A COMPARISON OF THE CHANGES IN FINE STRUCTURE OF L CELLS DURING SINGLE CYCLES OF VIRAL MULTIPLICATION, FOLLOWING THEIR INFECTION WITH THE VIRUSES OF MENGO AND ENCEPHALOMYOCARDITIS

The virus of encephalomyocarditis (EMC), examined by the negative-contrast method, is indistinguishable from the serologically related Mengovirus. The particles are 270 to 280 A in diameter. The surface of EMC is composed of an undetermined number of subunits. Frequent sampling of infected cells was carried out throughout one-step cycles of viral multiplication to observe cytopathic changes occurring in L cells infected by these two related RNA viruses. EMC and Mengovirus, which multiply at equal rates, in most respects elicit similar alterations in cell fine structure. Rearrangement and changes in nuclear material accompanied by formation of small vesicles in the centrosphere region commence at 4 to 6 hours after infection. Thereafter a progressive degeneration of the nucleus and vesiculation of the cytoplasm are observed up to 18 to 20 hours. Increased numbers of small dense granules, indistinguishable from ribonucleoprotein particles, appear in the cytoplasm between 8 and 14 hours after infection. L cells infected with Mengovirus become permeable to Erythrocin more slowly than those infected with EMC. Only in the case of Mengovirus infection are large aggregates of dense material first observed in the cytoplasm at 8 hours, followed by the appearance of crystals probably composed of Mengovirus particles, at 12 hours. Differences in the rates of cell permeability after infection with EMC and Mengovirus are discussed in relation to formation of virus crystals and plaque-type mutants.     

THALASSIOMYCETES II. NEW GENERA AND SPECIES OF DEUTEROMYCETES

Meyers , Samuel P. (U. Miami, Coral Gables, Fla.) and Royall T. Moore . Thalassiomycetes II. New genera and species of Deuteromycetes. Amer. Jour. Bot. 47(5) : 345-349. Illus. 1960.–On the basis of taxonomic studies, 3 new monotypic thalassic genera are erected. These are: Cirrenalia, type C. macrocephala (=Helicoma macrocephala Kohlmeyer) ; Cremasteria, type C. cymatilis; Culcitalna, type C. achraspora . Also described is a new species of Humicola, H. alopallonella, which constitutes the first report of this genus from the marine environment.     

Ein Beitrag zur Biosynthese und Physiologie von Kaffein und Trigonellin beiCoffea arabica

Summary Whole young plants were allowed to fix photosynthetically C¹⁴O₂ for 12 hours. The absolute amount and the specific activity of trigonelline, caffeine and glucose in developing and adult leaves were subsequently determined during up to five weeks. There is a rapid incorporation of photosynthetically fixed carbon into trigonelline in both developing and adult leaves. The specific activity of caffeine however increases to any extent only in young developing leaves. It can be concluded that both trigonelline and caffeine are synthesized in leaves ofCoffea arabica. Other problems of the metabolism and translocation of the two substances are discussed.

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Aspects of the life cycle of marine nematodes

Summary 1. Life cycles of approximately one month are recorded for laboratory maintained cultures of chromadorid, monhysterid and oncholaimid nematodes.2. Amphimictic and parthenogenetic reproduction occurs in the species investigated. Reproduction inMonhystera parelegantula is by parthenogenesis.3. The chromadoridChromadorina epidemos and the oncholaimidViscosia macramphida are able to reproduce by either amphimixis or parthenogenesis.4.Acanthonchus cobbi, Chromadora macrolaimoides andEuchromadora gaulica are amphimitically reproducing species.

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Aspekte des Lebenszyklus mariner Nematoden

Kurzfassung Bei einigen marinen Nematoden, die in Biscayne Bay (Florida) gesammelt und im Labor gezüchtet worden sind, vollzieht sich der gesamte Lebenszyklus ungefähr innerhalb eines Monats. BeiAcanthonchus cobbi, Chromadora macrolaimoides undEuchromadora gaulica ist zweigeschlechtliche Fortpflanzung festgestellt worden.Monohystera parelegantula vermehrt sich parthenogenetisch. Ein möglicherweise durch Umwelteinflüsse bedingter Wechsel von bisexueller und parthenogenetischer Fortpflanzung tritt beiChromadora epidemos undViscosia macramphida auf.

