College of Natural Resources, UC Berkeley

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May 15, 2003

UC Berkeley Study Finds New Clues to the Fate of Smog That Ends Up In Sierra Nevada Forests

by Sarah Yang

Berkeley - Most scientists believe that when smog ozone is taken up by the forests of the Sierra Nevada, it is mostly absorbed by trees and plants. But new research at the University of California, Berkeley, suggests a large proportion of the ozone is actually transformed by chemical reactions in the air with compounds emitted by the forest.

The new findings, published online in April in Geophysical Research Letters, indicate that much of the ozone entering pine forests in the Sierra Nevada could be reacting with natural hydrocarbons emitted by plants. One outcome of this reaction is the formation or growth of aerosols.

"We care about aerosols in the atmosphere because they can affect human health and visibility," said Allen Goldstein, associate professor of biogeochemistry at UC Berkeley's College of Natural Resources and principal investigator of the study. Aerosols also potentially impact climate by increasing the formation of clouds and scattering sunlight. They are generally believed to have a cooling effect on the environment.

The study has implications for managing both air quality and air pollution impacts on forests. Previous studies have shown that air pollution from manmade sources such as car exhaust and power plants travels up from the Central Valley to the Sierra Nevada Mountains. The ozone formed from those emissions is considered damaging to forest health - it leads to discoloration and loss of needles from pine trees, inhibits growth and potentially increases susceptibility to diseases.

"In order to relate the dose of ozone to the damage, we need to do a better job of quantifying uptake by the trees," said Meredith Kurpius, lead author of the study and a former UC Berkeley graduate student in ecosystem science.

"The forest acts as a type of 'sink,' a place where a lot of the ozone generated as pollution ends up being taken up by the trees, deposited on surfaces or transformed in chemical reactions in the air," said Kurpius, now a postdoctoral research associate at Oregon State University's Department of Oceanic and Atmospheric Science. "Our findings suggest that, in the summer, half of the ozone is lost by another mechanism that had never been quantified before."

In addition to forming aerosols, the reaction of ozone with hydrocarbons emitted by plants creates hydroxyl radicals, important elements in atmospheric chemistry near the Earth's surface.

"Traditionally, people thought that most of the ozone was going into the plants and trees and causing damage, but the amount of ozone lost through other processes was never measured," said Goldstein. "We set out to determine what controls the amount of ozone taken up by the forest, and what we found was very surprising."

Over the course of a year, the UC Berkeley researchers determined the amount of ozone lost in a ponderosa pine plantation in the Sierra Nevada Mountains, about 50 miles from Sacramento. They estimated that 45 to 55 percent of the ozone was lost in the summer through gas phase chemical reactions within the forest canopy.

As the temperature cooled going from fall into winter, the amount of hydrocarbons released by the trees decreased, leading to a subsequent decrease in the amount of ozone lost through gas phase chemistry. During the cooler months, more ozone was absorbed by the trees and plants, according to the study.

Kurpius and Goldstein suggest that the main hydrocarbons reacting with ozone are a group called terpenes. These highly reactive chemicals involved in the atmospheric reactions with ozone are so unstable that they are difficult to measure, but Goldstein said understanding such natural processes is necessary in the development of scientifically based air quality management policy.

"In order to develop legislation to control the amount of aerosols in the atmosphere, we need to better understand how much of the aerosol results from natural processes and how much is coming from manmade sources," he said.

The research was supported by the Environmental Protection Agency, the National Science Foundation and the California Air Resources Board.

May 12, 2003

Chemical in Broccoli Blocks Growth of Human Prostate Cancer Cells

by Sarah Yang

Berkeley - Those seeking yet another reason to eat their veggies, take note. Researchers at the University of California, Berkeley, have found that a chemical produced when digesting such greens as broccoli and kale can stifle the growth of human prostate cancer cells.
The findings show that 3,3'-diindolylmethane (DIM), which is obtained by eating cruciferous vegetables in the Brassica genus, acts as a powerful anti-androgen that inhibits the proliferation of human prostate cancer cells in culture tests.

