Evidence for an adaptation mechanism of mitochondrial translation via tRNA import from the cytosol

Although mitochondrial import of nuclear DNA-encoded RNAs is widely occurring, their functions in the organelles are not always understood. Mitochondrial function(s) of tRNA(Lys)(CUU), tRK1, targeted into Saccharomyces cerevisiae mitochondria was mysterious, since mitochondrial DNA-encoded tRNA(Lys)(UUU), tRK3, was hypothesized to decode both lysine codons, AAA and AAG. Mitochondrial targeting of tRK1 depends on the precursor of mitochondrial lysyl-tRNA synthetase, pre-Msk1p. Here we show that substitution of pre-Msk1p by its Ashbya gossypii ortholog results in a strain in which tRK3 is aminoacylated, while tRK1 is not imported. At elevated temperature, drop of tRK1 import inhibits mitochondrial translation of mRNAs containing AAG codons, which coincides with the impaired 2-thiolation of tRK3 anticodon wobble nucleotide. Restoration of tRK1 import cures the translational defect, suggesting the role of tRK1 in conditional adaptation of mitochondrial protein synthesis. In contrast with the known ways of organellar translation control, this mechanism exploits the RNA import pathway.     

Effect of hyperosmotic shock on phosphoenolpyruvate carboxykinase gene expression and gluconeogenic activity in the crab muscle

Chasmagnathus granulata phosphoenolpyruvate carboxykinase (PEPCK) cDNA from jaw muscle was cloned and sequenced, showing a specific domain to bind phosphoenolpyruvate in addition to the kinase-1 and kinase-2 motifs to bind guanosine triphosphate (GTP) and Mg(2+), respectively, specific for all PEPCKs. In the kinase-1 motifs the GK was changed to RK. The first 19 amino acids of the putative enzyme contain hydrophobic amino acids and hydroxylated residues specific to a mitochondrial type signal. The PEPCK is expressed in hepatopancreas, muscles, nervous system, heart, and gills. Hyperosmotic stress for 24 h increased the PEPCK mRNA level, gluconeogenic and PEPCK activities in muscle.     

Patient and observer reported outcome measures to evaluate health-related quality of life in inherited metabolic diseases: a scoping review

Background

Health-related Quality of Life (HrQoL) is a multidimensional measure, which has gained clinical and social relevance. Implementation of a patient-centred approach to both clinical research and care settings, has increased the recognition of patient and/or observer reported outcome measures (PROMs or ObsROMs) as informative and reliable tools for HrQoL assessment. Inherited Metabolic Diseases (IMDs) are a group of heterogeneous conditions with phenotypes ranging from mild to severe and mostly lacking effective therapies. Consequently, HrQoL evaluation is particularly relevant.

Objectives

We aimed to: (1) identify patient and/or caregiver-reported HrQoL instruments used among IMDs; (2) identify the main results of the application of each HrQoL tool and (3) evaluate the main limitations of HrQoL instruments and study design/methodology in IMDs.

Methods

A scoping review was conducted using methods outlined by Arksey and O’Malley. Additionally, we critically analysed each article to identify the HrQoL study drawbacks.

Results

Of the 1954 studies identified, 131 addressed HrQoL of IMDs patients using PROMs and/or ObsROMs, both in observational or interventional studies. In total, we identified 32 HrQoL instruments destined to self- or proxy-completion; only 2% were disease-specific. Multiple tools (both generic and disease-specific) proved to be responsive to changes in HrQoL; the SF-36 and PedsQL questionnaires were the most frequently used in the adult and pediatric populations, respectively. Furthermore, proxy data often demonstrated to be a reliable approach complementing self-reported HrQoL scores. Nevertheless, numerous limitations were identified especially due to the rarity of these conditions.

Conclusions

HrQoL is still not frequently assessed in IMDs. However, our results show successful examples of the use of patient-reported HrQoL instruments in this field. The importance of HrQoL measurement for clinical research and therapy development, incites to further research in HrQoL PROMs’ and ObsROMs’ creation and validation in IMDs.

