The effects of dispersal limitation and topographic heterogeneity on beta diversity and phylobetadiversity in a subtropical forest

We assessed the effects of topographic heterogeneity and stem density on species composition between grains of different sizes (20 × 20, 50 × 50, and 100 × 100 m), based on partial Mantel tests. Similarity in species composition was measured by the abundance-based Jaccard index (C_J) and by an index that incorporates phylogenetic information into C_J (pC_J). Plants were divided into five groups, arbor, subarbor, and shrub according to life form and two other groups: species that produce dry fruits (PDF) and that produce fleshy fruits (PFF). C_J and pC_J between any two grains at each grain size were calculated separately for these groups and for all species combined. In order to examine what influences C_J and pC_J, we analyzed their correlations with topographic heterogeneity variables and two dispersal limitation-related variables (stem and topographic resistance). Our data indicate that at all three grain sizes, C_J and pC_J decrease with increasing distance for all plant groups. Dispersal limitation and topographic heterogeneity were both important at 20 × 20 and 50 × 50 m grain sizes for C_J and pC_J of all plant groups; and at 100 × 100 m grain size, topographic heterogeneity dominates over dispersal limitation for some plant groups. C_J and pC_J of PDFs are less negatively correlated with stem resistance than those of PFFs. We conclude that both beta diversity and phylobetadiversity are dependent on plant groups and grain sizes.     

Genome‐wide scans to detect positive selection in Large White and Tongcheng pigs

Due to the direction, intensity, duration and consistency of genetic selection, especially recent artificial selection, the production performance of domestic pigs has been greatly changed. Therefore, we reasoned that there must be footprints or selection signatures that had been left during domestication. In this study, with porcine 60K BeadChip genotyping data from both commercial Large White and local Chinese Tongcheng pigs, we calculated the extended haplotype homozygosity values of the two breeds using the long‐range haplotype method to detect selection signatures. We found 34 candidate regions, including 61 known genes, from Large White pigs and 25 regions comprising 57 known genes from Tongcheng pigs. Many selection signatures were found on SSC1, SSC4, SSC7 and SSC14 regions in both populations. According to quantitative trait loci and network pathway analyses, most of the regions and genes were linked to growth, reproduction and immune responses. In addition, the average genetic differentiation coefficient F_ST was 0.254, which means that there had already been a significant differentiation between the breeds. The findings from this study can contribute to further research on molecular mechanisms of pig evolution and domestication and also provide valuable references for improvement of their breeding and cultivation.     

In vitro acetylation of the liver HMG non-histone proteins and its modulation by spermine and dexamethasone during aging of rats

The in vitro acetylation of HMG proteins was studied using liver slices of young (18-week) and old (138-week) male rats. Acetylation of total HMG proteins is lower in old age. The incorporation of (¹⁴C) acetate into individual HMG proteins varies remarkably with advancing age. Whereas acetylation of high mol. wt. proteins (HMG 1 and 2) is higher, that of low mol. wt. proteins (HMG 14 and 17) is lower in the liver of young rats as compared to the old ones. Spermine stimulates the acetylation of HMG 1 and 14 in young and HMG 1, 2 and 14 in old age. It inhibits the acetylation of HMG 17 in both ages. Dexamethasone decreases the level of incorporation of (¹⁴C) into HMG 1 and 17 in young and HMG 14 and 17 in old rats. On the other hand, it stimulates the acetylation of HMG 14 by two-fold in young and that of HMG 1 and 2 by more than three-fold in old rats. Such alteration in the acetylation of HMG proteins may account for age-related changes in the structure and function of chromatin.     

Hidden smectic properties of a chiral side-chain co-oligomer

We recently showed that a side-chain industrial co-oligosiloxane presents a quenchable enlarged blue phase behaviour at the cholesteric-isotropic phase transition. In this paper, we present the results of a structural study based on X-ray diffraction, differential scanning calorimetry and optical measurements. In particular, the smectic A organisation is demonstrated in the lower temperature domain, which was hitherto understood as a cholesteric phase. A structural model for this phase is proposed on the basis of the analysis of the anisotropic scattering of stretched fibers. Our results also suggest that the observed glass transition is indeed a rather complex phenomenon, which seems to involve not only the freezing of the main chains, but also smectic correlations at the side-chain level. Moreover, the calorimetric study indicates that, notwithstanding the conservation of the processed film's optical properties, low kinetic reorganisations occur at room temperature.     

