The contribution of phosphorylation and loss of COOH-terminal arginine to the microheterogeneity of myelin basic protein.

Two guinea pig myelin basic protein preparations which differed markedly in their contents of high pH electrophoretic or chromatographic forms were studied in an attempt to elucidate the causes of their microheterogeneity. Both total preparations and components isolated therefrom were examined for their amino acid compositions, NH2-terminal and COOH-terminal residues, total phosphorus contents, amd contents of phosphamino acids. The results showed that the five components differed sequentially by a single charge and that the microgeterogeneity arose as a result of secondary modifications of a single secies (Component 1) Of basic protein. Two modifications were demonstrated; viz. phosphorylation of serine and threonine and loss of COOH-terminal arginine. These two modifications were insufficient to account completely for the observed microheterogeneity; an additional cause, deamidation, was postulated. From the relationship between the number of components present in the total basic protein, the phosphorus and phosphoamino acid contents of the components, and the changes in relative electrophoretic mobility of the components which accompanied their phosphorylation and dephosphorylation we conclude that in the native basic protein no more than two sites in any polypeptide chain are phosphorylated.     

Growth phenology and water potential patterns of Periploca angustifolia in relation to water availability

Periploca angustifoliaLabill., is a multipurpose shrub also used to rehabilitate drylands. It is essential to understand its phenological patterns under arid conditions. In order to understand how plants manage extreme drought, this study investigates the relationship between phenological traits of P. angustifolia Labill., water potential and climatic conditions. During two successive growing seasons (Sep 2009–Augst 2011) phenological patterns, soil water content and water potentials were measured monthly for plants of Periploca angustifoliaLabill growing under rain-fed conditions (Annual rainfall = 168 mm) at the pastoretum of the Arid Regions Institute in southern Tunisia. The Ψmd decreased progressively and concomitantly with increasing seasonal drought, reaching the lowest values in late summer (down to –3 MPa). Water potentials of P. angustifoliaLabill were affected by spatial and temporal variations in soil water content. The increased diurnal amplitude values (∆ψ > −1.3 MPa) explained the especially high biological activity of this species during the dry season. Our results clearly demonstrate that P. angustifolia Labill is a drought-tolerant species reaching low water potentials during the driest months of summer. These characteristics make this shrub as promising for rehabilitating degraded arid ecosystems.     

Nutritional and metabolic studies in humans with 1,3-butanediol.

Three studies of the role of 1,3-butanediol (BD) in human nutrition are described. Isocaloric substitution of BD for starch in the diets of volunteers caused less negative nitrogen balance. Ingestion of urea also decreased negative nitrogen balance, and the effect of BD plus urea in the diets seemed to be additive. No effects were detected on many blood parameters measured during and after the study, except that BD feeding decreased blood glucose significantly. 1,3-Butanediol was shown to be a nontoxic metabolite providing a source of calories for human nutrition. In a second study, ingestion of BD was shown to cause slight increases in serum insulin and growth hormone concentrations in the fasting state. We next studied the effects of prior ingestion of BD on serum insulin, growth hormone, glucose, and lipids during glucose tolerance tests. No significant differences in these parameters were noted when prior ingestion of sucrose or an isocaloric quantity of BD were compared. Possible mechanisms whereby ingestion of BD spared nitrogen and caused decreased blood glucose are discussed.     

IMMUNOCHEMICAL AND BIOCHEMICAL STUDIES DEMONSTRATING THE IDENTITY OF A BOVINE SPINAL CORD PROTEIN (SCP) AND A BASIC PROTEIN OF BOVINE PERIPHERAL MYELIN (BF)

A protein extracted from bovine peripheral myelin (BF) and a protein extracted from bovine spinal cord (SCP) have been shown to be identical: the proteins cross-react immunochemicaliy with each other but not with highly purified CNS myelin basic protein. Neither BF nor SCP have anti-encephalitogenic activity. Their electrophoretic behavior is the same at three different pH values. Their apparent molecular weight by sodium dodecyl sulfate-gel electrophoresis is 13,800 ± 550. The amino acid compositions of the proteins are essentially identical. BF and SCP each contain 2 cysteine residues and have valine at the C terminus. The 23 major tryptic peptides are identical on peptide maps. Circular dichroic analyses yield essentially identical curves, which, when computed by best-fit curve analysis, indicate that each has 0%α helix and a large percentage of β structure.     

Attrition-free pyrolysis to produce bio-oil and char

Experiments are performed on a laboratory scale setup where beech wood chips are heated by gas convection and walls radiation. This study shows that it is possible to obtain high bio-oil and char yields with relatively low external heat transfer coefficients. The main advantage of this convection/radiation heat transfer mode compared to solid–solid collisions, applied in fluidized bed or twin screw reactors, is the reduction of solid attrition (char and sand). Thus tricky gas–solid separation through hot cyclones and/or hot filters could be avoided or reduced. It should be possible to recover directly bio-oil with less char particles and char free of sand dust. These qualities would allow easier use of these bio-products in different applications.