Environmental Protection Agency designates carbon dioxide a pollutant

The EPA formally declared on Friday that carbon dioxide as well as five other heat-trapping gases are pollutants endangering public health and welfare.

The move, which has been anticipated since the election of President Barack Obama, begins a 60-day comment period that must be completed before any regulations can be set in motion.

The EPA called the science supporting its decision “compelling and overwhelming.“ Opponents argue that regulating carbon dioxide admissions will eliminate jobs and increase energy costs.

In 2007 the United States Supreme Court ordered for the agency to determine if heat-trapping gases pose a threat to public health and the environment in Massachusetts v. EPA.

Despite agency scientists‘ nearly unanimous stance that the gases were dangerous, the Bush administration declined to take action.

The EPA has not yet laid out any specific targets or new requirements to reduce heat-trapping gases, but is expected to do so following the comment period.

(Source: nytimes.com)

Study finds sex ratio varies by latitude

While no one knows exactly why more boys are born than girls worldwide, a new study out of the University of Georgia has found that proximity to the equator could be a factor. Data suggests that populations living closer to the equator have a smaller sex ratio difference.

Many factors are thought to influence the skewed sex ratio – for example war, economic stress, age, diet and selective abortion all correlate with difference – but determining the effect of a single variable is nearly impossible.

Latitude, however, is a phenomenon not affected by socioeconomic factors. By comparing the sex ratios of 202 capital cities in relation to their latitude, political stability, economic status, annual variations in day length and temperature, as well as other socioeconomic indicators, researchers were able to determine that the effect of latitude held constant across all lifestyle and status variations.

The correlation even persisted after removing data from Asian and African countries that have been known to abort or kill baby girls.

Possible explanations for the phenomenon are all speculative. It could be that there is some benefit to having more girls in warmer regions or genetic and racial differences. Researchers say it‘s possible that humans are responding to factors programmed into them long ago, before cultural and socioeconomic factors.

(Source: nytimes.com)

Bacteria discovered under Antarctic glacier

Scientists from Montana State University and Harvard University have discovered a rare bacteria living underneath an Antarctic glacier.

The colony was discovered when researchers were investigating the flow of blood-red water from underneath the glacier. The flows, termed “Blood Falls,“ have been a long-standing intrigue to scientists. The researchers happened to discover the bacteria when determining that the blood color comes from iron compounds.

The bacteria have survived for millions of years on sulfur and iron compounds. Scientists say it is possible that because the colony has been isolated for so long, it could provide insight into how life could exist on other planets and under ice.

(Source: Associated Press)

ALYSOUN BONDE compiles Science Scene and can be reached at campus@theaggie.org. 

Today

Transforming Transportation and Energy: Politics and Technology

Dan Sperling, director, Institute of Transportation Studies, and professor of civil engineering and environmental science and policy – UC Davis

360 Shields Library 12:10 to 1 p.m.

Sponsored by the Institute of Governmental Affairs

Sequential Speciation: Why Are There So Many SMALL Animals?

Andrew Forbes, postdoctoral scholar – UC Davis department of entomology

122 Briggs 12:10 to 1 p.m.

Sponsored by entomology

Signaling in Electric Fish: Behavior, Neurobiology, Molecular Evolution

Harold Zakon, Dr. – University of Texas at Austin

1022 Life Sciences 1:10 to 2 p.m.

Sponsored by Neurobiology, Physiology and Behavior College of Biological Sciences

Thursday

Oncogenomics Approaches for Investigating Mechanisms of Cancer Pathogenesis and Therapy Resistance

Dr. Cliff Tepper & Dr. Jeff Gregg, assistant research biochemist, dept. of biochem & mol. med. & assoc. professor, dept. of pathology – UC Davis

UCD Medical Center auditorium 9 to 10 a.m.

Sponsored by UC Davis Cancer Center

Mechanisms Underlying Accurate Meiotic Chromosome Segregation in C. elegans

Monica Colaiacovo, assistant professor – Department of Genetics, Harvard Medical School

1022 Life Sciences 4:10 to 5 p.m.

Sponsored by the College of Biological Sciences and various graduate groups

Friday

What Is the Mouse Trying to Tell Us? The Post-genomic World and One Medicine

Robert D. Cardiff, M.D., Ph.D., director, Center for Genomic Pathology

1022 Life Sciences 11 a.m. to noon

Sponsored by the Biotechnology Program

Stem Cell Therapies – Options for Avoiding Immune Rejection

Jan Nolta

1005 Genome Biomedical Sciences Facility 2:10 to 3 p.m.

Sponsored by medical microbiology and immunology

Arboretum Talk: California Native Plants for the Garden

David Fross, founder of Native Sons Wholesale Nursery in Arroyo Grande and co-author of California Native Plants for the Garden

Wyatt Theater, Old Davis Road 7 to 8 p.m.

Sponsored by Friends of the UC Davis Arboretum

Sunday

Film Screening: Atom Smashers

Directors Clayton Brown and Monica Ross – directors of the documentary

194 Chemistry 7 to 10:30 p.m.

Sponsored by HEFTI, dept. of physics

Monday

Cognition and Dogs – Why Does It Matter?

