Anther culture of papaya (Carica papaya L.)

Papaya (Carica papaya L.) anther containing microspores in tetrad to early-binucleate stages were successfully cultured on 1/2 strength MS salts and vitamins with full strength Na-Fe-EDTA supplemented with 2 mg/l NAA, 1 mg/l BA and 6% sucrose for callus initiation and formation. Highest frequencies of callus induction were obtained when anthers at the uninucleate stage were cultured in the dark. Haploid plantlets and pollen-derived embryoids were obtained from anthers cultured at the uninucleate stage on solidified MS medium containing 3% sucrose without any growth regulators under a low light intensity (1,500 lux). Large quantities of embryoids were obtained when the original embryoids were transferred to MS medium with 3% sucrose and no growth regulators. Cytology of root tips of embryoid-derived plants confirmed the haploid chromosome number of 9 indicating that the embryoids originated from pollen.Abbreviations MS Murashige and Skoog (1962) - MAA naphthaleneacetic acid - BA 6-benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid     

细菌(Pseudomonas maltophilia)之绒毛膜促性腺激素(hCG)结合物质之研究

 细菌(Pseudomonas moltophilia)与hCG及LH有特异的亲和力,实验发现,细菌之生长曲线与hCG结合活性成平行关系,96小时达高峰,细菌之培养液中含有可溶性结合蛋白,该蛋白经硫酸铵沉淀(80％饱和度)、Sephadex G-100柱层析、DEAE-纤维素柱0.5mol/L NaCl梯度洗脱,再过Sepharose CL-AB柱,收集之活性部分经SDS电泳测得其分子量为70,000,凝胶层析测Stokes radius为41A,Schiff氏染色未见着色带。     

Conversion of a primary amine to a labeled secondary amine by the addition of phenolic group and radioiodination

To preserve the nucleophilicity of amino compounds during conjugative radioiodination, a new method for converting primary amines to phenolic secondary amines was developed. Amino acids were used as model compounds for establishing optimal conditions for the reductive amination. In the first step of the reaction, the aldehyde group of 4-hydroxybenzaldehyde (formylphenol) was reacted reversibly with an amino group to form an imine. The irreversible attachment of formylphenol to the amino group was accomplished by reduction of the imine with sodium cyanoborohydride. The pH optimum for the reaction was 5.0. Higher temperature has favorable effects on the rate and extent of the conjugation. Phenolic derivatives of amino compounds suitable for radioiodination are produced by the reactions described.     

Genetic characterization of mouse immunoglobulin allotypic determinants (allotopes) defined by monoclonal antibodies

We have generated a new series of monoclonal antibodies recognizing allotypic determinants on mouse IgG₁, IgG_2a, and IgG_2b. In this communication we describe their reactivities with immunoglobulins of the inbred mouse strains. Comparison with serology charts indicates that many of these monoclonal antibodies detect allotypic specificities previously defined by conventional antisera; others define previously undescribed specificities. Strain and isotype distribution allows us to assign five new allotypic specificities to Igh-1 and three new specificities to Igh-3. In addition, on the basis of reactivity with the monoclonal antibodies, we have defined a new Igh haplotype in SWR/J mice, Igh ^p.Abbreviations used in this paper Igh immunoglobulin heavy chain - SDS sodium dodecyl sulfate     

The isolation and properties of phenylalanine hydroxylase from human liver

Phenylalanine hydroxylase was prepared from human foetal liver and purified 800-fold; it appeared to be essentially pure. The phenylalanine hydroxylase activity of the liver was confined to a single protein of mol.wt. approx. 108000, but omission of a preliminary filtration step resulted in partial conversion into a second enzymically active protein of mol.wt. approx. 250000. Human adult and full-term infant liver also contained a single phenylalanine hydroxylase with molecular weights and kinetic parameters the same as those of the foetal enzyme; foetal, newborn and adult phenylalanine hydroxylase are probably identical. The K(m) values for phenylalanine and cofactor were respectively one-quarter and twice those found for rat liver phenylalanine hydroxylase. As with the rat enzyme, human phenylalanine hydroxylase acted also on p-fluorophenylalanine, which was inhibitory at high concentrations, and p-chlorophenylalanine acted as an inhibitor competing with phenylalanine. Iron-chelating and copper-chelating agents inhibited human phenylalanine hydroxylase. Thiol-binding reagents inhibited the enzyme but, as with the rat enzyme, phenylalanine both stabilized the human enzyme and offered some protection against these inhibitors. It is hoped that isolation of the normal enzyme will further the study of phenylketonuria.     

Identification and genetic control of starch-degrading enzymes in maize endosperm

Three starch-degrading enzymes from liquid endosperm of maize have been separated by means of horizontal acrylamide gel electrophoresis. The three enzymes are tentatively identified as -amylase (zone 1), -amylase (zone 2), and -glucan phosphorylase (zone 3). Electrophoretic variants of these enzymes were found among ten inbred strains examined. Results of genetic crosses with respect to zone 2 amylase show that it is controlled by a pair of alleles (Amy-2 ^A and Amy-2 ^B) acting without dominance. It further appears that Amy-2 and Ct (catalase) are linked with 5% recombination frequency.This work was supported by the U.S. Atomic Energy Commission, under contract No. AT(11-1)-1338.     

大肠杆菌棉子糖操纵子α—半乳糖苷酶表达的调节控制

The alpha-galactosidase, coded for by the first structural gene rafA in the plasmid determined raf operon was an inducible enzyme. In contrast to lac or mel operon, raf operon has more strict structural specificity for inducers. The enzyme can be induced by melibiose and raffinose, or weakly by D-galactose, but not by structurally related sugars such as lactose, PNPG etc.. The alpha-galactosidase forming capacity as function of growth curve reached a single peak at the end of the logarithmic phase of the growth. The structure and regulation of raf operon is similar to those of lac operon. The repressormor-mediated negative control plays a major role in the regulation of raf operon, and cAMP-CAP mediated positive control is also involved in the regulation. When 0.4% glucose was added into the medium with other carbon sources, the expression of the enzyme was repressed by 2-3 fold. Transient catabolite repression has been observed neither in inducible nor constitutive alpha-galactosidase expression. Based on alpha-galactosidase assay, in mutant strains CA8306(cya) and CA8445 (cya, crp) the expression level of raf operon was only 9% and 2.5% of that in wild type strain respectively. The glucose effect or the repression in cya mutant can be abolished by 1-5 mmol cAMP. The constitutive alpha-galactosidase expression in cya and cry double mutant (CA8445) remains repressible by glucose, but irreversible by cAMP, suggesting cAMP-CAP complex is not the exclusive mediator of the catablite repression.(ABSTRACT TRUNCATED AT 250 WORDS)     

小蜉属小蜉亚属一新种：蜉蝣目：小蜉科

本文记述小蜉属小蜉亚属 subgenus Ephemerella Walsh 一新种,小蜉亚属种类多,全世界已知有40种左右,广布于北美、苏联、日本等国,但中国尚未发现,因此本文也是小蜉亚属在中国的首次报道。     

L-serine degradation in Escherichia coli K-12: cloning and sequencing of the sdaA gene.

A new mutant of Escherichia coli K-12 unable to grow with L-serine, glycine, and L-leucine has been isolated by lambda plac Mu insertion and shown to be deficient in L-serine deaminase activity. The corresponding gene, sdaA, has been cloned from a prototrophic strain, and the clone has been characterized and sequenced. The evidence is consistent with the hypothesis that sdaA is the structural gene for L-serine deaminase. However, other possibilities are also considered. No significant homology with previously reported DNA or protein sequences was detected.