A new form of structural lipoprotein of outer membrane of Escherichia coli.

Among the membrane proteins synthesized in toluene-treated cells of Escherichia coli were two distinct membrane proteins of different molecular weights, which were cross-reactive with antiserum against a structural lipoprotein of the outer membrane. One was thought to be the known membrane lipoprotein since it migrated to the same position as that of the lipoprotein (Mr = 7,200) in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, the other protein migrated slower than the lipoprotein. No protein corresponding to the slower-migrating species was detected in the membrane proteins synthesized in vivo. The apparent molecular weight of the protein at the new peak was estimated to be between 10,000 and 15,000. Both the new protein and the lipoprotein were found to be synthesized from stable mRNA(s) in the toluene-treated cells. The synthesis of the new protein as well as the lipoprotein was sensitive to chloramphenicol, indicating that both proteins were synthesized on ribosomes. Peptides mapping of the new protein revealed the same COOH-terminal sequence as in the lipoprotein. This indicates that the new protein has an extra sequence at the NH2-terminal end. This hypothesis is supported by the finding that the NH2 terminus of the new lipoprotein is methionine, while that of the lipoprotein is a substituted cysteine. From double label experiments with each of 17 different amino acids and arginine, the amino acid composition of the extra region was deduced. The new protein was found to contain at least 18 to 19 extra amino acid residues over the lipoprotein, if it is assumed that the new protein has no extra arginine residues. It was found that 4 out of the 5 amino acids which were deficient in the lipoprotein (phenylalanine, tryptophan, proline, and histidine) were also deficient in the new protein, but the fifth one, glycine, was present in the new protein. From these results, it seems possible that this new form of the lipoprotine is a precursor of the lipoprotein (prolipoprotein) in the process of biosynthesis and assembly of the lipoprotein in the outer membrane.     

Changing the specificity of a bacterial chemoreceptor

The methyl-accepting chemotaxis proteins are a family of receptors in bacteria that mediate chemotaxis to diverse signals. To explore the plasticity of these proteins, we have developed a simple method for selecting cells that swim to target attractants. The procedure is based on establishing a diffusive gradient in semi-soft agar plates and does not require that the attractant be metabolized or degraded. We have applied this method to select for variants of the Escherichia coli aspartate receptor, Tar, that have a new or improved response to different amino acids. We found that Tar can be readily mutated to respond to new chemical signals. However, the overall change in specificity depended on the target compound. A Tar variant that could detect cysteic acid still showed a strong sensitivity to aspartate, indicating that the new receptor had a broadened specificity relative to wild-type Tar. Tar variants that responded to phenylalanine or N-methyl aspartate, or that had an increased sensitivity to glutamate showed a strong decrease in their response to aspartate. In at least some of the cases, the maximal level of sensitivity that was obtained could not be attributed solely to substitutions within the binding pocket. The new tar alleles and the techniques described here provide a new approach for exploring the relationship between ligand binding and signal transduction by chemoreceptors and for engineering new receptors for applications in biotechnology.     

Molecular mechanisms of macroevolution

The present paper is devoted to the evolutionary role of genetic modules shuffing. The mechanisms capable to produce new molecular functions and significant complications of ontogenesis are reviewed. Two-step model of macroevolution is proposed. This model comprises: (1) Arising of a new combination of genetic modules. This step does not result in formation of a new taxon but makes necessary ground for that process. (2) Precise structure completing of the new combination of modules and corresponding genome optimization by use of various mechanisms including point mutations. This step concerns many genes and finally leads to formation of a new taxon. It is shown that arising of new combinations of genetic modules might work out as molecular basis for progressive evolution, while alternative structural completing of the same combination might result in adaptive radiation.     

The evolutionary genetics of emerging plant RNA viruses

Over the years, agriculture across the world has been compromised by a succession of devastating epidemics caused by new viruses that spilled over from reservoir species or by new variants of classic viruses that acquired new virulence factors or changed their epidemiological patterns. Viral emergence is usually associated with ecological change or with agronomical practices bringing together reservoirs and crop species. The complete picture is, however, much more complex, and results from an evolutionary process in which the main players are ecological factors, viruses' genetic plasticity, and host factors required for virus replication, all mixed with a good measure of stochasticity. The present review puts emergence of plant RNA viruses into the framework of evolutionary genetics, stressing that viral emergence begins with a stochastic process that involves the transmission of a preexisting viral strain into a new host species, followed by adaptation to the new host.     

