Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

Comparative study of genomes of two species of flax by C-banding of chromosomes

C-banding patterns of the karyotypes of two closely related wild flax species, Linum austriacum L. (2n = 18) and Linum grandiflorum Desf. (2n = 16), were studied. The karyotypes of both species were similar in the chromosome morphology and size. In each species, metacentric and acrocentric chromosomes (1.7-4.3 microns) and one satellite chromosome were observed. In the karyotypes of the species studied, all homologous chromosome pairs were identified, and quantitative ideograms were constructed. Eight chromosome pairs in the two species had similar C-banding patterns. A low level of intraspecific polymorphism in the intercalary and telomeric C-bands was shown in both species. The results indicate that the genomes of two flax species originated from one ancestral genome with the main chromosome number of 8 or 9. Apparently, the doubling of chromosome number or loss of one chromosome with subsequent redistribution of the chromosome material in the ancestral form resulted in the divergence into two species, L. austriacum L. and L. grandiflorum Desf. A considerable similarity of chromosomes in these species provides evidence for their close phylogenetic relatedness, which makes it possible to place them in one section within the Linum genus.     

Age-related features of the metabolism of fatty acid components of phospholipids of the cell nuclei of rat liver under the effect of dietetic factors

The metabolism of nuclear phospholipid acyl components of liver in uneven-aged rats was studied in vitro under different dietary fat implications. The activity of phospholipases A1 and A2 in the nuclei was found to sharply increase in animals pretreated with excess of fat. The incorporation of labelled palmitic, oleic, linoleic and arachidonic acid into nuclear phospholipids is under control of age and diet manipulations. The observed changes in the level of fatty acids metabolism are more pronounced in cell nuclei of the young rat liver. The lipid composition of cell nuclei in the test 3-month old animals does not differ from that of the control animals. At the same time dietary implications induce deep changes in the composition of nuclear lipids in 24-months old animals.     

Effects of varying periods of immobilization of a limb on the morphology of a peripheral nerve

Immobilization of a hind limb of the cat in the resting position was found to result in morphological changes in the nerve supplying the medial head of the gastrocnemius muscle. A reduction in the diameter of the larger myelinated fibres (greater than 12 micrometers) concomitant with a reduction in the mean fibre diameter of the nerve were observed. This reduction in the mean fibre diameter of the nerve was found to be directly proportional to the period of immobilization. Prolonged immobilization beyond 8 weeks, resulted in the splitting of the myelin lamellae, formation of myelin rings and figures in some of the larger axons in addition to an abundant increase in collagen. These structural changes indicate a definite neural involvement in the disuse atrophy of the muscle as a result of immobilization extending for a period of 8 weeks and above.     

Interrelation of diurnal rhythms of recirculation of lymphocytes and their synthesis of cAMP

The correlative analysis of diurnal rhythms of cell number and adenylate cyclase cellular activity was performed in the thymus, spleen and peripheral blood of Swiss mice, intact or thymectomized at the age of 3 months. The existence of somehow synchronized diurnal rhythms of cAMP exchange and cell recirculation was found in the peripheral lymphocyte pool and in the thymus. Diurnal rhythm of cAMP synthesis in peripheral lymphocytes was regulated by the thymus. Thymectomy led to desynchronization of recirculating processes and cyclic nucleotide metabolism in immunocompetent cells.     

Shapes of curves of pH-dependence of reactions

A simple case is considered in which the rate of a two-step reaction depends on pH because the intermediate formed in the first step has to gain (or lose) a proton before it can react in the second step, and in which the rate-determining step therefore changes with pH. The curves of reaction rate against pH are shown to be symmetrical, and the sharpest peak possible has a width at half its height of 1.53pH units, i.e. of 2log(3+2 radical2). Any particular curve for this situation proves to be identical with a curve that could be generated for the pH-dependence of a single-step reaction in which the rate is proportional to the concentration of a particular ionic form of a reactant. Curves for the latter situation, however, can have forms impossible for the former case in which the rate-determining step changes, but only if the protonations that activate and deactivate the reactant are co-operative. The peak can then become even sharper, and its width at half its height can fall to 1.14pH units, i.e. to 2log(2+ radical3).     

