Chemical biology: Paper alert

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in chemical biology.     

Effect of protein S-100 on phosphorylation of nuclear proteins of cells of rat brain and liver

The effect of acidic neurospecific protein S-100 on the phosphorylation of brain and liver nuclear proteins with 1 and 10 microM ATP was investigated. It was shown that protein S-100 increases the phosphorylation of brain nuclear proteins, while antigen D, another acidic neurospecific protein half-identical to 14-3-2 protein, inhibits this process. Ca2+ and cAMP at concentration of 10(-6) M do not affect the phosphorylation of brain nuclear proteins. In control assays the tracer 32P is presumably incorporated into high molecular weight nuclear protein fractions (Mr greater than 40000). After addition of protein S-100 the tracer is mainly incorporated into these proteins as well independently of ATP concentration (1 or 10 microM). The phosphorylation of nuclear proteins with molecular weights above 100000 is mostly increased in this case. At ATP concentration of 1 microM protein S-100 decreases histone phosphorylation 2.3 times but does not affect that of non-histone proteins. However, at 10 microM ATP the inhibitory action of this protein on histone phosphorylation is absent. The possible mechanisms of protein S-100 action on nuclear proteins phosphorylation are discussed.     

The effect of repeated intermittent hypoxia on pulmonary vasoconstriction in the newborn

The effect of repeated intermittent hypoxia upon the basal pulmonary vascular tone in the newborn period is unknown. We therefore studied the central hemodynamic response to seven repeated intermittent hypoxic challenges in acutely prepared piglets under 2 weeks of age. Catheters were placed in the aorta, pulmonary artery, and atria, and an electromagnetic flow probe was positioned around the main pulmonary artery. Each hypoxic challenge (Fio2 = 0.14) lasted 5 min, and was separated by an equal duration of ventilation with air. Nine control animals were ventilated with air for 90 min, a period of time equivalent to the seven challenges in the experimental group, and subjected to one hypoxic challenge at the end. Hypoxia uniformly induced pulmonary vasoconstriction. Repeated intermittent hypoxic challenges produced a progressive increase in pulmonary artery pressure and vascular resistance, both during air ventilation and hypoxia. For each challenge, the vascular resistance value achieved during hypoxia was directly related to the immediately preceding air ventilation one, and the magnitude of hypoxic pulmonary vasoconstriction, defined as the incremental change in resistance from air to hypoxia, was not different from the first to the last challenge in the experimental group. In the control group the pulmonary vascular tone did not change during the 90 min of air ventilation, and the single hypoxic challenge induced an increase in pulmonary vascular pressure and resistance similar in magnitude to the first challenge in the experimental group. Indomethacin administration to five experimental animals, after the last challenge, reversed the increase in air ventilation pulmonary artery pressure and vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)     

High performance liquid chromatography of leukotriene C4 on the aminopropyl sorbent

Chromatographic behaviour of leukotriene C4, its methyl ester and hydrophobic side products of their synthesis on an aminopropyl sorbent has been investigated, the retention time values being determined by both hydrophobic and ionic interaction of the substances with the sorbent. Optimal conditions of the separation are determined.     

Acclimation or stress symptom? An integrated study of intraspecific variation in the clonal plant Aechmea bromeliifolia,a widespread CAM tank‐bromeliad

The clonal tank-bromeliad Aechmea bromeliifolia (Rudge) Baker was found in four different habitats in a restinga (vegetation mosaic on sandy coastal plains), of south-eastern Brazil. These habitats (swamp forest, dry forest, dry shrubland and herbaceous marsh) lie within a few hundred metres of each other along a gradient extending inland from the coast, and differ markedly in terms of light and flood regime. We compared ramet morphology, leaf anatomy and physiology, and population parameters to examine the amplitude of trait variation of this widespread species in the studied restinga. This integrated approach allowed us to examine which variation conferred acclimation and which was merely a stress symptom. A . bromeliifolia showed site-specific differences in abundance, distribution, rosette size and shape, leaf anatomical arrangement and photochemical efficiency (potential quantum yield; F _v/ F _m) during the day. Most of the variation found seemed to be related to the interaction of light and flooding. The lowest number and size of ramets at the exposed, dry shrubland was matched by a marked leaf photoinhibition, which suggested poor acclimation to local levels of light intensity and limited water supply. In the other habitats, the morpho-physiological parameters measured suggested adequate foraging behaviour and site acclimation.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 2002, 140 , 391-401.