Micro-organismos são profícuos produtores de produtos naturais bioativos. Diversos fármacos inovativos e de extrema importância clínica são de origem microbiana, como antibióticos, antitumorais, imunossupressores e agentes hipolipêmicos. A maioria dos fármacos de origem microbiana é produzida por actinobactérias. A estreita associação de micro-organismos com plantas, insetos, crustáceos e organismos marinhos, pode induzir a produção de substâncias bioativas, que eventualmente conferem vantagens adaptativas e ecológicas ao macro-organismo hospedeiro. Ambientes marinhos e áreas de transição como os manguezais são ainda pouco explorados para estudos químicos e farmacológicos dos micro-organismos presentes nos solos e em simbiose com outros hospedeiros. Neste sentido, o presente trabalho visou o estudo químico monitorado por ensaios de citotoxicidade em células cancerígenas de dois micro-organismos, Streptomyces sp. Act1 e Streptomyces sp. Act2, isolados da casca do caranguejo do maguezal, Ucides cordatus, coletado em Cananéia, SP. Estes micro-organismos apresentaram atividade antagônica frente ao fungo patogênico Aspergillus niger, confirmando o potencial para produção de substâncias bioativas. Os micro-organismos foram cultivados em diferentes meios de cultura para avaliar o potencial de crescimento, perfil químico dos extratos obtidos e atividade citotóxica dos extratos e subfrações. Os meios de cultura escolhidos foram meio líquido ISP-2 e meio sólido (arroz), e ainda, nestas mesmas condições foi avaliado o efeito do uso de água do mar de forma comparativa. Os micro-organismos desenvolveram-se adequadamente nos diferentes meios de cultivo. Os fracionamentos dos extratos obtidos nos experimentos evidenciaram características polares das subfrações obtidas, e neste sentido foram necessárias adaptações das técnicas de separação, incluindo fases estácionárias como sephadex LH-20 e fase reversa. Os ensaios de citotoxicidade frente às linhagens de células tumorais com os extratos obtidos mostraram o grande potencial das linhagens em estudo, em especial a linhagem Streptomyces sp. Act-2 cultivada na presença de água do mar. / Abstract Microorganisms are prolific producers of bioactive natural products. Most of innovative pharmaceuticals that have useful clinical importance have been isolated from from microorganisms, such as antibiotics, anticancer drugs, immunosuppressive drugs and lipid-lowering agents. Most of the drugs of microbial origin are produced by actinomycetes. The close association of micro-organisms with plants, insects, crustaceans or marine organisms may induce the production of bioactive substances. These natural products may confer adaptive advantages to the environment and to the host organism. Marine and transitional areas such as mangroves are still under explored for chemical and pharmacological studies of both soil microorganisms and symbiotic microorganisms. In this sense, this work aimed a chemical study of two actinobacteria strains, Streptomyces sp. Act1 and Streptomyces sp. Act2, guided by cancer cells cytotoxicity assays. Both microorganisms were isolated from the shell of the mangrove crab Ucides cordatus, collected in Cananéia, SP. These microorganisms showed antagonistic activity against the pathogenic fungus Aspergillus niger, confirming the potential for production of bioactive substances. Microorganisms were cultured in different culture media to assess the potential for growth, chemical profile of extracts and cytotoxic activity of extracts and subfractions. The culture media were chosen using liquid (ISP-2) and solid medium (rice). The effect of addition of saline water in the culture media has also been evaluated. The microorganisms developed adequately in different culture media. The fractions of extracts obtained from the experiments showed characteristics of polar subfractions obtained, requiring the use of sephadex LH-20 and reverse phase as chromatographic stationary phases. Cytotoxic assays of the extracts against cancer cell lines showed the great potential of the strains under study, mainly Streptomyces sp. Act2. grown in the presence of seawater.

