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1.
This paper deals with chromosomal numbers and morphology of 10 species of Aconitum in China. According to the basic number of the genus (x=8), these species can be referred to diploid, tetraploid, hexaploid and octoploid. Correlation is found between chromosomal numbers, sizes and structures. The perennial species with a rhizome are mostly diploid, with chromosomes larger than those in the biennial species with a tuber, and their chromosome pairs 3-7 are mostly subterminal ones, whereas most biennial species are polyploid, and their chromosome pairs 3-7 are almost submetacentric. The evolutionary trends of chromosome from diploid to polyploid, large to small, st to sm are considered possible. The data are agreed with the idea that rhizomal species are more primitive than tuberous ones. The existence of two types of karyotypes in these 10 species is a further support of taxonomic division of two subgenera, subgen. Paraconitum and subgen. Aconitum. In addition, some species are taxonomically discussed.  相似文献   

2.
Gel filtration with 1% agarose (Bio-Gel A-150m) separates polyribosomes bound to microsomal membranes from 'free' polyribosomes when these fractions are prepared by standard centrifugal techniques. However, when polyribosomes contained in an unfractionated postmitochondrial supernatant are run on an identical column, over 90% of the total polyribosomes are present as aggregates, designated 'membrane-cytomatrix', which are eluted in the column void volume. Polyribosomes are not released from these aggregates on removal of microsomal phospholipids by treatment of postmitochondrial supernatant with 1% Triton X-100, a neutral detergent. The aggregates are disrupted by the usual ultracentrifugation techniques used in subcellular fractionation. After treatment of membrane-cytomatrix with Triton X-100 to remove phospholipids and membrane proteins, 58% of the polyribosomes still remain associated with protein-containing complexes in the form of a cytomatrix and are not 'free'. Preparations of both membrane-cytomatrix and cytomatrix are capable of sustained protein synthesis. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis revealed that the cytoskeletal proteins actin and myosin are present in the cytomatrix. Incubation of cytomatrix preparations with the actin-depolymerizing agent deoxyribonuclease I caused release of the polyribosomes. Polyribosome release by deoxyribonuclease I was prevented by prior incubation with phalloidin, which is known to stabilize F-actin. Thus polyribosomes are associated with cytoskeletal elements in rat liver, and this association is dependent on polymeric forms of actin.  相似文献   

3.
Coupled oscillators in a ring are studied using perturbation and numerical methods. Stability of waves with nearest neighbor weak coupling is shown for a class of simple oscillators. Linkens' [23] model for colorectal activity is analyzed and several stable modes are found. Stability of waves with general (non nearest neighbor coupling) is determined and comparisons to the nearest neighbor case are made. Approximate solutions to a ring with inhomogeneities are compared with numerical simulations.Supported by a NSF Grant No. MCS8300885 and the Alfred Sloan Foundation  相似文献   

4.
Abdomens of housefly larvae which are isolated before pupariation and injected with labelled or unlabelled cholesterol are shown by bioassay, thin-layer and gas-liquid chromatography, and tracer experiments to synthesize α- and β-ecdysone. Autoradiography of cross-sections of abdomens injected with labelled cholesterol show that oenocytes are intensively labelled. The results are discussed with respect to the validity of the Calliphora or Musca assay for ecdysones.  相似文献   

5.
Recent studies suggest that species' life histories and ecology can be used to forecast future extinction risk. Threatened species often share similar traits such that if a trait predisposing a species to decline or extinction is evolutionarily conserved, then close relatives of threatened species are themselves likely to be at risk. The phylogenetic distribution of current threat has been argued to provide insight into the species that could be threatened in the future when trait data are not available. Conservation criteria are typically based on multiple indices that capture different symptoms of threat including population trends and range contraction. However, there is no reason to assume consistent phylogenetic distributions of different symptoms. I construct a molecular phylogeny of 249 species of British birds (more than 93% of the breeding and wintering species) and use this to show that the species that are threatened due to population declines are phylogenetically more closely related than expected by chance alone. However, species that are listed for other reasons, including range contraction, are distributed randomly with respect to phylogeny. I suggest that while phylogeny can be informative with respect to identifying clades that are susceptible to some measures of extinction risk, such patterns are likely to be idiosyncratic with respect to symptom and taxa.  相似文献   

