The Impact of Climatic Changes on Ant Distributions

Dissertação de mestrado em Biologia Celular e Molecular apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra.A retinopatia diabética é uma das principais complicações da diabetes mellitus, sendo considerada uma das principais causas de perda de visão e cegueira em adultos em idade activa nos países desenvolvidos. O dobesilate de cálcio (CaD) é um derivado sintético do sulfonato de benzeno, utilizado no tratamento da retinopatia diabética. Clinicamente, a sua eficácia foi demonstrada, principalmente, através da correcção da excessiva permeabilidade vascular na retina em pacientes diabéticos e em diabetes experimental. Contudo, os mecanismos moleculares e celulares dos fármacos envolvidos nesses efeitos não estão ainda completamente esclarecidos. Os efeitos protectores do CaD podem estar relacionados com as suas propriedades antioxidantes ou, possivelmente, com uma acção anti-inflamatória. Assim, este estudo teve como principal objectivo elucidar o efeito do tratamento com o CaD na inflamação e no stress oxidativo/nitrosativo induzidos na retina pela diabetes, utilizando para isso um modelo animal de diabetes. Ratos Wistar foram divididos em 4 grupos: controlos, animais tratados com CaD, diabéticos (2 meses de duração da diabetes) e diabéticos tratados com CaD (100 mg/kg/dia; administrado oralmente durante as duas últimas semanas). Devido à natureza inflamatória da retinopatia diabética, a reactividade glial foi avaliada nas células de Müller e nos astrócitos na retina. A expressão da proteína glial fibrilar acídica (GFAP) aumentou na retina aos 2 meses de diabetes. Curiosamente, o tratamento com CaD, por si só, fez aumentar os níveis de GFAP na retina. No que diz respeito à expressão das citocinas pró-inflamatórias, foi prestada particular atenção à interleucina-1β (IL-1β) e ao factor de necrose tumoral-α (TNF-α). Os níveis de expressão destas citocinas pró-inflamatórias aumentaram nas retinas dos animais diabéticos e o tratamento com CaD preveniu esse aumento. Além disso, o stress oxidativo/ nitrosativo foi avaliado através da detecção de grupos carbonilo oxidados e de resíduos de nitrotirosina. Tal com esperado, a diabetes aumentou o stress oxidativo/nitrosativo na retina, o qual foi inibido pelo tratamento com CaD, sugerindo assim que o efeito protector do CaD se mostra inegavelmente relacionado com suas as propriedades antioxidantes. Em conclusão, estes resultados suportam resultados anteriores, mostrando que o CaD exerce efeitos protectores na retina, principalmente inibindo o stress oxidativo/nitrosativo e a inflamação. Particularmente, neste trabalho, foi demonstrada pela primeira vez a inibição da produção de citocinas pró-inflamatórias pelo CaD naretina. É também provável, que os efeitos protectores do CaD sejam essencialmente devido às suas propriedades antioxidantes.Diabetic retinopathy is one of the most common complications of diabetes mellitus and is a leading cause of acquired blindness in working-age adults in developed countries. Calcium dobesilate (CaD) is a synthetic benzene sulfonate derivative used in the treatment of diabetic retinopathy. Its clinical effectiveness has been demonstrated mainly through a correction of the excessive vascular permeability in the retina of diabetic patients and in experimental diabetes. However, its molecular and cellular mechanisms of action are not completely elucidated. The protective effects of CaD might be due to its antioxidant properties or possibly they could also be related with an anti-inflammatory activity. Therefore, the main goal of the present study was to clarify the effects of the treatment with CaD on the inflammation and oxidative/nitrosative stress induced by diabetes in the retina of an animal model. Wistar rats were divided into four groups: controls, animals treated with CaD, diabetic (2 month diabetes duration) and diabetic treated with CaD (100 mg/kg/day; orally given, during the last 2 weeks). Given the inflammatory nature of diabetic retinopathy, glial reactivity was evaluated in Müller cells and astrocytes. Glial fibrillary acidic protein (GFAP) immunoreactivity was upregulated in the retina at 2 months of diabetes. Interestingly, CaD per se also enhanced GFAP levels in the retina. Regarding the expression of pro-inflammatory cytokines, a particular attention was given to interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). The expression levels of these pro-inflammatory cytokines were elevated in the retinas of diabetic animals, and CaD was able to prevent this upregulation. Oxidative/nitrosative stress was analysed by the detection of oxidized carbonyl groups and tyrosine nitration. As expected, diabetes increased the oxidative/nitrosative stress in the retina, which was inhibited by treatment with CaD, thus suggesting that the protective effect of CaD appeared undeniably related with its antioxidant properties. In conclusion, these results further support previous findings showing that CaD can exert potent protective effects in the retina, namely inhibiting oxidative/nitrosative stress and inflammation. In particular, the inhibition of the production of pro-inflammatory cytokines in the retina by CaD was demonstrated by the first time in this work. It is also likely that the protective effects of CaD are mainly due to its antioxidant properties

The genetic basis of mutualism in Pseudomyrmex plant-ants

Dissertação de mestrado em Geociências, apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.O presente estudo aborda a área temática dos riscos naturais, numa perspectiva concelhia, nomeadamente com a avaliação da susceptibilidade natural e da vulnerabilidade, na qual será identificado os elementos estruturais e sociais com maior grau de exposição. Situado na placa Africana, mais concretamente na região intraplaca, o Arquipélago da Madeira, formado no Miocénico, é de origem vulcânica e assenta em pleno domínio oceânico. A área em estudo, o concelho de Câmara de Lobos, situa-se na zona centro-ocidental da ilha da Madeira, a Oeste do Funchal. É um dos mais importantes da região, com uma área de 52,6 km2 e uma densidade populacional de 668,9 hab/km2. Desde a colonização da ilha, no início do século XV, que estão relatados inúmeros acontecimentos catastróficos naturais e em particular na área geográfica em estudo, causando inúmeras vítimas e avultados prejuízos materiais. Neste âmbito e de modo a proceder uma avaliação da susceptibilidade natural concelhia, foi efectuado um levantamento histórico dos fenómenos que causaram danos materiais e humanos, utilizando inúmeras referências bibliográficas, e precedido de uma análise as características do meio físico envolvente. Posteriormente e em conjugação com o anteriormente descrito, foi efectivada uma análise à vulnerabilidade social e infra-estrutural, por freguesia, aos riscos naturais. Numa primeira fase, foram seleccionados grupos sociais que, devido a inúmeros factores, são os mais indicativos das características da população que poderá ser afectada. Das variáveis seleccionadas, foi produzida uma estimativa da vulnerabilidade social. Na avaliação da vulnerabilidade infra-estrutural, foi utilizada a mesma metodologia para o parque habitacional concelhio, com a selecção de critérios estruturais, de forma a estimar a vulnerabilidade da habitação e consequentemente, a imposição de um risco acrescido dos seus habitantes; auxiliará também na validação do edificado como um elemento vulnerável, quando exposto a uma adversidade. A sobreposição das variáveis supramencionadas, determinou uma delimitação geográfica das áreas mais susceptíveis, tendo sido complementada com um levantamento dos elementos mais expostos aos eventos destrutivos naturais. Conclusivamente, a avaliação de risco efectuada permitiu a introdução de uma nova estratégia de pré-actuação aos fenómenos de elevada perigosidade, capaz de atenuar perdas e danos socioeconómicos, a nível concelhio. Este exercício terá como objectivo primordial o auxílio e optimização das políticas de gestão do território, no âmbito dos planos municipais de emergência e de ordenamento do território.This present study approaches, the thematic field of natural hazards in a local perspective, namely with the evaluation of the natural susceptibility and vulnerability, in which will be identified the structural and social elements exposed to natural disasters. Of volcanic origin and situated in the intraplate region of the African plate, the Madeira Archipelago was formed during the Miocenic and seats in full oceanic domain. The study area, the Câmara de Lobos county, is located in the center-western point of Madeira island, west of Funchal. With an area of 52,6 km2 and 668,9 hab/km2, this municipality, is one of the most important of the region. Since the settlement of the island, in the early 15th century, several destructive events were reported in different areas of Câmara de Lobos, causing several victims and great material damages. In order to proceed this current assessment, the county natural susceptibility, a survey of all natural phenomena that caused great material damage and human casualties was made, using historical references, preceded by an physical analysis of the county in study. Subsequently and in conjunction with the previously described, it was made an analysis of the social and infraestrutural vulnerability, at a parish scale, to natural hazards. Initially, were selected social groups that, due to countless factors, are the most indicative of the characteristics of the population that could be affected. From the variables selected, it was produced an estimate of the social vulnerability. In assessing the infraestrutural vulnerability, the same methodology was used for housing, with the selection of structural criteria, in order to produce an estimation of the vulnerability of the county housing and consequently, the imposition of an added risk for their inhabitants; it will also assist in the validation of the built as an vulnerable element, when exposed to an natural catastrophe. The overlap of the variables mentioned above, determined a geographical delimitation of the most susceptible areas, having been complemented with a survey of the most exposed elements to a destructive natural event. In conclusion, the risk evaluation made it possible the introduction of a new pre-action strategy to the higher risk phenomena, capable to mitigate losses and socioeconomic damages, at a county level. This exercise has as primordial objective, the aid and optimization of the land administration policies, within the municipal emergency plans and land management

Untangling the complex interactions between turtle ants and their microbial partners

Background: To understand the patterns of biodiversity it is important to consider symbiotic interactions as they can shape animal evolution. In several ant genera symbiotic interactions with microbial communities have been shown to have profound impacts for the host. For example, we know that for Camponotini the gut community can upgrade the host\u27s diet and is shaped by development and colony interactions. However, what is true for one ant group may not be true for another. For the microbial communities that have been examined across ants we see variation in the diversity, host factors that structure these communities, and the function these microbes provide for the host. In the herbivorous turtle ants (Cephalotes) their stable symbiotic interactions with gut bacteria have persisted for 50 million years with the gut bacteria synthesizing essential amino acids that are used by the host. Although we know the function for some of these turtle ant-associated bacteria there are still many open questions.Results: In the present study we examined microbial community diversity (16S rRNA and 18S rRNA amplicons) of more than 75 species of turtle ants across different geographic locations and in the context of the host\u27s phylogenetic history. Our results show (1) that belonging to a certain species and biogeographic regions are relevant to structuring the microbial community of turtle ants; (2) both bacterial and eukaryotic communities demonstrated correlations and cooccurrence within the ant host; (3) within the core bacterial community, Burkholderiaceae bacterial lineage were the only group that showed strong patterns of codiversification with the host, which is remarkable since the core bacterial community is stable and persistent.Conclusions: We concluded that for the turtle ants there is a diverse and evolutionarily stable core bacterial community, which leads to interesting questions about what microbial or host factors influence when these partner histories become evolutionarily intertwined

Symbiont Interactions in a Tripartite Mutualism: Exploring the Presence and Impact of Antagonism between Two Fungus-Growing Ant Mutualists

Mutualistic associations are shaped by the interplay of cooperation and conflict among the partners involved, and it is becoming increasingly clear that within many mutualisms multiple partners simultaneously engage in beneficial interactions. Consequently, a more complete understanding of the dynamics within multipartite mutualism communities is essential for understanding the origin, specificity, and stability of mutualisms. Fungus-growing ants cultivate fungi for food and maintain antibiotic-producing Pseudonocardia actinobacteria on their cuticle that help defend the cultivar fungus from specialized parasites. Within both ant-fungus and ant-bacterium mutualisms, mixing of genetically distinct strains can lead to antagonistic interactions (i.e., competitive conflict), which may prevent the ants from rearing multiple strains of either of the mutualistic symbionts within individual colonies. The success of different ant-cultivar-bacterium combinations could ultimately be governed by antagonistic interactions between the two mutualists, either as inhibition of the cultivar by Pseudonocardia or vice versa. Here we explore cultivar-Pseudonocardia antagonism by evaluating in vitro interactions between strains of the two mutualists, and find frequent antagonistic interactions both from cultivars towards Pseudonocardia and vice versa. To test whether such in vitro antagonistic interactions affect ant colonies in vivo, we performed sub-colony experiments using species of Acromyrmex leaf-cutting ants. We created novel ant-fungus-bacterium pairings in which there was antagonism from one, both, or neither of the ants' microbial mutualists, and evaluated the effect of directional antagonism on cultivar biomass and Pseudonocardia abundance on the cuticle of workers within sub-colonies. Despite the presence of frequent in vitro growth suppression between cultivars and Pseudonocardia, antagonism from Pseudonocardia towards the cultivar did not reduce sub-colony fungus garden biomass, nor did cultivar antagonism towards Pseudonocardia reduce bacteria abundance on the cuticle of sub-colony workers. Our findings suggest that inter-mutualist antagonism does not limit what combinations of cultivar and Pseudonocardia strains Acromyrmex fungus-growing ants can maintain within nests

Assessing the Diversity of Endogenous Viruses Throughout Ant Genomes

Endogenous viral elements (EVEs) can play a significant role in the evolution of their hosts and have been identified in animals, plants, and fungi. Additionally, EVEs potentially provide an important snapshot of the evolutionary frequency of viral infection. The purpose of this study is to take a comparative host-centered approach to EVE discovery in ant genomes to better understand the relationship of EVEs to their ant hosts. Using a comprehensive bioinformatic pipeline, we screened all nineteen published ant genomes for EVEs. Once the EVEs were identified, we assessed their phylogenetic relationships to other closely related exogenous viruses. A diverse group of EVEs were discovered in all screened ant host genomes and in many cases are similar to previously identified exogenous viruses. EVEs similar to ssRNA viral proteins are the most common viral lineage throughout the ant hosts, which is potentially due to more chronic infection or more effective endogenization of certain ssRNA viruses in ants. In addition, both EVEs similar to viral glycoproteins and retrovirus-derived proteins are also abundant throughout ant genomes, suggesting their tendency to endogenize. Several of these newly discovered EVEs are found to be potentially functional within the genome. The discovery and analysis of EVEs is essential in beginning to understand viral–ant interactions over evolutionary time

Inferring Phylogenies from RAD Sequence Data

Reduced-representation genome sequencing represents a new source of data for systematics, and its potential utility in interspecific phylogeny reconstruction has not yet been explored. One approach that seems especially promising is the use of inexpensive short-read technologies (e.g., Illumina, SOLiD) to sequence restriction-site associated DNA (RAD) – the regions of the genome that flank the recognition sites of restriction enzymes. In this study, we simulated the collection of RAD sequences from sequenced genomes of different taxa (Drosophila, mammals, and yeasts) and developed a proof-of-concept workflow to test whether informative data could be extracted and used to accurately reconstruct “known” phylogenies of species within each group. The workflow consists of three basic steps: first, sequences are clustered by similarity to estimate orthology; second, clusters are filtered by taxonomic coverage; and third, they are aligned and concatenated for “total evidence” phylogenetic analysis. We evaluated the performance of clustering and filtering parameters by comparing the resulting topologies with well-supported reference trees and we were able to identify conditions under which the reference tree was inferred with high support. For Drosophila, whole genome alignments allowed us to directly evaluate which parameters most consistently recovered orthologous sequences. For the parameter ranges explored, we recovered the best results at the low ends of sequence similarity and taxonomic representation of loci; these generated the largest supermatrices with the highest proportion of missing data. Applications of the method to mammals and yeasts were less successful, which we suggest may be due partly to their much deeper evolutionary divergence times compared to Drosophila (crown ages of approximately 100 and 300 versus 60 Mya, respectively). RAD sequences thus appear to hold promise for reconstructing phylogenetic relationships in younger clades in which sufficient numbers of orthologous restriction sites are retained across species.</p