具休眠体淡水水生生物分布假说的研究进展

淡水水生生物的分布模式一直是进化和生物地理学研究中的热点问题, 特别是对具休眠体水生生物的研究, 早在达尔文时代就开始探讨具休眠体淡水水生生物分布的原因。根据对文献的整理, 可以将具休眠体淡水水生生物分布模式归纳为三种假说: 随机分布(Everything is Everywhere, EIE)假说、独占(Monopolisation)假说和局域特有(Moderate Endemicity, ME)假说。通过对三种假说的定义, 研究进展和形成不同模式的原因等进行分析, 提出了在研究时需注意是否存在隐存种、季节变化引起基因型变化、研究区域是否覆盖了本物种的所有分布范围、地理环境及地质事件与分布模式之间的关系等问题, 以便更准确的研究具休眠体淡水水生生物分布模式。     

Leech segmentation: A molecular perspective

A variety of leech homeobox genes have been identified by homology with genes that are known to bring about the regionalization and segmentation of the anteroposterior body axis in other organisms. Embryonic expression patterns suggest a number of interphyletic similarities in the way that these genes are utilized. However, several interesting differences have also been observed. In particular, transplantation experiments in the leech embryo have shown that axially aligned patterns of homeobox gene expression are not specified by a global pattern of positional cues. Rather, the leech independently establishes anteroposterior patterns of gene expression in each of five discrete stem cell lineages, and these patterns are brought into their final alignment through a process of morphogenetic assembly.     

DNA replication patterns of human chromosomes from fibroblasts and amniotic fluid cells revealed by a Giemsa staining technique.

A technique is described for visualizing late-replicating regions by a Hoechst 33258-Geimsa-staining procedure combining the techniques of Latt (1973) and of Perry and Wolff (1974). The advantages are two-fold: distinct bands are obtained and many possible mistakes and interpretation difficulties with autoradiography are avoided. The time sequence of late-replication patterns (excepting C-group chromosomes) has been established in human fibroblasts of adults, and these results have been compared with three of four different cell types from amniotic fluid. No significant differences in late-replication patterns and time sequence of the different cells could be discovered. As expected, the replication patterns are in good concordance with the patterns of G- and Q-bands. Some exceptions are described.     

Familial mutagen sensitivities: are these the hallmarks of meiotic or mutator mutants in humans?

Mutagen hypersensitivity (MHS) has been found to be associated with abnormalities in DNA metabolic processes in many prokaryotic and eukaryotic organisms. The study of fibroblasts derived from humans with genetic diseases believed to have altered DNA metabolism, has also revealed patterns of MHS. In this paper results are presented that suggest MHS patterns unrelated to obvious disease can be inherited in a dominant fashion. As these individuals exhibiting MHS patterns have been observed in families with poor reproductive history, new syndromes, or ontogenetic problems (including malignancies) there may be a causal relationship between these events and the MHS. These events which may have a genetic basis appear as maternal or paternal effect mutants as the consequences are observed in reduced reproductive fitness or abnormal progeny. Since these effects are similar to the events precipitated by the meiotic or mutator mutants in Drosophila, it is speculated that the MHS patterns may be the hallmarks of such mutants in man.     

Prevalences of hereditary diseases in various populations in Russia

The geographic distribution of hereditary diseases (HDs) in different populations and ethnic groups of Russia has been studied. The main patterns of the formation of the prevalence and spectrum of HDs in five ethnic groups (Russians from six regions, Mari, Chuvashes, Udmurts, and Adygeans) from a total of ten regions of Russia have been analyzed. Analysis of correlations suggests that genetic drift is the main factor of the genetic differentiation of populations with respect to the prevalence of HDs. Accumulation of HDs in individual populations and ethnic groups has been analyzed. Hereditary diseases characterized by locally high prevalence rates in individual populations or ethnic groups have been detected. The main patterns of the accumulation of individual diseases and differences between populations and ethnic groups in this respect have been studied with the use of principal component analysis, which describes these patterns more graphically. It has been demonstrated that the genes of HDs are a promising tool for characterizing ethnogenetic processes in populations.     

Unusual isozyme patterns of glucose-6-phosphate isomerase in polydorids (Polychaeta: Spionidae) and the possible mechanisms of their formation

The isozyme patterns of glucose-6-phosphate isomerase (GPI) have been analyzed in ten species of polychaetes of the genera Polydora and Dipolydora (Polychaeta: Spionidae). The GPI patterns of these species have been found to have some specific characteristics that cannot be explained in terms of the generally accepted views on the nature of isozymes. The patterns are represented by two hybridizing isozymes with different expression specificities that exhibit coordinated allozymic variation in most individuals of each species studied. Involvement of alternative splicing in the expression of the GPI gene is considered to be the most probable mechanism of the formation of the unusual GPI isozyme patterns in polydorids.     

