Interações simbióticas entre Escherichia coli e seres humanos: a instabilidade de uma relação

Relações simbióticas são interações altamente instáveis. Uma série de fatores pode alterar drasticamente o perfil de uma relação, causando prejuízos ou benefícios ao hospedeiro. Essas mudanças estão intimamente ligadas ao custo/benefício por trás dessas interações. Tais fatos nos levam a questionar quais são as possíveis condições que favorecem o comportamento parasitário, comensal ou mutualista? E em que condições cada estratégia tornam-se mais vantajosas para o simbionte? A bactéria Escherichia coli é um exemplo de simbionte que pode apresentar as três estratégias em único hospedeiro, causando desde graves infecções a benefícios defensivos e nutricionais. Nesse contexto, discutiremos nesse trabalho as características da relação simbiótica entre essa bactéria e o ser humano, demonstrando sua complexidade, abordando os possíveis fatores que atuam como determinantes no perfil da relação e as vantagens e desvantagens de cada estratégia

Spider mite web mediates anti-predator behaviour

Herbivores suffer significant mortality from predation and are therefore subject to natural selection on traits promoting predator avoidance and resistance. They can employ an array of strategies to reduce predation, for example through changes in behaviour, morphology and life history. So far, the anti-predator response studied most intensively in spider mites has been the avoidance of patches with high predation risk. Less attention has been given to the dense web produced by spider mites, which is a complex structure of silken threads that is thought to hinder predators. Here, we investigate the effects of the web produced by the red spider mite, Tetranychus evansi Baker & Pritchard, on its interactions with the predatory mite, Phytoseiulus longipes Evans. We tested whether female spider mites recognize predator cues and whether these can induce the spider mites to produce denser web. We found that the prey did not produce denser web in response to such cues, but laid more eggs suspended in the web, away from the leaf surface. These suspended eggs suffered less from predation by P. longipes than eggs that were laid on the leaf surface under the web. Thus, by altering their oviposition behaviour in response to predator cues, females of T. evansi protect their offspring

Antipredator behaviours of a spider mite in response to cues of dangerous and harmless predators

Prey are known to invest in costly antipredator behaviour when perceiving cues of dangerous, but not of relatively harmless predators. Whereas most studies investigate one type of antipredator behaviour, we studied several types (changes in oviposition, in escape and avoidance behaviour) in the spider mite Tetranychus evansi in response to cues from two predatory mites. The predator Phytoseiulus longipes is considered a dangerous predator for T. evansi, whereas Phytoseiulus macropilis has a low predation rate on this prey, thus is a much less dangerous predator. Spider mite females oviposited less on leaf disc halves with predator cues than on clean disc halves, independent of the predator species. On entire leaf discs, they laid fewer eggs in the presence of cues of the dangerous predator than on clean discs, but not in the presence of cues of the harmless predator. Furthermore, the spider mites escaped more often from discs with cues of the dangerous predator than from discs without predator cues, but they did not escape more from discs with cues of the harmless predator. The spider mites did not avoid plants with conspecifics and predators. We conclude that the spider mites displayed several different antipredator responses to the same predator species, and that some of these antipredator responses were stronger with cues of dangerous predators than with cues of harmless predators

Catálogo Taxonômico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catálogo Taxonômico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Forrageamento e comportamento antipredação no sistema ácaro predador-presa em tomateiro

