Age dependent changes in enzymes involved in macromolecular synthesis in Turbatrix aceti.

The specific activities of elongation factor 1, RNA and DNA polymerase, as well as fructose-1,6-diphosphate aldolase were determined as a function of age in the nematode Turbatrix aceti. It was found that the specific activities of both DNA polymerase and aldolase declined constantly as the animal aged. In contrast, both elongation factor 1 and RNA polymerase showed sharp increases in their specific activities at 5 and 15 days, respectively, before ultimately declining. It was also shown that elongation factor 1, which exists mainly as a high molecular weight species in the young animal, undergoes a conversion to a lower molecular weight species as the organism ages. In addition there is a progressive accumulation of inactive or partially active elongation factor 1 molecules in older animals. The addition of α-tocopherol to the growth medium of these nematodes resulted in an increased life-span as well as alterations in the patterns of the enzyme activities.     

Cycloheximide genotoxicity in in vitro and in vivo test systems

The aim of this study was to investigate if there was any genotoxic effect produced by the antibiotic cycloheximide, widely used as a fungicide in agriculture as well as in everyday laboratory practice. The battery of test systems included the bacterium Salmonella typhimurium (strains TA98 and TA100), the yeast Saccharomyces cerevisiae (D7), Allium cepa somatic cells and mouse bone marrow cells. This combination of test systems enabled us to establish possible effects caused by cycloheximide at different levels of the genome and to indicate a possible mechanism of action. The results obtained in experiments showed that cycloheximide did not induce frameshift or base-pair substitution mutations in S. typhimurium regardless of metabolic activation. In S. cerevisiae cycloheximide had only toxic effects but no increase of mitotic gene conversion was noticed under the conditions of the experiment. However, in A. cepa somatic cells as well as in mouse bone marrow cells cycloheximide showed its activity causing different genetic damages, e.g., chromosome breaks, mitotic disturbances and nuclear abnormalities.     

Seed Rain in High-Altitude Restoration Plots in Switzerland

Seed rain was studied in restoration plots installed in 1985 and 1987, respectively, on an alpine downhill ski run at circa 2,500 m above sea level. The study was initiated in late autumn 1996 and completed in autumn 1998; it included temporal and spatial variation in density per m², as well as alpha diversity (species richness), and species composition of the seed rain versus that of the resident vegetation. This is the first report on post-restoration monitoring of seed rain above the timberline. Seed rain density and alpha diversity varied seasonally, with the first peak occurring immediately after spring snowmelt and the second in early autumn. The density of seed rain varied between plots and years (1,528–1,778 seeds per m² in one plot [RPF] versus 1,096–3,557 seeds per m² in another plot [RPG]). Total species number per plot was nearly twice as high in RPF as in RPG in both study years. Seed rain totaled 18 species; all but one represented either transplants introduced in restoration or colonizers established in the plots soon after restoration. Distribution of species in seed rain was largely asymmetric and only a few species provided substantial contributions. Composition of species and their respective contribution to seed rain differed between plots and was clearly influenced by performance of some species used in restoration as transplants; together they provided as much as 51% of the total seed rain. The results of the study demonstrate that restoration enhanced increase of species richness as well as seed rain in situ.     

Changes in nonhistone chromosomal proteins in phytohemagglutininstimulated lymphocytes

Stimulation of bovine lymphocytes with phytohemagglutinin results in quantitative as well as qualitative changes in the nonhistone chromosomal proteins. Analysis of these proteins by hydroxyapatite chromatography and sodium dodecylsulfate polyacrylamide gel electrophoresis shows not only a selective increase in the amount of some nonhistone proteins but also a decrease of other nonhistone protein bands. This observation is compatible with the view that nonhistone proteins have an inhibitory as well as an activating function at the genome level.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义.综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望.     

