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It reads, “U.S. Government Property – Trespassers Subject to Prosecution.”

UGA scientists have presented a strong case that the mechanism lies at the intersection of the genome and epigenome

What determines the life span of a mouse, alligator, dog or human? A team of scientists at the University of Georgia believes they have new insight into this age-old question.

Emily Bertucci and Benjamin B. Parrott, a research team at the Odum School of Ecology and the Savannah River Ecology Laboratory, have presented a strong case that the mechanism lies at the intersection of the genome and epigenome.

Bertucci, a doctoral candidate, and Parrott, an assistant professor, build on recently published data in epigenetics, which underlies changes in organisms caused by modifications to gene expression rather than alterations in genetic code. Their recent literature review, published in the journal Trends in Genetics, reports that a significant part of epigenetic aging occurs in regions with CpGs. A CpG is a region of DNA where the chemical elements cytosine and guanine are connected by a phosphate bond.

“CpGs are important because DNA methylation occurs in the area,” said Bertucci, the study’s lead author. “Methylation adds a chemical code to the DNA strand that empowers the strand and tells it how to function. It can also turn genes on or off.”

Scientists have observed that methylation patterns change as vertebrates age.

“We know that certain changes occur in the genome at certain times. These changes can be modeled to create epigenetic clocks and occur in the region associated with developmental genes,” he said. “You can take a blood sample to sequence DNA methylation and accurately predict age within several years.”

The activity that occurs in this area also determines a cell’s fate—whether it will be a skin cell, neuron or a heart cell—but this is just one piece of the puzzle.

Parrott said double-stranded breaks frequently occur in the genome throughout an organism’s life span. These breaks are efficiently repaired by proteins and enzymes known as chromatin modifiers.

According to the study, the chromatin modifiers leave the CpG Island to repair the breaks, and when they relocate, changes occur that alter gene expression and thus a cell’s fate.

If we think of these chromatin modifiers as soldiers, their role becomes quite clear, Bertucci said.

“They have unique power to support and enforce the code of the land, but if they leave the island to perform a rescue, the island becomes compromised and vulnerable if all of them don’t return.”

Scientists have known for years that species with longer life spans such as humans, alligators and elephants have higher levels of CpGs than species like fish and rodents, Parrott said. He likens increased CpGs on the island to a bright light beaconing from a lighthouse that aids the relocated chromatin modifiers or RCMs to make their way back home safely. They also act as a buffer to keep the foundation of the epigenetic landscape intact when the RCMs move to repair the double-stranded breaks.

The density of CpGs may not offer the total picture of life span, according to the researchers. Environmental factors and stress can also play a role.

The details of the study, including a list of the research the team reviewed, can be found at https://www.sciencedirect.com/science/article/pii/S0168952520301323

Soils with heavy metals had a higher level of specific bacterial hosts that were accompanied by antibiotic-resistant genes.

Since 2017, the wild lands of the Savannah River Site  have served as a front line in the U.S. Department of Agriculture’s fight to eradicate rabies in the nation.

Researchers at the University of Georgia’s Savannah River Ecology Laboratory have been conducting studies focused on the elimination of rabies in raccoons in partnership with the National Rabies Management Program operated by USDA’s Animal Plant Health and Inspection Service. The research is intended to determine the most efficient method for vaccinating the raccoon population to support the goal of preventing the spread of wildlife rabies.

Olin “Gene” Rhodes, director of SREL and a wildlife ecologist, said the site’s 310-square-mile landscape and its diverse habitats, characteristic of the southeast U.S., are ideal for conducting the research.

“Rabies is classified as a zoonotic disease because it is transmitted from animals to humans. If not quickly treated, it is fatal to humans, and it is a significant issue in the Southeastern U.S.,” Rhodes said. “Large areas of federally owned land like the SRS are excellent locations for critical research on zoonotic diseases as they are home to large populations of animals that commonly carry the variants of the rabies virus in the Southeastern U.S., like raccoons, skunks, foxes, and bats.”

According to APHIS and the Centers for Disease Control and Prevention, raccoons are the dominant carrier and species of concern for rabies in the region.

Guha Dharmarajan, an assistant research scientist at SREL, supervises graduate students working on the project. He said inoculating raccoon populations in Southeastern states requires overcoming an obstacle: opossums.

Opossums, non-carriers of the virus, can be found in the same habitats as the raccoons — bottomland swamps, isolated wetlands, and upland pine. As a result, they often consume the bait intended for raccoons, according to Dharmarajan.

“We are using capture-recapture methods and remote camera surveillance to determine how densities of raccoons and opossums differ among common southeastern habitat types, like those found on the SRS. Using this data, we can improve the efficacy of USDA’s baiting strategy in the region,” he said.

A major component of the research is the cost-effective approach of distributing oral placebo baits in the habitats to determine the percentage of baits eaten by the raccoons as well as the percentage taken by non-target species such as opossums. The results will provide guidance to USDA on the most efficient method to distribute oral vaccines to ensure a high rate of inoculation in the species.

Rhodes said ensuring the health of wild species is vital to ensuring human health, particularly in the case of zoonotic diseases. He also said research data that may be used to combat the spread of the disease is critical to the environmental stewardship goals of DOE and other federal agencies that are large landholders in the U.S.

Through its cooperative agreement with the DOE, UGA has been able to develop facilities, expertise, and capabilities to use the SRS as a testing ground for research focused on solving large-scale issues critical to human health and the control of zoonotic disease in the U.S.

“Since climate change has the ability to alter sex ratios, we could see either a dominant female or male population in the future that lacks the ability to reproduce.”

Combining this data with use of trail cameras to elucidate the number of wild pigs in these areas can help farmers and land managers prioritize locations for control efforts.

 Among her many honors, Sharitz was recognized by the Environmental Law Institute, which presented her with its National Wetlands Award in Science Research in 2010

Throughout his career he has advised twenty-seven graduate students, eleven postdoctoral researchers, and provided experiential learning opportunities for more than forty undergraduate students.

The researchers report the birds’ physical characteristics and social nature influence where they spend their time.

The five-year, $1.18 million CAREER grant will fund research about the impacts of wastewater on the structure and function of tropical rivers, particularly the impacts of pollution that results from aging and obsolete wastewater infrastructure.