6.
Summary Five females with duplication of the short arm of one chromosome 9 are reported, one tetrasomic and four trisomic for 9p. The tetrasomy is due to an isochromosome 9p while the trisomies are due in one case to an intrachromosomal duplication present in lymphocytes but not in fibroblasts, two are secondary to translocations with chromosomes 22 and 13 respectively, and one is a mosaic with a cell line with an additional deleted chromosome 9 present in lymphocytes and fibroblasts. This analysis indicates that duplications 9p may result in impairment of ovarian function. The phenotypic differences between trisomy and tetrasomy 9p are discussed.  相似文献   

7.
Six variable sequence markers are developed and analyzed to find out species boundaries in Hawaiian corals of the genus Pocillopora: the putative mitochondrial control region; a recently discovered, hypervariable mitochondrial open reading frame; the internal transcribed spacer 2 (ITS2), located in the nuclear ribosomal DNA; three nuclear introns of calmodulin, elongation factor-1alpha and the ATP synthase beta subunit. Using the first two markers, we identify five distinct mitochondrial lineages and these lineages are compatible with morphology. The situation is more complex with nuclear markers since more than two haplotypes are observed in some individuals. To detect clusters of individuals, haplotype networks are constructed with additional connections drawn between co-occurring haplotypes to delineate potential fields for recombination: few clusters of nuclear haplotypes are found to correspond to clusters of individuals, but those that are detected (mostly in the ITS2 dataset) are also compatible with morphology.  相似文献   

8.
By the acute glomerulonephritis (GN) of streptococcal etiology, autoantibodies (AA) reacting with the basal layer of skin epithelium (BLSE) are discovered. The presence of this AA's correlate with the high level of antibodies to the streptococcal group A polysaccharide (A-PS). In the control sera such AA's and the high level antibodies to A-PS are discovered very rarely. By the GN of non-streptococcal etiology, AA's to the BLSE apparently of other specificity are obtained in some cases, in spite of the absence of antibodies to A-PS. AA's reacting with the differentiated layers of skin epithelium are discovered in the high percent of cases by GN. The presence of these AA's do not correlate with the levels of antibodies to A-PS. The reduction of the number of T-lymphocyte suppressors is established in the blood by the presence of AA's to the BLSE by GN. This question is a subject of later investigations by the different autoimmune processes. Such data can apparently corroborate the previously expressed hypothesis, that AA's to BLSE, which as a rule react with endocrine thymus epithelium, are the cause of the beginning of immunoregulatory disorders, characteristic of autoimmune processes.  相似文献   

9.
This report represents a continuation of our laboratory's effort to understand the major phenomena associated with P-M dysgenesis-mediated transformation in Drosophila. A group of stable transformants are characterized with respect to rosy gene expression. Stable, true-breeding, line-specific variants in gene expression are described. These are shown to be associated with single transposons present in each line, and the lines are free of functional P elements. The effects on expression are cis-acting, and there are no identifiable rosy DNA sequence lesions associated with these transposons. Evidence is presented that demonstrates that two features of the transformation experimental system are responsible for such variation. The first relates to the fact that the transposons insert at numerous genomic sites. Both heterochromatic and euchromatic position effects are characterized. The second relates to the fact that transformation involves dysgenic mobilization of a P-element transposon. This process is mutagenic, and such a mutation is characterized.  相似文献   

10.
Human ecology is the science on interaction of the man with the environment including the social surrounding. In the human ecological morphology biogenic and sociogenic peculiarities are distinguished; they are formed in the phylo- or ontogenesis. Peculiarities of the body integument, proportions, development of the fat component of the body mass etc. are related with the biogenic signs of the phylogenic origin, since they are connected with life in certain climato-natural conditions. These signs have certain analogues among Mammalia. The sociogenic signs of the phylogenic origin include complexes of bepedality, labour and informative-speech activity. They are characteristic for the human being only. The sociogenic peculiarities of the ontogenic origin include certain changes of the organism connected with professional and sporting activities. According to the human organism state, observed in dynamics, it is possible to judge on biogenic and sociogenic consequences of the environmental influences. For this purpose the data of anthropometric observations in newborn are considered to be important. The role of the biogenic changes is followed in the example of shifts of the body dimensions in time, connected with the solar activity cycles; the sociogenic changes are considered in an example of growth processes under conditions of different gas-pollution of the atmosphere with industrial waste.  相似文献   

