A researcher from Iowa State University led a study that provided insight into how organisms adapt to solve sex chromosomal problems. The study, which examined the nature of the soft turtle, was published in the journal ‘Philosophical Transactions of the Royal Society B’, but Nicole Valenzuela, professor of ecology, evolution, and biological biology and the study’s lead author, said the findings could be flawed. information on important evolutionary processes in many species.
Many organisms determine what kind of individuals they are by special chromosomes that appear in almost every cell in the body of an organism. Two identical chromosomes result in one sex, while two mismatched chromosomes result in the other sex. For example, in humans and many other species, the sex chromosomes are called X and Y. Normally, the two X chromosomes end up in females and the XY chromosomes end up in males. These chromosomes also contain genes for the production of important proteins, and the imbalance of chromosomes in XY individuals is caused by having only one X for a pair each of the non-sex chromosomes (called autosomes) can lead to an imbalance in reproduction. of proteins. The study sheds light on how organisms have evolved to resolve such imbalances through a process called sex chromosome recombination, or SCDC.
The study focused on a species of loggerhead turtle known as the Apalone spinifera, which is among the largest freshwater turtles and lives across much of North America, including Iowa . But research can help scientists understand how other organisms work. This study may provide a better understanding of how death can occur if the SCDC process is not working properly. “Understanding the diversity of SCDC mechanisms in nature, how they occur and how they evolve, provides a broader understanding of how animals and humans compensate for genetic imbalances , and why the failure to properly compensate for these differences leads to disease states,” Valenzuela said.
The study was published this week in the peer-reviewed scientific journal Philosophical Transactions of the Royal Society B. Sex chromosome compensation works for people with sex chromosomes. In the case of the soft-shelled turtles included in the study, the sex chromosomes are called Z and W, and they are the females of the non-paired, or ZW, chromosomes. That mismatch means they don’t have a second copy of the Z chromosome, unlike their male counterparts who have two Z chromosomes.
Z chromosomes contain the instructions for some of the proteins that normally functioning cells must produce, and having only one copy of the chromosome can result in reduced protein production. , because protein production is often affected by the number of copies of a gene. More copies mean more protein production. Therefore, an imbalance in the number of copies of genes that work together can lead to developmental, physiological or other problems. But SCDC mechanisms work to amplify, or increase the level of, protein production from genes on one Z (or X) chromosome. The importance of maintaining the right balance is evident in diseases caused by abnormal numbers of sex chromosomes, including Klinefelter’s disease and Turner’s disease in humans, and Valenzuela says these patterns have consequences for evolution and health and many other things.
Valenzuela and her co-authors sampled soft-shell ducts at various stages of development, including embryos, young and adult, and analyzed the different tissues to determine whether which genes are activated. The researchers compared the activity of genes from sex chromosomes and from autosomes, broken by male and female turtles. This study not only represents the first such study to analyze the return of sex chromosome values in turtles, but the findings also show that surprisingly, temperature seems to affect the activity of SCDC in turtles. Valenzuela studied temperature-dependent sex drive (TSD), or the way environmental temperature influences whether a turtle embryo becomes male or female in species that lack sex chromosomes, in previous research. But because soft-shelled turtles lost this ancestral TSD system, this temperature sensitivity in SCDC was surprising, he said. And the way simple channels form SCDC is unusual and complex.
The study found that both sexes of softshells double in Z activity in early embryonic development, correcting the expression imbalance in ZW females (double Z expression now corresponds to autosomal expression). But the same reaction causes an imbalance in males (the Z expression then doubles the autosomal expression). In later embryonic stages, male Z expression decreases, and this effect is more pronounced at cooler than warmer incubation temperatures, according to the study. Valenzuela said the new study may be the first to show that temperature can affect SCDC not only in turtles, or animals, but more broadly as eukaryotes, or organisms where genes which are present in the nucleus of the cell. Eukaryotic species include many types of organisms, including animals, plants, and fungi. (ANI)
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