silas.edwin.johnson
Member
CHITIN:
Today, I want to introduce you to a molecule called chitin. Chitin is a highly complex chain of N-acetylglucosamine, which is somewhat similar to glucose. If you look up a picture of chitin, you will see what appears to be two shapes that kind of resemble an hourglass. These are cyclohexanes (hexane means six carbon atoms and cyclo means cyclic). They have a few groups I’m not going to get into, but what I do want to address is that n on the right side of the brackets. What that means is that the unit within the brackets is going to repeat, and that’s how you get super long chains of chitin.
Chitin is produced in the epidermal (skin cells) of many arthropods (insects and other bugs) and gives the insects a great level of protection from animals that want to eat them. It makes them very difficult to chew, but even more difficult to digest [1].
CHITINASE:
See, chitin is a carbohydrate. All animals can digest simple carbohydrates, and your chameleon is no exception. Given glycogen (the sugar in his bugs), his digestive system is going to spit out various enzymes such as amylase [2] which take the glycogen and break it into small glucose molecules which are absorbed by the bloodstream and taken to the chameleon’s cells.
The problem is that chitin can’t be broken by conventional enzymes. Chitin has hydrogen bonds (very strong bonds), it is insoluble in water (so it doesn’t dissolve) and is so tightly packed, that we call it crystalline. The reason insects have chitin is not because it’s hard to penetrate with a bite, but rather that, it’s harder to degrade. Thus, all of the nutrients inside an insect’s exoskeleton aren’t leaving without a chitin-degrading enzyme [3].
Most animals don’t eat insects because of this reason. The more insects an animal eats, the more energy it is spending to capture prey which it can’t extract nutrients from.
That was until chitinase became a thing. Chitinase is the enzyme that is capable of breaking apart chitinase. Chitinase takes the bonds between the cyclohexanes (we call these β-1,4-linkages) and breaks them, making much simpler sugars. Then, these sugars will go through a long list of other digestion attempts, until the chitin is turned into sugar and transported to the bloodstream.
DO CHAMELEONS RELY ON CHITINASE?
So, the question is, who has chitinase? Well, insects certainly have chitinase. They require chitinase to break their exoskeletons during the molting process [4]. Crustacean-eating fish (such as Atlantic Salmon) also have chitinases, so they can actually eat crustaceans [5]. Amphibians (such as the American Bullfrog) also do the same thing, they need chitinase to decompose all of the flies and other insects they eat [6].
Now, here’s where things get confusing. Your chameleon may or may not have chitinase. Previously, it had been assumed that reptiles just didn’t use chitinase for their insectivorous diets. It was assumed that they relied on bacteria that did have chitinase. We wouldn’t assume that an animal had chitinase, because it is a lot easier to hold onto chitinase-containing bacteria than it is to develop your own chitinase. We know that many Bacteria such as Streptomyces are big producers of chitinase, and they use chitinase to metabolize chitin. So, is it possible that chameleons use these bacteria to digest chitin? Yes, it’s definitely possible.
However, there was a study done on the Eastern Fence Lizard (Sceloporus undulatus) which is closely related to Chameleons (the Iguania diverged in the Cretaceous). What they found is that Sceloporus had chitinase in the stomach, pancreas and small intestine [7]. We can assume that chameleons probably also have chitinase.
I’m going to say that it is probably the case that chameleons have as much chitinase as insectivorous fish and amphibians, or a limited amount of chitinase. However, the question is, to what degree do chameleons depend on their own chitinase, and to what degree do they depend on the chitinase of bacteria? Because, if they depend on bacteria, we will see that antibiotics would significantly damage their digestive system for lengths of time, specifically, a chameleon’s ability to break down the chitin in their food.
BIBLIOGRAPHY:
[1] https://en.wikipedia.org/wiki/Chitin
[2] https://www.vetexotic.theclinics.com/article/S1094-9194(02)00054-3/pdf?utm
[3] https://pubmed.ncbi.nlm.nih.gov/10919822/
[4] https://academic.oup.com/jinsectscience/article/23/6/10/7453458?utm_source=chatgpt.com&login=true
[5] https://pubmed.ncbi.nlm.nih.gov/37581908/
[6] https://einstein.elsevierpure.com/en/publications/cellular-expression-of-the-gut-chitinase-in-the-stomach-of-frogs--2/?utm
[7] https://pubmed.ncbi.nlm.nih.gov/11290449/
Today, I want to introduce you to a molecule called chitin. Chitin is a highly complex chain of N-acetylglucosamine, which is somewhat similar to glucose. If you look up a picture of chitin, you will see what appears to be two shapes that kind of resemble an hourglass. These are cyclohexanes (hexane means six carbon atoms and cyclo means cyclic). They have a few groups I’m not going to get into, but what I do want to address is that n on the right side of the brackets. What that means is that the unit within the brackets is going to repeat, and that’s how you get super long chains of chitin.
