Inducing sporulation in Alternaria solani II. Effect of light

Among the three different light sources viz. incandescent electric light, infra-red light and sunlight, only sunlight was effective in inducing sporulation in petri dish cultures ofA. solani. The intensity of sporulation depended upon the age and growth stage of the cultures, duration and number of exposures to light and the presence or absence of a sporulating zone in the culture. Maximum sporulation was obtained in the case of 6 days old partially grown cultures by inducing the formation of sporulating zone which appeared in 24 hours after every exposure of 60 minutes to sunlight.     

Effect of zinc on increasing oxygen affinity of sickle and normal red blood cells

We have hypothesized a state of zinc deficiency in sickle cell disease (SCD). This could at least partially explain the growth problems, hypogonadism, and slow healing leg ulcers associated with SCD. Preliminary findings revealed abnormally low red blood cell zinc levels in 10 of 16 patients studied. Before suggesting zinc supplementation in SCD we thought it important to look at the effect of zinc on red cell metabolism and function. It was found that zinc chloride added to normal and SCD blood to a final concentration of 1.5 × 10^?3 M caused a left-shift of the blood oxygen affinity curve (increased oxygen affinity) varying from 1.5 to 3.5 mm Hg change in half saturation (p50). This curve shifting property has important implications for SCD since recent work with cyanate suggests that such shifts are very beneficial in treatment of SCD. Thus zinc supplementation in SCD, in addition to its potential role in correcting wound healing and growth problems, may have a beneficial effect on the basic pathological process. Data are given which suggest that zinc and 2, 3-diphosphoglycerate may not be competing for the same site on the hemoglobin molecule.     

Cell cycle analysis and DNA aneuploidy in autoimmune mice homozygous for the lpr and gld mutations.

Homozygosity for either of the mutations lpr (lymphoproliferation) or gld (generalized lymphoproliferative disease) in mice results in lymphoproliferation and autoimmune disease. To investigate the site and time of excessive lymphocyte proliferation in these mice, cell nuclei of normal and mutant mice of various ages were stained with propidium iodide and DNA profiles were analyzed by flow cytometry. Two major results were obtained. First, DNA aneuploidy was observed in the lymph nodes and spleen of these autoimmune mice and the cells involved in DNA aneuploidy were predominantly of a CD4-CD8- Thy-1- surface phenotype. Second, although DNA aneuploidy became apparent in mutant mice at 2 mo of age, the numbers of cycling cells were only minimally increased over control levels at all ages tested. Thus, the massive cellular accumulation in the lymph nodes of lpr and gld mice does not seem ascribable solely to excess cell proliferation in these tissues. Moreover, a previously unrecognized cell compartment (CD4-CD8-Thy-1-) characterized by apparent DNA aneuploidy appears in the same tissues and at the same times that the predominant "double negative" (CD4-CD8-Thy-1+) T cell subset accumulates.     

Evolutionarily conserved regions in Caenorhabditis transposable elements deduced by sequence comparison.

In this paper we present the sequence of an intact Caenorhabditis briggsae transposable element, Tcb2. Tcb2 is 1606 base pairs in length and contains 80 base pair imperfect terminal repeats and a single open reading frame. We have identified blocks of T-rich repeats in the regions 150-200 and 1421-1476 of this element which are conserved in the Caenorhabditis elegans element Tc1. The sequence conservation of these regions in elements from different Caenorhabditis species suggests that they are of functional importance. A single open reading frame corresponding to the major open reading frame of Tc1 is conserved among Tc1, Tcb1, and Tcb2. Comparison of the first 550 nucleotides of the sequence among the three elements has allowed the evaluation of a model proposing an extension of the major open reading frame. Our data support the suggestion that Tc1 is capable of producing a 335 amino acid protein. A comparison of the sequence coding for the amino and carboxy termini of the 273 amino acid transposase from Caenorhabditis Tc1-like elements and Drosophila HB1 showed different amounts of divergence for each of these regions, indicating that the two functional domains have undergone different amounts of selection. Our data are not compatible with the proposal that Tc1-related sequences have been acquired via horizontal transmission. The divergence of Tc1 from the two C. briggsae elements, Tcb1 and Tcb2, indicated that all three elements have been diverging from each other for approximately the same amount of time as the genomes of the two species.     

Mutagenic activity of antibiotics alone and in conjunction with alkanesulfonates

Differential and combined effects of 0.25 and 0.50% antibiotics (ampicillin, neomycin, furadentine) and alkylating agents (ethyl methanesulfonate, methyl ethanesulfonate, methyl methanesulfonate) were assayed on Phaseolus vulgaris L. (2 n = 22) at the M₂ generation for chlorophyll mutations. The general types scored were Albino, Xantha, Virescens and Maculata. Yellowish-green leaves having red mid-veins and veinlets were observed only amongst the progeny raised after treatment with 0.25% ethyl methanesulfonate or 0.25% methyl ethanesulfonate + 0.25% ampicillin. The frequency of chlorophyll mutation after combined treatments in general was higher than after differential treatments. Methyl methanesulfonate among alkanesulfonates and neomycin among antibiotics induced higher frequencies of chlorophyll mutations. No chlorophyll mutant was produced by ampicillin.Although antibiotics induced a lower frequency of chlorophyll mutation than alkylating agents, the frequency and pattern of spectra of chlorophyll mutants showed an action of antibiotics in inducing mutation similar to that of alkylating agents. Therefore, it is considered that antibiotics are potential mutagens.