The Effect of Diel Temperature and Light Cycles on the Growth of Nannochloropsis oculata in a Photobioreactor Matrix

A matrix of photobioreactors integrated with metabolic sensors was used to examine the combined impact of light and temperature variations on the growth and physiology of the biofuel candidate microalgal species Nannochloropsis oculata. The experiments were performed with algal cultures maintained at a constant 20u C versus a 15°C to 25°C diel temperature cycle, where light intensity also followed a diel cycle with a maximum irradiance of 1920 μmol photons m-2 s-1. No differences in algal growth (Chlorophyll a) were found between the two environmental regimes; however, the metabolic processes responded differently throughout the day to the change in environmental conditions. The variable temperature treatment resulted in greater damage to photosystem II due to the combined effect of strong light and high temperature. Cellular functions responded differently to conditions before midday as opposed to the afternoon, leading to strong hysteresis in dissolved oxygen concentration, quantum yield of photosystem II and net photosynthesis. Overnight metabolism performed differently, probably as a result of the temperature impact on respiration. Our photobioreactor matrix has produced novel insights into the physiological response of Nannochloropsis oculata to simulated environmental conditions. This information can be used to predict the effectiveness of deploying Nannochloropsis oculata in similar field conditions for commercial biofuel production. © 2014 Tamburic et al

Doing synthetic biology with photosynthetic microorganisms

The use of photosynthetic microbes as synthetic biology hosts for the sustainable production of commodity chemicals and even fuels has received increasing attention over the last decade. The number of studies published, tools implemented, and resources made available for microalgae have increased beyond expectations during the last few years. However, the tools available for genetic engineering in these organisms still lag those available for the more commonly used heterotrophic host organisms. In this mini-review, we provide an overview of the photosynthetic microbes most commonly used in synthetic biology studies, namely cyanobacteria, chlorophytes, eustigmatophytes and diatoms. We provide basic information on the techniques and tools available for each model group of organisms, we outline the state-of-the-art, and we list the synthetic biology tools that have been successfully used. We specifically focus on the latest CRISPR developments, as we believe that precision editing and advanced genetic engineering tools will be pivotal to the advancement of the field. Finally, we discuss the relative strengths and weaknesses of each group of organisms and examine the challenges that need to be overcome to achieve their synthetic biology potential.Peer reviewe

Interrelationships between Cellular Density, Mosaic Patterning, and Dendritic Coverage of VGluT3 Amacrine Cells

Amacrine cells of the retina are conspicuously variable in their morphologies, their population demographics, and their ensuing functions. Vesicular glutamate transporter 3 (VGluT3) amacrine cells are a recently characterized type of amacrine cell exhibiting local dendritic autonomy. The present analysis has examined three features of this VGluT3 population, including their density, local distribution, and dendritic spread, to discern the extent to which these are interrelated, using male and female mice. We first demonstrate that Bax-mediated cell death transforms the mosaic of VGluT3 cells from a random distribution into a regular mosaic. We subsequently examine the relationship between cell density and mosaic regularity across recombinant inbred strains of mice, finding that, although both traits vary across the strains, they exhibit minimal covariation. Other genetic determinants must therefore contribute independently to final cell number and to mosaic order. Using a conditional KO approach, we further demonstrate that Bax acts via the bipolar cell population, rather than cell-intrinsically, to control VGluT3 cell number. Finally, we consider the relationship between the dendritic arbors of single VGluT3 cells and the distribution of their homotypic neighbors. Dendritic field area was found to be independent of Voronoi domain area, while dendritic coverage of single cells was not conserved, simply increasing with the size of the dendritic field. Bax-KO retinas exhibited a threefold increase in dendritic coverage. Each cell, however, contributed less dendrites at each depth within the plexus, intermingling their processes with those of neighboring cells to approximate a constant volumetric density, yielding a uniformity in process coverage across the population.SIGNIFICANCE STATEMENT Different types of retinal neuron spread their processes across the surface of the retina to achieve a degree of dendritic coverage that is characteristic of each type. Many of these types achieve a constant coverage by varying their dendritic field area inversely with the local density of like-type neighbors. Here we report a population of retinal amacrine cells that do not develop dendritic arbors in relation to the spatial positioning of such homotypic neighbors; rather, this cell type modulates the extent of its dendritic branching when faced with a variable number of overlapping dendritic fields to approximate a uniformity in dendritic density across the retina

Detection of viral particles in feces of young dogs and their relationship with clinical signs Detecção de partículas virais em fezes de cães jovens e sua relação com sinais clínicos

Gross and light microscopic studies of 100 stool specimens of young dogs were carried out. Viral particles were detected in 31% of the analized samples using negative contrast electron microscopic diagnostic technique. Parvo-like virus, corona-like virus and other non-identified particles were observed in 17%, 7% and 2% of the samples, respectively. Parvo-like and corona-like viruses were found together in 5% of the samples. More than half (58.82%) of the positive parvo-like virus specimens were from dogs aged between 6 weeks and 6 months. 42.85% of the corona-like virus positive samples were detected in dogs between 6 weeks and 6 months and a similar percentage was found in dogs older than six months of age. Dual infections with parvo-like and corona-like viruses were observed in 5% of the samples. Unidentified virus-like particles were found in two specimens. 80.63% of the samples containing viral particles were obtained from dogs with diarrhea.<br>Foram analisadas macroscópica e microscopicamente 100 amostras de fezes de cães jovens colhidas em ambulatório clínico. Através de microscopia eletrônica de contraste negativo, foram detectadas partículas virais em 31% das amostras de fezes examinadas. Do total de amostras onde foram detectadas partículas virais, 17% continham partículas parvo-like, 7% continhan partículas corona-like virus e 2% continham partículas com morfologia não característica. Em 5% das amostras foi detectada a presença simultânea de partículas parvo-like e corona-like. Do total de amostras de fezes contendo partículas parvo-like, 58,82% eram de cães com 6 semanas a 6 meses de idade, o que também foi observado em 42,85% das amostras de fezes contendo partículas corona-like foram cães entre 6 semanas e 6 meses e um número semelhante foi encontrado em cães de mais de 6 semanas de idade. Uma dupla infecção de parvo-like virus e corona-like virus, foi confirmada em 5% dos especimens. Partículas "virus-like" não identificadas foram encontradas em 2 indivíduos Das amostras com identificação de partículas virais, 80,64% pertenceram a cães com diarréia