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Alligator Mississippiensis

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Ruth M. Elsey – 1st expert on this subject based on the ideXlab platform

  • Contribution of active atrial contraction to cardiac output in anesthetized American Alligators (Alligator Mississippiensis)
    The Journal of Experimental Biology, 2018
    Co-Authors: William Joyce, Ruth M. Elsey, Tobias Wang, Janna Crossley, Dane A Crossley

    Abstract:

    ABSTRACT Ventricular filling may occur directly from the venous circulation during early diastole or via atrial contraction in late diastole. The contribution of atrial contraction to ventricular filling is typically small in mammals (10–40%), but has been suggested to predominate in reptiles. We investigated the importance of atrial contraction in filling of the ventricle in American Alligators ( Alligator Mississippiensis ) by bypassing both atria (with the use of ligatures to prevent atrial filling) and measuring the resultant effects on cardiac output in anesthetized animals. Atrial ligation had no significant effects on total systemic blood flow before or after adrenaline injection. Unexpectedly, pulmonary flow was increased following atrial ligation prior to adrenaline treatment, but was unaffected after it. These findings suggest that the atria are non-essential (i.e. redundant) for ventricular filling in Alligators, at least under anesthesia, but may serve as important volume reservoirs.

  • american Alligator Alligator Mississippiensis embryos tightly regulate intracellular ph during a severe acidosis
    Canadian Journal of Zoology, 2018
    Co-Authors: Ryan B Shartau, Ruth M. Elsey, Dane A Crossley, Zachary F Kohl, Colin J Brauner

    Abstract:

    Crocodilian nests naturally experience high CO 2 (hypercarbia), which leads to increased blood P CO 2 and reduced blood pH (pH e ) in embryos; their response to acid-base challenges is not known. During acute hypercarbia, snapping turtle embryos preferentially regulate tissue pH (pH i ) against pH e reductions. This is proposed to be associated with CO 2 tolerance in reptilian embryos and is not found in adults. In the present study, we investigated pH regulation in American Alligator Alligator Mississippiensis (Daudin, 1802) embryos exposed to 1 h hypercarbia hypoxia (13 k P a P CO 2 , 9 k P a P O 2 ). Hypercarbia hypoxia reduced pH e by 0.42 pH units while heart and brain pH i increased, with no change in pH i of other tissues. The results indicate American Alligator embryos preferentially regulate pH i , similar to snapping turtle embryos, which represent…

  • coronary blood flow in the anesthetized american Alligator Alligator Mississippiensis
    Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2016
    Co-Authors: Bjarke Jensen, Ruth M. Elsey, Magnus Elfwing, Tobias Wang, Dane A Crossley

    Abstract:

    Coronary circulation of the heart evolved early within ectothermic vertebrates and became of vital importance to cardiac performance in some teleost fish, mammals and birds. In contrast, the role and function of the coronary circulation in ectothermic reptiles remains largely unknown. Here, we investigated the systemic and coronary arterial responses of five anesthetized juvenile American Alligators (Alligator Mississippiensis) to hypoxia, acetylcholine, adenosine, sodium nitroprusside, isoproterenol, and phenylephrine. We recorded electrocardiograms, monitored systemic blood pressure, blood flows in both aortae, and blood flow in a major coronary artery supplying most of the right ventricle. Coronary arterial blood flow was generally forward, but there was a brief retrograde flow during a ventricular contraction. Blood pressure was significantly changed in all conditions. Acetylcholine decreased coronary forward flow, but this response was confounded by the concomitant lowered work of the ventricles due to decreased heart rate and blood pressure. Coronary forward flow was poorly correlated with heart rate and mean arterial pressure across treatments. Overall changes in coronary forward flow, significant and not significant, were generally in the same direction as mean arterial pressure and ventricular power, approximated as the product of systemic cardiac output and mean arterial pressure.

Michael J. Tanner – 2nd expert on this subject based on the ideXlab platform

  • Analysis of gular and paracloacal gland secretions of the american Alligator (Alligator Mississippiensis) by thin-layer chromatography Gland, sex, and individual differences in lipid components
    Journal of Chemical Ecology, 1990
    Co-Authors: Paul J. Weldon, Timothy P. Scott, Michael J. Tanner

    Abstract:

    Secretions from the gular and the paracloacal glands of adult male and female American Alligators ( Alligator Mississippiensis ) were extracted with chloroform, weighed, and analyzed by thin-layer chromatography. In both sexes, more lipoidal secretions were recovered from the paracloacal glands than from the gular glands. Females produce more lipoidal secretions in both sets of glands than do males. The thin-layer chromatograms of extracts from both glands exhibit bands consistent with aliphatic alcohols, sterols, free fatty acids, and steryl esters. Triglycerides, hydrocarbons, phosphatidylethanolamine, and lysophosphatidylcholine also are indicated in some chromatograms. Gland, sex, and individual differences are suggested in the thinlayer profiles.

Paul J. Weldon – 3rd expert on this subject based on the ideXlab platform

  • Dorsal galnds of Alligator Mississippiensis: a histological and histochemical study
    Journal of Zoology, 1996
    Co-Authors: M. S. Cannon, Randall W. Davis, Paul J. Weldon

    Abstract:

    Several investigators have described in some crocodilians a row of round or oval organs, called dorsal glands, lying under scutes on each side of the dorsal midline. The function of these glands is unknown, but they are hypothesized to produce skin-conditioning secretions. We investigated the anatomy and histochemistry of the dorsal glands of adult American Alligators (Alligator Mississippiensis). Twenty to 22 pairs of glands containing a viscous, often black, material were observed lying from the mid-cervical to the anterior caudal regions in the axial musculature or on the inner surface of the dermis. The capsule of each gland consists of dense collagenous fibres and numerous short elastic fibres, and is surrounded by skeletal muscle. The single lumen is lined by one to several layers of cuboidal to columnar epithelium in varying stages of degeneration, indicating a holocrine secretory mode. The epithelial cell membranes often interdigitate and tight junctions and desmosomes occasionally are observed between them. The epithelial cells and secretory product contain slight to considerable amounts of lipid; glycoproteins may be present. Crystals exhibiting a dense core and/or layering occur in the epithelial cells and secretory product. Energy-dispersive X-ray analysis demonstrates calcium, copper, iron, lead, potassium, and zinc in the crystals. Mitochondria, vacuoles, and short segments of rough endoplasmic reticulum also occur in the cells.

  • Analysis of gular and paracloacal gland secretions of the american Alligator (Alligator Mississippiensis) by thin-layer chromatography Gland, sex, and individual differences in lipid components
    Journal of Chemical Ecology, 1990
    Co-Authors: Paul J. Weldon, Timothy P. Scott, Michael J. Tanner

    Abstract:

    Secretions from the gular and the paracloacal glands of adult male and female American Alligators ( Alligator Mississippiensis ) were extracted with chloroform, weighed, and analyzed by thin-layer chromatography. In both sexes, more lipoidal secretions were recovered from the paracloacal glands than from the gular glands. Females produce more lipoidal secretions in both sets of glands than do males. The thin-layer chromatograms of extracts from both glands exhibit bands consistent with aliphatic alcohols, sterols, free fatty acids, and steryl esters. Triglycerides, hydrocarbons, phosphatidylethanolamine, and lysophosphatidylcholine also are indicated in some chromatograms. Gland, sex, and individual differences are suggested in the thinlayer profiles.