Circulating steroid hormones during rapid aggressive responses of territorial male mountain spiny lizards, Sceloporus jarrovi

Levels of aggression and circulating steroid hormones were monitored simultaneously in free-living male lizards following a staged territorial aggressive encounter with another male. In the first 15 min following the aggressive encounter, the frequency of territorial patroling and the frequency of agonistic and advertisement displays increased four- to fivefold in resident males. In most cases these increases persisted for at least 90 min after withdrawal of the intruder male and probably persisted for the entire day of the encounter. Blood samples collected at 15-min intervals revealed no changes in circulating levels of testosterone or corticosterone while this behavioral change was occurring. Thus, the increase in aggressive behavior that follows a male-male territorial encounter in this species does not appear to be mediated by simultaneous changes in circulating levels of these hormones. Interspecific comparisons suggest that interspecific variation in steroid hormone involvement in rapid aggressive responses may depend on the mating system and the extent of male parental care.     

The effect of dihydrofolate reductase-mediated gene amplification on the expression of transfected immunoglobulin genes

Murine/human chimeric gamma 1 and K Ig genes were cloned adjacent to the gene coding for methotrexate-resistant dihydrofolate reductase. These constructs were introduced into myeloma cells, and lines containing stably integrated genes were selected. The integrated Ig genes were then amplified by selection of the cells in increasing concentrations of methotrexate. The extent of gene amplification, mRNA accumulation, and production of Ig was studied in transfectomas containing introduced light chain genes, heavy chain genes, or both. When the light chain gene was introduced alone, it was expressed at low levels, but after selection with methotrexate, light chain expression was increased as much as 63-fold. In contrast, the transfected heavy chain genes were highly expressed, but production of the corresponding protein was increased a maximum of only fourfold by methotrexate treatment. Cellular toxicity of unassembled heavy chain monomer was not observed, even at amounts equivalent to 2% of total cellular protein. Cointroduction of the heavy and light chain constructs with subsequent amplification resulted in as much as 25-fold increase in secretion of intact antibody relative to unamplified cells. The results demonstrate that amplification of Ig genes can induce transfectomas to secrete antibody at nearly the rate of hybridomas.     

Purification and Properties of Rubrophilin: A Novel Brain Specific Membrane Polypeptide

Rubrophilin, a unique brain specific polypeptide, was purified to apparent homogeneity from microsomal fractions of bovine brains. The peptide stains pink with Coomassie Brilliant Blue R-250 (C.I. No. 42660) under specific conditions, has an apparent Mr of 53,000, and is acidic with an apparent pI of 4.9. The purification involves initial solubilization of delipidated microsomes in sodium dodecyl sulfate, followed by ammonium sulfate fractionation, reversed ammonium sulfate gradient elution from diatomaceous earth, gel filtration on polyacrylamide (Biogel P-200), gradient elution chromatography from hydroxylapatite, and reverse-phase chromatography from phenyl-Sepharose. A yield of about 5 mg of rubrophilin was obtained from 9 g of microsomal proteins. Amino acid analysis shows that rubrophilin contains only nine amino acids with residues/mol as follows: alanine (102), glutamic acid (97), lysine (65), proline (55), aspartic acid (48), glycine (44), serine (37), threonine (35), and valine (10). Cysteine, methionine, tryptophan, tyrosine, isoleucine, phenylalanine, histidine, and arginine could not be detected. Relative rubrophilin content of vertebrate brains was as follows: mammals greater than birds greater than reptiles greater than fishes. It is present in mouse retina and human neuroblastoma cell cultures but could not be detected in octopus optic lobe or in cultured C-6 rat glioma cells.     

Characterization of root agravitropism induced by genetic, chemical, and developmental constraints

The patterns and rates of organelle redistribution in columella (i.e., putative statocyte) cells of agravitropic agt mutants of Zea mays are not significantly different from those of columella cells in graviresponsive roots. Graviresponsive roots of Z. mays are characterized by a strongly polar movement of 45Ca2+ across the root tip from the upper to the lower side. Horizontally-oriented roots of agt mutants exhibit only a minimal polar transport of 45Ca2+. Exogenously-induced asymmetries of Ca result in curvature of agt roots toward the Ca source. A similar curvature can be induced by a Ca asymmetry in normally nongraviresponsive (i.e., lateral) roots of Phaseolus vulgaris. Similarly, root curvature can be induced by placing the roots perpendicular to an electric field. This electrotropism increased with 1) currents between 8-35 mA, and 2) time between 1-9 hr when the current is constant. Electrotropism is reduced significantly by treating roots with triiodobenzoic acid (TIBA), an inhibitor of auxin transport. These results suggest that 1) if graviperception occurs via the sedimentation of amyloplasts in columella cells, then nongraviresponsive roots apparently sense gravity as do graviresponsive roots, 2) exogenously-induced asymmetries of a gravitropic effector (i.e., Ca) can induce curvature of normally nongraviresponsive roots, 3) the gravity-induced downward movement of exogenously-applied 45Ca2+ across tips of graviresponsive roots does not occur in nongraviresponsive roots, 4) placing roots in an electrical field (i.e., one favoring the movement of ions such as Ca2+) induces root curvature, and 5) electrically-induced curvature is apparently dependent on auxin transport. These results are discussed relative to a model to account for the lack of graviresponsiveness by these roots.     

