Bia blanc Bia blanc Bia blanc is a white French wine grape variety that is no longer commercially cultivated for wine production with only a few plantings existing worldwide in viticultural archives and experimental vineyards. The exact origins of Bia blanc are not yet known though ampelographers have noted that the grapevine shares some morphological similarities to the red Isère grape Peloursin, one of the parent varieties to Petite Sirah (Durif). In the 20th century, ampelographers Louis Levadoux and (decades later) Linda Bisson categorized Bia blanc as a member of the Pelorsien eco-geogroup along with Durif, Béclan, Dureza, Exbrayat, Jacquère, Joubertin, Mondeuse
Petite mutation Petite mutation petite (ρ–) is a mutant first discovered in the yeast "Saccharomyces cerevisiae". Due to the defect in the respiratory chain, 'petite' yeast are unable to grow on media containing only non-fermentable carbon sources (such as glycerol or ethanol) and form small colonies when grown in the presence of fermentable carbon sources (such as glucose). The petite phenotype can be caused by the absence of, or mutations in, mitochondrial DNA (termed "cytoplasmic Petites"), or by mutations in nuclear-encoded genes involved in oxidative phosphorylation. A neutral petite produces all wild type progeny when crossed with wild type. petite mutations can