Unrelated Lines Research Articles

Performance of Inbred Lines and Line Crosses of Holsteins for Body Growth

Estimates of the effects of inbreeding and outbreeding in dairy cattle were made in an experiment designed specifically to study these effects in a population in which no artificial selection was practiced. The basic groups in this study were 6 unrelated lines of Holstein cattle; each line was based on a foundation stock of 1 sire, 1 or 2 inbred sons and 20 noninbred daughters. Animals were mated within each line and between lines to produce inbred and “outbred” progeny, respectively. Further outbreeding was conducted by crossing the inbred animals from different lines to produce 2-, 3-, and 4-line crosses. Only a fraction of the total posssible crosses was made. Significant (P<.01) differences were found for body measurements at birth, 3, 6, 12 and 18 months of age, and at 3 months after first calving between the inbreds and “outbreds” when both were from noninbred dams, and between the inbreds and 2-line crosses when both were from inbred dams. The 2-line crosses were significantly superior to the “outbreds.” The inbred females from inbred dams averaged below the inbreds from noninbred dams at birth for all body measurements; but these differences were reversed at older ages. The average body measurements of the animals in the 2-line, 3-line, and 4-line cross mating systems were similar.

INHERITANCE OF CHLOROTIC COTYLEDON INBRASSICA CAMPESTRISL.

Inheritance of chlorotic cotyledon in Brassica campestris was studied in the M3generation descending from seed treated with ethyleneimine. Also studied were F1progenies from crosses between plants having the cotyledon character and a normal unrelated line. Data indicated the trait was controlled by a single partially dominant gene designated C with recognizable genotypes, CC (green), Cc (chlorotic), cc (albino). Mature plants of each genotype were indistinguishable except for some loss of vigor in plants with albino cotyledons.

VERTICAL DENSITY CURRENTS—II1

Examples of vertical density currents wholly within the domain of laminar flow, one in a water solution, the other in air, have come to my attention. Both examples illustrate new ways of introducing and dispersing microscopic particles into static fluids and both demonstrate that a stable, clearly defined layer of dispersed particles forms first and that the vertical density currents originate and flow from the lower part of this layer. The new information comes from wholly unrelated lines of research, one in virology, and the other in mycology. Neither investigation was aimed at hydrodynamics yet both provide good experimental support for vertical density currents.

Genetic Variation in Quantitative Characters in Maize Inbred Lines, II. Effects on Performance in Single‐Cross and Double‐Cross Hybrids1

Six inbred lines and seven single crosses involving these lines were obtained from four Corn Belt foundation seed stock organizations and the Iowa Agriculture Experiment Station. The genetic variation among the strains within inbred lines and among single crosses of the same pedigree was investigated. The inbred strains were compared in testcrosses with three unrelated inbred lines and the single crosses were compared in nine double‐cross hybrids. Tests in 10 environments, five locations for two years, revealed significant differences for percentage moisture among strain testcrosses within all inbreds and for yield in all except two of the inbreds. Strains included pollen restorer (Rf) and nonrestorer (rf) versions, except for two lines in which only rf versions were available. Significant variations were obtained for Rf vs. rf strain testcrosses, among Rf strain testcrosses, and among rf strain testcrosses. The Iowa Rf strain testcrosses were not different from the remaining Rf strain testcrosses for yidd, but the Iowa rf strain testcrosses compared with the remaining rf strain testcrosses were significantly different for yield within three of the six inbreds and for moisture within five of the six inbreds. Among strains within double crosses there were significant differences for percentage moisture in eight hybrids and for yield in four hybrids. Yield differences were great enough to be of practical importance in some cases, whereas moisture differences were not considered of practical importance even though many were statistically significant.

