraded and resynthesized. In addition, turnover rates for macromolecules and supramolecular structures can be elevated by alternation of fasting and feeding periods and can be influenced by metabolic regulatory mechanisms which are governed by steady-state concentrations of labile macromolecules.  相似文献   

2.
Biology and systematics of heterokont and haptophyte algae   总被引:1,自引:0,他引:1  
In this paper, I review what is currently known of phylogenetic relationships of heterokont and haptophyte algae. Heterokont algae are a monophyletic group that is classified into 17 classes and represents a diverse group of marine, freshwater, and terrestrial algae. Classes are distinguished by morphology, chloroplast pigments, ultrastructural features, and gene sequence data. Electron microscopy and molecular biology have contributed significantly to our understanding of their evolutionary relationships, but even today class relationships are poorly understood. Haptophyte algae are a second monophyletic group that consists of two classes of predominately marine phytoplankton. The closest relatives of the haptophytes are currently unknown, but recent evidence indicates they may be part of a large assemblage (chromalveolates) that includes heterokont algae and other stramenopiles, alveolates, and cryptophytes. Heterokont and haptophyte algae are important primary producers in aquatic habitats, and they are probably the primary carbon source for petroleum products (crude oil, natural gas).  相似文献   

3.
The marine sipunculan worm, Sipunculus nudus Linné, possesses a voluminous coelomic cavity filled with a fluid containing different types of free cells. Most of them (more than 90%) are nucleated haemerythrocytes. They arise from free, small haemerythroblastic cells which are described in this report. Different kinds of leucocytes are also found in the coelomic fluid, particularly granulocytes which are phagocytic cells showing some similarities with vertebrate macrophages. These cells seem to arise from small hyalocytes, which are cells having morphological and physiological resemblances with vertebrate lymphocytes. It appears that the older granulocytes are progressively degranulated and give rise to large hyalocytes. Ciliary cells arising from small cells, very similar to small hyalocytes, have also been observed and it is supposed that they give rise to urn cells. Lastly, some of the biological functions of the free coelomic cells of the sipunculan worms are described.  相似文献   

4.
Virtually every type of organism may serve as a host for viruses. In some hosts, virus presence may be considered beneficial to humans; in other hosts, viruses are considered detrimental. Examples of viruses that are considered beneficial to humans include those that are used for biological control of organisms that themselves are considered detrimental to humans, such as plant pathogenic fungi. Viruses are extremely variable in terms of morphology, structure, and genome organization. However, viruses that attack hosts from different kingdoms may be related, deriving from the same phylogeny. This paper summarizes some of the properties of three related families of viruses that attack hosts in different kingdoms: the animal-infecting Picornaviridae, the plant-infecting Potyviridae, and the fungus-infecting Hypoviridae. Properties of these viruses that set them apart from each other and factors that may affect their evolution are discussed.  相似文献   

5.
The major issues regarding the welfare of both farmed and laboratory rabbits are reviewed, according to husbandry and management systems. The main stressors that can affect welfare and homeostatic responses in rabbits are also reviewed. An overview of the most widespread housing systems for both farmed and laboratory rabbits is presented. The main problems related to housing and management are identified, in particular those related to individual and group housing, space requirements and group size, as well as human-animal interaction. The effects of psychological and physical stressors on physiology and behaviour are illustrated through examples in various rearing conditions. Psychological stressors include social stress and fear, while physical stressors include environmental variables such as housing system and climatic factors, i.e. heat. Welfare indicators are identified that can be monitored to determine the effects of individual and environmental variables on the animals' possible coping strategies. Physiological indicators include the neuro-endocrine and psycho-neuro-immuno-endocrine measurements, while behavioural indicators include the behavioural repertoire and responses to behavioural tests. Some possible ways to enhance welfare are indicated, such as enrichment of the environment and improved handling procedures.  相似文献   

6.
李寿建  汪琦  刘奇正  董彩虹 《菌物学报》2019,38(9):1395-1406
茯苓Wolfiporia cocos是我国药食两用的传统中药,本文对茯苓的分类地位、交配型、生活史、遗传育种、菌核栽培以及组学相关研究进展进行了总结,对有关专利进行了分析。以研究及生产现状为基础,分析了茯苓在基础生物学方面研究的不足、菌核栽培中存在的相关问题,重点分析了交配型研究、子实体诱导形成和生活史研究等重要方面,并对未来茯苓生物学研究和科学栽培进行了展望。  相似文献   

