Polysaccharides of diatoms occurring in Lake Baikal

Polysaccharide composition of neutral, acid- and alkali-soluble fractions of the diatoms Stephanodiscus meyerii Genkal et Popovsk and Aulacoseira baicalensis (K. Meyer) Simonsen of Lake Baikal has been studied. Neutral polysaccharides were represented by chrysolaminarans (1-->3;1-->6-beta-D-glucans). The chrysolaminaran from S. meyerii consists of the high- and low-molecular-weight fractions (40 and 2-5 kDa, respectively) and contains a large number of beta-1-->6-bound glucose residues. The chrysolaminaran from A. baicalensis is a low-molecular-weight 1-->3:1-->6-beta-D-glucan containing a small number of beta-1-->6 bonds, with mannitol being attached to the reducing unit of its chain. Acid- and alkali-soluble polysaccharide fractions are practically absent in S. meyerii. The alkali-soluble fraction from A. baicalensis is a low-molecular-weight (2-kDa) glycoprotein, the carbohydrate moiety of which is represented by a heteropolysaccharide.     

异株藤的离体快繁

1植物名称异株藤(Calamus dioicus)。 2材料类别胚。 3培养条件(1)胚芽生长培养基：MS+6-BA 2．0 mg·L一(单位下同)+4％蔗糖;(2)丛芽诱导培养基：MS+6-BA 4．0+IBA 1．0+NAA 1．0+4％蔗糖;(3)生根培养基1／2MS(大量元素减半)+IBA 0．5+NAA 0．5+3％蔗糖。培养基(1)和(2)加0．7％卡拉胶,培养基(3)加0．73％卡拉胶,pH 5．8±0．2。培养温度(28±2)℃,每天光照10 h,光照度为2 000 k。 4生长与分化情况 4.1 萌发果实大量成熟前一个半月采集近成熟果实,去除果肉得干净种子,用75％酒精浸泡30 s,0．1％升汞表面消毒加～30 min,无菌水冲洗4～5次,在超净台上用刀片将发芽孔打开后转接至培养基(1)。种子在培养基(1)上30 d,与田间播种相同,胚根先长出发芽孔,但受6-BA的作用,胚根长至0．5～1．0 cm即不再进一步生长。接种∞d,胚芽长出发芽孔,∞d长至1．5～2．0 cm高,即可切下胚芽转入丛芽诱导培养基(2)。 4.2 丛芽诱导在培养基(2)中,胚芽高生长明显减缓,基部开始横向膨胀生长,约40d分化出丛芽,丛芽诱导率为30％～35％。     

Effect of organic acids on the biosynthesis of carotenes by an Actinomyces chrysomallus strain

Synthesis of carotenes by Actinomyces chrysomallus var. carotenoides was stimulated by citric, acetic, oxalacetic, fumaric, succinic, malic, alpha-ketoglutaric, tartaric, pyruvic, and propionic acids. Acetic acid acts as a precursor of carotene synthesis and also has another stimulating mechanism of action on carotenogenesis of the actinomycete. Acetic, furmaric, malic, succinic, and alpha-ketoglutaric acids stimulate cyclization of lycopene yielding beta-carotene.     

DNA synthesis in rat liver following administration of antihepatocytotoxic serum]

Experiments were conducted on adult female rats. The autoradiographic method was applied to the study of thymidine-3H incorporation into the parenchymatous and reticulo-endothelial cells of the liver under conditions of using low doses (0.06 microgram of protein per 100 of body weight) of antihepatocytotoxic serum (AHCS), gamma-globulin isolated from it (gammaAHCS) and gamma-globulin fraction of normal rabbit serum (gammaNRS) to intact animals and rats with carbon tetrachloride affection of the liver. The labelled nuclei index of both the parenchyma and the reticuloendothelial cells increased in case of gammaAHCS administration, and, to a lesser extent, of AHCS to intact animals. gammaAHCS used against the background of CCl4 administration intensified the reparative regeneration. The action of gammaAHCS has phasic character--the period of the labeled nuclei elevation was followed by their reduction, replaced by new intensification of the proliferative processes.     

Ultrastructural identification of glial cells in the oral area of the comb-bearer <Emphasis Type="Italic">Berë cucumis</Emphasis>

In the electron microscopic study of oral epithelium and underlying areas of mesoglea of adult comb-bearers Berë cucumis (Ctenophora), there were described peculiar light cells with a characteristic localization, ultrastructure, ways of interaction with cells of other types including developing and mature chemoreceptors and neuronal processes. Comparison of the obtained results with the literature data allows identification of the light cells as glial cells, one of the first such cells in representatives of the first multicellular animals.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 6, 2004, pp. 579–588.Original Russian Text Copyright © 2004 by Aronova, Alekseeva.     

Evidence for Symbiont-induced Alteration of a Host's Gene Expression: Irreversible Loss of SAM Synthetase from Amoeba proteus

ABSTRACT. Symbiont-bearing xD amoebae no longer produce a 45-kDa cytoplasmic protein that functions as S-adenosylmethionine synthetase in symbiont-free D amoebae. The absence of the protein in xD amoebae is attributable to xD amoeba's failure to transcribe the corresponding gene as a result of harboring bacterial symbionts. However, xD amoebae have about half the level of enzyme activity found in D amoebae, indicating that they use an alternative source for the enzyme. xD amoebae originated from D amoebae by bacterial infection and now depend on their symbionts for survival. xD amoebae exhibit irreversible nucleolar abnormalities when their symbionts are removed, suggesting that X-bacteria supply the needed enzyme. A monoclonal antibody against the 45-kDa protein was produced and used as a probe in cloning its corresponding cDNA. The product of the cDNA was found to have S-adenosylmethionine synthetase activity. These results show how symbiotic X-bacteria may become essential cellular components of amoebae by supplementing a genetic defect for an amoeba's house-keeping gene that is brought about by an action of X-bacteria themselves. This is the first reported example in which symbionts alter the host's gene expression to block the production of an essential protein.     

Intracellular distribution of estradiol and estrogen binding sites in the uterus and oviducts of the green monkey (Cercopithecus griseus)

Plasma estradiol (E2) and progesterone (P) concentrations, E2 and estrogen binding sites (EBS) content in the uterus and oviducts of green monkey (Cercopithecus griseus) were measured during different phases of the menstrual cycle. Plasma E2 and P patterns were practically identical to those of African-Asian monkeys and humans. The E2 and EBS levels in various subcellular fractions were also determined. The correlations between these parameters were shown to be in accordance with the active mass law for monomolecular interaction at equilibrium state and might vary at different phases of the cycle. The alteration is probably attributable to variations in the activity of estrogen-receptor interaction during the menstrual cycle.     

Combined action of lithium salts and serotonin on the caudate nucleus

Intracaudate injections of lithium hydroxybutyrate (5 micrograms) produce a serotonin-like effect on the power characteristics of the caudatogram frequency ranges. However, when injected in a single dose, the drug is a serotonin antagonist at the level of the caudate nucleus. On the contrary, being administered for a long time, the drug potentiates the action of the mediator.