As plantas possuem mecanismos de defesa contra os ataques dos herbívoros. Estes mecanismos podem afetar diretamente os herbívoros, por exemplo, plantas podem produzir metabólitos secundários que reduzem ou param o desenvolvimento dos herbívoros, ou indiretamente por meio de interação com os inimigos naturais dos herbívoros. Plantas atacadas podem produzir compostos voláteis atrativos para inimigos naturais. Essas pistas voláteis são indicativas da presença das presas e são importantes para o sucesso do forrageamento de inimigos naturais. Por outro lado, herbívoros também são capazes de perceber pistas indicativas da presença de predadores e usá-las para evitar locais com risco de predação. Comportamentos antipredação aumentam a sobrevivência das presas, no entanto também podem gerar custos. No presente trabalho, foram estudados os comportamentos de forrageamento e antipredação no sistema do tomateiro com os ácaros fitófagos Tetranychus urticae e Tetranychus evansi, e os ácaros predadores Phytoseiulus longipes e Phytoseiulus macropilis. Ambos os predadores foram capazes de reconhecer pistas de tomateiros infestados mostrando preferência por plantas infestadas por T. evansi e T. urticae em relação a plantas limpas, mas não mostram preferência entre as presas. Estes predadores se alimentam de ambas as presas, no entanto P. macropilis não completa seu ciclo de vida se alimentando apenas de T. evansi. Assim, para P. longipes ambasas presas como fonte de alimento adequada, mas para P. macropilis T. evansi é um alimento de qualidade inferior. É possível que P. macropilis não seja capaz de distinguir pistas oriundas de tomateiros infestados por T. evansi ou T. urticae. Adicionalmente, T. evansi é capaz de perceber a presença de P. longipes e P. macropilis, e foi capaz de reconhecer pistas oriundas desses predadores e mudar seu comportamento de acordo com a espécie de predador e da escala espacial. Tetranychus evansi tentou escapar por mais vezes nos discos foliares com pistas de ambos predadores, tendo também redução no tempo de alimentação. No entanto, também há custos associados a estes comportamentos: T. evansi apresentou redução na taxa de oviposição nos discos foliares com pistas de P. longipes, mas não com pistas de P. macropilis, provavelmente por que este predador não é perigoso para T. evansi como P. longipes é. Em uma escala espacial maior (hexágono de plantas) onde os ácaros caminhariam sobre substrato tendo de percorrer longas distâncias e perceber pistas com intensidade provavelmente mais fraca, T. evansi não evitou plantas com predadores. Todos os tomateiros estavam infestados com coespecíficos que produzem grande quantidade de teia, possivelmente T. evansi não evitou plantas com predadores pela possível proteção conferida pela teia. Concluindo, os predadores P. longipes e P. macropilis são capazes de usar pistas de plantas atacadas para localizar suas presas T. evansi e T. urticae, mas não as distinguem. Tetranychus evansi é capaz de perceber a presença de ambos predadores e mostrar comportamento antipredação de acordo com o perigo oferecido pelo predador e a escala espacial envolvida.Conselho Nacional de Desenvolvimento Científico e TecnológicoPlants have mechanisms to defend themselves against herbivore attacks. These mechanisms may affect the herbivores directly, for example, plants can produce secondary metabolites that reduce or stop the growth of the herbivores, or indirectly by interacting with the natural enemies of the herbivores. Upon herbivore attack, plants are known to produce volatiles that are attractive to natural enemies. These volatile cues are indicative of the presence of prey, and are important for the foraging success of the natural enemies. In return, herbivores are able to recognize cues associated with the presence of predators and use these to avoid patches with predators. Such antipredator behaviour increases the survival of the prey; however, it may also have costs. Here, we studied the antipredator and foraging behaviour of the spider mites Tetranychus urticae and T. evansi, the predatory mites Phytoseiulus longipes and P. macropilis on tomato plants. Although the predators feed on both prey, P. macropilis can not complete its life cycle feeding only on T. evansi. Thus, for P. longipes both prey are adequate food sources, but T. evansi is a bad food source for P. macropilis. Both predators were able to recognize cues from infested or uninfested plants, showing preference for plants infested by T. evansi or T. urticae compared to uninfested plants, but they did not show a preference for plants with either of the two prey.It is possible that P. macropilis are not able to discriminate cues from tomato plants infested by these prey. Additionally, T. evansi can perceive the presence of P. longipes and P. macropilis. This herbivore was able to recognize cues from these predatory mites and to change its behaviour according to the species of predator and spatial scale. The spider mite tried to escape more often from leaf discs with predator cues, and also reduced its time spent feeding. However, there were also costs associated with this antipredator behaviour: T. evansi showed a decrease in oviposition rate on leaf discs with cues from P. longipes, but not with cues from P. macropilis, probably because this predator is not as dangerous to T. evansi as P. longipes is. At a larger spatial scale (hexagon of plants), where the spider mites walked on substrate soil and in all directions, T. evansi did not avoid plants with conspecific and predators; probably it perceived the presence of conspecific that produce high density of web which can protect it against predation. Concluding, the predatory mites P. longipes and P. macropilis can use cues from attacked plants to locate T. evansi and T. urticae, but do not discriminate between these two prey. In turn, T. evansi can perceive the presence of these predators, showing antipredator behaviour towards dangerous and harmless predators, according to the spatial scale

