Monthly Archives: December 2019

Sperm frozen for many years is still viable according to study

According to a new study, long-term cryopreservation of human sperm would not greatly affect sperm viability. The research, conducted by Chuan Huang of the Changsa-Hunan sperm bank in China and presented at the 35th annual ESHRE meeting in Vienna, saw a retrospective analysis of 119,558 sperm samples taken from donors.

The same samples were divided into three groups: the cryopreserved ones for a period of between six months and five years, the cryopreserved ones from six to 10 years and the cryopreserved ones between 11 and 15 years. Considering the samples of the longest period, Huang and colleagues realized that, as a result of the thawing, the sperm survival rate was reduced by a few percentage points, settling in a range between 85% and 74%.

This is a decline, according to the same scholars, which has made little difference, however, as regards the clinical use of sperm in the context of assisted pregnancies.

According to Huang, these percentages would also be favored by the quality of the sperm preserved and the psychophysical condition of the donors. Despite these factors, according to the researchers, long-term sperm conservation by cryopreservation methods does not seem to affect birth rates.

However, many sperm banks establish strict time limits for sperm storage, up to a maximum of 10 years in some cases, although the scientific literature does not offer clear explanations and detailed research that can justify the imposition of these limits, not even with regards to any DNA damage.

Researchers find why humans are more prone to fat than other primates

A study conducted by researchers at Duke University clarifies some aspects regarding the question of the greater accumulation of fat in humans compared to other species of primates. In fact, in some ways, it is a mystery: why are humans so subject to obesity compared to many other species of apes and in general primates with which they share 99% of DNA?

Suffice it to say that most other primates have less than 9% body fat while for humans a fat level of between 14 and 31% can be considered healthy and normal. It is not just about eating styles and diets: there must be something genetic behind it. And in fact, the researchers have discovered that the greater aptitude to fat of the humans is connected to a molecular change in the modalities with which the DNA is packed inside the fat cells, a change that would have happened in some point of our past evolution.

This change has reduced our body’s ability to transform white fat, called “bad” fat, into brown fat, which is then dubbed the “good” fat. The study, published in Genome Biology and Evolution, describes the results achieved by Devi Swain-Lenz and Greg Wray, two Duke biologists during experiments on fat samples taken from humans, chimpanzees and Rhesus macaques. By analyzing the genome of the samples, they identified a recurrent DNA fragment that underlies the conversion of fat from one cell type to another.

This fragment would still be fully operational in monkeys while in humans it would have remained “hidden” making us lose the ability to maximize the process that sees the fat cells being diverted to “good” fat. “We are stuck along the path of white fat,” reports Swain-Lenz.

The research could be useful to understand the possibilities of activation or deactivation of some genes to reactivate the process and therefore counteract obesity, but the same researchers report that at the research level we are still very far from such a goal: “I don’t think it’s as simple as pushing a switch: if it was, we would have understood it a long time ago,” reports Swain-Lenz.

New method to break down lignin with enzymes devised by researchers

A group of researchers has discovered a new family of enzymes that could be very useful for converting plant-based waste into materials that can be used to create materials of different nature. The research team, which had already engineered an enzyme to “digest” plastics last year, is headed by Jen Dubois of Montana State University, by Gregg Beckham of the National Renewable Energy Laboratory (NREL), Ken Houk of the University of California, Los Angeles, and by John McGeehan of the University of Portsmouth.

For years, scientists have been trying to “break down” lignin, a component found in plants, one of the most widespread biopolymers on Earth together with cellulose. Currently lignin can be broken down only by a few fungi and bacteria but there are many attempts made in the laboratory to find a method to break it down in order to extract the chemicals that it can potentially offer.

The researchers in this case, for the breakdown of lignin, used a natural enzyme and they engineered it in the laboratory. Unlike other enzymes used in other processes for the breakdown of lignin, in this case the modified enzyme adapts to a greater number of constituent elements at the base of the lignin itself. These results, according to the researchers, could represent an important step for a better, more economical and more efficient realization of new materials such as nylon, bioplastics and carbon fiber.

The work of the research group is certainly not finished here, as John McGeehan specifies: “Now we have proof of the principle that we can successfully engineer this class of enzymes to tackle some of the most challenging lignin-based molecules and we will continue to develop biological tools able to convert waste into precious and sustainable materials.”

New states of matter in graphene discovered that are useful for quantum computers

A group of physicists has discovered the existence of “previously unknown states of matter” in graphene, the best-known two-dimensional nanomaterial. These states of matter, according to the researchers, arise from complex interactions of electrons in the graphene layers.

As explained by Jia Li, a professor of physics at Brown University, one of the authors of the research, “the stacking of 2D materials in close proximity generates a completely new physics.” The same discovery could be useful on a practical level for the creation of electronic devices that exploit these phenomena that fall within the complex of the phenomenon called the fractional quantum Hall effect.

The latter is the quantum version of the Hall effect that occurs when a conductor is applied perpendicularly to the current flow of a magnetic field, which creates a transverse voltage. In particular, as Jim Hone, a professor of mechanical engineering and author of the study, explains, the results would prove useful for creating quantum computers that could more efficiently withstand faults.

These new states have different potentials including the one related to the fact that electrons can maintain a sort of “memory” of their past positions, which would allow quantum computers to not have to correct errors.

A swim in the sea alters the skin microbiome for several hours

A simple bath or a swim in the sea of ​​just a few minutes is enough to temporarily alter the skin microbiome, but in a quite evident way according to interesting research presented at the annual meeting of the American Society for Microbiology.

According to Marisa Chattman Nielsen, a student at the University of California, Irvine, lead author of the study, exposure to ocean water can alter the diversity and composition of the human skin microbiome, although the latter appears to return to its initial condition after several hours.

The experiment was carried out on nine participants who carried out a 10-minute swim monitored by the same researcher who took into account various factors. The beach met the criteria regarding the possibility of not being able to use a sunscreen while the participants had a history of sporadic swimming in the sea. Furthermore, the same participants had not immersed themselves in seawater during the 12 hours prior to the experiment and had not taken antibiotics in the previous six months.

The researcher and her colleagues followed a swab on the back of the calf of the participants in the experiment before they entered the water and after they had come out and dried completely in the sun. Additional swabs were then performed after six hours and 24 hours after the swim.

Before the swim, the participants showed different microbial communities on their skin but after the swim they all had similar communities, completely different from the previous communities.
Six hours after entering the water, the microbiomes of the skin seemed to return to the pre-swim composition. 24 hours after the swim the composition was almost similar to the one before the swim.

Interesting results saw the presence of bacteria of the genus Vibrio on the skin of the participants not only after they had dried but also six hours after the swim (24 hours later they were present only on one individual).

It is a demonstration of the fact that possible species of pathogenic vibrios could potentially persist on the skin even several hours after swimming, which actually increases the vulnerability of the human body to infections with regard to contact with seawater.