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Heterosis was documented in the 18th century, but its biological basis has been debated since. The theoretical framework proposed by Hill, and adapted by Lynch, is based on two central parameters: admixed composition (S), and the heterozygosity (H). Using genomic information, it is now possible to estimate independently the individual realized Si and Hi. In this research, a methodology for estimating the contribution of dominance and additive × additive effects to heterosis is proposed. This approach would be especially relevant in cases where there is insufficient phenotypic information available, or an adequate genetic group experimental design, common in humans, wild species and other admixed populations. We also provide theoretical arguments highlighting the enhanced precision of the estimations of heterosis parameters through this method. Furthermore, we exemplify this procedure by analysing data from an experimental F2 pig population, which was initially designed for QTL mapping. Notably, all animals in this population were genotyped (including F1 and parental breeds), but phenotypic information was only available for F2 individuals and included 13 traits related to growth, fat deposition, carcass characteristics and meat quality. Significant additive effects (p < 0.05) were detected for longissimus muscle area and carcass temperature, suggesting complementary additive effects for these traits. Significant dominance and additive × additive effects were also detected for birth weight and carcass length, respectively (p < 0.05), indicating that heterosis for these traits is primarily attributable to dominance and additive × additive interactions. These results demonstrate that the proposed methodology can successfully estimate the genetic components underlying heterosis and underscores the utility of this approach in situations where we possess genomic data but limited phenotypic data.
Inverses of relationship matrices are useful for prediction of individual additive or nonadditive genetic merits and for estimation of variance components. An algorithm to form inverses of additive by additive relationship matrices rapidly from lists of individuals and their parents was developed. The algorithm uses simple recurrences among additive by additive and sire-dam combination effects to construct inverses for noninbred or inbred populations. Dimensions of matrices produced may be several times the number of individuals in the population because combination effects for sire-dam subclasses must be included in matrices. Rules of inheritance of sire-dam combination effects are the same as for dominance combination effects. Cost of forming inverses increases linearly with number of individuals. Each individual contributes 36 or fewer nonzero coefficients, and each sire-dam subclass contributes an additional 81 or fewer nonzero coefficients to the matrix. Computation of inverse of the relationship matrix due to 1003 sires and maternal grandsires of 765,868 cows required forming a matrix of order 137,830 and 4 Mbytes of memory.
Recently, Widaman, Geary, Cormier, and Little (in press) offered a general componential model for simple and complex addition. In the present study, the generalizability of this model to very complex addition problems and to production task performance was tested. We investigated addition-production performance using a new research paradigm, the decision-production task. The paradigm was used to assess the reaction times of 16 adults to 100 single-digit addition problems (Experiment 1) and to very complex three-digit addition problems (Experiment 2). Generally, the results give evidence for the basic assumptions of the Widaman et al. model. Some of the results, however, demonstrate that short-term memory load factors and strategy choices also have important effects on complex addition-production performance. Furthermore, the results of both experiments indicate that, in production tasks, the nature of the elementary search/compute process can be characterized as a memory-retrieval process and that the decision-production paradigm is a valuable alternative to the classical verbal production paradigm.
Permitted levels of use for food additives should agree with the acceptable daily intakes (ADIs) established by toxicologists. To ensure accordance, nutritional and physiological factors can be used to estimate high intakes of food and beverages. Appetite and thirst (energy and liquid requirements) are such quantitative factors. They are universal and, if placed on the same level as the ADI, i.e., expressed on a kilogram of body weight basis, can be used to estimate high intakes of an additive. This tool can be easily used to judge whether a suggested level of use may cause consumption of the additive to exceed the ADI. It also tells us to what level (ADI) toxicological clearance should be sought, when the technological need is known. The method is independent of food consumption surveys, but these may be carried out to confirm its forecasts. This paper uses caramel in soft drinks as an example. The approach, also called "the budget method," has been tried out in Denmark and Sweden. It is now being offered as a solution to the problem facing the European Communities: to establish before 1993 a common list of food additives containing quantitative limitations for use.
We have attempted to provide an overview of the Food, Drug, and Cosmetic Act as it pertains to animal drugs and feed additives. The Act requires that each new animal drug application or food additive petition contain sufficient data to prove that the drug or feed additive is safe and effective before the drug or feed additive can be marketed. It also gives the Secretary of Health, Education, and Welfare the power to remove from the market a previously accepted drug if it is shown to be unsafe or lacks effectiveness. The Bureau of Veterinary Medicine has prepared guidelines to aid applicants in compiling ans submitting the necessary information for approval of drugs to be used in dairy cattle. A copy of these guidelines and a Drug Use Guide, which aids the dairymen to correctly use approved drugs, can be obtained from the Bureau.
