Here’s an interesting NPR piece on hagfish slime (http://www.theworld.org/2013/03/hagfish-clothes/). Scientists have been looking for strong yet lightweight fibers, preferably from a renewable source. For example see my post about spider silk.
Too busy for a longer post today. Don’t forget to circle ScienceSunday if you haven’t already. Mention the curators, Rajini Rao Allison Sekuler Buddhini Samarasinghe Robby Bowles and me, so that your #ScienceSunday post doesn’t get lost in never-never-land.
Erin Kane’s post Convergent Evolution: how cool is that? (http://goo.gl/47I1C) reminded me that hyena females are dominant, e.g., alfa females. Erin’s post also reminded me of our collaboration on work similar to the video.
OK, back to hyenas and hormones. Spotted hyena females release androgen to their offspring, which makes them more aggressive (think about what you’ve read about athletes using anabolic steroids). This added aggression is important to improve their chance of getting a meal, and therefore survive. It also makes the males more sexually active, early on. This is important as they need practice, to deal with the complicated copulation of hyenas. Female hyenas, especially the spotted hyena, have a pseudo-phallus due to the androgen that they received from their mother, i.e., the clitoris is enlarged. You can read more here: http://goo.gl/g6DA6
Brains: Another interesting fact about the spotted hyena is that they have a larger brain volume when compared to the striped hyena, brown hyena, and aardwolves. The spotted hyena also possesses a larger anterior cerebrum volume relative to total brain volume than is found in the other hyena species; this region is composed primarily of frontal cortex. These data are consistent with the idea that expansion of the frontal cortex is driven by the demands of processing cognitive information associated with complex social lives, but other factors may drive the evolution of large brains in hyaenids.
Brain size and social complexity: a computed tomography study in Hyaenidae.
Sakai ST, Arsznov BM, Lundrigan BL, Holekamp KE.
Brain Behav Evol. 2011;77(2):91-104. doi: 10.1159/000323849. Epub 2011 Feb 17.
Symbiotic relations: One more science tidbit, bacteria have a symbiotic relationship with hyenas. The diversity in the bacteria can aid hyenas in identifying members of the same social group based on how the structure of the bacteria affects the odor of the hyena’s scent gland.
Evidence for a bacterial mechanism for group-specific social odors among hyenas.
Theis KR, Schmidt TM, Holekamp KE.
Sci Rep. 2012;2:615. doi: 10.1038/srep00615. Epub 2012 Aug 30.
Prosopagnosia, or Face Blindness, is a largely unrecognized disorder. (Yes, yes, I know…) Various estimates hold that between 2% and 10% of the population exhibit some degree of this inability to recognize familiar faces, yet few people have even heard of it, and as a result many sufferers are hesitant to even mention they have difficulty for fear of embarrassment or discrimination.
Dr. Sarah Bate of the Centre for Face Processing Disorders at Bournemouth University is leading a campaign to raise greater awareness of Prosopagnosia in the U.K. House of Commons. She has an online petition available through www.prosopagnosiaresearch.org which I highly encourage U.K. readers to go sign. The attached article has further information.
For U.S. readers who wish to know more about prosopagnosia, the Prosopagnosia Research Centers at Dartmouth College, Harvard University, and University College London have excellent information at www.faceblind.org including their biannual Face to Face newsletter.
As a prosopagnosic myself, I am always interested in the current state of research and I hope to enlighten others about this condition. So many people don’t even know this disorder exists, even those suffering from it in many cases. Greater awareness can help out both by increasing research and reducing any perceived stigma in admitting to having prosopagnosia.
The first figure below is from:
The anatomic basis of the right face-selective N170 IN acquired prosopagnosia: A combined ERP/fMRI study
fMRI and ERP were used to gain insight into a region of the brain associated with the acquired form of prosopagnosia. Event-related potentials (ERP) are measured with electroencephalography (EEG). http://en.wikipedia.org/wiki/Event-related_potential
ScienceSunday co-curator Chad Haney has posted about fMRI frequently, and most recently here: http://goo.gl/xhc6T
An interesting point of the first figure is that the location of the lesion isn’t necessarily where the investigators are looking in terms of the functional image and as mention by Chad before, the figure demonstrates the variability in BOLD MRI (fMRI).
