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91.
J. G. P. Power R. M. Barnes W. N. C. Nash J. D. Robinson 《BMJ (Clinical research ed.)》1969,3(5666):336-337
Investigation of an outbreak of lead-poisoning in 121 Gurkha soldiers showed that this was due to the contamination of chilli powder (cayenne pepper), a constituent of curry powder, with lead chromate. Comprehensive systems of food sampling are needed in developing communities. 相似文献
92.
James A. Cahill Richard E. Green Tara L. Fulton Mathias Stiller Flora Jay Nikita Ovsyanikov Rauf Salamzade John St. John Ian Stirling Montgomery Slatkin Beth Shapiro 《PLoS genetics》2013,9(3)
Despite extensive genetic analysis, the evolutionary relationship between polar bears (Ursus maritimus) and brown bears (U. arctos) remains unclear. The two most recent comprehensive reports indicate a recent divergence with little subsequent admixture or a much more ancient divergence followed by extensive admixture. At the center of this controversy are the Alaskan ABC Islands brown bears that show evidence of shared ancestry with polar bears. We present an analysis of genome-wide sequence data for seven polar bears, one ABC Islands brown bear, one mainland Alaskan brown bear, and a black bear (U. americanus), plus recently published datasets from other bears. Surprisingly, we find clear evidence for gene flow from polar bears into ABC Islands brown bears but no evidence of gene flow from brown bears into polar bears. Importantly, while polar bears contributed <1% of the autosomal genome of the ABC Islands brown bear, they contributed 6.5% of the X chromosome. The magnitude of sex-biased polar bear ancestry and the clear direction of gene flow suggest a model wherein the enigmatic ABC Island brown bears are the descendants of a polar bear population that was gradually converted into brown bears via male-dominated brown bear admixture. We present a model that reconciles heretofore conflicting genetic observations. We posit that the enigmatic ABC Islands brown bears derive from a population of polar bears likely stranded by the receding ice at the end of the last glacial period. Since then, male brown bear migration onto the island has gradually converted these bears into an admixed population whose phenotype and genotype are principally brown bear, except at mtDNA and X-linked loci. This process of genome erosion and conversion may be a common outcome when climate change or other forces cause a population to become isolated and then overrun by species with which it can hybridize. 相似文献
93.
Ferdinand C. O. Los Tara M. Randis Raffi V. Aroian Adam J. Ratner 《Microbiology and molecular biology reviews》2013,77(2):173-207
SUMMARY
Pore-forming toxins (PFTs) are the most common bacterial cytotoxic proteins and are required for virulence in a large number of important pathogens, including Streptococcus pneumoniae, group A and B streptococci, Staphylococcus aureus, Escherichia coli, and Mycobacterium tuberculosis. PFTs generally disrupt host cell membranes, but they can have additional effects independent of pore formation. Substantial effort has been devoted to understanding the molecular mechanisms underlying the functions of certain model PFTs. Likewise, specific host pathways mediating survival and immune responses in the face of toxin-mediated cellular damage have been delineated. However, less is known about the overall functions of PFTs during infection in vivo. This review focuses on common themes in the area of PFT biology, with an emphasis on studies addressing the roles of PFTs in in vivo and ex vivo models of colonization or infection. Common functions of PFTs include disruption of epithelial barrier function and evasion of host immune responses, which contribute to bacterial growth and spreading. The widespread nature of PFTs make this group of toxins an attractive target for the development of new virulence-targeted therapies that may have broad activity against human pathogens. 相似文献94.
95.
Background
The nematode Caenorhabditis elegans has emerged as a powerful system to study biologic questions ranging from development to aging. The generation of transgenic animals is an important experimental tool and allows use of GFP fusion proteins to study the expression of genes of interest or generation of epitope tagged versions of specific genes. Transgenes are often generated by placing a promoter upstream of a reporter gene or cDNA. This often produces a representative expression pattern, but important exceptions have been observed. To better capture the genuine expression pattern and timing, several investigators have modified large pieces of DNA carried by BACs or fosmids for use in the construction of transgenic animals via recombineering. However, these techniques are not in widespread use despite the advantages when compared to traditional approaches. Additionally, some groups have encountered problems with employing these techniques. Hence, we sought identify ways to improve the simplicity and reliability of the procedure. 相似文献96.
