Browsing by Author "Wynne-Edwards, Katherine"
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- ItemOpen AccessConceptus-derived Fibrinogen and its Implication in Equine Pregnancy(2017) Macedo da Silva, Alysson; Klein, Claudia; Wynne-Edwards, Katherine; Kastelic, John; MacPhee, DanielThe equine conceptus presents an extensive mobile stage from days 9 to 16 after ovulation, during which it becomes fixed to one of the uterine horns. Throughout mobility, the conceptus secretes fibrinogen (an integrin-binding ECM). We hypothesized that conceptus-derived fibrinogen is converted into fibrin and aids in fixation via integrin receptors. We determined that RGD-binding integrins are expressed in endometrial and embryonic/fetal cells and interact with fibrinogen. Moreover, endometrial and embryonic cells presented the machinery to convert fibrinogen into fibrin and maintain the fibrin network. Overall, we demonstrated that conceptus-derived fibrinogen is likely converted to fibrin at the embryo-maternal interface and mediates cell adhesion via RGD-binding integrins.
- ItemOpen AccessEcology of Sex Ratios in Mountain Pine Beetles, Dendroctonus ponderosae(2016) Lachowsky, Leanna Elizabeth; Reid, Mary; Gwynne, Darryl; Harder, Lawrence; Vamosi, Steven; Wynne-Edwards, KatherineBiased sex ratios pose a fundamental question in evolutionary ecology. Populations are expected to have equal numbers of males and females when each offspring is produced from one mother and one father with equal genetic contributions. In mountain pine beetles (MPB), Dendroctonus ponderosae Hopkins, consistent reports of female-biased adult sex ratios (2:1 F:M) demand explanation. I investigated whether adult sex ratios of MPB reflected initial investment or became biased through adaptive or non-adaptive processes. Differential mortality is a potentially non-adaptive process that could bias sex ratios at later life stages, an idea often invoked to explain female-biased adult sex ratios in this system. However, Fisher noted that if mortality occurs during parental investment, selection will act to bias the primary sex ratio towards the sex with higher mortality, achieving an evolutionary stable state where expenditure to each sex is equal. Individual allocation strategies may differ depending on maternal condition. In insects, daughters were expected to benefit more from increased investment because of the strong relationship between body size and fecundity. Through genotyping of eggs from individual broods reared in the laboratory, I found that primary sex ratios of MPB were male-biased (~1:0.86). Male-biased primary sex ratios were counter to expectations if the sex-ratio distorter Wolbachia was acting in the system; Wolbachia was not detected in a screen of ten populations. Female-biased adult sex ratios arose from subsequent male-biased mortality, observed in both laboratory-reared broods and in experimentally manipulated overwintering field populations. Moreover, condition-dependent allocation occurred, but was counter to expectations, with larger females producing more males than did smaller females. Larger mothers produced larger eggs that experienced less male mortality. In this case, larger mothers gain more from investing in the rare sex than investing in daughters. Given male-biased developmental mortality, a male-biased primary sex ratio is consistent with Fisher’s theory of equal investment favouring the sex with greater mortality during parental investment. Further, differential mortality of the sexes is a strong selective force to which condition-dependent sex allocation may respond more strongly than increases in body size.
- ItemOpen AccessPhysiological consequences of environmental contamination in an elasmobranch with matrotrophic histotrophy, the Round Stingray (Urobatis halleri)(2018-01-15) Lyons, Katherine; Wynne-Edwards, Katherine; Syme, Douglas; Cobb, John; Anderson, Gary; Smits, JuditA range of physiological biomarkers were compared in two populations of Round Stingray (Urobatis halleri) that differed primarily in PCB exposure. Females, and their embryos, were sampled each month of pregnancy at both sites, while adult males were matched with a 40-day subset of females to investigate the effect of sex and its interaction with PCB exposure. I hypothesized that exposure would have negative energetic outcomes for PCB-exposed, compared to reference population, stingrays. Adverse impacts were widespread. Number of offspring was not affected by PCB exposure; however, exposure exacerbated maternal tissue mass, and quality, loss during pregnancy. PCB-exposed females also compromised osmoregulation with urea, an important osmolyte, reduced in maternal plasma. Higher liver quality in contaminant-exposed females was not associated with higher embryo quality, suggesting contaminants increase metabolic demands in adult females and lead to inefficiencies in embryos’ use of maternal resources. Embryos also influenced their uterine environment, as they were steroidogenic and capable of osmoregulating very early in development. I found sex- related differences in embryo mass only at the reference site, suggesting that contaminant effects on males begin in utero. These contaminant sex-related effects extended into adulthood, as relative liver mass and energy content were lower in comparably-sized adult males than females, whereas fewer differences were found between adults at the reference site. Higher energy generation potential, combined with lower tissue quality in contaminant-exposed adult males suggests they are more energetically compromised than females, despite the latter’s costly pregnancy demands. Regardless of sex, contaminant exposure had negative impacts on the ability of adult stingrays to mount a robust secondary stress response as reflected by lower plasma glucose levels after stress, thus potentially impairing their ability to respond to acute stressors. Effects found both in utero and in adulthood suggest that contaminants have a significant, and potentially life-long, impact on Round Stingray homeostasis. This has implications for other species with greater contaminant burdens. Contaminant exposure, and its interactive effects with sex and age, should be included as part of effective elasmobranch management.
- ItemOpen AccessSample Preparation and Liquid Chromatography-Tandem Mass Spectrometry for Multiple Steroids in Mammalian and Avian Circulation(Public Library of Science, 2012-02-27) Koren, Lee; Ng, Ella S. M.; Soma, Kiran K.; Wynne-Edwards, Katherine