132 research outputs found

    Not a Tiger but a Dagger: The Larva of Comachara Cadburyi and Reassignment of the Genus to Acronictinae (Lepidoptera: Noctuidae)

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    Comachara cadburyi Franclemont has benn classified as a sarrothripine (Noctuidae), lithosiine (Arctiidae), and afridine (Nolidae). Larval morphology and behavior indicate a close phylogenetic relationship with Polygrammate hebraeicum Hübner, an acronictine noctuid. The egg and larva of Comachara are described and illustrated with line drawings and scanning electron micrographs. Photographs of last instars of both Comachara and Polygrammate are provided. Larval feeding and pupation habits of C. cadburyi are briefly described and compared with those of Polygrammate. Larvae of both Polygrammate and Comachara exhibit a dramatic coloration change in the last instar, transitioning from a green phase to a mottled, steely gray form. As the color change progresses, the larva ceases feeding and enters a wandering phase, during which it seeks out wood in which to pupate. Interpretation of L group setal homologies on the ninth abdominal segment is briefly addressed. Comachara provides a poignant example of the importance of immatures in elucidating phylogeny - adult features of Comachara misled a number of the twentieth century century\u27s finest lepidopterists

    On the Mechanism of Plasma Membrane Turnover in the Salt Gland of Ducklings - Implications From DNA Content, Rates of DNA Synthesis, and Sites of DNA Synthesis During the Osmotic Stressing and Destressing Cycle

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    This study provides information on the rates of DNA synthesis, sites of DNA synthesis, and DNA content of the avian salt gland during the osmoticstressing (plasma membrane synthesis) and destressing (plasma membrane turnover) cycle, in an effort to better understand the relationship of cell turnover to the initial events in plasma membrane amplification, differentiation, and turnover. The rate of DNA synthesis increases 12-24 h after the onset of osmotic stress, is maximal at about 24 h of osmotic stress, and decreases thereafter in fully stressed and destressed glands. The maximum DNA and protein content, and the maximum protein/DNA ratio are obtained after about 3 days of stress. Autoradiograms show that at 24 h of stress 70-80% of DNA synthesis occurs in connective tissue cells and 20-30% in parenchymal cells, but by 6 days of stress, synthesis occurs about equally in these cell groups. Because destressing is characterized by a large decrease in plasma membrane and in glandular protein, but by little DNA turnover or loss, the loss of plasma membrane is likely due to some type of cell dedifferentiation rather than cell turnover

    Vascular Corrosion Casting

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    Ultrastructure Atlas of Human Tissues

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    Presents a variety of scanning and transmission electron microscope images of the major systems of the human body. This book looks at the structure and function of tissues at the subcellular and molecular level, an important perspective in understanding and combating diseases.https://dc.etsu.edu/etsu_books/1047/thumbnail.jp

    Introduction

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    Vascular Corrosion Casting

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    The larva and pupa of Lytrosis permagnaria Pack. (Geometridae)

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    Volume: 57Start Page: 107End Page: 11

    The Larva and Pupa of Lytrosis Permagnaria Pack (Geometridae)

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    Larvae of Lytrosis permagnaria were reared to maturity on red oak (Quercus rubra). The larva and pupa of this rare eastern geometrid are described and illustrated. Diagnoses and photographic images of late instar larvae are provided for three members of the genus: Lytrosis permagnaria, L. sinuosa, and L. unitaria

    Vascular Corrosion Casting: Review of Advantages and Limitations in the Application of Some Simple Quantitative Methods

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    Vascular corrosion casting has been used for about 40 years to produce replicas of normal and abnormal vasculature and microvasculature of various tissues and organs that could be viewed at the ultrastructural level. In combination with scanning electron microscopy (SEM), the primary application of corrosion casting has been to describe the morphology and anatomical distribution of blood vessels in these tissues. However, such replicas should also contain quantitative information about that vasculature. This report summarizes some simple quantitative applications of vascular corrosion casting. Casts were prepared by infusing Mercox resin or diluted Mercox resin into the vasculature. Surrounding tissues were removed with KOH, hot water, and formic acid, and the resulting dried casts were observed with routine SEM. The orientation, size, and frequency of vascular endothelial cells were determined from endothelial nuclear imprints on various cast surfaces. Vascular volumes of heart, lung, and avian salt gland were calculated using tissue and resin densities, and weights. Changes in vascular volume and functional capillary density in an experimentally induced emphysema model were estimated from confocal images of casts. Clearly, corrosion casts lend themselves to quantitative analysis. However, because blood vessels differ in their compliances, in their responses to the toxicity of casting resins, and in their response to varying conditions of corrosion casting procedures, it is prudent to use care in interpreting this quantitative data. Some of the applications and limitations of quantitative methodology with corrosion casts are reviewed here

    The Gill Arch of the Striped Bass (Morone Saxatilis). IV. Alterations in the Ultrastructure of Chloride Cell Apical Crypts and Chloride Efflux Following Exposure to Seawater

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    Osmotically induced alterations in the ultrastructure of the apical crypts of chloride cells and changes in chloride efflux were studied in striped bass (Morone saxatilis). Striped bass were divided into three groups: fish adapted to freshwater, fish transferred directly from freshwater to 100% seawater (3% salt, w/v) for 24 hr or less, and fish adapted to 100% seawater for 7 days or more. Transmission electron microscopy studies revealed multicellular complexes of cells in both freshwater‐ and seawater‐adapted fish. Cytoplasmic indigitations between cells in the complex were more numerous in seawateradapted bass. Scanning electron microscopy studies showed that the apical extensions in freshwater fish were uniform in size. Changes in ultrastructure and chloride efflux were observed within 3 hr after transfer to seawater. Initially the apical extensions of chloride cells become longer, more prominent, and branched. After 7 days in seawater some of the apical crypts develop into a deeper “pit” structure, while others remain like those of freshwater fish. An increase in the number of apical crypts is measured by 14 days after transfer. Chloride efflux increases to five times freshwater values after 24 hr and 17 times freshwater values after 7 days in seawater. Mitochondrial density is not significantly different between freshwater and seawater fish (7 or more days). The response of chloride cell apical crypts is not an all‐or‐none phenomenon as observed in other species. Striped bass are able to increase chloride efflux when osmotically stressed with little ultrastructural alteration
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