ABSTRACT
AIM: To determine the structure of the chimeric chromosome X of bottom-fermenting yeasts. METHODS AND RESULTS: Eight cosmid clones carrying DNA from chromosome X of bottom-fermenting yeasts were selected by end-sequencing. Four of the cosmid clones had Saccharomyces cerevisiae (SC)-type and Saccharomyces bayanus (SB)-type chimeric ends, two had SC-type ends and two had SB-type ends. Sequencing revealed that the bottom-fermenting yeast strains in this study had four types of chromosome X: SC-SC, SC-SB, SB-SC and SB-SB. The translocation site in the chimeric chromosome is conserved among bottom-fermenting yeast strains, and was created by homologous recombination within a region of high sequence identity between the SC-type sequence and the SB-type sequence. CONCLUSIONS: Existing bottom-fermenting yeast strains share a common ancestor in which the chimeric chromosome X was generated. SIGNIFICANCE AND IMPACT OF THE STUDY: The knowledge gained in this study sheds light on the evolution of bottom-fermenting yeasts.
Subject(s)
Chromosome Aberrations , Chromosomes, Fungal/genetics , Saccharomyces cerevisiae/genetics , Saccharomyces/genetics , Amino Acid Sequence , Chimera , DNA, Fungal/genetics , Hybridization, Genetic , Microarray Analysis , Polymerase Chain Reaction , Sequence Analysis, DNA , Translocation, GeneticABSTRACT
AIMS: To determine the chromosomal location and entire sequence of Lg-FLO1, the expression of which causes the flocculation of bottom-fermenting yeast. METHODS AND RESULTS: Two cosmid clones carrying DNA from a bottom-fermenting yeast chromosome VIII right-arm end were selected by colony hybridization. Sequencing revealed that the clones contained DNA derived from a Saccharomyces cerevisiae type chromosome VIII and a Saccharomyces bayanus type chromosome VIII, both from bottom-fermenting yeast. CONCLUSIONS: Lg-FLO1 is located on the S. cerevisiae type chromosome VIII at the same position as the FLO5 gene of the laboratory yeast S. cerevisiae S288c. The unique chromosome VIII structure of bottom-fermenting yeast is conserved among other related strains. FLO5 and Lg-FLO1 promoter sequences are identical except for the presence of three 42 bp repeats in the latter, which are associated with gene activity. Flocculin genes might have been generated by chromosomal recombination at these repeats. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of the exact chromosomal location and entire sequence of Lg-FLO1. This information will be useful in the brewing industry for the identification of normal bottom-fermenting yeast. Moreover, variations in the FLO5 locus among strains are thought to reflect yeast evolution.
Subject(s)
Beer , Genes, Fungal , Industrial Microbiology , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae/genetics , Base Sequence , Chromosome Mapping , Cloning, Molecular , DNA Primers/genetics , Flocculation , Mannose-Binding Lectins , Molecular Sequence Data , Phylogeny , Polymerase Chain Reaction/methods , Sequence Alignment , Sequence Analysis, DNA , Sequence HomologyABSTRACT
Okadaic acid is a metabolite of the unicellular algae dinoflagellate. Its biosynthesis has attracted considerable attention since the skeletal structure was shown to be synthesized via an unprecedented route. However, its relevant intermediates or enzymes are unknown. In the course of our previous investigations on the oxygen source of okadaic acid by tandem mass spectrometry (CID MS/MS), we determined the level of 18O incorporation for each oxygen site from 18O2 and [18O2]acetate. In the present study, we examined H218O-labelling patterns of okadaic acid from dinoflagellates in comparison with salinomycin from actinomycetes and has provided intriguing information regarding biosynthesis. Unexpectedly, oxygen atoms originating from acetate were not labelled from H218O; this can not be accounted for by the usual metabolic route where acetyl-CoA is biosynthesized via pyruvate. Similar experiments for salinomycin revealed that all of its oxygen atoms derived from acetate or propionate were labelled by H218O. Another interesting feature is that two oxygen sites were derived from both O2 and H2O while the others were labelled only from O2. These results imply that an oxidation mechanism other than those in actinomycetes polyethers may be involved in the biosynthesis of okadaic acid.
Subject(s)
Dinoflagellida/metabolism , Okadaic Acid/chemistry , Okadaic Acid/metabolism , Animals , Mass Spectrometry , Models, Molecular , Molecular Conformation , Molecular Structure , Okadaic Acid/isolation & purification , Oxygen Isotopes , Pyrans/chemistry , Pyrans/isolation & purification , WaterABSTRACT
A retrospective study is presented comparing the results of 167 frozen section diagnoses of surgical extirpated parotid gland tumors with permanent-section diagnoses. Percentages of correct diagnosis for malignancy (cases correctly classified as benign or malignant tumors) and of correct diagnosis for histopathology (cases in which frozen section diagnosis and permanent-section diagnosis were identical) were calculated. Percentages of correct diagnosis for malignancy in all cases, benign cases, and malignant cases were 98.8%, 99.3%, and 95.8%, respectively. Percentages of correct diagnosis for histopathology in all cases, benign cases, and malignant cases were 94.0%, 97.2%, and 75.0%, respectively. These results are superior to the previous reports both of frozen section diagnosis and of fine-needle aspiration biopsy diagnosis although the data for histopathological diagnosis in malignant tumors are average compared to previous reports. We conclude that diagnoses of most parotid gland tumors based on frozen section examination are reliable and accurate, but caution should be exercised in malignant tumors diagnosis.
