The landing of the NEAR-Shoemaker spacecraft on asteroid 433 Eros

The NEAR-Shoemaker spacecraft was designed to provide a comprehensive characterization of the S-type asteroid 433 Eros (refs 1,2,3), an irregularly shaped body with approximate dimensions of 34 x 13 x 13 km. Following the completion of its year-long investigation, the mission was terminated with a controlled descent to its surface, in order to provide extremely high resolution images. Here we report the results of the descent on 12 February 2001, during which 70 images were obtained. The landing area is marked by a paucity of small craters and an abundance of 'ejecta blocks'. The properties and distribution of ejecta blocks are discussed in a companion paper. The last sequence of images reveals a transition from the blocky surface to a smooth area, which we interpret as a 'pond'. Properties of the 'ponds' are discussed in a second companion paper. The closest image, from an altitude of 129 m, shows the interior of a 100-m-diameter crater at 1-cm resolution.     

Honeybee colonies achieve fitness through dancing

The honeybee dance language, in which foragers perform dances containing information about the distance and direction to food sources, is the quintessential example of symbolic communication in non-primates. The dance language has been the subject of controversy, and of extensive research into the mechanisms of acquiring, decoding and evaluating the information in the dance. The dance language has been hypothesized, but not shown, to increase colony food collection. Here we show that colonies with disoriented dances (lacking direction information) recruit less effectively to syrup feeders than do colonies with oriented dances. For colonies foraging at natural sources, the direction information sometimes increases food collected, but at other times it makes no difference. The food-location information in the dance is presumably important when food sources are hard to find, variable in richness and ephemeral. Recruitment based simply on arousal of foragers and communication of floral odour, as occurs in honeybees, bumble bees and some stingless bees, can be equally effective under other circumstances. Clarifying the condition-dependent payoffs of the dance language provides new insight into its function in honeybee ecology.     

The role of bHLH genes in ear development and evolution: revisiting a 10-year-old hypothesis

In mouse ear development, two bHLH genes, Atoh1 and Neurog1, are essential for hair cell and sensory neuron differentiation. Evolution converted the original simple atonal-dependent neurosensory cell formation program of diploblasts into the derived developmental program of vertebrates that generates two neurosensory cell types, the sensory neuron and the sensory hair cell. This transformation was achieved through gene multiplication in ancestral triploblasts resulting in the expansion of the atonal bHLH gene family. Novel genes of the Neurogenin and NeuroD families are upregulated prior to the expression of Atoh1. Recent data suggest that NeuroD and Neurogenin were lost or their function in neuronal specification reduced in flies, thus changing our perception of the evolution of these genes. This sequence of expression changes was accompanied by modification of the E-box binding sites of these genes to regulate different downstream genes and to form inhibitory loops among each other, thus fine-tuning expression transitions.     

Status and conservation of salmonids in relation to hydrologic integrity in the Greater Yellowstone Ecosystem

Native salmonid status was evaluated with an index quantifying distribution and abundance of cutthroat trout ( Oncorhynchus clarki ) and grayling ( Thymallus arcticus ) in 41 watersheds comprising the Greater Yellowstone Ecosystem. We assessed hydrologic integrity with a percentile-based index measuring cumulative effects of reservoirs, surface water withdrawals, and consumptive water use. Status of native salmonids was poor in 70% of the watersheds; exceptions occurred in a north-south core extending from the Upper Yellowstone southward through the national parks to Bear Lake. Hydrologic integrity was highest in headwater areas and lowest in lower-elevation watersheds. Status of native and nonnative salmonid populations currently existing in the ecosystem was positively correlated with hydrologic integrity ( r = 0.58), indicating that the hydrologic index performed well on a watershed scale in quantifying suitability of stream environments for salmonids. However, native trout status and hydrologic integrity were similarly correlated ( r = 0.63) only when watersheds receiving the lowest possible native salmonid index score were removed from analysis because these watersheds were uniformly distributed across hydrologic integrity. We infer that nonphysical factors such as interactions with introduced fish species have played an important role in the disappearance of native salmonids. The highest priority for conservation is preservation of core watersheds, where both hydrologic integrity and native trout status are high. Restoration opportunities exist in the Teton, Idaho Falls, Willow Creek, Central Bear, and Bear Lake watersheds, where viable cutthroat trout populations remain but are threatened by habitat degradation.     

