Novel strategies for genomic prediction of untested single-cross maize hybrids using unbalanced historical data.

KEY MESSAGE: Weighted outperformed unweighted genomic prediction using an unbalanced dataset representative of a commercial breeding program. Moreover, the use of the two cycles preceding predictions as training set achieved optimal prediction ability. Predicting the performance of untested single-cross hybrids through genomic prediction (GP) is highly desirable to increase genetic gain. Here, we evaluate the predictive ability (PA) of novel genomic strategies to predict single-cross maize hybrids using an unbalanced historical dataset of a tropical breeding program. Field data comprised 949 single-cross hybrids evaluated from 2006 to 2013, representing eight breeding cycles. Hybrid genotypes were inferred based on their parents' genotypes (inbred lines) using single-nucleotide polymorphism markers obtained via genotyping-by-sequencing. GP analyses were fitted using genomic best linear unbiased prediction via a stage-wise approach, considering two distinct cross-validation schemes. Results highlight the importance of taking into account the uncertainty regarding the adjusted means at each step of a stage-wise analysis, due to the highly unbalanced data structure and the expected heterogeneity of variances across years and locations of a commercial breeding program. Further, an increase in the size of the training set was not always advantageous even in the same breeding program. The use of the two cycles preceding predictions achieved optimal PA of untested single-cross hybrids in a forward prediction scenario, which could be used to replace the first step of field screening. Finally, in addition to the practical and theoretical results applied to maize hybrid breeding programs, the stage-wise analysis performed in this study may be applied to any crop historical unbalanced data.

A laparoscopic approach to allograft nephrectomy and bilateral native nephrectomy: a case report.

INTRODUCTION: Laparoscopic surgery is rapidly emerging as the standard of care for a variety of urological conditions, even among patients who have undergone prior renal transplantation. We describe the technique of bilateral native nephrectomy and allograft nephrectomy by laparoscopy. CASE REPORT: A 32-year-old man with end-stage renal disease who had undergone a cadaveric renal transplant presented with chronic graft dysfunction. He had received a living donor kidney transplant with a postoperative course complicated by persistent proteinuria and refractory hypertension. Our nephrology service indicated the need for bilateral native nephrectomy and allograft nephrectomy for better blood pressure control following a second transplant. Bilateral native nephrectomy was performed following the previous reported techniques for pure laparoscopic nephrectomy. Allograft nephrectomy started by dissection of the iliac vessels to identify the vascular anastomosis. The hilum of the transplanted kidney was accessed. The renal vessels were clipped and transected. The ureter was identified and clipped. All three kidneys were removed from the abdominal cavity through a 3-cm skin incision. RESULTS: The left nephrectomy took 25 minutes and the right nephrectomy, 40 minutes. The estimated blood loss was 300 mL and the total operative time was 210 minutes. The patient had an uneventful postoperative course and was discharged on the third postoperative day. CONCLUSIONS: We demonstrate the feasibility of laparoscopic allograft nephrectomy and bilateral native nephrectomy in a transplant recipient.