Jpn.
J.Phycol.(Sorui)40:1
73‑175，June20，1992H吋imeYasui: Karyologicalobservationintheyoungsporophytesof
Costαrzαcos
tαtα(Turner)Saunders(Laminariales，Phaeophyta)
Kり lndexWords: chromosomenumber‑
Costariacostat
a一haploid‑Laminariales‑parthenogenesis‑
Phaeophyta
Hのime，
Y出 ui，FacuL
伊01F.
叫eries，HokkaidoUniversity，Hakodate，Hokkaido，041Ja
戸an

The brown alga，Costaria costata (Turner)
Saunders is very widel
ydistribu
tedfromnor
thernJ
apan tothe northweste
r
nP
ac
if
i.ccoasts， forming comunities with sev
eral
Laminari
aceou
splantsonkelpb巴ds，andt
hejuv
enile fronds are occasi
onaly used asseafoods. Re
cently，thec
hromosom巴 countsint
hesporophytec
elsoft
he fourpopu
larLaminaria spe
cies from J
apan (Yabu andYasui1991)werei
ndic
at
edt
ohavediffl
巴rentresults(n=32，2n=ca.
60)fromt
hep
revi
ou
s/ジ，:
7
¥.
‑

も1・三;~-tーreports (Abe 1939，Nishibayashi and lnoh
1956， Kaneko 1
972， Yabu 1
973， Funano
1983，etc.
)asn=22i
nt
hei
rzoosporangium.
The chromosome numbe
roft
hi
salg
a hasbeenrecordedt
o ben=ca.
30 a
td
ia
ki
ne
si
sst
agei
nt
he zoosporangium with para伍 nmet
hod(Nishibaya
shi and lnoh 1957，Oh‑
mori 1
967). Thepresen
tpaperr
eport
st
hec
hromosome number (n=32，2n=64) andtherat
iosofhaploi
danddiploi
dintheearly
sporophyti
cdivi
dingcelso
fthisalgai
ncul
‑ー ー
日ー・.
‑
•• /ese
〈ae

司i，/

¥2

Yasui，H.

1
7
4.
.
'，

iI.
‑

6d9

1
1

F
igs.1
‑
11. C
ostar
iacostata(Turner)Saunders.S
cale=10μm.One‑
celledsporophyteFigs.1‑
5. M
etaphasec
hromosomesof
haploidnucleioftheyoun
gsporophytes.1and2.Tw
o‑
celle
ds
poro
phyte.4.T
hr
ee
‑
celle
ds
po
r
o
phyte.5.Four‑celledsporophyte.Fi
gs
I¥IIIustr
ati
oni
nF
i
g.1.3.One‑celledsporophytes. B.
6‑11.Metaphasechromosomeso
fd
iploidnucleio
fyoun
gsporophytes. 6and7.T
hree‑celedsporophyte.1
0.F
iv
e‑
celleds
porophyte. 1
1.Nine‑ce
leds
porophyte
Two‑celedsporophyte.9ture.
Thematurespecimenso
fC.costat
awereco1‑1ectedatOsatsube，Minamikayabe‑cho，Hok‑kaido onJu1
y11，1990，were imme
diately
broughttotheFacu1tyo
fFisheries，
Hokkaido
University. Inthe1
aboratory，
1i
berat
edz
oo‑
spor
e
sfromthosefrond
swerecu1turedinthefilte
red seawater containing 0.01% SLP(SquidLiverProteinPowder)extract(Yabuet al. 1984) under 3000‑35001
ux with12L:12D photoper
iod，at10土 10C. After18‑
22 days cultu
re，theone‑toeight‑celed

sporophyteswerefixedat5‑
6hoursfromt
hestar
tofd
ar
k‑
per
iodbyethy1alcoho13:aceticacidsolution， stai
ned with aceto‑iron‑haematoxylin‑chloral hy
dratesolution (Wit‑tmann1965).
The one‑tothree‑celled sporophytes dis‑played to have exactly 32 (hap10id)or 64(diploid)chromos
omesa
tmetaphase(Figs.1‑4，Figs.6‑
9.
).Thenumberwast
hes
amewitht
he fourspeciesofLaminaria，L.angustatakjellman，L.j
aponicaAr巴schoug，L.ochotensis
Miyabe and L.relぜiosa Miyabe (Yabu andKaryologicalobservationintheyoungsporophytesofCostariacostata

