The total burden of rare,non-synonymous exome genetic variants is not associated with childhood or late-life cognitive ability

Human cognitive ability shows consistent, positive associations with fitness components across the life-course. Underlying genetic variation should therefore be depleted by selection, which is not observed. Genetic variation in general cognitive ability (intelligence) could be maintained by a mutation–selection balance, with rare variants contributing to its genetic architecture. This study examines the association between the total number of rare stop-gain/loss, splice and missense exonic variants and cognitive ability in childhood and old age in the same individuals. Exome array data were obtained in the Lothian Birth Cohorts of 1921 and 1936 (combined N = 1596). General cognitive ability was assessed at age 11 years and in late life (79 and 70 years, respectively) and was modelled against the total number of stop-gain/loss, splice, and missense exonic variants, with minor allele frequency less than or equal to 0.01, using linear regression adjusted for age and sex. In both cohorts and in both the childhood and late-life models, there were no significant associations between rare variant burden in the exome and cognitive ability that survived correction for multiple testing. Contrary to our a priori hypothesis, we observed no evidence for an association between the total number of rare exonic variants and either childhood cognitive ability or late-life cognitive ability.     

内蒙东部地区绵羊中华双腔吸虫生物学和流行病学的研究

中华双腔吸虫(Dicrocoelium chinensis Tang et Tang,1978)的生活史虽经研究,但本吸虫在第二中间宿主及终末宿主体内发育的情况尚未经阐明(唐崇惕等,1980).内蒙科右前旗附近数个旗县是本吸虫的流行区,1980—1981年我们在那里进行本项工作,从     

四种主要大豆食叶害虫种群空间分布型及其应用研究

通过分层随机与连片调查获得114个样本．利用微机分别对豆天蛾卵和豆天蛾．银纹夜蛾．棉铃虫．豆灰蝶及混合种群的幼虫．进行了4种频次分布型检验和6项聚集度指标的测定．结果表明．上述害虫在豆田内均属零集分布．中分析了聚集原因．提出了“Z”字型10样点,每样点以1／3m双行为单位的抽样方法．确立了在两种允许误差下的抽样数量．进行了序贯抽样分析。     

Experimental Oesophagostomum dentatum infection in the pig: Worm populations resulting from single infections with three doses of larvae

This report describes the effect of different dose levels of infection upon worm burdens and development and fecundity of the parasites. Three groups each of 40, 9-week-old, helminth naïve pigs were inoculated once with either 2000 (group A), 20,000 (group B), or 200,000 (group C) infective third stage larvae of Oesophagostomum dentatum. Subgroups of 5 pigs from each major group were killed 3, 6, 11, 14, 18, 25, 34 and 47 days post inoculation (p.i.) and the large intestinal worm burdens were determined. Faecal egg counts were determined at frequent intervals after day 13 p.i. There were no overt clinical signs of gastrointestinal helminthosis during the experiment. Faecal egg counts became positive in groups A and B at around day 19 p.i., whereas most pigs in the high dose group C did not have positive egg counts until day 27–33 p.i. and some pigs remained with zero egg counts until the end of the study. Throughout the experiment the worm populations in group C consisted mainly of immature larval stages, while those in groups A and B were predominantly adult stages after days 14–18. Adult worms from the low dose group A were significantly longer than those from group C. At high population densities, stunted development of worms and reduced fecundity among female worms were found. Furthermore, there was a tendency for the distribution of the worms within the intestine to be altered with increasing population size.     

A study of the microtriches of adult Echinococcus granulosus by scanning electron microscopy

Thompson R. C. A., Houghton A. and Zaman V. 1982. A study of the microtriches of adult Echinococcus granulosus by scanning electron microscopy. International Journal for Parasitology12: 579–583. The microtriches in different regions of the scolex and strobila of sexually mature Echinococcus granulosus were examined using the scanning electron microscope. E. granulosus was found to possess two morphologically distinct types of microthrix. A cylindrical, slender filamentous type of microthrix which appeared to be flexible was restricted to the scolex. On the strobila, the only type of microthrix observed was a flattened blade-like form which appeared to be rigid for most of its length. The occurrence of two distinct types of microthrix in separate regions of the body of E. granulosus suggests that they may be involved in different functional activities.     

