Research Interests: Computer Science, Genomics, Comparative Genomics, Biology, Cell Cycle, and 15 moreRNA polymerase, Medicine, Biological Sciences, Humans, Animals, Peptides, Evolutionary History, Stabilizing Selection, Kinase, CTD, Protozoan Proteins, Amino Acid Sequence, Cell Cycle Proteins, Molecular Sequence Data, and Medical and Health Sciences
Research Interests: Evolutionary Biology, Genetics, Phylogenetics, Molecular Evolution, Biology, and 15 moreMedicine, Phylogeny, Plants, Biological evolution, Red Algae, Molecular phylogenetics, Rhodophyta, Time Factors, Monophyly, Phylogenetic Tree, Statistical models, Bayes Theorem, Ribosomal DNA, reverse transcriptase polymerase chain reaction, and Evolutionary analysis
The origin of the red algae has remained an enigma. Historically the Rhodophyta were classified first as plants and later as the most ancient eukaryotic organisms. Recent molecular studies have indicated similarities between red and green... more
The origin of the red algae has remained an enigma. Historically the Rhodophyta were classified first as plants and later as the most ancient eukaryotic organisms. Recent molecular studies have indicated similarities between red and green plastids, which suggest that there was a single endosymbiotic origin for these organelles in a common ancestor of the rhodophytes and green plants. Previous efforts to confirm or reject this effort by analyses of nuclear DNA have been inconclusive; thus, additional molecular markers are needed to establish the relationship between the host cell lineages, independent of the evolutionary history of their plastids. To furnish such a data set we have sequenced the largest subunit of RNA polymerase II from two red algae, a green alga and a relatively derived amoeboid protist. Phylogenetic analyses provide strong statistical support for an early evolutionary emergence of the Rhodophyta that preceded the origin of the line that led to plants, animals, and...
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In recent years a great deal of biochemical and genetic research has focused on the C-terminal domain (CTD) of the largest subunit (RPB1) of DNA-dependent RNA polymerase II. This strongly conserved domain of tandemly repeated... more
In recent years a great deal of biochemical and genetic research has focused on the C-terminal domain (CTD) of the largest subunit (RPB1) of DNA-dependent RNA polymerase II. This strongly conserved domain of tandemly repeated heptapeptides has been linked functionally to important steps in the initiation and processing of mRNA transcripts in both animals and fungi. Although they are absolutely required for viability in these organisms, C-terminal tandem repeats do not occur in RPB1 sequences from diverse eukaryotic taxa. Here we present phylogenetic analyses of RPB 1 sequences showing that canonical CTD heptads are strongly conserved in only a subset of eukaryotic groups, all apparently descended from a single common ancestor. Moreover, eukaryotic groups in which the most complex patterns of ontogenetic development occur are descended from this CTD-containing ancestor. Consistent with the results of genetic and biochemical investigations of CTD function, these analyses suggest that ...
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Unlike parasitic protist groups that are defined by the absence of mitochondria, the Pelobiontida is composed mostly of free-living species. Because of the presence of ultrastructural and cellular features that set them apart from all... more
Unlike parasitic protist groups that are defined by the absence of mitochondria, the Pelobiontida is composed mostly of free-living species. Because of the presence of ultrastructural and cellular features that set them apart from all other eukaryotic organisms, it has been suggested that pelobionts are primitively amitochondriate and may represent the earliest-evolved lineage of extant protists. Analyses of rRNA genes, however, have suggested that the group arose well after the diversification of the earliest-evolved protists. Here we report the sequence of the gene encoding the largest subunit of DNA-dependent RNA polymerase II ( RPB 1) from the pelobiont Mastigamoeba invertens . Sequences within RPB1 encompass several of the conserved catalytic domains that are common to eubacterial, archaeal, and eukaryotic nuclear-encoded RNA polymerases. In RNA polymerase II, these domains catalyze the transcription of all nuclear pre-mRNAs, as well as the majority of small nuclear RNAs. In co...