Age-related changes in the mevalonate metabolism in vivo in chick kidneys

The mevalonate incorporation in vivo into total nonsaponifiable lipids by chick kidneys drastically increased after hatching, reaching similar levels to those previously observed in liver. Cholesterol was the major sterol formed from mevalonate from 11 days onward, while a fraction of polar nonsaponifiable lipid(s) was observed as the major compound(s) synthesized at 5-8 days. Relative percentages of squalene, squalene oxide(s) and lanosterol synthesized from mevalonate also increased between 11-18 days after hatching. Results in this paper demonstrate for the first time the accumulation of a fraction of nonsaponifiable lipid(s) identified as lanosterol derivatives and cholesterol precursors formed by kidneys from [5-14C]mevalonate in experiments carried out in vivo, as well as their evolution during postnatal period.     

Adriamycin depresses in vivo and in vitro phosphatidylethanolamine N-methylation in rat heart sarcolemma

Adriamycin, an effective anticancer chemotherapeutic agent, causes an insidious and delayed cardiotoxicity. Different subcellular abnormalities including calcium transport changes in the sarcolemma (SL) as well as downregulation of the adrenergic system have been shown to be associated with the development of this cardiomyopathy. Since both of these activities are influenced by phospholipid methylation, effects of adriamycin on the three catalytic sites of SL phosphatidylethanolamine N-methyltransferase were examined. Rats were administered with a cumulative dose of adriamycin (15 mg/kg) over 2 weeks and examined after 3 weeks. Vehicle injected animals served as controls. Dyspnea, high mortality rate, ascites and decrease in aortic and left ventricular systolic pressure, as well as increase in left ventricular end diastolic pressure were seen in the adriamycin group. Myocardial cell damage typical of adriamycin cardiomyopathy, i.e. sarcotubular swelling, vacuolization and myofibrillar drop-out, was also apparent. Total methyl group incorporation into SL phosphatidylethanolamine using radiolabeled S-adenosyl-L-methionine as the donor was significantly depressed in the 3 week group at catalytic sites II and III. Decreased production of methylated intermediates, phosphatidyl-N-monomethylethanolamine and phosphatidyl-N,N-dimethylethanolamine as well as phosphatidylcholine (PC) was seen. Depression of phosphatidylethanolamine N-methylation was also noticed when SL, isolated from untreated hearts, was exposed in vitro to different concentrations (10, 100 and 1000 µM) of adriamycin. Inhibition of phosphatidylethanolamine N-methylation appears to be mediated by adriamycin-induced increase in the oxidative stress and may contribute in the pathogenesis of subcellular changes associated with this cardiomyopathy.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。     

DNA fragmentation in microorganisms assessed in situ

Chromosomal DNA fragmentation may be a direct or indirect outcome of cell death. Unlike DNA fragmentation in higher eukaryotic cells, DNA fragmentation in microorganisms is rarely studied. We report an adaptation of a diffusion-based assay, developed as a kit, which allows for simple and rapid discrimination of bacteria with fragmented DNA. Intact cells were embedded in an agarose microgel on a slide, incubated in a lysis buffer to partially remove the cell walls, membranes, and proteins, and then stained with a DNA fluorochrome, SYBR Gold. Identifying cells with fragmented DNA uses peripheral diffusion of DNA fragments. Cells without DNA fragmentation show only limited spreading of DNA fiber loops. These results have been seen in several gram-negative and gram-positive bacteria, as well as in yeasts. Detection of DNA fragmentation was confirmed by fluoroquinolone treatment and by DNA breakage detection-fluorescence in situ hybridization. Proteus mirabilis with spontaneously fragmented DNA during exponential and stationary growth or Escherichia coli with DNA damaged after exposure to hydrogen peroxide or antibiotics, such as ciprofloxacin or ampicillin, was clearly detected. Similarly, fragmented DNA was detected in Saccharomyces cerevisiae after amphotericin B treatment. Our assay may be useful for the simple and rapid evaluation of DNA damage and repair as well as cell death, either spontaneous or induced by exogenous stimuli, including antimicrobial agents or environmental conditions.     

