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TWiV 181 Letters

Spencer writes:

I would like to propose the book:

Netter's Infectious Diseases, 1e as a listener pick of the week.

The book, filled with great explanations, is beautifully illustrated by the late Frank Netter MD, a pioneer in medical illustration. As a student, one of my classmates at Mount Sinai actually had Dr. Netter as a cadaver. Dr. Netter taught us so much in life as well as after! The sections on parasitic diseases are particularly well done.

Sincerely,

Spencer MD PhD

Richard writes:

Hi Vincent and other hosts!

I have no silly questions for you this week, but a book that I found interesting.

Germs, genes and civilisation: how epidemics shaped who we are today.

By David P Clark

Thanks again for the series of podcasts, that I enjoy learning from each week.

Regards

Richard

Andrew writes:

Good [insert appropriate distinction regarding time of day you receive this] gentlemen of TWiV,

I've been an off-and-on listener to TWiV for what must have been before 2009 in the middle of my undergraduate years. This podcast serves as an example of the power of the medium to deliver focused higher-level discussion on topics too complex to survive on traditional broadcast media but still casual enough for the non-scientist. So thank you for your excellent service to us, the listener!

The question/concern/comment I'm writing about is this: Graduate School is Scary. I graduated from a local state school with a BS in Biology in 2010, and have been out of school for just under two years. I've maintained some (probably about 5-10 hours a week) of activity in the population genetics lab I worked in prior to my graduation. Some family issues kept me tied to the area and reluctant to apply to graduate school but recently those issues have resolved themselves and now I find myself looking to take the next step. This is very frightening, and I find it difficult to proceed. How do I find what Masters or (preferably) PhD program is right for me? Am I doomed? What do I do if the program best for me doesn't think I'm best for it? It seems too late in the year to apply to anything? Most programs have closed applications by now and those that haven't have disclaimers stating that funding is usually assigned already. Should I bide my time and wait? In the mean time, I'm currently applying to the IRTA Postbaccalaureate Training Program which seems like a great program to get into in order to help bridge that gap between undergrad and PhD (and may even deserve a mention on the show: https://www.training.nih.gov/programs/postbac_irta ). Any advice on how to proceed when caught in this quagmire would be greatly appreciated and would likely help any listener also caught in the same post-undergraduate-pre-graduate morass.

Thank you, whether you read this or not, your podcast has been a huge influence on me. Please, never stop.

P.S. I forgot to actually include the field of study I'm interested in, because I meant to move it around, then forgot to reinclude it. My longstanding interest in genetics managed to fuse and include virology, and so ideally I'm most interested in virology (hence looking for TWiV's perspective) with a focus on evolution and genetics.

Jim writes:

Hi Vince,

Last November you had Science360 Radio as a TWIV pick. There are now over a hundred program links there. That provides a concentration of material you can point folks towards to more easily find what they want. I hear many podcasts from these places that are good, but some sites always stand out, like TWIP/V/M. Others periodically have great shows or a segment of a digest, and some have a huge number of past programs. So if you have an interested listener, I don't know where you send them, especially if their time is limited, such as a teacher who wants to use certain subjects.

I'm trying a blog describing selected items culled from 60 or more podcasts each week thinking it might be a way to make better podcasts easier to locate. No feedback or comment has occurred after 16 entries over four months, a short period considering the probability anyone is even looking. I now suspect blog material is read more frequently on smart phones and my efforts are too wordy for small screens, so will begin producing shorthand-type entries. It does a far better job of offering material than an alphabetized list of podcasts on my hard drive. This doesn't address all your TWI(*) efforts, especially as their numbers increase, and only a few of them are included in this blog.

Anyway, if you contact anyone to suggest an article about use of podcasts in schools, the attached list of 92 rss feeds with podcast names might be of use. In addition, this link about listening faster might be of use, too, in light of Kathy Spindler's comment about finding time to hear your episodes. The blog, Media Mining, is included should anyone have an interest in that approach. Suggested improvements are welcomed, of course, to include ditching it for some other approach.

Oh, I enjoyed your descriptions of daily activities; all time well spent!

Regards,

Jim

Smithfield, VA

Stephanie writes:

Dear Twivers,

I was a bit shocked when a listener wrote in last week and requested that you guys to avoid the subject of evolution in order to avoid offending anti-evolutionary Christians. I understand that, in order to reach the largest audience possible, it is important to be politically correct. But, is it even possible to discuss papers in the field of virology without understanding viral evolution? Why do viruses become resistant to drugs? Why does a virus tend to be less pathogenic in long term hosts? How did viruses develop so many ways to subvert host immune defenses? This is a sensitive subject to be sure, but this subject is something that just about every teacher of biology must face at one point. I look forward to hearing how you guys respond to this issue. You TWIVERs are role models for the scientists and educators that do not practice communicating science to a large, diverse audience on a weekly basis.

