Rare earth thiocyanate complexes with tripiperidinophosphine oxide: synthesis and characterization. Crystal structure of Pr(SCN)3(tpppO)3

The synthesis and characterization of rare-earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) thiocyanate adducts with tripiperidinophosphine oxide (tpppO) with general formula (RE)(SCN)₃(tpppO)₃ are reported. Conductance measurements in acetonitrile indicate the non-electrolytic nature of the complexes. Infrared absorption spectra evidence that the SCN⁻ ion coordinates through the nitrogen atom (isothiocyanate form) and that tpppO coordinates through the phosphoryl oxygen. X-ray powder patterns suggest the existence of three different crystal forms: (1) La; (2) an isomorphous series including Ce, Nd and Pr; and (3) another isomorphous series, including Sm, Gd, Eu, Ho, Er, Tb, Lu and Y. The visible spectra of the Nd adduct and the calculated parameters β = 0.98, b^1/2 = 0.072 and δ = 1.06 indicate that the metal-ligand bonds are essentially electrostactic. The emission spectra of the Eu compound showed ⁵D₀ → ⁷F_J bands (J = 0, 1, 2), suggesting a C_3v symmetry for the coordination polyhedron. The lifetime of the ⁵D₀ state is 1.28 ms. The emission spectra of the Tb complex presented ⁵D₄ → ⁷F_J bands (J = 4, 5, 6) and the Dy complex showed the ⁴F_9/2 → ⁶H_13/2 band. The structure of the Pr complex showed that the coordination polyhedron is a trigonal antiprism, with the isothiocyanate anions in one base and three tpppO ligands in the other. Thermal analyses (TG-DTG) were carried out for the Ce, Nd and Gd adducts. Mass losses start between 250 and 334 °C. The final residues at 1300 °C are the corresponding phosphates.     

四川宝兴雉类生态和垂直分布的调查研究

宝兴位于四川盆地西缘山地,境内纵贯世界闻名的大雪山——即夹金山。 自19世纪30年代至20世纪30年代,先后有Verreaux(1838—1871),Geoffroy(1866),David(1871),Seinhoe(1871),Sharpe(1875),David et Oustalet(1877),Oustaler (1891—92),Styan(1899),Laubmann(1920),La Touch(1925—30),Smith(1931—34),Bangs(1932),Seys(1934)等对宝兴进行过调查和采集,而我     

Genetic diversity among progenitors and elite lines from the Iowa Stiff Stalk Synthetic (BSSS) maize population: comparison of allozyme and RFLP data

Summary Data for restriction fragment length polymorphisms (RFLPs) of 144 clone-enzyme combinations and for 22 allozyme loci from 21 U.S. Corn Belt maize (Zea mays L.) inbreds were analyzed. The genetic materials included 14 progenitors of the Iowa Stiff Stalk Synthetic (BSSS) maize population, both parents of one missing BSSS progenitor, four elite inbreds derived from BSSS, and inbred Mo17. Objectives were to characterize the genetic variation among these 21 inbreds for both allozymes and RFLPs, to compare the results from both types of molecular markers, and to estimate the proportion of unique alleles in the BSSS progenitors. Genetic diversity among the 21 inbreds was substantially greater for RFLPs than for allozymes, but the percentages of unique RFLP variants (27%) and unique allozyme alleles (25%) in the BSSS progenitors were similar. Genetic distances between inbreds, estimated as Rogers' distance (RD), were, on average, twice as large for RFLP (0.51) as for allozyme data (0.24). RDs obtained from allozyme and RFLP data for individual line combinations were only poorly correlated (r = 0.23); possible reasons for discrepancies are discussed. Principal component analysis of RFLP data, in contrast to allozyme data, resulted in separate groupings of the ten BSSS progenitors derived from the Reid Yellow Dent population, the four BSSS elite lines, and Mo17. The remaining six BSSS progenitors were genetically rather diverse and contributed a large number of rare alleles to BSSS. The results of this study corroborate the fact that RFLPs are superior to allozymes for characterizing the genetic diversity of maize breeding materials, because of (1) the almost unlimited number of markers available and (2) the greater amount of polymorphisms found. In particular, RFLPs allow related lines and inbreds with common genetic background to be identified, but a large number of probe-enzyme combinations is needed to estimate genetic distances with the precision required.Joint contribution from Cereal and Soybean Research Unit, USDA, Agricultural Research Service, and Journal Paper No. J-14236 of the Iowa Agricultural and Home Economics Experiment Station, Projects 2818 and 2778     

大熊猫(Ailuropoda melanolenca)显带染色体的研究

大熊猫系我国特产的世界珍稀动物,素有“活化石”和“国宝”之称。限于材料来源,虽有核型的少数报道（邓承宗等,1980;陈文元等,1984;Newnham et al.,1966）,但研究尚不够深入。1980年,Wurster-Hill和Bush首先报道了大熊猫（）的显带核型,并与杂交熊等比较,探讨了大熊猫的分类地位。本文对四只大熊猫的G带、C带核型和Ag-NORs作了分析,绘制了G带核型模式图,并提出了某些商榷的意见。     

Population fragmentation may reduce fertility to zero in Banksia goodii — a demonstration of the Allee effect

All individuals of all known populations of Banksia goodii were assessed for seed production. Small populations produced no or only a few seeds per unit canopy area. Effects of population size on seed production per unit area and seed production per plant were present over the whole range of population sizes, indicating that even in large populations seed production may still not be at its maximum. Resource differences could not explain this disproportionate decrease in seed production with decline in population size, because there were no differences in soil properties and understorey or overstorey cover between the small and large populations. Although plants in small and large populations were similar in size, seed production per plant was much lower in small populations. This was not because plants in small populations produced fewer cones but because the fraction of these cones that was fertile was much lower. Five of the nine smallest populations (<200 m²) produced no fertile cones over the last 10 years. The number of seeds per fertile cone did not depend on population size. The results are discussed in relation to pollination biology.     

