Interaction of rat testis protein, TP, with nucleosome core particle

Circular dichroism studies have revealed that addition of testis specific protein, TP in vitro, to rat testes nucleosome core particle resulted in a decrease in the compaction of the core particle DNA. This was also corroborated by thermal denaturation analysis. Addition of TP to nucleosome core particle resulted in the conversion of a biphasic transition towards a single phase. However, at the same time there was a 20% reduction in the overall hyperchromicity of core particle DNA at core particle to TP molar ratios of 1:2 and 1:3. These observations along with our earlier report, showing the DNA melting properties of TP, suggest that TP may play an important role in the disassembly process of nucleosome core particle during spermiogenesis.     

Directed metabolic flow with high butanol yield and selectivity in continuous cultures ofClostridium acetobutylicum

Summary This work addresses the problem of stable butanol formation byClostridium acetobutylicum in continuous culture. Sustained altered electron flow was observed in the presence of benzyl viologen which serves to redirect carbon flow towards primarily butanol formation. A yield of butanol of over 0.28 g.g^–1 glucose was obtained and butanol comprised over 90% of the total solvents formed. Additionally, acid formation decreased significantly with butyric acid as the dominant acid end product.     

Structural similarities among the high molecular weight protein fractions of oilseeds

Data on the physico-chemical properties of proteins from soybean, groundnut, sesame seed, sunflower seed, safflower seed, mustard seed, rapeseed and cotton seed are fairly extensive. An examination of the available data on high molecular weight proteins suggests that there are similarities in many of their properties. In this report the similarity in amino acid composition, size and shape, molecular weight, secondary structure, subunit composition, association-dissociation at high and low pH, stability towards denaturants, hydrolysis by enzymes and quaternary structure of the high molecular weight proteins is discussed. Based on these similarities a model has been proposed for the associationdissociation, denaturation and reassociation behaviour of the high molecular weight proteins of oilseeds.     

Isolation and identification ofMicrococcus roseus andPlanococcus sp. from schirmacher oasis,antarctica

Five cultures isolated from soil samples collected in Schirmacher oasis, Antarctica, have been identified as members of the familyMicrococcaceae, with 3 belonging to the genusMicrococcus and two toPlanococcus. The 3Micrococcus isolates (37R, 45R and 49R) were red-pigmented and h a d ∼ 75 mol% G + C in their DNA; they were identified asMicrococcus roseus. The twoPlanococcus isolates (30Y and Lz3OR) were yellow and orange in colour, and had 43.5 and 40.9 mol % G + C in their DNA respectively; they were identified asPlanococcus sp.     

Ankylosis of hock joints in group caged male B6C3F1 mice

Enlarged hock joints were observed during 1983 in B6C3F1 mice of chronic toxicity and carcinogenicity studies sponsored by the National Toxicology Program (NTP). Subsequently, approximately 9,500 B6C3F1 mice on 32 NTP chemical toxicity and carcinogenicity studies were evaluated for this condition by clinical examination. Group caged male B6C3F1 mice had thickening and reduced mobility of the hock joints at prevalences of 1.2% up to 6 months of age; 23% at 6 to 12 months of age; and 62% at 13 to 26 months of age. Group caged female B6C3F1 mice had a prevalence of 2% or less. Histologically, affected mice had periarticular exostoses on the bones of the hock joints, with formation of bony bridges around joints and deposition of new bone in joint spaces, resulting in partial or complete ankylosis. Individually caged male and female B6C3F1 mice were not affected. The cause of the ankylosis was not determined, but its occurrence in the NTP studies has been reduced by individual caging.     

X-linkage of malic enzyme in Anopheles culicifacies species B

A survey for malic enzyme (Me) in laboratory strains of species A and species B of Anopheles culicifacies had uncovered two electrophoretic variants, slow and fast, in two strains of species B. Genetic analysis revealed the two variants to be codominant alleles segregating at a locus, Me, which is sex linked. Because of the XX-XY sex determining mechanism, in F1 females, two electromorphs, viz., slow and fast, were observed, whereas in males only one electromorph of maternal origin was seen. Linkage experiments with another X-linked mutant, white eye (w), indicated the map distance between the two loci to be 9.52 +/- 0.86.     

