Dissertations / Theses on the topic 'Bryopsida'

Entosthodon Schwägr. (Funariaceae) is a genus of soil-inhabiting, annual to biennial mosses occurring worldwide in temperate to tropical-montane climates. Although a number of regional revisions and treatments exist for the genus, in many parts of the world, it remains poorly known. This is perhaps especially true in Africa, where the identities of most species names are obscure. Furthermore, recent work on the Funariaceae suggests that the sporophytes, long used as the main basis for classification and identification in the group, exhibit high levels of homoplasy and that Entosthodon is paraphyletic as currently circumscribed. I further test the monophyly of Entosthodon, and its relationships to other members of the Funarioideae, through phylogenetic analysis of DNA sequences from four chloroplast regions. These analyses included 45 Entosthodon species (ca. 50 % of those currently recognised), as well as an additional 22 species comprising representatives of all genera of the subfamily (except the rare, monotypic genera Cygnicollum, Clavitheca, Nanomitrella and Brachymeniopsis and the recently described monotypic Afoninia). Bayesian analyses of these data strongly contradict the monophyly of Entosthodon, and it is instead resolved as paraphyletic to a large clade comprising mostly members of Physcomitrium and Physcomitrella. Within this grade, five well supported lineages are resolved - the first comprises 3 species of Entosthodon and is sister to the second lineage, the monotypic Physcomitrellopsis. The third is sister to the afore mentioned i clades and comprises 11 species of Entosthodon within which the monotypic genus Funariella is embedded. The fourth lineage comprises 7 species of Entosthodon and is sister to a clade within which a Physcomitrium-Physcomitrella group is sister to the fifth lineage - a large clade comprising 24 species of Entosthodon. Entosthodon hungaricus is shown to belong in the Physcomitrium clade instead, consistent with its rostrate operculum. Based on the phylogeny, a new classification of Entosthodon sensu lato is proposed. The genus is split into 4 genera (Amphoritheca, Fifeobryum gen nov., Funariella and Entosthodon sens. str.) and the monophyletic Physcomitrellopsis is also maintained. Because of a lack of diagnostic morphological taxonomic characters this new classification is based largely on the molecular circumscription of clades. Nonetheless, particular character combinations do largely characterise most of these genera, albeit that frequent reversals render particular character states non-diagnostic. A revision of these five genera for Africa results in the recognition of twentysix species in total: three in Amphoritheca, 12 in Entosthodon, one in Physcomitrellopsis, one in Fifeobryum, and nine in Funariella. Six of these species, 4 in Entosthodon and 2 in Funariella, are newly described based on specimens from East and southern Africa. A key to the sub-Saharan species is provided, and each is fully described, mapped and illustrated.

Les strigolactones (SL) sont une nouvelle classe de phytohormones, retrouvées chez toutes les plantes terrestres. Chez les plantes vasculaires, les SL ont un rôle hormonal prédominant dans la régulation de l’architecture aérienne, mais aussi une fonction de signal symbiotique, favorisant ainsi la captation d’eau et de nutriments du sol par les plantes. Ces deux fonctions ont conduit à l’hypothèse selon laquelle les SL ont pu être essentielles dans les processus de colonisation du milieu terrestre par les plantes il y a 450 millions d’années. L’étude de la biosynthèse et de la signalisation des SL chez la bryophyte Physcomitrium patens (P. patens, non-vasculaire), par comparaison avec ce qui est connu chez les plantes vasculaires, permet de questionner l’évolution des voies cellulaires associées aux SL chez les plantes terrestres. Chez les plantes vasculaires, les voies de biosynthèse et de perception des SL sont assez bien décrites. La voie de signalisation des SL commence par la perception de la molécule par le récepteur D14 dans le cytosol, qui la clive et reste associé à une partie de la SL. Ce complexe interagit dans le noyau avec deux partenaires : la protéine à boîte F MAX2, capable de recruter un complexe d’ubiquitination, et certaines protéines SMXL. Ces protéines agissent comme des répresseurs de la réponse aux SL et vont être ubiquitinées sous l’action du complexe recruté par MAX2, puis rapidement dégradées par le protéasome. Chez P. patens, la plupart des gènes de biosynthèse et de signalisation des SL sont retrouvés, parfois en nombres différents comparés aux plantes vasculaires. Seules des approches de génétique inverse permettent de définir précisément leur fonction. La précédente caractérisation du mutant de biosynthèse Ppccd8 chez P. patens a montré que les SL sont synthétisées via une voie similaire à celle des plantes vasculaires. En outre, la fonction des SL dans la régulation de l’architecture est conservée chez P. patens. Au contraire, en accord avec la découverte précédente que l’unique homologue de MAX2 chez P. patens n’est pas impliqué dans la signalisation des SL, les résultats ici présentés indiquent que la signalisation des SL n’est que partiellement conservée entre P. patens et les plantes vasculaires. En effet, seuls 2 homologues PpKAI2L de D14, sur les 13 possédés par P. patens, sont impliqués dans la perception des SL, d’après l’étude de mutants perte-de-fonction et les analyses de biochimie. Par ailleurs, les protéines PpKAI2L sont phylogénétiquement plus proches d’une autre protéine appelée KAI2 que de D14. Or KAI2 ne perçoit pas les SL chez les plantes vasculaires. De plus, la caractérisation des mutants perte-de-fonction Ppsmxl, obtenus par l’utilisation de la technologie CRISPR, et les analyses de liaison génétique avec PpMAX2 et PpCCD8 montrent que les quatre protéines PpSMXL ne jouent pas un rôle majeur dans la réponse aux SL. Cependant, les protéines PpSMXL les plus proches phylogénétiquement des SMXL ancestrales apparaissent comme des régulateurs importants de la croissance, ce qui pourrait constituer le rôle ancestral des protéines SMXL, en accord avec des études phylogénétiques récentes. Cette régulation de la croissance constituerait la réponse à un autre signal endogène, plus ancestral que les SL, le KL (ligand de KAI2). La transduction du signal KL serait conservée au moins chez les plantes terrestres et impliquerait chez P. patens certaines protéines PpKAI2L et les protéines PpMAX2 et PpSMXL. L’identité moléculaire du KL n’a pas encore été élucidée. N’étant pas conservée chez P. patens, la signalisation des SL résulte possiblement d’une innovation spécifique de la lignée des plantes vasculaires. Ainsi, la voie de réponse aux SL présente chez la mousse résulterait d’une évolution convergente vers la perception des SL. Il reste donc à élucider comment le signal SL est transduit chez P. patens, en aval de sa perception par certaines protéines PpKAI2L<br>Strigolactones (SL) make up a novel class of phytohormones that are found across the whole land plant lineage. In vascular plants, the main hormonal role of SL is the repression of shoot axillary branching. However, SL are also a major symbiotic signal, granting the plant increased access to the nutrients and water contained in the rhizosphere. These two functions of SL led to the hypothesis that these molecules have been instrumental at the time of land colonization by plants, approximately 450 million years ago. Studying SL biosynthesis and signaling in the bryophyte Physcomitrium patens (P. patens, a non-vascular plant), and comparing these processes with the available knowledge in vascular plants, enables to investigate the evolution of SL cellular pathways in land plants. As a matter of facts, SL biosynthesis and signaling pathways are quite extensively described in vascular plants. Notably, SL signaling starts in the cytosol where the SL molecule binds to the D14 receptor. D14 cleaves the SL and stays covalently linked to a part of the SL. Under this conformation, D14 can then interact with two partners in the nucleus: the MAX2 F-box protein and SMXL proteins. SMXL proteins act as repressors of the SL response, as their interaction with D14 and MAX2 will trigger their ubiquitination and subsequent proteasomal degradation. Most SL biosynthesis and signaling genes have homologs in P. patens genome, sometimes in different numbers. Nevertheless, only reverse genetics approaches can clearly establish these homologs function. Previous characterization of P. patens SL deficient mutant Ppccd8 revealed that SL biosynthesis is broadly conserved between mosses and vascular plants. Furthermore, SL play a similar role in the regulation of plant architecture in P. patens as demonstrated in vascular plants. On the other hand, results presented herein show that SL signaling is only partly conserved between P. patens and vascular plants, supporting the prior observation that the sole MAX2 homolog in P. patens is not needed for SL response. Indeed, only 2 out of the 13 P. patens D14 homologs (PpKAI2L genes) are involved in SL perception according to the characterization of Ppkai2l CRISPR knock-out mutants and to biochemistry analyses. Moreover, instead of D14, PpKAI2L proteins are closer to the KAI2 protein, which is not involved in SL perception in vascular plants. In addition, the phenotype of CRISPR knock-out mutants for the PpSMXL genes, together with genetic linkage analysis of PpSMXL with PpMAX2 and PpCCD8, show that none of the 4 PpSMXL proteins play a major role in SL response. However, the two PpSMXL homologs that are closer to the ancestral land plants SMXL seem to be important regulators of growth, which as per recent phylogenetic studies could be the ancestral role of the SMXL family. This effect on growth would actually be the main response to the ancestral KL (KAI2-ligand) signal, an endogenous signal different from SL. Transduction of the KL signal would hence be conserved across land plants and would be achieved in P. patens via some PpKAI2L proteins, together with the PpMAX2 and at least two PpSMXL proteins. To date, the identity of the KL molecule(s) remains under debate. As SL signaling is not conserved in P. patens, it appears that the known SL signaling pathway results from a vascular plants specific innovation. Likewise, SL response in P. patens would be the product of a convergent evolution. Therefore, the question as to how P. patens transduces the SL signal, downstream of perception by specific PpKAI2L proteins, remains open

As algas marinhas representam uma rica fonte de compostos bioativos, algumas delas precurssoras de ferramentas farmacológicas e de substâncias potencialmente úteis para o desenvolvimento de novos fármacos. A macroalga Bryopsis pennata , Cloroficea pertencente à ordem Caulerpales, sin. Bryopsidales é uma espécie tropical encontrada em diversos costões rochosos. É uma pequena alga de cor verde-musgo, plumosa, que geralmente forma agrupamentos homogêneos e vive fixada em superfícies sólidas como corais e rochas. Essa espécie produz uma defesa química tóxica para organismos herbívoros, além de promover alelopatia e se reproduzir facilmente a partir de pequenos fragmentos. Possui um potencial de se tornar invasiva e dominante em condições ambientais favoráveis como águas ricas em nutrientes. A ausência aparente de predadores conhecidos, indicaram a presença de possível defesa química nesta espécie. Por ser uma espécie que possui aparentemente pouco ou nenhum predador, uma vez que esta se encontra, na maioria das vezes, intacta no ambiente, o presente da continuidade a um trabalho anteriormente realizado que versa sobre a investigação de um efeito farmacológico cardiotônico, inotrópico positivo, da fração polar do extrato metanólico oriundo dessa alga marinha. Inicialmente foi feito um breve estudo farmacológico da atividade citotóxica e hemolítica do extrato polar. Posteriormente evidenciamos o efeito cardiotônico da fração polar de algas cultivadas e coletadas em tiras ventriculares de anuro, comparamos com a resposta cardiotônica quando submetido a ação do propranolol e finalmente evidenciamos algumas características bioquímicas das frações ativas. Nas atividades citotóxicas a fração polar da alga coletada provocou deformações na morfologia dos ovos de ouriço-do-mar e não apresentou atividade hemolítica em eritrócitos de camundongo. O efeito cardiotônico em tiras ventriculares de anuros ficou fortemente evidenciado nos testes com extratos polares de algas coletadas e cultivadas. Estudos comparativos realizados com extratos de algas coletadas e de algas cultivadas em laboratório, demonstraram efeitos farmacológicos similares entre os extratos, demonstrando não haver influencia dos contaminantes, tais como cianobacterias, nas respostas cardiotônicas. O propranolol antagonizou o efeito da fração polar dessa alga e enzimas endopeptidases não reagiram com o extrato metanólico de Bryopsis pennata. Testes bioquímicos demonstraram que a fração polar de peso molecular menor que 10.000 daltons de caráter iônico ácido foi a fração que manteve os efeitos inotrópicos cardíacos.