Effects of overexpression of nutrient receptors on germination of spores of Bacillus subtilis

The rates of germination of Bacillus subtilis spores with L-alanine were increased markedly, in particular at low L-alanine concentrations, by overexpression of the tricistronic gerA operon that encodes the spore's germinant receptor for L-alanine but not by overexpression of gerA operon homologs encoding receptors for other germinants. However, spores with elevated levels of the GerA proteins did not germinate more rapidly in a mixture of asparagine, glucose, fructose, and K(+) (AGFK), a germinant combination that requires the participation of at least the germinant receptors encoded by the tricistronic gerB and gerK operons. Overexpression of the gerB or gerK operon or both the gerB and gerK operons also did not stimulate spore germination in AGFK. Overexpression of a mutant gerB operon, termed gerB*, that encodes a receptor allowing spore germination in response to either D-alanine or L-asparagine also caused faster spore germination with these germinants, again with the largest enhancement of spore germination rates at lower germinant concentrations. However, the magnitudes of the increases in the germination rates with D-alanine or L-asparagine in spores overexpressing gerB* were well below the increases in the spore's levels of the GerBA protein. Germination of gerB* spores with D-alanine or L-asparagine did not require participation of the products of the gerK operon, but germination with these agents was decreased markedly in spores also overexpressing gerA. These findings suggest that (i) increases in the levels of germinant receptors that respond to single germinants can increase spore germination rates significantly; (ii) there is some maximum rate of spore germination above which stimulation of GerA operon receptors alone will not further increase the rate of spore germination, as action of some protein other than the germinant receptors can become rate limiting; (iii) while previous work has shown that the wild-type GerB and GerK receptors interact in some fashion to cause spore germination in AGFK, there also appears to be an additional component required for AGFK-triggered spore germination; (iv) activation of the GerB receptor with D-alanine or L-asparagine can trigger spore germination independently of the GerK receptor; and (v) it is likely that the different germinant receptors interact directly and/or compete with each other for some additional component needed for initiation of spore germination. We also found that very high levels of overexpression of the gerA or gerK operon (but not the gerB or gerB* operon) in the forespore blocked sporulation shortly after the engulfment stage, although sporulation appeared normal with the lower levels of gerA or gerK overexpression that were used to generate spores for analysis of rates of germination.     

Effect of conditioning polarization of soma of giant neurons of mollusks on the mechanism of action-potential generation

To ascertain the properties of an excitable membrane of the soma of giant neurons of mollusks, experiments were carried out to study the effect of conditioning shift of the membrane potential on the mechanism of action-potential generation. The effect of conditioning was assessed from changes in the action-potential curve and its first derivative, as well as from the curve of transmembrane currents under voltage clamp conditions. It was found that a change in membrane potential evokes at least two reactions which have opposite effects on the mechanism of generation of action potentials. These reactions evidently have different time characteristics. One of these does not differ notably from the reaction recorded for other excitable structures, and is manifested in the activation (with hyperpolarization) or inactivation (with depolarization) of the mechanism generating action potentials. The other reaction contributes either to an increase (with depolarization) or a decrease (with hyperpolarization) in the efficiency of this mechanism. Conditioning polarization also has a marked effect on the system responsible for repolarization of the membrane during generation of action potentials. This effect is manifested in a change in the reaction of this system to tetraethylammonium ions. The specific membrane systems sustaining excitability and reacting to changes in the strength of the membrane's electrical field were found to be very inert. After a shift in the potential to a given stable level a rearrangement, lasting sometimes tens of seconds, takes place in the membrane.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 2, No. 1, pp. 91–99, January–February, 1970.     

Isolation of hyperactive mutants of mammalian target of rapamycin

The mammalian target of rapamycin (mTOR) is a Ser/Thr kinase that plays essential roles in the regulation of a wide array of growth-related processes such as protein synthesis, cell sizing, and autophagy. mTOR forms two functionally distinct complexes, termed the mTOR complex 1 (mTORC1) and 2 (mTORC2); only the former of which is inhibited by rapamycin. Based on the similarity between the cellular responses caused by rapamycin treatment and by nutrient starvation, it has been widely accepted that modulation in the mTORC1 activity in response to nutrient status directs these cellular responses, although direct evidence has been scarce. Here we report isolation of hyperactive mutants of mTOR. The isolated mTOR mutants exhibited enhanced kinase activity in vitro and rendered cells refractory to the dephosphorylation of the mTORC1 substrates upon amino acid starvation. Cells expressing the hyperactive mTOR mutant displayed larger cell size in a normal growing condition and were resistant to cell size reduction and autophagy induction in an amino acid-starved condition. These results indicate that the activity of mTORC1 actually directs these cellular processes in response to nutrient status and confirm the biological functions of mTORC1, which had been proposed solely from loss-of-function analyses using rapamycin and (molecular)genetic techniques. Additionally, the hyperactive mTOR mutant did not induce cellular transformation of NIH/3T3 cells, suggesting that concomitant activation of additional pathways is required for tumorigenesis. This hyperactive mTOR mutant will be a valuable tool for establishing physiological consequences of mTOR activation in cells as well as in organisms.     

