Interactions of an acid tolerant strain of phosphate solubilizing bacteria with a few acid tolerant crops

Phosphate solubilizing bacteria (PSB) were isolated from sixty soil samples of various soil classes and cropping histories in Himalayan regions of Uttar Pradesh, India by enrichment culture techniques. Phosphate solubilization and acid tolerance of each strain was estimated. A strain (PAS-2) isolated froma pasture and waste land of pH 4.8, organic matter 2.6% available N 265kg ha^-1, available P₂O₅(Bray's II) 2.3kg ha^-1 and available K₂O 353 kg ha^-1 had the highest P-solubilization (45 µg P per mL per day) and also highest acid tolerance rating 42. The strain was identified as Bacillus sp. Seed inoculation of this bacterial strain resulted in significant increases in grain and vegetative yield of fingermillet (Elosine coracana), maize (Zea mays), amaranth (Amaranthus hypochondriacus), buckwheat (Fagopyrium esculentum), frenchbean (Phaseolus vulgaris) with or without added P sources. The significant grain yield (quintol ha^-1) with phosphate and seed inoculation ranged from 33.85 in maize, 26.33 in frenchbean, 22.41 in buckwheat, 20.71 in amaranth and 19.19 in fingermillet as compared to controls. The highest response was observed with frenchbean followed by fingermillet, buckwheat, amaranth and maize. Phosphate use efficiency was highest in frenchbean followed by maize and lowest and almost at par in buckwheat, amaranth and fingermillet. Available phosphate was also highest in frenchbean cultivated plot followed by amaranth, fingermillet, buckwheat and maize. The MPN count of phosphate solubilizing bacteria were also influenced by seed inoculation of strain PAS-2. Frenchbean exerted greaterrhizosphere effect followed by pseudocereals and cereals. Likewise, phosphate nutrition of crops were also improved through seed inoculation irrespective of added P sources. The study thus demonstrated that selection of efficient strain of PSB from acid soil and its seed inoculation in selected crop genotype is beneficial in boosting up crop yield in low productive hill soil. Seed inoculation also created greater rhizosphere effect over uninoculation which improved P-nutrition of crops and also available soil P.     

南洋楹根瘤菌的分离和特性

从南洋楹新鲜根瘤中分离得到根瘤菌菌株8638,再经稀释分离,挑取不同形态的菌落,经连续单菌落纯化,获得8638L、8638M和86385三株菌落型．对它们的形态特征、培养性状、生长速度、生理生化特性进行观测．并对它们回接南洋楹后的结瘤状况和共生固氮活性,以及在自生条件下固氮酶和吸氢酶活性作了测定．     

抗人IgM单克隆抗体的研究—脾内免疫建立抗人IgM单克隆抗体杂交瘤细胞株

用多发性骨髓瘤病人血清中提纯的ＩｇＭ抗原,用脾内免疫ＢＡＬＢ／ｃ小鼠后与Ｓｐ２／Ｏ骨髓瘤细胞融合,获得了７株分泌人ＩｇＭ单克隆抗体的杂交瘤细胞株,分别命名为２５Ｇ１、２５Ｇ３、２５Ｇ４、２５Ｇ５、２５Ｄ２、２５Ｄ３和２５Ｄ５。注射同系小鼠后可诱生含较高效价抗人ＩｇＭ腹水（ＰＨＡ＝１２１２）。该杂交瘤细胞经组织培养传代半年,冻存１４个月后复苏,其分泌ＩｇＭ性能稳定。用ＰＨＡ、ＥＬＩＳＡ做人ＩｇＭ、ＩｇＧ、ＩｇＡ阻断试验,仅ＩｇＭ可阻断。用琼脂糖双扩散证明其与羊抗人ＩｇＭ有共同沉淀线     