O cenário de grandes transformações do mundo atual fez com que autores consagrados como C. K. Prahalad, Gary Hamel e Peter F. Drucker reconhecessem que os modelos estratégicos vigentes estariam encontrando dificuldades para oferecer racionalidades adequadas para se lidar com o problema da mudança nas sociedades e nas organizações de produção contemporâneas. Para parcela significativa da produção científica recente na área, a problemática em tela se deve, em grande medida, à fragmentação teórica e à especialização decorrente do uso intensivo de abordagens prescritivas nas Ciências Administrativas. Este cenário conduz à necessidade de se repensar os correntes arcabouços conceituais. Neste sentido, o presente esforço de pesquisa tem por objetivo desenvolver uma sintetize dos aspectos internos e externos da dinâmica do problema estratégico, a partir de abordagens aderentes à teoria da Complexidade. Para tal, foi realizado um esforço de revisão conceitual embasado em análise do problema, segundo a metodologia fenomenológica de Husserl. Os resultados foram submetidos a um procedimento analógico realizado por meio de pesquisa bibliográfica nas literaturas que tratam da complexidade em outros sistemas teóricos próprios, especialmente os da Biologia. Como resultado, identificou-se que as organizações são produto de acoplamentos entre dois ou mais sistemas distintos que, por sua vez, se acoplam ao sócio-sistema humano e estes, por sua vez, ao restante da dinâmica planetária. Em última análise, esta configuração nutre forte analogia com as dinâmicas baseadas na simbiose, encontradas nos estudos mais recentes da biologia que, ao que o estudo indica, podem se transformar em uma inspiradora, importante e útil analogia para o aperfeiçoamento dos arcabouços teóricos em gestão estratégia. / Major Changes in today´s world has made renowned authors such as C. K. Prahalad, Gary Hamel and Peter F. Drucker recognized that the existing strategic models are not providing reasonable and adequate solutions to deal with the society changing problems and with the contemporary production organizations. For a significant portion of the recent scientific output in this area, the issue faced is due to, in most of it, the theoretical fragmentation and the specialization resulting from the intensive use of prescriptive approaches in Administrative Sciences. This scenario leads to the need of rethinking the current conceptual frameworks. This study, in particular, addresses the concepts related to the strategic problem of which we highlight the dynamics behind the problem, results of the aforementioned organizational changes which are characteristic of a contemporary society. For this, the present research effort aims to develop a summarized study of the internal and external aspects of dynamic strategic problems and, taking as a starting point the approaches inherent in the complexity theory. To achieve this, an effort was made to review the concept behind the problem analysis, according to Husserl´s phenomenological methodology. The results were submitted to an analog procedure, bibliographical research on the literatures that deals with complexity in other theoretical systems, especially in biology. As a result, it was found that organizations are products of couplings between two or more separate systems, which will couple to the socio-­human system, and these, to the rest of the planetary dynamics. As a last analysis, this configuration has strong analogy with the dynamics based on symbiosis, found in recent biology; this study suggests that it can become an inspiring, important and useful metaphor for the improvement of the theoretical frameworks in management strategy.

Orientador: Louis Bernard Klaczko / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-04T11:23:51Z (GMT). No. of bitstreams: 1 Montenegro_Horacio_D.pdf: 10351368 bytes, checksum: 5516ef31afbe4c57e6bf15156c33fdb7 (MD5) Previous issue date: 2005 / Resumo: Elementos genéticos egoístas são partículas herdáveis de etiologia e mecanismos de ação variados, mas com a caracterítica em comum de modificar a segregação mendeliana dos alelos em favor próprio, aumentando a própria freqüência. Elementos citoplásmaticos egoístas são um caso especial de elementos genéticos egoístas, como são herdados apenas pelo citoplasma materno, eles sofrem seleção para causar desvios na proporção sexual, em favor de um excesso de fêmeas. A proporção sexual nas progênies de organismos que se reproduzem sexualmente é, em geral, 1.