The potential of shifting recombination hotspots to increase genetic gain in livestock breeding

International audienceAbstractBackgroundThis study uses simulation to explore and quantify the potential effect of shifting recombination hotspots on genetic gain in livestock breeding programs.MethodsWe simulated three scenarios that differed in the locations of quantitative trait nucleotides (QTN) and recombination hotspots in the genome. In scenario 1, QTN were randomly distributed along the chromosomes and recombination was restricted to occur within specific genomic regions (i.e. recombination hotspots). In the other two scenarios, both QTN and recombination hotspots were located in specific regions, but differed in whether the QTN occurred outside of (scenario 2) or inside (scenario 3) recombination hotspots. We split each chromosome into 250, 500 or 1000 regions per chromosome of which 10% were recombination hotspots and/or contained QTN. The breeding program was run for 21 generations of selection, after which recombination hotspot regions were kept the same or were shifted to adjacent regions for a further 80 generations of selection. We evaluated the effect of shifting recombination hotspots on genetic gain, genetic variance and genic variance.ResultsOur results show that shifting recombination hotspots reduced the decline of genetic and genic variance by releasing standing allelic variation in the form of new allele combinations. This in turn resulted in larger increases in genetic gain. However, the benefit of shifting recombination hotspots for increased genetic gain was only observed when QTN were initially outside recombination hotspots. If QTN were initially inside recombination hotspots then shifting them decreased genetic gain.DiscussionShifting recombination hotspots to regions of the genome where recombination had not occurred for 21 generations of selection (i.e. recombination deserts) released more of the standing allelic variation available in each generation and thus increased genetic gain. However, whether and how much increase in genetic gain was achieved by shifting recombination hotspots depended on the distribution of QTN in the genome, the number of recombination hotspots and whether QTN were initially inside or outside recombination hotspots.ConclusionsOur findings show future scope for targeted modification of recombination hotspots e.g. through changes in zinc-finger motifs of the PRDM9 protein to increase genetic gain in production species

Treatment of American tegumentary leishmaniasis in special populations : a summary of evidence

We aimed to assess and synthesize the information available in the literature regarding the treatment of American tegumentary leishmaniasis in special populations. We searched MEDLINE (via PubMed), EMBASE, LILACS, SciELO, Scopus, Cochrane Library and mRCT databases to identify clinical trials and observational studies that assessed the pharmacological treatment of the following groups of patients: pregnant women, nursing mothers, children, the elderly, individuals with chronic diseases and individuals with suppressed immune systems. The quality of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. The available evidence suggests that the treatments of choice for each population or disease entity are as follows: nursing mothers and children (meglumine antimoniate or pentamidine), patients with renal disease (amphotericin B or miltefosine), patients with heart disease (amphotericin B, miltefosine or pentamidine), immunosuppressed patients (liposomal amphotericin), the elderly (meglumine antimoniate), pregnant women (amphotericin B) and patients with liver disease (no evidence available). The quality of evidence is low or very low for all groups. Accurate controlled studies are required to fill in the gaps in evidence for treatment in special populations. Post-marketing surveillance programs could also collect relevant information to guide treatment decision-making

Calcineurin inhibitors in renal transplantation still needed but in reduced doses: a review.

Despite their contribution in the success of organ transplantation, calcineurin inhibitors (CNIs) may be responsible for frequent and severe side effects that can affect graft survival and life expectancy. In this article, we have reviewed registry studies and randomized controlled trials (RCTs) that seek to avoid, withdraw, or minimize CNIs in renal transplant recipients. Attempts to completely avoid CNIs by administering mycophenolate mofetil (MMF) and/or sirolimus (SRL) have resulted in increased risks of rejection and side effects, with small advantage to improve renal graft function. Early withdrawal of CNIs after transplantation using administration of MMF can improve graft function but may be associated with a greater risk of acute or chronic rejection and graft failure. RCTs in which CNIs were replaced a few months after transplantation by SRL reported improved graft function among SRL-treated patients, but such a treatment was complicated by iatrogenic toxicity. Late replacement of CNIs with SRL did not produce a particular advantage and again was complicated by more frequent side effects. On the basis of these trials, it seems that CNI elimination can trigger rejection or side effects. Recent RCTs showed that minimization of CNI doses in association with everolimus does not increase the risk of rejection, allows one to obtain good graft function, and is well tolerated. Such an approach seems therefore preferable to complete elimination of CNIs with substitution of the current immunosuppressive drugs

Non-Imaging Nuclear Monitoring of Left Ventricular Function: Twenty-Five Years of Technical Development and Clinical Experience

Although the first non-imaging nuclear probe for clinical application was already available 25 years ago, this technique is still underused for the assessment of ventricular function. Over the years substantial technological progress rendered nuclear probes more accurate and easier to use, and so far the applicability of these devices has been evaluated in several experimental and clinical contexts. Bedside devices can be used in the evaluation of hemodynamically unstable patients and of drug therapy. In patients with several heart diseases, particularly with ischemic cardiomyopathy, accurate information on the changes in ventricular function occurring during routine activities, as well as during structured activities, can be provided using the ambulatory probes. This review will focus on the development and clinical application of these diagnostic tools