酪氨酸酶高产菌株的快速、简便筛选方法

报道了用含酪氨基酸的平板和培养液筛选高产酪氨酸酶菌株的方法。     

中国两性生殖卤虫种群MDH同工酶基因的表达

采用聚丙烯酰胺凝胶垂直板电泳法对中国两性生殖卤虫12个品系的苹果酸脱氢酶(MDH)同工酶基因的表达进行了研究。实验结果表明:(1)由于一些MDH同工酶基因所编码产生的亚基相互结合的频率较低,故没有得到理论上应得到的基因型数;(2)存在品系内和品系间的多态现象;(3)A. sini ca与A.parthenogenet ica之间存在高度的遗传变异和分化,另外,二者间具有相同的基因型和较高的遗传相似系数值也说明二者间存在一定的亲缘关系。 Abstract:Expression of malate dehydrogenase isozymic genes of 12 bisexual Artemia strains from China was strudied by means of polyacrylamide gel electrophorsis method.The experimental results showed are as follows,(1)Because of low frequency of some isozymic subunits combining each other and small number of experimental samples,we did not get the theoretical number of genotype that should appeare;(2)A.sinaca and A.parthenogenetica have characteristic MDH isozymic patterns,this provides precise biochemical index for distinguishing different Artemia strains;(3)MDH isozyme in 12 bisexual Artemia strainis is polymorphic.     

Random mutagenesis in the large extrinsic loop E and transmembrane α-helix VI of the CP 47 protein of Photosystem II

The intrinsic chlorophyll-protein CP 47 is a component of Photosystem II which functions in both light-harvesting and oxygen evolution. Using the Escherichia coli mutator strain XL-1 Red, we introduced mutations at 14 sites in the large extrinsic loop E of CP 47 and its adjacent transmembrane -helix VI. Four mutant cell lines were recovered in which the histidyl residues 455H, 466H and 469H were altered. The cell lines H455T, H455Y, H469Y, and the double mutant F432L,H466R exhibited phenotypes that supported the identification of the histidyl residues 455H, 466H and 469H as chlorophyll ligands. Four additional mutant cell lines were recovered which contained mutations at positions 448R in the large extrinsic loop of CP 47. These mutants, R448K, R448Q, R448S, and R448W, exhibited variable phenotypes ranging from moderate alteration of photoautotrophic growth and oxygen evolution rates to a complete inhibition of these parameters. Those mutants exhibiting photoautotrophic growth and oxygen evolution capability under standard conditions were unable to grow photoautotrophically or evolve oxygen when grown at low chloride concentrations. Finally, a mutant cell line exhibiting a substitution at position 342G was recovered. The mutant G342D exhibited moderate alterations of photoautotrophic growth and oxygen evolution. In addition to these alterations, mutants were recovered in which deletions and insertions (leading to frame shifts) and stop codons were introduced. These mutants uniformly lacked the ability to either grow photoautotrophically or evolve oxygen.     

REAPPRAISAL OF PHYSIOLOGICAL ATTRIBUTES OF NINE STRAINS OF DUNALIELLA (CHLOROPHYCEAE): GROWTH AND PIGMENT CONTENT ACROSS A SALINITY GRADIENT

Among the few taxonomic characters used to circumscribe sections within the subgenus Dunaliella are the physiological response to changes in salt concentration, which define a specific range for optimal growth, and the carotenogenic ability of the vegetative cells, responsible for the change in cell color from green to orange or red, under suboptimal culture conditions. Previous work based on molecular data from seven taxa of different sections of the subgenus showed no correlation between the genetic relationship inferred from the internal transcribed spacer RFLP data and the morphophysiological attributes in use in taxonomy. The present work was performed to experimentally reevaluate the physiological attributes in the same seven previous taxa ( D. tertiolecta Butcher UTEX 999 and CCMP 1320, D. parva Lerche UTEX 1983 and CCMP 362, D. salina Teodoresco UTEX 200, D. viridis Teodoresco CONC 002, and D. peircei Nicolai et Baas Becking UTEX 2192) adding D. parva CCAP 19/9 and D. pseudosalina Massyuk et Radchenko CONC 010. Growth responses and pigment content in a wide range of NaCl concentrations were assessed. The results revealed that two strains of D. parva , two strains of D. tertiolecta , and one strain of D. peircei showed similarity in their growth responses to the whole range of salt concentrations. Dunaliella parva UTEX 1983, on the other hand, showed a growth rate pattern very different from those of their conspecifics and similar to those of D. viridis CONC 002 and D. salina UTEX 200. In relation to the pigment content, none of the strains turned orange or red in color under the whole range of salt concentrations assayed, and the total carotenoids to chlorophyll ratios were always lower or equal to 1.0. These results reaffirm the validity of the physiological attributes used to discriminate sections within the subgenus Dunaliella and show correlation with the previous molecular data, but stress the need for relocating some strains into different sections.     