<br>Marine algae are a rich source of bioactive compounds and some of them have shown to be useful for the development of new pharmacological tools and medicines. Bryopsis pennata , (Clorofícea, Caulerpales, sin. Bryopsidales) is a marine algae that can be found in the Southeastern Brazilian coast and some other oceans. It is a small green moss algae, feathery, generally forming homogeneous groups fixed upon solid surface such as corals. The species produces a toxic chemical defense to the herbivorous organism, besides promoting allelopathy and easily reproducing itself from tiny fragments. They possess a potential to become invasive and dominant in favorable environmental conditions like waters with rich nutrients. The absence of true epibionts and known predators indicated the presence of chemical defense mechanisms in this species. As it is a species that apparently has little or none predator, since usually it is found intact in its environment, the present is a complement of a previously study and it is about the investigation of the cardiotonic pharmacological effect, positive inotropic effect, of the methanolic extract from this marine algae. Initially it was done a brief pharmacological study of the cytotoxic and hemolytic activity of the polar extract. Then we showed the cardiotonic effect of the polar fraction from the cultivated and collected algae, the cardiotonic results of the explosive of a propranolol and finally some evidences from a biochemistry character of theses fractions. In the cytotoxic activities, the metanolic extract of the collected algae, promoted disfiguration in the egg\'s morphology and did not show hemolytic activity in the mouse erythrocytes. The cardiotonic effect in the anurou\'s ventricular strips was strongly unequivocal when it was tested with the polar extracts from the collected and cultivated algae. Comparative studies performed with the collected algae extracts and the ones cultivated in laboratory showed similar effects between them appearing not having cardiotonic influences by the contaminants. The propranolol antagonized polar tahe polar effects of these algae and the endopeptidase enzyme was not reacting with the methanolic extracts of Bryopsis pennata. Biochemical tests showed that the polar fraction of weight less than 10.000 Daltons and with acid character is the one that kept the inotropic cardiac activity

Several species of Bryopsidales (Chlorophyta) are known for displaying functional absence of the xanthophyll cycle, a common photoprotection mechanism responsible for qE component of NPQ. To cope with the extreme variability of their natural environment, these algae must be able to avoid photodamage. Previous works reported significant accumulation of all-trans-neoxanthin and violaxanthin under high light acclimation in different Bryopsidales, and speculated that these xanthophylls might control the amount of energy that reaches the photosystems, causing photoprotection. In this work, we investigated photoacclimation and photoprotection strategies in two species of Bryopsidales (Codium tomentosum and Bryopsis plumosa). We first characterised the acclimation state of algae exposed for 7 days to low light or high light (respectively 20 and 1000 μmol photons m2 s−1) in terms of pigment content (HPLC) and chlorophyll a variable fluorescence (PAM). We confirmed that high light triggers significant alteration of pigment content with accumulation of trans-Neoxanthin and Violaxanthin, and for the first time we characterised thoroughly how the pigment pool is altered during acclimation. We also confirmed that no evidence of any xanthophyll cycle is present in high light acclimated cultures. On a second note we tried to answer another major question: are trans-neoxanthin and violaxanthin photoprotective? Using a novel chlorophyll a variable fluorescence approach (pNPQ assessment) and performing quantification of PSII repair capacity (via lincomycin treatment) we were not able to give a clear answer to this question. Nonetheless, we concluded that despite trans-Neoxanthin and Violaxanthin might contribute to photoprotection, this process in Bryopsidales algae is likely given by the coordination between different mechanisms that deserve to be further investigated, including chloroplast movement, PSII repair/modulation, state transitions, and PSI cyclic electron transport.

