Morphological and somatic clonal analyses of pattern triplications

The growth of pattern triplications induced by a 48-hr 29 degrees C treatment given to larvae homo- or hemizygous for a ts cell-lethal mutation was examined to determine which structures result from new, regulative growth and which are produced by the original imaginal disc cells. Pattern triplications contain one complete leg pattern (orthodrome) and two partial patterns (antidrome and paradrome). The results of two morphological analyses and one somatic clonal analysis suggest that in triplications in which the antidrome and paradrome become more complete distally (diverge) the paradrome is formed by a portion of the original leg pattern, and the antidrome and orthodrome are formed by extra, regulative growth. A different result is suggested for triplications in which the antidrome and paradrome become less complete distally (converge). In these, the orthodrome appears to be formed by the original leg pattern and the antidrome and paradrome by extra growth. These results agree with predictions based on the polar coordinate model of positional information.     

Enviromentally Induced Changes in Clamp Connection Incidence in Hyphal Branching Systems of Coprinus disseminatus

The incidence of clamp connections among surface hyphae at thecolony margin of apparent dikaryons from four stocks of Coprinusdisseminatus has been investigated under several environmentalconditions. On 2 per cent malt agar, clamp connections are formed at allnodes of the main leader hyphae, but they are absent from theearlier-formed nodes of primary branch hyphae. Most primarybranches have begun to form clamp connections by their fifthcell division, and continue to do so subsequently. Onset ofclamp connection formation in primary branches is delayed whenthe concentration of malt in the medium is reduced. The occurrenceof clamp connections on main leader hyphae is reduced or preventedwhen nutrient supply in the medium is reduced, or when the mediumis ‘pre-staled’ by previous growth of C. disseminatus.Clamp-free main hyphal tips revert to formation of clamp connectionswhen the intact hyphal system is transferred to more favourableenvironmental conditions. Presence of clamp connections on bothmain and branch hyphae is associated with high hyphal diameter,and in some instances, also with high hyphal extension rate. The significance of these observations to mechanisms of growthof hyphal branching systems and their relevance to other speciesthat form clamp connections intermittently, are discussed.     

Theory of V.A. Dogiel on polymerization and oligomerization as a general integration concept

The theory of V.A. Dogiel on the significance of polymerization and oligomerization processes in the evolution of Protozoa and Metazoa is compared with the paper of I.I. Schmalhausen (1972) on factors and steps of aromorph evolution. Dogiel’s theory is considered as a general integration conception. Four steps are distinguished in the evolution of biological systems: (1) formation of morphofunctional system by units of the lower structural level, (2) polymerization of morphofunctional units of a system, (3) oligomerization of morphofunctional units of system by means of their reduction, uniting, or differentiation, (4) integration and stabilization of a system owing to development of morphofunctional connections between its parts.     

Evolution of predetermined germ cells in vertebrate embryos: implications for macroevolution

The germ line is established in animal embryos with the formation of primordial germ cells (PGCs), which give rise to gametes. Therefore, the need to form PGCs can act as a developmental constraint by inhibiting the evolution of embryonic patterning mechanisms that compromise their development. Conversely, events that stabilize the PGCs may liberate these constraints. Two modes of germ cell determination exist in animal embryos: (a) either PGCs are predetermined by the inheritance of germ cell determinants (germ plasm) or (b) PGCs are formed by inducing signals secreted by embryonic tissues (i.e., regulative determination). Surprisingly, among the major extant amphibian lineages, one mechanism is found in urodeles and the other in anurans. In anuran amphibians PGCs are predetermined by germ plasm; in urodele amphibians PGCs are formed by inducing signals. To determine which mechanism is ancestral to the tetrapod lineage and to understand the pattern of inheritance in higher vertebrates, we used a phylogenetic approach to analyze basic morphological processes in both groups and correlated these with mechanisms of germ cell determination. Our results indicate that regulative germ cell determination is a property of embryos retaining ancestral embryological processes, whereas predetermined germ cells are found in embryos with derived morphological traits. These correlations suggest that regulative germ cell formation is an important developmental constraint in vertebrate embryos, acting before the highly conserved pharyngula stage. Moreover, our analysis suggests that germ plasm has evolved independently in several lineages of vertebrate embryos.     