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Research Interests: Genetics, Flow Cytometry, Biology, Genetic Networks, Medicine, and 15 moreGene expression, Multidisciplinary, Cell separation, Mutation, Gene, Phenotype, DNA content, Growth rate, CTD, Metabolic pathway, Amino Acid Sequence, Cell Wall, Chromosomes, Differential expression, and Molecular Sequence Data
Research Interests: Evolutionary Biology, Genetics, Computational Biology, Molecular Evolution, Biology, and 15 moreMedicine, Saccharomyces cerevisiae, Circular Dichroism, Molecular biology and evolution, Peptides, Phosphorylation, Phenotype, Genetic variation, CTD, Amino Acid Sequence, Structure activity Relationship, Biochemistry and cell biology, Molecular Sequence Data, Pliability, and conserved sequence
Research Interests: Evolutionary Biology, Genetics, Computational Biology, Coevolution, Comparative Genomics, and 15 moreBiology, Biological Sciences, Enzymes, Environmental Sciences, Animals, Alternative splicing, Gene, Enzyme, Degeneration, CTD, Alternative Splicing, Amino Acid Sequence, Base Sequence, Biochemistry and cell biology, and binding sites
Research Interests: Evolutionary Biology, Genetics, Conservation Genetics, Molecular Evolution, Comparative Genomics, and 15 moreBiology, Medicine, Budding Yeast, Saccharomyces cerevisiae, Protein Kinases, Molecular biology and evolution, Phosphorylation, Phenotype, Degeneration, CTD, Amino Acid Sequence, Structure activity Relationship, Protein Binding, Fusion Protein, and Biochemistry and cell biology
Background The acquisition of complex transcriptional regulatory abilities and epigenetic machinery facilitated the transition of the ancestor of apicomplexans from a free-living organism to an obligate parasite. The ability to control... more
Background The acquisition of complex transcriptional regulatory abilities and epigenetic machinery facilitated the transition of the ancestor of apicomplexans from a free-living organism to an obligate parasite. The ability to control sophisticated gene expression patterns enabled these ancient organisms to evolve several differentiated forms, invade multiple hosts and evade host immunity. How these abilities were acquired remains an outstanding question in protistan biology. Results In this work, we study SET domain bearing genes that are implicated in mediating immune evasion, invasion and cytoadhesion pathways of modern apicomplexans, including malaria parasites. We provide the first conclusive evidence of a horizontal gene transfer of a Histone H4 Lysine 20 (H4K20) modifier, Set8, from an animal host to the ancestor of apicomplexans. Set8 is known to contribute to the coordinated expression of genes involved in immune evasion in modern apicomplexans. We also show the likely tra...
Research Interests: Evolutionary Biology, Genetics, Biology, Horizontal Gene Transfer, Medicine, and 15 morePlasmodium, Phylogeny, Parasitism, Animals, Parasites, Dictyostelium, Gene, Biological evolution, Plasmodium falciparum, Protozoa, Nematoda, Amino Acid Sequence, Bayes Theorem, Likelihood Functions, and Apicomplexa
Unlike all other RNA polymerases, the largest subunit (RPB1) of eukaryotic DNA-dependent RNA polymerase II (RNAP II) has a C-terminal domain (CTD) comprising tandemly repeated heptapeptides with the consensus sequence Y-S-P-T-S-P-S. The... more
Unlike all other RNA polymerases, the largest subunit (RPB1) of eukaryotic DNA-dependent RNA polymerase II (RNAP II) has a C-terminal domain (CTD) comprising tandemly repeated heptapeptides with the consensus sequence Y-S-P-T-S-P-S. The tandem structure, heptad consensus, and most key functions of the CTD are conserved between yeast and mammals. In fact, all metazoans, fungi, and green plants examined to date, as well as the nearest protistan relatives of these multicellular groups, contain a tandemly repeated CTD. In contrast, the RNAP II largest subunits from many other eukaryotic organisms have a highly degenerate C terminus or show no semblance of the CTD whatsoever. The reasons for intense stabilizing selection on CTD structure in certain eukaryotes, and its apparent absence in others, are unknown. Here we demonstrate, through in vivo genetic complementation, that the essential functional unit of the yeast CTD is contained within pairs of heptapeptides. Insertion of a single al...
