Chromosomal features and evolution of Bromeliaceae

New cytological information and chromosome counts are presented for 19 taxa of 15 genera of the Bromeliaceae, among them, data for 15 taxa and five genera are reported for the first time. The basic number x = 25 is confirmed and polyploidy seems to be the main evolutionary mechanism in Bromeliaceae. Most of the analyzed species presented 2n = 50. Polyploids have been detected in Deinacanthon urbanianum with 2n = ca.160 and Bromelia laciniosa with 2n = ca.150. In Deuterocohnia lorentziana we observed individuals with two different ploidy levels (2n = 50 and 2n = 100) growing together in the same pot. Ayensua uaipanensis showed the uncommon number 2n = 46. After triple staining with CMA₃/Actinomycin/DAPI one or two CMA⁺/DAPI⁻ bands could be observed in the studied species (Aechmea bromeliifolia, Greigia sphacelata and Ochagavia litoralis). The role of these features in the evolution of the family is discussed, revealing new aspects of the evolution of the Bromeliaceae.     

Characteristic features of the coumarin induced growth

Summary Effect of 2,4-dinitrophenol, iodoacetic acid, mannitol, ribonuclease, CaCl₂, phosphates, low oxygen tension, different temperatures, CCC and IAA on the coumarin-induced growth of sunflower hypocotyl sections have been investigated. Results indicate that coumarin-induced growth is auxin-like in type; nevertheless, the primary mode of coumarin action is probably quite different from that of IAA.With 4 Figures in the Text     

Characteristic features of electron-ion collisions in strong electric fields

The classical motion of an electron in the Coulomb field of an ion and in a uniform external electric field is analyzed. A nondimensionalization method that makes it possible to study electron motion in arbitrarily strong electric fields is proposed. The possible electron trajectories in the plane of motion in a static field are classified. It is noted that, from a practical standpoint, the most interesting trajectories are snakelike trajectories, which are absent in the problem with a weak external field. An adiabatic approximation for transverse electron motions in quasistatic (strong) fields is constructed. A one-dimensional equation of motion is derived that accounts for transverse electron oscillations and the increase in the effective electron mass as an electron approaches an ion. An analytic model is used to calculate the spectra of bremsstrahlung generated by individual electrons. The calculated results are shown to agree well with the results of direct numerical integration of the basic equations. It is predicted that, at frequencies higher than the frequency of the incident light, pronounced peaks can appear in the spectrum of the transverse dipole moment of an electron; as a result, an electron is expected to effectively emit radiation at these frequencies in the direction of the external field.     

Universal features in the genome-level evolution of protein domains

Background  

Protein domains can be used to study proteome evolution at a coarse scale. In particular, they are found on genomes with notable statistical distributions. It is known that the distribution of domains with a given topology follows a power law. We focus on a further aspect: these distributions, and the number of distinct topologies, follow collective trends, or scaling laws, depending on the total number of domains only, and not on genome-specific features.     

Major features in the evolution of early hominoid locomotion

Evolution of hominoid locomotion is a traditional topic in primate evolution. Views have changed during the last decade because a number of crucial differences between early and advanced hominoid morphologies have been demonstrated. Increasing evidence on primate behaviour and ecology show that any direct analogies between living and fossil hominoids must be made extremely carefully. The necessity of synthesizing data on primate behaviour, locomotion, morphology and ecology and simultaneously defining the framework in which the data should be interpreted are explained. Results of our studies of ontogeny of locomotor and behavioural patterns (LBP) are presented that could help identify the main features of early hominoid locomotor patterns (LP) and the mechanisms of their changes. The early hominoid LP was different from those of pronograde monkeys and specialized antipronograde living apes. Some similar features could be expected between early hominoid LP and the LP of ceboid monkeys. Analogous mechanisms of change of LBP exist in all groups of living higher primates. Crucial early mechanisms of change are the ontogenetic shifts in LBP connected with ethoecological changes. Analysis of fossil evidence has shown that Miocene hominoids differ morphologically from any group of living primates. Certain features present in Miocene hominoids could be found in Atelinae and living Asian apes but they are limited to some functional regions of the postcrania only. Consequently the early hominoid general LP can not be strictly analogous either to that of any monkey group or to the LP of apes. We suppose that certain pronograde adaptations, such as climbing, bipedality, limited suspensory activity and sitting constituted the main part of their LP.     

