Homeotic transformation of the occipital bones of the skull by ectopic expression of a homeobox gene.

Murine Hox genes have been postulated to play a role in patterning of the embryonic body plan. Gene disruption studies have suggested that for a given Hox complex, patterning of cell identity along the antero-posterior axis is directed by the more 'posterior' (having a more posterior rostral boundary of expression) Hox proteins expressed in a given cell. This supports the 'posterior prevalence' model, which also predicts that ectopic expression of a given Hox gene would result in altered structure only in regions anterior to its normal domain of expression. To test this model further, we have expressed the Hox-4.2 gene more rostrally than its normal mesoderm anterior boundary of expression, which is at the level of the first cervical somites. This ectopic expression results in a homeotic transformation of the occipital bones towards a more posterior phenotype into structures that resemble cervical vertebrae, whereas it has no effect in regions that normally express Hox-4.2. These results are similar to the homeotic posteriorization phenomenon generated in Drosophila by ectopic expression of genes of the homeotic complex HOM-C (refs 7-10; reviewed in ref. 3).     

Rab protein evolution and the history of the eukaryotic endomembrane system

Spectacular increases in the quantity of sequence data genome have facilitated major advances in eukaryotic comparative genomics. By exploiting homology with classical model organisms, this makes possible predictions of pathways and cellular functions currently impossible to address in intractable organisms. Echoing realization that core metabolic processes were established very early following evolution of life on earth, it is now emerging that many eukaryotic cellular features, including the endomembrane system, are ancient and organized around near-universal principles. Rab proteins are key mediators of vesicle transport and specificity, and via the presence of multiple paralogues, alterations in interaction specificity and modification of pathways, contribute greatly to the evolution of complexity of membrane transport. Understanding system-level contributions of Rab proteins to evolutionary history provides insight into the multiple processes sculpting cellular transport pathways and the exciting challenges that we face in delving further into the origins of membrane trafficking specificity.     

Long‐Term Forecasting of Global Carbon Dioxide Emissions: Reducing Uncertainties Using a Per Capita Approach

Global CO₂ emission forecasts span such a wide range as to yield little guidance for climate policy and analysis. But global per capita emissions appear to be better constrained than total emissions, which we argue has an economic justification. Trend stationarity of per capita emissions may provide a means of characterizing the relative likelihood of global forecasts. On data spanning 1950 to 2009 a unit root hypothesis allowing for endogenous structural breaks is rejected, but adding in the 2010 observation pushes the p‐value slightly over 0.1. Since structural breaks cannot be detected at the end of sample this may simply indicate a power problem. Using Monte Carlo simulations we conclude that the lower half of a well‐known suite of IPCC emission scenarios is more likely to occur than the upper half, and the top quartile is particularly difficult to justify. Copyright © 2013 John Wiley & Sons, Ltd.     

Conservation status of threatened fishes in Warner Basin, Oregon

Two federally listed fishes, the Foskett speckled dace and Warner sucker, are endemic to Warner Basin in south central Oregon. The Foskett speckled dace is native only to a single spring in Coleman Valley. A nearby spring was stocked with dace in 1979 and 1980, and now provides a second population. The present numbers of dace probably are at their highest levels since settlement of the region. The Warner sucker historically occurred throughout much of the Warner Valley, but its distribution and abundance have been reduced by construction of reservoirs and irrigation dams and the introduction of predatory game fishes. Lentic habitats have become dominated by introduced fishes, particularly white crappie, black crappie, and brown bullhead. The largest remaining population of Warner suckers occurs in Hart Lake, where successful reproduction was documented but there is no evidence of recruitment to the adult population.     

A 4000-year record of woodland vegetation from Wind River Canyon, central Wyoming

Plant macrofossil analyses of 16 radiocarbon-dated woodrat middens spanning the past 4000 years from the Wind River Canyon region in central Wyoming provide information concerning late Holocene development of juniper woodlands. The study sites are currently dominated by Juniperus osteosperma , with J. scopulorum present locally. Woodlands in the region were dominated by J. scopulorum from ca 4000 yr BP until at least 2800 yr BP. Juniperus osteosperma invaded and expanded before 2000 yr BP. This expansion fits a regional pattern of J. osteosperma colonization and expansion in north central Wyoming during a relatively dry period between 2800 and 1000 yr BP. At the time the Wind River Canyon region was colonized by J. osteosperma , the species had populations 50-100 km to both the north and south. Long-distance seed dispersal was required for establishment in the study area. Genetic studies are necessary to identify source populations and regions.     

Habitat characteristics of leatherside chub ( Gila copei ) at two spatial scales

Populations of leatherside chub ( Gila copei ), a little-known species native to the eastern Great Basin, have declined and their distribution has become fragmented. To determine habitat requirements and possible factors responsible for population decline, we quantified macrohabitats and microhabitats occupied by leatherside chub. Macrohabitat was surveyed at 59 sites in the Sevier River drainage of south central Utah, and microhabitats occupied by leatherside chub were measured at 3 locations spanning the species latitudinal range. Characteristics of points in the stream where leatherside chub occurred were compared to points where they did not occur. Abundance of brown trout ( Salmo trutta ) and elevation were weakly negatively correlated with leatherside chub distribution on a macrohabitat scale. Microhabitats occupied by leatherside chub were characterized by low water velocities (2.5-45 cm sec -1 ), intermediate water depths (25-65 cm), and low percent composition of sand-silt or gravel substrates. This study suggests that the presence of introduced brown trout may have led to the decline of leatherside chub.     

Inhibition of ovulation in rats by antagonists to serotonin and by a new tricyclic compound.

The ovulation inhibiting activity in adult rats of the 5HT-antagonists cyproheptadine, mianserin and methysergide is shown. Furthermore the activity of a newly synthetized Cycloheptathiophenederivative, compound 26-921, which inhibits LH-secretion and consequently ovulation, is described.     

Generation of a functional mammary gland from a single stem cell

The existence of mammary stem cells (MaSCs) has been postulated from evidence that the mammary gland can be regenerated by transplantation of epithelial fragments in mice. Interest in MaSCs has been further stimulated by their potential role in breast tumorigenesis. However, the identity and purification of MaSCs has proved elusive owing to the lack of defined markers. We isolated discrete populations of mouse mammary cells on the basis of cell-surface markers and identified a subpopulation (Lin-CD29hiCD24+) that is highly enriched for MaSCs by transplantation. Here we show that a single cell, marked with a LacZ transgene, can reconstitute a complete mammary gland in vivo. The transplanted cell contributed to both the luminal and myoepithelial lineages and generated functional lobuloalveolar units during pregnancy. The self-renewing capacity of these cells was demonstrated by serial transplantation of clonal outgrowths. In support of a potential role for MaSCs in breast cancer, the stem-cell-enriched subpopulation was expanded in premalignant mammary tissue from MMTV-wnt-1 mice and contained a higher number of MaSCs. Our data establish that single cells within the Lin-CD29hiCD24+ population are multipotent and self-renewing, properties that define them as MaSCs.