victolgizhupparatus

Photograph by Vera Kratochvil, License: CC0 Public Domain

Recent research from the University of British Columbia and BC Children’s Hospital Research Institute proved that the amount of physical contact between infants and their caregivers can affect children at the molecular level. The study demonstrated that children who had been more distressed as infants and received less physical contact had an underdeveloped molecular profile for their age. This is the first study to show that the simple act of physical touching on human children can result in deeply-rooted changes in genetic expression.

The researchers measured a biochemical modification called DNA methylation in which parts of the chromosome are tagged with small molecules made of carbon and hydrogen. These molecules act as “dimmer switches” that help control how active each gene is and affect how cells function. The extent of methylation and where on the DNA it takes place can be impacted by external conditions, especially in childhood.

The team analyzed DNA methylation of 94 healthy children with records of received caregiving from the age of five weeks to four and a half years. The DNA methylation patterns the scientists gathered presented consistent differences between high-contact and low-contact children at five specific DNA sites. Two of the five sites are related to genes: one involves in the immune system, and the other in metabolism. The children who experienced higher distress and received little contact had a lower “epigenetic age” than what’s expected from their age. Such low epigenetic age is conceived as an underdevelopment of the child’s molecular profile. As medical genetics professor Michael Kobor said, “In children, we think slower epigenetic aging might indicate an inability to thrive.”

The researchers intend to further examine whether the “biological immaturity” – epigenetic changes resulted from low physical contact – carries broader implications for children’s health, especially their psychological development. According to the lead author Sarah Moore, “If further research confirms this initial finding, it will underscore the importance of providing physical contact, especially for distressed infants.”

By Jzp706 (Own work) [CC0], via Wikimedia Commons https://commons.wikimedia.org/wiki/File%3AKinesin_walking.gif

Have you ever wondered how tiny motor proteins manage to carry cargo inside cells?

As we know, motor proteins called kinesins transform energy from chemical ATP into mechanical action by attaching themselves to large cargoes like mitochondria and pulling them along cytoskeletal filaments. Each kinesin contains two “head” subunits, and each subunit contains two binding sites – one to grip and walk along microtubules and the other to bind ATP. However, few studies have been conducted on motor proteins’ detailed mechanisms.

Recently, Rice University led a study exploring the little-understood topic of the sensitivity of a motor’s velocity in response to a force and the cooperation between motor proteins. The researchers used computer simulations to provide the first molecular-level details of how kinesins respond to external forces. The models showed that the velocity of kinesins is weakly influenced by small to midrange external force but is steeply reduced by a large force: only under large loading forces would the velocity of kinesin be significantly reduced as the motor head releases ATP at a fast rate. Under small to midrange forces, the velocity barely changes.

What’s interesting to note is that the study also confirmed while motor proteins naturally work in teams, two load-bearing kinesins are not able to equally share the load unless they are within the distance of 48 nanometers from each other! As a consequence of such weak cooperation, the trailing kinesin faces the challenge of catching up to the leading one, while the lead kinesin has to take on the responsibility of carrying more than 90 percent of its cargo load. This is because, according to the researching, “the lead kinesin pays more attention to the pull of the cargo itself, which triggers a ‘switch’ in the neck linker that controls the speed. A trailing kinesin that’s too far away doesn’t sense the force and therefore can’t contribute its muscle.”

The study gives an opportunity for future study of similar mechanisms, such as that of dyneins, larger and more complex proteins that move cargo within cells. It also inspires more scientists to research kinesins as defective or deficient kinesins are implicated in certain kidney diseases and Charcot-Marie-Tooth disease.

By Boumphreyfr (Own work) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

Click here to read the original article. Click here to watch “A Day in the Life of a Motor Protein” and learn more about motor proteins!

BioQuakes

AP Biology class blog for discussing current research in Biology

Author: victolgizhupparatus

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