Scrapie strain infection in vitro induces changes in neuronal cells

PC12 cells, in the presence of nerve growth factor (NGF), support replication of the mouse-derived scrapie strains 139A and ME7, with the former yielding 100–1000-fold higher levels of infectivity. Infectivity remained cell-associated and cells did not show any gross morphological alterations, although changes were observed by electron microscopy in the form of an increased number of lipid droplets in 139A-infected cultures. Analysis of phospholipid metabolism in 139A infected cells indicated that scrapie replication did not change the inositol phosphate levels, but did stimulate phosphoinositide synthesis. Replication was not detected in PC12 cells infected with either the hamster-derived 263K or rat-derived 139R scrapie strains. Since scrapie-infected cultures did not exhibit cell death or any gross changes, any scrapie-induced effects would probably be manifested in nonvital cellular functions. When compared to controls, infection with the 139A scrapie strain resulted in decreased activity of the cholinergic pathway-related enzymes, as well as the GABA synthetic pathway; however, the adrenergic pathway was unaffected by scrapie infection. The effects of the 139A scrapie strain on the cholinergic system appeared to be dose-dependent and were first detected prior to the detection of scrapie agent replication in these cells. No neurotransmitter-related enzymatic changes were detected in 263K- or 139R-infected PC12 cells. The enzymatic changes observed in ME7-infected PC12 cells and in Chandler agent-infected mouse neuroblastoma cells suggest that the significant changes in neurotransmitter levels in cultures exhibiting low infectivity titers must involve factors other than, but not excluding, replication of the agent. The role of additional factors is also suggested in studies of protein kinase C activity in 139A- and 139R-infected PC12 cells. These studies emphasize the value of the PC12 cell model system in examining the scrapie strain-host cell interaction and, in addition, support the concept of variation among scrapie strains.     

TheN haplotype of the murineβ-glucuronidase gene is altered in both its systemic regulation and its response to androgen induction

A new haplotype of the -glucuronidase gene complex, [Gus]^N, has been characterized following its transfer from the PAC/Cr strain to the standard strain C57BL/6J. TheN haplotype contains a novel structural gene allele which encodes an allozyme differing from all previously characterized allozymes in both size and charge. Altered systemic regulation is exhibited by the [Gus]^N haplotype. Multiple tissues contain levels of GUS protein that are 60±15% those found in the standardB haplotype. The regulatory mechanism for reduction is complex, involving tissue-specific changes in both enzyme synthesis and enzyme turnover. The changes in GUS protein synthesis do not result from changes in GUS mRNA levels. Instead, the amount of mature enzyme formed per mRNA molecule, or translational yield, is altered. These regulatory changes parallel those seen in other systemic regulatory variants of GUS which are also altered in translational yield. A commonality of mechanism among systemic regulatory variants of this gene is suggested. TheN haplotype is also exceptional in the nature of its response to androgenic induction in kidney proximal tubule epithelial cells. The time course for GUS induction consists of a lag period followed by a progressive increase in mRNA, rate of enzyme synthesis, and enzyme activity. For the [Gus]^N haplotype the lag is of an exceptionally short duration and the plateau is of a greater magnitude than for any haplotype previously described.This work was supported by United States Health Service Research Grant GM 31656.