Tetraploidization event 15-20 million years ago Fish Prions
Tetrapod -- lungfish -- coelacanth relationships
Origin of neuro-proteins in evolution
Two c-myc genes from a tetraploid fish, the common carp (Cyprinus carpio).Zhang H; Okamoto N; Ikeda Y
Gene 153: 231-6 (1995)Two c-myc genes have been isolated from a tetraploid fish, the common carp (Cyprinus carpio). The nucleotide (nt) sequences of the two genes and their flanking regions (CAM1, 8675 bp and CAM2, 5784 bp) have been determined. Both genes contain two coding exons which are homologs of c-myc exons 2 and 3 in higher vertebrates. The nt sequence homologous to c-myc exon 1 of higher vertebrates has not been found. Carp CAM1 and CAM2 presumably encode peptides of 394 and 401 amino acids (aa), respectively. These two peptides share 55-91% aa identity with those of humans, chickens, frog, rainbow trout and zebra fish. The two carp c-Myc have a Glu stretch at the beginning region of exon 3. This Glu stretch is also present in zebra fish, suggesting that it may be characteristic to c-myc genes of cyprinid fishes. The existence of two c-myc in carp is attributed to the tetraploid nature of carp. These two genes share 92.4% nt identity in the coding region and 84.2% in the intron. The two deduced peptides share 94.2% aa identity, suggesting that the tetraploid event probably occurred 58 million years ago.
Molecular cloning and sequencing of coho salmon growth hormone cDNA.
Gonzalez-Villasenor LI; Zhang PJ; Chen TT; Powers DA
Gene 65: 239-46 (1988)A cDNA library was constructed using mRNA isolated from coho salmon pituitaries. By employing rainbow trout growth hormone cDNA as a probe, the coho salmon cDNA was isolated and the complete nucleotide (nt) sequence determined. The coding region contains 630 nt while the 5'- and 3'-untranslated regions are 64 and 489 nt in length, respectively. Comparison of the noncoding regions of coho and chum salmon cDNAs reveal identity at the 5' end but significant variation in the 3' end. Chum salmon and rainbow trout have identical amino acid (aa) sequences, but coho salmon growth hormone has a sequence that differs by 6 of the 188 predicted aa. Since salmonids are tetraploid, this difference may be the result of either divergence of the same growth hormone locus or of variation between different loci. Comparisons of the cDNA restriction maps of these three fish species suggest the former possibility.
Linkage relationships reflecting ancestral tetraploidy in salmonid fish.
Johnson KR; Wright JE Jr; May B
Genetics 116: 579-91 (1987)Fifteen classical linkage groups were identified in two salmonid species (Salmo trutta and Salmo gairdneri) and three fertile, interspecific hybrids (S. gairdneri X Salmo clarki, Salvelinus fontinalis X Salvelinus namaycush and S. fontinalis X Salvelinus alpinus) by backcrossing multiply heterozygous individuals. These linkage relationships of electrophoretically detected, protein coding loci were highly conserved among species. The loci encoding the enzymes appeared to be randomly distributed among the salmonid chromosomes. Recombination frequencies were generally greater in females than in males. In males, certain linkage groups were pseudolinked with other linkage groups, presumably because of facultative multivalent pairing and directed disjunction of chromosomes. Five such pseudolinkage groups were identified and they also appeared to be common among species and hybrids. Duplicate loci were never classically linked with each other, although some exhibited pseudolinkage and some showed evidence of exchanging alleles. Gene-centromere recombination frequencies estimated from genotypic distributions of gynogenetic offspring were consistent with map locations inferred from female intergenic recombination frequencies. These linkage relationships support the contention that all extant salmonids arose from a common tetraploid progenitor and that this progenitor may have been a segmental allotetraploid.
Multiple loci for synapse protein SNAP-25 in the tetraploid goldfish.
Risinger C; Larhammar D
Proc Natl Acad Sci U S A 90: 10598-602 (1993)The common goldfish Carassius auratus is tetraploid and has 100 chromosomes. We describe here goldfish cDNA clones for SNAP-25, a 200-amino-acid synaptosome-associated protein that has remained highly conserved during evolution. SNAP-25 occurs as a single-copy gene in mouse, chicken, and Drosophila melanogaster. Goldfish has three, or possibly four, SNAP-25 loci rather than two as expected.
A gene duplication early in actinopterygian fish evolution gave rise to the loci SnapA and SnapB. The proteins SNAP-A and SNAP-B are 94% and 91% identical to the mouse protein but are only 91% identical to each other. SNAP-B has a larger number of unique amino acid replacements than SNAP-A and also has more dramatic replacements. The tetraploidization resulted in two SnapB loci whose divergence from each other is consistent with a tetraploidization event 15-20 million years ago. The presence of duplicate SnapA loci has not yet been possible to confirm, possibly because they are still very similar to each other. Two of the SnapA cDNA clones and one SnapB cDNA clone have frameshift mutations. As these aberrant alleles otherwise display high sequence identity to the functional alleles, they probably became nonfunctional recently. The findings of allelic variability and aberrant alleles emphasize the importance of characterizing multiple DNA clones in tetraploid species.
Origin of tetrapods inferred from their mitochondrial DNA affiliation to lungfishMeyer A; Wilson AC
J Mol Evol 31: 359-64 (1990)For decades, it has been unclear whether coelacanth fishes or lungfishes are the closest living relatives of land vertebrates (Tetrapoda). Segments of mtDNA from a lungfish, the coelacanth, and a ray-finned fish were sequenced and compared to the published sequence of a frog mtDNA. A tree based on inferred amino acid replacements, silent transversions, and ribosomal RNA (rRNA) substitutions showed with statistical confidence that the lungfish mtDNA is more closely related to that of the frog than is the mtDNA of the coelacanth. This result appears to rule out the possibility that the coelacanth lineage gave rise to land vertebrates; hence, morphological characters that link the latter two groups are possibly due to convergent evolution or reversals and not to common descent. The common ancestor of lungfishes and tetrapods already possessed 14 multiple morphological traits preadapting their locomotion, circulation, and respiration for life on land.
Molecules, fossils, and the origin of tetrapods.Meyer A; Dolven SI
J Mol Evol 35: 102-13 (1992)Since the discovery of the coelacanth, paleontologists and comparative morphologists have debated whether coelacanths or lungfishes, two groups of lobe-finned fishes, are the closest living relatives of land vertebrates (Tetrapoda). Previously determined partial DNA sequences from two conservative mitochondrial genes support a close relationship of lungfishes to tetrapods. We present additional DNA sequences from the 12S rRNA mitochondrial gene for three species of the two lineages of lungfishes: Protopterus annectens and Protopterus aethiopicus from Africa, and Neoceratodus forsteri from Australia.
This extended data set tends to group the two lepidosirenid lungfish lineages (Lepidosiren and Protopterus) with Neoceratodus as their sister group. All lungfishes seem to be more closely related to tetrapods than the coelacanth is. This result appears to rule out the possibility that the coelacanth lineage gave rise to land vertebrates. Those traits that seem to link coelacanth and tetrapods are arguably due to convergent evolution or reversals and not to common descent.
Differences among paleontologists in the interpretation of the fossils have stood in the way of a consensus opinion for the branching order among lobefinned fishes. Marshall and Schultze criticized the morphological analysis presented by Meyer and Wilson and suggest that 13 of the 14 morphological traits that support the sister group relationship of lungfishes and tetrapods are not shared derived characters. Here we present further alternative viewpoints to the ones of Marshall and Schultze from the paleontological literature.
