Polysystemic assessment of the state of sanogenesis in workers employed in nuclear fuel plants. The analysis of functional state of cardiovascular, respiratory, and psychomotor systems

The state of the cardiovascular, respiratory, and psychomotor systems of workers employed in nuclear fuel plant was evaluated using a computer-assisted laboratory complex. It was found that neuroendocrine regulation of the peripheral circulation and muscular activity responsible for fine motions are most vulnerable to industrial hazardous factors.     

植物细胞核与叶绿体基因的双向调控作用

在长期进化过程中,叶绿体与细胞核已形成高度适应性。在分子水平上,两者的基因表达存在着复杂的双向调控作用。细胞核的众多基因对叶绿体基因的转录、转录后加工以及翻译等过程发挥着普遍的调节作用,而叶绿体通过四吡咯信号以及自身氧化还原状态的改变调控着细胞核基因的表达。双向调节方式的存在从分子水平上说明了细胞核与叶绿体在功能上的相互适应。然而,细胞核与叶绿体基因表达双向调控的详细机制还有待研究。     

Phytochrome regulation of nuclear gene expression in plants

The photoregulation of gene expression in higher plants was extensively studied during the 1980s, in particular the light-responsive cis -acting elements and trans -acting factors of the Lhcb and rbcS genes. However, little has been discovered about: (1) which plant genes are regulated by light, and (2) which photoreceptors control the expression of these genes. In the 1990s, the functional analysis of the various photoreceptors has progressed rapidly using photoreceptor-deficient mutants, including those of the phytochrome gene family. More recently however, advanced techniques for gene expression analysis, such as fluorescent differential display and DNA microarray technology, have become available enabling the global identification of genes that are regulated by particular photoreceptors. In this paper we describe distinct and overlapping effects of individual phytochromes on gene expression in Arabidopsis thaliana.     

Ethylene and the regulation of senescence processes in transgenic Nicotiana sylvestris plants

BACKGROUND AND AIMS: Exposure of plants to ethylene can influence a spectrum of developmental processes including organ senescence and abscission. The aim of this study was to examine the role of the gaseous regulator in Nicotiana sylvestris plants exhibiting a silenced or constitutive ethylene response. METHODS: Transgenic N. sylvestris plants were generated that either ectopically expressed the Arabidopsis mutant ethylene receptor ETR1-1 or the tomato EIN3-like (LeEIL1) gene. Highly expressing homozygous lines were selected and the time-course of development, from germination to organ senescence, was studied. KEY RESULTS: Fifty percent of the homozygous Pro(35S):ETR1-1 lines examined showed a high susceptibility to collapse prior to flowering, with plant death occurring within a few days of leaf wilting. The time-course of leaf senescence in the remaining Pro(35S):ETR1-1 lines was visibly arrested compared to wild type (negative segregant) plants and this observation was reaffirmed by chlorophyll and protein analysis. Petal necrosis was also delayed in Pro(35S):ETR1-1 lines and corolla abscission did not take place. When senescence of Pro(35S):ETR1-1 plants did take place this was accompanied by leaf bleaching, but tissues remained fully turgid and showed no signs of collapse. A single Pro(35S):LeEIL1 line was found to exhibit consistently accelerated leaf and flower senescence and precocious flower bud shedding. CONCLUSIONS: These observations support a role for ethylene in regulating a spectrum of developmental events associated with organ senescence and tissue necrosis. Furthermore, the transgenic lines generated during this study may provide a valuable resource for exploring how senescence processes are regulated in plants.     

Recent developments in understanding the regulation of starch metabolism in higher plants

This article reviews current knowledge of starch metabolism in higher plants, and focuses on the control and regulation of the biosynthetic and degradative pathways. The major elements comprising the synthetic and degradative pathways in plastids are discussed, and show that, despite present knowledge of the core reactions within each pathway, understanding of how these individual reactions are co-ordinated within different plastid types and under different environmental conditions, is far from complete. In particular, recently discovered aspects of the fine control of starch metabolism are discussed, which indicate that a number of key reactions are controlled by post-translational modifications of enzymes, including redox modulation and protein phosphorylation. In some cases, enzymes of the pathway may form protein complexes with specific functional significance. It is suggested that some of the newly discovered aspects of fine control of the biosynthetic pathway may well apply to many other proteins which are directly and indirectly involved in polymer synthesis and degradation.     

Autophagic processes in plants: mechanisms, regulation and function

Large numbers of publications investigating the molecular details, the regulation and the physiological roles of autophagic processes have appeared over the last few years, dealing with animals, plants and unicellular eukaryotic organisms. This strong interest is caused by the fact that autophagic processes are ubiquitous in eukaryotic organisms. They are involved in the adaptation of organisms to their environment and to stressful conditions, thereby contributing to cell and organism survival and longevity. This review article aims to describe the discovery of autophagy, the molecular details of this complex process, its regulation, and its specific functions in plants.     

