BBC Focus - 09.2019

Whowantstoliveforever?A tinyfreshwater

creaturecalledthehydradoes(andcan!),

andscientistsat theUniversityofCalifornia

haverevealedthesourceofitsremarkable

healingability.

Thehydrabelongstothesamephylum

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serpentmonsterfromGreekmyth,which

regrowstwoheadseachtimeoneis

cutoff.Butfreshwaterhydrashaveaneven

moreimpressiveabilitythanthemythical

beast:anentirehydracanregrowfroma

smallpieceoftissueinonlya fewdays.

Biologistsareparticularlyexcitedbythis

ability,sincemanyofthenetworksinvolved

inthehealingprocessdevelopedearly

intheprocessofevolution,meaningthat

theyaresharedamongmanyanimals,

includinghumans.

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recoveringbecausethebrainlacksthe

kindofregenerativeabilitiesweseein

hydra,”saidresearcherAbbyPrimack.

Therefore,if hydra’shealingabilitycan

befullyunderstood,it couldpotentially

beharnessedtohealbraininjuriesor

degenerativedisease.

Whena hydrais damaged,it growsnew

tissuefromstemcells.Stemcellsarefound

inhumanembryosandadultbonemarrow.

Theyarea basicformofcellwhichcando

somethingnoothertypeofanimalcellcan

do:theycanreproducetocreatea different

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braincellsorskincells.

Theteamanalysedmoleculesknown

asRNAtostudytheprocessesthatturned

hydrastemcellsintodifferentspecialised

cells.RNA,orribonucleicacid,is the

moleculethatreadsDNAandcarriesout

itsinstructions.BystudyingtheRNA,they

coulddeducewhichparticulargeneswere

beingactivatedintheprocess.

“Thebeautyofsingle-cellsequencingand

whythisis sucha bigdealfordevelopmental

biologistsis thatwecanactuallycapturethe

genesthatareexpressedascellsdifferentiate

fromstemcellsintotheirdifferentcell

types,”saidCelinaJuliano,whotookpartin

theresearch.

Hydrahasnotjustonetypeofstemcell,

butthree.Theresearcherstrackedhow

eachtypeofstemcellcoulddevelopinto

differentcelltypes.Theylearntthatone

pathbranchedouttocreateeitherneuronsor

glandcells,asthoughthecellhadn’tmadea

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studies,theteamwantstounderstandwhat

genesdeterminethisdecision.

Secret of the

‘immortal’

hydra’s

regeneration

ability

uncovered

Thisrelativeofjellyfish

canregrowitsentirebody

froma smallpieceoftissue

GET T Y IMAGES X2, ALAMY

ZOOLOGY

Think you’ve got

regeneration

skills, Wolverine?

Get a load of this

freshwater

hydra...