Auxin binding site in tobacco cells

A specific, high affinity, IAA binding site was demonstrated in both a cytosolic fraction, and in isolated nuclei, fromNicotiana tabacum cv. Wisconsin No. 38 cells grown in suspension culture. The amount of the binding site detected in both these fractions changed during the culture cycle according to a strict pattern. The molecular mass of the binding site was estimated by gel filtration to be approximately 175 000 and it appears to be a protein. When partially purified by affinity chromatography and allowed to pre-incubate with IAA, the site had a significant stimulatory effect on total RNA synthesis, as measured by a cell-free assay system. Unpurified extracts had no such effects. The system behaves rather like the steroid hormone-receptor system in animals.     

Effects of sedation on the controlled pulmonary circulation

The pulmonary circulatory effects of sedatives and groups of sedatives in dosages commonly employed as pre cardiac catheterization sedatives were evaluated. The sedatives included: meperidine, thiamylal, hydroxyzine, promethazine, meperidine + chlorpromazine + promethazine and meperidine + hydroxyzine. An animal preparation with constant pulmonary blood flow and left atrial pressure was employed. This preparation has the unique advantage of permitting measurement of the active pulmonary vascular resistance change since passive effects are controlled. In order to establish the significance of a given change in active PVR, a dose response relationship for serotonin was established and the effect of the sedatives was calibrated against it. PVR increased following infusion of all sedatives tested except hydroxyzine and chlorpromazine.A technique was detailed to permit subtraction of passive PVR change from total PVR change in intact, unsedated animals. Results of active change in PVR of previous investigations in intact, unsedated animals were compared to the active change observed in this experiment and were found to be similar in direction and magnitude. This investigation stresses the need to consider possible effects of sedatives on the pulmonary circulation.     

New method for determination of fecal sterols in urine using non-chlorinated solvents

A new method has been developed to determine a number of sterols in urine using non-chlorinated solvents, namely methyl tert.-butyl ether and methanol (the MTB method). The method involves liquid–liquid extraction, saponification, reextraction, silylation and final identification and quantification by GC–FID. The sterols determined were coprostanol, epicoprostanol, cholesterol and dihydrocholesterol. 5α-Cholestane was used as internal standard. The limit of detection for the sterols in this experiment was 2 μg l⁻¹ urine. Recovery of coprostanol over the range 5–100 μg l⁻¹ urine by this method was between 80 and 92%.     

Mutant alpha-synuclein-induced degeneration is reduced by parkin in a fly model of Parkinson's disease.

Parkinson's disease (PD) patients show a characteristic loss of motor control caused by the degeneration of dopaminergic neurons. Mutations in the genes that encode alpha-synuclein and parkin have been linked to inherited forms of this disease. The parkin protein functions as a ubiquitin ligase that targets proteins for degradation. Expression of isoforms of human alpha-synuclein in the Drosophila melanogaster nervous system forms the basis of an excellent genetic model that recapitulates phenotypic and behavioural features of PD. Using this model, we analysed the effect of parkin co-expression on the climbing ability of aging flies, their life span, and their retinal degeneration. We have determined that co-expression of parkin can suppress phenotypes caused by expression of mutant alpha-synuclein. In the developing eye, parkin reduces retinal degeneration. When co-expressed in the dopaminergic neurons, the ability to climb is extended over time. If conserved in humans, we suggest that upregulation of parkin may prove a method of suppression for PD induced by mutant forms of alpha-synuclein.     

Nearest Neighbours: Estimators for Heterogeneity

Papadakis' method is shown to be an example of an estimation procedure for a heterogeneity function localized in a reproducing kernel Hilbert space. Within this framework some current models for the evaluation of field trials are discussed.     

NADPH-dependent reductase solubilized from microsomes by peroxidation and its activity

Isolated rat liver microsomes were subjected to enzymatic or non-enzymatic lipid peroxidation $\text{in vitro}$. NADPH-dependent cytochrome $\text{c}$ reductase activity was released from the microsomes into the media during peroxidation. This activity could be recovered from the media by DEAE-cellulose chromatography. The recovered enzyme retained high activity for the reduction of cytochrome $\text{c}$ and a lower level of activity for the reduction of cytochrome P-450. The active fractions were capable of enzymatically supporting the peroxidation of isolated mitochondria in the presence of organically complexed Fe⁺³ and NADPH, and in this respect the specific activity was found to be about ten times higher than in microsomes.