7.
Nordin A  Savić S  Tibell L 《Mycologia》2010,102(6):1339-1349
Phylogenetic analyses based on nuLSU and mtSSU indicate that Megasporaceae is monophyletic. Aspicilia species were distributed among three main well supported groups and one group with low support that included the type species; a division of the family into five genera is proposed. The old names Circinaria and Sagedia are reintroduced for groups not including A. cinerea, the type of Aspicilia. The monotypic Megaspora is closely related to Circinaria, while Lobothallia is the sister group of the other Megasporaceae genera. Aspicilia recedens and A. farinosa are transferred to Lobothallia. Species of the 'Sphaerothallia group' are nested in Circinaria. Aspilidea is not a member of Megasporaceae but seems to be more closely related to Ochrolechiaceae. Aspilidea myrinii is neotypified, and lectotypes are designated for Aspicilia gibbosa, A. leprosescens and Lecanora gibbosula.  相似文献   

8.
Cell surface proteins are posttranslationally modified by tightly regulated enzymes of glycosylation. Typical patterns of glycosylation may signal pathological situations to the immune system. Here, carbohydrate receptors on the surface of cells in the immune system are involved in regulation of effector cells. Moreover, some lectins are circulating in the plasma and take part in host defense. The code of carbohydrate modifications is impaired in malignant cells and yet they are not eliminated. In this review, we focus on recent experimental evidence for regulatory functions of lectins and carbohydrate derivatives in the immune system and tumours.  相似文献   

9.
The astelioid group of asparagoid lilies (Lilianae - Asparagales) comprises Hypoxidaceae, Asteliaceae, Blandfordia and Lanaria. New information is presented on astelioid anatomy, together with a review of other systematic characters. These data are analysed in the context of recent evidence from rbc L nucleotide sequences that astelioids are related to orchids, and that astelioids and orchids (plus Alania and Borya ) form a clade that is sister to all other asparagoid taxa. Hypoxidaceae and Asteliaceae differ from each other in several respects, but there are certain characters linking the two families, notably branched hairs and mucilage canals, unusual characters in Lilianae. Family diagnoses are upheld, but the precise relationships of Blandfordia and Lanaria are still poorly supported within the astelioid clade.  相似文献   

10.
Evolutionary theories of aging predict the existence of certain genes that provide selective advantage early in life with adverse effect on lifespan later in life (antagonistic pleiotropy theory) or longevity insurance genes (disposable soma theory). Indeed, the study of human and animal genetics is gradually identifying new genes that increase lifespan when overexpressed or mutated: gerontogenes. Furthermore, genetic and epigenetic mechanisms are being identified that have a positive effect on longevity. The gerontogenes are classified as lifespan regulators, mediators, effectors, housekeeping genes, genes involved in mitochondrial function, and genes regulating cellular senescence and apoptosis. In this review we demonstrate that the majority of the genes as well as genetic and epigenetic mechanisms that are involved in regulation of longevity are highly interconnected and related to stress response.  相似文献   

11.
The major components of the phospholipids of rhesus monkey spermatozoa are phosphatidyl choline (33%), phosphatidyl ethanolamine (25%), ethanolamine plasmalogen (16-1%), sphingomyelin (8-1%), choline plasmalogen (6-9%) and cardiolipin (4-5%). The major phospholipid-bound fatty acids are 16:0, 18:0, 18:1 and 22:6; the major fatty aldehydes are 15:0, 16:0 and 18:2. The same phospholipids are also present in the seminal plasma.  相似文献   

12.
The lentil isolectins, CMLcH A and CMLcH B, and pea isolectins, CMPSA A and CMPSA B, are compared in terms of their spectroscopic and saccharide binding properties. The paramagnetic contribution to the solvent proton magnetic relaxation dispersion profiles of solutions of the isolectins of each protein are found to be essentially identical. Electron paramagnetic resonance spectra suggest a high degree of octahedral symmetry at the Mn2+ site for both pairs of isolectins. The near-ultraviolet absorption spectra of CMLcH A and CMLcH B are identical, as are the spectra of CMPSA A and CMPSA B. Carbohydrate binding activities of the isolectins of each protein are compared using hemagglutination, precipitation, and precipitation-inhibition assays, and are found to be identical, although the activities of CMLcH and CMPSA differ somewhat. These results demonstrate that the spectroscopic and saccharide binding properties of the isolectins of CMLcH are essentially identical, as are those of the isolectins of CMPSA, and suggest that native mixtures of the isolectins may be treated as single proteins in further studies.  相似文献   

