Raising tilapia is easy and inexpensive. It adapts well to fresh or salt water and fattens fast. Unlike most salmoniforms in aquaculture (salmon, trout, perch, bream), for which fishmeal and fish oil constitute an essential part of their diet, tilapia is lower down in the trophic or food chain and feeds on algae, plankton or small animals. In extensive and semi-extensive production systems, tilapia is largely fed on vegetable waste (rice, cotton, etc.).
Thus, with output exceeding 2 million tons each year, tilapia production contributes to sustainable development without damaging marine resources. This is one of the arguments put forward to support research into the complete sequencing of the tilapia genome. In addition, it is one of two species of interest to aquaculture which is being studied more than any other in laboratories.
Sex determination at the service of aquaculture
This model fish belongs to the order percomorphs which includes many French and European species, such as perch, bream and pargo bream. These fish take a long time to reach sexual maturity, which means that their genetic study is not easy. As tilapia has a short generation gap, it can be used as a study model for improving percomorphs. It is also the main group used for studying the phenomena of speciation (birth of a new species).
Of the 10 laboratories involved in the tilapia genome sequencing project, CIRAD and Stirling University of Aquaculture (Great Britain), are particularly interested in the benefits that the project may represent for aquaculture. They are researching genes linked to characteristics of interest, such as growth, rusticity, sex ratio (proportion of males to females), etc.
The tilapia breeders are calling on research for the selection of male tilapias, which grow much faster than the females. The CIRAD research unit Aquaculture and aquatic resource management is developing research programmes to find a real hormone-free alternative for producing single sex male populations. Research into genetics and the use of breeding conditions could provide solutions to the danger of hormones in food, human health and the preservation of biodiversity.
”High water temperature may influence the sex of fingerlings, so we are genetically selecting parents in the hope that the progeny will have this heritable characteristic, “ explains Jean-François Baroiller, a scientist at the research unit Aquaculture and aquatic resource management. Genetic markers for thermal sensitivity are used to optimise this kind of selection and also to study individuals of interest within the natural diversity of tilapias. A similar approach has been set up to develop tilapias resistant to high variations in water salinity in order to meet the demand of numerous producing countries.
The expected development of the first sequences will complete numerous specific genome resources for tilapia that have already been developed by CIRAD. Three PhD students from the research unit Aquaculture and aquatic resource management are working full-time on these issues in collaboration with international research organisations. The sequencing project is already of considerable benefit to the scientific community as well as for world aquaculture.* CIRAD (France)
Helen Burford | alfa
Kakao in Monokultur verträgt Trockenheit besser als Kakao in Mischsystemen
18.09.2017 | Georg-August-Universität Göttingen
Ultrasound sensors make forage harvesters more reliable
28.08.2017 | Fraunhofer-Institut für Zerstörungsfreie Prüfverfahren IZFP
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy