鄂西南山地植被的基本特征

本文系湖北省区划办委托进行的湖北植被类型图、植被区划图过程中的一个阶段性小结。鄂西南山地位于中国亚热带东部(湿润)常绿阔叶林亚区域,为湖北植被区划中鄂西南山地植被区,所属范围包括整个鄂西自治州、宜昌地区的大部及神农架南坡。约当北纬29°05′—31°22′,东经108°30′—111°47′的地理位置。     

Synthesis of Gp4N and Gp3N compounds by guanylyltransferase purified from yeast

Guanylyltransferase that catalyzes mRNA capping by the reaction, ppNpN + GTP----GpppNpN was purified from S. cerevisiae. The enzyme forms a nucleotidyl intermediate by phosphoamide linkage of GMP. Two guanylylated polypeptides of MR approximately 52,000 and 46,000 were obtained, the latter apparently by proteolysis of the larger component. Both forms transferred the covalently bound GMP to ppApG, yielding GpppApG. Dinucleoside tri- and tetraphosphates of the type Gp3N and Gp4N were also produced by using ribonucleoside 5'-di and triphosphates as acceptors. The purified yeast guanylyltransferase contained little or no RNA 5'-triphosphatase or methyltransferase.     

Microbial cooxidation of naphthalene for the production of 1,2-dihydroxy-1,2-dihydronaphthalene

A microbial cooxidation process for 1,2-dihydroxy-1,2-dihydronaphthalene from naphthalene has been demonstrated. A Pseudomonas putida it119 mutant strain grown with glucose as the sole carbon and energy source was used to oxidize naphthalene. Growth characteristics of the P. putida mutant strain were studied in both batch and continuous fermentation experiments. The rate of product formation was found to depend on naphthalene particle sizes, initial naphthalene and glucose concentrations. Kinetic models were developed to quantify the microbial cooxidation process and a two-stage fermentation process is proposed for further studies.     

Functional groups at the catalytic site of F1 adenosine triphosphatase

The protection of F1 ATPase by inorganic phosphate, ADP, ATP, and magnesium ion against inactivation by 1-fluoro-2,4-dinitrobenzene, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, and 1-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline, respectively, has been investigated. Dissociation equilibrium constants and rate constants for the labeling reactions have been deduced from a quantitative treatment of the kinetic data. Comparison of these dissociation constants with each other and with the corresponding literature values indicates that the essential Tyr, Arg, Lys, and Glu or Asp residues are indeed located at the catalytic site of the enzyme. Examination of the rate constants for the labeling reactions in the presence of excess inorganic phosphate, ADP, ATP, or magnesium ion, respectively, suggests that the essential phenol and amino groups are located nearer to the bound inorganic phosphate or the gamma-phosphate group than to the alpha- or beta-phosphate group of the bound ATP, that the essential guanidinium group is located nearer to the alpha- or beta-phosphate group than to the gamma-phosphate group of the bound ATP or the bound inorganic phosphate, and that the essential carboxylate group is located slightly farther away but complexed with magnesium ion which it shares with the bound inorganic phosphate. A mechanism consistent with these topographical relationships is proposed for the catalytic hydrolysis and synthesis of ATP.     

Acute viral infection of the central nervous system in children: an 8-year review.

Reliable information on acute viral infections of the central nervous system (CNS) in Canadian children has not been available. To investigation this disease in Halifax the medical records of 180 patients with presumed or definite acute viral CNS infection diagnosed at the Izaak Walton Killam Hospital for Children over an 8-year period were reviewed. The yearly incidence was estimated at 19.5/100 000 for children up to 16 years of age, and the peak incidence was in July, August and September. The cause was determined in 64 (36%) of the 180 patients; it was most commonly a known infectious disease -- mumps (in 24 patients) or varicella (in 9 patients). An enterovirus was responsible in nine cases, herpes simplex virus in eight and measles virus in six. The clinical manifestations were variable and included apnea in three infants who would otherwise have been considered to have nearly suffered the sudden infant death syndrome. Localizing features were present on the electroencephalograms of nine patients, including six with herpes simplex infection. Serologic study of paired serum samples obtained during the acute phase of the illness and during convalescence was the most useful laboratory method of establishing the diagnosis. As medical therapy for specific causes of acute viral CNS infection advances, greater attention should be placed on establishing the correct diagnosis.