Genetic diversity and origin of weedy rice (Oryza sativa f. spontanea) populations found in North-eastern China revealed by simple sequence repeat (SSR) markers

BACKGROUND AND AIMS: Weedy rice (Oryza sativa f. spontanea) is one of the most notorious weeds occurring in rice-planting areas worldwide. The objectives of this study are to determine the genetic diversity and differentiation of weedy rice populations from Liaoning Province in North-eastern China and to explore the possible origin of these weedy populations by comparing their genetic relationships with rice varieties (O. sativa) and wild rice (O. rufipogon) from different sources. METHODS: Simple sequence repeat (SSR) markers were used to estimate the genetic diversity of 30 weedy rice populations from Liaoning, each containing about 30 individuals, selected rice varieties and wild O. rufipogon. Genetic differentiation and the relationships of weedy rice populations were analysed using cluster analysis (UPGMA) and principle component analysis (PCA). KEY RESULTS: The overall genetic diversity of weedy rice populations from Liaoning was relatively high (H(e) = 0.313, I = 0.572), with about 35 % of the genetic variation found among regions. The Liaoning weedy rice populations were closely related to rice varieties from Liaoning and japonica varieties from other regions but distantly related to indica rice varieties and wild O. rufipogon. CONCLUSIONS: Weedy rice populations from Liaoning are considerably variable genetically and most probably originated from Liaoning rice varieties by mutation and intervarietal hybrids. Recent changes in farming practices and cultivation methods along with less weed management may have promoted the re-emergence and divergence of weedy rice in North-eastern China.     

Tubular stress proteins and nitric oxide synthase expression in rat kidney exposed to mercuric chloride and melatonin.

Stress proteins such as HSP70 members (HSP72 and GRP75) and metallothionein (MT) protect the kidney against oxidative damage and harmful metals, whereas inducible nitric oxide synthase (iNOS) regulates tubular functions. A single dose of mercuric chloride (HgCl(2)) can cause acute renal failure in rats, its main target being the proximal tubule. Oxidative damage has been proposed as one of its pathogenic mechanisms. In this study we tested whether melatonin (MEL), a powerful antioxidant compound, is effective against HgCl(2) nephrotoxicity. Rats were treated with saline, HgCl(2) (3.5 mg/kg), MEL (5 mg/kg), and MEL + HgCl(2) and examined after 24 hr for HSP72, GRP75, MT, and iNOS by immunohistochemistry and immunoblotting. Tubular effects of the treatment were then characterized by ultrastructure. In the HgCl(2) group, all markers were overexpressed in convoluted proximal tubules and sometimes in distal tubules. In the MEL + HgCl(2) group, GRP75 and iNOS decreased in convoluted and straight proximal tubules, whereas HSP72 and MT persisted more than the saline and MEL-only groups. Tubular damage and mitochondrial morphometry were improved by MEL pretreatment. In conclusion, the beneficial effect of MEL against HgCl(2) nephrotoxicity was outlined morphologically and by the reduction of the tubular expression of stress proteins and iNOS. These markers could represent sensitive recovery index against mercury damage.     

High molecular weight RNA containing histone messenger in the sea urchin Paracentrotus lividus

Sea urchin RNA extracted from early and mesenchyme blastula embryos and oocytes and fractionated on denaturing sucrose density gradients, was hybridized with histone DNA recombinants of Psammechinus miliaris (clone λh22) and of Paracentrotus lividus (clone pPH70). Histone sequences are found in the 9 S and larger than 9 S regions of the formamide/sucrose density gradients. The melting of the RNA-DNA duplexes obtained by hybridization of polysomal and high molecular weight RNA of embryos of P. lividus at the stage of early blastula, suggests a degree of heterogeneity in the high M_r RNA. The high M_r RNA contains at least four of the five histone gene sequences covalently linked.     

In vitro Biological Activities of Seed Essential Oils from the Cameroonian Spices Afrostyrax lepidophyllus Mildbr. and Scorodophloeus zenkeri Harms Rich in Sulfur‐Containing Compounds

The chemical composition of the essential oils obtained from the seeds of bush onion (Afrostyrax lepidophyllus) and tropical garlic tree (Scorodophloeus zenkeri), plants used as spices in the traditional African cuisine, was determined by GC‐FID and GC/MS analyses. Moreover, in vitro biological properties of the oils, namely, the cytotoxic, antioxidant, and antimicrobial activities, were investigated by the MTT, the DPPH^. and ABTS^.+ scavenging, and the agar disc‐diffusion methods, respectively. Both oils were composed mainly by S‐containing compounds, accounting for 91.0–96.1% of the total oil compositions, which provided them the typical garlic‐ and onion‐like odors of spices. The predominant compound in both oils, 2,4,5,7‐tetrathiaoctane ( 1 ; 51.5–52.9%), was isolated by preparative TLC and structurally elucidated by ¹H‐ and ¹³C‐NMR data. The oils exhibited a strong inhibitory effect on the growth of human cancer cells, namely, T98G (human glioblastoma multiforme cell line), MDA‐MB 231 (human breast adenocarcinoma cell line), A375 (human malignant melanoma cell line), and HCT116 (human colon carcinoma cell line) cells, and a good DPPH^.‐ and ABTS^.+‐scavenging activity, while the antimicrobial effects were negligible. The volatile compositions of A. lepidophyllus and S. zenkeri oils supported their use as odorous spices. The significant inhibition activities detected make these oils worthy of further investigation as promising chemopreventive agents to be exploited in the African pharmaceutical market.     

