Commentary by Professor Dave Hornby and Dr. John Dyer on student activities in the Liverpool Life Sciences UTC Innovation labs, together with suggestions for further reading and research
Friday, 11 September 2015
Turn and face the strange, ch-ch-changes
This time of year is always associated with great
change within schools and universities. Many of our students have left the UTC
and are set to embark upon an exciting new era in their lives by starting in
jobs, apprenticeships or higher education courses. Other students are moving up
a year, in some cases making the challenging transition from GCSEs to A Levels.
We also welcome a new cohort of Y10 and Y12 students, joining us in the
innovation labs at Liverpool Life Sciences for the first time. I have enjoyed
meeting you this week and look forward to an exciting year of research in the
The inspiration for my first blog post
came to me during my first innovation lab session with Y11 on Friday. During
the session the students were making observations about the different stages in
the life cycle of our very own model organism – the darkling beetle. It never
fails to fascinate the students and indeed myself that an organism can go
through such a transition or metamorphosis and emerge as what often looks like
a completely different species. So what better topic to begin this time of
great change than one of the greatest changes in the animal kingdom; complete
only after nearly finishing writing this post that I realised that Dave Hornby
had already written a little on this topic before the summer, including a title
based upon song lyrics. I guess that means I have spent too much time in the
labs with him over the last year! Anyway, it is a useful topic to revisit as we continue to develop our use of the darkling beetle as a model
organism for genomics and proteomics.
Let us start with the great Charles Darwin. The Voyage Of The Beagle covers Darwin’s part
in the second survey expedition of the ship HMS Beagle, which set sail on 27
December 1831. In this book Darwin tells the story of a German Naturalist
called Renous, who was arrested for heresy in Chile for claiming that he could
turn a caterpillar into a butterfly. Today it is common knowledge that many
insects, like the caterpillar go through a process of complete metamorphosis
and emerge as a very different looking organism. In fact, people have known
since at least as early as Egyptian times that grubs and worm-like
(they are not really worms) larval stages develop into
adult insects. However, there has been much confusion surrounded this incredible process. It is something which has always fascinated
me since being a child, collecting caterpillars to look at in an insect viewer,
through my final year university project studying the life stages of the
swallowtail butterfly (below) and now working on the darkling beetle in the
innovation labs at the UTC.
So what is metamorphosis?
According to Thain and Dixon’s - Dictionary of
Biology (1992), metamorphosis is a
“process during, and as a result of, which an animal
undergoes a comparatively rapid change from larval to adult form. Under
hormonal control, it is most noteable in the life histories of many marine
invertebrates, the majority of insects and of Amphibia. Often requires destruction
of much larval tissue and changes in gene expression.”
what occurs is a reorganisation of the organism’s tissues. Inside the
pupae the larvae essentially digests some of its own tissues into their constituent proteins. Some organs stay intact and others are broken down into groups of cells that can be reused. Some groups of highly specialised cells called imaginal discs start the formation of a specific body part of the adult stage, such as an antennae. The obvious physical changes that occur during
metamorphosis are accompanied by changes in the biochemistry, physiology and
behaviour of the organism.
So the questions which arise are what is the point
in going through this complex, potentially costly transformation? How does the
The most likely explanation comes from a reduction in
intraspecific competition for food and space. By having distinct life stages
which exploit different resources, these insects avoid direct competition with
their young, increasing their survival chances.
The evolution of complete metamorphosis in insects is
still considered a great mystery and many theories have been proposed to
explain it. An early attempt is the rather entertaining but implausible idea
proposed by Donald Williamson that the butterfly metamorphosis is the result of
an accidental mating between a ground dwelling species and a flying species.
More recent attempts have focused on the more likely idea that complete
metamorphosis evolved from incomplete metamorphosis. This theory is supported
by evidence from the fossil record as the earliest insects have life cycles
which are similar to modern ametabolous insects, like grasshoppers where the
young appear more like smaller versions of the adult and there is no pupal
stage. It is only later in the fossil record that we find examples with life
cycles similar to modern day holometabolous insects, those that undergo
complete metamorphosis, like butterflies and our very own darkling beetle.
read more about this follow the link below to a good summary by Ferris Jebr in
the Scientific American (http://www.scientificamerican.com/article/insect-metamorphosis-evolution/)
Since adopting the darkling beetle as a model organism,
our students have had great success and with Professor Hornby’s help, published
a paper in the current issue of the Young Scientists Journal (http://lifesciencesutc.co.uk/blog/young-scientists-journal/).
I am hugely optimistic that our new students will embrace their change in
environment and build upon the successes of those who have moved on to the next
stage in their lives.
So in the words of the great David Bowie - "Turn and face the strange, ch-ch-changes"