Reticulate evolution: frequent introgressive hybridization among chinese hares (genus lepus) revealed by analyses of multiple mitochondrial and nuclear DNA loci

<p>Abstract</p> <p>Background</p> <p>Interspecific hybridization may lead to the introgression of genes and genomes across species barriers and contribute to a reticulate evolutionary pattern and thus taxonomic uncertainties. Since several previous studies have demonstrated that introgressive hybridization has occurred among some species within <it>Lepus</it>, therefore it is possible that introgressive hybridization events also occur among Chinese <it>Lepus </it>species and contribute to the current taxonomic confusion.</p> <p>Results</p> <p>Data from four mtDNA genes, from 116 individuals, and one nuclear gene, from 119 individuals, provides the first evidence of frequent introgression events via historical and recent interspecific hybridizations among six Chinese <it>Lepus </it>species. Remarkably, the mtDNA of <it>L. mandshuricus </it>was completely replaced by mtDNA from <it>L. timidus </it>and <it>L. sinensis</it>. Analysis of the nuclear DNA sequence revealed a high proportion of heterozygous genotypes containing alleles from two divergent clades and that several haplotypes were shared among species, suggesting repeated and recent introgression. Furthermore, results from the present analyses suggest that Chinese hares belong to eight species.</p> <p>Conclusion</p> <p>This study provides a framework for understanding the patterns of speciation and the taxonomy of this clade. The existence of morphological intermediates and atypical mitochondrial gene genealogies resulting from frequent hybridization events likely contribute to the current taxonomic confusion of Chinese hares. The present study also demonstrated that nuclear gene sequence could offer a powerful complementary data set with mtDNA in tracing a complete evolutionary history of recently diverged species.</p

Usefulness and limitations of transthoracic echocardiography in heart transplantation recipients

Transthoracic echocardiography is a primary non-invasive modality for investigation of heart transplant recipients. It is a versatile tool which provides comprehensive information about cardiac structure and function. Echocardiographic examinations can be easily performed at the bedside and serially repeated without any patient's discomfort. This review highlights the usefulness of Doppler echocardiography in the assessment of left ventricular and right ventricular systolic and diastolic function, of left ventricular mass, valvular heart disease, pulmonary arterial hypertension and pericardial effusion in heart transplant recipients. The main experiences performed by either standard Doppler echocardiography and new high-tech ultrasound technologies are summarised, pointing out advantages and limitations of the described techniques in diagnosing acute allograft rejection and cardiac graft vasculopathy. Despite the sustained efforts of echocardiographic technique in predicting the biopsy state, endocardial myocardial biopsies are still regarded as the gold standard for detection of acute allograft rejection. Conversely, stress echocardiography is able to identify accurately cardiac graft vasculopathy and has a recognised prognostic in this clinical setting. A normal stress-echo justifies postponement of invasive studies. Another use of transthoracic echocardiography is the monitorisation and the visualisation of the catheter during the performance of endomyocardial biopsy. Bedside stress echocardiography is even useful to select appropriately heart donors with brain death. The ultrasound monitoring is simple and effective for monitoring a safe performance of biopsy procedures

Ozone based chemical oxide growth for crystalline solar cell production

Emitter formation of crystalline silicon solar cells by inline diffusion can be affected by non uniformities in dopant deposition prior to the furnace due to insufficient wetting of hydropho bic surfaces. The impact of dissolved ozone treatment after texturing has been investigated with respect to the possibility of improving the emitter formation with a low cost process enhancement. The chemically grown thin oxide improves wetting capability without modification of other surface characteristics that can impact cell efficiency. It could be shown that already low concentrations of ozone in UPW prior to phosphorus doping improve the sheet resistance uniformity on Cz Si and multi crystalline Si solar cells between 30 and 100 compared to HF last treated one

Ozone based chemical oxide growth for chrystalline solar cell production

A low cost alternative route for uniform hydrophilisation and cleaning is the surface passivation with a thin chemical oxide layer grown by using an ozonised rinse after the final HF dip, potentially combined with an HF O3 cleaning step. This work investigates the surface characteristic of crystalline substrates after texturing with final passivation by ozon. Oxide growth characteristic, thickness and uniformity as well as impact of surface wettability for inline phosphorus doping are reported. Potential benefit for high quality, low cost wet processing in Si solar production are derive

Ozone based chemical oxide growth for crystalline silicon solar cell production

Treatment of crystalline silicon solar cells with ozone dissolved in ultra pure water is a low cost alternative to improve surface characteristics before and after emitter formation. The impact of dissolved ozone treatment after texturing has been investigated with respect to interface state densities and the possibility of improving the emitter formation with a low cost process enhancement. The chemically grown thin oxide improves wetting capability without modification of other surface characteristics that can impact cell efficiency. It could be shown that already low concentrations of ozone in ultra pure water UPW prior to phosphorus doping improves sheet resistance uniformity on Cz Si and multi crystalline mc silicon solar cells by 30 5