[Show abstract][Hide abstract] ABSTRACT: By using life table parameters, the effects of seven constant temperature regimes (17, 20, 23, 26, 29, 32 and 35 degrees C) on the development and reproduction of Sylepta derogata was investigated. The results indicated that the durations of egg-laying, larval, pupal, and adult stages of S. derogata shortened significantly when the temperature increased from 17 degrees C to 26 degrees C, but prolonged at 32 degrees C and 35 degrees C. The lower development threshold temperature of S. derogata at its all development stages was 12.08 degrees C, and the effective accumulative temperature was 436.2 degree-days. The survival rates of all immature stages were the highest at 26 degrees C, and would be decreased when the temperature was above or under 26 degrees C. The innate capacity to increase (rm), net reproductive rate (R0), and finite rate of increase (lambda) reached the maximum at 29, 26 and 32 degrees C, with the values being 0.1268, 415.65 and 1.185, respectively. The mean generation time (T) shortened with increasing temperature, with the maximum and minimum values of 89.11 and 28.68 days at 17 degrees C and 35 degrees C, respectively.
No preview · Article · Jul 2008 · Ying yong sheng tai xue bao = The journal of applied ecology / Zhongguo sheng tai xue xue hui, Zhongguo ke xue yuan Shenyang ying yong sheng tai yan jiu suo zhu ban
[Show abstract][Hide abstract] ABSTRACT: Phospholipid hydroperoxide glutathione peroxidase is an antioxidant enzyme that has the highest capability of reducing membrane-bound hydroperoxy lipids as compared to free organic and inorganic hydroperoxides amongst the glutathione peroxidases. In this study, urea-induced effects on the inactivation and unfolding of a recombinant phospholipid hydroperoxide glutathione peroxidase (PHGPx) from Oryza sativa were investigated by means of circular dichroism and fluorescence spectroscopy. With the increase of urea concentration, the residual activity of OsPHGPx decreases correspondingly. When the urea concentration is above 5.0 mol/L, there was no residual activity. In addition, the observed changes in intrinsic tryptophan fluorescence, the binding of the hydrophobic fluorescence probe ANS, and the far UV CD describe a common dependence on the concentration of urea suggesting that the conformational features of the native OsPHGPx are lost in a highly cooperative single transition. The unfolding process comprises of three zones: the native base-line zone between 0 and 2.5 mol/L urea, the transition zone between 2.5 and 5.5 mol/L urea, and the denatured base-line zone above 5.5 mol/L urea. The transition zone has a midpoint at about 4.0 mol/L urea.
No preview · Article · Sep 2007 · Chemical Research in Chinese Universities