Contest and scramble competitions in two bruchid species,Callosobruchus analis andC. phaseoli (Coleoptera: Bruchidae)

Larval competition between contest and scramble strategists was investigated using the two bruchid species, C. analis (contest species) and C. phaseoli (scramble species) with two different sized mung beans (large and small beans). In both sized beans, the adult emergences of each species dependen on total density of the initial larval densities of the two species and the ratio of the two densities. The emergence of one species was suppressed by the existence of the other species when the initial larval density per bean of the former species was less than that of the latter one. There were many cases in which both C. analis and C. phaseoli emerged from one bean in large beans, but such cases were quite rare in small beans. C. analis performed interference behavior only at late larval stages, whereas C. phaseoli was superior in exploitative competition all through their larval stages. These, combined with the niche segregation inside a bean, are throught to be the major factors of observed density- and frequency-dependent competition results. Based on the above experimental results, long-term competition results between the contest and scramble species were predicted.     

A new type of mitogenic factor produced by Streptococcus pyogenes.

A new type of mitogenic factor (protein) was purified from the culture supernatant of a strain of Streptococcus pyogenes by SP-Sephadex C-25 column chromatography, preparative isoelectric focusing and reversed-phase high-performance liquid chromatography. The purified factor, showing marked mitogenic activity in rabbit peripheral blood lymphocytes, gave a single-band staining for protein on SDS-PAGE. The molecular weight of the purified mitogenic factor was determined to be 25,370, which was different from those calculated from reported amino acid sequences deduced from 4 different nucleotide sequences of 3 kinds of streptococcal pyrogenic exotoxins (two SPEAs, SPEB and SPEC). The amino acid sequence of the N-terminal region of the purified mitogenic factor was determined to be Gln-Thr-Gln-Val-Ser-Asn-Asp-Val-Val-Leu-Asn-Asp-Gly-Ala-Ser-Lys-Tyr-Leu- Asn-Glu - Ala-, which was also different from the reported N-terminal sequences deduced from the 4 different nucleotide sequences. These data indicate that this mitogenic factor is distinct from the already described streptococcal pyrogenic exotoxins.     

Recognition of a 56 kDa protein in partially purified rat hepatic nuclear thyroid hormone receptor by anti-human c-erb A beta antibody.

Human beta thyroid hormone receptor (c-erb A beta protein) produced by an Escherichia coli expression system was purified by sequential column chromatography followed by electroelution from an electrophoresis gel and an antibody was prepared. The antibody recognized a 56 kDa protein band in a partially purified rat hepatic nuclear thyroid hormone receptor fraction on Western blotting. Although multiple bands appeared on Western blotting of crude rat hepatic receptor preparations, a 56 kDa band was the most prominent and preadsorption of the antibody by purified c-erb A protein resulted in almost complete disappearance of the 56 kDa band, indicating that the 56 kDa band was formed by a specific antigen-antibody interaction. Furthermore, the 56 kDa protein appeared to co-elute with 3, 5, 3'-triiodo-L-thyronine binding activity in hydroxylapatite, Sephacryl S-200, and DNA-cellulose column chromatography of rat hepatic nuclear receptor, and sequential column purification resulted in selective enrichment of the 56 kDa band. These results suggest that the 56 kDa protein may be the major component of the rat hepatic thyroid hormone receptor.     

Autoregulation of androgen receptor expression in rodent prostate: immunohistochemical and in situ hybridization analysis

Autoregulation of androgen receptor mRNA and protein was investigated by immunohistochemical and in situ hybridization techniques. In both mouse and rat prostate, the epithelial cell nuclei were stained with the monoclonal or polyclonal antibodies raised against human androgen receptor. It was observed that 3 days after castration, nuclear staining of the epithelium was greatly reduced, while androgen treatment restored the staining intensity to a normal level. In situ hybridization using an androgen receptor cDNA fragment as probe demonstrated that the change in androgen receptor mRNA level correlated with the change in antibody staining intensity. These data suggested an up-regulation of androgen receptor expression by androgen.     

