Dwarfism with joint laxity in Friesian horses is associated with a splice site mutation in B4GALT7

Background: Inbreeding and population bottlenecks in the ancestry of Friesian horses has led to health issues such as dwarfism. The limbs of dwarfs are short and the ribs are protruding inwards at the costochondral junction, while the head and back appear normal. A striking feature of the condition is the flexor tendon laxity that leads to hyperextension of the fetlock joints. The growth plates of dwarfs display disorganized and thickened chondrocyte columns. The aim of this study was to identify the gene defect that causes the recessively inherited trait in Friesian horses to understand the disease process at the molecular level. Results: We have localized the genetic cause of the dwarfism phenotype by a genome wide approach to a 3 Mb region on the p-arm of equine chromosome 14. The DNA of two dwarfs and one control Friesian horse was sequenced completely and we identified the missense mutation ECA14:g.4535550C> T that cosegregated with the phenotype in all Friesians analyzed. The mutation leads to the amino acid substitution p.(Arg17Lys) of xylosylprotein beta 1,4-galactosyltransferase 7 encoded by B4GALT7. The protein is one of the enzymes that synthesize the tetrasaccharide linker between protein and glycosaminoglycan moieties of proteoglycans of the extracellular matrix. The mutation not only affects a conserved arginine codon but also the last nucleotide of the first exon of the gene and we show that it impedes splicing of the primary transcript in cultured fibroblasts from a heterozygous horse. As a result, the level of B4GALT7 mRNA in fibroblasts from a dwarf is only 2 % compared to normal levels. Mutations in B4GALT7 in humans are associated with Ehlers-Danlos syndrome progeroid type 1 and Larsen of Reunion Island syndrome. Growth retardation and ligamentous laxity are common manifestations of these syndromes. Conclusions: We suggest that the identified mutation of equine B4GALT7 leads to the typical dwarfism phenotype in Friesian horses due to deficient splicing of transcripts of the gene. The mutated gene implicates the extracellular matrix in the regular organization of chrondrocyte columns of the growth plate. Conservation of individual amino acids may not be necessary at the protein level but instead may reflect underlying conservation of nucleotide sequence that are required for efficient splicing

Inferring stabilizing mutations from protein phylogenies : application to influenza hemagglutinin

One selection pressure shaping sequence evolution is the requirement that a protein fold with sufficient stability to perform its biological functions. We present a conceptual framework that explains how this requirement causes the probability that a particular amino acid mutation is fixed during evolution to depend on its effect on protein stability. We mathematically formalize this framework to develop a Bayesian approach for inferring the stability effects of individual mutations from homologous protein sequences of known phylogeny. This approach is able to predict published experimentally measured mutational stability effects (ΔΔG values) with an accuracy that exceeds both a state-of-the-art physicochemical modeling program and the sequence-based consensus approach. As a further test, we use our phylogenetic inference approach to predict stabilizing mutations to influenza hemagglutinin. We introduce these mutations into a temperature-sensitive influenza virus with a defect in its hemagglutinin gene and experimentally demonstrate that some of the mutations allow the virus to grow at higher temperatures. Our work therefore describes a powerful new approach for predicting stabilizing mutations that can be successfully applied even to large, complex proteins such as hemagglutinin. This approach also makes a mathematical link between phylogenetics and experimentally measurable protein properties, potentially paving the way for more accurate analyses of molecular evolution

Mental fatigue after very severe closed head injury: Sustained performance, mental effort, and distress at two levels of work-load in a driving simulator

In patients with very severe closed head injury (CHI), returning to work is often problematic. The present study focuses on a persistent complaint of these patients, viz. mental fatigue. To study this, the effect of sustained workload is assessed in a continuous dynamic divided attention task. Three types of measures are employed: performance loss with time-on-task, and subjective reports and cardiovascular measures of mental effort and distress. Eight very severe CHI patients (mean post-traumatic amnesia duration 51 days, mean age 23 years, (SD 6.4) and eight hospital controls (mean age 29 years, (SD 5.9) were tested. No differences were found between the patients and controls in the effects of task load on performance and the amount of mental effort, even in very demanding simulated work conditions. This parallels previous findings in less demanding laboratory tasks of sustained attention. Effects of CHI were found on both subjective and physiological indicators of distress. Compared to the controls, patients showed stronger effects on systolic blood pressure and subjectively experienced load

Similar adverse pregnancy outcome in native and nonnative dutch women with pregestational type 2 diabetes:a multicentre retrospective study

Objective. To assess the incidence of adverse pregnancy outcome in native and nonnative Dutch women with pregestational type 2 diabetes (T2D) in a multicenter study in The Netherlands. Methods. Maternal characteristics and pregnancy outcome were retrospectively reviewed and the influence of ethnicity on outcome was evaluated using independent t-test, Mann-Whitney U-test, and chi-square test. Results. 272 pregnant women (80 native and 192 non-native Dutch) with pregestational T2D were included. Overall outcome was unfavourable, with a perinatal mortality of 4.8%, major congenital malformations of 6.3%, preeclampsia of 11%, preterm birth of 19%, birth weight >90th percentile of 32%, and a Caesarean section rate of 42%. In nonnative Dutch women, the glycemic control was slightly poorer and the gestational age at booking somewhat later as compared to native Dutch women. However, there were no differences in incidence of preeclampsia/HELLP, preterm birth, perinatal mortality, macrosomia, and congenital malformations between those two groups. Conclusions. A high incidence of adverse pregnancy outcomes was found in women with pregestational T2D, although the outcome was comparable between native and non-native Dutch women. This suggests that easy access to and adequate participation in the local health care systems contribute to these comparable outcomes, offsetting potential disadvantages in the non-native group

Programmable Ligand Detection System in Plants through a Synthetic Signal Transduction Pathway

There is an unmet need to monitor human and natural environments for substances that are intentionally or unintentionally introduced. A long-sought goal is to adapt plants to sense and respond to specific substances for use as environmental monitors. Computationally re-designed periplasmic binding proteins (PBPs) provide a means to design highly sensitive and specific ligand sensing capabilities in receptors. Input from these proteins can be linked to gene expression through histidine kinase (HK) mediated signaling. Components of HK signaling systems are evolutionarily conserved between bacteria and plants. We previously reported that in response to cytokinin-mediated HK activation in plants, the bacterial response regulator PhoB translocates to the nucleus and activates transcription. Also, we previously described a plant visual response system, the de-greening circuit, a threshold sensitive reporter system that produces a visual response which is remotely detectable and quantifiable.We describe assembly and function of a complete synthetic signal transduction pathway in plants that links input from computationally re-designed PBPs to a visual response. To sense extracellular ligands, we targeted the computational re-designed PBPs to the apoplast. PBPs bind the ligand and develop affinity for the extracellular domain of a chemotactic protein, Trg. We experimentally developed Trg fusions proteins, which bind the ligand-PBP complex, and activate intracellular PhoR, the HK cognate of PhoB. We then adapted Trg-PhoR fusions for function in plants showing that in the presence of an external ligand PhoB translocates to the nucleus and activates transcription. We linked this input to the de-greening circuit creating a detector plant.Our system is modular and PBPs can theoretically be designed to bind most small molecules. Hence our system, with improvements, may allow plants to serve as a simple and inexpensive means to monitor human surroundings for substances such as pollutants, explosives, or chemical agents