     

Studies on marine fungal-nematode associations and plant degradation

Summary 1. Studies of the broad-leafed turtle grass,Thalassia testudinum König, have revealed a diverse range of fungal infestation different in generic composition and dynamics of attack from that found on submerged wood. Certain of the fungi, notably the AscomyceteLindra thalassiae, initiate considerable degradation of leaf tissue and show a developmental cycle in nature related to the physiological state of the host plant.2. Use of fungal-cellulose mats as a trapping substrate has been extremely effective for discernment of ecologically significant shifts in nematode concentrations, especially those of the omnivorous species,Metoncholaimus scissus.3. Patterns of activity ofM. scissus, as well as those of various foliicolous nematodes, suggest that loci of organic material, such as fungal infested leaves and decaying plant tissue, significantly affect biological activity of these animals.4. Laboratory analysis of degraded cotton cellulose filters show a striking incidence of fungal reproduction of the ascomycetous fungusLulworthia, along with development of a considerable associated nematode fauna, especially species ofViscosia (V. macramphida) andLeptolaimus (L. plectoides). Successional patterns in nematode development are noted with continued degradation of the cotton cellulose matrix.

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Studien über marine Pilz-Nematoden-Assoziationen und Pflanzendegradation

Kurzfassung Untersuchungen am SeegrasThalassia testudinum König haben ergeben, daß sich hier Pilzinfektionen hinsichtlich der Komposition der beteiligten Gattungen und der Dynamik des Befalls von den am untergetauchten Holz festgestellten Infektionen unterscheiden. Bestimmte Pilze, insbesondere der AscomycetLindra thalassiae, leiten eine erhebliche Degradation des Blattgewebes ein und zeigen einen Entwicklungszyklus, welcher in Beziehung steht zum physiologischen Zustand der Wirtspflanze. Die Anwendung von Pilz-Zellulose-Matten als Einfangsubstrat war außerordentlich erfolgreich für das Erkennen ökologisch signifikanter Verschiebungen in den Nematodenkonzentrationen, insbesondere bei der omnivoren ArtMetoncholaimus scissus. Die Aktivitätsmuster vonM. scissus — ebenso wie die verschiedener foliicolöser Nematoden — deuten darauf hin, daß pilzinfizierte und zerfallende Pflanzenteile in entscheidendem Maße die biologische Aktivität dieser Tiere beeinflussen. Laboratoriumsanalysen degradierter Wollzellulosefilter lassen eine überraschend starke Vermehrung des AscomycetenLulworthia erkennen und gleichzeitig die Entwicklung einer beachtlichen Fauna assoziierter Nematodenarten, insbesondere vonViscosia macramphida undLeptolaimus plectoides. Im Verlaufe der weiteren Degradation der Wollzellulosematrix kommt es bei der Nematodenfauna zu entsprechenden Sukzessionen.

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Contribution No. 768 from the Institute of Marine Science, University of Miami, Miami, Florida, and from the Canada Department of Agriculture, Ottawa, Canada. This work was supported at the IMS by grant GM 12842 from the National Institutes of Health, USA.     

Biodegradation of atrazine in surface soils and subsurface sediments collected from an agricultural research farm

The purpose of the present study was to assess atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) mineralization by indigenous microbial communities and to investigate constraints associated with atrazine biodegradation in environmental samples collected from surface soil and subsurface zones at an agricultural site in Ohio. Atrazine mineralization in soil and sediment samples was monitored as ¹⁴CO₂ evolution in biometers which were amended with ¹⁴C-labeled atrazine. Variables of interest were the position of the label ([U-¹⁴C-ring]-atrazine and [2-¹⁴C-ethyl]-atrazine), incubation temperature (25°C and 10°C), inoculation with a previously characterized atrazine-mineralizing bacterial isolate (M91-3), and the effect of sterilization prior to inoculation. In uninoculated biometers, mineralization rate constants declined with increasing sample depth. First-order mineralization rate constants were somewhat lower for [2-¹⁴C-ethyl]-atrazine when compared to those of [U-¹⁴C-ring]-atrazine. Moreover, the total amount of ¹⁴CO₂ released was less with [2-¹⁴C-ethyl]-atrazine. Mineralization at 10°C was slow and linear. In inoculated biometers, less ¹⁴CO₂ was released in [2-¹⁴C-ethyl]-atrazine experiments as compared with [U-¹⁴C-ring]-atrazine probably as a result of assimilatory incorporation of ¹⁴C into biomass. The mineralization rate constants (k) and overall extents of mineralization (P _max ) were higher in biometers that were not sterilized prior to inoculation, suggesting that the native microbial populations in the sediments were contributing to the overall release of ¹⁴CO₂ from [U-¹⁴C-ring]-atrazine and [2-¹⁴C-ethyl]-atrazine. A positive correlation between k and aqueous phase atrazine concentrations (C _eq ) in the biometers was observed at 25°C, suggesting that sorption of atrazine influenced mineralization rates. The sorption effect on atrazine mineralization was greatly diminished at 10°C. It was concluded that sorption can limit biodegradation rates of weakly-sorbing solutes at high solid-to-solution ratios and at ambient surface temperatures if an active degrading population is present. Under vadose zone and subsurface aquifer conditions, however, low temperatures and the lack of degrading organisms are likely to be primary factors limiting the biodegradation of atrazine.Abbreviations C _eq solution phase atrazine concentration at equilibrium - C _s amount of atrazine sorbed - CLA [2-¹⁴C-ethyl]-atrazine - k first-order mineralization rate constant - K _d sorption coefficient - m slope - P _max maximum amount of CO₂ released - RLA [U-¹⁴C-ring]-atrazine     

