Why do some sex chromosomes degenerate more slowly than others? The odd case of ratite sex chromosomes

The hallmark of sex chromosome evolution is the progressive suppression of recombination which leads to subsequent degeneration of the non-recombining chromosome. In birds, species belonging to the two major clades, Palaeognathae (including tinamous and flightless ratites) and Neognathae (all remaining birds), show distinctive patterns of sex chromosome degeneration. Birds are female heterogametic, in which females have a Z and a W chromosome. In Neognathae, the highly-degenerated W chromosome seems to have followed the expected trajectory of sex chromosome evolution. In contrast, among Palaeognathae, sex chromosomes of ratite birds are largely recombining. The underlying reason for maintenance of recombination between sex chromosomes in ratites is not clear. Degeneration of the W chromosome might have halted or slowed down due to a multitude of reasons ranging from selective processes, such as a less pronounced effect of sexually antagonistic selection, to neutral processes, such as a slower rate of molecular evolution in ratites. The production of genome assemblies and gene expression data for species of Palaeognathae has made it possible, during recent years, to have a closer look at their sex chromosome evolution. Here, we critically evaluate the understanding of the maintenance of recombination in ratites in light of the current data. We conclude by highlighting certain aspects of sex chromosome evolution in ratites that require further research and can potentially increase power for the inference of the unique history of sex chromosome evolution in this lineage of birds

Nutrição mineral de hortaliças VI deficiência de macronutrientes em cebola

Onion plants (Allium cepa L. var. Baia Piriforme Precoce de Piracicaba) were grown in pots containing 1 kg of pure quartz. Twice a day they were irrigated by percolation with nutrient solution. The treatments were: complete solution, -N, -P, -K, -Ca, -Mg and -S. The plants showed deficiencies symptoms in the following order: N, Ca, P, K, Mg and S. The deficiencies were comproved by chemical analysis of the different parts of the plant. The percentage of macronutrients in dry matter are expressed on the Table 3 in Portuguese text. "Levels" found in percentage of dry matter were: The amount of nutrients exported per plant, in mag, were: N-657.7; P-84.1; K-992.4; Ca-102.2; Mg-72.9; S-167.7.Plantas de cebola Allium cepa L. var. Baia Piriforme precoce de Piracicaba, foram cultivadas em vasos contendo silica. Foram irrigadas diversas vêzes ao dia com solução nutritiva completa e deficiente nos macronutrientes. Às plantas exibiram sintomas de carência na seguinte ordem de aparecimento: nitrogênio, cálcio, fósforo, potássio, magnésio e enxôfre. Os nutrientes foram extraídos em mg pela cebola na seguinte ordem: potássio-992, nitrogênio-658, enxôfre-168, cálcio-103, fósforo-84, magnésio-73

Gene expression variation and expression quantitative trait mapping of human chromosome 21 genes

Inter-individual differences in gene expression are likely to account for an important fraction of phenotypic differences, including susceptibility to common disorders. Recent studies have shown extensive variation in gene expression levels in humans and other organisms, and that a fraction of this variation is under genetic control. We investigated the patterns of gene expression variation in a 25 Mb region of human chromosome 21, which has been associated with many Down syndrome (DS) phenotypes. Taqman real-time PCR was used to measure expression variation of 41 genes in lymphoblastoid cells of 40 unrelated individuals. For 25 genes found to be differentially expressed, additional analysis was performed in 10 CEPH families to determine heritabilities and map loci harboring regulatory variation. Seventy-six percent of the differentially expressed genes had significant heritabilities, and genomewide linkage analysis led to the identification of significant eQTLs for nine genes. Most eQTLs were in trans, with the best result (P=7.46×10−8) obtained for TMEM1 on chromosome 12q24.33. A cis-eQTL identified for CCT8 was validated by performing an association study in 60 individuals from the HapMap project. SNP rs965951 located within CCT8 was found to be significantly associated with its expression levels (P=2.5×10−5) confirming cis-regulatory variation. The results of our study provide a representative view of expression variation of chromosome 21 genes, identify loci involved in their regulation and suggest that genes, for which expression differences are significantly larger than 1.5-fold in control samples, are unlikely to be involved in DS-phenotypes present in all affected individual

Implementation of World Health Organization Recommendations for Semen Analysis: A Survey of Laboratories in the United Kingdom

