Leopard Tortoise

[FLINTUS]

Yeah, I know you can increase the red with beta carotene foods. Don't know if you're on any of the US tort forums but presume you would be so if you look up N2TORTS on there you can find some more of them. I believe they stay outside mainly, with addition of misters e.t.c and are fed a relatively normal red foot diet supplemented with mazuri. One thing he does do is feed a lot more citrus fruits than most of us do.

[Baoh]

Originally Posted by Lisamn

Baoh, can I ask what RF marbling is please (in simple terms)? Also, you mentioned that tortoises kept without UV suffered no ill effects (I'm paraphrasing here). Do you just mean terms of their markings and colouring, or do you include general health and well-being too?

The mottled coloration you see in redfoot tortoises. Most often witnessed in "cherryheads" (the definitions for cherryhead vary somewhat depending on who is talking -some go by region/locale and some go by phenotype/appearance-, so I am staying away from that bit), but non-cherryhead animals occasionally display this as well (less frequently, I think).

I generally provide UVB sources, whether sunlight or artificial, to my tortoises for much if not all of the year. However, there are some tortoises I have kept without access to UVB for the sake of my curiosity. In these instances of no UVB exposure, I do provide D3 in the diet (my UVB-exposed animals also get dietary D3, mind you), and these animals do not display observable differences in health. I was only referring to coloration.

[Baoh]

Originally Posted by Lisamn

And how often do you supplement with D3 if not providing UV?

The commercial food I provide to such animals is fortified, so daily. A multi-mineral supplement with D3 is also provided a few times a week, depending on the animal.

[Baoh]

Originally Posted by Lisamn

Just done a (very brief) bit of research and it seems that tyrosinase activity would tend to decrease at approx 37 °C, therefore melanin production would probably be inhibited, so I guess torts kept at higher temps than this might show effects with regards to colouring.

Depends on the tyrosinase enzyme variant (isozyme). 37C is the typical human body temperature. There are plenty of animals that have tyrosinase and produce melanin at temperatures higher than this. Their enzymes would be better tuned to a higher operating temperature relative to some species that do not operate at such temperatures. Even within a species. Dogs, for example, express melanin well enough, so their enzymes are capable of operating above 37C. Were you looking at human data or human-derived tyrosinase? If so, the 37C is in reference to that specificity.

[Baoh]

Originally Posted by EJ

I have to disagree with you on the calcium content in the keritin layer of the shell. I believe that is how the shell gets it's white color... why a Sulcata lightens up... the source of the those squiggly lines that so many keepers or concerned when the keritin layer takes up calcium. I would think the calcium would add hardness to the keratin layer of the shell... which is why I believe the scutes become brittle and less plyable as they develope.

Sorry I don't know the mechanism... but... there is a change to the structure of the scutes on the shell that I believe is the uptake of calcium.

I think we could have a better conversation if you could dumb it down a little.

It seems like you are trying to impress more than properly communicate. I hope you don't take offense at this. I'll admit that I'm really ignorant when it comes to the vocabulary you are using and I have an AS degree in biology along with priding myself in having an extensive herp library... not to mention access to the internet. I get the feeling you are trying to say some neat stuff... I'm not getting it all without breaking out the books or researching every other sentence.... and I don't have time for that until Tuesday.

I have printer paper. It has a white color. It does not require calcium to reflect white light. My ivory hatchlings and their heterozygous siblings would possess roughly the same amount of calcium thanks to mom's contributions. One is white. The other, not. A sulcata lightens up when exposed more to the sunlight. An Aldabra does not. That does not mean the Aldabra's calcium level is dropping and does not mean the sulcata's calcium level is rising, scute content or otherwise. Correlation (if that) versus causation.

If you could show me a reference that shows via testing that the squiggly lines are an expression of calcium uptake in keratin, I would like the opportunity to see it. Could just as easily be keratinocyte activity hotspots during growth phases, but I would not state is as such unless there was something more than a guess to it.

The literature and testing shows keratin to be primarily uncalcified. If you have testing that shows otherwise, I am all eyes. There is calcium, but it is not a large amount.

Here is a shot that shows it from a reference examining such. It is from "Micro-structure and mechanical properties of the turtle carapace as a biological composite shield."



S refers to sulfur, richly abundant in keratin proteins. C is for carbon. Ca is for calcium. Notice the relatively large density of carbon, significant amount of sulfur, and much lower amount of calcium.

I doubt the calcium, based on the way it is incorporated (distribution and concentration), adds much in the way of hardness. Scutes would naturally be less pliable when thicker than when thinner, too, for a given material composition, so that may offer an alternative explanation for differences in perceived pliability.

I am a Biologist and we are discussing a technical topic. I take no offense. Believe it or not, this is dumbed down, regardless of any impression or belief in such. I think the Einstein quote goes, "Make things as simple as possible, but not simpler." I could argue, alternatively, that we could also have a better conversation if you researched the topic more extensively or familiarized yourself with the vocabulary surrounding the biological aspects broached, but I do not state that unless there is a prompt for it because I, likewise, am not seeking to offend.

