Autosomal-Recessive Hypophosphatemic Rickets Is Associated with an Inactivation Mutation in the ENPP1 Gene

Human disorders of phosphate (Pi) handling and hypophosphatemic rickets have been shown to result from mutations in PHEX, FGF23, and DMP1, presenting as X-linked recessive, autosomal-dominant, and autosomal-recessive patterns, respectively. We present the identification of an inactivating mutation in the ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) gene causing autosomal-recessive hypophosphatemic rickets (ARHR) with phosphaturia by positional cloning. ENPP1 generates inorganic pyrophosphate (PPi), an essential physiologic inhibitor of calcification, and previously described inactivating mutations in this gene were shown to cause aberrant ectopic calcification disorders, whereas no aberrant calcifications were present in our patients. Our surprising result suggests a different pathway involved in the generation of ARHR and possible additional functions for ENPP1.     

Novel cationic vesicle platform derived from vernonia oil for efficient delivery of DNA through plant cuticle membranes

Novel cationic amphiphilic compounds were prepared from vernonia oil, a natural epoxidized triglyceride, and studied with respect to vesicle formation, encapsulation of biomaterials such as DNA, and their physical stability and transport through isolated plant cuticle membranes. The amphiphiles studied were a single-headed compound III (a quaternary ammonium head group with two alkyl chains) and a triple-headed compound IV, which is essentially three molecules of compound III bound together through a glycerol moiety. Vesicles of the two amphiphiles, prepared by sonication in water and solutions of uranyl acetate or the herbicide 2,4-D (2,4-dichloropenoxy acetic acid), were examined by TEM, SEM, AFM, and confocal laser systems and had a spherical shape which encapsulated the solutes with diameters between 40 and 110 nm. Vesicles from amphiphile IV could be made large enough to encapsulate a condensed 5.2kb DNA plasmid (pJD328). Vesicles of amphiphile IV were also shown to pass intact across isolated plant cuticle membranes and the rate of delivery of encapsulated radio-labeled 2,4-D through isolated plant cuticle membranes obtained with these vesicles was clearly greater in comparison to liposomes prepared from dipalmitopyl phosphatidylcholine (DPPC) and the control, nonencapsulated 2,4-D. Vesicles from amphiphiles III and IV were found to be more stable than those of liposomes from DPPC. The data indicate the potential of vesicles prepared from the novel amphiphile IV to be a relatively efficient nano-scale delivery system to transport DNA and other bioactive agents through plant biological barriers. This scientific approach may open the way for further development of efficient in vivo plant transformation systems.     

A finite shell element for heart mitral valve leaflet mechanics, with large deformations and 3D constitutive material model

This paper presents a shell finite element formulation appropriate for simulating the heart valve leaflet mechanics, including three-dimensional (3D) stress and strain effects. A 4-node mixed-interpolation shell is formulated in convected coordinates. This shell model is made capable of handling arbitrary 3D material models by use of an algorithm that satisfies the shell stress assumption at every element integration point. A method for tracking the fiber direction is incorporated. The resulting shell element operates under the same conditions as a standard 4-node shell element with 5 degrees of freedom per node, but extends the modeling capabilities to handle large-deformation and anisotropic behavior.     

Autosomal recessive ichthyosis with hypotrichosis caused by a mutation in ST14, encoding type II transmembrane serine protease matriptase

In this article, we describe a novel autosomal recessive ichthyosis with hypotrichosis syndrome, characterized by congenital ichthyosis associated with abnormal hair. Using homozygosity mapping, we mapped the disease locus to 11q24.3-q25. We screened the ST14 gene, which encodes matriptase, since transplantation of skin from matriptase(-/-)-knockout mice onto adult athymic nude mice has been shown elsewhere to result in an ichthyosislike phenotype associated with almost complete absence of erupted pelage hairs. Mutation analysis revealed a missense mutation, G827R, in the highly conserved peptidase S1-S6 domain. Marked skin hyperkeratosis due to impaired degradation of the stratum corneum corneodesmosomes was observed in the affected individuals, which suggests that matriptase plays a significant role in epidermal desquamation.     

