Kato, Kazuo

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RIGHT:URL:CITATION:AUTHOR(S):ISSUE DATE:TITLE:Chromosome Arrangement in theMeiotic Divisions in Pollen MotherCells of Rhoeo discolor, HANCEKato, KazuoKato, Kazuo. Chromosome Arrangement in the Meiotic Divisions in Pollen Mother Cells ofRhoeo discolor, HANCE. Memoirs of the College of Science, Kyoto Imperial University. Ser.B 1930, 5(2): 229-2381930-03-31http://hdl.handle.net/2433/257736  ]vfEMOIRs oF TilE CoLLF.GE oF SclENcE, KyoTo IMI,ERIAL UNIvERslTY, SERIEs B                   Vof" V, No. 2, .A.RTIcLE IO, I930                   'Chromosome Arrangement in the Meiotic Divisions in PolleR Mother Cells of /k'/t'oeo dis,-o,ior, HANcEi)     t/t                                                           '                              l'ly                       KAzBo KAT6                     'iMil'li 3o T('xt-77..o'zi7'vs                     (I'xecel,vecl Fel)ruary 5, i930)    In the heterotype metapliase in polleik mother cells oÅí Rlzoeodi3coZor, the chromosomes are founct conjoined with one another toform a ring (I<. AT6, ig3o), ancl there is iio definite aiTran.crement of tkeehromosomes in cle'finite pxctterns, the free inoxrement of each chromo-somes being preventecl by its conjoiinment witliL the others. I[n theheterotype. anaphase and homotype metaphase, h'owever, the chromo-somes are quite free from o.ne Enother and arrange themselves on aplcane. into dcfinite confi.o.'urations. In the homotype metaphase, theyare V-N or ,I-shapecl, ancl the configurations of their an'angement seem,at the 'firs.t glEnce, to be niani'folcl, but if we tal<e only the point oÅíspinclle fiber cattachment in each chroniosoine into consideration, thearrangenients ccan be classified into several different types, as is thecEtse with Vi'ci'a• fa.ba. (IVIAEDA ancl I<Air6, ig2g)•                          '                        OBSERVATION                                '            21 7' 7' a• •n ,.o.. 'c' •ln e 71. t o../ Cll 7` o 7n. oso, 7n. es z'll X lu?                     1. IYe X• t •i'ol.i,Pe A7i a•f5 /i as (r    XVhen the chromosopnes are freecl from one another in the anaphaseI) Chromosome Arran.cr.e}nent AYT.23o I<Azuo l<AT6:-by the breal<ing of their conjoinment, and approach towards the poles,they are loBg+itiidinally double o"ring to tlieiir lonsritudina, 1 fission, tal<ingthe shape of an X, ancl asstune various confi.gurations of, arraiigeiiioiit.Althous,h the nornift,! nuniber of chroniosoines in this plane is 6, suchabnormal nuinbers o'f chroniosomes as .g or 7 are often fomid as theconsequence of unequal distrjbution of tlie chromosomes toxvarcls thepoles. In t-he followin.o' description each case o'f chromosome number,6, s and 7 will be g'iven separately.                   T/ie Casc of6 Clv'omosomes    In this case, the configurations of arrangenient can be classifiedinto two clistlnct forms, as shoxvn in the diag'rains in Table I (:FormI End llForm .'tl). Intermediate or transitory forms which clo not fai1into either of these forms are groupecl together as•Form I[I.                            'i"ABLE I          TIie case of 6 Åëhromosomes in the heterotype nnaphase. So]id          circles indicate the positions of the chromosomes in t]ie          arrangement.FormE:I)'tunber ofocctuJrenceII'ercentage85SO•9IIg[c>F IIIInterm.474L29li 7•9TotalH4Ioo    In Table I, we see. that Form 'I. which resembles the stEble formOf arrclll...crelnellt Of TLY{IAYER'S flO,ltill.O.' lll,lg'lletS (I i.O.'. D iS gl'{-)atel' illÅ}'requency of occurrence than Form II, in which all the chromosomesare ic rr.ang-ecl in a ring' having none of them insiCle it (IFi.o.'. 