Stimulation par la lumière rouge lointain de la synthèse de la δ-aminolévulinate déshydratase des cotylédons de radis

Stimulation of de novo synthesis of δ-aminolevulinate dehydralasc of radishes grown under far-red light .
Density labelling studies of δ-aminolevulinate dehydratase (ALAD) in cotyledons of radish ( Raphanus sativus L. cv. Longue Rave Saumonée) seedlings demonstrate that far-red light stimulates de novo synthesis of ALAD and that the turn-over of this enzyme is very poor. Cycloheximide reduces considerably both the increase of ALAD activity and the incorporation of deuterium in ALAD, which indicates that ALAD synthesis depends upon cytoplasmic ribosomes.     

Ovarian and haemolymph titres of ecdysteroid during the gonadotrophic cycle in Diploptera punctata

The free (non-conjugated) ecdysteroid in the ovaries during the first gonadotrophic cycle of Diploptera punctata was identified as 20-hydroxyecdysone. The hormone, quantified by radioimmunoassay and by ultraviolet absorbance, was detectable in the ovary toward the end of vitellogenesis; the quantity increased rapidly during chorion formation. Ovaries with chorionated eggs contained 67 μg of 20-hydroxyecdysone per g fresh weight. The haemolymph free-ecdysteroid, not identified physicochemically, was quantified by radioimmunoassays. The highest concentration was observed at adult emergence; the titre declined between days 1–3 and then remained at a relatively constant level through oviposition (which occurs between day 7 and 8); titres in pregnant females were higher. Ovariectomized females exhibited the same pattern of ecdysteroid titres in the haemolymph as the sham operated controls throughout the period corresponding to the first gonadotrophic cycle. Thus the ovary may not be the only source of haemolymph ecdysteroid related to reproduction in adult females.     

A tandemly reiterated DNA sequence in the long repeat region of herpes simplex virus type 1 found in close proximity to immediate-early mRNA 1.

The 3' end of immediate-early mRNA 1 was mapped precisely within the IRL/TRL genome regions, and the DNA sequences around the 3' end were determined. An AATAAA polyadenylation signal was present 17 base pairs upstream of the 3' end, and eight tandemly repeated copies of a 16-base-pair sequence (GGGGGTGCGTGGGAGT) plus one further closely related copy were located 20 base pairs downstream. Other tandem reiterations present in the herpes simplex virus genome are described and their properties are considered.     

Intracellular Ca and cell injury: A paradoxical role of Ca in complement membrane attack

Disturbances in intracellular Ca2+ are known to be important in cell injury caused by a wide range of toxic factors. The complement system is a major effector of immune damage in vivo, and is known to be involved in the pathogenesis of many immune diseases. We present here evidence that the potentially lethal membrane attack complex of complement causes a rapid increase in intracellular free Ca2+ concentration before any other detectable biochemical changes in the cell. In nucleated cells the increased intracellular free Ca2+ concentration initially stimulates recovery processes, allowing the cell to escape mild complement attack and also activates the production of inflammatory mediators, which may amplify an ongoing inflammatory response. More severe complement membrane attack causes a more rapid rise in intracellular free Ca2+ concentration allowing a threshold to be breached above which recovery processes are overwhelmed, and cell death occurs. The importance of non-lytic effects and recovery processes mediated by Ca2+, and the molecular basis of these effects are discussed, and the hypothesis proposed that the cell-injuring effects of other "pore-forming" toxins are also caused by increases in intracellular free Ca2+.     

Production of indole alkaloids by gel-entrapped cells of Catharanthus roseus in a continuous flow reactor

Summary Calcium alginate gel-entrapped cells ofCatharanthus roseus were used to study the production of indole alkaloids in a flow through process. The bioreactor was functional for more than two months and product recovery was analyzed under various operating conditions.     

Laryngeal papillomas: local cellular immune response,keratinization and viral antigen

Virchows Archiv B Cell Pathology - Various parameters of the local cellular response have been studied in 16 laryngeal papillomas from ten patients with recurrent papillomas as well as normal...     

Long-chain fatty acid assimilation By rhodopseudomonas sphaeroides

Exogenously supplied long-chain fatty acids have been shown to markedly alleviate the inhibition of phototrophic growth of cultures of Rhodopseudomonas sphaeroides caused by the antibiotic cerulenin. Monounsaturated and polyunsaturated C18 fatty acids were most effective in relieving growth inhibition mediated by cerulenin. Medium supplementation with saturated fatty acids (C14 to C18) failed to influence the inhibitory effect of cerulenin. The addition of mixtures of unsaturated and saturated fatty acids to the growth medium did not enhance the growth of cerulenin-inhibited cultures above that obtained with individual unsaturated fatty acids as supplements. Resolution and fatty acid analysis of the extractable lipids of R. sphaeroides revealed that exogenously supplied fatty acids were directly incorporated into cellular phospholipids. Cells treated with cerulenin displayed an enrichment in their percentage of total saturated fatty acids irrespective of the presence of exogenous fatty acids. Cerulenin produced comparable inhibitions of the rates of both fatty acid and phospholipid synthesis and was further found to preferentially inhibit unsaturated fatty acid synthesis.