Defesa de planta, ácaros e teia afetando respostas de artrópodes ao tomateiro

Plants developed a wide range of defences in response to herbivore attack. These defences can affect herbivores directly, for example, through production of defensive compounds and proteins that reduce herbivore performance; or indirectly, by attracting the natural enemies of the herbivores. The spider mite Tetranychus urticae, for example, induces defences in tomato plants which decrease herbivorous mites performance and attract predatory mites. Moreover, some herbivores have adapted and are able to suppress plant defences, such as the spider mite Tetranychus evansi. Additionally, T. evansi cover the plant with a dense web, which among other functions, avoid competitors to profit from the suppressed defences. In this thesis, | studied the direct and indirect effects of changes in plant defence due infestation of the spider mites T. urticae and T. evansi, as well as their presence and their web, on other arthropods that occur in tomato plants. Studies that aim to investigate the effect of plant defences on herbivores, are commonly performed through evaluation of herbivores performance on treated plants, being done on whole plants or plant parts. Both methods have pros and cons, and the choice of which one to use depends on the system being studied: research question, organism and plant. Thus, in the first chapter, | investigated the effects of plants with defences induced and suppressed on the subsequent performance of an herbivore, on whole plants and on leaf discs. The method of evaluation and plant treatment affected the performance of T. evansi. However, there was no effect of the method on T. evansi response to plant defences: the oviposition rate of T. evansi was lower on plants infested with the inducer T. urticae than on plants infested with the suppressor T. evansi and uninfested plants on both methods, whole plants and leaf discs. In the second chapter, | investigated the attraction of arthropods to plants with defences suppressed by T. evansi and induced by T. urticae in an outdoor area, with infested plants covered or not with spider mite web. The plant defence interfered on the host choice of some herbivores, but not on the choice of natural enemies. The presence of web in combination with plant defences interfered on whiteflies host plant choice: plants with defences suppressed were more attractive to whiteflies in absence of web, but not when plants were covered by spider mite web. In the third chapter, | investigated the effect of indirect and direct plant defences and spider mite web on host plant choice and performance of the whitefly B. tabaci. Whiteflies preferred plants where they had higher survival of juvenile and recently emerged adults, that was uninfested and plants with defence suppressed without web. Finally, in the fourth chapter, we investigated whether thechanges in tomato plant defences through infestation with the defence-inducer T. urticae and the defence-suppressor T. evansi, as well as the presence of the spider mites and their web, affect the plant host preference and performance of Frankliniella occidentalis. The presence of the spider mites and the induction of plant defences did not affect the survival and performance of juveniles of F. occidentalis. Nevertheless, the presence of spider mite web on plants infested with T. evansi made these plants more attractive to F. occidentalis, but did not affect the performance and survive of juveniles. In conclusion, the results showed that both whole plants and leaf discs can be used for studies that aim to evaluate effects of tomato defences on the spider mites. Also, tomato plants with defences suppressed or induced by the spider mites can affect the host plant preference and performance of whiteflies but not of thrips. Likewise, the combination of web with plant defences also interfered on thrips and whiteflies host choice.As plantas desenvolveram uma ampla gama de defesas em resposta à herbívoria. Essas defesas podem afetar os herbívoros de forma direta, como por exemplo, produzindo compostos tóxicos e proteínas defensivas que reduzem o desempenho de herbívoros; ou indireta, atraindo os inimigos naturais. O ácaro Tetranychus urticae, por exemplo, induz as defesas do tomateiro o que reduz a performance de ácaros herbívoros e atrai ácaros predadores. Entretanto, alguns herbívoros se adaptaram e são capazes de suprimir as defesas das plantas, como por exemplo o ácaro Tetranychus evansi. Além disso, T. evansi cobre sua planta hospedeira com uma densa teia, que dentre outras funções, evita que os competidores se beneficiem da sua supressão de defesa. Nesta tese, estudou-se os efeitos diretos e indiretos das repostas do tomateiro ao ataque por T. urticae e T. evansi, bem como da presença dos ácaros e sua teia, em outros artrópodes que ocorrem no tomateiro. Estudos que visam investigar a resistência das plantas aos herbívoros são comumente realizados através da avaliação do desempenho de herbívoros nas plantas tratadas, o que pode ser realizado em plantas inteiras ou partes da planta. Ambos métodos possuem prós e contras, e sua escolha depende da pergunta a ser respondida e do sistema a ser estudado: organismo e planta. Desse modo, no primeiro capítulo, investigou-se os efeitos da defesa induzida ou suprimida do tomateiro no desempenho de um herbívoro, quando avaliado em arenas delimitadas em plantas inteiras e discos de folha. O tipo de arena e tratamento das plantas afetou o desempenho de T. evansi. No entanto, o tipo de arena não afetou a resposta de T. evansi aos tratamentos: T. evansi ovipositou menos nas plantas infestadas com o indutor T. urticae do que nas plantas infestadas com o supressor T. evansi e plantas não infestadas, tanto quando avaliado em plantas inteiras quanto em discos foliares. No segundo capítulo, foi investigado a atração de artrópodes por plantas com defesas suprimidas por T. evansi e induzidas por T. urticae em campo, com as plantas infestadas cobertas ou não pela teia dos ácaros. A manipulação da defesa das plantas interferiu na escolha de alguns herbívoros, mas não na escolha dos inimigos naturais. A presença da teia em combinação com a defesa das plantas interferiu na escolha de moscas brancas: plantas com defesas suprimidas foram mais atraentes para as moscas brancas na ausência de teia, mas não quando as plantas estavam cobertas de teia. No terceiro capítulo, investigou-se o efeito das respostas indiretas e diretas do tomateiro ao ataque de T. evansi e T. urticae, bem como a teia dos mesmos, na escolha da planta hospedeira e no desempenho da mosca branca B. tabaci. As moscas brancas preferiam plantas onde apresentavam maior sobrevivência de juvenis e adultos recém emergidos: plantas não infestadas e plantas com defesas suprimidas e sem teia. No quarto capítulo, estudou-se o efeito das respostas do tomateiro ao ataque de T. urticae e T. evansi, bem como a presença dos ácaros e sua teia, na preferência e desempenho de Frankliniella occidentalis. A presençade ácaros nas plantas e sua interferência na defesa não afetou a sobrevivência e desempenho de jovens de F. occidentalis. A presença de teia nas plantas infestadas com T. evansi tornou-as mais atrativas para F. occidentalis; no entanto, não afetou o desempenho e sobrevivência de juvenis. Em conclusão, os resultados demonstram que tanto as plantas inteiras como os discos foliares podem ser utilizados para estudos que visam avaliar os efeitos da resistência tomateiro sobre T. evansi. Adicionalmente, plantas de tomate com defesas suprimidas ou induzidas pelos ácaros podem afetar a preferência e o desempenho de moscas brancas, mas não de tripes. Da mesma forma, a combinação da presença de teia com manipulação da defesa do tomateiro também interferiu na escolha da planta hospedeira por moscas brancas e tripes.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Interações simbióticas entre Escherichia coli e seres humanos: a instabilidade de uma relação

