Regulatory process for organ scaling discovered

October 25, 2011

A new study has shed light on the process by which fruit flies develop with their body proportions remaining constant. The study, conducted by the research group of Professor Markus Affolter at the Biozentrum of the University of Basel and Sven Bergmann's group at the Department of Medical Genetics, University of Lausanne, has demonstrated that the morphogen Dpp and the feedback regulator Pentagone are key factors responsible for proportional tissue growth in wings of a fruit fly. This process keeps the body plan of the fruit fly Drosophila constant. Their research results, published October 25 in the online, open-access journal PLoS Biology, might also be important for organ growth in other organisms.

One of the most interesting and perhaps mysterious questions in developmental biology is to understand how organisms develop from an embryo to an adult with their body proportions remaining constant over generations. External factors such as nutrition and temperature generally impact the overall size of an organism, but leave body proportions unaffected. Fish kept in too small aquaria, for example, just grow proportionally smaller and flies kept under starving conditions have proportionally smaller heads, abdomens, legs and wings. The phenomenon of keeping proportions during growth is called 'scaling' and has been subject of study for decades. Indeed, how scaling is achieved has, until recently, not been very well understood.

In an attempt to solve open questions regarding scaling, Affolter's and Bergmann's research groups have made a large step forward. In the new study they analyze the scaling process of the Drosophila wing; more specifically the insect's wing imaginal disc, the precursor tissue of the adult wing. Using a combination of experimental and mathematical approaches, they could demonstrate that the morphogen called Decapentaplegic (Dpp) plays a central role in regulating and scaling wing growth and patterning via the regulation of Pentagone. A morphogen produces different cellular responses depending on its concentration, and the two groups found that, as the disc grows, the Dpp response expands and scales with the tissue size. Naturally, the morphogen itself needs to be regulated and controlled. In this study, they identify Pentagone, one of Dpp's recently discovered transcriptional targets, as the first negative feedback controller responsible for scaling. Hence, scaling is achieved in the wing due to the feedback loop between the signaling activity of Dpp and its regulator Pentagone. Besides this, Affolter's and Bergmann's groups could also show that scaling is not perfect at all positions during wing disc growth and that scaling of the target gene domains is best where they have a function.

Affolter's and Bergmann's groups used the wing of the fruit fly Drosophila as a model to study scaling quantitatively during growth. Similar to the micro-macro link - a term used in social sciences - scaling is defined as the preservation of proportions of gene expression domains with tissue size during growth. In other words, proportions found on the micro-level of gene expression are found on the macro-level of wing formation. "Better insight into the molecular control of scaling will have large consequences for the understanding of how nature has developed such robust body plans", explains Affolter.
-end-
Funding: SystemsX.ch within the framework of the WingX RTD, the Swiss National Science Foundation, the Kantons of Basel-Stadt and Basel-Land and the International Human Frontier Science Program Organization (LT000234-2009) supported this work. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Citation: Hamaratoglu F, de Lachapelle AM, Pyrowolakis G, Bergmann S, Affolter M (2011) Dpp Signaling Activity Requires Pentagone to Scale with Tissue Size in the Growing Drosophila Wing Imaginal Disc. PLoS Biol 9(10): e1001182. doi:10.1371/journal.pbio.1001182

PLOS

Related Fruit Fly Articles from Brightsurf:

What can you learn by peering into a fruit fly's gut? It turns out a lot!
They say a picture is worth 1,000 words. But what about a real-time window into the complexity of the gastrointestinal system?

Study gives the green light to the fruit fly's color preference
In a study published in the journal Nature on Wednesday, University of Miami researchers made two unexpected discoveries.

Maleness-on-the-Y: A novel male sex determiner in major fruit fly pests
Becoming a male Mediterranean fruit fly relies on the newly identified Y-chromosome linked gene -- Maleness-on-the-Y (MoY) -- which encodes the small protein required to signal male sex determination during development, a new study shows.

Why so fly: MU scientists discover some fruit flies learn better than others
Fruit flies could one day provide new avenues to discover additional genes that contribute to a person's ability to learn and remember.

Fruit fly wing research reshapes understanding of how organs form
How do fruit flies grow their wings? Rutgers scientists discovered a surprising answer that could one day help diagnose and treat human genetic diseases.

Fruit fly promiscuity alters the evolutionary forces on males
Researchers in the Department of Zoology at Oxford University have demonstrated for the first time what effect female fruit flies having multiple partners has on sexual selection -- before and after mating.

Fruit fly protein could be new tool in tackling disease-carrying mosquitos
An insulin-binding protein in fruit flies could provide new opportunities for tackling disease-carrying mosquitos, such as malaria and yellow fever, scientists at the University of York have found.

Guiding flight: The fruit fly's celestial compass
Fruit flies use the sun to avoid flying in circles, according to new research.

When confronted, a single neuron helps a fruit fly change course
In the fruit fly, a single pair of brain neurons command backward locomotion in both larvae and adults, researchers report.

Fecal deposits reveal the fruit fly's pheromone flag
Fruit flies have a rich language of smell messages that they exchange, but now their secret is out.

Read More: Fruit Fly News and Fruit Fly Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.