Will the Three Gorges Dam affect the underwater light climate of <Emphasis Type="Italic">Vallisneria spiralis</Emphasis> L. and food habitat of Siberian crane in Poyang Lake?

Almost 95% of the entire population of the Siberian crane (Grus leucogeranus) winter in Poyang Lake, China, where they forage on the tubers of the submerged aquatic macrophyte Vallisneria spiralis. The Three Gorges Dam on the Yangtze River may possibly affect this food source of the Siberian crane by affecting the light intensity reaching the top of the V. spiralis canopy. In this study, the photosynthetically active radiation at the top of the V. spiralis canopy (PAR_tc) in Lake Dahuchi was modeled from 1998 to 2006, and the potential impacts of changes in water level and turbidity on the underwater light climate of V. spiralis were analyzed. PAR_tc was calculated from incident irradiance while the losses due to reflection at the water surface, absorption, and scattering within the water column were taken into consideration. The results indicated significant differences in PAR_tc between years. Six years of water level and Secchi disk depth records revealed a seasonal switching of the lake from a turbid state at low water levels in autumn, winter, and spring to a clear state at high water levels during the monsoon in summer. The highest PAR_tc occurred at intermediate water levels, which were reached when the Yangtze River forces Lake Dahuchi out of its turbid state in early summer and the water becomes clear. The intended operation of the Three Gorges Dam, which will increase water levels in May and June, may advance the moment when Lake Dahuchi switches from turbid to clear. We suggest that this might increase production of V. spiralis and possibly improve the food habitat conditions for wintering Siberian crane in Poyang Lake.

Suitability evaluation of some specific crops in Souma area (Iran), using Cervatana and Almagra models

In the present study Cervatana and Almagra models from decision support system, MicroLEIS DSS, were applied to segregation of arable land surfaces from the marginal ones and suitability evaluation of wheat (Triticum aestivum), maize (Zea mays) and alfalfa (Medicago sativa) in Souma area with approximately 4100 ha extension in West Azarbaijan. Obtained results from both models are presented and discussed in this research work. Soil morphological and analytical data were collected from 35 soil profiles, representative of the study area and stored in SDBm plus database. The control or vertical section of soil for applying and running the models for annual selected crops, was calculated by soil layer generator 0.0–50 cm in depth, or between the surface and the limit of useful depth when the latter is between 0.0 and 50 cm. According to results, 80.49% of the total area was good capable for agricultural uses and 19.51% must be reforested and not dedicated to agriculture. The lands with good capability for agricultural uses is classified as highly suitable area (S2) for wheat, maize and alfalfa, but results in 822 ha for maize and in 126 ha for alfalfa refers to an excellent suitable (S1) and moderately suitable (S3) classes respectively. The most important limitation factors are soil texture and carbonate alone or together and maize — wheat — alfalfa can be selected as the best crop rotation. A simple map subsystem (ArcView GIS) was used for basic data and models result demonstration on a map.     

Effects of Top‐Soil Preparation and Broad‐Leaved Tree Mixture on Carabid Beetles in Afforested Fallow Plots

A 2‐year study to evaluate the effect of four soil preparation techniques and four species compositions in a pine plantation with an admixture of broad‐leaved trees on the species diversity and structure of ground beetle assemblages (Carabidae) was conducted. The soil preparation techniques were full shallow agricultural plowing (25 cm deep with three variants—plowing, plowing with ridge formation, and plowing with subsoiling) and full deep plowing (50 cm deep). The plantation species compositions were pine 7000/hectare, pine 5500/hectare + broad‐leaved species 1500/hectare, pine 4000/hectare + broad‐leaved species 3000/hectare, and pine 2000/hectare + broad‐leaved species 5000/hectare. Carabidae were sampled monthly with pitfall traps in the plantation from May to November in 2003 and 2004—the fourth and fifth years after afforestation. Only the soil preparation technique affected species diversity. The mean number of carabid species and the Shannon–Wiener index were higher in the case of the full agriculture plowing with subsoiling treatment and the full agriculture plowing with ridge formation than in the full shallow agriculture plowing. The structure of the assemblages was dependent on the soil preparation technique, but not on tree species composition. In general, deep plowing and shallow plowing with subsoiling were conducive to an increase in the proportion of individuals representing late succession species, whereas shallow plowing favored early succession species. The results suggest that for effective plantation of a managed stand, deep plowing or shallow plowing with subsoiling is more beneficial for afforestation of fallow fields than typical shallow agricultural plowing.     

