News by Subject Medicine & Health

A handful of left-handed women have excellent senses of smell, despite lacking olfactory bulbs.

A team of researchers have uncovered a sliver of the population who have no apparent olfactory bulbs yet can somehow still smell. Extensive tests of two of these people proved they could identify, detect, and discriminate between odors as well as the average person, according to a paper published Nov. 6 in the journal Neuron.

A team of neuroscientists led by Professor Christiana Ruhrberg (UCL, UK) and Professor Anna Cariboni (University of Milan, Italy) have found two molecules that work together to help set up the sense of smell and pave the way to puberty in mice. These findings, reported in the journal Development, may help our understanding of why patients with the inherited condition Kallmann syndrome cannot smell properly and cannot start puberty without hormone treatment.

Using optogenetic and chemogenetic techniques, researchers at the National Institute for Physiological Sciences in Okazaki, Japan, identified brain circuits underlying hunger-induced changes in the preferences for sweet and aversive tastes in mice. These circuits involved Agouti-related peptide-expressing neurons, which projected to glutamate neurons in the lateral hypothalamus. From there, glutamate neurons projecting to the lateral septum increased sweetness preferences, and glutamate neurons projecting to the lateral habenula decreased sensitivity to aversive tastes.

Scientists from the Max Planck Institute for Chemical Ecology demonstrated that not only plant odors determine the best oviposition site for egglaying hawkmoths, but also the frass of other larvae. They specified the repelling substance in the feces which signals the presence of competing conspecifics. Moreover, the researchers identified an odorant receptor which is involved in the detection of the typical smell of larval frass and thereby governs competition avoidance during oviposition.

Newly discovered chemical-sensing cells in the gums protect the mouth by standing guard against infections that damage soft tissue and destroy the bone that supports the teeth. With the help of bitter taste receptors that also detect byproducts from harmful bacteria, these special gum cells trigger the immune system to control the amount and type of bacteria in the mouth and could one day lead to personalized dental treatments against gum disease.