• University of MassachusettsMedical School. (2016, July 21).Scientists untangle Barr bodyof inactive X chromosome:Highly elaborate chromosomestructure. ScienceDaily.Retrieved July 27, 2016 fromwww.sciencedaily.com/releases/2016/07/160721143503.htm

• Asociación RUVID. (2016, July20). XX protection against age-relatedmutations. ScienceDaily.Retrieved July 27, 2016 fromwww.sciencedaily.com/releases/2016/07/160720094446.htm

• MARTINEZ SÁNCHEZ, LinaMaría. Biología molecular. 8.ed. Medellín: UPB. Fac. deMedicina, 2015. 59 p.

• University of MassachusettsMedical School. (2016, July 21).Scientists untangle Barr bodyof inactive X chromosome:Highly elaborate chromosomestructure. ScienceDaily.Retrieved July 27, 2016 fromwww.sciencedaily.com/releases/2016/07/160721143503.htm

• Asociación RUVID. (2016, July20). XX protection against age-relatedmutations. ScienceDaily.Retrieved July 27, 2016 fromwww.sciencedaily.com/releases/2016/07/160720094446.htm

• MARTINEZ SÁNCHEZ, LinaMaría. Biología molecular. 8.ed. Medellín: UPB. Fac. deMedicina, 2015. 59 p.

The researches treated inhere have specialimportance because theydecrypt chromosomalmachinery by giving adescription of the Barr bodythat involves active DNAand by describing that aninactive X chromosome hasa protective effect forfemales. This may be theanswer ofor sex prevalencediseases and aging processin genders and this is thepoint where genic therapycan make tracking ofspecific mutations and givea diagnosis or cure inagreement to specificgenes and its expression.

The researches treated inhere have specialimportance because theydecrypt chromosomalmachinery by giving adescription of the Barr bodythat involves active DNAand by describing that aninactive X chromosome hasa protective effect forfemales. This may be theanswer ofor sex prevalencediseases and aging processin genders and this is thepoint where genic therapycan make tracking ofspecific mutations and givea diagnosis or cure inagreement to specificgenes and its expression.

The chromatin is a condensedstructured formed byeukaryotic DNA and chromatinproteins like histones and non-histone proteins.A chromosome is a structurecomposed by wrappedchromatin and it is essential forthe cellular division.

Cell cycle is the process thatcells make to divide and origindaughter cells with an specificamount of genetic informationand it’s divided in three periodscalled interphase, mitosis andcytokinesis.All these events are involved inorganism maintenance anddevelopment.

The chromatin is a condensedstructured formed byeukaryotic DNA and chromatinproteins like histones and non-histone proteins.A chromosome is a structurecomposed by wrappedchromatin and it is essential forthe cellular division.

Cell cycle is the process thatcells make to divide and origindaughter cells with an specificamount of genetic informationand it’s divided in three periodscalled interphase, mitosis andcytokinesis.All these events are involved inorganism maintenance anddevelopment.

Researchers at the University ofValencia's Cavanilles Institute ofBiodiversity and EvolutionaryBiology tested and confirmedthat differences in lifespanbetween the sexes may indeedbe due to the protective effectof having two copies of the Xchromosome.The explanation for this lies in thefact that most geneticmutations are by naturerecessive. For XX individuals, thismeans they are only harmfulwhen the same mutation occursin both copies of the Xchromosome, otherwise theyare not expressed. In the case ofXY individuals, with no 'guard',any recessive mutation presentin either the X or the Ychromosome would beexpressed unconditionally.STUDENT’S OBSERVATIONThis study helps to develop a fullexplanation about mutationalexpression and aging in males,being an important target forgenic therapy.

Researchers at the University ofValencia's Cavanilles Institute ofBiodiversity and EvolutionaryBiology tested and confirmedthat differences in lifespanbetween the sexes may indeedbe due to the protective effectof having two copies of the Xchromosome.The explanation for this lies in thefact that most geneticmutations are by naturerecessive. For XX individuals, thismeans they are only harmfulwhen the same mutation occursin both copies of the Xchromosome, otherwise theyare not expressed. In the case ofXY individuals, with no 'guard',any recessive mutation presentin either the X or the Ychromosome would beexpressed unconditionally.STUDENT’S OBSERVATIONThis study helps to develop a fullexplanation about mutationalexpression and aging in males,being an important target forgenic therapy.

Scientist at UMass Medical School,the Institut Curie in Paris andStanford University have taken adetailed look inside the small,densely packed structure of theinactive X chromosome found infemale mammals called the Barrbody.What they found was that the Barrbody wasn't a single dense massof DNA but instead is composedof two separately packed lobesseparated by a highly repetitivesegment of DNA called amacrosatellite repeat, found onlyin a few places in the genome. Dr.Dekker speculates that thesemacrosatellite repeats areresponsible for packing andorganizing DNA inside the Barrbody.

