Temperature, reproduction link holds promise for insect control

Date:
February 17, 2022
Source:
Cornell University
Summary:
Scientists have uncovered a set of neurons in fruit flies that
shut down in cold temperatures and slow reproduction, a system
conserved in many insects, including mosquitoes, which could
provide a target for pest control.



FULL STORY ========================================================================== Scientists have uncovered a set of neurons in fruit flies that shut
down in cold temperatures and slow reproduction, a system conserved in
many insects, including mosquitoes, which could provide a target for
pest control.


========================================================================== Their study, published Feb. 16 in the journal Current Biology,takes a step toward understanding how a fly's brain contributes to sensing the cold
and limiting reproduction. Insects and animals, including many mammals,
curb reproduction in the winter to protect their newborns from being
exposed to harsh winter conditions.

The study has public health and agricultural implications, as tapping
into environmentally-dependent mechanisms that influence reproduction in mosquitoes and crop pests may offer new control strategies. Mosquitoes
act as reservoirs for the malaria-causing Plasmodium falciparum parasite,
which spend the winter inside them.

"If there's a brake in the mosquito's brain that shuts down their
reproductive facilities, and if we can find that brake and artificially activate it, it might open ways to control mosquito populations,"
said Nilay Yapici, assistant professor of neurobiology and behavior and
Nancy and Peter Meinig Family Investigator in the Life Sciences in the
College of Arts and Sciences. Matt Meiselman, a postdoctoral associate
in Yapici's lab, is the paper's first author.

In the study, the researchers conducted genetic screens and identified
a subset of circadian neurons in the fly brain. These circadian neurons
are important for sensing and responding to such environmental cues
as light and cold and for keeping time in the brain, but they are not
well understood. The researchers decided to investigate whether these
circadian cells could be involved in the interplay between reproduction
and environmental cues such as light and temperature.

They found that while light may have some effect on reproduction,
as a short day corresponds to the winter season, cold temperatures
dominate light in controlling reproduction. In experiments where fruit
flies were exposed to long days and cold temperatures, the rate of egg production still slowed down. They also used electrodes in the flies'
brains to show that the dorsal neurons were active in warm temperatures
and inactive in cold temperatures.

"These dorsal neurons are sensing the temperature and telling the brain it
is cold out there, and to slow the rate of egg production," Yapici said.

Once the neurons were identified, the scientists asked whether there
might be specific genes expressed in these cells. Their investigation
revealed an insect neuropeptide (signaling protein) called Allotostatin
(AstC) is expressed specifically in these circadian neurons. Experiments
showed that both injecting AstC or over-expressing the neuropeptide from
the dorsal neurons stimulated egg production. Furthermore, AstC gene
expression was also regulated by temperature, levels of AstC was low at
cold temperatures and increased in in warm temperatures. "It looks like
both the dorsal neuron activity and the neuropeptide expression decrease
in the cold," Yapici said.

The researchers also discovered the receptor that the AstC neuropeptide
binds with to activate egg production.

In future work, Yapici and colleagues plan to generate mutant mosquitos
for the AstC peptide and its receptor to further understand their roles
in regulating egg production in mosquitos. If modifying the AstC receptor reduces reproduction, it could become a target for chemical intervention
that could suppress mosquito and agricultural pest populations.

"Understanding how animals cope with environmental stressors is very
critical in the age of climate change," Yapici said, noting that
analogous genes and neurons are also found in vertebrates, including
mammals. "We are fascinated by how our brains might be sensing changes in
the environment and regulating our physiological functions accordingly."
The study was supported by the National Institutes of Health.

========================================================================== Story Source: Materials provided by Cornell_University. Original written
by Krishna Ramanujan, courtesy of the Cornell Chronicle. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Matthew R. Meiselman, Michael H. Alpert, Xinyue Cui, Jamien
Shea, Ian
Gregg, Marco Gallio, Nilay Yapici. Recovery from cold-induced
reproductive dormancy is regulated by temperature-dependent AstC
signaling. Current Biology, 2022; DOI: 10.1016/j.cub.2022.01.061 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220217134747.htm

--- up 10 weeks, 5 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)