Ovicidal and adulticidal activities of Cinnamomum zeylanicum bark essential oil compounds and related compounds against Pediculus humanus capitis (Anoplura: Pediculicidae)

The toxicity of cinnamon, Cinnamomum zeylanicum, bark essential oil compounds against eggs and adult females of human head louse, Pediculus humanus capitis, was examined using direct contact and vapour phase toxicity bioassays and compared with the lethal activity of their related compounds, benzyl alcohol, cinnamic acid, cinnamyl acetate, 4-hydroxybenzaldehyde and salicylaldehyde, as well as two widely used pediculicides, d-phenothrin and pyrethrum. In a filter-paper contact toxicity bioassay with female lice at 0.25 mg/cm², benzaldehyde was 29- and 27-fold more toxic than pyrethrum and d-phenothrin, respectively, as judged by median lethal time (LT₅₀) values. Salicylaldehyde was nine and eight times more active than pyrethrum and d-phenothrin, respectively. Pediculicidal activity of linalool was comparable with that of d-phenothrin and pyrethrum. Cinnamomum bark essential oil was slightly less effective than either d-phenothrin or pyrethrum. Benzyl alcohol and (E)-cinnamaldehyde exhibited moderate pediculicidal activity. After 24 h of exposure, no hatching was observed with 0.063 mg/cm² salicylaldehyde, 0.125 mg/cm² benzaldehyde, 0.5 mg/cm² Cinnamomum bark essential oil, 1.0 mg/cm² (E)-cinnamaldehyde, and 1.0 mg/cm² benzyl cinnamate. Little or no ovicidal activity was observed with d-phenothrin or pyrethrum. In vapour phase toxicity tests with female lice, benzaldehyde and salicylaldehyde were much more effective in closed containers than in open ones, indicating that the mode of delivery of these compounds was largely due to action in the vapour phase. Neither d-phenothrin nor pyrethrum exhibited fumigant toxicity. Cinnamomum bark essential oil and test compounds described merit further study as potential pediculicides or ovicides for the control of P. h. capitis.     

Natural killer cells and innate immunity to protozoan pathogens

Natural killer (NK) cells are lymphoid cells that mediate significant cytotoxic activity and produce high levels of pro-inflammatory cytokines in response to infection. During viral infection, NK cell cytotoxicity and cytokine production is induced principally by monocyte-macrophage- and dendritic cell-derived cytokines but virally encoded ligands for NK cells are also beginning to be described. NK derived interferon-gamma (IFN-gamma) production is also essential for control of several protozoal infections including toxoplasmosis, trypanosomiasis, leishmaniasis and malaria. The activation of NK cells by protozoan pathogens is also believed to be cytokine-mediated although some recent studies suggest that direct recognition of parasites by NK cells also occurs. Both indirect signalling via accessory cell-derived cytokines and direct signalling, presumably through NK receptors, are needed in order for human malaria parasites (Plasmodium falciparum) to optimally stimulate NK activity.     

Non-invasive assessment of parasitic nematode species diversity in wild Soay sheep using molecular markers

Considerable effort has been put into detecting and identifying parasitic nematodes in live ruminants, but to date most studies are limited to a small group of nematodes and/or to experimentally infected sheep. In this study, a PCR-based assay using species-specific primer pairs, located in the second internal transcribed spacer ribosomal DNA, was developed to identify nine different species from six different families of parasitic nematodes in a wild, unmanaged and naturally infected population of sheep. Each primer pair was tested for its specificity and sensitivity and it exclusively amplified the species it was designed for and exhibited a high degree of sensitivity. The method was applied to eggs and cultured larvae to identify the parasitic nematodes present in a pooled faecal sample from several host individuals with unknown parasite burden. To test detection reliability, a faecal sample from an individual with known parasite burden (through post-mortem analysis) was also examined. All species present could be correctly identified by PCR, but detecting very low levels and/or early stages of infection proved to be difficult. The method was also tested for its applicability to high through-put screening of faecal samples.     

An early- and late-stage convolution model for disease natural history

The standard convolution model of disease natural history posits an asymptomatic (preclinical) and a symptomatic (clinical) state. An augmented model includes, in both the preclinical and clinical states, an early and late stage of disease. In the case of cancer, the early stage would generally correspond to the organ-confined stages before there is evidence of cancer spread. We compute the number of screen-detected (preclinical) and clinical cases in the early and late stages expected under a given screening program and show how the model can be fit to data from a screening trial using maximum likelihood. We also develop expressions for sojourn time, lead time, and overdiagnosis in the context of the model, where each of the above concepts incorporates disease stage. As an example, we fit the model to data from the Mayo Lung Cancer Screening trial.     

