Sex chromosome difference and Origin of Snake
The sex of the snake is determined by the sex chromosome and belongs to the ZZ/ZW mechanism. In order to study the origin and evolution of snake sex chromosomes, KazumiMatsubara, a researcher from the Creative Science Research Institute (CreativeResearch.InitiativeSousei,CRIS) of Hokkaido University, Japan, used fluorescence in situ hybridization (fish) to measure the cytogenetic map (cytogeneticmap) of Japanese four-stripedrat snake (Elaphequadrivirgata). The article was published in PNAS on November 28th.
There are 109 cDNA clones in the map, 11 of which are located on Z chromosome. The genes of humans and birds corresponding to the Z chromosome genes of snakes are located on autosomal (autosomes), indicating that the sex chromosomes of snakes, mammals and birds originated from different autosomal pairs of common ancestors. The researchers also mapped 11 Z-linked genes (Z-linkedgenes) of E.quadrivirgat, Burmese python (Pythonmolurusbivittatus) and rattlesnake (Trimeresurusflavoviridis) to study the differences in W chromosomes. It was found that all 11 clones were found in the Z chromosome of P.molurus and E.quadrivirgata, 3 clones were found in the W chromosome of P.molurus and E.quadrivirgata, and cDNA was not detected on the W chromosome of T.flavoviridis. The results of comparative mapping (Comparativemapping) showed that there was little change in sex chromosomes in P.molurus, but there was a great difference in T.flavoviridis. E.quadrivirgata was in the excessive stage of sex chromosome differentiation. This sex chromosome difference may occur in the short arm terminal region of the pre-sex chromosome of the autosomal common ancestor (protosexchromosome), and then deletions and heterochromatin (heterochromatizationprogressed) occur during the evolution from the most primitive boids to the highly evolved viperids.
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The dog's "fear of hands"
When dealing with dogs, the trainer tries to play only a friendly and commanding role. And never give the dog any threat and intimidation impression. Now let's talk about the dog's "phobia." This "hand phobia" in dogs is caused by improper hand movements of the trainer, which give the dog the impression of danger and fear in daily training. So much so that every gesture of the trainer, whether given to him or intended to show affection, alarmed the dog, and some dogs even began to panic at the sight of the trainer's or anyone else's gesture.
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Prevention and treatment of selenium deficiency in raccoon dogs
The prevention and treatment of selenium deficiency in raccoon dogs has obvious regional characteristics. Generally speaking, the geological environment of selenium deficiency causes selenium deficiency in human beings and animals, especially in the years with more autumn rain, the selenium in the surface soil is lost with Rain Water, mainly herbivores or omnivores, it is difficult to obtain enough selenium from plants, which leads to selenium deficiency. The narrow areas from northeast to southwest of China are selenium-deficient areas, especially in the western part of Heilongjiang Province and Liangshan in Sichuan Province. The concentration of selenium in organs and tissues of selenium deficient animals decreased.
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