Search results for "Systematics"

A new chromosomal rearrangement improves the adaptation of wine yeasts to sulfite

2019

Sulfite‐generating compounds are widely used during winemaking as preservatives because of its antimicrobial and antioxidant properties. Thus, wine yeast strains have developed different genetic strategies to increase its sulfite resistance. The most efficient sulfite detoxification mechanism in Saccharomyces cerevisiae uses a plasma membrane protein called Ssu1 to efflux sulfite. In wine yeast strains, two chromosomal translocations (VIIItXVI and XVtXVI) involving the SSU1 promoter region have been shown to upregulate SSU1 expression and, as a result, increase sulfite tolerance. In this study, we have identified a novel chromosomal rearrangement that triggers wine yeast sulfite adaptation.…

Performance of industrial strains of Saccharomyces cerevisae during wine fermentation is affected by manipulation strategies based on sporulation.

2002

Genetic manipulation of industrial wine yeast strains has become an essential tool for both the study of the molecular mechanisms underlaying their physiology and the improvement of their fermentative properties. The construction of null mutants for any gene in these usually diploid strains, by using a procedure based on sporulation of a heterozygote lacking one copy of the gene of interest, has been tested as an alternative to the tedious work of sequential disruption of the complete set of copies. Our results indicate that most of the homozygotes resulting from sporulation of wine yeast strains are defective in glucose consumption under microvinification conditions in synthetic must and p…

Study of the First Hours of Microvinification by the Use of Osmotic Stress-response Genes as Probes

2002

Summary When yeast cells are inoculated into grape must for vinification they find stress conditions because of osmolarity, which is due to very high sugar concentration, and pH lower than 4. In this work an analysis of the expression of three osmotic stress induced genes ( GPD1 , HSP12 and HSP104 ) under microvinification conditions is shown as a way to probe those stress situations and the regulatory mechanisms that control them. The results indicate that during the first hours of microvinification there is an increase in the GPD1 mRNA levels with a maximum about one hour after inoculation, and a decrease in the amount of HSP12 and HSP104 mRNAs, although with differences between them. The…

Arginase activity is a useful marker of nitrogen limitation during alcoholic fermentations.

2003

Nitrogen deficiency in musts is one of the causes of sluggish or stuck fermentations. In this work we propose that arginase activity determination can be useful for detecting nitrogen starvation early in vinification. CAR1 and YGP1 genes are not specifically induced under conditions of nitrogen starvation. However, a significant increase in the enzymatic activity of arginase, the product of the CAR1 gene, is detected in vinifications carried out with musts containing limiting amounts of nitrogen. Moreover, on adding ammonia to a nitrogen-deficient vinification, even at late stages, this enzymatic activity is repressed, and growth rate is restored simultaneously. We also investigate the role…

Dioecy and its correlates in the flowering plants

1995

From Europe to Africa and vice versa: evidence for multiple intercontinental dispersal in ribbed salamanders (Genus Pleurodeles)

2004

Aim  The intricate puzzle-like geography of the western Mediterranean is a product of long-term tectonic and orogenic events, supplemented by repeated climatic oscillations since the Pliocene. It offers numerous vicariance events that may be invoked to explain speciation in amphibians. We test for plausibility of two mutually exclusive Iberian–African vicariance hypotheses to explain the basal split within newts of the genus Pleurodeles: (1) the disconnection of the Betic arch c. 14 Ma and (2) the end of the Messinian salinity crisis 5.33 Ma. Location  Specimens of P. waltl and P. poireti were sampled from 32 populations in Portugal, Spain, Morocco, Algeria and Tunisia. Methods  Parts of th…

A molecular phylogeny of ‘true’ salamanders (family Salamandridae) and the evolution of terrestriality of reproductive modes

2009

Key innovations enable species to conquer new habitats. Within the family Salamandridae, particular adaptations to terrestrial life, such as the anatomy and physiology of the feeding apparatus, courtship behaviour and in some cases viviparity, allowed the ‘true’salamanders (genera Chioglossa, Mertensiella, Salamandra) to shift from a semi-aquatic to a more terrestrial life cycle. We sequenced 423 base pairs of the 16S RNA gene of the mitochondrial DNA for all species of the ‘true’salamanders. Based on the resulting phylogeny we discuss the evolution of terrestrial reproductive modes within this species group. We especially tested two hypotheses of monophyletic origin of specific adaptations…

Molecular systematics of two Mediterranean blenniid species from the genus Salaria (Perciformes, Blenniidae): Salaria basilisca and S. pavo

2016

Effects of Changing Rainfall on the Limnology of a Mediterranean, Flowthrough-Seepage Chain of Lakes

2006

Relationships between groundwater and lake ecology are often overlooked, but they may be strong, particularly in seepage lakes. As a result, the nature and degree of groundwater effects on lakes are usually neglected. In this study interactions among rainfall, groundwater and surface water and their limnological effects were traced seasonally for two years of changing rainfall in a Spanish flowthrough, seepage lake complex. Cumulative rainfall dictated recharge of groundwater with delays of nine months. Groundwater discharge, in turn, increased surface discharge downstream. Mediated by the geographical setting of lakes, both fluxes impinged on lake water renewal time, but effects of the lat…

Elucidating the picocyanobacteria salinity divide through ecogenomics of new freshwater isolates

2022

Abstract Background Cyanobacteria are the major prokaryotic primary producers occupying a range of aquatic habitats worldwide that differ in levels of salinity, making them a group of interest to study one of the major unresolved conundrums in aquatic microbiology which is what distinguishes a marine microbe from a freshwater one? We address this question using ecogenomics of a group of picocyanobacteria (cluster 5) that have recently evolved to inhabit geographically disparate salinity niches. Our analysis is made possible by the sequencing of 58 new genomes from freshwater representatives of this group that are presented here, representing a 6-fold increase in the available genomic data. …