Domain II + III of bovine serum albumin: Isolation and its characterization

Some properties of a fragment of bovine serum albumin containing residues 184–582 of the protein sequence, produced by cyanogen bromide cleavage, have been reported. Urea-induced difference spectra of the fragment showed considerable exposure of aromatic chromophores by 8 M urea. Reversible unfolding of the fragment by urea, as followed by difference spectral measurements at 30°C, pH 7.0, occurred in two distinct steps involving at least 3 major conformational states, namely the native (N), intermediate (X) and completely denatured (D) states. The co-operativity values for the two transitions, N⇌X and X⇌Dwere found to be 4.0 and 16.4, respectively. Analysis of the data on bilirubin binding to bovine serum albumin and its fragment suggested that the fragment retains significant amount of its native structure. However, hydrodynamic parameters such as Stokes radius (3.f14 nm), diffusion coefficient (6.98 × 10⁻⁷cm²/s) and frictional ratio (1.32) obtained by analytical gel chromatography as well as intrinsic viscosity (4.31 ml/g) indicates some asymmetry in the fragment molecule.     

Evidence that the same structural gene encodes testicular and adrenal 3β-hydroxysteroid dehydrogenase-isomerase

Thermostability of 3-hydroxysteroid dehydrogenase-isomerase (3HSD) activity was examined in testes and adrenal glands from several inbred lines and feral mice. A thermolabile varant of 3HSD was detected in the feral Brno mice. The thermostability (t _1/2) of 3HSD was approximately 7 min for both testes and adrenal glands from C57BL/6J mice, compared with 4 min for both tissues from Brno mice. Comparison of testicular and adrenal 3HSD thermostability in six kinds of mice indicated that the t _1/2of 3HSD was correlated in the two tissues and could be classified into two distinct types, thermolabile and thermostable. In contrast, quantitative variants in 3HSD activity were not correlated in the two tissues. These data are consistent with the hypothesis that testicular and adrenal 3HSD is encoded by the same structural gene but that expression of 3HSD activity is independently controlled in testes and adrenal glands.This work was supported by NICHHD National Research Service Award HD-06392 to J.R.D.S. and Grant HD-17916 to A.H.P.     

Probing ecosystem health: a multi-disciplinary and multi-trophic assay strategy

The ecosystem health of stressed environments in the Great Lakes has been evaluated simultaneously by means of a battery of structural and functional tests based on current technology and involving various trophic levels. These tests attempt to assess ecosystem health at the organism level and simultaneously focus on water-borne and sediment-bound toxicities. The use of structural indicators has been successfully demonstrated. Similarly, functional tests were selectively chosen across various trophic levels and included size-fractionated primary productivity (filtered versus unfiltered assays), and Colpidium, Daphnia, Hyalella, and Pontoporeia assays. Some of the emerging techniques such as in situ plankton cages (I.P.C.), microcomputer-based chlorophyll fluorescence (Video Analysis System), and other assays are discussed. The multi-trophic and multi-disciplinary battery of tests followed in our laboratory adopts a field-to-laboratory approach. The availability of diverse bioassays have placed toxicologists and environmentalists in a position where they are now better equipped to probe the complexities of ecosystem health and its management.Dedicated to the memory of my mother who was a great teacher, guide and an incredible source of inspiration.     

Structural variability and chromosome numbers variation in natural populations ofScilla autumnalis (Liliaceae)

Chromosome variability within three populations ofScilla autumnalis was analysed. Among a total of 167 individuals we have detected one triploid structural heterozygote, 26 B-containing (with two different B-types), 11 structural variants (in the fifth chromosome pair), and one asynaptic. The possible relation between both types of chromosome variability (structural and chromosome numbers) is discussed.     

Influence of proteolytic enzymes and calcium-binding agents on nuclear and cell surface topography

Summary Transmission electron microscopy was used to study the effects of proteolytic enzymes (collagenase, trypsin, clostripain), the calcium chelator ethyleneglycol-bis-(-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA), and the calcium ionophore A 23187 on substrate adhesion and fine structure of chondrocytes and fibroblasts. Monolayer cultured cells responded to treatment with the proteolytic enzymes followed by EGTA or A 23187 by rounding and detaching from the substrate. This was accompanied by the formation of a microvillous surface, deep nuclear folds, and numerous cytoplasmic vacuoles. Labeling experiments with colloidal thorium dioxide indicated that the vacuoles were formed by endocytosis and fusion of endocytic vesicles with preexisting lysosomes. To a variable extent, similar changes were produced by trypsin or EGTA alone. The cells regained their normal fine structure after withdrawal of the reagents and when seeded onto a substrate. In suspension culture, recovery was incomplete; the cells retained a rounded shape and an increased number of cytoplasmic vacuoles.The results suggest that changes in plasma membrane composition and its permeability to calcium represent the primary signal for cell rounding and detachment. The cellular mechanisms responsible for the associated folding of the nuclear envelope and the cell surface remain unidentified. Nevertheless, this is believed to represent a means of handling of excess membrane during sudden transition from a flattened to a rounded shape. Membrane stored in folds and vacuoles is reutilized when the cells reattach and spread out on a substrate.Expert technical assistance was provided by Karin Blomgren and Anne-Marie Motakefi. Financial support was obtained from the Swedish Medical Research Council (06537), the King Gustaf V 80th Birthday Fund and from the Funds of Leiden University     

