Sterilization of Plants for Phytoremediation Studies by Bleach Treatment

Bleach treatment of plants was studied as a simple alternative to axenic tissue cultures for demonstrating phytodegradation of aqueous and gas-phase environmental contaminants. Parrotfeather (Myriophyllum aquaticum), spinach (Spinacia oleracea), and wheat (Triticum aestivum) were exposed to 0.525% NaC10 solutions for 15 s, then rinsed in deionized water. Plate counts indicated that 97 to 100% of viable bacteria were removed from parrotfeather and spinach. Transformation rates for 2,4,6-trinitrotoluene (TNT) by bleached and untreated parrotfeather were virtually identical. Similarly, treated and untreated spinach, wheat heads, and wheat leaves removed methyl bromide (MeBr) from air at the same rates. However, wheat root with attendant adhering soil was rendered inactive by bleach treatment. Parrotfeather roots examined by dissecting microscope and by electron microscope showed no significant damage caused by bleach treatment.     

Enhanced in vitro growth of murine fibroblast cells and preimplantation embryos cultured in medium supplemented with an amphipathic peptide.

Preliminary studies on the proliferative effects of lytic peptides were carried out using NIH 3T3 murine fibroblast cells and human lymphocytes. Cells were cultured in various concentrations of three different amphipathic peptides (SB-37, Shiva-1, and Vishnu), and enhanced proliferation was determined by uptake of 3H-thymidine with treated cells compared with control cultures. Enhanced proliferation of 3T3 cells was observed in cultures containing 50 microM or less SB-37. The primary study consisted of 263 four-cell- to eight-cell-stage mouse embryos from naturally bred mice and incubated in Whitten's medium containing 0.2, 1, or 10 microM of the amino terminus of an amphipathic cecropin B analog (Vishnu) or in Whitten's medium alone. Embryos were cultured to the hatched blastocyst stage, and effect of treatment was determined by the rate of growth to that stage of development. Statistical analysis revealed that culture in all three levels of Vishnu significantly accelerated in vitro growth of these stages of preimplantation embryos compared with controls. These results indicate that Vishnu promotes increased cleavage rates of embryos in vitro. A growth factor receptor clustering mechanism of action is proposed. This peptide may have some potential as an embryo culture medium additive to enhance in vitro growth rate.     

Size and location of poly (A) in encephalomyocarditis virus RNA.

Encephalomyocarditis (EMC) virus RNA contains a covalently bound sequence of polyriboadenylic acid (poly(A). This was determined by two-dimensional gel electrophoresis of complete T1 and pancreatic RNase digests of formamidesucrose gradient-purified RNA and subsequent analysis of the product by alkaline hydrolysis. The size of the EMC virus genomic poly(A) sequence was estimated by formamide-polyacrylamide gel electrophoresis of the RNase-resistant product, or by [3H-]poly(U) hybridization to freshly purified virion RNA, to be, on average, 40 nucleotides in length. The evidence obtained from [3H-]isoniazid labelling and other experiments would indicate that the poly(A) sequence is located at the 3'-terminus of EMC virus RNA.     

Control of chicken coccidiosis

Coccidiosis could potentially cause enormous economic loss to the poultry industry, especially in the production of broiler chickens (see Box 1). Losses are currently minimized by chemotherapeutic treatment but the effectiveness of many drugs seems to be declining. In this article, Peter Long and Tom Jeffers discuss the future for coccidial chemotherapy, and the potential for immunological control methods.     

Lanthanide probes in biological systems: characterization of luminescence excitation spectra of terbium complexes with proteins

Upon irradiation in the ultraviolet region aromatic chromophores may transfer energy to a nearby Tb³⁺, which in turn emits a green phosphorescence. This paper reports the characterization of the ultraviolet excitation spectra of aromatic chromophores capable of transferring energy to Tb³⁺ by monitoring of the green Tb³⁺ emission in the 540-550 nm region. Results are included for complexes containing phenyl, hydroxyphenyl, indole. and catechol chromophores. Characteristic excitation spectra are presented for the aromatic chromophores occurring as side chains in proteins. Though it is preferable to compare entire excitation spectra, the ratio of intensities at 292 to 276 nm, R, is suggested as a useful diagnostic criterion. Numerical R values are indicative of the following aromatic side chains as the energy donor to Tb³⁺: R <0.2, unionized tyrosine; R = 0.5 to 1.0, tryptophan; and R > 1.8. ionized tyrosine. Tlie phenylalanyl chromophore displays a definitive excitation spectrum at shorter wavelengths. For ovotransferrin R = 0.9 and comparison of the full excitation spectra suggests that it contains comparable contributions from both ionized tyrosine and tryptophan side chains. Some difficulties in obtaining reliable excitation spectra are described. An analysis of inner-filtering of incident light reveals that for an absorbance less than 0.8 the excitation spectrum is broadened and flattened compared to the absorption spectrum. At maximum absorbances greater than 0.8 false maxima may appear to both sides of a real maximum. Two spurious maxima in an excitation spectrum were generated in a Tb³⁺ complex and compared to the correct excitation spectrum of the same complex obtained at lower absorbance.     