Alterations in blood pressure due to chronic exposure to natural sour gas leakage containing sulfur compounds

In order to show the alteration of blood pressure in subjects chronically exposed to natural gas containing sulfur compounds, the present study was done. The blood pressure of 94 (43 males, 51 females) of healthy individuals living in the polluted area of Masjid-i-Sulaiman (Khozestan province, southwest of Iran) was measured. The non-parametric Sign test was applied in order to detect differences between the study subjects and the normal mean values according to the sex and age of subjects. Statistical analysis showed that the systolic blood pressure significantly decreased (Z=-2.74; P=0.0031) while the diastolic blood pressure (Z=+2.11; P=0.0174) and heart rate (Z=+3.62; P<0.001) significantly increased in individuals living in the contaminated areas compared with those of normal mean values. The systolic and diastolic blood pressure decreased and increased, respectively, in individuals chronically exposed to natural sour gas containing sulfur compounds.     

广东象头山国家级自然保护区珍稀野生花卉资源

对广东象头山国家级自然保护区珍稀野生花卉资源调查结果表明,本区内有52科68属88种,其中蕨类植物11科11属13种;被子植物41科57属75种,并对其基本组成、多样性等进行分析。根据本区珍稀野生花卉的现状与特点,划分出生活类型,提出园林配置方式,对资源保护和开发利用提出建议。     

Isolation and Phylogenetic Analysis of Halophilic Archaeon AJ6

Halophilic archaeon A J6 was isolated and purified from the Altun Mountain National Nature Reserve of the Xinjiang Uygur Autonomous Region.Strain AJ6 is a Gram-negative rod whose size is 0.2-0.6 by 1.6-4.2 μm,wherein a few cells are globular.The optimum salt concentration for its growth is 20% NaC1 and 0.6% Mg2+,and the optimum pH is 6.0-7.0.Morphological,physiological,and biochemical characteristics of strain AJ6 were observed.The 16S rRNA encoding gene (16S rDNA)sequence of strain A J6 was amplified by PCR,and its nucteotide sequence was determined subsequently."Clustalw"and"PHYLIP"software bags were used to analyze the 16S rDNA sequence;the homology was compared,and then the phylogenetic tree was established.The results indicate that strain AJ6 is a novel species of the genus Natrinema.The GenBank accession number of the 16S rDNA sequences of strain AJ6 is AY277584.     

松山自然保护区森林群落的数量分类和排序

根据68个森林群落样方数据,采用双向指示种分析(TW INSPAN)方法,对松山自然保护区的森林群落进行分类和采用除趋势对应分析(DCA)、典范对应分析(CCA)方法进行排序。结果表明:(1)TW INSPAN将该区的森林群落分为13类型;(2)样方的DCA排序及样方和优势种的CCA排序较好地揭示了该区森林群落的分布格局与环境梯度的关系;CCA第一轴明显地反映出森林群落的海拔梯度、枯枝落叶层厚度和土壤深度变化,沿CCA第一轴从左到右,海拔逐渐升高,枯枝落叶层越厚和土壤越深;第二轴与海拔高度和坡度成正相关,而与土壤紧实度成负相关。其中海拔梯度是环境因子中对森林群落起决定性作用的因子。(3)与DCA相比,CCA的排序轴更有利于生态意义的解释,后者能同时反映样方间在种类组成上及环境因子组成上的相似性,表现在排序图中样方较集中,群落间的界线变得较模糊,因此如果排序同分类结合使用,DCA的效果要好于CCA。(4)TW INSPAN分类与DCA和CCA排序的结果,同时表明了该地区森林群落的垂直分布格局。     

湖南小溪国家级自然保护区野生观赏植物资源初步研究

实地调查了小溪国家级自然保护区内的野生观赏植物资源的种类、生活习性、利用价值及现状。结果表明,小溪自然保护区的野生观赏植物资源十分丰富,有81科171属519种及变种。蔷薇科、菊科等10科植物含有10种以上的植物,为该区的优势类群。对其中具有一定代表性、开发利用潜力较大的40种植物的生活型及供观赏的主要特征、花(果)期、生境、其他用途等进行了扼要描述。就如何充分合理地开发和保护野生观赏资源提出了建议。