Construction and analysis of full-length and normalized cDNA libraries from citrus

[EN] We have developed an integrated method to generate a normalized cDNA collection enriched in full-length and rare transcripts from citrus, using different species and multiple tissues and developmental stages. Interpretation of ever-increasing raw sequence information generated by modern genome sequencing technologies faces multiple challenges, such as gene function analysis and genome annotation. In this regard, the availability of full-length cDNA clones facilitates functional analysis of the corresponding genes enabling manipulation of their expression and the generation of a variety of tagged versions of the native protein. The development of full-length cDNA sequences has the power to improve the quality of genome annotation, as well as provide tools for functional characterization of genesThe authors would like to thank to all participants in the Spanish Citrus Functional Genomic Project, specially to Drs. Javier Forment, Jose Gadea, and Vicente Conejero. This work was funded by grants from the Spanish Government GEN2001-4885-CO5-01 and GEN2001-4885-CO5-02.Marques, MC.; Perez Amador, MA. (2012). Construction and analysis of full-length and normalized cDNA libraries from citrus. Functional Genomics: Methods and Protocols. 815:51-65. https://doi.org/10.1007/978-1-61779-424-7_5S5165815Carninci P, Kvam C, Kitamura A, Ohsumi T, Okazaki Y, Itoh M, Kamiya M, Shibata K, Sasaki N, Izawa M, Muramatsu M, Hayashizaki Y, and Schneider C (1996) High-efficiency full-length cDNA cloning by biotinylated CAP trapper. Genomics 37 327–336.Carninci P, Shibata Y, Hayatsu N, Sugahara Y, Shibata K, Itoh M, Konno H, Okazaki Y, Muramatsu M, and Hayashizaki Y (2000) Normalization and subtraction of CAP-trapper-selected cDNAs to prepare full-length cDNA libraries for rapid discovery of new genes. Genome Res. 10, 1617–1630.Suzuki Y, and Sugano S (2003) Construction of a full-length enriched and a 5’-end enriched cDNA library using the Oligo-capping method. Methods Mol. Biol. 221 73–91.Clepet C, Le Clainche I, and Caboche M (2004) Improved full-length cDNA production based on RNA tagging by T4 DNA ligase. Nucleic Acids Res. 32 e6.Zhu YY, Machleder EM, Chenchik A, Li R, and Siebert PD (2001) Reverse transcriptase template switching: a SMART approach for full-length cDNA library construction. Biotechniques 30 892–897.Zhulidov PA, Bogdanova EA, Shcheglov AS, Vagner LL, Khaspekov GL, Kozhemyako VB, Matz MV, Meleshkevitch E, Moroz LL, Lukyanov SA, and Shagin DA (2004) Simple cDNA normalization using Kamchatka crab duplex-specific nuclease. Nucleic Acids Res. 32 e37.Zhulidov PA, Bogdanova EA, Shcheglov AS, Shagina IA, Wagner LL, Khazpekov GL, Kozhemyako VV, Lukyanov SA, and Shagin DA (2005) A method for the preparation of normalized cDNA libraries enriched with full-length sequences. Russian J. Bioorg. Chem. 31 170–177.Anisimova VE, Rebrikov DV, Zhulidov PA, Staroverov DB, Lukyanov SA, and Shcheglov AS (2006) Renaturation, activation, and practical use of recombinant duplex-specific nuclease from Kamchatka crab. Biochem.-Moscow 71 513–519.Toru M, Matsui T, Heidaran MA, and Aaronson SA (1989) An efficient directional cloning system to construct cDNA libraries containing full-length inserts at high frequency. Gene 83 137–146.Castelli V, Aury JM, Jaillon O, Wincker P, Clepet C, Menard M, Cruaud C, Quétier F, Scarpelli C, Schächter V, Temple G, Caboche M, Weissenbach J, and Salanoubat M (2004) Whole genome sequence comparisons and “Full-length” cDNA sequences: a combined approach to evaluate and improve Arabidopsis genome annotation. Genome Res. 14 406–413.Earley KW, Haag JR, Pontes O, Opper K, Juehne T, Song KM, and Pikaard CS (2006) Gateway-compatible vectors for plant functional genomics and proteomics. Plant J. 45 616–629.Karimi M, Inzé D, and Depicker A (2002) GATEWAY™ vectors for Agrobacterium- mediated plant transformation. TRENDS Plant Sci. 7 193–195.Hartley JL, Temple GF, and Brasch MA (2000) DNA cloning using in vitro site-specific recombination. Genome Res. 10 1788–1795.Marques M C, Alonso-Cantabrana H, Forment J, Arribas R, Alamar S, Conejero V, and Perez-Amador MA (2009) A new set of ESTs and cDNA clones from full-length and normalized libraries for gene discovery and functional characterization in citrus. BMC Genomics 10, 428

