1,992 research outputs found

    Further Studies of Non-Nuclear Structures in the Basidium

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    Pursuing a further analysis of the so-called Golgi apparatus in the basidium, tests were made with some accepted chondriosome techniques. Typical chondriosomes were found to be present, quite unlike the bodies associated with the Golgi apparatus. It is suggested that the Nebenkern and Golgi material are discrete cell bodies, apart from nucleus, chondriosomes and centrosomal mechamsm

    Cytoplasmic Structures in the Basidium Revealed by Silver Impregnation

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    Basidia of Coprinus fimetarius treated by silver impregnation methods exhibit blackened bodies in the cytoplasm. The size, shape, position and distribution of these bodies correspond to those of bodies demonstrated by mitochondrial techniques. The silver-absorbing bodies in the basidium are unlike the Golgi bodies demonstrated in some animal cells by silver impregnation, but bear much resemblance to mitochondria

    Some Cytological Details of Ceresan Poisoning in Seedlings

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    Heavy overdoses of Ceresan induces the formation of giant cells in seedlings of corn and small grains. Cell division is inhibited. Nuclear division occurs, with more or less normal prophases. Anaphase separation of halves of split chromosomes fails to take place, accompanied by apparent failure of the sprindle mechanism. Cell wall formation may he initiated, but the evidence suggests subsequent dissolution of partial cell walls

    Pathological Polyploidy in Seedlings of Corn and Sorghum

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    The writer had demonstrated that Coprinus sterquilinus contains an extra-nuclear mechanism which bears structural homologies with the Golgi apparatus in animal spermatocytes. Numerous other Hymenomycetes have been examined. Coprinus atramentarius contains a distinct Nebenkern sphere, consisting of a large hyaline sphere, in which there are peripheral, chromophilic granules. This body is most distinct just before the meiotic division of the fusion nucleus occurs. It is probable that the sterigmatic bodies described by various workers, are derived from this Golgi apparatus, rather than from the centrosomes

    The Presence of a Nebenkern In Coprinus atramentarius

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    The writer had demonstrated that Coprinus sterquilinus contains an extra-nuclear mechanism which bears structural homologies with the Golgi apparatus in animal spermatocytes. Numerous other Hymenomycetes have been examined. Coprinus atramentarius contains a distinct Nebenkern sphere, consisting of a large hyaline sphere, in which there are peripheral, chromophilic granules. This body is most distinct just before the meiotic division of the fusion nucleus occurs. It is probable that the sterigmatic bodies described by various workers, are derived from this Golgi apparatus, rather than from the centrosomes

    The Nuclear Cycle and Sexuality of Trametes peckii

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    Trametes peckii is a heterothallic member of the Polyporaceae. The sex classes exhibit considerable irregularity, making any attempt to classify this organism as bipolar or tetrapolar highly questionable. Segregation of monosporous haplonts into cottony and non-cottony mycelia is clearly indicated. The dikaryotic secondary mycelium is always cottony, suggesting the possibility of the dominance of the cotton character. Repulsion between certain combinations of two mycelia of opposite sex groups, and the absence of repulsion between other pairs, resembles the phenomenon designated as Barrage by Vandendries. This fungus appears to exhibit three segregating characters; sex potentiality, haploid mycelial character, and repulsion

    Aerogel Insulation Applications for Liquid Hydrogen Launch Vehicle Tanks

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    Aerogel based insulation systems for ambient pressure environments were developed for liquid hydrogen (LH2) tank applications. Solutions to thermal insulation problems were demonstrated for the Space Shuttle External Tank (ET) through extensive testing at the Cryogenics Test Laboratory. Demonstration testing was performed using a 1/10th scale ET LH2 intertank unit and liquid helium as the coolant to provide the 20 K cold boundary temperature. Cryopumping tests in the range of 20K were performed using both constant mass and constant pressure methods. Long-duration tests (up to 10 hours) showed that the nitrogen mass taken up inside the intertank is reduced by a factor of nearly three for the aerogel insulated case as compared to the un-insulated (bare metal flight configuration) case. Test results including thermal stabilization, heat transfer effectiveness, and cryopumping confirm that the aerogel system eliminates free liquid nitrogen within the intertank. Physisorption (or adsorption) of liquid nitrogen within the fine pore structure of aerogel materials was also investigated. Results of a mass uptake method show that the sorption ratio (liquid nitrogen to aerogel beads) is about 62 percent by volume. A novel liquid nitrogen production method of testing the liquid nitrogen physical adsorption capacity of aerogel beads was also performed to more closely approximate the actual launch vehicle cooldown and thermal stabilization effects within the aerogel material. The extraordinary insulating effectiveness of the aerogel material shows that cryopumping is not an open-cell mass transport issue but is strictly driven by thermal communication between warm and cold surfaces. The new aerogel insulation technology is useful to solve heat transfer problem areas and to augment existing thermal protection systems on launch vehicles. Examples are given and potential benefits for producing launch systems that are more reliable, robust, reusable, and efficient are outlined

    Epidermal Patterns in Haploid, Diploid and Tetraploid Tomatoes (Abstract)

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    Beginning with a sterile, dwarf tomato haploid of Lycopericon esculentum, carrying 12 univalent chromosomes, and a completely homozygous diploid strain with 12 pairs of chromosomes and highly fertile was produced by asexual doubling of chromosomes with the decapitation-callus technique. The latter was in turn doubled by the same method producing the relatively sterile homozygous autotetraploid form with 18 chromosomes (12 sets of quadrivalents). This n-2n-4n series of tomatoes provides unique material to test the influence of the very same genes in different dosages. The length of the guard cells along the median line affords a means of distinguishing between haploid, diploid and tetraploid plants. Stomata length averages 15 microns in haploid, 24 microns in diploid, and 3G microns in tetraploid plants. Stomata length in the three classes of plants is roughly in the ratio 5:8:12. Epidermal cells of haploid plants are approximately isodiametric, those of the tetraploid are considerably longer than wide, and those of the diploid are intermediate in proportions

    Some Historical Features of Potato Stem Necrosis Associated With Actinomyces Scabies

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    Certain varieties of potato (Solanum tuberosum L.) are extremely susceptible to the common scab disease caused by Actinomyces scabies (Thaxt.) Güssow, whereas the tubers of others are very resistant. The scab organism is also capable of parasitizing the stems, causing severe necrosis which may result in premature death of the plant. Varieties known to be resistant to tuber scab show considerable resistance to stem necrosis, whereas those susceptible to tuber scab are likewise susceptible to scab on the stems

    Histology of a Genetic Malformation in Corn

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    Knotted leaf is a malformation of corn leaves, manifested as scattered, conical or irregular emergences on the dorsal surface of the leaf. These raised regions occur most commonly on the veins. A corresponding depression occurs on the ventral surface opposite each emergence. Sections show that an emergence is a thickened fold of the leaf blade. Thickening is associated with great enlargement of mesophyll and epidermal cells. There is little or no increase in the number of layers of cells comprising the thickness of the fold. The enlarged cells are uninucleate and the relatively small nuclei are diploid
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