___.__)LVKHU________SURS{V_D_SULPHLUD_H[SOLFDoão baseada em seleção natural para esta proporção. O princípio de Fisher prediz que o sexo mais raro tem maior valor adaptativo, pois sua contribuição média por indivíduo é maior. Assim, a seleção favorecerá alelos que aumentem a freqüência do sexo raro nas progênies. Quando a proporção chegar a 1.___.__indivíduos dos dois sexos terão o mesmo valor adaptativo. Parasitas reprodutivos, endosimbiontes herdados maternalmete, representam a maior parte dos elementos citoplasmáticos egoístas, e uma das causas mais comuns de desvios à proporção de 1.___.__ Agentes androcidas, endossimbiontes que matam os embriões machos, são um destes parasitas reprodutivos. Como conseqüência, a proporção sexual da prole das fêmeas infectadas afasta-se de 1.___.__apresentando excesso ou totalidade de fêmeas. Agentes androcidas foram encontrados em mais de 40 espécies de 6 ordens de insetos. Várions táxons de bactérias já foram associados com o fenótipo, e a filogenia dos parasitas e hospedeiros não é congruente, indicando transmissão horizontal freqüente. Neste trabalho, estudamos o agente androcida de Drosophila melanogaster, descrito recentemente. Sistemática molecular mostrou que trata-se de uma bactéria do gêneroSpiroplasma, muito próxima ao agente androcida encontrado em D. nebulosa. As seqüências comparadas (3000 pares de base, representando seqüências parciais de 3 genes) são idênticas, portanto, as duas bactérias têm um ancestral comum muito recente. De fato, possivelmente as duas espécies de Drosophila só entraram em contato há 4 ou 5 séculos, com a expansão mundial de D. melanogaster, e a transmissão do Spiroplasma de D. nebulosa para D. melanogaster deve ter ocorrido depois disso. Em uma coleta em Recife, foi encontrado que 2,3% das fêmeas estavam infectadas com Spiroplasma; outro parasita reprodutivo, a bactéria Wolbachia (que causa incompatibilidade citoplasmática) infectava 96% das fêmeas. Além disso, as duas bactérias co-infectavam os mesmos indivíduos, uma observação até agora incomum para parasitas reprodutivos com fenótipos diferentes. Como parasitas reprodutivos tem transmissão exclusivamente materna, seu valor adaptativo é altamente correlacionado com o das fêmeas hospedeiras. Desta forma, espera-se que parasitas reprodutivos não tenham efeitos deletérios no valor adaptativo das fêmeas hospedeiras, ou até que sejam benéficos. Por outro lado, a eficiência de transmissão ou a intensidade do fenótipo de manipulação reprodutiva podem estar positivamente correlacionados com a densidade de bactérias no hospedeiro, de forma que parasitas mais eficientes causem efeitos deletérios no valor adaptativo da fêmea. Para verificar se existem efeitos de Spiroplasma e Wolbachia no valor adaptativo de fêmeas, medimos a viabilidade larval e a fecundidade de fêmeas adultas, comparando com a de fêmeas não-infectadas. Nenhuma das duas características parece ser afetada por Spiroplasma ou Wolbachia, nem por infecção com as duas bactérias simultaneamente. Finalmente, foi verificado que temperaturas baixas (em torno de 16,5°C) interrompem a transmissão do agente androcida para a progênie das moscas infectadas / Abstract: Selfish genetic elements are inheritable particles with diverse ethiology and mechanisms, but sharing the fact that they modify the Mendelian segregation for their own benefit, thus increasing their own frequency. Selfish cytoplasmic elements are a special instance of selfish genetic elements, as they are inherited only by maternal cytoplasm, they suffer strong selection to alter the sexual proportion, in direction to an excess of females. The usual sexual proportion in sexually reproducing organisms is 1.___.__)LVKHU________ was the first to propose an explanation based on the natural selection for this proportion. Fisher¿s principle predicts that, if one of the sexes is rarer, it will have higher fitness, because its individual average contribution will be larger. Thereafter, selection will favour alleles that increase the frequencies of the rarer sex in broods. When the proportion reaches 1.___.__both sexes will have the same fitness. Reproductive parasites, maternally inherited endosymbionts, are the majority of selfish cytoplasmic elements, and one of the most common causes of departures from the 1.___._sexual proportion. Male killers, endosymbionts that kill male embryos, are one of these reproductive parasites. Consequently, the sexual proportion of infected females deviates from 1.