VI. Summary
The relations have been studied between (a) the tetrad exchange frequencies in theX-chromosome ofDrosophila melanogaster calculated by Weinstein (1936) from strand cross-over data of Bridges (1935b), and (b) distances along the salivary maps of theX-chromosome (Painter, 1934a; Bridges, 1935a). It has been found that:
(1) Theaverage position of the exchange, in tetrads where only one exchange occurs, is approximately the midpoint of the chromosome.
(2) The average positions of the left and right exchanges, in tetrads where two exchanges occur, are approximately the midpoints of the left and right halves of the chromosome.
(3) For any particular position of one exchange, in two-exchange tetrads, the average distance to the next exchange is about five-eighths of the total distance beyond the first exchange.
(4) The average positions of the exchanges in three-exchange tetrads are approximately the midpoints of the left, central and right thirds of the chromosome.
(5) The general characteristics of the relation between exchange frequency and chromosome position are fairly well reproduced by Pearson Type II smooth distributions of the general form,y=x 2 (1 −x)2, wherey represents the relative frequency of exchange in a short chromosome section andx and (1 −x) the distances from the section to the chromosome ends or adjacent exchange points.
(6) The data used do not support the conclusion of Mather (1936) that there is a temporal seriation in the formation of chiasmata, starting at the spindle attachment point.
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References
Anderson, E. G. &Rhoades, M. M. (1931).Pap. Mich. Acad. Sci. 13, 227–39.
Bridges, C. B. (1916).Genetics,1, 1–52, 107–63.
—— (1935a).J. Hered. 26, 60–4.
Bridges, C. B. InMorgan, T. H., Bridges, C. B. &Schultz, J. (1935b).Yearb. Carneg. Inst. 34, 287.
Demerec, M. InMorgan, T. H., Bridges, C. B. &Schultz, J. (1935).Yearb. Carneg. Inst. 34, 289.
Demerec, M. &Hoover, M. E. (1936).J. Hered. 27, 207–12.
Gowen, J. W. (1933).Genetics,18, 1–31.
Mackensen, O. (1935).J. Hered. 26, 163–74.
Mather, K. (1936).J. Genet. 33, 207–35.
Morgan, L. V. (1933).Genetics,18, 250–83.
Morgan, T. H. (1911).J. Exp. Zool. 11, 365–413.
Muller, H. J. (1916).Amer. Nat. 50, 421–34.
Muller, H. J. &Painter, T. S. (1932).Z. indukt. Abstamm.-u. VererbLehre,62, 316–63.
Offermann, C. A., Stone, W. S. &Muller, H. J. (1931).Anat. Rec. 51, 109.
Offermann, C. A. &Muller, H. J. (1932).Proc. VI Int. Cong. Gen. 2, 143–5.
Painter, T. S. (1934a).Genetics,19, 448–69.
—— (1934b).J. Hered. 25, 465–76.
Sax, K. (1932).J. Arn. Arbor. 13, 180–212.
Schultz, J. InMorgan, T. H., Bridges, C. B. &Schultz, J. (1935).Yearb. Carneg. Inst. 34, 289.
Schweitzer, M. D. (1935).Genetics,20, 497–527.
Stone, W. S. &Thomas, I. (1935).Genetica,17, 170–85.
Sturtevant, A. H. (1913).J. Exp. Zool. 14, 43–59.
Weinstein, A. (1928).Anat. Rec. 41, 109–10.
—— (1932).Proc. VI Int. Cong. Gen. 2, 206–8.
—— (1936).Genetics,21, 155–99.
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National Research Fellow in Zoology (1935–6). Part of the present study was done during tenure of the Columbia University Fellowship in Zoology (1933–4) and of working space in the Department of Genetics of the Garnegie Institution of Washington (summer 1935) for which the writer is grateful to the Trustees and Council of Columbia University and to the Carnegie Institution, respectively.
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Charles, D.R. The spatial distribution of cross-overs inX-chromosome tetrads ofDrosophila Melanogaster . Journ. of Genetics 36, 103–126 (1938). https://doi.org/10.1007/BF02982376
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DOI: https://doi.org/10.1007/BF02982376