Presence of 2-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and 1,2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, novel endogenous amines, in parkinsonian and normal human brains

2-Methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and 1,2-dimethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline were identified for the first time as novel endogenous amines in parkinsonian and normal human brains by gas chromatography-mass spectrometry. It is of interest that these tetrahydroisoquinolines are analogues of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) which produces Parkinson's disease.     

Monoclonal antibody against platelet thrombospondin decreases erythrocyte aggregation rate.

The effect of thrombospondin, a major glycoprotein in the platelet alpha-granule, on the erythrocyte aggregation rate was investigated. Venous blood was sampled from 8 healthy male volunteers and anticogulated with 1.1 mg/ml EDTA(K2). The erythrocyte aggregation rate of each blood sample was measured with a whole-blood erythrocyte aggregometer before and after incubation with murine monoclonal antibody against human platelet thrombospondin. After 15 min incubation, the erythrocyte aggregation rate exhibited a significant decrease to 0.055 +/- 0.022/s, representing 71.9 +/- 8.7% of the control value (0.075 +/- 0.028/s) (p less than 0.0005). The results obtained suggest that thrombospondin may participate in the control of erythrocyte aggregability in the circulating blood.     

Evidence that glycine and GABA mediate postsynaptic inhibition of bulbar respiratory neurons in the cat.

Experiments were carried out on decerebrate cats to identify transsynaptic mediators of spontaneous postsynaptic inhibition of bulbar inspiratory and postinspiratory neurons. Somatic membrane potentials were recorded through the central micropipette of a coaxial multibarreled electrode. Blockers of type A gamma-aminobutyric acid (GABA-A) and glycine receptors were iontophoresed extracellularly from peripheral micropipettes surrounding the central pipette. Effective antagonism was demonstrated by iontophoresis of agonists with antagonists; application of strychnine antagonized the action of glycine but not GABA, and application of bicuculline antagonized the action of GABA but not glycine. In both types of neurons, iontophoresis of either antagonist depolarized the somatic membrane and increased input resistance throughout the respiratory cycle. Bicuculline preferentially depolarized the somatic membrane in both types of neurons during inactive phases. Strychnine increased the firing rate of inspiratory neurons during inspiration despite maintenance of somatic membrane potential at preiontophoresis levels. Tetrodotoxin reduced the effects of iontophoresed bicuculline and strychnine, suggesting that the action of the antagonists required presynaptic axonal conduction. The present results suggest that presynaptic release of both GABA and glycine contributes to tonic postsynaptic inhibition of bulbar respiratory neurons. GABA-A receptors appear to contribute to inhibition during inactive phases in inspiratory and postinspiratory neurons, whereas glycinergic mechanisms appear to contribute to inspiratory inhibition in inspiratory neurons.     

Primary structure of a precursor for the delta-subunit of sweet potato mitochondrial F1-ATPase deduced from full length cDNA.

A cDNA library constructed from poly(A)-rich RNA of the sweet potato tuberous root using a newly developed plasmid vector carrying tac-SP6 promoters was used to identify full length cDNAs for the nuclear-encoded delta-subunit of mitochondrial F1-ATPase by oligonucleotide-hybridization selection. Selected clones contained cDNA insert which carry the entire coding capacity for the pre-delta-subunit, since the RNA transcribed in vitro from SP6 promoter on the vector directed the synthesis of pre-delta-subunit polypeptide in a wheat germ in vitro translation assay. The nucleotide sequence of one of these cDNAs indicates that it can code for the pre-delta-subunit of 244 amino acids of which 199 amino acids encode the mature subunit. The amino acid sequence of the mature delta-subunit shows similarities of about 18-25% amino acid positional identity with the delta-subunits of bacterial F1-ATPases, about 26% with the delta-subunit of chloroplast CF1-ATPase, and about 32-37% with oligomycin sensitivity conferring proteins of animal and fungal mitochondria. The N-terminal presequence of the precursor composed of maximum of 45 amino acids does not show any obvious sequence homology with either the transit peptide of the nuclear-encoded pre-delta-subunit of chloroplast CF1 or the presequence of the nuclear-encoded pre-oligomycin sensitivity conferring proteins. At least two types of the delta-subunit cDNAs with very similar structures were identified from the library, and the presence of multiple copies of the delta-subunit gene in the hexaploid genome of the sweet potato is also suggested by genomic Southern blot hybridization.     