Complete mitochondrial genome of lungfish (Protopterus dolloi) supports its phylogenetic position as a close relative of land vertebrates.Zardoya R; Meyer A
Genetics 142: 1249-63 (1996)The complete DNA sequence (16,646 bp) of the mitochondrial genome of the African lungfish, Protopterus dolloi, was determined. The evolutionary position of lungfish as possibly the closest living relative among fish of land vertebrates made its mitochondrial DNA sequence particularly interesting. Its mitochondrial gene order conforms to the consensus vertebrate gene order. Several sequence motifs and secondary structures likely involved in the regulation of the initiation of replication and transcription of the mitochondrial genome are conserved in the lungfish and are more similar to those of land vertebrates than those of ray-finned fish. A novel feature discovered is that the putative origin of L-strand replication partially overlaps the adjacent tRNA(Cys). The phylogenetic analyses of genes coding for tRNAs and proteins confirm the intermediate phylogenetic position of lungfish between ray-finned fishes and tetrapods. The complete nucleotide sequence of the African lungfish mitochondrial genome was used to estimate which mitochondrial genes are most appropriate to elucidate deep branch phylogenies. Only a combined set of either protein or tRNA mitochondrial genes (but not each gene alone) is able to confidently recover the expected phylogeny among vertebrates that have diverged up over approximately 400 mya.
Close tetrapod relationships of the coelacanth Latimeria from haemoglobin sequenceGorr T; Kleinschmidt T; Fricke H
Nature 351: 394-7 (1991)The origin of tetrapods has been debated for many years. In traditional systematics, the extinct lobe-finned bony fish (Rhipidistia) are regarded as the closest relatives of tetrapods. Among living fish, the coelacanth, Latimeria chalumnae (Actinistia), which is the only recent representative of the Crossopterygii (Actinistia and Rhipidistia), the lungfish (Dipnoi) and ray-finned fish (Actinopterygii), have each been considered as sister-groups of the tetrapods. Haemoglobins of bony fish match more closely those of larval than adult amphibians. The beta chains of coelacanth match those of tadpoles more closely (54%) than do those of any other fish, whereas the alpha chains of coelacanth (45.4%), and especially of teleosts (49.2%), are closer to those of larval amphibians than are those of lungfish (39.8%). If only synapomorphous sequence matches, those at derived positions shared by one bony fish and tadpoles but not by any other bony fish, are considered, both coelacanth globin chains have distinctly more identities with phase of tadpoles than do those of any bony fish. Thus the primary structure of Latimeria haemoglobin indicates that the coelacanth is the closest living relative of tetrapods.
Evolutionary relationships of the coelacanth, lungfishes, and tetrapods from 28S ribosomal RNA geneZardoya R; Meyer A
Proc Natl Acad Sci U S A 93: 5449-54 (1996)The Devonian origin of land vertebrates was one of the major transitions in the history of vertebrates. Yet, despite many studies that are based on either morphology or molecules, the phylogenetic relationships among tetrapods and the other two living groups of lobe-finned fishes, the coelacanth and the lungfishes, are still debated. We collected the largest molecular data set on this issue so far, about 3,500 base pairs from seven species of the large 28S nuclear ribosomal gene. All phylogenetic analyses (maximum parsimony, neighbor-joining, and maximum likelihood) point toward the hypothesis that lungfishes and coelacanths form a monophyletic group and are equally closely related to land vertebrates.
Lungfish prolactin exhibits close tetrapod relationships.Noso T; Nicoll CS; Kawauchi H
Biochim Biophys Acta 1164: 159-65 (1993)Prolactin from the pituitary glands of African lungfish, Protoputerus aethiopicus, consists of 200 residue with 66% identities with amphibian, reptilian and bird prolactins, 57% with mammalian prolactins, and 38% with teleost (modern bony fish) prolactins. Moreover, the prolactin contains three disulfide bonds homologous to those of tetrapod PRLs and differs from teleost PRLs which lack the amino-terminal disulfide bond. Thus, the structural features of lungfish prolactin indicate a closer relationship to tetrapod prolactins than to teleost PRLs.
Molecular phylogeny of fish based on sequence analysis of 28S ribosomal RNALe HL; Perasso R; Billard R
C R Acad Sci [III] 309: 493-8 (1989)Fish phylogeny has been studied using partial 28 S ribosomal RNA sequences of 14 species among which 12 are fish ranging from lamprey to perciforms. Our results are in good agreement with generally accepted cladograms based on anatomical and paleontological data. Two interesting conclusions emerged: a) Polypterus is the sister-group of all other actinopterygians; b) the divergences of the Clasdistia, Tetrapoda and Chondrichthyes seem to have occurred during a relatively short period of time.