Chitin is produced in the epidermal (skin cells) of many arthropods (insects and other bugs) and gives the insects a great level of protection from animals that want to eat them. It makes them very difficult to chew, but even more difficult to digest [1].
CHITINASE:
See, chitin is a carbohydrate. All animals can digest simple carbohydrates, and your chameleon is no exception. Given glycogen (the sugar in his bugs), his digestive system is going to spit out various enzymes such as amylase [2] which take the glycogen and break it into small glucose molecules which are absorbed by the bloodstream and taken to the chameleon’s cells.
The problem is that chitin can’t be broken by conventional enzymes. Chitin has hydrogen bonds (very strong bonds), it is insoluble in water (so it doesn’t dissolve) and is so tightly packed, that we call it crystalline. The reason insects have chitin is not because it’s hard to penetrate with a bite, but rather that, it’s harder to degrade. Thus, all of the nutrients inside an insect’s exoskeleton aren’t leaving without a chitin-degrading enzyme [3].
Most animals don’t eat insects because of this reason. The more insects an animal eats, the more energy it is spending to capture prey which it can’t extract nutrients from.
That was until chitinase became a thing. Chitinase is the enzyme that is capable of breaking apart chitinase. Chitinase takes the bonds between the cyclohexanes (we call these β-1,4-linkages) and breaks them, making much simpler sugars. Then, these sugars will go through a long list of other digestion attempts, until the chitin is turned into sugar and transported to the bloodstream.
DO CHAMELEONS RELY ON CHITINASE?
So, the question is, who has chitinase? Well, insects certainly have chitinase. They require chitinase to break their exoskeletons during the molting process [4]. Crustacean-eating fish (such as Atlantic Salmon) also have chitinases, so they can actually eat crustaceans [5]. Amphibians (such as the American Bullfrog) also do the same thing, they need chitinase to decompose all of the flies and other insects they eat [6].
Now, here’s where things get confusing. Your chameleon may or may not have chitinase. Previously, it had been assumed that reptiles just didn’t use chitinase for their insectivorous diets. It was assumed that they relied on bacteria that did have chitinase. We wouldn’t assume that an animal had chitinase, because it is a lot easier to hold onto chitinase-containing bacteria than it is to develop your own chitinase. We know that many Bacteria such as Streptomyces are big producers of chitinase, and they use chitinase to metabolize chitin. So, is it possible that chameleons use these bacteria to digest chitin? Yes, it’s definitely possible.
However, there was a study done on the Eastern Fence Lizard (Sceloporus undulatus) which is closely related to Chameleons (the Iguania diverged in the Cretaceous). What they found is that Sceloporus had chitinase in the stomach, pancreas and small intestine [7]. We can assume that chameleons probably also have chitinase.
I’m going to say that it is probably the case that chameleons have as much chitinase as insectivorous fish and amphibians, or a limited amount of chitinase. However, the question is, to what degree do chameleons depend on their own chitinase, and to what degree do they depend on the chitinase of bacteria? Because, if they depend on bacteria, we will see that antibiotics would significantly damage their digestive system for lengths of time, specifically, a chameleon’s ability to break down the chitin in their food.
BIBLIOGRAPHY:
[1] https://en.wikipedia.org/wiki/Chitin
[2] https://www.vetexotic.theclinics.com/article/S1094-9194(02)00054-3/pdf?utm
[3] https://pubmed.ncbi.nlm.nih.gov/10919822/
[4] https://academic.oup.com/jinsectscience/article/23/6/10/7453458?utm_source=chatgpt.com&login=true
[5] https://pubmed.ncbi.nlm.nih.gov/37581908/
[6] https://einstein.elsevierpure.com/en/publications/cellular-expression-of-the-gut-chitinase-in-the-stomach-of-frogs--2/?utm
[7] https://pubmed.ncbi.nlm.nih.gov/11290449/
