Novel mutation G324C in <Emphasis Type="Italic">WNT1</Emphasis> mapped in a large Pakistani family with severe recessively inherited <Emphasis Type="Italic">Osteogenesis Imperfecta</Emphasis>

Introduction

Osteogenesis imperfecta (OI) is a clinically and genetically heterogeneous disease with skeletal fragility and variable extra-skeletal manifestations. To date several point mutations in 18 different genes causing different types of OI have been identified. Mutations in WNT1 compromise activity of the osteoblasts leading to disturbed bone mass accrual, fragility fractures and progressive skeletal abnormalities. The present study was conducted to determine the underlying genetic cause of an autosomal recessive skeletal dysplasia in a large consanguineous family from Chinute, Pakistan.

Materials and methods

Blood was collected from 24 individuals of affected family along with clinical data. Homozygosity mapping was performed to confirm consanguinity. SNPs were identified, followed by whole exome and Sanger sequencing. In silico characterization of WNT1 mutation was performed using multiple platforms.

Results

Nine affected family members exhibited severe bone deformities, recurrent fractures, short stature and low bone mineral density. SNP array data revealed homozygous segments >?1 Mb in length accounting for 2.1–12.7% of the genome in affected individuals and their siblings and a single 6,344,821 bp homozygous region in all affected individuals on chromosome 12q12-q13. This region includes two potential OI candidate genes WNT1 and VDR. We did whole-exome sequencing for both genes in two patients and identified a novel damaging missense mutation in exon 4 of WNT1: c.1168G?>?T (NM_005430) resulting in p.G324C. Sanger sequencing confirmed segregation of mutation with the disease in family.

Conclusion

We report a novel mutation responsible for OI and our investigation expands the spectrum of disease-causing WNT1 mutations and the resulting OI phenotypes.

     

How does biodiversity conservation argumentation generate effects in policy cycles?

Arguments in the formulation, implementation and evaluation of biodiversity policy frame conservation in a range of ways and express interests that can be conflicting. Policy processes are cyclic and iterative by nature and as policies are constantly reformulated, argumentation has an important role at each policy stage. In this paper, we utilise the policy cycle model to shed light on biodiversity-related policy processes and the ways in which argumentation generates effects at different stages of these processes. The paper first draws on literature and the theory-driven assumptions are then illustrated with insights from four European case studies on different policy processes in which biodiversity conservation plays a role. The analysis shows that argumentation tends to evolve over the course of the policy cycle, and framing has a key role across the different policy stages. It is concluded that the ways in which arguments persist, accumulate, diffuse, and replace old arguments, should be the target of increased attention in policy analysis.     

Ecosystem state shifts during long‐term development of an Amazonian peatland

The most carbon (C)‐dense ecosystems of Amazonia are areas characterized by the presence of peatlands. However, Amazonian peatland ecosystems are poorly understood and are threatened by human activities. Here, we present an investigation into long‐term ecohydrological controls on C accumulation in an Amazonian peat dome. This site is the oldest peatland yet discovered in Amazonia (peat initiation ca. 8.9 ka BP), and developed in three stages: (i) peat initiated in an abandoned river channel with open water and aquatic plants; (ii) inundated forest swamp; and (iii) raised peat dome (since ca. 3.9 ka BP). Local burning occurred at least three times in the past 4,500 years. Two phases of particularly rapid C accumulation (ca. 6.6–6.1 and ca. 4.9–3.9 ka BP), potentially resulting from increased net primary productivity, were seemingly driven by drier conditions associated with widespread drought events. The association of drought phases with major ecosystem state shifts (open water wetland–forest swamp–peat dome) suggests a potential climatic control on the developmental trajectory of this tropical peatland. A third drought phase centred on ca. 1.8–1.1 ka BP led to markedly reduced C accumulation and potentially a hiatus during the peat dome stage. Our results suggest that future droughts may lead to phases of rapid C accumulation in some inundated tropical peat swamps, although this can lead ultimately to a shift to ombrotrophy and a subsequent return to slower C accumulation. Conversely, in ombrotrophic peat domes, droughts may lead to reduced C accumulation or even net loss of peat. Increased surface wetness at our site in recent decades may reflect a shift towards a wetter climate in western Amazonia. Amazonian peatlands represent important carbon stores and habitats, and are important archives of past climatic and ecological information. They should form key foci for conservation efforts.     

Contractility and structure of adult rat seminiferous tubules in organ culture

Summary Isolated pieces of seminiferous tubules of adult rats were grown in organ culture for up to 8 weeks in Petri dishes on the surface of nutrient agar. The medium consisted of newborn calf serum, Eagle's minimum essential medium, glutamate and antibiotics. This method allowed observation of the contractions of the seminiferous tubules in the culture. Contractility, light and electron microscopic structure and histochemically demonstrable activities of alkaline phosphatase and ATPase of the tubule walls were studied at 1-week intervals. The contractility and alkaline phosphatase activity were maintained in the tubule wall for 3 weeks, and the activity of ATPase was maintained for 5 weeks. The thin filaments of the myoid cells, which are responsible for the contractility, were seen with the electron microscope in tubules cultured for 5 weeks. The organ culture method described in the present paper seems to be valuable for studies concerning the functioning of the myoid cells of the seminiferous tubules and the possibility that this is regulated by hormones.     

Selection for population‐specific adaptation shaped patterns of variation in the photoperiod pathway genes in Arabidopsis lyrata during post‐glacial colonization

Spatially varying selection can lead to population‐specific adaptation, which is often recognized at the phenotypic level; however, the genetic evidence is weaker in many groups of organisms. In plants, environmental shifts that occur due to colonization of a novel environment may require adaptive changes in the timing of growth and flowering, which are often governed by location‐specific environmental cues such as day length. We studied locally varying selection in 19 flowering time loci in nine populations of the perennial herb Arabidopsis lyrata, which has a wide but patchy distribution in temperate and boreal regions of the northern hemisphere. The populations differ in their recent population demographic and colonization histories and current environmental conditions, especially in the growing season length. We searched for population‐specific molecular signatures of directional selection by comparing a set of candidate flowering time loci with a genomic reference set within each population using multiple approaches and contrasted the patterns of different populations. The candidate loci possessed approximately 20% of the diversity of the reference loci. On average the flowering time loci had more rare alleles (a smaller Tajima's D) and an excess of highly differentiated sites relative to the reference, suggesting positive selection. The strongest signal of selection was detected in photoperiodic pathway loci in the colonizing populations of Northwestern Europe, whereas no evidence of positive selection was detected in the Central European populations. These findings emphasized the population‐specific nature of selection and suggested that photoperiodic adaptation was important during postglacial colonization of the species.     

Natural variation in Arabidopsis lyrata vernalization requirement conferred by a FRIGIDA indel polymorphism

Species share homologous genes to a large extent, but it isnot yet known to what degree the same loci have been targetsfor natural selection in different species. Natural variationin flowering time is determined to a large degree by 2 genes,FLOWERING LOCUS C and FRIGIDA, in Arabidopsis thaliana. Here,we examine whether FRIGIDA has a role in differences in floweringtime between and within natural populations of Arabidopsis lyrata,a close outcrossing perennial relative of A. thaliana. We found2 FRIGIDA sequence variants producing potentially functionalproteins but with a length difference of 14 amino acids. Thesevariants conferred a 15-day difference in flowering time inan association experiment in 2 Scandinavian populations. Thedifference in flowering time between alleles was confirmed withtransformation to A. thaliana. Because the north European late-floweringpopulations harbor both late- and early sequence variants atintermediate frequencies and the late-flowering variant is mostfrequent in the southern early flowering European population,other genetic factors must be responsible for the floweringtime differences between the populations. The length polymorphismoccurs at high frequencies also in several North American populations.The occurrence of functional variants at intermediate frequenciesin several populations suggests that the variation may be maintainedby balancing selection. This is in contrast to A. thaliana,where independent loss-of-function mutations at the FRIGIDAgene are responsible for differences between populations andlocal adaptation.     

CD marker expression profiles of human embryonic stem cells and their neural derivatives,determined using flow-cytometric analysis,reveal a novel CD marker for exclusion of pluripotent stem cells

Human embryonic stem cells (hESCs) are pluripotent cells that can differentiate into neural cell lineages. These neural populations are usually heterogeneous and can contain undifferentiated pluripotent cells that are capable of producing teratomas in cell grafts. The characterization of surface protein profiles of hESCs and their neural derivatives is important to determine the specific markers that can be used to exclude undifferentiated cells from neural populations. In this study, we analyzed the cluster of differentiation (CD) marker expression profiles of seven undifferentiated hESC lines using flow-cytometric analysis and compared their profiles to those of neural derivatives. Stem cell and progenitor marker CD133 and epithelial adhesion molecule marker CD326 were more highly expressed in undifferentiated hESCs, whereas neural marker CD56 (NCAM) and neural precursor marker (chemokine receptor) CD184 were more highly expressed in hESC-derived neural cells. CD326 expression levels were consistently higher in all nondifferentiated hESC lines than in neural cell derivatives. In addition, CD326-positive hESCs produced teratomas in SCID mouse testes, whereas CD362-negative neural populations did not. Thus, CD326 may be useful as a novel marker of undifferentiated hESCs to exclude undifferentiated hESCs from differentiated neural cell populations prior to transplantation.     

1H, 13C and 15N resonance assignments of the major extracytoplasmic domain of the cell shape-determining protein MreC from Bacillus subtilis

MreB, MreC and MreD are essential cell shape-determining morphogenetic proteins in Gram-positive and in Gram-negative bacteria. While MreB, the bacterial homologue of the eukaryotic cytoskeletal protein actin, has been extensively studied, the roles of MreC and MreD are less well understood. They both are transmembrane proteins. MreC has a predicted single transmembrane domain and the C-terminal part outside the cell membrane. MreC probably functions as a link between the intracellular cytoskeleton and the cell wall synthesizing machinery which is located at the outer surface of the cell membrane. Also proteins involved in cell wall synthesis participate in cell morphogenesis. How these two processes are coordinated is, however, poorly understood. Bacillus subtilis (BS), a non-pathogenic Gram-positive bacterium, is widely used as a model for Gram-positive pathogens, e.g. Staphylococcus aureus (SA). Currently, the structures of MreC from BS and SA are not known. As part of our efforts to elucidate the structure–function relationships of the morphogenetic protein complexes in Gram-positive bacteria, we present the backbone and side chain resonance assignments of the extracytoplasmic domain of MreC from BS.