Dexamethasone-induced phospholipase A2-inhibitory proteins (PLIP) influenced by the H-2 histocompatibility region

Recent work has indicated that the H-2 histocompatibility complex on chromosome 17 influences the degree of glucocorticoid-induced teratogenicity and anti-inflammatory response. Since both of these hormonal actions appear to be mediated by the induction of phospholipase A2-inhibitory proteins (PLIP), the influence of the H-2 complex on the induction of PLIP by glucocorticoids in thymocytes and embryonic palates has been investigated. Analysis of dexamethasone-induced PLIP by Sephadex G-100 revealed four peaks of mol wt 55,000, 40,000, 28,000 and 15,000 in mouse thymocytes and from one to three of these PLIPs in mouse embryonic palates. The 55,000 mol wt PLIP comprised 50-60% of the total activity. The total amount of dexamethasone-induced PLIP is significantly higher in B10.A (H-2a) thymocytes than that in thymocytes of their congenic resistant partners, B10 (H-2b). The induced level of PLIP in the embryonic palates treated with dexamethasone is also significantly higher in the H-2a congenic strains with either the A or B background (AWy or B10.A) than that in their resistant partners (A.BY or B10). Thus, both susceptibility to glucocorticoid-induced cleft palate and the production of PLIP by this hormone are influenced by the H-2 complex.     

Selection of diverse genotypes for heterosis in yield and response in toria (Brassica campestris L.)

Summary Thirty-one genotypes of toria (Brassica campestris L.) were grown in twelve environments and subsequently analysed in order to select potential parents which expressed diversity for both 12 different characters (estimated by Mahalanobis' D² technique) and response to the environments (estimated on the basis of negative correlation between deviations in seed yield of a pair of genotypes from their respective environmental means). Coefficients of determination (r²) were also used to measure the reliability of correlation, which is the basis of diversity of response. Stability parameters (b and S²d) and mean seed yield were also considered in selecting potential parents. On the basis of these criteria, three pairs of genotypes (ITSA and TCSU-1, TCSU-7 and TH-8 and Ludhiana Composite-1 and TH-4) are recommended to be used as parents for hybridization programmes so that heterosis both in seed yield and response may be exploited.     

Detection of antimycin-binding subunits of Complex III by photoaffinity-labeling with an azido derivative of antimycin

Deformamidoazidoantimycin A (DAA), a photoactive derivative of antimycin A containing an azido group substituting for the formamido group attached to the phenyl ring, was synthesized. The ultraviolet spectrum of DAA was almost identical to that of antimycin A, indicating little alteration of the electronic structure of the substituted phenyl ring by the azido substitution. However, the inhibitory effectiveness of DAA toward ubiquinol-cytochromec reductase (Complex III) purified from bovine heart (K _i =ca. 0.5 µM) was considerably less than that of antimycin (K _i 3 pM), indicating a direct rather than a supporting role of the formamido group in the inhibitory activity of antimycin. Exposure of purified Complex III to [³H]DAA plus ultraviolet light caused a major labeling by tritium of SDS-PAGE band 7 (m=13 kDa by SDS-PAGE) and lesser but significant labeling of bands 3, 6, 8, and 9. Pretreatment of Complex III with antimycin greatly suppressed the labeling of bands 5, 6, and 7 but caused an apparent increased labeling of bands 8 and 9 by [³H]DAA, respectively. The labeling of band 7 by [³H]DAA also was strongly suppressed by reduction of Complex III by either sodium borohybride or ascorbate. Based on magnitude of labeling by [³H]DAA and the degree of suppression of labeling by antimycin, the protein of band 7 qualified as the principal component for specific binding of antimycin with the protein of band 6 (m=16 kDa) showing a lesser but significant amount of specific binding.     

Callus initiation and plant regeneration in ragi (Eleusine coracana Gaertn.)

