[Alan McDougall (OP)]

I know we exist in a  "Sea of viruses", that are almost countless, even in one drop of ocean water, or inside our bodies there are trillions.

There is even debate if they are not truly living things, however, they have killed of countless humans over history and almost always get a negative report, from those who do not really understand their part in nature.

Could you name some positive aspects about viruses in nature and in human evolution? (We all know the negativity of these murderous tittle fellas)

Alan

[evan_au]

Some viral genes are active in formation of the human placenta and early embryo.
That makes it pretty important to all of us.

See: https://en.wikipedia.org/wiki/Endogenous_retrovirus#Human_endogenous_retroviruses

[puppypower]

Since virus can insert DNA, into the host's DNA, virus could theoretically, cause the DNA to change, even quicker than just in situ changes? For one thing, viral DNA insertions will get past the proofreader enzymes used during cell cycles.

Do virus add material to the junk DNA, which controls the configurational context for active genes? Configuration context is how the junk genes define the active shape of the DNA, which, in turn, defines the potentials seen by the active genes.

Picture you are making raisin bread. The raisons are analogous to the active genes, and the dough are junk genes. Depending how you prepare and kneed the dough, can determine the raisin distribution in each slice. The slice distribution, in turn, will impact how the raisons will play off each other, each bite. This can impact cellular differentiation control and/or introduce new differentiations; slice of raisin bread with all the raisins in the middle.

[evan_au]

In the past century, the Drosophila Melanogaster fly (much beloved in research laboratories) has been overrun in the wild by an identical-looking but genetically incompatible fly. This genetic incompatibility (and effective development of a new species) is due to viral genes, or "transposons".
See: https://en.wikipedia.org/wiki/P_element

There is some evidence that some viral genes have been active in the human genome in the past 100,000 years - perhaps a similar event led to us as a species, in the past?

Plus, the study of viruses gives Chris Smith something to do when he's not working on the next podcast...

[Alan McDougall (OP)]

Since virus can insert DNA, into the host's DNA, virus could theoretically, cause the DNA to change, even quicker than just in situ changes? For one thing, viral DNA insertions will get past the proofreader enzymes used during cell cycles.

Do virus add material to the junk DNA, which controls the configurational context for active genes? Configuration context is how the junk genes define the active shape of the DNA, which, in turn, defines the potentials seen by the active genes.

Picture you are making raisin bread. The raisons are analogous to the active genes, and the dough are junk genes. Depending how you prepare and kneed the dough, can determine the raisin distribution in each slice. The slice distribution, in turn, will impact how the raisons will play off each other, each bite. This can impact cellular differentiation control and/or introduce new differentiations; slice of raisin bread with all the raisins in the middle.

Viruses insert RNA into a cell, not DNA!

[RD]

... Could you name some positive aspects about viruses in nature and in human evolution? ...

Dr. Sharp, who won a Nobel Prize for elucidating details of our genetic code. Base for nucleic base, he said, “we humans are well over 50 percent viral.”

http://www.nytimes.com/2008/01/08/science/08angi.html

[evan_au]

Viruses insert RNA into a cell, not DNA!

There are various kinds of virus, categorized by the nature of their genetic code. Most use RNA, but some use single-stranded DNA and some use double-stranded DNA.

In some cases (like HIV), the virus transcribes itself into the host's DNA before it can begin replicating. If this virus infected an egg or sperm cell, this viral DNA could be passed on to a child, and appear in every cell in their body.

See: https://en.wikipedia.org/wiki/Virus#Genome

[Alan McDougall (OP)]

Viruses insert RNA into a cell, not DNA!

There are various kinds of virus, categorized by the nature of their genetic code. Most use RNA, but some use single-stranded DNA and some use double-stranded DNA.

In some cases (like HIV), the virus transcribes itself into the host's DNA before it can begin replicating. If this virus infected an egg or sperm cell, this viral DNA could be passed on to a child, and appear in every cell in their body.

See: https://en.wikipedia.org/wiki/Virus#Genome

I stand correct!, however it seems the viruses with RNA  are most most dangerous?

Are viruses alive or somewhere between a living thing and nonliving?

[yellowcat]

I stand correct!, however it seems the viruses with RNA  are most most dangerous?

Are viruses alive or somewhere between a living thing and nonliving?

Not sure that it is possible to say that RNA viruses are more dangerous than DNA viruses. Polio, Ebola, Hepatitis C, Measles virus and influenza viruses are RNA but papilloma viruses, pox viruses, Hepatitis B and herpes viruses are DNA.

Virus infected  cells are living but virus particles have no metabolism and are considered non living infectious agents.

[evan_au]

Could you name some positive aspects about viruses in nature and in human evolution?

Bacteriophages are viruses that attack bacteria.
They play a role in protecting us from dangerous bacteria.
Bacteriophages live in the environment, and in our digestive system, and keep bacteria from getting out of control.

[evan_au]

Europeans introduced rabbits to Australia, and they spread rapidly, destroying plant cover.
The Myxoma virus was introduced as a biological control, and it now keeps rabbit population density down to a barely tolerable level.
See: https://en.wikipedia.org/wiki/Myxomatosis

[Blame]

If viruses can add DNA to the host then one has to ask if it can take as well. That does kind of pose a further question. Could there be rare occasions where DNA has been transferred between species in the wild?   

I don't suppose the duck billed platypus really has part duck DNA but there might more subtle transfers.

[evan_au]

There is a routine way that bacteria transfer DNA in the wild, using plasmids or transposons.
See: https://en.wikipedia.org/wiki/Bacterial_conjugation
This is a source of great concern about the spread of antibiotic resistance; should antibiotic resistance genes appear in a plasmid, they can be easily transferred to other bacteria.

Much of the early genetic work on plants used "Crown Gall Disease" which can transfer a segment of DNA into a plant.
See: https://en.wikipedia.org/wiki/Agrobacterium_tumefaciens

Some experiments on genetic surgery in humans have tried using viruses to carry corrected genes into human cells. These have had varied success:
- Sometimes it has had no effect. If the human has been previously exposed to this virus, the immune system will kill it on sight.
- Sometimes it has had a catastrophic effect, with an overactive immune response which ended up killing the patient.
- Most viruses insert their DNA into a random place in the DNA, which could disrupt vital genes, or could trigger uncontrolled cell growth (cancer)

Genetic engineering by these techniques has been a shotgun approach.
Genetics researchers are excited about the possibilities of CRISPR, which is able to do much more targeted form of genetic surgery.