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Tag: "sperm" at biology news

Study hints at role of stem cell genes in testicular, breast cancers

...cells, which are located in the testis and produce sperm in boys following puberty. Germ cells, like all cells of the body, develop from embryonic stem cells, and go through a multi-stage evolution in their structure and genetic activity before attaining their mature state. The study revealed that the gene...

Scientists unpick genetics of first 15 minutes of life

...erones' the early processes that take place once a sperm enters an egg, giving it a crucial role in the mos...he DNA from the mother's egg cell and the father's sperm cell meet for the first time," said Dr Tim Karr from the University of Bath (UK) who worked closely ...

Research suggests fitness of Florida panthers improved by limited breeding with Texas animals

...r an array of genetic abnormalities, including low sperm counts and heart defects. "It turns out that purebred kittens don't survive very well," he said. "They die in very high numbers. Once you get new blood, those defects disappear from the population. Hybrids are better than inbred animals." The paper ...

Elderly mice yield clues to the process of growing old

..., and loss of male germ cells that lead to reduced sperm production and infertility. Intriguingly, the mice develop symptoms of old age, notably gray hair and hair loss, more commonly seen in humans than mice. Prolla suggests that new studies of mice engineered to have fewer than normal mitochondrial DNA...

Orientation and the egg

...are in contrast to those who feel that the site of sperm entry determines the orientation of the future body axes. "It would now make sense to base our future experiments on the premise that the mammalian egg neither has nor requires predetermination for successful development," explains Dr. Hiiragi. ...

Multi-species genome comparison sheds new light on evolutionary processes, cancer mutations

...rms of evolution. When chromosomes break in egg or sperm cells, opportunities arise for the rearrangement of DNA in the resulting offspring. Such inheritable rearrangements may be lethal or cause disease. However, in some cases, the breaks may lead to the production of new or altered proteins with potentia...

Human embryonic stem cells have the potential to develop into eggs and sperm in the laboratory

... Their work opens up the possibility that eggs and sperm could be grown from stem cells and used for assist... the ancestral cells that eventually form eggs and sperm (gametes). "Investigating the mechanisms of human primordial germ cell and gamete development is imp...

Can our genes tell the story of our divergence?

...e, that there is a battle between the interests of sperm cells (favoring genetic changes that increase cell number and decrease cell death), and the need for the organism to avoid cancer. Future studies will have to determine whether these explanations - of an evolutionary arms race - prove plausible. We'...

Tufts researchers shine light on firefly mysteries

...heir reproductive glands. These chemicals kill the sperm of other males that have mated with the same female but they are also toxic to the female -- hence conflict." In a collaborative research effort with insect physiologist and Tufts postdoctoral research fellow Dr. William Woods, Lewis is also examini...

Decisions, decisions: Male or female?

How germ cells decide whether to be sperm or eggs Johns Hopkins biologists have determined ...ized "germ cells" whether to develop into a male's sperm or a female's eggs. Present in both male and female embryos, germ cells are the precursors to both ...

Environmental chemical cocktail may sabotage sperm

...od have subtle but potentially damaging effects on sperm fertility. Professor Lynn Fraser told the 21st an...legumes), on human sperm, she found that the human sperm were much more sensitive to it than mouse sperm. Even tiny doses could cause human sperm to "burn ou...

Invitrogen Launches i-Path -- A Unique Systems Biology Platform at BIO 2005

...loned embryos and develop them to provide eggs and sperm for infertile couples, the 21st annual conference ...homologous [matching] chromosomes, instead of from sperm and eggs which carry only one set of chromosomes each." Five oocytes divided to the two-cell stage,...

Scientists succeed in cloning human embryos from eggs matured in the lab

...loned embryos and develop them to provide eggs and sperm for infertile couples, the 21st annual conference ...homologous [matching] chromosomes, instead of from sperm and eggs which carry only one set of chromosomes each." Five oocytes divided to the two-cell stage,...

Scripps research scientists identify infertility molecule

...perm, and a woman has to produce healthy eggs. The sperm has to be able to travel up the fallopian tubes to...lity. A man might not produce enough sperm, or his sperm might be unable to reach the eggs. A woman might have problems producing eggs or her fallopian tubes...

IMF Launches World’s First DNA Database for Myeloma Patients

...results from post-mating sexual selection, such as sperm competition or cryptic female choice. That is, most evolutionists have believed that for animals with internal fertilization -- like the livebearing fish Langerhans studies which don't lay eggs-- selection acting within the female's body that biases ...

Certain fish have a special mating preference

...results from post-mating sexual selection, such as sperm competition or cryptic female choice. That is, most evolutionists have believed that for animals with internal fertilization -- like the livebearing fish Langerhans studies which don't lay eggs-- selection acting within the female's body that biases ...

Mother birds increase progesterone to hatch females

In mammals, sperm from the male determines the sex of the offspring. In birds, however, it is the female's sex chromosome that determines offspring sex. Now, Cornell University researchers think they understand the mechanism that several bird species use to bias the s...

Retrovirus struck ancestors of chimpanzees and gorillas millions of years ago, but did not affect ancestral humans

...virus had invaded the genome in the germline -- in sperm or egg cells -- allowing the sequence to be passed on to future generations. In those animals in which the virus was taken up next to or inside a gene -- in the part of the genome that codes for the most important biological functions -- the virus ha...

Of mice and men's (and women's) contraceptives

...ers to the group of cells that give rise to either sperm or eggs in animals, as opposed to all other cell t...proteins are critical for the production of normal sperm and also are unique to germ cells. "When trying to develop a new contraceptive, it's hard because w...

To sea or not to sea: When it comes to salmon sex, size sometimes doesn't matter

...r" as the full-size males that are releasing their sperm in a competitive frenzy as the female deposits her eggs. And the tiny male has avoided the harrowing journey taken by most salmon to the ocean and back, bypassing hazards such as dams, sharks and fishermen. "In some species, all or a fraction of th...

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