Adenovirus early gene products may control viral mRNA accumulation and translation in vivo

The mechanisms controlling early adenovirus gene expression in vivo have been studied using inhibitors of protein synthesis. When inhibitors were added shortly before or at the onset of infection, viral mRNA from all early regions was transcribed, spliced and accumulated over a 7 hr period. After longer pretreatment, accumulation of several early mRNAs were suppressed. Addition of inhibitors 1 hr after infection enhanced the accumulation of viral mRNA in the cytoplasm. Translation of early mRNA selected on adenovirus DNA in a cell-free system reflected the amount of viral mRNA present. A viral coded product may therefore control accumulation of viral mRNA.A different pattern emerged when inhibitors of protein synthesis were removed at 5 hr postinfection and cells were pulse-labeled in vivo. If inhibitors were introduced at or before infection, early viral proteins were synthesized only after a lag of 1–3 hr. However, if treatment was introduced 1 hr post-infection, reversion of the protein synthesis block was instantaneous. It appears that protein synthesis inhibitors reveal an in vivo translational block for viral mRNA. This block could be overcome by preinfection with a related virus. Furthermore, no block was observed in a virus-transformed human embryonic kidney cell line (293) which expresses early region 1 of the viral genome. Viral gene product(s) encoded in early region 1 may control translation of early adenovirus messenger RNA in vivo.     

Host gall size and oviposition success by the parasitoid Eurytoma gigantea

Abstract. 1. Eurytoma gigantea Walsh is a specialist parasitoid of the tephritid gallmaker Eurosta solidaginis (Fitch).
2. In the natural environment the incidence of parasitism by Eurytoma is greater in small galls than in large ones.
3. Laboratory experiments demonstrated that small galls are not more frequently discovered; however, oviposition attempts on small galls were more likely to be successful.
4. Eurytoma spends much time probing galls too big to penetrate; this leads to a decrease in foraging efficiency when many large galls are present.
5. The chance of successfully penetrating a gall depends on the thickness of the gall wall and the length of the parasitoid's ovipositor.
6. A simulation model was constructed which shows that a gallmak-er's chance of being parasitized depends on gall size, the number of parasitoids that discover the gall, and their ovipositor lengths.     

The role of histones H3 and H1 in the formation of thymine-lysine cross-links during UV-irradiation of deoxyribonucleoprotein

The effect of UV light (lambda = 254 nm) on calf thymus DNP at low ionic strengths was studied. It was found that at the irradiation doses used the protein in the DNA-protein complex increases as the irradiation dose rises. Thermal treatment and acid hydrolysis resulted in a predominant release of histones H3 and H1 from the complex. Data from liquid high performance chromatography, amino acid analysis, thin-layer chromatography point to the induction by UV-light of a thymine-lysine bond, whose formation involves DNA thymines and histone lysine residues, predominantly H3 and H1 fractions.     

Effect of serotonin on the yield of UV- and x ray-induced DNA damage

Using two-dimensional thin-layer chromatography, the effect of serotonin on the yield of thymine dimers and on cleavage of the N-glycosidic bond in the DNA irradiated with ultraviolet (UV) light and X-ray was studied. Bound serotonin was shown to reduce the synthesis of UV-induced thymine dimers but had no effect on the number of X-ray-induced breaks in the N-glycoside bonds in thymidine residues. The data obtained are discussed in terms of the mechanisms of serotonin involvement in the photoprotection of yeast cells from the lethal action of UV and X-ray irradiations.     

Chromosome studies in 952 infertile males with a sperm count below 10 million/ml

Summary A major chromosomal abnormality was observed in 10.3% of subfertile men in this study. This result is similar to a previous survey using the same criteria for selection of probands. The high frequency of chromosomal abnormalities emphasizes the importance of cytogenetic examination in subfertile men. The detection of such an abnormality should be followed by chromosome analysis in the patient's family. Prenatal diagnosis is indicated if a subfertile man with an abnormal karyotype fathers a child.     

Cimetidine-resistant Zollinger-Ellison syndrome: successful management with ranitidine.

In a patient with the Zollinger-Ellison syndrome who had undergone vagotomy, pyloroplasty and, later, gastrojejunostomy, epigastric pain and stomal ulceration recurred despite the use of high doses (2700 mg/d) of cimetidine. Ranitidine, a new histamine H2-receptor antagonist, reversed all symptoms and healed the stomal ulcer without side effects, thus obviating the need for further surgery. Ranitidine may prove to be the drug of choice in the medical management of patients with the Zollinger-Ellison syndrome.     

Hexapeptide analogue of somatostatin, Sandoz 201-456. Conformational study in dimethylsulfoxide by 1D and 2D n.m.r. methods

The conformational properties of the somatostatin analogue 201-456 (1) have been studied by high field n.m.r. in DMSO. This analogue is the base structure of nine derivates synthesized by Bauer et al. and shows a very low biological activity, although derived structures such as SMS 201-995 (2) are very potent. Our study has shown an important difference between the most stable conformation of the two compounds: although the beta turn type II' structure at the Phe3-Trp4-Lys5 level is present in both analogues, an important conformational change appears at the cystine bridge. In SMS 201-995 the beta turn/beta sheet conformation is stabilized by the additional amino-acids D-Phe1 and Thr8 (ol) through intramolecular H-bonds.