Maria de la Paz Celorio-Mancera

Bio: Maria de la Paz Celorio-Mancera is an academic researcher from Stockholm University. The author has contributed to research in topics: Colias & Host (biology). The author has an hindex of 12, co-authored 23 publications receiving 596 citations. Previous affiliations of Maria de la Paz Celorio-Mancera include University of California, Davis & Max Planck Society.

Mechanisms of macroevolution: polyphagous plasticity in butterfly larvae revealed by RNA-Seq

Abstract: Transcriptome studies of insect herbivory are still rare, yet studies in model systems have uncovered patterns of transcript regulation that appear to provide insights into how insect herbivores attain polyphagy, such as a general increase in expression breadth and regulation of ribosomal, digestion- and detoxification-related genes. We investigated the potential generality of these emerging patterns, in the Swedish comma, Polygonia c-album, which is a polyphagous, widely-distributed butterfly. Urtica dioica and Ribes uva-crispa are hosts of P. c-album, but Ribes represents a recent evolutionary shift onto a very divergent host. Utilizing the assembled transcriptome for read mapping, we assessed gene expression finding that caterpillar life-history (i.e. 2nd vs. 4th-instar regulation) had a limited influence on gene expression plasticity. In contrast, differential expression in response to host-plant identified genes encoding serine-type endopeptidases, membrane-associated proteins and transporters. Differential regulation of genes involved in nucleic acid binding was also observed suggesting that polyphagy involves large scale transcriptional changes. Additionally, transcripts coding for structural constituents of the cuticle were differentially expressed in caterpillars in response to their diet indicating that the insect cuticle may be a target for plant defence. Our results state that emerging patterns of transcript regulation from model species appear relevant in species when placed in an evolutionary context.

Transcriptional responses underlying the hormetic and detrimental effects of the plant secondary metabolite gossypol on the generalist herbivore Helicoverpa armigera.

Abstract: Background Hormesis is a biphasic biological response characterized by the stimulatory effect at relatively low amounts of chemical compounds which are otherwise detrimental at higher concentrations. A hormetic response in larval growth rates has been observed in cotton-feeding insects in response to increasing concentrations of gossypol, a toxic metabolite found in the pigment glands of some plants in the family Malvaceae. We investigated the developmental effect of gossypol in the cotton bollworm, Helicoverpa armigera, an important heliothine pest species, by exposing larvae to different doses of this metabolite in their diet. In addition, we sought to determine the underlying transcriptional responses to different gossypol doses.

Transcriptome responses in herbivorous insects towards host plant and toxin feeding

Abstract: Food source is a major determinant of physiological performance and a strong selection force for insect herbivores. The ability to adequately respond to chemical challenges posed by their host plants is the primary determinant of larval fitness. Most herbivorous insects must consume large quantities of plant material to meet their nutritional requirements and, at the same time, cope with numerous mechanical, chemical and protein-based defences posed by their sessile hosts. Despite the importance of host plants on essential life history traits of insect herbivores, data on global responses to both individual plant-derived compounds and plant feeding is scarce. Here we discuss the existing data on herbivore responses to host plant exposure, toxin feeding or nutrient limitations, and we make an attempt at identifying changes in genome-wide expression patterns of generalist and/or specialist herbivores. While generalists face an array of different plant defences, and therefore likely need to invest in broad detoxifying strategies, specialist herbivores need to fine-tune their adaptation to specific plant defences.

Unprecedented reorganization of holocentric chromosomes provides insights into the enigma of lepidopteran chromosome evolution.

Abstract: Chromosome evolution presents an enigma in the mega-diverse Lepidoptera. Most species exhibit constrained chromosome evolution with nearly identical haploid chromosome counts and chromosome-level gene collinearity among species more than 140 million years divergent. However, a few species possess radically inflated chromosomal counts due to extensive fission and fusion events. To address this enigma of constraint in the face of an exceptional ability to change, we investigated an unprecedented reorganization of the standard lepidopteran chromosome structure in the green-veined white butterfly (Pieris napi). We find that gene content in P. napi has been extensively rearranged in large collinear blocks, which until now have been masked by a haploid chromosome number close to the lepidopteran average. We observe that ancient chromosome ends have been maintained and collinear blocks are enriched for functionally related genes suggesting both a mechanism and a possible role for selection in determining the boundaries of these genome-wide rearrangements.