The reality of the higher taxonomic categories

A higher category is the result of a population's breaking-throuh into a new adaptive zone (attaining a new grade), and the subsequent adaptive radiation tiere. The taxonomic level of the new group is determined by the amount (quantitative and ualitative) of radiation that occurs; and tgis amount in turn is determined by the number of open sub-zones in the new zone and by the genetic plasticity of the new population. The more the new adaptive zone differs from the old one, the less likely a new population can survive in it. Should such survival occur, however, adaptations of the new population to the new zone will appear quickly. The new population will rapidly become quite different from the old one, minimizing the likelihood of finding intermediate forms, i. e., “missing links.” In addition, the intermediate population – the early entrants into the new zone – will be less well adapted to it than their descendents, and will become extinct. The combination of rapid extinction and an ephemeral transitional population explains the apparent gaps between higher-category taxa. These ideas do not help in solving such dilemmas of taxonomists as equivalence of taxa in different groups, and the taxonomic level at which to place a given group of species. But a higher taxonomic category itself is the result of a very real biological phenomenon, and that fact must influence systematicists.     

Delayed degradation of parental macronuclear DNA in programmed nuclear death of Paramecium caudatum

In the ciliated protozoan Paramecium caudatum, a parental macronucleus that is fragmented into some 40-50 pieces during conjugation does not degenerate immediately, but persists until the eighth cell cycle after conjugation. Here we demonstrate that the initiation of the parental macronuclear degeneration occurs at about the fifth cell cycle. The size of parental macronuclear fragments continued to increase between the first and fourth cell cycle, but gradually decreased thereafter. By contrast, a new macronucleus grew and reached a maximum size by the fourth cell cycle, suggesting that the new macronucleus matured by that stage. Southern blot analysis revealed that parental macronuclear DNA was degraded at about the fifth cell cycle. The degradation was supported by acridine orange staining, indicating degeneration of the macronuclear fragments. Prior to the degradation, the fragments once attached to the new macronucleus were subsequently liberated from it. These observations lead us to conclude that once a new macronucleus has been fully formed by the fourth cell cycle, the parental macronuclear fragments are destined to degenerate, probably through direction by new macronucleus. Considering the long persistence of the parental macronucleus during the early cell cycles after conjugation, the macronuclear fragments might function in the maturation of the imperfect new macronucleus. Two possible functions, a gene dosage compensation and adjustment of ploidy level, are discussed.     

Statistical Computations Underlying the Dynamics of Memory Updating

Psychophysical and neurophysiological studies have suggested that memory is not simply a carbon copy of our experience: Memories are modified or new memories are formed depending on the dynamic structure of our experience, and specifically, on how gradually or abruptly the world changes. We present a statistical theory of memory formation in a dynamic environment, based on a nonparametric generalization of the switching Kalman filter. We show that this theory can qualitatively account for several psychophysical and neural phenomena, and present results of a new visual memory experiment aimed at testing the theory directly. Our experimental findings suggest that humans can use temporal discontinuities in the structure of the environment to determine when to form new memory traces. The statistical perspective we offer provides a coherent account of the conditions under which new experience is integrated into an old memory versus forming a new memory, and shows that memory formation depends on inferences about the underlying structure of our experience.     

A general version of optimal foraging theory: The effect of simultaneous encounters

Optimal foraging theory is extended so as to treat cases where a choice between several options is required. A new version of optimal foraging theory is derived under this assumption of simultaneous encounters of prey species and proved by using a set-theoretic approach. On the basis of this new version, it is demonstrated that, in general, no unique ranking of food types can be specified only from knowledge of the intrinsic properties of the food types. It is demonstrated that a food type may become less frequent in the diet as a result of becoming more abundant in the environment; that an increase in the abundance of a food type represented in the diet may have the effect that new food types enter the diet; and that an increase in the overall food abundance may imply that new types are included and/or old ones are excluded.     