___.__towards an excess or totality of females. Male killers have been found in more than 40 species of 6 insect orders. Several bacterial taxa have been associated with male-killing phenotype, and the phylogeny of parasites ad hosts is not congruent, indicating frequent horizontal transmission. In this work, we studied the recently described male killer agent found in Drosophila melanogaster. Molecular systematics showed that this agent is a Spiroplasma bacterium, closely related to the D. nebulosa male-killer. The compared sequences (3000 base pairs, partial sequence from 3 genes) are identical, thus both bacteria share a very recent common ancestral. Indeed, only since D. melanogaster worldwide expansion, 4 or 5 centuries ago, both Drosophila species overlap in their distribution, and the Spiroplasma transmission from D. nebulosa to D. melanogaster probably occurred after this. In one collection in Recife, Spiroplasma has been found infecting 2.3% of all females, another reproductive parasite, the bacterium Wolbachia (which causes cytoplasmic incompatibility) infected 96% of all females. Wolbachia was also found co-infecting flies alongside with Spiroplasma, a rather uncommon observation for reproductive parasites with different phenotypes. As reproductive parasites have exclusively maternal transmission, their fitness is highly correlated with its female host fitness. Consequently, it is expected that reproductive parasites do not pose deleterious fitness effects to their female hosts, or even be beneficial. However, transmission efficiency or the intensity of the reproductive manipulation phenotype could be positively correlated to the bacterial load on the host, in a way that more efficient parasites will have a deleterious fitness effect on females. In order to verify if Spiroplasma and Wolbachia have any kind of fitness effects on female hosts, we assessed larval viability and fecundity of adult females, in relation to uninfected females. Both characteristics showed signs of being affected by Spiroplasma or Wolbachia, nor by double-infection with both bacteria. Finally, low temperature (approximately 16.5°C) interrupts transmission of the male killing agent to the progeny of infected females / Doutorado / Genetica Animal e Evolução / Doutor em Genetica e Biologia Molecular

Lors de cette thèse, nous avons présenté trois principaux types d'analyses du métabolisme, dont la plupart impliquaient la symbiose : dialogue métabolique entre un trypanosomatide et son symbiote, analyses comparatives de réseaux métaboliques et exploration de données métabolomiques. Tous ont été essentiellement basés sur des données de génomique où les capacités métaboliques ont été prédites à partir des gènes annotés de l'organisme cible, et ont été affinées avec d'autres types de données en fonction de l'objectif et de la portée de chaque analyse. Le dialogue métabolique entre un trypanosomatide et son symbiote a été explorée avec des objectifs fonctionnels et évolutifs qui comprenaient une analyse des voies de synthèse des acides aminés essentiels et des vitamines telles que ces voies sont classiquement définies, une exploration de réseaux complets métaboliques et une recherche de potentiels transferts horizontaux de gènes des bactéries vers les trypanosomatides. Les analyses comparatives effectuées ont mis l'accent sur les capacités métaboliques communes de bactéries appartenant à différents groupes de vie, et nous avons proposé une méthode pour établir automatiquement les activités métaboliques communes ou spécifiques à chaque groupe. Nous avons appliqué notre méthode d'énumération d'histoires métaboliques à la réponse de la levure à une exposition au cadmium comme une validation de cette approche sur une réaction au stress bien étudiée. Nous avons montré que la méthode a bien capté la connaissance que nous avons de cette réponse en plus de permettre de nouvelles interprétations des données métabolomiques mappées sur le réseau métabolique complet de la levure / In this thesis, we presented three main types of analyses of metabolism, most of which involved symbiosis: metabolic dialogue between a trypanosomatid and its symbiont, comparative analyses of metabolic networks and exploration of metabolomics data. All of them were essentially based on genomics data where metabolic capabilities were predicted from the annotated genes of the target organism, and were further refined with other types of data depending on the aim and scope of each investigation. The metabolic dialogue between a trypanosomatid and its symbiont was explored with functional and evolutionary goals which included analysing the classically defined pathways for the synthesis of essential amino acids and vitamins, exploring the genome-scale metabolic networks and searching for potential horizontal gene transfers from bacteria to the trypanosomatids. The comparative analyses performed focused on the common metabolic capabilities of different lifestyle groups of bacteria and we proposed a method to automatically establish the common and the group-specific activities. The application of our method on metabolic stories enumeration to the yeast response to cadmium exposure was a validation of this approach on a well-studied biological response to stress. We showed that the method captured well the underlying knowledge as it extracted stories allowing for further interpretations of the metabolomics data mapped into the genome-scale metabolic model of yeast

Le genre Bradyrhizobium est le genre de rhizobia qui nodule la plus grande diversité d’espèces de légumineuses. Certaines de ces bactéries ont la particularité d’établir une symbiose fonctionnelle avec des légumineuses du genre Aeschynomene en utilisant un processus Nod-indépendant. De plus, au sein des nodules d’Aeschynomene, les Bradyrhizobium subissent une différenciation terminale en bactéroïde qui s’accompagne de modifications métaboliques et morphologiques drastiques. A la différence de la majorité des autres rhizobia, des hopanoïdes sont retrouvés au sein des membranes de l’ensemble des souches de Bradyrhizobium, dont certains, de façon inédite, liés à l’une des très longue chaîne d’acide gras (VLCFA) présentent sur le lipide A du LPS de ces bactéries. De plus, le LPS des Bradyrhizobium photosynthétiques possède un antigène-O également inédit et non-immunogénique. Le but de cette thèse était de déterminer si les particularités de la membrane externe des Bradyrhizobium pouvaient être impliquées dans la physiologie de ces bactéries ainsi que dans l’initiation et le maintien de la symbiose avec Aeschynomene. Les résultats obtenus ont mis en évidence que les hopanoïdes et plus particulièrement ceux liés au lipide A, ainsi que les VLCFAs permettent de rigidifier la membrane externe des Bradyrhizobium. Ces propriétés leur confèrent ainsi une plus grande résistance face aux conditions de stress, dont celles présentes au sein des nodules d’Aeschynomene, ce qui permet aux Bradyrhizobium de maintenir une symbiose efficiente avec ces plantes. Ces travaux ont ainsi permis d’avancer dans la connaissance de la voie de biosynthèse et du rôle du LPS atypique et des hopanoïdes des Bradyrhizobium et pourrait conduire à la production d’inocula plus résistants. / The Bradyrhizobium genus is the genus of rhizobia which nodulates the widest range of legume species. Some of these bacteria have the peculiarity of establishing a functional symbiosis with legumes of the genus Aeschynomene using a Nod-independent process. Moreover, within Aeschynomene nodules, the Bradyrhizobium strains undergo a terminal differentiation into bacteroids which is accompanied by drastic metabolic and morphological changes. Unlike the majority of other rhizobia, hopanoids are found in the membranes of all the Bradyrhizobium strains, some of which linked to one of the very long chain fatty acid (VLCFA) on the lipid A of these bacteria. In addition, LPS of photosynthetic Bradyrhizobium have an O-antigen that is also unique and non-immunogenic. The aim of this thesis was to determine whether the peculiarities of the external membrane of Bradyrhizobium strains could be implicated in the physiology of these bacteria as well as in the initiation and maintenance of the symbiosis with Aeschynomene. The obtained results showed that hopanoids and more particularly those linked to the lipid A, as well as the VLCFAs rigidify and stabilize the outer membrane of Bradyrhizobium strains. These properties give them greater resistance to stress conditions, including those present in Aeschynomene nodules, which allows the Bradyrhizobium to maintain an efficient symbiosis with these plants. This work allowed us to advance in the understanding of the biosynthesis and the role of the atypical LPS and the hopanoids produced by the Bradyrhizobium strains and could lead to the production of more resistant inocula.

Ce travail de thèse vise à mieux comprendre les mécanismes de choix du partenaire chez l'isopode terrestre Armadillidium vulgare. Cette espèce est infectée par la bactérie intracellulaire Wolbachia, connue pour manipuler la sexualité de ses hôtes. Chez Armadillidium vulgare, Wolbachia entraine une féminisation des mâles génétiques, les transformant en femelles fonctionnelles. L'objectif est donc à la fois de comprendre comment les individus choisissent leurs partenaires sexuels, mais également de connaître l'effet de Wolbachia sur ces mécanismes de choix. Afin de répondre à ces questions, une approche comportementale a été utilisée, afin de comparer l'attractivité et le comportement de différents types de femelles. Les résultats montrent que les mâles sont capables de discriminer finement entres des femelles ayant différents traits d'histoire de vie ou différents degrés d'apparentement. Nous montrons également que cette discrimination est corrélée à des changements d'odeur des femelles en fonction de leur état reproducteur et infectieux. Les conséquences de ces choix ont également été étudiées via des expériences de reproduction, et il apparaît que les préférences des mâles sont liées à des bénéfices en termes de succès reproducteur. Quant aux femelles, un suivi sur le long terme de différentes situations de sex-ratio révèle qu'à la fois les mâles et le fait qu'elles soient infectées par Wolbachia diminuent leur fitness, et notamment leur succès reproducteur, allant même jusqu'à modifier leurs préférences sociales. / This work investigates mate choice in the terrestrial isopod Armadillidium vulgare. This species is parasitized with intracellular bacteria Wolbachia, which is known to manipulate the sexuality of its hosts. In Armadillidium vulgare, Wolbachia lead to a feminization of genetic males, transforming them into functional females. The aim of this thesis was both to investigate how individuals choose their mates, and to understand the effect of Wolbachia on such choices. In order to answer these questions, we used a behavioural approach in order to compare the attractiveness and the behaviour of different kinds of females. The results indicate that males are able to accurately discriminate females with different life history traits or different degrees of relatedness. We also show that such discrimination from males toward females is correlated to females odour change, according to both their reproductive and infection status. The consequences of male mate choice were studied through reproduction experiment, and it seems that male’s preferences are linked to benefits in terms of reproductive success. Concerning females, a long-term monitoring in different sex-ratio conditions reveals that both males' presence and Wolbachia infections decrease their fitness, in particular their reproductive success, or even modify their social preferences.

Marine micro-organisms are important components of various biogeochemical cycles, complex food webs and ecological niches. Metagenomic sequencing can provide rapid profile of metabolic activities within the sponge and resident microbes. However, the study of metatranscriptomes from sponges using high throughput sequencing technology has only recently begun. Through this study we isolated, characterized and compared metatranscriptome profiles of Axinella corrugata host and sponge-specific microbial communities using 454 pyrosequencing technology. Four cDNA libraries (two eukaryotic and two prokaryotic) were generated from Axinella corrugata sponge samples collected in December 2009 and May 2010, and were characterized to a) reveal which metabolic genes were actively expressed and b) reveal possible interactions between the sponge and its microbial symbionts. The techniques used for isolation of mRNA and cDNA normalization also helped in optimization of whole-transcriptome amplification. More than 130,000 ESTs were generated for the two seasonal sponge samples and the metagenomic data sets were analyzed using bioinformatics tool, MG-RAST. Several stress-related transcripts were found which can increase our understanding of sensitivity of the sponge to changes in physical parameters in nature. The involvement of the sponge and its microbial consortia is depicted through actively expressed nitrogen and sulfur metabolism genes. Novel genes involved in several functional pathways may be discovered upon further studying hypothetical genes found across all four metagenomic data sets. Metatranscriptomic data sheds light on the functional role of microbes within the sponges and the extent of their involvement in sponge metabolism. 16S rRNA analysis was also carried out using genomic DNA of the same samples, to better elucidate the bacterial taxa abundance in the sponge. This study provides a profile of active mRNA trancripts in Axinella corrugata which include eukaryotic as well as prokaryotic sequences. The data analysis of this research provides new information at the cross-disciplinary interface between molecular biology and computational science.

