排序方式: 共有185条查询结果,搜索用时 15 毫秒
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Marc Choisy Pejman Rohani 《Proceedings. Biological sciences / The Royal Society》2012,279(1747):4574-4581
Prediction and control of the geographical spread of emerging pathogens has become a central public health issue. Because these infectious diseases are by definition novel, there are few data to characterize their dynamics. One possible solution to this problem is to apply lessons learnt from analyses of historical data on familiar and epidemiologically similar pathogens. However, the portability of the spatial ecology of an infectious disease in a different epoch to other infections remains unexamined. Here, we study this issue by taking advantage of the recent re-emergence of pertussis in the United States to compare its spatial transmission dynamics throughout the 1950s with the past decade. We report 4-year waves, sweeping across the continent in the 1950s. These waves are shown to emanate from highly synchronous foci in the northwest and northeast coasts. In contrast, the recent resurgence of the disease is characterized by 5.5-year epidemics with no particular spatial structure. We interpret this to be the result of dramatic changes in patterns of human movement over the second half of the last century, together with changing age distribution of pertussis. We conclude that extrapolation regarding the spatial spread of contemporaneous pathogens based on analyses of historical incidence may be potentially very misleading. 相似文献
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Salmonella enteritidis is a food-borne enteric human pathogen that can form a complex protective extracellular matrix. We describe here a component of this matrix which is distinct from other known salmonella extracellular polysaccharides such as cellulose and colanic acid. We have used glycosyl composition and linkage analysis, as well as 1D and 2D NMR spectroscopy to determine the structure of this polysaccharide. We propose that the primary saccharide in the S. enteritidis capsule has a branched tetrasaccharide repeating unit having the following structure: -->3)-alpha-D-Galp-(1-->2)-[alpha-Tyvp-(1-->3)]-alpha-D-Manp-(1-->4)-alpha-L-Rhap-(1-->. This structure is partially substituted on both tyvelose and galactose with a glucose-containing side chain. It further bears considerable similarity to the O antigen from this organism, a feature found in a number of other capsules from Gram-negative bacteria. In addition, we have detected fatty acids at levels that indicate the presence of a lipid anchor. 相似文献
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Valentine Otang Ntui Gunaratnam Thirukkumaran Pejman Azadi Raham Sher Khan Ikuo Nakamura Masahiro Mii 《Plant cell reports》2010,29(9):943-954
Production of “Egusi” melon (Colocynthis citrullus L.) in West Africa is limited by fungal diseases, such as Alternaria leaf spot and Fusarium wilt. In order to engineer “Egusi”
resistant to these diseases, cotyledonary explants of two “Egusi” genotypes, ‘Ejagham’ and NHC1-130, were transformed with
Agrobacterium tumefaciens strain EHA101 harbouring wasabi defensin gene (isolated from Wasabia japonica L.) in a binary vector pEKH1. After co-cultivation for 3 days, infected explants were transferred to MS medium containing
100 mgl−l kanamycin to select transformed tissues. After 3 weeks of culture, adventitious shoots appeared directly along the edges
of the explants. As much as 19 out of 52 (36.5%) and 25 out of 71 (35.2%) of the explants in genotype NHC1-130 and ‘Ejagham’,
respectively, formed shoots after 6 weeks of culture. As much as 74% (14 out of 19) of the shoots regenerated in genotype
NHC1-130 and 72% (18 out of 25) of those produced in genotype ‘Ejagham’ were transgenic. A DNA fragment corresponding to the
wasabi defensin gene or the selection marker nptII was amplified by PCR from the genomic DNA of all regenerated plant clones rooted on hormone-free MS medium under the same
selection pressure, suggesting their transgenic nature. Southern blot analysis confirmed successful integration of 1–5 copies
of the transgene. RT-PCR, northern and western blot analyses revealed that wasabi defensin gene was expressed in transgenic
lines. Transgenic lines showed increased levels of resistance to Alternaria solani, which causes Alternaria leaf spot and Fusarium oxysporum, which causes Fusarium wilt, as compared to that of untransformed plants. 相似文献
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Hashemzadeh Pejman Ghorbanzadeh Vajihe Valizadeh Otaghsara Seyede Maryam Dariushnejad Hassan 《International journal of peptide research and therapeutics》2020,26(3):1523-1525
International Journal of Peptide Research and Therapeutics - Prostate cancer is one of the most common cancers around the world. Vaccines are a new hope for prevention of this cancer. In the case... 相似文献
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Hashemzadeh Pejman Ghorbanzadeh Vajihe Lashgarian Hamed Esmaeil Kheirandish Farnaz Dariushnejad Hassan 《International journal of peptide research and therapeutics》2020,26(3):1417-1428
International Journal of Peptide Research and Therapeutics - Kala-azar or visceral leishmaniasis (VL) is the most important vector-borne protozoan disease and a life-threatening problem in the... 相似文献
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Aminlari M Gholami S Vaseghi T Azadi A Karimi H 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2000,127(3):369-374
The enzyme rhodanese (thiosulfate:cyanide sulfurtransferase) is a ubiquitous enzyme present in all living organisms, from bacteria to humans and plays a central role in cyanide detoxification. The purpose of this investigation is to determine and compare rhodanese activity in different parts of urogenital systems of male and female sheep fetuses at 2.5, 3, 3.5, 4, 4.5, and 5 months of age. The highest activity of rhodanese in male fetus was in kidney cortex, followed by medulla of the kidney. No significant difference was observed in other organs. In female fetus, the highest activity was in kidney cortex followed by oviduct and medulla of kidney. The enzyme activity of tissues increased with age. There was no significant difference (P > 0.05) between male and female fetuses in levels of rhodanese activity of different tissues except in urinary bladder at 2.5 and 3 months and in urethra at 4.5 months of age. The results of this study might indicate the involvement of rhodanese in cyanide detoxification in tissues which are more exposed to cyanide. On the other hand, rhodanese might perform other functions which are specific in these tissues. 相似文献
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