The influence of denervation of the maturation of the flight muscle of Periplaneta americana.

The metathoracic musculature of the American cockroach Periplaneta americana was denervated by dissecting the nerves originating in the metathoracic ganglion on one side within 2 days after the last moult. The biochemical and morphological differences between normal and denervated musculature were followed two weeks later. Denervation completely prevents the gain in weight, protein content and cytochrome oxidase activity which occur in normal muscles during the two weeks after previous moulting. The content of phosphoarginine in the denervated muscle does not differ from the control muscle and is lower than in young muscles. The ability to resynthesize phosphoarginine postanaerobically is substantially lower in the denervated muscle than in control muscles, or in young muscles immediately after the last moult. The ultramicroscopic structure of the denervated muscle differs from that of the normal muscle: the mitochondria possess less cristae, the matrix between them appears less dense and the sarcoplasmatic reticulum is less developed. Thus the denervated muscle not only fails to mature, but also developes serious structural and biochemical disorders.     

Determination of stoichiometry of radioiodination of proteins

A sensitive method for the detection of small quantities of hydrophobic antioxidant free radical scavengers such as butylatedhydroxytoluene (BHT) and butylatedhydroxyanisole (BHA) in aqueous samples is described. The procedure involves extraction of the hydrophobic free radical scavenger into an organic solvent phase, followed by the subsequent reaction of an aliquot of this extract with the stable cation radical tris(p-bromophenyl)amminium hexachloroantimonate (TBACA). In experiments with BHT and BHA, the loss of TBACA absorbance at 730 nm was found to be linearly proportional to the amount of antioxidant added, with quantities of BHT as small as 200 pmol being easily detectable. In aqueous suspensions of dimyristoylphosphatidylcholine vesicles, assays of the aqueous BHT concentration showed that BHT partitioned strongly into the membrane phase, achieving very high BHT/phospholipid ratios. For a given concentration of BHT, partitioning into the membrane phase was greater in large, multilamellar liposomes than in either small, single-walled vesicles or in purified rat brain synaptic vesicle membranes. Direct assay of BHT and BHA in phospholipid membranes, however, was complicated by a nonspecific interaction between TBACA and the phospholipid.     

Asymmetry of aging of the large hemispheres of the rat brain

The dynamics of the accumulation of free-radical oxidation products in the brain hemispheres of rats in rate ontogenesis was studied. Multiphase changes in the concentration of products in the right and left hemispheres in different age groups were registered. Significant differences in the contents of hydroperoxides, Schiff's bases of phospholipids and lipofuscin in brain hemispheres revealed, which correlates with different rate of ageing of hemispheres.     

History of the study of biodiversity of photosynthesizing bacteria

The tendencies in the study of anoxygenic photosynthesizing bacteria (APB) are considered in the review in the historical aspect, since APB discovery till present day. The contribution made by the researchers of the Institute of Microbiology, Russian Academy of Sciences, to the study of the phylogeny, ecology, and morphophysiological diversity of APB is noted. At present, the molecular-biological approaches play a decisive role in ecology and taxonomy. The most important task at the modem stage of the development of microbiology is to maintain the continuity of the historically formed classical approaches in the study of APB diversity.     

