Extracellular Water and Blood Pressure in Adults with Growth Hormone (GH) Deficiency: A Genotype-Phenotype Association Study

Objectives

Growth hormone deficiency (GHD) in adults is associated with decreased extracellular water volume (ECW). In response to GH replacement therapy (GHRT), ECW increases and blood pressure (BP) reduces or remains unchanged. Our primary aim was to study the association between polymorphisms in genes related to renal tubular function with ECW and BP before and 1 year after GHRT. The ECW measures using bioimpedance analysis (BIA) and bioimpedance spectroscopy (BIS) were validated against a reference method, the sodium bromide dilution method (Br⁻).

Design and Methods

Using a candidate gene approach, fifteen single-nucleotide polymorphisms (SNPs) in nine genes with known impact on renal tubular function (AGT, SCNN1A, SCNN1G, SLC12A1, SLC12A3, KCNJ1, STK39, WNK1 and CASR) were genotyped and analyzed for associations with ECW and BP at baseline and with their changes after 1 year of GHRT in 311 adult GHD patients. ECW was measured with the Br⁻, BIA, and BIS.

Results

Both BIA and BIS measurements demonstrated similar ECW results as the reference method. At baseline, after adjustment for sex and BMI, SNP rs2291340 in the SLC12A1 gene was associated with ECW volume in GHD patients (p = 0.039). None of the SNPs influenced the ECW response to GHRT. One SNP in the SLC12A3 gene (rs11643718; p = 0.024) and three SNPs in the SCNN1G gene [rs5723 (p = 0.02), rs5729 (p = 0.016) and rs13331086 (p = 0.035)] were associated with the inter-individual differences in BP levels at baseline. A polymorphism in the calcium-sensing receptor (CASR) gene (rs1965357) was associated with changes in systolic BP after GHRT (p = 0.036). None of these associations remained statistically significant when corrected for multiple testing.

Conclusion

The BIA and BIS are as accurate as Br⁻ to measure ECW in GHD adults before and during GHRT. Our study provides the first evidence that individual polymorphisms may have clinically relevant effects on ECW and BP in GHD adults.     

Variation in selection pressure acting on body size by age and sex in a reverse sexual size dimorphic raptor

Body size strongly influences fitness, with larger individuals benefiting in terms of both greater productivity and survivorship; for reverse sexual size dimorphic (RSD) species, this relationship may be more complex. We examined the selection pressures acting on body size in male and female Merlins Falco columbarius to assess whether larger or smaller individuals of this RSD species were favoured in terms of survival and breeding performance. For males and females there were clear links between body size and survival but the exact relationship varied by sex. Among males, birds that survived each year class were larger than those that died and yearlings were on average smaller than older birds, but there were no measurable differences among adult males (age 2+). Among females, larger individuals aged 1 and 2 years were more likely to survive, but this size‐based pattern was not apparent in older age classes. Size early in life predicted the lifespan in male Merlins but not as strongly as for females and not for the largest individuals. Reproductive performance based on brood size was not associated with body size in either males or females, but there was a weak positive relationship between female body size and lifetime reproductive success. Selection appears to favour larger males and females but there is no indication that the population is evolving towards bigger individuals, perhaps in part due to selection against the largest birds. Increased survival may allow larger and higher quality individuals to occupy higher quality territories as they age and thereby to accrue greater lifetime reproductive success in the process.     

Fitness components of Drosophila melanogaster developed on a standard laboratory diet or a typical natural food source

Drosophila melanogaster is often used as a model organism in evolutionary biology and ecophysiology to study evolutionary processes and their physiological mechanisms. Diets used to feed Drosophila cultures differ between laboratories and are often nutritious and distinct from food sources in the natural habitat. Here we rear D. melanogaster on a standard diet used in our laboratory and a field diet composed of decomposing apples collected in the field. Flies developed on these two diet compositions are tested for heat, cold, desiccation, and starvation resistance as well as developmental time, dry body mass and fat percentage. The nutritional compositions of the standard and field diets were analyzed, and discussed in relation to the phenotypic observations. Results showed marked differences in phenotype of flies from the two types of diets. Flies reared on the field diet are more starvation resistant and they are smaller, leaner, and have lower heat resistance compared to flies reared on the standard diet. Sex specific effects of diet type are observed for several of the investigated traits and the strong sexual dimorphism usually observed in desiccation resistance in D. melanogaster disappeared when rearing the flies on the field diet. Based on our results we conclude that care should be taken in extrapolating results from one type of diet to another and especially from laboratory to field diets.     

Phosphatidylinositol 3-phosphate is found in microdomains of early endosomes

Phosphatidylinositol 3-phosphate [PI(3)P] is a phosphatidylinositol 3-kinase product whose localisation is restricted to the limiting membranes of early endosomes and to the internal vesicles of multivesicular bodies. In this study the intracellular distribution of PI(3)P was compared with those of another phosphoinositide and a number of endosomal proteins. Using a 2xFYVE probe specific for PI(3)P we found that PI(3)P is present in microdomains within the endosome membrane, whereas a phosphoinositide required for clathrin-mediated endocytosis, PI(4,5)P₂, was only detected at the plasma membrane. The small GTPase Rab5 as well as the PI(3)P-binding proteins EEA1, SARA and CISK were found to be abundant within PI(3)P-containing endosomal microdomains. In contrast, another PI(3)P-binding protein, Hrs, was found concentrated in clathrin-coated endosomal microdomains with low levels of PI(3)P. While PI(3)P-containing microdomains could be readily distinguished on enlarged endosomes in cells transfected with a constitutively active Rab5 mutant, such domains could also be detected in endosomes of non-transfected cells. We conclude that the membranes of early endosomes consist of microdomains in which PI(3)P and specific proteins are concentrated. These microdomains may be necessary for the assembly of distinct multimolecular complexes that specify organelle identity, membrane trafficking and receptor signalling.David J. Gillooly and Camilla Raiborg contributed equally     

Utilisation of plant functional diversity in wildflower strips for the delivery of multiple agroecosystem services

Increased plant diversity in cropping systems can play an important role in agriculture by enhancing arthropod‐mediated ecosystem services, including biological control and pollination. However, there is limited research investigating the concurrent influence of plant functional diversity within cultivated systems on different arthropod functional groups, the provision of multiple ecosystem services, and crop yield. During a field experiment, repeated over 2 years, we measured the effect of increasing plant functional diversity on community structure of arthropod visitors, the abundance of multiple pests and induced crop damage, and fruit production in two varieties of tomato. Plant resources (floral and extra‐floral nectar and pollen) were included within experimental plots in four levels, with each level increasing the plant functional group richness, based on floral morphology and availability of resources, in a replacement series. The presence of sown flower mixtures in experimental plots was associated with increased abundance and diversity of natural enemy functional groups and an enhanced abundance of bees (Hymenoptera: Apiformes). However, we only detected relatively small variability in arthropod visitors among types of mixtures, and increased abundance of natural enemies did not translate into stronger pest suppression or reduced crop damage. Lepidoptera pest damage was significantly higher in plots adjacent to wildflower strips, an ecosystem disservice, but a significantly higher crop productivity was recorded from these plots. Our results provide evidence that inclusion of non‐crop plant resources in agroecosystems can improve the conservation of beneficial arthropods and may lead to increased crop productivity.     

Membrane remodeling by the PX-BAR protein SNX18 promotes autophagosome formation

The membrane remodeling events required for autophagosome biogenesis are still poorly understood. Because PX domain proteins mediate membrane remodeling and trafficking, we conducted an imaging-based siRNA screen for autophagosome formation targeting human PX proteins. The PX-BAR protein SNX18 was identified as a positive regulator of autophagosome formation, and its Drosophila melanogaster homologue SH3PX1 was found to be required for efficient autophagosome formation in the larval fat body. We show that SNX18 is required for recruitment of Atg16L1-positive recycling endosomes to a perinuclear area and for delivery of Atg16L1- and LC3-positive membranes to autophagosome precursors. We identify a direct interaction of SNX18 with LC3 and show that the pro-autophagic activity of SNX18 depends on its membrane binding and tubulation capacity. We also show that the function of SNX18 in membrane tubulation and autophagy is negatively regulated by phosphorylation of S233. We conclude that SNX18 promotes autophagosome formation by virtue of its ability to remodel membranes and provide membrane to forming autophagosomes.     

