Ⅱ型限制性核酸内切酶NcrⅠ的研究

 在肉色诺卡氏菌C-212株Nocardia carnea C-212中筛选到一种Ⅱ型限制性核酸内切酶NcrⅠ,经与BglⅡ的λDNA降解物的酶谱比较,以及酶识别特异性和切割位点的检测,证明了NcrⅠ是已知的限制酶BglⅡ的同切限制酶,而且其切割位点也与BglⅡ相同,其为:     

高温厌氧条件下纤维素的直接乙醇发酵

本文介绍了出分解纤维素的嗜热厌氧菌Clostridium celluloflavus sp.nov.直接发酵纤维素产乙醇的初步研究、发酵于60℃下进仃,其主要产物为乙醇、乙酸、氢气和二氧化碳。文中介绍了间歇发酵的若干特征与影响发酵的因素,1％纤维素发酵至120小时,大约有70％纤维素被分解;乙醇的转化率约为0.36g/g降解纤维素;发酵液中乙醇浓度达到56至61mM。发酵中乙醇与乙酸浓度的比值因发酵时间与其它发酵条件的不同而不同。     

EFFECTS OF HELPER PROTEINS ENCODED BY p19 AND orf1-orf2 GENES ON Cyt1Aa PROTEIN EXPRESSION IN ACRYSTALLIFEROUS STRAIN OF BACILLUS THURINGIENSIS

A series of plasmids were constructed to examine the effects of p19 and orf1‐orf2 genes from Bacillus thuringiensis on Cyt1Aa synthesis and inclusion formation. The plasmids expressed the cyt1Aa gene along with either p19 or orf1‐orf2, or each of them coordinatively with p20 in the acrystalliferous strain of B. thuringiensis subsp. israelensis 4Q7. No effect on the expression of Cyt1Aa protein was found when P19 or Orf1‐Orf2 co‐expressed with Cyt1Aa. However, when including p20 gene, the constructs with p19 or orf1‐orf2 gene produced lower yield of Cyt1Aa proteins than without p19 or orf1‐orf2 gene. Electron microscopy observation and bioassay showed that P19 and Orf1‐Orf2 have no influence on the crystal size and toxicity of Cyt1Aa protein. It is presumed that P19 and Orf1‐Orf2 might have negative effects on Cyt1Aa synthesis in B. thuringiensis.     

Metabolism of prostaglandins in spontaneously hypertensive rats: NAD"-dependent 15-hydroxyprostaglandin dehydrogenase activity is decreased in kidney and increased in lung.

Renal, pulmonary and gastric NAD⁺-dependent 15-hydroxyprostaglandin dehydrogenase activities were determined in both spontaneously hypertensive and normotensive rats at 6 and 12 weeks of age. Renal enzyme activity in hypertensive rats was only 30–40% of that present in normotensive controls at both ages. In contract, pulmonary enzyme activity in hypertensive animals was twice as active as that in normal controls. There was no significant difference in gastric enzyme activity. NAD⁺-dependent 9-hydroxyprostaglandin dehydrogenase activity, the enzyme responsible for the conversion of vasoinactive PGF metabolites to PGE metabolites, also failed to show any difference in two types of rat kidneys. The results indicate that, in hypertension, prostaglandin inactivation is impaired in kidney but is facilitated in lung.     

湖北石松目植物的研究

石松目植物是蕨类植物中经济价值较高的一个类群,除孢子粉供铸造工业使用外,大部份种类供药用,有的种类为酸性土的指示植物。湖北石松种类比较丰富,历年来植物学工作者们在我省采集了大量标本,并对民间使用情况进行过调查,积累了不少有用     

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.     

Induction of erythropoietin responsiveness in murine hematopoietic cells by the gag-myb-ets-containing ME26 virus.

ME26 virus, which was generated by inserting the coding region of the acute avian leukemia-inducing virus E26 into a murine retrovirus vector, encodes a 135-kDa gag-myb-ets fusion protein. Amphotropic murine leukemia virus pseudotypes of ME26 virus induce a high incidence of erythroleukemia 2 to 4 months after injection into newborn NFS/N mice. Spleen cells from the majority of these mice proliferate to high levels in the presence of the erythroid hormone erythropoietin (Epo) and can easily be established as permanent Epo-dependent cell lines. The cell lines contain multiple copies of ME26 viral DNA and express viral message and protein. An Epo receptor mRNA of normal size can be detected in these cells, and binding studies reveal a single class of lower-affinity Epo receptor with an affinity for Epo that is in the range of that previously reported for erythroid cells. The ME26 virus-induced Epo-dependent cell lines, however, appear more immature than previously described erythroid cell lines and more closely resemble early hematopoietic precursor cells, suggesting that the virus may be activating the Epo receptor in hematopoietic cells that do not normally express it. Consistent with this idea, we are able to infect an interleukin-3-dependent myeloid cell line, FDC-P2, with ME26 virus and convert it to Epo dependence. The ME26 virus-infected FDC-P2 cells, even before growth on Epo, showed a large increase in the amount of Epo receptor mRNA. However, no ME26 viral integrations can be detected adjacent to the Epo receptor gene, indicating that the virus is not activating the Epo receptor gene by promoter/enhancer insertion. Our results are more consistent with the hypothesis that the gag-myb-ets-encoded viral fusion protein, which is known to bind DNA, is directly or indirectly activating the expression of the Epo receptor gene in these cells.     

The matrix protein of human immunodeficiency virus type 1 is required for incorporation of viral envelope protein into mature virions.

Accumulating evidence suggests that the matrix (MA) protein of retroviruses plays a key role in virus assembly by directing the intracellular transport and membrane association of the Gag polyprotein. In this report, we show that the MA protein of human immunodeficiency virus type 1 is also critical for the incorporation of viral Env proteins into mature virions. Several deletions introduced in the MA domain (p17) of human immunodeficiency virus type 1 Gag polyprotein did not greatly affect the synthesis and processing of the Gag polyprotein or the formation of virions. Analysis of the viral proteins revealed normal levels of Gag and Pol proteins in these mutant virions, but the Env proteins, gp120 and gp41, were hardly detectable in the mutant virions. Our data suggest that an interaction between the viral Env protein and the MA domain of the Gag polyprotein is required for the selective incorporation of Env proteins during virus assembly. Such an interaction appears to be very sensitive to conformational changes in the MA domain, as five small deletions in two separate regions of p17 equally inhibited viral Env protein incorporation. Mutant viruses were not infectious in T cells. When mutant and wild-type DNAs were cotransfected into T cells, the replication of wild-type virus was also hindered. These results suggest that the incorporation of viral Env protein is a critical step for replication of retroviruses and can be a target for the design of antiviral strategies.