Chemical safety in animal care,use, and research

Chemical safety is an essential element of an effective occupational health and safety program. Controlling exposures to chemical agents requires a careful process of hazard recognition, risk assessment, development of control measures, communication of the risks and control measures, and training to ensure that the indicated controls will be utilized. Managing chemical safety in animal care and use presents a unique challenge, in part because research is frequently conducted in two very different environments--the research laboratory and the animal care facility. The chemical agents specific to each of these environments are typically well understood by the employees working there; however, the extent of understanding may not be adequate when these individuals, or chemicals, cross over into the other environment. In addition, many chemicals utilized in animal research are not typically used in the research laboratory, and therefore the level of employee knowledge and proficiency may be less compared with more routinely used materials. Finally, the research protocol may involve the exposure of laboratory animals to either toxic chemicals or chemicals with unknown hazards. Such animal protocols require careful review to minimize the potential for unanticipated exposures of the research staff or animal care personnel. Numerous guidelines and regulations are cited, which define the standard of practice for the safe use of chemicals. Key chemical safety issues relevant to personnel involved in the care and use of research animals are discussed.     

贵州紫云产黄花香茶菜的化学成分研究

采用甲醇回流提取和硅胶柱层析方法,从紫云产黄花香茶菜中分离得到6个化合物,结合1H-NMR、13C-NMR数据及文献资料鉴定为黄花香茶菜乙素(Ⅰ)、黄花香茶菜丁素(Ⅱ)、大萼变型香茶菜甲素(Ⅲ)、3β-Hydroxy-18α,19α-urs-20-en-28-oic acid(Ⅳ)、齐墩果酸(Ⅴ)和熊果酸(Ⅵ)。其中化合物Ⅳ为首次从该属植物中分离得到。     

Chemical communication,sexual selection,and introgression in wall lizards

Divergence in communication systems should influence the likelihood that individuals from different lineages interbreed, and consequently shape the direction and rate of hybridization. Here, we studied the role of chemical communication in hybridization, and its contribution to asymmetric and sexually selected introgression between two lineages of the common wall lizard (Podarcis muralis). Males of the two lineages differed in the chemical composition of their femoral secretions. Chemical profiles provided information regarding male secondary sexual characters, but the associations were variable and inconsistent between lineages. In experimental contact zones, chemical composition was weakly associated with male reproductive success, and did not predict the likelihood of hybridization. Consistent with these results, introgression of chemical profiles in a natural hybrid zone resembled that of neutral nuclear genetic markers overall, but one compound in particular (tocopherol methyl ether) matched closely the introgression of visual sexual characters. These results imply that associations among male chemical profiles, sexual characters, and reproductive success largely reflect transient and environmentally driven effects, and that genetic divergence in chemical composition is largely neutral. We therefore suggest that femoral secretions in wall lizards primarily provide information about residency and individual identity rather than function as sexual signals.     

农作物体内铅,镉,铜的化学形态研究

本文报道了农作物体内重金属存在的化学形态。用逐步提取法分析了生长在污染土壤上的水稻、小麦的根与叶。结果表明,在两种作物中,根部的铅以活性较低的醋酸可提取态与盐酸可提取态占优势,而叶中的铅以盐酸可提取态占优势。不论根部或叶部,在各种形态镉中,以氯化钠可提取镉所占比例较高,作用较重要。作物体内的铜活性较强,根部以乙醇可提取态占优势,叶中以水提取态占优势。各种结合形态的重金属迁移能力、毒性效应有显著差异。作物体内重金属化学形态特征与其表观毒性效应有密切联系。     

Chemical Induction of Autogamy in Paramecium multimicronucleatum,Syngen 21

The combination of KCl + acriflavine + Ca²⁺-poor condition, known as conjugation-inducing-chemicals, was found to be autogamy-inducing-chemicals as well. Suspension of a single cell of Paramecium multimicronucleatum, syngen 2 in this medium for three hours or more resulted in autogamy that was evidenced by cytological similarity to conjugation.     

Chemical Structures of Reniformin A,B, and C

Three new cytotoxic diterpenoids reniformin A, B and C, have been isolated from the leaves of Rabdosia latifolia var. reniformis Z. W. Xue et X. W. Wang. Their structures were established as (1), (2), and (3) by spectroscopic and chemical data respectively.     

Chemical,chemophenetic, and anticancer studies of Cattleya tigrina

The Orchidaceae family comprises about 27,000 species and is considered one of the largest families of flowering plants. Herein, the first chemical study of the native Brazilian orchid Cattleya tigrina A. Rich. reports the isolation of 15 compounds of different classes of natural products, among them triterpenoids, stilbenoids, phenolic acids, and 1,4-dihydro-phenanthrenequinone derivatives. The compounds were identified based on spectroscopic analyses. Cytotoxicity assays with plant crude extract, fractions and isolated compounds were performed against the HeLa cells and against the non-cancerous VERO cell lines. The chemophenetic significance of the presence of different compounds in Epidendroideae subfamily and Laeliinae subtribe was also discussed.     