175Table1. Numbero
fhaploidordiploidsporophyteso
fCostariacostata(Turner)Saundersobt
aine
dfromchromosomec
ounti
n出 ed
iv
idin
gcells.
Nuc1earphaseHaploidDiploid1‑
celledstage2‑celledstage3‑celledstage

67282239823537Yasui1991). Theratio(haploid:diploid)of
theone‑celledsporophytesshowedtobeap‑
however，thepercen‑
proximately70%:30%，
tageofhaploidwasrapidlydecreasingasthe
became2‑4%inthe
germinationdeveloped，Ta‑
four‑orfive‑celledstage(Figs.5 and10，ble 1). Although i
ti
sdi
ffi
cult to countthe
chromosomenumberofthemoredeveloped
sporophytes than nine‑ or ten‑celled stage(Fig. 11)，the rare occurrence for par司thenogeneticsporophytesofC.costatawassug‑
gested by the above results.

In size，thehaploid sporophytes (Figs. 1‑3) were nearlysamewiththediploid(Figs.6‑8)，
bothsporo‑phytes (width: 27‑35μm，length: 35‑45μm)
at one‑ortwo‑celled stagewerelargerthan
length:24‑31μm)ofthose(width:20‑25μm，the other japanese Laminariaceous plants
tal. 1985，
YabuandYasui 1991).
(YabueReferences93
9. Mitoseni
nSporangiumvonLaminan.aAbe，K. 1reschoug.Sci.Rep.TohokuI
mp.Univ.
japonicaAl.1
4:3
27‑
329.
Bio.1
983. Theecologyo
fLaminaria religiosaFunano，T4‑celledstage

5‑celledstage

2
7Miyabe. 1. Thelifehistor
yandt
healternationofnuclearphaseso
fLaminaria叫 igiosaandt
hephysio‑logicalecologyofgametophyte
sand血 eembryonalsporophytes.Sci.Rep.HokkaidoF
ish.E
xper.S
tat.
2
5:6
1‑
1
0
9Kaneko，T.1
972. S
porogenesisi
nLaminariajaponicavar.ochotens
isOkamura.Sci.Rep.HokkaidoF
ish.
.1
4:4
5‑
53.
Exper.Stat.andInoh，S.1
957. MorphogeneticalNishibayashi，TstudiesinLaminarialesII. The development ofzoosporangia and thefor
mationofzoosporesin
凸star
iacostata(Turn.
)Saunde
此Biol.J.Okayama
Univ.3:169‑
181.
Ohmori， T. 1
967. Morphogenetical studies inl.J.OkayamaUniv.13:23‑84.
Laminariales.BioYabu，H.andYasui，
H.1
991. Chromosomenumberi
nfou
rspecieso
fLaminaria.Jpn.J.Phycol.3
9:1
85‑
1
89.
985.
Yabu， H.， Yamamoto， H. and Yasui， H. 1
jellmaniellac
間 sifoliaCytologialobserv
ations on KandEiseniabicyclis(Laminariales，Phaeophyceae)
Bull.Fac.Fish.HokkaidoUniv.3
6:64‑
68.
asui，H.andTakamoto，M.1
984. Unda
πaYabu，H.，Y
gametophytesincuIturew
ithSLP(SquidLiv
erPro‑tein)extr
act.Bull.Fac.Fish.HokkaidoUniv.3
5:
195‑
200.
965. Aceto‑iron‑haematoxylin‑
chloralWittmann，W. 1hydrateforchromosomes
taining.S
tainTech.40:
161‑
164.

安井肇:スジメの初期胞子体に於ける核学的観察
褐藻コンブ目植物スジメ Costariacostata(Turner)Saundersの成熟藻体より得た遊走子を培養して雌性配偶体上に形成される 1‑数細胞期の芽胞体について核分裂を調べたところ n=32または 2n=64の染色体数を有する 2種類の個体が観察された。これらの芽胞体に於ける単相体の割合は 1細胞期で約 70%に達していたが，その後減少 し 2細胞期で約36%， 4‑5細胞期には数%以下となった。 1‑2細胞期での単相体と複相体の大きさはほぼ同じであったが，何れも他の邦産コンプ科のものより幾分高い値を示した。

本種では，少なくとも初期発生の段階で正常 2倍体と単為発生体が混在しているものと推察された。 (041 函館市港町3‑1‑1 北海道大学水産学部)