A Quick History of Xenopus
1 “The Humble Batrachian”
John B. Wallingford
CONTENTS
1.1. Introduction .................................................................................................................................................................... 3
1.2. What’s in a Name? ......................................................................................................................................................... 3
1.3. Pregnancy and Prominence: The Rise of Xenopus as a Laboratory Animal ................................................................. 6
1.4. Some Unsung Heroes of Early Developmental Biology Research With Xenopus ........................................................ 8
1.5. The Ninth Day of Creation: Xenopus at the Dawn of Molecular Biology ..................................................................... 9
1.6. Where History Stops and “the Literature” Begins ......................................................................................................... 9
Acknowledgments .................................................................................................................................................................. 10
References .............................................................................................................................................................................. 10
Might I suggest that a little credit might be given to the
humble batrachian, which seems to give an invariably
correct diagnosis.
—J.W.C. Gunn (1939 )
When a developmental biologist says “in mammals” he
probably means “in the mouse”; by “in birds” he almost
certainly means “in the chick”. When he generalizes
more widely than this about mechanisms of differentiation in “all developing cells” there is a danger that he is
referring to work carried out exclusively on Xenopus.
—Elizabeth Deuchar (1972 )
1.1. INTRODUCTION
Frogs have played so central a role in biological research that
many people’s only memory of actual biological study involves
dissecting one in high school. It’s no surprise, then, that frogs
have been central to scientifc discovery for centuries. Marcello
Malpighi had at least an inkling of the concept we now call
“model organisms.” He repeatedly extolled the frog as an outstanding system for study, and it was in a frog that he f rst discovered capillaries of the circulatory system in 1661 (Holmes,
1993; West, 2013). He even wrote to his friend Giovanni Borelli
that “indeed, things show up much more clearly in frogs”
(Boorstin, 1985). Likewise, the entire feld of electrophysiology is frequently considered to have originated with Galvani’s
experiments on frog legs in 1791 (Piccolino, 1997 ).
The frog’s external development is another boon, one that
was exploited by embryologists at least since 1758, when
Johann Rösel von Rosenhof engraved the f rst chronological
depictions of eggs developing into tadpoles and then into
frogs (Wellmann, 2017). In 1886, nuclear transplantation in
frogs and toads would frst be attempted in an exploration
of the hereditary control of development (Rauber, 1886),
presaging Nobel prize-winning work on nuclear totipotency
nearly another century later. In the late 19th century, newts
and salamanders became the favored amphibian for embryologists (Beetschen, 2004), but beginning in the mid-20th
century, a curious foray into endocrinology in South Africa
led to the rise of Xenopus frogs as the dominant amphibian
for laboratory studies of biology across the world.
Since that time, Xenopus was used for discoveries as
varied as the frst description of nuclear pores, to the f rst
isolation of a eukaryotic gene, to the demonstration of the
totipotence of nuclei, to the invention of in situ hybridization. Several excellent historical memoirs of research on
Xenopus have been published previously, but each has a
more specifc focus on discrete elements of our frog’s success (Blow and Laskey, 2016; Brown, 2004; Deuchar, 1975b;
Gurdon and Hopwood, 2000; Maller, 2012). My goal here is
to provide a more general history of research with Xenopus.
I will cover the period spanning the frst description of the
genus in 1803 through about 1980, when work with Xenopus
exploded, establishing the vibrant model organism that we
use today. I hope the chapter will provide an entertaining
journey back in time for the Xenopus community, my scientifc family for over 30 years.
1.2. WHAT’S IN A NAME?
As has been frequently described, the f rst scientif c description of Xenopus frogs comes from the French naturalist
François Marie Daudin in 1803. But who was this man?
As it happens, he was a tragic fgure: having lost the use
of his legs (and also his mother) while still a child, he died
of tuberculosis at the young age of 27, shortly after writing
his description of what he called Bufo laevis or Crapaud
lisse (“smooth toad”). Despite his physical handicap and
DOI: 10.1201/9781003050230-2
3
1 “The Humble Batrachian”
John B. Wallingford
CONTENTS
1.1. Introduction .................................................................................................................................................................... 3
1.2. What’s in a Name? ......................................................................................................................................................... 3
1.3. Pregnancy and Prominence: The Rise of Xenopus as a Laboratory Animal ................................................................. 6
1.4. Some Unsung Heroes of Early Developmental Biology Research With Xenopus ........................................................ 8
1.5. The Ninth Day of Creation: Xenopus at the Dawn of Molecular Biology ..................................................................... 9
1.6. Where History Stops and “the Literature” Begins ......................................................................................................... 9
Acknowledgments .................................................................................................................................................................. 10
References .............................................................................................................................................................................. 10
Might I suggest that a little credit might be given to the
humble batrachian, which seems to give an invariably
correct diagnosis.
—J.W.C. Gunn (1939 )
When a developmental biologist says “in mammals” he
probably means “in the mouse”; by “in birds” he almost
certainly means “in the chick”. When he generalizes
more widely than this about mechanisms of differentiation in “all developing cells” there is a danger that he is
referring to work carried out exclusively on Xenopus.
—Elizabeth Deuchar (1972 )
1.1. INTRODUCTION
Frogs have played so central a role in biological research that
many people’s only memory of actual biological study involves
dissecting one in high school. It’s no surprise, then, that frogs
have been central to scientifc discovery for centuries. Marcello
Malpighi had at least an inkling of the concept we now call
“model organisms.” He repeatedly extolled the frog as an outstanding system for study, and it was in a frog that he f rst discovered capillaries of the circulatory system in 1661 (Holmes,
1993; West, 2013). He even wrote to his friend Giovanni Borelli
that “indeed, things show up much more clearly in frogs”
(Boorstin, 1985). Likewise, the entire feld of electrophysiology is frequently considered to have originated with Galvani’s
experiments on frog legs in 1791 (Piccolino, 1997 ).
The frog’s external development is another boon, one that
was exploited by embryologists at least since 1758, when
Johann Rösel von Rosenhof engraved the f rst chronological
depictions of eggs developing into tadpoles and then into
frogs (Wellmann, 2017). In 1886, nuclear transplantation in
frogs and toads would frst be attempted in an exploration
of the hereditary control of development (Rauber, 1886),
presaging Nobel prize-winning work on nuclear totipotency
nearly another century later. In the late 19th century, newts
and salamanders became the favored amphibian for embryologists (Beetschen, 2004), but beginning in the mid-20th
century, a curious foray into endocrinology in South Africa
led to the rise of Xenopus frogs as the dominant amphibian
for laboratory studies of biology across the world.
Since that time, Xenopus was used for discoveries as
varied as the frst description of nuclear pores, to the f rst
isolation of a eukaryotic gene, to the demonstration of the
totipotence of nuclei, to the invention of in situ hybridization. Several excellent historical memoirs of research on
Xenopus have been published previously, but each has a
more specifc focus on discrete elements of our frog’s success (Blow and Laskey, 2016; Brown, 2004; Deuchar, 1975b;
Gurdon and Hopwood, 2000; Maller, 2012). My goal here is
to provide a more general history of research with Xenopus.
I will cover the period spanning the frst description of the
genus in 1803 through about 1980, when work with Xenopus
exploded, establishing the vibrant model organism that we
use today. I hope the chapter will provide an entertaining
journey back in time for the Xenopus community, my scientifc family for over 30 years.
1.2. WHAT’S IN A NAME?
As has been frequently described, the f rst scientif c description of Xenopus frogs comes from the French naturalist
François Marie Daudin in 1803. But who was this man?
As it happens, he was a tragic fgure: having lost the use
of his legs (and also his mother) while still a child, he died
of tuberculosis at the young age of 27, shortly after writing
his description of what he called Bufo laevis or Crapaud
lisse (“smooth toad”). Despite his physical handicap and
DOI: 10.1201/9781003050230-2
3