Chromocentral nature of interchromosome connections coorienting nonhomologous chromosomes in meiosis of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> females

Data are presented in favor of universal significance of physical connections between pericentromeric regions of homologs in their orientation to the opposite poles of the first meiotic division in Drosophila melanogaster. Disturbances in the formation of such connections caused by structural or locus mutations are compensated for by the presence of pericentromeric chiasmata between homologs or (in the case of their absence) by chromocentral connections between nonhomologs being preserved up to the prometaphase. In the latter case, an interchromosome effect on chromosome disjunction and nonhomologous pairing is registered by genetic methods. Inhibition of the formation of the division spindle fibers during prometaphase of meiosis 1 by the long-term action of colcemide promotes the retention of connections between paired nonexchanged homologs and between nonhomologous chromosomes with abnormal homologous pairing because of heterozygosity for numerous inversions and transpositions (X and autosome 2). These connections are registered cytologically. Cytologically registered are also connections between normal X chromosomes and metacentric compounds by the arms of autosome 2 (C(2L)RM, C(2R)RM), which is the known case of the interchromosome effect on chromosome nondisjunction. It is supposed that cytologically detected associations between compounds are realized through a normal mechanism, as a result of interaction and formation of orienting connections between the homologous pericentromeric regions of these compounds. Cytological evidence is presented for colocation of compounds in the chromocentrally organized nucleus of somatic and germline cells.     

Production and HPLC analysis of black tea theaflavins and thearubigins during in vitro oxidation

A model fermentation system has been designed which utilizes pure catechins and partially purified polyphenol oxidase (EC 1.14.18.1 from green tea shoots. HPLC analysis of the products formed during in vitro oxidation has demonstrated a close similarity between this system and in vivo oxidation occurring during factory fermentation. Furthermore, changes in theaflavin and thearubigin levels, revealed by time courses of fermentation, show in vitro and in vivo systems to be qualitatively similar, although the former system produces considerably higher levels of both components. The model fermentation system, therefore, appears to be a suitable experimental system for studying the formation of theaflavin and thearubigin pigments under strictly controlled conditions. In preliminary experiments the theaflavins have been identified on HPLC profiles by enzymic oxidation of the relevant catechin pairs. Similarly, major coloured components other than theaflavins, which are considered to be thearubigins, have been shown to be formed by the oxidation and reaction of two gallocatechins (epigallocatechin and epigallocatechin gallate). The model fermentation system, in conjunction with HPLC as described in this paper, provides a means whereby precise data on theaflavin and thearubigin formation can be obtained and, in the case of the thearubigins, one which could yield additional structural information.     

Syncytial perforations of human neuronal embryo membranes

An electron microscopy study of the anlage of cerebral cortex of human embryo has been carried with the aim of determining the presence of syncytial interneuronal connections in embryogenesis. It has been determined that, in part of the neurons, the glial embryo is absent and their external cell membranes are directly attached to each other by forming elongated or dotted tight junctions. Sometimes these junctions are perforated and, on their basis, the true syncytial interneuronal connections are formed. Natural structural properties of these connections are the following: formation of the base of tight membrane contacts, obligatory rounding of perforation edges, and the presence of residual particles in the form of spherical vesicles in the lumen of perforations. Results obtained allowed us to conclude that, in the anlage of cerebral cortex of embryos obtained during surgical abortion of pregnancy, apart from the formation of synaptic contacts, or until their formation, there is the possibility of syncytial interneuronal connections appearing. This should be considered during the transplantation of the developing brain.     

Syncytial perforations of human embryo membranes

An electron microscopy study of the anlage of cerebral cortex of human embryo has been carried with the aim of determining the presence of syncytial interneuronal connections in embryogenesis. It has been determined that, in part of the neurons, the glial embryo is absent and their external cell membranes are directly attached to each other by forming elongated or dotted tight junctions. Sometimes these junctions are perforated and, on their basis, the true syncytial interneuronal connections are formed. Natural structural properties of these connections are the following: formation of the base of tight membrane contacts, obligatory rounding of perforation edges, and the presence of residual particles in the form of spherical vesicles in the lumen of perforations. Results obtained allowed us to conclude that, in the anlage of cerebral cortex of embryos obtained during surgical abortion of pregnancy, apart from the formation of synaptic contacts, or until their formation, there is the possibility of syncytial interneuronal connections appearing. This should be considered during the transplantation of the developing brain.     

