A genome scan reveals QTL for growth, fatness, leanness and meat quality in a Duroc-Pietrain resource population.

We performed a genome-wide QTL scan for production traits in a line cross between Duroc and Pietrain breeds of pigs, which included 585 F(2) progeny produced from 31 full-sib families genotyped with 106 informative microsatellites. A linkage map covering all 18 autosomes and spanning 1987 Kosambi cM was constructed. Thirty-five phenotypic traits including body weight, growth, carcass composition and meat quality traits were analysed using least square regression interval mapping. Twenty-four QTL exceeded the genome-wide significance threshold, while 47 QTL reached the suggestive threshold. These QTL were located at 28 genomic regions on 16 autosomal chromosomes and QTL in 11 regions were significant at the genome-wide level. A QTL affecting pH value in loin was detected on SSC1 between marker-interval S0312-S0113 with strong statistical support (P < 3.0 x 10(-14)); this QTL was also associated with meat colour and conductivity. QTL for carcass composition and average daily gain was also found on SSC1, suggesting multiple QTL. Seventeen genomic segments had only a single QTL that reached at least suggestive significance. Forty QTL exhibited additive inheritance whereas 31 QTL showed (over-) dominance effects. Two QTL for trait backfat thickness were detected on SSC2; a significant paternal effect was found for a QTL in the IGF2 region while another QTL in the middle of SSC2 showed Mendelian expression.

Central retinal venous outflow pressure.

BACKGROUND: Does the venous collapse phenomenon provide the possibility of venous dynamometry? METHOD: A technical model is presented which allows analysis of the conditions of the collapse of the central retinal vein in vitro. The conditions of the venous collapse were analysed with regard to intraocular pressure, intravasal pressure in the outflow of the central retinal vein and the overall perfusion. For clinical measurements dynamometry of the venous collapse is performed parallel to the experimental setting. RESULTS: The experiment reveals identical results for venous outflow pressure measured by venous dynamometry and by intravasal pressure detector. Venous dynamometry in vivo means that we use the onset of the venous collapse phenomenon to register the pressure in the central retinal vein at the point where it leaves the eye. Using this technique, retroocular obstruction of the venous outflow may be assessed. The venous outflow pressure itself depends on the venous flow resistance, intracranial pressure and arterial perfusion pressure. Any disorder of these three parameters may be assessed when the absolute venous outflow pressure is registered. CONCLUSION: The venous collapse phenomenon enables us to determine the venous outflow pressure. Clinical applications have proven promising.