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Inferences from protein and nucleic acid sequences: early molecular evolution, divergence of kingdoms and rates of change.
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Mosaic genes and RNA processing in mitochondria.
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[Genetics of the immunoglobulins: achievements and problems].
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A new algorithm for analysis of the homology in protein primary structure.
A new algorithm for analysis of the homology and genetic semihomology in protein sequence is described. It assumes the close relation between the compared amino acids and their codons in related proteins. The algorithm is based on the network of the genetic relationship between amino acids and, thus differs from the commonly used statistical matrices. The results obtained by using this method are more comprehensive than used at present, and reflect the actual mechanism of protein differentiation and evolution. They concern: (1) location of homologous and semihomologous sites in compared proteins; (2) precise estimation of insertion/deletion gaps in non-homologous fragments; (3) analysis of internal homology and semihomology; (4) precise location of domains in multidomain proteins; (5) estimation of genetic code of non-homologous fragments; (6) construction of genetic probes; (7) studies on differentiation processes among related proteins; (8) estimation of the degree of relationship among related proteins; (9) studies on the evolution mechanism within homologous protein families and (10) confirmation of actual relationship of sequences showing low degree of homology.
The Y chromosome as a target for acquired and amplified genetic material in evolution.
The special properties of the Y chromosome stem form the fact that it is a non-recombining degenerate derivative of the X chromosome. The absence of homologous recombination between the X and the Y chromosome leads to gradual degeneration of various Y chromosome genes on an evolutionary timescale. The absence of recombination, however, also favors the accumulation of transposable elements on the Y chromosome during its evolution, as seen with both Drosophila and mammalian Y chromosomes. Alongside these processes, the acquisition and amplification of autosomal male benefit genes occur. This review will focus on recent studies that reveal the autosome-acquired genes on the Y chromosome of both Drosophila and humans. The evolution of the acquired and amplified genes on the Y chromosome is also discussed. Molecular and comparative analyses of Y-linked repeats in the Drosophila melanogaster genome demonstrate that there was a period of their degeneration followed by a period of their integration into RNAi silencing, which was beneficial for male fertility. Finally, the function of non-coding RNA produced by amplified Y chromosome genetic elements will be discussed.
Predicting coding function from nucleotide sequence or survival of "fitness" of tRNA.
The sequence of a nucleotide region of f1 bacteriophage was determined on a bonded ultrathin acrylamide gel with a discontinuous buffer system by using the dideoxy-DNA sequencing method. This sequence and one other were analyzed for maximal base pairing with tRNAs. The results allow a prediction of the direction and phase of possible coding functions. The implication of sequence constraints on mRNA codon frequency, tRNA structure, the origin of protein synthesis, and triplet reading are discussed in terms of neutral, Darwinian, and genotypic selectionist perspectives of evolution. The model of F. H. C. Crick, S. Brenner, A. Klug, and G. Pieczenik [(1976) Origins of Life 7, 389-397] for the origin of the genetic code is used to interpet contemporary adaptive and functional nucleic acid sequences.
The evolution of genomic imprinting.
In some mammalian genes, the paternally and maternally derived alleles are expressed differently: this phenomenon is called genomic imprinting. Here we study the evolution of imprinting using multivariate quantitative genetic models to examine the feasibility of the genetic conflict hypothesis. This hypothesis explains the observed imprinting patterns as an evolutionary outcome of the conflict between the paternal and maternal alleles. We consider the expression of a zygotic gene, which codes for an embryonic growth factor affecting the amount of maternal resources obtained through the placenta. We assume that the gene produces the growth factor in two different amounts depending on its parental origin. We show that genomic imprinting evolves easily if females have some probability of multiple partners. This is in conflict with the observation that not all genes controlling placental development are imprinted and that imprinting in some genes is not conserved between mice and humans. We show however that deleterious mutations in the coding region of the gene create selection against imprinting.
Possible evolution of splice-junction signals in eukaryotic genes from stop codons.
Splice-junction sequence signals are strongly conserved structural components of eukaryotic genes. These sequences border exon/intron junctions and aid in the process of removing introns by the RNA splicing machinery. Although substantial research has been undertaken to understand the mechanism of splicing, little is known about the origin and evolution of these splice signal sequences. Based on the previously published theory that the primitive genes evolved in pieces from primordial genetic sequences to avoid the interfering stop codons, a "stop-codon walk" mechanism is proposed in this paper to have assisted in the evolution of coding genes. This mechanism predicts the presence of stop codons in splice-junction signals inside the introns. Evidence of the consistent presence of stop codons in the splice-junction signals, in a position where they are expected, is shown by the analysis of codon statistics in these signal sequences in the GenBank databank. The results suggest that the splice-junction signals may have evolved from stop codons as a consequence of a selective pressure to avoid stop codons during the original evolution of coding genes. They also suggest that other splice signals within the introns, such as the branch-point sequence, may have evolved from stop codons for similar reasons.
Libsequence: a C++ class library for evolutionary genetic analysis.
UNLABELLED: A C++ class library is available to facilitate the implementation of software for genomics and sequence polymorphism analysis. The library implements methods for data manipulation and the calculation of several statistics commonly used to analyze SNP data. The object-oriented design of the library is intended to be extensible, allowing users to design custom classes for their own needs. In addition, routines are provided to process samples generated by a widely used coalescent simulation. AVAILABILITY: The source code (in C++) is available from http://www.molpopgen.org
Incorporation of non-natural amino acids into proteins.
