![]() Humans have long been enchanted by seashells and regarded them variously as symbols of purity, fertility, and prestige. Nine out of ten shells coil to the right, and the rare left coilers have trouble mating because the rest of their anatomy also skews to the wrong side. Scales cites numerous studies that explain the myriad shapes and patterns of seashells, beginning with the observations of the 19th-century mathematician Reverend Henry Mosley, who noted that shells form logarithmic spirals. Shells are mainly calcium carbonate laid over a scaffold of protein they grow in spurts throughout the mollusks’ lives. But the majority of mollusks-from coiled nautiluses to hinged bivalves, from microscopic sea butterflies to mini-fridge-sized giant clams-are armored. Not all mollusks make shells: octopi, squid, and slugs are contentedly shell free. Scales takes the reader on a dizzying tour of mollusks past and present, beginning with a deep dive into their biology. Since their appearance 540 million years ago, mollusks have expanded from their marine origins into fresh water and onto land, and they’ve found their way into human culture the world over. “No matter where you are in the world, you will never be far from a mollusk,” writes Helen Scales in Spirals in Time, her eclectic homage to the phylum of creatures that makes seashells. These coastal souvenirs are so commonplace we may forget how little we know about the animals that once inhabited them. Octo| 500 words, about 2 minutes Share this articleĪnyone who has dipped a toe in the ocean has surely picked up a seashell from the beach. 148: 138–142.Cover image courtesy of Bloomsbury Publishing Book Review: Spirals in Time Helen Scales explores the secret life and curious afterlife of seashells. Hong (2019) Improving L-serine production in Escherichia coli via synthetic protein scaffold of SerB, SerC, and EamA. Hong (2013) Efficient gamma-aminobutyric acid bioconversion by employing synthetic complex between glutamate decarboxylase and glutamate/GABA antiporter in engineered Escherichia coli. Hong (2018) Efficient malic acid production in Escherichia coli using a synthetic scaffold protein complex. Davies (1988) Three-dimensional structure of the tryptophan synthase alpha 2 beta 2 multienzyme complex from Salmonella typhimurium. DeLisa (2008) Engineering the spatial organization of metabolic enzymes: mimicking nature’s synergy. Maranas (2001) Probing the performance limits of the Escherichia coli metabolic network subject to gene additions or deletions. Liu (2013) A serine hydroxy-methyltransferase from marine bacterium Shewanella algae: isolation, purification, characterization and l-serine production. Keasling (2009) Synthetic protein scaffolds provide modular control over metabolic flux. Nielsen (2016) Engineering of high yield production of L-serine in Escherichia coli. Tsuchiya (1990) Target of serine inhibition in Escherichia coli. ![]() Qi (2014) Construction of an L-serine producing Escherichia coli via metabolic engineering. Xu (2015) L-Serine overproduction with minimization of by-product synthesis by engineered Corynebacterium glutamicum. Eggeling (2005) Metabolic engineering of Corynebacterium glutamicum for L-serine production. ![]() Lu (2012) Construction of Escherichia coli strains producing L-serine from glucose. Nakae (2010) A 90-day feeding toxicity study of l-serine in male and female fischer 344 rats. Hirabayashi (2000) L-serine and glycine serve as major astroglia-derived trophic factors for cerebellar Purkinje neurons. These results suggest that the carbon flux was successfully directed to the L-serine secretion pathway without knocking out a competing pathway or adding expensive glycine.įuruya, S., T. By fermentation, 9.4 g/L of serine was produced at a yield of 0.34 mol/mol glucose. By the introduction of a synthetic protein scaffold without metabolic pathway engineering or addition of glycine, 1.8 g/L of L-serine was produced at pH7 and 37☌. Through this strategy, the L-serine production is more efficient than in competing pathways. A synthetic protein scaffold between SerB and EamA was introduced in this study to physically combine the two enzymes. A novel strategy is needed to overcome the L-serine degradation pathway and low L-serine tolerance of Escherichia coli for efficient L-serine production. L-serine microbial development is considered a difficult activity due to L-serine’s central role in cellular metabolism with 2 main degradation pathways. L-serine is a non-essential amino acid which has a wide range of applications and plays an important role as a building block for growing cells. ![]()
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