The standard method for identification of male fertility status is a semen analysis. This is performed in fertility and pathology laboratories accredited by different bodies in the UK such as the HFEA or UKAS, and is based on whether they perform licenced clinical treatment or diagnostic testing. The WHO laboratory semen analysis criteria provide the most comprehensive guidance for best practice, yet this is not strictly adhered to. Our objective was to determine any differences in semen analyses between laboratories in the UK, based on the regulatory body they are registered with. A cross-sectional survey was sent to NEQAS for andrology registrants (n=184 laboratories), HFEA (n=117 clinics), and individual ARCS members (n=682). Most ARCS members are associated with NEQAS and/or the HFEA. A ∼50% laboratory response rate (n=106 included responses) was found. Results were grouped based on accreditation: Group 1, UKAS accredited only (n=38); Group 2, both UKAS accredited and HFEA licenced (n=17); Group 3, HFEA licenced only (n=42); and Group 4, no accreditation (n=9). Over 85%of UKAS accredited laboratories (Groups 1 and 2) state they perform semen analysis according to WHO 2010 recommendations and adhere to best practice guidelines. A significantly fewer number of HFEA only laboratories (<74% Group 3, p <0:01) adhere to both guidelines. Non-HFEA laboratories (Groups 1 and 4) are almost all performing sperm counts according to WHO criteria, while <60% HFEA clinics (Groups 2 and 3) perform counts according to regulation (Group 1 vs. Groups 2 and 3: Fixed sperm, p <0:05; Neubauer chamber: p <0:005). QC is implemented in most laboratories, however there is a significant difference (p <0:01) between non- UKAS (Groups 3 and 4) and UKAS laboratories (Groups 1 and 2). There is a significant difference in semen analysis performance between UKAS and HFEA laboratories with regards to implementation of best practice guidelines and QC procedures. This may have a detrimental effect on result accuracy and consequently lead to patient misdiagnosis and mismanagement

BCAA catabolism in brown fat controls energy homeostasis through SLC25A44.

Branched-chain amino acid (BCAA; valine, leucine and isoleucine) supplementation is often beneficial to energy expenditure; however, increased circulating&nbsp;levels of BCAA are linked to obesity and diabetes. The mechanisms of this paradox remain unclear. Here we report that, on cold exposure, brown adipose tissue (BAT) actively utilizes BCAA in the mitochondria for thermogenesis and promotes systemic BCAA clearance in mice and humans. In turn, a BAT-specific defect in BCAA catabolism attenuates systemic BCAA clearance, BAT fuel oxidation and thermogenesis, leading to diet-induced obesity and glucose intolerance. Mechanistically, active BCAA catabolism in BAT is mediated by SLC25A44, which transports BCAAs into mitochondria. Our results suggest that BAT serves as a key metabolic filter that controls BCAA clearance via SLC25A44, thereby contributing to the improvement of metabolic health

DGAT1 activity synchronises with mitophagy to protect cells from metabolic rewiring by iron depletion

Mitophagy removes defective mitochondria via lysosomal elimination. Increased mitophagy coincides with metabolic reprogramming, yet it remains unknown whether mitophagy is a cause or consequence of such state changes. The signalling pathways that integrate with mitophagy to sustain cell and tissue integrity also remain poorly defined. We performed temporal metabolomics on mammalian cells treated with deferiprone, a therapeutic iron chelator that stimulates PINK1/PARKIN-independent mitophagy. Iron depletion profoundly rewired the metabolome, hallmarked by remodelling of lipid metabolism within minutes of treatment. DGAT1-dependent lipid droplet biosynthesis occurred several hours before mitochondrial clearance, with lipid droplets bordering mitochondria upon iron chelation. We demonstrate that DGAT1 inhibition restricts mitophagy in vitro, with impaired lysosomal homeostasis and cell viability. Importantly, genetic depletion of DGAT1 in vivo significantly impaired neuronal mitophagy and locomotor function in Drosophila. Our data define iron depletion as a potent signal that rapidly reshapes metabolism and establishes an unexpected synergy between lipid homeostasis and mitophagy that safeguards cell and tissue integrity.Peer reviewe

N-acetylgalactosaminyl transferase-3 is a potential new marker for non-small cell lung cancers

N-acetylgalactosaminyl transferase-3 (GalNAc-T3) is an enzyme involved in the initial glycosylation of mucin-type O-linked proteins. In the present study, we used immunohistochemistry to examine GalNAc-T3 expression in 215 surgically resected non-small cell lung cancers. We analysed the biological and clinical importance of GalNAc-T3 expression, especially with regard to its potential as a prognostic factor. We found that normal bronchial epithelial cells, bronchial gland cells, and alveolar pneumocytes showed cytoplasmic immunostaining for GalNAc-T3. Low expression of GalNAc-T3, observed in 93 of 215 tumours (43.4%), was found more frequently in tumours from smokers than those from nonsmokers (P=0.001), in squamous cell carcinomas than nonsquamous cell carcinomas (P<0.0001), and in moderately and poorly differentiated tumours than well differentiated tumours (P=0.0002). Multivariate logistic regression analysis showed that an association of low GalNAc-T3 expression with squamous cell carcinomas was the only one significant relationship of GalNAc-T3 expression with various factors (P<0.0001). Moreover, tumours losing GalNAc-T3 expression had a significantly higher Ki-67 labelling index than tumours retaining GalNAc-T3 expression (P=0.0003). Patients with low GalNAc-T3 expression survived a significantly shorter time than patients with high GalNAc-T3 expression in 103 pStage I non-small cell lung cancers (5-year survival rates, 58% and 78%, respectively; P=0.02 by log-rank test) as well as in 61 pStage I nonsquamous cell carcinomas (5-year survival rates, 63% and 85%, respectively; P=0.03). Low GalNAc-T3 expression was an unfavourable prognostic factor in pStage I non-small cell lung cancers (hazards ratio, 2.04; P=0.03), and in pStage I nonsquamous cell carcinomas (hazards ratio, 2.70; P=0.03). These results suggest that GalNAc-T3 is a new marker of non-small cell lung cancers with specificity for histology and prognosis