Research Interests: Genetics, Biology, Fungi, RNA polymerase, Medicine, and 15 moreBiological Sciences, Saccharomyces cerevisiae, Phylogeny, Animals, Stabilizing Selection, Molecular cloning, Degeneration, CTD, Amino Acid Sequence, Amino Acid Substitution Rates, Eukaryotic Cell, RNA Polymerases, Cell Growth, Molecular Sequence Data, and Medical and Health Sciences
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Red algae are the oldest identifiable multicellular eukaryotes, with a fossil record dating back more than a billion years. During that time two major rhodophyte lineages, bangiophytes and florideophytes, have evolved varied levels of... more
Red algae are the oldest identifiable multicellular eukaryotes, with a fossil record dating back more than a billion years. During that time two major rhodophyte lineages, bangiophytes and florideophytes, have evolved varied levels of morphological complexity. These two groups are distinguished, in part, by different patterns of multicellular development, with florideophytes exhibiting a far greater diversity of morphologies. Interestingly, during their long evolutionary history, there is no record of a rhodophyte achieving the kinds of cellular and tissue-specific differentiation present in other multicellular algal lineages. To date, the genetic underpinnings of unique aspects of red algal development are largely unexplored; however, they must reflect the complements and patterns of expression of key regulatory genes. Here we report comparative evolutionary and gene expression analyses of core subunits of the SWI/SNF chromatin-remodeling complex, which is implicated in cell differ...
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Porphyra umbilicalis (laver) belongs to an ancient group of red algae (Bangiophyceae), is harvested for human food, and thrives in the harsh conditions of the upper intertidal zone. Here we present the 87.7-Mbp haploid Porphyra genome... more
Porphyra umbilicalis (laver) belongs to an ancient group of red algae (Bangiophyceae), is harvested for human food, and thrives in the harsh conditions of the upper intertidal zone. Here we present the 87.7-Mbp haploid Porphyra genome (65.8% G + C content, 13,125 gene loci) and elucidate traits that inform our understanding of the biology of red algae as one of the few multicellular eukaryotic lineages. Novel features of the Porphyra genome shared by other red algae relate to the cytoskeleton, calcium signaling, the cell cycle, and stress-tolerance mechanisms including photoprotection. Cytoskeletal motor proteins in Porphyra are restricted to a small set of kinesins that appear to be the only universal cytoskeletal motors within the red algae. Dynein motors are absent, and most red algae, including Porphyra, lack myosin. This surprisingly minimal cytoskeleton offers a potential explanation for why red algal cells and multicellular structures are more limited in size than in most mul...
