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LSM4 is an essential yeast gene encoding a component of different LSM complexes involved in the regulation of mRNA splicing, stability, and translation. In previous papers, we reported that the expression in S. cerevisiae of the K. lactis LSM4 gene lacking the C-terminal Q/N-rich domain in an Lsm4 null strain S. cerevisiae (Sclsm4Δ1) restored cell viability. Nevertheless, in this transformed strain, we observed some phenotypes that are typical markers of regulated cell death, reactive oxygen species (ROS), and oxidated RNA accumulation. In this paper, we report that a similar truncation operated in the S. cerevisiae LSM4 gene confers on cells the same phenotypes observed with the K. lactis lsm4Δ1 gene. Up until now, there was no evidence of the direct involvement of LSM4 in autophagy. Here we found that the Sclsm4Δ1 mutant showed a block in the autophagic process and was very sensitive to nitrogen starvation or treatment with low doses of rapamycin, an inducer of autophagy. Moreover, both during nitrogen starvation and aging, the Sclsm4Δ1 mutant accumulated cytoplasmic autophagy-related structures, suggesting a role of Lsm4 in a later step of the autophagy process.

Living organisms on the surface biosphere are periodically yet consistently exposed to light. The adaptive or protective evolution caused by this source of energy has led to the biological systems present in a large variety of organisms, including fungi. Among fungi, yeasts have developed essential protective responses against the deleterious effects of light. Stress generated by light exposure is propagated through the synthesis of hydrogen peroxide and mediated by regulatory factors that are also involved in the response to other stressors. These have included Msn2/4, Crz1, Yap1, and Mga2, thus suggesting that light stress is a common factor in the yeast environmental response.

Lactic acid bacteria (LAB) share and provide several beneficial effects on human health, such as the release of bioactive metabolites, pathogen competition, and immune stimulation. The two major reservoirs of probiotic microorganisms are the human gastro-intestinal tract and fermented dairy products. However, other sources, such as plant-based foods, represent important alternatives thanks to their large distribution and nutritive value. Here, the probiotic potential of autochthonous Lactiplantibacillus plantarum PFA2018AU, isolated from carrots harvested in Fucino highland, Abruzzo (Italy), was investigated through in vitro and in vivo approaches. The strain was sent to the biobank of Istituto Zooprofilattico Sperimentale della Lombardia ed Emilia Romagna in Italy for the purpose of patent procedures under the Budapest Treaty. The isolate showed high survival capability under in vitro simulated gastro-intestinal conditions, antibiotic susceptibility, hydrophobicity, aggregation, and the ability to inhibit the in vitro growth of Salmonella enterica serovar Typhimurium, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus pathogens. Caenorhabditis elegans was used as the in vivo model in order to analyse prolongevity and anti-ageing effects. L. plantarum PFA2018AU significantly colonised the gut of the worms, extended their lifespan, and stimulated their innate immunity. Overall, these results showed that autochthonous LAB from vegetables, such as carrots, have functional features that can be considered novel probiotic candidates.

The 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme of the mevalonate pathway for the synthesis of cholesterol in mammals (ergosterol in fungi), is inhibited by statins, a class of cholesterol lowering drugs. Indeed, statins are in a wide medical use, yet statins treatment could induce side effects as hepatotoxicity and myopathy in patients. We used Saccharomyces cerevisiae as a model to investigate the effects of statins on mitochondria. We demonstrate that statins are active in S.cerevisiae by lowering the ergosterol content in cells and interfering with the attachment of mitochondrial DNA to the inner mitochondrial membrane. Experiments on murine myoblasts confirmed these results in mammals. We propose that the instability of mitochondrial DNA is an early indirect target of statins.

