Elsholtzia splendens is a Cu-tolerant plant growing in copper mine areas in the south of China. In this study, X-ray absorption spectroscopy (XAS) was used to investigate the Cu speciation and biotransformation in E. splendens with 300 μM Cu treatment from 10 days to 60 days. The results showed that 300 μM Cu was phytotoxic to E. spendens. The Cu Kedge X-ray absorption near edge structure (XANES) revealed that most copper in roots, stems and leaves exists as divalent Cu. Cu speciation changed depending on the treatment time, but there was no unidirectional trend in roots, stems, and leaves. The percentages of potential Cu ligands in all samples were estimated by fitting the XANES spectra with linear combinations. Most Cu in roots, stems and leaves was bound with cell wall and histidine (His)-like ligands, while a minor proportion of the Cu was bound to oxalate and glutathione-like ligands. The fitting results of Cu K-edge extended X-ray absorption fine structure (EAXFS) showed that nitrogen/oxygen (N/O) ligands were dominant in roots, stems and leaves of the plant, while S ligands were rare. All these results suggest that Cu bound by N/O ligands plays a key role in Cu detoxification of E. splendens, and a role for classical metal-detoxifying S ligands, such as metallothioneins and phytochelatins, in Cu detoxification of E. splendens is not supported in the present study. Due to the phytotoxicity of 300 μM Cu to E. splendens, the question of whether S ligands play a significant role in Cu detoxification in E. splendens exposed to lower levels of Cu should be further studied.

A complex consisting of the EcoRI endonuclease site-specifically bound to spin-labeled DNA 26mers was prepared to provide a model system for studying possible conformational changes resulting from protein binding. EPR was used to monitor the mobility of the spin labels that were strategically placed in position 6, 9, or 11 with respect to the dyad axis of the 26mer. These positions are located within the flanking region on either side of the EcoRI hexamer binding site. This allows the monitoring of potential distal structural changes in the DNA helix caused by protein binding. The spectral line shapes indicate that the spin label closest to the EcoRI endonuclease binding site, i.e., in position 6, is most influenced by the binding event. The EPR data are analyzed according to a model that distinguishes between spectral effects due to a change in the hydrodynamic shape of the complex and those resulting from local variations in the spin-label mobility as characterized by a local order parameter S. S reflecting the motional restriction of the spin-labeled base is 0.20 +/- 0.01 for all three oligomers as well as for the two complexes with the label in position 9 or 11, while the position 6 labeled complex yields S = 0.25. To further evaluate the origin of the slightly larger EPR effect observed with position 6 labeled material, molecular dynamics (MD) simulations were used to explore the space accessible to the probes in positions 6, 9, and 11. MD results gave similar nitroxide trajectories for all three labeled 26mers in the absence or presence of EcoRI. Thus, the small position 6 effect is attributed to a structural distortion in the major groove of the DNA at this location possibly corresponding to a bend induced by protein binding. The observation that the spectral changes are small indicates the absence of any significant structural disruption being propagated along the helix as a result of protein binding. Also, the fact that the line shape of the 26mers did not change as expected from hydrodynamic theory in view of the significant increase in molecular volume upon protein binding suggests that there are additional relaxation processes involving the protein and nucleic acid.

ABSTRACT. Fenneropenaeus penicillatus is a widely distributed economically and ecologically important shrimp species, which is endangered in China. Sequence analysis of 16s rRNA and control region (CR) fragments from mitochondrial DNA was conducted to obtain information on genetic diversity and population structure. Individuals from 12 wild F. penicillatus populations located along the southeast coast of China were used. Polymerase chain reaction (PCR) fragments of the CR gene revealed high genetic diversity among the 12 populations; however, PCR fragments of the 16s rRNA gene revealed very low genetic diversity in the Hainan (HN) and Ningde (ND) populations and high genetic diversity in the DS, BH, PT, XM, and SZ populations. Data obtained from the CR and 16s rRNA genes suggested that high genetic differentiation exists among the 12 populations, which is mainly due to the high genetic differentiation between HN and all other 11 populations. These results may be useful for further sustainable management and utilization of this species.

ABSTRACT. Megalonibea fusca is a commercially important large edible fish. In this study, the first set of 10 polymorphic microsatellite loci for M. fusca was developed and characterized. The number of alleles per locus ranged from two to five, with the observed and expected heterozygosities ranging from 0.0667 to 0.7667, and from 0.0644 to 0.5828, respectively. Most of the loci were in HardyWeinberg equilibrium (P > 0.05), except for two loci (Mf25 and Mf30) after a Bonferroni's correction (P < 0.005). These informative microsatellite markers will be useful in further studies of the population and conservation genetics of this species.