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TWiP 64 letters

Richard writes:

Good morning, day, evening (depending on your time of day). Esteemed professors!

Firstly my weather report, for Weston super Mare, uk.

It is currently 3 centigrade (feels like 2C), dew point 4C, humidity 78%, there has been 1mm of rain/sleet, with a 50% chance of further precipitation, and the wind is 16 km/h from the WNW. It is currently dark so no visibility, but this is estimated as 2 miles, as it is cloudy with light rain.

The predicted high for the day (2PM) 9C, with humidity of 68%, and dew point of 4C, with predicted wind of 21km/h, a 40% chance of precipitation (rain or sleet), to is expected to be partly sunny, with good visibility >10 miles predicted.

I hope the weather report meets your increasingly exacting requirements :)

My question is actually fairly simple; Giardia lamblia and a number of other eukaryotes lack mitochondria. Most of them appear to be anaerobic, and I can see the point that the mitochondria and electron transport mechanism might well be selected against.

However, no where can I find if it is clear that mitochondria where selected against, and lost. Or if these bugs are a branch, that where started before eukaryotes adopted mitochondria.

I'm not scientist, but simply an interested party. I actually work as an engineer, on sewage treatment plants. So I do get to see a lot of bacteria, since they do all the work, treating the sewage. Given plenty of oxygen, and the correct nutrients, they do a fine job of this, and then happily settle out, leaving clean enough water that it can be returned to the environment (or with minimal treatment, and filtration, to the drinking water supply, as is becoming more popular).

However it is my personal theory, that apoptosis in eukariotic cells derives from the incorporation of a once parasitic bacterium. Such a parasite requiring a method to kill the host cell, in order to proliferate into the medium, to infect other cells. I hypothesise that this was co-opted by eukaryotes, in order to allow for apoptosis (or programmed cell death).

Knowing if apoptosis odours in eukaryotes, that lack mitochondria, and if they are a pre mitochondria branch, would answer my question. However I have been unable to find the required information.

I wonder if you can point me in the right direction, and also thought the subject might lead to an interesting conversation on the podcast.

Many thanks for your ongoing series of podcasts.

I have emailed this to both TWIP, and TWIM. I suspect it is better suited to TWIM, but my research has been on parasites, since these seem better studied, so have included TWIP.

Thanks in advance for any insights you may be able to provide, or simply interesting conversation.



Dave writes:


Hiya! Entering mid-dialogue, so sorry for out-of-touch points hereafter. Trivial anyhow.

As to fuel powered machines and discovery of oil deposits (identified as refineable fuel, since deposits were mined for minor purposes in antiquity), um, as I recall, Henry Ford intended his internal combustion engines to run on ethanol at the outset. I have no idea how far earlier the engine-makers planned ethanol, but.... Anyway, Rockefeller et al came along shortly to amend all that. Besides, obviously y'all were perfectly accurate about all that machinery thing and slavery.

More to the point of parasitology, another trivial emendation may be that the first hookworms didn't necessarily enter N. America on African feet after 1600. West Africans had been transported to Caribbean islands for labor by mid 1500s. They may have inoculated soil there with hookworms, which may have been picked up by sojourning barefoot non-Africans, and transported to N. America first by those people after 1600. Maybe. (If I haven't misremembered the true mid-century. Got it from "Diary of an Irish Slave Girl," a novel about a kidnapped child who was taken to a British sugar plantation and ended up marrying an Ashanti man. Therefore my historiography may be off. But I do think those island plantations were started up in the 1550s or so -- and, from other sources, European population growth began to explode, apparently correlated with sudden availability of enough extra calories to delay starvation, preserving more children, etc.)

So anyway. Hope It's not wasted your time. Entertained me, but not enough to edit it down.


Benedict writes:

I love your show, I hear it on the way to work and home again each day. Would love to hear during work as well but my coworkers would complain I guess. I have a question regarding the theme song at the beginning of twip63. What song/remix is that?
Kind regards and all the best!

John writes:

Dear Professors,

I have listened to you discuss parasitic diseases in mice, fish, mosquitoes, ladybugs, cats, and even humans, and feel you have paid relatively little attention to squirrels. A recent paper in BMC Veterinary Research could help cure that deficiency.

British veterinarians studied 163 dead red squirrels. The squirrels were mostly found near houses and roads, and half of them were killed by cars or pets.

The dead squirrels were examined to determine cause of death and inventory parasites and other disease causing agents.

I spotted at least four eukaryotic parasites -- three Apicomplexa and a nematode -- only one of which I recall hearing about on TWiP.

Toxoplasmosis was blamed for one sixth of squirrel deaths on the Isle of Wight. It was considered a direct cause of death rather than a contributing factor like when it prevents mice from avoiding cats.

Hepatozoon infections were common in lungs and heart muscles, and Eimeria in gut contents, but neither seemed to be a primary cause of poor health.

The last parasite is so obscure it does not even have a Wikipedia page. It is related to pinworm, which you have discussed. Quoting the paper:

"Nematodes were sometimes observed during gross and histological examination of intestine. Morphologically they resembled pin worms (Enterobius sp.) but, apart from one case where they were identified as Rodentoxyuris sciuri, none were submitted for species identification. Typically there was no apparent associated pathology but one juvenile with a heavy nematode infection died due to an intestinal intussusception. However, in a second case of intussusception involving an adult there was no significant worm burden and the aetiology was obscure."

The squirrels also had viruses and bacteria, in case you want to have a squirrel week across all three "this week in" podcasts, end ectoparasites and fungus if you want to expand to five podcasts.

Suzanne writes: 

I couldn't remember being tested for Toxoplasmosis with any of my pregnancies while listening to your most recent podcast so I looked it up. According to most women aren't tested automatically these days. I didn't find any specific recommendations anywhere, though, so maybe it's something that depends on the doctor.
I do remember tests for AIDS and Hepatitis. Especially since with the most recent one the lab gave me someone else's positive Hepatitis result and missed my anemia :p
These days they just tell every pregnant woman to avoid under cooked meats and litter boxes.


PS It's cold down here in central Texas! I can translate easily from Fahrenheit to Celsius because it's been hovering just above 32F/0C for the last few days. We may even get what passes for snow around here... a few flakes mixed with the rain. I expect by next week it'll be shorts weather again, though.

Maybe that would make more sense as While listening to your most recent podcast, I couldn't remember being tested for Toxoplasmosis during any of my pregnancies...

Sam writes:

Hello TWIP! I write to you again from Tucson, where we are having quite a warm December. Today was a beautiful day, 75F, with sunshine and scattered clouds.

I was listening to Dickson explain the difference between Plasmodium vivax and P. falciparum on a historical TWIP whose number I don't recall, when later that day what should I read but the links below, reporting P. vivax infections in Duffy negative humans. The articles report that duplication of the Duffy binding genes seems to enable infection even without the Duffy receptor (per another report is expected 12/5, in just a few days).

It seems odd to me that duplicating this gene would have this effect - after all, wouldn't this be like having multiple keys to a door with no lock? It must be using a receptor of some kind, right? If it's not using Duffy, then it must be using another one - is Duffy part of a family of related receptors, or has the gene duplication produced a match for some other receptor altogether? I also wonder how this mutated parasite will fare in ordinary Duffy positive humans. I'd love it if you all could revisit this topic on the show.

On an unrelated note, I must say that the presentation of this open access paper (link below) is really great. No truncated article, clear navigation and organization, and it even includes a twitter interface. Three cheers for PLOS!

Thanks again, Victor and Dickson, for the podcast - Sam








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