Viral-bacterial-fungal associations in chronic tonsillitis in children

The microflora of palatal tonsils was studied in 84 children with chronic tonsillitis in comparison with that in the control group of 38 healthy children. In most of the sick children viral-bacterial and less frequently viral-bacterial-fungal associations were detected with the prevalence of reo- and adenoviruses, Epstein-Barr viruses, coagulase negative staphylococci and Staphylococcus aureus, as well as peptostreptococci. Adhesive activity and persistence factors among the main bacterial pathogens were shown to be widely prevalent. The depth of the lesion of tonsillar tissue by the infective agents of bacterial and fungal nature, as well as their persistence potential, depended on the taxonomic position of these microorganisms.     

Autophagy in immunity

Autophagy is now emerging as a spotlight in trafficking events that activate innate and adaptive immunity. It facilitates innate pathogen detection and antigen presentation, as well as pathogen clearance and lymphocyte homeostasis. In this review, we first summarize new insights into its functions in immunity, which underlie its associations with autoimmunity. As some lines of evidence are emerging to support its role in autoimmune and autoinflammatory diseases, we further discuss whether and how it affects autoimmune diseases including systemic lupus erythematosus, rheumatoid arthritis, diabetes mellitus and multiple sclerosis, as well as autoinflammatory diseases, such as Crohn disease and vitiligo.     

Role of microbial enzymes in flavor development in foods

There are four main sources of enzymes in foods—these being the inherent enzymes, enzymes from microbial contaminants, enzymes elaborated by microorganisms added to foods, and specific enzymes added to foods. This study primarily deals with the latter two sources of enzymes in food. Although both plants and animals serve as sources of enzymes, they are not as economical or versatile sources as are enzymes obtained from microorganisms. In the meat industry, proteases are used to tenderize muscle and to obtain flavor precursors. In the preparation of cured meat products such as sausages, lipases, and proteases from bacterial cultures are utilized. Similarly, proteases and lipases are used in the dairy industry to develop flavor compounds. Proteases and amylases also have applications in the baking and milling industries where they are used to produce precursors for the nonenzymatic browning reactions. Carbohydrases such as amylase, amyloglucosidase, and glucose isomerase have found usage in the starch and syrup industry for the production of high dextrose and high fructose syrups. Other enzymes such as glucose oxidase, pectinase, and naringinase are of value to the wine and fruit juice industries. A better understanding of the mode of action of enzymes as well as the mechanisms of development of flavor compounds will further enhance the use of microbial enzymes to develop specific and desired flavors in foods.     

Tau protein is involved in morphological plasticity in hippocampal neurons in response to BDNF

Tau protein, a microtubule-associated protein involved in a number of neurological disorders such as Alzheimer's disease (AD), may undergo modifications under both physiological and pathological conditions. However, the signaling pathways that couple tau protein to neuronal physiology such as synaptic plasticity have not yet been elucidated. Here we report that tau protein is involved in morphological plasticity in response to brain derived neurotrophic factor (BDNF). Stimulation of the cultured rat hippocampal neurons with BDNF resulted in increased tau protein expression, as detected by Western blotting. Furthermore, tau protein accumulated in the distal region of the neurite when treated with taxol or taxol plus BDNF. The increased tau protein also protected neurons against nocodazole-induced dendrite loss. Moreover, BDNF promoted spine growth as well as tau protein over-expression. Knockdown of tau protein using specific short-hairpin RNA (shRNA) significantly decreased the spine density. And BDNF could not increase the spine density of tau-knockdown neurons. These results highlight a possible role for tau protein in the dynamic rearrangement of cytoskeletal fibers vital for BDNF-induced synaptic plasticity.     