Effectiveness of Selection in F2 of Crosses Among Related and Unrelated Lines of Oats1

Crop ScienceVolume 3, Issue 4 cropsci1963.0011183X000300040012x p. 319-323 Article Effectiveness of Selection in F2 of Crosses Among Related and Unrelated Lines of Oats1 P. B. Escuro, P. B. EscuroSearch for more papers by this authorJ. C. Sentz, J. C. SentzSearch for more papers by this authorW. M. Myers, W. M. Myers Formerly graduate student (now Head, Department of Agronomy, College of Agriculture, University of the Philippines, Los Banos, Laguna, Philippines), Associate Professor, and Professor and Head, respectively, Department of Agronomy and Plant Genetics, University of Minnesota. The senior writer gratefully acknowledges the fellowship granted him by the Rockefeller Foundation and the technical help of F. S. Koo, now at Puerto Rico Nuclear Center, Mayaguez, P. R., throughout the duration of his work.Search for more papers by this author P. B. Escuro, P. B. EscuroSearch for more papers by this authorJ. C. Sentz, J. C. SentzSearch for more papers by this authorW. M. Myers, W. M. Myers Formerly graduate student (now Head, Department of Agronomy, College of Agriculture, University of the Philippines, Los Banos, Laguna, Philippines), Associate Professor, and Professor and Head, respectively, Department of Agronomy and Plant Genetics, University of Minnesota. The senior writer gratefully acknowledges the fellowship granted him by the Rockefeller Foundation and the technical help of F. S. Koo, now at Puerto Rico Nuclear Center, Mayaguez, P. R., throughout the duration of his work.Search for more papers by this author First published: 01 July 1963 https://doi.org/10.2135/cropsci1963.0011183X000300040012xCitations: 1 1 Contribution from the Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minn. Published with approval of the Director as Paper No. 4948, Scientific Journal Series, Minnesota Agr. Exp. Sta. Part of thesis submitted by senior writer in partial fulfillment of requirements for the Ph.D. degree. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume3, Issue4July–August 1963Pages 319-323 RelatedInformation

EXERCISE TOLERANCE IN PREGNANT CARDIAC PATIENTS

Changes involving the immune system may be instigators of, or consequent upon, disorders in other systems in the natural history of gestosis. The extent of the immune 'disorder' may not correlate with the severity of the disease as manifest in either eclampsia or fetal death. A number of variables, e.g. hormonal and genetic, could affect any immunological trigger mechanism or any secondary altered immune response. Thus attempts to find an immunological factor in gestosis that operates in all cases may prove unrewarding. Certain matings, immunogenetic constitutions, or certain feto-maternal immune relationships may predispose to a particular pathology and directly or indirectly potentiate other pathological processes. Others may either have no effect or conceivably have even a homeostatic effect protecting the maternal host from pathological change. The picture of the role of immunological factors in the pathogenesis of pregnancy hypertension is no more, as yet, than a few hesitant, unrelated lines. However, the lines are getting more numerous and stronger.

Behavioral and Ecological Notes on Spalax leucodon

An adult female Spalax leucodon was maintained in captivity for one month in a soil-filled metal box. Its food consisted of root vegetables and large broad beans. Observations were made on burrowing techniques, defense, vocalization, nest building, and water requirements. Additional notes are included on the species' economic importance, local methods of capture, time sense, natural burrows, and distribution in the Aegean region. Convergent characters and behavior adapted to fossorial habits in unrelated and allopatric rodent evolutionary lines suggest that these various forms are ecological equivalents and that the subterranean herbivore niche is one with narrow limits.

Maternal effects on the rate of egg development inDrosophila subobscura

The time in hours from laying to hatching at 17°C. has been measured for eggs from four inbred lines ofDrosophila subobscura, and also for F1eggs, and for eggs obtained by crossing F1hybrids to unrelated inbred lines and to unrelated F1hybrids.Eggs laid by females of a given genotype have a characteristic rate of development, which, with one exception, is not greatly influenced by the genotype of the male parent. F1hybrid females laid eggs which were more uniform in hatching time than eggs laid by inbred females, and which developed more rapidly than eggs laid by three of the four kinds of inbred female studied. The slowest-developing eggs were laid by females from theNFSinbred line, a line originally selected for slow development from egg to adult.The male parent, and hence the zygotic nucleus, had an appreciable effect on the rate of egg development only for eggs laid byNFSfemales; these eggs developed more rapidly if fertilized by sperm from an unrelated male.

