Broad phylogenomic sampling improves resolution of the animal tree of life

Long-held ideas regarding the evolutionary relationships among animals have recently been upended by sometimes controversial hypotheses based largely on insights from molecular data. These new hypotheses include a clade of moulting animals (Ecdysozoa) and the close relationship of the lophophorates to molluscs and annelids (Lophotrochozoa). Many relationships remain disputed, including those that are required to polarize key features of character evolution, and support for deep nodes is often low. Phylogenomic approaches, which use data from many genes, have shown promise for resolving deep animal relationships, but are hindered by a lack of data from many important groups. Here we report a total of 39.9 Mb of expressed sequence tags from 29 animals belonging to 21 phyla, including 11 phyla previously lacking genomic or expressed-sequence-tag data. Analysed in combination with existing sequences, our data reinforce several previously identified clades that split deeply in the animal tree (including Protostomia, Ecdysozoa and Lophotrochozoa), unambiguously resolve multiple long-standing issues for which there was strong conflicting support in earlier studies with less data (such as velvet worms rather than tardigrades as the sister group of arthropods), and provide molecular support for the monophyly of molluscs, a group long recognized by morphologists. In addition, we find strong support for several new hypotheses. These include a clade that unites annelids (including sipunculans and echiurans) with nemerteans, phoronids and brachiopods, molluscs as sister to that assemblage, and the placement of ctenophores as the earliest diverging extant multicellular animals. A single origin of spiral cleavage (with subsequent losses) is inferred from well-supported nodes. Many relationships between a stable subset of taxa find strong support, and a diminishing number of lineages remain recalcitrant to placement on the tree.     

微生物让食物更美味

正早在公元前3000多年,酸奶就已诞生。随着人们巧妙地利用有益微生物加工制造发酵食品种类的不断增加,人类的饮食生活也因这些具有独特风味的食物而更加多姿多彩对我来说,最好吃的食物往往都有一些奇怪的味道:黄瓜虽然很好吃,但当我想找点什么塞进三明治的时候,腌黄瓜才是我的第一选择。平淡无味的白菜腌成泡菜就变得美味多滋,而蓝奶酪毋庸置疑比普通的奶酪更有味道。毛豆?算了吧,味噌汤加一小杯清酒,似乎更对我的胃口。是什么让这些食物变得更加鲜美可口的?答案是细菌和真菌。食品科学作家哈罗德·麦基指出,我们的食     

Linear and threshold forecasts of output and inflation using stock and housing prices

This study examines whether simple measures of Canadian equity and housing price misalignments contain leading information about output growth and inflation. Previous authors have generally found that the information content of asset prices in general, and equity and housing prices in particular, are unreliable in that they do not systematically predict future economic activity or inflation. However, earlier studies relied on simple linear relationships that would fail to pick up the potential nonlinear effects of asset price misalignments. Our results suggest that housing prices are useful for predicting GDP growth, even within a linear context. Meanwhile, both stock and housing prices can improve inflation forecasts, especially when using a threshold specification. These improvements in forecast performance are relative to the information contained in Phillips‐curve type indicators for inflation and IS‐curve type indicators for GDP growth. Copyright © 2008 John Wiley & Sons, Ltd.     

Nonresponse of native cottonwood trees to water additions during summer drought

Studies have demonstrated that some riparian trees may switch their reliance on surface soil water (unsaturated or vadose zone) to groundwater (saturated zone) sources during the growing season in association with changes in moisture availability. A closely related question is: How do these trees respond to pulse increases in water availability in previously dry zones? We tested the whole-tree physiological response of 6 natural Populus genotypes to water additions during the peak of summer drought in northern Utah, USA. We found clear evidence that trees were insensitive to water additions to the surface soil that were twice the magnitude of whole-tree transpiration rates. Our results suggest that some cottonwoods may have little immediate transpiration or leaf conductance response to pulse soil moisture increases. This lack of response may be related to a water-use strategy associated with regional climate patterns (i.e., genetic or environmental programming), cavitation recovery, or other physical determinants of water use such as depth to groundwater. Our data suggest that it is important to consider potential nonresponsiveness to changes in soil water availability when evaluating the impact of climate change on these important and productive ecosystems.     

