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684 results on '"Guillette, Louis J."'

1. Leucistic American Alligator Hatchlings in Coastal South Carolina

Author

Rainwater, Thomas R., Griess, Jane, Murphy, Thomas M., Boylan, Shane M., Parrott, Benjamin B., Kohno, Satomi, Rainwater, Katherine A.E., Richards, Sean M., Guillette, Matthew, Mills, Tony, Platt, Steven G., Wilkinson, Philip M., and Guillette, Louis J.

Published
2020

2. Improved genome assembly of American alligator genome reveals conserved architecture of estrogen signaling

Author

Rice, Edward S, Kohno, Satomi, St. John, John, Pham, Son, Howard, Jonathan, Lareau, Liana F, O'Connell, Brendan L, Hickey, Glenn, Armstrong, Joel, Deran, Alden, Fiddes, Ian, Platt, Roy N, Gresham, Cathy, McCarthy, Fiona, Kern, Colin, Haan, David, Phan, Tan, Schmidt, Carl, Sanford, Jeremy R, Ray, David A, Paten, Benedict, Guillette, Louis J, and Green, Richard E

Subjects
Biological Sciences, Bioinformatics and Computational Biology, Genetics, Estrogen, Human Genome, 1.1 Normal biological development and functioning, Underpinning research, Alligators and Crocodiles, Animals, CCCTC-Binding Factor, Chromatin, Conserved Sequence, Contig Mapping, Estrogens, Female, Genome, Male, Sequence Analysis, DNA, Sex Determination Processes, Signal Transduction, Synteny, Medical and Health Sciences, Bioinformatics
Abstract

The American alligator, Alligator mississippiensis, like all crocodilians, has temperature-dependent sex determination, in which the sex of an embryo is determined by the incubation temperature of the egg during a critical period of development. The lack of genetic differences between male and female alligators leaves open the question of how the genes responsible for sex determination and differentiation are regulated. Insight into this question comes from the fact that exposing an embryo incubated at male-producing temperature to estrogen causes it to develop ovaries. Because estrogen response elements are known to regulate genes over long distances, a contiguous genome assembly is crucial for predicting and understanding their impact. We present an improved assembly of the American alligator genome, scaffolded with in vitro proximity ligation (Chicago) data. We use this assembly to scaffold two other crocodilian genomes based on synteny. We perform RNA sequencing of tissues from American alligator embryos to find genes that are differentially expressed between embryos incubated at male- versus female-producing temperature. Finally, we use the improved contiguity of our assembly along with the current model of CTCF-mediated chromatin looping to predict regions of the genome likely to contain estrogen-responsive genes. We find that these regions are significantly enriched for genes with female-biased expression in developing gonads after the critical period during which sex is determined by incubation temperature. We thus conclude that estrogen signaling is a major driver of female-biased gene expression in the post-temperature sensitive period gonads.

Published
2017

7. Competencies: a cure for pre-med curriculum.

Author

Anderson, Winston A, Amasino, Richard M, Ares, Manuel, Jr, Banerjee, Utpal, Bartel, Bonnie, Corces, Victor G, Drennan, Catherine L, Elgin, Sarah C R, Epstein, Irving R, Fanning, Ellen, Guillette, Louis J, Jr, Handelsman, Jo, Hatfull, Graham F, Hoy, Ronald Raymond, Kelley, Darcy, Leinwand, Leslie A, Losick, Richard, Lu, Yi, Lynn, David G, Neuhauser, Claudia, O'Dowd, Diane K, Olivera, Toto, Pevzner, Pavel, Richards-Kortum, Rebecca R, Rine, Jasper, Sah, Robert L, Strobel, Scott A, Walker, Graham C, Walt, David R, Warner, Isiah M, Wessler, Sue, Willard, Huntington F, and Zare, Richard N

Subjects
Curriculum, Education, Premedical, Educational Status, School Admission Criteria, Schools, Medical, Universities, curriculum, curriculum development, engineering, letter, mathematics, medical education, medical school, priority journal, science, United States, Curriculum, Education, Premedical, Educational Status, School Admission Criteria, Schools, Medical, Universities
Published
2011

24. Male Reproductive Health and Environmental Xenoestrogens

Author

Toppari, Jorma, Christiansen, Peter, Giwercman, Aleksander, Grandjean, Philippe, Guillette,, Louis J., Jégou, Bernard, Jensen, Tina K., Jouannet, Pierre, Keiding, Niels, Leffers, Henrik, McLachlan, John A., Meyer, Otto, Müller, Jørn, Meyts, Ewa Rajpert-De, Scheike, Thomas, Sharpe, Richard, Sumpter, John, and Skakkebæk, Niels E.

Published
1996
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30. Group-Advantaged Training of Research (GATOR): A Metamorphosis of Mentorship

Author

Edwards, Thea M., Smith, Barbara K., Watts, Danielle L., Germain-Aubrey, Charlotte C., Roark, Alison M., Bybee, Seth M., Cox, Clayton E., Hamlin, Heather J., and Guillette, Louis J.

Abstract

We describe Group-Advantaged Training of Research (GATOR), a yearlong structured program at the University of Florida that guided graduate student mentors and their undergraduate mentees through the mentored research process. Using the national Survey of Undergraduate Research Experiences for an academic year, we found that outcomes for our mentees were similar to those for other programs. We also used an internal survey, combined with qualitative observations, to develop a road map of the mentoring process, which we call the "Metamorphosis of Mentorship." This model provides tangible steps on the road to becoming a scientist, incorporates reasons mentees stall in research, and suggests ways to overcome mentoring challenges and prevent attrition. The structure and outcomes of this program will be useful to researchers and administrators working to engage undergraduates in scientific research, particularly at large universities where undergraduates are often mentored by graduate students.

Published
2011
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36. Why Public Health Agencies Cannot Depend on Good Laboratory Practices as a Criterion for Selecting Data: The Case of Bisphenol A

Author

Myers, John Peterson, Saal, Frederick S. vom, Akingbemi, Benson T., Arizono, Koji, Belcher, Scott, Colborn, Theo, Chahoud, Ibrahim, Crain, D. Andrew, Farabollini, Francesca, Guillette,, Louis J., Hassold, Terry, Ho, Shuk-mei, Hunt, Patricia A., Iguchi, Taisen, Jobling, Susan, Kanno, Jun, Laufer, Hans, Marcus, Michele, McLachlan, John A., Nadal, Angel, Oehlmann, Jörg, Olea, Nicolás, Palanza, Paola, Parmigiani, Stefano, Rubin, Beverly S., Schoenfelder, Gilbert, Sonnenschein, Carlos, Soto, Ana M., Talsness, Chris E., Taylor, Julia A., Vandenberg, Laura N., Vandenbergh, John G., Vogel, Sarah, Watson, Cheryl S., Welshons, Wade V., and Zoeller, R. Thomas

Published
2009
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43. Variation in Nest Temperatures of the American Alligator Found on the Kennedy Space Center Merritt Island National Wildlife Refuge

Author

Lowers, Russell, Guillette, Louis J, and Weiss, Stephanie

Subjects
Life Sciences (General)
Abstract

Information on nest temperatures of the American Alligator (Alligator mississippiensis) constructed in the wild is limited. Nesting temperatures during a critical thermal sensitive period determine the sex of alligators and are therefore critical in establishing the sex biases in recruitment efforts of alligators within a given community. Nest components, varying environmental conditions, and global warming could have a significant impact on nest temperatures, thus affecting future generations of a given population. One hundred and seventy four programmable thermistors were inserted into fifty eight nests from 2010 through 2015 nesting cycles. Three thermistors were placed inside each nest cavity (one on top of the eggs, one in the middle of the eggs, and one at the bottom of the clutch of the eggs) to collect temperature profiles in the incubation chamber and throughout the entire incubation period. One thermistor was also placed near or above these nests to obtain an ambient air temperature profile. Once retrieved, data from these thermistors were downloaded to examine temperature profiles throughout the incubation period as well as during the period of sexual determination. These data would help establish survival rates related to nest temperature and predict sex ratio of recruited neonates at the Kennedy Space Center. Over three million temperatures have been recorded since 2010 for the alligator thermistor study giving us insight to the recruitment efforts found here. Precipitation was the largest influence on nesting temperatures outside of daily photoperiod, with immediate changes of up to eight degrees Celsius.

