Search

The authors have studied Xanthophyllomyces dendrorhous strain UCD 67-385. They have cloned the unexpected cDNA obtained from the strain's ctrI and ctrYB and ctrYB genes' RNAs could be spliced in alternative splice sites.

Objectives: To describe characteristics and immediate results of surgical treatment of patients with intrathoracic goiter (ITG). Methods: Retrospective review. Period: October 2003 - March 2010. We describe general characteristics, morbidity and mortality. Results: 33 patients, 23 women, mean age 59.1 ± 14.3 years. Preoperative thyroid function: 32 euthyroid and 1 hyperthyroid. Asymptomatic 10 patients. ITG rate: 31 cervico-mediastinal and 2 mediastinal. Approach: 24 cervicotomy, 7 cervicotomy and sternotomy and 2 sternotomy. Type of resection: 19 total thyroidectomy and 14 subtotal thyroidectomy. Histology: 29 benign and 4 malignant neoplasms. Postoperative stay: median of 4.5 days. Complications in 12 patients: 10 hypoparathyroidism (9 transient and 1 permanent), 2 dysphonia, 2 cervical hematoma (one redo), 1 wound infection and 1 ventilator associated pneumonia. One patient died (pneumonia). Conclusions: The ITG is more common in women, most are euthyroid and may be asymptomatic. Most can be resected by cervicotomy. The histology is benign in most but may represent malignancies. The surgery is not free of morbidity and mortality. [ABSTRACT FROM AUTHOR]

Background: Xanthophyllomyces dendrorhous is a basidiomycetous yeast that synthesizes astaxanthin, which is a carotenoid with a great biotechnological impact. The ergosterol and carotenoid synthesis pathways are derived from the mevalonate pathway, and in both pathways, cytochrome P450 enzymes are involved. Results: In this study, we isolated and described the X. dendrorhous CYP61 gene, which encodes a cytochrome P450 involved in ergosterol biosynthesis. This gene is composed of nine exons and encodes a 526 amino acid polypeptide that shares significant percentages of identity and similitude with the C22-sterol desaturase, CYP61, from other fungi. Mutants derived from different parental strains were obtained by disrupting the CYP61 gene with an antibiotic selection marker. These mutants were not able to produce ergosterol and accumulated ergosta-5,8, 22-trien-3-ol and ergosta-5,8-dien-3-ol. Interestingly, all of the mutants had a more intense red color phenotype than their respective parental strains. The carotenoid composition was qualitatively and quantitatively analyzed by RP-HPLC, revealing that the carotenoid content was higher in the mutant strains without major changes in their composition. The expression of the HMGR gene, which encodes an enzyme involved in the mevalonate pathway (3-hydroxy-3-methylglutaryl-CoA reductase), was analyzed by RT-qPCR showing that its transcript levels are higher in the CYP61 mutants. Conclusions: These results suggest that in X. dendrorhous, ergosterol regulates HMGR gene expression by a negative feedback mechanism and in this way; it contributes in the regulation of the carotenoid biosynthesis. [ABSTRACT FROM AUTHOR]

The term periodontitis encompasses several polymicrobial infectious diseases, of multifactorial etiology, with chronic and aggressive forms. In spite of the etiopathogenic differences between these two forms of the disease, few studies have analyzed the subgingival colonization by yeast. The objective of this investigation was to analyze the composition of the yeast microbiota present in the mucosa and subgingival sites of healthy individuals and patients with aggressive and chronic periodontitis. For this, samples were recovered from these two locations and the yeast recovered identified by phenotypic and genotypic methods. Patients with chronic periodontitis showed significant differences in relation to the other groups with respect to carrier status (69.2% versus 35.7% of healthy individuals; [χi2 test; p=0.014]), the total number of isolated colony forming units or CFU (mean and ranges 281.6 (0-6048) [K-W2=6.998; p=0.03]), the Simpson diversity index (I) in site b (Ib=0.344 versus healthy subjet and aggresive periodontitis where I=0 [multiple t-test comparisons with the Bonferronni correction, p<0.05]), and the species profile. Interestingly, in spite of the varied profiles of the species present in the mucosa of the three groups analyzed we noted that only C. albicans and C. dubliniensis were capable of colonizing the periodontal pockets in patients with chronic periodontitis, while only C. albicans was identified in the subgingiva of healthy individuals and patients with aggressive periodontitis. [ABSTRACT FROM AUTHOR]

