Jap.J.P
hyco.
l(Sorui)30:303‑
304.December15，1982

Gameteconjugationi
nPαndorinα(Chlorophyta，Volvocales)with particularreferencetothemating papilla
Hisayoshi NOZAKI
KeioSenioγ HighS
chool，Hiyoshi，Kohoilu‑
lzu，Yokohama‑shi，Kanagaωa，223Ja戸anhlorophyta;gameteconjllgatioll;isogamete;matiηgpapilla;Key!
ndex Words・ CPandorina;Volvocales.
Theprocessofsexual reproductionint
hetwospeciesof Pandorina，P.1norU7n BORYand P.unicocca RAYBURNetSTARR，wasob‑
servedunderc
ontrolledlaboratoryc
ondit
ionsint
heprevi
ousstudies(NOZAKIand KASAKI1979，NOZAKJ 1981). However，it was notdetermined whether thisisogamous genushas a mating papi
lla which initiatest
heplasmogamy ofthe gamet巴s，as do t
herelatedisogamousgenera，Volvulina(STARR
1962，CAREFOOT 1
966，NOZAKI 1
982) andAstrephomeηe (BROOKS1
966). The present
paper gives a detailed account of gameteconjugationint
hetwosp巴ciesof Pandorina，wit
h particularreference tot
he roleofmating papilla.
ThestrainsofP. 7norum and P. uni
coc
causedinthisstudy，aswel
lasthe methods
ofculture，mat
ing and observat
ion，arethesame asi
nthep
revio
us s
tudies(NOZAKIand KASAKI 1
979，NOZAKI 1
981)
P. m07um and P. unicocca showed essen‑ti
alythesameprocessingameteconjugation
During col
ony clumpi
ng，th
efir
s
tste
pof
t
hemating r
eac
ti
on，th
econs
ti
tut
iv巴 C巴I
lso
fth
ec
ol
onyescaped from th
eg
ela
ti
nou
s
matrixand functi
oned as gametes. Thesesphericali
sogameteshadthesam巴 organell
e
sa
sth
ev
ege
ta
ti
ve c
巴ll
s except t
hat theyboretransparent pa
pillaea
tthebas巴 oftheflagela (Figs.1，3). The
se papillae wer巴vari
ed i
nsiz
eand couldnot be detectedinsomegametes even with a phase contr
ast
mlcroscope.
伊民
ゆ'
F
ig.1
. G
ameteofPandorina lI1
1
icocca，showing matingpa
pillaaseo
fflagella(arrow heads). F
ig.2.lnitialstage(arrow) atth巴 bofpl
asmogamy inP.l1W l'lIrn. Notecyto
plasmicbridge(arrow)for
medb
ymutualmatingpapillae. Scale20μm.

目

，H.
NOZAKI

304

mating papilla in the two species ofPandorinau
singaphasec
ontr
astmicroscope.
ReferencesFig.3. Gamete clumpingandconju
gationofg
ametesinP
andorinamorum. Notem
ating11ae(mp)andt
hec
ytoplasmicbridge(cb)
papi
for
me
dbyt
hem
utua
l papi11ae. The arrowin‑dicatesresidualflagel
lartipsofg
ametes. Scale
20μm.

1ump
Thegametessoonaggregatedinacwith theirflagellartipss
tic
kingt
o one
another(Fig.3). Conjugationo
fthegametes
occurredinthisgametec
1umping. Duringthi
sproc
ess，twoofthegametesconnectedthei
rpapillae(Fig.2)，and t
hef
usin
goft
h
e
i
rwholebodi
esproceededl
aterally(Fig.
3). Asa result，a quadriflagellate zygote
was formed inthec1umpinggroup. This
motil
ezygotesoondepartedfromt
hegroup，leavingt
hetipsoft
heflagella(arrow，Fig.
3)，andentereda dormantperiod.
Thematingpapillaofthegametehasn
ot
beenr
e
por
te
dinealierobserv
ation
sont
hese
xualreprodu
ct
ionof Pandorina (PRING‑SHEIM 1
870， 1YENGAR 1
933， SMITH 1
933，MEYER 1
935，THOMPSON 1
954， COLEMAN，RAYBURN and STARR 1974，NOZAKI
1959and KASAKI 1
979，NOZAKI 1981). 1nthepresent study， however， 1 detected the野崎久義

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.1
3:367‑
375.
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966. Sexualreproduction andCAREFOOT，Jolvulinasteinii. J.Phycol.
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2:1
50‑
156.
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959. Sexualisolationin Pan‑
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rotozool
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49‑
264.
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amorum. ，.P.1
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白Pandorina (緑藻・オオヒゲマワリ目)の配偶子の接合過程と接合突起について

Pandorin
a属の P.morumBORY と P.unicocca RAYBURNetSTARRの同型配偶子の接合の過程を培養条件下で詳細に観察したところ，本属において今までに報告のない接合突起 (matingpapilla) が確認され， 配223神奈川県横浜市港北区日吉四丁目一番二号 慶応義塾高等学
偶子の融合は両接合突起の結合から関始した。 (校)