Recent comments in /f/askscience

OryuSatellite OP t1_jcq6umw wrote

Reply to comment by h3rbi74 in How does immunity to larger internal parasites such as worms work? by OryuSatellite

My vet does describe it as immunity, for what it's worth, and my understanding is that adults with "immunity" are expected to have relatively low parasite load, not only higher tolerance of parasite load. But certainly it only means relative immunity, not absolute immunity. Immune response that attacks eggs and freshly hatched parasites as the previous answer described (and as in the very cool video) seems to make sense.

ETA: I also have farm cats, and the cats get wormed every three months without fail for their whole lives (on advice of the same vet) so no expectation of immunity there. But I don't think it's economics of pets versus farm animals that is the reason for the difference, although avoidance of anthelmintic resistance is certainly a factor for the sheep.

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Greyswandir t1_jcq5ask wrote

Reply to comment by GulliblePlantain6572 in What decides which wavelength to reflect and which one to be absorbed in an object? by TheSimpleHumans

Key distinction: the color of something is based on the spectrum of light (how much light at each wavelength in the visible range) reaches our eye. Absorption is a big part in that, but it’s not all of it. For example: an apple won’t appear red if the light illuminating it doesn’t include any red light since there’s no red light there to reach our eyes. And there are plenty of situations where optical effects other than absorption are dominant. A great practical example is the Lycurgus Cup. It’s a glass cup full of gold nano particles. When light shines through it, absorption dominates and so only red light passes through and it appears red. When light shines on it, scattering dominates, and those same particles scatter green light, but not red or blue, so it appears green since the scattered green light is reaching our eye.

Also, up until now we’ve been talking about the light itself. How we perceive that light and turn it into our sense of color is a whole other part of this. Very simplified explanation but: our eyes contain two types of light sensitive cells, rods and cones. Rods are great in low light conditions but can only see black and white. Cones are less sensitive to light, but they come in three variants, red, blue, and green. Red cones most strongly absorb red light, blue cones most strongly absorb blue and green absorbs green. When a cone absorbs light, it sends a signal to our brain. Based on how many of the RGB cones are triggered our brain mixes those signals together to form a perceived color. So complimentary colors have to do with how our eye and brain perceive colors. I don’t think there’s anything inherent to the photons that makes, say, blue the complement of red. It’s the way our sense of color works that makes those have high contrast.

Emission specta (or scattering spectra, or transmission spectra, etc) are basically the same yeah. You read the wavelength (or frequency) of light along the x axis and the y value tells you how much is emitted/scattered etc for that wavelength. It’s been a while but I think for an emission spectrum you need to specify the conditions under which the object is emitting.

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h3rbi74 t1_jcq4wsa wrote

Reply to comment by OryuSatellite in How does immunity to larger internal parasites such as worms work? by OryuSatellite

I think it’s not that the adults are immune to worms, it’s that they have the capacity to carry a small to moderate parasite load without severe health effects, which is not the case for tiny babies. Economics of farming says treat the babies but leave the adults be.

(Also it really depends on which worms you’re talking about, because they each have different life cycles, but in some there is no way to truly eliminate them. I’m a vet tech but haven’t worked with sheep since undergrad so would need to brush up on them, but in adult dogs for example, common roundworms migrate out of the intestines and encyst themselves in a dormant state, then can be activated later by certain triggers, including pregnancy. I’ve been taught that 99% of puppies have roundworms, even if the mother had a negative fecal test. So we routinely aggressively deworm all puppies, and then treat adults on an as-needed case-by-case basis. https://www.merckmanuals.com/home/multimedia/image/life-cycle-of-the-toxocara-roundworm )

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iayork t1_jcq2plo wrote

Reply to How do scientists know the racoon dog was the most likely vector for the COVID-19 zoonotic transfer to humans? by AgaricX

A very early genomic sequence of SARS-CoV-2 was posted by Chinese researchers, then removed (probably because of Chinese government pressure). However, a few western researchers grabbed the sequence before it was removed and analyzed it. As well as viral sequence, the sample had raccoon dog DNA sequences associated with it (as contaminants), implying that this extremely early virus sample came from raccoon dogs. It’s known that raccoon dogs were kept in the wet market that’s been implicated in very early COVID19 transmission, and raccoon dogs are highly susceptible to infection with SARS-CoV-2, so it’s a consistent story.

It’s unfortunate that the Chinese government are obviously trying to suppress this, because if they’d simply make available the info about this there would be less space for the silly conspiracy theories.

Here’s the WHO statement, which explains a little more and shows the level of frustration they have with the Chinese government: SAGO statement on newly released SARS-CoV-2 metagenomics data from China CDC on GISAID

> …samples collected from the environment and animals within the market in early 2020, 73/923 environmental samples tested positive for SARS-CoV-2-specific RT-qPCR, from various stalls and sewerage systems in and around the market … the presence of high levels of raccoon dog mitochondrial DNA in the metagenomics data from environmental samples identified in the new analysis, suggest that raccoon dog and other animals may have been present before the market was cleaned as part of the public health intervention…

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Broad-Turnover6945 t1_jcpneds wrote

Reply to comment by [deleted] in How does the body excrete bacteria and infections? by leinard97

Most toxic drugs and alcohol are processed in the liver via a system called the Cytochrome C450 (CYP) system. It’s an enzyme, Most common is CYP is 450 but there’s many types. Certain drugs alter the metabolism or speed of CYP enzymes, thus increasing or decreasing the metabolism of said drug, thus altering its pharmacology

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OryuSatellite OP t1_jcpgkdw wrote

Reply to comment by zumiaq in How does immunity to larger internal parasites such as worms work? by OryuSatellite

Thank you, that's helpful! To clarify, usual practice with the sheep is to worm lambs a bit after they start grazing substantially, to hit the initial worm exposure, but then expect that after that they will have a good start on developing immunity and as adults will usually not need worming unless they are having some other kind of health challenge. That seems to fit your explanation, I think.

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