Featured Research

from universities, journals, and other organizations

Survival of the females: Horse embryo study provides important new information

Date:
December 18, 2012
Source:
University of Veterinary Medicine -- Vienna
Summary:
It is well known that many mammals are able to adjust the ratio of male and female young depending on the surrounding conditions at the time of conception. A recent study provides important information on how the survival of female embryos may be enhanced under conditions that would otherwise favor the birth of males.

It is well known that many mammals are able to adjust the ratio of male and female young depending on the surrounding conditions at the time of conception but how precisely this is accomplished remains a matter for debate. A recent study in the group of Christine Aurich at the University of Veterinary Medicine, Vienna has provided important information on how the survival of female embryos may be enhanced under conditions that would otherwise tend to favour the birth of males.

The work is published in the journal Theriogenology.

Because of the process involved in the formation of sperm cells, there should be an equal chance that a mammalian egg will be fertilized by "male" sperm, carrying a Y chromosome, as by a "female" sperm, carrying an X chromosome. The symmetry of the system ensures that roughly the same number of males and females are born, which is clearly helpful for the species' long-term survival. Surprisingly, though, many mammals do not produce equal numbers of male and female offspring.

The discrepancy could theoretically be explained by differential fertilization efficiencies of male and female sperm (Y chromosomes are smaller than X chromosomes so perhaps male sperm can swim faster?) or by different rates of survival of male and female foetuses in the uterus. Indeed, it does seem as though male embryos are better able to survive under conditions of high energy intake. But how does this work?

Jana Beckelmann in Christine Aurich's laboratory at the University of Veterinary Medicine, Vienna now presents provocative evidence that a particular protein, insulin-like growth factor-1 or IGF1, might somehow be involved. From an examination of about 30 embryos, Beckelmann noticed that during early pregnancy (between eight and twelve days after fertilization) the level of messenger RNA encoding IGF1 was approximately twice as high in female embryos as in male embryos.

The difference could relate to the fact that female embryos have two X chromosomes, which might produce more of a factor required for the expression of the IGF1 gene (which is not encoded on the X chromosome) than the single X chromosome in males is able to generate. Beckelmann was also able to confirm that the IGF1 protein was present in the embryos, confirming that the messenger RNA is actually translated to protein.

IGF1 is known to have important functions in growth and to inhibit apoptosis, or programmed cell death. As IGF1 treatment of cattle embryos produced in vivo improves their survival, it is likely that the factor has positive effects on the development of the early embryo in the horse. So why should female embryos contain more of the factor than males?

Losses in early pregnancy are unusually high in the horse and it is believed that female embryos are especially prone to spontaneous abortion. Male embryos are known to be better able to survive under high glucose concentrations, so well-nourished mares preferentially give birth to male foals.

As Beckelmann says, "We think the higher IGF1 concentrations in female embryos might represent a mechanism to ensure the survival of the embryos under conditions that would otherwise strongly favour males." If this is so, the ratio of the sexes in horses is the result of a subtle interplay between environmental and internal factors, including insulin-like growth factor-1.

The paper "Sex-dependent insulin like growth factor-1 expression in preattachment equine embryos" by Jana Beckelmann, Sven Budik, Magdalena Helmreich, Franziska Palm, Ingrid Walter and Christine Aurich in the journal "Theriogenology" is available online and will appear in print in the issue of January 1, 2013 (Volume 79, Issue 1, 1 January 2013, pp. 193-199)."


Story Source:

The above story is based on materials provided by University of Veterinary Medicine -- Vienna. Note: Materials may be edited for content and length.


Journal Reference:

  1. J. Beckelmann, S. Budik, M. Helmreich, F. Palm, I. Walter, C. Aurich. Sex-dependent insulin like growth factor-1 expression in preattachment equine embryos. Theriogenology, 2013; 79 (1): 193 DOI: 10.1016/j.theriogenology.2012.10.004

Cite This Page:

University of Veterinary Medicine -- Vienna. "Survival of the females: Horse embryo study provides important new information." ScienceDaily. ScienceDaily, 18 December 2012. <www.sciencedaily.com/releases/2012/12/121218112015.htm>.
University of Veterinary Medicine -- Vienna. (2012, December 18). Survival of the females: Horse embryo study provides important new information. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2012/12/121218112015.htm
University of Veterinary Medicine -- Vienna. "Survival of the females: Horse embryo study provides important new information." ScienceDaily. www.sciencedaily.com/releases/2012/12/121218112015.htm (accessed April 18, 2014).

Share This



More Plants & Animals News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Vermont Goat Meat Gives Refugees Taste of Home

Vermont Goat Meat Gives Refugees Taste of Home

AP (Apr. 18, 2014) Dairy farmers and ethnic groups in Vermont are both benefiting from a unique collaborative effort that's feeding a growing need for fresh and affordable goat meat. (April 18) Video provided by AP
Powered by NewsLook.com
The Great British Farmland Boom

The Great British Farmland Boom

Reuters - Business Video Online (Apr. 17, 2014) Britain's troubled Co-operative Group is preparing to cash in on nearly 18,000 acres of farmland in one of the biggest UK land sales in decades. As Ivor Bennett reports, the market timing couldn't be better, with farmland prices soaring over 270 percent in the last 10 years. Video provided by Reuters
Powered by NewsLook.com
Flamingo Frenzy Ahead of Zoo Construction

Flamingo Frenzy Ahead of Zoo Construction

AP (Apr. 17, 2014) With plenty of honking, flapping, and fluttering, more than three dozen Caribbean flamingos at Zoo Miami were rounded up today as the iconic exhibit was closed for renovations. (April 17) Video provided by AP
Powered by NewsLook.com
Change of Diet Helps Crocodile Business

Change of Diet Helps Crocodile Business

Reuters - Business Video Online (Apr. 16, 2014) Crocodile farming has been a challenge in Zimbabwe in recent years do the economic collapse and the financial crisis. But as Ciara Sutton reports one of Europe's biggest suppliers of skins to the luxury market has come up with an unusual survival strategy - vegetarian food. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins