Cytogenetic Definition and Morphogenetic Analysis of Delta, a Gene Affecting Neurogenesis in Drosophila Melanogaster

We have conducted a genetic analysis of a small interval of the third chromosome known to include Delta (Dl), a locus that affects the segregation of the ectoderm into neural and epidermal lineages during embryogenesis and the morphogenesis of some ectodermally derived structures, in Drosophila melanogaster. This analysis has led to the definition of seven independent complementation groups, one of which is Delta, within the interval extending from 91F6-13 to 92A2. Among the extant mutations in these seven loci, only mutations in Dl lead to the so-called neurogenic phenotype: hypertrophy of the nervous system and reduction of the epidermis. Combined cytogenetic and genetic analyses allow us to define absolute proximal (91F5-92A1) and distal (92A2) cytogenetic limits for the Dl locus. We have isolated hypomorphic and amorphic alleles of Dl and find that, for any given allele, there is an inverse correlation between neural hypertrophy and epidermal reduction in embryos and a direct correlation between the severity of embryonic phenotypes in mutant homozygotes and hemizygotes and the imaginal phenotype in heterozygous adults.     

Growth hormone regulates the abundance of insulin-like growth factor I RNA in adult rat liver

Insulin-like growth factor I (IGF-I) is a mitogenic polypeptide present in the plasma of man and rat that is thought to mediate the actions of pituitary growth hormone on cartilage to promote skeletal elongation. In the rat, plasma levels of IGF-I show both developmental and hormonal regulation: levels are low at birth, increase with age, and are decreased in growth hormone-deficient adult animals. The present study demonstrates that these changes in plasma IGF-I reflect the abundance of IGF-I RNA in rat liver. A human IGF-I cDNA probe hybridized to multiple RNA species in adult rat liver with sizes 8.6, 4.6, 3.2, 2.1, and 1.0-1.4 kilobases. These RNA species were decreased by greater than 80% in neonatal (2- and 12-day-old) rat liver and by greater than 90% in liver from adult rats made growth hormone-deficient by hypophysectomy. Treatment of hypophysectomized rats with growth hormone increased the abundance of all species of IGF-I RNA. These results suggest that growth hormone regulates the expression of its physiological mediator by altering the synthesis, stability, or both of IGF-I RNA in rat liver.     

Fermentation by a new daunomycin-producing organism, Streptomyces insignis ATCC 31913.

A new organism belonging to the grey series of streptomycetes is described which produces 55 to 75 micrograms of daunomycin per ml in a sparged fermentor. This organism is not taxonomically related to other known daunomycin producers. Its proposed name in Streptomyces insignis ATCC 31913.     

Wound-induced proteinase inhibitors from tomato leaves. I. The cDNA-deduced primary structure of pre-inhibitor I and its post-translational processing

A cDNA containing the coding region for the complete amino acid sequence of wound-induced proteinase Inhibitor I from tomato leaves was constructed in the plasmid pUC9 and characterized. The open reading frame codes for a protein of 111 amino acids. This deduced amino acid sequence revealed the presence of a 42-amino acid N-terminal sequence that is not found in the native protein. This sequence appears to contain a 23-amino acid segment typical of a signal sequence followed by a 19-amino acid sequence containing 9 charged amino acids. The 42-amino acid sequence is apparently lost during maturation to the native Inhibitor I and represents 38% of the translated protein. The Inhibitor I amino acid sequence contains 71% identity with potato tuber Inhibitor I sequence and 35% identity with an inhibitor from the leech.     

Isolation of enamelinlike proteins from blue shark (Prionace glauca) enameloid

A sequential dissociative extraction scheme was used to extract proteins from developing Blue Shark enameloid. The first extraction solution (4 M guanidine HC1) solubilized the polypeptides, mainly collagenous, not closely associated with the hydroxyapatite. The next extraction solution (4 M guanidine HC1, 0.5 M ethylenediaminetetraacedic acid (EDTA] solubilized the proteins more closely associated with the tooth mineral component. After extraction, the proteins were separated and isolated with gel electrophoresis. Protein molecular weights were determined and selected proteins were isolated for amino acid composition analysis. The two proteins isolated were tested for mammalian enamel protein antigenic determinants by a "Dot" immunobinding assay. The isolated proteins were enamelinlike by extraction criteria and amino acid composition. Further, the two proteins share antigenic determinants with mammalian enamel proteins.     

Transposon donor plasmids, based on ColIb-P9, for use in Pseudomonas putida and a variety of other gram negative bacteria

Summary The properties of pLG221, a derivative of the ColIb plasmid carrying the transposon Tn5 are described. This plasmid can be used to introduce Tn5 by conjugation from Escherichia coli into a variety of Gram negative bacteria outside the host range for maintenance of ColIb. Plasmid pLG221, and a similar plasmid pLG223 carrying Tn10 may be of general utility as vectors for transposon-mediated mutagenesis in a variety of Gram negative bacteria.     

Complementation of a pKM101 derivative that decreases resistance to UV killing but increases susceptibility to mutagenesis

The drug resistance plasmid pKM101 makes Escherichia coli resistant to the lethal effects of ultraviolet (UV) irradiation and more susceptible to mutagenesis by a variety of agents. The plasmid operon responsible for increasing mutagenesis has been termed mucAB (Mutagenesis, UV and chemical). We have isolated a derivative of pKM101 called pGW1975 which makes cells more sensitive to killing by UV but which retains the ability of pKM101 to increase susceptibility to methyl methanesulfonate (MMS) mutagenesis. pGW1975 increases UV mutagenesis less than pKM101 in a uvrA⁺ strain but more than pKM101 in a uvrA⁻ strain. muc⁻ point and insertion mutants of pKM101 and pGW1975 complement to restore the plasmid-mediated: (i) ability to reactivate UV-irradiated phage, (ii) resistance to killing by UV, and (iii) level of susceptibility to UV mutagenesis. We have identified a 2.0 kb region of pKM101 which is responsible for the complementation and which maps counterclockwise of mucAB.     

Decreased Exopolysaccharide Synthesis by Anaerobic and Symbiotic Cells of Bradyrhizobium japonicum

Experiments were conducted to determine whether symbiotic bacteroids of Bradyrhizobium japonicum produce exopolysaccharide within soybean (Glycine max [L.] Merr. cv `Lee 74') nodules. B. japonicum strains RT2, a derivative of USDA 110 with resistance to streptomycin and rifampicin, and RT176-1, a mutant deficient in exopolysaccharide synthesis, were used. Although aerobically cultured RT2 produced 1550 micrograms of exopolysaccharide per 10¹⁰ cells, root nodules formed by RT2 contained only 55.7 micrograms of polysaccharide per 10¹⁰ bacteroids, indicating that little exopolysaccharide synthesis occurred within the nodules. The polysaccharide level of RT2 nodules was about equal to that of nodules containing the exopolysaccharide mutant RT176-1 (61.0 micrograms per 10¹⁰ bacteroids). Gas chromatographic analysis showed that the sugar composition of polysaccharide from nodules of RT2 or RT176-1 was almost the same as that of polysaccharide from unnodulated root tissue, but differed strikingly from that of rhizobial exopolysaccharide from aerobic cultures. Thus, the host plant and not the bacteroids was probably the source of most or all of the polysaccharide in the nodule extracts. Also, bacteroids from nodules failed to bind soybean lectin, confirming the absence of an exopolysaccharide capsule.