Cryptococcus neoformans population includes hybrid strains homozygous at mating-type locus

Recent attempts to characterise the hybrid strains of Cryptococcus neoformans have led to the identification of a cryptic population of hybrid strains ('H strains') with double DNA content but only a single mating-type allele. To verify a set of hypotheses concerning their origin, we investigated 14 previously isolated H strains and ten F1-progeny strains arising from H99 and JEC20 mating. The double DNA content was tested by flow cytometry; the presence of only one mating type was tested by amplifying 12 mating-type-specific genes and one gene unlinked with the mating-type locus (URA5). Analysis of the F1 progeny identified two H strains, and electrophoretic karyotyping confirmed the occurrence of genetic recombination. The simultaneous presence of the homozygous and heterozygous loci, and the fact that all of the F1-progeny strains presented a recombinant karyotype, suggest that the H strains originated from the post-meiotic random fusion of two of the four recombinant nuclei. Further studies are required to elucidate the role of the homozygous mating-type loci in the virulence of C. neoformans.     

Effect of Pedoclimatic Conditions on the Chemical Composition of the Sigoise Olive Cultivar

The present work focused on the quality and the chemical composition of monovarietal virgin olive oil from the Sigoise variety grown in two different locations in Tunisia, viz., a sub‐humid zone (Béjaoua, Tunis) and an arid zone (Boughrara, Sfax). In addition to the quality characteristics (acidity, peroxide value, and the spectrophotometric indices K232 and K270) and the chemical composition (content of fatty acids, antioxidants, and volatile compounds) of the oil, the fruit characteristics of the olives were studied. Except for the content of the majority of the fatty acids, there were significant differences observed in the oil composition of olives that were cultivated in different locations. The content of total phenols and lipoxygenase (LOX) oxidation products was higher for olives grown at the higher altitude, whereas that of α‐tocopherol, carotenes, and chlorophylls was higher for olives from the Boughrara region (lower altitude). Moreover, olives produced at the higher altitude showed a higher ripeness index and oil content than those cultivated at the lower altitude.     

Molecular analysis of 311 Cryptococcus neoformans isolates from a 30-month ECMM survey of cryptococcosis in Europe

During a European Confederation of Medical Mycology (ECMM) prospective survey of cryptococcosis in Europe (from July 1997 to December 1999) 655 cases were reported from 17 countries; 565 of the completed questionnaires were evaluable. Cryptococcosis was associated with HIV infection in 77% of cases (range 57.5-94%). Assessment of the laboratory data highlighted the lack of defined standard procedures for the diagnosis of cryptococcosis: the antigen test was not usually used for screening, the disease was mainly recognised when meningitis occurred (65% of patients) and, with the exception of a few cases, the extent of the infection was not investigated. Cryptococcus neoformans was the etiological agent in all of the cases except for six caused by C. gattii and four by other Cryptococcus species. A total of 311 C. neoformans strains were serotyped by Crypto Check latex agglutination, genotyped by PCR-fingerprinting using the (GACA)4 oligonucleotide as a single primer, and their mating type was determined by PCR of the STE20 alleles. Serotype A was the most represented (51% of the isolates), followed by serotype D (30%) and serotype AD (19%). PCR-fingerprinting analysis significantly increased the percentage of hybrid strains to 30%, as 6% of the serotype A and 28% of the serotype D isolates were of the VN3 or VN4 hybrid genotype. In addition, the mating type determinations revealed the MATa serotype A allele in one haploid strain and 28 hybrids, and hybrid isolates with a single mating type (four Aalpha and two Dalpha) were also identified. This is the first prospective survey to be carried out in Europe which has attempted to investigate the epidemiology of cryptococcosis and the population structure of C. neoformans, and the results obtained thus far show the widespread involvement of AD hybrid strains in C. neoformans infections.     

Genome plasticity in Festuca arundinacea: direct response to temperature changes by redundancy modulation of interspersed DNA repeats

The response of the genome of Festuca arundinacea seedlings to changes in the temperature at which they were grown was investigated. Fifteen repeated sequences in the nuclear DNA were isolated and hybridized to the genomic DNA of seedlings grown at 10 degrees C or 30 degrees C. The redundancies of sequences recognized by four probes ( FaA5, FaH8, FaH13 and FaH14), were found to differ significantly in the two DNAs. DNA sequences recognized by FaH8, FaH13 and FaH14 were more represented in the genome of the 30 degrees C-raised seedlings than in the genome of the 10 degrees C-raised seedlings (76.5 x 10(3), 1.9 x 10(3), and 111.8 x 10(3) copies per haploid, 1C genome vs 62.7 x 10(3), 1.3 x 10(3), and 80.8 x 10(3) copies, respectively). In contrast, FaA5-related sequences were more represented in the genome of seedlings grown at the lower temperature (15.5 x 10(3) vs 10.2 x 10(3) copies, respectively). Southern-blot hybridization of these repeats to digested genomic DNA produced patterns which indicated that the probe sequences were part of longer repeated sequences having a limited degree of structural heterogeneity. These patterns were partly different when the probes were hybridized to the DNA from seedlings grown at 10 degrees C or 30 degrees C. In situ hybridization showed that the DNA sequences recognized by each probe were scattered along the length of all the chromosomes, with preferential location of FaA5- and FaH13-related sequences at given, mainly centromeric, regions of certain chromosomes. These findings suggest that redundancy modulations of interspersed repeated sequences allow direct responses of the genome of F. arundinacea to changes in environmental temperature.     

Aggregation of gelsolin wild-type and G167K/R,N184K,and D187N/Y mutant peptides and inhibition

Molecular and Cellular Biochemistry - Gelsolin, an actin-binding protein, is localized intra- and extracellularly in the bloodstream and throughout the body. Gelsolin amyloidosis is a disease...