all reproductive biology stories

Mode of seed dispersal shapes placement of rainforest trees

Thu, 12 Jul 2007 09:21:43 -0400

The apple might not fall far from the tree, but new research shows that how it falls might be what is most important in determining tree distribution across a forest. A recent study of the seed dispersal methods of rainforest trees demonstrates that these methods play a primary role in the organization of plant species in tropical forests.

Joshua B. Plotkin, a junior fellow in the Faculty of Arts and Sciences at Harvard University, and co-author Tristram Seidler published the results of their study on seed dispersal methods in the journal Public Library of Science - Biology (PLoS Biology).

Spar takes on boom in baby biz

70652986 — Mon, 26 Mar 2007 06:25:22 -0400

The field of reproductive technologies has become a fast- growing and profitable economic sector. "Parents choose for different traits, clinics woo clients, and specialized providers earn millions of dollars," points out Harvard Business School Professor Debora Spar in her book, "The Baby Business: How Money, Science and Politics Drive the Commerce of Conception."

Some parents pay up to $100,000 to produce what others make for free. Spar doesn't judge if this market is either good or evil, but with her research hopes to start a public debate about the need to establish governmental oversight.

The baby industry, Spar notes, expanded beneath the radar of most business analysts. This is, she says, partly because clients generally recoil from the notion that their families are - at least in part - the result of "market activity." In addition, there has been little call for governmental regulation of this new and unique business.

The development of the baby industry took off, says Spar, in 1978 with the birth of Louise Brown, the first test-tube baby. Today desperate couples go through round after round of in vitro fertilization (IVF) at an average cost of $12,400 per try, even though the success rate hovers around 27 percent and drops as low as 9 percent if the woman is over 40. Those who do give up can turn to adoption, along with about 120,000 other U.S. families each year, paying out up to $35,000 per child.

Sexual attraction a matter of scent

70652986 — Mon, 26 Mar 2007 05:42:13 -0400

An unexpected finding may settle an ongoing scientific debate by providing evidence that key reproductive behaviors in mice arise predominantly, if not exclusively, from olfactory input instead of input from the vomeronasal, visual, or auditory senses.

The results, from a team led by Harvard biologist Catherine Dulac, appear on the Web site of the journal Cell and were published in the journal's Nov. 18, 2005 issue.

"It's always interesting when there is a surprise finding," says Dulac, professor of molecular and cellular biology in Harvard's Faculty of Arts and Sciences and an investigator with the Howard Hughes Medical Institute. "Most biology textbooks now say that pheromones affecting reproductive behavior in nonhuman mammals are detected by the vomeronasal organ, while the nose processes all other odors. Our work suggests quite convincingly that the mouse nose processes both pheromones and other scents, and in fact provides much or all of the chemosensory input that drives mating."

In addition to funding from the Howard Hughes Medical Institute, the research was supported by the National Institutes of Health.

Harvard, MGH researchers track egg cell production to marrow

50443248 — Fri, 20 Jul 2007 15:51:26 -0400

Harvard researchers have found new evidence that female mammals can produce egg cells throughout life and have traced their production out of the ovary and into the bone marrow in findings that could both reshape science's understanding of female reproduction and provide new avenues for treatment of infertility.
In a series of experiments on sterile female mice, researchers from Massachusetts General Hospital (MGH), a Harvard teaching hospital, were able to restore egg production by transplanting bone marrow from fertile mice. The researchers believe that egg stem cells in the donor bone marrow established themselves in the sterile mice and began producing egg cells, also called oocytes.

Sperm cells made in lab can fertilize eggs

70652986 — Mon, 26 Mar 2007 05:33:28 -0400

Scientists injected laboratory-created sperm into eggs, and the resulting embryos grew to the point where they would normally be implanted into a womb. The experiment was done with mouse stem cells, but mice, genetically speaking, are so close to men, few scientists doubt that the same experiment can be done in humans. The breakthrough, made by researchers at the Whitehead Institute for Biomedical Research and Harvard University, was reported in the Dec. 11, 2003 issue of the journal Nature. "This is the first time that sperm cells made in a petri dish from embryonic stem cells have resulted in the creation of an embryo," says George Daley, a Harvard Medical School biologist who led the experiments. (Egg cells were developed from mouse embryonic stem cells earlier this year by another group of scientists.) "Such experiments are being done solely for the purpose of studying how genes regulate the transformation of stem cells into germ cells, one of the basic mysteries of life." However, Daley quickly admits that this work has implications for genetically modifying animals, for treating human infertility, and, perhaps, for other medical purposes.

Genetic sonograms may reduce need for amniocentesis

70652986 — Mon, 26 Mar 2007 05:24:41 -0400

Radiologist Beryl Benacerraf is a Harvard Medical School clinical professor of obstetrics, gynecology and reproductive biology at Brigham and Women's Hospital. Benacerraf, a handful of like-minded maternal-fetal ultrasound specialists, and a growing number of older pregnant women believe in clarifying the risk of a genetic abnormality in a fetus by adding a detailed ultrasound known as a genetic sonogram. In skilled hands, the method may pick up about 80 percent of Down syndrome fetuses while reducing the risk for most high-risk women. Benacerraf says "there has to be a better way" than the amniocentesis test routinely used for pregnant women 35 and older.

Pigment plays role in Xenopus development

70652986 — Mon, 26 Mar 2007 05:18:51 -0400

Harvard Medical School researchers have discovered that a pigment contained in the egg of the South African claw-toed frog is indispensable for development. Witout the pigment, called biliverdin, which is present in yolk platelets, the egg cannot go through dorsal axis formation. In its absence, Xenopus laevis embryos develop into headless, eyeless, spineless lumps of tissue. "For many decades, biliverdin has been considered to have no biological significance or function," said principal investigator Kenneth Falchuk, Harvard Medical School associate professor of medicine at Brigham and Women's Hospital. "There's going to be a lot of interest now to identify what biliverdin's functions are." A study by Falchuk's research team was published in the Jan.

New technique could repair severe birth defects

70652986 — Mon, 26 Mar 2007 05:18:33 -0400

Physicians used to think that the amniotic fluid that cushions a fetus in the womb was junk, a kind of garbage bag into which the fetus urinates and sheds old cells. But recently two Harvard researchers took another look at amniotic cells and discovered that they could be used to grow new tissue. "We thought these cells were at the end of their life cycle, and were shed like adults shed old skin cells," says Dario Fauza, an instructor in surgery who works at Children's Hospital in Boston. "But last year we were surprised to find that these fetal cells are viable cells that grow quickly." Generating new tissue from the old amniotic cells is a promising technique to help repair severe birth defects.

Examining differing reproductive desires in Gambia

70652986 — Mon, 26 Mar 2007 05:06:39 -0400

For men in rural Gambia, more than 15 kids are desirable. That's double the number of children that women are actually delivering. The number may seem high to people in the West, but in rural Gambia fertility for both men and women represents more than simple family size. Allan Hill, a researcher at the Harvard School of Public Health, addressed questions about what happens when men and women want different numbers of children in "Separate Lives, Different Interests: Male and Female Reproduction in the Gambia," a paper published in the Bulletin of the World Health Organization. Hill has been overseeing a research program on the fertility and reproductive health of people in rural Gambia for several years.