Published
2016

44. Seasonal Variation of Total Mercury Burden in the American Alligator (Alligator Mississippiensis) at Merritt Island National Wildlife Refuge (MINWR), Florida

Author

Nilsen, Frances M, Dorsey, Jonathan E, Long, Stephen E, Schock, Tracey B, Bowden, John A, Lowers, Russell H, and Guillette, Louis J., Jr

Subjects
Life Sciences (General), Environment Pollution
Abstract

Seasonal variation of mercury (Hg) is not well studied in free-ranging wildlife. Atmospheric deposition patterns of Hg have been studied in detail and have been modeled for both global and specific locations with great accuracy and correlates to environment impact. However, monitoring these trends in wildlife is complicated due to local environmental parameters (e.g., rainfall, humidity, pH, bacterial composition) that can affect the transformation of atmospheric Hg to the biologically available forms. Here, we utilized an abundant and healthy population of American alligators (Alligator mississippiensis) at Merritt Island National Wildlife Refuge (MINWR), FL, and assessed Hg burden in whole blood samples over a span of 7 years (2007 2014; n 174) in an effort to assess seasonal variation of total [Hg]. While the majority of this population is assumed healthy, 18 individuals with low body mass indices (BMI, defined in this study) were captured throughout the 7 year sampling period. These individual alligators exhibited [Hg] that were not consistent with the observed overall seasonal [Hg] variation, and were statistically different from the healthy population of alligators. The alligators with low BMI had elevated concentrations of Hg compared to their age/sex/season matched counterparts with normal BMI. Statistically significant differences were found between the winter and spring seasons for animals with normal BMI. The data in this report supports the conclusion that organismal total [Hg] do fluctuate directly with seasonal deposition rates as well as other seasonal environmental parameters, such as average rainfall and prevailing wind direction. This study highlights the unique environment of MINWR to permit annual assessment of apex predators, such as the American alligator, to determine detailed environmental impact of contaminants of concern.

Published
2016

45. Perfluorinated Alkyl Acids in Plasma of American Alligators (Alligator Mississippiensis) from Florida and South Carolina

Author

Bangma, Jacqueline T, Bowden, John A, Brunell, Arnold M, Christie, Ian, Finnell, Brendan, Guillette, Matthew P, Jones, Martin, Lowers, Russell H, Rainwater, Thomas R, Reiner, Jessica L, Wilkinson, Philip M, and Guillette, Louis J., Jr

Subjects
Life Sciences (General)
Abstract

This study aimed to quantitate fourteen perfluoroalkyl acids (PFAAs) in 125 adult American alligators at twelve sites across the southeastern US. Of those fourteen PFAAs, nine were detected in 65% - 100% of the samples: PFOA, PFNA, PFDA, PFUnA, PFDoA, PFTriA, PFTA, PFHxS, and PFOS. Males (across all sites) showed significantly higher concentrations of four PFAAs: PFOS (p = 0.01), PFDA (p = 0.0003), PFUnA (p = 0.021), and PFTriA (p = 0.021). Concentrations of PFOS, PFHxS, and PFDA in plasma were significantly different among the sites in each sex. Alligators at Merritt Island National Wildlife Refuge and Kiawah Nature Conservancy both exhibited some of the highest PFOS concentrations (medians 99.5 ng/g and 55.8 ng/g respectively) in plasma measured to date in a crocodilian species. A number of positive correlations between PFAAs and snout-vent length (SVL) were observed in both sexes suggesting PFAA body burdens increase with increasing size. In addition, several significant correlations among PFAAs in alligator plasma may suggest conserved sources of PFAAs at each site throughout the greater study area. This study is the first to report PFAAs in American alligators, reveals potential PFAA hot spots in Florida and South Carolina, and provides and additional contaminant of concern when assessing anthropogenic impacts on ecosystem health.

Published
2016

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