Feline leukemia virus: biochemical and immunological characterization of gag gene-coded structural proteins.

The major non-glycosylated structural proteins of feline leukemia virus have been isolated, and competition immunoassays have been developed for each. These proteins include the 27,000- to 30,000-molecular-weight major internal antigen designated p30, a 15,000-molecular-weight protein (p15), an acidic protein of 12,000 molecular weight (p12), and a highly basic 10,000-molecular-weight protein (p10). Immunologically and biochemically corresponding proteins of feline and murine leukemia viruses have been identified. and, on the basis of analogy to the known sequence of a prototype type C virus of mouse origin, the map order of the gag region of the feline type C viral genome has been tentatively deduced as NH2-p15-p12-p10-COOH. The demonstration of two feline leukemia virus gag gene-coded proteins, p15 and p12, expressed in the form of an uncleaved precursor in a mink cell line nonproductively transformed by feline sarcoma virus provides indirect support for the proposed sequence.     

Suppression of maltose-negative phenotype by a specific nuclear gene (PMU1) in the petite cells of the yeast Saccharomyces cerevisiae

Summary A small percentage of the primary petites isolated from strain 1403-7A-P1, constitutive for maltase synthesis, simultaneously lost the ability to utilize maltose and alpha-methylglucoside. Further studies showed that these primary petites were not stable with respect to maltose utilization. Approximately 30% of the secondary petites when isolated from the primary petites after vegetative growth were found to papillate on maltose plates. Tetrad analysis data revealed that a nuclear gene has reverted in these papillae, which is responsible for suppression of the maltose negative phenotype in primary petites. We have designated this nuclear gene as the PMU1 gene (petite maltose utilizer). The functional form of the PMU1 gene is required in addition to the MAL4 gene for both constitutive maltase synthesis and maltose utilization in cytoplasmic petite cells derived from strain 1403-7A-P1.     

Improved assay conditions for measurement of corpus allatum activity in vitro in the adult Colorado potato beetle, Leptinotarsa decemlineata

Assay conditions for the short-term, radiochemical, in vitro determination of the spontaneous rate of juvenile biosynthesis by isolated corpora allata from Leptinotarsa decemlineata have been further improved, permitting the measurement of juvenile hormone biosynthesis by individual pairs of corpora allata. The final incubation product has been identified as juvenile hormone III with the aid of High-performance liquid chromatography (HPLC) and juvenile hormone esterase degradation. Using the new assay conditions, the activities of adult corpora allata during maturation were found to be significantly higher in reproductive, long-day animals than in pre-diapause, short-day beetles. During diapause no activity was detectable, whereas corpora allata from post-diapause beetles were reactivated totally after 5 days. Simultaneous determination of the in vitro rates of juvenile hormone biosynthesis and corpus allatum volumes revealed no clear correlation although the results suggest that the volume may be indicative of the maximal capacity for juvenile hormone production. Corpora allata from a population of beetles did not display any synchronous diurnal rhythmicity.     

Microbial transformation of sterols

Summary Arthrobacter simplex, Serratia marcescens, Fusarium and Mycobacterium were tested for their ability to transform phytosterol to Androsta 1, 4 diene 3, 17 dione (ADD). Arthrobacter simplex ATCC 6946 was found to be more efficient than the other species tested.     

A histochemical and ultrastructural study of heterogeneous red fibres of pigeon pectoralis muscle

The oxidative fibres of pigeon pectoralis muscle are 'type II red' on the basis of high myofibrillar adenosine triphosphatase (ATPase) and succinate dehydrogenase (SDH). The ATPase and SDH reactions do not characterize the heterogeneity of the red fibres in the normal pigeon pectoralis. Therefore, lipid, glycogen, phosphorylase, glycogen synthetase, SDH and ATPase reactions were studied in transverse sections of the pigeon pectoralis red fibre. This study has revealed the existence of an inherent heterogeneity between these red fibres. Three sub-populations distinguished were : (1) 'red1' fibres showing low fat but high glycogen and enzymes of glycogen metabolism (EGM); (2) 'red2' fibres displaying higher fat and higher amount of glycogen and EGM; and (3) 'red3' fibres possessing higher fat but lower content of glycogen and EGM. Ultrastructurally, one category of fibres (presumably red2 and red3) showed a higher concentration of fat; these fibres presumably possess higher synthetic capacity and lower (or higher?) utilization. Other mitochondria-loaded red fibres (presumably red1) documented here for the first time, showed fewer and smaller fat droplets indicating that they are 'predominantly lipid utilizers' and are incapable of storing large quantities of lipid. Moreover, the differing histochemical-ultrastructural attributes are presumably correlated with differences in levels of energetic metabolism, heat production and motor units of the red fibres.     

