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Biology What, biologically, is a cat?

Negentropic said:
Can anyone here fundamentally prove that I myself am not a cat?
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1. You engage with humans for reasons other than food or laser pointers.
2. You engage often enough that I seriously doubt that you sleep 23hrs per day.

Now if you can fall backwards from 3 stories high and always land on your feet, unhurt, then maybe we can talk about your possible cathood.
 
Las Veghost grower said:
True, gotta wonder if our cats are just nice to us cause they know they can’t kick our ass, cause there are times I look into my brothers cats eyes and see him thinking about if he can take me
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Ever seen those videos of canuck dummies taking in wild lynx?
 
Skorpio said:
It's only a problem when the chimps come off the xan.
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b63KUIO.png
 
Fire&Water said:
Which ones before
or after?
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The dark part is they used the chimp for the transplant in a cruel act of revenge.


Ummm, cats (not the Andrew Lloyd Weber jawn)


Is a cell line derived from a cat, a cat?

Are cat stem cells that can be genetically programmed to express human proteins still cat cells?

Is a kitten a cat?
 
Skorpio said:
Is a cell line derived from a cat, a cat?
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this reminds me of the immortal life of henrietta lacks (a MUST read for anyone interested in where ethics meets science via totally fucking up and racism). her family had a very poor comprehension of what HeLa cells actually were because no one bothered to educate them on their mothers immense contribution to science and came across as thinking that somehow those cells were, in some way, her.

but i'm gonna go no.
Skorpio said:
Are cat stem cells that can be genetically programmed to express human proteins still cat cells?
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i'd go no for this one too but i'd be interested to know how this is done if you have any info.
 
chinup said:
i'd go no for this one too but i'd be interested to know how this is done if you have any info.
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I should probably clarify that this is usually done only for a gene or two at a time and is quite labor intensive.

First you use CRISPR to target the original gene, causing a cut which then gets improperly repaired. You screen a bunch of edited cell populations for something where the repair causes an insertion or deletion of nucleotides in the gene that disrupts the translation to amino acids (as amino acids are encoded by patterns of 3 nucleotides at a time, adding or subtracting a number non-divisible by 3 will change the identity of all of the amino acids downstream of the edit). If there is a protein produced after this edit, it will be scrambled and broken down quickly.

To put a gene back into a cell line you use lentiviral transduction to incorporate it into the genome. Lentiviruses are viruses like HIV that use a reverse transcriptase to edit your genome directly. The ones used as genetic tools lack the ability to replicate, and contain a payload of DNA that you want to encode into the cell lines. Usually the plasmids for lentiviruses encode a resistence gene for a cytotoxic drug such as puromycin (inhibits eukaryotic protein translation), so that when you grow the cells in puro, only those that are expressing the lentiviral DNA will survive (also this keeps the cell line from eventually kicking out the viral DNA).

Expressing an orthologous gene from other species is a common technique for validating function. If you can demonstrate an effect from knocking out a gene, and then reverse the effect by adding back in the gene from a different species (usually will be slightly different), you have grounds to make a claim on the function of the gene product.
 
Skorpio said:
I should probably clarify that this is usually done only for a gene or two at a time and is quite labor intensive.

First you use CRISPR to target the original gene, causing a cut which then gets improperly repaired. You screen a bunch of edited cell populations for something where the repair causes an insertion or deletion of nucleotides in the gene that disrupts the translation to amino acids (as amino acids are encoded by patterns of 3 nucleotides at a time, adding or subtracting a number non-divisible by 3 will change the identity of all of the amino acids downstream of the edit). If there is a protein produced after this edit, it will be scrambled and broken down quickly.

To put a gene back into a cell line you use lentiviral transduction to incorporate it into the genome. Lentiviruses are viruses like HIV that use a reverse transcriptase to edit your genome directly. The ones used as genetic tools lack the ability to replicate, and contain a payload of DNA that you want to encode into the cell lines. Usually the plasmids for lentiviruses encode a resistence gene for a cytotoxic drug such as puromycin (inhibits eukaryotic protein translation), so that when you grow the cells in puro, only those that are expressing the lentiviral DNA will survive (also this keeps the cell line from eventually kicking out the viral DNA).

Expressing an orthologous gene from other species is a common technique for validating function. If you can demonstrate an effect from knocking out a gene, and then reverse the effect by adding back in the gene from a different species (usually will be slightly different), you have grounds to make a claim on the function of the gene product.
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Oh and to do it on stem cells, you just have to use really fancy media to grow them that has a lot of growth factors and drugs in it to keep the stem cells from differentiating.

Unfortunately one of the factors (FGF2) is unstable at 37C, so the expensive media needs to be changed daily or you will see the beautiful stem cell line you are working on begin turning into fibroblast or muscle looking cells. This differentiation can also occur from letting the cells grow too dense before splitting them. It also happens if you look at them wrong honestly, stem cells seriously need to be coddled.
 