13.
Sterols and sphingolipids are considered mainly eukaryotic lipids even though both are present in some prokaryotes, with sphingolipids being more widespread than sterols. Both sterols and sphingolipids differ in their structural features in vertebrates, plants, and fungi. Interestingly, some invertebrates cannot synthesize sterols de novo and seem to have a reduced dependence on sterols. Sphingolipids and sterols are found in the plasma membrane, but we do not have a clear picture of their precise intracellular localization. Advances in lipidomics and subcellular fractionation should help to improve this situation. Genetic approaches have provided insights into the diversity of sterol and sphingolipid functions in eukaryotes providing evidence that these two lipid classes function together. Intermediates in sphingolipid biosynthesis and degradation are involved in signaling pathways, whereas sterol structures are converted to hormones. Both lipids have been implicated in regulating membrane trafficking.Typical examples of eukaryotic lipids, sterols, and sphingolipids can both be found in membranes from simple unicellular fungi and protists to multicellular animals and plants. Their versatile use as structural elements but also as signaling molecules has probably played an important role during the evolution of this large and diverse group of organisms. There are also many eukaryotes that have lost the ability to synthesize sterols de novo including nematodes, insects, and marine invertebrates, which have to take up sterols with their diet. Sterol biosynthesis has also been reported in a number of bacteria. Sphingolipids are more widely spread among prokaryotes than sterols and also show a greater variety of structures among the different eukaryotes.In this short review we will first give an overview about the diversity of sterol and sphingolipid structures and their distribution in nature. Then we will discuss their subcellular distribution. A brief technical section will add some information on the separation and detection of these lipid molecules. Subsequently, we will summarize different genetic approaches to study the functions of sterols and sphingolipids, and finally, we will discuss the functional and possible physical interactions of the two lipid classes within the cell. Far from being comprehensive, we will focus only on a few interesting aspects and try to give new view points, which are less frequently discussed.  相似文献   

14.
Results of the scientific research of genetic mechanisms of ontogenetic and phylogenetic adaptation in the department of genetics and molecular biology of the Odessa national university (ONU) are summarized. The new concept of genetic adaptation and adaptive heterosis is proposed. The evidence are presented that not only selection of selectively valuable alleles of the structural genes of enzymes, but also of gene-modifiers of the gene products are involved in the adaptation of D. melanogaster populations to environmental conditions. As a result, the sets of coadaptation alleles--adaptation complexes of genes (ACG), which are specific to the selective factors, are formed in persons of the population.  相似文献   

15.
The world's oceans are three-dimensional habitats that support high diversity and biomass. Because the densities of most of the constituents of life are greater than that of seawater, planktonic and pelagic organisms had to evolve a host of mechanisms to occupy the third dimension. Some microscopic organisms survive at the surface by dividing rapidly in vertically well mixed zones, but most organisms, small and large, have antisinking strategies and structures that maintain vertical position and mobility. All of these mechanisms have energetic costs, ranging from the "foregone metabolic benefits" and increased drag of storing high-energy, low-density lipids to direct energy consumption for dynamic lift. Defining the niches in the mesopelagic zone, understanding evolution, and applying such ecological concepts as optimal foraging require good estimates of these costs. The extreme cases above are reasonably well quantified in fishes, but the energetic costs of dynamic physiological mechanisms like swim bladders are not; nor are the costs of maintaining vertical position for the chief invertebrate competitors, the cephalopods. This article evaluates a matrix of buoyancy mechanisms in different circumstances, including vacuum systems and ammonium storage, based on new data on the metabolic cost of creating buoyancy in Sepia officinalis.  相似文献   

