“Oxygen regulation” of the respiratory chain composition in the yeast Debaryomyces hansenii under multiple stress

It was shown that two stress factors, hypoxia and hyperosmotic shock, if applied simultaneously to the yeast Debaryomyces hansenii, display an antagonistic mode of interaction, which results in an increased degree of halophily of this microorganism under microaerobic conditions. Studies of the effects of respiration inhibitors (sodium azide and salicyl hydroxamic acid, SHA) and of the pattern of changes in the composition of the respiratory chain of Debaryomyces hansenii under the stated stress conditions led to the suggestion of three (or four) chains of electron transfer functioning simultaneously in the cell: the classical respiratory chain involving cytochrome-c oxidase, an alternative respiratory chain involving a cyanide-and azide-resistant oxidase, and additional respiratory chains involving oxidases resistant to salt, azide and SHA. Thus, the antagonistic mode of interaction between hypoxia and hyperosmotic shock results from the redirection of the electron flow from the salt-susceptible respiratory systems to the salt-unsusceptible ones encoded by “the hypoxia genes” and activated (induced) under microaerobic conditions.     

In vitro propagation of the neotropical giant bamboo, Guadua angustifolia Kunth, through axillary shoot proliferation

Guadua angustifolia Kunth was successfully propagated in vitro from axillary buds. Culture initiation, bud sprouting, shoot and plant multiplication, rooting and acclimatization, were evaluated. Best results were obtained using explants from greenhouse-cultivated plants, following a disinfection procedure that comprised the sequential use of an alkaline detergent, a mixture of the fungicide Benomyl and the bactericide Agri-mycin, followed by immersion in sodium hypochlorite (1.5% w/v) for 10 min, and culturing on Murashige and Skoog medium containing 2 ml l^?1 of Plant Preservative Mixture^®. Highest bud sprouting in original explants was observed when 3 mg l^?1 N⁶-benzylaminopurine (BAP) was incorporated into the culture medium. Production of lateral shoots in in vitro growing plants increased with BAP concentration in culture medium, up to 5 mg l^?1, the highest concentration assessed. After six subcultures, clumps of 8–12 axes were obtained, and their division in groups of 3–5 axes allowed multiplication of the plants. Rooting occurred in vitro spontaneously in 100% of the explants that produced lateral shoots. Successful acclimatization of well-rooted clumps of 5–6 axes was achieved in the greenhouse under mist watering in a mixture of soil, sand and rice hulls (1:1:1).     

渗透压对硝化作用的影响

在气升式内循环硝化反应器中研究了渗透压对硝化作用的影响。保持进水氨氮浓度420mg·L-1,将进水渗透压逐渐从4.3×105Pa提高到18.8×105Pa,硝化反应器的氨氮转化率稳定在93%～100%。将进水渗透压进一步提高到19.2×105Pa,氨氮转化率降至69.2%。渗透压对硝化作用的影响具有突发性,临界值在18.8×105～19.2×105Pa之间。受高渗透压胁迫时,活性污泥中硝化细菌的形态趋向单一,个体变小,内膜数量减少,并产生许多不明成分的颗粒状内含物。解除渗透压胁迫后,细胞结构恢复。添加钾离子能够缓解高渗压对硝化作用的影响。高渗透压胁迫以及解除渗透压胁迫可增强污泥硝化活性,比污泥氨氮转化率(污泥以SS计)分别从0.083kg·kg-1·d-1升至0.509kg·kg-1·d-1和2.569kg·kg-1·d-1,同比提高5.1倍和30.0倍。     

常夏石竹耐盐突变体渗透调节的研究

在离体培养条件下利用γ-射线作诱变剂获得耐0.5%、0.7%、1.0%NaCl的突变系,通过对稳定突变系植株叶片渗透剂含量及对渗透势贡献大小的测定表明耐盐突变体叶中K+、游离氨基酸、Na+、脯氨酸的含量高于对照,其中脯氨酸和Na+积累最明显。而叶片中可溶性糖的含量、K+/Na+低于对照。Na+对突变体植株叶片渗透势贡献最大,是最主要的渗透调节剂之一。耐盐突变体植株内存在渗透物质的再分配,叶内有吸钾排钠现象。     

胭脂红景天引种至西藏日喀则其渗透调节物质及保护酶活性的变化

胭脂红景天叶片呈胭脂红色,花开红色,具有极强的耐寒性和耐旱性,是优良的城市绿化植物。为了扩大胭脂红景天的应用范围,丰富恶劣生境的绿化材料,本试验对从哈尔滨引种到西藏日喀则表现良好的胭脂红景天进行了生理适应性研究。结果表明,随着栽植时间的延长,胭脂红景天叶片中丙二醛含量逐渐升高,但增加的幅度较小,脯氨酸含量先降低后升高,SOD、POD、CAT等保护酶的活性均呈先升高后降低的趋势。胭脂红景天可以通过增加体内渗透调节物质含量和提高保护酶活性来调节自身的生理代谢,适应日喀则地区高辐射、干旱等条件。     

