Today

“Biological Control of Greenhouse Pests with Natural Arthropod Enemies“

Urs Wyss

122 Briggs, 12:10 to 1 p.m.

Sponsored by the entomology department

“Power on. Design thinking (arrow) energy“

Ted Howes

Technocultural Studies Building (south of Art Building), noon to 1 p.m.

Sponsored by the design program

“Cross-regulation of a Dual Two-component System in Escherichia coli K-12“

Chris Noriega, Hsia-Yin Lin

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

Sponsored by the microbiology department

Thursday

Integrated Analysis of Biomedical Data: From Connectivity to Cancer

Ron Shamir

1065 Kemper Hall, 4:10 to 5 p.m.

Sponsored by the department of computer science

Monday, Oct. 20

“Integrated Control and Decision Support for Powdery Mildew Management in Commercial Vineyards Using a Native Mycophagous Ladybird Beetle“

Andrew Sutherland

115 Hutchison, 1:10 to 2 p.m.

Sponsored by the department of plant pathology

“Regulation of Meiotic Chromosome Segregation: Controlling the Crossover Landscape“

Jennifer Fung

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

Sponsored by Genetics Graduate Group, Graduate Group Complex

More seminars can be found at calendar.ucdavis.edu. If you want to have a seminar published here, e-mail us at features@californiaaggie.com. 

In collaboration with the San Francisco Estuary Institute, UC Davis researchers have made headway in understanding the sources of toxic mercury in the San Francisco Bay and Delta. The findings, revealed in SFEI’s annual report of the Regional Monitoring Program for Water Quality (RMP), indicate that changes in current habitat management techniques could prevent mercury from entering the food web and threatening the health of wildlife and humans.

A small fraction of elemental mercury is converted to the organic form methylmercury by bacteria in the sediments of aquatic environments. Metyhylmercury poses a health concern if it enters the aquatic food web and builds up to toxic levels further up the food chain.

According to SFEI’s annual report, this threat is a reality. Researchers at the U.S. Geological Survey documented a higher risk of hatch failure for the eggs of exposed Bay water birds, and mercury concern is the main incentive for fish consumption advisories in the Bay.

Insights about the controlling factors and areas where methylmercury is most problematic may indicate what can be done in terms of management, said Richard Looker, an engineer for the San Francisco Bay Regional Water Quality Control Board.

Darell Slotton, a research ecologist with the department of environmental science and policy at UC Davis, developed a sensitive approach to trace and record sources of mercury contamination using small, young fish that tend to stay in the same area.

“We can use these little fish that are out there in the environment, like the canary in the goldmine, as an indicator of the levels of mercury exposure in different places around the Bay and the Delta, and at different times of year,” Slotton said.

His method was refined over a period of 20 years, and uses a technique to determine mercury levels in individual fish.

Slotton monitored fish samples collected every four months from about 25 sites scattered around the Sacramento-San Joaquin Delta and the Central Valley. The RMP used a similar approach in a smaller study with fish collected around the Bay from 2005 to 2007. Both efforts were part of the Fish Mercury Project, a three-year CALFED-funded program to examine and monitor potential changes in the amount of mercury in fish in the Bay-Delta watershed.

One highlight of Slotton’s findings linked elevated mercury contamination to lands that underwent periodic flooding. These included the Yolo Bypass, which is deliberately flooded during the rainy seasons in order to divert water from the Sacramento River away from many communities, as well as normally dry areas in the Central Valley that flooded during 2006.

Other potential sources for contamination are the vast wetland restoration projects that have been created in the Bay-Delta watershed.

The conventional knowledge 10 years ago was that any wetland habitat is a suspected methylmercury production source, Slotton said.

Instead, he and other groups found that many sites that are often submerged in water, including the restored wetlands, are not problem areas for food web contamination.

“The biggest implication is focusing our management efforts on … these wetlands that go dry and are flooded,” Slotton said. “A lot of places that undergo that kind of cycle are manmade.… We can keep these places wet rather than letting them go dry in the first place, and the fish will tell us if it’s working or not.“

No management solutions have been implemented as a result of the project, according to Looker.

