If 2 heads are better than 1

[physicsisphirst]

if 2 heads are better than 1 ...

this is apparently a first - or is it a third

anyone care to comment on the "environmental warning'?

in friendship,
prad


'Warning' over three-headed frog
(http://news.bbc.co.uk/1/hi/england/somerset/3534361.stm)

Children in a nursery were shocked when they spotted a three-headed frog hopping in their garden.

The creature - which has six legs - has stunned BBC wildlife experts who warned it could be an early warning of environmental problems.

Laura Pepper, from the Green Umbrella nursery in Weston-super-Mare, said: We thought it was three frogs huddled together at first.

It is very strange. The children couldn't believe it.

Mike Dilger, from the BBC Natural History Unit, added: I have never seen anything like this.

Frogs are primitive animals - so the occasional extra toe is not that unusual. But this is very unusual.

All the creature's eyes and legs appear to function normally, but it is not known whether it eats using all three of its mouths.

The mystery amphibian is currently the subject of a frog-hunt after it hopped away and disappeared as staff at the nursery showed it to curious parents.

 

[Evo]

I pity the frog on the bottom. The ones on top seem rather fat.

 

[Tsu]

I can't believe it got away! (I'd LOVE to see a Cat Scan of it! )

 

[Moonbear]

It seems everytime someone finds a mutant frog, there's an uproar about environmental this or that. I'm searching my brain for the final outcome of a similar case of a whole bunch of frogs turning up in a particular lake with extra legs that also caused a big worry about some pollutant. I can't remember what they finally determined to be the cause, but it wasn't quite so horrendous as people were predicting...something like a virus that infected the tadpoles during metamorphosis. I wouldn't be overly concerned about a single case of this showing up...afterall, conjoined twins occur in humans too...with all the frogs in the world, one is bound to find a few oddities here and there.

 

[Monique]

Amazing that it survived this long though . Instead of an environmental disaster waiting to happen, this could just mean that there are lots of flies flying around: providing the animal with food, allowing it to survive.

 

[Moonbear]

Good point Monique! You're right, it could mean environmental conditions are so favorable, that even a severely disadvantaged animal can survive. The whole idea of mutants as an indicator of environmental disruption is probably spurred on more by science fiction than science. I li

 

[Monique]

Well, a very warm winter (as we've just experienced in w. Europe), allowing insects to survive, cóuld be classified as an environmental disruption. But not in the widely perceived way of environmental toxins producing mutants, but lots of food sustaining mutants :)

 

[Phobos]

the success of a "hopeful monster"

shows the power of mutation

so now the question is what caused the mutation...something "natural" (like in Moonbear's example) or a pollutant?

 

[Monique]

Frogs are primitive animals, just how many eggs do they lay at a time? It is not surprising if things go wrong once in a while, happens in humans too.

The thing I don't understand is that the three frogs are ON TOP of each other in the right orientation. From a developmental point of view I would have expected them all to be attached on the bellies.. of course from a different point of view: such mutants would never lived after hatching.

So are these three different frogs that somehow ended up in the same egg and fused or are these one frog which split into several and never detached? I guess the former, from the reasoning I just gave.

 

[Monique]

Hmg, something just doesn't seem right to me.. if you ask me the bottom one is a female and the top two are males holding on véry tightly..

 

[spuriousmonkey]

It seems like a duplication (triplication) of the body axis.

'antique' research showed that basically anything done to an early embryo of a certain stage can duplicate the body axis.

http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?call=bv.View..ShowSection&rid=.0QuOwrVaSH1yUah_WMHm2UOd1GKDaH6Qel5

 

[Njorl]

Originally posted by Monique
Hmg, something just doesn't seem right to me.. if you ask me the bottom one is a female and the top two are males holding on véry tightly..

I think you just have a dirty mind young lady!


Njorl

 

[Monique]

Originally posted by Njorl
I think you just have a dirty mind young lady!

Njorl

Now WHO is thinking dirty thoughts, eh? I was just saying those *edit: male* frogs are really lazy

 

[Monique]

Originally posted by spuriousmonkey
It seems like a duplication (triplication) of the body axis.