2). TliefrequeRcy of occurrence of intermediate fortns (Form III) is rathersmall, being on!y g out of ii4 cases•    Chi'omosoi7ie A•i'raii2gemeiit iiz$agX& Rg,e        IRhoeo2discolo7've kge$3231 gssxifs •&'pL;"5"ifgdipt$6     fg3e, sRteg, Z"X,  Jr'igs, I-g. tXrrangeinent conll..aurations of cln'omosomes in the heterotype anaphase.           Tlie das"s e/s avz(l.lh C"lv'omosom('s   rj]Nhe restilts obtainecl from the cases of s aRcl 7 chro.inosomes ai'ct(riven in 1[al)les I[ ancl .III.tb                     TABLE II                The case of 7 chromosomes. -I?oriiiINruinber ofoccurrencel IV••(Ii>I?ercentage 3-8866.7 v'x2l6.7 VIIInterni. 1Ltor1l.IlIl8.3 IOOIn the case of 7 chr. oniosomes, the inajority of the COIIficr11r.ltiOllS   b232 I<Az.vo I{:AT6:-belong to Form X,' in which 6 chroi'nosomes at'e arrang'ecl in a rin.o'haxriltg' the seveiktli in its center (Fig. ,s). 1?oi'in Xrl in xvhicli ail the7 cllromosomes tEl<e pal't ill tlle 'fol'lllatiOll Of tile 1'ill.o..' comes llext' illfrequency (.Fi.o'. 6). The coRfis.?'uration in which s chromosonies tal<g.up positions on a rhig ancl tlie sixth and seventlit occupy tliie i•nnerposit,ions insicle this rinLg' (lf'orin IX•i), ancl configurations xvhich arointerniediate or ti'ansitory (IF."ig". 7) were foun(1 respectively in onlyone case.                          "l)ABLE II[                     '.1)he case of S cliroinosoincs•ForinVIIIeIX xIriteriii.ITotalpm29LN'umberofoccut'rence5 24 o].'ercentage I7•.2 82.8t.o lOO    In the case of s chromosomes, as shown in 'Irable III, IForm IXin Nvhich all the. s chroniosonies niake. a rlns.)" having'r none inside it(Fig. g) occurs more frequently than 1[;aorm "K7I[I in xvhich 4 chromo-sonies nial<e a ring' 1]a.vinsr the fifth iR its center (Fig', 8). 'I'hcfreq"ency of occurrence of t'he fornier foirm is 82,89b of all the casesobserx'ecl.                   w st.                     Io(v Iol? Jr,ig. io. Aryangement config.uratioiis of chromosomes in two sister groups in the heterotype       anapliase. ct> 7 chromesonies of which 2 lie in a cliflrevent pla}ie froin tliat of       the otlier s. b) [["he sistey gronp svith s chroniosonies,             Chromosome Arranbaement in Rhoeo discolor 233    In both Tables II and III are excluded those forms of arrangement,                                             'such crts are sl}owR in llFig. ioa, in which only s chromosomes ot}t of7 arrange themseives on a piane, the remaining' 2 iagging- ones lyingunder that pla.ne.    In suinming up the results obtainecl in the heterotype cltnaphase itcan be said that the first maximum of frequency of occurrence is founclin any case of chromosoiirie number$ s, 6 and 7 in the config'urationreseinbiing the stable form of' attirangement oÅí ]VIAyER's floating magnets•            tlr'ran.crem6'iit of Cli•romoso-mes i'n lhe                    Z-7omotyPe .irfetaP liase    The chromosomes in the homotype metaphase are more slenclerand larger than tliose of the heterotype metaplncse aiad anaphase.There are 6 atelomitic chromosomes of which 2 are subterminal andthe others approximately meclian. They are arrang'ecl in the nuclearplate directing' their points of spinclle fiber insertion towards the centerof the arrangement configuration. All the config'urations observeclw• ere exa. mined oni.v. with respect to the position of the point of spindlefiber insertiot},                   Tlid Case' of 6 Cliromosoiiies    .te-x.s is seen in Table XV, configurations belonsring to Form XII inwhich s chromo$omes are arranged in the f-o. rm of a ring having thereiiriahking oBe in its center (Fisrs. ii aBd i2) occurs inarl<edly oftnerthan Form X[II in which all tlte 6 cltromosomes are arranged in theforin of a ring having none inside it (Fi.o's. i3, i4 and is). This formof arrangemeRt forms the first maxinkum, the frequency of occurrenceexpressecl in percentag-e being 