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• 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
“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.