Characteristic features of protoplast formation and regeneration in Fusidium coccineum

The methods for preparation and regeneration of protoplasts were tested with respect to the strains of F. coccineum markedly differing in their capacity for antibiotic production, sporulation and the growth rate. It was found that the substrate used for the culture growth had a significant effect on the cell wall and sensitivity of the mycelium to lytic enzymes. An enzyme from Hellix pomatia and its combination with lysozyme were used for lysing the culture. The cytological investigation of the time course of the culture lysis revealed a stage-by-stage pattern of protoplast formation by means of fragmentation of the hyphal contents till a ball was formed. Two to 4 protoplasts differing in their size and structure were formed within a cell. The pH value and osmotically stabilizing component had some effect on the rate of protoplast formation. Highly productive strains were characterized by formation of protoplasts heterogenous in their size and by decreased frequency of regenerations. The enzyme-free protoplasts preserved their viability and capacity for germination in osmotically stabilizing media for 72-96 hours of storage at 4 degrees C. On solid media the regeneration frequency reached 38 per cent. The regenerated cells formed colonies morphologically similar to those of the intact culture.     

Characteristic features of amino acid residues in coiled-coil protein structures

Detailed analyses of protein structures provide an opportunity to understand conformation and function in terms of amino acid sequence and composition. In this work, we have systematically analyzed the characteristic features of the amino acid residues found in alpha-helical coiled-coils and, in so doing, have developed indices for their properties, conformational parameters, surrounding hydrophobicity and flexibility. As expected, there is preference for hydrophobic (Ala, Leu), positive (Lys, Arg) and negatively (Glu) charged residues in coiled-coil domains. However, the surrounding hydrophobicity of residues in coiled-coil domains is significantly less than that for residues in other regions of coiled-coil proteins. The analysis of temperature factors in coiled-coil proteins shows that the residues in these domains are more stable than those in other regions. Further, we have delineated the medium- and long-range contacts in coiled-coil domains and compared the results with those obtained for other (non-coiled-coil) parts of the same proteins and non-coiled-coil helical segments of globular proteins. The residues in coiled-coil domains are largely influenced by medium-range contacts, whereas long-range interactions play a dominant role in other regions of these same proteins as well as in non-coiled-coil helices. We have also revealed the preference of amino acid residues to form cation-pi interactions and we found that Arg is more likely to form such interactions than Lys. The parameters developed in this work can be used to understand the folding and stability of coiled-coil proteins in general.     

Characteristic features in the "laryngotrachea" of Suncus murinus

In the larynx of the Suncus murinus (house musk shrew), the cricoid cartilage was situated laterally to and overlapped with the 1st, the 2nd, and a part of the 3rd tracheal cartilages. The term "laryngotrachea" was used for the region maintained by both the cricoid cartilage and the tracheal ones. It is suggested that the condition of the cartilages in Suncus laryngotrachea is the most primitive condition in mammals. In the dorsal wall, just caudal to the plate of the cricoid cartilage and dorsal to the 3rd tracheal cartilage, there existed the "L-shaped cartilage" (named by the authors).     

Clone selection and the evolution of modifying features

A statistical mechanism of long-run selection is formulated in order to explain the evolution of modifying features governing mutation, recombination, sexual behavior, demographic mobility, and other factors that do not directly increase the individual fitness of their carrier but which are, supposedly, essential for future evolution of a population. Survival probability of a clone, rather than that of the individual, is shown to play the main role in this mechanism. Changing environment proves to be the main factor affecting it.A theoretical possibility of a long-run adaptation to the dynamics of an environmental change—rather than to a static situation resulting from it—is demonstrated.     

Characteristic features of antilipolytic activity of serum in relation to obesity.

