Synthesis and secretion of serum gelsolin by smooth muscle tissue

Gelsolin is one of many actin binding proteins which regulate the structure of intracellular microfilaments. A secretory form of gelsolin, a protein also known as "actin depolymerizing factor" or "brevin," is present in animal sera. In the present studies, we: demonstrate that a 90-kDa secretory protein produced by chicken gizzard smooth muscle is serum gelsolin; show that chicken serum gelsolin, as compared with its mammalian counterparts, lacks 26 amino acid residues at its NH2-terminal end; show that gizzard smooth muscle devotes on the order of 100 times more of its total protein synthetic effort (about 1% of the total) to the production of serum gelsolin than does liver, a previously speculated major source of this protein; and give evidence that rat tissues which are rich in smooth muscle cells (blood vessels, uterine muscle) also produce serum gelsolin. Our work suggests that, in vivo, smooth muscle-containing tissues may be major producers of the serum form of this actin binding protein.     

Production of fumonisins by Fusarium moniliforme strains from various substrates and geographic areas.

Strains of Fusarium moniliforme from different geographic areas and from corn and other substrates were tested for the ability to produce fumonisins in culture. The test results indicate that the potential exists for production of fumonisins by such strains in agricultural commodities and other substrates in widespread geographic areas.     

Synthesis of apolipoprotein A1 in skeletal muscles of normal and dystrophic chickens

We recently observed that, around the time of hatching, chick skeletal muscles synthesize and secrete apolipoprotein A1 (apo-A1) at high rates and that reinitiation of synthesis of this serum protein to high levels occurs in mature chicken breast muscle following surgical denervation (Shackelford, J. E., and Lebherz, H. G. (1983) J. Biol. Chem. 258, 7175-7180; 14829-14833). In the present work we investigate the effect of avian muscular dystrophy on the synthesis of apo-A1 in chicken muscles. The relative rate of synthesis of apo-A1 and levels of apo-A1 RNA in mature dystrophic breast (fast-twitch) muscle were about 6-fold higher than normal, while synthesis of apo-A1 in breast muscles derived from 2-day-old dystrophic chicks was close to normal. These observations suggest that the elevated apo-A1 synthetic rate in mature dystrophic breast muscle results from a failure of the diseased tissue to "shut down" apo-A1 synthesis to the normal level during postembryonic maturation. Apo-A1 synthesis in the "slow-twitch" lateral adductor muscle of dystrophic chickens was found to be normal. Our work is discussed in terms of the apparent similarities between the effects of surgical denervation and muscular dystrophy on the protein synthetic programs expressed by chicken skeletal muscles.     

Regulation of apolipoprotein A1 synthesis in avian muscles

Until recently, liver and intestinal mucosa were believed to be the sole sites of synthesis of apolipoprotein A1 (Apo-A1), the major protein component of serum high density lipoprotein particles. We recently showed (Shackelford, J.E., and Lebherz, H.G. (1983) J. Biol. Chem. 258, 7175-7180) that chick breast muscle also synthesizes and secretes Apo-A1 but does so at high rates only around the time of hatching. In the present work, we investigate the regulation of synthesis of Apo-A1 in chicken muscles. 1) The primary translation product encoded for by muscle Apo-A1 mRNA is about 2600 daltons larger than the mature serum protein which is consistent with the idea that, like its mammalian liver counterpart, chick muscle Apo-A1 mRNA codes for an NH2-terminal extension (prepro segment) which is 24 amino acids long. 2) The developmentally regulated rise and fall in muscle Apo-A1 synthesis which occurs around the time of hatching is associated with a large accumulation followed by depletion of Apo-A1 mRNA molecules during this period. 3) Reinitiation of Apo-A1 synthesis to high levels in mature breast muscle occurred in vivo following surgical denervation and in vitro by maintaining breast muscle explants for several days in defined culture media. 4) Cardiac, but not smooth, muscles also synthesize and secrete Apo-A1 at high levels around the time of hatching. These and other observations are discussed in terms of possible regulatory "signals" which may control Apo-A1 synthesis in avian muscles.     

Phylogeny of Greya (Lepidoptera: Prodoxidae), based on nucleotide sequence variation in mitochondrial cytochrome oxidase I and II: congruence with morphological data

The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from nucleotide sequence variation across a 765-bp region in the cytochrome oxidase I and II genes of the mitochondrial genome. Most parsimonious relationships of 25 haplotypes from 16 Greya species and two outgroup genera (Tetragma and Prodoxus) showed substantial congruence with the species relationships indicated by morphological variation. Differences between mitochondrial and morphological trees were found primarily in the positions of two species, G. variabilis and G. pectinifera, and in the branching order of the three major species groups in the genus. Conflicts between the data sets were examined by comparing levels of homoplasy in characters supporting alternative hypotheses. The phylogeny of Greya species suggests that host-plant association at the family level and larval feeding mode are conservative characters. Transition/transversion ratios estimated by reconstruction of nucleotide substitutions on the phylogeny had a range of 2.0-9.3, when different subsets of the phylogeny were used. The decline of this ratio with the increase in maximum sequence divergence among taxa indicates that transitions are masked by transversions along deeper internodes or long branches of the phylogeny. Among transitions, substitutions of A-->G and T-->C outnumbered their reciprocal substitutions by 2-6 times, presumably because of the approximately 4:1 (77%) A+T-bias in nucleotide base composition. Of all transversions, 73%-80% were A<-->T substitutions, 85% of which occurred at third positions of codons; these estimates did not decrease with an increase in maximum sequence divergence of taxa included in the analysis. The high frequency of A<-->T substitutions is either a reflection or an explanation of the 92% A+T bias at third codon positions.