[Type text]
2013
Erfahrungsbericht zur Bachelor
Thesis
Galina Bernhardt
Studiengang Mechatronik
Trinational
www.trinat.net
Virtualdissectionofbeebrainsbymicro‐computed‐tomography(micro‐CT)
Erfahrungsbericht zur Bachelor Thesis 1
Introduction
Bees are both ecologically and economically important insects. Bees pollinate many of the world’s crops
– a service critical to the human survival. A great body of research indicates a worldwide decline in the
bee populations. Three main hypotheses are currently proposed for their decline: a) negative effect of
parasitism, b) degradation of their ecosystem and c) the impact of pesticides on bee physiology and
fitness.
Recently published research lends weight to the thesis that commonly used pesticides such as
neonicotinoids are causing irreparable damage to the bee population. Although, there is now general
acceptance that pesticides adversely affect the bee population there is still no understanding of clear
mechanism for their death. This work was focussed on furthering the understanding of mechanism of
the impact of pesticides. Our research was motivated by the hypothesis that beyond differences in
volumes of brain regions it is also possible that there are detrimental effects due to changes in shape of
the brain regions.
My work is only a part of a bigger project endowing inter alia behaviour and learnability study of
bumblebees.
Methods and Discussion
To be able to analyse the bee brain regions without destruction we had to use technics such as
computed tomography (CT). But using non‐destructive imaging technics such as CT, MicroCT or MRI etc.
may experience a problem of automatically or semi‐automatically separating different tissues.
Therefore, a solution was needed for better differentiation. One of the solutions could be staining,
which needs to be applied on the object before scanning. There are a number of stains generally used
and accepted by researchers, such as osmium tetroxid or uranyl acetate etc. All of them stain different
part of a tissue. Furthermore different stains penetrate different tissues at different speeds, which is
very crucial and useful. Therefore before we were able to gather qualitative data for analysis we had to
developed protocols for staining and better separation of different tissues and after that we could start
with scanning and analysis.
Staining is a supporting technique used mainly in microscopy to improve contrast in the microscopic
images. Stains as well as dyes are often used in medicine and biology to highlight structures in objects
for better viewing. Staining is not limited to biological structures and is also used in the industry to
highlight e.g. micro fractures or structure of metals or polymers. But staining in CT or MicroCT is a novel
technique and need better understanding and investigation.
In dese work tree stains (uranyl acetat (UA), Iodine, phosphotungstic acid (PTA)), which were already
used with success by other researchers are investigated.
Erfahrungsbericht zur Bachelor Thesis 2
The bee body was separated from the head. Since our interest was
only in brain, only this part was stained and scanned. In order for
staining to penetrate the entire brain, front part was cut (Picture 1)
with scalpel. The scans were carried out almost daily on the Metris X‐
Tek HMX ST 225 CT System.
In the (Picture 2) you can see the author with
Dr. Pedroso Rovira preparing the bee heads
for scan in the NHM lab.
After scanning during several days and
comparison, it was found, that UA, which
works great as negative stain in electron
microscopy, did not deliver any results. It was
also found that Iodine acted very fast. After
two days in staining, the contrast between
different tissues could be seen. Although
between days 6 and 7 the shape of the brain
was crispy, it started to be blurry or foam like. It is assumed, that there is a limit till which the brain
tissues can absorb Iodine and then start to bleed out creating exactly the effect, which appeared in this
study. After looking at the PTA it was observed that one of the brains was perfectly stained after day 7
while the other one was only half stained. It seems like the PTA stain went all the way from front
chopped part to half of the brain and then stopped. The well‐stained brain looked very crispy and all the
shapes could be separated easily. In addition, a negative effect, such as bleeding out like in Iodine did
not appear. On the contrary the shape was maintained during next days in the same conditions.
All behavioural and learnability test on bees were carried out previous to this part of the project.
Furthermore, to avoid any bias, until the statistical analysis were carried out it was a blind study i.e.
student was unaware of which specimen was treated with Imidacloprid and which one was from the
control group.
On account of time limitation for the completion of this project and the ability to capture shape, volume
and surface with landmarks we decided to use a combination of VG Studio Max and Drishti. Both are
programs widely used in this field. The decision is also based on careful analyses and comparison of
different to that time available programs.
Picture 1: Bee head frontal cut
Picture 2: Preparations in the NHM Lab
Erfahrungsbericht zur Bachelor Thesis 3
For capturing shape, volume and surface we placed in total 20 landmarks all over the parts of the brain,
we expected to differ the most. All 20 (3D) landmarks were imported in to PAST a statistical program for
analyzing landmarks, originally aimed at paleontology. But before we could place all the landmarks we
had to “clean” the brain or to remove all tissues, which were blocking the view. In Fehler! Verweisquelle
konnte nicht gefunden werden. you can see the scan in Drishti and after several hours of “cleaning” you
could place all the landmarks for the statistics. A bee brain with all the landmarks and cleaned can be
seen in Picture 4.
Benifit of this work and future work
The main goal of this ongoing project is to use a cross‐disciplinary approach combining expertise in a
diverse range of fields to find a new, innovative way to investigate the effect of pesticides on brain
morphology. We had to test different methodologies to standardize and optimize the results and we are
preparing scientific publications to provide the community with protocols to perform similar studies on
bees. In our opinion, with this work we are closer to solve the mystery about the bee disappearance.