Variation and morphogenetic characteristics of different Stachys species during microclonal propagation

Morphogeneses of Stachys different species introduced in culturing in vitro have been compared. The frequency of altered forms have been demonstrated to be related to the plant genotype. All regenerants of S. sieboldii, which reproduces in vivo only vegetatively, are phenotypically normal, irrespective of the concentrations of plant growth regulators at which they have been obtained. Only changes in isozyme patterns have been observed in the regenerants grown in media containing at least 10 mg/l benzyl aminopurine (BAP); most of these changes are the absence of a particular component of the pattern. The cross-pollinating species Stachys ocymastrum, which typically reproduces by seeds, has yielded morphologically altered forms even in phytohormone-free media; its isozyme patterns often contained a new component. Analysis of the isoperoxidase patterns of regenerants of both Stachys species obtained with the use of high phytohormone concentrations has demonstrated qualitative and quantitative changes suggesting the appearance of somaclonal variants even in the course of plant regeneration directly from nodal segments, bypassing callus formation. Changes have also been found in Stachys plants regenerating from the callus tissue.     

Chemical modification patterns compatible with high potency dicer-substrate small interfering RNAs

Dicer-substrate small interfering RNAs (DsiRNAs) are synthetic RNA duplexes that are processed by Dicer into 21-mer species and show improved potency as triggers of RNA interference, particularly when used at low dose. Chemical modification patterns that are compatible with high potency 21-mer small interfering RNAs have been reported by several groups. However, modification patterns have not been studied for Dicer-substrate duplexes. We therefore synthesized a series of chemically modified 27-mer DsiRNAs and correlated modification patterns with functional potency. Some modification patterns profoundly reduced function although other patterns maintained high potency. Effects of sequence context were observed, where the relative potency of modification patterns varied between sites. A modification pattern involving alternating 2'-O-methyl RNA bases was developed that generally retains high potency when tested in different sites in different genes, evades activation of the innate immune system, and improves stability in serum.     

Prevalences of hereditary diseases in different populations of Russia

The geographic distribution of hereditary diseases (HDs) in different populations and ethnic groups of Russia has been studied. The main patterns of the formation of the prevalence and spectrum of HDs in five ethnic groups (Russians from six regions, Mari, Chuvashes, Udmurts, and Adygeans) from a total of ten regions of Russia have been analyzed. Analysis of correlations suggests that genetic drift is the main factor of the genetic differentiation of populations with respect to the prevalence of HDs. Accumulation of HDs in individual populations and ethnic groups has been analyzed. Hereditary diseases characterized by locally high prevalence rates in individual populations or ethnic groups have been detected. The main patterns of the accumulation of individual diseases and differences between populations and ethnic groups in this respect have been studied with the use of principal component analysis, which describes these patterns more graphically. It has been demonstrated that the genes of HDs are a promising tool for characterizing ethnogenetic processes in populations.     

Characterization of normal and rearranged human chromosomes by simultaneous Q- and R-banding with chromomycin A3

Simultaneous Q- and R-type banding patterns in human chromosomes have been achieved by staining with chromomycin A3. Some peculiarities of these patterns as compared to the patterns induced by other fluorochromes are described. The resolution power of this technique in analyzing structural rearrangements of human chromosomes is discussed.     

Pattern formation in interacting and diffusing systems in population biology

In this article, we have been mainly concerned with spatially non-uniform stationary states and their stability, motivated by pattern formation arising in population biology. The discussions are restricted to one-dimensional space, though real systems are always distributed in at least two-dimensional space. Even if we limit ourselves to small-amplitude solutions, it seems difficult to discuss the bifurcation problems in a manner similar to that for one-dimensional space. One of the reasons is that the bifurcation points are not easily found. However, some general theories have nearly been completed.There are a variety of phenomena of other patterns such as wave trains, wave fronts, pulse waves, target patterns, and rotating patterns in equations of reaction and diffusion. We have not discussed these here.Moreover, we emphasize that there are a lot of nonlinear diffusion problems which are different from the ones that were dealt with here. The book by Fife (1), for example, provides a good exposition on these problems.     

Comparison of egg-white proteins: Effect of electrophoretic conditions

The electrophoretic patterns of whole egg-white proteins have been determined for a variety of species from several avian orders using standard techniques of cellulose acetate strip electrophoresis. The results obtained have been correlated with immunological measurements made on ovalbumin. It is concluded that the nature of the separation media and the buffers used must be considered if meaningful comparisons are to be made between different studies. More information on both intra- and inter-group comparisons are necessary before the full significance of the patterns can be assessed and related to immunological data.     

The fossil record of fish ontogenies: Insights into developmental patterns and processes

One of the properties of fossils is to provide unique ontogenies that have the potential to inform us of developmental patterns and processes in the past. Although fossilized ontogenies are fairly rare, size series of relatively complete specimens for more than 90 fish species have been documented in the literature. These fossilized ontogenies are known for most major phylogenetic groups of fishes and have a broad stratigraphic range extending from the Silurian to the Quaternary with a good representation during the Devonian. Classically, size series have been studied in terms of size and shape differences, where subsequently allometric changes were used as indicators of heterochronic changes in Paleozoic placoderms and sarcopterygians. Quantitative analyses of fossilized ontogenies of dipnoans have been interpreted in terms of morphological integration and fluctuating asymmetry. Recently, reconstructed sequences of ossification have been used to identify recurrent patterns of similar development in actinopterygians and sarcopterygians in order to infer phenotypic developmental modularity and saltatory pattern of development. Phylogenetic and temporal landmarks are put forward for some of the major developmental patterns in the evolution of fishes.     

Environmental signals from leaves--a physiognomic analysis of European vegetation

Leaf physiognomic traits vary predictably along climatic and environmental gradients. The relationships between leaf physiognomy and climate have been investigated on different continents, but so far an investigation based on European vegetation has been missing. A grid data set (0.5 degrees x 0.5 degrees latitude/longitude) has been compiled in order to determine spatial patterns of leaf physiognomy across Europe. Based on distribution maps of native European hardwoods, synthetic chorologic flora lists were compiled for all grid cells. Every synthetic chorologic flora was characterised by 25 leaf physiognomic traits and correlated with 16 climatic parameters. Clear spatial patterns of leaf physiognomy have been observed, which are statistically significant related to certain, temperature-related climate parameters. Transfer functions for several climatic parameters have been established, based on the observed relationships. The study provides evidence that synthetically generated floras represent a powerful tool for analysing spatial patterns of leaf physiognomy and their relationships to climate. The transfer functions from the European data set indicate slightly different relationships of leaf physiognomy and environment compared with results obtained from other continents.     

达乌尔黄鼠显带染色体的研究

达乌尔黄鼠分布在我国北方及蒙古和苏联等区域,对牧草及农田危害甚大。有关达乌尔黄鼠的核型国内外已有报道(Lyapunova等,1970;蔡有余等,1985;马继霞等,1985)。签于其染色体的一些特征,达乌尔黄鼠有可能成为染色体工程及检测环境诱变剂等方面的实验材料。虽然苏联Lyapunova等(1978,1980)对黄鼠属某些种的G-带和C-带进行过比较研究,我国蔡有余等(1985)对达乌尔黄鼠的C-带和Ag-NOR进行了观察,但无法对其染色体进行逐个地准确识别,特别是对Χ染体色的正确识别。为此,我们对达乌尔黄鼠的显带染色体进行了较详细的研究。     

Nature disfavors sequences of alternating polar and non-polar amino acids: implications for amyloidogenesis

Recent experiments with combinatorial libraries of de novo proteins have demonstrated that sequences designed to contain polar and non-polar amino acid residues arranged in an alternating pattern form fibrillar structures resembling beta-amyloid. This finding prompted us to probe the distribution of alternating patterns in the sequences of natural proteins. Analysis of a database of 250,514 protein sequences (79,708,024 residues) for all possible binary patterns of polar and non-polar amino acid residues revealed that alternating patterns occur significantly less often than other patterns with similar compositions. The under-representation of alternating binary patterns in natural protein sequences, coupled with the observation that such patterns promote amyloid-like structures in de novo proteins, suggests that sequences of alternating polar and non-polar amino acids are inherently amyloidogenic and consequently have been disfavored by evolutionary selection.     

Activity and isoenzyme composition of peroxidase and esterase in fertile and male-sterile lines of tomatoes (Lycopersicon esculentum Mill.)

A comparative study of the isoenzyme patterns of esterase and peroxidase and overall peroxidase activity in stamens of male-sterile (MS) lines of Pearson ms-35 and P ms-35aa and of the respective male-fertile (MF) tomato plants have been conducted. The study has been made at two stages of stamens development — tetrad and pollen. Higher activities of the esterase isoenzymes in the MF stamens than that of MS in both ontogeny stages have been found. The slow moving esterase isoenzymes both of the MF and the MS stamens are the major isoenzymes in the early stage and are connected with tapetum development while the fast moving esterase isoenzymes are connected with pollen formation in the later ontogeny stage. Overall peroxidase levels in the MS stamens were higher than those of MF. The peroxidase patterns of the MS lines are also characterized by the greater number of isoenzymes and also the presence of specific isoenzymes, the contrast between the MF and the MS stamens being more strongly expressed at the later stage of development. A strong similitude between esterase and peroxidase patterns behaviour in both MS lines has been found.     

Tissue specificity of chromatin glycoproteins recognized by concanavalin A

Chromatin glycoproteins recognized by Concanavalin A have been isolated from pig liver, kidney and heart by the use of immobilized lectin. Two groups of proteins differing in affinity for DNA have been analysed. Glycoproteins are mainly present in the group of proteins which are tightly bound to DNA. Mono and bidimensional electrophoretic patterns of total tightly bound proteins reveal a similarity among the three organs examined, while the corresponding patterns of the glycoproteins are typical for each organ. The tissue specificity of chromatin glycoproteins, together with their capability to interact not only with DNA but possibly also with other nuclear components, suggest a role for these proteins in the mechanism of genome expression.