Horatio writes:

A brief comment on rabies: the genotype 1 rabies virus usually sustains itself in an endemic cycle in different carnivores according to geography and species composition. Bats may carry genotype 1 but are not needed as reservoirs; however they are reservoirs of the specific bat genotypes, which may cause disease in various animals and humans. Fortunately, the basic reproduction number of rabies virus is low, primarily due to the particular mode of transmission, restricted tissue tropism and long incubation time. Let's hope that the path to a putative, aerogenically transmitted virus is long and with many obstacles.

Erica writes:

Hi Team TWiV!

I just wanted to write in and let you know that you did indeed discuss miR-122 and HCV in a previous podcast as Rich suspected--it was episode 97 with my PI, Peter Sarnow. Not only is Peter a fantastic mentor, but he is a pioneer in the field of virology, and his episode on your show is one of my favorites. I highly recommend it to anyone who is interested in learning more about miR-122 and HCV.

Thanks so much for a great podcast!

Rohit writes:

I was pleasantly surprised to hear our (miR-122 & HCV) paper discussed on Twiv #180. We are really glad to know that the TWIV crew liked our study. Thanks for discussing our paper.

Currently, I am a postdoctoral fellow with Dr Benjamin tenOever in the Department of Microbiology at the Mount Sinai School of Medicine where I am trying to further develop the novel technology of use of host miRNAs to engineer a live-attenuated influenza vaccine. This technology was demonstrated earlier by Jasmine Perez in the tenOever lab [http://www.ncbi.nlm.nih.gov/pubmed/19483680].

I did my PhD with Dr Stan Lemon while he was at the University of Texas Medical Branch (UTMB) at Galveston, TX. Some of the initial experiments of the PNAS manuscript were actually carried out in the Lemon lab when we were located on the 5th floor of the Galveston National Laboratory, where you are headed sometime soon to do a TWIV episode.

I thought that I would answer some of the questions that came up during the discussion of the paper. In addition to its positive role in HCV replication, miR-122 also regulates cholesterol metabolism in liver. Knockdown of miR-122 significantly reduces serum cholesterol levels in mice as well as non-human primates. Thus, miR-122 is also an attractive drug target for cardiovascular diseases. However, certain liver cancers are associated with lower miR-122 levels suggesting that long-term knockdown of miR-122 might have some side-effects.

Location of miRNA targets in 5'UTR by itself is not enough to change a miRNA from a "repressor" to an "activator" of gene expression as there are examples where miRNA targets located in 5'-UTR of mRNAs down-regulate gene expression. Thus, miR-122 effect on HCV 5'-UTR seems to be unique so far. However, there must be other such examples out there that are yet to discovered.

Allan was right in pointing out that RISC, as the name RNA-Induced Silencing Complex suggests, is a complex of multiple types of proteins. Argonautes are the central and canonical components of RISC. There are 4 argonaute proteins in the human genome, argonaute 1-4. Ago-2 is the best studied one and is the only argonaute with a slicer/endonuclease activity that is used to cleave the target mRNA when there is perfect complementarity between miRNA/siRNA and its target.

Thanks

Rohit

Stephen writes:

I'm a new subscriber to TWIV, and just began with #180. Richard Condit's comments on polydnaviruses and wasps was fascinating, and I will follow up on that.

A few comments:

1. Broken link: "Viral and wasp genes involved in symbiotic replication (J Virol)" http://www.ncbi.nlm.nih.gov/pubmed/22238295

2. braconid wasps are parasitoids, not parasites. Parasitoids kill the host.

3. The layers of complexity involving parasitoid wasps are sometimes even deeper. Here's a photo I took by accident while shooting some grasshoppers (Nisquallia olympica http://onh.eugraph.com/insects/orthop/nolympica) I casually study in the Olympic mountains. I've appended a comment from bugguide.net, to which I contributed a crop of this photo.

Brachymeria tegularis…

These are hyperparasitoids of common grasshoppers (through sarcophid and tachinid flies). More commonly found in western states. Great find.

See reference here.

… Ross Hill, 12 September, 2011 - 4:32pm

http://bugguide.net/node/view/575501

So the flies parasitize (or parasitoidize) grasshoppers, then Chalcidid wasps lay an egg on the grasshopper. The larva of the wasp then finds the larva of the fly and parasitoidizes it.

I have to wonder how much of a role viral genes play in all of this.

 

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