New target for inhibition of bacterial RNA polymerase: 'switch region'

A new drug target - the 'switch region' - has been identified within bacterial RNA polymerase (RNAP), the enzyme that mediates bacterial RNA synthesis. The new target serves as the binding site for compounds that inhibit bacterial RNA synthesis and kill bacteria. Since the new target is present in most bacterial species, compounds that bind to the new target are active against a broad spectrum of bacterial species. Since the new target is different from targets of other antibacterial agents, compounds that bind to the new target are not cross-resistant with other antibacterial agents. Four antibiotics that function through the new target have been identified: myxopyronin, corallopyronin, ripostatin, and lipiarmycin. This review summarizes the switch region, switch-region inhibitors, and implications for antibacterial drug discovery.     

The role of competition in creating multiple steady states and favouring evolution of prebiotic polymers

In a prebiotic context the assumption is made that a mutation leads to the formation of a new polymer displaying autocatalytic and cross-catalytic properties. By the use of a simple chemical model it is shown that, despite these favourable attributes, the new species either remains at low concentration or accumulates, unless a competition is imposed between the new polymer and its precursor. In the latter case, the well-known situation of multiple steady states and hysteresis is established and the new “improved” species, under specific conditions, may become the dominant one. The need of competition suggests an early compartmentation of the system.     

Synthesis and vasorelaxant activity of new coumarin and furocoumarin derivatives

We have synthesized a new series of coumarins and furocoumarins and evaluated their vasorelaxant activity in rat aorta rings pre-contracted with noradrenaline or by depolarisation with high KCl. The new furocoumarins relax smooth vascular muscle with a profile similar to that of khellin (a furochromone that directly relaxes smooth muscle) and at a greater potency, suggesting that these compounds have a potential interest for the development of new and more efficient vasodilator drugs.     

The Child on the Threshold of Becoming a Pupil

The functions of a preschooler's imagination that are required for a child to become immersed in the new social situation of development that characterizes the beginning of the early school ages are analyzed. The new social situation of development consists, above all, of new forms of interaction for the child with adults and other children within new primary activity—education. Imagination is viewed as a condition for the development of interaction during the older preschool ages based on a number of important indicators—the degree of development of social-communication skills and communicative competence—that underlie the “social component” of school readiness.     

On prediction of genetic values in marker-assisted selection.

We suggest a new approximation for the prediction of genetic values in marker-assisted selection. The new approximation is compared to the standard approach. It is shown that the new approach will often provide substantially better prediction of genetic values; furthermore the new approximation avoids some of the known statistical problems of the standard approach. The advantages of the new approach are illustrated by a simulation study in which the new approximation outperforms both the standard approach and phenotypic selection.     

航天与辐射共诱变在水稻育种中的应用

利用航天诱变与辐射诱变相结合的方法进行水稻新种质、新品种的选育,显著地提高其突变频率和突变类型,提高诱变育种的选择效果,育成1个两系杂交水稻新组合“培两优721”及一批优质水稻新种质和新品系(组合)。     

中国神农架蜡梅属一新变种和新变型

描述了蜡梅（Chimonanthus praecox L.）一新变种即卷瓣蜡梅,该变种与原变种的主要区别是中花被片高度反卷,中被片颜色为白色或金黄色,主要分布于神农架林区。其中中被片颜色为白色的卷瓣蜡梅可以被看作一个新变型跳枝蜡梅。     

Metagenomics for mining new genetic resources of microbial communities

Recent progress has revealed that the capture of genetic resources of complex microbial communities in metagenome libraries allows the discovery of a richness of new enzymatic diversity that had not previously been imagined. Activity-based screening of such libraries has demonstrated that this new diversity is not simply variations on known sequence themes, but rather the existence of entirely new sequence classes and novel functionalities. This new diversity, the surface of which has thus far only been scratched, constitutes potential for a wealth of new and improved applications in industry, medicine, agriculture, etc., and promises to facilitate in a significant manner our transition to a sustainable society, by contributing to the transition to renewable sources of energy, chemicals and materials, the lowering of pollutant burdens, lower processes energies, etc. Current bottlenecks in metagenomics include insufficient functional characterization and amplifying non-validated annotations of proteins in databases.     

