| 1. |
- Alvarez, Francisco J., et al.
(författare)
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Diverse Nitrogen Sources in Seminal Fluid Act in Synergy To Induce Filamentous Growth of Candida albicans
- 2015
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 81:8, s. 2770-2780
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Tidskriftsartikel (refereegranskat)abstract
- The pathogenic fungus Candida albicans is the leading cause of vulvovaginal candidiasis (VVC). VVC represents a major quality- of-life issue for women during their reproductive years, a stage of life where the vaginal epithelium is subject to periodic hormonally induced changes associated with menstruation and concomitant exposure to serum as well as potential intermittent contact with seminal fluid. Seminal fluid potently triggers Candida albicans to switch from yeastlike to filamentous modes of growth, a developmental response tightly linked to virulence. Conversely, vaginal fluid inhibits filamentation. Here, we used artificial formulations of seminal and vaginal fluids that faithfully mimic genuine fluids to assess the contribution of individual components within these fluids to filamentation. The high levels of albumin, amino acids, and N-acetylglucosamine in seminal fluid act synergistically as potent inducers of filamentous growth, even at atmospheric levels of CO2 and reduced temperatures (30 degrees C). Using a simplified in vitro model that mimics the natural introduction of seminal fluid into the vulvovaginal environment, a pulse of artificial seminal fluid (ASF) was found to exert an enduring potential to overcome the inhibitory efficacy of artificial vaginal fluid (AVF) on filamentation. These findings suggest that a transient but substantial change in the nutrient levels within the vulvovaginal environment during unprotected coitus can induce resident C. albicans cells to engage developmental programs associated with virulent growth.
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| 2. |
- Hooijmaijers, Cornelis
(författare)
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Desiccation tolerance in red and green gametophytes of Jamesoniella colorata in relation to photoprotection.
- 2008
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Ingår i: Planta. - : Springer Science and Business Media LLC. - 0032-0935 .- 1432-2048. ; 227:6, s. 1301-10
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Tidskriftsartikel (refereegranskat)abstract
- This study tests the hypothesis that red-leaved gametophytes of the liverwort Jamesoniella colorata (Lehm.) Schiffn., which are found in relatively dry habitats, are more desiccation tolerant than their green counterparts, which are found in moister environments, through superior photoprotective systems. The potential role of red foliar pigments in relation to water deficits is investigated by measuring cell water-relations, oxidative damage and photosynthetic responses. The presence of red pigments, or other cellular constituents, did not affect cell water-relations during dehydration and thus appear not to be involved in cell osmotic regulation. During drying, both colour morphs showed a similar non-photochemical quenching activity and did not experience significant oxidative damage, as measured by the amounts of ascorbate, malondialdehyde and photosynthetic pigments. However, the levels of oxidative damage increased directly upon rewetting the gametophytes, especially in low light conditions (25 µmol m(-2) s(-1)). The efficiency of photosystem II only recovered partially after severe water deficits in both phenotypes. However, the red gametophytes recovered faster and more completely from mild water deficits than did the greens. Moreover, they experienced significantly less photobleaching after rehydration in low light. It is suggested that red pigments and/or carotenoids in these gametophytes improve desiccation tolerance by alleviating photooxidative damage.
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| 3. |
- Hooijmaijers, Cornelis, et al.
(författare)
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Photoprotective pigments in red and green gametophytesof two New Zealand liverworts
- 2007
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Ingår i: New Zealand Journal of Botany. - : The Royal Society of New Zealand. - 0028-825X .- 1175-8643. ; 45, s. 451-461
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Tidskriftsartikel (refereegranskat)abstract
- Gametophytes of Jamesoniella colorata (Jungermanniaceae) and Isotachis lyallii (Isotachidaceae) produce red leaves in exposed habitats, but green leaves in shaded environments. To understand the functional significance of this colour polymorphism, the anatomy, pigment composition, optical properties, and kinetics of chlorophyll a fluorescence were compared for red and green gametophytes. Both colour morphs were structurally similar, but the red leaves held unidentified red pigment(s) firmly associated with the cell wall. Green morphs contained more chlorophylls and carotenoids, and had higher ratios of chlorophylls to carotenoids, than did the red morphs. Red leaves absorbed 10% more photosynthetically active radiation, with a maximum at 540 nm, than did the green leaves. Under high irradiance, the red leaves maintained higher apparent quantum efficiencies for photosynthesis, and had larger photochemical and non-photochemical quenching values. The data indicate that red gametophytes have the greater potential to mitigate the damaging effects of high irradiance.
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