Internal Changes in Hyphae of Rhizopus sexualis (Smith) Callen and Mucor hiemalis Wehm. associated with Zygospore Formation

The distribution of nucleic acids, nuclei, mitochondria, andreserve foods in vegetative hyphae, zygophores, and developingzygospores of Rhizopus sexualis and Mucor hiemalis were examinedby differential staining. The extreme tips and growing zones of vegetative hyphae containeda high concentration of RNA and numerous mitochondria. Nucleiwere not present at the extreme tip but were numerous just behindit. In older parts of the hyphae the concentration of RNA waslow and both nuclei and mitochondria were fewer than in thezone of elongation. Glycogen and lipids were present in all parts of the livinghyphae except the extreme tips and were more highly concentratedin the older parts of the hyphae. Young zygophores showed a much lower RNA/DNA ratio than thatfound in the vegetative hyphal tips. Transfer of colonies from20? C to temperatures of less than 10? C, which is known toprevent zygospore initiation, caused some but not all recognizablezygophores of R. sexualis, but not those of M. hiemalis, torevert to the RNA/DNA ratio characteristic of vegetative hyphae.Some zygophores of Rhizopus and most of those of Mucor developedinto sporangiophores at low temperature, retaining the relativelylow RNA/DNA ratio throughout development. It is suggested thata reduction in the RNA/DNA ratio is an early step in the changefrom the vegetative state to the reproductive one. At firstthis step is reversible, but soon becomes irreversible by anadditional step, the nature of which is unknown. For some timeafter this the reproductive hyphae are capable of either producingasexual sporangia or of conjugating to produce zygospores. Onceconjugation has taken place development either ceases or continuesuntil the spore is fully mature, but it cannot under any circumstancesthen be reversed. The development and maturation of the zygospore involves a greatincrease in number of both nuclei and mitochondria and in theconcentration of glycogen and lipids.     

Effect of inhibitors of nucleic acid and protein synthesis on the reappearance of "light interruption rhythm" in a long-day duckweed, Lemna gibba G 3

Effects of several inhibitors of DNA, RNA and protein synthesison the reappearance of a once faded-out light interruption rhythmin a long-day duckweed, Lemna gibba G 3, were studied. The reappearancewas not affected by inhibitors of RNA and protein synthesis;i.e., 2-thiouracil, 8-azaguanine, ethionine and chloramphenicol,but was suppressed by inhibitors of DNA synthesis; i. e., 5-fluorodeoxyuridine,5-fluorouracil and mitomycin C only when these were appliedduring the light period for perturbation. We concluded that synthesis of a new DNA species during thelight period was required for the recurrence of this rhythm. (Received September 25, 1968; )     

The Behaviour of Nucleic Acids and Other Constituents in Protomyces inundatus Dangeard

Estimations of contents per cell of DNA and RNA were made inProtomyces inundatus. There was twice as much DNA per cell incultures derived from fusion bodies and from mycelium in thehost (Apium nodiflorum) as in those derived from unfused endospores,indicating that the former two were diploid, the latter haploid.Dry weight/cell, volume/cell, insoluble nitrogen/cell, and metaphosphate/cell,like RNA/cell, had similar values for all three types of cultures.Giant cells resulting from camphor treatment not only had twiceas much DNA/cell as normal cultures derived from unfused endospores,but all the other characteristics studied had doubled as well.In any one culture the ratio of RNA to DNA remained constantthough the absolute values decreased as the cultures aged. TheRNA to DNA ratios in P. inundatus of haploid and diploid culturesare compared to those found in yeast and other organisms.     

Leaf Nucleic Acids:: II. METABOLISM DURING SENESCENCE AND THE EFFECT OF KINETIN

The nucleic acids in the green and in the senescent leaves ofthree types of plant have been studied. High and low molecularweight RNA of the chloroplast is not present in senescent leavesof Xanthium pensylvanicum, but both cytoplasmic and chloroplasticfractions are found in yellow leaves of Vicia faba and Nicotianatabacum. RNA is more rapidly degraded than DNA in the leavesof these plants when they are detached, and kinetin treatmenttemporarily arrests the loss of chlorophyll and nucleic acid.Once X. pensylvanicum leaves are yellow and senescent they cannotbe re-greened, whereas those of Nicotiana spp., and to someextent those of V. faba, can be rejuvenated. We suggest thatthe retention of chloroplast RNA in yellow leaves may be a majorfactor determining their ability to re-green and that the patternof organelle senescence prior to the first stages of leaf autolysisand dehydration is species-specific.     

