FISHERIES AND MARINE SERVICE Translation Series No. 4422

FISHERIES
AND MARINE SERVICE
Translation
Series No. 4422
The
physiology
of
differentiation
and growth
II.
Critical periods
in the
development
of salmonids
and
their physiological basis
by A.N. Trifonova
et al.
Original
title:
La physiologie de la différenciation et de la croissance
IL Les périodes critiques dans le développement des salmonides et
leur base physiologique
•From:
Acta Zoo1.20: 239-267, 1939
Translated by
Translation Section
Department of
Fisheries and the Environment
Department
of the
Environment
Fisheries
and Marine Service
Faci“c Biological
Station
Nanaimo, B,C,
3 8
pages
typescript

•
• S
239
THE PHYSIOLOGY
OF DIFFERENTIATION
AND GROWTH
IL CRITICAL PERIODS IN THE
DEVELOPMENT OF SALMONIDS AND THEIR
PHYSIOLOGICAL BASIS
BY
A N TRIFONOVA, M F VERNIDOUBE and N D PHILIPPOV
(Laboratory
of Ichthyology of the
State University of Leningrad and
of the Institute for
biology of Peterhof. Director: Professor K M DERJUGIN).
TABLE OF CONTENTS
1, Introduction and statement of the question.
239
2. Critical periods in salmon development
240
3.
Acclimation
of fish eggs exposed to high temperatures
246
4.
Growth rate in the development
of salmon embryos
248
5. General
data on the growth rate of the
salmon embryo 250
6. Glycolytic processes
in the development of salmon .
embryos
254
7.
Respiration during embryonic development
of the
salmon 258
8. General conclusions
264
1. INTRODUCTION AND STATEMENT
OF THE QUESTION
In the development of
fish that spawn in the spring, the periods
of
growth and
differentiation are
characterized by different
types of
metabo-
lism
and by
differences in the ability
of eggs to resist
the effect
of harmful factors.
During the period of
gastrulation and growth of
the tail (caudal bud), the
embryo shows an intensive growth rate, a
shift of the Pasteur-Meyerhof
equilibrium boward the
predominance
of the processes
of anaerobic fission and a
high resistance to harmful
factors. During
the passage to gastrulation (differentiation
of the
embryonic layers) and the formation of the axial organs, the
Pasteur-
Meyerhof equilibriumellifts
in the opposite direction. The
role of
anaerobic processes is suppressed in the
metabolism
of the eggs and
they are damaged by the slightestuiverse action. The

•
240
type of metabolism i and the reaction of the egg to harmful factors therefore
vary depending on
thê .
Privolniev, 1935; NikiforOv, 1937).
_morohcfgenetic Processes-(Trifonova, 1935-1937;
The relation between morphogenesis and the type of metabolism has
been established only for fish that spawn in the spring (perch, ruffe),
the embryonic development of which differs considerably from that
of the salmon.
In the latter, incorporation is rapid, probably because of the smaller
yolk, and the anlage of the embryo forms at the stage of blastopore
closure. It can be seen, then, that
in the development of these fish,
the stage of the
anlage of the axial organs almost coincides with the
formation of the caudal bud (Chevey, 1925).
In fish that spawn
in the spring, blastopore closure
modifies the type
of metabolism (respiration becomes
more intense, the glycolysis decreases,
the eggs become
more sensitive). If the type of
metabolism
and the
morphogenetic
processes
show an
interrelationship, we
have
to know whether this change
in
metabolism is linked to the formation of axial organs or to
blastopore
closure connected with the formation of the caudal bud. The study of
perch development cannot provide an
answer to this
question, since in the
perch these two processes almost coincide.
In the development of the
salmon, on the
other hand, embryo formation and blastopore
closure are
separated; -- the axial organs form much earlier,
and at the moment of
blastopore closure
the embryo already has
28 myotomes.
The
purpose
ofthis
study is firs;to
determine whether in
salmon development there is a
connection between the type of
morphogenesis and the type of metabolism,
similar to that observed in fish that spawn in the spring, and second,
to determine whether the change in metabolism that occurs
in the perch
at the stsge of blastopore
closure occurs in the salmon at the start
of embryo formation (neural keel) or at the blastopore closure stage.
For the purposes of our study we examined the stability of
eggs at various
stages of their development,
the growth rate, the respiratory rate and
the formation of
lactic acid. As the material for our study we chose the
eggs
of Salmo salar.

241
2.
CRITICAL PERIODS IN SALMON
DEVELOPMENT
In the development of
fish that spawn
in the spring, there is hyper-
sensitivity not only at
the stages of passage to gastrulation and formation
of the axial
organs, but also at
the start
of segmentation. The sensitivity
of this latter
period is related neither to
the nature of the
morphogenetic
processes nor to
the type of metabolism
(Trifonova, 1935, page 780). An
acute sensitivity at the start
of segmentation is observed
in many forms
and is probably caused by
the fact that at this period
the regulatory
mechanisms
of the eggs have
not yet had time to develop. According to
Hein
(1907, 1911), salmon eggs are
especially stable at the start
of
development. With time their sensitiveness increases to reach its
maximum on the fourteenth day
of
development, after which it again decreases.
According to
Hata (1927),
another salmonid,
Oncorynchus mason, possesses
in addition to this sensitivity period to
daysfourteen and
fifteen
of
development, another sensitivity period at
the start
of segmentation.
During the
sensitivity developmental periods,
the embryo is easily
harmed by a wide variety of factors (Hein,
Svietlov)
. Trifonova (1935)
and Privolniev (1935), in
their studies of
fish that spawn
in the spring,
used
- respectively asphixia
and high temperature
as harmful factors.
In the present study,
the harmful
factor for groducing
differentiated
sensitivity is also high temperature
(19.5-21 C). At some stages
this
temperature
causes the rapid
destruction of the eggs, whereas at other
stages the eggs will remain alive for
dozens of
hours. For
each experiment
we took 25 eggs which we placed
in a crystalizer
with 300 ml
capacity
containing 200 ml of water.
During the
experiment we always marked
the
point
at which the
first egg died, then in succession the instant of
death of all the
other eggs to the last egg. In
some experiments,
the
eggs were all dead only after
60 to 70 hours. In all, over
a
period of
two years (1934-1935),
we carried
out
95
experiments
on 5 batches of eggs.
These experiments covered
the whole developmental process from
the start
of segmentation
to hatching. We fixed the
eggs and then made total
preparations (boric carmine), after which we compared experimental results
from the same stages (table
I and figure 1).
These results clearly
show
first, that
the salmon, unlike the
perch (Perca fluviatilis),
in full
agreement with
the data of Hein, has its stablest
stage at the
start of
segmentation (death of the first egg
in 28.6 hours
and of the last in
58.3
hours) . Our
results tallied with Hein's also
in that the particularly
acute sensitivity began
on the
same day of
development in
our experiments
as in his.
1
The figures are the average of
all the
experiments at that particular
stage. Table I, bottom line.

242 & 243
Table
I. Mortality of
salmon eggs under the effect
of high temperature.
LEGEND (see photocopy next
page)
1.
Stages
2. Morula of the large
cells
3.
Morula of the medium
cells
4. Morula of the small cells
5. Start
of gastrulation
6. Gastrulation at a more advanced
stage
7 « . Growth og the
forming embryo
8. Blastopore closure
9. Growth of the
embryo until eye pigmentation
10. Series of experiments
11. Time till death in
hours:
12. Of the first egg
13. Of all eggs
14. Average
15. Average of
all series