头花杜鹃、陇蜀杜鹃及杜鹃属植物叶绿体基因组比较分析

头花杜鹃(Rhododendron capitatum)和陇蜀杜鹃(R. przewalskii)是极具观赏价值的野生花卉和药用植物。为探讨头花杜鹃和陇蜀杜鹃叶绿体基因组的遗传结构及进化特征,该研究利用 Illumina HiSeq 4000 平台对头花杜鹃和陇蜀杜鹃的叶绿体全基因组进行测序,经组装和注释后,结合 7 个已发表的杜鹃属植物叶绿体全基因组进行比较基因组学分析和系统发育分析。结果表明:(1)头花杜鹃和陇蜀杜鹃叶绿体全基因组呈典型的环状四分体结构,均由一个大单拷贝区(105 990、109 191 bp)、一个小单拷贝区(2 617、2 606 bp)和一对反向重复区(45 825、47 516 bp)构成,全长分别为200 257、206 829 bp。(2)头花杜鹃和陇蜀杜鹃叶绿体基因组中共鉴定出 263 个SSR位点,大部分 SSR 偏好使用 A/T 碱基,密码子偏好使用 A/U 结尾。(3)杜鹃属植物叶绿体全基因组中普遍存在基因丢失以及基因组重排等结构变异现象。该研究丰富了杜鹃属植物的基因组资源,为头花杜鹃、陇蜀杜鹃的资源开发、遗传进化、育种及系统发育相关研究提供了理论参考。     

C and N utilization of two lettuce genotypes during growth under non-varying light conditions and after changing the light intensity

Growth and N-incorporation in two lettuce genotypes ( Lactuca sativa L. cv. Deci minor and cv. Grosse brune), which differ significantly in nitrate accumulation, were studied. Under constant environmental conditions cv. Deci minor produced more fresh and dry weight than cv. Grosse brune. Cultivar Deci minor also produced more fresh weight per mmol N absorbed than cv. Grosse brune, and contained less organic nitrogen in the dry matter, but accumulated more nitrate. As cv. Deci minor showed a higher fresh and dry weight production per mmol N absorbed than cv. Grosse brune, it used its nitrogen more efficiently.
When the light intensity was decreased, the growth of both cultivars decreased, and the fresh weight production per mmol N absorbed increased. After reduction of the light intensity, cv. Deci minor maintained a higher fresh weight production per N absorbed than before, whereas cv. Grosse brune returned to its original level. After decrease of the light intensity, an increased nitrate concentration in the cell sap was accompanied by a decreased concentration of organic compounds in both cultivars. The organic nitrogen level in the dry matter remained constant after the higher intensity was reduced. However, due to the decreased dry weight percentage, the demand for nitrogen for protein synthesis decreased on fresh weight basis.
It can be concluded that the two cultivars differ in their partition of C and N between dry matter and cell sap. Nitrate accumulation in preference to accumulation of organic compounds does not automatically result from a shortage of organic compounds. The high accumulation of nitrate of cv. Deci minor enables it to use more carbohydrates for structural growth than cv. Grosse brune.     

A functional genomics approach to evaluate candidate genes located in a QTL interval for milk production traits on BTA6

The potential genetic and economic advantage of marker-assisted selection for enhanced production in dairy cattle has provided an impetus to conduct numerous genome scans in order to identify associations between DNA markers and future productive potential. One area of focus has been a quantitative trait locus on bovine chromosome 6 (BTA6) found to be associated with milk yield, milk protein and fat percentage, which has been subsequently fine-mapped to six positional candidate genes. Subsequent investigations have yet to resolve which of the potential positional candidate genes is responsible for the observed associations with productive performance. In this study, we analysed candidate gene expression and the effects of gene knockdown on expression of β- and κ-casein mRNA in a small interfering RNA transfected bovine in vitro mammosphere model. From our expression studies in vivo , we observed that four of the six candidates ( ABCG2 , SPP1 , PKD2 and LAP3 ) exhibited differential expression in bovine mammary tissue over the lactation cycle, but in vitro functional studies indicate that inhibition of only one gene, SPP1 , had a significant impact on milk protein gene expression. These data suggest that the gene product of SPP1 (also known as osteopontin) has a significant role in the modulation of milk protein gene expression. While these findings do not exclude other positional candidates from influencing lactation, they support the hypothesis that the gene product of SPP1 is a significant lactational regulatory molecule.     

Quantitative trait loci for porcine white blood cells and platelet-related traits in a White Duroc × Erhualian F2 resource population

White blood cell count and platelets are implicated as risk factors for common complex diseases. Genetic factors substantially affect these traits in humans and mice. However, little is known about the genetic architecture of these traits in pigs. To identify quantitative trait loci (QTL) for leucocyte- and platelet-related traits in pigs, the total leucocyte number and differential leucocyte counts including the fraction of basophils, eosinophils, lymphocytes, monocytes, neutrophils, and a series of platelet parameters including platelet count, mean platelet volume, platelet distribution width and plateletcrit were measured in 1033 F₂ animals on 240 days from a White Duroc × Erhualian intercross resource population. A total of 183 informative microsatellites distributed across 19 pig chromosomes (SSC) were genotyped across the entire resource population. Thirty-three QTL were identified for the examined traits, including eight genome-wide significant QTL for white blood cells and differential leucocyte counts on SSC2, 7, 8, 12 and 15 and six significant QTL for platelet-related traits on SSC2, 8, 13 and X. Erhualian or White Duroc alleles were not systematically associated with increased phenotypic values. These results not only confirmed many QTL identified previously in the mouse and swine, but also revealed a number of novel QTL for the traits recorded. Moreover, it is the first time that QTL for platelet-related traits in pigs have been reported.