Inverse relationship between chromosome ploidy and host-specificity of sixteen transplantable tumors

A representative series of four lymphomas, five carcinomas, one melanoma, and six sarcomas (largely in the ascites form) has been surveyed for chromosome number distribution, growth capacity in foreign strains and, where possible, histocompatibility genes. This comparative analysis, supported by relevant data from other laboratories, has demonstrated a consistent influence of ploidy (2n versus 4n) upon degree of antigenicity. The diploid neoplasms were entirely strain-specific and always regressed in unrelated lines. The tumors characterized by a tetraploid modal value were able to grow in and kill hosts of one or more foreign genotypes, or even showed complete genetic indifference. This inverse relationship between chromosome number and host-requirements appears to be independent of the tumor's histology, virulence, strain of origin, method of induction, and transplantation history. The findings are suggestive of “immunologic selection” from a relatively narrow (mode near 2n) or wide (mode near 4n) range of viable antigenic variants in a malignant cell population.

Studies in quantitative inheritance

1. A crossing method is described for creating all possible combinations of major chromosomes from pairs of inbred lines ofDrosophila melanogaster. The twenty-seven different genotypes in females, eighteen in males, provide the basis for different tests which throw light on the genetic control of body size. 2. Complete chromosome analyses have been carried out on two pairs of contrasted lines of different size, descended from the Nettlebed and Edinburgh wild stocks. Each such pair comprises a small line, descended from a strain selected for small body size, and an approximately normal-sized line, inbred without selection from the same stock. Three unrelated lines inbred without selection have been studied in a similar way, except that twenty-one out of the twenty-seven possible combinations for each pair have been studied in females only. 3. The accuracy of the method of combining chromosomes was demonstrated by the agreement between preparations of the same genotype by different means, and also by the level of the within-culture variance, which was generally of the same order as that for untreated inbred lines. 4. The within-culture variance is not constant for all genotypes, but tends to decline with an increase in the number of heterozygous pairs of chromosomes. 5. When the unselected and small lines are crossed, a highly non-additive situation is revealed by the size of theF1 which may be as great, or nearly as great, as the size of the unselected parent line. 6. In the analysis of the unselected and small Edinburgh lines the size of the different types could be accounted for by aggregate dominance of the chromosomes of the larger 7. In the Nettlebed combinations, aggregate dominance and additive combination of non-homologous chromosomes account for the size of the majority of the types. But there are also a number of striking interactions which increase or decrease size, leading to different effects of particular substitutions and different dominance relations in different genetic backgrounds. Most of the larger interactions occur in genotypes carrying several chromosomes from the small line. The behaviour of the X-chromosome of the small line is exceptional in being incompletely recessive in all backgrounds. 8. In the combination of chromosomes from the unrelated, unselected, inbred lines, interactions between non-homologous chromosomes are much more frequent and striking. The substitution of a single chromosome or of a homozygous pair may increase or decrease size, according to the genetic background. 9. Inter-crossing these unrelated inbred lines always leads to heterosis in theF1, which exceeds both parent lines in size. This heterosis cannot be accounted for merely in terms of the summation of the effects of dominance or over-dominance on different chromosomes, but must be considered in terms of gene interaction. The effects of making each pair of chromosomes heterozygous in otherwise homozygous backgrounds may be compared with the joint effects of making two or more pairs heterozygous. In several cases, the presence of a single pair of heterozygous chromosomes may lead to a body size quite as large as in the fully heterozygous type, and actually exceeding the size of types with two heterozygous pairs. But, in one series, on the other hand, increase in the number of heterozygous pairs of chromosomes increases size more than the sum of the individual effects. 10. The results are discussed in relation to the mechanism of heterosis, inbreeding decline and possible ways in which selection has changed the genotype to produce small size.