47.s. In Fig. is, a chromosome withsubterminal spindle fiber attachment, stretches its arms out into anearly straight rocl across the eqRatorial piate. The point of spindlefiber attachment of this chroniosoine (marl<ed Å~) lies on the ring"consisting of the point$ of spinclle fiber attachment oÅí the other schromosomes, 'Ill'he word "riBg" is of course not iisecl here in its234 KAzuo KAtr6 :-strict sense. Oxving to the relatively small size and the semicircularshape of the cell in which the long chromosomes ar.e confineci, thearrangement config'urations are generally elliptical rather than circtrkar.IForm XI in x/ hich 2 chromosomes are surrounded by the reinaininErag. is an unexpected configuration and is very rarely founq (Fig. i6).INTo svich coltf/Lg-uratioiit was met xvitk in ii:ivestigations witliL SI2bi:na•ci2xancl Z71i'cde, both of which also carry 6 chroniosomes in the homotypeclivision (}v'fAEDA aRd KAT6, ig2g). Besicles these three types thereare other configurations differing froin any of theim, ancl they ares,rouped together into Iform XLIV (I?i.o's. i7, i8, ig, 2o and -..i). [llliehig'hly frequent occurrence of this form as comparecl with Case IV inSPitzaciiz seenis to be clue ro the diflleraty which long chromosomeshave in taldng their proper position in the arrangement in the relativelysmall confined space.                            ['ABLE IV  [ll'he case of 6 chromosomes. The clots on the rings in the accompanying diagrams    indicate the position of the point of spindle fiber insertion in eacli chromosbme.FormNtunber ofoccut'renceI.'ercentageXI<E))>4l.8XIII03147•5XIIIo5927.rl xiv  Intemn.    and  irrecrulat'    b5I23•5Total2I799•9    The ratio between [Forms XII icncl XIII in TEble IV is i.8:i,while in kS'Pi)zaciiz the Åëorresponding ratio is 2.4:i. The comparlsonof these ratios shows that tlie arrangement confi.o'uration of chromo-somes in A'/ioco resembles the arrangement of 1}ilAyEi<'s flociting magnetsto a ies$ extent than in SIPi'7ia,cid. T.his decreasa in tke degree ofresemblance seems to be cl!ie to the fact that while in kS'Pi:7?acilv thesmall i'ouncl chromosomes have a relatively ample space in which they        Chromosome Arran.aement in Rhoeo'discolor 23.scan move about freely, in leliodo the long chromosomes have to movein a relatively smill space.   >"IA"'e' s'NY.,}.l}' ?si)Weq Pg",ld'bG,`s     II I2. I3 I4  ee. iNtwfK. ,s"S. 2SY,V- x'    Is I6 I7 I8   2pu'"R q")NV(e e).,`',"e `::S'.%Xg    I9 20 2I 22  'a\.t"k cti.st{!e sur,`. eX};    23 2Ll.. 2s 26   #*? "?afk, '2< >>ss    27 28 2g 30 b"igs. H-3o. Arrangen]ent configurations of chromosomes iti the homotype metaphase.236 '  KAzuo KA"r6:--                Tke Cases of s aiitl 7 Cli'roniosom6's                 '    Tl}e results obtaingd froiin the case of 7 chromosomes are tabulateclin Table V. In this table, we see that Form XVI in whicli 6chromosomes take up their positions on the peripheral rin.cr of thechromosome arrang'ement having' the seventl} in its center (IFig's. 22and 23) is of most frequent occurrence, 48.70/6 of .ftll the cases observedbelonging to this form. Another form in which s chromosomes forma ying' and the remainiRg 2 occ"py inner positions inside the ring(Form XV, I{"ig. 24), and the form in whlch all the 7 chromosomesform .an empty ring (Case X' VI[[, Fig. 2s) are of less frequent occur•-rence, tlieir frequeRcy •values being io.3 9'o ancl 2o-.i O/o respectively.In Form XVIII those arrangemeltt config,urations tl}at can hardly beclassified as a definite pattern are groupeci'together (Fig. 26). Thepercentage of occurrence of these configuratioti an3ounts to i7.g.                            