A RING-finger photocarotenogenic repressor involved in asexual sporulation in Mucor circinelloides.

Mucor circinelloides responds to blue light by activating the biosynthesis of carotenoids and bending its sporangiophores towards the light source. The CrgA protein product acts as a repressor of carotene biosynthesis, as its inactivation leads to the overaccumulation of carotenoids in both the dark and the light. We show here that asexual sporulation in Mucor is also stimulated by light and that the crgA gene is involved in sporulation, given that lack of crgA function affects both carotenogenesis and the normal production of spores. A small interference RNA (siRNA) gene silencing approach was used to block the biosynthesis of carotenoids and to demonstrate that abnormal sporulation in crgA mutants is not a consequence of a defective production of carotenes. These results reveal an active role for the predicted CrgA product, a RING-finger protein, in the control of cellular light-regulated processes in Mucor.     

Role of killer character in spontaneous fermentations from NW Spain: ecology,distribution and significance

Summary The presence of killer, resistant and sensitive populations of Saccharomyces cerevisiae along the successive stages of alcoholic fermentation in three vineyards from NW Spain was investigated. The global results showed that approximately 71% were killer-sensitive strains, 6.6% were killer-resistant, and 22.4% belonged to the k₂ killer type. However, there were important differences concerning the presence of the three phenotypes during successive stages of fermentation. Killer populations were isolated at the highest percentages in samples from must and from active alcoholic fermentations. Killer-resistant strains steadily increased during fermentation. Additionally, important differences in these populations were observed among the three vineyards. In this sense, the presence of killer populations was more important in samples from the vineyards with higher average pH values of the must. However, great differences in the distribution of killer phenotype between successive vintages (with the same initial pH of must) belonging to the same vineyard implies the presence of other factors effecting killer behaviour. Offprint requests to: T. G. Villa     

Genetic evidence of a new flocculation suppressor gene in Saccharomyces cerevisiae

Abstract The flocculation character in strain IM1-8b of Saccharomyces cerevisiae is controlled by a single and dominant gene shown to be allelic to FLO1 . Such a gene has been both mitotically and meiotically mapped on the right arm of chromosome I at 4.7 cM from PHO11 . The phenotype was suppressed by a single gene of wide distribution among non-flocculent strains (proposed as fsu3 ) that, however, was unable to suppress other FLO1 genes in other flocculent strains.