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Need nice pics and images for your presentation?

A collection of microalgae cultures at CSIRO Marine Research. Image released by CSIRO under Creative Commons Attribution license http://scienceimage.csiro.au/tag/algae/i/1938/microalgae-collection/

A collection of microalgae cultures at CSIRO Marine Research. Image released by CSIRO under Creative Commons Attribution license http://scienceimage.csiro.au/tag/algae/i/1938/microalgae-collection/

The Commonwealth Scientific and Industrial Research Organization (CSIRO) has just released its Scientific Image Library under a Creative Commons Licence.

Among the many available pictures and images a small section is also dedicated to the microalgal collection of the institute. Following this link you can browse and freely download useful high quality images for lectures, reports and blog posts.

Do not forget that various collection of high quality images released under Creative Common licence already exist and some of them contain images and pictures of microalgae. For instance The Wikimedia Commons Scientific Images Collection. Don’t forget that you can easily upload your pictures and images of Nannochloropsis to the wikimedia commons collection too, as I did some time ago: https://en.wikipedia.org/wiki/File:NannochloropsisMinusNitrogenNileRed.jpg

 

Proteomics and transcriptomics findings on lipids accumulation in Nannochloropsis

Confocal microscopy image of Nannochloropsis cell grown in nitrogen deprivation. Lipid droplets are in yellow and chloroplast is in red. From "Going ultradeep to unravel the secret recipe of biofuel" Elisa Corteggiani Carpienelli

Confocal microscopy image of Nannochloropsis cell grown in nitrogen deprivation. Lipid droplets are in yellow and chloroplast is in red. From “Going ultra deep to unravel the secret recipe of biofuel” by Elisa Corteggiani Carpinelli

What is the mechanism by which Nannochloropsis cells synthesise and accumulate lipids in certain culturing conditions? And moreover is there a key control that we can manipulate to improve lipid yields and overcome the tradeoff between lipid production and growth? This is probably the “holy grail” of Nannochloropsis research. The general feeling is that we do not have an answer yet, but at least we have some clues to start our quest.

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Proteomics and transcriptomics findings on Nitrogen stress respons in Nannochloropsis

Nannochloropsis cultivated in normal growth condition and deprived of a nitrogen source continues growing for at least 4–5 days.

Analyses of the gene expression and of the protein abundance in nitrogen scarcity, reveal that Nannochloropsis activates mechanisms for nitrogen assimilation and redistribution to allow survival through a partial reorganisation of the cellular metabolism.

Model of Nannochloropsis response to nitrogen deprivation

This figure reports the model of the response to nitrogen deprivation elaborated by Corteggiani Carpinelli et al. (2013).

DEGRADATIVE PROCESSES

Various genes involved in controlled degradation of proteins are over-expressed in the cells grown in nitrogen deprivation, including: cullin (Naga_100070g1), which is responsible for protein ubiquitination; ubiquitin-specific protease (Naga_100587g2); proteases (Naga_100611g3, Naga_100098g23, Naga_100015g80.1); endopeptidase Naga_101780g1); aminopeptidase (Naga_100024g51) and two autophagy-related proteins (Naga_101823g1 and Naga_100732g4), which are likely involved in the formation of cytosolic sequestering vesicles used for degradation and recycling of cellular components.

The proteomic study shows that the relative abundance of one subunit of the protein degrading complex (Proteasome subunit alpha) increases in nitrogen starvation supporting the evidence that processes of protein degradation are activated in response to nitrogen starvation. The analysis of protein abundance also suggests that in nitrogen starvation autophagy is induced. Indeed the abundance of a receptor-mediated endocytosis protein slightly increases and also that of two vacuolar proton pump subunits. These data, together with morfological observations, support the hypothesis that upon nitrogen deprivation the organelles are degraded in the vacuoles through a process of controlled autophagy.

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Nannochloropsis genomes, what have we learnt?

Nannochloropsis

Schematic representation of Nannochloropsis cell by Andrea Telatin

Thanks to the sequencing of the genomes of two strains of  Nannochloropsis gaditana [1][2] and two strains of Nannochloropsis oceanica [3][4] we now have the reference sequences to design molecular biology experiments on this microorganism. Moreover we have learnt a great deal of information, opened up new interrogatives .. and more will come analysing the data available though this portal and through the other web resources: N. gaditana CCMP526 genome and N. oceanica CCMP1779 genome.

Nannochloropsis genome is small, about 28-29 Mega bases, and very compact: there is on average 1 gene each 2.7 kilo bases in N. gaditana B-31, the genes are long on average 1.2 kilo bases and they contain very few introns.

The proteins predicted in the two species are in large part similar, about 80% of the proteins of each species are found in clusters of homologous proteins, ~60% of which accomodate proteins common to the two species. Further studies will help ruling out the limits and the  inaccuracies of the gene predictions allowing to focus on the actual differences between the two species.

The pathways leading to the synthesis of cellulose and sulfated fucans and to the remodelling of cellulose in the cell wall have been identified both in N. gaditana and in N. oceanica, casting a light on the molecular composition of the cell wall and suggesting possible targets of genetic modification.

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