Optimizing purebred selection for crossbred performance using QTL with different degrees of dominance

A method was developed to optimize simultaneous selection for a quantitative trait with a known QTL within a male and a female line to maximize crossbred performance from a two-way cross. Strategies to maximize cumulative discounted response in crossbred performance over ten generations were derived by optimizing weights in an index of a QTL and phenotype. Strategies were compared to selection on purebred phenotype. Extra responses were limited for QTL with additive and partial dominance effects, but substantial for QTL with over-dominance, for which optimal QTL selection resulted in differential selection in male and female lines to increase the frequency of heterozygotes and polygenic responses. For over-dominant QTL, maximization of crossbred performance one generation at a time resulted in similar responses as optimization across all generations and simultaneous optimal selection in a male and female line resulted in greater response than optimal selection within a single line without crossbreeding. Results show that strategic use of information on over-dominant QTL can enhance crossbred performance without crossbred testing.     

Biliary, fecal and urinary excretion of [3H]-prostaglandins in the rat

The profiles of biliary, fecal and urinary excretion of tritium labeled prostaglandins (PG's) of differing biological activity were investigated in the rat. The PG's (10 micrograms/kg: 2 to 50 microCi/rat, in 1 ml polyethylene glycol-400) were administered intragastrically. Excretion data were expressed as a percentage of the total administered radioactivity. For the orally administered PG's 11R-methyl-16R-fluoro-15R-hydroxy-9-oxoprosta-ci s-5-trans-13-dienoic acid and its methyl ester, excretion was equally divided between urine and feces. The fecal and urinary profile of excretion of 3H after prostacyclin (PGI2) was similar to that following administration of 11R, 16, 16-trimethyl-15R-hydroxy-9-oxoprosta-cis-5-trans-13-dienoic acid (trimoprostil), a PG with antisecretory-antiulcer potential. However, PGI2 was very poorly absorbed from the intestine, while the absorption of trimoprostil was very efficient. Biliary excretion, with little entero-porto-hepatic biliary circulation, was the main route of elimination of trimoprostil, thereby resulting in rapid elimination of drug-related products and diminishing the potential for systemic liability in the rat.     

Estrogen and the induction of lordosis in female and male prairie voles (Microtus ochrogaster)

Estrogen elicited lordosis in ovariectomized female prairie voles (Microtus ochrogaster). Treatment with estradiol benzoate (EB) was particularly effective if administered as multiple injections. Very high dose levels were not, in general, any more effective than lower doses. Individual animals typically showed lordosis within 24 to 48 hr following the onset of EB treatment and prolonged treatments did not increase the percentage of females responding to EB. Castrated male prairie voles did not respond with lordosis to repeated daily injections of 10 micrograms EB given for a period of 15 consecutive days.     

Purification of phospholipase D from citrus callus tissue

Phospholipase D in extracts of soluble proteins from callus cultures derived from cotyledons of Citrus sinensis (L.) Osbeck is activated by Ca2+ and anionic detergents and has a pH optimum of 6.5. The enzyme was purified 703-fold over the crude protein extract with a yield of 15% by ammonium sulfate precipitation, ion exchange chromatography, gel filtration, hydrophobic interaction chromatography, and preparative acrylamide gel electrophoresis. Preparative electrophoresis was carried out using conventional slab gel equipment and electroelution of the sliced gel. Analytical sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified phospholipase revealed two bands of the same staining intensity running at 94.2K and 90.5K.     

Effects of nucleotides and divalent cations on phospholipase activity in Saccharomyces cerevisiae

Divalent cations activate the lysophospholipase and transacylase reactions catalyzed by the same enzymes in the yeast Saccharomyces cerevisiae. The activation was observed at neutral pH, but not at the pH optimum of lysophospholipase/transacylase, near 3.5. Adenine nucleotides, especially AMP and ADP, are strong inhibitors of the same group of enzymes. Half maximal inhibition by AMP was found at a concentration of about 20 M. The inhibition by nucleotides in low concentrations is enhanced by divalent cations.     

Effect of postnatal development on calcium currents and slow charge movement in mammalian skeletal muscle

Single- (whole-cell patch) and two-electrode voltage-clamp techniques were used to measure transient (Ifast) and sustained (Islow) calcium currents, linear capacitance, and slow, voltage-dependent charge movements in freshly dissociated fibers of the flexor digitorum brevis (FDB) muscle of rats of various postnatal ages. Peak Ifast was largest in FDB fibers of neonatal (1-5 d) rats, having a magnitude in 10 mM external Ca of 1.4 +/- 0.9 pA/pF (mean +/- SD; current normalized by linear fiber capacitance). Peak Ifast was smaller in FDB fibers of older animals, and by approximately 3 wk postnatal, it was so small as to be unmeasurable. By contrast, the magnitudes of Islow and charge movement increased substantially during postnatal development. Peak Islow was 3.6 +/- 2.5 pA/pF in FDB fibers of 1-5-d rats and increased to 16.4 +/- 6.5 pA/pF in 45-50-d-old rats; for these same two age groups, Qmax, the total mobile charge measurable as charge movement, was 6.0 +/- 1.7 and 23.8 +/- 4.0 nC/microF, respectively. As both Islow and charge movement are thought to arise in the transverse-tubular system, linear capacitance normalized by the area of fiber surface was determined as an indirect measure of the membrane area of the t-system relative to that of the fiber surface. This parameter increased from 1.5 +/- 0.2 microF/cm2 in 2-d fibers to 2.9 +/- 0.4 microF/cm2 in 44-d fibers. The increases in peak Islow, Qmax, and normalized linear capacitance all had similar time courses. Although the function of Islow is unknown, the substantial postnatal increase in its magnitude suggests that it plays an important role in the physiology of skeletal muscle.     

Chemical and spectroscopic evidence for the formation of a ferryl Fea3 intermediate during turnover of cytochrome c oxidase

When partially reduced cytochrome c oxidase samples are reoxidized with dioxygen, an EPR-silent dioxygen intermediate, which is at the three-electron level of dioxygen reduction, is trapped at the dioxygen reduction site. The intermediate has novel spectral features at 580 and 537 nm. Combined optical and EPR results reveal that this intermediate reacts rapidly with CO at 277-298 K causing the abolition of the 580/537 mm features and the appearance of a rhombic CuB EPR signal. A ferryl Fea3, or an intermediate at the same formal level of oxidation, is proposed to oxidize CO to CO2 producing an EPR-detectable CuB adjacent to a low-spin ferrous Fea3-dioxygen (or carbon monoxide) adduct.     

Purification of a phospholipase B inhibitor from Saccharomyces cerevisiae

The phospholipase B activity of plasma membrane vesicles from Saccharomyces cerevisiae is inhibited by the 100 000 X g supernatant of mechanically disrupted yeast cells. A 1850-fold purification of the inhibitor activity was achieved by gel filtration, ion exchange chromatography with DEAE-cellulose and hydrophobic interaction chromatography with Octyl-Sepharose. SDS-polyacrylamide gel electrophoresis of the purified inhibitor revealed two main bands with an apparent Mr of 60 000 and 26 500. The phospholipase B activity was strongly reduced but not completely blocked by this preparation, while the lysophospholipase and transacylase reactions, which are catalyzed by the same membrane-bound enzymes (Witt, W. et al. (1984) Biochim. Biophys. Acta 795, 108-116), were not affected.     

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