Evolution of a New Function by Degenerative Mutation in Cephalochordate Steroid Receptors

Gene duplication is the predominant mechanism for the evolution of new genes. Major existing models of this process assume that duplicate genes are redundant; degenerative mutations in one copy can therefore accumulate close to neutrally, usually leading to loss from the genome. When gene products dimerize or interact with other molecules for their functions, however, degenerative mutations in one copy may produce repressor alleles that inhibit the function of the other and are therefore exposed to selection. Here, we describe the evolution of a duplicate repressor by simple degenerative mutations in the steroid hormone receptors (SRs), a biologically crucial vertebrate gene family. We isolated and characterized the SRs of the cephalochordate Branchiostoma floridae, which diverged from other chordates just after duplication of the ancestral SR. The B. floridae genome contains two SRs: BfER, an ortholog of the vertebrate estrogen receptors, and BfSR, an ortholog of the vertebrate receptors for androgens, progestins, and corticosteroids. BfSR is specifically activated by estrogens and recognizes estrogen response elements (EREs) in DNA; BfER does not activate transcription in response to steroid hormones but binds EREs, where it competitively represses BfSR. The two genes are partially coexpressed, particularly in ovary and testis, suggesting an ancient role in germ cell development. These results corroborate previous findings that the ancestral steroid receptor was estrogen-sensitive and indicate that, after duplication, BfSR retained the ancestral function, while BfER evolved the capacity to negatively regulate BfSR. Either of two historical mutations that occurred during BfER evolution is sufficient to generate a competitive repressor. Our findings suggest that after duplication of genes whose functions depend on specific molecular interactions, high-probability degenerative mutations can yield novel functions, which are then exposed to positive or negative selection; in either case, the probability of neofunctionalization relative to gene loss is increased compared to existing models

Inferring selection in the Anopheles gambiae species complex: an example from immune-related serine protease inhibitors

<p>Abstract</p> <p>Background</p> <p>Mosquitoes of the <it>Anopheles gambiae </it>species complex are the primary vectors of human malaria in sub-Saharan Africa. Many host genes have been shown to affect <it>Plasmodium </it>development in the mosquito, and so are expected to engage in an evolutionary arms race with the pathogen. However, there is little conclusive evidence that any of these mosquito genes evolve rapidly, or show other signatures of adaptive evolution.</p> <p>Methods</p> <p>Three serine protease inhibitors have previously been identified as candidate immune system genes mediating mosquito-Plasmodium interaction, and serine protease inhibitors have been identified as hot-spots of adaptive evolution in other taxa. Population-genetic tests for selection, including a recent multi-gene extension of the McDonald-Kreitman test, were applied to 16 serine protease inhibitors and 16 other genes sampled from the <it>An. gambiae </it>species complex in both East and West Africa.</p> <p>Results</p> <p>Serine protease inhibitors were found to show a marginally significant trend towards higher levels of amino acid diversity than other genes, and display extensive genetic structuring associated with the 2La chromosomal inversion. However, although serpins are candidate targets for strong parasite-mediated selection, no evidence was found for rapid adaptive evolution in these genes.</p> <p>Conclusion</p> <p>It is well known that phylogenetic and population history in the <it>An. gambiae </it>complex can present special problems for the application of standard population-genetic tests for selection, and this may explain the failure of this study to detect selection acting on serine protease inhibitors. The pitfalls of uncritically applying these tests in this species complex are highlighted, and the future prospects for detecting selection acting on the <it>An. gambiae </it>genome are discussed.</p

Complementary Proteomic and Biochemical Analysis of Peptidases in Lobster Gastric Juice Uncovers the Functional Role of Individual Enzymes in Food Digestion

Crustaceans are a diverse group, distributed in widely variable environmental conditions for which they show an equally extensive range of biochemical adaptations. Some digestive enzymes have been studied by purification/characterization approaches. However, global analysis is crucial to understand how digestive enzymes interplay. Here, we present the first proteomic analysis of the digestive fluid from a crustacean (Homarus americanus) and identify glycosidases and peptidases as the most abundant classes of hydrolytic enzymes. The digestion pathway of complex carbohydrates was predicted by comparing the lobster enzymes to similar enzymes from other crustaceans. A novel and unbiased substrate profiling approach was used to uncover the global proteolytic specificity of gastric juice and determine the contribution of cysteine and aspartic acid peptidases. These enzymes were separated by gel electrophoresis and their individual substrate specificities uncovered from the resulting gel bands. This new technique is called zymoMSP. Each cysteine peptidase cleaves a set of unique peptide bonds and the S2 pocket determines their substrate specificity. Finally, affinity chromatography was used to enrich for a digestive cathepsin D1 to compare its substrate specificity and cold-adapted enzymatic properties to mammalian enzymes. We conclude that the H. americanus digestive peptidases may have useful therapeutic applications, due to their cold-adaptation properties and ability to hydrolyze collagen