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51.
Reid JM Arcese P Cassidy AL Hiebert SM Smith JN Stoddard PK Marr AB Keller LF 《The American naturalist》2005,165(3):299-310
Models of sexual selection propose that exaggerated secondary sexual ornaments indicate a male's own fitness and the fitness of his offspring. These hypotheses have rarely been thoroughly tested in free-living individuals because overall fitness, as opposed to fitness components, is difficult to measure. We used 20 years of data from song sparrows (Melospiza melodia) inhabiting Mandarte Island, British Columbia, Canada, to test whether a male's song repertoire size, a secondary sexual trait, predicted overall measures of male or offspring fitness. Males with larger song repertoires contributed more independent and recruited offspring, and independent and recruited grandoffspring, to Mandarte's population. This was because these males lived longer and reared a greater proportion of hatched chicks to independence from parental care, not because females mated to males with larger repertoires laid or hatched more eggs. Furthermore, independent offspring of males with larger repertoires were more likely to recruit and then to leave more grandoffspring than were offspring of males with small repertoires. Although we cannot distinguish whether observed fitness variation reflected genetic or environmental effects on males or their offspring, these data suggest that female song sparrows would gain immediate and intergenerational fitness benefits by pairing with males with large song repertoires. 相似文献
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Mutations of the retinoblastoma tumor suppressor, pRb, or its cyclin-cyclin-dependent kinase (CDK) regulatory kinases or CDK inhibitors, allows unrestrained E2F activity, leading to unregulated cell cycle progression. However, overexpression of E2F-1 also sensitizes cells to apoptosis, suggesting that targeting this pathway may be of therapeutic benefit. Enforced expression of E2F-1 in interleukin-3-dependent myeloid cells led to preferential sensitivity to the topoisomerase II inhibitor, etoposide, which was independent of p53 accumulation. Pretreatment of the E2F-1-expressing cells with ICRF-193, a second topoisomerase II inhibitor that does not cause DNA damage, protected these cells against etoposide-induced apoptosis. However, ICRF-193 cooperated with other DNA-damaging agents to induce apoptosis. Enforced expression of E2F-1 led to accumulation of p53 protein. An E2F-1 mutant that is defective in inducing cell cycle progression also induced p53, suggesting that p53 was responding directly to E2F, and not to secondary events caused by inappropriate cell cycle progression (i.e., DNA damage). Thus, topoisomerase II inhibition and DNA damage cooperate to selectively induce apoptosis in cells that have mutations in the pRb pathway. 相似文献
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55.
Daniel Hiebert 《Ethnic and racial studies》2015,38(1):5-21
In this paper we advocate the study of local street markets to explore fundamental issues about the relationship between economy and society. This relationship evolves over time and we believe that it has been recast in an age of increasing cultural diversity and neo-liberal state regulatory structures. In street markets we can see how diversity and the nature of economic transactions become mutually constitutive. We argue that cultural diversity propels local markets, while everyday interactions in markets influence intercultural relationships. These complex processes are affected by the spatiality of markets and the regulatory environments within which they operate. We conclude by framing a research programme on street markets and discuss a number of methodological complications that would need to be addressed in this endeavour. 相似文献
56.
Hottes TS Skowronski DM Hiebert B Janjua NZ Roos LL Van Caeseele P Law BJ De Serres G 《PloS one》2011,6(7):e22618
Background
Administrative databases provide efficient methods to estimate influenza vaccine effectiveness (IVE) against severe outcomes in the elderly but are prone to intractable bias. This study returns to one of the linked population databases by which IVE against hospitalization and death in the elderly was first assessed. We explore IVE across six more recent influenza seasons, including periods before, during, and after peak activity to identify potential markers for bias.Methods and Findings
Acute respiratory hospitalization and all-cause mortality were compared between immunized/non-immunized community-dwelling seniors ≥65years through administrative databases in Manitoba, Canada between 2000-01 and 2005-06. IVE was compared during pre-season/influenza/post-season periods through logistic regression with multivariable adjustment (age/sex/income/residence/prior influenza or pneumococcal immunization/medical visits/comorbidity), stratification based on prior influenza immunization history, and propensity scores. Analysis during pre-season periods assessed baseline differences between immunized and unimmunized groups. The study population included ∼140,000 seniors, of whom 50–60% were immunized annually. Adjustment for key covariates and use of propensity scores consistently increased IVE. Estimates were paradoxically higher pre-season and for all-cause mortality vs. acute respiratory hospitalization. Stratified analysis showed that those twice consecutively and currently immunized were always at significantly lower hospitalization/mortality risk with odds ratios (OR) of 0.60 [95%CI0.48–0.75] and 0.58 [0.53–0.64] pre-season and 0.77 [0.69–0.86] and 0.71 [0.66–0.77] during influenza circulation, relative to the consistently unimmunized. Conversely, those forgoing immunization when twice previously immunized were always at significantly higher hospitalization/mortality risk with OR of 1.41 [1.14–1.73] and 2.45 [2.21–2.72] pre-season and 1.21 [1.03–1.43] and 1.78 [1.61–1.96] during influenza circulation.Conclusions
The most pronounced IVE estimates were paradoxically observed pre-season, indicating bias tending to over-estimate vaccine protection. Change in immunization habit from that of the prior two years may be a marker for this bias in administrative data sets; however, no analytic technique explored could adjust for its influence. Improved methods to achieve valid interpretation of protection in the elderly are needed. 相似文献57.
Colin W. Hiebert Tom G. Fetch Taye Zegeye Julian B. Thomas Daryl J. Somers D. Gavin Humphreys Brent D. McCallum Sylvie Cloutier Davinder Singh Doug R. Knott 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,122(1):143-149
Stem rust (caused by Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn.) has re-emerged as a threat to wheat production with the evolution of new pathogen races, namely TTKSK
(Ug99) and its variants, in Africa. Deployment of resistant wheat cultivars has provided long-term control of stem rust. Identification
of new resistance genes will contribute to future cultivars with broad resistance to stem rust. The related Canadian cultivars
Peace and AC Cadillac show resistance to Ug99 at the seedling stage and in the field. The purpose of this study was to elucidate
the inheritance and genetically map resistance to Ug99 in these two cultivars. Two populations were produced, an F2:3 population from LMPG/AC Cadillac and a doubled haploid (DH) population from RL6071/Peace. Both populations showed segregation
at the seedling stage for a single stem rust resistance (Sr) gene, temporarily named SrCad. SrCad was mapped to chromosome 6DS in both populations with microsatellite markers and a marker (FSD_RSA) that is tightly linked
to the common bunt resistance gene Bt10. FSD_RSA was the closest marker to SrCad (≈1.6 cM). Evaluation of the RL6071/Peace DH population and a second DH population, AC Karma/87E03-S2B1, in Kenya showed
that the combination of SrCad and leaf rust resistance gene Lr34 provided a high level of resistance to Ug99-type races in the field, whereas in the absence of Lr34 SrCad conferred moderate resistance. A survey confirmed that SrCad is the basis for all of the seedling resistance to Ug99 in Canadian wheat cultivars. While further study is needed to determine
the relationship between SrCad and other Sr genes on chromosome 6DS, SrCad represents a valuable genetic resource for producing stem rust resistant wheat cultivars. 相似文献
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59.
Caitlyn W. Barrett J. Joshua Smith Lauren C. Lu Nicholas Markham Kristy R. Stengel Sarah P. Short Baolin Zhang Aubrey A. Hunt Barbara M. Fingleton Robert H. Carnahan Michael E. Engel Xi Chen R. Daniel Beauchamp Keith T. Wilson Scott W. Hiebert Albert B. Reynolds Christopher S. Williams 《PloS one》2012,7(12)
60.
Sheung-Tak Cheng Rosanna WL Lau Emily PM Mak Natalie SS Ng Linda CW Lam Helene H Fung Julian CL Lai Timothy Kwok Diana TF Lee 《Trials》2012,13(1):1-10