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LUCA BRAGAZZA 《Global Change Biology》2008,14(11):2688-2695
Heat waves, which are projected to be more frequent and intense in a warmer climate, could become a serious threat to plants that rely on water surplus availability, such as bryophytes. Here, I take the advantage of the European summer 2003 climate anomaly to assess the impact of an extreme heat wave on peat mosses of the genus Sphagnum, a group of bryophytes forming the bulk of living and dead biomass in peatlands. With this aim, 20 selected bogs in the Italian Alps were checked for Sphagnum survival in the years following the heat wave. Over the study area, the period May–September 2003 was characterized by higher mean monthly air temperature (13.5 °C) and lower mean monthly precipitation (87 mm) compared with normal climatic conditions (11.5 °C and 117 mm, respectively) so that the heat wave coincided with a drought spell. As a consequence of the unusual water stress, I documented an increased mortality of peat mosses forming high hummocks. In particular, at habitat scale, the distribution of desiccated peat mosses was restricted to the hummock face receiving the greatest amount of solar irradiation. However, at regional scale, the present study identified a climatic threshold, simply defined by the ratio of precipitation to temperature (P : T), which triggered an irreversible desiccation of peat mosses when mean monthly P : T dropped below 6.5 (mm : °C) during May–September 2003. The absence of any sign of recovery after 4 years since the drought must be seen as a harbinger of the deleterious effects of extreme heat waves on organisms not adapted to cope with abrupt climate anomaly. 相似文献
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ELISA BIGLIARDI MARIA GIOVANNA RIPARBELLI MARIA GLORIA SELMI LUCA BINI SABRINA LIBERATORI VITALIANO PALLINI ANNA BERNUZZI SIMONETTA GATTI MASSIMO SCAGLIA LUCIANO SACCHI 《The Journal of eukaryotic microbiology》1999,46(4):410-415
Using transmission electron microscopy, immuno-electron microscopy, and biochemical techniques such as 2-D electrophoresis and immunoblotting, actin was found in all biological stages of the microsporidia Encephalitozoon hellem and Encephalitozoon cuniculi. 相似文献
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SIRO PASSI MAURO GRANDINETTI FRANCESCO MAGGIO ANDREA STANCATO CHIARA DE LUCA 《Pigment cell & melanoma research》1998,11(2):81-85
Epidermal levels of enzymatic and non-enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), vitamin E (Vit E), ubiquinol (CoQ10H2), and reduced glutathione (GSH), as well as polyunsaturated fatty acids of phospholipids (PL-PUFA), were evaluated in the affected epidermis of 15 patients with active vitiligo (AVP) and in the corresponding epidermis of 15 healthy phototype matched controls. The epidermal levels of CoQ10H2, Vit E, GSH, and CAT activity were significantly reduced in AVP and were associated with a marked increase of oxidized glutathione, whereas SODs and GSH-Px activities and ubiquinone concentration remained similar to control values. Antioxidant deficiency, in particular the decline of lipophilic antioxidants, i. e., CoQ10H2 and Vit E, accounts well for PL-PUFA reduction observed in vitiligo epidermis, mainly affecting C18: 3 n-3, C20: 3 n-6, C20: 4 n-6, and C22: 6 n-3 fatty acids and suggesting the occurrence of a lipoperoxidative process. In conclusion, both an imbalance of the intracellular redox status and a significant depletion of enzymatic and non-enzymatic antioxidants feature the epidermis of AVP, and represent a fingerprint of an abnormal oxidative stress leading to epidermal cell injury. 相似文献
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