Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Toxic fruits hold the key to reproductive success

09.12.2014

A dopamine precursor in the toxic fruits of the morinda tree increases fertility in female Drosophila sechellia flies. Drosophila sechellia females, which lay their eggs on these fruits, carry a mutation in a gene that inhibits egg production.

The flies have very low levels of L-DOPA, a precursor of the hormone dopamine, which controls fertility; interestingly, large amounts of L-DOPA are contained in morinda fruits. Flies that were fed with L-DOPA can compensate for the genetic deficiency and considerably increase their reproductive success.


The Morinda citrifolia fruit, also called noni fruit, contains toxic acids. Nevertheless, the fruit is the sole host of Drosophila sechellia fruit flies. Anna Schroll


Ovary (specifically stained) of a female Drosophila sechellia fruit fly raised outside its host. Without L-DOPA in its food, oogenesis is halted.

Sofia Lavista Llanos, Max Planck Institute for Chemical Ecology

In the course of evolution, animals have become adapted to certain food sources, sometimes even to plants or to fruits that are actually toxic. The driving forces behind such adaptive mechanisms are often unknown. Scientists at the Max Planck Institute for Chemical Ecology in Jena, Germany, have now discovered why the fruit fly Drosophila sechellia is adapted to the toxic fruits of the morinda tree.

Drosophila sechellia females, which lay their eggs on these fruits, carry a mutation in a gene that inhibits egg production. The flies have very low levels of L-DOPA, a precursor of the hormone dopamine, which controls fertility; interestingly, large amounts of L-DOPA are contained in morinda fruits.

Flies that were fed with L-DOPA can compensate for the genetic deficiency and considerably increase their reproductive success. The same gene mutation also contributes to the resistance that these flies have to the toxic acids produced in the fruits and killing all other fruit fly species. (eLife, December 2014)

Drosophila sechellia is a fruit fly species closely related to Drosophila melanogaster. It is endemic to the Seychelles archipelago in the Indian Ocean and a specialist on its only host, Morinda citrifolia. The flies are strongly attracted by the fruits of the morinda tree: they feed on its fruits, and females prefer to lay their eggs on these. Contact with ripe morinda fruits kills other Drosophila species.

Female Drosophila sechellia flies produce fewer eggs than do other fruit flies. Therefore it is difficult to raise this species in the laboratory. However, if these flies are provided with morinda fruits or chemicals from these fruits, fertility in females increases considerably.

Sofia Lavista Llanos, Bill Hansson and their colleagues at the Department of Evolutionary Neuroethology at the Max Planck Institute for Chemical Ecology in Jena, Germany, have now found out why Drosophila sechellia is so dependent on the toxic fruits of their host plant. Feeding assays revealed that Drosophila sechellia females produced six times as many eggs when they were fed a diet of morinda fruit instead of the typical laboratory diet.

Egg production in the flies is controlled by the hormone dopamine. A dopamine deficiency reduces ovary size and the amount of eggs produced. In Drosophila sechellia, scientists found much lower levels of the precursor compound needed for dopamine biosynthesis than was found in other Drosophila species. This dopamine precursor is L-DOPA, a chemical that is used as a psychoactive drug to treat Parkinson’s disease. If L-DOPA is added to their diet, Drosophila sechellia females produce much more eggs than if the drug is not present. This effect is not achieved if dopamine itself is added to the food. The scientists were not too surprised when analyses revealed that morinda contains L-DOPA.

A genetic comparison with other Drosophila species showed that Drosophila sechellia carries a mutation in a gene called Catsup. This mutation inhibits egg production in females. “When we mutated the Catsup gene in the model species Drosophila melanogaster, the mutant flies showed the same characteristics as Drosophila sechellia: They produced fewer eggs and accumulated an enzyme which makes L-DOPA inside their developing eggs,” explains Sofia Lavista Llanos. On the other hand, the Catsup mutation provides Drosophila sechellia with an increased resistance to the toxic acids of the morinda fruit.

In Drosophila sechellia early resistance is partly achieved by the fact that the Catsup mutation makes the flies ovoviviparous, which means that females lay advanced embryos with a protective skin (cuticle) that shields the offspring from the toxic environment of their host plant. The Catsup mutation is also responsible for the bigger size of Drosophila sechellia embryos, which are almost three times as big as the embryos of other drosophilids. The scientists showed that this increases their hatchability on morinda, probably as a result of the augmented buffering capacity of the embryos.

Fruit flies are usually attracted by low levels of fruity odors, yet highly concentrated odors are repulsive to them. This is not true for Drosophila sechellia: “As we showed in earlier studies, these flies show a persistent attraction to extremely high concentrations of morinda odors without being repulsed,” says Bill Hansson. The scientists showed that feeding dopamine to vulnerable fruit fly species helped them cope with the toxic effects of morinda. Now they want to find out if dopamine also influences the strong attraction that Drosophila sechellia shows towards its only host.

The enzymes involved in the dopamine synthesis are conserved across species boundaries in invertebrates and vertebrates. “Drosophila sechellia could serve as a useful genetic model organism in which to study dopamine metabolism. Its close relationship to Drosophila melanogaster is a great advantage, because it provides over 50 years of accumulated knowledge,” says Sofia Lavista Llanos. The etiology and effects of dopamine deficiency are of particular interest in medical research: Dopamine is an important neurotransmitter and controls physiological processes, also in humans. Low levels of the “pleasure” hormone dopamine result in fatigue and depression. Patients with Parkinson’s disease also suffer from very low dopamine levels. Fundamental knowledge of the genetic and biochemical processes associated with L-DOPA deficiency in Drosophila sechellia may also contribute to understanding dopamine metabolism in humans. [AO]

Original Publication:
Lavista Llanos, S., Svatoš, A., Kai, M., Riemensperger, T., Birman, S., Stensmyr, M. C., Hansson, B. S. (2014). Dopamine drives Drosophila sechellia adaptation to its toxic host. eLife 2014;3:e03785, DOI: 10.7554/eLife.03785
http://dx.doi.org/10.7554/eLife.03785

Further Information:
Dr. Sofia Lavista Llanos, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Germany, Tel. +49 3641 57- 1465, E-Mail slavista-llanos@ice.mpg.de
Prof. Dr. Bill S. Hansson, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Germany, Tel. +49 3641 57- 1401, E-Mail hansson@ice.mpg.de

Picture Requests:
Angela Overmeyer M.A., Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, +49 3641 57-2110, overmeyer@ice.mpg.de

Download of high resolution images via http://www.ice.mpg.de/ext/735.html


Weitere Informationen:

http://www.ice.mpg.de/ext/1176.html?&L=0
http://www.ice.mpg.de/ext/735.html

Angela Overmeyer | Max-Planck-Institut für chemische Ökologie

More articles from Life Sciences:

nachricht Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology

nachricht The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides

16.07.2018 | Life Sciences

New research calculates capacity of North American forests to sequester carbon

16.07.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>