97.
Richard S. Cottrell Aysha Fleming Elizabeth A. Fulton Kirsty L. Nash Reg A. Watson Julia L. Blanchard 《Global Change Biology》2018,24(2):580-596
With the human population expected to near 10 billion by 2050, and diets shifting towards greater per‐capita consumption of animal protein, meeting future food demands will place ever‐growing burdens on natural resources and those dependent on them. Solutions proposed to increase the sustainability of agriculture, aquaculture, and capture fisheries have typically approached development from single sector perspectives. Recent work highlights the importance of recognising links among food sectors, and the challenge cross‐sector dependencies create for sustainable food production. Yet without understanding the full suite of interactions between food systems on land and sea, development in one sector may result in unanticipated trade‐offs in another. We review the interactions between terrestrial and aquatic food systems. We show that most of the studied land–sea interactions fall into at least one of four categories: ecosystem connectivity, feed interdependencies, livelihood interactions, and climate feedback. Critically, these interactions modify nutrient flows, and the partitioning of natural resource use between land and sea, amid a backdrop of climate variability and change that reaches across all sectors. Addressing counter‐productive trade‐offs resulting from land‐sea links will require simultaneous improvements in food production and consumption efficiency, while creating more sustainable feed products for fish and livestock. Food security research and policy also needs to better integrate aquatic and terrestrial production to anticipate how cross‐sector interactions could transmit change across ecosystem and governance boundaries into the future. 相似文献
98.
99.
Truc Thi Kim Thanh Hoang Anneline Nansen Sugata Roy Rolf Billeskov Claus Aagaard Tara Elvang Jes Dietrich Peter Andersen 《PloS one》2009,4(6)
Background
Recently we and others have identified CD8 and CD4 T cell epitopes within the highly expressed M. tuberculosis protein TB10.4. This has enabled, for the first time, a comparative study of the dynamics and function of CD4 and CD8 T cells specific for epitopes within the same protein in various stages of TB infection.Methods and Findings
We focused on T cells directed to two epitopes in TB10.4; the MHC class I restricted epitope TB10.4 3–11 (CD8/10.4 T cells) and the MHC class II restricted epitope TB10.4 74–88 (CD4/10.4 T cells). CD4/10.4 and CD8/10.4 T cells displayed marked differences in terms of expansion and contraction in a mouse TB model. CD4/10.4 T cells dominated in the early phase of infection whereas CD8/10.4 T cells were expanded after week 16 and reached 5–8 fold higher numbers in the late phase of infection. In the early phase of infection both CD4/10.4 and CD8/10.4 T cells were characterized by 20–25% polyfunctional cells (IL-2+, IFN-γ+, TNF-α+), but whereas the majority of CD4/10.4 T cells were maintained as polyfunctional T cells throughout infection, CD8/10.4 T cells differentiated almost exclusively into effector cells (IFN-γ+, TNF-α+). Both CD4/10.4 and CD8/10.4 T cells exhibited cytotoxicity in vivo in the early phase of infection, but whereas CD4/10.4 cell mediated cytotoxicity waned during the infection, CD8/10.4 T cells exhibited increasing cytotoxic potential throughout the infection.Conclusions/Significance
Our results show that CD4 and CD8 T cells directed to epitopes in the same antigen differ both in their kinetics and functional characteristics throughout an infection with M. tuberculosis. In addition, the observed strong expansion of CD8 T cells in the late stages of infection could have implications for the development of post exposure vaccines against latent TB. 相似文献100.
Jane Zochling Felicity Newell Jac C Charlesworth Paul Leo Jim Stankovich Adrian Cortes Yuan Zhou Wendy Stevens Joanne Sahhar Janet Roddy Peter Nash Kathleen Tymms Maureen Rischmueller Sue Lester Susanna Proudman Matthew A Brown 《Arthritis research & therapy》2014,16(5)