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Uncovering the internal rhythms of flagella
New findings by European scientists are opening the way to increasing our knowledge of conditions such as infertility, which are still not completely understood. The findings concern flagella in particular: these structures are named from the Latin word for whip, because they resemble a whip that extends from certain prokaryotic and eukaryotic cells.
These flagella are very small, but despite their size, the rhythmic beats they create as they wave back and forth can generate motion. They are responsible for the propulsion of single cells such as the swimming of sperm (the tail end of the sperm is the flagellum), and moving eggs from the ovary to the uterus, as well as other vital functions in the human body.
The findings were made possible thanks to funding by the European Research Council (ERC), the Portuguese Fundação para a Ciência e Tecnologia (FCT) and the European Molecular Biology Organization (EMBO).
The European scientists based at the Instituto Gulbenkian de Ciência (IGC) in Portugal analysed how sperm cells of the fruit fly build their flagella, and published their results in the latest issue of the journal Developmental Cell. This is the first time ever that the different steps involved in the actual construction of motile flagella in sperm cells of the fruit fly (Drosophila melanogaster) have been described. By understanding how these flagella work, the scientists hope that they then can better understand conditions and disorders such as infertility, respiratory problems and hydrocephaly, which are associated with defects in flagella movements.
The team, led by Monica Bettencourt-Dias, focused their efforts on when and how a critical protein structure, called the central microtubule pair, is formed. The central microtubule pair complex is what allows the flagella to move in a coordinated fashion.
Zita Carvalho-Santos, a postdoctoral researcher, explains their findings: 'We looked at a particular fly gene, called Bld10, and found that flies in which this gene is inactive produce sperm with incomplete flagella because, it seems, the Bld10 protein is essential for the central microtubule pair to form. As a result, mutant sperm are immobile, and male flies are infertile. Humans have an analogous gene that produces a similar protein, which has been linked to male infertility.'
These findings were made possible through the use of electron microscopy that uses electrons, as opposed to traditional light-powered optical microscopes. Electron microscopes are able to achieve magnifications of 10 000 000 times. To put this in context, this type of magnification allows them to see things that are 3 500 times thinner than a strand of human hair. Scientists have used them to examine specimens such as microorganisms, cells and crystals.
Monica Bettencourt-Dias added: 'We found that the process is much more dynamic than we had anticipated: first a single microtubule chain forms, and then the second. Our work has provided several long-awaited answers, but also raised other questions, that studying sperm formation in Drosophila may answer.'
This study was carried out in collaboration between the researchers at the IGC and the Instituto de Tecnologia Química e Biológica (ITQB), also in Portugal. Zita Carvalho-Santos and Pedro Machado (IGC) contributed equally to the work.
Contact person:For more information, please visit:
Instituto Gulbenkian de Ciência
European Research Council
European Molecular Biology Organization
Data Source Provider:Instituto Gulbenkian de Ciência; Developmental Cell
Document of reference:Zita Carvalho-Santos et al., 'BLD10/CEP135 is a microtubule-associated protein that controls the formation of the flagellum central microtubule pair', Developmental Cell, 23: 1-13, 2012.
Subject index:Biotechnology,Medical biotechnology,Medicine, Health,Nanotechnology and Nanosciences
Programme Acronym: MS-P C
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