Studies on nucleic acids in plastids of the pigment mutant C-2A{acute} of Scenedesmus obliquus

Pigment mutant C-2A{acute} of Scenedesmus obliquus whose chlorophyllformation and chloroplast development are light dependent, wasstudied for the nucleic acid content of its plastids. The ribosomalRNA of plastids of the achlorophyllous or greened mutant C-2A{acute},did not show any difference from that of the wild type. Incorporationof [5-³H] uridine into mutant cells was partially inhibitedby rifampicin, indicating this part as being plastidial incorporation.Since there were no significant differences in the ribosomalRNA of plastids between the mutant and the wild type of Scenedesmus,the ribosomal system in the plastids of mutant C-2A' seemednot to be affected by the mutation. C_sCl gradient patterns ofScenedesmus mutant and wild-type DNA were almost identical withthose of Chlorella DNA. A peak at a buoyant density of 1.69g/cm³, the same as that of Chlorella chloroplast DNA, couldbe identified in Scenedesmus also as plastid DNA because itdisappeared after prolonged treatment with myxin and hybridizedwith rifampicin-sensitive pulse-labelled RNA. This peak waspresent to nearly the same degree in the mutant and the wildtype, indicating that a larger deficit of plastid DNA did notoccur in the mutant. Whether or not the mutation might be localizedin the plastid genome is discussed. (Received March 19, 1976; )     

RNA synthesis required for DNA replication in Vicia seed embryos

The synthesis of DNA and RNA during germination of Vicia seedswas examined. Incorporation of ³H-thymidine into DNA reacheda maximum at about 32 hr after the beginning of imbibition,and RNA synthesis was shown to precede DNA replication. Sedimentationanalyses of ³H-uridine-labeled RNAs indicated that the embryossynthesize all types of rRNA, heterodisperse RNA and 4–5SRNA before and also during the phase of DNA replication. Actinomycin-treatments at lower concentrations (50 or 100 µg/ml)resulted in the specific inhibition of rRNA synthesis. Suchinhibition did not lead to a large reduction in ³H-thymidineincorporation during the replication phase. However, DNA synthesiswas drastically inhibited by a higher level (200 µg/ml)of actinomycin D. The results strongly suggest the involvementof synthesis of heterodisperse RNA in DNA replication. (Received May 28, 1976; )     

Effect of UV-Irradiation on Total Protein and Nucleic Acids in Alternaria alternata and Fusarium solani

UV-A^* irradiation caused increases in total protein in Fusariumsolani, while its effect on Alternaria alternata was variable,and not as clear-cut as in F. solani. On the other hand, UV-Birradiation stimulated protein production in both fungi. UV-Airradiation showed an inhibitory effect on total DNA in bothfungi, while the effect on RNA was stimulatory in F. solanibut had no effect on A. alternata. Short fluences of UV-B inhibitedDNA production to some extent in both fungi, however longerfluences increased DNA content especially in F. solani. Theeffect of UV-B on RNA production was inhibitory in F. solanibut not in A. alternata. A. alternata is much more resistantto UV-irradiation than is F. solani, and increases in proteinin the former after UV-irradiation suggests that protein mayplay a part in protection against the harmful effect of UV-irradiation. UV-A, UV-B, fluence, protein, nucleic acids, Alternaria alternata, Fusarium solani     

Ribonuclease-P RNA Gene of the Plastid Chromosome from Cyanophora Paradoxa

The gene, rnpB, encoding the RNA portion of ribonuclease-P hasbeen found in the cyanelle DNA of Cyanophora paradoxa. A secondarystructure model for the cyanelle RNA fits into that for eubacterialRapb-RNAs.     

