Involvement of the conserved Hox gene Antennapedia in the development and evolution of a novel trait

<p>Abstract</p> <p>Background</p> <p>Hox proteins specify segment identity during embryogenesis and have typical associated expression patterns. Changes in embryonic expression and activity of <it>Hox </it>genes were crucial in the evolution of animal body plans, but their role in the post-embryonic development of lineage-specific traits remains largely unexplored. Here, we focus on the insect <it>Hox </it>genes <it>Ultrabithorax </it>(<it>Ubx</it>) and <it>Antennapedia </it>(<it>Antp</it>), and implicate the latter in the formation and diversification of novel, butterfly-specific wing patterns.</p> <p>Results</p> <p>First, we describe a conserved pattern of <it>Ubx </it>expression and a novel pattern of <it>Antp </it>expression in wing discs of <it>Bicyclus anynana </it>butterflies. The discrete, reiterated domains of Antp contrast with the typical expression of Hox genes in single continuous regions in arthropod embryos. Second, we show that this pattern is associated with the establishment of the organizing centres of eyespots. <it>Antp </it>upregulation is the earliest event in organizer development described to date, and in contrast to all genes implicated in eyespot formation, is exclusive to those centres. Third, our comparative analysis of gene expression across nymphalids reveals unexpected differences in organizer determination.</p> <p>Conclusions</p> <p>We show that the Antp's recruitment for the formation of novel traits in butterfly wing discs involved the evolution of new expression domains, and is restricted to a particular lineage. This study contributes novel insights into the evolution of <it>Antp </it>expression, as well as into the genetic mechanisms underlying morphological diversification. Our results also underscore how a wider representation of morphological and phylogenetic diversity is essential in evolutionary developmental biology.</p

Co-option of hedgehog and wingless pathways in the formation of evolutionary novelties

Tese de mestrado, Biologia (Biologia Evolutiva e do Desenvolvimento), 2009, Universidade de Lisboa, Faculdade de CiênciasResumo alargado em português disponível no documentoThe world is like a biological diversity accumulator and understanding the mechanisms responsible for the generation of this diversity is a fascinating theme in biology. The diversification of patterns and shapes can be accomplished by the origin of novelties lineage specific traits of new adaptive value. Much recent data suggest that novelties can arise from co-option: recycling of shared genetic circuitry. One of the most beautiful examples of this is found in butterfly wing patterns. Some wings have conspicuous circular paintings called eyespots development of which is divided in four main stages: prepattern, focus determination, focal signaling and cellular differentiation. There are some gaps in our knowledge about genes involved in this pattern design. Experiments with Junonia coenia revealed the expression of hedgehog around the foci in larvae, and, in Bicyclus anynana pupae, imunohistochemistry analysis showed the expression of Wingless, also a morphogen. Here, we studied the co-option of those two signaling pathways in formation of novelties using in situ hybridization to detect spatial patterns of gene expression. hedgehog was found only in the posterior area of larval wings with no higher expression around the foci as observed for J. coenia. On the other hand, it was detected that both sense and anti-sense transcripts for wingless were being expressed in eyespot foci at the same time. A model was designed to explain this finding that requires that different cells should be expressing wingless mRNA and anti-transcript. To have a better comprehension about Hedgehog and Wingless pathways involvement in eyespot formation we also analyzed expression of other genes: patched (hedgehog receptor), frizzled (wingless receptor) and groucho (a negative regulator of wingless signal transduction). However, there is still a lot to be done and the necessity of functional tests is clear

Effects ofWolbachiaon Transposable Element Expression Vary BetweenDrosophila melanogasterHost Genotypes

Transposable elements (TEs) are repetitive DNA sequences capable of changing position in host genomes, thereby causing mutations. TE insertions typically have deleterious effects but they can also be beneficial. Increasing evidence of the contribution of TEs to adaptive evolution further raises interest in understanding what factors impact TE activity. Based on previous studies associating the bacterial endosymbiont Wolbachia with changes in the abundance of piRNAs, a mechanism for TE repression, and to transposition of specific TEs, we hypothesized that Wolbachia infection would interfere with TE activity. We tested this hypothesis by studying the expression of 14 TEs in a panel of 25 Drosophila melanogaster host genotypes, naturally infected with Wolbachia and annotated for TE insertions. The host genotypes differed significantly in Wolbachia titers inside individual flies, with broad-sense heritability around 20%, and in the number of TE insertions, which depended greatly on TE identity. By removing Wolbachia from the target host genotypes, we generated a panel of 25 pairs of Wolbachia-positive and Wolbachia-negative lines in which we quantified transcription levels for our target TEs. We found variation in TE expression that was dependent on Wolbachia status, TE identity, and host genotype. Comparing between pairs of Wolbachia-positive and Wolbachia-negative flies, we found that Wolbachia removal affected TE expression in 21.1% of the TE-genotype combinations tested, with up to 2.3 times differences in the median level of transcript. Our data show that Wolbachia can impact TE activity in host genomes, underscoring the importance this endosymbiont can have in the generation of genetic novelty in hosts.info:eu-repo/semantics/publishedVersio