STUDENT’S OBSERVATIONFinding a possible function of theBarr body can open doors toresearch in the field of mutationsin DNA packing and relate it tofemale prevalence diseases givingthe key to a cure.

Chromatin packaged inchromosomes allows geneticinformation to fit in the nucleus

Determines the characteristics ofevery cell of the organism

Growth, development, division,gametes origin and preservationof genetic information are incharge of cell cycle

Scientists untangle Barr body of inactive Xchromosome: Highly elaborate

chromosome structure.University of Massachusetts Medical.

21 July 2016.

Inactive X chromosome:highly organized structure Two distinct lobes of

condensed inactive DNA Smaller structured

domains of active DNAembedded in them

Domains significant role ingene expression

The Barr body is composedof two separately packed

lobes separated by ahighly repetitive segment

of DNA called aMACROSATELLITE REPEATResponsible for packingand organizing DNA inside

the Barr body?

Process of thethree-dimensionalstructure of thechromosomes

Process of thethree-dimensionalstructure of thechromosomes

Cross two different mousestrains

Build a computational approach

Use naturally occurring mutations in oneof the X chromosomes as guideposts

Fill in the gapscomputationally andconnect enough dots

Clusters of genes insidethe lobes that are being

expressed

These genes reside insidetopologically associating

domains (TADs)

TADs organize thegenome into

neighborhoods separatedby boundaries rich in

CTCF proteins

CTCF proteins represstranscription

TADs play a role inmaking organizinggene expression

XX protection against age-relatedmutations.

Asociación RUVID.20 July 2016.

“The accumulation ofmutations over the course ofa lifetime, or passed on from

generation to generation,has a larger affect on the sexthat has just one 'unguarded'copy of the X chromosome;generally males, including in

human beings.”

Affects the lifespan of thehomogametic sex (individuals

with two of the same sex-determining chromosomes)

to a greater extent

INBREEDING inDrosophilamelanogaster

Heterogametic sex (with twodifferent sex-determining

chromosomes)is less affected

The X chromosome is only 'guarded' if thetwo X chromosomes are different, whichis not the case after repeated inbreeding

The X chromosome is always'unguarded', with or withoutinbreeding

Otherwise theyare simply not

expressed

XX individuals: theyare only harmful when

the same mutationoccurs in both copiesof the X chromosome

Most geneticmutations are

by naturerecessive

Full development ofthe chromosome

structure is importantfor people of themedical field to

understand its functionand so, gen expression

applied to health orpathology.

This researches may be theexplanation of why some mutationsaffect males over females and that

enables the development of specifictreatments to prevent or to cure the

diseases caused by them.

Both studies were made with thefinal intention of increasing generalpeople’s life quality byunderstanding normal geneticexpression and abnormalities thatare the cause of many diseases orthe prone to it. An specificchromosome and an specificlocation may be applied by genictherapy according to everyone’sdifferences. By using this resource inthe medical field patients wouldhave much better results.

Both studies were made with thefinal intention of increasing generalpeople’s life quality byunderstanding normal geneticexpression and abnormalities thatare the cause of many diseases orthe prone to it. An specificchromosome and an specificlocation may be applied by genictherapy according to everyone’sdifferences. By using this resource inthe medical field patients wouldhave much better results.

University of Massachusetts Medical School. (2016, July 21).Scientists untangle Barr body of inactive X chromosome:Highly elaborate chromosome structure. ScienceDaily.Retrieved July 27, 2016 fromwww.sciencedaily.com/releases/2016/07/160721143503.htm

Asociación RUVID. (2016, July 20). XX protection againstage-related mutations. ScienceDaily. Retrieved July 28, 2016fromwww.sciencedaily.com/releases/2016/07/160720094446.htm

MARTINEZ SÁNCHEZ, Lina María. Biología molecular. 8. ed.Medellín: UPB. Fac. de Medicina, 2015. 59 p.

University of Massachusetts Medical School. (2016, July 21).Scientists untangle Barr body of inactive X chromosome:Highly elaborate chromosome structure. ScienceDaily.Retrieved July 27, 2016 fromwww.sciencedaily.com/releases/2016/07/160721143503.htm

Asociación RUVID. (2016, July 20). XX protection againstage-related mutations. ScienceDaily. Retrieved July 28, 2016fromwww.sciencedaily.com/releases/2016/07/160720094446.htm

MARTINEZ SÁNCHEZ, Lina María. Biología molecular. 8. ed.Medellín: UPB. Fac. de Medicina, 2015. 59 p.