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The average biotech catalog contains a dizzying array of kits offering tried-and-true protocols in molecular biology and biochemistry. Many of the most reliable have been adapted to biology teaching. Prepackaged experiences, ranging from... more
The average biotech catalog contains a dizzying array of kits offering tried-and-true protocols in molecular biology and biochemistry. Many of the most reliable have been adapted to biology teaching. Prepackaged experiences, ranging from DNA fingerprinting to protein purification, are now available to high school students. With minimal practice for students, instructors can expect a high success rate even with fairly advanced molecular techniques. [ILLUSTRATION OMITTED] Although commercial kits designed for education provide excellent hands-on experiences in molecular technology, the students using them are merely reproducing predetermined results. Such canned laboratories do not necessarily promote an "inquiry into authentic questions generated from students' experiences, the central strategy for teaching science" (NRC 1996, p. 31). Fortunately, however, the remarkable reliability of many available protocols now makes this possible. Teaching molecular technology within the framework of open scientific inquiry provides a dynamic learning experience. Students discover that science is not just about learning techniques, but rather using those techniques to answer questions about the world around them. In this setting, where the design of the research experience is not hatched in a distant commercial laboratory, students are invested in the outcome of their experiments beyond the goal of an "A" on a lab report. Because a wide variety of molecular protocols are now so reliable, teachers can emphasize scientific inquiry and experimental design rather than the technology itself. Of course, there are additional challenges to such an approach. Open-ended molecular research can require the ability to string together multiple techniques and the use of expensive instrumentation or hazardous materials unavailable or inappropriate in a high school setting. However, teachers can address these challenges by developing partnerships with university and other professional researchers, as outlined in the "Standards for Professional Development for Teachers of Science" (NRC 1996, p. 55). [ILLUSTRATION OMITTED] Planning a project in DNA forensics Using resources common at research institutions and commercially available molecular protocols, two Advanced Placement biology high school classes carried out a project in DNA forensics. We used a series of procedures, all from fully contained commercial kits, to perform genetic typing on bacteria growing in students' everyday environment. Although some of the exercises may at first sound intimidating to those with little hands-on molecular experience, they involve knowledge and techniques that are already incorporated into most high school biology curricula. All of the exercises can be easily accomplished in collaboration with an experienced research partner. Students began by swabbing a surface and streaking the swab on a petri dish containing enriched agar medium. Our students were encouraged to be creative in their sampling, but it is important to observe commonsense safety. Students should not collect bacteria from a location that they would not go poking around otherwise. Even with precautions, however, environmental samples may contain potentially dangerous bacteria and therefore should not be cultured in a high school lab (Kwan, Summers, and Texley 2004). By teaming up with a professional, students can sample the unknown, free from the risk of exposure to disease-causing agents. Sampling plates should be sealed immediately, before any bacterial colonies begin to grow, and removed to a safe culturing facility where they can be handled by only the teacher or trained researchers. Students can then work with clear digital images of their sample plates (see petri dish image, p. 20) when choosing colonies to begin their forensic examinations. Isolating a gene from each sample colony Using the polymerase chain reaction (PCR) (Mullis et al. …
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Chromist algae include diverse photosynthetic organisms of great ecological and social importance. Despite vigorous research efforts, a clear understanding of how various chromists acquired photosynthetic organelles has been complicated... more
Chromist algae include diverse photosynthetic organisms of great ecological and social importance. Despite vigorous research efforts, a clear understanding of how various chromists acquired photosynthetic organelles has been complicated by conflicting phylogenetic results, along with an undetermined number and pattern of endosymbioses, and the horizontal movement of genes that accompany them. We apply novel statistical approaches to assess impacts of endosymbiotic gene transfer on three principal chromist groups at the heart of long-standing controversies. Our results provide robust support for acquisitions of photosynthesis through serial endosymbioses, beginning with the adoption of a red alga by cryptophytes, then a cryptophyte by the ancestor of ochrophytes, and finally an ochrophyte by the ancestor of haptophytes. Resolution of how chromist algae are related through endosymbioses provides a framework for unravelling the further reticulate history of red algal-derived plastids, ...
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A tandemly repeated C-terminal domain (CTD) of the largest subunit of RNA polymerase II is functionally essential and strongly conserved in many organisms, including animal, yeast and plant models. Although present in simple, ancestral... more
A tandemly repeated C-terminal domain (CTD) of the largest subunit of RNA polymerase II is functionally essential and strongly conserved in many organisms, including animal, yeast and plant models. Although present in simple, ancestral red algae, CTD tandem repeats have undergone extensive modifications and degeneration during the evolutionary transition to developmentally complex rhodophytes. In contrast, CTD repeats are conserved in both green algae and their more complex land plant relatives. Understanding the mechanistic differences that underlie these variant patterns of CTD evolution requires knowledge of CTD-associated proteins in these 2 lineages. To provide an initial baseline comparison, we bound potential phospho-CTD associated proteins (PCAPs) to artificially synthesized and phosphorylated CTD repeats from the unicellular red alga Cyanidioschyzon merolae and green alga Chlamydomonas reinhardtii. Our results indicate that red and green algae share a number of PCAPs, inclu...
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Sequence-based molecular phylogenies have provided new models of early eukaryotic evolution. This includes the widely accepted hypothesis that animals are related most closely to fungi, and that the two should be grouped together as the... more
Sequence-based molecular phylogenies have provided new models of early eukaryotic evolution. This includes the widely accepted hypothesis that animals are related most closely to fungi, and that the two should be grouped together as the Opisthokonta. Although most published phylogenies have supported an opisthokont relationship, a number of genes contain a tree-building signal that clusters animal and green plant sequences, to the exclusion of fungi. The alternative tree-building signal is especially intriguing in light of emerging data from genomic and proteomic studies that indicate striking and potentially synapomorphic similarities between plants and animals. This paper reviews these new lines of evidence, which have yet to be incorporated into models of broad scale eukaryotic evolution.
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Research Interests: Life history, Plant Cell Walls, Transposable Elements, Aquaculture, Gene expression, and 15 moreFossil record, Genome evolution, Expressed Sequence Tags, Elements, Genome Analysis, Red Algae, ribosomal RNA, Single Cell, microRNAs, Spores, Genome sequence, Mutants, Chloroplast, Cell Motility, and high light
Dinoflagellates are a peculiar group of protists with a surprising and varied history of plastid acquisition. They employ a variety of trophic strategies including photoautotrophy, heterotrophy, and mixotrophy, with multiple modes of food... more
Dinoflagellates are a peculiar group of protists with a surprising and varied history of plastid acquisition. They employ a variety of trophic strategies including photoautotrophy, heterotrophy, and mixotrophy, with multiple modes of food ingestion identified. This collection of features apparently preadapted dinoflagellates for acquisition of a bewildering array of photosynthetic bodies ranging from “stolen” plastids (or kleptoplastids) through permanent endosymbionts to true plastids, acquired in various primary, secondary, and tertiary endosymbioses. In this chapter, we focus on tertiary plastid endosymbioses (that is, uptake of an alga with a complex, secondary plastid), and especially on three that show distinct levels of host–endosymbiont integration. These endosymbiotic consortia are represented by (1) cryptophyte-derived kleptoplastids in Dinophysis species, (2) diatom endosymbionts in genera known as “dinotoms” (e.g., Kryptoperidinium and Durinskia), and (3) haptophyte-derived plastids in Karenia, Karlodinium, and Takayama. We discuss details of the structures, evolutionary origins, and processes involved in these varied endosymbioses, including feeding mechanisms, endosymbiotic gene transfer, and how nucleus-encoded proteins are targeted to each of these photosynthetic entities. Available data support previous predictions that all these photosynthetic bodies evolved via replacements of the peridinin plastid found in most photosynthetic dinoflagellates.
Research Interests: Biology and Endosymbiosis
The C-terminal domain (CTD) of the largest subunit (RPB1) of eukaryotic RNA polymerase II is essential for pol II function and has been shown to play a number of important roles in the mRNA transcription cycle. The CTD is composed of a... more
The C-terminal domain (CTD) of the largest subunit (RPB1) of eukaryotic RNA polymerase II is essential for pol II function and has been shown to play a number of important roles in the mRNA transcription cycle. The CTD is composed of a tandemly repeated heptapeptide that is conserved in yeast, animals, plants and several protistan organisms. Some eukaryotes, however, have what appear to be degenerate or deviant CTD regions, and others have no CTD at all. The functional and evolutionary implications of this variation among RPB1 C-termini is largely unexplored. We have transformed yeast cells with a construct consisting of the yeast RPB1 gene with 25 heptads from the primitive protist Mastigamoeba invertens in place of the wild-type CTD. The Mastigamoeba heptads differ from the canonical CTD by the invariable presence of alanines in place of threonines at position 4, and in place of serines at position 7 of each heptad. Despite this double substitution, mutants are viable even under conditions of temperature and nutrient stress. These results provide new insights into the relative functional importance of several of the conserved CTD residues, and indicate that in vivo expression of evolutionary variants in yeast can provide important clues for understanding the origin, evolution and function of the pol II CTD.
