African fermented foods: from art to science

Summary The fermentation of food has the following advantages: longer keeping quality, variety in flavour, making inedible foods edible. In addition, the fermented foods have enhanced nutritional values and decreased toxicity. Unfortunately, production of these foods in most African countries is largely unsophisticated and does not allow for increased production to meet increasing demand. To improve the production, there should be scientific investigations into the microbial culture involved in the fermentation, the processing equipment and the methods of optimizing the fermentation conditions.Research on the fermentation of African locust bean and soybean to producedawadawa (iru) is reviewed with a view to exposing the scientific background available for transforming the production from art to science.

---

Resumen La fermentación de alimentos tiene las siguientes ventajas: calidad de conservación superior, variedad de sabores y permite el consumo de productos previamente incomestibles. Además los alimentos fermentados tienen mayores propiedades nutritivas y menor toxicidad. Desafortunadamente la elaboración de este tipo de alimentos en la mayoría de paises africanos esta poco desarrollada y no permite el incremento de producción necesario para satisfacer el incremento de la demanda. Para mejorar la producción deberían de realizaese estudios sobre los procesos microbiológicos envueltos en la fermentación, sobre el equipamiento y sobre los métodos para optimizer las condiciones de fermentación.Se hace una revisión de los trabajos realizados sobre la fermentación de una variedad africana de soja para la producción dedawadawa (iru) exponiendo la información disponible a fin de transformar esta elaboración de arte en ciencia.

---

Résumé La fermentation des aliments possède les avantages suivants: une qualité de plus longue conservation, une variété de flaveurs, et la transformation d'aliments non comestibles en aliments comestibles. De plus, les aliments fermentés ont une valeur nutritonnelle accrue et une moindre toxicité. Malheureusement, la production de ces aliments fermentés reste largement fruste dans la plupart des pays africains et ne permet pas une production accure pour satisfaire une demande en augmentation. Pour améliorer la production, il importerait d'investiguer dans la science des cultures microbiennes impliquées dans la fermentation, dans l'équipement technologique et dans les méthodes d'optimisation des conditions de fermentation. On passe en revue la recherche sur la fermentation de la caroube africaine pour produire ledawadawa (iru) dans l'esprit d'exposer les connaissances de base disponibles pour transformer cette production d'un art à une science.

---

---

Based on a paper presented at IFS/UNU Workshop on Development of indigenous fermented foods and food technology in Africa, Douala, Cameroon, 14–18 October, 1985.     

Turning neurons into a nervous system

The RIKEN Center for Developmental Biology recently held its 2008 Symposium ;Turning Neurons into a Nervous System' in Kobe, Japan. The program, organized by Masatoshi Takeichi, Joshua Sanes, Hideki Enomoto and Raj Ladher, provided a rich sampling from current work in developmental neurobiology. Researchers from Japan, Europe and the USA gathered at this meeting to share insights into neural development and to admire the opening of the cherry blossom season.     

De novo shoot organogenesis: from art to science

In vitro shoot organogenesis and plant regeneration are crucial for both plant biotechnology and the fundamental study of plant biology. Although the importance of auxin and cytokinin has been known for more than six decades, the underlying molecular mechanisms of their function have only been revealed recently. Advances in identifying new Arabidopsis genes, implementing live-imaging tools and understanding cellular and molecular networks regulating de novo shoot organogenesis have helped to redefine the empirical models of shoot organogenesis and plant regeneration. Here, we review the functions and interactions of genes that control key steps in two distinct developmental processes: de novo shoot organogenesis and lateral root formation.     

Turning the tide of parachute science

Media player

Turning Maize Cobs into a Valuable Feedstock

With rising energy demand and limited resources, the need for alternative energy production is increasing. Maize cobs have an advantageous composition for the production of biofuels such as cellulosic ethanol but are currently left unused on the fields after harvest. Furthermore, cobs contain a low concentration of nitrogen (<1%). Therefore, cob harvest will not deplete soil fertility. Consequently, maize cobs are a cheap and promising source for sustainable energy production. Yet with primary focus on grain yield, no or little effort has been spent to increase cob biomass yield in addition to grain yield. Both cob and grain yield are complex inherited traits affected by the environment. Breeding of dual-purpose maize varieties with simultaneously increased cob and grain yield requires a deeper understanding of factors influencing both cob and grain development. In this article, the available knowledge on the genetics of cob formation and current and future applications of maize cob utilization are discussed to evaluate the prospects for development of dual-purpose maize varieties.     

Turning Saccharomyces cerevisiae into a Frataxin-Independent Organism

Frataxin (Yfh1 in yeast) is a conserved protein and deficiency leads to the neurodegenerative disease Friedreich’s ataxia. Frataxin is a critical protein for Fe-S cluster assembly in mitochondria, interacting with other components of the Fe-S cluster machinery, including cysteine desulfurase Nfs1, Isd11 and the Isu1 scaffold protein. Yeast Isu1 with the methionine to isoleucine substitution (M141I), in which the E. coli amino acid is inserted at this position, corrected most of the phenotypes that result from lack of Yfh1 in yeast. This suppressor Isu1 behaved as a genetic dominant. Furthermore frataxin-bypass activity required a completely functional Nfs1 and correlated with the presence of efficient scaffold function. A screen of random Isu1 mutations for frataxin-bypass activity identified only M141 substitutions, including Ile, Cys, Leu, or Val. In each case, mitochondrial Nfs1 persulfide formation was enhanced, and mitochondrial Fe-S cluster assembly was improved in the absence of frataxin. Direct targeting of the entire E. coli IscU to ∆yfh1 mitochondria also ameliorated the mutant phenotypes. In contrast, expression of IscU with the reverse substitution i.e. IscU with Ile to Met change led to worsening of the ∆yfh1 phenotypes, including severely compromised growth, increased sensitivity to oxygen, deficiency in Fe-S clusters and heme, and impaired iron homeostasis. A bioinformatic survey of eukaryotic Isu1/prokaryotic IscU database entries sorted on the amino acid utilized at the M141 position identified unique groupings, with virtually all of the eukaryotic scaffolds using Met, and the preponderance of prokaryotic scaffolds using other amino acids. The frataxin-bypassing amino acids Cys, Ile, Leu, or Val, were found predominantly in prokaryotes. This amino acid position 141 is unique in Isu1, and the frataxin-bypass effect likely mimics a conserved and ancient feature of the prokaryotic Fe-S cluster assembly machinery.     

Perspectives on science and art

Artists try to understand how we see, sometimes explicitly exploring rules of perspective or color, visual illusions, or iconography, and conversely, scientists who study vision sometimes address the perceptual questions and discoveries raised by the works of art, as we do here.     

Turning a disulfide isomerase into an oxidase: DsbC mutants that imitate DsbA

There are two distinct pathways for disulfide formation in prokaryotes. The DsbA-DsbB pathway introduces disulfide bonds de novo, while the DsbC-DsbD pathway functions to isomerize disulfides. One of the key questions in disulfide biology is how the isomerase pathway is kept separate from the oxidase pathway in vivo. Cross-talk between these two systems would be mutually destructive. To force communication between these two systems we have selected dsbC mutants that complement a dsbA null mutation. In these mutants, DsbC is present as a monomer as compared with dimeric wild-type DsbC. Based on these findings we rationally designed DsbC mutants in the dimerization domain. All of these mutants are able to rescue the dsbA null phenotype. Rescue depends on the presence of DsbB, the native re-oxidant of DsbA, both in vivo and in vitro. Our results suggest that dimerization acts to protect DsbC's active sites from DsbB-mediated oxidation. These results explain how oxidative and reductive pathways can co-exist in the periplasm of Escherichia coli.