'antique' research showed that basically anything done to an early embryo of a certain stage can duplicate the body axis.

http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?call=bv.View..ShowSection&rid=.0QuOwrVaSH1yUah_WMHm2UOd1GKDaH6Qel5

See! That picture proves my point! Previously posted by me: "From a developmental point of view I would have expected them all to be attached on the bellies"

Those three frogs are nót one organism.

 

[Evo]

Originally posted by spuriousmonkey
It seems like a duplication (triplication) of the body axis.

'antique' research showed that basically anything done to an early embryo of a certain stage can duplicate the body axis.

http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?call=bv.View..ShowSection&rid=.0QuOwrVaSH1yUah_WMHm2UOd1GKDaH6Qel5

But what is so bizarre about this as Monique pointed out, is that they all seem to be fully formed, pointed in the same direction, aligned perfectly. What are the odds of that? Have you ever seen even conjoined twins so perfectly connected?

 

[Monique]

Have you ever seen someone carrying its twin on its back?? No, that is because the way an embryo develops, as I have been referring to. Embryonic development depends on a lot of very orchastrated signals which dictate body axis and orientation. The spinal cord forms on the outside, the endoderm on the inside. See figure B http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&rid=.0QuOwrVaSH1yUah_WMHm2UOd1GKDaH6Qel5 Try to visualize the three frogs being inside that embryo, it doesn't work..

 

[spuriousmonkey]

I didn't say they are twins...they have a secondary and tertiary body axis. It is not the same as twins.

 

[Monique]

Ok, so tell me how that is different.

 

[spuriousmonkey]

Follow the link I gave for explanation of secondary axis formation.

and twins:

wins can occur in two ways. In around a third of cases just one egg is fertilised but within days it splits, each half developing into an identical baby. In the remaining two-thirds, two eggs are released at the same time and both fertilised by separate sperm resulting in two non-identical babies.

 

[Monique]

Twins too have duplication of body axis, just look at the famous siamese twin. So instead of naturally almost splitting in two and aquiring two dorsal blastopore tips, the article you provided describes artificially creating two blastopore tips, thus proving the developmental basis of commitment of certain embryonic tissues.

So AGAIN I say that you cannot get something to grow -either from the same cluster of cells, or from another one- belly to back.

Unless you provide me with a link where scientists transplanted a different embryonic region to a developing embryo, where that DID occur.

 

[spuriousmonkey]

That twins arise from a duplication of the body axis is entirely a conclusion you made. It cannot be found in the link I gave or in the notion of how twins arise.

I think you should provide a link for such a statement. I'm just referring to basic developmental biology.

 

[Monique]

Ok.. think a little here..

HOW do you think that two persons grow out of a single embryo? THAT is basic developmental biology. How can a monozygotic twin grow with two spinal cords without duplication of body axis? If there is no duplication of body axis, you get a person with two heads. Such people exist.

 

[Monique]

http://www.hapmoore.com/images/sept03/two-heads.jpg

 

[spuriousmonkey]

I'm a bit harsh here because I had a very bad 2 weeks behind me but here it goes anyway:

again then

wins can occur in two ways. In around a third of cases just one egg is fertilised but within days it splits, each half developing into an identical baby. In the remaining two-thirds, two eggs are released at the same time and both fertilised by separate sperm resulting in two non-identical babies.

in what way is this the same as the induction of a second primary organizer region or nieuwkoop center resulting in another body axis?

No , not at all the same.


You post a pic of a siamese twin but i doubt a siamese twin develops in the same way as a regular twin.

Let's look for instance at this reference



http://zygote.swarthmore.edu/cleave4a.html

may be caused by any number of factors, being influenced by genetic and environmental conditions. It is presently thought that these factors are responsible for the failure of twins to separate after the 13th day after fertilization. Conjoined twins can be artificially generated in amphibians by constricting the embryo so that two embryos form, one on each side of the constriction.

Now, is that the same as forming a new primary organizer resulting in multiple body axis?

No.

another link to siamese twins
link

Siamese twins are formed from a single egg which develops into two almost separate balls of cells. In normal twinning, each ball becomes an identical twin. As a result cells in Siamese twins become confused about where they are in the body - indeed which of the two Siamese twins they are actually in.

IS this then similar to the formation of a secondary bodyaxis by induction of an ectopic organizer?

No.

I think I posted enough links.

For more information read

'developmental biology' by Scott Gilbert.

It is a nice book, and I am not just saying that because I got a copy from him for free.