Scientific news in small doses

A few milligrams of all the scientific news of the week.

The Aztec calendar and corn planting

Pre-Columbian Aztecs determined when to plant corn by watching the sun rise between two mountain peaks, according to a new California study. Archaeologists from the University of California at Riverside have studied Aztec manuscripts and identified Mount Tlaloc, east of Mexico City. It would be the site of that observation crucial to the success of agriculture – and the well-being of the 3 million people who depended on it. An aisle in a temple was in the XVI^e century directly in line with the sunrise between two peaks of Tlaloc, at the beginning of xiuhpohualli, the Aztec solar year, or towards the end of February. Observers therefore knew to sow a month later, to take full advantage of the summer rains beginning in May.

Quiz

What Have Japanese Biologists Discovered About the Sexual Appendage of a Mason Wasp?

This penis can be used as a weapon to defend against predators. The discovery of researchers from Kobe University, published in mid-December in the journal Current Biology, calls into question the safety of male wasps, which lack the poisonous stinger of females. After being painfully stung by a male wasp Anterhynchium gibbifrons, one of the researchers tested whether the insect’s sexual appendage protected it against its predators, frogs. The result is clear: a third of the male wasps survived the attack of the frog, but none remained alive if their sexual appendage was removed. The poisonous stinger of female wasps is more effective, however, protecting them against a predator nine times out of ten.. Other wasp species have a similar sexual appendage, called a “pseudo-stinger”.

The number

4%

It is the increase in ocean productivity by 2100, if we take into account the “plasticity” of phytoplankton. This modeling by Korean biologists counters the pessimistic forecasts of the impact of climate change on the oceans, which predict a decrease in their productivity of 8% by 2100. The analysis by researchers from the University of Pusan, published in the mid-December in Science Advances, takes into account 30 years of observations at the ALOHA ocean observation site near Hawaii. There was a surprising increase in phytoplankton productivity when the sea was warmer.

A Quebec ataxia

Quebec researchers have identified a genetic mutation responsible for the majority of cases of late hereditary ataxia in Quebec. In the New England Journal of Medicine in mid-December, researchers from the Neuro, the CHUM and McGill and Sherbrooke universities presented the mutation in the FGF14 gene, found in 61% of the 66 patients suffering from this ataxia followed in Quebec. This ataxia, which affects 1 to 3 people each year in Quebec, begins around the age of 30 and causes problems with locomotion and speech. Colleagues in Australia, India, the UK and Germany have determined that this genetic mutation is present in 10% to 18% of late ataxia cases in these countries. This is the most common genetic mutation associated with this late ataxia. A diagnostic test based on this advance could be offered to relatives of people with this ataxia.

A vegetal mouth

California researchers have elucidated how plants use their temperature and humidity measurements to decide whether or not to open their “mouths”. The respiration of plants allows them to absorb CO₂ on which they feed, but causes them to lose internal moisture, at the risk of drying out. Researchers from the University of California, San Diego, who publish their results in early December in Science Advancesbelieve that their discovery will make it possible to design transgenic plants that are more resistant to drought.