Isolation, identification and oenological characterization of non-Saccharomyces yeasts in a Mediterranean island

We isolated, identified and characterized yeast strains from grapes, and their fermented musts, sampled in the small island of Linosa, where there are no wineries and therefore the possibility of territory contamination by industrial strains is minimal. By traditional culture-dependent methods, we isolated 3805 colonies, distinguished by molecular methods in 17 different species. Five hundred and forty-four isolates were analysed for the main oenological characteristics such as fermentative vigour with and without sulphites, sugar consumption and production of alcohol, volatile acidity, hydrogen sulphide, glycerol and β-glucosidase. This analysis identified Kluyveromyces marxianus (seldomly used in winemaking) as the most interesting candidate yeast for the production of innovative wines.

SIGNIFICANCE AND IMPACT OF THE STUDY

In recent years, interest is growing for wine production by non-Saccharomyces yeasts, both in research and in the industry. This study describes the yeast population of the grapes in a small-secluded island in the Mediterranean Sea, useful site for the search of new strains. Evaluation of fundamental oenological characters identifies potential best yeasts to assay in experimental vinifications. We also describe, for the first time, 14 new colony morphologies on WL Nutrient Agar, culture medium used to monitor the yeast population dynamics.

Temporal variations in the usefulness of normalized difference vegetation index as a predictor for Ixodes ricinus (Acari: Ixodidae) in a Borrelia lusitaniae focus in Tuscany, central Italy

Host-seeking ticks were collected during monthly dragging sessions from November 2004 through October 2006 in Tuscany, central Italy. Normalized difference vegetation index (NDVI), which was calculated from Landsat ETM+ 7 remote sensing data recorded in August 2001, was significantly correlated with numbers of host-seeking immature Ixodes ricinus L. (Acari: Ixodidae) during periods of relatively low rainfall such as summer 2005 (Spearman's p = 0.78, P < 0.001 for nymphs in July) and to a lower extent in spring-summer 2006. In spring 2005, when rainfall was relatively high, the correlation was weak and not statistically significant. Generalized estimating equations (GEEs), taking into account repeated sampling of the same dragging sites, were used to model the effects of NDVI and season on counts of host-seeking I. ricinus nymphs. Seasonal variations of the effect of NDVI yielded a significant NDVI-by-season interaction in the first year of the study (November 2004-October 2005), but not in the second year (November 2005-October 2006) when there was a 2.5-fold increase of the number of nymphs per 100-m dragging for every 0.1 unit increase in NDVI (95% confidence interval = 1.6, 3.0). Risk maps that were obtained based on GEE results confirmed that the predicted number of I. ricinus nymphs per 100 m was relatively homogeneous through the study area during the 2005 spring peak of activity. Conversely, in 2006, the predicted abundance of nymphs was greater in moist bottomland habitat (characterized by high NDVI) than in dry, typically Mediterranean, upland habitat.

Temporal variations in the usefulness of normalized difference vegetation index as a predictor for Ixodes ricinus (Acari: Ixodidae) in a Borrelia lusitaniae focus in Tuscany, central Italy

Host-seeking ticks were collected during monthly dragging sessions from November 2004 through October 2006 in Tuscany, central Italy. Normalized difference vegetation index (NDVI), which was calculated from Landsat ETM+ 7 remote sensing data recorded in August 2001, was significantly correlated with numbers of host-seeking immature Ixodes ricinus L. (Acari: Ixodidae) during periods of relatively low rainfall such as summer 2005 (Spearman's p = 0.78, P < 0.001 for nymphs in July) and to a lower extent in spring-summer 2006. In spring 2005, when rainfall was relatively high, the correlation was weak and not statistically significant. Generalized estimating equations (GEEs), taking into account repeated sampling of the same dragging sites, were used to model the effects of NDVI and season on counts of host-seeking I. ricinus nymphs. Seasonal variations of the effect of NDVI yielded a significant NDVI-by-season interaction in the first year of the study (November 2004-October 2005), but not in the second year (November 2005-October 2006) when there was a 2.5-fold increase of the number of nymphs per 100-m dragging for every 0.1 unit increase in NDVI (95% confidence interval = 1.6, 3.0). Risk maps that were obtained based on GEE results confirmed that the predicted number of I. ricinus nymphs per 100 m was relatively homogeneous through the study area during the 2005 spring peak of activity. Conversely, in 2006, the predicted abundance of nymphs was greater in moist bottomland habitat (characterized by high NDVI) than in dry, typically Mediterranean, upland habitat.