The yeast Xanthophyllomyces dendrorhous synthesizes astaxanthin, a high-value carotenoid with biotechnological relevance in the nutraceutical and aquaculture industries. However, enhancing carotenoid production through strain engineering remains an ongoing challenge. Recent studies have demonstrated that carotenogenesis in X. dendrorhous is regulated by the SREBP pathway, which includes the transcription factor Sre1, particularly in the mevalonate pathway that also produces precursors used for ergosterol synthesis. In this study, we explored a novel approach to enhance carotenoid synthesis by replacing the native crtE promoter, which drives geranylgeranyl pyrophosphate synthesis (the step where carotenogenesis diverges from ergosterol biosynthesis), with the promoter of the HMGS gene, which encodes 3-hydroxy-3-methylglutaryl-CoA synthase from the mevalonate pathway. The impact of this substitution was evaluated in two mutant strains that already overproduce carotenoids due to the presence of an active Sre1 transcription factor: CBS.cyp61-, which does not produce ergosterol and strain CBS.SRE1N.FLAG, which constitutively expresses the active form of Sre1. Wild-type strain CBS6938 was used as a control. Our results showed that this modification increased the crtE transcript levels more than threefold and fourfold in CBS.cyp61 - .pHMGS/crtE and CBS.SRE1N.FLAG.pHMGS/crtE, respectively, resulting in 1.43-fold and 1.22-fold increases in carotenoid production. In contrast, this modification did not produce significant changes in the wild-type strain, which lacks the active Sre1 transcription factor under the same culture conditions. This study highlights the potential of promoter substitution strategies involving genes regulated by Sre1 to enhance carotenoid production, specifically in strains where the SREBP pathway is activated, offering a promising avenue for strain improvement in industrial applications., (© 2024. The Author(s).)

Codon usage bias (CUB) has been described in viruses, prokaryotes, and eukaryotes and has been linked to several cellular and environmental factors, such as the organism's growth temperature, gene expression levels, and regulation of protein synthesis and folding. Most of the studies in this area have been conducted in bacteria and higher eukaryotes, in some cases with different results. In this study, a comparative analysis of CUB in yeasts isolated from cold and template environments was performed in order to evaluate the correlation of CUB with yeast optimal temperature of growth (OTG), gene expression levels, cellular function, and structure of encoded proteins. Among the main findings, highly expressed ORFs tend to have a more similar CUB within and between yeasts, and a direct correlation between codons ending in C and expression level was generally found. A low correspondence between CUB and OTG was observed, with an inverse correlation for some codons ending in C. The clustering of yeasts based on their CUB partially aligns with their OTG, being more consistent for yeasts with lower OTG. In most yeasts, the abundance of preferred codons was generally lower at the 5' end of ORFs, higher in segments encoding beta strand, lower in segments encoding extracellular and transmembrane regions, and higher in "translation" and "energy metabolism" pathways, especially in highly expressed ORFs. Based on our findings, it is suggested that the abundance and distribution of preferred and non-preferred codons along mRNAs contribute to proper protein folding and functionality by regulating protein synthesis rates, becoming a more important factor under conditions that require faster protein synthesis in yeasts., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Baeza, Sepulveda, Cifuentes and Alcaíno.)

The sterol regulatory element-binding protein (SREBP) pathway is an integral cellular mechanism that regulates lipid homeostasis, in which transcriptional activator SREBPs regulate the expression of various genes. In the carotenogenic yeast Xanthophyllomyces dendrorhous , Sre1 (the yeast SREBP homolog) regulates lipid biosynthesis and carotenogenesis, among other processes. Despite the characterization of several components of the SREBP pathway across various eukaryotes, the specific elements of this pathway in X. dendrorhous remain largely unknown. This study aimed to explore the potential regulatory mechanisms of the SREBP pathway in X. dendrorhous using the strain CBS. cyp61 - as a model, which is known to have Sre1 in its active state under standard culture conditions, resulting in a carotenoid-overproducing phenotype. This strain was subjected to random mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine (NTG), followed by a screening methodology that focused on identifying mutants with altered Sre1 activation phenotypes. Single-nucleotide polymorphism (SNP) analysis of 20 selected mutants detected 5439 single-nucleotide variants (SNVs), narrowing them down to 1327 SNPs of interest after a series of filters. Classification based on SNP impact identified 116 candidate genes, including 49 genes with high impact and 68 genes with deleterious moderate-impact mutations. BLAST, InterProScan, and gene ontology enrichment analyses highlighted 25 genes as potential participants in regulating Sre1 in X. dendrorhous . The key findings of this study include the identification of genes potentially encoding proteins involved in protein import/export to the nucleus, sterol biosynthesis, the ubiquitin-proteasome system, protein regulatory activities such as deacetylases, a subset of kinases and proteases, as well as transcription factors that could be influential in SREBP regulation. These findings are expected to significantly contribute to the current understanding of the intricate regulation of the transcription factor Sre1 in X. dendrorhous , providing valuable groundwork for future research and potential biotechnological applications.

Background: Executive function is often altered in overweight/obese children and adolescents, which has a negative impact on their learning and daily life. Furthermore, research has shown the benefits of physical exercise in improving cognitive performance. This protocol aims to define in a detailed and structured manner the procedures that will be conducted for the development of a systematic review of the literature aimed at evaluating the effects of physical exercise on the executive functions of children and adolescents (≤18 years) with overweight/obesity in comparison with peers in control groups., Methods: The Web of Science, PubMed, Scopus, and EBSCO databases will be searched for longitudinal studies that have at least one experimental and one control group using pre- and post-intervention measures of executive function, including working memory, inhibition, and cognitive flexibility in the pediatric population who are overweight or obese. The risk of bias and certainty of evidence will be assessed using Cochrane RoB2 and GRADE, respectively. Furthermore, Der Simonian-Laird's random effects model will be employed for meta-analyses. The effect sizes will be calculated with 95% confidence intervals, and p values < 0.05 indicate statistical significance for each dimension of executive function in the different groups before and after the intervention., Discussion: The results of this review may be useful for education and health professionals to design treatment plans for overweight/obese children and adolescents, offering potential benefits related to the learning and cognitive abilities of this population. PROSPERO registration number: CRD42023391420.

Introduction: Lactic acid bacteria (LAB) produce various metabolites (i.e. metabiotics) with inhibitory capacity towards harmful foodborne pathogens., Methods: This study aimed to design several antimicrobial formulations based on metabiotics obtained from different native LAB species ( Lactobacillus pentosus UTNGt5, Lactococcus lactis UTNGt28, and Weissella cibaria UTNGt21O) and to detect the possible mode of action towards two multidrug resistant Staphylococcus spp. strains isolated from avocado ( Persea nubigena var. guatemalensis ) fruits. Additionally, the formulation with the highest inhibitory activity was tested ex vitro on avocados at the immature (firm) ripeness stage to evaluate their effect on microorganisms' growth and fruit quality attributes post-harvest., Results and Discussion: Out of the top five formulations showing the highest bactericidal effect in vitro at their minimum inhibitory concentration (1 x MIC) on both Staphylococcus spp. targets one candidate annotated P11 (consisting of UTNGt21O and UTNGt28; 1:3, v/v) was selected. Co-cultivation of Staphylococcus strains with P11 formulation results in cell viability reduction by 98%, by impairing the integrity of the cell membrane inducing cytoplasm molecule content leakage, protein profile changes, and finally bacterial death. Even though the total coliforms, Staphylococcus spp., Enterobacte r spp., molds, and yeasts counts were not fully eliminated by day 13 of storage, a statistically significant reduction ( p  < 0.05) in viable cell counts were observed by day 8 upon the P11 treatment compared with non-treated control (C) and treated with a commercial disinfectant (T1) samples, suggesting that P11 formulation inhibited microbial colonization during storage. Likewise, no visible dark spots were observed on the mesocarp (pulp) upon the treatment with P11, whereas T1 and C fruits showed greater dark spots on the pulp as indicative of damage. The quality attributes, such as pH, total soluble solids, total titratable acidity, antioxidant capacity, and total polyphenol content, were not affected by the treatment. Principal Component Analysis (PCA) conducted on these five variables showed a clear separation of samples according to the maturity stage regardless of the treatment., Conclusion: These results suggest that the active metabolites from LAB strains might create a barrier between the exocarp and mesocarp, inhibiting the microorganisms colonization, reducing fruit damage, and lengthening the fruit quality and safety after harvest., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Tenea, Angamarca, Cifuentes and Hidalgo.)