“We can’t really draw conclusions until we have a sufficient amount of data to know that the patterns we’re seeing are not just random but that they’re consistent and repeated through time,” Looker said.

Although the Fish Monitoring Project ends this year, Slotton will continue working with the RMP to annually monitor small fish around the Bay.

“Mercury remains an important focus for the RMP,” said SFEI senior project manager Meg Sedlak. “More extensive small fish monitoring is a key component of the RMP Mercury Strategy.“

ELAINE HSIA can be reached at features@californiaaggie.com

Although the mosquito season comes to a close as the chill of winter approaches, fly season is in full swing as autumn’s temperatures ideally foster their abundant breeding.

“This time of year is perfect for flies to reproduce,” said UC Davis entomologist Lynn Kimsey, who heads the department of entomology. “And Davis is the perfect place.“

The common housefly, also known as Musca domestica, breeds in manure, sewage or any decaying object. For this reason, the surrounding fields and even the cows on campus are ideal breeding grounds for this common household pest.

Temperature is also a factor in the fly’s life cycle. California’s characteristically warm fall months allow flies to reproduce at an alarmingly fast pace.

“Flies at this time only live for about two and a half weeks but can deposit up to 150 eggs during that time,” Lynn said. “Their numbers will grow exponentially larger.“

Even though they only seem like pests, having the housefly around human food can carry significant health consequences.

According to the University of Rhode Island’s Landscape Horticulture Program’s website, the mouthparts of the fly are adapted for sponging up liquids and therefore cannot bite. To bypass this, they eat solid foods by regurgitating their saliva and stomach contents and then re-consume it.

“If a fly lands on that hamburger that you’re eating and had just came from a pile of feces, then that will be on your hamburger, as well as any bacteria in it and any bacteria on the fly’s feet,” Lynn said.

This method of feeding makes the common housefly an excellent carrier and transmitter of diseases to animals and humans. They are known to transfer at least 100 different pathogens and cause more than 65 diseases in humans, according to the URI’s website.

Many bacterial and viral diseases can be spread from flies to humans this way. They include Typhoid, cholera, salmonella, tuberculosis, dysentery, E. coli, parasitic worms and even infective hepatitis.

“The probability of a housefly infecting a human is not good, but there is still a propensity of transferring and flies remain an exceedingly important vector of infection transmission,” said Lynn’s husband Robert Kimsey, a UC Davis medical entomologist.

Flies can also infect domestic animals such as cattle and other animal products.

“Cows can eat the food flies have contaminated and be infected with E. coli in this way,” Lynn said.

The life cycle of a housefly has three stages: maggot, pupa and adult. A female housefly deposits its eggs in decaying organic matter. After a day or two, the eggs hatch creating worm-like maggots, which eat the decaying matter around them for nourishment. The maggots then pupate into a cocoon-like structure until they emerge as an adult fly. The whole process can be completed between one and three weeks.

The natural predator of flies in their egg state is the fly parasite. A fly parasite lays its own eggs in the fly egg, killing the fly before it even hatches.

Many agricultural sites use these fly parasites as a way to control the housefly population because they do not affect or bite animals and humans themselves, according to the U.S. Department of Agriculture’s website.

Some insects, birds and amphibians also act as predators of the housefly.

Humans have also developed other methods for preventing the transmission of diseases from houseflies, which has affected our current state of living.

“The development of window screens and indoor plumbing can be attributed to the housefly,” Lynn said.

In the earlier part of the century, there was a higher infant mortality rate because flies would come from the outhouse and land in the kitchen, contaminating food and bottled milk for babies, Lynn said.

Nowadays, besides trying to keep flies away from decaying organic material, the best way to control flies is to use boric acid in the bottom of dumpsters and use fly bait around adult food sources, according to Ohio State University Extension’s website.

If that does not work, there is always a fly swatter.