Cloning and characterization of the gene encoding the z66 antigen of Salmonella enterica serovar Typhi

Z66 antigen-positive strains of Salmonella enterica serovar Typhi change flagellin expression in only one direction from the z66 antigen to the d or j antigen, which is different from the phase variation of S. enterica serovar Typhimurium. In the present study, we identified a new flagellin gene in z66 antigen-positive strains of S. enterica serovar Typhi. The genomic structure of the region containing this new flagellin gene was similar to that of fljBA operon of biphasic S. enterica serovars. A fljA-like gene was present downstream of the new flagellin gene. A rho-independent terminator was located between the new flagellin gene and the fljA-like gene. Hin-like gene was not present upstream of the new flagellin gene. We generated a mutant strain of S. enterica serovar Typhi, which carries a deletion of the new flagellin gene. Western blotting revealed that the 51-kDa z66 antigen protein was absent from the population of proteins secreted by the mutant strain. Southern hybridization demonstrated that the z66 antigen-positive strains of S. enterica serovar Typhi carried the new flagellin gene and fliC on two different genomic EcoRI fragments. When z66 antigen-positive strains were incubated with anti-z66 antiserum, the flagellin expression by S. enterica serovar Typhi changed from z66 antigen to j antigen. The new flagellin gene and the fljA-like gene were absent in the strain with altered flagellin expression. These results suggested that the new flagellin gene is a fljB-like gene, which encodes the z66 antigen of S. enterica serovar Typhi, and that deletion of fljBA-like operon may explain why S. enterica serovar Typhi alters the flagellin expression in only one direction from the z66 antigen to the d or j antigen.     

Formation of a new type of dinitrosyl iron complexes bound to cysteine modified with methylglyoxal

It has been shown that interaction of cysteine dinitrosyl iron complexes with methylglyoxal leads to the formation of a new type of dinitrosyl iron complexes, EPR spectrum of these complexes essentially differs from spectra of dinitrosyl iron complexes containing unmodified thiol. The products of the cysteine reaction with methylglyoxal are hemithioacetals, Schiff bases and thiazolidines, which most likely serve as ligands for the new type of dinitrosyl iron complexes. It has been shown that the new type of dinitrosyl iron complexes as cysteine dinitrosyl iron complexes, which are physiological donors of nitric oxide, exert a vasodilator effect. It has also been found that the oxidative destruction of the new type of dinitrosyl iron complexes occurs at normal oxygen partial pressure, but these dinitrosyl iron complexes remain rather stable under hypoxia modeling. An assumption that the destruction of the new type of dinitrosyl iron complexes is caused by the formation of a bound peroxynitrite-containing intermediate is made.     

Analysis of large gene databases for discovery of novel therapeutic agents

During the 1980s and early 1990s the recombinant DNA revolution provided a vital source of therapeutic targets and agents for pharmaceutical research. However, during the early 1990s, it became apparent that the identification and cloning of novel human cDNAs was a rate limiting step in drug discovery and that new technological approaches were required to address the challenge. There was an increasing realisation that the new science of 'genomics', together with the associated large gene sequence databases, would provide a radically new means of generating targets. SmithKline Beecham has been at the forefront of this breakthrough in pharmaceutical research. The productivity of this strategy is illustrated by reference to our work on novel enzymes, chemokines and receptors and new approaches linking genes to pathological processes.     

Orientation of comb building by honeybees

Summary Upon entering a new home site a honeybee swarm is faced with the task of organizing the building activities of thousands of component bees so that several straight and parallel vertically oriented combs can be quickly and efficiently built. As a part of this organization process it is necessary for the bees to select and agree upon a planar orientation for the new combs.This paper presents evidence that memory of a previously used comb direction influences the building of the new set of combs. Swarms which have recently moved into bait-hives (empty boxes placed in trees to attract feral swarms) tend to maintain the previously used comb direction when removed and forced to build new combs, whereas swarms which have occupied the bait-hives for a longer period (over 9 days) do not.Recent swarms predictably alter their comb building direction within the influence of an applied earthstrength magnetic field, indicating that honey bees are able to use the earth's magnetic field as a reference at the commencement of comb construction in a new hive.