Washington: A new study has revealed that occupational sitting is tied to increased likelihood of obesity in women, especially among black women.
Lead author Lin Yang said that the objective of this study from the School of Medicine and the Brown School at Washington University in St. Louis was to quantify the association between self-reported occupational sitting time and BMI by gender and race, independent of time spent in physical activity outside of work.
Yang added that to the best of their knowledge, this is the first study to examine differences in the association between occupational sitting and weight status among African American women and white women.
The researchers examined the association between occupational sitting and BMI between men and women and between black and white women and found that average daily time spent by both men and women in occupational sitting was between three and six hours. Most participants in the study were overweight or obese.
The researchers wrote in the study that after adjusting for potential confounders, they found that African-American women in three categories of sitting time (31-180 minutes, 181-360 minutes, and more than 360 minutes) were approximately and consistently 2.5 times as likely to be obese as African-American women who reported sitting for 30 minutes or less, independent of occupational and leisure-time physical activity.
This association was not seen among white women and no significant associations were found among men.
The researchers wrote that the lack of association between occupational sitting and weight status among men might be explained by the differences between men and women in physical activity preferences and men are more active in leisure-time physical activity than women and women tend to do less vigorous and more moderate activity compared with men.
The study is published in the journal Preventing Chronic Disease.
Artificial enzymes suggest life doesn't need DNA or RNA
London, Dec 7 (PTI) Researchers have developed artificial enzymes from genetic material that does not exist in nature, called XNA, an advance that hints at the possibility that life could evolve without DNA or RNA.
DNA or deoxyribonucleic acid and ribonucleic acid or RNA are two self-replicating molecules considered indispensable for life on Earth.
"Our work with XNA shows that there's no fundamental imperative for RNA and DNA to be prerequisites for life," said Philipp Holliger of the Laboratory of Molecular Biology in Cambridge, UK.
XNA or xeno nucleic acid created by Holliger's team contains the same bases - adenine, thymine, guanine, cytosine and uracil - on which DNA and RNA rely for coding hereditary information, 'New Scientist' reported.
In DNA and RNA, the sugars are deoxyribose and ribose, respectively. Holliger made new types of genetic material by replacing these with different sugars or other molecules.
In the new study, researchers showed that XNAs can also serve as enzymes - indispensable catalysts for speeding up chemical reactions vital for life.
One of the first steps towards life on Earth is thought to be the evolution of RNA into self-copying enzymes.
The XNA enzymes can't yet copy themselves but they can cut and paste RNA, just like natural enzymes do, and even paste together fragments of XNA.
Holliger said that RNA and DNA may have come to dominate Earth by chance, simply because they were the best evolutionary materials to hand.
"You could speculate that on other planets, XNAs would dominate instead," he said.