The landscape of recombination in African Americans

Recombination, together with mutation, gives rise to genetic variation in populations. Here we leverage the recent mixture of people of African and European ancestry in the Americas to build a genetic map measuring the probability of crossing over at each position in the genome, based on about 2.1 million crossovers in 30,000 unrelated African Americans. At intervals of more than three megabases it is nearly identical to a map built in Europeans. At finer scales it differs significantly, and we identify about 2,500 recombination hotspots that are active in people of West African ancestry but nearly inactive in Europeans. The probability of a crossover at these hotspots is almost fully controlled by the alleles an individual carries at PRDM9 (P?value 相似文献   

Ascaris suum draft genome

Parasitic diseases have a devastating, long-term impact on human health, welfare and food production worldwide. More than two billion people are infected with geohelminths, including the roundworms Ascaris (common roundworm), Necator and Ancylostoma (hookworms), and Trichuris (whipworm), mainly in developing or impoverished nations of Asia, Africa and Latin America. In humans, the diseases caused by these parasites result in about 135,000 deaths annually, with a global burden comparable with that of malaria or tuberculosis in disability-adjusted life years. Ascaris alone infects around 1.2 billion people and, in children, causes nutritional deficiency, impaired physical and cognitive development and, in severe cases, death. Ascaris also causes major production losses in pigs owing to reduced growth, failure to thrive and mortality. The Ascaris-swine model makes it possible to study the parasite, its relationship with the host, and ascariasis at the molecular level. To enable such molecular studies, we report the 273 megabase draft genome of Ascaris suum and compare it with other nematode genomes. This genome has low repeat content (4.4%) and encodes about 18,500 protein-coding genes. Notably, the A. suum secretome (about 750 molecules) is rich in peptidases linked to the penetration and degradation of host tissues, and an assemblage of molecules likely to modulate or evade host immune responses. This genome provides a comprehensive resource to the scientific community and underpins the development of new and urgently needed interventions (drugs, vaccines and diagnostic tests) against ascariasis and other nematodiases.     

Capillary lengths and areas, and intercapillary distances in tissue near the human knee.

Quantiative stereological electron microscopy has been used to investigate the capillary lengths, surface areas and intercapillary distances in the tissues around the human knee, the synovial membrane, synovial capsule, fat and tendon. The vascularity of these regions was much less than in other areas of the body, especially muscle.     

A possible method for improving the efficacy of dapsone

The antileprosy drug dapsone is unable to penetrate intact Mycobacterium leprae in vitro, as determined by its effect on o-diphenoloxidase in the bacilli. When combined with the peptide polylysine, the sulfone drug passes through the bacterial cell membranes, and penetrates the enzyme protein, resulting in a 100% inhibition of its activity.     

Capillary lengths and areas,and intercapillary distances in tissue near the human knee

Summary Quantitative stereological electron microscopy has been used to investigate the capillary lengths, surface areas and intercapillary distances in the tissues around the human knee, the synovial membrane, synovial capsule, fat and tendon. The vascularity of these regions was much less than in other areas of the body, especially muscle.This work was performed with the support of the Australian Research Grants Committee and the skilful assistance of Mr.K. W. J. Crocker.