Evolution of the 28S ribosomal RNA gene in anurans: phylogenetic implications.Hillis DM; Davis SK
Mol Biol Evol 4: 117-25 (1987)Fifteen restriction sites were mapped to the 28S ribosomal RNA gene of individuals representing 54 species of frogs, two species of salamanders, a caecilian, and a lungfish. Eight of these sites were present in all species examined, and two were found in all but one species. Alignment of these conserved restriction sites revealed, among anuran 28S rRNA genes, five regions of major length variation that correspond to four of 12 previously identified divergent domains of this gene. One of the divergent domains (DD8) consists of two regions of length variation separated by a short segment that is conserved at least throughout tetrapods. Most of the insertions, deletions, and restriction-site variations identified in the 28S gene will require sequence-level analysis for a detailed reconstruction of their history. However, an insertion in DD9 that is coextensive with frogs in the suborder Neobatrachia, a BstEII site that is limited to representatives of two leptodactylid subfamilies, and a deletion in DD10 that is found only in three ranoid genera are probably synapomorphies.
Molecular phylogeny of 18S rRNA gene from two teleosts and sharksBernardi G; Sordino P; Powers DA
Mol Mar Biol Biotechnol 1: 187-94 (1992)The 18S rRNA sequence was determined for two teleostean fish species, Fundulus heteroclitus and Sebastolobus altivelis, and two sharks, Squalus acanthias and Echinorhinus cookei. The sequences were compared with the coelacanth, Latimeria chalumnae, the frog, Xenopus laevis, and humans. Maximum parsimony analysis of the sequences resulted in a single most parsimonious tree that is in agreement with the expected phylogeny.
Phylogenetic relationships a primitive bony fish Amia calva (Halecomorphi) from growth hormoneRubin DA; Dores RM
Gen Comp Endocrinol 95: 71-83 (1994)Growth hormone and prolactin, are a multigene superfamily. The structural and functional domains of GH appear to be highly conserved among vertebrates. To investigate the phylogenetic relationships in Actinopterygii (ray-finned fish) and Sarcopterygii (African lungfish and African bullfrog), we sequenced GH from the pituitary of the primitive bony fish, Amia calva. Bony fishes (teleosts) and Amia (Halecomorphi) are purported sister-groups within the Neoptergii. Phylogenetic comparisons of GH from blue shark, sturgeon, four teleosts (eel, carp, porgy, flounder), and two sarcopterygians indicate Halecomorphi is a sister-group to the teleosts, that sturgeon is a sister-group to the Neopterygii, and that the African lungfish and African bullfrog are in the same clade.
The phylogeny of Met-enkephalin and Leu-enkephalin in the holostean fish Lepisosteus platyrhincus and Australian lungfish, Neoceratodus forsteri.McDonald LK; Joss JM; Dores RM
Gen Comp Endocrinol 84: 228-36 (1991)Extracts of the brain of the holostean fish Lepisosteus platyrhincus and the forebrain of the dipnoan fish Neoceratodus forsteri were fractionated, with results suggesting that the ancestral proenkephalin gene of both actinopterygian and sarcopterygian fish contained both the Met-enkephalin and Leu-enkephalin sequences.
Myelin basic proteins in the shark, Squalus acanthias, and the ray, Raja erinacia.Spivack WD; Zhong N; Salerno S; Saavedra RA; Gould RM
J Neurosci Res 35: 577-84 (1993)Myelin basic proteins (MBPs) are a family of alternatively spliced isoforms present in myelin sheaths of most vertebrates. Species studied represent two superorders of elasmobranchs: Squalus acanthias, representing Squalomorph sharks, and Raja erinacia, representing Batoidea rays. Two products were generated from each species. The larger product encoded a 155 amino acid protein, the same size as MBPs from two Galeomorph sharks, Heterodontus francisci and Carcharhinus obscurus, which, based upon alignment with other vertebrate MBPs, contained six of the seven MBP exons; only exon II was absent. The smaller product encoded a 141 amino acid protein that lacked exon II and exon V. There were 26 and 30 nucleotide differences between Squalus and Heterodontus, and Raja and Heterodontus, respectively. Sequences from Squalus and Raja were far more similar, having only five nucleotide differences. Both isoforms of elasmobranch MBP contain 18.5% basic (lysine plus arginine) amino acids, compared with 17.5% in mammalian MBPs comprised of the corresponding exons. Northern blot analysis of whole brain total RNA revealed a single band of 2.5 kb in Squalus, and three bands of 1.2, 1.4, and 2.3 kb in Raja. The finding that MBPs of a Squalomorph shark and a Batoidea ray are closer to one another than either is to the Galeomorph sharks suggests that MBP sequence information may prove useful in classifying modern day Chondrichthytes.