NICK MARKWITH can be reached at features@californiaaggie.com

UC Davis is one of two schools in the country with a nematology department. What’s a nematode, you ask? Professor Valerie Williamson can not only tell you that a nematode is a microscopic worm, she can also tell you its DNA sequencing and the massive impact it has on the agricultural world today. Williamson is a professor of nematology, focusing her research on plant parasitic nematodes – the cause of over $50 million of plant damage in the U.S. The California Aggie sat down with her to chat about nematodes, her research and even her taste in produce.

Why study nematodes?

Well, lots of reasons. They’re really interesting. They’re one of the largest phyla of animals in the whole world. There’s a lot of free living [nematodes] that affect the soil and environment; there are animal parasites that have caused lots of diseases in animals, including humans.

[For instance] in Africa, you’ve probably seen Elephantitis in your biology books, which is caused by a nematode. Probably a third of the world’s population has nematode infections-mostly developing countries. So they’re very common.

What kind of nematodes do you research?

I study the ones that infect plants. They’re a big problem because most of them cause $50 to $100 million in damage worldwide. For example, I work with tomatoes, and nematodes can be a big problem on tomatoes.

In fact, a lot of home-growers have nematodes on their tomatoes. Sometimes if your tomato isn’t growing very well, you can pull it up and find these big knots on the root – that’s due to nematodes.

So it’s a pretty big problem around here – especially if you have heirloom tomatoes because they don’t have resistance. In agriculture in California, some of the ways they control these nematodes is that they put pesticides on the fields like Methyl Bromide, which is being banned because it’s damaging the ozone layer. One of the uses of [Methyl Bromide] is for killing the nematodes in the soil. So right now, there’s a lot of concern about how we’re going to kill these nematodes without harming the environment. A lot of the things that kill them are really nasty and toxic.

The other thing bad about [nematodes] is that they kill everything in the soil. And there are good things in the soil that can help kill a nematode. So it’s difficult to find a sustainable way to control [what is killed in the soil].

I’m working more at the basic research biology end of that, so in order to figure out better ways – instead of hitting [a nematode] on the head with a hammer using a pesticide, you have to understand the organism better. So I’ve been working on plant parasitic nematodes, trying to understand how they work and if there’s any weakness in their system, [so] we can figure out a control that we can just target instead of the good guys.

So nematodes have a lot of impact on California agriculture?

Yeah, they have a lot of impact. I study the root knot nematode which affects not only tomatoes but also just about everything. Fruit trees, grape vines, cucumbers, melons and lots of other plants. There are other nematodes that have a big impact on trees, like walnut trees, that are causing a lot of damage.

Does all this research on food ever make you hungry?

Well, I like a good tomato. But the problem is that the heirloom tomatoes really taste better than the ones you buy in the grocery store, but [heirlooms] are susceptible to nematodes! Sometimes when I go to the grocery store and look at the organic carrots, I check the root at the bottom for bumps in there. I know that inside of those little bumps there’s a nematode, so sometimes that makes me not hungry. You can eat them and it doesn’t hurt you at all, it‘s just an unappetizing thought.

So you eat organic food?

Only when it’s on sale. I don’t go out of my way for it because I think it tends to be overpriced. Although sometimes I buy it at the farmers market because I know the people who grow it locally take good care of their land.

Who is your favorite scientist?

My husband! He’s a virologist here.

What do you teach?

I teach molecular biology lab techniques, so it’s a lab course in animal genetics. It’s a course that a lot of undergraduates take. I also teach a course in agricultural biotechnology that discusses transgenic [genetically modified] plants and the pros and cons of them.

Have you been able to form a relationship with the students in your lab classes?

Oh yeah, we talk all the time! The interaction with the students is what I value most about being a professor. Both classes I teach are relatively small and I get to interact individually with the students and I really like that. I like that a lot better than standing in front of 100 students lecturing. I like to talk to them a lot more individually; it’s more fun.

Do you think the pros of transgenic plants overweigh the cons?

[Yes,] I think so. There’s a lot of issues with them because of the way they’ve been developed by these big companies. In general though, they’re a good idea because you can reduce pesticides.

Have you ever had a bad run-in with a transgenic plant protester?

No not really – other people have. When they first sold genetically modified tomatoes, they sold them in a grocery store in town and protesters came and dropped tomatoes in the parking lot. In other places there’s big controversy, but in Davis since we’re an agriculture school there’s not so much.

