Chemical Constituents and Hydrogenase Binding in Cell Envelopes of Vibrio succinogenes

The particulate hydrogenase of Vibrio succinogenes is solubilized during treatment of cell envelopes at pH 11.0. Alkali-solubilized enzyme requires sulfhydryl compounds for activity. At neutral pH, soluble enzyme is reincorporated into alkalitreated cell envelopes and no longer requires an additional activator. In the present study, cell envelopes prepared by lysing cells with ethylenediaminetetraacetic acid plus lysozyme (EDTA-lysozyme) were used to determine the chemical composition of cell envelopes and derived pH 11.0 soluble and insoluble fractions and to investigate some properties of the binding and activation of alkali-solubilized hydrogenase. Lysis with EDTA-lysozyme resulted in the formation of spheroplast ghosts. The derived cell envelopes contained 61% protein, 3% ash, 23% lipid, and 1% phosphorus. The alkali-treated cell envelopes contained 50% protein, 2% ash, 24% lipid, and 1% phosphorus. The ash from cell envelopes and alkali-treated cell envelopes was rich in iron and phosphorus and also contained calcium, copper, magnesium, sodium, and zinc. Virtually all of the weight of the ashed samples was accounted for by the oxides of these metals. Since the reconstitution of particulate hydrogenase was achieved with pH 11.0 supernatant solution and precipitate, intact mucopeptide is not essential for hydrogenase binding. Release of hydrogenase during EDTA-lysozyme lysis was found to depend upon an apparent structural change which occurs in the membranes during extended storage at −20 C.     

Substrate Specificity of Actinoplanes Antibiotic Peptide Lactonases

A constitutive peptide lactonase from Actinoplanes missouriensis hydrolyzed echinomycin, stendomycin, thiostrepton, vernamycin B, staphylomycin S, and etamycin. An induced lactonase hydrolyzed actinomycin but not the other peptide lactones.     

Copper Sulfate-induced Fermentation Changes in Continuous Cultures of the Rumen Microbial Ecosystem

The effect of CuSO(4) on fermentation was studied in a continuously cultured rumen ecosystem. CuSO(4), introduced at a level of 50 mg/500 ml of culture volume twice daily, caused a marked inhibition of fermentation of concentrates. Fermentation of alfalfa hay was not inhibited by the same CuSO(4) concentration when the inoculum for the culture was obtained from a cow maintained on a normal concentrate ration. When the inoculum was from a cow on a high concentrate ration, hay fermentation was partially inhibited by CuSO(4). Concentrations of CuSO(4) that did not inhibit the fermentation of alfalfa hay or hay-concentrate mixtures caused preferential production of propionic acid and decreased production of methane.     

Lysis of Vibrio succinogenes by ethylenediamine-tetraacetic acid or lysozyme

Wolin, M. J. (University of Illinois, Urbana). Lysis of Vibrio succinogenes by ethylenediaminetetraacetic acid or lysozyme. J. Bacteriol. 91:1781-1786. 1966.-Cell suspensions of Vibrio succinogenes are lysed by ethylenediaminetetraacetic acid (EDTA) or lysozyme. Lysis occurs at alkaline pH and is prevented by 0.15 m NaCl or KCl or 0.3 m sucrose. The addition of 10(-3)m Mg(++), 10(-3)m spermine, or 10(-2)m Ca(++) prevents lysozyme lysis, and 10(-4)m spermine prevents EDTA lysis. EDTA lysis leads to the formation of a cell ghost, and lysozyme lysis leads to the formation of an empty round body. Freezing and thawing of cells permits lysozyme attack which is not prevented by the protective agents mentioned above. Much of the cell protein, and almost all of the nucleic acids, are released from the cells during EDTA lysis. Treatment of frozen-thawed cells with lysozyme at neutral pH does not cause release of more than 50% of the cell protein and 60% of the nucleic acids of the cells.     