Amino acid neurotransmitter receptors of carp brain expressed in amphibian oocytesZhu H; Zhu X; Bao YD Sheng Li Hsueh
Pao 47: 1-10 (1995)GABA receptor and inotropic glutamate receptors from carp (Carassius carassius) brains were expressed in amphibian oocytes These observations suggest the existence of GABAC receptor. Subtypes of glutamate receptors, including NMDA subtype, KA/AMPA subtype and metabotropic glutamate receptors were also expressed and the dose-response relations were studied. Furthermore, we found that NMDA competitively suppressed the current response to KA, suggesting that NMDA probably was a weak antagonist of the KA/AMPA receptor.
Glial fibrillary acidic protein in fish optic nerve.Blaugrund E; Cohen I; Shani Y; Schwartz M
GLIA 4: 393-9 (1991)The intermediate filament glial fibrillary acidic protein (GFAP) is the predominant cytoskeletal protein of mature glial cells in the mammalian nervous system. The nervous systems of lower vertebrates, such as fish, have been examined for the presence of GFAP; goldfish (Carassius auratus) brain contains GFAP-positive astrocytes. Antibodies to porcine GFAP react with the optic nerve of carp (Cyprinus carpio), another member of the goldfish family.
Ependymins from the cerebrospinal fluid of salmonid fish: gene structure and molecular characterization.Muller-Schmid A; Rinder H; Lottspeich F; Gertzen EM; Hoffmann W
Gene 118: 189-96 (1992)So far, ependymins (Epds) have been sequenced only from cypriniform fish, and in the past all attempts have failed to characterize, on a molecular level, homologous Epd proteins in higher vertebrates. Therefore, rainbow trout (Oncorhynchus mykiss) Epds, which represent the predominant proteins of the cerebrospinal fluid, have been N-terminally sequenced and the encoding cDNA subsequently cloned using PCR. Surprisingly, only 40-42% of the amino acids are identical with the corresponding sequences from goldfish (Carassius auratus)
Expansion of genes that encode MHC class I molecules in cyprinid fishes.Okamura K; Nakanishi T; Kurosawa Y; Hashimoto K
J Immunol 151: 188-200 (1993)We have analyzed the genomic genes and the mRNA that encode MHC class I molecules in cyprinid fishes, namely, the ginbuna crucian carp (Carassius auratus langsdorfii) and the carp (Cyprinus carpio). The presence of several distinct class I genes was revealed in the genome of cyprinid fishes, and distinct class I genes that are expressed in carp cells were identified. The sequences of the alpha 3 domain of these class I genes are relatively well conserved, whereas the sequences of the respective alpha 1 and alpha 2 domains have diverged from one another. A comparison of the sequences expressed in carp with the sequences of the human classical class I molecules revealed that several amino acids in the peptide-binding region, including those that have been proposed to interact with antigenic peptide termini, are highly conserved. The present study demonstrated a dynamic expansion of the genes that encode MHC class I molecules in teleost fish whose ancestor branched off from the vertebrate line leading to mammals more than 400 million years ago.
Cloning and characterization of a truncated dopamine D1 receptor from goldfish retinaFrail DE; Manelli AM; Witte DG; Lin CW; Steffey ME; Mackenzie RG
Mol Pharmacol 44: 1113-8 (1993)Receptors for dopamine are present on horizontal cells of fish retina that are linked to the activation of adenylate cyclase. In the present study, the goldfish (Carassius auratus) gene that encodes these receptors, referred to as gfD1, was isolated and analyzed. A single open reading frame within the gfD1 gene encodes a protein of 363 amino acids that is highly homologous with dopamine D1 receptors from rats and humans. Interestingly, the carboxyl terminus of gfD1 lacks 80 amino acids that are present in the mammalian receptor sequences.
Biplexiform ganglion cells in teleost fish retinaeCook JE; Kondrashev SL; Podugolnikova TA Vis Neurosci 13: 517-28 (1996)
Biplexiform ganglion cells were labelled by retrograde transport of HRP in five species of marine fish from the neoteleost acanthopterygian orders Perciformes and Scorpaeniformes. The exclusion radius differed in Hexagrammos stelleri, Ernogrammus hexagrammus (Perciformes), and Myoxocephalus stelleri (Scorpaeniformes). Similar cells were previously observed not only in the freshwater cichlid Oreochromis spilurus (Perciformes) but also in the goldfish Carassius auratus (Cypriniformes) which, being an ostariophysan teleost, is only distantly related. Thus, biplexiform ganglion cells may be regular elements of all teleost fish retinae. Their functional role remains unknown.
Galanin, substance P, vasotocin, and isotocin in teleost Atlantic salmon (Salmo salar).Holmqvist BI; Ekstrom P
J Comp Neurol 306: 361-81 (1991)The presence of galanin-like substances and their relation to substance P-, vasotocin-, and isotocin-immunoreactive neurons and fibers in the brain of teleosts was investigated in the brain of four teleost species (Salmo salar, Carassius carassius, Gasterosteus aculeatus, and Anguilla anguilla). In all four species the main location of galanin immunoreactivity was in the hypothalamo-pituitary region. A detailed study of the distribution of galanin immunoreactivity in S. salar showed that galanin immunoreactive (GALir) perikarya were present in the nucleus preopticus periventricularis, an area that may be compared to the supraoptic nucleus in mammals, and in the nucleus lateralis tuberis, a nucleus involved in pituitary control in fishes that may be compared with the arcuate nucleus in mammals.
Nitric oxide synthase from a goldfish (Carassius auratus)
Immunol Cell Biol 74: 374-9 (1996)
Neurotensin in the brain of a teleost, amphibian, and reptileBello AR; Milan J; Anglade I; Martin A; Negrin I; Diaz C; Conlon JM; Tramu G; Kah O
J Comp Neurol 348: 511-30 (1994)The distribution of neurotensin was studied in the brain of three species belonging to the three major classes of cold-blooded vertebrates: teleost fishes (Carassius auratus), anuran amphibians (Hyla meridionalis), and reptiles (Gallotia galloti; Lacertidae). Immunoreactive cell bodies were discovered mostly in the telencephalon and diencephalon, in particular at the level of the preoptic region the mediobasal hypothalamus, and the thalamus. In the frog and the lizard, additional immunoreactive (ir) structures were observed in the optic tectum and the tegmentum of the mesencephalon. In the goldfish pituitary, an extensive innervation was consistently observed at the level of the rostral pars distalis, whereas in both frog and lizard, positive fibers were only detected in the external layer of the median eminence. In the three species there is a striking overlap between the distribution of the NT-ir cell bodies and that of the target cells for sexual steroids. The results are discussed in relation with those reported in birds and mammals, and with the possible interactions among NT, sexual steroids, and the neuroendocrine control of pituitary hormone release, in particular prolactin and gonadotrophin.
Novel tachykinins from the brain of the sea lamprey, Petromyzon marinus, and the skate, Raja rhina.Waugh D; Sower S; Bjenning C; Conlon JM
Peptides 15: 155-61 (1994)Tachykinins, peptides with substance P-like immunoreactivity and neurokinin A-like immunoreactivity were identified in the brain of the longnose skate, Raja rhina (elasmobranch) but only a peptide with neurokinin A-like immunoreactivity was identified in the brain of the sea lamprey, Petromyzon marinus (agnathan). The primary structure of the skate peptide with substance P-like immunoreactivity shows one amino acid substitution compared with scyliorhinin I, previously isolated from dogfish brain and gut. The skate neurokinin A-related peptide shows two substitutions compared with mammalian neurokinin A. Although the COOH-terminus of the lamprey tachykinin resembles neurokinin A, the presence of the strongly conserved Lys/Arg-Pro-Xaa-Pro motif at the NH2-terminus of the peptide indicates greater structural similarity with substance P. The additional arginine residue at position 1 in the peptide suggests that the lamprey is utilizing a site of posttranslational processing in the tachykinin precursor that is different from the equivalent site in mammalian and other lower vertebrate preprotachykinins.
Neuropeptide Yfrom the pancreas of a teleostean (eel), holostean (bowfin) and elasmobranch (skate) fish.Conlon JM; Bjenning C; Moon TW; Youson JH; Thim L
Peptides 12: 221-6 (1991)Homologous peptides belonging to the pancreatic polypeptide (PP) family were isolated from the pancreas of a teleostean fish, the American eel (Anguilla rostrata), an holostean fish, the bowfin (Amia calva) and an elasmobranch fish, the skate (Raja rhina), and their primary structures were determined. The peptides show stronger homology to neuropeptide Y, particularly in their COOH-terminal regions, than to peptide YY or pancreatic polypeptide and contain an alpha-amidated COOH-terminal tyrosine residue.
Phylogenetic comparison of benzodiazepine receptor subunits.Hebebrand J; Friedl W; Breidenbach B; Propping P
J Neurochem 48: 1103-8 (1987)The late evolutionary appearance of the benzodiazepine receptor: a systematic comparison of the subunit patterns in fishes, amphibians, reptiles, birds, and mammals revealed that the subunit of 53K is phylogenetically the oldest labeled subunit; whereas it is the only band present in the lungfish and most amphibians, additional bands are apparent in higher tetrapods. In fishes, the evolution of the BZR subunits leads to the loss of the 53K subunit. Possible explanations for the observed variation of the subunits are discussed, with special emphasis placed on the possible evolution by gene duplication and subsequent divergence.
DNA photolyases in aplacental mammals.Yasui A; Eker AP; Yasuhira S; Yajima H; Kobayashi T; Takao M; Oikawa A
EMBO J 13: 6143-51 (1994)DNA photolyase repairs UV pyrimidine dimers in DNA. Photolyase genes from Drosophila melanogaster (fruit fly), Oryzias latipes (killifish) and the marsupial Potorous tridactylis (rat kangaroo) show only limited homology with microbial photolyase genes. Together with the previously cloned Carassius auratus (goldfish) gene they form a separate group of photolyase genes. The biologically active protein contained FAD as light-absorbing cofactor, a property in common with the microbial class photolyases. Furthermore, we found in the archaebacterium M. thermoautotrophicum a gene similar to the higher eukaryote photolyase genes, but we could not obtain evidence for the presence of a homologous gene in the human genome. Our results suggest a divergence of photolyase genes in early evolution.
Cloning of a marsupial DNA photolyase gene and the lack of related nucleotide sequences in placental mammals.Kato T Jr; Todo T; Ayaki H; Ishizaki K; Morita T; Mitra S; Ikenaga M
Nucleic Acids Res 22: 4119-24 (1994)DNA photolyase has been detected in a wide variety of organisms ranging from bacteria to nonplacental mammals. However, the evidence for photoreactivation in placental mammals, including humans, is controversial. We isolated a cDNA clone of this gene from a marsupial, the South American opossum Monodelphis domestica. Photolyase activity was expressed in Escherichia coli from the cDNA which is predicted to encode a polypeptide of 470 amino acid residues. The deduced amino acid sequence of this protein is strikingly similar to those of photolyases from two metazoans; the opossum photolyase shares 59% and 63% sequence identity with the Drosophila melanogaster and goldfish, Carassius auratus, enzymes, respectively. However, no closely related nucleotide sequence was detected in higher mammals and a homologous transcript was undetectable in a number of human tissues. These results strongly suggest that humans, as well as other placental mammals, lack the photolyase gene.