Ontogenia larval comparativa de duas esp?cies (Characiformes e Siluriformes) end?micas do rio S?o Francisco

Objetivou-se com este trabalho comparar histologicamente o desenvolvimento ontogen?tico de duas esp?cies de peixes end?micos da bacia do rio S?o Francisco, Prochilodus argenteus (curimat?-pacu) e Lophiosilurus alexandri (pacam?). As coletas para as an?lises histol?gicas foram realizadas a cada 24 horas a partir do momento da eclos?o at? o 14? dia p?s-eclos?o (DPE) para a observa??o do desenvolvimento larval e at? o 39? DPE para a observa??o do desenvolvimento gonadal. As larvas foram fixadas inteiras em solu??o de Bouin e as l?minas histol?gicas foram coradas pelo m?todo de Hematoxilina-Eosina. Larvas de pacam? exibiram um tamanho corporal maior em rela??o ?s larvas de curimat?-pacu desde a eclos?o. Larvas de pacam? apresentaram a abertura da boca e in?cio da pigmenta??o dos olhos no momento da eclos?o, enquanto que nas larvas de curimat?-pacu, esses eventos foram observados no 1? DPE. No curimat?-pacu a visualiza??o e a insufla??o da bexiga natat?ria ocorreram no 1? e 3? DPE, respectivamente, sendo esses eventos mais tardios no pacam?, com visualiza??o no 2? e insufla??o no 8? DPE. Os gr?nulos de vitelo foram absorvidos no 4? DPE pelo curimat?-pacu e no 10? DPE pelo pacam?. No 7? DPE, o tubo digest?rio do pacam? apresentou-se mais diferenciado em rela??o ao curimat?-pacu. O sistema digest?rio de ambas as esp?cies ao 14? DPE demonstraram caracter?sticas relacionadas aos seus respectivos h?bitos alimentares, com est?mago amplo e intestino curto no pacam?, t?picos de h?bito carn?voro; est?mago com fun??o mec?nica e intestino longo no curimat?-pacu, t?picos de h?bito detrit?voro. O tecido epitelial de revestimento, formado por uma ?nica camada de c?lulas nas larvas rec?m-eclodidas (0 DPE), apresentou diferencia??o ao longo dos dias, exibindo presen?a de escamas no curimat?-pacu e numerosas c?lulas ?club? na regi?o epitelial intermedi?ria do pacam?, em avalia??es realizadas ao 39? DPE. Analisando os indiv?duos com 39 DPE, verificou-se a presen?a de g?nadas indiferenciadas com c?lulas som?ticas e c?lulas germinativas primordiais que foram observadas realizando migra??o no sentido caudo-cranial desde o 1? DPE em ambas as esp?cies. P?de-se concluir que as altera??es anat?micas observadas durante a ontogenia de larvas P. argenteus e L. alexandri est?o diretamente relacionadas ao h?bito alimentar e ao comportamento inerente ? cada esp?cie, sendo uma detrit?vora que nada ativamente na coluna d??gua, e outra carn?vora que habita regi?es de fundo, respectivamente. Aos 39 dias p?s-eclos?o, em ambas as esp?cies n?o foram observados ind?cios histol?gicos de diferencia??o sexual.Banco do Nordeste do Brasil (BNB)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Zootecnia, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016.The objective of this work was to compare histologically the ontogenetic development of two endemic species of fish from the S?o Francisco river basin, Prochilodus argenteus (curimat?-pacu) and Lophiosilurus alexandri (pacam?). The samples for the histological analyzes were performed every 24 hours since the moment of hatching until the 14th day post-hatching (DPH) for observation of the larval development and until the 39th DPH for the observation of gonadal development. The whole larvae were fixed in Bouin's solution and the histological slides were stained by the Hematoxylin-Eosin method. Pacam? larvae exhibited a larger body size relative than the curimat?-pacu larvae since hatching. Pacam? larvae presented the mouth opening and pigmentation of eyes beginning at the time of hatching, whereas in curimat?-pacu larvae, these events were observed in the 1st DPH. The visualization and the inflation of the swim bladder in the curimat?-pacu, occurred in the 1st and 3rd DPH, respectively, being these events in the pacam? later, with visualization in the 2nd and insufflation in the 8th DPH. The yolk granules were absorbed in the 4th DPH by the curimat?-pacu and in the 10th DPE by the pacam?. In the 7th DPH, the pacam??s digestive tube was more differentiated than curimat?-pacu. The digestive system of both species at the 14th DPH has features of it eating habits the pacam?, with a broad stomach and a short intestine in the pacam?, typical of a carnivorous habit; stomach with a mechanical function and a long intestine in curimat?-pacu, typical of detritivorous habit. The epithelial lining tissue, formed by a single layer of cells in the newly hatched larvae (0 DPH), showed a differentiation throughout the days, exhibiting scales in curimat?-pacu and numerous club cells in the middle epithelial region of the pacam?, at evaluations carried at the 39th DPH. Analyzing the individuals with 39 DPH, the presence of undifferentiated gonads with somatic cells and primordial germinative cells were observed, which has a caudate-cranial migration since 1st DPH in both species. It was concluded that the anatomical alterations of the ontogeny of P. argenteus and L. alexandri larvae are directly associated to the feeding habit and the inherent behavior of each species, being these detritivorous that nothing actively in the column of water and carnivorous that inhabits bottom regions, respcectively. At the 39 day post-hatching, both species hasn't evidenced of sexual differentiation