A new approach to analysis of participation of oxidative processes in regulation of metabolism in animal tissues

A new approach to the analysis of the oxidative processes participated in regulation of metabolism in norm and the assessment of the biological consequences under the action of damaging factors of different nature and intensity for animal groups is suggested using the analysis of interrelations between the different parameters of the physicochemical regulatory system of the lipid peroxidation in tissues of the laboratory mice (the phospholipid composition, amounts of the oxidation products in lipids) by changes of the scale and direction of interrelations between the reciprocal parameters of the lipid peroxidation system in norm.     

The distribution of 5-methylcytosine in the nuclear genome of plants.

We have determined the 5-methylcytosine (5mC) content in high molecular weight DNA, from two dicot (tobacco and pea) and two monocot (wheat and maize) plant species, fractionated according to base composition. The results show that the proportion of 5mC in the genomic fractions increases linearly with their guanine + cytosine (G + C) content while the proportion of non-methylated cytosine remains almost constant. This can be interpreted as a consequence of a difference in mutation pressure related to spontaneous deamination of 5mC to thymine between the different compartments of plant genomes.     

Glycophorin A mutant frequency in radiation workers at the nuclear power plants and a hospital

We studied to assess the validity of the glycophorin A (GPA) mutant assay as a biological marker of the cumulative effects of chronic low doses of ionizing radiation. In 144 nuclear power plants workers and 32 hospital workers, information on confounding factors, such as age and cigarette smoking, was obtained through a self-administered questionnaire. The information on physical exposure doses was obtained from the registries for radiation exposure monitoring and control at each facility. The range of cumulative exposure doses were 0-12.02cGy. GPA mutant assay was performed by the BR6 method with modification using a FACScan flow cytometer. Potential confounders, such as, age and cigarette smoking habits showed increasing trends with GPA variants, but were not of statistical significance. The hospital workers showed higher frequency of the GPA NO variant than nuclear power plant workers. Significant dose-response relationships were found between cumulative exposure to radiation and variants levels by simple and multiple linear regression models. The slope of regression equation of the dose-response of nuclear power plants workers was much smaller than that of hospital workers. These findings suggest that there may be dose-rate effects. In a population exposed to chronic low-dose radiation, the GPA assay shows potential to be used as an effective biologic marker for assessing the cumulative exposure dose although it could not be able to see a dose relation below 10cGy of cumulative exposure dose.     

Roles for inositol polyphosphate kinases in the regulation of nuclear processes and developmental biology

Our laboratory studies the biology and enzyme regulation of inositol signal transduction pathways, which are activated in response to a wide range of stimuli. As a six-carbon cyclitol, inositol and its numerous phosphorylated derivatives efficiently generate combinatorial ensembles of signaling molecules. Through the cloning and characterization of inositol polyphosphate kinases (IPK), novel roles for inositol tetrakisphosphate (IP₄), inositol pentakisphosphate (IP₅), and inositol hexakisphosphate (IP₆) and inositol pyrophosphates (PP-IPs), have been identified. Studies have linked the IPKs and their inositide products to the regulation of nuclear processes including gene expression, chromatin remodeling, mRNA export, DNA repair and telomere maintenance. Analysis of IPK knockout animals has revealed a role for production of IPs in regulation of embryogenesis and organism development.The discoveries of the IPK proteins and their connection to nuclear signaling have generated significant interest in the field. Furthermore, they have provided interesting clues into the evolution of inositide-signaling pathways. Ipk2/IPMK and IPS/IP6K family members are conserved from yeast to man. In contrast, the IP₃ 3-kinase (ITPK) branch is observed in selected metazoans and not in plant or fungi. This may imply that Ipk2 and IPS activities evolved first among the group. The promiscuity of the Ipk2 protein further supports this notion and may provide the cell with a means to generate many IP species in a genetically economical fashion. Studies of yeast inositide signaling reveal that these simple eukaryotes do not have an IP₃ receptor in their genome and do not utilize diacylglycerol to activate protein kinase C. Thus, it appears that the canonical “text book” aspects of inositide-signaling pathways are not conserved throughout eukaryotic evolution. In light of the conservation of Ipk2/IPMK, Ipk1 and IPS/IP6K pathways from yeast to man it is interesting to speculate that a primordial role of phospholipase C-induced, IPK-dependent inositide signaling was to regulate nuclear processes. As calcium and PKC signaling evolved in metazoans, these may have greatly enhanced signaling capabilities. Recent studies demonstrating an essential role for IP₅, IP₆ and possibly PP-IP production in metazoan development highlight the importance of IPK signaling in cellular responses in metazoans. With these thoughts in mind, we eagerly await future studies aimed at further elucidating how these signaling codes participate in developmental processes and the control of gene expression, mRNA export, and DNA metabolism.