11.
The equilibrium configurations for a two-locus multialle model of sex-linked meiotic drive are studied with regard to the recombination fraction:limit cycles can occur in the case of small recombination while stable equilibrium points associated with linkage equilibrium can exist for an intermediate range of recombination values depending on the equilibrium sex ratio, linkage disequilibrium at nearby equilibrium points taking turn with loser linkage. The evolutionary dynamics in two-locus sex-ratio distortion systems is enlightened: while equilibria with a sex ratio closer to 1/2 are more likely to be stable with respect to perturbations on the frequencies of sex-ratio distorters that are represented at equilibrium, such equilibria are also more vulnerable to the invasion of mutant distorters when there is some degree of linkage with the sex-determining locus. For X-linked multimodifier systems of sex-ratio distortion, differential fertilities and viabilities are incorporated and a maximum principle is suggested.  相似文献   

12.
Insights about scaling of folding properties of proteins are obtained bystudying folding in heteropolymers described by Go-like Hamiltonians. Bothlattice and continuum space models are considered. In the latter case, themonomer-monomer interactions correspond to the Lennard-Jones potential.Several statistical ensembles of the two- and three-dimensional targetnative conformations are considered. Among them are maximally compactconformations which are confined to a lattice and those which are obtainedeither through quenching or annealing of homopolymers to their compactlocal energy minima. Characteristic folding times are found to grow aspower laws with the system size. The corresponding exponents are notuniversal. The size related deterioration of foldability is found to beconsistent with the scaling behavior of the characteristic temperatures:asymptotically, the folding temperature becomes much lower than thetemperature at which glassy kinetics become important. The helicalconformations are found to have the lowest overall scaling exponent andthe best foldability among the classes of conformations studied. Thescaling properties of the Go-like models of the protein conformationsstored in the Protein Data Bank suggest that proteins are not optimizedkinetically.  相似文献   

13.
Immunocharacteristics of the pars distalis cells of the pituitary of the male lizard A. carolinensis are determined by employing the immunoperoxidase technique with antisera to mammalian pituitary hormones. On the basis of their immunoreactivity, 5 different cell types with characteristic anatomical distribution are recognized. ACTH cells are found in the rostral half of the pars distalis, and PRL cells in the rostral two thirds of the pars distalis. GH and TSH cells are located in the caudal half of the pars distalis. GTH cells are distributed throughout the gland. When consecutive sections are stained with antiserum to ovine FSH or its beta-subunit and to ovine LH, the same cells show immunoreactivity to all the three antisera. None of the GTH cells show positive immunoreactivity to ovine beta-LH antiserum. The results suggest the existence of one gonadotropic cell type in the pituitary of this lizard.  相似文献   

14.
Macromolecules are sulfated during the vegetative growth of Dictyostelium discoideum. A characterisation of the structures of sulfated oligosaccharides associated with these macromolecules indicates that the oligosaccharides are heterogeneous. Endoglycosidase and pronase digestion were used with gel-filtration chromatography to obtain two different oligosaccharide fractions and a glycopeptide fraction; these were further characterised by ion-exchange and lectin-affinity chromatography and by acid hydrolysis. The data indicate that up to 43% of the sulfate is associated with typical N-linked oligosaccharides, that up to 5% is associated with N-linked oligosaccharides that are either very large or extremely highly charged, and that the remaining sulfate is associated with oligosaccharides non-N-linked to protein. Each fraction was also shown to be heterogeneous at most other structural levels. Electrophoretic analyses following the endoglycosidase and pronase treatments indicated that all of the macromolecules are glycoproteins and suggested further that at least two of the oligosaccharide fractions are located on different groups of glycoproteins.  相似文献   