Skorpio said:
I should probably clarify that this is usually done only for a gene or two at a time and is quite labor intensive.
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ahhhhh ok that makes more sense.

Skorpio said:
First you use CRISPR to target the original gene, causing a cut which then gets improperly repaired. You screen a bunch of edited cell populations for something where the repair causes an insertion or deletion of nucleotides in the gene that disrupts the translation to amino acids (as amino acids are encoded by patterns of 3 nucleotides at a time, adding or subtracting a number non-divisible by 3 will change the identity of all of the amino acids downstream of the edit). If there is a protein produced after this edit, it will be scrambled and broken down quickly.

To put a gene back into a cell line you use lentiviral transduction to incorporate it into the genome. Lentiviruses are viruses like HIV that use a reverse transcriptase to edit your genome directly. The ones used as genetic tools lack the ability to replicate, and contain a payload of DNA that you want to encode into the cell lines. Usually the plasmids for lentiviruses encode a resistence gene for a cytotoxic drug such as puromycin (inhibits eukaryotic protein translation), so that when you grow the cells in puro, only those that are expressing the lentiviral DNA will survive (also this keeps the cell line from eventually kicking out the viral DNA).
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thank you for explaining so clearly.

i'm a bit confused though, where do the plasmids come in? in my head they only exist for bacteria (or, i've only worked on them for bacteria) and i've only really come across them when trying to work out how to differentiate between things like strains of e. coli so i'm basically in a place of total ignorance. in this context are they just the packaging for the genetic material?


Skorpio said:
Expressing an orthologous gene from other species is a common technique for validating function. If you can demonstrate an effect from knocking out a gene, and then reverse the effect by adding back in the gene from a different species (usually will be slightly different), you have grounds to make a claim on the function of the gene product.
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i think i've actually heard of this. i know biology!! woohoo!!
 
chinup said:
Where do plasmids come in?
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Plasmids are the key vehicle for storing and manipulating genes in molecular biology. They are much more stable than linear DNA, and can be inserted into E. coli to replicate them. Plasmids contain genes for antibiotic resistence (to select for bacteria containing the plasmid and kill the rest). This allows for amplification of plasmid DNA for downstream use.

Common plasmids contain either stretches of different restriction sites to allow for cut and paste cloning, or more specialized sites such as phage recognition sites, that allows for quicker insertion of a gene flanked with complementary sites into the plasmid.

Finally plasmids for expression (as opposed to cloning plasmids, which are just used like molecular work benches to modify the gene) will contain different promoter sequences, allowing for tuning of the relative intensity of gene expression.
 
Well, the definition of a species is that it is not possible for the two animals to successfully reproduce together. Though, sometimes two different species can be close enough to one another for hybrid offspring to be created (e.g. a horse and a donkey can create a mule, tigers and lions can interbreed and create a "liger", etc.). However, the offspring is typically sterile in these cases. The definition is specific to reproduction. Genetic and/or anatomical similarities do not determine whether or not two animals are of the same species.
 
thanks @Skorpio!! i feel embarassed not knowing this shit. i've just always considered them to be things containing nucleic acids outside of the nucleus, it makes sense given how stable and versatile they are that, as well as playing a crucial role in evolution, we can use them for cool molecular biology stuff.
LandsUnknown said:
tigers and lions can interbreed and create a "liger"
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ah, but is a liger still a cat?

the speciation thing generally only applies to animals. plants can do crazy shit. bread wheat is 3 grass species smooshed together, and it reproduces just fine. strawberries as we eat them were made by combining two wild strawberries that were already each two wild strawberries combined to produce an insanely heterozygous octoploid genome.

then we get to microbes. bacteria just about fit into a sensible definition of species but viruses do not- a standard cut off for things being in the same species is an average nucliotide identity of 99.5%, you can be a host to a single type of virus with an ANI lower than that between individual vrions especially if you've been failing to fight it off for a while and it has widened its tropism. and some genera of viruses have so little in common between their members that from a lowly bioinformaticians point of view i don't see how they can be considered the same.

back on topic. given i reduce everything to its genome, maybe a cat is any organism who's DNA is >99.5% identical to that of our feline reference sequences?
 
chinup said:
back on topic. given i reduce everything to its genome, maybe a cat is any organism who's DNA is >99.5% identical to that of our feline reference sequences?
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A question borne out of lazieness, but do you know the ballpark similarity between human and cat DNA?

Also I think the slight philosophical component of this question is important. What signifies a cat? Are we going by a srict biological definition (cat=feline) or are we going by an ideal concept of a cat (say a fully mature housecat). Considering where this question came from, I think this is a worthwhile lens.

Is a dead cat a cat? If so for how long? Is a fossil of a cat a cat?
 
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