     

Familiar soil conditions help Pinus ponderosa seedlings cope with warming and drying climate

Changes in temperature and moisture as a result of climate forcing can impact performance of planted trees. Tree performance may also be sensitive to new soil conditions, for example, brought about by seeds germinating in soils different from those colonized by ancestral populations. Such “edaphic constraint” may occur with natural migration or human‐assisted movement. Pinus ponderosa seedlings, sourced from one location (“home” site), were grown across a field environmental gradient in either their original home soil or in soils from two different “away” sites. Seedlings were inoculated with site‐specific soil organisms by germinating seeds in living soil. After 6 months, the inoculated seedlings were transplanted into sterilized soils from the home or away sites. This experimental design allowed us to uncouple the importance of abiotic and biotic soil properties and test (1) how biotic and abiotic soil properties interact with climate to influence plant growth and stress tolerance, and (2) the role of soil biota in facilitating growth in novel environments. Seedlings grew least in hotter and drier away sites with away soil biota. Home soil biota ameliorated negative impacts on growth of hotter and drier away sites. Measurements of photosynthetic rate, stomatal conductance, and chlorophyll florescence (Fv/Fm) suggest that edaphic constraint reduced growth by increasing tree water stress. Results suggest that success of Ponderosa pine plantings into warming environments will be enhanced by pre‐inoculation with native soil biota of the seed source.     

Candidemia by Species of the Candida parapsilosis Complex in Children’s Hospital: Prevalence, Biofilm Production and Antifungal Susceptibility

Opportunistic infections are an increasingly common problem in hospitals, and the yeast Candida parapsilosis has emerged as an important nosocomial pathogen. The aims of this study were to determine and compare (i) the prevalence rate among C. parapsilosis complex organisms isolated from blood in a public children’s hospital in São Paulo state, (ii) the ability of the complex C. parapsilosis species identified to produce biofilm and (iii) the antifungal susceptibility profiles. Forty-nine (49) specimens of isolated blood yeast were analyzed, previously identified as C. parapsilosis by conventional methods. After the molecular analysis, the isolates were characterized as C. parapsilosis sensu stricto (83.7 %), C. orthopsilosis (10.2 %) and C. metapsilosis (6.1 %). All species were able to form biofilm. The species with the highest biofilm production was C. parapsilosis sensu stricto, followed by C. orthopsilosis and further by C. metapsilosis. All of the strains have demonstrated similar susceptibility to fluconazole, caspofungin, voriconazole, cetoconazole and 5-flucytosine. Only one strain of C. parapsilosis was resistant to amphotericin B. Regarding itraconazole, 66.6 and 43.9 % isolates of C. metapsilosis and C. parapsilosis, respectively, have demonstrated to be susceptible dose-dependent, with one isolate of the latter species resistant to the drug. Candida parapsilosis sensu stricto has demonstrated to be the less susceptible, mainly to amphotericin B, caspofungin and “azoles” such as fluconazole. Therefore, C. metapsilosis and C. orthopsilosis are still involved in a restricted number of infections, but these data have become essential for there are very few studies of these species in Latin America.     

Predictors of Condom Use among Peer Social Networks of Men Who Have Sex with Men in Ghana,West Africa

