Navigation Links
Male or female?
Date:4/23/2014

This news release is available in French and German.

Man or woman? Male or female? In humans and other mammals, the difference between sexes depends on one single element of the genome: the Y chromosome. It is present only in males, where the two sexual chromosomes are X and Y, whereas women have two X chromosomes. Thus, the Y is ultimately responsible for all the morphological and physiological differences between males and females.

But this has not always been the case. A very long time ago, the X and Y were identical, until the Y started to differentiate from the X in males. It then progressively shrank to such an extent that, nowadays, it only contains about 20 genes (the X carries more than one thousand genes). When did the Y originate and which genes have been kept? The answer has just been brought to light by the team of Henrik Kaessmann, Associate Professor at the CIG (UNIL) and group leader at the SIB Swiss Institute of Bioinformatics, and their collaborators in Australia. They have established that the first sex genes appeared concomitantly in mammals around 180 million years ago.

4,3 billion genetic sequences

By studying samples from several male tissues in particular testicles from different species, the researchers recovered the Y chromosome genes from the three major mammalian lineages: placentals (which include humans, apes, rodents and elephants), marsupials (such as opossums and kangaroos) and monotremes (egg-laying mammals, such as the platypus and the echidna, a kind of Australian porcupine). In total, the researchers worked with samples from 15 different mammals, representing these three lineages, as well as the chicken, which they included for comparison.

Instead of sequencing all Y chromosomes, which would have been a colossal task according to Diego Cortez, researcher at CIG and SIB and main author of the study, the scientists opted for a shortcut . By comparing genetic sequences from male and female tissues, they eliminated all sequences common to both sexes in order to keep only those sequences corresponding to the Y chromosome. By doing so, they established the largest gene atlas of this male chromosome to date.

This study required more than 29,500 computing hours! A gigantic task, which could not have been performed without important technical means: the high-throughput DNA sequencers of the genomics platform at the Center for Integrative Genomics, for the generation of the genetic sequences, and the calculation means of Vital-IT, SIB's high-performance computing centre, for the biological analyses.

Two independent sex-determining genes

The study shows that the same sex-determining gene, named SRY, in placentals and marsupials had formed in the common ancestor of both lineages around 180 million years ago. Another gene, AMHY, is responsible for the emergence of Y chromosomes in monotremes and appeared some 175 million years ago. Both genes, which according to Henrik Kaessmann are involved in testicular development , have thus emerged nearly at the same time but in a totally independent way .

The nature of the sex-determination system present in the common ancestor of all mammals remains unclear, given that mammalian Y chromosomes did not yet exist at that time - at least not those discovered in this study. So what triggered back then that an individual was born male or female? Was this determination linked to other sex chromosomes, or even environmental factors such as the temperature? The latter is not an unreasonable scenario, given that temperature determines sex in present-day crocodiles. As far as mammals are concerned, the question remains open , concludes Diego Cortez.


'/>"/>

Contact: Irene Perovsek
irene.perovsek@isb-sib.ch
41-216-924-054
Swiss Institute of Bioinformatics
Source:Eurekalert

Post Your Comments:
*Name:
*Comment:
*Email:
(Date:12/7/2016)... Dec. 7, 2016   Veridium , a ... appointment of new CEO James Stickland . ... decades of experience, has served in senior executive ... he specialized in expanding a pipeline of venture ... He most recently served as managing director of ...
(Date:12/6/2016)... Securus Technologies, a leading provider of ... safety, investigation, corrections and monitoring, and the Prison ... (5) year funding commitment by Securus to PEP ... and reentry support to more inmates and their ... the Prison Entrepreneurship Program (PEP) is an independent ...
(Date:12/2/2016)...   SoftServe , a global digital technology ... electrocardiogram (ECG) biosensor analysis system for continuous driver ... The smart system ensures device-to-device communication between ECG ... mobile devices to easily ,recognize, and monitor users ... technology advances, so too must the security systems ...
Breaking Biology News(10 mins):
(Date:12/8/2016)... 2016 AskLinkerReports.com has published a report ... Amyloglucosidase Industry 2016 Market Research Report. From a basic outline ... overview are all covered in the report. This report projects ... analysis of the Amyloglucosidase industry. ... , , ...
(Date:12/8/2016)... , Dec. 8, 2016  Renova™ Therapeutics, ... congestive heart failure and type 2 diabetes, announced ... a novel adeno-associated virus (AAV) vector developed in ... M.D., Ph.D., at Stanford University. The company plans ... paracrine gene therapy product pipeline. ...
(Date:12/8/2016)... CARDIFF, UK (PRWEB) , ... December 08, 2016 ... ... high precision light to control cells — optogenetics — is key to exciting ... state of the art, spatially patterned light projected via free-space optics stimulates small, ...
(Date:12/8/2016)... 2016 Oxford Gene ... seine Palette an anpassbaren SureSeq™ NGS-Panels mit dem ... das ein schnelles und kostengünstiges Studium der Varianten ... eine Erkennung von Einzel-Nukleotid-Variationen (Single Nucleotide Variation, SNV) ... kleinen Panel und ermöglicht eine individuelle Anpassung durch ...
Breaking Biology Technology: