The Arabidopsis thaliana aquaporin AtPIP1;2 is a physiologically relevant CO₂ transport facilitator

Cellular exchange of carbon dioxide (CO₂) is of extraordinary importance for life. Despite this significance, its molecular mechanisms are still unclear and a matter of controversy. In contrast to other living organisms, plants are physiologically limited by the availability of CO₂. In most plants, net photosynthesis is directly dependent on CO₂ diffusion from the atmosphere to the chloroplast. Thus, it is important to analyze CO₂ transport with regards to its effect on photosynthesis. A mutation of the Arabidopsis thaliana AtPIP1;2 gene, which was characterized as a non‐water transporting but CO₂ transport‐facilitating aquaporin in heterologous expression systems, correlated with a reduction in photosynthesis under a wide range of atmospheric CO₂ concentrations. Here, we could demonstrate that the effect was caused by reduced CO₂ conductivity in leaf tissue. It is concluded that the AtPIP1;2 gene product limits CO₂ diffusion and photosynthesis in leaves.     

Yeast 3-phosphoinositide-dependent protein kinase-1 (PDK1) orthologs Pkh1-3 differentially regulate phosphorylation of protein kinase A (PKA) and the protein kinase B (PKB)/S6K ortholog Sch9

Pkh1, -2, and -3 are the yeast orthologs of mammalian 3-phosphoinositide-dependent protein kinase-1 (PDK1). Although essential for viability, their functioning remains poorly understood. Sch9, the yeast protein kinase B and/or S6K ortholog, has been identified as one of their targets. We now have shown that in vitro interaction of Pkh1 and Sch9 depends on the hydrophobic PDK1-interacting fragment pocket in Pkh1 and requires the complementary hydrophobic motif in Sch9. We demonstrated that Pkh1 phosphorylates Sch9 both in vitro and in vivo on its PDK1 site and that this phosphorylation is essential for a wild type cell size. In vivo phosphorylation on this site disappeared during nitrogen deprivation and rapidly increased again upon nitrogen resupplementation. In addition, we have shown here for the first time that the PDK1 site in protein kinase A is phosphorylated by Pkh1 in vitro, that this phosphorylation is Pkh-dependent in vivo and occurs during or shortly after synthesis of the protein kinase A catalytic subunits. Mutagenesis of the PDK1 site in Tpk1 abolished binding of the regulatory subunit and cAMP dependence. As opposed to PDK1 site phosphorylation of Sch9, phosphorylation of the PDK1 site in Tpk1 was not regulated by nitrogen availability. These results bring new insight into the control and prevalence of PDK1 site phosphorylation in yeast by Pkh protein kinases.     

L-type Calcium Channel Cav1.2 Is Required for Maintenance of Auditory Brainstem Nuclei

Ca_v1.2 and Ca_v1.3 are the major L-type voltage-gated Ca²⁺ channels in the CNS. Yet, their individual in vivo functions are largely unknown. Both channel subunits are expressed in the auditory brainstem, where Ca_v1.3 is essential for proper maturation. Here, we investigated the role of Ca_v1.2 by targeted deletion in the mouse embryonic auditory brainstem. Similar to Ca_v1.3, loss of Ca_v1.2 resulted in a significant decrease in the volume and cell number of auditory nuclei. Contrary to the deletion of Ca_v1.3, the action potentials of lateral superior olive (LSO) neurons were narrower compared with controls, whereas the firing behavior and neurotransmission appeared unchanged. Furthermore, auditory brainstem responses were nearly normal in mice lacking Ca_v1.2. Perineuronal nets were also unaffected. The medial nucleus of the trapezoid body underwent a rapid cell loss between postnatal days P0 and P4, shortly after circuit formation. Phosphorylated cAMP response element-binding protein (CREB), nuclear NFATc4, and the expression levels of p75NTR, Fas, and FasL did not correlate with cell death. These data demonstrate for the first time that both Ca_v1.2 and Ca_v1.3 are necessary for neuronal survival but are differentially required for the biophysical properties of neurons. Thus, they perform common as well as distinct functions in the same tissue.     

Hydrocarbons,Pb-Concentrations,and Pb-Isotope Ratios in Contaminated Alluvial Soils (Southern Québec,Canada)

Hydrocarbon-contaminated layers found over 100 kilometers of riverbanks (southern Québec) were investigated. Analytical results for hydrocarbons, trace metals, Pb concentrations, and Pb isotopic signatures (²⁰⁶Pb/²⁰⁷Pb, ²⁰⁸Pb/²⁰⁶Pb, ²⁰⁴Pb/²⁰⁶Pb) of contaminated soil are presented. Soil samples show hydrocarbon concentrations (C₁₀-C₅₀) ranging from <60 to 660 mg kg^?1. Higher concentrations were found in the Richmond site (southern Québec). The values for Pb-concentrations ranged between 7 and 149 mg kg^?1 with median value of 23 mg kg^?1. For the Pb isotope ratios, the values obtained in the hydrocarbon layer range from 1.124 to 1.175 ± 0.011 (²⁰⁶Pb/²⁰⁷Pb), 2.085 to 2.126 ± 0.011 (²⁰⁸Pb/²⁰⁶Pb), and 0.054 to 0.057 ± 0.000 (²⁰⁴Pb/²⁰⁶Pb). The combination of various techniques used allows us to distinguish the various sources of contaminants. The study also reveals that Pb and other trace metal elements continue to be found in the fluvial environment, even after many years, and this soil pollution could affect the quality of streams and living organisms.     

Genomic prediction based on runs of homozygosity

Background

Genomic prediction is based on the accurate estimation of the genomic relationships among and between training animals and selection candidates in order to obtain accurate estimates of the genomic estimated breeding values (GEBV). Various methods have been used to predict GEBV based on population-wide linkage disequilibrium relationships (G_IBS) or sometimes on linkage analysis relationships (G_LA). Here, we propose a novel method to predict GEBV based on a genomic relationship matrix using runs of homozygosity (G_ROH). Runs of homozygosity were used to derive probabilities of multi-locus identity by descent chromosome segments. The accuracy and bias of the prediction of GEBV using G_ROH were compared to those using G_IBS and G_LA. Comparisons were performed using simulated datasets derived from a random pedigree and a real pedigree of Italian Brown Swiss bulls. The comparison of accuracies of GEBV was also performed on data from 1086 Italian Brown Swiss dairy cattle.

Results

Simulations with various thresholds of minor allele frequency for markers and quantitative trait loci showed that G_ROH achieved consistently more accurate GEBV (0 to 4% points higher) than G_IBS and G_LA. The bias of GEBV prediction for simulated data was higher based on the real pedigree than based on a random pedigree. In the analyses with real data, G_ROH and G_LA had similar accuracies. However, G_LA achieved a higher accuracy when the prediction was done on the youngest animals. The G_IBS matrices calculated with and without standardized marker genotypes resulted in similar accuracies.

Conclusions

The present study proposes G_ROH as a novel method to estimate genomic relationship matrices and predict GEBV based on runs of homozygosity and shows that it can result in higher or similar accuracies of GEBV prediction than G_LA, except for the real data analysis with validation of young animals. Compared to G_IBS, G_ROH resulted in more accurate GEBV predictions.     

Self-Report of Healthcare Utilization among Community-Dwelling Older Persons: A Prospective Cohort Study

Background

Self-reported data are often used for estimates on healthcare utilization in cost-effectiveness studies.

Objective

To analyze older adults’ self-report of healthcare utilization compared to data obtained from the general practitioners’ (GP) electronic medical record (EMR) and to study the differences in healthcare utilization between those who completed the study, those who did not respond, and those lost to follow-up.

Methods

A prospective cohort study was conducted among community-dwelling persons aged 70 years and above, without dementia and not living in a nursing home. Self-reporting questionnaires were compared to healthcare utilization data extracted from the EMR at the GP-office.

Results

Overall, 790 persons completed questionnaires at baseline, median age 75 years (IQR 72–80), 55.8% had no disabilities in (instrumental) activities of daily living. Correlations between self-report data and EMR data on healthcare utilization were substantial for ‘hospitalizations’ and ‘GP home visits’ at 12 months intraclass correlation coefficient 0.63 (95% CI; 0.58–0.68). Compared to the EMR, self-reported healthcare utilization was generally slightly over-reported. Non-respondents received more GP home visits (p<0.05). Of the participants who died or were institutionalized 62.2% received 2 or more home visits (p<0.001) and 18.9% had 2 or more hospital admissions (p<0.001) versus respectively 18.6% and 3.9% of the participants who completed the study. Of the participants lost to follow-up for other reasons 33.0% received 2 or more home visits (p<0.01) versus 18.6 of the participants who completed the study.

Conclusions

Self-report of hospitalizations and GP home visits in a broadly ‘healthy’ community-dwelling older population seems adequate and efficient. However, as people become older and more functionally impaired, collecting healthcare utilization data from the EMR should be considered to avoid measurement bias, particularly if the data will be used to support economic evaluation.     

Lombards on the Move – An Integrative Study of the Migration Period Cemetery at Szólád,Hungary

In 2005 to 2007 45 skeletons of adults and subadults were excavated at the Lombard period cemetery at Szólád (6^th century A.D.), Hungary. Embedded into the well-recorded historical context, the article presents the results obtained by an integrative investigation including anthropological, molecular genetic and isotopic (δ¹⁵N, δ¹³C, ⁸⁷Sr/⁸⁶Sr) analyses. Skeletal stress markers as well as traces of interpersonal violence were found to occur frequently. The mitochondrial DNA profiles revealed a heterogeneous spectrum of lineages that belong to the haplogroups H, U, J, HV, T2, I, and K, which are common in present-day Europe and in the Near East, while N1a and N1b are today quite rare. Evidence of possible direct maternal kinship was identified in only three pairs of individuals. According to enamel strontium isotope ratios, at least 31% of the individuals died at a location other than their birthplace and/or had moved during childhood. Based on the peculiar ⁸⁷Sr/⁸⁶Sr ratio distribution between females, males, and subadults in comparison to local vegetation and soil samples, we propose a three-phase model of group movement. An initial patrilocal group with narrower male but wider female Sr isotope distribution settled at Szólád, whilst the majority of subadults represented in the cemetery yielded a distinct Sr isotope signature. Owing to the virtual absence of Szólád-born adults in the cemetery, we may conclude that the settlement was abandoned after approx. one generation. Population heterogeneity is furthermore supported by the carbon and nitrogen isotope data. They indicate that a group of high-ranking men had access to larger shares of animal-derived food whilst a few individuals consumed remarkable amounts of millet. The inferred dynamics of the burial community are in agreement with hypotheses of a highly mobile lifestyle during the Migration Period and a short-term occupation of Pannonia by Lombard settlers as conveyed by written sources.