"As far as we know, this is the first plant-derived chemical discovered that acts as an anti-androgen," said Leonard Bjeldanes, professor and chair of nutritional sciences and toxicology at UC Berkeley's College of Natural Resources and principal investigator of the study. "This is of considerable interest in the development of therapeutics and preventive agents for prostate cancer."

Vegetables such as broccoli, Brussels sprouts, kale and cauliflower are rich sources of indole-3-carbinol (I3C), which the body converts into DIM during digestion. Over the years, Bjeldanes has been researching the anti-cancer properties of dietary indoles with co-author Gary Firestone, UC Berkeley professor of molecular and cell biology.

The new study will be published in the June 6 issue of the Journal of Biological Chemistry, but is now available online.

Androgen is an important hormone for the normal development and function of the prostate, but it also plays a key role in the early stages of prostate cancer, which is typically treated with anti-androgen drugs.

In most cases of prostate cancer, the cancer cells develop resistance to androgen and grow independently of the hormone in later stages of the disease.

In the new study, the researchers conducted a series of tests comparing the effects of DIM on androgen-dependent human prostate cancer cells as well as on their androgen-independent counterparts.

They found that androgen-dependent cancer cells treated with a solution of DIM grew 70 percent less than the same type of cancer cells that had been left untreated. The same solution had no effect on the growth of androgen-independent cells, pointing to androgen inhibition as the key mechanism by which the DIM is acting.

This was confirmed with further tests showing that DIM inhibits the actions of dihydrotestosterone (DHT), the primary androgen involved in prostate cancer. DHT stimulates the expression of prostate specific antigen (PSA), which acts as a growth factor for prostate cancer. When androgen-dependent cells were treated with DIM, the researchers found a drop in the level of PSA.

"There are lots of things that can stop growth, but the fact that DIM decreases the expression of PSA shows that it is functioning at a gene expression level," said Bjeldanes.

Comparisons of the molecular conformation of DIM show that it is similar to Casodex, a synthetic anti-androgen on the market. "DIM works by binding to the same receptor that DHT uses, so it's essentially blocking the androgen from triggering the growth of the cancer cells," said Hien Le, lead author of the study and a former graduate student in Bjeldanes' lab.

"DIM is chemically different than Casodex, but it behaves similarly in how it blocks the effects of androgen," said Le, who received her PhD in molecular and biochemical nutrition in 2002.

These latest findings appear to add new burnish for this class of chemicals that has already shown promise in prior studies as a therapeutic agent for breast and endometrial cancer. For instance, a 1998 study by Bjeldanes and Firestone showed that I3C keeps breast cancer cells from duplicating.

"We are investigating the potential use of indoles in combination with current anti-cancer drugs on the market," said Firestone. "The advantage of combination therapy is that you can back off on the dose of a single agent and thereby reduce potential side effects."

Prostate cancer is the second leading cause of cancer deaths in American men. One in 10 men in the United States will develop signs of prostate cancer in his life, and more than 100,000 new cases are reported each year.

Le pointed out that the incidence of prostate cancer among men in Asia - where consumption of vegetables is higher - is significantly lower than that for men in the United States. However, the risk for Asian immigrants rises to levels comparable to American men the longer they stay in the United States, suggesting that factors such as diet and lifestyle play a role in the development of prostate cancer.

"There are already plenty of health reasons for consuming more vegetables such as broccoli," said Le. "This study suggests that there are even more benefits to a diet rich in these phytochemicals when it comes to preventing prostate cancer."

The study was also co-authored by Charlene Schaldach, a former PhD student in the Bjeldanes lab.

The research is supported by the California Cancer Research Project and the National Institute of Environmental Health Sciences, part of the National Institutes of Health.

May 11, 2003

Agroecology Exchange Program Brings Interdisciplinary Study to US, Brazilian Students


by Malgorzata Wozniacka

For five Brazilian students at the College of Natural Resources studying sustainable agriculture, and for their four Berkeley counterparts in Santa Catarina, Brazil, Fall semester 2003 was spent learning not only about farming, but also about each other's cultures.

The students were part of the US-Brazil exchange program in agroecology funded by the Department of Education-FIPSE and Brazil's CAPES, which brings together a group of students, educators and researchers from the University of California, Berkeley; the University of Nebraska; and two Brazilian Universities, UNICAMP and Universidade Federal de Santa Catarina.