The additive natriuretic effect of a single dose of bendroflumethiazide, 5 mg., has been studied in patients with advanced congestive heart failure in long-term treatment with bumetanide, 4 mg., daily. Three permutation trial tests were performed including six patients each. In the first trial, the response to supplementary bendroflumethiazide, 5 mg., was definitely superior to that of additional bumetanide, 4 mg., in terms of renal output of sodium, chloride, potassium, water, and osmolar clearance. In the second trial, a similar pattern was found in patients receiving a combination of bumetanide, 4 mg., and spironolactone, 100 mg., daily. The third trial compared the effects of bendroflumethiazide, 5 mg., plus bumetanide, 4 mg.; of bendroflumethiazide, 5 mg.; and of bumetanide, 4 mg. In terms of natriuresis and chloruresis, the response to the combination of two drugs was significantly larger than the sum of the effects of other treatments. It is concluded that the combined effects of the drugs represent a supra-additive effect addition for sodium and chloride. A tentative explanation of the mechanism of interaction in terms of inhibition of renal tubular supplementary spironolactone, involve a tendency to development of hypokalemia, hypochloremia, and alkalosis, it is recommended that supplementary use of bendroflumethiazide in this setting is combined with the administration of potassium chloride or potassium-saving diuretics.
This research links neuro- and cognitive psychology by asking whether performance of two concurrent cognitive tasks is facilitated by presentation of each task to a different cerebral hemisphere. Subjects were required to perform two arithmetic problems which were presented simultaneously. One problem required addition; the other subtraction. In Experiment I, briefly exposed numbers were exposed for 100 ms and were arranged so that a digit at fixation had to be added to a top number and subtracted from a bottom number. In Experiment II, the numbers were reversed so that the addition task was below the subtraction task. During Bilateral/bihemispheric trials, the addition problem was presented to one visual field and the subtraction problem to the other visual field. During Unilateral/single hemisphere trials, the addition and subtraction problems were projected to only one visual field. Results indicated that a higher proportion of problems were correctly solved during the Bilateral/bihemispheric trials than during the Unilateral/single hemisphere trials. These data suggest that dividing simultaneous inputs so that each hemisphere is confronted with a task requiring only one kind of cognitive operation facilitates performance, perhaps by minimizing intertask interference. This study illustrates one kind of hemispheric cooperation which facilitates dual task performance.
A melanoma proteoglycan model system has been used to examine the role of core protein asparagine-linked (N-linked) oligosaccharides in the transport and assembly of proteoglycan molecules. The use of agents which block discrete steps in the trimming and processing of core oligosaccharides (castanospermine, 1-deoxynojirimycin, N-methyldeoxynojirimycin, 1-deoxymannojirimycin, and swainsonine) demonstrates that removal of glucose residues from the N-linked oligosaccharides is required for the cell surface expression of a melanoma proteoglycan core protein and for the conversion of the core protein to a chondroitin sulfate proteoglycan. However, complete maturation of the oligosaccharides to a "complex" form is not required for these events. Treatment of M21 human melanoma cells with the glucosidase inhibitors castanospermine, 1-deoxynojirimycin, or N-methyldeoxynojirimycin results in a dose-dependent inhibition of glycosaminoglycan (GAG) addition to the melanoma antigen recognized by monoclonal antibody 9.2.27. In contrast, treatment with the mannosidase inhibitors 1-deoxymannojirimycin and swainsonine does not effect GAG addition. Identical results are obtained when the major histocompatibility complex class II antigen gamma chain proteoglycan is examined in inhibitor-treated melanoma and B-lymphoblastoid cells. These data, in conjunction with the known effects of the glucosidase and mannosidase inhibitors on the transport and secretion of other glycoproteins support the hypothesis that the addition, trimming, and processing of N-linked oligosaccharides is involved in the transport of certain proteoglycan core proteins to the site of GAG addition and to the cell surface.
The optico-physical characteristics of four different designs of progressive addition lenses(PALs) were assessed using a computer-controlled automated focimeter. For each design and for the four designs taken together, reading addition power was shown to correlate positively with PAL progression corridor length and negatively with PAL progression corridor width. Empirical measurements from the four PALs measured showed each design to have more favourable characteristics when compared with a theoretical single power law model.
10188 growth records (performance up to weaning) of 283 Largewhite pigs were used to estimate various components of variance using a mixed linear model for the birth weight, litter size at birth, weaning weight, and litter size at weaning. Restricted maximum likelihood procedures were used. Object of the investigation were the respective additive genetic, non-additive genetic, and permanent environmental variation traits within the overall variation as well as the respective residual components. The results were tabulated and expressed specifically by way of the heritability and repeatability coefficients.
The mechanism by which microcapsule aggregation is diminished in the presence of low concentrations of adjunct non-walling polymers such as polyisobutylene (PIB) in organic solvents is uncertain. It is here investigated by phase separation studies employing the non-solvent addition method (cyclohexane) in parallel with microencapsulation experiments, using Eudragit wall polymers and tetrahydrofurane (THF) as solvent with and without PIB. Polymer incompatibility leads to formation of two dilute liquid phases and emulsification from the outset. Progressive solvent transfer to the PIB phase modulates the rate of wall polymer desolvation and maintains the concentrated wall polymer phase in a fluid state during the critical microencapsulation stages of wall polymer entrapment--and spreading. A three-phase system is formed when gelling ensues (L1 + L2 + gel). In the absence of PIB, phase separation leads immediately to deposition of the wall polymer in gel form (L1 + gel) leading to adhesion. Phase diagrams are presented.
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