生命系统中分子间的对应关系

生命系统与非生命系统的差别是认识生命本质的一个重要问题.本文提出了对应关系的概念及总的对应式,认为对应关系是生命系统分子间的基本关系,决定了生命系统的主要性质,是生命系统与非生命系统的重要差别. 对应关系按照分子集合的数量可分为简单对应关系和复杂对应关系. 按照功能的不同可分为对应转换、对应催化、对应转运、对应转导、对应免疫等多种对应关系. 对应关系通过功能上的相互作用还形成了相互协作的具有调控作用的对应关系网络.本文重点介绍了前4种基本的对应关系及相应的对应式,并就对应关系的形成与蛋白质多样性的关系、对生命系统的意义及存在的其它问题进行了初步的讨论.     

Periodical polydeoxynucleotides and DNA curvature

A theoretical method to predict DNA curvature was developed, and a strikingly good correlation between the experimental retardations and theoretical curvature of all the periodical biosynthetic DNAs so far reported in the literature was found. The analysis has been extended to G- and C-rich synthetic polynucleotides, which show a behavior in agreement with the theoretical prediction. A possible application of the method to biologically significant DNA tracts is shown in the case of the regulative region of one of the genes which code for the small subunit of ribulose-1,5-bisphosphate carboxylase in Pisum sativum. While curvature measurements have not so far been reported for this system, biochemical analysis has indicated short nucleotide sequences (boxes I-III) as recognition sites for regulative proteins. On the basis of the theoretical curvature profile of the region and of the electrophoretic retardation measurements of synthetic polynucleotides, obtained by ligating monomers mimicking the boxes, we suggest that the proteins could use DNA local curvature as structural motif in the recognition process.     

Significance of the relative position in space of associated stimuli for formation and performance of motor conditioned reflexes

In experiments on cats the rate of formation of conditioned reflexes to sound (running to the feeding trough) depended on the spatial interrelations of the paired stimuli: the closer the source of the conditioned signal to the feeding trough, the sooner the formation of the conditioned reflex. It has been assumed that during formation of a conditioned reflex the closing of connection between conditioned and unconditioned stimuli is also attended with the closing of connection between the spatial parameters of the paired stimuli. Experiments with inactivation through cold of the temporal area (cortical representation of the vestibular system) of one hemisphere have shown that such a connection is formed in central parts of the vestibular analyser. When the conditioned reflex is elaborated to one feeding trough, the connection is duplicated by both hemispheres; in reflexes to two feeding troughs (i.e. spatial choice) such connections are lateralized in each hemisphere.     

The Role of the Genotype in the Development of the Neurophysiological Mechanisms Involved in the Spatial Integration of Neocortex Bioelectric Activity

The contribution of genetic factors into the formation of the neurophysiological mechanisms determining the systemic organization of cortical activity has been estimated in 12 pairs of monozygotic (MZ) and 5 pairs of dizygotic (DZ) twins (18–25 years of age). The similarity of individual patterns of the spatial interaction of cortical bioelectric activity measured for different combinations of EEG statistical relationships from 16 monopolar leads has been estimated in each pair of twins and in each of the 544 pairs of unrelated subjects in both groups. The results of the study suggest a high population invariance and small genetic and phenotypic variations of the morphofunctional systems constituting the main neurophysiological mechanisms of general cerebral integration. Brainstem and subcortical regulatory structures play the leading role in the integration of different brain regions into an organized system. Apparently, the formation of these structures during ontogeny follows the same general pattern in all individuals, because deviation from it is likely to affect the fundamental monomorphic characters of the species. The formation of neocortical interregional connections may be expected to exhibit greater individual variation, with the roles of hereditary and environmental factors in the formation of long and relatively short intercortical interactions being different. Apparently, the individual variation of the long intra- and interhemispheric fiber pathways forming the specific morphological framework of the neocortex is largely determined by the genotype. However, the intercentral interactions mediated by short corticocortical connections that are formed in the course of the vital activity of an individual are likely to be mainly determined by the external and internal environments.     

Hemo- and lymphomicrocirculatory bed of the broad ligament of the uterus in the presence of collateral circulation

Structural adaptation of the vascular bed in the broad ligament of the dog uterus has been studied at various time of the experimental phlebohypertension. Restitution of the circulation after the posterior vena cava occulsion occurs phasically. The venous collateralies are not formed at one time and it is connected with the venous pressure level in the inferiocaval system and with some changes in the construction of the microcirculatory bed. Basing on the morphometry data, a general equation has been derived which reflects dynamics of the microangiological parameters and demonstrates unidirectionness of the adaptive reactions in the vascular bed at the disturbed venous circulation. Using principles of the system-structural analysis and the mathematical graph theory, we consider the microcirculatory system of the broad ligament of the uterus as a graph-system and study the reorganization of the microcirculatory network at a venous congestion. Realization of the compensatory possibilities is reached in the microcirculatory bed by a changed relationships in the number of the intervascular connections. The latter are estimated according to the graph-schemes of the microvascular bed. Morphokinetics of the connections between the vessels is characterized by widening or narrowing the borders of the "adaptive norm" and by changing the microangioarchitectonics. At the same time, there is noted formation of specialized microhemoangioconstructions. Morphofunctional state of the lymphatic system is connected with reorganization of the angioarchitectonics. This is certain manifestation of the law of the lymphatic and blood beds "synergism". Thus, the structural changes of the vascular bed are aimed to support a certain hemodynamic level.     