Enzyme Profiles in Seedling Development and the Effect of Itaconate, an Isocitrate Lyase-directed Reagent

Changes in levels of isocitrate lyase, malate synthase, and catalase have been investigated during germination of flax (Linum usitatissimum L.) in the presence and absence of itaconate. Germination was accompanied by a rapid increase in these enzymes during the first 3 days. The presence of 38 millimolar itaconate inhibited the incidence of seed germination and the growth of embryo axes as well as the appearance of isocitrate lyase but did not alter the levels of malate synthase, catalase, or NADP⁺-isocitrate dehydrogenase. The specific activity for the latter enzyme was constant throughout germination. Oxalate or succinate, each at 38 millimolar, had no effect upon germination of flax seeds. Itaconate did not inhibit the activities of malate synthase, catalase, or NADP⁺-isocitrate dehydrogenase in vitro but was a potent noncompetitive inhibitor of isocitrate lyase (K_i:17 micromolar at 30 C, pH 7.6). Itaconate (at 38 millimolar) did not alter the appearance of malate synthase but reduced the incidence of germination, onset of germination, and growth of the embryo axis as well as the specific activity of isocitrate lyase in seedlings of Zea mays, Vigna glabra, Glycine hispida, Vigna sinensis, Trigonella foenumgraecum, Lens culinaris, and Medicago sativa. The incidence and onset of germination of wheat seeds were unaltered by the same concentration of itaconate but seedlings did not contain isocitrate lyase or malate synthase. The data suggest that itaconate may be isocitrate lyase-directed in inhibiting the germination of fatty seeds.     

Examining serological diversity of “cowpea” rhizobia by the ELISA technique

To appraise the usefulness of the enzyme-linked immunosorbent assay (ELISA) technique for examining the serological diversity of slow-growing rhizobia, twelve diverse strains from three countries were examined with four antisera. Eleven of the strains were from the cowpea miscellany, and the twelfth was a Rhizobium japonicum strain. Some cowpea strains showed no antigenic relatedness with each other while others were closely related, and some showed a greater affinity with the R. japonicum strain than with other cowpea strains. All of the strains showed antigenic homology to an isolate from a wild Arachis sp., while two strains isolated from adjacent plants of the same cultivar had little homology. These patterns ofrelatedness and diversity clearly demonstrated the utility of the ELISA method, and so it was used to examine 53 strains isolated from cowpeas grown at three West African locations, Maradi (Niger), Ibadan and Onne (Nigeria). Broad ranges of serological diversity were found in the rhizobia at each location, moreover each population had its own general characteristics. Maradi strains were highly reactive with the five antisera used, Onne strains less so, and Ibadan strains even less so. ELISA reactivity correlated with colony morphology but not with nodulation potential.     

Localization of HLA on the short arm of chromosome 6

Summary A detailed marker gene study in a large Dutch kindred segregating for a reciprocal translocation between the chromosomes 6 and 20, t(6;20) (p21;p13), revealed a close linkage between the HLA genes and the breakpoint on the short arm of 6. During this study an apparent peak lod score of 2.9 was obtained at a recombination value of 0.05 for a linkage between HLA and the breakpoint, indicating that the chromosomal region, carrying the HLA genes, is situated near the breakpoint in band 6p21 close to the transition to 6p22.     

The behaviour of pigment cells in the leg muscle compartments of Silver Campine fowl

The presence of pigment cells in the leg muscle of Silver Campine fowl is ascertained. Transverse sections of legs of 16 and 21 day embryos gave similar results. Analysis of the states of differentiation indicates three types of pigment cells contained by the leg muscles. The relationship between the tissue environment and the melanoblast differentiation is discussed.