Water flow is an important abiotic factor for corals and other cnidarians. This study shows how water flow influences bleaching in Palythoa caribaeorum. Colonies were exposed to flow (low = 3 cm s-1, high = 15 cm s-1) in two temperature regimes (low: 26.5°C, which is within natural variability on the reef where specimens were collected; high: 33.5°C, which is 3.5°C above usual summer temperature) in a unidirectional flume for 48 hours. Two sizes (small = 2.3 ± 0.2 cm, large = 7.3 ± 0.4 cm in diameter) were tested in six repeats per flow regime. Bleaching was determined by zooxanthellae count using a hemocytometer and by chlorophyll a concentration using fluorometry. Results suggest that onset of bleaching is rapid (within 48 hours) in high temperature. The low temperature did not cause significant bleaching. In the high temperature treatment, P. caribaeorum consistently bleached less in high flow. Upstream sides of large colonies bleached less than the downstream sides in high flow. In high flow, small colonies bleached less than large colonies. This suggests that enhanced diffusion of toxic oxygen species is important to mitigate bleaching and is more easily accomplished in small colonies, which may thus have an advantage during bleaching events, as has been observed in the literature.

A variety of secondary metabolites with promising antimicrobial and anti-tumor properties have been identified in marine organisms. Sponges, in particular, have been the source of several of these, including discodermolide from Discodermia dissoluta. While metagenomic studies have been undertaken to identify genes involved in discodermolide production, presently, a transcriptomic approach has not been taken to characterize the metagenome of D. dissoluta. Samples of D. dissoluta were collected from a site in the Bahamas and screened for secondary metabolite production. Some specimens of D. dissoluta were positive for discodermolide while others were not. In order to determine which genes are differentially expressed between the two specimens, suppression subtractive hybridization (SSH) was performed utilizing a chemistry negative and chemistry positive morphotype as the “driver” and “tester” populations respectively. Here we demonstrate the efficacy of SSH through the identification of transcripts related to symbiosis and secondary metabolite production by metatranscriptomic and bioinformatics analyses of the resulting subtracted library as well as a 16S rRNA library. Additionally, we have confirmed differential gene expression of selected sequences utilizing quantitative polymerase chain reaction (qPCR) with SYBR Green chemistry to screen and characterize genes, some of which appear to be related to novel metabolism and unknown functions related to symbiosis within the complex sponge-microbial community.

François Cheng est devenu une figure symbolique incontournable aussi bien pour la France que pour la Chine. C’est un écrivain dont la culture et la conscience sont doubles, car sa vie est étroitement liée à la Chine et à l’Occident. Sa grande intériorité énigmatique s’explique par son âme chinoise et son amour de l’Occident. Toute sa vie, il a poursuivi la réconciliation et le dialogue entre les deux cultures. Son écriture est aussi fortement marquée par une expérience personnelle de l’exil liée à un profond sentiment d’authenticité. D’un côté il nous fait redécouvrir une Chine traditionnelle et artistique, de l’autre il nous dépeint un vieux pays hanté par les destinées tragiques d’innocents, nous offrant ainsi l’image d’une Chine très riche et diversifiée. La constante comparaison entre les deux cultures nous révèle ses racines chinoises et son esprit français, marqué par un humanisme épris de liberté. C’est dans cette symbiose que se révèle la pensée de François Cheng, nourrie de multiples spiritualités et habitée par les concepts dualistes de la beauté et du mal. Cette recherche nous permet de mieux connaître cet écrivain : un quêteur de beauté, un homme en marche, un écrivain indéfinissable – le plus chinois des écrivains français ou bien le plus français des écrivains chinois –. / François Cheng is a major and symbolic figure in France and in China as well. He is a dual-culture writer who draws upon two streams of consciousness. His destiny is closely associated with China and the West. His enigmatic introspection can be explained by his Chinese soul and his love for the West. Throughout his life, he constantly pursued reconciliation in the dialogue between Eastern and Western cultures. His writing is strongly coloured by his unique experience of exile and a deep sense of authenticity. On the one hand, he enables us to rediscover a traditional and artistic China, while on the other hand, he describes an old country where innocent people suffered tragically. Thus the image of China that François Cheng draws, proves to be very rich and diverse. The continuous and coherent comparison between both cultures – French and Chinese ‒ reveals the French side of his reflection, his humanist trend and sense of freedom. It is within this symbiosis that we discover François Cheng’s thinking, nurtured by multi-spirituality and inhabited by the dualistic concepts of beauty and evil. This research intends to improve the knowledge we have of Francois Cheng : in search of beauty and dedicated to a constant reflection, he appears a double and indefinable writer : the most Chinese of French writers, and the most French of Chinese writers.