[EJ]

I'd love to see any photos of non Cherryhead Redfoots that display the mottling color.

Originally Posted by Baoh

The mottled coloration you see in redfoot tortoises. Most often witnessed in "cherryheads" (the definitions for cherryhead vary somewhat depending on who is talking -some go by region/locale and some go by phenotype/appearance-, so I am staying away from that bit), but non-cherryhead animals occasionally display this as well (less frequently, I think).

I generally provide UVB sources, whether sunlight or artificial, to my tortoises for much if not all of the year. However, there are some tortoises I have kept without access to UVB for the sake of my curiosity. In these instances of no UVB exposure, I do provide D3 in the diet (my UVB-exposed animals also get dietary D3, mind you), and these animals do not display observable differences in health. I was only referring to coloration.

[EJ]

What is the reference the photos come from?

I didn't say there was a great amount of calcium in the scutes... I believe that there is an increased uptake of calcium in the shell scutes as the tortoise develops. In other words there is more calcium in the older growth of the scutes than in the new growth.

If you're a scientist you probably have more access to the equipment to measure the percent content of calcium in a given material. It would be easy to obtain a scute of a hatchling and that of a more developed tortoise to make a comparison.

Originally Posted by Baoh

I have printer paper. It has a white color. It does not require calcium to reflect white light. My ivory hatchlings and their heterozygous siblings would possess roughly the same amount of calcium thanks to mom's contributions. One is white. The other, not. A sulcata lightens up when exposed more to the sunlight. An Aldabra does not. That does not mean the Aldabra's calcium level is dropping and does not mean the sulcata's calcium level is rising, scute content or otherwise. Correlation (if that) versus causation.

If you could show me a reference that shows via testing that the squiggly lines are an expression of calcium uptake in keratin, I would like the opportunity to see it. Could just as easily be keratinocyte activity hotspots during growth phases, but I would not state is as such unless there was something more than a guess to it.

The literature and testing shows keratin to be primarily uncalcified. If you have testing that shows otherwise, I am all eyes. There is calcium, but it is not a large amount.

Here is a shot that shows it from a reference examining such. It is from "Micro-structure and mechanical properties of the turtle carapace as a biological composite shield."



S refers to sulfur, richly abundant in keratin proteins. C is for carbon. Ca is for calcium. Notice the relatively large density of carbon, significant amount of sulfur, and much lower amount of calcium.

I doubt the calcium, based on the way it is incorporated (distribution and concentration), adds much in the way of hardness. Scutes would naturally be less pliable when thicker than when thinner, too, for a given material composition, so that may offer an alternative explanation for differences in perceived pliability.

I am a Biologist and we are discussing a technical topic. I take no offense. Believe it or not, this is dumbed down, regardless of any impression or belief in such. I think the Einstein quote goes, "Make things as simple as possible, but not simpler." I could argue, alternatively, that we could also have a better conversation if you researched the topic more extensively or familiarized yourself with the vocabulary surrounding the biological aspects broached, but I do not state that unless there is a prompt for it because I, likewise, am not seeking to offend.

[Baoh]

Originally Posted by EJ

I'd love to see any photos of non Cherryhead Redfoots that display the mottling color.

I do not own them and have only seen a few examples in person as well as a few on the internet.

[Baoh]

Originally Posted by EJ

What is the reference the photos come from?

I didn't say there was a great amount of calcium in the scutes... I believe that there is an increased uptake of calcium in the shell scutes as the tortoise develops. In other words there is more calcium in the older growth of the scutes than in the new growth.

If you're a scientist you probably have more access to the equipment to measure the percent content of calcium in a given material. It would be easy to obtain a scute of a hatchling and that of a more developed tortoise to make a comparison.

The reference is stated just prior to the image.

I would like to see a reference showing those changes in uptake and that result in scute development.

I could probably run XRF easily enough, but I would have to be inclined and I would also have to sacrifice animals, as I do not get too many chelonian deaths or keep corpses around outside of specific situations (like DOAs).

It would be interesting to see.

[EJ]

Fault one... we are discussing terrestrial tortoises. I'm sure the micro structure of the scutes is very different at that level.

I'll see if I can accomodate you on the reference showing the changes...

Again... I don't have a clue what XRF is.

Animal sacrifice would not be necessary if you have been studying these animals for any length of time. You should either have shells at your disposal or access to preserved shells.

Either way it repeaked my interest and I do have some friends at UG Athens who might be able to help me.

I'll keep you posted on my research.

btw... check out the relationship between calcium and keratin... pay particular attention to the molecular structure and what bonds each chain together...

Originally Posted by Baoh

The reference is stated just prior to the image.

I would like to see a reference showing those changes in uptake and that result in scute development.

I could probably run XRF easily enough, but I would have to be inclined and I would also have to sacrifice animals, as I do not get too many chelonian deaths or keep corpses around outside of specific situations (like DOAs).

It would be interesting to see.