Search results for "Molecular Evolution"
showing 10 items of 117 documents
Phylogenetic analysis of the thiolase family. Implications for the evolutionary origin of peroxisomes
1992
The thiolase family is a widespread group of proteins present in prokaryotes and three cellular compartments of eukaryotes. This fact makes this family interesting in order to study the evolutionary process of eukaryotes. Using the sequence of peroxisomal thiolase from Saccharomyces cerevisiae recently obtained by us and the other known thiolase sequences, a phylogenetic analysis has been carried out. It shows that all these proteins derived from a primitive enzyme, present in the common ancestor of eubacteria and eukaryotes, which evolved into different specialized thiolases confined to various cell compartments. The evolutionary tree obtained is compatible with the endosymbiotic theory fo…
Rapid radiation of North American desert genera of the Papaveraceae: Evidence from restriction site mapping of PCR-amplified chloroplast DNA fragments
1995
Phylogenetic relationships of a group of North American desert genera of the Papaveraceae subfam. Papaveroideae and Platystemonoideae were investigated with an RFLP analysis of three PCR-amplified chloroplast genome regions. In agreement with earlier results it was found that subfam. Platystemonoideae is nested within subfam. Papaveroideae. The group under study is characterized by a large number of generic autapomorphies but only few informative synapomorphies. This is interpreted as strong evidence for a rapid radiation event caused by major climatic changes in the past. Poor phylogenetic resolution seems to reflect biological reality and not to be an experimental artifact. There is also …
Different mechanisms generating sequence variability are revealed in distinct regions of the hydroxyproline-rich glycoprotein gene from maize and rel…
1992
The sequences of the genes coding for a hydroxyproline-rich glycoprotein from two varieties of maize (Zea mays, Ac1503 and W22), a teosinte (Zea diploperennis) and sorghum (Sorghum vulgare) have been obtained and compared. Distinct patterns of variability have been observed along their sequences. The 500 bp region immediately upstream of the TATA box is highly conserved in the Zea species and contains stretches of sequences also found in the sorghum gene. Further upstream, significant rearrangements are observed, even between the two maize varieties. These observations allow definition of a 5' region, which is common to the four genes and is probably essential for their expression. The 3' e…
Quasispecies dynamics and molecular evolution of human norovirus capsid P region during chronic infection.
2009
In this novel study, we have for the first time identified evolutionarily conserved capsid residues in an individual chronically infected with norovirus (GGII.3). From 2000 to 2003, a total of 147 P1-1 and P2 capsid sequences were sequenced and investigated for evolutionarily conserved and functionally important residues by the evolutionary trace (ET) algorithm. The ET algorithm revealed more absolutely conserved residues (ACR) in the P1-1 domain (47/53, 88 %) as compared with the P2 domain (86/133, 64 %). The capsid P1-1 and P2 domains evolved in time-dependent manner, with a distinct break point observed between autumn/winter of year 2000 (isolates P1, P3 and P5) and spring to autumn of y…
Temperature-dependence of spontaneous mutation rates
2020
Mutation is the source of genetic variation and the fundament of evolution. At the interphase of ecology and evolution, temperature has long been suggested to have a direct impact on realised spontaneous mutation rates. The question is whether mutation rates can be a species-specific constant under variable environmental conditions, such as variation of the ambient temperature. By combining mutation accumulation with whole genome sequencing in a multicellular organism, we provide empirical support to reject this null hypothesis. Instead mutation rates depend on temperature in a U-shaped manner with increasing rates towards both temperature extremes. This relation has important implications …
Distinct Clones of Yersinia pestis Caused the Black Death
2010
From AD 1347 to AD 1353, the Black Death killed tens of millions of people in Europe, leaving misery and devastation in its wake, with successive epidemics ravaging the continent until the 18th century. The etiology of this disease has remained highly controversial, ranging from claims based on genetics and the historical descriptions of symptoms that it was caused by Yersinia pestis to conclusions that it must have been caused by other pathogens. It has also been disputed whether plague had the same etiology in northern and southern Europe. Here we identified DNA and protein signatures specific for Y. pestis in human skeletons from mass graves in northern, central and southern Europe that …
Molecular evolution of tomato black ring virus and de novo generation of a new type of defective RNAs during long‐term passaging in different hosts
2020
Tomato black ring virus (TBRV) is a worldwide-distributed RNA virus infecting a wide range of different host plants, including crop species, trees, shrubs, and weeds. Here, we investigated the molecular evolution of TBRV and its adaptability to different plant species. The TBRV-Pi isolate was used to generate five independent evolution lineages serially passaged in either quinoa, tobacco, or tomato plants. After 15 passages, the genetic variability present in all the lineages was characterized for the movement (MP) and coat (CP) coding cistrons. We addressed two main questions: to what extent does the amount of genetic variability in the TBRV genome depend on the host species, and are there…
Molecular Evolution of Lactate Dehydrogenase in the Developing Nervous Tissue*
1964
Publisher Summary This chapter describes both electrophoretic and catalytic studies on lactate dehydrogenase (LDH) in the developing brain. It has been found that the enzyme exhibits at birth a composition that gradually changes to attain the final pattern observed in the adult. The neurochemical findings on LDH isozymes parallel the rapid growth in the first days after birth. Isozyme E, which is not present in detectable amounts 2 days after birth, represents 15% of the enzyme on the 22nd day. Similarly, the percentage decrease of isozyme B is quite steep at the beginning. Nevertheless, the final pattern is attained only at the end of the 2nd month that is, when the cerebral cortex is full…
Evolutionary site-number changes of ribosomal DNA loci during speciation: complex scenarios of ancestral and more recent polyploid events.
2015
Genes encoding ribosomal RNA are universal key constituents of eukaryotic genomes, but the number of loci varies between species. We assessed the evolutionary trends in site-number changes of rDNA loci during speciation in a lineage of the cabbage family, characterized by complex scenarios of polyploidy. Our results suggest the existence of constrictions to burst loci amplification in the 5S rDNA family in polyploids and an overall trend to further reduce their number. The 45S rDNA site change in polyploids tells a different story, implying loci amplification in most of the polyploid entities.
Convergent Loss of Chemoreceptors across Independent Origins of Slave-Making in Ants
2022
The evolution of an obligate parasitic lifestyle often leads to the reduction of morphological and physiological traits, which may be accompanied by loss of genes and functions. Slave-maker ants are social parasites that exploit the work force of closely related ant species for social behaviours such as brood care and foraging. Recent divergence between these social parasites and their hosts enables comparative studies of gene family evolution. We sequenced the genomes of eight ant species, representing three independent origins of ant slavery. During the evolution of eusociality, chemoreceptor genes multiplied due to the importance of chemical communication in societies. We investigated ev…