基于GIS的稻田蜘蛛混合种群发生分析

在地理信息系统的支持下 ,对中国稻区 117个样点蜘蛛物种数与个体数进行空间插值 ,获得稻田蜘蛛混合种群数量专题地图和个体数量发生专题地图 .根据所得专题地图 ,分析了不同水稻种植区蜘蛛种群发生以及不同稻区的生态特征 .研究结果如下 :在北纬 35 .5°以南的水稻种植区域 ,蜘蛛种群与个体发生量较高 ,种群一般在 13种以上 ,个体数一般在每 10 0丛禾 10 0头以上 ;在北纬 35 .5°以北的水稻种植区域种群一般在 11种以下 ,个体数一般在每 10 0丛禾 47头以下 ;在北纬 35 .5°以南的水稻种植区域的年降雨量、年无霜期和 7月平均温度要高于在北纬 35 .5°以北的水稻种植区域 .在北纬 35 .5°以南的水稻种植区域的年日照时数要低于在北纬 35 .5°以北的水稻种植区域 .     

Correction of distortion of histologic sections of arteries

Histologic sections of arteries can be used to generate three-dimensional (3D) geometric models and identify structural constituents. However, geometric distortions are introduced by fixation, embedding and sectioning; distortions which can, for example, lead to errors in stresses predicted by finite element models. We developed a method to measure and correct for distortions caused by acrylic processing and applied it to intact, healthy porcine coronary arteries. Micro-computed tomography was used to image arteries in the fresh and embedded states. Tissue blocks were sectioned, stained and imaged using a light microscope. Each section contained four registration marks used to determine strains introduced by sectioning and staining. Using these three image sets, 3D geometric models were generated and distortions were measured. Fixation, processing, and embedding resulted in shrinkage of 6.4+/-2.3% axially and 35.4+/-5.0% in mean cross-sectional area (n=5). Shrinkage in a cross section was well characterized by a uniform, equibiaxial strain. Sectioning and staining resulted in additional compressive strains in the sectioning direction of 0.067+/-0.011 and, in the direction perpendicular to sectioning, of 0.023+/-0.005 (n=5). These strains are assumed uniform and form the basis for correcting section geometry. Reconstructions using corrections for sectioning and shrinkage-related distortions had errors of 1.6+/-0.5% (n=5) and 4.0+/-1.7% (n=5), respectively.     

Study of the effectiveness of methods of purification of metalloprotease produced by Bacillus subtilis

The effectiveness of the purification of proteolytic enzyme produced by B. subtilis production strain 3H in different nutrient media was evaluated. As revealed in this study, the use of the initial material obtained in peptone nutrient medium made it possible to obtain proteolytic enzyme with the highest specific activity by the methods of salting out, gel and ion-exchange chromatography, but the use of these methods on a production scale led to the deterioration of purity characteristics. Changes in the nutrient medium composition used for the cultivation of the production strain resulted in greater effectiveness of the purification methods. The highly purified preparation of metalloprotease with specific activity exceeding that of available commercial preparations more than twofold was obtained.     

History of the Study of Biodiversity of Photosynthetic Bacteria

The tendencies in the study of anoxygenic photosynthetic bacteria (APB) are considered in the review in the historical aspect, from the discovery of APB till the present day. The contribution made by the researchers of the Institute of Microbiology, Russian Academy of Sciences, to the study of the phylogeny, ecology, and morphophysiological diversity of APB is noted. At present, molecular biological approaches play a decisive role in ecology and taxonomy. The most important task at the modern stage of the development of microbiology is to maintain the continuity of the historically formed classical approaches in the study of APB diversity.     

Effector innervation of melanophores of the arteries of the base of the brain]

Melanophores in the arteries of the base of the brain of kittens displayed pronounced variations in size and shape in response to the peripheral electrical stimulation of the vagus and the sympathetic nerves. These melanophores changed their size and shape under the influence of acetylcholine and noradrenaline solutions in vitro too. The present experiments showed melanophores to have a double effector innervation.     

Tumorigenicity of minute dose levels of N-methyl-N-formylhydrazine of Gyromitra esculenta

Separate administrations of 0.0005 to 0.00025% N-methyl-N-formylhydrazine in drinking water to 6-week-old randomly bred Swiss mice for the remainder of their lifetime induced lung neoplasms. At the high dose level, 64% of the females and 48% of the males developed lung tumors, while the corresponding tumor incidences at the lower dose level were 62% in the females and 54% in the males. In untreated controls, the lung tumor incidences were 29% in the females and 19% in the males. Histopathologically, the lesions were classified as adenomas and adenocarcinomas of the lungs.N-methyl-N-formylhydrazine is a stable constituent of the edible false morel mushroom Gyromitra esculenta. The environmental significance is discussed, in view of the carcinogenicity of minute doses of this chemical.