8 research outputs found
Discordant introgression in a rapidly expanding hybrid swarm
The erosion of species boundaries can involve rapid evolutionary change. Consequently, many aspects of the process remain poorly understood, including the formation, expansion, and evolution of hybrid swarms. Biological invasions involving hybridization present exceptional opportunities to study the erosion of species boundaries because timelines of interactions and outcomes are frequently well known. Here, we examined clinal variation across codominant and maternally inherited genetic markers as well as phenotypic traits to characterize the expansion and evolution of a hybrid swarm between native Cyprinella venusta and invasive Cyprinella lutrensis minnows. Discordant introgression of phenotype, microsatellite multilocus genotype, and mtDNA haplotype indicates that the observable expansion of the C. venusta Ă— C. lutrensis hybrid swarm is a false invasion front. Both parental and hybrid individuals closely resembling C. lutrensis are numerically dominant in the expansion wake, indicating that the non-native parental phenotype may be selectively favored. These findings show that cryptic introgression can extend beyond the phenotypic boundaries of hybrid swarms and that hybrid swarms likely expand more rapidly than can be documented from phenotypic variation alone. Similarly, dominance of a single parental phenotype following an introduction event may lead to instances of species erosion being mistaken for species displacement without hybridization
Growth Hormone Response to Hyperinsulinaemia in Insulin-dependent Diabetics Comparison of Patients With and Without Retinopathy
Functional implications of quasi-equivalence in a T=3 icosahedral animal virus established by cryo-electron microscopy and X-ray crystallography
Transplantation of fetal liver tissue suspension into the spleens of adult syngenic rats: Inducibility of cytochrome P450 dependent monooxygenase functions by β-naphthoflavone, phenobarbital and dexamethasone
Transplantation of fetal liver tissue suspension into the spleens ofadult syngenic rats: Effects of β-naphthoflavone, Phenobarbital and dexamethasone on cytochrome P450 isoforms expression and on glycogen storage
Amplification Of A Gene Encoding A P53-associated Protein In Human Sarcomas
DESPITE extensive data linking mutations in the p53 gene to human tumorigenesis 1, little is known about the cellular regulators and mediators of p53 function. MDM2 is a strong candidate for one such cellular protein; the MDM2 gene was originally identified by virtue of its amplification in a spontaneously transformed derivative of mouse BALB/c cells 2 and the MDM2 protein subsequently shown to bind to p53 in rat cells transfected with p53 genes 3,4. To determine whether MDM2 plays a role in human cancer, we have cloned the human MDM2 gene. Here we show that recombinant-derived human MDM2 protein binds human p53 in vitro, and we use MDM2 clones to localize the human MDM2 gene to chromosome 12q13-14. Because this chromosomal position appears to be altered in many sarcomas 5-7, we looked for changes in human MDM2 in such cancers. The gene was amplified in over a third of 47 sarcomas, including common bone and soft tissue forms. These results are consistent with the hypothesis that MDM2 binds to p53, and that amplification of MDM2 in sarcomas leads to escape from p53-regulated growth control. This mechanism of tumorigenesis parallels that for virally-induced tumours 8,9, in which viral oncogene products bind to and functionally inactivate p53.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62637/1/358080a0.pd