Functional Systems and Modular Evolution: The Relationship between Fixation of New Domain Copies and the Present Structure of the Connections in the Functional System

The distribution of paralogous domains in relation to the structure of functional systems (FSs) is examined. It was found that the frequencies of particular domain types in genes for the hemostasis and complement FSs by far exceeded the frequencies expected on assumption of their random distribution in the genome, i.e., the domains were not randomly distributed in relation to the FS boundaries. For instance, it was shown that approximately 50% of the total mRNA of genes for the hemostasis and complement FSs encodes 20 domain types repeated on average 16 (from 2 to 115) times. Thus, the present structure of the FS connections plays a key role in the formation of new connections in the system evolution. Possible causes and mechanisms of the accumulation of paralogous genes and domains in these systems are discussed. The distribution asymmetry may be explained by the systemic character of the organization (system connectivity). Since any structural innovation must be included in the scheme of the present connections, the new protein must contain at least one functional site complementary to sites of the molecules already functioning in the system. The mechanism of preference of own domains probably consists in fixation via selection of the shortest among many alternative possible formation pathways of the new functional structure. This mechanism must promote the accumulation in the FS of copies of already functioning structures (genes, domains) that can relatively rapidly adapt for performing the new function.     

Linear clusters of gold nanoparticles in quasinematic layers of DNA liquid-crystalline dispersion particles

The effects of small size (～2 nm) gold nanoparticles on the properties of particles of cholesteric liquid-crystalline dispersions formed by double-stranded DNA molecules were analyzed. It has been shown that gold nanoparticles induce two different processes. First, they facilitate reorganization of the spatial cholesteric structure of dispersion particles to nematic one. This process is accompanied by the fast decrease in the amplitude of abnormal band in the CD spectrum. Second, they can form ensembles consisting of gold nanoparticles. This process is accompanied by the development and displacement of surface plasmon resonance band in the visible region of the absorption spectrum. The appearance of this band is analyzed by considering two different models of the formation of ensembles consisting of gold nanoparticles. By small-angle X-ray scattering we performed structural analysis of phases formed by DNA cholesteric liquid-crystalline dispersion particles treated with gold nanoparticles. As a result of this study it was possible to prove the formation of linear clusters of gold nanoparticles in the “free space” between the adjacent DNA molecules fixed in the quasinematic layers of liquid-crystalline particles. It has been hypothesized that the formation of linear clusters of gold nanoparticles is most likely related to DNA molecules, ordered in the spatial structure of quasinematic layers, and the toxicity of these nanoparticles in biological systems hypothesized.     

Regulation and restoration of motoneuronal synaptic transmission during neuromuscular regeneration in the pulmonate snail Helisoma trivolvis

Regeneration of motor systems involves reestablishment of central control networks, reinnervation of muscle targets by motoneurons, and reconnection of neuromodulatory circuits. Still, how these processes are integrated as motor function is restored during regeneration remains ill defined. Here, we examined the mechanisms underlying motoneuronal regeneration of neuromuscular synapses related to feeding movements in the pulmonate snail Helisoma trivolvis. Neurons B19 and B110, although activated during different phases of the feeding pattern, innervate similar sets of muscles. However, the percentage of muscle fibers innervated, the efficacy of excitatory junction potentials, and the strength of muscle contractions were different for each cell's specific connections. After peripheral nerve crush, a sequence of transient electrical and chemical connections formed centrally within the buccal ganglia. Neuromuscular synapse regeneration involved a three-phase process: the emergence of spontaneous synaptic transmission (P1), the acquisition of evoked potentials of weak efficacy (P2), and the establishment of functional reinnervation (P3). Differential synaptic efficacy at muscle contacts was recapitulated in cell culture. Differences in motoneuronal presynaptic properties (i.e., quantal content) were the basis of disparate neuromuscular synapse function, suggesting a role for retrograde target influences. We propose a homeostatic model of molluscan motor system regeneration. This model has three restoration events: (1) transient central synaptogenesis during axonal outgrowth, (2) intermotoneuronal inhibitory synaptogenesis during initial neuromuscular synapse formation, and (3) target-dependent regulation of neuromuscular junction formation.     