Sister chromatid exchange analysis of the 15q11 region in Prader-Willi syndrome patients

Summary Prader-Willi syndrome (PWS) is a sporadic disorder in which about half of cases have a 15q12 deletion. Although a small number of cases have other rearrangements involving 15q12, the rest of the cases appear to have normal chromosomes. Clinical similarities among all these patients regardless of the karyotype strongly suggests a common etiology. To investigate the nature of this common etiology, we analyzed sister chromatid exchange (SCE) at the 15q11-13 region in 10 PWS patients with the chromosome deletion, 12 PWS patients with normal chromosomes, and 11 normal control individuals. While SCE at the q11-13 region was absent on the 15q12 deleted chromosome, the percentage of SCE on chromosome 15 at q11 was statistically higher for PWS with normal chromosomes (10.1%) compared to that for normal controls (1.9%) and the normal homologue (2.2%) in deleted patients (²=7.7982, df=2, P<0.025). The data suggest relative instability of DNA at the 15q11 region in PWS patients.     

Chromosomal evolution withinPiperaceae

Chromosome numbers for 26 different species of the generaPiper, Peperomia andPothomorphe (Piperaceae) are reported. The basic chromosome numbers are 2n = 26, x = 13 (Piper, Pothomorphe) and 2n = 22, x = 11 (Peperomia), polyploid series are characteristic forPiper andPeperomia. Piper has the smallest chromosomes and prochromosomal interphase nuclei,Peperomia the largest ones and mostly reticulate to euchromatic nuclei.Pothomorphe is intermediate in both characters. The karyomorphological differences betweenPothomorphe andPiper underline their generic separation. Interspecific size variation of chromosomes occurs inPiper andPeperomia. Infraspecific polyploidy was observed inPiper betle. C-banding reveals different patterns of heterochromatin (hc) distribution between the genera investigated. The genome evolution is discussed.     

Mucociliary interaction in vitro: effects of physiological and inflammatory stimuli

Mucociliary transport in the airways is governed by the interaction between ciliary activity and the depth and rheological properties of the liquids (mucus) covering the epithelial surface. A change in one of these parameters may not predict the direction and magnitude of a concomitant change in mucociliary transport. We therefore determined the effects of physiological (neurotransmitters) and pathological (inflammatory mediators) stimuli on ciliary beat frequency (CBF), surface liquid velocity (SLV), surface liquid depth (SLD), and viscoelasticity of mucus in pieces of sheep trachea (n = 5 for each treatment) mounted in a chamber such that the submucosal side was bathed with Krebs-Henseleit perfusate (KH) and the luminal side was exposed to conditioned air. SLV, SLD, and CBF were measured with a microscope provided with an electronic micrometer and strobe light. Apparent viscosity and shear elastic modulus were measured with a microcapillary method using mucus collected at the downstream end of the preparation. Control CBF, SLV, and SLD were 11.6 +/- 0.4 (SE) Hz, 91 +/- 8 micron/s, and 33 +/- 5 microns, respectively, at base line and did not change during KH perfusion for 100 min. Perfusion with both acetylcholine and epinephrine (10(-5) to 10(-3) M) produced concentration-dependent increases in mean CBF (maximum increases at 10(-3) M of 16 and 9%, P less than 0.05), whereas only acetylcholine increased mean SLV (+56% at 10(-3) M, P less than 0.05). Perfusion with platelet-activating factor (10(-7) to 10(-5) M) decreased both mean CBF and SLV in a dose-dependent fashion (-6 and -63% at 10(-5) M, P less than 0.05), whereas antigen perfusion (1:60 dilution) increased mean CBF (+10%, P less than 0.05) but decreased SLV (-47%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)