Experimental Design for Testing Inbred Lines of Swine

In an unselected population, additive genetic differences between unrelated inbred lines are expected to average times as large as those between unrelated first generation linecrosses, 2 times those between topcrosses of unrelated inbred lines, and times those in comparisons of individual topcrosses of unrelated lines with outbred stock. As the homozygosity of the inbred lines increases, average differences between inbred lines approach a maximum which is times as large as average genetic differences between unrelated individuals in an outbred population, when all gene effects combine additively. Comparable maxima are 1 for linecrosses, for topcrosses, and for comparisons of individual topcrosses with outbred stock. Non-additive gene effects would make differences between groups larger, especially as the lines become more highly inbred. Prior selection, particularly elimination of inferior lines, would make differences between groups smaller, except in comparisons of individual topcrosses with outbred stock. Conclusions reached for swine breeding experiments concerned with weight of pigs at 180 days of age and the productivity of sows are as follows: The average numbers of animals necessary for the statistical significance of expected infra-herd and intra-season differences between two groups have the following approximate ratios to the numbers required for differences between two inbred lines: 1.5 for linecrosses; 2 to 3 for topcrosses; and about 4 for comparisons of individual topcrosses with outbred stock. For characters with as much environmental variation as weight and productivity, the homozygosity of the lines and the kind of comparison have little effect on the standard error of differences between groups and hence do not have much effect on the numbers required for the significance of a given absolute difference. When all gene effects combine additively, little further reduction in the average numbers required for the 5 or the 10 per cent level of significance is accomplished by advancing the inbreeding of the parents in unrelated lines beyond 20 to 30 per cent for comparisons between the inbred lines themselves, 30 to 40 per cent for those between linecrosses, and 40 to 50 per cent for those between topcrosses. For the 1 per cent level of significance, up to 20 per cent of additional inbreeding will accomplish appreciable further reduction in numbers required. Additional group differences due to dominance and epistasis increase in size as inbreeding progresses, so that numbers required would decline a bit more than this with further inbreeding. Inbred lines should be unrelated if maximum differences between lines are desired. Average differences between related lines are reduced to times what they would be between unrelated lines, where f is Wright's (1921) inbreeding coefficient for the lines and f0 is the average inbreeding which would result from mating animals of one line to those of another. Inter-line relationship reduces average differences between topcrosses, between linecrosses, and between individual topcrosses and outbred stock in the same proportion as those between inbred lines. About twice as many herd-season replications and considerably more work will be required to demonstrate significant differences in sow productivity than in 180-day weight, since productivity is less heritable than weight, and its observation is more expensive and is limited to less than half of the animals. In comparing groups having no parents in common, fewest litters are needed for statistical significance if no parent has more than one litter. However, the cost of sire service, the mating system, and other factors, will modify that in determining what experimental plan will provide significant results most economically.

Legislative Restrictions on Marketing Integration

The struggle of one type of business concern to protect itself against competitive encroachments either from new forms of business, or merely from additions to its ranks of more of the same type of competitors,1 is probably as old as man himself. For where self-interest resides, there one finds resourcefulness in the fashioning of protective weapons. And for each weapon that is removed, judicially or otherwise, from the hands of its fashioners, new ones spring forth from the fertile minds behind those hands. Even as early man devised tangible weapons to wield against encroaching competitors in the form of human or animal enemies who threatened his food supply, so the modern man eternally attempts to devise intangible weapons to wield against threats to his established form of livelihood. The man in the business of marketing goods or services today finds his livelihood threatened, among other ways, by the competition created through the evolution of those new forms of distribution achieved by the horizontal or vertical integration of previously separate products or functions. Horizontally, the threat to existing merchandising patterns takes the form of integration in one business unit, or under common ownership, of what might be designated as unrelated lines of business or merely as the marketing of many goods or services instead of one or a limited number. Through vertical integration, the old-line seller is faced with combination in one unit of either production and distribution or the various stages of the distribution process itself. To meet this competition, or the threat of it, resort is had to the legal weapon of protective legislation, though an attempt is made to disguise the real purpose in its use under the gaudy trappings of declarations that it is all done in the interest of protecting the public against practices dangerous to its health2 or practices promotive of monopoly.3 Such attack invites resistance, for the newly developing forms of dis* A.B., 1929, Goucher College; LL.B., 1932, Columbia University. Assistant Administrative Attorney, Marketing Laws Survey. 1 For a discussion of the efforts of business to protect itself against this form of competition, see Silverman, Bennett and Lechliter, Control by Licensing Over Entry into the Market, supra this issue, an example of which is the adoption by mere occupational groups (barbers and beauty culturists, and other service trades) of a professional status with concomitantly stringent requirements set up for entry therein. 2 See, infra, the discussion of legislation restricting the sale of food to food establishments, and the sale of drugs to registered pharmacists. 8 See, infra, the discussion of restrictions on the retail merchandising of appliances by public utilities, on the ownership of theaters by motion picture producers, and on the wholesaling of groceries by the meat-packing companies.