Condensin II never switches on in a tardigrade embryo: it is maternally supplied and shuts down with the division machinery

{"We":[0,249,349],"recently":[1],"reported":[2],"that":[3,151,178,213,251,282],"Hypsibius":[4],"exemplaris":[5,73],"has":[6],"a":[7,17,115,126,149,223,280,352],"complete":[8],"condensin":[9,174],"II,":[10],"including":[11],"two":[12],"divergent":[13],"CAP-H2":[14,83],"kleisins,":[15],"correcting":[16],"record":[18],"in":[19,57,216,269],"which":[20,343],"the":[21,24,48,53,60,77,136,141,159,169,197,200,204,217,237,245,252,257,270,287,293,298,326,329,332],"species":[22],"was":[23,37],"only":[25],"one":[26,318],"of":[27,76,140,199,319,328],"24":[28],"with":[29,196,292],"neither":[30],"condensin's":[31],"accessory":[32],"subunits":[33],"found.":[34],"That":[35],"argument":[36],"made":[38],"on":[39,274,356],"sequence,":[40],"structure":[41],"and":[42,94,106,125,156,185,189,236,277,340],"gene":[43],"order.":[44],"Here":[45],"we":[46,341,354],"ask":[47],"obvious":[49,210],"next":[50],"question":[51],"from":[52,164,337],"other":[54],"side:":[55],"when":[56],"development":[58],"does":[59,107,111,173,180,192,361],"complex":[61],"become":[62],"active?":[63],"Reading":[64],"Levin":[65],"et":[66],"al.":[67],"2016's":[68],"62":[69],"single":[70],"timestamped":[71],"H.":[72],"embryos":[74,87,95,259,290],"out":[75],"deposited":[78],"counts,":[79],"normalised":[80],"per":[81,104],"embryo,":[82],"falls":[84,119],"31.9-fold":[85],"between":[86,154],"sampled":[88,96],"before":[89],"15":[90],"h":[91,99,219],"after":[92,97],"laying":[93],"23":[98],"(158.3":[100],"to":[101,122,132,166,171,207,222],"5.0":[102],"counts":[103],"million)":[105],"not":[108,112,284,335,362],"return.":[109],"It":[110],"fall":[113,299],"alone:":[114],"replication-dependent":[116],"histone":[117,309],"H3":[118],"92.2-fold":[120],"(8,230":[121],"89":[123],"cpm)":[124,134],"mitotic":[127],"cyclin":[128,313],"B":[129],"86.3-fold":[130],"(1,738":[131],"20":[133],"over":[135],"same":[137,246],"span.":[138],"88":[139],"429":[142],"most":[143],"dynamic":[144],"genes":[145],"behave":[146],"this":[147,225,338,365],"way,":[148],"share":[150],"is":[152,162,177,183,193,212,261,283,300,324,334],"stable":[153],"17%":[155],"23%":[157],"as":[158,203],"fold":[160],"threshold":[161],"swept":[163],"4-fold":[165],"32-fold.":[167],"So":[168],"answer":[170],"\\"when":[172],"II":[175],"activate\\"":[176],"it":[179,182,191,367],"not:":[181],"present":[184],"running":[186],"through":[187],"cleavage,":[188],"what":[190],"switch":[194],"off":[195],"rest":[198],"division":[201],"machinery":[202],"embryo":[205,215],"turns":[206],"organogenesis.":[208],"The":[209,322],"confound":[211],"every":[214,317],"15--23":[218],"gap":[220,271],"belongs":[221],"batch":[224,247,296],"project":[226],"had":[227],"already":[228],"flagged":[229,258,295],"for":[230,305,308,312],"roughly":[231],"30-fold":[232],"low":[233],"ERCC":[234],"spike-ins,":[235],"deposit's":[238],"own":[239],"mid-developmental":[240],"transition":[241,330],"boundary":[242],"sits":[243],"at":[244],"edge.":[248],"report":[250],"usual":[253],"test":[254,281],"--":[255,260],"dropping":[256],"uninformative":[262],"here":[263],"by":[264],"construction,":[265],"since":[266],"they":[267],"lie":[268],"rather":[272],"than":[273],"either":[275],"side,":[276],"give":[278],"instead":[279],"circular:":[285],"across":[286,364],"53":[288],"unflagged":[289],"alone,":[291],"whole":[294],"removed,":[297],"monotone":[301],"(Spearman":[302],"rho":[303],"-0.72":[304],"CAP-H2,":[306],"-0.75":[307],"H3,":[310],"-0.76":[311],"B,":[314],"each":[315],"beyond":[316],"2,000":[320],"permutations).":[321],"magnitude":[323],"real;":[325],"position":[327],"inside":[331],"window":[333],"claimable":[336],"dataset,":[339],"say":[342],"further":[344],"data":[345],"would":[346],"settle":[347],"it.":[348],"also":[350],"correct":[351],"statement":[353],"published":[355],"21":[357],"September":[358],"2026:":[359],"elav":[360],"rise":[363],"transition,":[366],"falls.":[368]}

Authors

Publication Details

Journal
Zenodo (CERN European Organization for Nuclear Research)
Published
2026-09-21
DOI
https://doi.org/10.5281/zenodo.22879339
Primary Topic
Tardigrade Biology and Ecology
Type
preprint
Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
preprint

Condensin II never switches on in a tardigrade embryo: it is maternally supplied and shuts down with the division machinery

Meow-Ludo Meow-Meow
Zenodo (CERN European Organization for Nuclear Research)
Tardigrade Biology and Ecology
preprint

Condensin II never switches on in a tardigrade embryo: it is maternally supplied and shuts down with the division machinery

Meow-Ludo Meow-Meow
preprint en

Abstract

We recently reported that Hypsibius exemplaris has a complete condensin II, including two divergent CAP-H2 kleisins, correcting a record in which the species was the only one of 24 with neither condensin's accessory subunits found. That argument was made on sequence, structure and gene order. Here we ask the obvious next question from the other side: when in development does the complex become active? Reading Levin et al. 2016's 62 single timestamped H. exemplaris embryos out of the deposited counts, normalised per embryo, CAP-H2 falls 31.9-fold between embryos sampled before 15 h after laying and embryos sampled after 23 h (158.3 to 5.0 counts per million) and does not return. It does not fall alone: a replication-dependent histone H3 falls 92.2-fold (8,230 to 89 cpm) and a mitotic cyclin B 86.3-fold (1,738 to 20 cpm) over the same span. 88 of the 429 most dynamic genes behave this way, a share that is stable between 17% and 23% as the fold threshold is swept from 4-fold to 32-fold. So the answer to "when does condensin II activate" is that it does not: it is present and running through cleavage, and what it does is switch off with the rest of the division machinery as the embryo turns to organogenesis. The obvious confound is that every embryo in the 15--23 h gap belongs to a batch this project had already flagged for roughly 30-fold low ERCC spike-ins, and the deposit's own mid-developmental transition boundary sits at the same batch edge. We report that the usual test -- dropping the flagged embryos -- is uninformative here by construction, since they lie in the gap rather than on either side, and give instead a test that is not circular: across the 53 unflagged embryos alone, with the whole flagged batch removed, the fall is monotone (Spearman rho -0.72 for CAP-H2, -0.75 for histone H3, -0.76 for cyclin B, each beyond every one of 2,000 permutations). The magnitude is real; the position of the transition inside the window is not claimable from this dataset, and we say which further data would settle it. We also correct a statement we published on 21 September 2026: elav does not rise across this transition, it falls.

Zenodo (CERN European Organization for Nuclear Research)
Tardigrade Biology and Ecology
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.