Hispid cotton rat ( Sigmodon hispidus ) in Nebraska: distribution, reproduction, and seasonal activity

The hispid cotton rat ( Sigmodon hispidus ) has occurred in Nebraska for about 50 years and entered the state from the south via northward movements through Kansas. However, little is known about its status or distribution in the state in recent decades. We conducted surveys for S. hispidus in southern Nebraska at historical sites and sites without previous records to determine its current status. From 2004 to 2008, we documented cotton rats at 9 of 12 historical sites in south-central and extreme southeastern parts of the state, and we captured this species at 13 new sites in southwestern and south-central Nebraska. In the past 3 decades, the distribution of S. hispidus has expanded westward but not northward in the state. An explanation for such a shift is unclear. At this northern edge of its geographical range, pregnant females were captured from early April to early October, and nonreproductive females were captured from November to January. Males with enlarged testes occurred from late March to September. Aspects of its natural history in Nebraska are similar to those reported in Kansas.     

Rsx is a metatherian RNA with Xist-like properties in X-chromosome inactivation

In female (XX) mammals, one of the two X chromosomes is inactivated to ensure an equal dose of X-linked genes with males (XY). X-chromosome inactivation in eutherian mammals is mediated by the non-coding RNA Xist. Xist is not found in metatherians (marsupials), and how X-chromosome inactivation is initiated in these mammals has been the subject of speculation for decades. Using the marsupial Monodelphis domestica, here we identify Rsx (RNA-on-the-silent X), an RNA that has properties consistent with a role in X-chromosome inactivation. Rsx is a large, repeat-rich RNA that is expressed only in females and is transcribed from, and coats, the inactive X chromosome. In female germ cells, in which both X chromosomes are active, Rsx is silenced, linking Rsx expression to X-chromosome inactivation and reactivation. Integration of an Rsx transgene on an autosome in mouse embryonic stem cells leads to gene silencing in cis. Our findings permit comparative studies of X-chromosome inactivation in mammals and pose questions about the mechanisms by which X-chromosome inactivation is achieved in eutherians.     

Variation in the life history and abundance of three popluations of Bruneau hot springsnails ( Pyrgulopsis bruneauensis )

Bruneau hot springsnail density, size class structure, recruitment, and mortality were measured monthly over approximately 2 years and compared to environmental variables at 3 hot spring sites in southwestern Idaho. Food resources (attached algae) and water chemistry were similar among sites, but temperature, population density, and size structure differed significantly. Density was highest at a warm, fairly constant temperature site. A cooler, highly variable temperature site and a site where temperatures frequently approached or exceeded thermal maxima tolerance limits had lower densities. Size class structure varied seasonally and distinctly among sites, with recruitment occurring year-round at temperatures < 36°C. Mortality affected different size classes at different sites, with smaller snails incurring greatest mortality at site 3 (highest temperature variability). Growth rates were positively correlated with temperatures up to 36° C. Mean snail size differed among sites and also appeared to be related to temperature, with the variable temperature sites having larger snails. Although these snail populations are found in a range of water temperatures, they appear best adapted to springs with mean temperatures between 32° and 33°C and low thermal variance.     

REDUCING FIBER LOSS IN LABORATORY-AND MILL-SCALE FLOTATION DEINKING USING SURFACTANT SPRAY TECHNOLOGY

INTRODUCTIONDuring the past few years, the use of recycled fiber has increased dramatically due to the shortage of fiber resources and restrictive environmental regulations on paper landfills. Since the successful application of flotation in the paper recycling industry from the minerals industry in 1980s, flotation deinking has become a necessary process for ink removal from wastepaper in many paper recycling mills. The deinking chemistry and the physicochemical interactions among air bub…     

Trend analysis shows decline of an endangered thermophilic springsnail ( Pyrgulopsis bruneauensis ) in southwestern Idaho

We analyzed population trend data during 1991–2004 for the Bruneau hot springsnail ( Pyrgulopsis bruneauensis ) from rangewide hot spring surveys completed along 4 km of Bruneau River. The objectives of this study were to analyze population trends and assess other measured parameters, such as water temperature, specific conductance, and groundwater decline, for changes that may influence population trends. We used simple linear regression to determine significant relationships between measured parameters. Total numbers of hot springs surveyed in the 4-km reach are declining at a rate of ～5 hot springs per year, and numbers of hot springs containing P. bruneauensis in the same reach are declining at a rate of 3.75 per year. We found that the decline of hot springs with and without P. bruneauensis was significantly related to the decline of the thermal aquifer which underlies this area.