Biopedia

Building on our discussion of both signalling pathways and G-protein coupled receptors from a few weeks ago, this week we’re going to discuss the Wnt signalling pathway- a pathway which is crucial in aspects of development and can have widespread impacts on the cell. It all sounds rather intimidating, but there’s actually surprisingly few steps involved in this pathway- and we’re only going to be focusing on one part of the signalling network, which makes life a lot less complicated!

Sources for this episode: 1) Alberts, Johnson, Lewis, Raff, Roberts, and Walter (2008), Molecular Biology of the Cell, Fifth Edition, p.948- 950. Abingdon: Garland Science, ‘Taylor and Francis Group LLC’ 2) National Center for Biotechnology Information (2020). PubChem Compound Summary for CID 445638, Palmitoleic acid. Retrieved November 29, 2020 from https://pubchem.ncbi.nlm.nih.gov/compound/Palmitoleic-acid 3) Janda, C. Y., Waghray, D., Levin, A. M., Thomas, C. and Garcia, K. C. (2012), Structural basis of Wnt recognition by Frizzled. Science 337: 59- 63.

In the first of our ‘Rewind’ episodes, we go back to basics and discuss cells- where they came from and the famous cell theory of 1839, which is still present in textbooks today. There are more stories than we can cover which lead up to cell theory, so just see this as an introductory episode until when and if we can come back to these famous names and discoveries.

Sources for this episode: 1) Author unknown, National Geographic, date unknown, Cell Theory (Encyclopaedic entry, online). 2) Silver (1987), Virchow, the Heroic Health Model in Medicine: Health Policy by Accolade. AJPH 77(1): 82- 88 (p.86 for the discussion of Remak).

Please note: at 02:29 I mention that the postulates were ‘released’. I am not sure if this is the right word to use, but I am still looking into this, so watch this space for now.

As discussed in previous episodes, the actin cytoskeleton is vital to allow cells to move. But what about the specifics? In this episode, we’re going to be dissecting the lamellipodium- a meshwork actin structure that some cells use to move.

Sources for this episode: 1) Alberts, Johnson, Lewis, Raff, Roberts, and Walter (2008), Molecular Biology of the Cell, Fifth Edition. Abingdon: Garland Science, ‘Taylor and Francis Group LLC’ 2) ‘Mechanobiology Institute, Singapore’, 2013 (YouTube), Arp2/3 complex mediated actin nucleation (online) [Accessed 23/11/2020] 3) Berro, Michelot, Blanchoin, Kovar and Martiel (2007), Attachment Conditions Control Actin Filament Buckling and the Production of Forces. Biophysical Journal 92(7): 2546- 2558. 4) Kiuchi, Ohashi, Kurita and Mizuno (2007), Cofilin promotes stimulus-induced lamellipodium formation by generating an abundant supply of actin monomers. The Journal of Cell Biology 177(3): 465- 476.

We’re all familiar with the platypus, but it still has surprises up its sleeve. On the podcast today, we get to know its bumper-sized cousin- Obdurodon tharalkooschild.

Sources for this episode: 1) Pian, R., Archer, M. And Hand, S. J. (2013), A new, giant platypus, Obdurodon tharalkooschild, sp. nov. (Monotremata, Ornithorhynchidae), from the Riversleigh, World Heritage Area, Australia. Journal of Vertebrate Paleontology 33(6): 1255- 1259. 2)Dell’Amore, C., National Geographic (2013), Giant Platypus Found, Shakes Up Evolutionary Tree (online) [Accessed 17/11/2020, 11:36 am].

Killer whales are an icon of the world’s oceans. However, genetic studies show that they haven’t always been doing so well- especially during the last Ice Age. What’s the story? And what relevance does the millennia-old plight of the orca have today? On the podcast today, we’re going to use a genetic study from 2014 to explore just that.

Sources for this episode: 1) Moura, A. E. et al (2014), Killer Whale Nuclear Genome and mtDNA Reveal Widespread Population Bottleneck during the Last Glacial Maximum. Molecular Biology and Evolution 31(5): 1121- 1131. 2) General dates for some of the geological epochs discussed are widely available and can be found at sources such as Wikipedia.

A small housekeeping note: the lamellipodium episode is taking longer than expected and so has had to be pushed back a bit until November 25th (episode 10).

On the podcast today, we cover the concept of localised mRNA, which can be relevant to cell polarity.

Source for this episode: 1) Martin, K. C. And Ephrussi, A. (2009), mRNA Localisation: Gene Expression in the Spatial Dimension. Cell 136: 719- 730.

Antibiotic resistance we’ve all heard of by now, but what about antibiotic persistence? Join us as we explore the phenomenon of persistence, which allows bacterial infections to reappear even after antibiotic treatment. And all while being genetically identical to their susceptible neighbours!

Sources: 1) Wiley, J. M., Sherwood, L. M. and Woolverton, C. J. (2017), Prescott’s microbiology, 10th edition (International Edition), New York, McGraw-Hill Education, p.150, p.188. 2) Fisher, R. A., Gollan, B. and Helanie, S. (2017), Persistent bacterial infections and persister cells. Nature Reviews Microbiology 15: 453- 464. 3) Balaban, N. Q., Helanie, S., Lewis, K., Ackermann, M., Aldridge, B., Andersson, D. I., Brynildsen, M. P., Bumann, D., Camilli, A., Collins, J. J., Dehio, C., Fortune, S., Ghigo, J.-M., Hardt, W.-D., Harms, A., Heinemann, M., Hung, D. T., Jenal, U., Levin, B. R., Michiels, J., Storz, G., Tan, M.-W., Tenson, T., Van Melderen, L., Zinkernagel, A. (2019), Definitions and guidelines for research on antibiotic persistence. Nature Reviews 17: 441- 448. 3) Some of this discussion is also based on my prior education on the topic.

It is common knowledge that bees as a whole are declining as a result of climate change. But what about individual species? On the podcast today, we cover a 2019 paper which predicted that the Australian small carpenter bee, Ceratina australensis, might go against this trend….

Source for this episode: 1) Dew, R. N., Silva, D. P. And Rehan, S. M. (2019), Range expansion of an already widespread bee under climate change. Global Ecology and Conservation 17 (2019): e00584.

An example of the GTPase content we discussed last time. Specifically, we look at the diploid mating of baker’s yeast in stressful environments.

Source for this episode: 1) Alberts, Johnson, Lewis Raff, Roberts and Walter (2008), Molecular Biology of the Cell, Fifth Edition, p.1044. Abingdon: Garland Science, Taylor and Francis Group LLC. This episode builds on content covered in episode 3, so be sure to check it out if you haven’t listened to it already.