Evidence for a Discriminatory Action of Androgenic Steroids on the Synthesis of Nucleolar Ribonucleic Acids in Prostatic Nuclei

Testosterone, when injected into castrated rats, enhances theRNA-synthesizing activity of isolated prostatic nuclei. Thenearest-neighbor frequency and base composition of RNA synthesizedunder the influence of androgens are completely different fromthose of control castrates. These effects of androgens in vivocan be abolished by low concentrations of actinomycin D addedto the RNA-synthesizing systems or injected into the experimentalanimals. Only about 1% of total prostatic nuclear chromatinparticipates in the synthesis of RNA by prostatic nuclei ofcontrol castrated rats. The androgen-provoked enhancement ofRNA-synthesis occurred at a separate and small (1% or less)region of nuclear DNA. The androgen-sensitive region of DNAhas a strikingly high content of deoxycytidylyl (3',5')-deoxyguanosinedinucleotide sequence: 24 and 2 times, respectively, that ofpurified rat DNA and of the DNA region which functions as templatefor RNA-synthesis after animals are deprived of androgens. Fromthe available information, it was concluded that androgen selectivelyenhanced the synthesis of RNA at nucleolar and/or perinucleolarregions of prostatic chromatin.     

Does 5-fluorodeoxyuridine inhibit growth by indirectly inhibiting RNA synthesis?

5-Fluorodeoxyuridine (FdUrd), a specific inhibitor of DNA synthesis,inhibits elongation growth in the cucumber hypocotyl. It alsoinhibits both DNA and RNA synthesis, as measured by incorporationof labelled precursors. Possible changes in internal pools orinhibition of RNA synthesis by conversion of FdUrd to 5-fluorouracil(FU) have been ruled out. The possible implications of these findings are discussed. (Received February 13, 1973; )     

SPECIFIC RNA FROM PHOTOPERIODICALLY INDUCED COTYLEDONS OF PHARBITIS NIL

The nucleotide ratio of several RNA species from cotyledonsof Pharbitis nil subjected to a single 16 hr night with or withouta 15 min light-break, or to continuous light was investigated.RNA species examined were RNAs from nuclear, mitochondrial,microsomal, and supernatant fractions separated by differentialcentrifugation, and s-, r-, and m-RNAs fractionated by methylatedalbumin column chromatography. Of the RNAs examined, m-RNA alone was found to change its nucleotideratio with photoperiod applied. Thus as compared with m-RNAfrom non-induced cotyledons (exposed to continuous light oran interrupted night), m-RNA from cotyledons induced by an uninterruptednight contained significantly reduced guanylic and cytidylicacids on molar ratio basis. A working hypothesis was proposed that floral stimulus productionin cotyledons may be directed by gene DNA derepressed photoperiodically. (Received October 18, 1966; )     

Focused Microarray Analysis of Peripheral Mononuclear Blood Cells from Churg-Strauss Syndrome Patients

DNA diagnostics are useful but are hampered by difficult ethicalissues. Moreover, it cannot provide enough information on theenvironmental factors that are important for pathogenesis ofcertain diseases. However, this is not a problem for RNA diagnostics,which evaluate the expression of the gene in question. We herereport a novel RNA diagnostics tool that can be employed withperipheral blood mononuclear cells (PBMCs). To establish thistool, we identified 290 genes that are highly expressed in normalPBMCs but not in TIG-1, a normal human fibroblast cell. Thesegenes were entitled PREP after predominantly expressed in PBMCand included 50 uncharacterized genes. We then conducted PREPgene-focused microarray analysis on PBMCs from seven cases ofChurg–Strauss syndrome (CSS), which is a small-vesselnecrotizing vasculitis. We found that PREP135 (coactosin-likeprotein), PREP77 (prosaposin), PREP191 (cathepsin D), PREP234(c-fgr), and PREP136 (lysozyme) were very highly up-regulatedin all seven CSS patients. Another 28 genes were also up-regulated,albeit more moderately, and three were down-regulated in allCSS patients. The nature of these up- and down-regulated genessuggest that the immune systems of the patients are activatedin response to invading microorganisms. These observations indicatethat focused microarray analysis of PBMCs may be a practical,useful, and low-cost bedside diagnostics tool.     

Effects of Benzyladenine on Chlorophyll, DNA, RNA and Protein Content of Attached Young Bean (Phaseolus vulgaris L.) Leaves

N⁶-Benzyladenine (BA) was applied to intact bean (Phaseolusvulgaris L.) primary leaves at 2 and 6 days after imbibition,when they were in the cell division and post-cell division stages,respectively. BA treatment at day 2 temporarily inhibited an increase in chlorophyllcontent in the following day, but stimulated it in later days.No such inhibition by BA was observed for changes with timein DNA, RNA, and protein content and f. wt. On the other hand,BA treatment at day 6 enhanced RNA and protein content, withoutsignificant influence on DNA and chlorophyll content and f.wt. The mode of cytokinin action on greening in leaves during cell-divisiongrowth seems to be different from that in etiolated cotyledons. Phaseolus vulgaris L., bean, greening, benzyladenine, DNA, RNA, protein     

A Cytochemical Study of DNA, RNA, and Protein in the Developing Maize Anther: II. Observations

Changes in acetic-alcohol fixable DNA, RNA, and protein werefollowed in the tapetum, sporogenous tissue, and spores of thedeveloping maize anther using standard cytochemical methodsand microdensitometry. In the tapetum, early nuclear divisionsoccur without prior DNA synthesis, giving a population of IC nuclei. Subsequent synthesis produces the equivalent of 34,000C amounts per pollen sac, 20 times more than is present in thespores before pollen mitosis. The main tapetal RNA synthesisis during the meiotic prophase, with a further period of accumulationin the interval, tetrad to young spores. In the meiocytes, theprincipal accumulation is in the early prophase, with no synthesisduring the meiotic divisions or through the tetrad period. Proteinaccumulation occurs in the tapetum up to mid-meiotic prophase;after this there is a pause, followed by further synthesis frommeiotic metaphase I to the final dissolution of the tissue.In the meiocytes, protein is accumulated through the early prophase;there is no synthesis during the meiotic mitoses or in the tetradperiod, but active accumula-tion occurs in the developing spores. The implications of these observations are discussed in relationto the function of the tapetum.     

Two Phases in Adventitious Root Formation in Phaseolus mungo Hypocotyl Cuttings, a Phase Sensitive to an Inhibitor of RNA or Protein Synthesis and a Phase Sensitive to an Inhibitor of DNA Synthesis

The development of adventitious roots in Phaseolus mungo cuttingswas inhibited by 2-thiouracil, cycloheximide, and 5-bromodeoxyuridine.The stage of rooting blocked by 2-thiouracil and cycloheximidewas different from that blocked by 5-bromodeoxyuridine. Somecell division in the basal rooting region occurred with 5-bromodeoxyuridine,but not with 2-thiouracil and cycloheximide. Radioactivity from labelled 2-thiouracil appeared in RNA fractionsbut the amount was reduced by simultaneously applied uracil.5-Bromodeoxyuridine inhibited incorporation of thymidine intoDNA fractions. 2-Thiouracil and 5-bromodeoxyuridine act as antimetabolitesof uracil and thymidine, respectively. Cycloheximide, an inhibitorof protein synthesis, prevented the incorporation of radioactivityfrom labelled leucine into the trichloroacetic acid-insolublefraction. RNA synthesis inhibitors (2-thiouracil and actinomycin D) andprotein synthesis inhibitors (cycloheximide and blasticidinS) increased roots effectively when dosed at the beginning ofincubation. Inhibitors of DNA synthesis (5-bromodeoxyuridineand mitomycin C) were effective when applied after several hours'pre-incubation in water. It is suggested that there are at leasttwo phases in adventitious root formation, a phase sensitiveto an inhibitor of RNA or protein synthesis and a phase sensitiveto an inhibitor of DNA synthesis.     

Effect of aluminium on some properties and template activity of purified pea DNA

In order to study the mechanism of aluminium(Al)-induced inhibitionof root elongation, DNA was purified from Alaska pea seedlingsand some physical properties and template activity supportedby E. coli RNA polymerase were measured in the presence of Al.The absorption spectrum of the DNA did not shift, indicatingthat Al might bind to the DNA phosphate. While the Tm (meltingtemperature) of DNA was not affected by Al, the rate of hyperchromicitywas reduced with increasing concentrations of Al. The templateactivity of the DNA was clearly suppressed by the amount ofAl which was needed for the reduction of hyperchromicity. (Received September 9, 1977; )