Transcriptome Analysis of Honeybee (Apis Mellifera) Haploid and Diploid Embryos Reveals Early Zygotic Transcription during Cleavage

In honeybees, the haplodiploid sex determination system promotes a unique embryogenesis process wherein females develop from fertilized eggs and males develop from unfertilized eggs. However, the developmental strategies of honeybees during early embryogenesis are virtually unknown. Similar to most animals, the honeybee oocytes are supplied with proteins and regulatory elements that support early embryogenesis. As the embryo develops, the zygotic genome is activated and zygotic products gradually replace the preloaded maternal material. The analysis of small RNA and mRNA libraries of mature oocytes and embryos originated from fertilized and unfertilized eggs has allowed us to explore the gene expression dynamics in the first steps of development and during the maternal-to-zygotic transition (MZT). We localized a short sequence motif identified as TAGteam motif and hypothesized to play a similar role in honeybees as in fruit flies, which includes the timing of early zygotic expression (MZT), a function sustained by the presence of the zelda ortholog, which is the main regulator of genome activation. Predicted microRNA (miRNA)-target interactions indicated that there were specific regulators of haploid and diploid embryonic development and an overlap of maternal and zygotic gene expression during the early steps of embryogenesis. Although a number of functions are highly conserved during the early steps of honeybee embryogenesis, the results showed that zygotic genome activation occurs earlier in honeybees than in Drosophila based on the presence of three primary miRNAs (pri-miRNAs) (ame-mir-375, ame-mir-34 and ame-mir-263b) during the cleavage stage in haploid and diploid embryonic development.     

Comparison of two versions of an EPD,using generic and specific data for the foreground system,and some methodological implications

Purpose

Differences in the practice of inclusion and the definition of specific and generic data when performing an LCA for an Environmental Product Declaration (EPD) may lead to incomparable EPDs. The purpose of this paper is to illuminate the importance of precise definitions regarding data quality in EPDs.

Method

The authors define relevant terminology before describing methodological differences between two versions of EPDs for an office chair. The analyses performed for one EPD use generic data for the foreground system, while the other uses specific data. Results for some impact categories as well as inventory findings are shown, and the reasons for differences are investigated and discussed.

Results

Relevant dilemmas are examined with regard to the choice of generic or specific data. These include practical hindrances and the promotion of environmental improvement. Some preliminary methodological and organisational implications are described, followed by an outline of further research.

Conclusions

This paper shows the substantial variations arising from using two datasets with different degrees of specificity, and concludes that they increase in relation to the distinctiveness of the process or material. This highlights the importance of EPD programmes in establishing precise, unambiguous definitions and vocabulary with regard to specific as against generic data, when combined with foreground and background processes. It is essential to take this into consideration so as to avoid misunderstandings or false agreement when discussing data quality. It is also necessary in order to avoid comparisons of products based on very different assumptions.

     

Probing concentration-dependent behavior of DNA-binding proteins on a single-molecule level illustrated by Rad51

Low throughput is an inherent problem associated with most single-molecule biophysical techniques. We have developed a versatile tool for high-throughput analysis of DNA and DNA-binding molecules by combining microfluidic and dense DNA arrays. We use an easy-to-process microfluidic flow channel system in which dense DNA arrays are prepared for simultaneous imaging of large amounts of DNA molecules with single-molecule resolution. The Y-shaped microfluidic design, where the two inlet channels can be controlled separately and precisely, enables the creation of a concentration gradient across the microfluidic channel as well as rapid and repeated addition and removal of substances from the measurement region. A DNA array stained with the fluorescent DNA-binding dye YOYO-1 in a gradient manner illustrates the method and serves as a proof of concept. We have applied the method to studies of the repair protein Rad51 and could directly probe the concentration-dependent DNA-binding behavior of human Rad51 (HsRad51). In the low-concentration regime used (100 nM HsRad51 and below), we detected binding to double-stranded DNA (dsDNA) without positive cooperativity.