Distinct secondary structures of the leucine-rich repeat proteoglycans decorin and biglycan. Glycosylation-dependent conformational stability

Biglycan and decorin have been overexpressed in eukaryotic cells and two major glycoforms isolated under native conditions: a proteoglycan substituted with glycosaminoglycan chains; and a core protein form secreted devoid of glycosaminoglycans (Hocking, A. M., Strugnell, R. A., Ramamurthy, P., and McQuillan, D. J. (1996) J. Biol. Chem. 271, 19571-19577; Ramamurthy, P., Hocking, A. M., and McQuillan, D. J. (1996) J. Biol. Chem. 271, 19578-19584). Far-UV CD spectroscopy of decorin and biglycan proteoglycans indicates that, although they are predominantly beta-sheet, biglycan has a significantly higher content of alpha-helical structure. Decorin proteoglycan and core protein are very similar, whereas the biglycan core protein exhibits closer similarity to the decorin glycoforms than to the biglycan proteoglycan form. However, enzymatic removal of the chondroitin sulfate chains from biglycan proteoglycan does not induce a shift to the core protein structure, suggesting that the final form is influenced by polysaccharide addition only during biosynthesis. Fluorescence emission spectroscopy demonstrated that the single tryptophan residue, which is at a conserved position at the C-terminal domain of both biglycan and decorin, is found in similar microenvironments. This indicates that in this specific domain the different glycoforms do exhibit apparent conservation of structure. Exposure of decorin and biglycan to 10 M urea resulted in an increase in fluorescent intensity, which indicates that the emission from tryptophan in the native state is quenched. Comparison of urea-induced protein unfolding curves provide further evidence that decorin and biglycan assume different structures in solution. Decorin proteoglycan and core protein unfold in a manner similar to a classic two-state model, in which there is a steep transition to an unfolded state between 1 and 2 M urea. The biglycan core protein also shows a similar steep transition. However, biglycan proteoglycan shows a broad unfolding transition between 1 and 6 M urea, probably indicating the presence of stable unfolding intermediates.     

Electrodeposited MnOx Films from Ionic Liquid for Electrocatalytic Water Oxidation

A novel method for the electrodeposition of highly active water oxidation catalysts is described. The manganese oxide (MnO_x) films are electrodeposited on fluorine tin oxide (FTO) glass substrate at high temperature (120 °C) from an ionic liquid electrolyte (ethylammonium nitrate). A range of analytical techniques, including X‐ray absorption spectroscopy (XAS), X‐ray diffraction (XRD), and energy‐dispersive X‐ray analyzer (EDX), indicate that the valence state of manganese in the deposited films can be controlled by changing the electrolyte composition. Along with the different phase compositions, a number of different morphologies including nanowires, nanoparticles, nanofibers as well as highly open and dense structures are obtained by varying the acidity of the electrolyte. The effect of morphology and chemical composition on the catalytic activity towards water oxidation is investigated. The film composed of Mn₃O₄ shows low catalytic activities, while the films composed of birnessite‐like manganese oxide phase and Mn₂O₃ exhibit high catalytic activities for water oxidation. The catalytic activities are also affected by the surface morphology, i.e., a higher surface area and more open structure shows a higher catalytic activity. High rates of oxygen production are observed from MnO_x films prepared in a neutral electrolyte.     

D-glyceraldehyde-3-phosphate dehydrogenase. Amino-acid sequence of the enzyme from the extreme thermophile Thermus aquaticus

1. The amino acid sequence of D-glyceraldehyde-3-phosphate dehydrogenase from the extreme thermophile Thermus aquaticus has been elucidated. 2. The polypeptide contains 332 amino acids and its sequence is 70% identical with that of the enzyme from the moderate thermophile Bacillus stearothermophilus. 3. In contrast to less thermostable forms of the enzymes from B. stearothermophilus, pig, lobster and yeast, the T. aquaticus enzyme has only one cysteine residue, namely cysteine-149 which is required for catalysis.     

An X-Ray Scattering Study into the Structural Basis of Corneal Refractive Function in an Avian Model

Avian vision diseases in which eye growth is compromised are helping to define what governs corneal shape and ultrastructural organization. The highly specific collagen architecture of the main corneal layer, the stroma, is believed to be important for the maintenance of corneal curvature and hence visual quality. Blindness enlarged globe (beg) is a recessively inherited condition of chickens characterized by retinal dystrophy and blindness at hatch, with secondary globe enlargement and loss of corneal curvature by 3–4 months. Here we define corneal ultrastructural changes as the beg eye develops posthatch, using wide-angle x-ray scattering to map collagen fibril orientation across affected corneas at three posthatch time points. The results disclosed alterations in the bulk alignment of corneal collagen in beg chicks compared with age-matched controls. These changes accompanied the eye globe enlargement and corneal flattening observed in affected birds, and were manifested as a progressive loss of circumferential collagen alignment in the peripheral cornea and limbus in birds older than 1 month. Progressive remodeling of peripheral stromal collagen in beg birds posthatch may relate to the morphometric changes exhibited by the disease, likely as an extension of myopia-like scleral remodeling triggered by deprivation of a retinal image.     