Angiotensin II generation in mesenteric arteries in rats: effects of nephrectomy, deoxycorticosterone and dexamethasone

Angiotensin II (ANG II) generation in the mesenteric arteries was studied in four groups of rats: deoxycorticosterone (DOCA)/salt treated, glucocorticoid treated, nephrectomized and control rats. Basal plasma renin activity (PRA) was undetectable in the nephrectomized group and suppressed in the DOCA/salt treated rats, but was increased in the rats treated with glucocorticoid. The Basal plasma ANG II concentration changed comparably with PRA in all four groups of rats. In the control rats, ANG II was released from the mesenteric arteries at a rate of 43.0 +/- 12.0 pg/h, and it was not decreased by nephrectomy. In DOCA/salt rats and glucocorticoid rats, ANG II release significantly decreased to 12.8 +/- 7.1 and 6.9 +/- 1.5 pg/h, respectively. Captopril treatment significantly reduced ANG II release from the mesenteric arteries in both controls and nephrectomized rats, but did not influence ANG II output in DOCA/salt rats or in glucocorticoid treated rats. In nephrectomized rats, captopril lowered blood pressure in association with a significant reduction in the mesenteric ANG II formation. These results indicate that the renal and vascular renin-angiotensin system (RAS) may be independently regulated, and in nephrectomized animals the vascular RAS contributes in part to the maintenance of blood pressure. The present results also suggest that volume expansion per se and/or pharmacological intervention by DOCA and glucocorticoid could modulate vascular ANG II generation.     

Duct,exocrine, and endocrine components of cultured fetal mouse pancreas

Summary Twenty to twenty-two days postcoitum mouse fetal pancreas organ bits were cultured on the dermal surface of irradiated pigskin as a substrate. The medium used for long term culture consisted of Eagle’s Minimum Essential Medium with the addition of 10% bovine serum, 0.02 U/ml insulin, 0.025 μg/ml glucagon, 3.63 μg/ml hydrocortisone, 100 μg/ml soybean trypsin inhibitor or 10⁻⁸ M atropine. When the medium lacked trypsin inhibitor or atropine but contained the three hormones, the pigskin support began to be destroyed after 2 to 4 wk in culture. Thereafter, the cultured cells could not grow and survive on the digested pigskin. When 10⁻⁶ M atropine was added to the medium, amylase secretion from cultured cells and destruction of pigskin were inhibited completely but pancreas cells could not grow or survive. In contrast, 100 μg/ml soybean trypsin inhibitor or 10⁻⁸ M atropine permitted cell growth, permitted amylase secretion from the cultured acinar cells, and prevented the destruction of pigskin. Under these conditions pancreas cells migrated or grew or both from the organ bits onto the surface of the pigskin dermis and organoid aggregations formed. Hydrocortisone was needed to permit growth for more than 2 wk. Glucagon and insulin had additive effects. Light and electron microscopic observations indicated the culture of at least five kinds of cells, i.e., duct, acinar, centroacinar, endocrine, and mesenchymal. The majority of cultured cells were duct cells and acinar cells. There were few mesenchymal cells. Mouse pancreas cells were cultured for at least 12 wk by this method. This investigation was supported by PHS Grant CA 30220 awarded by the National Cancer Institute, DHHS, Grant 1203M awarded by the Council for Tobacco Research, Inc., and Grant RD-65 (for equipment) awarded by the American Cancer Society. Nude mice were provided by Dr. Wendall M. Farrow of Life Sciences, Inc., Resource Laboratory N01, CP6-1005 of the National Cancer Institute.