Björn Brembs

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Positive controls in joystick optogenetics

on Tuesday, March 31st, 2020 7:40

I’ve started rescreening Christian’s most consistent dopaminergic lines with the positive controls at the joystick machine, to see if everything works. These flies express the optogenetic channel Chrimson in Gr28bd and TrpA1 heat sensitive neurons, so they should use the joystick to switch the light off.

I tested three rounds of three flies each and I got the impression that it worked while I was looking at the flies. The data didn’t look that great, however:

Experimental time course of positive control flies. PIs (Y-axis) should be mostly negative.

Setting up the experiments, I noticed that the middle setup didn’t really focus the light on the head of the fly very well. This shows in the raw performance index data:

The two middle flies (row #2 and #8) have positive preferences, but never avoid the light, while nearly all other flies do avoid the light to various extents, even if they start out with a positive preference. So I deleted these two flies to see how the data would look then:

As above, only this time with the training periods averaged at the end (“Means”).

I decided that this should be good enough. I improved the middle setup to focus the light better on the fly’s head. Hopefully it will improve the PIs of the flies placed there now.

Come work with us on FoxP!

on Wednesday, December 19th, 2018 2:52

We are looking for a PhD student for behavioral experiments with Drosophila fruit flies with manipulated FoxP function.

The human orthologues of the fly FoxP gene are the FOXP1-4 genes. Mutations in the FOXP2 gene cause verbal dyspraxia, a form of articulation impairment. Humans learn to articulate phonemes and words by a form of motor learning we can model in flies. Supporting the conceptual analogy of motor learning in humans and flies, manipulations of the fly FoxP gene also lead to impairments in motor learning.

FoxP isoform B expression pattern in the adult brain (green). Counterstaining: Bruchpilot (red)

In the past year, graduate student Ottavia Palazzo used CRISPR/Cas9 to edit the FoxP gene locus, tagging the gene with reporters. These reporters allow us to manipulate not only the gene, but also the neurons which express FoxP. The candidate will work closely with Ottavia to design behavioral experiments characterizing the various manipulations of the different neuronal populations for their involvement in the form of motor learning we use, operant self-learning at the torque meter:

The position is fully funded by a grant from the German funding agency DFG, with full healthcare, unemployment, etc. benefits. It includes admission and tuition to the “Regensburg International Graduate School of Life Sciences“. Starting date is as soon as convenient.

The successful candidate will have a Master’s degree or equivalent. They will be proficient in English as our group is composed of international members. The ideal candidate will have some training in behavioral experiments in Drosophila or other animals, some coding experience and an inclination towards electronics. However, all of these skills can also be learned during the project.

We are a small, international  group consisting of a PI (Björn Brembs), a postdoc (Anders Eriksson), one more graduate student besides Ottavia (Christian Rohrsen) and a technician. We are an open science laboratory and so one aspect of the project will involve a new open science initiative in our laboratory, where we have developed a simple method to make our behavioral data openly accessible automatically, i.e., without any additional efforts by the experimenter. This entails at least two advantages for the candidate in addition to doing science right: the data are automatically backed up and there is no need for a data management plan.

Regensburg is a university town in Bavaria, Germany with about 120k inhabitants and a vibrant student life, due to the 20k students enrolled here. The University of Regensburg is an equal opportunity employer.

Interested candidates should contact Björn Brembs with a CV and a brief letter of motivation.

Good bye Lena, welcome Weitian!

on Tuesday, October 25th, 2016 6:53

Lena Matzeder just finished her Bachelor thesis, entitled “Is anxiety a factor influencing photo-preference in Drosophila melanogaster?“. She administered Diazepam (valium) to flies and asked them if that changed their preference for bright or dark places. A warm welcome to Weitian Sun, a Master’s student who will be testing candidate genes for their involvement in operant self-learning.

Good luck Christian

on Friday, April 29th, 2016 10:25

Our graduate student, Christian Rohrsen, was so fortunate to receive grant funding for a six-month research stay in the laboratory of Benjamin de Bivort at Harvard University. All of us here are very excited at this opportunity and are wishing him all the best of luck with his projects there!

With all our undergraduate students graduating and our graduate student on research leave, the lab has now shrunk to two people plus our technician. Looks like it’s going to be lonely for a while.

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Good bye Isabelle and Bianca


I just received the Bachelor theses from Isabelle Steymans and Bianca Birk. Both have worked tirelessly and diligently on their respective projects, but with very different outcomes. While both outcomes are very useful, one managed to answer a scientific question, while the other showed that the method we tried did not work. Research often is this unfair, with discovery acting more like a capricious belladonna than even a lottery. Research results are, of course, impossible to predict, so the difference in outcome will not affect their grades.

We are very happy with the work of these two students, we enjoyed their time with us and hope they also enjoyed their research here in our lab. All the best to you two!

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Good bye Katrin and Amelie

on Thursday, March 24th, 2016 10:55

Two students have recently left our lab, Katrin Hofweber and Amelie Rödel. Katrin was a master’s student working on the role of dopaminergic neurons in reward/punishment using optogenetics. Amelie’s task was to find out what, if any, temperature had on the photopreference of flies. She summarized her work in her Bachelor thesis entitled “Temperature impact on phototactic preference in Drosophila melanogaster

Farewell you two, we enjoyed having you in the lab and will always be happy seeing you again. Good luck and all the best!

Category: Lab | 1 Comment

Good bye Pablo!

on Friday, March 4th, 2016 5:00

After more than four months in our lab, we said good bye to Pablo Martinez (between Axel and Christian in the picture below).

2016-02-26 20.23.54He worked tirelessly to collect data on spontaneous flight behavior using strokelitude. We have enjoyed his visit tremendously and wish him all the best in his future research endeavors. Many thanks, Pablo!

The next students to leave the lab will be Amelie Roedel, Isabelle Steymans and Bianca Birk, who are writing up their theses right now.

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Reminder: use safe passwords

on Sunday, January 25th, 2015 1:17

I’ve spent all morning deleting and re-installing major portions of the system running this site. Please do keep in mind that it is important to only use safe passwords on this site! clean again

on Friday, June 21st, 2013 8:30

I have now cleaned the site from all malicious code and installed a few new plug-ins which I still need to properly adjust all settings. The site should now almost be back to normal, please resume posting your data and let me know if there is anything that still needs fixing!

Mine is bigger than yours!

on Thursday, November 29th, 2012 6:36

My camera is bigger than Julien’s :mrgreen: I realized that the camera I had been using to track the laser position in my flight simulator didn’t quite fit with the way everything is arranged now. I remembered I had seen an old camera in the basement, so I went there to check it out. It worked really well and it provides a fantastic picture of the fly. It’s just that it is now the largest piece of the equipment: