Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tilapia fish: Ready for mating at the right time

01.09.2014

Researchers identify a pheromone in the urine of male tilapia fish that stimulates spawning in females

The exchange of chemical signals between organisms is considered the oldest form of communication. Acting as messenger molecules, pheromones regulate social interactions between conspecifics, for example, the sexual attraction between males and females. Fish rely on pheromones to trigger social responses and to coordinate reproductive behavior in males and females.


Male Mozambique tilapia (Oreochromis mossambicus).

© Olinda G. Almeida / Peter C. Hubbard, Centre of Marine Sciences (CCMAR), Universität der Algarve, Faro, Portugal


Rival male Mozambique tilapias in an aquarium: The dominant male (right) defends the nest, an excavation in the sand he made with his mouth. Females take up the eggs in their mouths, once they have been externally fertilized in the nest by the males. Oral incubation is a strategy for protecting offspring.

© Peter C. Hubbard / Olinda G. Almeida, University of the Algarve, Faro, Portugal

Scientists at the Marine Science Center at the University of the Algarve in Faro, Portugal, and at the Max Planck Institute for Chemical Ecology in Jena, Germany, have now identified such a signal molecule in the urine of male Mozambique tilapia (Oreochromis mossambicus): this pheromone boosts hormone production and accelerates oocyte maturation in reproductive females. Hence, the Mozambique tilapia is one of the first fish species in which the chemical structure of a pheromone has been identified and the biological basis of its activity elucidated.

The social behavior of Mozambique tilapias (Oreochromis mossambicus) native to southern Africa is very complex. The strict hierarchic ranking among males is fought out in so-called courtship arenas. With their mouths, male tilapias make excavations in the sand in the middle of an arena with the aim of attracting females to spawn in these nests.

At the same time, they act aggressively to keep other males away. Dominant males have been observed to urinate more often and squirt larger quantities of urine in the water during fights compared to their subordinate rivals. The urine contains pheromones that reduce aggressive behavior in other males. The compounds also lure females to the nest and modify their hormonal status by accelerating oocyte maturation. Thus the pheromones help to synchronize female spawning and external fertilization by the males and so to increase the odds of reproductive success.

Tilapias also show this behavior in captivity, which makes them an ideal model system for reproducible biological assays. Tina Keller-Costa and her colleagues at the Marine Science Center at the University of the Algarve in Faro, Portugal, as well as the Biosynthesis/NMR Research Group at the Max Planck Institute for Chemical Ecology in Jena, Germany, have now identified the chemical structure of the signaling molecules in tilapia males and studied their function. She collected urine samples from dominant males and purified the samples in several steps, testing them for biological activity as pheromones after each step.

Two steroids as main components in the urine

This procedure resulted in two pure substances whose chemical structures were elucidated using nuclear magnetic resonance spectroscopy (NMR). Their identity was confirmed by chemical synthesis: “The two structures are stereoisomers or mirror images of a pregnane-type steroid linked to glucuronic acid,” Bernd Schneider, the head of the NMR lab in Jena, said, summarizing the results of the analysis.

Both males and females showed highly sensitive responses to the odor of these two steroids. Although the two pheromone components stimulate the hormonal system of the females and trigger spawning, they are not by themselves capable of reducing aggressive behavior in rival males. The researchers thus assume that the urine of dominant males must contain additional yet-to-be identified substances that contribute to this effect in a complex mixture.

Until now only very few fish pheromones have been chemically identified. “Our discovery will allow for further investigations, for example, of the mechanisms of perception and processing of these chemical signals by the brain in order to originate a response, in this case oocyte maturation and behavioral changes,” says Tina Keller-Costa, who conducted the experiments for her PhD thesis.

Ways to control invasive fish species and benefits for the aquaculture of food fish

Apart from the carp family, tilapias belong to the most important edible fish raised commercially. However, their aquaculture in many tropical and subtropical waters has led to an uncontrolled population growth and spread of the species. The use of pheromones could help optimize the aquaculture of tilapia species by increasing female fertility and reducing aggression between competing males. Pheromones could also help to control the invasive behavior of these fish, which threatens the ecological balance of many ecosystems.

Contact 

Dr. Bernd Schneider

Max Planck Institute for Chemical Ecology, Jena

Phone: +49 3641 57-1600

 

Angela Overmeyer

Press and Public Relations

Max Planck Institute for Chemical Ecology, Jena

Phone: +49 3641 57-2110

 

Original publication

 
Keller-Costa, T., Hubbard, P.C., Paetz, C., Nakamura, Y., da Silva, J. P., Rato, A., Barata, E. N., Schneider, B., Canario, A. V. M.
Identity of a tilapia pheromone released by dominant males that primes females for reproduction.
Current Biology, DOI: 10.1016/j.cub.2014. 07.049

Dr. Bernd Schneider | Max-Planck-Institut

Further reports about: Chemical Ecology aquaculture females invasive pheromones publication species steroids tilapia urine

More articles from Life Sciences:

nachricht Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View
22.06.2018 | University of Sussex

nachricht New cellular pathway helps explain how inflammation leads to artery disease
22.06.2018 | Cedars-Sinai Medical Center

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>