So when you were a kid, what did you want to be when you grew up?

I always liked biology – I never knew exactly what it was – but I did think about being a veterinarian. And I wanted to become a medical technician. But research has always been my point of interest.

Do you have pets?

Yes, I have two dogs. They’re pound rescues. They’re really nice pets.

Where are you from originally?

New Hampshire. I came to Davis for graduate school. I did my Ph.D. work at Davis and my undergraduate work in Boston. I went to Seattle for my post-doctoral and then came back to Davis. A lot of people come back to Davis.

Which has been your favorite place?

I like being right on the ocean, so probably Bodega Bay. We’re planning to retire to Bodega Bay.

Are you retiring soon?

Well, we just sequenced a [nematode] genome, so a lot of possibilities have opened up that we didn’t know about before. That makes it hard to leave.

LAUREN STEUSSY can be reached at features@californiaaggie.com.

New tests for Down syndrome have no known risks of miscarriage

Scientists have developed a new, non-invasive technique to test for Down syndrome that differs from the traditional tests that may cause miscarriages. The new procedure only requires a blood sample from the pregnant woman.

Down syndrome is a disorder that occurs when a baby is born with three copies of Chromosome 21 instead of two. A person with Down syndrome generally has mental retardation, unusual facial characteristics and high risk of heart problems.

The traditional testing techniques, amniocentesis and chorionic villus, sampling require samples of fetal cells in order to count the chromosomes. These techniques are invasive and include a risk of miscarriage.

The new blood-sampling tests have been performed by a Stanford and a San Diego-based company called Sequenom. As of Oct. 6, the testing records have shown no false positives or negatives. However, testing is still in its initial stages – Stanford has tried the test on only 18 samples whereas Sequenom has tested on approximately 400 samples.

A former consultant Sequenom will conduct the test on samples from 10,000 women. The company plans to sell the test beginning next June.

Stanford scientists said the tests may begin at $700 per sample but costs are rapidly decreasing. (nytimes.com)

Pediatricians recommend higher doses of Vitamin D

The American Academy of Pediatrics recommends double the dose of Vitamin D for newborns, children and teens. The new recommendation of 400 units replaces one made in 2003 suggesting a daily 200 units of Vitamin D.

According to AAP‘s research, millions of children may have to take supplements to meet this new requirement. The increase in daily recommendation for the vitamin is based on recent research that Vitamin D contains more beneficial properties than keeping bones strong: It can also reduce risk for cancer, diabetes and heart disease.

Although babies are recommended to be breastfed for at least one year, it is suggested that they also consume supplements or formula that contain higher doses of Vitamin D. Supplements for young children are offered in drops, capsules and tablets.

As commercial milk is fortified with Vitamin D, teens and adults can meet the daily requirement by drinking four glasses of milk per day. Vitamin D can also be obtained in oily fish such as tuna, mackerel and sardines.

Additionally, sunlight can help the body produce Vitamin D. It is believed that 10 to 15 minutes spent in the sun weekly is sufficient, but Vitamin D supplements are still recommended to avoid risk of skin cancer. (HealthDay)

HPV vaccine becomes more prominent among teens

The Center for Disease Control and Prevention estimates that approximately 25 percent of teenage girls received at least one dose of a human papillomavirus vaccine, Gardasil, in 2007. The estimate is the first of its kind and will be included in a survey of vaccination rates among teens ages 13 to 17.

Gardasil is administered in three doses and is intended to protect against four strains of HPV. Two of the four strains are known to account for 70 percent of cervical cancer cases. It is recommended that girls between ages 11 and 14 receive the vaccines before they become sexually active.

Since 2005, the list of recommended vaccines has grown to include three more types. In addition to Gardasil, teens are also recommended to receive an extra dose of Varicella, which protects against chicken pox.

Results from the survey also show an increase in vaccinations that protect against tetanus, diphtheria, pertussis and meningitis.

(The Wall Street Journal Online)

THUY TRAN compiled SCIENCE SCENE and can be reached at features@californiaaggie.com