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5 results on '"A F, Clemons"'

1. Multi-generational benefits of genetic rescue

Author

Dave P. Onorato, Mark W. Cunningham, Mark Lotz, Marc Criffield, David Shindle, Annette Johnson, Bambi C. F. Clemons, Colin P. Shea, Melody E. Roelke-Parker, Warren E. Johnson, Brett T. McClintock, Kristine L. Pilgrim, Michael K. Schwartz, and Madan K. Oli

Subjects
Endangered species conservation, Fitness, Florida panther, Genetic rescue, Inbreeding depression, Puma concolor, Medicine, Science
Abstract

Abstract Genetic rescue—an increase in population fitness following the introduction of new alleles—has been proven to ameliorate inbreeding depression in small, isolated populations, yet is rarely applied as a conservation tool. A lingering question regarding genetic rescue in wildlife conservation is how long beneficial effects persist in admixed populations. Using data collected over 40 years from 1192 endangered Florida panthers (Puma concolor coryi) across nine generations, we show that the experimental genetic rescue implemented in 1995—via the release of eight female pumas from Texas—alleviated morphological, genetic, and demographic correlates of inbreeding depression, subsequently preventing extirpation of the population. We present unequivocal evidence, for the first time in any terrestrial vertebrate, that genetic and phenotypic benefits of genetic rescue remain in this population after five generations of admixture, which helped increase panther abundance (> fivefold) and genetic effective population size (> 20-fold). Additionally, even with extensive admixture, microsatellite allele frequencies in the population continue to support the distinctness of Florida panthers from other North American puma populations, including Texas. Although threats including habitat loss, human-wildlife conflict, and infectious diseases are challenges to many imperiled populations, our results suggest genetic rescue can serve as an effective, multi-generational tool for conservation of small, isolated populations facing extinction from inbreeding.

Published
2024
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2. Myocardial effects of repetitive episodes of rapid ventricular pacing in conscious dogs: surgical creation, echocardiographic evaluation, and morphometric analysis

Author

D E, Burkett, A A, Seymour, D H, Knight, C E, Rabon, V M, Lanoce, A F, Clemons, and F G, Spinale

Subjects
Heart Failure, Male, Heart Ventricles, Cardiac Pacing, Artificial, Hemodynamics, Heart, Organ Size, Myocardial Contraction, Catheterization, Disease Models, Animal, Dogs, Tachycardia, Animals, Female, Ultrasonography
Abstract

The interactions of the systemic and myocardial adaptations during and after rapid ventricular pacing, a model of heart failure, were assessed in conscious, unstressed dogs. Ultrasonic probes and vascular catheters were surgically implanted into dogs for measurements of blood flows and pressures during 3 weeks of pacing and after 2 months of recovery. Three weeks of tachycardia (260 beats/min) resulted in a marked reduction in hemodynamic parameters and left ventricular dilatation, with caudal wall thinning throughout the pacing period and 1 week of recovery. Sinus rhythm resumed after the pacer was turned off, with return toward normal in hemodynamic parameters; however, left ventricular dilatation and ventricular remodeling, with significant fibrosis, loss of myocytes, and hypertrophy of the surviving cells were still present after 2 months of recovery. In conclusion, even though hemodynamic parameters normalized during recovery, adaptive myocardial remodeling caused permanent ventricular fibrosis, hypertrophy, and increased cardiac filling pressures.

Published
1994

3. Hemodynamic, renal, and hormonal effects of rapid ventricular pacing in conscious dogs

Author

A A, Seymour, D E, Burkett, M M, Asaad, V M, Lanoce, A F, Clemons, and W L, Rogers

Subjects
Heart Failure, Male, Heart Ventricles, Cardiac Pacing, Artificial, Hemodynamics, Natriuresis, Blood Pressure, Kidney, Disease Models, Animal, Dogs, Heart Rate, Tachycardia, Renin, Animals, Female, Vascular Resistance, Cyclic GMP, Atrial Natriuretic Factor, Glomerular Filtration Rate
Abstract

The interactions of the systemic adaptations during and after rapid ventricular pacing, a model of heart failure, were assessed in conscious, unstressed dogs. One week of ventricular tachycardia (260 beats/min) significantly reduced mean +/- SEM cardiac output (2.3 +/- 0.1 to 1.2 +/- 0.1 liter/min), mean arterial pressure (119 +/- 3 to 93 +/- 3 mm Hg), renal blood flow (168 +/- 19 to 96 +/- 9 ml/min), sodium excretion (36 +/- 5 to 10 +/- 4 mEq/d), increased left and right atrial pressures (8 +/- 1 to 21 +/- 1 and 4 +/- 0 to 11 +/- 1 mm Hg, respectively), plasma atrial natriuretic peptide concentration (24 +/- 4 to 141 +/- 38 fmol/ml), plasma cyclic GMP concentration (9 +/- 1 to 16 +/- 4 pmol/ml), and urinary cyclic GMP excretion (0.77 +/- 0.05 to 2.18 +/- 0.34 nmol/min). These changes persisted throughout 3 weeks of pacing. Gradual increases in systemic and renal vascular resistances (to 122 +/- 17 and 1.30 +/- 0.22 mm Hg/liter/min, respectively) and reductions in glomerular filtration rate (65 +/- 6 to 44 +/- 4 ml/min) reached significance during the third week. Resumption of sinus rhythm stimulated a brisk natriuresis and a return of cardiac output, systemic vascular resistance, and hormone concentrations to control values within 7 days. However, increases of left and right atrial pressures (14 +/- 2 and 8 +/- 1 mm Hg, respectively) were still present after 2 months of recovery. In conclusion, persistent increases in cardiac filling pressures were induced by rapid ventricular pacing in conscious, unstressed dogs, whereas the systemic hemodynamic, renal, and hormonal responses were largely reversible during recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Published
1994

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