scrambles frog sex organs atrazine-contaminated Exposure to atrazine demasculinizes ponds in the Midwest to see tadpoles and can turn them into her- if such reproductive abnor- maphrodites with both male and fe- malities occur in frogs in male sexual characteristics, UC Berke- the wild. They turned up ley scientists have found. many native leopard frogs In the April 16 Proceedings of the Na- (Rana pipiens) with similar tional Academy of Sciences, develop- problems, and are now test- mental endocrinologist Tyrone Hayes ing captured animals to de- and colleagues report that the widely termine whether the applied also can lower levels changes are due to atrazine. of the male hormone testosterone in The researchers are also try- sexually mature male frogs as much as responseto a new study by uc ing to determine how the tenfold, to levels lower than those in Berkeley scientist Tyrone Hayes, abnormalities affect the normal female frogs. above, the U.S. Environmental frogs’ ability to produce off- ”Atrazine-exposed frogs don’t Protection Agency may Wcon- spring. The National Sci- sider forthcoming rules on the have normal reproductive systems,” use of atrazine. ence Foundation is ~~ Hayes says. ”The males have ovaries supporting the studies. in their testes and much smaller vocal organs,” which are essential in calling potential mates. The vocal chords of more than 80% of male Oral exposure to hormones ”masculinizes“ frogs exposed to 1 part per billion (ppb) or more finches of atrazine were smaller than average; at concen- Female zebra finches that orally ingest the hor- trations of 0.1 ppb and higher, as many as 16% of mone estradiol benzoate as chicks develop ”mas- the frogs had extra gonads. culinized’’ brains and can sing if stimulated with Because it has been in use for 40 years in some testosterone as adults, UC Davis scientists have 80 countries, atrazine’s effect on sexual develop- found. ment in male frogs could be a factor contributing Scientists discovered several decades ago that to the global decline of amphibians, Hayes says. female finches exposed to estradiol - an estro- More than 60 million pounds of atrazine were ap- gen commonly used in hormone replacement plied last year in the . therapy - can sing like their male counter- The laboratory tests used the African clawed parts. Now UC scientists have found that frog (Xenopus laevis), which is very sensitive to giving doses of hormones to female finch chicks hormones that mimic its own sex hormones. If orally, a natural route of exposure to estrogenic raised in a pond with the female hormone estro- chemicals in the environment, can induce ”truly gen, for example, all Xenopus tadpoles turn into significant brain changes,” UC Davis animal sci- females. In the presence of male androgens such ence professor James Millam says. as testosterone, the frogs grow larger voice boxes. Exposure to estradiol benzoate also caused in- Abnormal gonads in a “Atrazine probably does not have such se- fertility in male finches and hindered the song- male Xenopus frog are the result of exposure to vere effects on humans, because it does not ac- birds’ ability to reproduce, according to studies the herbicide atrazine. cumulate in tissue and humans don’t spend The frog has become a their lives in water the way frogs do,” Hayes hermaphrodite, with says. Nevertheless, the effects of atrazine on both male (testes) and female (ovaries) sex frogs could be a sign that the herbicide is subtly organs. affecting human sex hormones. The U.S. Environmental Protection Agency is currently re-evaluating allowable levels of atra- zine in drinking water and the environment. Hayes found hermaphroditism in frogs at levels as low as 0.1 ppb, while draft regulations to pro- posed to estrogenic to estradiol benzoate;an tect aquatic life limit 4-day exposures to 12 ppb. chemicals as chicks,” , had a greater Levels as high as 40 ppb have been measured in Millam says. incidence of infertility and reduced reproductive ability. rain and spring water in parts of the Midwest, Hormones are while atrazine in agricultural runoff can be present powerful chemicals that regulate sexual develop- at several parts per million. ment and reproductive ability. Synthetic hor- Hayes and his colleagues subsequently visited mones are leaking into the environment and may