The remaining three figures are from
Congenital prosopagnosia: multistage anatomical and functional deficits in face processing circuitry.
V Dinkelacker et al
J Neurol. 2011 May;258(5):770-82. doi: 10.1007/s00415-010-5828-5. Epub 2010 Dec 1.
The interesting finding there is that facial recognition is not as impaired when it comes to negative faces. The images also show that unlike the first study linked here, the congenital prosopagnosia patients lack any lesion. They hypothesize that congenital prosopagnosia is due to a network dysfunction and that the lingual gyrus plays a substantial role. The lingual gyrus has to do with visual processing, especially letters. The name is due to its physical apperance as it looks like a tongue. It is not associated with speech.
Happy birthday Rajini Rao have a #punderstorm day, especially #ScienceEveryday with the #Incorrigibles.
#Wolverine2WonderWomanHappyBD
Originally shared by Buddhini Samarasinghe
Interfering with RNA
A birthday tribute to someone I really admire here on G+, who is an amazing mentor and friend. Happy Birthday Rajini Rao, hope you have a wonderful year ahead and it’s been a pleasure knowing and working with you on our many projects together on G+!
A few days ago during our ENCODE Hangout on Air (http://goo.gl/H6KDE), I mentioned microRNAs. I wanted to write a post today about the general mechanism of how a gene can be ‘silenced’ through a process known as RNA interference.
• As we explained during the Hangout, the Central Dogma of Molecular Biology is DNA –> RNA –> Protein. This means the DNA blueprint makes a sequence-specific copy of RNA, which in turn acts as a blueprint for a specific sequence of amino acids which make up a protein.
• So imagine if you could somehow destroy the RNA blueprint (known as the messenger RNA, or mRNA) for a particular protein. This would prevent the protein from being made – no blueprint, no protein. This is what RNA interference, or gene silencing is.
• It was first observed by plant scientists working on petunias in 1990. They were trying to make the color of the flower darker, so they introduced extra copies of the gene chalcone synthase, a key enzyme involved in the synthesis of pink and violet flower pigment (http://goo.gl/2A0Wk). Their logic makes sense – adding more copies of the gene for chalcone synthase should make more protein, which in turn should make flowers darker. But when they did the experiment, instead of darker flowers they got lighter flowers, or fully or partially white flowers absent of any color (see image below). Clearly, introducing extra copies of the chalcone synthase gene was decreasing the activity of chalcone synthase.
• Similar phenomena were reported in fungi, and also in plant viruses. However, it was not until 1998 when Andrew Fire and Craig Mello formally identified the process as ‘RNA interference’ in their groundbreaking work on the nematode worm Caenorhabditis elegans (http://goo.gl/XYId1). They injected sequence specific double-stranded DNA into the worm and then observed the silencing of the target gene (the mRNA blueprint went missing, and therefore so did the protein). This was the first time that double-stranded DNA was identified as the causative agent for the gene silencing phenomenon.
• The discovery completely revolutionized biology; Fire and Mello were awarded the Nobel Prize just eight short years after the publication of their work, which is very unusual (usually Nobel-prizes recognize work that is several decades old!). The work was so important because now we could silence any gene to see the effect it would have on the organism.
• Why is this important? Imagine you have a car, and you want to learn the function of the different parts. If you remove (or silence!) a wheel, the car cannot move. Therefore you can conclude that the wheel is necessary for motion. The same could be done within the organism; silence a gene, and you notice that the animal is now impaired in movement, so you can conclude that the gene may be involved in muscle development or coordination. Silence another gene, and you notice the eggs look strange, and you conclude that the gene was involved in egg development. RNA interference allowed scientists to assign a function to a gene; this has been and will remain an invaluable tool in molecular biology for decades ahead.
All the original research papers I’ve cited above are #openaccess