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Plastids evolved from free-living cyanobacteria through a process of primary endosymbiosis. The most widely accepted hypothesis derives three ancient lineages of primary plastids, i.e. those of glaucophytes, red algae and green plants,... more
Plastids evolved from free-living cyanobacteria through a process of primary endosymbiosis. The most widely accepted hypothesis derives three ancient lineages of primary plastids, i.e. those of glaucophytes, red algae and green plants, from a single cyanobacterial endosymbiosis. This hypothesis was originally predicated on the assumption that transformations of endosymbionts into organelles must be exceptionally rare because of the difficulty in establishing efficient protein trafficking between a host cell and incipient organelle. It turns out, however, that highly integrated endosymbiotic associations are more common than once thought. Among them is the amoeba Paulinella chromatophora, which harbours independently acquired cyanobacterial endosymbionts functioning as plastids. Sequencing of the Paulinella endosymbiont genome revealed an absence of essential genes for protein trafficking, suggesting their residence in the host nucleus and import of protein products back into the endosymbiont. To investigate this hypothesis, we searched the Paulinella endosymbiont genome for homologues of higher plant translocon proteins that form the import apparatus in two-membrane envelopes of primary plastids. We found homologues of Toc12, Tic21 and Tic32, but genes for other key translocon proteins (e.g. Omp85/Toc75 and Tic20) were missing. We propose that these missing genes were transferred to the Paulinella nucleus and their products are imported and integrated into the endosymbiont envelope membranes, thereby creating an effective protein import apparatus. We further suggest that other bacterial/cyanobacterial endosymbionts found in protists, plants and animals could have evolved efficient protein import systems independently and, therefore, reached the status of true cellular organelles.
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5. Discussion In recent years a consensus has emerged from molecular phylogenetic investigations favoring a common endosymbiotic ancestor for all chloroplasts. It is within this conceptual framework that most comparative analyses of... more
5. Discussion In recent years a consensus has emerged from molecular phylogenetic investigations favoring a common endosymbiotic ancestor for all chloroplasts. It is within this conceptual framework that most comparative analyses of eukaryotic biochemistry and genetics now are interpreted. One of the first and most influential sources of data leading to this consensus is the remarkable similarity in genome content among all major plastid lineages. Here we report statistical analyses of two sequence data sets, genes encoding ...
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ABSTRACT Recent advances in biotechnology have taken much of the guesswork out of many molecular biological procedures, and promote a high rate of success even for relative beginners. In designing the laboratory component of my Phycology... more
ABSTRACT Recent advances in biotechnology have taken much of the guesswork out of many molecular biological procedures, and promote a high rate of success even for relative beginners. In designing the laboratory component of my Phycology course, I have taken advantage of these improved methods to develop a semester-long, molecular-based class project, using “environmental PCR” to examine phytoplankton diversity. Students learn a number of common molecular techniques within the context of dynamic and unrehearsed phycological research. This provides a greater appreciation of the general utility of molecular technology, and its application to algal systems in particular. A series of easy to follow protocols are linked together, allowing students to PCR amplify sequences from mixed environmental samples, clone the resulting fragments to separate individual sequences, screen the clones by restriction enzyme digests and sequence clones with clearly different restriction patterns. The resulting sequences then are used in BLAST searches of GenBank to determine the nearest available match among sequences annotated previously. The techniques allow both qualitative and quantitative estimates of the organisms present, as well as comparative analyses of the diversity observed through direct visual observations versus those recovered by PCR. Each step of the procedure can be accomplished in the duration of a typical 3 hour lab period, and most involve intervals of incubation that permit adequate time for other lab exercises, such as a survey algal diversity, on which traditional phycological laboratories are based.