Effects of host endocrine gland removal on the permissive status of laboratory rodents to infection by Schistosoma mansoni

Knopf P. M. and Soliman M. 1980. Effects of host endocrine gland removal on the permissive status of laboratory rodents to infection by Schistosoma mansoni. International Journal for Parasitology, 10: 197–204. The capacity of Schistosoma mansoni to complete its life cycle was compared in CD-1 mice (permissive hosts) and Sprague-Dawley rats (nonpermissive hosts) from which the pituitary gland had been removed prior to infection with cercariae. Except for a modest decrease in egg burden, none of the parameters of worm life cycle assessed were affected in hypophysectomized mice. In contrast, all these parameters were affected in hypophysectomized rats, e.g. onset of adult worm elimination was delayed, worm development improved, oviposition increased and miracidia developed. Effects of removal from rats of the thyroid/parathyroid glands on the parasite life cycle were similar to hypophysectomy; adrenalectomy or gonadectomy were without affect. Differences between thyroidectomized and thymectomized rats are discussed. It is concluded that host hormones contribute to the nonpermissive status of rats to Schistosoma mansoni infections.     

Manifestations of resistance to Haemonchus contortus in sheep: Worm populations and abomasal changes in sheep superinfected with 1,000,000 larvae of H. contortus

The super-infecting dose produced a marked rise in gastric pH in all sheep from the 3rd day after administration of larvae. Expulsion of the existing population of adult worms may have begun on the 4th day but was still only completed in 3/6 sheep on the 5th day. The larvae caused extensive damage in the individual glands which they parasitised. Very few of the 10⁶ larvae survived for 27 days and only in 1/8 sheep had they developed beyond early 4th stage at 27 days. Extensive histological changes were seen in the fundic mucosa beginning as early as 2 days after the superinfection. While the pH change preceded expulsion of the adults and was consistent in its timing, the timing of the expulsion was irregular. This throws doubt on the hypothesis that the change in physico-chemical conditions produced by the superinfecting larvae is the only cause of the expulsion of the adult worms.     

Enzymes of the tricarboxylic acid cycle in Obeliscoides cuniculi (Nematoda; Trichostrongylidae) during parasitic development

The specific activities of the enzymes of the tricarboxylic acid cycle; citrate synthase, aconitase, isocitrate dehydrogenase, succinate dehydrogenase, fumarase, and malate dehydrogenase, were determined in early fifth-stage, young and mature adult Obeliscoides cuniculi, the rabbit stomach worm. ∝-Ketoglutarate dehydrogenase activity could not be determined in any fraction. Fumarate reductase activity was found only in the mitochondrial fraction while all other enzymes, including an NADP-dependent malic enzyme were localized in the cytoplasm. Glutamate dehydrogenase, acid and alkaline phosphatase activities were also recorded. High levels of those enzymes acting in the “reversed” direction, i.e. MDH and fumarase relative to the enzymes of the “forward” direction, i.e. citrate synthase, aconitase and isocitrate dehydrogenase suggests that under anaerobic conditions a modified tricarboxylic acid cycle can operate. Some variations in specific activities were apparent as the worms matured but no qualitative differences were observed.     

Lessons from the eradication of smallpox: an interview with D. A. Henderson

It has been more than 35 years since the last naturally occurring case of smallpox. Sufficient time has passed to allow an objective overview of what were the key factors in the success of the eradication effort and what lessons smallpox can offer to other campaigns. Professor D. A. Henderson headed the international effort to eradicate smallpox. Here, we present a summary of D. A. Henderson''s perspectives on the eradication of smallpox. This text is based upon the Unither Baruch Blumberg Lecture, delivered by D. A. Henderson at the University of Oxford in November 2012 and upon conversations and correspondence with Professor Henderson.