setting a stage for cancer: another reason for women not to drink while pregnant

S C I E N C E N E W S

Initial trials indicated that Rico treats cer-tain spoken words as names for specific itemsrather than using nonverbal cues, such as aspeaker’s shrugs or gaze direction, to deter-mine a word’s meaning. The scientists ran-domly assigned to 20 sets the 200 itemsRico’s owners claim that the dog knows.While one of his owners waited with Rico inanother room, an experimenter arranged the10 items of one set in an adjoining room. Hethen told the owner to instruct the dog witha single verbal command to fetch a specificitem.

Forced to search where he couldn’t seeanyone, the dog in four tests retrieved 37 of40 objects correctly.

An experimenter then placed a toy thatRico had never seen before with sevenfamiliar ones in the adjacent room. Rico’sowner instructed him to fetch the item,using a name the dog hadn’t previouslyheard. In 7 of 10 trials, Rico returned withthe new item. The researchers propose that

the dog matched the unfamiliar word to anovel object through a process of elimina-tion.

One month later, Rico correctly retrievedthree items during six tests, each test usingone of these new words. That’s a good score,given that it was only the second time thedog had heard each word, Fisher says.

Rico’s interpretive skill partly stems fromthe breeding of border collies for mentalagility. Also, 9-year-old Rico has beentrained by his owners to retrieve toys bytheir names since he was 9 months old.

Still, it’s not yet clear whether Rico real-izes that words refer to categories ofobjects, as even 1-year-old children do,remarks Yale University psychologist PaulBloom in a comment published with thenew report. —B. BOWER

Genetic PickupDid animals get braingenes from bacteria?

Reviving a controversy about whether ani-mals have acquired key genes from bacte-ria, a study suggests that microbes have pro-vided genes that now play vital roles in

brain-cell signaling and other forms of cell-to-cell communication. The genes impli-cated encode enzymes required for themetabolism and synthesis of crucial brainchemicals, including dopamine, serotonin,melatonin, and histamine.

“These enzymes did not evolve [in ani-mals]. They were picked up, as a shortcut,”contends David C. Klein of the NationalInstitute of Child Health and HumanDevelopment in Bethesda, Md.

Klein’s collaborators on the study, how-ever, made a similar claim several years agoabout the transfer of bacterial genes intohuman DNA. That assertion was stronglyrefuted, and the new work has quicklydrawn pointed remarks from some of thesame critics.

“I think the claims that they are makingare scientifically questionable. I think it’sactually somewhat irresponsible of them tokeep publishing these papers without show-ing more skepticism,” says Steven L.Salzberg of the Institute for GenomicResearch in Rockville, Md.

The fiery debate centers on what all thescientists agree is a provocative notion,namely, that some genes didn’t arise grad-ually through evolution but were picked upwhole by early animals from the DNA ofmicrobes. This possibility has gained inter-

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SCIENCENEWSThis Week

Imbibing substantial amountsof alcohol during pregnancycan cause fetal alcohol syn-

drome, a condition characterizedby birth defects ranging fromabnormal facial features tosevere neurological defects.New studies with rats indicatethat a previously unrecognizedrisk to the fetus, cancer later inlife, might come from even mod-est in utero exposure to alcohol.

Leena Hilakivi-Clarke ofGeorgetown University inWashington, D.C., fed alcoholto 30 pregnant rats each dayduring their latter twotrimesters. Half consumedsmall amounts, such that 7percent of their daily caloriescame from the alcohol. Theother half consumed twice thatquantity of alcohol. “These[amounts] are similar to thoseseen in low-to-modest alcoholdrinkers . . . and lower thanthose found to induce fetalalcohol syndrome,” says Clarke

in the June British Journal ofCancer. A third group of ratsreceived no alcohol.

Three weeks after birth, thefemale rats exposed to alcoholin utero had significantly moreterminal end buds—a type ofbreast tissue that can laterform tumors—than did the ratsthat had not been exposed toalcohol, Clarke found.

Once the rats enteredpuberty, Clarke injected themwith a cancer-causing chemi-cal. Almost all the animalsdeveloped mammary tumors,but those whose mothersimbibed the most alcoholdeveloped twice as manytumors as those whose moth-ers consumed no alcohol. Thegroup exposed to the low doseof alcohol showed an interme-diate number of tumors.

How alcohol might set thestage for cancer is not clear.Clarke speculates that alcoholaccelerates the natural conver-

sion of testosterone to estro-gen in the womb. “Estrogensomehow programs the [breasttissue] so that, later on, it turnsout to be more dense,” saysClarke. Researchers havelinked dense breast tissue inwomen to increased risk ofbreast cancer.

Most of the risk factors asso-ciated with breast cancer,including tissue density, birthweight, and the age at whichmenstruation begins, are onesthat women can’t easily control.And most choices about adultexercise and diet appear to beunrelated to breast cancer, saysKarin Michels of Harvard Med-ical School in Boston. However,she notes, a woman’s alcoholconsumption slightly increasesher breast cancer risk.

Michels and a growing num-ber of breast cancer research-ers are now focusing on thelifestyles of women from ado-lescence to just before meno-

pause. With studies of fetalrats, Michels notes, Clarke is“looking even earlier in life.”

The new study doesn’testablish a link between awoman’s alcohol consumptionduring pregnancy and breastcancer in her adult daughter,says Clarke, but the resultsought to serve as a warning.

This isn’t the first suggestionthat fetal conditions can affecta person’s health decades later.For example, many researchershave noted links between lowbirth weight and adult heartdisease, stroke, osteoporosis,and diabetes.

For most pregnant women,one drink a month is not likelyto affect their sons or daughtersin later life, Clarke says. But con-sidering the severity of prob-lems already pegged to alcoholand the variation in responsesto it, she adds, “there’s no safelevel” of consumption duringpregnancy. —C. LOCK

Setting a Stage for Cancer Another reason for women not to drink while pregnant

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