96
ALBERTO MONROY AND RACHELE MAGGIO
specific proteins. Indeed, this is also the main problem of differentiation
It is therefore evident that nowadays the study of differentiation cannot
be divorced from the consideration of the participation of the genetic
material contained in the nucleus in the formation of the various specific
proteins and hence in the segregation of the various specific organforming areas. However, for this problem to be effectively dealt with it
is necessary that the genetics of the selected organism be sufficiently
well known. Unfortunately this is not the case with the sea urchin egg,
and indeed the organisms whose genetics are well or fairly well known
are not the most suitable ones for most of the investigations of chemical
embryology. This seems to discourage the hope that the study of
Echinoderms might make any significant contribution to a sufficiently
advanced analysis of the fundamental processes of differentiation.
Nevertheless, some of the data obtained from the study of the sea
urchin embryo appear to make an important contribution to the
understanding of the chemical basis of differentiation. And, what is still
more important, there are numerous problems which may best be
approached through this same material.
In this article we shall review some of the results obtained in several
Laboratories including our own with regard to the biochemical events
taking place in the development of the sea urchin embryo, and we will
try to see to what extent they can contribute to furthering the study of
the problems of differentiation. We are aware of the limitations involved
when working with one single organism and of the danger of attempts to
extrapolate the results to other animal groups. But for several years
now we have found ourselves in the fortunate (though it may possibly
turn out to be unfortunate) position of having a great opportunity to
work with this material, and we have felt a kind of psychological
difficulty in switching to any other.
II. Remarks about Methods
The method most widely used nowadays in the study of biochemical
processes in cells, is that of homogenization, followed by separation of
the various cell components by differential centrifugation. This method
has in fact provided most useful information and has led to the most
fundamental discoveries in the field of cell physiology and biochemistry.
However, Holter (1952) had already drawn attention to the danger of
elution and/or re-absorption of enzymes and other cell constituents in
the course and as a result of homogenization. Only in a very few cases
have the separated fractions been submitted to scrutiny of sufficient
accuracy to make certain that they actually did correspond to those it
was intended to prepare. As has been aptly pointed out by Brächet
ALBERTO MONROY AND RACHELE MAGGIO
specific proteins. Indeed, this is also the main problem of differentiation
It is therefore evident that nowadays the study of differentiation cannot
be divorced from the consideration of the participation of the genetic
material contained in the nucleus in the formation of the various specific
proteins and hence in the segregation of the various specific organforming areas. However, for this problem to be effectively dealt with it
is necessary that the genetics of the selected organism be sufficiently
well known. Unfortunately this is not the case with the sea urchin egg,
and indeed the organisms whose genetics are well or fairly well known
are not the most suitable ones for most of the investigations of chemical
embryology. This seems to discourage the hope that the study of
Echinoderms might make any significant contribution to a sufficiently
advanced analysis of the fundamental processes of differentiation.
Nevertheless, some of the data obtained from the study of the sea
urchin embryo appear to make an important contribution to the
understanding of the chemical basis of differentiation. And, what is still
more important, there are numerous problems which may best be
approached through this same material.
In this article we shall review some of the results obtained in several
Laboratories including our own with regard to the biochemical events
taking place in the development of the sea urchin embryo, and we will
try to see to what extent they can contribute to furthering the study of
the problems of differentiation. We are aware of the limitations involved
when working with one single organism and of the danger of attempts to
extrapolate the results to other animal groups. But for several years
now we have found ourselves in the fortunate (though it may possibly
turn out to be unfortunate) position of having a great opportunity to
work with this material, and we have felt a kind of psychological
difficulty in switching to any other.
II. Remarks about Methods
The method most widely used nowadays in the study of biochemical
processes in cells, is that of homogenization, followed by separation of
the various cell components by differential centrifugation. This method
has in fact provided most useful information and has led to the most
fundamental discoveries in the field of cell physiology and biochemistry.
However, Holter (1952) had already drawn attention to the danger of
elution and/or re-absorption of enzymes and other cell constituents in
the course and as a result of homogenization. Only in a very few cases
have the separated fractions been submitted to scrutiny of sufficient
accuracy to make certain that they actually did correspond to those it
was intended to prepare. As has been aptly pointed out by Brächet