MICROSPECTROPHOTOMETRIC ANALYSIS OF NUCLEAR DNA IN CHARA ZEYLANICA

Microspectrophotometric analysis of the DNA content of nuclei in various parts of Chara zeylanica Willd. revealed that the amount of DNA in the nucleus of an internodal cell equals twice the amount of DNA in the nucleus of a sperm, while the half-anaphase stage of the same nodal cells contains the same amount of DNA as the nuclei of the male gametes. The DNA content of the nuclei of internodal cells may rise as much as 50 times higher than that of the gametes. However, in the oldest (most basal) internodal cells, the DNA content of the minute nuclei falls again to the basic (1 C) amount. Measurements of sister nuclei derived by amitosis indicated that both nuclei have equal amounts of DNA; this was interpreted as further evidence that amitosis is not a disorganized process or manifestation of degeneration. The bearing of these analyses on the question of the site of meiosis in these plants is discussed.     

THE NUCLEIC ACIDS OF BASAL BODIES ISOLATED FROM TETRAHYMENA PYRIFORMIS

Pellicular fragments were isolated from ethanol-fixed cells of the holotrichous ciliate Tetrahymena pyriformis by the action of digitonin. The isolated pellicles were further fragmented and the basal bodies of the cilia isolated from them by three methods. The preparations, examined in the electron microscope as embedded sections or negatively stained samples, consisted mainly of somewhat deformed pellicular material, the bulk of which was basal body. DNA was determined by the diphenylamine method and by reaction with DNase, and RNA, by the orcinol method. Nucleic acids were isolated by phenol extraction and analyzed spectrophotometrically and by reaction with RNase. The assays indicated 1.2 to 2.6 per cent RNA, similar to previously published work, but only 0.0 to 1.0 per cent DNA, near enough the sensitivity limits to render the presence of DNA in the preparations uncertain. Although the isolation procedure removed nuclear contents and ribosomes, the nucleic acids could still be a residual contaminant bound to the pellicle during the isolation. Hypotheses of basal body self-duplication, moreover, can be constructed both with and without nucleic acids.     

Acute Appendicitis

Acute appendicitis still is a cause of considerable morbidity and now and then of death. The diagnostic accuracy in 316 patients operated on for acute appendicitis at Holy Cross Hospital was 76 per cent. In 24 of 239 cases of proved acute appendicitis, perforation had occurred, and the morbidity in those cases was three times that in the cases without perforation. Review of the cases did not reveal any clear-cut diagnostic criteria that might be used to predict perforation.A study of 30 patients with mesenteric lymphadenitis who were inadvertently operated on in the belief they had appendicitis, revealed that this condition is most likely to occur in young females with only a slight increase in the number of leukocytes. Although positive diagnosis of acute appendicitis is a difficult problem, the morbidity associated with needless operation is so much less than that which occurs in acute perforated appendicitis, that prompt exploration in any questionable case seems warranted.