Metamorphosis occurs in X. laevis and X.tropicis tadpoles. Do their digestive systems differ? What is the function of their typhlosole? Let’s look at each of these organisms and see if there is any connection. X. laevis secretes wastes in the digestive tract. Does the typhlosole help in nutrient absorption?
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X. tropicalis
The typhlosole plays a key role in nutrient absorption. However, X. tropicalis tadpoles also experience a reduction in the small intestine length after T3 treatment. The effects of T3 treatment on the intestine are similar to those of metamorphosis. The length of the small intestine in stage 54 X.tropicis tadpoles was measured after three and five days of T3 treatment. After three and five days, the length of the small intestine decreased.
The intestine of X. tropicalis undergoes extensive changes during metamorphosis. MGPY weakly staining the epithelium in larvae at stage 61. At stage 62, the epithelium of newly formed adult epithelial progenitor/stem cells is strongly stained by MGPY, similar to X. laevis. The epithelium begins folding at stage 64-66. During this stage, the typhlosole is absent.
In premetamorphic tadpoles, the entire small intestine is made of a monolayer of larval epithelial cells, with little connective tissue. This epithelium eventually degenerates and the X. tropicalis adult epithelium grows into a multi-folded structure. It is also believed to be essential for epithelial development.
The extra cell layer in the gizzards of earthworms stores food. This crop stores food until it reaches its gizzard, where it is ground with stones. Typhlosole is an aid to nutrient absorption. This tissue contains a small molecule known as a protein called stromelysin.
X. laevis
In tadpoles, typhlosole is present in the entire small intestine. This lining can also be found in the anterior part of X.tropicis’ intestine. Typhlosole’s presence suggests that it is involved in nutrient absorption. Besides, typhlosole also helps in the formation of a protective layer around the food in the intestine.
The larval intestinal epithelium becomes weakly stained by MGPY at stage 61, and the newly formed adult epithelial progenitor/stem cells are strongly stained by MGPY. In stage 62, the epithelium begins folding, and it becomes more resembles X. laevis. During stages 64-66, typhlosole disappears from the intestine.
In a study, T3 induced similar changes in tadpoles’ intestines. The length of the small intestinal tract was reduced in tadpoles who were treated with T3 from 0 to 6 days. Similar results were observed in stage 54 X.tropicis tadpoles following T3 treatment. The X. laevis intestine was significantly smaller after 5 days.
Frogs also need this protein in their larval intestines. It is also important in nutrient absorption and helps in the development of the adult intestine. Despite being a non-native protein, it does play an important role in nutrient absorption in Xenopus. It helps in nutrient absorption, promoting frog growth and development.
X. tropicalis tadpoles
We hypothesized that the typhlosole found in the tadpoles helps in enhancing nutrient absorption. Premetamorphic tadpoles with small intestinal epithelium were treated with T3 for 0 to 5 days, and then the intestine was isolated and stained with MGPY. As the larval epithelium began to degenerate, its staining was diminished. During metamorphosis, however, this trait was strongly stained in newly formed epithelial islets.
Although the organization of Typhlosole is different in each species, it is similar to that in mammals and amphibians. In both species, heavy chain genes recombine before light chain genes. Igs are composed of 11 families, including VH1 and VH2. The recombination patterns of the Igs vary from species to species. The VH1 family is expressed more often in tadpoles than in adults.
The intercalating non-ciliated cells in X. tropicalis embryos are also present in the epidermal layer. Tadpoles that were caged with air developed slower than those raised in the absence of air. The researchers studied both effects by separating the caged and air-deprived groups. They raised tadpoles both in high- and low-density control tanks as well as in cages that were exposed to air. After many experiments, they found that different cage positions relative to airstones were possible. They also experimented with the flow of water from the airstones.
In Xenopus, connexins are involved in gap junctions. Researchers have identified seven connexin protein species in X. tropicalis. One of them, Cx28.6, has a 60% amino acid identity to human Cx25. In addition, it possesses strong homology with mouse Cx26 and Cx30.
Metamorphosis of X. laevis
It is unclear what role T3 plays in intestinal remodeling. T3 levels are at their highest during postembryonic development. This is when adult stem cells develop. This metamorphosis involves de novo generation of adult stem cells. However, studies of adult stem cell development in X. laevis have been done, revealing that the role of T3 in regulating metamorphosis is not well understood in this organism.
Premetamorphic tadpoles were treated with T3 to induce similar changes in the intestine as natural metamorphosis. MGPY was used to stain the premetamorphic intestinal cells. This dye differentiates proliferating larval epithelial cells and dying larval cells. Stage 54 saw the larval epithelium becoming monolayer of larval epithelial cell with a thin connective tissue and outer muscle layers. The typhlosole, which was abundant, remained unchanged throughout the metamorphisis.
However, the role of T3 in X. laevis metamorphosis is not entirely understood. However, it appears to play a role in the development of adult intestinal stem cells. This effect may be explained by T3 action in the non-epithelial epithelium, which is likely to be the case in the intestine. The presence of this gene in the epithelium helps in nutrient absorption.
X. tropicalis typhlosole
Researchers have discovered that the typhlosole in X. tropicalis tadpoles aids in nutrient intake. The tadpoles can grow faster and live longer at higher temperatures by reducing the length their small intestine. The differences in tadpole growth were due to a difference in typhlosole organization.
It is not clear what exact physiological role typhlosole plays in the development and maintenance of adult intestinal stem cell. However, it may be involved in promoting the development of adult intestinal stem cells. In vitro culture of anterior small intestinal fragments containing typhlosole showed that larval epithelial cells were apoptosis was delayed and that the development of adult intestinal epithelium had been delayed.
The intestine underwent extensive changes during metamorphosis. At stage 61, the larval epithelium is weakly stained by MGPY. MGPY strongly stain the newly formed adult epithelial stem cells/progenitor/stem cells. They resemble X. laevis. At stage 62, the epithelium folds and develops into a multiple-layered structure. By stage 66, the larval typhlosole is no longer visible.
Premetamorphic X.tropicis tadpoles are affected by T3. However, T3 is toxic to tadpoles and can even cause death. However, T3 also inhibits apoptosis in T3-treated larvae. It is unclear if this is a beneficial effect of typhlosole in tadpole metamorphosis.
X. laevis typhlosole
Xenopus tropicalis’ intestine is made up of a monolayer larval epithelial cells and very little connective tissue. The typhlosole is a single fold in this epithelium. The larval epithelium degenerates during metamorphosis, whereas the adult epithelium develops into a multifolded structure. Despite being present in the adult intestine, typhlosole is not visible in X. tropicalis tadpoles.
It is believed to play a role in the development and maintenance of adult intestinal stem cells, although its exact function is not known. Intestinal metamorphosis was observed in cultured tadpoles. Fragments of the anterior small intestinale were subject to intestinal metamorphosis with and without typhlosole. The development of the adult epithelium was markedly enhanced in tadpoles without typhlosole.
Typhlosole, an endocrinine hormone, aids in nutrient absorption. Although Xenopus larvae lack the larval lymph glands, they are found in the liver, kidneys, and lungs. The ventral cavity bodies are not likely to be lymphoid glands in adults. They could, however, be equivalent to these organs in an adult tadpole.
Similar studies of X. tropicalis (X. laevis) revealed that X. larval epithelium in X. Laevis degenerates via apoptosis. In addition, it exhibits similar transcriptional activities. Both species exhibit metabolic changes during metamorphosis. This suggests that the two species could be related. There are also similarities in the developmental stages of the gastrointestinal tracts.