Transfer of the chromosomally encoded tetracycline resistance gene <Emphasis Type="Italic">tet</Emphasis>(M) from marine bacteria to <Emphasis Type="Italic">Escherichia coli</Emphasis> and <Emphasis Type="Italic">Enterococcus faecalis</Emphasis>

The transferability of the tetracycline (TC) resistance gene tet(M) from marine bacteria to human enteric bacteria was examined by a filter-mating method. Vibrio spp., Lactococcus garvieae, Bacillus spp., Lactobacillus sp., and Paenibacillus sp. were used as donors, and Escherichia coli JM109 and Enterococcus faecalis JH2-2 were used as recipients. The combination of Vibrio spp. and E. coli resulted in 5/68 positive transconjugants with a transfer rate of 10⁻⁷ to 10⁻³; however, no transfer was observed with E. faecalis. In case of L. garvieae and E. faecalis, 6/6 positive transconjugants were obtained with a transfer rate of 10⁻⁶ to 10⁻⁵; however, no transfer was observed with E. coli. The tet(M) gene of Bacillus, Lactobacillus, and Paenibacillus were not transferred to either E. coli or E. faecalis. tet(M) transfer was confirmed in positive E. coli and E. faecalis transconjugants by polymerase chain reaction (PCR) and Southern hybridization. All the donor strains did not harbor plasmids, while they all harbored transposon Tn916. In the transconjugants, the transposon was not detected by PCR, suggesting the possible transfer of tet(M) from the marine bacterial chromosome to the recipient chromosome. This is the first report to show that tet(M) can be transferred from marine bacteria to human enteric bacteria in a species-specific manner.     

Post-synthetic acetylation of HMGB1 protein modulates its interactions with supercoiled DNA

High mobility group box (HMGB) proteins 1 and 2 are abundant non-histone nuclear proteins that regulate chromatin structure because of their structure-specific binding to DNA. Here, we have investigated how the post-synthetic acetylation of HMGB1 affects its interaction with negatively supercoiled DNA by employing monoacetylated at Lys2 protein, isolated from butyrate-treated cells. Our data reveal that this modification enhances three reaction parameters: binding affinity, supercoiling activity and capacity to protect the supercoiled DNA from relaxation by topoisomerase I. We show that monoacetylation at Lys2 mimics the effect of acidic tail removal but to a lesser extent thus demonstrating that in vivo acetylated HMGB1 is capable of modulating its interaction with negatively supercoiled DNA.     

Stability and structural constraints of random brain networks with excitatory and inhibitory neural populations

The stability of brain networks with randomly connected excitatory and inhibitory neural populations is investigated using a simplified physiological model of brain electrical activity. Neural populations are randomly assigned to be excitatory or inhibitory and the stability of a brain network is determined by the spectrum of the network’s matrix of connection strengths. The probability that a network is stable is determined from its spectral density which is numerically determined and is approximated by a spectral distribution recently derived by Rajan and Abbott. The probability that a brain network is stable is maximum when the total connection strength into a population is approximately zero and is shown to depend on the arrangement of the excitatory and inhibitory connections and the parameters of the network. The maximum excitatory and inhibitory input into a structure allowed by stability occurs when the net input equals zero and, in contrast to networks with randomly distributed excitatory and inhibitory connections, substantially increases as the number of connections increases. Networks with the largest excitatory and inhibitory input allowed by stability have multiple marginally stable modes, are highly responsive and adaptable to external stimuli, have the same total input into each structure with minimal variance in the excitatory and inhibitory connection strengths, and have a wide range of flexible, adaptable, and complex behavior.