Gravitational energy of a magnetized Schwarzschild black hole - a teleparallel approach

We investigate the distribution of gravitational energy on the spacetime of a Schwarzschild black hole immersed in a cosmic magnetic field. This is done in the context of the {\it Teleparallel Equivalent of General Relativity}, which is an alternative geometrical formulation of General Relativity, where gravity is describe by a spacetime endowed with torsion, rather than curvature, with the fundamental field variables being tetrads. We calculate the energy enclosed by a two-surface of constant radius - in particular, the energy enclosed by the event horizon of the black hole. In this case we find that the magnetic field has the effect of increasing the gravitational energy as compared to the vacuum Schwarzschild case. We also compute the energy (i) in the weak magnetic field limit, (ii) in the limit of vanishing magnetic field, and (iii) in the absence of the black hole. In all cases our results are consistent with what should be expected on physical grounds.Comment: version to match the one to be published on General Relativity and Gravitatio

Fungal Adenylyl Cyclase Acts As a Signal Sensor and Integrator and Plays a Central Role in Interaction with Bacteria

10.1371/journal.ppat.1003612PLoS Pathogens910

The Rewiring of Ubiquitination Targets in a Pathogenic Yeast Promotes Metabolic Flexibility, Host Colonization and Virulence

Funding: This work was funded by the European Research Council [http://erc.europa.eu/], AJPB (STRIFE Advanced Grant; C-2009-AdG-249793). The work was also supported by: the Wellcome Trust [www.wellcome.ac.uk], AJPB (080088, 097377); the UK Biotechnology and Biological Research Council [www.bbsrc.ac.uk], AJPB (BB/F00513X/1, BB/K017365/1); the CNPq-Brazil [http://cnpq.br], GMA (Science without Borders fellowship 202976/2014-9); and the National Centre for the Replacement, Refinement and Reduction of Animals in Research [www.nc3rs.org.uk], DMM (NC/K000306/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Acknowledgments We thank Dr. Elizabeth Johnson (Mycology Reference Laboratory, Bristol) for providing strains, and the Aberdeen Proteomics facility for the biotyping of S. cerevisiae clinical isolates, and to Euroscarf for providing S. cerevisiae strains and plasmids. We are grateful to our Microscopy Facility in the Institute of Medical Sciences for their expert help with the electron microscopy, and to our friends in the Aberdeen Fungal Group for insightful discussions.Peer reviewedPublisher PD

DNA Damage Triggers Genetic Exchange in Helicobacter pylori

Many organisms respond to DNA damage by inducing expression of DNA repair genes. We find that the human stomach pathogen Helicobacter pylori instead induces transcription and translation of natural competence genes, thus increasing transformation frequency. Transcription of a lysozyme-like protein that promotes DNA donation from intact cells is also induced. Exogenous DNA modulates the DNA damage response, as both recA and the ability to take up DNA are required for full induction of the response. This feedback loop is active during stomach colonization, indicating a role in the pathogenesis of the bacterium. As patients can be infected with multiple genetically distinct clones of H. pylori, DNA damage induced genetic exchange may facilitate spread of antibiotic resistance and selection of fitter variants through re-assortment of preexisting alleles in this important human pathogen

Rates of Mutation and Host Transmission for an Escherichia coli Clone over 3 Years

Although over 50 complete Escherichia coli/Shigella genome sequences are available, it is only for closely related strains, for example the O55:H7 and O157:H7 clones of E. coli, that we can assign differences to individual evolutionary events along specific lineages. Here we sequence the genomes of 14 isolates of a uropathogenic E. coli clone that persisted for 3 years within a household, including a dog, causing a urinary tract infection (UTI) in the dog after 2 years. The 20 mutations observed fit a single tree that allows us to estimate the mutation rate to be about 1.1 per genome per year, with minimal evidence for adaptive change, including in relation to the UTI episode. The host data also imply at least 6 host transfer events over the 3 years, with 2 lineages present over much of that period. To our knowledge, these are the first direct measurements for a clone in a well-defined host community that includes rates of mutation and host transmission. There is a concentration of non-synonymous mutations associated with 2 transfers to the dog, suggesting some selection pressure from the change of host. However, there are no changes to which we can attribute the UTI event in the dog, which suggests that this occurrence after 2 years of the clone being in the household may have been due to chance, or some unknown change in the host or environment. The ability of a UTI strain to persist for 2 years and also to transfer readily within a household has implications for epidemiology, diagnosis, and clinical intervention