Showing posts with label chromosomes. Show all posts
Showing posts with label chromosomes. Show all posts

Tuesday, November 21, 2017

Fertility fails if chromosomes don’t have time to zip

fertility and chromosomes,female fertility and chromosomes
"Before an egg becomes fertilized, sets of chromosomes must pair up to pass along genetic information.

This happens within each reproductive cell, where separate chromosomes of male and female origin move toward each other and eventually join.


“You need to give the strands time to join for cell division to be done correctly.”

“Chromosomes’ movement is important because you need to move them in synchronicity,” says Sarit Smolikove, associate professor in biology at the University of Iowa. “We’ve shown you don’t want to move them too much or too frequently. You need to give the strands time to join for cell division to be done correctly.”

Smolikove likens the process to a parent zipping a coat for a child. If the child is jerking about as the parent tries to zip the coat, it takes longer for the action to be completed; worse, the zipper could break, meaning the coat doesn’t get zipped at all.

Likewise, the chromosome strands need to line up and have the time to “zip up,” so genetic information is accurately swapped.

Smolikove and colleagues have discovered a protein that appears to regulate the speed at which the female (maternal) and male (paternal) chromosome strands move and pair up.

In laboratory tests, the researchers learned the protein acts like a brake on the chromosomes’ movement, especially the juncture at which the chromosomes join and share DNA, which is critical to an offspring’s successful inheritance of its parents’ genes.

The findings offer new insight into the intricate steps involved in animal fertility, from basic organisms all the way to humans. They also could help biologists better understand defects that occur in reproduction, including those that contribute to Down syndrome..."

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Tuesday, October 31, 2017

Sleep duration may affect the integrity of sperm DNA

sleep duration and human spern dna
via 123rf.com
"A new study found a link between sleep duration and a measure of chromosomal health in sperm. The findings are published in the Journal of Sleep Research.

In the study of 2020 semen samples provided by 796 male volunteers from colleges in Chongqing (China) from 2013 to 2015, volunteers with more than 9 hours per day of sleep and those with 6.5 hours or less per day sleep had 41% and 30% lower High DNA Stainability -- an index that represents the proportion of sperm with abnormal chromatin -- than did volunteers with 7 to 7.5 hours per day of sleep. Chromatin is a complex of DNA and proteins that forms chromosomes.

"This is new information after our previous finding that sleep duration has an inverse U-shaped association with semen volume and total sperm count. In the previous study, we found that these two semen parameters were highest when sleep is 7.0 to 7.5 hours per day, and either longer or shorter sleep was associated with the decrease of the two semen parameters.," said Dr. Jia Cao, co-author of the study."

Source: sciencedaily.com

Monday, October 31, 2016

Application of comprehensive chromosome screening could improve IVF success

ivf and chromosome screening,application of chromosome screening and ivf
credit: pinterest.com
"An increase in the frequency of polymorphic variants among infertile patients compared with fertile donors suggest they have an impact on fertility.

Chromosomal polymorphisms have an impact on fertility, increasing the chromosomal abnormalities in male gametes and embryos. While previous studies have reported a higher incidence of chromosomal polymorphisms in infertile patients, the relationship between these variants and infertility is still unclear.

"Chromosomal polymorphic variants increase aneuploidies in male gametes and embryos" examines the relationship between polymorphisms and infertility. The study and its findings were published in the latest issue of Systems Biology in Reproductive Medicine. The results showed an increase in the frequency of polymorphic variants among infertile patients compared with fertile donors, suggesting they have an impact on fertility.

Further results revealed that female polymorphism carriers have a higher risk for embryo aneuploidy than females with a normal karyotype..."

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Tuesday, October 4, 2016

How to be a male without the Y chromosome

how to be a male without the y chromosome,males without the y chromosome
credit: gizmodo.com
"Hokkaido University researchers have revealed that key sex-determining genes continue to operate in a mammalian species that lacks the Y chromosome, taking us a step further toward understanding sex differentiation.

In most placental mammals, the Y chromosome induces male differentiation during development, whereas embryos without it become female. The sex-determining gene SRY is present on the Y chromosome and induces other regulatory genes that suppress female differentiation. The Amami spiny rat (Tokudaia osimensis) is exceptional as it lacks a Y chromosome and thus the SRY gene, raising the question of why male differentiation can still occur.

Tomofumi Otake and Asako Kuroiwa of Hokkaido University in Japan performed gene mapping to determine the chromosomal locations of sex-related genes in the T. osimensis genome. They then compared its nucleotide and amino acid sequences with those of the mouse and rat. Furthermore, using cultured cells, they examined how the sex-related genes were regulated..."

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