Repeated evolution of a derived feature: insights from complementary sex determination

Trabalho de projeto do mestrado em Economia (Economia Financeira), apresentado à Faculdade de Economia da Universidade de Coimbra, sob a orientação de António Portugal e Rita MartinsO trabalho de projeto que se segue tem como objetivo principal refletir sobre os impactos económicos de um grande evento desportivo no país onde é organizado e realizado. Em primeiro lugar, são identificados os conceitos chave que permitem desenvolver uma correta interpretação do estudo. Da revisão da literatura teórica, apresentam-se autores que expõem os diversos impactos, não só económicos, mas também socioculturais, ambientais e na imagem exterior do país em questão. A análise prossegue com o estudo das variações do produto num conjunto de períodos em que se considera a presença do evento desportivo, comparativamente a períodos anteriores e posteriores, nos países que realizaram um grande evento desportivo como o Campeonato do Mundo de futebol, o Campeonato da Europa de futebol e os Jogos Olímpicos. Essa análise aponta para uma tendência de aceleração do crescimento económico quando ocorre um dos acontecimentos em estudo. Com recurso a estudos econométricos, calculam-se coeficientes que permitem estimar o efeito positivo destes eventos sobre o crescimento económico. De seguida, focando o Euro 2004 organizado e realizado em Portugal, verificam-se que infraestruturas foram construídas e de que forma foram financiadas, assim como os impactos decorrentes das mesmas, nomeadamente, o acréscimo na produção, o acréscimo de postos de trabalho e o acréscimo de rendimentos salariais. Ao nível da estatística descritiva são examinadas três variáveis, o número de hóspedes estrangeiros, a riqueza produzida e o emprego, nas regiões em que se construíram/remodelaram os estádios utilizados no Euro 2004, e comparadas estas variações, em cada região e no conjunto das regiões, com as variações no espaço nacional. Esta análise permite verificar taxas de crescimento, do conjunto das regiões, superiores às taxas de crescimento nacionais, nos períodos seguintes ao evento e, portanto, o efeito positivo do referido evento no turismo, assim como o impacto na taxa de crescimento da riqueza produzida, principalmente, no ano em que ocorreu o evento, e ainda, os efeitos sobre a distribuição da mão-de-obra no país, que mostram indícios de deslocação de mão-de-obra entre regiões. Em conclusão, a organização e realização de um grande evento desportivo pode ser um acontecimento que afeta positivamente o crescimento económico de um país, por via dos efeitos criadas pelas infraestruturas e por via da remodelação da imagem do país no exterior

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

Transgenic Overexpression of the Type I Isoform of Neuregulin 1 Affects Working Memory and Hippocampal Oscillations but not Long-term Potentiation

Neuregulin 1 (NRG1) is a growth factor involved in neurodevelopment and plasticity. It is a schizophrenia candidate gene, and hippocampal expression of the NRG1 type I isoform is increased in the disorder. We have studied transgenic mice overexpressing NRG1 type I (NRG1tg-type I) and their wild-type littermates and measured hippocampal electrophysiological and behavioral phenotypes. Young NRG1tg-type I mice showed normal memory performance, but in older NRG1tg-type I mice, hippocampus-dependent spatial working memory was selectively impaired. Hippocampal slice preparations from NRG1tg-type I mice exhibited a reduced frequency of carbachol-induced gamma oscillations and an increased tendency to epileptiform activity. Long-term potentiation in NRG1tg-type I mice was normal. The results provide evidence that NRG1 type I impacts on hippocampal function and circuitry. The effects are likely mediated via inhibitory interneurons and may be relevant to the involvement of NRG1 in schizophrenia. However, the findings, in concert with those from other genetic and pharmacological manipulations of NRG1, emphasize the complex and pleiotropic nature of the gene, even with regard to a single isoform

Independent Evolutionary Origin of <i>fem</i> Paralogous Genes and Complementary Sex Determination in Hymenopteran Insects

