Genomic sequencing of Pleistocene cave bears

Despite the greater information content of genomic DNA, ancient DNA studies have largely been limited to the amplification of mitochondrial sequences. Here we describe metagenomic libraries constructed with unamplified DNA extracted from skeletal remains of two 40,000-year-old extinct cave bears. Analysis of approximately 1 megabase of sequence from each library showed that despite significant microbial contamination, 5.8 and 1.1% of clones contained cave bear inserts, yielding 26,861 base pairs of cave bear genome sequence. Comparison of cave bear and modern bear sequences revealed the evolutionary relationship of these lineages. The metagenomic approach used here establishes the feasibility of ancient DNA genome sequencing programs.     

东北三省番茄叶霉病生理小种分化的初步研究

采用国际通用番茄叶霉病鉴别寄主谱，利用苗期人工喷雾接种方法，参照国外Ｎ·Ｈｕｂｂｅｌｉｎｇ氏叶霉病生理小种分化表（１９７１），仿照Ｐ．Ｄａｙ分类方法，对东北三省郊区大棚番茄叶霉病进行鉴定．结果表明．东北三省郊区大棚番茄叶霉病生理小种为小种１，２，３；小种１，３和小种３；而以小种１，２，３为主．     

Tracing the Movement of Irrigated Effluent into an Alluvial Gravel Aquifer

Three microbial tracers – Escherichia coli J6-2, a somatic coliphage (ØESR1) and endospores of Bacillus subtilis var. niger NCIB 8649 tracer strain JHI – were added to effluent flood irrigated onto border dyke strips at a sewage treatment plant near Christchurch, New Zealand. All three tracers, and three effluent indicators – faecal coliforms, F-RNA phages, and chloride – were recovered in a bore, approximately 100 m downstream. A simple spatial model was applied to the breakthrough curves (BTCs) in the bore, using a series of hypothetical “entry points” in the strips. This analysis indicated effluent transport velocities through the 16.8 m deep vadose zone of between 15.7 and 39.2 m hr^{? 1}. The shapes of the BTCs for the microorganisms and chloride were very different, suggesting that they reached the groundwater table via two pathways: – both underwent rapid transport to the groundwater though macropores, but chloride also underwent far slower (matrix) transport though micropores. The BTC shapes also suggested transport velocities in the vadose zone of E. coli J6-2 > B. subtilis JH1 endospores > phage ØESR1, which is consistent with the theory of pore size exclusion, based on particle size. Reductions in microbial concentrations were ≈100 times greater than for chloride, and occurred rapidly, suggesting that up to 99% of the microorganisms underwent early exclusion from macropore flow and were removed during matrix flow. Nevertheless, the results show that substantial numbers of bacteria and viruses will still reach the groundwater through macropores beneath effluent irrigation schemes located on alluvial gravel formations.     

Effects of Soil Matric Suction on Retention and Percolation of Bacillus Subtilis in Intact Soil Cores

Bacillus subtilis endospores (resistant to rifampicin) irrigated on the surface of intact soil cores (20 cm diameter × 8 cm length) which were equilibrated under selected suctions, i.e. 0, 0.5, 2, 5, 10 kPa, were then percolated by saturated water flow. The bacterial retention and percolation percentage were significantly correlated with the suctions. The higher retention with higher suction was explained by micropore storage, attachment to static air-water interface (AWI), and irreversible adsorption to soil particles. The bacterial percolation was mainly controlled by initial replacement of pore water storage, and following reversible detachment process. Another sensitivity experiment with four replicates using lincomycin-resistant B. subtilis at 0 and 0.5 kPa suctions revealed that small increase (0 to 0.5 kPa) in soil matric suction incurred a substantial higher level of bacterial retention. Based on our experimental results, soil matric suction was proposed as a comprehensive parameter to monitor bacterial transport and fate for animal waste disposal (irrigation) and subsurface bioremediation.     

Design of nondestructive examination system for bridge cables surface defect

Aiming at the drawbacks of the current detecting methods, a nondestructive examination system design for bridge cables based on high speed digital signal processors chip DM642 is presented, and the hardware platform of the system is built. This examination system mainly consists of four parts: the image defaults acquisition part, DM642 hardware platform, creeping part and defaults locating equipment. The designed system is tested on the hardware platform based on digital image processing algorithm. The experimental results show that the detecting system has the advantages of high stability and reliability, real time, mass storage, and nondestructive examination, etc. This system uses high technology and has significant meaning on detecting the current bridge cables health, furthermore, this method can be used in other examination fields.