The genome of the green anole lizard and a comparative analysis with birds and mammals

The evolution of the amniotic egg was one of the great evolutionary innovations in the history of life, freeing vertebrates from an obligatory connection to water and thus permitting the conquest of terrestrial environments. Among amniotes, genome sequences are available for mammals and birds, but not for non-avian reptiles. Here we report the genome sequence of the North American green anole lizard, Anolis carolinensis. We find that A. carolinensis microchromosomes are highly syntenic with chicken microchromosomes, yet do not exhibit the high GC and low repeat content that are characteristic of avian microchromosomes. Also, A. carolinensis mobile elements are very young and diverse-more so than in any other sequenced amniote genome. The GC content of this lizard genome is also unusual in its homogeneity, unlike the regionally variable GC content found in mammals and birds. We describe and assign sequence to the previously unknown A. carolinensis X chromosome. Comparative gene analysis shows that amniote egg proteins have evolved significantly more rapidly than other proteins. An anole phylogeny resolves basal branches to illuminate the history of their repeated adaptive radiations.     

Civil partnerships five years on

The Civil Partnership Act 2004, which came into force in December 2005 allowing same-sex couples in the UK to register their relationship for the first time, celebrated its fifth anniversary in December 2010. This article examines civil partnership in England and Wales, five years on from its introduction. The characteristics of those forming civil partnerships between 2005 and 2010 including age, sex and previous marital/civil partnership status are examined. These are then compared with the characteristics of those marrying over the same period. Further comparisons are also made between civil partnership dissolutions and divorce. The article presents estimates of the number of people currently in civil partnerships and children of civil partners. Finally the article examines attitudes towards same-sex and civil partner couples both in the UK and in other countries across Europe.     

Chronic high-fat diet in fathers programs β-cell dysfunction in female rat offspring

The global prevalence of obesity is increasing across most ages in both sexes. This is contributing to the early emergence of type 2 diabetes and its related epidemic. Having either parent obese is an independent risk factor for childhood obesity. Although the detrimental impacts of diet-induced maternal obesity on adiposity and metabolism in offspring are well established, the extent of any contribution of obese fathers is unclear, particularly the role of non-genetic factors in the causal pathway. Here we show that paternal high-fat-diet (HFD) exposure programs β-cell 'dysfunction' in rat F(1) female offspring. Chronic HFD consumption in Sprague-Dawley fathers induced increased body weight, adiposity, impaired glucose tolerance and insulin sensitivity. Relative to controls, their female offspring had an early onset of impaired insulin secretion and glucose tolerance that worsened with time, and normal adiposity. Paternal HFD altered the expression of 642 pancreatic islet genes in adult female offspring (P?相似文献   

The deubiquitinase USP9X suppresses pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) remains a lethal malignancy despite much progress concerning its molecular characterization. PDA tumours harbour four signature somatic mutations in addition to numerous lower frequency genetic events of uncertain significance. Here we use Sleeping Beauty (SB) transposon-mediated insertional mutagenesis in a mouse model of pancreatic ductal preneoplasia to identify genes that cooperate with oncogenic Kras(G12D) to accelerate tumorigenesis and promote progression. Our screen revealed new candidate genes for PDA and confirmed the importance of many genes and pathways previously implicated in human PDA. The most commonly mutated gene was the X-linked deubiquitinase Usp9x, which was inactivated in over 50% of the tumours. Although previous work had attributed a pro-survival role to USP9X in human neoplasia, we found instead that loss of Usp9x enhances transformation and protects pancreatic cancer cells from anoikis. Clinically, low USP9X protein and messenger RNA expression in PDA correlates with poor survival after surgery, and USP9X levels are inversely associated with metastatic burden in advanced disease. Furthermore, chromatin modulation with trichostatin A or 5-aza-2'-deoxycytidine elevates USP9X expression in human PDA cell lines, indicating a clinical approach for certain patients. The conditional deletion of Usp9x cooperated with Kras(G12D) to accelerate pancreatic tumorigenesis in mice, validating their genetic interaction. We propose that USP9X is a major tumour suppressor gene with prognostic and therapeutic relevance in PDA.     

Taxonomy: Sus bucculentus revisited

In 1997, the rediscovery of Sus bucculentus in Laos was announced by Groves et al.--this wild pig species had gone unrecorded since first being described in 1892. Although the identification of the new specimen was based initially on morphology, the authors also used a 7% sequence divergence from the common Eurasian pig S. scrofa (based on their analysis of 327 base pairs of the gene encoding mitochondrial 12S ribosomal RNA) as support for the species status of S. bucculentus. Concerned about the large divergence reported for a relatively conserved gene, and the absence of the sequence in any public database, we analysed an additional tissue sample from the specimen and found only 0.6% divergence from S. scrofa. Our more extensive analysis places the sample within the S. scrofa clade, calling into question the species status of S. bucculentus and demonstrating the need for both phylogenetic and morphological evidence in defining species.     

The influence of the surface migration of gold on the growth of silicon nanowires

Interest in nanowires continues to grow, fuelled in part by applications in nanotechnology. The ability to engineer nanowire properties makes them especially promising in nanoelectronics. Most silicon nanowires are grown using the vapour-liquid-solid (VLS) mechanism, in which the nanowire grows from a gold/silicon catalyst droplet during silicon chemical vapour deposition. Despite over 40 years of study, many aspects of VLS growth are not well understood. For example, in the conventional picture the catalyst droplet does not change during growth, and the nanowire sidewalls consist of clean silicon facets. Here we demonstrate that these assumptions are false for silicon nanowires grown on Si(111) under conditions where all of the experimental parameters (surface structure, gas cleanliness, and background contaminants) are carefully controlled. We show that gold diffusion during growth determines the length, shape, and sidewall properties of the nanowires. Gold from the catalyst droplets wets the nanowire sidewalls, eventually consuming the droplets and terminating VLS growth. Gold diffusion from the smaller droplets to the larger ones (Ostwald ripening) leads to nanowire diameters that change during growth. These results show that the silicon nanowire growth is fundamentally limited by gold diffusion: smooth, arbitrarily long nanowires cannot be grown without eliminating gold migration.