16.
Moss  Brian 《Hydrobiologia》1992,243(1):31-45
Freshwater basins are vulnerable to human-induced change for a number of reasons. They lie at the bottoms of catchments and therefore are subject to the run-off of a large variety of dissolved and particulate substances; shallow basins provide fertile agricultural soils if drained; and public perception, particularly of wetland basins, is of inhospitable places, so that lobbies for drainage are more likely to be effective than those seeking to preserve the habitat. On the other hand, water is so important to human life that there is also strong concern about the fate of freshwater habitats. Freshwater systems are also often open systems capable of faster recovery from disturbance than their terrestrial counterparts.Three lake, river and wetland ecosystems, the Sudd in the Sudan, the Everglades and adjacent swamplands of southern Florida, USA, and the Norfolk Broadland in the UK are examined from the viewpoints of how they are or were used by their indigenous human populations, and the problems they may face or already face. This sites are used to suggest a general model of human impact and to establish approaches to the wise future use and conservation of these and other similar systems.  相似文献   

17.
Extensive measurements and analysis of thermodynamic stability and kinetics of urea-induced unfolding and folding of hisactophilin are reported for 5-50 degrees C, at pH 6.7. Under these conditions hisactophilin has moderate thermodynamic stability, and equilibrium and kinetic data are well fit by a two-state transition between the native and the denatured states. Equilibrium and kinetic m values decrease with increasing temperature, and decrease with increasing denaturant concentration. The betaF values at different temperatures and urea concentrations are quite constant, however, at about 0.7. This suggests that the transition state for hisactophilin unfolding is native-like and changes little with changing solution conditions, consistent with a narrow free energy profile for the transition state. The activation enthalpy and entropy of unfolding are unusually low for hisactophilin, as is also the case for the corresponding equilibrium parameters. Conventional Arrhenius and Eyring plots for both folding and unfolding are markedly non-linear, but these plots become linear for constant DeltaG/T contours. The Gibbs free energy changes for structural changes in hisactophilin have a non-linear denaturant dependence that is comparable to non-linearities observed for many other proteins. These non-linearities can be fit for many proteins using a variation of the Tanford model, incorporating empirical quadratic denaturant dependencies for Gibbs free energies of transfer of amino acid constituents from water to urea, and changes in fractional solvent accessible surface area of protein constituents based on the known protein structures. Noteworthy exceptions that are not well fit include amyloidogenic proteins and large proteins, which may form intermediates. The model is easily implemented and should be widely applicable to analysis of urea-induced structural transitions in proteins.  相似文献   

18.
国内外蝗害治理技术现状与展望   总被引:3,自引:0,他引:3  
张龙 《昆虫知识》2011,48(4):804-810
本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...  相似文献   

19.
Molecular Systematics and Evolution of Arabidopsis and Arabis   总被引:6,自引:0,他引:6  
Abstract: We provide a phylogenetic analysis of the genera Arabidopsis and Arabis based on nuclear ribosomal DNA sequences. We show that traditional taxonomical concepts within tribe Ara-bideae, which includes these genera, are highly artificial. Arabis and Arabidopsis are paraphyletic and consist of several different independent lineages. The genus Capsella, originally placed in tribe Lepideae, is related to North American Arabis and the Arabidopsis thaliana lineage. Other genera, including East Asian Yin-shania, North American Halimolobus, cosmopolitan Barbarea and Cardamine, and European Aubrieta are positioned among different Arabis lineages. One Arabis species, Arabis pauciflora, is only distantly related to tribe Arabideae. Base chromosome number reduction from n = 8 to n = 5 to 7 occurred several times, suggesting that lower base chromosome numbers than n = 8 are derived in tribe Arabideae. Current knowledge on the evolution and systematics of the genera Arabis and Arabidopsis and relationships within the mustard family are summarized and discussed in the light of convergent evolution and transfer of knowledge from Arabidopsis thaliana as a molecular model plant to other species of the Cruciferae.  相似文献   

20.
The adjuncts to the existing determinations of homoiothermia are made on the basis of new data, the principles of temperature adaptation of humans and homoiothermal animals are presented. The main purposes of the thermoregulation system of homoiothermal animals and humans in various temperature excesses are formulated. The arguments are advanced in favor of the fact that in the thermoneutral zone the thermoregulation system goes from the principles of regulating the temperature homeostasis by one or several temperature points of a body to the regulation by the fluctuations of the total heat content of an organism, which increases the sensitivity and the accuracy of the thermoregulation system operation. The physiological mechanisms are described of determining (measuring) the total heat content of a body.  相似文献   

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