Antilipolytic activity (ALA) of serum of the obese and controls was tested on rat epididymal adipose tissue incubated in medium containing adrenaline; the results were compared with the effect of insulin. Serum of the obese displayed lower ALA than controls, in one third obese individuals serum potentiated the effect of adrenaline. After fasting, ALA of serum decreased. ALA value is related to the prevailing metabolic situation, an inverse relationship was observed between ALA and levels of NEFA and ketone bodies. This seems to suggest that antilipolytic effect of insulin, whose concentrations are higher in the obese, is antagonised. This effect does not apparently depend on the presence of insulin antibodies, which do not inhibit, but, on the contrary, potentiated antilipolytic effect of insulin in vitro. Investigation of fractions of native serum proteins showed the effect of fraction 10 000--50 000 MW. to differ in the obese and controls. That particular fraction of sera of the obese had an adipokinetic effect.     

Characteristic features of induced mutagenesis in hybrid dysgenesis systems of Drosophila melanogaster

The mutagenic effect of low-dose gamma-irradiation was studied in Drosophila melanogaster systems of hybrid dysgenesis by estimating polytene chromosome rearrangements, recombination frequency, and viability at the embryonic and postembryonic developmental stages. A dose of gamma-irradiation which had no effect detectable by routine line crossing proved to significantly reduce the number of recombinants in the H-E and P-M systems and mortality at postembryonic stages. However, this combined effect was obtained if irradiation followed transposition, i.e., it depended on the application sequence of the mutagenic factors. The reverse order of the mutagenic treatment led to summation of the effects: as compared to either control, the frequencies of the dominant allele mutations as well as the larval and pupal mortality in F2 increased significantly (at the level of 99.9%). This allowed us to estimate the contribution of extremely low-dose gamma-irradiation into the mutagenic effect, which was impossible under routine conditions.     

Characteristic features of protein synthesis in the extracellular matrix during tumor growth

Changes in the biosynthesis of basic extracellular proteins (e.g., collagen proteins, fibronectins, proteoglycans) in the course of neoplastic growth are reviewed. Some peculiarities of quantitative changes in the biosynthesis and modifications of the primary structure of the above macromolecules are discussed in terms of neoplastic cell differentiation. The main emphasis is laid on the mechanisms underlying the disturbances in the biosynthetic activity of extracellular matrix proteins in neoplastic cells at different steps of protein synthesis and extracellular degradation of protein molecules.     

Simulation of interstellar chemical evolution in a low temperature plasma

In order to simulate the interstellar chemical evolution, the chemical process was studied in a laboratory plasma flow. The apparatus was so designed as to establish the similarity between laboratory and cosmic conditions. The plasma temperature was found to be less than 100 K in the downstream region. HCN, HC₃N, H₂CO, and several kinds of hydrocarbons were produced from the plasma whose elementary composition was approximately same as the cosmic abundance. Based on the analysis by laser-induced-fluorescence method, HCN and HC₃N were concluded to be synthesized via CN loss reactions, while it was unlikely that the syntheses of C₂H₂ and H₂CO were related to the generation or depletion of C₂.     

Size and temperature in the evolution of fish life histories

Body size and temperature are the two most important variablesaffecting nearly all biological rates and times, especiallyindividual growth or production rates. By favoring an optimalmaturation age and reproductive allocation, natural selectionlinks individual growth to the mortality schedule. A recentmodel for evolution of life histories for species with indeterminategrowth, which includes most fish, successfully predicts thenumeric values of two key dimensionless numbers and the allometryof the average reproductive allocation versus maturation sizeacross species. Here we use this new model to predict the relationshipsof age-at-maturity, adult mortality and reproductive effortto environmental temperature and maturation size across species.Age-at-maturity, adult mortality and the proportion of the bodymass given to reproduction per year are predicted to show ±0.25power allometries with mass at maturity, and an exponential(Boltzmann) temperature dependence. Temperature is assumed toaffect only body size growth, so the temperature linkages ofmaturation, mortality and reproductive effort are indirect vialife history optimization; this is briefly contrasted with theidea that (for example) temperature directly affects mortality.     

