In small plastic tubs lining the shelves of a basement laboratory at the University of Pennsylvania, a million organisms live in complex societies.
Just as the brain forms memories of familiar faces, the immune system remembers pathogens it has encountered in the past. T cells with these memories circulate in the blood stream looking for sites of new infection.
By encoding information in photons via their spin, “photonic” computers could be orders of magnitude faster and efficient than their current-day counterparts. Likewise, encoding information in the spin of electrons, rather than just their quantity, could make “spintronic” computers with similar advantages.
The human genome encodes roughly 20,000 genes, only a few thousand more than fruit flies. The complexity of the human body, therefore, comes from far more than just the sequence of nucleotides that comprise our DNA, it arises from modifications that occur at the level of gene, RNA and protein.
A scar might be a reminder of an accident or surgery, but the fibrous tissue that makes up a scar also forms after a heart attack and arises in solid tumors as well as in chronic diseases such as liver cirrhosis and muscular dystrophy. Implanted medical devices and materials are similarly surrounded by fibrous capsules that impede their function.
Cancer cells defy the rules by which normal cells abide. They can divide without cease, invade distant tissues and consume glucose at abnormal rates.
By Sarah Welsh
Nature versus nurture is an age-old question in biology, centering on whether a given trait is determined by an organism’s genes or by its environment. Most times the answer is “both,” but research at the University of Pennsylvania has found one trait in particular that is not easily described by either.
Lyme disease cases are on the rise, with diagnoses occurring in areas that were historically Lyme-free. Scientists attribute the spread to the fact that populations of blacklegged ticks, which carry the bacteria that causes the disease, now flourish in areas once thought to be devoid of ticks.
In the most severe form of male infertility, men do not make any measurable levels of sperm. This condition, called azoospermia, affects approximately 1 percent of the male population and is responsible for about a sixth of cases of male infertility.