Science Simplified!

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Comment by Dr. Krishna Kumari Challa on February 3, 2016 at 6:06am

Chromosomes must be accurately segregated during the production of sex cells to ensure that the next generation inherits an intact copy of the genome. However, this process is particularly error-prone in women and gets worse as they get older. Errors in chromosome segregation produce egg cells with the wrong number of chromosomes, which can lead to infertility and Down syndrome .
New eggs develop from immature egg cells (or oocytes) via meiosis: this process involves the original cell’s DNA being replicated once before it divides twice to produce four new cells, each with half the original number of chromosomes. Most errors in the number of chromosomes in human eggs come from mistakes made when the oocyte divides for the first time in a process commonly called meiosis I. Multiple factors can contribute to these errors, but it is not clear which are most significant in human oocytes.
Human oocytes start with 23 pairs of homologous chromosomes, which are split during the anaphase stage of meiosis I so that the egg contains one from each pair. There are two main requirements that must be met during meiosis I. First, each pair of homologous chromosomes must be physically connected to form a “bivalent”. Second, the two sister kinetochores on each chromosome must be functionally fused together so that both sisters connect to the same spindle pole. These two requirements are both compromised in human oocytes. This provides a plausible mechanism to explain the errors often seen in meiosis I in women.
-elifesciences.org

http://elifesciences.org/content/5/e13788?utm_source=content_alert&...

Comment by Dr. Krishna Kumari Challa on February 2, 2016 at 8:36am

Small ponds produce an outsized share of greenhouse gases
Tiny ponds play a disproportionately large role in global greenhouse gas emissions from inland waters, according to a new study by Yale's School of Forestry & Environmental Studies.
The reason has to do with the physical makeup of very small ponds and the way they cycle carbon. Small ponds have a high perimeter-to-surface-area ratio, for example, and accumulate a higher load of terrestrial carbon -- so-called "leaf litter," sediment particles and other material. Small ponds also tend to be shallow, which means their terrestrial carbon loads are highly concentrated compared to larger lakes. Lastly, gases produced at the bottom of these ponds are able to reach the top more often than what occurs in larger lakes, due to greater water mixing and shallower waters. Because of this, CO2 and CH4 generated in sediments affects the entire pond.

That makes small ponds an important player in the carbon cycle.
The carbon cycling that happens in freshwater systems needs to be accounted for in estimates of terrestrial production. These numbers are important to quantifying the global carbon cycle and making predictions about future stocks and flows of carbon.

Although ponds less than a quarter of an acre in size make up only 8.6% of the surface area of the world's lakes and ponds, they account for 15.1% of carbon dioxide (CO2) emissions and 40.6% of diffusive methane (CH4) emissions. The findings appear in the Feb. 1 online edition of the journal Nature Geoscience.

Comment by Dr. Krishna Kumari Challa on February 2, 2016 at 8:27am

UK scientists just got approval to edit human embryos
Scientists in Britain just got approval to conduct research that involves editing the genetic material of healthy human embryos.

This is a big deal: The UK's Human Fertilisation and Embryology Authority is the first government agency in the world to endorse research that involves altering the human genome for research — a move that could signal broader acceptance for a promising (but controversial) new area of science.

The research team, led by Dr. Kathy Niakan at the UK's Francis Crick Institute, is trying to better understand which genes allow a healthy human embryo to develop. Niakan’s team will use a promising new technique, known as CRISPR/Cas9, to edit genes that are active following conception. They'll then stop the experiments at day seven and destroy the embryos (so that they can't be used to start a pregnancy).

The hope is that this gene hacking could help researchers better understand what causes miscarriages and infertility — and perhaps one day lead to better treatments for infertility.

Comment by Dr. Krishna Kumari Challa on February 2, 2016 at 8:20am

New evidence emerges for 'transmissible Alzheimer's' theory:
Autopsies reveal plaques in the brains of people who died after receiving grafts from cadavers.

For the second time in four months, researchers have reported autopsy results that suggest Alzheimer’s disease might occasionally be transmitted to people during certain medical treatments — although scientists say that neither set of findings is conclusive.
The latest autopsies, described in the Swiss Medical Weekly1 on 26 January, were conducted on the brains of seven people who died of the rare, brain-wasting Creutzfeldt–Jakob disease (CJD). Decades before their deaths, the individuals had all received surgical grafts of dura mater — the membrane that covers the brain and spinal cord. These grafts had been prepared from human cadavers and were contaminated with the prion protein that causes CJD.