猪CFL2b基因在成肌细胞中的表达及对肌球蛋白重链基因表达的影响

猪CFL2b基因主要在骨骼肌中表达,对肌肉的发育和肌纤维的形成具有一定作用。为了解猪CFL2b基因与肌纤维性状的相关性,利用定向克隆和基因转染技术获得能稳定表达猪CFL2b基因的成肌细胞株,荧光显微镜观察及Western Blotting检测CFL2b基因在成肌细胞中的表达;应用实时定量PCR技术对细胞内肌球蛋白重链基因（MyHC）的表达变化进行检测。结果显示：CFL2b基因对MyHC的表达有明显影响,其中MyHC2x基因和MyHC26基因的表达明显上调,MyHCl／slow的表达变化不明显。表明CFL2b基因与猪的肌纤维性状密切相关,推测猪CFL2b基因的高表达可能导致猪的不良肉质性状,可以考虑将CFL2b基因作为猪肉质性状的候选基因[动物学报54（6）：1014—1019,2008]。     

Henbane—Healing herb of hercules and of apollo

Economic Botany - This poisonous drug, formerly available only from Europe, India and the Sudan but now produced also in the United States to the extent of 80,000 pounds annually, has been used...     

巴松措原生动物群落结构季节及垂直分布

为揭示我国西藏高原湖泊原生动物群落结构特征及垂直分布格局,于2017年11月及2018年5月和9月,在巴松措中心分7层设置采样点,利用25号浮游生物网采集原生动物。采用活体观察和固定染色相结合的方法,共鉴定到原生动物195种(其中春季86种,夏季93种,秋季80种),隶属于2门11纲24目43科59属。其中以肉鞭门种类较丰富,砂壳类纤毛虫占优势。垂直分布的物种组成和群落结构复杂表现为：表层>中层>底层,物种多样性、丰富度和优势度指数表现为：表层>中层>底层,均匀度指数大多数为1;季节分布的物种组成和群落结构群复杂程度表现为：夏季>春季>秋季,物种多样性、丰富度指数表现为：夏季>秋季>春季,优势度指数表现为：夏季>秋季>春季,均匀度指数表现为：秋季>春季>夏季;优势物种和群落结构都会随水深的增加而减少。总体呈现出物种多样性较低、均匀度较高,具有明显的时空异质性。     

Cluster-root production and organic anion exudation in a group of old-world lupins and a new-world lupin

We examined the capacity of several Old-World lupin species (Lupinus luteus L., L. hispanicus Boiss. et Reuter and L. angustifolius L.) and one species of a New-World lupin (L. mutabilis Sweet) to form cluster roots under a range of conditions in solution culture. The effect of the synthetic auxin, IBA (indole-3-butyric acid), on cluster-root development in L. luteus and L. albus L. provided with an adequate phosphorus (P) supply was also investigated. In addition, the effect of a high nitrate-N (NO₃-N) supply on the efflux of citrate and malate from roots of L. angustifolius was examined to determine if specific regions of the root system exuded these organic anions. When P-deficient, L. hispanicus, L. luteus and L. mutabilis formed cluster roots that secreted organic anions. Citrate was generally the dominant organic anion exuded, although succinate was also exuded in large quantities from L. luteus. Citrate efflux by L. hispanicus and L. luteus was at least comparable to that reported for P-deficient L. albus[up to 1.092 nmol g^–1 fresh weight (FW) s^–1], but was over an order of magnitude lower in L. mutabilis (0.036 nmol g^–1 FW s^–1). Citrate and malate were not detected in significant amounts from either the lateral roots or the root tips of any species grown under P-sufficient or -deficient conditions. Citrate efflux from cluster roots of L. luteus showed a diurnal pattern, similar to that reported for L. albus, with maximum efflux during the day, and declining to a minimum before dawn. IBA added to the nutrient solution induced cluster-root formation on both L. albus and L. luteus at concentrations of P that would normally suppress the production of these roots. However, the IBA-induced cluster roots did not exude significant amounts of citrate. Although L. angustifolius did not produce cluster roots when P-deficient, it produced cluster-like root structures that exuded citrate (0.053 nmol g^–1 FW s^–1) when grown at a high nitrate-N (NO₃-N) supply. L. angustifolius did not exude significant citrate or malate from lateral roots or root tips when grown at either high or low NO₃-N supply. Our findings for L. hispanicus and L. luteus are the first reports of cluster-root formation in response to P deficiency for these Old-World species, and for L. mutabilis, it is the first report of cluster roots for a New-World lupin species. These reports indicate that evolutionary and biogeographical aspects of cluster-root formation in the genus Lupinus need to be revised. Furthermore, investigation is warranted to determine the capacity of species of the large group of New-World lupins to form cluster roots in soils of their native habitats.     

Thick and thin fingers point out Turing waves

Mouse genetics and computer simulations demonstrate that digit number and width are controlled by a Turing-type mechanism in which distal Hox genes modulate periodicity.