Radioactive tracer shows corn roots fight pest

Scientists have used radioisotopes to uncover the mechanisms corn plants use to combat a major pest, the western corn rootworm.

“The western corn rootworm is a voracious pest,” says Richard Ferrieri, a research professor in the University of Missouri Interdisciplinary Plant Group, and an investigator at the University of Missouri Research Reactor. “Rootworm larvae hatch in the soil during late spring and immediately begin feeding on the crop’s root system. Mild damage to the root system can hinder water and nutrient uptake, threatening plant fitness, while more severe damage can result in the plant falling over.” Read more.

Bat guano: A possible new source for paleoclimate reconstructions

Nitrogen isotopes within samples of bat excrement accurately reflect modern precipitation patterns. So could guano serve as a paleoclimate record?

Over the ages, armies have fought wars over guano, a stinky, cockroach-infested treasure that’s rich in nitrogen and phosphate. Although still valued for its fertilization qualities, this natural resource—once used to make gunpowder—may offer a new application as a window into climate change.

Scientists investigate past climates by studying substances that accumulate slowly over time. Trees, stalactites and stalagmites, peat, ice, lake sediments, ocean sediments, and corals all grow or accumulate in ways that reflect the environment surrounding them. Specifically, the isotopes within their structures fingerprint the conditions prevalent at the time of formation, be they wet, dry, cold, or warm. But paleoclimate records aren’t limited to tree rings and the like. Read more.

Did a supernova spark the solar system?

And now, from the Department of Silver Linings, some good news about star death.

Every star dies, eventually. The details of how and when depend on the mass of the star. When lightweights like the Sun run out of nuclear fuel, their outer layers drift out and away like dandelion fluff. Bigger stars — those more than ten times as massive as the sun — have more finales. These stars go supernova, strewing their guts across the galaxy in explosive shockwaves, including elements that can only be made via inside stars or in supernova explosions. Read more.

Radiocarbon method still a reliable tool for dating fossils

Radiocarbon dating can still be considered a reliable method for determine the age of artefacts and materials, according to a new study.

Recently, it was suggested that the dates offered by radiocarbon dating are increasingly being distorted by external factors. Human carbon dioxide emissions have sped up the reduction of the carbon isotope C-14 in the Earth’s atmosphere, bringing into question the accuracy of the method’s results.

The author of a new study published in the journal Environmental Research Letters argues that the level of distortion caused by anthropogenic emissions can actually be precisely identified. He believes this can be done by measuring the carbon isotope C-13. Read more.

Bound to need essential minerals: Isotope fractionation in mineral uptake by plants

All life on Earth requires certain essential minerals, such are iron and zinc, to function properly. Animals obtain these minerals from their diet, but plants have to take them up directly from the environment and that can create problems. This is because although these minerals are generally abundant in the soil and water, they are mainly present in the form of ionic species that are not very soluble and so can’t easily be absorbed by plant roots.

One solution to this problem adopted by many plants, as well as by bacteria and fungi that obtain minerals directly from the soil, is to release compounds known as siderophores that can bind these ionic species. Because the resultant complexes are much more soluble, they can easily be taken up by plants, providing them with the necessary minerals. An interesting adjunct to this binding process is that it tends to work more effectively with certain isotopes than others, producing a natural isotopic fractionation of the metal ions in soil and water. Read more.