244
B. L. ASTAUROV
It has been shown (Ostriakova-Varshaver and Astaurov, 1947) that
the tendency to androgenetic development among the survivors varies
greatly according to the origin of the female parent ; females taken from
some parthenogenetic clones steadily give low percentages, and those
taken from others give high percentages of androgenesis among surviving
embryos (the ranges observed are 6.1-79.2%). It seems that the capacity
to undergo androgenetic development depends strictly on the maternal
genetic constitution, which opens some prospects for selection with regard
to this developmental character.
Some attempts were also made in our laboratory to obtain androgenetic development of ova laid by the females taken from triploid and
tetraploid parthenogenetic clones (unpublished). Androgenesis of tetraploid ova has been produced almost as readily as in the case of diploid
ova. In the case of triploid ova, only androgenetic progeny can survive;
all zygotes from $ 3 n X cf 2 n are aneuploid and unviable. However, the
total frequency of androgenesis in the offspring of triploid females, at
least in the progeny of females taken from the few polyploid clones
tested so far, is rather low.
Another possibility of producing purely androgenetic (i.e., purely
male) progeny is the elimination of all regular zygotic embryos by
means of heavy X-irradiation of eggs prior to insemination. As discovered
by the author for the first time in 1937 and later proved more precisely
(Astaurov, 1947a,b), a very heavy irradiation of the egg cytoplasm
(i.e., of the female moth prior to insemination) does not prevent the
survival and successful development of androgenetic embryos, provided
sperm nuclei have been derived from the unirradiated male parent
(Fig. 8). On the contrary, comparatively much less irradiation kills all
zygotic embryos as a result of dominant lethals induced in the maternal
chromosome set.
Solitary androgenetic larvae are capable of hatching even when the
egg cytoplasm is irradiated with a dose up to 500,000 r, and at least up
to 54,000 r the viability of androgenetic individuals remains normal. At
the same time the dose of 20,000 r is quite enough to kill 100% of
zygotic embryos that receive an irradiated female pronucleus besides the
irradiated egg cytoplasm (Astaurov, 1947a,b; Strunnikov, 1960). It is
therefore possible to eliminate all zygotic embryos and to obtain purely
male androgenetic progeny by treating oocytes with ionizing irradiation
prior to their insemination and the induction of thermal dispermic
androgenesis.
With regard to the biological range of irradiation doses, a principle
of general importance may be formulated as follows: the final (secondary) effects of ionizing radiation and especially its damaging effect
are connected mainly with primary irreversible changes in the genetic
B. L. ASTAUROV
It has been shown (Ostriakova-Varshaver and Astaurov, 1947) that
the tendency to androgenetic development among the survivors varies
greatly according to the origin of the female parent ; females taken from
some parthenogenetic clones steadily give low percentages, and those
taken from others give high percentages of androgenesis among surviving
embryos (the ranges observed are 6.1-79.2%). It seems that the capacity
to undergo androgenetic development depends strictly on the maternal
genetic constitution, which opens some prospects for selection with regard
to this developmental character.
Some attempts were also made in our laboratory to obtain androgenetic development of ova laid by the females taken from triploid and
tetraploid parthenogenetic clones (unpublished). Androgenesis of tetraploid ova has been produced almost as readily as in the case of diploid
ova. In the case of triploid ova, only androgenetic progeny can survive;
all zygotes from $ 3 n X cf 2 n are aneuploid and unviable. However, the
total frequency of androgenesis in the offspring of triploid females, at
least in the progeny of females taken from the few polyploid clones
tested so far, is rather low.
Another possibility of producing purely androgenetic (i.e., purely
male) progeny is the elimination of all regular zygotic embryos by
means of heavy X-irradiation of eggs prior to insemination. As discovered
by the author for the first time in 1937 and later proved more precisely
(Astaurov, 1947a,b), a very heavy irradiation of the egg cytoplasm
(i.e., of the female moth prior to insemination) does not prevent the
survival and successful development of androgenetic embryos, provided
sperm nuclei have been derived from the unirradiated male parent
(Fig. 8). On the contrary, comparatively much less irradiation kills all
zygotic embryos as a result of dominant lethals induced in the maternal
chromosome set.
Solitary androgenetic larvae are capable of hatching even when the
egg cytoplasm is irradiated with a dose up to 500,000 r, and at least up
to 54,000 r the viability of androgenetic individuals remains normal. At
the same time the dose of 20,000 r is quite enough to kill 100% of
zygotic embryos that receive an irradiated female pronucleus besides the
irradiated egg cytoplasm (Astaurov, 1947a,b; Strunnikov, 1960). It is
therefore possible to eliminate all zygotic embryos and to obtain purely
male androgenetic progeny by treating oocytes with ionizing irradiation
prior to their insemination and the induction of thermal dispermic
androgenesis.
With regard to the biological range of irradiation doses, a principle
of general importance may be formulated as follows: the final (secondary) effects of ionizing radiation and especially its damaging effect
are connected mainly with primary irreversible changes in the genetic