The Tetraploids of Newts Produced by a Shock of Ultrasonic Waves and the Histological Observation of Them

超音波刺激によるイモリの四倍体の作成とそれらの組織学的観察

Utsunomiya Yasuaki

広島大学水畜産学部紀要

Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University

イモリ(Triturus pyrrhogaster)とシリケンイモリ(Triturus ensicauda)の受精卵を超音波で刺激することにより多数の四倍体を二倍－四倍性モザイクと共に作成することができた。受精卵の二分割のかすかな条溝が現われた時超音波を照射するのがよく,その量は超音波で撹伴しながらその熱作用により5分間で39℃ないし3分間で42℃に昇温するときが効果的であった。同質四倍体はいずれも幼生の時は二倍体とほぼ同様に成長したが,上陸は遅れた。上陸後も外鰓は残り,皮膚は幼生のようで変態を完了できず,ほとんどの個体は半年以内に死滅した。これに対し異質四倍体は,二倍体とほぼ同様に変態を完了した。両者のうちシリケンイモリの雌にイモリの雄をカケ合わせた雑種から作った四倍体のほうが生活力旺盛であった。イモリとシリケンイモリの二種からの同種,異種四種の組み合わせの二倍体の内臓諸器官の間には特に著しい差はなかった。而しシリケンイモリおよびシリケンイモリ雌×イモリ雄の雑種はその脊椎骨は丈夫に見え,また骨化が他より進んでいるようだった。四倍体についても同様なことが云える。また四倍体の骨化が二倍体に比較して少し遅れるということが云える。

四倍体の内臓諸器官を構成する細胞並びに細胞核は全て二倍体に比較してその体積において二倍以上,数において少なかった。従って四倍体の器官の構造は一般に簡単である。特に四倍体の多くの線(胃線,涙線,唾液線,甲状線,脳下垂体等)は構造が非常に簡単で,数が少なかった。

四倍体の性比は,イモリ雌×イモリ雄からの14個体中雌6雄4,シリケンイモリ雌×シリケンイモリ雄からの1個体中雌1,イモリ雌×シリケンイモリ雄からの18個体中雌10雄7,シリケンイモリ雌×イモリ雄からの5個体中雌3雄2であった。

1) Many auto- and allotetraploids and diploid-tetraploid mosaics of newts were produced by treating the eggs of two species of newts, Triturus pyrrhogaster and Triturus ensicauda, by ultrasonic waves. When the temperature of the water around the eggs in the test tube was raised at 39°C, which required 3-5 minutes by the action of ultrasonic waves, the latter were effective in inducing tetraploid and diploid-tetraploid mosaics.
2) All the autotetraploids produced from Triturus pyrrhogaster or Triturus ensicauda had a same vital power as the control (diploid) until their metamorphosis, on the contrary after the landing, they could not complete their metamorphosis and died within half a year wholly.

The allotetraploids of Triturus pyrrhogaster and Triturus ensicauda could complete their metamorphosis and have a same vital power as the controls approximately. Especially the allotetraploids of Triturus ensicauda ♀×Triturus pyrrhogaster ♂ were stronger in vital power.
3) Among most of the organs of diploid newts of the four mating, Triturus pyrrhogaster ♀×Triturus pyrrhogaster ♂, Triturus ensicauda ♀×Triturus ensicauda ♂, Triturus pyrrhogaster ♀×Triturus ensicauda ♂, Triturus ensicauda ♀×Triturus pyrrhogaster ♂, especially conspicuous differences were not seen, but the vertabra of Triturus ensicauda and hybrid diploids produced from Triturus ensicauda were observed as stronger and their ossification were observed as more prograssive.

On tetraploids, the same facts as the above can be stated, too, but the ossification of tetraploids was generally seemed to be delayed a little as compared with that of the controls.
4) All the cells and cell nuclei consisted of every organs of tetraploids were larger than twice of diploid one in volume and less in number. Then the constitution of tetraploid organs was simple in general. Especially, all the gland tissues (gastric glands, lacrimal glands, salivary glands, thyroid gland, hypophysis etc.) of tetraploids were very simple in structure and very few in number.
5) The sex ratio made clear in tetraploid newts up to date, was 6 females and 4 males in 14 Triturus pyrrhogaster ♀×Triturus pyrrhogaster ♂, 1 female in 1 Triturus ensicauda ♀×Triturus ensicauda ♂, 10 females and 7 males in 18 Triturus pyrrhogaster ♀× Triturus ensicauda ♂, 3 females and 2 males in 5 Triturus ensicauda ♀×Triturus pyrrhogaster ♂.

動物学 [ 480 ]

英語

広島大学水畜産学部

[ISSN] 0440-8756

[NCID] AN00213563

[NAID] 40003288830