Isotope geochemistry and petrogenesis of peralkaline Middle Miocene ignimbrites from central Sonora: relationship with continental break-up and the birth of the Gulf of California

Middle Miocene peralkaline ignimbrites constitute a specific geodynamic marker of the early stage of opening of the Gulf of California, preserved either in central Sonora or the Puertecitos area, in Baja California. Very uniform ages (12-12.5 Ma) obtained on these rocks show that this volcanic episode corresponds to a specific stage in the tectonic evolution of the proto-gulf area. Field observations and slightly different Sr and Nd isotopic signatures support eruptions from several small volume magma batches rather than from a large-volume caldera forming event. Isotopic ratios help to constrain the petrogenesis of the peralkaline liquids by fractional crystallization of transitional basalts in a shallow reservoir, with slight contamination by Precambrian upper crustal material. Less differentiated glomeroporphyritic icelandites erupted at about 11 Ma, mark an increase in the magma production rate and highlight an easier access to the surface, illustrating an advanced stage in the weakening of the continental crust. The tilting of the Middle Tertiary sequences results from a major change in the tectonic regime, from E-W extension giving rise to N-S grabens, to NNW-SSE strike-slip motion that can be related to the transfer of Baja California from North America to the Pacific plate. The location of peralkaline volcanism coincides with the southern edge of the Precambrian crust and the southernmost extension of the California slab window at 12.5 Ma

Sexual health knowledge and behaviours in International MSM Students in Australia

Background International sexual minority students, particularly men who have sex with men (MSM), experience disparities in health, including a significantly higher prevalence of HIV and other STIs and lower levels of sexual health services use. Limited research has been conducted in this population around sexual health knowledge, behaviour and services use. Methods A multi-language cross-sectional online survey was completed by 168 international MSM tertiary students (median age: 25 years) in New South Wales (Australia). Variables included demographics, sexual identity and behaviour, sexual health knowledge and behaviour including PrEP use as well as sexual health services use. Descriptive and correlational analyses, and binary logistic regressions were conducted. Results Sexual health knowledge including routes of HIV transmission was overall high in the sample, while 20% had limited knowledge regarding pre-exposure prophylaxis (PrEP) and 28% regarding post-exposure prophylaxis (PEP). Less than half (44%) reported inconsistent condom use. PrEP use was low in the sample (14%) and not correlated with condom use. Sexual health behaviours and dimensions LGBT Community connectedness were significantly correlated with the use of different sexual health services. Conclusions This first comprehensive study among international MSM tertiary students in Australia demonstrates a high level of inconsistent condom use and low levels of PrEP use as well as strong correlations between sexual health behaviour and HIV/STI testing, and connectedness with other sexual minority men. International MSM students do not feel included in the local LGBT Community but demonstrate a strong desire to be involved. Those included were more likely to use vital sexual health services. Main Message International MSM students are an emerging priority population for sexual health research and practice. , and future health promotion campaigns should consider incorporating strong community building and connectedness elements

Most Lung and Colon Cancer Susceptibility Genes Are Pair-Wise Linked in Mice, Humans and Rats

Genetic predisposition controlled by susceptibility quantitative trait loci (QTLs) contributes to a large proportion of common cancers. Studies of genetics of cancer susceptibility, however, did not address systematically the relationship between susceptibility to cancers in different organs. We present five sets of data on genetic architecture of colon and lung cancer susceptibility in mice, humans and rats. They collectively show that the majority of genes for colon and lung cancer susceptibility are linked pair-wise and are likely identical or related. Four CcS/Dem recombinant congenic strains, each differing from strain BALB/cHeA by a different small random subset of ±12.5% of genes received from strain STS/A, suggestively show either extreme susceptibility or extreme resistance for both colon and lung tumors, which is unlikely if the two tumors were controlled by independent susceptibility genes. Indeed, susceptibility to lung cancer (Sluc) loci underlying the extreme susceptibility or resistance of such CcS/Dem strains, mapped in 226 (CcS-10×CcS-19)F2 mice, co-localize with susceptibility to colon cancer (Scc) loci. Analysis of additional Sluc loci that were mapped in OcB/Dem strains and Scc loci in CcS/Dem strains, respectively, shows their widespread pair-wise co-localization (P = 0.0036). Finally, the majority of published human and rat colon cancer susceptibility genes map to chromosomal regions homologous to mouse Sluc loci. 12/12 mouse Scc loci, 9/11 human and 5/7 rat colon cancer susceptibility loci are close to a Sluc locus or its homologous site, forming 21 clusters of lung and colon cancer susceptibility genes from one, two or three species. Our data shows that cancer susceptibility QTLs can have much broader biological effects than presently appreciated. It also demonstrates the power of mouse genetics to predict human susceptibility genes. Comparison of molecular mechanisms of susceptibility genes that are organ-specific and those with trans-organ effects can provide a new dimension in understanding individual cancer susceptibility