Data analysis are still ongoing and we are excited by the great potential of this project, on one hand to
change the way to study bee brains and on the other to provide rigorous scientific information for policy
makers to address the pressing issue of pesticides impacts on essential pollinators.
Even though we have with our landmarks good information about the size, symmetry and the shape of
different brain regions, we could still be missing important information by choosing wrong or too less
landmarks. Additional, it seems like optical lobes play a key role in our analysis and they need to be
investigated further. A Master student took over this work and uses different methods to analyse the
datasets for further conclusions.
The classifications of bees are not updated. The categorization was made long time ago and without
modern technics. Accordingly, it is possible that the classification could be inaccurate and scientists all
over the world are working on the classification. Our method could build a basis for such classification.
Bees could be scanned, segmented and with help of “landmarks” a comparison of numbers of futures
such as brain, bone etc. in volume and structure can be made in reasonable time as well.
Picture 3: Scanned and stained bee brain Picture 4: Cleaned bee brain with landmarks
Erfahrungsbericht zur Bachelor Thesis 4
Furthermore, our developed staining protocols are now used in different studies such as scanning of fly
heads or even human eye.
Additional Information
The members of the team are: Dr. Farah Ahmed, Dr. Richard Gill and Dr. Inti Pedroso Rovira, Dr. Richard
Abel and Galina Bernhardt.
The project team was very diverse – two British, one Argentinian and one with Pakistani background and
a German – with different cultural, religious, work style. There was potential for misunderstandings. But
studying for several years in a multicultural class (Germans, French and Swiss) you are more sensible for
such misunderstandings and know how to react.
Additionally, the analysis work was done in Imperial College with research performed in Natural History
Museum – this can be challenging both from logistical standpoint and supervisory (who might have
different viewpoints on the problems). Being part of this so called matrix‐organization (being student of
FHNW and spending time in other universities) student is used to this kind of situations and needs being
able to adapt to the situation easier and gather all relevant information from different parties.
Despite all the challenges I was faced in this project I would do the project again. And winning an
Innovation price 2012 from the Swiss engineering society is a nice recognition for all my efforts.
Formation of this work
I already worked in Stage II and III with Dr. Richard Abel, who was also my supervisor in this work. Both
of us know what we can expect from each other and we work great together. Before the thesis it was
clear that my work would involve MicroCT and maybe medicine (Hyman body) or animals. As Dr. Abel
approach me with the bee project, it made me very curios and I agreed with excitement to be a part of
this project.
Relations with course of „Mechatronik Trinational“
You would be surprise how much information I could used or transform from the coursework. E.g. this
work involved managing projects with more than two parties. Issues such as time management,
effective communication and managing logistics when each member is not present locally were critical
for the success of the project. Skills obtain in management as well as cultural management obtained in
lectures such as Intercultural management, Prozessmanagement, Unternehmensführung und Controlling
and other management subjects proved to be very valuable for this project.
In subjects such as medical technics (Medizinaltechnologie) I obtained general information about CT and
image processing and editing. In particular the practical experience was gained on systems such as
Metris X‐Tek HMX ST 225 CT Systems. During previous practical parts of the course, I studied noise in the
CT data described in Stage II and applications of image processing and editing. Mathematical
background such as Méthodes Numérique, Differntialgleichungen or Métrologie, Informationssysteme
gave good insight into how CT data is reconstructed. Medical technics and Transformationen were very
Erfahrungsbericht zur Bachelor Thesis 5
useful to understand the impact of digital filters or smoothing filters on the data. CAD, Konstruktion and
Fertigungstechnik or Photo Shop classes and practical experience Stage II and Stage III gained from
previous internships were very useful to understand and getting used to process 3 D digital data, which
was big part of this project. Understanding of manipulation of the data was possible with Statistics as
well as skills obtained during Semester project. Also skills to manage projects independently was
practiced during the last semester group project, where a group of two to three student worked on
projects with as little involvement from supervisors as possible.
Recommendations
Don’t hesitate to choose a project in a field, which you think has less to do with mechatronics e.g. study
bees. You would be surprise how much of the lecture work you can apply. In my opinion, the most
important point is to choose a topic in which you have a personal interest and where you can develop
yourself and grow. It will be very helpful constantly to motivate yourself through the progress, as you
have to spend 3 to 6 months on the same topic.
Secondly try to find a supervisor as well from university as from industry/company with whom you can
work together. By this I mean, who will support you with suggestions and have always an ear for your
problems during the project and eager to motivate. It doesn’t necessary need to be someone from the
same field. It is more about a mentor position, someone who can guide you. For the expertise or an
opinion you can always ask/contact an expert or get the information by reading a book or publication.
And last, do not hesitate to contact experts, you will be surprise how willingly they share there expertise
with a curios student, at least I did those experiences.
My future professional path
My future goal is to be a patent attorney. I plan to start with LLM (Master) program in Technology and
Intellectual Property Law from University of Liverpool this winter.
Datum der Erstellung des Erfahrungsberichtes: August 2013
© Fachhochschule Nordwestschweiz, Studiengang Mechatronik Trinational, 2013
www.trinat.net