Borrelia lusitaniae OspA gene heterogeneity in Mediterranean basin area

In this study, Borrelia lusitaniae DNA extracted from ticks and lizards was used to amplify the outer surface protein A (OspA) gene in order to increase knowledge about sequence variability in the Mediterranean basin area, to better understand how Borrelia lusitaniae has evolved and how its distribution has expanded. Phylogenetic trees including Italian and reference sequences showed a clear separation of B. lusitaniae OspA strains in two different major clades. North African isolates form a clade with Portuguese POTIB strains, whereas Italian samples are grouped with German strains and a human Portuguese strain. This subdivision was supported by very high posterior probability values in the trees, by both analysis of molecular variance and selective pressure. These results, based on phylogenetic information contained in the OspA gene sequences, show the presence of two different B. lusitaniae strains circulating in the Mediterranean basin area, suggesting two different evolution paths.

Borrelia lusitaniae in immature Ixodes ricinus (Acari: Ixodidae) feeding on common wall lizards in Tuscany, central Italy

Lizards and small rodents were live captured in Tuscany, central Italy, from May through August 2005. Prevalence of infestation by larval Ixodes ricinus L. (Acari: Ixodidae) and mean numbers of larvae per host were not significantly different for common wall lizards, Podarcis muralis Laurenti, and Apodemus spp. mice, whereas infestation levels by nymphs were significantly greater on lizards. Borrelia lusitaniae, which was previously shown to be dominant in host-seeking I. ricinus in the same study area, was detected by polymerase chain reaction (PCR) in 19.8% (95% confidence interval: 14.4, 26.0) of larval ticks and in 52.9% (27.8, 77.0) of nymphs that were collected from lizards. Moreover, 18.8% (7.2, 36.4) and 25.0 (3.2, 65.1) of lizards' tail biopsies and blood samples, respectively, were positive for B. lusitaniae. Conversely, attached ticks and ear biopsies from Apodemus spp. mice were PCR negative. Passerine birds belonging to 10 species were live captured in March 2005, and Borrelia valaisiana was detected in 57.1% (18.4, 90.1) of I. ricinus nymphs feeding on Eurasian blackbirds, Turdus merula L. Results of this study suggest that lizards play an important role as reservoirs for B. lusitanae and may affect the dominance of this genospecies in the Mediterranean area.

Borrelia lusitaniae and spotted fever group rickettsiae in Ixodes ricinus (Acari: Ixodidae) in Tuscany, central Italy

Prevalence of infection by Borrelia burgdorferi s.l. and spotted fever group (SFG) rickettsiae was estimated in host-seeking ticks in an area in Tuscany, central Italy, where Lyme borreliosis was reported in a forestry worker. B. burgdorferi s.l. was identified by polymerase chain reaction in 16.7% (95% CI = 10.3, 24.8) of Ixodes ricinus (L.) nymphs and 39.6% (95% CI = 26.5, 54.0) of adults. Borrelia lusitaniae accounted for 82.9% of positive samples, followed by Borrelia garinii (9.8%), Borrelia afzelii (2.4%), and Borrelia burgdorferi s.s. (2.4%). One Rhipicephalus spp. adult was infected with B. garinii (prevalence = 8.3%; 95% CI = 0.21, 38.5). Prevalence of infection by SFG rickettsiae was 38.5% (95% CI = 26.7, 51.4) in I. ricinus nymphs, 34.6% (95% CI = 22.0, 49.1) in I. ricinus adults, and 50% (95% CI = 21.1, 78.9) in Rhipicephalus spp. adults. Phylogenetic analysis showed the similarity of B. lusitaniae strains that were identified in this study and of a strain that was previously isolated from a human patient in Portugal. Results of this study confirm the dominance of B. lusitaniae in areas in the Mediterranean basin and the infection by SFG rickettsiae in I. ricinus.

Recovery of developmentally defined gene sets from high-density cDNA macroarrays

New technologies for isolating differentially expressed genes from large arrayed cDNA libraries are reported. These methods can be used to identify genes that lie downstream of developmentally important transcription factors and genes that are expressed in specific tissues, processes, or stages of embryonic development. Though developed for the study of gene expression during the early embryogenesis of the sea urchin Strongylocentrotus purpuratus, these technologies can be applied generally. Hybridization parameters were determined for the reaction of complex cDNA probes to cDNA libraries carried on six nylon filters, each containing duplicate spots from 18,432 bacterial clones (macroarrays). These libraries are of sufficient size to include nearly all genes expressed in the embryo. The screening strategy we have devised is designed to overcome inherent sensitivity limitations of macroarray hybridization and thus to isolate differentially expressed genes that are represented only by low-prevalence mRNAs. To this end, we have developed improved methods for the amplification of cDNA from small amounts of tissue (as little as approximately 300 sea urchin embryos, or 2 x 10(5) cells, or about 10 ng of mRNA) and for the differential enhancement of probe sequence concentration by subtractive hybridization. Quantitative analysis of macroarray hybridization shows that these probes now suffice for detection of differentially expressed mRNAs down to a level below five molecules per average embryo cell.

Effect of the IMPase inhibitor L690,330 on sea urchin development

A variety of concentrations of the IMPase inhibitor L690,330 were added to sea urchin embryos. Immediate arrest of development was obtained for concentrations from 7.5 mm on. Concentrations lower than 3.5 mm permitted gastrulation but inhibited skeletogenesis and disturbed elongation along the animal-vegetal axis. The latter results are similar to those obtained by counteracting lithium effect with myoinositol, which are suggested to be due to partial relief of IMPase inhibition.

Identification and characterization of a constitutive HSP75 in sea urchin embryos

An antiserum against a hsp of the 70-kDa family was prepared, by means of a fusion protein, which was able to detect a constitutive 75-kDa hsc in the sea urchin P. lividus. This hsc was present both during oogenesis and at all developmental stages. A two-dimensional electrophoresis has revealed four isolectric forms of this 75-kDa hsc. The amino acid sequence of the fragment used to prepare the anti-hsp70 antibodies revealed a 43% identity with the corresponding part of sea urchin sperm receptor, and in mature eggs a brighter immunofluorescence was seen all around the cell cortex where the receptor for sea urchin sperm is localized. In oocytes the hsp75 was localized in the cytoplasms but not in the nuclei. In the embryos a higher hsp75 concentration was found in the portion facing the lumen of the cells which invaginate at gastrulation.

Activation by heat shock of hsp70 gene transcription in sea urchin embryos

We had previously shown that P. lividus embryos subjected to heat shock are unable to synthesize proteins of the hsp70 family at a detectable level before the hatching blastula stage. We show here that this is not due to the inability to synthesize the hsp70 mRNAs, which are detectable following heat shock also in early stages, although in much lower amounts per embryo than in later stages. These mRNAs are also translated, as judged by the facts that they are present in the polysomal pellet, and that they are translatable in a cell free system. As to the question of the amount of hsp70 RNAs per nucleus, we conclude that this is also higher in later than in earlier stages. The presence of hsp70 mRNAs is already detectable after heating at 4 centigrades above 20 and their amount increases with the increase of temperature in the range between 24 degrees C and 28 degrees C.