Determination of effective diffusivity of substrate in biological films and particles

Summary Particle supported biofilms of uniform thickness were generated in an aerobic fluidized-bed reactor with phenol as the carbon source. A method was developed for determining the effective diffusivities of oxygen and phenol using trypan blue, a vital stain as the tracer. The effective diffusivities of oxygen and phenol were found to be 2.72×10^–6 cm²/s and 1.12×10^–6 cm²/s respectively.Nomenclature C_i initial solute concentration in bulk, g/cm³ - C_t solute concentration in bulk at time t, g/cm³ - C bulk solute concentration at equilibrium, g/cm³ - D molecular diffusivity, cm²/s - D effective diffusivity, cm²/s - D_o D_p D_tb molecular diffusivity of oxygen, phenol and trypan blue, cm²/s - D_o, D_p, D_tb effective diffusivity of oxygen, phenol and trypan blue, cm²/s - D_s molecular diffusivity of substrate, cm²/s - D_s effective diffusivity of substrate, cm²/s - K partition coefficient - M_t amount of solute in the particle at time t, g - M amount of solute in the particle at equilibrium, g - r particle radius, cm - r _bp radius of the particle with biofilm, cm - S substrate concentration, g/cm³ - S_b substrate concentration in bulk, g/cm³ - S_i initial substrate concentration, g/cm³ - V₁ solute molar volume, cm³/g mol Greek Symbols bf porosity of the biofilm - tortuosity factor     

东南亚和云南爬行动物区系的一致性及其起源和演化

云南与川、黔、贵等邻近省区都属于东南亚的一部分。依据爬行动物分布范围广的特点,把云南爬行动物区系起源和演化与东南亚甚至南亚的爬行动物作为一个整体进行研究,可能为解决东南亚及云南爬行动物某些类群的起源这一共同性问题,提供一些有用的资料。 本文将印度半岛、东南亚及其邻近岛屿现生爬行动物与世界范围的相同科级阶元的分布进行比较,并以古地质、古地理演变资料推论科级阶元同祖先起源地的大致范围。在此基础上,再将印度半岛、中南半岛和邻近岛屿,云南高原及邻近地区爬行动物的科属种进行比较,以探讨地区间差异的规律性。运用新构造运动和古气候变化观点阐明其物种或类群的迁移规律及其变化原因。     

RNA-DNA hybridization promoted by E. coli RecA protein.

RecA protein of E. coli plays a central regulatory role that is induced by damage to DNA and results in the inactivation of LexA repressor. In vitro, RecA protein binds preferentially to single-stranded DNA to form a nucleoprotein filament that can recognize homology in naked duplex DNA and promote extensive strand exchange. Although RecA protein shows little tendency at neutral pH to bind to RNA, we found that it nonetheless catalyzed at 37 degrees C the hybridization of complementary RNA and single-stranded DNA sequences. Hybrids made by RecA protein at 37 degrees C appeared indistinguishable from ones prepared by thermal annealing. RNA-DNA hybridization by RecA protein at neutral pH required, as does RecA-promoted homologous pairing, optimal conditions for the formation of RecA nucleoprotein filaments. The cosedimentation of RNA with those filaments further paralleled observations made on the formation of networks of nucleoprotein filaments with double-stranded DNA, an instrumental intermediate in homologous pairing in vitro. These similarities with the pairing reaction support the view that RecA protein acts specifically in the hybridization reaction.     

Propagation of banana through encapsulated shoot tips

Plants were regenerated from encapsulated shoot tips of banana. Shoot tips (ca 4 mm) isolated from multiple shoot cultures of banana cv. Basrai were encapsulated in 3% sodium alginate containing different gel matrices. The encapsulated shoot tips regenerated in vitro on different substrates. Use of White's medium resulted in 100% conversion of encapsulated shoot tips into plantlets. The plantlets were successfully established in soil.Abbreviations BA Benzylaminopurine - NAA Naphthalene acetic acid - DMSO Dimethyl sulphoxide