Beer spoiling bacteria, oh no! But we know now how you’re made, suckers!

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Over 250 years ago today, on 31 December 1759, Arthur Guinness started brewing one of the most loved adult drinks today, the Guinness beer.

As with all food and drink products, beer can be also suffer spoiling due to various bacteria. The genomes of two of these culprits – Megasphaera cerevisiae PAT 1T and Lactobacillus brevis BSO 464 – have been sequenced in 2015 by two different groups.

Funny thing though: the papers that announce the completion of the genome sequencing (see bellow References) do not talk abut the significance of their discovery. The usual template for a biology paper (or as a matter of fact any science paper) is:

Introduction: x is important because y,
Methods and Results: here is what we did to understand x,
Conclusion: now we can better tackle y.

Not these papers, which basically say, in less than a page: “This bacterium spoils beer; here is its genome. You’re welcome!”

Well played, geneticists, well played… And we are, indeed, grateful. Oh, yes, we are…

References:

1. Kutumbaka KK, Pasmowitz J, Mategko J, Reyes D, Friedrich A, Han S, Martens-Habbena W, Neal-McKinney J, Janagama HK, & Nadala C, Samadpour M (10 Sep 2015). Draft Genome Sequence of the Beer Spoilage Bacterium Megasphaera cerevisiae Strain PAT 1T. Genome Announcements, 3(5). pii: e01045-15. doi: 10.1128/genomeA.01045-15. Article | FREE Fulltext PDF | FREE GENOME

2. Bergsveinson J, Pittet V, Ewen E, Baecker N, & Ziola B (3 Dec 2015). Genome Sequence of Rapid Beer-Spoiling Isolate Lactobacillus brevis BSO 464. Genome Announcements, 3(6). pii: e01411-15. doi: 10.1128/genomeA.01411-15. Article | FREE Fulltext PDF | FREE GENOME

By Neuronicus, 31 December 2015

Pic of the day: Galileo Galilei

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Over four hundred years ago, on December 28, 1612, Galileo was the first person to observe the planet Neptune.

Read the Galileo quote in Leonard Nimoy’s voice. Fans of Civilization V are familiar with his voice saying this quote when the Scientific Method is discovered in the game.

Prostaglandins in the sickness syndrome

63woman-698962_960_720When you’re sick you also feel awful: no appetite, weak, sleepy, feverish, achy, and so on. This is called, appropriately so, the sickness syndrome.

Saper, Romanovsky & Scammell (2012) wrote a beautiful review of the neural circuits underlying this collection of symptoms. In a nutshell, the immune system releases cytokines to fight the inflammation, which in turn stimulate the release of prostaglandins. Prostaglandins bind to various areas in the brain to produce the sickness syndrome symptoms. Below are outlined four simplified brain circuits which the non-specialists can skip entirely.

  1. Prostaglandins in the median preoptic nucleus lead to a cascade involving dorsomedial hypothalamus, rostral medullary raphe and finally the spinal cord to produce fever by activating the brown adipose tissue.
  2. Prostaglandins in the preoptic area lead to the inhibition of the brain’s analgesic system involving the descending projections of the periaqueductal grey to spinal cord, thus promoting achiness.
  3. Prostaglandins in the meninges result in adenosine release in nucleus accumbens and ventrolateral preoptic nucleus which, downstream, end in inhibiting the arousal system to produce sleepiness.
  4. Prostaglandins in the arcuate nucleus lead to inhibition of several hypothalamic nuclei involved in promoting feeding, thereby producing anorexia.

The sickness syndrome and the role prostaglandins play in it has tremendous adaptive role, as it promotes rest and recuperation. So don’t blame them too much. And if you’re really done feeling sick, take some non-steroid anti-inflammatory drugs, like aspirin, which inhibit the prostaglandins’ synthesis very effectively. That’s how and why NSAIDs work.

Reference: Saper CB, Romanovsky AA & Scammell TE (26 Jul 2012). Neural Circuitry Engaged by Prostaglandins during the Sickness Syndrome. Nature Neuroscience, 15(8):1088-95. doi: 10.1038/nn.3159. Article | FREE Fulltext PDF

By Neuronicus, 21 December 2015

The FIRSTS: Betz pyramidal neurons (1874)

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Betz cell in the dog cortex. Copyright: RA Bergman, AK Afifi, PM Heidger, & MP D’Alessandro. Pic taken from here.