Agroecology is the study of agricultural systems that are productive but also resource conserving. The students in Berkeley and in Brazil audited classes and worked in interdisciplinary teams to study the various social, cultural, economic and environmental aspects of sustainable agriculture.

According to Miguel Altieri, Berkeley professor and program coordinator, the students' focus is on organic agriculture and small farming. This is important, because sustainable agriculture is key for combating rural poverty, enhancing food security, and conserving natural resources. Altieri has been doing research in agroecology since 1981 and will participate in the exchange program again next year.

The exchange program puts an emphasis on practical learning. At Berkeley, the five Brazilian students visited both organic and conventional farmers and concuted research on agroecology as part of the program in order to better understand California agriculture.

All of them admitted to being surprised.

"It's a market-oriented, industrial system of agriculture here," summarized Marcos Alberto Lana, 22. "In Brazil, the most important thing is not only to produce for the market but to also to provide food for your family. It's about food security, while here it's only about profit."

For the Brazilians, who hailed from the south of Brazil which is known for small farms, the most jarring aspect of the big-farm system in the US was its lack of ties to the community.

"The concept of agroecology is not just about not using pesticides. It's also a social issue," said Lana. "People in the U.S. think more about money, so there is big pressure to specialize."

During a visit to a farm in Fresno, the students were surprised that the only crop the farmer grew was cotton. He bought everything else from the store - a practice unheard of in the south of Brazil.

The students hope that the US-Brazil exchange program will help spread small-scale farming, perhaps even in the US.

"Our presence here is important to help people have another view," said one of the students, Marina Baptista, 22. "People in the United States are so used to big farmers. Talking to an American friend and trying to convince him that agroecology can be productive was very hard. By coming here, we can make people aware that small farms can be productive while preserving the environment and rural communities."

While the Brazilians said they found American agriculture "inefficient", because it overlooks social implications, they were also very impressed by the so-called organic revolution.

"People actually care what they eat here," Baptista said. "They are better informed. In Brazil, people are poor and they don't care about their food quality. The ultimate goal is to give everybody access to organic food, not just to the rich people who can afford it."

Meanwhile, four American students each spent a month living at a home-based farm in Brazil. The home-stay is a cornerstone of the agroecology program at the University of Santa Catarina. Students get college credit for writing a report about their experiences.

Paul Roge, 22, lived on a 93-acre farm near Florianopolis. He says he learned part of the family and farm history, as well as the farmer's approach to commercial and home production. The family he stayed with sells dairy and grains to a regional cooperative, and pigs to industry.

"It was a wonderful experience," he wrote from Brazil by e-mail. "I hope to get a sense of what life is like for small-scale family farms in southern countries. I want to understand their dreams and realities, and to find some ecologically mindful examples for what agriculture could be or what it is already."

In addition to the home-stay and to taking classes at the university, Roge and his fellow Berkeley students also took numerous field trips, visiting farms that practice sustainable agriculture, and met with members of "Terra Viva", the Landless Workers Movement.

It is this very movement that the Brazilian students at Berkeley hope to support in the future. Their stay in the US is important, they say, because big farms similar to those in the US are destroying the ecosystem in central Brazil. Also, small farms are put out of business by big ones, and unemployed farmers migrate to cities in search of a better life.

"This exchange program came at the right time," said Diogo Feistauer, 22, one of the Brazilian students. "The new president of Brazil has been pushing projects on agricultural issues. We are hopeful that we can contribute to sustainable farming in the future as experts. There are actually many vacancies for agronomists."

And all of the students learned more than just farming. The Brazilian students lived through their first earthquake, experienced their first Halloween, and fostered some conversations with open-minded Americans. They have also had to battle stereotypes about Brazil, and to convince people that Brazilians are not just about carnivals, soccer, and the Amazon.


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UC Berkeley Study Finds New Clues to the Fate of Smog That Ends Up In Sierra Nevada Forests
Chemical in Broccoli Blocks Growth of Human Prostate Cancer Cells
Agroecology Exchange Program Brings Interdisciplinary Study to US, Brazilian Students


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