Chemical and biological diversity of protein structures and functions can be widely expanded by position-specific incorporation of non-natural amino acids carrying a variety of specialty side groups. After the pioneering works of Schultz's group and Chamberlin's group in 1989, noticeable progress has been made in expanding types of amino acids, in finding novel methods of tRNA aminoacylation and in extending genetic codes for directing the positions. Aminoacylation of tRNA with non-natural amino acids has been achieved by directed evolution of aminoacyl-tRNA synthetases or some ribozymes. Codons have been extended to include four-base codons or non-natural base pairs. Multiple incorporation of different non-natural amino acids has been achieved by the use of a different four-base codon for each tRNA. The combination of these novel techniques has opened the possibility of synthesising non-natural mutant proteins in living cells.
Functional convergence of regulatory regions provides vital insights into mammalian gliding adaptation.
Uncovering the key genetic basis of complex phenotypic convergence in distantly related species has been a long-standing focus in evolutionary biology and genetics, and the convergent evolution of gliding in mammals offers a valuable opportunity to address this question. Here, we investigated the genomic basis of convergent evolution of gliding in mammals by analyzing both protein-coding genes and conserved non-coding elements (CNEs). We first de novo assembled and annotated two chromosome-level genomes of gliding mammals, the red and white giant flying squirrel (Petaurista alborufus) and sugar gliders (Petaurus breviceps), and conducted comprehensive comparative genomic analysis combined with another gliding mammal, the Sunda flying lemur (Galeopterus variegatus) and 14 background species. We found that the convergent evolution of protein-coding genes provided relatively limited but functionally relevant evidence linked to gliding phenotypes. By contrast, we found that gliding-accelerated CNEs (GACNEs) cluster near functionally equivalent genes and frequently aggregate into highly diverged yet functionally convergent hotspot regions. Across the three gliding lineages, both GACNEs and hotspot GACNEs show strong convergence in their functional enrichment profiles, suggesting a broad genetic basis underlying the convergent gliding phenotype. Furthermore, we identified 72 core transcription factors underpinning the genetic basis of gliding convergence, including EMX2 and ZFHX3, potentially involved in multiple aspects of gliding adaptation. Our study highlights the role of functional convergence in regulatory regions as a key mechanism in mammalian gliding convergence, offering valuable insights and strategies for uncovering the genetic basis of complex convergent traits, thereby advancing understanding of the molecular basis of convergent traits.
[Molecular drive].
The review of the concept of molecular drive developed by Dover is presented. The ideas on the possible role of non-coding DNA are described and the duplication of genes as the fundamental factor preceding the appearance of the gene, which possesses a new function are characterized. The non-Mendelian processes--the non-equal crossing-over and the conversion of genes are considered. Molecular drive includes both these phenomena and the transposition of genes. The examples of drive are presented. Drive can be considered as the fundamental molecular mechanism of speciation and macroevolution. Evolution at molecular level is directly connected with the non-constancy of the genome and is non-Mendelian and non-Darwinian. Both the coding and non-coding DNA can serve as material for evolution.
Aminoacyl-tRNA synthetases database.
Aminoacyl-tRNA synthetases (AARSs) are at the center of the question of the origin of life. They constitute a family of enzymes integrating the two levels of cellular organization: nucleic acids and proteins. AARSs arose early in evolution and are believed to be a group of ancient proteins. They are responsible for attaching amino acid residues to their cognate tRNA molecules, which is the first step in the protein synthesis. The role they play in a living cell is essential for the precise deciphering of the genetic code. The analysis of AARSs evolutionary history was not possible for a long time due to a lack of a sufficiently large number of their amino acid sequences. The emerging picture of synthetases' evolution is a result of recent achievements in genomics [Woese,C., Olsen,G.J., Ibba,M. and Söll,D. (2000) Microbiol. Mol. Biol. Rev., 64, 202-236]. In this paper we present a short introduction to the AARSs database. The updated database contains 1047 AARS primary structures from archaebacteria, eubacteria, mitochondria, chloroplasts and eukaryotic cells. It is the compilation of amino acid sequences of all AARSs known to date, which are available as separate entries via the WWW at http://biobases.ibch.poznan.pl/aars/.
Fine structure of ribosomal RNA. III. Location of evolutionarily conserved regions within ribosomal DNA.
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Homology of amino-terminal regions of C-phycocyanins from a prokaryote and a eukaryote.
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Killing two birds with one stone: a chemically plausible scheme for linked nucleic acid replication and coded peptide synthesis.
To understand how life began, we must explain the origins of nucleic acid replication and genetically coded peptide synthesis. Neither of these is easy to explain individually; here, we propose a chemically plausible scheme for the evolution of a process that simultaneously produced both polymers. Later, two separate machineries could have evolved from the linked process.
A genetically encoded fluorescent amino acid.
The fluorescent amino acid l-(7-hydroxycoumarin-4-yl) ethylglycine 1 has been genetically encoded in E. coli in response to the amber TAG codon. Because of its high fluorescence quantum yield, relatively large Stoke's shift, and sensitivity to both pH and polarity, this amino acid should provide a useful probe of protein localization and trafficking, protein conformation changes, and protein-protein interactions.