List Lit, graduate student – M.I.N.D. Institute and departments of neurology & psychiatry, UCD

Weir Room, 2151 Meyer noon to 1 p.m.

Sponsored by animal science

Identification of Factors Mediating Cold Therapy of Xylella fastidiosa-infected Grapevines

Melody Meyer – department of plant pathology, UC Davis

115 Hutchison 12:10 to 1 p.m.

Sponsored by plant pathology

Tuesday, April 28

Spray Nozzel and Fluid Property Sensors for Process Control: Theory, Experiments and Development

Ken Giles, UC Davis

2045 Bainer 1:10 to 2 p.m.,

Sponsored by biological agricultural engineering

More seminars can be found at calendar.ucdavis.edu. If you’d like to publish a seminar here, send an e-mail to campus@theaggie.org. XXX

Thirty years after PCBs (polychlorinated biphenyls) were banned in the U.S., UC Davis researchers have discovered how the class of toxic chemicals may cause behavioral disorders in some children, even at the low levels that people encounter now.

The series of three new studies together reveal that PCBs can disrupt cellular signals crucial for normal brain development and function.

Earlier studies linked PCBs to a range of neurological impairments such as autism, ADHD and seizure disorders.

The new studies provide a compelling explanation for this link and furthermore implicate the most abundant and least regulated PCBs – which were once thought to pose less threat to human health – as particularly harmful agents in the developing nervous system, the researchers said.

“Not all PCB forms will have this same effect, but the work represents a clear picture of the damage that these chemicals – and ones like it – can cause,” said Thomas Zoeller, a biology professor at University of Massachusetts, Amherst who was not involved in the studies.

PCBs were used in a wide variety of products such as electronic components, pesticides and flame retardants. They do not easily degrade and substantial amounts persist in the environment, accumulating in the air and in fish that people consume from hotspots like Chicago and the Great Lakes.

In the first study, published in Environmental Health Perspectives, researchers simulated in animals the type of PCB exposure that children might have in order to find out how the chemicals alter the way brain neurons (cells) develop.

The researchers exposed rat pups in utero and during weaning by feeding mother rats a mixture of PCBs similar to those found in the environment. Compared to their untainted counterparts, pups that had low levels of PCB exposure exhibited slower learning curves in a water maze exercise designed to stimulate patterns of neural growth associated with learning and memory.

In brain regions affected by developmental disorders, PCBs altered the plasticity (shape) of neurons, as well as the changes in neural growth and plasticity typically observed with water maze training. The researchers also noticed higher levels and activity of calcium channels in neurons known as ryanodine receptors (RR), which generate electric signals that influence plasticity.

“We think, in part, it’s because that the function of the RRs have been altered [by PCB exposure] over a long period of time [that we saw all these changes],” said Isaac Pessah, professor and chair of the department of molecular biosciences at the UC Davis School of Veterinary Medicine, who co-authored all three studies.

At higher doses, these effects are not seen because the PCBs trigger defensive mechanisms in the body that remove the chemicals before they reach the brain, he explained.

To get a clearer sense of the cause and effect relationship between PCBs and RR activity in the second study, which was published in Toxicology and Applied Pharmacology, the researchers exposed rat brain tissue slices to individual PCBs.

Although one was more potent than the other, both of the tested PCBs had excitatory effects on brain tissue at low doses, which could be dampened by adding a compound that blocks RR signaling.

Normal brain function depends on a fine balance between excitatory and inhibitory pathway signals in the nervous system, and we showed that PCBs can disrupt this balance through the RRs, Pessah explained.

“In kids with autism [and some other disorders], the inhibitory side seems to be not operating quite as well as it should be,” he said. “So these kids tend to start out being somewhat imbalanced,” a problem that can be intensified “…with compounds [like PCBs] that enhance the excitatory side preferentially over the inhibitory side.“

The researchers sealed their conclusion with their third and newest study, which was published in Public Library of Science – Biology. They captured high resolution snapshots of PCB molecules directly interacting with RRs and locking the channels in the open active form, which account for the PCB effects seen in the first two studies.

“We found out that it was only those [PCBs] which act at [and activate] the RR … that were causing these effects on neurotoxicity and excitability,” said Pamela Lein, lead author of the Environmental Health Perspectives animal study and an associate professor in the department of molecular biosciences at the UC Davis School of Veterinary Medicine.

Because certain populations may be at higher risk for PCB-linked developmental disorders, the researchers next plan to study PCB effects on mice that carry some of the same RR genetic variants that humans do.

“We would predict that people that have genetic mutations that target [signaling] balance in their neurons would be more at risk for developing PCB developmental neurotoxic effects,” Lein said. “So [this type of study] might be able to help us … eliminate or to protect and prevent some problems in people by minimizing their exposure to PCBs.“

The findings also raise speculations that chemicals similar to PCBs that are widely used today might target RR function and contribute to impaired brain development, the researchers said.

“Without this work, the scientific community and government regulatory agencies are stuck in a quagmire of ambiguity about the relationships between human disease and chemical exposures and the relative safety of our living conditions,” Zoeller said.

ELAINE HSIA can be reached at campus@theaggie.org.