Divergence of paralogous pairs, resulting from gene duplication, plays an important role in the evolution of specialized or novel gene functions. Analysis of selected duplicated pairs has elucidated some of the mechanisms underlying the functional diversification of Saccharomyces cerevisiae (S. cerevisiae) paralogous genes. Similar studies of the orthologous pairs extant in pre-whole genome duplication yeast species, such as Kluyveromyces lactis (K. lactis) remain to be addressed. The genome of K. lactis, an aerobic yeast, includes gene pairs generated by sporadic duplications. The genome of this organism comprises the KlLEU4 and KlLEU4BIS paralogous pair, annotated as putative α-isopropylmalate synthases (α-IPMSs), considered to be the orthologs of the S. cerevisiae ScLEU4/ScLEU9 paralogous genes. The enzymes encoded by the latter two genes are mitochondrially located, differing in their sensitivity to leucine allosteric inhibition resulting in ScLeu4-ScLeu4 and ScLeu4-ScLeu9 sensitive dimers and ScLeu9-ScLeu9 relatively resistant homodimers. Previous work has shown that, in a Scleu4Δ mutant, ScLEU9 expression is increased and assembly of ScLeu9-ScLeu9 leucine resistant homodimers results in loss of feedback regulation of leucine biosynthesis, leading to leucine accumulation and decreased growth rate. Here we report that: (i) K. lactis harbors a sporadic gene duplication, comprising the KlLEU4, syntenic with S. cerevisiae ScLEU4 and ScLEU9, and the non-syntenic KlLEU4BIS, arising from a pre-WGD event. (ii) That both, KlLEU4 and KlLEU4BIS encode leucine sensitive α-IPMSs isozymes, located in the mitochondria (KlLeu4) and the cytosol (KlLeu4BIS), respectively. (iii) That both, KlLEU4 or KlLEU4BIS complement the Scleu4Δ Scleu9Δ leucine auxotrophic phenotype and revert the enhanced ScLEU9 transcription observed in a Scleu4Δ ScLEU9 mutant. The Scleu4Δ ScLEU9 growth mutant phenotype is only fully complemented when transformed with the syntenic KlLEU4 mitochondrial isoform. KlLEU4 and KlLEU4BIS underwent a different diversification pathways than that leading to ScLEU4/ScLEU9. KlLEU4 could be considered as the functional ortholog of ScLEU4, since its encoded isozyme can complement both the Scleu4Δ Scleu9Δ leucine auxotrophy and the Scleu4Δ ScLEU9 complex phenotype.

Abstract Background During the past years, a number of studies have demonstrated the positive effect of apple on ageing and different diseases such as cancer, degenerative and cardiovascular diseases. The unicellular yeast Saccharomyces cerevisiae represents a simple eukaryotic model to study the effects of different compounds on lifespan. We previously demonstrated that apple extracts have anti-ageing effects in this organism because of their antioxidant properties. In particular, the effect is related to the presence in this fruit of polyphenols, which give a large contribution to the antioxidant activity of apples. Methods We we used a clonogenic assay to assess the viability and the resistance to oxidative stress of S. cerevisiae cells in the presence of Annurca apple extracts. The production of ROS and the aberrant morphology of nuclei were detected by cell staining with the fluorescent dies Dihydrorhodamine 123 and DAPI, respectively. Mitochondrial morphology was analyzed by following the localization of the mito-GFP protein into the mitochondrial matrix. Results In this study, we show that apple extracts can increase yeast lifespan, reduce the levels of reactive oxygen species and cell sensitivity to oxidative stress, and prevent nuclei and mitochondria fragmentation protecting cells from regulated cell death. Conclusions In this paper, by using the yeast S. cerevisiae as a model, we have demonstrated that Annurca extracts possess antioxidant properties thanks to which the extracts can reduce the intracellular ROS levels and have anti-apoptotic functions thus prolonging cell lifespan. These results contribute to knowledge on the effects of natural compounds on ageing and support the use of yeast as a model organism for the development of simple tests to assess the effectiveness of bioactive substances from natural sources.

Blue light, a key abiotic signal, regulates a wide variety of physiological processes in many organisms. One of these phenomena is the circadian rhythm presents in organisms sensitive to the phase-setting effects of blue light and under control of the daily alternation of light and dark. Circadian clocks consist of autoregulatory alternating negative and positive feedback loops intimately connected with the cellular metabolism and biochemical processes. Neurospora crassa provides an excellent model for studying the molecular mechanisms involved in these phenomena. The White Collar Complex (WCC), a blue-light receptor and transcription factor of the circadian oscillator, and Frequency (FRQ), the circadian clock pacemaker, are at the core of the Neurospora circadian system. The eukaryotic circadian clock relies on transcriptional/translational feedback loops: some proteins rhythmically repress their own synthesis by inhibiting the activity of their transcriptional factors, generating self-sustained oscillations over a period of about 24 h. One of the basic mechanisms that perpetuate self-sustained oscillations is post translation modification (PTM). The acronym PTM generically indicates the addition of acetyl, methyl, sumoyl, or phosphoric groups to various types of proteins. The protein can be regulatory or enzymatic or a component of the chromatin. PTMs influence protein stability, interaction, localization, activity, and chromatin packaging. Chromatin modification and PTMs have been implicated in regulating circadian clock function in Neurospora. Research into the epigenetic control of transcription factors such as WCC has yielded new insights into the temporal modulation of light-dependent gene transcription. Here we report on epigenetic and protein PTMs in the regulation of the Neurospora crassa circadian clock. We also present a model that illustrates the molecular mechanisms at the basis of the blue light control of the circadian clock.