Competitive interactions of serum protein fractions during complex formation with polycations

Interaction of gamma-globulin with quaternized poly-4-vinylpyridine in water solutions at pH 7 has been studied. Formation of soluble stable cooperative complexes has been observed in a wide range of component ratios. Protein globules are distributed unevenly between adsorbing polycations. Soluble complexes are rod-like particles assembled from the globules which are stabilized by polycation chains. Complex formation in the system gamma-G + PE is similar to that in the system BSA + PE. Competitive interaction of serum protein fractions was studied at the interacting with polycation. It has been shown that selectivity at binding protein fractions is observed in both artificially prepared systems (BSA + gamma-G, beta1-G + gamma-G, BSA + gamma-G + beta1-G), and in serum and whole blood. In those ratios where uneven distribution of protein molecules is observed the soluble complexes protein-PE are formed by separate distribution of individual proteins at the matrix. Decrease of PE concentration in the systems results in the formation of a soluble complex of mixed composition. When an insoluble complex is formed in the system serum-PE selective sorbtion of beta 2-globulin fractions is observed. The reasons for the selective sorbtion of various protein fractions are described, structural models of the soluble complexes protein-PE are suggested.     

Role of protein motions on proton transfer pathways in human carbonic anhydrase II

We report here a theoretical study on the formation of long-range proton transfer pathways in proteins due to side chain conformational fluctuations of amino acid residues and reorganization of interior hydration positions. The proton transfer pathways in such systems may be modeled as fluctuating hydrogen-bonded networks with both short- and long-lived connections between the networked nodes, the latter being formed by polar protein atoms and water molecules. It is known that these fluctuations may extend over several decades of time ranging from a few femtoseconds to a few milliseconds. We have shown in this article how the use of a variety of theoretical methods may be utilized to detect a generic set of pathways and assess the feasibility of forming one or more transient connections. We demonstrate the application of these methods to the enzyme human carbonic anhydrase II and its mutants. Our results reveal several alternative pathways in addition to the one mediated by His-64. We also probe at length the mechanism of key conformational fluctuations contributing to the formation of the detected pathways.     

Structural reorganizations of the lipids and proteins of erythrocyte membranes under the action of low temperatures

The reversible structural rearrangement of lipids and protein oligomerization has been shown to occur during cooling in membranes of model systems (liposome, erythrocyte shadows) and native erythrocytes. Analysing the dependence of Azz in membrane probes (5- or 15-doxylstearic acids) in the Arrhenius plots a conclusion on the structural changes at 13-19 degrees C and within the range of interior water freezing from -17 up to -19 degrees C has been drawn, the last transition is smoothed out in the presence of glycerin. Using diamide joining spectrin and electrophoresis in polyacrylamide gel it has been determined that the low temperatures cause the spatial approach of proteins of spectrin-actinic complex and formation connections between the erythrocyte membrane proteins which aren't destroyed by dodecylsulfate.     

Molecular dynamic simulation studies on the effect of one residue chain staggering on the structure and stability of heterotrimeric collagen-like peptides with interruption

A systematic molecular dynamics (MD) simulation has been carried out on collagen-like peptides with different combinations of interruptions in the Gly-X(AA) -Y(AA) repeats. Although experimental studies have been carried out to elucidate the structural consequences of homotrimeric collagen-like peptides, this is the first report on the structural effect on the heterotrimeric models with G4G and G1G breaks present simultaneously in the constituent chains with difference in one residue chain staggering. The results reveal that the axial registry of the interrupted region changes significantly from that of conventional triple helical peptide without interruption. Further, results from MD simulations show the formation of a kink in the interrupted region of the triple-helical peptides. The conformational analysis reveals that the interruption in the Gly-X(AA) -Y(AA) pattern in these peptides induces β-strand conformation in triple helical peptides. The conventional hydrogen bonds in the interrupted triad are affected and new nonconventional H-bonds are formed in the triple helical structure, and as a result interrupted region becomes locally fragile. MM-PBSA calculations on the different systems clearly suggest that the binding affinity varies marginally due to one residue staggering. However, it is found from the structural parameters that hydrogen-bonding pattern differs significantly due to the difference in the staggering of chains.