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Biology subjects

Ross, I. L.

Publications and source records attributed to Ross, I. L..

2 recordsLinked to original sources

New glucose-abstaining Chlorella algae doubles mammalian cell culture longevity, boosts performance and drops serum needs enabling scaled applications.

Mammalian cell culture technologies are crucial for recombinant protein production, organoid generation, medical applications, and the generation of in vitro cultivated meat. However, they are limited by high costs, vascular O2 provision, and the resultant inhibition of 3D tissue formation. Effective media usage along with oxygenation and waste management to extend culture health and longevity are key to improving all three. Microalgae, utilizing organic or inorganic CO2, produce O2 from light which complements oxygen-consuming and CO2-respiring mammalian cells and tissue culture. However, common microalgal cultivation conditions differ in temperature and salinity from mammalian cell cultivation environments, making co-cultivation short-lived and challenging. We screened several different microalgae species to identify locally isolated Chlorella BDH-1 as candidate that has high growth rates in mammalian culture conditions while, unlike other Chlorella species, does not compete for glucose as an energy source. In mammalian cell co-culture, BDH1 reduces cellular waste products, stabilizes pH, doubles culture longevity, increases growth performance up to 80%, and reduces expensive and ethically challenging foetal bovine serum requirements. Chlorella BDH-1 was also non-inflammatory and tolerant of clinical antibiotics. Collectively, mammalian cell/BDH1 co-cultivation improves tissue culture health and reduces costs, paving the path for applications in the biotechnology and medical sectors.

cell biology↗

Strategy for unlimited cycles of scarless oligonucleotide directed gene editing in Chlamydomonas reinhardtii

CRISPR/Cas9 gene editing in the model green alga Chlamydomonas reinhardtii relies on the use of selective marker genes to enrich for non-selectable target mutations. This becomes challenging when many sequential modifications are required in a single cell line, as useful markers are limited. Here we demonstrate a cyclical selection process which only requires a single marker gene to identify an almost infinite sequential series of CRISPR-based target gene modifications. The NIA1 (Nit1, NR; nitrate reductase) gene was this selectable marker. In the forward stage of the cycle, a stop codon was engineered into the NIA1 gene at the CRISPR target location. Cells retaining the wild type NIA1 gene were killed by chlorate, while NIA1 knockout mutants survived. In the reverse phase of the cycle, the stop codon engineered into the NIA1 gene during the forward phase was edited back to the wild type sequence. Using nitrate as the sole nitrogen source, here only the reverted wild type cells survived. By using CRISPR to specifically deactivate and reactivate the NIA1 gene, a marker system was established that flipped back and forth between chlorate- and auxotrophic (nitrate) based selection. This provided a scarless cyclical marker system that enabled an indefinite series of CRISPR edits in other, non-selectable genes. Here, we demonstrate that this Sequential CRISPR via Recycling Endogenous Auxotrophic Markers (SCREAM) technology enables an essentially limitless series of genetic modifications to be introduced to a single cell lineage of C. reinhardtii in a fast and efficient manner to complete complex genetic engineering.

plant biology↗