But in addition to the damage caused by the prions, five of the brains displayed some of the pathological signs that are associated with Alzheimer’s disease, researchers from Switzerland and Austria report. Plaques formed from amyloid-β protein were discovered in the grey matter and blood vessels. The individuals, aged between 28 and 63, were unusually young to have developed such plaques. A set of 21 controls, who had not had surgical grafts of dura mater but died of sporadic CJD at similar ages, did not have this amyloid signature.
According to the authors, it is possible that the transplanted dura mater was contaminated with small ‘seeds’ of amyloid-β protein — which some scientists think could be a trigger for Alzheimer’s — along with the prion protein that gave the recipients CJD.
http://www.smw.ch/content/smw-2016-14287/
http://www.nature.com/news/autopsies-reveal-signs-of-alzheimer-s-in...

Comment by Dr. Krishna Kumari Challa on January 31, 2016 at 11:04am

Till now we are under the impression that earthworms are highly beneficial to plants. But listen to this:  Earthworms not always beneficial, may threaten plant diversity!

A new study suggests that an abundance of earthworms in soils could lead to reductions in the number of trees and and other plant species.

Contrary to the popular belief that these creatures and beneficial to the natural ecosystem, the scarcity of these invertebrates can be a threat to certain plant species, causing adverse effects on the ecosystem.

Researchers from Canada's Université Laval and Université de Sherbrooke visited sugar maple forests in Quebec province where they found half of which were populated by earthworms.

Their analysis revealed a correlation between the number of earthworms and the abundance and diversity of certain understory species as they found that new shoots of red maple, striped maple, American beech, and two fern species became rarer as populations of these invertebrates increased.

"The most likely explanation is that the earthworms consume organic matter in forest litter," said Line Lapointe, a professor at Université Laval's faculty of science and engineering and the study's lead author.

"This results in soils that can't hold as much moisture, and that in turn interferes with seed germination and the ability of some species' plantlets to survive," she added.

Earthworms have started to change plant composition in sugar maple forests, according to the researchers.

Researchers suggest that earthworms used for bait should never be released in the forest, instead they be thrown into the lake to avoid overpopulation in the ecosystem.

The study has been published in the journal Forest Ecology and Management.

Comment by Dr. Krishna Kumari Challa on January 30, 2016 at 7:39am

Electrons do not orbit around an atomic nucleus like planets around a star. This outdated model of the atom (called the Bohr-Rutherford model) is still taught in schools, but only as an introduction to modern ideas about the atom.

Max Born showed us that electrons do not have a definite position, but instead exist as probability wave functions that describe how likely it is that the electron would be at a particular point in its atomic orbit. That is to say, the electron exists in a superposition of all possible locations around the atom. Werner Heisenberg discovered that it isn't until an electron is observed (detected by an instrument) that its wave function collapses and it takes on a discrete location.

So, really, electrons do not orbit around a nucleus; they exist in all possible locations around that nucleus simultaneously. Quantum mechanics!

Electrons don't orbit around atomic nucleuses like planets around a star. But that doesn't mean that they aren't moving.

The probability density for an electron is symmetric around the nucleus, so the average velocity would cancel out to zero. So let's calculate a typical speed from the square-root of the average velocity squared instead. (This is the referred to as root-mean-squared or r.m.s. for short.)

It's actually pretty easy to figure out the r.m.s. velocity for a typical electron from a few physics facts.

First, we need to the know the binding energy of the electron to the nucleus. We might as well assume it's in hydrogen, the simplest atom, so it has total binding energy of E = -13.6 eV (electron-volts):

Next, we need to know what part of the energy is kinetic (moving) instead of potential (due to the electric force holding the atom together). For closed orbits (electrons or planets), there is very handy relationship known as the Virial Theorem [1]. The Virial Theorem tells us that for particles experiencing an attractive 1/r21/r2 force like that between opposite charges, the average kinetic energy is equal to the negative of the total energy:
⟨T⟩=−E⟨T⟩=−E.

To calculate the r.m.s. velocity, we just need the non-relativistic [2] formula relating kinetic energy T and velocity v:
T=12mv2T=12mv2,
where m is the mass of the object.

Solving the above equations, we find:
vrms=−2Em−−−−√.vrms=−2Em.
Plugging in the binding energy and mass of an electron, we see that our hypothetical electron is moving at 2.2*10^6 m/s [3] or just shy of 5 million mph. Fast, but still about a factor of 100 times slower than the limit, the speed of light.

