Stratospheric Mean Ages and Transport Rates from Observations of Carbon Dioxide and Nitrous Oxide

Measurements of stratospheric carbon dioxide (CO2) and nitrous oxide (N2O) concentrations were analyzed to investigate stratospheric transport rates. Temporal variations in tropospheric CO2 were observed to propagate into the stratosphere, showing that tropospheric air enters the lower tropical stratosphere continuously, ascends, and is transported rapidly (in less than 1 month) to both hemispheres. The mean age A of stratospheric air determined from CO2 data is approximately 5 years in the mid-stratosphere. The mean age is mathematically equivalent to a conserved tracer analogous to exhaust from stratospheric aircraft. Comparison of values for A from models and observations indicates that current model simulations likely underestimate pollutant concentrations from proposed stratospheric aircraft by 25 to 100 percent.     

Pentaborate Polyanion in the Crystal Structure of Ulexite, NaCaB5O6(OH)6{middle dot}5H2O

Triclinic ulexite crystals contain isolated borate polyanions [B(5)O(6)(OH)(6)](3-) related to the well known pentaborate polyanion [B(5)O(6)(OH)(4)](-) by addition of two hydroxyl groups to two opposite B-O triangles. The isolated ulexite polyanions form the [B(5)O(7)(OH)(4)](n)(3n-) chains previously found in crystals of the related mineral probertite, NaCaB(5)O(7)(OH)(4).3H(2)O.     

Naturally occurring viral infections inSolanum brevidens andS. fernandezianum

Summary Two species of wild potato,S. brevidens andS. fernandezianum, were surveyed for six potato-infecting viruses in their natural habitats in the Puerto Montt Region and Robinson Crusoe Island of Chile, respectively. Potato viruses S (PVS), M (PVM) and X (PVX) and potato yellowing virus (PYV) were found in some clones of the Chilean Potato Germplasm Collection, whereas only one population ofS. brevidens out of six was virus-infected, namely by PVS. The cultivated potatoes on Robinson Crusoe Island were infected by PVS, PVM and PVX and infested byAulacorthum solani andMyzus persicae, whereasS. fernandezianum was infected by PYV and infested byA. circumflexum, A. solani andAphis spp.     

应用GAR-HRP进行甘薯病毒NCM-ELISA检测试验

分别采用辣根过氧化物酶标记的羊抗兔抗体 (GAR -HRP)和碱性磷酸酯酶标记的羊抗兔抗体(GAR -AP) ,对甘薯羽状斑驳病毒 (SPFMV)、甘薯潜隐病毒 (SPLV)、甘薯轻斑驳病毒 (SPMMV)及甘薯褪绿病毒(SPCFV)进行NCM -ELISA检测 ,结果表明 ,采用GAR -HRP进行NCM -ELISA检测对于SPFMV、SPLV、SPM MV、SPCFV同样有效 ,且特异性高 ,重现性好 ,在某些方面优于GAR -AP。对于国内危害甘薯的SPFMV、SPLV等主要病毒 ,采用GAR -HRP进行ELISA检测更加经济有效 ,是切实可行的     

Alzheimer's disease: insolubility of partially purified paired helical filaments in sodium dodecyl sulfate and urea

A method is described for the partial purification of the paired helical filaments that accumulate progressively in human neurons in Alzheimer's disease (senile dementia). Paired helical filaments have unusual solubility characteristics, including insolubility in sodium dodecyl sulfate, urea, reducing agent, and guanidine, which prevent analysis of their molecular composition by gel electrophoresis. The paired helical filaments appear to contain covalent bonds other than disulfide, which cross-link individual filaments into a rigid intracellular polymer. Thus, paired helical filaments appear to represent an example in neurons of an insoluble cross-linked protein. Covalently cross-linked protein polymers occur in lens senile cataracts and in terminally differentiated skin keratinocytes, suggesting that there may be a common mechanism for remodeling some structural proteins during cell aging.     

Global mammal conservation: what must we manage?

We present a global conservation analysis for an entire "flagship" taxon, land mammals. A combination of rarity, anthropogenic impacts, and political endemism has put about a quarter of terrestrial mammal species, and a larger fraction of their populations, at risk of extinction. A new global database and complementarity analysis for selecting priority areas for conservation shows that approximately 11% of Earth's land surface should be managed for conservation to preserve at least 10% of terrestrial mammal geographic ranges. Different approaches, from protection (or establishment) of reserves to countryside biogeographic enhancement of human-dominated landscapes, will be required to approach this minimal goal.     

Effect of temperature and water variables on the juvenile growth of lucerne and red clover

Plants of three cultivars of lucerne ( Medicago sativa L.) and of red clover ( Trifolium pratense L.) were grown at four levels each of water availability and temperature in all combinations to evaluate these factors as determinants of plant growth. Plants grew in conventional plant growth chambers from age 2 to 4 weeks with the roots held between layers of polyester cloths that held a volume of nutrient solution which was adjusted at 24-h intervals by flushing and blotting the cloths. The experimental design consisted of two growth chamber runs at each of four temperatures. Within each run, water treatments and the species-cultivar combination were arranged In four replicates of a split-plot design with water treatment as whole plot and species-cultivars as subplots.
Plant response variables over all treatments were significant (P < 0·05) for temperature and water for shoot weights, root weights, shoot/root ratios and number of roots. Cultivars within species had no significant difference in response lo the treatments, but species differences were significant for alt response variables except shoot/root ratio.