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Why do rodents' teeth stay sharp? What is the difference between the mouse and the kangaroo?
November 10, 2004Answers to these two questions are given by two recent studies on tooth development and evolution. Scientists at the University of Helsinki have identified the gene responsible for tooth enamel formation, which also explains the sharp incisors of rodents. The second study adds to our knowledge on evolution: the differences between teeth in various species, which have been utilised in evolution research, can be altered through one signalling molecule that regulates development. The research findings will be published this week in two leading scientific journals, Developmental Cell and Nature.
"Enamel gene" explains why rodents' teeth stay sharp
Scientists at the University of Helsinki Institute of Biotechnology have, in collaboration with their American and Swiss colleagues, identified a novel function for a gene which codes a crucially important signalling molecule, BMP (bone morphogenetic protein). BMP initiates the development of enamel and is, thereby, vital for the formation of enamel.
The scientists have also shown that BMP, together with its specific inhibitor follistatin, explain the special characteristic of rodents' incisors, their sharp, cutting edge, which stays sharp although the rest of the incisors are worn by gnawing. The sharp edge is caused by the inhibition of BMP signalling molecule in the inner surface of the tooth so that enamel is built only on the outer surface. Thanks to the enamel, the outer surface is harder and will not wear as fast as the inner surface, and a sharp edge is formed at the point where the two surfaces meet.
The fine-tuning of various signalling molecules is the most important mechanism regulating the shape of tissues and organs. The mouse incisor is an illustrative example of how local differences in the activities of the signalling molecules determine the generation of complex structures.
The scientists participating in the study at the University of Helsinki were Xiu-Ping Wang and Marika Suomalainen from the Research Program in Developmental Biology - one of the national Centres of Excellence in Research - and Professor Irma Thesleff, the director of the unit. The results were published in Developmental Cell on 9 November.
One gene brings back teeth of mouse ancestors from 45 million years ago
Tooth fossils are the only remains of many extinct mammals. There are several details in the teeth of different species by which scientists determine the kinship between species. The University of Helsinki evolutionary biologists have shown that several of these characteristics used in evolution research can be changed with one signalling molecule regulating individual development.
The scientists discovered that when the production of a signalling molecule ectodysplasin is increased during development, the mouse teeth develop structures that can be found, for example, in the teeth of the kangaroo. Increasing the secretion of ectodysplasin also causes the mouse to have an extra tooth in a place where the ancestral form of rodents 45 million years ago still had a tooth. If the secretion of ectodysplasin is decreased, however, the mouse's teeth lose several structures.
The results are beneficial to evolutionary biologists in determining the kinship relations between species, and for developmental biologists when studying why closely related species, such as the chimpanzee and human, have so many structural differences.
The study was conducted by Aapo Kangas, Alistair Evans, Irma Thesleff and Jukka Jernvall from the University of Helsinki Institute of Biotechnology. The study belongs to the field of evolution and developmental biology and its results will be published in Nature on 11 November.
Helsingin yliopisto (University of Helsinki)
The scientists have also shown that BMP, together with its specific inhibitor follistatin, explain the special characteristic of rodents' incisors, their sharp, cutting edge, which stays sharp although the rest of the incisors are worn by gnawing. The sharp edge is caused by the inhibition of BMP signalling molecule in the inner surface of the tooth so that enamel is built only on the outer surface. Thanks to the enamel, the outer surface is harder and will not wear as fast as the inner surface, and a sharp edge is formed at the point where the two surfaces meet.
The fine-tuning of various signalling molecules is the most important mechanism regulating the shape of tissues and organs. The mouse incisor is an illustrative example of how local differences in the activities of the signalling molecules determine the generation of complex structures.
The scientists participating in the study at the University of Helsinki were Xiu-Ping Wang and Marika Suomalainen from the Research Program in Developmental Biology - one of the national Centres of Excellence in Research - and Professor Irma Thesleff, the director of the unit. The results were published in Developmental Cell on 9 November.