TABLE V                      The case of 7 chromosomes.I?orrnNumber ofocctlrrence].'ercent'.agexv(s)4Io.3XVI<[[III)I948•7XVII923.IXVI IIInterm. andirre(Jular  b717•9Total39Ioo    'Ilrhe restilts obtalned from the case of s chromosomes are shownin Table VI. Iilere we see that Form XX is of inuch more frequentoccurrence than the other two IForms, XIX and zXX, their perceritag.esof occurrence being sg.i in the former, and 22.7 ancl i82 respectivelyin the latter two. In the former all the s chroinosomes form a ringhaving none inslcle it (Figs. 27 anc!. 28), aRcl in one of the lattev (ForniXIX) 4 chromosomes tal<e up their positions on the circumference of             Chrom,osome ArTan.gement in Rhoeo discolora rin.cr surroundiRg" the fifth (Fig. 2g). IForm XXI comprisesinediate and irreg-ular configtirations that care hardly classifiable asof a def}Rite pE ttern (Fl.(,),'. 3o),  '                            [Il'ABLE "Vrl                      The case of 5 cliroinosoiiies.  237.Illtelr-fOl'lllSForni]l XIX<(s>N.Ttunbei' ofoccuvrenee?el'cellt,lae      bjlIO22.7xxO   xxi li ii l,t,;'E-• l  ivretsqii}ar lTotal26 ll8t'I4459.i I8.2lIOO    In the results mentioned above, it is shown that in each cicse,whether of s, 6 or 7 chromosomes, the arrangement configuratiolt whichoccurs most frequently is always that resembling the stable form ofarric ng'ement of .INtlAyER's fio.aLtin.o." inagnets, if the chromosome arrange-ment is examinccl with respect to the point of spinclle fiber insertionin tlie chromosoines.               CONCLUSION AND SUMMARY    In the heterotype anapha.se the configuration of chromosoi'Bearran.,o.'ement, which resembles the sta,ble config"uration of AilAyER'sfloating' ma..c.)'nets, i$ of most frequent occurrence in any case wherethe chromosome number is s, 6 or 7, and in t.lie homotype metaphasethe same is also true, if we consider in tiae examination only the pointsof spindle•fiber attachment of the chromosomes, The flrst maximumof t,he freqtiency of o.ccurrence is gre;xter in the heterotype anaphasethan in the homotype metaphase, and Åíhe seconcl max{mum is foundin the forni in which the. ntmiber of inner chroi'nosomes in the•arrang,'ement is less than that of the sttable form of lxN(rtNyEi<'s floatins')'                         '238 l<Azuo l<AT6niagne.ts. rl-he very hl.crh freciuency of occztrrence of the transitoryf()rms (Il?orm II) in the heterotype anapkase may l)e interpreted a. s dueto the fact that in thls pl?.tnt the chromosomes are linl<ed tog'ether ii}toa chain in tke inetaphase ancl that it ls only in the anaphac se that theycan move freely to tal<e up tlieir proper positions, The reletively sm,allclegree of resemblance to the stal).le form of rflAyi],R's fl( ating magnetsin the homotype division may be res.arded as due to the Åíact that IR•this plant the long' chromosomes have to move in a relatively smallconfined space,    In conclusion, the writer wishes to acknowledge his gratitude toPyof. ')t'. I<uwAD.x uRder whose direction this investiE,.ratioR was carriedout.                                      '                    LITERATURE CITEI)   t .tI<A'r(5, I<. (TL(;3o), Cytolo.crical Stuclies of l'ollen ).v'Iother Cells of lz'hoeo d,iscolor, f-I,sN(rF "'i:h    special t'eferi.ts.nc'-' to the P.aestion of th: },llode of Syridesls. i7L'[ern. CoH. StL, I<yoto    Imp. Univ. Ser. B. (Xl'oL. ivr, No. 2.). •:Itvr.i)tx, T. tiRd I<A'i6, I<, (ig2g), Chromosoniv iX.rrttngement VI{. The ]'ollen liY[othef                     '    Cel]s of SPintzcia oldrat-t,a, l[!LL. ancl F'i771't .11rba, L. Ibid. Xr' ol. IX/', X'o. 3.'

Chromosome Arrangement in the Meiotic Divisions in Pollen Mother Cells of Rhoeo discolor, HANCE

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Chromosome Arrangement in the Meiotic Divisions in Pollen Mother Cells of Rhoeo discolor, HANCE

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