116 CALIFORNIA AGRICULTURE, VOLUME 56, NUMBER 4 be having important impacts on wildlife, Millam from the unfertilized says. For example, millions of women take estro- egg cell of one cow. gen in birth control pills and menopause treat- Then a cell is taken ments; estrogen is not broken down by water from somatic tissue of treatment and remains in sewage wastewater. a donor animal of the More relevant to birds is the presence of hormone same species and mimics in pesticides and industrial chemicals, placed next to the which can be ingested by developing chicks. ”empty” egg. In this The finches received a variety of estradiol case the donor cell doses, primarily at levels higher than those en- was a follicle, support- ive tissue in the cow’s Rosie weighed about 100 pounds at birth, a bit countered in the environment (except the most larger than the average 75 to 80 pounds usually polluted areas), although some reproductive im- ovary. seen in Hereford calves. Cloned calves are often pacts - such as increased egg breakage and male An electrical charge unusually large, but this calf is considered infertility - were identified at environmental lev- is applied, causing the within the normal range for her breed. els. The US. Environmental Protection Agency two cells to fuse together. The fused egg is placed in funded the research. a lab dish with the appropriate nutrients. Eventually the resulting embryo -which is a genetic copy of the animal that donated the nucleus - is trans- Cloned calf “Rosie“ is rosy planted into a surrogate mother. A cloned Hereford calf named Rosie is doing well after its birth at UC Davis on May 2. The reddish-brown and white female is part of Master Gardeners on page and screen an ongoing study aimed at better understanding Published earlier this year, ANRs California Master which types of adult cells are best suited for clon- Gardener Handbook is a runaway hit, quickly selling ing cows. The researchers hope to improve the out its first print run (an additional 10,000 more cop- cloning technique, eventually using it to produce ies have been delivered). “A new bible on the block more healthful meat and milk products. for home gardeners,” one garden ”We’re encouraged that Rosie is feeding well editor wrote. and acting energetic like any other newborn calf,” Now home gardeners have an- says Gary Anderson, professor and chair of the other opportunity to learn from UC UC Davis animal science department. However, Master Gardeners: UCTV will broad- because young calves are especially vulnerable to cast about 20 hours of the program’s respiratory, digestive and umbilical infections, sci- certification lectures this summer Master Gardener entists continue to watch her closely. and fall. Broadcasts begin the last The calf was cloned from a follicle cell taken week in July and will include classes ma.smnsn from the ovary of a 16-year-old, reddish-brown on integrated pest management, Hereford cow, and has the same coloring and weed identification, the home vine- markings as the cow from which she was cloned. yard and vertebrate pest control. This is the second calf cloned and delivered at UCTV is a systemwide channel with UC Davis. The first was born in August 2001 and programming from all UC campuses, died three days later due to multiple birth defects. labs and ANR; it can be found on Worldwide, an estimated 150 cloned calves have Dish Network Channel 9412 and ANR’s California Master been born at about 10 laboratories. various locations on cable. For infor- Gardener Handbook is ”a new bible” for home gardeners. The new calf is expected to remain at UC Davis mation, go to www.uctv.tv. for about 2 months, then go to a Northern Califor- The California Master Gardener Handbook (ANR nia ranch where the cow from which she was Publication 3382) is 702 pages, with black-and-white cloned lives. photos, line illustrations and a glossary of terms. It Cloning may someday enable scientists to pro- includes chapters on individual crop cultural prac- duce replicas of individual animals that have tices and, when applicable, nutrition of edible crops, valuable traits, such as cows whose milk is par- plus chapters on related disciplines such as soil and ticularly nutritious. Cloning could also be used to water management, weeds and insect pests, and genetically engineer cows and sheep that can pro- landscape plants and design. Copies cost $30, with duce pharmaceuticals in their milk. discounts for ANR personnel and Master Gardeners. The current technology used to produce clones To order, go to http://anrcatalog.ucdavis.edu/ or in the laboratory, called nuclear transfer, involves call 1-800-994-8849or (510) 642-2431. removing the nucleus (with its genetic material) - Compiled from UC and other news sources

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