<div><p>The primary signal of sex determination in the honeybee, the <i>complementary sex determiner</i> (<i>csd</i>) gene, evolved from a gene duplication event from an ancestral copy of the <i>fem</i> gene. Recently, other paralogs of the <i>fem</i> gene have been identified in several ant and bumblebee genomes. This discovery and the close phylogenetic relationship of the paralogous gene sequences led to the hypothesis of a single ancestry of the <i>csd</i> genetic system of complementary sex determination in the Hymenopteran insects, in which the <i>fem</i> and <i>csd</i> gene copies evolved as a unit in concert with the mutual transfers of sequences (concerted evolution). Here, we show that the paralogous gene copies evolved repeatedly through independent gene duplication events in the honeybee, bumblebee, and ant lineage. We detected no sequence tracts that would indicate a DNA transfer between the <i>fem</i> and the <i>fem1/csd</i> genes between different ant and bee species. Instead, we found tracts of duplication events in other genomic locations, suggesting that gene duplication was a frequent event in the evolution of these genes. These and other evidences suggest that the <i>fem1/csd</i> gene originated repeatedly through gene duplications in the bumblebee, honeybee, and ant lineages in the last 100 million years. Signatures of concerted evolution were not detectable, implicating that the gene tree based on neutral synonymous sites represents the phylogenetic relationships and origins of the <i>fem</i> and <i>fem1/csd</i> genes. Our results further imply that the <i>fem1</i> and <i>csd</i> gene in bumblebees, honeybees, and ants are not orthologs, because they originated independently from the <i>fem</i> gene. Hence, the widely shared and conserved complementary sex determination mechanism in Hymenopteran insects is controlled by different genes and molecular processes. These findings highlight the limits of comparative genomics and emphasize the requirement to study gene functions in different species and major hymenopteran lineages.</p></div

The evolutionary fate of <i>fem</i> gene substitutions in an evolutionary window predating the putative repeated gene duplications.

<p>(<b>a</b>) The expected evolutionary fate of <i>fem</i> substitutions in the paralogous genes <i>fem</i> and <i>csd</i>/<i>fem1</i> under the model of concerted evolution and repeated gene duplication. (<b>b, c</b>) The letters above the yellow boxes show the inferred amino acid changes in the Fem protein tree that evolved during the evolutionary window of the MRCA of ants and bees and the MRCAs of ants (<b>b</b>) and of bees (<b>c</b>). Letters above the blue boxes indicate the amino acid residues that are found at the homologous sites in the ancestral Csd/Fem1 protein sequence of the MRCA of ants (<b>b</b>) and of bees (<b>c</b>). Numbers above the letters designate the homologous sites in the Fem amino acid sequence alignment. Numbers before the boxes indicate the nodes (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091883#pone.0091883.s002" target="_blank">Fig. S2</a>) used to infer the ancestral sequence information. aa denotes amino acid.</p

Two models for the evolutionary history of <i>fem</i> paralogous genes in ants and bees: (a) repeated gene duplication and (b) concerted evolution.

<p>Points in (<b>a</b>) denote gene duplication events giving rise to two gene copies. Connecting lines in (<b>b</b>) between branches indicate concerted evolution events resulting from unequal crossing over and/or gene conversion.</p

The evolutionary trajectory of <i>fem</i> gene substitutions in the evolutionary window that follows the putative gene duplication event in the <i>Bombus</i> lineage.

<p>(<b>a</b>) The expected evolutionary fate of <i>fem</i> substitutions in the paralogous genes <i>fem</i> and <i>fem1</i> under the models of concerted evolution and repeated gene duplication. (<b>b</b>) Deduced amino acid changes. The yellow box indicates the Fem protein, and the blue box indicates the Fem1 protein. Black letters above the boxes indicate the ancestral state of the amino acid residues found in the MRCA of <i>B. terrestris</i> and <i>B. impatiens</i>. Red letters in the red frame indicate the amino acid residues that evolved since the MRCA of <i>B. terrestris</i> and <i>B. impatiens</i> in the Fem protein. Blue letters in the blue frame indicate the amino acid residues that evolved since the MRCA of <i>B. terrestris</i> and <i>B. impatiens</i> in the Fem1 protein. Numbers before the boxes indicate the nodes (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091883#pone.0091883.s002" target="_blank">Fig. S2</a>) used to infer the ancestral sequence information. aa denotes amino acid.</p

Pseudogenes (<i>ps</i>) of the <i>fem</i> and <i>csd</i> genes in the ant, bumblebee and western honeybee genomes.

<p>(<b>a</b>) The orientation and location of the pseudogenes (<i>psfem</i>, <i>pscsd</i>). Boxes denote the genes or pseudogenes. The box length of pseudogenes indicates the relative degree of homology to the coding nucleotide sequences of the <i>fem</i> or <i>csd</i> genes. The phylogenetic relationship assignments are based on the lowest <i>d_S</i> estimates or the ancestral state. Numbers behind the bars indicate the genomic scaffold, linkage group or the GenBank accession number. (<b>b</b>) Evolutionary distance between duplicated <i>fem</i> and <i>fem1/csd</i> gene copies are presented in terms of pairwise synonymous divergence per synonymous site (<i>d_S</i>). Abbreviations<i>: Amel</i>, <i>A. mellifera</i>; <i>Bimp</i>, <i>B. impatiens</i>; <i>Bter</i>, <i>B. terrestris</i>; <i>Hsal</i>, <i>H. saltator</i>; <i>Pbar</i>, <i>P. barbatus.</i></p