Relações simbióticas podem ser interações altamente instáveis. Uma série de fatores pode alterar drasticamente o perfil de uma relação, causando prejuízos ou benefícios ao hospedeiro. Essas mudanças estão intimamente ligadas ao custo/benefício por trás dessas interações. Tais fatos nos levam a questionar quais são as possíveis condições que favorecem o comportamento parasitário, comensal ou mutualista? E em que condições cada estratégia tornam-se mais vantajosas para o simbionte? A bactéria Escherichia coli é um exemplo de simbionte que pode apresentar as três estratégias em único hospedeiro, causando desde graves infecções a benefícios defensivos e nutricionais. Nesse contexto, discutiremos nesse trabalho as características da relação simbiótica entre essa bactéria e o ser humano, demonstrando sua complexidade, abordando os possíveis fatores que atuam como determinantes no perfil da relação e as vantagens e desvantagens de cada estratégia.Symbiotic interactions can be highly unstable. A series of factors can dramatically alter the relationship, leading to costs or benefits to the host. These facts lead us to question: what are the possible conditions that promote parasitism, mutualism or commensalism? And under what conditions does each strategy become more advantageous for the symbiont? The bacterium Escherichia coli is an example of symbiont that may have the three strategies in a single host, it may cause serious infections or defensive and nutritional benefits. In this context, we discuss the characteristics of the symbiotic relationship between this bacterium and human hosts, demonstrating its complexity and addressing the possible factors that act as determinants in the profile of the relationship and the advantages/disadvantages of each strategy

The first cytogenetic report of fireflies (Coleoptera, Lampyridae) from Brazilian fauna

The first cytogenetic analysis of fireflies from Brazilian fauna was carried out in this work. The investigation of two species of the subfamily Lampyrinae, Aspisoma maculatum and Photinus sp. (aff. pyralis), showed the diploid number 2n = 19 and an X0 sex determination system in males. These observations are similar to those already described for all the Lampyrinae species previously studied. In contrast, Bicellonycha lividipennis (Photurinae) revealed the karyotype 2n = 16 + neoXY, which has not yet been registered for any firefly species. The neoXY sex determination system encountered in this species probably arose through fusion between an ancestral X sex chromosome, belonging to the X0 system, and an autosomal element. This event also reduced the diploid number from 2n = 19, which is more frequent in the family Lampyridae, to 2n = 18 in B. lividipennis. The analysis of meiotic cells showed that the neoXY sexual bivalent of B. lividipennis exhibited a prominent terminal chiasma, indicating that the sex chromosomes are not wholly differentiated and still retain a region of homology. A review of the cytogenetic data known for the family Lampyridae was also documented in this work, as well as a discussion on the main trends of chromosomal evolution that seem to have occurred in this group