2015年5月11日星期一

Genetic changes to basic developmental processes evolve more frequently than thought -- ScienceDaily

Genetic changes to basic developmental processes evolve more frequently than thought -- ScienceDaily

"The genes that drive embryonic polarity are not conserved across flies and their evolutionary replacement does not seem to be rare at all," said study senior author Urs Schmidt-Ott, PhD, associate professor of organismal biology and anatomy at the University of Chicago. "The hijacking of this early developmental pathway by novel or newly evolved genes happens at a much higher frequency than previously thought."

In the common fruit fly Drosophila and related flies, the gene bicoid determines which end of an embryo will develop into the head and which will become the tail. However, most flies and other insects lack bicoid, and how they establish this head-to-tail polarity has been poorly understood. Early studies of chironomids, a group of mosquito-like midges, found that ultraviolet light or RNAse targeted toward the front portion of embryos led to double-abdomen formation (two tail ends and no head), which suggested that localized RNA in the anterior egg might function as head determinant.

To identify which gene products were being disrupted, Schmidt-Ott's team profiled and compared gene expression levels between the front and rear halves of Chironomus embryos. Out of thousands of candidates, the team identified a specific gene that appeared to be necessary for the formation of head-to-tail polarity. Double-abdomen formation occurred when this gene, called panish, was silenced in early Chironomus embryos. These embryos could be returned to normal with the addition of an independent source of panish gene product.

Although panish and bicoid perform essentially the same function, they are structurally unrelated and found in completely separate families of flies. Both genes act by regulating other genes involved in genetic patterning, but panish represses them while bicoid activates them.

The team found no evidence of panish in flies other than Chironomus, suggesting that panish is a newly evolved gene that appropriated the function of regulating head-to-tail polarity. They also reexamined the occurrence of bicoid and discovered that the gene has been repeatedly lost or substantially altered in certain fruit flies and tsetse flies during evolution.

Despite the importance of head-to-tail patterning in early embryonic development, it appears that genes that regulate the process are poorly conserved in flies, and that new genes took over the role far more often than previously thought.

The discovery of this phenomenon now opens a multitude of new research avenues. Schmidt-Ott and his colleagues are now investigating questions such as how do genes appropriate new roles, why it happens so frequently, and whether such instances share common features.

"It's astonishing how a newly evolved gene can, in a very short amount of time, take over control of such a fundamental process," Schmidt-Ott said. "Given that a small sample of examined genomes already suggests four independent fundamental substitutions, we probably are looking at the 'tip of the iceberg' for these events."


Welcome to SUV System Ltd!

SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.

We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.

SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com

Electronic Components distributor:http://www.suvsystem.com

Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html

IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html

LED Distributor:http://www.suvsystem.com/l/LED-1.html

Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html

Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html

Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html

Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html

SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc

we are focus on the following fields,and hope we can help you.


AVX Resistors TI IC IDT IC PANASONIC LED Kingbrigt LED LITTELFUSE Diodes Electronic News Multi-units Transistors Military IC Zener Diodes Fleld Effect Transistors Microchip IC TOSHIBA Diodes TDK IC Cypress IC Civil IC Bipolar Transistors Chip Fuses TOSHIBA Transistors Diodes Inc Ligitek LED ROHM Resistors IR Diodes Low Ohmic Resistors Thick Film Resistors Transistors SANYO IC AGILENT LED Chip Ferrite Beads IR transistor Resistors Voltage Regulators Transistors Transistors Freescale MOTOROLA IC Fast Recovery Diodes YAGEO Resistors HARRIS IC ELPIDA IC MURATA IC
http://www.suvsystem.com/a/45754.aspx