Atherosclerotic Coronary Heart Disease (CHD) is responsible for one in every six deaths in the United States as well as being the leading cause of death throughout the developed world.

 The theory of dietary saturated fats as the principal promoter of elevated serum cholesterol and heart disease stems from research beginning in the 1950's by an American scientist Ancel Keys. It was this hypothesis which was embraced by the American Heart Association and the US federal government in the 1960s and until recently. However, at the same time of Keys research, a British physiologist named John Yudkin argued that sugar intake was more closely related to incidence of and mortality from CHD. 

Florida's citrus industry has been struggling for nearly a decade with citrus greening, also known as Huanglongbing (HLB), a disease caused by a bacterium that destroys fruit production and eventually kills the tree. An effective cure has eluded researchers so far, and crop production is declining steadily.

Sperm that don't swim well rank high among the main causes of infertility but these cells may get a boost from motorized "spermbots" that can deliver poor swimmers -- that are otherwise healthy -- to an egg.  

The study indicates that under the frigid weight of Barents Sea Ice sheet, which covered northern Eurasia some 22 000 years ago, significant amounts of methane may have been stored as hydrates in the ground. As the ice sheet retreated, the methane rich hydrates melted, releasing the climate gas into the ocean and atmosphere for millennia.

This finding was published last week in Nature Communications in the paper "Ice-sheet-driven methane storage and release in the Arctic".

As decision makers from around the world congregated in Paris to prepare a global climate agreement at the 21st Conference of the Parties (COP21), many discussions focused on how to reduce greenhouse gases, including ozone.

While efforts to limit ozone precursor emissions tend to focus on industrial activities and fossil fuel combustion in the United States and China, a new study suggests that future regulations may need to address the burning of forests and vegetation. The study, which was published online January 13, 2016 in the journal Nature Communications, indicates that these types of "biomass burning" may play a larger role in climate change than previously realized.

High levels of vitamin D are linked to improved fertility and reproductive success, a study of wild sheep has found.

The study, carried out on a remote Hebridean island, adds to growing evidence that vitamin D - known as the sunshine vitamin - is associated with reproductive health.

Experts hope that further studies will help to determine the relevance of the results for other mammals, including people.