Prosopis juliflora pollen allergen induced hypersensitivity and anaphylaxis studies in guinea pigs

In vivo and in vitro allergenic activities of Prosopis juliflora pollen allergens were measured in guinea pigs. Intracutaneous skin test showed an early wheal flare response and a late erythema-redness, sensitized with various concentrations (100, 50, 25, 5 and 1.5 micrograms/ml) of Prosopis juliflora pollen extract after administration of a challenging dose. A 50 micrograms/ml sensitizing dose of Prosopis juliflora pollen allergen gave optimum skin response as both early and late effects. The nature of immunochemical reactivity between pollen allergens and reaginic antibodies were further characterized by histamine release test, gel diffusion test, radioallergosorbent test and passive cutaneous anaphylaxis test. These tests confirm allergenicity caused by Prosopis juliflora pollen allergens and showed the binding of allergens with reaginic antibody and its regulation in guinea pigs.     

云南10个民族红细胞酸性磷酸酶型分布调查

用淀粉凝胶电泳法对云南省汉族及9个少数民族的红细胞酸性磷酸酶(ACP_1)的表型分布进行了调查,检出A、BA和B3种表型,计算得云南汉、彝、白、傣、瑶、佤、哈尼、布朗、基诺和拉祜族ACP_1~A、ACP_1~B的基因频率依次为0.2067、0.7933;0.2406、0.7594;0.2341、0.7659;0.3750、0.6250;0.2300、0.7700;0.2727、0.7273;0.3594、0.6406;0.3036、0.6964;0.2381、0.76119和0.4474、0.5526。未发现ACP_1~C基因及其它稀有基因。研究表明,ACP_1表型的分布存在着一定的种族与民族差异。     

Characterization of Senescence in Lemna gibba G3: A Determinate Growth System

Frond senescence in Lemna gibba G3 was characterized, and itscontrol by light, ABA and kinetin investigated. The plant exhibitsa determinate growth pattern with a frond producing a set numberof daughter fronds before undergoing senescence and death regardlessof whether or not it flowers. When a frond was cut in half,the distal half (half frond) which lacks any meristem underwentrapid senescence as compared with intact fronds. In both intactand half fronds, the onset of senescence was accelerated byABA and retarded by kinetin. Continuous white light acceleratedsenescence in both intact and half fronds over the dark controls.Under different photoperiodic light regime, the pace of daughterfrond production is accelerated in proportion to the lengthof light period. In half fronds, however, very short photoperiodiclight treatments (e.g. 1L: 23D or 3L: 21D) rather delayed senescenceover the dark controls. Two separate light control systems operatingin opposite directions in Lemana senescence appear to exist. ¹Present address: Department of Biology, Yonsei University,Seoul 120-749, Korea ²Present address: U.S. Department of Agriculture, Aero SpaceBuilding, Rm. 323, 901 D Street, S.W., Washington, D.C. 20251-2200, U.S.A. (Received July 13, 1989; Accepted May 8, 1990)     

Steroidal glycosides from Agave cantala.

Two new steroidal glycosides, agaveside A and B, isolated from the fruits of Agave cantala were characterized as 3 beta-O-[beta-D-xylopyranosyl-(1----2),beta-D-xylopyranosyl-(1----3), beta-D-glucopyranosyl-(1----3)-[beta-D-xylopyranosyl-(1----3)-beta-D- galactopyranosyl-(1----2)]-beta-D-glucopyranosyl]-(25R)-5 alpha-spirostane and 3 beta-O-[beta-D-xylopyranosyl-(1----2), beta-D-xylopyranosyl-(1----3)-beta-D-glucopyranosyl-(1----3)- [beta-D-galactopyranosyl-(1----2)]-beta-D-glucopyranosyl]-(25R)-5 alpha-spirostane. The structures were elucidated by a combination of 13CNMR spectroscopy, chemical degradation and fast atom bombardment mass spectrometry.     

Phenylmethylsulfonyl fluoride stimulates proteolysis of nuclear proteins from chick liver.

The degradation of H1 histone and high mobility group (HMG) nonhistone proteins was stimulated when the homogenate from chick liver was incubated in the presence of phenylmethylsulfonyl fluoride (PMSF). Two proteinase inhibitors, elastatinal and chymostatin, significantly inhibited the PMSF-stimulated degradation of H1 histone and HMG proteins. On the contrary, other proteinase inhibitors like leupeptin, pepstatin, trypsin inhibitor, antipain, o-phenanthroline and EDTA had no effect on the degradation of the nuclear proteins. These results warn the researcher to be cautious while using PMSF for preparation of nuclear proteins such as H1 histone and HMG proteins.