One gene brings back teeth of mouse ancestors from 45 million years ago
Tooth fossils are the only remains of many extinct mammals. There are several details in the teeth of different species by which scientists determine the kinship between species. The University of Helsinki evolutionary biologists have shown that several of these characteristics used in evolution research can be changed with one signalling molecule regulating individual development.
The scientists discovered that when the production of a signalling molecule ectodysplasin is increased during development, the mouse teeth develop structures that can be found, for example, in the teeth of the kangaroo. Increasing the secretion of ectodysplasin also causes the mouse to have an extra tooth in a place where the ancestral form of rodents 45 million years ago still had a tooth. If the secretion of ectodysplasin is decreased, however, the mouse's teeth lose several structures.
The results are beneficial to evolutionary biologists in determining the kinship relations between species, and for developmental biologists when studying why closely related species, such as the chimpanzee and human, have so many structural differences.
The study was conducted by Aapo Kangas, Alistair Evans, Irma Thesleff and Jukka Jernvall from the University of Helsinki Institute of Biotechnology. The study belongs to the field of evolution and developmental biology and its results will be published in Nature on 11 November.
Helsingin yliopisto (University of Helsinki)
Evolution Current Events and Evolution News RSSWe're off then: the evolution of bat migration
Not just birds, but also a few species of bats face a long journey every year. Researchers at Princeton University in the U.S. and at the Max Planck Institute for Ornithology in Radolfzell, Germany studied the migratory behaviour of the largest extant family of bats, the so-called "Vespertilionidae" with the help of mathematical models.
Insect Resistance to Bt Crops can be Predicted, Monitored, and Managed
Since 1996, crop plants genetically modified to produce bacterial proteins that are toxic to certain insects, yet safe for people, have been planted on more than 200 million hectares worldwide.
Multiple health concerns surface as winter, vitamin D deficiences arrive
A string of recent discoveries about the multiple health benefits of vitamin D has renewed interest in this multi-purpose nutrient, increased awareness of the huge numbers of people who are deficient in it, spurred research and even led to an appreciation of it as "nature's antibiotic."
Supervolcano eruption -- in Sumatra -- deforested India 73,000 years ago
A new study provides "incontrovertible evidence" that the volcanic super-eruption of Toba on the island of Sumatra about 73,000 years ago deforested much of central India, some 3,000 miles from the epicenter, researchers report.
Is global warming unstoppable?
In a provocative new study, a University of Utah scientist argues that rising carbon dioxide emissions - the major cause of global warming - cannot be stabilized unless the world's economy collapses or society builds the equivalent of one new nuclear power plant each day.
Scientists at UA, collaborating institutions decode maize genome
Scientists from the University of Arizona led by Arizona Genomics Institute director Rod A. Wing and from collaborating institutions have deciphered the complete genetic code of the maize plant for the first time.
New Maize Map to Aid Plant Breeding Efforts
In a massive survey of genetic diversity in maize, also known as corn, researchers across the United States, have developed a gene map that should pave the way to significant improvements in a plant that is a major source of food, fuel, animal feed and fiber around the world.
'Hobbits' are a new human species -- according to the statistical analysis of fossils
Researchers from Stony Brook University Medical Center in New York have confirmed that Homo floresiensis is a genuine ancient human species and not a descendant of healthy humans dwarfed by disease.
Research challenges for understanding landscape changes identified
Nine research challenges and four research initiatives that are poised to advance the study of how Earth's landscapes change were unveiled today in a new report by the National Research Council.
Scientists Unravel Evolution of Highly Toxic Box Jellyfish
With thousands of stinging cells that can emit deadly venom from tentacles that can reach ten feet in length, the 50 or so species of box jellyfish have long been of interest to scientists and to the public. Yet little has been known about the evolution of this early branch in the animal tree of life.
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