Wolbachia-Conferred Antiviral Protection Is Determined by Developmental Temperature

Insects are often infected with beneficial intracellular bacteria. The bacterium Wolbachi

Wolbachia Variants Induce Differential Protection to Viruses in Drosophila melanogaster: A Phenotypic and Phylogenomic Analysis

Wolbachia are intracellular bacterial symbionts that are able to protect various insect hosts from viral infections. This tripartite interaction was initially described in Drosophila melanogaster carrying wMel, its natural Wolbachia strain. wMel has been shown to be genetically polymorphic and there has been a recent change in variant frequencies in natural populations. We have compared the antiviral protection conferred by different wMel variants, their titres and influence on host longevity, in a genetically identical D. melanogaster host. The phenotypes cluster the variants into two groups--wMelCS-like and wMel-like. wMelCS-like variants give stronger protection against Drosophila C virus and Flock House virus, reach higher titres and often shorten the host lifespan. We have sequenced and assembled the genomes of these Wolbachia, and shown that the two phenotypic groups are two monophyletic groups. We have also analysed a virulent and over-replicating variant, wMelPop, which protects D. melanogaster even better than the closely related wMelCS. We have found that a ~21 kb region of the genome, encoding eight genes, is amplified seven times in wMelPop and may be the cause of its phenotypes. Our results indicate that the more protective wMelCS-like variants, which sometimes have a cost, were replaced by the less protective but more benign wMel-like variants. This has resulted in a recent reduction in virus resistance in D. melanogaster in natural populations worldwide. Our work helps to understand the natural variation in wMel and its evolutionary dynamics, and inform the use of Wolbachia in arthropod-borne disease control.FCT PhD fellowship: (SFRH/BD/51625/2011), Royal Society University Research Fellowship

Dinâmicas de (investig)ação em contextos de promoção da língua portuguesa: a presença do CIDTFF na rede Camões, I.P.

Sem resumo disponível.publishe

The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AIM: The SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery. METHODS: This was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin. RESULTS: Overall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P < 0.001). After adjustment, delay was not associated with a lower rate of complete resection (OR 1.18, 95% CI 0.90-1.55, P = 0.224), which was consistent in elective patients only (OR 0.94, 95% CI 0.69-1.27, P = 0.672). Longer delays were not associated with poorer outcomes. CONCLUSION: One in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

Effects of envirnonmental and genetic factors on transposable element activity

Heritable phenotypic variation is the raw material for evolution to occur through natural selection. It is a pervasive property of living organisms and, in order to understand evolutionary processes, we must study the factors that mediate the production of heritable phenotypic, and therefore genotypic variation. Transposable elements (TEs) are mobile DNA sequences that constitute a large proportion of most eukaryotic genomes and that can drive the production of adaptive genetic variation. There are many studies on transposon mobility, but these generally include only few environmental conditions, TEs and genetic backgrounds. As a consequence, we still know very little about the impact of genetic and environmental factors that can affect transposon dynamics in natural populations. Here, I proposed to overcome those limitations by analysing the impact of a multitude of factors on transposon mobility using Drosophila melanogaster as a model organism. (…)Instituto Gulbenkian de Ciênci

High anti-viral protection without immune upregulation after interspecies Wolbachia transfer

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Expression of antimicrobial peptide genes in <i>Wolbachia</i>-free <i>iso</i>, <i>w</i>Au and <i>w</i>MelCS_b harbouring flies.

<p>qRT-PCR on the RNA collected from 3–6 days-old whole flies performed with the primers specific for <i>Defensin</i> (A), <i>Diptericin</i> (B) <i>Cecropin A1</i> (C) and <i>Drosomycin</i> (D). Relative expression of the host antimicrobial peptide genes was calculated using host Rpl32 as a reference. Values are relative to median of samples of <i>w</i>MelCS_b. The only statistically significant difference is in <i>Diptericin</i> gene expression between <i>iso</i> and <i>w</i>MelCS_b (pairwise Wilcoxon rank sum test, <i>p</i> = 0.006).</p