CENTRIFUGAT主ON OF CHI
1主uNO将uS E
GGS INSERTED INTO THE HuLES 工N AN
AGAR PLATE

Masa限 i Sawa
Department of Biology，Faculty of Sciences，Ibaraki University，Mito，310 J呂 panLongitudinal double malformations are induced by cen七rifug昌 tion ofChironomu日 eggs (Yajima，1事60，1983; Gauss and Sander，1苦66; Qverton and Raab，1967; Kalthoff et alリ

1事77; 訳語 U註

nd K品 ltho王f，19821.

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祭会ゑ立主主主主s，wh告 n the 硲 ggs were centrifuged by the Yajima's method (1970)，inwhj.ch the egg 滋 昌 55 W品5 sucked into 品 gla55 tubin守， the d母velopm芭ntal re器 ults
在asses. This m昌 y be ascribed to thediffered among the centrifuged egg r

shortcoming of the method as followsi(1)工 f the in詰ide diamet合 r of the tubing i草 皆 ide主 than the width of egg mass，

it couldn't be obtained egg古 centrifug母d parallel to their lenghts.

The品jirtほ，1960).
parallel centrifugation yields 品 lot of double malformations (Y(2) Since the e守 守 殴 ass is stretched to about 4 cm in the tubing，thedif王erences of the centrifugal forces are so large between the c母 ntripetal 晶 ndcentrifugal end of egg mass.
Therefore， modifying little the method of centrifugation of Qrosophila
eggs adopedbyHowl呂 nd (1941)， in which theB雪 雪 書 官 告 re in草 草 主 主 号 d intohol告 s in
品red the result obtained from the agar method withthat
an agar plate，工 compfrorn the glass tubing m日 thod. However，when group器 of 唖 ggS' one group from
畠 r rnethod and the resultsware
each egg m品 55，腎 ere centrifuged by the aヲ
品red，there still occurred diff邑 renc母 of freguency of dev母 lopmental typ曹 s，compincludi時

double cephalons and invert日 d embryos，among th世 S世 間 9 masses.

n告 thod，s由 ver晶 1 egg groups from the sam申 告 99 mass ar睦
Since in this ag品 r r

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treated separately in different experimental conditions，1 performed following
two experiments. Firstly，egg groups from a same egg mass were centrifuged
one by one at different developmental stages from two pole cells to nuclear
migration stage. The result showed that the frequency of th巴 various develop‑mental types varied in small cycles and decreased gradually toward nuclear
migration stage. These results may b巴 due to the appearance and disappearanceof mitotic apparatus or a change of viscosity accompanied with nuclear divi‑
sion cycle.
Secondary，eggs wer巴 centrifuged anterolaterally at various angles.

Theresults showed that the frequency of the various types of development changed
with the angle.

For example，the fr巴 quency of double cephalons and inverted

embryos was higher after the anterolateral centrifugation at 600 than after
the anterior centrifugation (900 ) .

The latter angl巴 is the same as that ofthe early glass tubing centrifugation.

In future study，1 would like toinvestigate effects of the oblique centrifugation in detail.

References
Gauss，U. and K. Sander (1966)
Howland，JR. B. (1941)

Naturwiss.，53:182‑181.

Proc. Amer. phil
. Soc.，84:605‑616.

Kalthoff， K.， P. Han巴 1 and D. Zissler (1977) Develop. Biol.
， 55:285‑305.
Overton，J. and M. Raab (1967)

Develop. Biol.，15:271‑287.

Rau，K. G. and K. Kalthoff (1982)

Nature，287:635‑637.

Yajima，H. (1960)

J. Embryol. exp. Morphol.，8:198‑215.

Yajima，H. (1970)

J. Embryol. exp. Morphol.，24:287‑303.

Yajima，H. (1983)

Entomol. Gen.，8:171‑191.

Proc.Arthropod.Embryol.Soc.Jpn.，
1985