Callus was successfully initiated on root, mesocotyl and leaf base segments of 3- to 4-day-old seedlings of ragi (Eleusine coracana Gaertn.). 2,4-D along with casein hydrolysate for Murashige and Skoog's basal medium was found to be most effective for callus initiation and maintenance. Mesocotyl and leaf base tissue derived calli gave shoot buds in medium in which the 2,4-D concentration was lowered.     

Identification of a phosphoenolpyruvate:fructose 1-phosphotransferase system in Azospirillum brasilense

An inducible phosphoenolpyruvate:fructose phosphotransferase system has been detected in Azospirillum brasilense, which requires a minimum of two components of the crude extracts for activity: (i) a soluble fraction (enzyme I) and (ii) a membrane fraction (enzyme II). The uninduced cells neither show any uptake of fructose nor express activity of either of these two enzyme fractions. C-1 of fructose is the site of phosphorylation. This phosphotransferase system does not accept glucose as a substrate for phosphorylation.     

Studies on mitotic and salivary chromosomes of Dacus cucurbitae Coquillett (Diptera: Trypetidae)

Dacus cucurbitae is a serious pest of various types of fleshy fruits and vegetables. The mitotic and salivary chromosomes were reinvestigated using the air-drying and different (C-and H-) banding techniques with a view to rectify the existing controversy regarding the Indian populations of this species. A standard map of its salivary chromosomes was constructed and some important identifiable landmarks were recognized in each arm.     

DNA sequence organization in the genomes of three related millet plant species

Summary A major portion of the genomes of three millet species, namely, barn yard millet, fox tail millet and little millet has been shown to consist of interspersed repeat and single copy DNA sequences. The interspersed repetitive DNA sequences are both short (0.15–1.0 kilo base pairs, 62–64% and long (>1.5 kilo base pairs, 36–38%) in barn yard millet and little millet while in fox tail millet, only long interspersed repeats (>1.5 kilo base pairs) are present. The length of the interspersed single copy DNA sequences varies in the range of 1.6–2.6 kilo base pairs in all the three species. The repetitive duplexes isolated after renaturation of 1.5 kilo base pairs and 20 kilo base pairs long DNA fragments exhibit a high thermal stability with Tms either equal to or greater than the corresponding native DNAs. The S1 nuclease resistant repetitive DNA duplexes also are thermally stable and reveal the presence of only 1–2% sequence divergence.The present data on the modes of sequence arrangement in millets substantiates the proposed trend in plants, namely, plants with 1C nuclear DNA content of less than 5 picograms have diverse patterns of sequence organization while those with 1C nuclear DNA content greater than 5 picograms have predominantly a short period interspersion pattern.Abbreviations kbp kilobase pairs NCL Communication No. 3606.     

Mobilization of cloned luciferase genes into Vibrio harveyi luminescence mutants

A recombinant plasmid which carried a 5 kb fragment of Vibrio harveyi DNA containing the luxA and luxB genes was mobilized from Escherichia coli into luminescence-deficient mutants of V. harveyi. The cloned genes complemented a temperature sensitive luciferase mutation, but failed to complement lesions in two different aldehyde deficient mutants. Expression of the cloned genes was not subject to autoinduction in either E. coli or in V. harveyi.     

Separation of hemoglobin types by cation-exchange high-performance liquid chromatography

The use of a recently developed cation-exchange HPLC packing material for the separation of hemoglobin types in human blood has been investigated. Adult and newborn hemolysates from normal individuals and from subjects with hemoglobin disorders were analyzed using a weak cation carboxymethyl-bonded phase on 5-micron-particle-size silica. Elution was accomplished using a Bistris (2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)-1, 3-propanediol) gradient. Seven well-resolved HbA1 fractions eluted before the major HbA peak. Hbs A1a, A1b, A1c and an HbA1 fraction that increased with aging of the hemolysates were separately eluted. HbF when present or when added to the hemolysates eluted as a distinct peak. HbA was followed by Hbs A2, S, and C when present. An early-eluting peak corresponding to Hb Bart's was identified in newborn hemolysates. It is concluded that cation-exchange HPLC provides a new tool for the reliable separation of minor hemoglobin components.