Unusual features of cereal seed protein structure and evolution

The alcohol-soluble (prolamin) storage proteins of barley, wheat and rye vary in their structures, but all have two features in common: the presence of distinct structural domains differing in amino acid compositions, and of repeats within one of these domains. Detailed comparisons of amino acid sequences show that all appear to have evolved from a single ancestral gene consisting of three short related regions (called A, B and C). Regions related to A, B and C are also present in the minor prolamins of maize and in three other groups of seed proteins: inhibitors of alpha-amylase and/or trypsin from cereals. 25 storage globulins from several dicotyledonous species and a 2S albumin from sunflower. It is suggested that these proteins together constitute a protein superfamily with limited sequence homology.     

Current filaments in plasmas

Possible configurations of current filaments in Z-pinch and tokamak plasmas are analyzed. A thin current-carrying beam injected in a plasma should be surrounded by a halo of countercurrents, in which case the resulting configuration may resemble a tubular structure. A.B. Kukushkin and V.A. Rantsev-Kartinov pointed out the existence of specific plasma structures of the squirrel-cage type and interpreted them as “wild cables of solid-state nanotubes.” It is shown that these structures can also be attributed to the fundamental mode of the conventional magnetic filamentation in the form of a “hexagonal parquet.” Also, a study is made of the phenomena governing the pattern of plasma structures, namely, tearing filamentation, two types of longitudinal beam bunching, and self-organization of the filaments.     

Sperm methylation profiles reveal features of epigenetic inheritance and evolution in primates

During germ cell and preimplantation development, mammalian cells undergo nearly complete reprogramming of DNA methylation patterns. We profiled the methylomes of human and chimp sperm as a basis for comparison to methylation patterns of ESCs. Although the majority of promoters escape methylation in both ESCs and sperm, the corresponding hypomethylated regions show substantial structural differences. Repeat elements are heavily methylated in both germ and somatic cells; however, retrotransposons from several subfamilies evade methylation more effectively during male germ cell development, whereas other subfamilies show the opposite trend. Comparing methylomes of human and chimp sperm revealed a subset of differentially methylated promoters and strikingly divergent methylation in retrotransposon subfamilies, with an evolutionary impact that is apparent in the underlying genomic sequence. Thus, the features that determine DNA methylation patterns differ between male germ cells and somatic cells, and elements of these features have diverged between humans and chimpanzees.     

Unique genes in plants: specificities and conserved features throughout evolution

Background  

Plant genomes contain a high proportion of duplicated genes as a result of numerous whole, segmental and local duplications. These duplications lead up to the formation of gene families, which are the usual material for many evolutionary studies. However, all characterized genomes include single-copy (unique) genes that have not received much attention. Unlike gene duplication, gene loss is not an unspecific mechanism but is rather influenced by a functional selection. In this context, we have established and used stringent criteria in order to identify suitable sets of unique genes present in plant proteomes. Comparisons of unique genes in the green phylum were used to characterize the gene and protein features exhibited by both conserved and species-specific unique genes.     

Characteristic features of EchoCG parameters in men and women with different geometric configurations

An echocardiographic study of 190 subjects in the second period of adult age (108 women and 82 men) has been conducted. The absolute and relative sizes of the left ventricle (LV), left atrium (LA), right ventricle (RV), myocardium mass, and LV mass index were determined. Morphological changes in the heart detected by echocardiography (EchoCG) depended on the geometric configuration of the LV. The size of the RV was significantly increased in women with hypertrophy of the myocardium of the LV. All the EchoCG parameters with the exception of relative wall thickness (RWT) were gender-dependent. The gender-dependent differences in LV remodeling included higher values of LV mass index in men, different dynamics of the LV mass index (LVMI) in subjects with different geometric configurations of the LV, and more pronounced elevation of the index in women with eccentric hypertrophy of the LV (LV EG), in particular. The functional capacity of the heart was lower in men than in women.