Ghanaian men who have sex with men (MSM) have high rates of HIV infection. A first step in designing culturally relevant prevention interventions for MSM in Ghana is to understand the influence that peer social networks have on their attitudes and behaviors. We aimed to examine whether, in a sample of Ghanaian MSM, mean scores on psychosocial variables theorized to influence HIV/STI risk differed between peer social networks and to examine whether these variables were associated with condom use. We conducted a formative, cross-sectional survey with 22 peer social networks of MSM (n = 137) in Ghana. We assessed basic psychological-needs satisfaction, HIV/STI knowledge, sense of community, HIV and gender non-conformity stigmas, gender equitable norms, sexual behavior and condom use. Data were analyzed using analysis of variance, generalized estimating equations, and Wilcoxon two sample tests. All models were adjusted for age and income, ethnicity, education, housing and community of residence. Mean scores for all psychosocial variables differed significantly by social network. Men who reported experiencing more autonomy support by their healthcare providers had higher odds of condom use for anal (AOR = 3.29, p<0.01), oral (AOR = 5.06, p<0.01) and vaginal (AOR = 1.8, p<0.05) sex. Those with a stronger sense of community also had higher odds of condom use for anal sex (AOR = 1.26, p<0.001). Compared to networks with low prevalence of consistent condom users, networks with higher prevalence of consistent condom users had higher STD and HIV knowledge, had norms that were more supportive of gender equity, and experienced more autonomy support in their healthcare encounters. Healthcare providers and peer social networks can have an important influence on safer-sex behaviors in Ghanaian MSM. More research with Ghanaian MSM is needed that considers knowledge, attitudes, and norms of their social networks in the development and implementation of culturally relevant HIV/STI prevention intervention strategies.     

Complexity of agonist- and cyclic AMP-mediated downregulation of the human beta 1-adrenergic receptor: role of internalization,degradation, and mRNA destabilization

Prolonged agonist exposure often induces downregulation of G protein-coupled receptors (GPCRs). Although downregulation of the prototypical beta(2)-adrenergic receptor (beta(2)AR) has been extensively studied, the underlying mechanisms have yet to be resolved. As even less is known about the beta(1)-subtype, we investigated the downregulation of human beta(1)AR stably expressed in Chinese hamster fibroblasts in response to the agonist isoproterenol or the cell-permeable, chlorophenylthio-cAMP (CPT-cAMP). While either effector mediated decreases in both beta(1)AR binding activity and steady-state beta(1)AR mRNA levels, there were significant differences in their actions. Whereas agonist-mediated downregulation of beta(1)AR followed first-order kinetics, that induced by CPT-cAMP was delayed for several hours and approximately 50% of the former. Furthermore, agonist but not CPT-cAMP induced beta(1)AR internalization, and inhibiting internalization also suppressed agonist-mediated downregulation. The latter, however, was more sensitive than the former to agonist concentration (EC(50) of 0.3 vs 48 nM). Thus, at < or =1 nM agonist, downregulation occurred without internalization and with a pattern similar to that mediated by CPT-cAMP. The amounts of beta(1)AR downregulated or internalized were proportional to initial receptor levels but reached saturation at approximately 2 and 3 pmol/mg of protein, respectively. The fate of beta(1)AR protein during downregulation was determined by immunoblotting with anti-C-terminal antibodies. In agonist-treated cells, beta(1)AR protein disappeared with time and without any immunoreactive degradation products. Agonist-mediated downregulation of the human beta(1)AR appears to be a complex process that consists of both agonist- and cAMP-specific components. The former involves both receptor internalization and degradation whereas the latter involves a reduction in receptor mRNA.     

The eukaryotic nucleotide excision repair pathway

Nucleotide excision repair (NER) is the most versatile mechanism of DNA repair, recognizing and dealing with a variety of helix-distorting lesions, such as the UV-induced photoproducts cyclobutane pyrimidine dimers (CPDs) and pyrimidine 6-4 pyrimidone photoproducts (6-4 PPs). In this review, we describe the main protein players and the different sequential steps of the eukaryotic NER mechanism in human cells, from lesion recognition to damage removal and DNA synthesis. Studies on the dynamics of protein access to the damaged site, and the kinetics of lesion removal contribute to the knowledge of how the cells respond to genetic insult. DNA lesions as well as NER factors themselves are also implicated in changes in cell metabolism, influencing cell cycle progression or arrest, apoptosis and genetic instability. These changes are related to increased mutagenesis and carcinogenesis. Finally, the recent collection of genomic data allows one to recognize the high conservation and the evolution of eukaryotic NER. The distribution of NER orthologues in different organisms, from archaea to the metazoa, displays challenging observations. Some of NER proteins are widespread in nature, probably representing ancient DNA repair proteins, which are candidates to participate in a primitive NER mechanism.