Early detection of effects of acid deposition and automobile exhaust on young spruce [Picea abies (L.) Karst.] trees

Rooted spruce cuttings from three clones were sprayed daily with sulfuric acid at pH 2.5 for one month or treated with automobile exhaust for one hour. Foliage samples were extracted and analyzed by high performance liquid chromatography. Chromatographic peaks representing unidentified leaf constituents from treated and control trees were compared. Discriminant analysis indicated a weak but significant difference and Canonical discriminant analysis indicated clear differences between treatments and control. Similar differences were found between the three clones. Visible symptoms of damage were not evident even four months after treatment. This result is important because it demonstrates the possibility of using unidentified plant constituents to detect damage to plants even before visible symptoms appear.     

清华大学钟毅课题组阐明果蝇短期记忆遗忘机理

新获取的记忆如果未经强化记忆通常会很快遗忘,这种记忆遗忘被认为是由于新获取记忆本身的不稳定性或随后获取信息的干扰所造成的.近日,来自清华大学钟毅课题组的研究人员在这种短期记忆遗忘机理研究上取得重大进展,该研究认为这种快速遗忘是一种主动行为,用以抹掉旧的记忆腾出空间来存储新的记忆.相关研究结果于2010年2月19日发表在(Cell)杂志上,并被列为同期的特色文章(Featured Article).     

Fungal growth on a common wood substrate across a tropical elevation gradient: Temperature sensitivity, community composition, and potential for above-ground decomposition

Fungal breakdown of plant material rich in lignin and cellulose (i.e. lignocellulose) is of central importance to terrestrial carbon (C) cycling due to the abundance of lignocellulose above and below-ground. Fungal growth on lignocellulose is particularly influential in tropical forests, as woody debris and plant litter contain between 50% and 75% lignocellulose by weight, and can account for 20% of the C stored in these ecosystems. In this study, we evaluated factors affecting fungal growth on a common wood substrate along a wet tropical elevation gradient in the Peruvian Andes. We had three objectives: 1) to determine the temperature sensitivity of fungal growth - i.e. Q₁₀, the factor by which fungal biomass increases given a 10 °C temperature increase; 2) to assess the potential for above-ground fungal colonization and growth on lignocellulose in a wet tropical forest; and 3) to characterize the community composition of fungal wood decomposers across the elevation gradient. We found that fungal growth had a Q₁₀ of 3.93 (95% CI of 2.76-5.61), indicating that fungal biomass accumulation on the wood substrate nearly quadrupled with a 10 °C increase in temperature. The Q₁₀ for fungal growth on wood at our site is higher than Q₁₀ values reported for litter decomposition in other tropical forests. Moreover, we found that above-ground fungal growth on the wood substrate ranged between 37% and 50% of that measured in the soil, suggesting above-ground breakdown of lignocellulose represents an unexplored component of the C cycle in wet tropical forests. Fungal community composition also changed significantly along the elevation gradient, and Ascomycota were the dominant wood decomposers at all elevations. Fungal richness did not change significantly with elevation, directly contrasting with diversity patterns observed for plant and animal taxa across this gradient. Significant variation in fungal community composition across the gradient suggests that the characteristics of fungal decomposer communities are, directly or indirectly, influenced by temperature.     

MET amplification leads to gefitinib resistance in lung cancer by activating ERBB3 signaling

The epidermal growth factor receptor (EGFR) kinase inhibitors gefitinib and erlotinib are effective treatments for lung cancers with EGFR activating mutations, but these tumors invariably develop drug resistance. Here, we describe a gefitinib-sensitive lung cancer cell line that developed resistance to gefitinib as a result of focal amplification of the MET proto-oncogene. inhibition of MET signaling in these cells restored their sensitivity to gefitinib. MET amplification was detected in 4 of 18 (22%) lung cancer specimens that had developed resistance to gefitinib or erlotinib. We find that amplification of MET causes gefitinib resistance by driving ERBB3 (HER3)-dependent activation of PI3K, a pathway thought to be specific to EGFR/ERBB family receptors. Thus, we propose that MET amplification may promote drug resistance in other ERBB-driven cancers as well.     

Reclamation of Fine Fraction Bauxite Processing Residue (Red Mud) Amended with Coarse Fraction Residue and Gypsum

Establishment of vegetation on residues produced from the bauxite refining process is a beneficial part of their environmental management. Of the two fractions produced in the refining, the coarse fraction has greater efficiency in the leaching of excess salts and alkalinity. However, these same properties can result in increased loss of nutrients and low water-holding capacity. The current study investigated the use of mixing coarse fraction residue with fine fraction residue, at two different application rates (10% and 25%), with and without the use of gypsum as an ameliorant, for re-vegetation of the residue with Trifolium pratense. Optimum plant growth was observed in treatments that had also received gypsum amendment, with higher plant biomass, Mn nutrition and lower Al and Fe concentration. However, use of process sand at the higher application rate (25%) promoted lower levels of soluble Al and Fe and exchangeable Na in the substrate and, consequently, lower plant uptake of Na. Results indicate that co-disposal of the coarse fraction sand at 25% w/w with fine fraction residue can improve the substrate and, therefore, plant uptake and growth. Further monitoring is recommended to determine the effect of the absence of gypsum and other nutrient sources on plant growth.     

Ivermectin for the control of swine scabies: relative values of prefarrowing treatment of sows and weaning treatment of pigs

Ivermectin given in a single subcutaneous dose (300 micrograms/kg of body weight) was tested for activity against swine scabies (Sarcoptes scabiei). Efficacy was determined by recoveries of mites from ear scrapings and by observations of clinical signs. Treatment of infected sows 8 to 37 days before farrowing eliminated scabies from the sows and prevented its transmission to their offspring. Pigs farrowed by ivermectin-treated sows remained noninfected throughout the study regardless of whether they were treated with ivermectin at weaning. Placebo-treated sows remained infected and transmitted scabies to their offspring. Ivermectin treatment of pigs at weaning eliminated the infection, whereas placebo treatment did not. The placebo-treated pigs remained infected while in the nursery, but ivermectin treatment eliminated the infection when they were moved to the growing and finishing floor at 12 weeks of age. It appears that an effective control program for swine scabies using ivermectin could be based on a single treatment of the sows before farrowing. Any infection (epizootic) appearing in growing pigs could be controlled by a single treatment of all in-contact pigs.