Community response of nontarget species to herbicide application and removal of the nonindigenous invader Potentilla recta L

Our main objective was to improve understanding of herbicide effects on community dynamics to refine the use of technology and advance the development of ecologically based weed management strategies. We hypothesized that native grasslands would exhibit reductions in culturally sensitive forb cover, biomass, and density relative to the rate of application of selective rangeland herbicides, and that hand-removal of sulfur cinquefoil ( Potentilla recta L.) would increase indigenous species cover, biomass, density, species richness, and diversity. Treatments consisted of 3 rates each of 2,4-D + clopyralid (0.28 kg ai ? ha -1 + 0.0532 kg ai ? ha -1 , 0.56 kg ai ? ha -1 + 0.1064 kg ai ? ha -1 , 0.84 kg ai ? ha -1 + 0.1596 kg ai ? ha -1 ); 2,4-D amine (0.532 kg ai ? ha -1 , 1.064 kg ai ? ha -1 , 1.596 kg ai ? ha -1 ); metsulfuron (0.0042 kg ai ? ha -1 , 0.021 kg ai ? ha -1 , 0.032 kg ai ? ha -1 ); picloram (0.14 kg ai ? ha -1 , 0.28 kg ai ? ha -1 , 0.56 kg ai ? ha -1 ); and clopyralid (0.05025 kg ai ? ha -1 , 0.21 kg ai ? ha -1 , 0.42 kg ai ? ha -1 ). This experiment was replicated 3 times at 2 lateseral, noninfested sites in southeastern Montana. In a companion study, sulfur cinquefoil was removed adjacent to paired nonremoved controls in 5 replicates at 2 sites in 1-m 2 plots for 2 growing seasons. Canopy cover, density, and biomass were collected 24 months after initial treatment at all sites. Indigenous perennial grass cover and biomass increased with herbicide application; however, picloram, metsulfuron, and clopyralid reduced native forb density at 1 site, and picloram reduced forb cover at both sites regardless of rate. Effects of herbicides on species richness or diversity were not detected. Hand-removing sulfur cinquefoil increased total plant richness, especially that of native forbs. Restoring species richness and diversity may be difficult using selective broadleaf herbicides because key functional groups, such as forbs, appear to be at risk.     

Mutations in the gene encoding the PML nuclear body protein Sp110 are associated with immunodeficiency and hepatic veno-occlusive disease

We describe mutations in the PML nuclear body protein Sp110 in the syndrome veno-occlusive disease with immunodeficiency, an autosomal recessive disorder of severe hypogammaglobulinemia, combined T and B cell immunodeficiency, absent lymph node germinal centers, absent tissue plasma cells and hepatic veno-occlusive disease. This is the first report of the involvement of a nuclear body protein in a human primary immunodeficiency and of high-penetrance genetic mutations in hepatic veno-occlusive disease.     

从湿法烟气脱硫残渣制取α型半水硫酸钙的研究

作者提出一种处理烟气脱硫残渣的新方法。该法将脱硫残渣在硫酸溶液中转变为ＦＧＤ石膏，同时回收ＳＯ２。ＦＧＤ石膏在碱土金属盐类和硫酸的混合液中，于大气压下加热脱水生成α型半水硫酸钙。研究中发现酸浓度和温度是影响ＦＧＤ石膏脱水速度最敏感的因素；固液比虽然对脱水速度影响不大，但于晶体生长和习性改良不利；ｐＨ值愈接近中性范围，愈能增强α型半水结晶在液相中的稳定性，有利于结晶习性改良     

Lamin B1 duplications cause autosomal dominant leukodystrophy

Adult-onset autosomal dominant leukodystrophy (ADLD) is a slowly progressive neurological disorder characterized by symmetrical widespread myelin loss in the central nervous system, with a phenotype similar to chronic progressive multiple sclerosis. In this study, we identify a genomic duplication that causes ADLD. Affected individuals carry an extra copy of the gene for the nuclear laminar protein lamin B1, resulting in increased gene dosage in brain tissue from individuals with ADLD. Increased expression of lamin B1 in Drosophila melanogaster resulted in a degenerative phenotype. In addition, an abnormal nuclear morphology was apparent when cultured cells overexpressed this protein. This is the first human disease attributable to mutations in the gene encoding lamin B1. Antibodies to lamin B are found in individuals with autoimmune diseases, and it is also an antigen recognized by a monoclonal antibody raised against plaques from brains of individuals with multiple sclerosis. This raises the possibility that lamin B may be a link to the autoimmune attack that occurs in multiple sclerosis.