氯化镧对玉米根切段钾离子外渗影响的动力学研究

研究了氯化镧对玉米(Zea mays L.)“京早8号”根切段细胞膜透性及质子分泌的影响,并用动力学方法研究了钾离子外渗过程的变化。氯化镧处理可降低外渗液的电导率及K~ 和糖的外渗量,使质子分泌活动增强。用动力学方法分析玉米根切段K~ 外渗过程的结果表明:(1)应用于K~ 吸收研究的数学模型也能适应于K~ 外渗的研究;(2)在LaCl_3和(或)CaCl_2存在的条件下,最大吸收速度(V_(max))升高,而米氏常数(K_m)没有变化;(3)在LaCl_3和(或)CaCl_2存在的条件下,K~ 外渗量降低是由于最大吸收速度(V_(max))升高所致。     

Rare earth cerium oxide nanoparticles attenuated liver fibrosis in bile duct ligation mice model

Liver fibrosis is one of the major liver complications which eventually progresses to liver cirrhosis and liver failure. Cerium oxide nanoparticles, also known as nanoceria (NC) are nanoparticles with potential antioxidant and anti-inflammatory activities. Herein, we evaluated the hepatoprotective and anti-fibrotic effects of nanoceria (NC) against bile duct ligation (BDL) induced liver injury. NC were administered i.p. for 12 days (0.5 and 2 mg/kg) to C57BL/6J mice. The biochemical markers of liver injury, oxidative and nitrosative stress markers, inflammatory cytokines were evaluated. Fibrosis assessment and mechanistic studies were conducted to assess the hepatoprotective effects of NC. Administration of NC proved to significantly ameliorate liver injury as evident by reduction in SGOT, SGPT, ALP and bilirubin levels in the treated animals. NC treatment significantly reduced the hydroxyproline levels and expression of fibrotic markers. In summary, our findings establish the hepatoprotective and anti-fibrotic effects of NC against BDL induced liver injury and liver fibrosis. These protective effects were majorly ascribed to their potential ROS inhibition and antioxidant activities through catalase, superoxide dismutase (SOD)-mimetic properties and auto-regenerating capabilities.     

EVIDENCE OF AN ORGANIC MATRIX FROM DIATOM BIOSILICA1

Most biominerals appear to be composites of organic material and mineral. Whether biosilica is such a composite is unresolved because of a lack of evidence for such organic components. We present evidence that organic material exists within diatom biosilica and can be extracted using HF/NH₄F solutions from frustules isolated from Cyclotella meneghiniana Kütz and diatomaceous earth. To eliminate organic casing on the silicified frustules as a source of organic materials, the casing was removed by oxidation of frustules with NaOCl before extraction. The removal of the casing was confirmed in that oxidized frustules no longer displayed the ability to be stained with ruthenium red and fluorescamine. Frustules examined with EDXA showed an emission peak from sulfur before treatment but no peak following treatment, indicating that oxidation removed organic sulfur. The organic material obtained from extracts of fresh frustules contained both soluble and insoluble components. Only soluble material was evident in extracts from diatomaceous earth. The soluble material appears to contain glycoproteins with relatively high levels of serine and glycine. The soluble proteins from fresh frustules also appear to be phosphorylated. Indirect evidence is presented that suggests the soluble proteins may contain regions of primary structure enriched in anionic amino acids. The soluble extracts differ from general cell contents when the two fractions are compared, suggesting that frustules contain specialized organic material. The identification of silica-specific organic material suggests that mineralization in diatoms may be in part matrix-mediated.     

A test for preference of association in a color polymorphic poeciliid fish: laboratory study

Synopsis The ecological and evolutionary forces maintaining genetic polymorphism within populations is of continuing interest to evolutionary biologists. Male pygmy swordtails,Xiphophorus pygmaeus, are polymorphic at a Y-linked locus controlling body color. Fish with the + and cp alleles have blue bodies; those with the con allele have bright gold bodies. Male and female fish were tested in the laboratory to determine if there were any preferences for association with groups of male fish based on color. Single test fish were presented with two groups of males of different phenotypes, and times in which the test fish spent in proximity to each group were recorded. Males of different phenotypes showed no differences in preference, nor did phenotype of the males in the groups affect the behavior of the test fish. Females also showed no preference for males of a particular phenotype. Finally, female test fish showed no preference for groups containing a male with the rare phenotype compared to a group containing all males of the same phenotype.     

Blood genetic systems in four Amazonian tribes.

Data on 31 genetic systems were obtained for 421 individuals belonging to the Arara, Araweté, Mundurucu, and Jamamadi tribes of northern Brazil. The Jamamadi depart farthest, and the Mundurucu least, from South American Indian averages. These data are analyzed together with those of 24 other Amazonian groups. Genetic distances and corresponding dendrograms indicate a cluster of 14 related tribes living north of the Amazon river. These genetic results show only a modest correlation with linguistic and geographic relationships among these groups.