Chemical,Target, and Bioactive Properties of Allosteric Modulation

Allosteric modulators are ligands for proteins that exert their effects via a different binding site than the natural (orthosteric) ligand site and hence form a conceptually distinct class of ligands for a target of interest. Here, the physicochemical and structural features of a large set of allosteric and non-allosteric ligands from the ChEMBL database of bioactive molecules are analyzed. In general allosteric modulators are relatively smaller, more lipophilic and more rigid compounds, though large differences exist between different targets and target classes. Furthermore, there are differences in the distribution of targets that bind these allosteric modulators. Allosteric modulators are over-represented in membrane receptors, ligand-gated ion channels and nuclear receptor targets, but are underrepresented in enzymes (primarily proteases and kinases). Moreover, allosteric modulators tend to bind to their targets with a slightly lower potency (5.96 log units versus 6.66 log units, p<0.01). However, this lower absolute affinity is compensated by their lower molecular weight and more lipophilic nature, leading to similar binding efficiency and surface efficiency indices. Subsequently a series of classifier models are trained, initially target class independent models followed by finer-grained target (architecture/functional class) based models using the target hierarchy of the ChEMBL database. Applications of these insights include the selection of likely allosteric modulators from existing compound collections, the design of novel chemical libraries biased towards allosteric regulators and the selection of targets potentially likely to yield allosteric modulators on screening. All data sets used in the paper are available for download.     

The Microbiota,Chemical Symbiosis,and Human Disease

Our understanding of mammalian–microbial mutualism has expanded by combing microbial sequencing with evolving molecular and cellular methods, as well as unique model systems. Here, the recent literature linking the microbiota to diseases of three of the key mammalian mucosal epithelial compartments—nasal, lung, and gastrointestinal tract—is reviewed with a focus on new knowledge about the taxa, species, proteins, and chemistry that promote health and impact progression toward disease. The information presented is further organized by specific diseases now associated with the microbiota: Staphylococcus aureus infection and rhinosinusitis in the nasal-sinus mucosa, as well as cystic fibrosis, chronic obstructive pulmonary disorder, and asthma in the pulmonary tissues. For the vast and microbially dynamic gastrointestinal compartment, several disorders are considered, including obesity, atherosclerosis, Crohn's disease, ulcerative colitis, drug toxicity, and even autism. Our appreciation of the chemical symbiosis ongoing between human systems and the microbiota continues to grow and suggests new opportunities for modulating this symbiosis using designed interventions.     

Chemical acetylation, trypsinolysis and stability of nucleosomes

Gel electrophoretic analysis of the histone chemical acetylation in the nucleosome core particles with acetic andydride revealed availability of about 14 lysine residues of histone H2A, 15-21 of H2B, 8-11--H3 and 6-9--H4. Moderately lysine-rich histones H2A and H2B were found to be more susceptible to acetylation than arginine-rich H3 and H4. Chemical acetylation enhanced the rate of trypsin digestion in acetylated nucleosomes as evidenced by gel electrophoresis of histone fragments. A more pronounced trypsin digestion was evident at acetylation of only 3-5 histone amino groups per nucleosome. However, even heavily acetylated nucleosomes yielded in familiar trypsin limit digest pattern of histone fragments thus indicating persistence of histone octamer. Nucleosomes which were trace acetylated (up to 3-5 histone amino groups neutralized per nucleosome) and treated with trypsin to remove highly charged terminal histone regions revealed remarkable unfolding and partial dissociation when analyzed by gel electrophoresis. The same trace acetylated nucleosomes did not show such destabilization prior to trypsin digestion.     

Chemical Constituents of Lac Host,Acacia suma

Six crystallin compounds were isolated from the stem bark of Acacia surna BuchHam. ex. Wall. Based on spectral and chemical evidences, four of them were demonstrated as triacontanol, β-sitosterol, daucosterin and lupeol heptylate. All were firstly reported from the plant. Among them lupeol heptylate was a new compound.     

Chemical evolution,recent syntheses of bioorganic molecules

This review covers important developments in abiological synthesis of biomonomers and biopolymers since about 1967. The significance of these experiments to the field of chemical evolution and the origin of life is also discussed. Lunar Science Institute Contribution. Continuation of: Oró, J.: ‘Extraterrestrial Organic Analysis’,Space Life Sci. 3 (1972), 507.     

Chemical characteristics of lakes in the High Tatra Mountains,Slovakia

The chemistry of 53 lakes at various stages of acidification and inhabited (at the presence and/or in the past) by pelagic Crustacea was studied in September 1984. Ten of these lakes were investigated in detail biannually (July and October 1987–1990). The July results reflect the influence of snowmelt and were compared with the October ones. The most important anion was sulphate with the average values of 98 and 104 μeq 1^-1 in 1984 and 1987–1990, respectively. High concentrations of nitrate (21–56 μeq 1^-1) were observed in lakes above the treeline. Mean relative composition of cations does not differ between July and October; small changes are in the mean relative composition of anions. Acidification of lakes, expressed as a decrease in alkalinity, is 100 μeq l^-1, and is equal to the increase in the sum of sulphate and nitrate. The values of total phosphorus and COD are the lowest in the range of pH 5–6.5. Alkalinity, sulphate, nitrate and pH do not show any trend with time over the last ten years.     

Chemical and genetic diversity of Ligularia vellerea in Yunnan, China

Intra-specific diversity in Liularia vellerea growing in the northwestern to central Yunnan province of China was studied by chemical and genetic approaches. Samples collected in the Jianchuan, Lijiang, and Zhongdian areas contained 6,15-dioxygenated furanoeremophilanes as their major components (type A); whereas samples from the Luguhu area accumulated 1,6-dioxygenated furanoeremophilanes (type B); a sample from near Kunming, however, contained 6,15-dioxygenated eremophilanolides (type C). 11 beta H- and 11 alpha H-6 beta-angeloyloxy-15-carboxyeremophil-7-en-12,8-olides (eremofarfugins D and E) were also isolated and their structures were determined. A correlation between the composition and the DNA sequence was observed in the ITSs.