农林复合系统种间关系研究进展

种间相互作用在很大程度上决定了农林复合系统的生产力和可持续性,理解种间相互作用是经营和管理农林复合系统的关键。地上部分相互作用主要包括复合系统组分对光的竞争与互利、小气候的改变对系统生产力的影响;地下部分相互作用主要包括复合系统组分对水分和养分资源的竞争与互利、固氮树种对系统生产力的影响以及化感作用。今后需加强不同立地条件下的不同农林复合系统种间关系的比较、农林复合系统组分的空间分布格局、化感作用以及农林复合系统种间关系模型等研究。     

Stability in development and variability in morphological signs in a natural population of Drosophila melanogaster: seasonal dynamics in 1999

Seasonal dynamics of developmental stability and variability of morphological traits was examined in a natural population of Drosophila melanogaster in order to compare these two parameters as indicators of temperature stress. Morphometric (thorax length and wing length) and meristic (number of sternopelural and orbital bristles) were studied. Variability was measured as the coefficient of variation. Stability of development was estimated as fluctuating asymmetry (FA) of bilateral traits. Thorax length and wing length did not exhibit consistent seasonal trends whereas wing loading significantly decreased. Significant seasonal changes in FA were not detected in any trait examined. Two traits showed reduced variation in autumn. The use of FA as an indicator of ecological stresses in insects is discussed on the basis of these results and the literature evidence.     

Structures in focus--filopodia

Filopodia are thin cell surface extensions filled with tight parallel bundles of actin filaments. They are highly dynamic structures which rapidly extend and retract as well as sweep up and down and from side to side, and can be found at the leading edge of many types of motile cells such as fibroblasts and keratinocytes, as well as the growth cone tips of migrating axons. Cells appear to use filopodia to explore the extracellular matrix (ECM) and surfaces of other cells, identifying appropriate targets for adhesion or in the case of a migrating growth cone, for sensing guidance cues that enable the axon to navigate to it's appropriate target. As well as this sensory role, filopodia have also recently been shown to play an important mechanical role in epithelial adhesion, and are likely to be key players in developmental processes that require migrating epithelial sheets to zipper and fuse to one another. Their dynamic properties as well as their tendency to be damaged or lost after fixation mean they are best analysed using live imaging techniques. As this field improves, the number of tissues in which filopodia are seen to be playing key roles is fast increasing.     

Atrial natriuretic peptide inhibits neurohypophysial hormones' release in the rat (in vitro and in vivo studies).

Intracerebroventricular hANP (50 nmol) inhibits release of vasopressin and oxytocin following dehydration as well as after haemorrhage. 10 nmol/L hANP markedly inhibits vasopressin and oxytocin release in vitro from the neurointermediate lobes both under basal condition as well as during stimulation with excess (56 mM) potassium. It is suggested that ANP may serve as a modulator of vasopressin and oxytocin release. The respective processes are localized, at least in part, at the neurohypophysial level.     

Ammonia metabolism in tissue of newborn animals in health and in digestive disorders]

Ammonium nitrogen was studied for its metabolism in the tissues of ruminants in transition from pre- to postnatal development in norm and with disorders in gastroenteric digestion. It is established that the intensity of ammonium genesis and glycolysis processes as well as a cycle of tricarbonic acids change in newborn calves as compared to adult animals. The ammonium toxicosis development in sick animals, which is confirmed by an increase of the ammonia level and intensification of the reactions of ammonium- and ureogenesis in tissues of the gastroenteric tract, liver and kidneys.     

Anaerobes in waters

The classification of anaerobic bacteria in the aquatic environment with regard to their ability to survive in extreme environments (such as high or low temperatures, high salinity and pH) as well as the pathogenicity of Clostridia are presented briefly in this article. The importance of anaerobic bacteria in environmental pollution and several types of corrosion is discussed. The usefulness of anaerobic bacteria as pollution indicators of pollution in the aquatic environment and the methods used for their isolation, enumeration and identification are also presented.