Organ culture of the terminal abdominal segment of an adult female lepidopteron

Summary Organ cultures containing the sex pheromone gland ofDiatraea saccharalis (F.) (sugarcane borer) were maintained for over 2 months. Juvenile hormone but not ecdysterone appeared to be essential for the maintenance of integrity of the sex pheromone gland in the organ culture system. Muscles associated with these cultures pulsated during hte entire culture period with or without juvenile hormone, suggesting that the hormone requirement was specific for the sex pheromone gland and not a general requirement of the cells of the organ-cultured segment.     

Human T-helper clones induce IgG production in a subclass-specific fashion.

The mechanisms governing the induction of IgG subclasses by T-helper cells in humans were investigated. As preliminary bulk-culture experiments had indicated that a direct B cell contact with viable T cells was an essential requirement for optimal IgG subclass production, 256 CD4+ human T cell clones were preactivated with PHA and cultured in direct contact with autologous B cells. These clones induced IgG production in a strikingly subclass-specific fashion. Moreover, the distribution of subclass-specific helper clones was very similar to the IgG subclass profile observed in serum and peripheral lymphoid tissue plasma cells (IgG1 approximately 60%, IgG2 approximately 30%, IgG3 approximately 5-10%, IgG4 less than or equal to 5%) and unlike that observed in resting B cells (which is IgG1 approximately 40% and IgG2 approximately 50%). It would, therefore, seem that a predominance of T cells capable of delivering IgG1-specific, as opposed to IgG2-specific, help is an essential factor for the preferential induction of IgG1 antibodies during B cell proliferation and differentiation. There was no relationship between IL2, IL4, IL6, and IFN-gamma secreted by the T-helper clones and their IgG subclass induction patterns. In addition, only a few supernatants were able to reproduce the helper effects of the clones themselves. Therefore, direct contact of B cells with helper clones is crucial for IgG-subclass production in humans.     

Effects of arachidonic acid and indomethacin on the in vitro release of prostaglandins by aortic strips of spontaneously hypertensive rats

Aortic strips removed from spontaneously hypertensive (SH) rats and preincubated with arachidonic acid (1.0 X 10(-5) g/ml) for 15 min produced two times more prostaglandin (PG) like material than aortae unexposed to the precursor of PG biosynthesis. The stimulating effect of arachidonic acid was largely inhibited by indomethacin (1.0 X 10(-5) g/ml). Also, the release of PG-like material by aortic strips derived from SH rats treated with an intravenous injection of indomethacin (10 mg/kg) was inhibited by 74% compared with the control tissues. These results raised the possibility that the in vivo conversion of arachidonic acid by large arteries of SH rats may contribute to the hypotensive effect of this PG precursor in SH rats.     

Mouth morphology, testes size and body size in male Tilapia zillii: implications for fighting and assessment

In Tilapia zillii , the outcome of fights is closely related to difference in testis weight between opponents rather than differences in body weight. Testes size was predictable statistically on the basis of the size of the mouth in relation to body size, suggesting that among other functions mouth morphology may have evolved to facilitate assessment during fighting.     

A recA-ada hybrid gene inducible by DNA damage.

A damage-inducible expression vector was constructed in which the original recA structural gene was replaced by the protein-coding region of the ada gene. The O6-alkylguanine-DNA alkyltransferase encoded by the ada gene can be measured by a rapid and highly sensitive assay. The introduction of this construct into an appropriate host cell provides an effective bacterial assay for genotoxins.     

Effect of neonatal administration of norethynodrel-mestranol on the reproductive system of female mice

39 female mice were injected with 98.5 mg norethynodreland 1.5 mcg mestrand (ENOVID) at 5 days of age. Eyelid opening, an indication of general maturation was significantly advanced from 15 to 12 days. (p less than .001). Vaginal opening advanced from 38 days to 37 days (p less than .001). After puberal age, all treated animals had persistant vaginal cornification showing the classical syndrome of steroid induced sterility. At autopsy, mammary pads of all the treated animals showed a branched duct system with slender ends and almost no alveoli. Most of the control animals had frequent alveoli. Ovarian weight was reduced by 50 percent in treated animals (p less than .001). .001). No corpora lutea were found in treated animals.