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The idea that evolutionary models should minimize plastid endosymbioses has dominated thinking about the history of eukaryotic photosynthesis. Although a reasonable starting point, this framework has not gained support from observed... more
The idea that evolutionary models should minimize plastid endosymbioses has dominated thinking about the history of eukaryotic photosynthesis. Although a reasonable starting point, this framework has not gained support from observed patterns of algal and plant evolution, and can be an obstacle to fully understanding the modern distribution of plastids. Empirical data indicate that plastid losses are extremely uncommon, that major changes in plastid biochemistry/architecture are evidence of an endosymbiotic event, and that comparable selection pressures can lead to remarkable convergences in algae with different endosymbiotic origins. Such empirically based generalizations can provide a more realistic philosophical framework for interpreting complex and often contradictory results from phylogenomic investigations of algal evolution.
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The red seaweed Porphyra (Bangiophyceae) and related Bangiales have global economic importance. Here, we report the analysis of a comprehensive transcriptome comprising ca. 4.7 million expressed sequence tag (EST) reads from P.... more
The red seaweed Porphyra (Bangiophyceae) and related Bangiales have global economic importance. Here, we report the analysis of a comprehensive transcriptome comprising ca. 4.7 million expressed sequence tag (EST) reads from P. umbilicalis (L.) J. Agardh and P. purpurea (Roth) C. Agardh (ca. 980 Mbp of data generated using 454 FLX pyrosequencing). These ESTs were isolated from the haploid gametophyte (blades from both species) and diploid conchocelis stage (from P. purpurea). In a bioinformatic analysis, only 20% of the contigs were found to encode proteins of known biological function. Comparative analysis of predicted protein functions in mesophilic (including Porphyra) and extremophilic red algae suggest that the former has more putative functions related to signaling, membrane transport processes, and establishment of protein complexes. These enhanced functions may reflect general mesophilic adaptations. A near-complete repertoire of genes encoding histones and ribosomal proteins was identified, with some differentially regulated between the blade and conchocelis stage in P. purpurea. This finding may reflect specific regulatory processes associated with these distinct phases of the life history. Fatty acid desaturation patterns, in combination with gene expression profiles, demonstrate differences from seed plants with respect to the transport of fatty acid/lipid among subcellular compartments and the molecular machinery of lipid assembly. We also recovered a near-complete gene repertoire for enzymes involved in the formation of sterols and carotenoids, including candidate genes for the biosynthesis of lutein. Our findings provide key insights into the evolution, development, and biology of Porphyra, an important lineage of red algae.
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Somatolactin (SL) is a pituitary hormone belonging to the growth hormone/prolactin superfamily, with recognizable homologues in all fish taxa examined to date. Although sequences from most fish share reasonably high sequence identity,... more
Somatolactin (SL) is a pituitary hormone belonging to the growth hormone/prolactin superfamily, with recognizable homologues in all fish taxa examined to date. Although sequences from most fish share reasonably high sequence identity, several more highly divergent SLs have been reported. Goldfish SL and a second SL protein found in rainbow trout (rtSLP) are remarkably different from each other and also dissimilar to other SLs. It has been unclear whether rtSLP is a recent paralogue restricted to rainbow trout, or reflects a more ancient duplication of the SL gene, and whether it is related to the goldfish sequence. Here we report the cloning of two different zebrafish SL cDNAs, which share only 57.5% nucleotide and 47.7% deduced amino acid identities. One copy, designated zebrafish SLalpha (zfSLalpha), displays a typical range of sequence similarity to most other SLs. The other copy, zebrafish SLbeta (zfSLbeta), shows low identity to most other SLs; surprisingly, it is most similar ...