Showing papers in "Proceedings of the National Academy of Sciences of the United States of America in 1939"

The Behavior in Successive Nuclear Divisions of a Chromosome Broken at Meiosis

Abstract: After reporting her observations of ring chromosomes, McClintock followed broken chromatids through successive cycles of cell division, in which she could observe the behavior of the "monstrous" chromosome 9 through meiosis and crossing-over. McClintock reported in a long series of articles that the chromatid breakage-fusion-bridge (BFB) cycle occurred only in the germ cells and endosperm, while the chromosome BFB continued in the sporophyte, which meant that she could selectively produce persistent variegation in plant tissues.

Solution of the Inverse Problem of the Calculus of Variations

Abstract: Our essential results and methods have already been published in two preliminary notes('). Basically, our procedure consists in an application of the Riquier theory of systems of partial differential equations to a certain linear differential system e on which the inverse problem can be made to depend. This differential system has already appeared-derived in a different way-in the interesting work, of little more than a decade ago, by D. R. Davis on the inverse problem(2); but, as he stated, its general solution-even existence-theoreticallypresented difficulties which he could not overcome.

High Mutation Frequency Induced by Hybridization.

Abstract: The increase in variability that is a familiar result of the rearing of second generations from crosses between different races is certainly due chiefly to segregation and recombination of genes in which the parental races differed. There is, however, a persistent feeling that perhaps interracial crossing also induces the production of new mutations. The first attempt to test this view experimentally with Drosophila led to negative results (Duncan 1915). Belgovsky (1937) reported an increased frequency of somatic mutations in the hybrids between D. melanogaster and D. simulans, in x-ray experiments. The differences reported were not very striking, and in any case have little bearing on questions concerning spontaneous frequencies.

On the Subdivision of the Genus Drosophila.

Abstract: There is now in progress in several laboratories a comparative study of the genetics of the species of Drosophila Several authors have pointed out possible deductions concerning the history of the group that may be derived from such studies (eg, Donald 1936, Sturtevant and Tan 1936, Serebrovsky 1938) If such deductions are to be of value, it is desirable that there be available a satisfactory arrangement of the species into some scheme of classification that can be taken as indicating their degree of genetic relationship It is the purpose of this note to present the results of an attempt to derive a classification by a method as free of personal equation as it can be made

On the Gaussian Law of Errors in the Theory of Additive Functions

Abstract: In the present note we state without proofs some results concerning additive functions, the proofs of which depend partially on statistical methods. A function f(m) is called additive if for (ml, m) = 1 one has f(mr*ms) = f(mr) + f(mz). We assume furthermore that fw) = f(ip) and 1 f&) 1 < 1 for every prime p. None of these assumptions is essential but they simplify the statement of Theorem A.’ THEOREM A. iht f($) be S&Z thut

The Wound Hormones of Plants: II. The Isolation of a Crystalline Active Substance.

Abstract: The existence of plant "wound hormones" has been recognized since the formulation of the wound hormone concept by Wiesner (1) and the demonstration by Haberlandt (2) of the diffusible nature of the active principles. It was shown by these early investigators that there are formed or liberated at injured surfaces of plant tissues water-soluble substances which are capable of evoking renewed growth activity in mature uninjured cells or tissues. In the present paper the isolation from plant material of a crystalline substance possessing typical "wound hormone" activity will be described.

Nuclease Action, Protease Action and Histochemical Tests on Salivary Chromosomes of Drosophila.

Abstract: There is considerable evidence for the presence of both nucleic acids and proteins in the salivary gland chromosomes of certain diptera The socalled "euchromatic" bands stain intensely after application of the FeulgenRossenbeck technique, which is a fairly specific test for the pentose of animal nucleic acids The heterochromatic regions also give a weak reaction, and the boundaries between the bands are not sharp' Caspersson2 found that the material of the euchromatic bands had a similar ultra-violet

Leaf Growth Factors II-The Activity of Pure Substances in Leaf Growth.

Abstract: It was shown by Went(7) that leaf growth in etiolated pea seedlings is primarily controlled by substances supplied from the cotyledons. Vein growth is controlled by auxin,(2) while growth of the mesophyll is independent of auxin, and it is the factors concerned in the growth of the latter which we will discuss in this paper. In a recent paper(3) a bio-assay for these factors was described in detail, as well as a variety of sources, and so will be discussed only briefly here.

Crystalline Echinochrome and Spinochrome: Their Failure to Stimulate the Respiration of Eggs and of Sperm of Strongylocentrotus.

Abstract: The blood cells (elaeocytes) of sea-urchins contain a red pigment to which MacMunn' gave the name echinochrome. McClendon2 found that this pigment is also present in the test and, in the species Arbacia punctulata, in the eggs as well. Cannan3 showed that it could be reversibly oxidized and reduced. VlWs and Vellinger4 made use of it (called it Arbacine) as a natural pH indicator in the eggs of Arbacia. Stern6 (referring to unpublished data) considers it to be bound as a chromoprotein in the blood cells. The present author's interest in echinochrome arose from Friedheim's6 report that it would cause a-16-fold increase in the respiratory rate of unfertilized sea-urchin (Strongylocentrotus lividus) eggs. In view of the magnitude of the reported effect and the fact that the substance is a naturally occurring pigment, it seemed desirable to examine its action on fertilized sea-urchin eggs. This was of especial interest in connection with studies7 on the energetics of development. However, my attempts to duplicate Friedheim's results on unfertilized sea-urchin eggs have proved unsuccessful. Friedheim did not give in his articles the method of preparation except to state that he extracted the tests of Sphaerechinus granularis with sea water. In the present work sea water extracts of Strongylocentrotus purpuratus were found to be inactive. The material was then prepared in crystalline form, and the purified echinochrome also was found to have no stimulating effect on the respiration of sea-urchin eggs. Recently another effect has been attributed to echinochrome: Hartmann, Schartau, Kuhn and Wallenfels8 have announced that it is the substance causing activation and chemotaxis of the spermatozoa in Arbacia pustulosa. They state that the limit of physiological activity lies at a dilution of 1:2,000,000,000. On examination of the action of purified echinochrome on the sperm of Strongylocentrotus purpuratus I have found no such action as Hartmann, et al., reported for Arbacia. The crystallization of echinochrome was first reported by Ball.9 It was also crystallized by Lederer and Glaser10 who, though evidently unacquainted with Ball's brief abstract, assigned to it the same empirical formula, C12H1007. Lederer and Glaser also obtained another pigment which they call spinochrome and which differs from echinochrome in containing one more atom of oxygen. By a similar procedure I was able to obtain VOL. 25, 1939 523