Controlled loading of oligodeoxyribonucleotide monolayers onto unoxidized crystalline silicon; fluorescence-based determination of the surface coverage and of the hybridization efficiency; parallel imaging of the process by Atomic Force Microscopy

Unoxidized crystalline silicon, characterized by high purity, high homogeneity, sturdiness and an atomically flat surface, offers many advantages for the construction of electronic miniaturized biosensor arrays upon attachment of biomolecules (DNA, proteins or small organic compounds). This allows to study the incidence of molecular interactions through the simultaneous analysis, within a single experiment, of a number of samples containing small quantities of potential targets, in the presence of thousands of variables. A simple, accurate and robust methodology was established and is here presented, for the assembling of DNA sensors on the unoxidized, crystalline Si(100) surface, by loading controlled amounts of a monolayer DNA-probe through a two-step procedure. At first a monolayer of a spacer molecule, such as 10-undecynoic acid, was deposited, under optimized conditions, via controlled cathodic electrografting, then a synthetic DNA-probe was anchored to it, through amidation in aqueous solution. The surface coverage of several DNA-probes and the control of their efficiency in recognizing a complementary target-DNA upon hybridization were evaluated by fluorescence measurements. The whole process was also monitored in parallel by Atomic Force Microscopy (AFM).     

Comparison of morphological and genetic analyses reveals cryptic divergence and morphological plasticity in Stylophora (Cnidaria, Scleractinia)

A combined morphological and genetic study of the coral genus Stylophora investigated species boundaries in the Gulf of Aden, Yemen. Two mitochondrial regions, including the hypervariable IGS9 spacer and the control region, and a fragment of rDNA were used for phylogenetic analysis. Results were compared by multivariate analysis on the basis of branch morphology and corallite morphometry. Two species were clearly discriminated by both approaches. The first species was characterised by small corallites and a low morphological variability and was ascribed to a new geographical record of Stylophora madagascarensis on the basis of its phylogenetic distinction and its morphological similarity to the type material. The second species was characterised by larger corallite size and greater morphological variability and was ascribed to Stylophora pistillata. The analysis was extended to the intrageneric level for other S. pistillata populations from the Red Sea and the Pacific Ocean. Strong internal divergence was evident in the genus Stylophora. S. pistillata populations were split into two highly divergent Red Sea/Gulf of Aden and western Pacific lineages with significant morphological overlap, which suggests they represent two distinct cryptic species. The combined use of morphological and molecular approaches, so far proved to be a powerful tool for the re-delineation of species boundaries in corals, provided novel evidence of cryptic divergence in this group of marine metazoans.     

On-column epimerization of dihydroartemisinin: an effective analytical approach to overcome the shortcomings of the International Pharmacopoeia monograph

We developed a cryo-HPLC/UV method for the simultaneous determination of artemisinin (1), alpha-dihydroartemisinin (2alpha), beta-dihydroartemisinin (2beta), and a ubiquitous thermal decomposition product of 2 (designated as diketoaldehyde, 3), starting from the International Pharmacopoeia monograph on dihydroartemisinin. The method takes for the first time the on-column epimerization process of 2 into consideration. Chromatographic separation was obtained under reversed-phase conditions on a Symmetry C18 column (3.5 microm particle size) with a mobile phase consisting of acetonitrile-water 60:40 (v/v), delivered at 0.60-1.00 ml/min flow-rates, with ultraviolet detection at low wavelength (lambda = 210 nm). Low temperatures (T = 0-10 degrees C) were selected on the grounds of a diastereoselective dynamic HPLC (DHPLC) study performed at different temperatures, aimed at identifying the best experimental conditions capable of minimizing the on-column interconversion process.     

Functional annotation by identification of local surface similarities: a novel tool for structural genomics

Background  

Protein function is often dependent on subsets of solvent-exposed residues that may exist in a similar three-dimensional configuration in non homologous proteins thus having different order and/or spacing in the sequence. Hence, functional annotation by means of sequence or fold similarity is not adequate for such cases.     

Cell cycle and behaviour in Euplotes crassus: an attempt at describing the biological relationship between its cellular and organismic natures

The two-faced nature of protozoa allowed us to study the relationship between cell cycle and behaviour in Euplotes crassus; the former represents one of the most typical cellular traits, the latter is one of the most significant characteristics of an organism. Dividing cells of E. crassus were isolated on a slide and recorded for 11 h: the classic ethographic parameters were calculated every 60 min. The percentage of mobile cells went from 0-100% in the first 2.5 h. This value was maintained for 6.5 h, but from 9 h the value began to drop, reaching 0% at 11 h. The relative frequency of leftward arcs was very high in the first hour, the radius and length of the arcs increased from 1-7 h; velocity showed a similar trend, peaking at 7 h. All our results showed that the behaviour of this ciliate is heavily affected by its cell-division cycle.