In defence of the Cell Quota model of micro-algal growth

When proper statistical procedures were employed, the empiricalCell Quota model of Droop (J. Mar. Biol. Assoc. UK, 48, 689–733,1968; J. Phycol., 9, 264–272, 1973) proved a better fitto 20 out of 21 data sets (of conserved nutrients) than didthe power law-based Chemical Reaction model of Baird (J. PlanktonRes., 21, 85–126, 1999).     

SOME THOUGHTS ON NUTRIENT LIMITATION IN ALGAE1

An empirical relation relating specific growth, rate in steady state systems to nutrient status with respect to more than one nutrient simultaneously is proposed, based on 3 experimentally verifiable postulates: (1) that uptake depends on the external substrate concentration; (2) that growth depends on the interval substrate concentration; and (3) in a steady state system specific rate of uptake (in the absence of significant, excretion) is necessarily the product of the specific growth rate and internal substrate concentration. The implications of this model are discussed in particular in respect to the concept of luxury consumption and Liebig's law of minimum. Some aspects of uptake in transient situations are also discussed.     

A taxonomic database and linked iconograph for diatoms

Hydrobiologia - The Royal Botanic Garden Edinburgh and the Natural History Museum are collaborating to establish a database and linked iconograph, wherever possible using TDWG (Taxonomic Databases...     

Analysis of CRISPR‐Cas9 screens identifies genetic dependencies in melanoma

Targeting the MAPK signaling pathway has transformed the treatment of metastatic melanoma. CRISPR‐Cas9 genetic screens provide a genome‐wide approach to uncover novel genetic dependencies that might serve as therapeutic targets. Here, we analyzed recently reported CRISPR‐Cas9 screens comparing data from 28 melanoma cell lines and 313 cell lines of other tumor types in order to identify fitness genes related to melanoma. We found an average of 1,494 fitness genes in each melanoma cell line. We identified 33 genes, inactivation of which specifically reduced the fitness of melanoma. This set of tumor type‐specific genes includes established melanoma fitness genes as well as many genes that have not previously been associated with melanoma growth. Several genes encode proteins that can be targeted using available inhibitors. We verified that genetic inactivation of DUSP4 and PPP2R2A reduces the proliferation of melanoma cells. DUSP4 encodes an inhibitor of ERK, suggesting that further activation of MAPK signaling activity through its loss is selectively deleterious to melanoma cells. Collectively, these data present a resource of genetic dependencies in melanoma that may be explored as potential therapeutic targets.     

Digital microscopy in phycological research, with special reference to microalgae

Digital imaging technology is gradually being incorporated into all areas of biological research, but there is a distinct lack of information resources targeted at scientists in their specialist areas. There is a wealth of potential applications for digital images in phycology, including morphometric or visual analysis of specimens, taxonomic databases and publication of digital micrographs in lieu of photomicrographs. Here, we provide a review of digital imaging in general and its potential for the field of microalgal research in particular. We also present a number of imaging techniques that are critical for image acquisition and optimization, which can enable beginners to build their own libraries of high quality digital images. Resolution requirements of digital cameras are explained and related to microscope resolution. The benefits of digital imaging technology are discussed and contrasted with those of traditional silver halide technology.     

Conditions governing haematochrome formation and loss in the alga haematococcus pluvialis flotow

Summary Culture experiments withHaematococcus pluvialis show that carotenogenesis may be independent of available nitrogen but not of the carbon supply, and that cell multiplication not only precludes the accumulation of carotenoids even under conditions which are otherwise favourable to it, but also effects their disappearance.Chodat's hypothesis concerning the importance of the carbon/nitrogen balance has only limited application and is replaced by one of a more general nature.