Transcriptional analysis of physiological pathways in a generalist herbivore: responses to different host plants and plant structures by the cotton bollworm, Helicoverpa armigera

Abstract: The generalist cotton bollworm, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), can consume host plants in more than 40 families, and often utilizes several tissues of a single plant. It is believed that generalists owe their success to the deployment of various members of multigene families of detoxification and digestive enzymes, a strategy that may also be responsible for rapid evolution of insecticide resistance. However, studies of generalist adaptations have been limited to specific genes or gene families, and an overview of how these adaptations are orchestrated at the transcriptional level is lacking. We used Drosophila melanogaster Meigen gene homology to H. armigera-expressed sequence tags to identify key groups of genes and pathways differentially regulated in the gut of fifth instars after 2 days of feeding on a variety of food sources. A series of microarray hybridizations was performed following two alternating loop designs, one comparing the gut gene expression upon feeding on various hosts (cotton, bean, tobacco, and chickpea) and two artificial diets (pinto bean and wheat germ-based), whereas the second design compared the gut expression toward feeding on various plant structures within cotton (leaf, square, and boll). The transcriptional responses toward bean and tobacco feeding treatments were more closely related in comparison with the rest of the diets, whereas the gene expression profiles toward cotton leaf and square-feeding were highly similar. We furthermore found significant changes in several pathways not directly responsible for detoxification mechanisms. Genes involved in primary and secondary metabolism, environmental information processing, and cellular processes were found to be differentially expressed. In addition, regulation of xenobiotic metabolism and the extracellular matrix-receptor pathways appeared differentially regulated across feeding treatments. Three cytochrome P450 genes – CYP6AE17, CYP6B6, and CYP9A17 – grouped as part of a xenobiotic metabolism pathway, were up-regulated in the bean-feeding treatment, and down-regulated in both tobacco and cotton-feeding treatments. CYP4L11, CYP4L5, and CYP4S13 were differentially expressed upon feeding on different cotton plant structures. The present work provides host plant and plant structure-specific transcriptional responses in a lepidopteran herbivore, including pathways and gene candidates for future studies of H. armigera physiology under a more integrative ecologically meaningful framework.

Rapid transcriptional plasticity of duplicated gene clusters enables a clonally reproducing aphid to colonise diverse plant species

Abstract: The prevailing paradigm of host-parasite evolution is that arms races lead to increasing specialisation via genetic adaptation. Insect herbivores are no exception and the majority have evolved to colonise a small number of closely related host species. Remarkably, the green peach aphid, Myzus persicae, colonises plant species across 40 families and single M. persicae clonal lineages can colonise distantly related plants. This remarkable ability makes M. persicae a highly destructive pest of many important crop species. To investigate the exceptional phenotypic plasticity of M. persicae, we sequenced the M. persicae genome and assessed how one clonal lineage responds to host plant species of different families. We show that genetically identical individuals are able to colonise distantly related host species through the differential regulation of genes belonging to aphid-expanded gene families. Multigene clusters collectively upregulate in single aphids within two days upon host switch. Furthermore, we demonstrate the functional significance of this rapid transcriptional change using RNA interference (RNAi)-mediated knock-down of genes belonging to the cathepsin B gene family. Knock-down of cathepsin B genes reduced aphid fitness, but only on the host that induced upregulation of these genes. Previous research has focused on the role of genetic adaptation of parasites to their hosts. Here we show that the generalist aphid pest M. persicae is able to colonise diverse host plant species in the absence of genetic specialisation. This is achieved through rapid transcriptional plasticity of genes that have duplicated during aphid evolution.

A link between host plant adaptation and pesticide resistance in the polyphagous spider mite Tetranychus urticae.

Abstract: Plants produce a wide range of allelochemicals to defend against herbivore attack, and generalist herbivores have evolved mechanisms to avoid, sequester, or detoxify a broad spectrum of natural defense compounds. Successful arthropod pests have also developed resistance to diverse classes of pesticides and this adaptation is of critical importance to agriculture. To test whether mechanisms to overcome plant defenses predispose the development of pesticide resistance, we examined adaptation of the generalist two-spotted spider mite, Tetranychus urticae, to host plant transfer and pesticides. T. urticae is an extreme polyphagous pest with more than 1,100 documented hosts and has an extraordinary ability to develop pesticide resistance. When mites from a pesticide-susceptible strain propagated on bean were adapted to a challenging host (tomato), transcriptional responses increased over time with ∼7.5% of genes differentially expressed after five generations. Whereas many genes with altered expression belonged to known detoxification families (like P450 monooxygenases), new gene families not previously associated with detoxification in other herbivores showed a striking response, including ring-splitting dioxygenase genes acquired by horizontal gene transfer. Strikingly, transcriptional profiles of tomato-adapted mites resembled those of multipesticide-resistant strains, and adaptation to tomato decreased the susceptibility to unrelated pesticide classes. Our findings suggest key roles for both an expanded environmental response gene repertoire and transcriptional regulation in the life history of generalist herbivores. They also support a model whereby selection for the ability to mount a broad response to the diverse defense chemistry of plants predisposes the evolution of pesticide resistance in generalists.

Oxidative Stress and Hormesis in Evolutionary Ecology and Physiology

Abstract: The transition from a reducing to an oxidising chemistry in the atmosphere and oceans paved the way for the diversification of life. Oxygen expanded metabolic and biochemical capacities of organisms. Over the incipient stages of evolution of oxidative metabolism, organisms also needed to develop mechanisms to mitigate the toxic effects of oxygen derivatives, such as free radicals and nonradical reactive species. This chapter provides a general historical background, with definitions and information of free radicals, antioxidants and oxidative stress. This chapter also examines how mild doses of stress can have stimulatory effects on organismal performance through hormetic mechanisms and that this may significantly relate to evolutionary fitness and to the ecology of species. Finally, the chapter explains the concept of life-history trade-offs and highlights how the need to manage oxidative stress in an optimal way may be an important mechanism driving the outcome of many of these trade-offs. 1.1 The Great Oxidation Event: From a Reducing to an Oxidising World The planet Earth is approximately 4.5 billion years old. The atmosphere of the primeval Earth was quite different from what we observe nowadays. It was mildly reducing, with large proportions of methane, ammonia and hydrogen and a low concentration of oxygen (Schopf and Klein 1992; Sessions et al. 2009). Around 2.45 billion years ago, atmospheric oxygen rose suddenly in what is now termed the Great Oxidation Event (Sessions et al. 2009). A second significant increase in atmospheric oxygen occurred at around 600–800 million years ago and was accompanied by the oxygenation of the deep oceans and emergence of multicellular animals (Sessions et al. 2009). The increase in oxygen concentration in the atmosphere and oceans paved the way for the diversification of life (Fig. 1.1). D. Costantini, Oxidative Stress and Hormesis in Evolutionary Ecology and Physiology, DOI: 10.1007/978-3-642-54663-1_1, Springer-Verlag Berlin Heidelberg 2014 1 The transition from a reducing to an oxidising atmosphere was characterised by the evolution of metabolic networks of increasing complexity (Raymond and Segrè 2006). Adaptation to molecular oxygen has also likely taken place independently in species from diverse lineages, even if it is unclear whether it contributed to shaping taxonomical diversity (Raymond and Segrè 2006). Certainly, oxygen expanded metabolic and biochemical capacities of organisms. The stimulatory effect of oxygen on the evolution of metabolic networks was not cost-free. Beyond diversification of mechanisms using oxygen to produce energy, organisms also needed to evolve mechanisms to mitigate the toxic effects of oxygen derivatives, such as free radicals and non-radical reactive species. 1.2 Reactive Species, Antioxidants and Oxidative Stress 1.2.1 On the Nature of Free Radicals and Other Reactive Species The discovery of organic free radicals dates back to over a century ago, when the scientist Gomberg (1900) at the University of Michigan identified the triphenylmethyl The primeval Earth’s atmosphere was mildly reducing. Photochemical reactions between simple gas elements 2H2 + CO2 → H2CO + H2O Evolution of anaerobic bacteria H2S + CO2 → (H2CO)n + S Evolution of photosynthetic organisms H2O + CO2 → (H2CO)n + O2 Evolution of aerobic eukaryotes; aerobic pathways produce much more energy than anaerobic pathways O2 + (H2CO)n → H2O + CO2 Aerobic pathways generate oxygen free radicals and non-radical species. Hence, evolution of antioxidant mechanisms to cope with oxidative stress. Fig. 1.1 Sequence of main transitions in energetic metabolism induced by changes in atmosphere and ocean chemistry (see Falkowski 2006) 2 1 Historical and Contemporary Issues of Oxidative Stress