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.     

Effects of noradrenaline on45Ca2+ efflux from isolated rat islets of Langerhans

Noradrenaline caused a prompt but transient increase in the rate of⁴⁵Ca²⁺ efflux from isolated rat islets of Langerhans perifused in Ca²⁺ depleted medium. The response was modest in size and was unaffected by isosmotic replacement of NaCl with choline chloride or by inclusion of 0.5 mM dibutyryl cAMP in the perifusion medium, suggesting that it was not mediated by Na+: Ca²⁺ exchange nor by lowered cAMP. Despite its effect on⁴⁵Ca²⁺ efflux, noradrenaline treatment did not alter the kinetics of⁴⁵Ca²⁺ efflux in response to the muscarinic agonist, carbamylcholine, nor did it change the magnitude of the response to this agent. Simultaneous introduction of 20 mM glucose with noradrenaline prevented a rise in⁴⁵Ca²⁺ efflux and indeed resulted in inhibition of⁴⁵Ca²⁺ efflux. The data suggest that noradrenaline does not directly activate the mechanisms which regulate Ca²⁺ extrusion from islets cells, and they do not support a primary role for the Ca²⁺ efflux response in mediating adrenergic inhibition of insulin secretion.     

Anatomy of antenno-cerebral pathways in the brain of the sphinx moth Manduca sexta

Summary In the moth Manduca sexta, the number and morphology of neuronal connections between the antennal lobes and the protocerebrum were examined. Cobalt injections revealed eight morphological types of neurons with somata adjacent to the AL neuropil that project in the inner, middle, and outer antenno-cerebral tracts to the protocerebrum. Neurons innervating the macroglomerular complex and many neurons with fibers in the inner antennocerebral tract have uniglomerular antennal-lobe arborizations. Most neurons in the middle and outer antenno-cerebral tracts, on the other hand, seem to innervate more than one glomerulus. Protocerebral areas receiving direct input from the antennal lobe include the calyces of the mushroom bodies, and circumscribed areas termed olfactory foci in the lateral horn of the protocerebrum and several other regions, especially areas in close proximity to the mushroom bodies. Fibers in the inner antenno-cerebral tract that innervate the male-specific macroglomerular complex have arborizations in the protocerebrum that are distinct from the projections of sexually non-specific neurons. Protocerebral neurons projecting into the antennal lobe are much less numerous than antennal-lobe output cells. Most of these protocerebral fibers enter the antennal lobe in small fiber tracts that are different from those described above. In the protocerebrum, these centrifugal cells arborize in olfactory foci and also in the inferior median protocerebrum and the lateral accessory lobes. The morphological diversity of connections between the antennal lobes and the protocerebrum, described here for the first time on a single-cell level, suggests a much greater physiological complexity of the olfactory system than has been assumed so far.     

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.     

Phosphatidylinositol hydrolysis in isolated guinea-pig islets of Langerhans.

Previous studies have reported an increased turnover of phospholipid in isolated islets of Langerhans in response to raised glucose concentrations. The present investigation was thus undertaken to determine the nature of any phospholipases that may be implicated in this phenomenon by employing various radiolabelled exogenous phospholipids. Hydrolysis of 1-acyl-2-[14C]arachidonoylglycerophosphoinositol by a sonicated preparation of islets optimally released radiolabelled lysophosphatidylinositol, arachidonic acid and 1,2-diacylglycerol at pH 5,7 and 9 respectively. This indicates the presence of a phospholipase A1 and a phospholipase C. However, the lack of any labelled lysophosphatidylinositol production when 2-acyl-1-[14C]stearoylglycerophosphoinositol was hydrolysed argues against a role for phospholipase A2 in the release of arachidonic acid. Phospholipase C activity as measured by phosphatidyl-myo-[3H]inositol hydrolysis was optimal around pH8, required Ca2+ for activity and was predominantly cytosolic in origin. The time course of phosphatidylinositol hydrolysis at pH 6 indicated a precursor-product relationship for 1,2-diacylglycerol and arachidonic acid respectively. The release of these two products when phosphatidylinositol was hydrolysed by either islet or acinar tissue was similar. However, phospholipase A1 activity was 20-fold higher in acinar tissue. Substrate specificity studies with islet tissue revealed that arachidonic acid release from phosphatidylethanolamine and phosphatidylcholine was only 8% and 2.5% respectively of that from phosphatidylinositol. Diacylglycerol lipase was also demonstrated in islet tissue being predominantly membrane bound and stimulated by Ca2+. The availability of non-esterified arachidonic acid in islet cells could be regulated by changes in the activity of a phosphatidylinositol-specific phospholipase C acting in concert with a diacylglycerol lipase.     

On the applicability of adaptive bioprocess state estimators

This article presents an industrial case study, examining the application of a novel adaptive biomass estimator to an industrial microfungi production process. It is our intention that this contribution should focus upon the implementation issues of the algorithm, in preference to a rigorous theoretical development. The novel algorithm adopted is developed from Adaptive Inferential Estimation studies of Guilandoust and co-workers. The technique utilizes input-output process measurements obtained at different frequencies, thereby providing more frequent estimates of biomass concentration than are otherwise available from off-line laboratory analyses. The algorithm is particularly suited to the biotechnology industry, as it is capable of utilizing irregular assay measurements with varying delays.Although this article demonstrates the encouraging industrial implications of the adaptive algorithm, like all adaptive techniques currently developed, it is restricted by the inability to perform robust on-line system identification. The ultimate selection of a "suboptimal" "fixed parameter" algorithm for on-line implementation, is therefore directly attributable to these inadequacies. Aspects of data acquisition, data pretreatment, and data quality are critical for real process applications, and while some practical approaches are adopted here, many important implementation problems remain unresolved. (c) 1993 John Wiley & Sons, Inc.     

Mapping the diabetes polygene Idd3 on mouse Chromosome 3 by use of novel congenic strains

Development of novel congenic mouse strains has allowed us to better define the location of the diabetogenic locus, Idd3, on Chromosome (Chr) 3. Congenic strains were identified by use of published and newly developed microsatellite markers, their genomes fingerprinted by a rapid, fluorescence-based approach, and their susceptibility to type 1 diabetes evaluated. The maximum interval containing Idd3 is now approximately 4 cM.