Your privacy is important to us. Any information you provide to us via this website may be placed by us on servers located in countries outside of the EU.
If you do not agree to such placement, do not provide the information. To proceed, simply complete the form below, and a link to the article will be sent by email on your behalf. Note: Please don't include any URLs in your comments, as they will be removed upon submission. We do not store details you enter into this form.
- The X in Sex: How the X Chromosome Controls Our Lives.
- Fire and Polymers II. Materials and Tests for Hazard Prevention?
- Beyond Good and Evil.
- Critical Musicological Reflections: Essays in Honour of Derek B. Scott.
- Special Edition Using TCP IP, 2nd Edition.
- The Truth About the Music Business: A Grassroots Business and Legal Guide (Book).
- Confronting Corruption, Building Accountability: Lessons from the World of International Development Advising.
X Chromosome Fact Sheet
The sex chromosomes - X and Y - determine whether an embryo becomes male or female. The mother contributes an X chromosome to the child, and it is the chromosome from the father - which can be an X or a Y - that determines whether the child is a girl or a boy.
In each human cell, men have one X chromosome and one Y chromosome, while women have two X chromosomes. Taru Tukiainen. We nevertheless wanted to take up the challenge since we had a strong belief that opening 'the X files' for research would reveal new, interesting biological insights," she adds. Tukiainen and colleagues found that a genetic variant with a role in cartridge development is more common among people who are shorter than average.
The researchers also found that the effect of this gene was much stronger in women. But why was this gene - which is associated with a gene called "ITM2A" - more powerful in women? Here's where the X chromosome comes in. ITM2A is a chromosome X gene.
- Commerce in Space: Infrastructures, Technologies and Applications (Premier Reference Source)?
- The X chromosome is necessary for ovule production in Silene latifolia.
- The X in Sex: How the X Chromosome Controls Our Lives.
- CallRail API v1 Documentation?
- Sex differences in lifespan: X chromosome not the reason -- ScienceDaily?
- Programming 16-Bit PIC Microcontrollers in C - Learning to Fly the PIC24?
Normally, one of the X chromosomes in female cells is randomly and permanently inactivated - except in egg cells. This means that two copies of the gene could remain active in each cell in women - unlike men, who, with just one X chromosome, would only have one copy of the gene per cell.
Browse more videos
Because both copies of ITM2A remain active, the gene is expressed in higher levels in women. Identifying associations in regions like this where X-chromosomal gene doses are not balanced between men and women can be particularly valuable in helping us to understand why some characteristics differ between sexes. Because the X chromosome is such an important source of DNA, the researchers hope that their work, which is published in the journal PLOS Genetics , provides motivation for future researchers to further examine this chromosome and how it influences other biological differences between men and women.
They think that such research will give scientists a better understanding of why some diseases are more prevalent in one sex than the other. Last year, Medical News Today reported on a study that found the female version of the X chromosome has evolved to play a role in sperm production. Additional source: Genetics Home Reference , accessed on 7 February Additional source: MedlinePlus , accessed on 7 February Visit our Genetics category page for the latest news on this subject, or sign up to our newsletter to receive the latest updates on Genetics.
X chromosome is key. In many species, including humans, females have two X chromosomes while males have an X and a Y chromosome. In birds, and in some species of fish, reptiles and insects, males have two copies of the same sex chromosome, and in such cases it is most often males who have the longer lifespan. The sex that has two X chromosomes has two variants of each gene on the X chromosome. The gene variants act as back-ups for each other, so if a gene on the X chromosome is not functional, the gene copy on the other chromosome can compensate for this.
In the sex that has two different sex chromosomes one X and one Y , in contrast, only one copy of most genes on the X chromosome is present, and no back-up is available if there is something wrong with them. The theory suggests that this mechanism contributes to making the average lifespan of males shorter. It is an old theory, but only a few studies have been carried out to test it. The researchers who carried out the new study used fruit flies Drosophila melanogaster to test the theory. If the theory is true, the effects should be clear in the fruit fly," says Martin Brengdahl, PhD student at the Department of Physics, Chemistry and Biology at LiU, and one of the principal authors of the study.
The researchers bred fruit flies in which the two X chromosomes in the females were identical, such that neither of the copies was able to compensate for faults in the other. The flies in a second group were instead given two identical copies of one of the other chromosomes not the sex chromosomes , known as "autosomal chromosomes.
X Chromosome Fact Sheet | NHGRI
Inbreeding of one autosomal chromosome, on the other hand, did have a negative effect and the effects were equally large in females and males," says Martin Brengdahl. The results suggest that having an unguarded X chromosome cannot explain the difference in lifespan between the sexes.
At least, not in fruit flies. We have investigated the validity of the issue in one model, and further research can build on these results in the future," says Urban Friberg, senior lecturer at the Department of Physics, Chemistry and Biology, who has led the study. The research group is now continuing to examine why there is a difference in lifespan between the sexes, and will be taking a close look at one of the alternative theories.
In many species, competition between males to mate with females is intense. The theory of sexual selection suggests that this may compel the males to use more energy in finding partners and less in maintaining bodily functions, which leads to a shorter lifespan.
Note: Content may be edited for style and length. Science News. Sex differences in life span: Females homozygous for the X chromosome do not suffer the shorter life span predicted by the unguarded X hypothesis.