Made available in DSpace on 2014-06-12T23:01:48Z (GMT). No. of bitstreams: 2 arquivo8174_1.pdf: 1364392 bytes, checksum: 5f208d4d80dbd6e4370de3cd78884137 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006<br>O fital é um habitat do ambiente marinho que serve de morada, abrigo e alimentação para a fauna e a flora relacionadas a ela. O Arquipélago de São Pedro e São Paulo (ASPSP) possui uma alta biodiversidade e, por ser um local geograficamente isolado, ainda há muito do que se conhecer e explorar. As macroalgas abrigam grande quantidade de animais, tendo suma importância na cadeia alimentar do local. O presente trabalho vem contribuir com a ampliação dos conhecimentos dos crustáceos, sendo o primeiro a inventariar os crustáceos associados às macroalgas do ASPSP. As plantas foram coletadas aleatoriamente no fundo da enseada e na parte do costão próximo à superfície da água onde sofrem ação das ondas na maré baixa. Foram utilizados sacos plásticos para remover as algas manualmente, depois foram acondicionadas em vasilhas plásticas e posteriormente fixadas. Em laboratório o processamento das amostras envolveu lavagens sucessivas das plantas e retenção da fauna em peneiras com tela de nylon com 500 m de abertura de malha, e a carcinofauna foi separada em grandes grupos e identificados em nível de espécie, quando possível. Foi encontrado um Alfeídeo do gênero Synalpheus, o Majídeo Mithraculus forceps (A. Milne Edwards, 1875), o Grapsídeo Plagusia depressa (Fabricius, 1775), o Xantídeo Nanocassiope melanodactyla (A. Milne-Edwards, 1867). Para os Anfípodos foram encontrados da família Amphithoidae exemplares do gênero Amphitoe e Cymadusa. Hyale sp. e Hyale macrodactyla Stebbing, 1899 da família Hyalidae e Elasmopus sp., Elasmopus brasiliensis (Dana, 1855), Elasmopus rapax Costa, 1853, E. pectenicrus (Bate, 1862), E. spinidactylus Chevreux, 1907 e Elasmopus brasiliensis (Dana, 1855) representantes da família Melitidae. Os Isopoda Asselota Joeropsis sp. também apareceram nas amostras. Os Tanaidacea estiveram representados com exemplares de Psamokalliapseudes granulosus, Leptochelia dúbia, Calozodion sp. e Pseudosphyrapus sp. O Arquipélago de São Pedro e São Paulo possui um registro de 32 espécies de Crustáceos; com o presente trabalho essa lista de espécies aumenta para 40, registrando mais oito novas ocorrências e dez novos gêneros que não foram possíveis de identificar em nível específico. Os Amphipoda, Isopoda e Tanaidacea citados são registrados pela primeira vez para o Arquipélago

La teneur mediane en selenium du microplancton de la mer ligure (mediterranee nord-occidentale) est de 0,62 microgrammes par gramme de poids sec (0,57 pour le microzooplancton et de 0,20 a 0,90 pour le microphytoplancton). Les fluctuations sont importantes lors du brassage vertical hivernal des masses d'eau ou faibles du fait de la composition specifique de la peche. La teneur en selenium du microplancton est une fonction lineaire inverse de la biomasse microzooplanctonique, mais lors d'une floraison phytoplanctonique elle augmente avec la biomasse de diatomees. Seul le selenite (se iv) stimule la croissance et le metabolisme des deux algues et protege de la peroxydation les lipides membranaires de la microalgue cricosphaera elongata. Les effets toxiques apparaissent au-dela de la concentration en selenium mesuree en milieu pollue: ralentissement de la multiplication cellulaire de c. Elongata et degradation de la chlorophylle a avec synthese d'un pigment orange pour la macroalgue bryopsis maxima. Le selenium penetre a travers les membranes, de facon controlee chez c. Elongata ou simple chez b. Maxima. La teneur intracellulaire en selenium reste stationnaire grace au pompage vers l'exterieur; pour la premiere algue: le niveau est bas pour le seleniate et plus eleve pour le selenite dont 41% est libre dans le cytosol et 58% est associe aux proteines; pour la seconde algue: le niveau intracellulaire n'est pas modifie par 8 jours de decontamination