Tag: Evolution + Development

Men are not in Driver's Seat of Human Evolution

August 9, 2000

For more than half a century, the field of human genetics has harbored a gender bias about the relative contribution of males versus females to human evolution. Since 1947, when biologist J.B.S Haldane suggested that the rate of genetic mutation is much higher in the male germ line than in the female germ line, geneticists have credited males with much of the evolutionary changes that occurred in the 5 million years since human ancestors departed from chimpanzees.

Tracing the Evolution of Sex Chromosomes

October 29, 1999

Of the 46 human chromosomes, 44 are members of identical pairs. But two—the X and the Y—stand apart because they have no perfect match. Nevertheless, evolution has charged these two genetic loners with the critical task of sex determination: embryos with two X chromosomes develop into females, while embryos with an X and a Y chromosome develop into males.

Transmitting Infertility from Father to Son

July 1, 1999

Genetic studies at the Whitehead Institute for Biomedical Research have shown that some boys will be infertile as adults because they have inherited a genetic defect from their fathers through a commonly used method of assisted reproduction known as intracytoplasmic sperm injection (ICSI).

New Gene May Help Scientists Understand More About How the Body Grows

April 3, 1999

Scientists at the Whitehead Institute for Biomedical Research and Genetics Institute, Inc. have identified a new gene called derriere that plays a key role in the development of the frog embryo from the neck down, including the neural tube and the muscles flanking the spinal cord. Embryos lacking derriere gene function developed normal heads but only had disorganized tissue where the trunk and tail should have been. Scientists conclude that derriere controls the formation of the posterior regions of the embryo-that is, the entire body from the neck down.

Whitehead Study Supports Existence of Ancient RNA World

September 16, 1998

For decades, many researchers thought that ribonucleic acid, or RNA, was nothing more than a molecular interpreter that helps translate DNA codes into proteins. But research over the past 15 years, including studies at the Whitehead Institute, has been lending credence to the notion of a so-called “RNA world,” an era in early evolution when all life forms were based on RNA.

Study Paints New Picture Of Y Chromosome as a Safe Haven for Male Fertility Genes

October 24, 1997

For decades scientists thought that the human Y chromosome, the male sex chromosome, was nothing more than a smaller, less stable version of its partner, the X (the sex chromosome present in both females and males). However, new research led by Dr. David Page, member of the Whitehead Institute for Biomedical Research, and associate investigator of the Howard Hughes Medical Institute, reverses this unflattering picture of the Y and reveals it as a crucial player in the evolution of sex chromosomes and also as a safe haven for male fertility genes. These results are not only generating a new respect for the Y chromosome but also could lead to novel diagnostic techniques for thousands of infertile men. The results also have profound implications for understanding the genetic differences between men and women and the genetic underpinnings of chromosomal disorders such as Turner syndrome.

New respect for the Y chromosome: sheltering genes that enhance male fertility

October 31, 1996

For decades the human Y chromosome, the male sex chromosome, has been the Rodney Dangerfield of human genetics: "it don't get no respect." For long, the Y was considered to be little more than a smaller, less stable version of the X. Now, new evidence from Dr. Page and his collaborators at the Whitehead Institute, the Massachusetts Institute of Technology, and the University of Washington reveals that the Y chromosome has led an independent existence after all.

Novel Assay Provides Researchers a Key Tool to Study Nervous System Development

June 6, 1996

For the first time, scientists have isolated embryonic tissue from zebrafish and successfully grown the tissue in culture. This assay will offer scientists a long-sought and powerful research tool, allowing them to study early development in ways that are not possible with other model organisms like frogs, mice, or chicks. Using this culture, the scientists also found key genes involved in the formation of the zebrafish nervous system.

Genetic Factors Cause Low Sperm Counts in Some Otherwise Healthy Males

May 11, 1996

Scientists have found that a specific defect in the male sex (Y) chromosome, known to cause azoospermia, or the inability to make sperm, can also cause the most common form of male infertility-low sperm production, or oligozoospermia. This study is the first to definitively show that genetic defects can cause low sperm counts in some males and suggests that intracytoplasmic sperm injection (ICSI)—the now popular technology of injecting a single sperm into an egg to circumvent low sperm counts—may cause the sons of these men to inherit infertility.

Glue-Like Protein Provides New Key to Understanding Common Birth Defects

October 20, 1995

Scientists at the Whitehead Institute for Biomedical Research have discovered a glue-like protein in fruit flies that ensures proper partitioning of hereditary material and could shed new light on the origin of some of the most common human birth defects, including Down syndrome. Dr. Terry Orr-Weaver and her colleagues describe the new protein, called MEI-S332, and its role in sexual reproduction in the October 20 issue of Cell.

Genetic Factors May Account for Infertility in Otherwise Healthy Males

August 1, 1995

A team of U.S. and Finnish scientists has found that a specific defect in the male sex chromosome (the Y chromosome) may be responsible for 13 percent of cases of azoospermia, the complete inability to make sperm and the most severe form of male infertility. The study is one of the first to demonstrate that genetic defects can sometimes explain infertility in otherwise healthy couples and could lead to a better understanding of the molecular mechanisms required to make healthy sperm. This research, reported in the August issue of Nature Genetics, was led by Dr. David Page of the Whitehead Institute for Biomedical Research and the Howard Hughes Medical Institute (HHMI).

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