Genetic variation in DNMT3B and increased global DNA methylation is associated with suicide attempts in psychiatric patients

Recently, a significant epigenetic component in the pathology of suicide has been realized. Here we investigate candidate functional SNPs in epigenetic‐regulatory genes, DNMT1 and DNMT3B, for association with suicide attempt (SA) among patients with co‐existing psychiatric illness. In addition, global DNA methylation levels [5‐methyl cytosine (5‐mC%)] between SA and psychiatric controls were quantified using the Methylflash Methylated DNA Quantification Kit. DNA was obtained from blood of 79 suicide attempters and 80 non‐attempters, assessed for DSM‐IV Axis I disorders. Functional SNPs were selected for each gene (DNMT1; n = 7, DNMT3B; n = 10), and genotyped. A SNP (rs2424932) residing in the 3′ UTR of the DNMT3B gene was associated with SA compared with a non‐attempter control group (P = 0.001; Chi‐squared test, Bonferroni adjusted P value = 0.02). Moreover, haplotype analysis identified a DNMT3B haplotype which differed between cases and controls, however this association did not hold after Bonferroni correction (P = 0.01, Bonferroni adjusted P value = 0.56). Global methylation analysis showed that psychiatric patients with a history of SA had significantly higher levels of global DNA methylation compared with controls (P = 0.018, Student's t‐test). In conclusion, this is the first report investigating polymorphisms in DNMT genes and global DNA methylation quantification in SA risk. Preliminary findings suggest that allelic variability in DNMT3B may be relevant to the underlying diathesis for suicidal acts and our findings support the hypothesis that aberrant DNA methylation profiles may contribute to the biology of suicidal acts. Thus, analysis of global DNA hypermethylation in blood may represent a biomarker for increased SA risk in psychiatric patients.     

Sequestration,Phytoreduction, and Phytooxidation of Halogenated Organic Chemicals by Aquatic and Terrestrial Plants

Laboratory data from plant-mediated transformation of chlorinated and brominated alkanes, alkenes, and chlorinated pesticides, including phytotransformation data from field plants currently used in phytoremediation of trichloroethylene (TCE), were reviewed for the purpose of identifying important phytoprocesses and their respective roles in phytoremediation of halogenated organic compounds (HOCs). The results of the laboratory experiments indicated that the initial very rapid removal of hydrophobic HOCs from water or the gas phase by aquatic and terrestrial plants is primarily due to sequestration. The amount of HOC sequestered is controlled by the plant species and the physicochemical properties (e.g., K_ow, aqueous solubility, volatility) of the contaminant. Phytodegradation studies conducted in both the gas and aqueous phases indicated that hexachloroethane (HCA) is dechlorinated to the same metabolites by sterilized and axenically cultivated aquatic plants and an isolated plant dehalogenase factor. Similar results were obtained in experiments conducted with o,p'-DDT and p,p'-DDT in aqueous solution. The sterilized and axenically cultivated aquatic plants also oxidized HCA to similar chloroacetic acids. The metabolism of HOCs to the corresponding oxidative and reductive transformation products identified in the plant rhizosphere, stems, and leaves suggested that more than one pathway, requiring different enzymes, may be involved in phytotransformation reactions. Four phytoprocesses (mechanisms) were found to be important in the removal of the probe HOCs from water by aquatic plants, namely, (1) rapid sequestration by partitioning to the lipophilic plant cuticles; (2) phytoreduction to less halogenated metabolites; (3) phytooxidation to haloethanols, haloacetic acids, and unidentified metabolites; and (4) assimilation into the plant tissues as nonphytotoxic products, presumably produced by covalent binding with the plant tissues. Laboratory and field data indicate that the distribution of metabolites of perchloroethylene (PCE) and TCE in cottonwood and willow trees is determined by the growth stage or age of these vascular plants, the plant species, and the duration of exposure to the compound. For terrestrial plants, the predominant phytoprocesses by which HOCs are attenuated in the environment include sequestration, rhizodegradation, uptake, phytodegradation, and phytovolatilization. Using PCE as a model chlorinated organic solvent, possible phytotransformation pathways are proposed to account for the different metabolites identified in the rhizosphere and tissues of laboratory and field plants. The proposed pathways also combine phytoreduction reactions that occur in plant tissues and are likely catalyzed by plant dehalogenase(s) for example, enzyme(s) such as glutathione-S-transferase and Fe-S clusters in chloroplast ferredoxin, with phytooxidation and covalent binding (phytoassimilation) reactions mediated by oxidative-enzymes (possibly cytochrome P-450 with monooxygenase activity, glutathione or laccase). Depending on the characteristics of the field site, the phytoprocesses identified in this study are vital in the design and implementation of phytoremediation of halogenated organic contaminants.     

The effects of habitat complexity on aggression and fecundity in zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>)

Female zebrafish housed in aquaria with spatial complexity (plastic plants) over a 13–16-week period showed reduced levels of aggressive behavior compared to females in bare tanks. In tanks with plants, there was no relationship between levels of aggression and fecundity but, in bare tanks, females experiencing the highest levels of aggression showed reduced fecundity. Our results suggest that it may be beneficial, when maintaining zebrafish at moderate to high densities or working with especially aggressive strains, to house them in spatially complex conditions.