The 10 Australian ecosystems most vulnerable to tipping points

We identify the 10 major terrestrial and marine ecosystems in Australia most vulnerable to tipping points, in which modest environmental changes can cause disproportionately large changes in ecosystem properties. To accomplish this we independently surveyed the coauthors of this paper to produce a list of candidate ecosystems, and then refined this list during a 2-day workshop. The list includes (1) elevationally restricted mountain ecosystems, (2) tropical savannas, (3) coastal floodplains and wetlands, (4) coral reefs, (5) drier rainforests, (6) wetlands and floodplains in the Murray-Darling Basin, (7) the Mediterranean ecosystems of southwestern Australia, (8) offshore islands, (9) temperate eucalypt forests, and (10) salt marshes and mangroves. Some of these ecosystems are vulnerable to widespread phase-changes that could fundamentally alter ecosystem properties such as habitat structure, species composition, fire regimes, or carbon storage. Others appear susceptible to major changes across only part of their geographic range, whereas yet others are susceptible to a large-scale decline of key biotic components, such as small mammals or stream-dwelling amphibians. For each ecosystem we consider the intrinsic features and external drivers that render it susceptible to tipping points, and identify subtypes of the ecosystem that we deem to be especially vulnerable.     

沙棘叶水提物适应原性及安全性评价

本文评估了沙棘叶水提物在大白鼠体内的适应原活性和毒性.提取物的剂量依赖性适应原活性的研究采取将小鼠置于低温(5℃),低压(428mmHg),抑制(C-H-R)的环境下的30min前口服不同剂量的沙棘叶水提物.在亚急性毒性中,连续14d每天口服10倍和20倍最大有效剂量（每天口服1g/kg体重和2g/kg体重）和连续30...     

The amyloid beta protein gene is not duplicated in brains from patients with Alzheimer's disease

Complementary DNAs (cDNAs) encoding portions of the amyloid beta protein were used to investigate possible amyloid gene duplication in sporadic Alzheimer's disease. A strategy employing two Eco RI restriction fragment length polymorphisms (RFLPs) detected by the amyloid cDNAs was used. RFLPs allow the detection of a 2:1 gene dosage in the DNA of any individual who is heterozygous for a particular RFLP. The amyloid gene regions homologous to the cDNAs used were not duplicated in the DNA from brains of individuals with sporadic Alzheimer's disease. Similar results were also obtained with a strategy employing a test for 3:2 gene dosage.     

Lunar soil: size distribution and mineralogical constituents

The lunar soil collected by Apollo 11 consists primarily of submillimeter material and is finer in grain size than soil previously recorded photographically by Surveyor experiments. The main constituents are fine-grained to glassy rocks of basaltic affinity and coherent breccia of undetermined origin. Dark glass, containing abundant nickel-iron spheres, coats many rocks, mineral, and breccia fragments. Several types of homogeneous glass occur as fragments and spheres. Colorless spheres, probably an exotic component, are abundant in the fraction finer than 20 microns.     

Eradication of potato wart disease from Maryland

Potato wart disease, caused bySynchytrium endobioticum (Schilb.) Perc., is a disease of quarantine significance due to the production of persistent resting spores and lack of effective chemical control measures. The disease was present in limited areas of Pennsylvania, Maryland and West Virginia in 1918–1920 and was thought to have been eradicated by 1974. A recent survey in Maryland to verify eradication in that state had revealed the presence of resting spores of the fungus in one home garden in Allegany County. A subsequent delimiting soil sample survey was conducted in and around the old quarantine area in Allegany County. None of the soil samples from 176 home gardens surveyed were positive forS. endobioticum resting spores. Bioassays with susceptible potato cultivars were conducted for five consecutive years at the site from which spores had been recovered. During three of the five years, environmental conditions did not preclude development of disease, yet no symptoms were obtained. According to the USDA APHIS guidelines for eradication of potato wart disease, the spores at the Allegany County, Maryland site are declared nonviable and Maryland is considered to be free of the potato wart pathogen.