Factors affecting pathogenicity of NPV preparations to the corn earworm,Heliothis armigera

Pathogenicity ofHeliothis nuclear polyhedrosis virus (HSNPV) to the corn earworm,Heliothis armigera, was studied using 3 different inoculative methods. The LD50 values of 4^th-instar larvae inoculated with corn-fed, diet-fed and inoculum-imbiding method were 1.85×10⁶, 2.55×10⁵ and 1,22×10³ PIBs/larva, respectively. The inoculum-imbiding is more sensitive and convenient for inoculatingH. armigera with HSNPV. The HSNPV product, Elcar^®, was highly pathogenic toH. armigera, the LD50 values of 2^nd-, 3^rd- and 4^th-instar larvae being 27, 83 and 1,221 PIBs/larva, respectively, as measured by the inoculum-imbiding method. The mortality of 4^th-instar larvae caused by HSNPV was increased, but the incubation period was shortened with higher incubation temperatures. However, the high temperature at 35°C caused a lower mortality, and a prolongation of the median lethal time (LT50). Stability and persistence of HSNPV preparations were better in January–February and April–May than in June–July and October–November periods when sprayed on corn silks under field conditions. The HSNPV was inactivated by weak alkaline dew (pH 8.1) collected from soybean leaves, but it remained active on those from corn, tomato and asparagus with pH 7.2–7.3. The artificial heavy rainfall of 242 mm/h for 30 min did not wash off HSNPV preparations sprayed on the corn silks.     

人γ干扰素突变体(rIFN-γ132-PGIL)的构建及其生物学活性的测定

利用DNA重组技术,去掉人γ干扰素(IFNγ)基因3′端含编码多肽羧基(C)端11个氨基酸的核苷酸序列,与编码P,G,I,L的DNA序列相连接,构成IFNγ突变体(rIFN-γ132-PGIL)基因,将后者插入pBV220P_RP_L串连启动子下游,转化大肠杆菌DH5α,在CIts857基因的调节下,通过升温诱导,获得了高效表达,表达量约占菌体可溶性蛋白的30％以上,抗病毒活性平均可达4.9×10~-8U/L,比母体菌株高10倍。SDS—PAGE结果表明,rIFN-γ132—PGIL分子量为17kd。     

Correlation between redistribution of a 26 kDa protein and development of chronic thermotolerance in various mammalian cell lines

Previous studies suggested that a 26 kDa protein might play an important role in protein synthesis-independent thermotolerance development in CHO cells. To determine if this phenomenon was universal, four mammalian cell lines, viz., CHO, HA-1, murine Swiss 3T3, and human HeLa, were studied. Cells were heated at 42 degrees C, and the level of 26 kDa protein in the nucleus was measured, together with clonogenic survival and protein synthesis. The results demonstrated that 1) the 26-kDa protein was present in the four different cell lines, and 2) the level of the 26 kDa protein in their nuclei was decreased by 30-70% after heating at 42 degrees C for 1 hr. However, restoration of this protein occurred along with development of chronic thermotolerance. The protein synthesis inhibitor cycloheximide (10 micrograms/ml) neither inhibited the development of chronic thermotolerance nor affected the restoration of the 26 kDa protein in the nucleus. In fact, this drug protected cells from hyperthermic killing and heat-induced reduction of 26 kDa protein in the nucleus. Heat sensitizers, quercetin (0.1 mM), 3,3'-dipentyloxacarbocyanine iodide (DiOC5[3]: 5 micrograms/ml), and stepdown heating (45 degrees C-10 min----42 degrees C), potentiated hyperthermic killing and inhibited or delayed the restoration of the 26 kDa protein to the nucleus. These results support a correlated, perhaps causal relationship between the restoration of the 26 kDa protein and chronic thermotolerance development in four different mammalian cell lines.     

大兴安岭林区针叶林的生长方程及火灾林木死亡率

本文用随机模拟的方法建立了北方针叶林的生长方程及其受到火灾侵害后的林木死亡率,定量地研究了火灾对这种林分变动的影响．