1062-3604/02/3305- $27.00 © 2002
Russian Journal of Developmental Biology, Vol. 33, No. 5, 2002, pp. 295–298. Translated from Ontogenez, Vol. 33, No. 5, 2002, pp. 361–365.
Original Russian Text Copyright © 2002 by Korochkin.
In the 1960s, the outstanding Russian embryologist
Alexander Neyfakh discovered that the spatial-tempo-
ral organization in embryogenesis of various animals is
of the morphogenetic
nuclear activity. It consists in that upon continuous
transcription, the informational, matrix RNA (mRNA)
providing for morphogenetic events is synthesized only
in strictly deﬁned time intervals, i.e., is as if quantized.
Neyfakh proved this statement using different methods
of transcription inhibition (Neyfakh, 1959, 1962; Ney-
fakh and Timofeeva, 1977, 1978). He notices that
inhibition of morphogenetic nuclear function by X-irra-
diation, to which the nuclei are especially susceptible
as compared to the cytoplasm which remains viable,
was accompanied by the inhibition of mRNA synthesis
The same effect is induced by the antibiotic actinomy-
cin, which speciﬁcally inhibits the mRNA synthesis. At
the same time, the rate of RNA synthesis in the whole
embryo does not follow the periods of morphogenetic
activity: for example, it is maintained in the loach
embryos at a constantly high level, starting from the
early blastula stage. This pattern proved to be universal
and was found in representatives of different animal
taxa (Neyfakh, 1961) (Fig. 1).
Hence, the quantum of information produced during
the period of morphogenetic nuclear activity provides
for the morphogenetic processes during a sufﬁciently
long interval of development and, then, another mRNA
portion is “sent” to the cytoplasm.
Thus, the morphoge-
netic nuclear activity is realized at the expense of syn-
thesis of speciﬁc mRNAs producing the proteins
involved in morphogenetic processes
Korolev and Neyfakh (1965) demonstrated that all
embryonic rudiments were also characterized by peri-
odic morphogenetic nuclear function. Each rudiment
had speciﬁc features expressed in different time inter-
vals of sensitivity to the nuclear function suppression.
The active nuclear function began in all zones at about
the same time (from 6 to 8.5 and after 14 hours of devel-
opment of the loach embryos at 21.5
C), while gastru-
lation proceeded in the absence of direct control of the
nuclei and was ensured by their preceding “activity.”
Meanwhile, different rudiments reached different
stages. Inactivation of the nuclei during the period from
8.5 to 14 hours of development induced the earliest
arrest in development of the ectoderm. Endodermal
cells are located between the periblast and chordameso-
derm (15 hours of normal development), their develop-
ment proceeded no further and they soon degenerated.
Mesodermal elements reached a somewhat advanced
stage of differentiation. The stages of developmental
arrest were different in tow components of the meso-
dermal complex: axial cell cord (notochord) and mass
of nondetermined mesoderm. Prospective notochord
cells form a compact cord characteristic of the late gas-
trula stage (18 hours). The material of neuroectoderm
Studies of A.A. Neyfakh on Periodicity of Morphogenetic Nuclear
Function and Their Significance
L. I. Korochkin
Kol’tsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow, 119991 Russia
Institute of Biology of the Gene, Russian Academy of Sciences, ul. Vavilova 34/5, Moscow 117334 Russia
Received April 29, 2002
—The studies of A.A. Neyfakh on morphogenetic nuclear activity are considered in the light of exper-
imental embryology data.
: ontogenesis, critical periods, speciﬁc transcription.
MATERIALS OF THE CONFERENCE
OF ONTOGENETIC PROCESSES”
2 6 18 22 26 3010
12 16 20 24 2862
2 6 10 14 18 22
4 12202836 4452606876
10 30 50 70
2 6 10 14 18
Timing of morphogenetic nuclear activity in embry-
os of various species (after Neyfakh, 1962).