The arterial supply of the muscle biceps brachii

The bicipital arteries (Rami bicipitales) were classified according to the part of the muscle they supply, to the artery from which they originate and to their relative position to the median, musculocutaneous and ulnar nerves. The maximal density of bicipital arteries can be found in the middle of the upper arm and slightly distal to the greater tubercle.     

Glutathione peroxidase activities in sheep and rat muscle and some effects of selenium deficiency.

The activity and distribution of the selenium-containing enzyme, glutathione peroxidase, has been determined in muscle fractions in normal adult rats and sheep. Skeletal and cardiac muscle have been examined, and in both types of muscle the major proportion of the enzyme appeared in the cytosol fraction. Enzyme activity was higher in cardiac muscle than in skeletal muscle in both species, and based on total protein present in fractions, it appears that rat muscle contains more enzyme activity than sheep muscle. In tissues from lambs born to selenium-deprived ewes the levels of enzyme were significantly depressed. Two sampling periods were selected, the first when the lambs were 2-3 weeks of age and the second at slaughter when they were 10 weeks old. Muscle, plasma and erythrocyte levels of the enzyme indicated that the most sensitive measure of selenium deficiency is likely to be that of the erythrocyte enzyme level.     

Cruciate ligaments of the avian knee: Insight into a complex system

The avian cruciate ligaments were examined in Gallus domesticus, Anas platyrhynchos, Meleagris gallopavo, and Struthio camelus australis. The ligaments proved to be deviated around the intercondylar groove (cranial cruciate) and around the medial femoral condyle (caudal cruciate). Four functionally different fiber groups could be differentiated: fibers taut only in maximal extension, fibers taut only in maximal flexion, fibers taut in ranges from an intermediate position to an extreme position, and fibers taut throughout the entire range of motion (guiding bundles). Hence the cruciates serve the guiding of the joint and the restriction of motion, whereby the majority of the cranial cruciate fibers are taut in extension while those of the caudal cruciate are in flexion. No differences were found between the species examined with respect to fiber arrangement and function. The avian mechanical model proved to be more complex than the relatively simple mammalian four-bar link model as the avian guiding bundles change their shape due to deflection during motion. © 1992 Wiley-Liss, Inc.     

不同胁迫预处理提高水稻幼苗抗寒性期间蛋白质的变化

水稻(Oryza sativa L.)幼苗经盐、热激和冷三种不同胁迫预处理均提高了幼苗的抗寒性。与未预处理苗相比,在处理后、低温伤害后和常温下恢复2d的三个时期,不同胁迫预处理苗的可溶性和热不稳定蛋白含量变化趋势甚为相似,但热稳定蛋白含量变化则各有异同。SDS-PAGE图谱分析显示,不同胁迫预处理提高水稻幼苗抗寒性时,其可溶性蛋白、热稳定和热不稳定蛋白组成变化亦各有异同。除诱导出共有的新多肽外,还各自诱导出特有的新多肽。结果表明,植物对不同胁迫的交叉适应存在一定的共同机理,但亦可看出植物对同一种环境胁迫似乎不是以同一的机理去适应。     

Purification and characterization of Dolichos lablab lectin

The mannose/glucose-binding Dolichos lablab lectin (designated DLL) has been purified from seeds of Dolichos lablab (hyacinth bean) to electrophoretic homogeneity by affinity chromatography on an ovalbumin- Sepharose 4B column. The purified lectin gave a single symmetric protein peak with an apparent molecular mass of 67 kDa on gel filtration chromatography, and five bands ranging from 10 kDa to 22 kDa upon SDS-PAGE. N-Terminal sequence analysis of these bands revealed subunit heterogeneity due to posttranslational proteolytic truncation at different sites mostly at the carboxyl terminus. The carbohydrate binding properties of the purified lectin were investigated by three different approaches: hemagglutination inhibition assay, quantitative precipitation inhibition assay, and ELISA. On the basis of these studies, it is concluded that the Dolichos lablab lectin has neither an extended carbohydrate combining site, nor a hydrophobic binding site adjacent to it. The carbohydrate combining site of DLL appears to most effectively accommodate a nonreducing terminal alpha-d-mannosyl unit, and to be complementary to the C-3, C-4, and C-6 equatorial hydroxyl groups of alpha-d-mannopyranosyl and alpha-d-glucopyranosyl residues. DLL strongly precipitates murine IgM but not IgG, and the recent finding that this lectin interacts specifically with NIH 3T3 fibroblasts transfected with the Flt3 tyrosine kinase receptor and preserves human cord blood stem cells and progenitors in a quiescent state for prolonged periods in culture, make this lectin a valuable tool in biomedical research.      

Lysophosphatidic Acid can Support the Formation of Membranous Structures and an Increase in MBP mRNA Levels in Differentiating Oligodendrocytes

During development, differentiating oligodendrocytes progress in distinct maturation steps from premyelinating to myelinating cells. Such maturing oligodendrocytes express both the receptors mediating signaling via extracellular lysophosphatidic acid (LPA) and the major enzyme generating extracellular LPA, namely phosphodiesterase-Iα/autotaxin (PD-Iα/ATX). However, the biological role of extracellular LPA during the maturation of differentiating oligodendrocytes is currently unclear. Here, we demonstrate that application of exogenous LPA induced an increase in the area occupied by the oligodendrocytes’ process network, but only when PD-Iα/ATX expression was down-regulated. This increase in network area was caused primarily by the formation of membranous structures. In addition, LPA increased the number of cells positive for myelin basic protein (MBP). This effect was associated by an increase in the mRNA levels coding for MBP but not myelin oligodendrocyte glycoprotein (MOG). Taken together, these data suggest that LPA may play a crucial role in regulating the later stages of oligodendrocyte maturation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Special issue article in honor of Dr. George DeVries. Luciana Nogaroli and Larra M. Yuelling contributed equally to this work.     

Does life originate from a single molecule?

Life did not emerge in a single step. In chemical evolution, the first formation of a self-replicating molecule was probably one of the most critical bottlenecks, which was overcome only with a very low probability. If only one such event was successful, present-day life originates from a single molecule. In this case, homochirality in DNA and RNA is explained almost without further assumptions. By contrast, the enantiomer excess, produced by the deterministic mechanisms suggested so far, is smaller than the statistical standard deviation, unless the postulated initial number of molecules is very--in some mechanisms unreasonably--large. A certain chiral nonuniformity of natural monosaccharides other than (deoxy)ribose supports the idea that homochirality originates not from such small molecules but from an early RNA-like oligomer. This nonuniformity seems also hard to explain by any deterministic mechanism.