Bigger that Purkinje cerebellar neurons, the Betz pyramidal neurons (aka the giant pyramidal neurons) can have up to 100 micrometers in diameter. They are located in the fifth layer of the grey matter in the primary motor cortex. And they were discovered by a Ukrainian who did not receive the just place he deserves in the history of neuroscience, as most books on the subject ignore him. So let’s give him some attention.

Vladimir Alekseyevich Betz (1834–1894) was a professor of anatomy and a histologist at the Kiev University. Just like with Pavlov, sometimes there is nothing spectacular or weird or bizarre in the life of a great thinker. Betz was a child of a relatively wealthy family, went to good schools, then to Medical School, where he showed interest in the anatomy department. He continued his postgraduate studies in the West (that is Germany and Austria) after which he returned home where he got a position as a professor at his Alma Mater where he stayed until he died of heart problems at the age of 60.

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Vladimir Alekseyevich Betz (1834 – 1894), License: PD

During his PhD, which was on the blood flow in the liver, Betz discovered an interest in histology. He was unsatisfied with the quality of the existing staining methods, so he worked for years to improve the fixation and staining methods of the brain tissue. His new methods allowed the cutting and preserving very thin slices and then he described what he saw. But Betz’s genius was in linking his cortical cytoarchitechtonic findings with physiological function, dividing the cortex into the motor and sensory areas. He also made revolutionary observations of the anatomical organization and development and various pathologies.

Original reference (which I did not find): Betz W (1874). Anatomischer Nachweis zweier Gehirncentra. Centralblatt für die medizinischen Wissenschaften. 12:578-580, 595-599.

Reference: Kushchayev SV, Moskalenko VF, Wiener PC, Tsymbaliuk VI, Cherkasov VG, Dzyavulska IV, Kovalchuk OI, Sonntag VK, Spetzler RF, & Preul MC (Jan 2012, Epub 10 Nov 2011). The discovery of the pyramidal neurons: Vladimir Betz and a new era of neuroscience. Brain, 135(Pt 1):285-300. doi: 10.1093/brain/awr276.  ArticleFREE FULLTEXT PDF

By Neuronicus, 17 December 2015

Vagus nerve stimulation improves recovery after stroke

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Vagus nerve stimulation by a wireless device implanted subcutaneously. License: PD. Credit: NIH/NIMH

A stroke is a serious medical condition that is characterized by the death of brain cells following bleeding in the brain or lack of blood supply to those cells. Three quarters of the survivors have weakness in the arm which can be permanent. Physical therapy helps, but not much.

Dawson et al. (2015) report a novel way to increase arm mobility after stroke. Previous findings in animal studies showed promising results by stimulating the vagus nerve (VNS). This nerve is the tenth out of the twelve cranial nerves and has many functions, primarily heart and digestive control. The authors implanted a small wireless device in the neck of nine stroke survivors and delivered very short (half a second) mild (0.8 mA) electrical pulses during rehabilitation therapy. Ten matched controls received rehab therapy only.

The authors measured motor recovery by several tests, one of which is Fugl–Meyer assessment-UE. At this test, the rehab only group improved by 3 points and the VNS + rehab group by about 9 points and this difference was statistically significant (I believe this scale’s upper limit is 66, but I’m not 100% sure).

Although the authors offer a possible mechanism through which VNS might produce cortical plasticity (through release of acetylcholine and norepinephrine driven by activation of nucleus tractus solitarius) the truth is that we don’t really know how it works. Nevertheless, it seems that VNS paired with rehab is better than rehab alone, and that in itself certainly warrants further studies, perhaps the next step being a fully double-blind experiment.

Reference: Dawson J, Pierce D, Dixit A, Kimberley TJ, Robertson M, Tarver B, Hilmi O, McLean J, Forbes K, Kilgard MP, Rennaker RL, Cramer SC, Walters M, & Engineer N. (Epub 8 Dec 2015). Safety, Feasibility, and Efficacy of Vagus Nerve Stimulation Paired With Upper-Limb Rehabilitation After Ischemic Stroke. Stroke. 2016; 47:00-00. DOI: 10.1161/STROKEAHA.115.010477. Article | FREE FULLTEXT PDF

By Neuronicus, 11 December 2015