The world's wealth of plant genetic resources has much value for world food security, but these resources are under considerable threat. Crop improvement, particularly under climate change, depends on the genetic diversity of our plant genetic resources, which are arguably inadequately conserved and poorly used. There is wide recognition that the Convention on Biological Diversity's 2010 targets to reduce the loss of biodiversity have not been met. Biodiversity is at risk from multiple threats, including climate change, and the genetic diversity contained within plant genetic resources, particularly of species that are wild relatives of our crops, faces similar threats but is essential to our ability to respond to the new stresses in the agricultural environment resulting from climate change. It is important to consider the genetic value of these crop wild relatives, how they may be conserved, and what new technologies can be implemented to enhance their use.

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The bipyridyl herbicide, diquat, is a potent prooxidant that generates superoxide anions through redox cycling in vivo. Exposure to elevated levels of this compound causes acute hepatic and renal toxicity as well as death in rodents. In the present study, we investigated whether melatonin, a free radical scavenger and antioxidant, could protect against diquat-induced hepatic and renal damage and whether the indole would improve survival of Kunming mice given a lethal dose of diquat. When mice were intraperitoneally (i.p.) given a single dose of diquat (50 mg/kg body weight), liver and kidney injuries were observed at 6 hr as indicated by elevated serum levels of both alanine aminotransferase (ALT) activity and blood urea nitrogen (BUN). In addition, lipid peroxidation levels in both liver and kidney showed significant increases as shown by elevated concentrations of F(2)-isoprostanes. The administration of melatonin (20 mg/kg) 30 min before the diquat injection resulted in a significant reduction in serum levels of ALT and BUN as well as hepatic and renal F(2)-isoprostanes levels. For the survival study, 75 mg/kg diquat was administered i.p. into mice to induce acute death. Without melatonin treatment, 10 of 23 (43.5%) mice died within 24 hr after diquat injection. Pretreatment with melatonin (20 mg/kg) 30 min prior to the injection of diquat and thereafter at 4-hr intervals until the end of the observation period (24 hr), reduced the death rate to two of 22 (9.1%) mice. Chi-squared test revealed a significant difference with P< or = 0.05. In conclusion, melatonin, a broad spectrum antioxidant, reduces hepatic and renal damage and lowers the death rate in diquat-treated mice.

In this paper, we compare the relationship between scale and period in ecological pattern analysis and wavelet analysis. We also adapt a commonly used wavelet, the Morlet, to ecological pattern analysis. Using Monte Carlo assessments, we apply methods of statistical significance test to wavelet analysis for pattern analysis. In order to understand the inherent strength and weakness of the Morlet and the Mexican Hat wavelets, we also investigate and compare the properties of two frequently used wavelets by testing with field data and four artificial transects of different typical patterns which is often encountered in ecological research. It is shown that the Mexican Hat provides better detection and localization of patch and gap events over the Morlet, whereas the Morlet offers improved detection and localization of scale over the Mexican Hat. There is always a trade-off between the detection and localization of scale versus patch and gap events. Therefore, the best composite analysis is the combination of their advantages. The properties of wavelet in dealing with ecological data may be affected by characteristics intrinsic to wavelet itself. The peaks of different scales in isograms of wavelet power spectrum from the Mexican Hat may overlap with each other. Alternatively, these peaks of different scales in isograms of wavelet power spectrum may combine with each other unless the size of the analyzed scales is significantly different. These overlapping or combining lead to combining of peaks for different scales, or the masking of trough between peaks of different scales in the scalogram.Ecologists should combine all the information in scalogram and isograms of wavelet coefficient and wavelet power spectrum from different wavelets, which can provide us a broader view and precise pattern information.

Melatonin is a powerful antioxidant and free radical scavenger. A large body of in vivo and in vitro evidence shows that melatonin effectively inhibits membrane lipid peroxidation; this damage was based on the measurement of malondialdehyde and/or 4-hydroxynonenal levels. In the current study, for the first time using a more sensitive and specific biomarker, i.e. F2-isoprostanes, we investigate the effect of melatonin on diquat-induced lipid peroxidation in Fischer 344 rats. When diquat (40 mg/kg body weight) was intraperitoneally injected into rats, the levels of liver F2-isoprostanes were significantly increased at 1, 3, and 6 hr while plasma free F2-isoprostanes concentrations were augmented at 3, 6, and 12 hr after administration of the toxin. In addition, the plasma alanine aminotransferase activity level was measured as a parameter of hepatoxicity; the activity of this enzyme was augmented at 3, 6, and 12 hr after diquat administration when compared with levels of this constituent in untreated control rats. Pretreatment with melatonin (20 mg/kg) 30 min before diquat administration resulted in a significant reduction in both tissue and plasma F2-isoprostanes levels, and plasma alanine aminotransferase activity. These findings, using a sensitive and specific index of lipid peroxidation, show that the hepatoxicity of diquat, at least partially, is a consequence of reactive oxygen species-induced lipid damage. Melatonin's protective effects likely relate to its direct free radical scavenging ability and/or due to other antioxidative processes induced by the indole.

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