Comment by Dr. Krishna Kumari Challa on January 29, 2016 at 7:08am

A new global analysis of seafood found that fish populations throughout the world's oceans are contaminated with industrial and agricultural pollutants, collectively known as persistent organic pollutants (POPs). The study from researchers at Scripps Institution of Oceanography at UC San Diego also uncovered some good news?concentrations of these pollutants have been consistently dropping over the last 30 years. The findings, reported in the Jan. 28, 2016 issue of the journal PeerJ, were based on an analysis by Scripps researchers Lindsay Bonito, Amro Hamdoun, and Stuart Sandin of hundreds of peer-reviewed articles from 1969-2012. The pollutants studied included older 'legacy' chemicals, such as DDT and mercury, as well as newer industrial chemicals, such as flame retardants and coolants.
Although POPs were found in fish in all of the world's oceans, the researchers say that concentrations in the consumable meat of marine fish are highly variable, where one region or group of fish may find concentrations of POPs that vary by 1,000-fold. The analysis revealed that average concentrations of each class of POP were significantly higher in the 1980s than is found today, with a drop in concentration of 15-30 percent per decade.

"This means that the typical fish that you consume today can have approximately 50 percent of the concentration of most POPs when compared to the same fish eaten by your parents at your age," said Bonito, the lead author of the study. "But there still remains a chance of getting a fillet as contaminated as what your parents ate.
The authors caution that although pollutant concentrations in marine fish are steadily declining, they still remain quite high, and that understanding the cumulative effects of numerous exposures to pollutants in seafood is necessary to determine the specific risk to consumers.
Source: University of California - San Diego
and Science news

Comment by Dr. Krishna Kumari Challa on January 27, 2016 at 10:28am

Tenacious proteins similar to those implicated in Alzheimer’s disease could help purify polluted water.

A newly designed membrane uses thin amyloid protein fibers to pull heavy metals and radioactive wastes out of water. The membranes can capture more than their own weight in some contaminants, scientists in Switzerland report January 25 in Nature Nanotechnology.
Specifically, the team converted milk proteins into fibers of durable amyloid protein. Other amyloids are infamous for building up in the brains of Alzheimer’s patients, but the team put their amyloids’ sticky tendrils to different use.
When paired with strong, porous carbon in a membrane, the lab-made amyloids successfully filtered over 99 percent of toxic materials out of solutions that mimicked severely polluted waters, the scientists report. The amyloids trapped particles of lead and mercury at a molecular site that is involved in turning the original milk protein into its pasty form. Radioactive waste particles also got tangled in the membranes. And the membranes snagged gold contaminants, which the team found could later be recovered and purified. A membrane with less than 6 milligrams of amyloids could trap 100 milligrams of gold, the scientists report.
The membranes could be developed for small- or large-scale water purification units, says study coauthor Raffaele Mezzenga, a physicist at ETH Zurich. Mezzenga estimates the technology would cost roughly one dollar per every thousand liters of water filtered. And a membrane can recover hundreds of times its own value in precious metals, Mezzenga says. The membrane design is simple and flexible, and could be adjusted to optimize cleanup or metal recovery, he says.
http://www.nature.com/nnano/journal/vaop/ncurrent/full/nnano.2015.3...

Comment by Dr. Krishna Kumari Challa on January 27, 2016 at 10:07am

Comment by Dr. Krishna Kumari Challa on January 27, 2016 at 9:04am

The editors of the leading medical journals around the world made a proposal recently that could change medical science forever. They said that researchers would have to publicly share the data gathered in their clinical studies as a condition of publishing the results in the journals. This idea is now out for public comment.

As it stands now, medical scientists can publish their findings without ever making available the data upon which their conclusions were based.

Only some of the top journals, such as The BMJ, have tried to make data sharing a condition of publication. But authors who didn't want to comply could just go elsewhere.

Think about it. The scientists who generate the data, with the participation of the people being studied and often with public funding, control it and most often don't share. By holding the data tight, researchers who ran a study are the only ones who can conduct additional analysis and studies.

If the proposed change is adopted it would make sharing more compelling. Inaccessible data is a problem rife throughout medical science. Industry traditionally held its data close — but so did academics.

These researchers have felt that they deserved the right to future papers for all their hard work gathering the original data. And maybe they didn't want others examining their work.

But this practice shields data from scrutiny. It forgoes an opportunity to crowdsource knowledge from scientists who weren't associated with the original study. It also violates the sensible practice of showing your work, not just the presumed answer.
The editors who made the proposal sought to be sensitive to the rights of researchers, funders and participants. But their intent is clear: It's time to share.
http://www.npr.org/sections/health-shots/2016/01/26/464010931/journ...

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