15.
16.
Alkamides are natural products formed by connecting straight-chain, mostly unsaturated, aliphatic acids with various amines by an amide linkage. More than 300 derivatives are known from eight plant families consisting of various combinations of 200 acids with 23 amines. Apart from a few saturated derivatives alkamides with unsaturated acid parts are grouped into compounds with purely olefinic patterns and those with olefinic and acetylenic linkages. Derived from C18 oleic acid the acid parts are modified either by chain elongations to C28 or by oxidative shortenings to C4 acid residues. Substrate and regiospecific desaturases and acetylenases are responsible for their characteristic patterns of unsaturation. Amine parts are derived from various amino acids by decarboxylation. Beside the widespread isobutylamines alkamides with six- and five-membered ring amines and those with phenylalanine derived amines are characteristic for the Asteraceae and Piperaceae while benzylamines are restricted to the Brassicaceae. Within the Asteraceae 2-methylbutylamine distinguishes the tribe Heliantheae from Anthemideae characterized by ring amines. Alkamides with elongated olefinic acid parts are mainly found in Piperaceae and Brassicaceae while acetylenic acid parts are typical for Asteraceae. A wide variety of biological activities ranges from the characteristic pungent/tingling property and high insecticidal toxicity to significant antifungal, antibacterial, antiprotozoal, molluscicidal, cercaricidal, and acaricidal activity. They also act as plant growth-promoting substances. Position and stereochemistry of the double bonds are essential for the different qualities of the pungent taste. Medically alkamides possess anti-inflammatory and analgesic properties and are responsible for immuno-modulatory and cannabinomimetic effects.  相似文献   

17.
InRita rita the upper lip is associated with the rostral cap and the lower lip with a skin fold. The epithelia of the lips, which are modified with respect to the peculiar feeding behaviour of the fish, are mucogenic. The superficial layer of epithelial cells, in addition to the mucous cells, are involved in active secretion of mucopolysaccharides. Mucus, apart from its diverse functions, as in fish epidermis, lubricates the epithelia giving protection against possible mechanical injury during the searching and catching of prey from bottom debris. Furthermore, the epithelia are thick, an adaptation to their mucogenic nature, so as to provide additional protection. The contents of the club cells are proteinaceous, which correlates with the helical filaments reported in similar cells in fish epidermis. Characteristic ridges on the surface of the lips are considered to be an adaptation to assist in manipulation during the procuring of food. Mucus secreted in the grooves between them reduces friction and prevents the deposition of foreign matter. The skin fold facilitates an increase in gape. The taste buds and ampullary organs, which on the lips and the rostral cap are associated with the localization of prey and triggering of a pick-up reflex, are not located on the skin fold, as the latter often remains concealed between the lower lip and the ventral head skin. The importance of histochemical analysis as a supplement to histological studies is emphasised.  相似文献   

18.
Farrodes nymphs are specialized periphyton/biofilm scrapers. Their maxillae are the most specialized mouthparts, but other elements, with their systems of variously modified setae, are designed to obtain and transport food particles to the pharynx with a minimum of loss. The morphology and adaptations of these mouthparts and related head areas, as well as associated musculature, are described.  相似文献   

19.
贵州疣螈骨骼系统的研究   总被引:6,自引:3,他引:3  
余平静  赵尔宓 《四川动物》2007,26(1):133-136,140
本文运用硬骨-软骨双染色技术对贵州疣螈(Tylototriton kweichowensis)的骨骼系统做了较全面的观察研究,包括头骨、脊柱和前后肢带骨,并对各骨块的形状、位置以及与邻近骨块的关系都作了详细的描述。最后,将贵州疣螈与东方蝾螈、有斑肥螈的骨骼系统进行了比较,为揭示蝾螈科属间演化关系提供一定的依据。  相似文献   

20.
The kinetics of disulphide bond formation in reduced ribonuclease have been determined by following electrophoretically the appearance and disappearance of protein molecules with one, two, three or four intramolecular disulphide bonds. Each successive protein disulphide bond was observed to be formed much less readily than the preceding one, and the resulting species are increasingly unstable to reduction of their disulphide bonds. Most of the species formed directly, even those with four disulphide bonds, do not have the electrophoretic mobility of native protein.Protein molecules apparently refolded correctly are formed by slow intramolecular interconversion of molecules with three disulphide bonds and by thiolcatalyzed interchange of incorrect disulphide bonds in three-or four-disulphide species.These observations are compared with the properties of the folding pathway elucidated for pancreatic trypsin inhibitor under the same conditions and are contrasted with those often envisaged as to how proteins might fold.  相似文献   

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