Buchbesprechungen

Abstract

Schenk/Kolb: Grundriß der physiologischen Chemie, 6. überarbeitete Auflage. Erschienen im VEB Gustav Fischer Verlag Jena, 1971. Mit 116 Abb. und 237 Tab., Ganzleinen, Format 10,5 × 24,5 cm. Preis: 30,—M. Reviewed by H. Bergner.

H. Bergner: Energie — Leben — Leistung — Nahrung. Erschienen im Urania-Verlag Leipzig-Jena-Berlin 1971, 144 Seiten, mit 49 Abb. und 25 Tab., Ganzleinen, Format 14,5 × 21,5 cm, Preis: 9,80 M. Reviewed by H. Haenel.

G. Dirksen, W. Kaufmann und E. Pfeffer: Untersuchungen zur Verdauungs physiologie der Milchkuh mit der Umleitungstechnik am Duodenum. Erschienen im Verlag Paul Parey, Hamburg und Berlin 1972. 43 Seiten mit 10 Abb. und 22 Tab., kart., Format 16,5 × 25 cm, Preis: 22,00 DM (als Beiheft zur Z. Tierphys. Tierernähr. Futtermittelkd., für Bezicher der Zeitschrift 20,35 DM). Reviewed by H. Bergner.     

Self-Diffusion in Electrostatically Stabilized Colloidal Suspensions Using Brownian Dynamics

Abstract

Brownian dynamics is applied to suspended colloidal particles interacting through a screened Coulombic pair potential in the dilute region where the hydrodynamics is approximated by Stokes drag. Calculated properties include the osmotic pressure, the radial distribution function, and the self-diffusion coefficient. Verification is obtained by comparing the results to independently evaluated properties. Self-diffusion coefficicents are compared to approximate theories in the literature. The self-diffusion coefficient is observed to depend strongly on the local structure but only slightly on the longer range structure.     

l-Serine Production Improved by Analogue-resistant Mutants of a Methanol-utilizing Bacterium

In the higher plant, Arabidopsis thaliana, histidine-to-aspartate (His-to-Asp) phosphorelay signal transduction systems play crucial roles in propagation of environmental stimuli, including plant hormones. This plant has 11 sensor His-kinases, 5 histidine-containing phosphotransfer (HPt) factors (AHPs), and 20 response regulators (ARRs). To gain new insight into the functions of these phosphorelay components, their intracellular localization was examined with use of GFP-fusion proteins, constructed for certain representatives of HPt factors (AHP2) and type-A and type-B ARRs (ARR6/ARR7 and ARR10, respectively). The results showed that AHP2 is mainly located in the cytoplasmic space, while both the types of ARRs have an ability to enter preferentially into the nuclei, if not exclusively. Together with the results from an in vitro phosphorelay assay with AHP2 and ARRs, these results are discussed, in terms of a geneal framework of the Arabidopsis His-to-Asp phosphorelay network.     

Highly efficient in vitro proliferation and genetic stability analysis of micropropagated Ceropegiaevansii by RAPD and ISSR markers: A critically endangered plant of Western Ghats

Ceropegiaevansii McCann (family: Asclepiadaceae), a critically endangered plant of Western Ghats has acquired significant importance due to its medicinal implications, edible tubers, and ornamental flowers. This study deals with the optimization of axillary bud proliferation using nodal explants followed by genetic stability analysis of regenerants. Maximum number of shoots (11.6 ± 1.1) was observed on the Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (4.0 mg/l) and indole-3-acetic acid (0.3 mg/l) with 85% shoot multiplication frequency. In vitro-grown shoots were rooted best in 1/2 MS medium supplemented with indole-3-butyric acid (1.0 mg/l) with an average of 10.3 ± 0.9 roots per shoot and 92% rooting frequency. Plantlets were acclimatized best (90%) in a mixture of sterile soil, sand, and coco peat (1:2:1). Micropropagated plants were subjected to random amplified polymorphic DNA and inter simple sequence repeat markers analyses. Collectively, 759 bands were generated which were monomorphic and similar to the mother plant. Findings of this study are the first report on micropropagation and assessment of genetic stability of micropropagated plantlets in C. evansii which suggests that axillary shoot proliferation can safely be used as an effective tool for propagation and conservation of C. evansii.