Buddhist monasteries facilitated landscape conservation on the Qinghai-Tibetan Plateau

Landscape Ecology - The Sanjiangyuan region of the Qinghai-Tibetan Plateau—also known as the “Three Rivers’ Headwaters”—is the origin of the Yellow, Yangtze, and...     

Dynamic expression pattern of corticotropin-releasing hormone,urotensin I and II genes under acute salinity and temperature challenge during early development of zebrafish

Corticotropin-releasing hormone (CRH), urotensin I (UI) and urotensin II (UII) are found throughout vertebrate species from fish to human. To further understand the role of crh, uI and uII in teleosts during development, we investigated the expression pattern of crh, uI, uIIα and uIIβ genes, and their response to acute salinity and temperature challenge during early development of zebrafish, Danio rerio. The results reveal that crh, uI, uIIα and uIIβ mRNA are detected from 0hpf, and the expression levels increase to a maximum at 6 days post fertilization (dpf), with the exception of uIIα that peak at 5dpf. Exposure of zebrafish embryos and larvae to acute osmotic (30ppt) stress for 15 min failed to modify expression levels of crh, uI, uIIα and uIIβ mRNA from levels in control fish except at 6dpf when uIIα and uIIβ were significantly (P < 0.05) modified. Exposure of embryos and larvae to a cold (18 °C) or hot stress (38 °C) generally down-regulated mRNA levels of crh, uI, uIIα and uIIβ apart from at 3dpf. The results indicate that the contribution of crh, uI, uIIα and uIIβ genes to the stress response in zebrafish may be stressor-specific during early development. Overall, the results from this study provide a basis for further research into the developmental and stressor-specific function of crh, uI, uIIα and uIIβ in zebrafish.     

Combined effects of sodium chlorite dip treatment and chitosan coatings on the quality of fresh-cut d’Anjou pears

This study evaluated the effects of sodium chlorite (SC) alone and its sequential treatment with edible coatings on browning inhibition and quality maintenance of fresh-cut d’Anjou pears. Edible coatings were prepared from chitosan (CH) and its water-soluble derivative carboxymethyl chitosan (CMCH), separately. Pear wedges were immersed in SC solution, followed by coating with CH or CMCH solutions. The samples were packed in unsealed bags and stored at 4 °C for subsequent color, firmness, and weight loss measurement. The effects of the SC and coating treatments on polyphenol oxidase (PPO) inhibition and microbial inactivation were also evaluated. Results indicated that SC exhibited significant (P < 0.05) inhibition of browning and PPO activity. The SC treatment was also strongly effective in inactivating Escherichia coli O157:H7 on pear slices. Coating SC-treated pear slices with CH adversely affected the quality of pear slices by accelerating the discoloration of cut surfaces and increasing the PPO activity. On the contrary, coating SC-treated samples with CMCH significantly prevented the browning reaction and inhibited PPO activity. In addition, SC and CH/CMCH coatings maintained tissue firmness and did not affect weight loss. Our study may provide a scientific basis for the use of SC + CMCH treatment as an alternative preservation treatment for fresh-cut fruits and vegetables.     

帽儿山的潜在沟系分析及其应用

定义了潜在沟系的概念,并将帽儿山的潜在沟系分为平行沟、陡坡显沟和平坦沼泽三种类型。同时应用ARCVIEW GIS的空间分析系统对帽儿山的潜在沟系进行了计算,结果发现：帽儿山的潜在沟系与现有沟系图非常相似,而潜在沟系比现有沟系图更细致地刻画了帽儿山的沟系特征。     

Modeling the impact of alternative drainage practices in the northern Corn-belt with DRAINMOD-NII

The hydrologic and water quality impacts of subsurface drainage design and management practices are being investigated through field and simulation studies throughout the northern Corn-belt. Six years of data from an ongoing field study in south central Minnesota (Sands et al., 2008) were used to support a modeling effort with DRAINMOD-NII to investigate: (1) the performance of the model in a region where soils are subject to seasonal freeze-thaw and (2) the long-term hydrologic and water quality characteristics of conventional and alternative subsurface drainage practices. Post-calibration model prediction and efficiency were deemed satisfactory using standard model performance criteria. Prediction errors were primarily associated with early spring snowmelt hydrology and were attributed to the methods used for simulating snow accumulation and melting processes, in addition to potential sublimation effects on ET estimates. Long-term simulations with DRAINMOD-NII indicated that drainage design and/or management practices proposed as alternatives to conventional design may offer opportunities to reduce nitrate (NO₃)-nitrogen losses without significantly decreasing (and in some cases, increasing) crop yields for a Webster silty clay loam soil at Waseca, Minnesota. The simulation study indicated that both shallow drainage and controlled drainage may reduce annual drainage discharge and NO₃-nitrogen losses by 20-30%, while impacting crop yields from −3% (yield decrease) to 2%, depending on lateral drain spacing. The practice of increasing drainage intensity (decreasing drain spacing) beyond recommended values appears to not significantly affect crop yield but may substantially increase drainage discharge and nitrate-nitrogen losses to surface waters.