Influence of microgravity on cellular differentiation in root caps of Zea mays

We launched imbibed seeds of Zea mays into outer space aboard the space shuttle Columbia to determine the influence of microgravity on cellular differentiation in root caps. The influence of microgravity varied with different stages of cellular differentiation. Overall, microgravity tended to 1) increase relative volumes of hyaloplasm and lipid bodies, 2) decrease the relative volumes of plastids, mitochondria, dictyosomes, and the vacuome, and 3) exert no influence on the relative volume of nuclei in cells comprising the root cap. The reduced allocation of dictyosomal volume in peripheral cells of flight-grown seedlings correlated positively with their secretion of significantly less mucilage than peripheral cells of Earth-grown seedlings. These results indicate that 1) microgravity alters the patterns of cellular differentiation and structures of all cell types comprising the root cap, and 2) the influence of microgravity on cellular differentiation in root caps of Zea mays is organelle specific.     

Cricket Paralysis Virus, a Potential Control Agent for the Olive Fruit Fly, Dacus oleae Gmel

Representatives of several families of insect viruses were tested for growth and pathogenicity in the olive fruit fly, Dacus oleae Gmel. The viruses included nuclear polyhedrosis viruses, an iridovirus, two picornaviruses, and Trichoplusia ni small RNA virus (a member of the Nudaurelia β family), in addition to two naturally occurring viruses of the olive fruit fly. Two viruses, one of the two picornaviruses (cricket paralysis virus [CrPV] and the iridovirus (type 21 from Heliothis armigera), were found to replicate in adult flies. Flies which were fed on a solution containing CrPV for 1 day demonstrated a high mortality with 50% dying within 5 days and nearly 80% dying within 12 days of being fed. The virus was transmissible from infected to noninfected flies by fecal contamination. The CrPV which replicated in the infected flies was demonstrated to be the same as input virus by infection of Drosophila melanogaster cells and examination of the expressed viral proteins, immunoprecipitation of the virus purified from flies, and electrophoretic analysis of the structural proteins.     

Isolation of Different Agrobacterium Biovars from a Natural Oak Savanna and Tallgrass Prairie

Populations of agrobacteria in excess of 10⁵ CFU/g were recovered from 12 soil and root samples obtained from the Allison Savanna, Minn., a natural oak savanna and tallgrass prairie which has never been disturbed agriculturally. Of 126 strains picked randomly from selective media, 54 were identified as Agrobacterium spp. Biovar 2 strains predominated (35 of 54), but these strains were distributed into three phenotypically distinct subgroups. Of the remaining Agrobacterium strains, four were biovar 1-2, one was biovar 1, and none were biovar 3. The last 14 Agrobacterium strains formed a homogeneous group which differed biochemically from the hitherto reported biovars. Opine utilization (coded for by genes on the tumor-inducing plasmid in pathogenic Agrobacterium spp.) by these agrobacteria was limited to two biovar 2 strains. In contrast, 10 nonfluorescent gram-negative strains utilized either nopaline or octopine as the sole carbon and nitrogen source. There may be a need to reexamine the source and role of opines in the terrestrial environment because (i) all of these opine utilizers were isolated from an environment free of crown gall, the only known terrestrial source of opines, and (ii) 83% of the opine utilizers were not Agrobacterium spp.     

Complementary Methodologies To Identify Specific Agrobacterium Strains

Serological techniques and restriction enzyme cleavage patterns of total DNA were used to differentiate strains of Agrobacterium spp. Forty-five wild-type and plasmid-cured Agrobacterium strains were tested by immunodiffusion and immunofluorescence against polyclonal antisera to a crude ribosome preparation from Agrobacterium strains K84, U11, B6, A323, NT1, and C58. In immunodiffusion gels, these antisera reacted only with water-phenol extracts of the homologous strain, producing a single, strain-specific precipitin line. In contrast, when the same antisera were used in immunofluorescence staining, cross-reactions occurred with a limited number of heterologous Agrobacterium strains. However, the cross-reacting heterologous cells fluoresced generally less brightly than the homologous cells. When the EcoRI-digested DNA profiles from the same Agrobacterium strains were compared, 34 distinct cleavage patterns were observed. The DNA profiles were the same for all strains sharing a common chromosomal background and correlated with the strain-specific serological reaction. The presence or absence of plasmid DNA did not alter the strain-specific serological reaction or the DNA cleavage patterns. Both the serological reaction and the restriction enzyme digestion of total DNA were complementary to each other. These methods were used successfully to identify A. radiobacter K84 strains which were recovered 6 months after being inoculated to young trees in the field.     

Mechanistic consequences of charge transfer systems in serine proteases and angiotensin: semiempirical computations

Structures and relative energies for the triads of interacting groups in the serine charge relay system of serine proteases and the proposed tyrosine charge relay system of angiotensin II, respectively, were computed according to the standard MNDOC procedure. The most stable configuration obtained for both systems was one in which the histidine residue was negatively charged. These findings indicate that the histidine ring and not the serine hydroxyl group at the active site of serine proteases would be the nucleophilic center which is acylated by substrate. Similarly, the extreme nucleophilicity of the imidazole anion produced by the proposed triad of interacting groups in angiotensin could provoke the formation of a transient covalent bond (acyl intermediate) between receptor and peptide in the receptor activation mechanism.