The geological record of a mid-Holocene marine storm in southwestern Spain

Integrated analysis of a 50-m long sedimentary core collected in the central part of the Odiel estuary (SW Atlantic coast of Spain) allows delineation of the main paleoenvironmental changes that occurred in this area during the Holocene. Eight sedimentary facies were deposited in the last ca. 9000 years BP, confirming a transgressive-regressive cycle that involves the transition from fluvial to salt marsh deposits with intermediate marine tidal deposits. A storm event is detected at ca. 5705 ¹⁴C years BP (mean calibrated age) with distinct lithostratigraphical, textural, geochemical, and palaeontological features.     

<Emphasis Type="Italic">Slc11a1</Emphasis> (<Emphasis Type="Italic">Nramp1</Emphasis>) alleles interact with acute inflammation loci to modulate wound-healing traits in mice

Lines of mice were obtained by selective breeding for maximum (AIRmax) or minimum (AIRmin) acute inflammation. They present distinct neutrophil influx and show frequency disequilibrium of the solute carrier family 11a member 1 (Slc11a1) alleles. This gene is involved in ion transport at the endosomes within macrophages and neutrophils, interfering in their activation. Homozygous AIRmax and AIRmin sublines for the Slc11a1 gene were produced to examine the interaction of this gene with the acute inflammatory loci. The present work investigated wound-healing traits in AIRmax and AIRmin mice, in F₁ and F₂ intercrosses, and in Slc11a1 sublines. Two-millimeter ear punches were made in the mice and hole closure was measured during 40 days. AIRmax mice demonstrated significant tissue repair while AIRmin mice did not. Significant differences between the responses of male and female mice were also observed. Wound-healing traits demonstrated a correlation with neutrophil influx in F₂ populations. AIRmax ^SS showed higher ear-wound closure than AIRmax ^RR mice, suggesting that the Slc11a1 S allele favored ear tissue repair. QTL analysis has detected two inflammatory loci modulating ear wound healing on chromosomes 1 and 14. These results suggest the involvement of the acute inflammation modifier QTL in the wound-healing phenotype.     

Flow cytometric identification and enumeration of photosynthetic sulfur bacteria and potential for ecophysiological studies at the single-cell level

We show the potential of flow cytometry as a fast tool for population identification and enumeration of photosynthetic sulfur bacteria. Purple (PSB) and green sulfur bacteria (GSB) oxidize hydrogen sulfide to elemental sulfur that can act as storage compound to be further oxidized to sulfate generating the reducing power required for growth. Both groups have different elemental sulfur allocation strategies: whereas PSB store elemental sulfur as intracellular inclusions, GSB allocate sulfur globules externally. We used well-characterized laboratory strains and complex natural photosynthetic populations developing in a sharply stratified meromictic lake to show that PSB and GSB could be detected, differentiated and enumerated in unstained samples using a blue laser-based flow cytometer. Variations in cell-specific pigment content and the dynamics of sulfur accumulation, both intra- and extracellularly, were also detected in flow cytometric plots as sulfur accumulation changed the light scatter characteristics of the cells. These data were used to show the potential for studies on the metabolic status and the rate of activity at the single-cell level. Flow cytometric identification and enumeration resulted in faster and more precise analyses than previous approaches, and may open the door to more complex ecophysiological experiments with photosynthetic sulfur bacteria in mixed cultures and natural environments.     

Human Rap1 modulates TRF2 attraction to telomeric DNA

More than two decades of genetic research have identified and assigned main biological functions of shelterin proteins that safeguard telomeres. However, a molecular mechanism of how each protein subunit contributes to the protecting function of the whole shelterin complex remains elusive. Human Repressor activator protein 1 (Rap1) forms a multifunctional complex with Telomeric Repeat binding Factor 2 (TRF2). Rap1–TRF2 complex is a critical part of shelterin as it suppresses homology-directed repair in Ku 70/80 heterodimer absence. To understand how Rap1 affects key functions of TRF2, we investigated full-length Rap1 binding to TRF2 and Rap1–TRF2 complex interactions with double-stranded DNA by quantitative biochemical approaches. We observed that Rap1 reduces the overall DNA duplex binding affinity of TRF2 but increases the selectivity of TRF2 to telomeric DNA. Additionally, we observed that Rap1 induces a partial release of TRF2 from DNA duplex. The improved TRF2 selectivity to telomeric DNA is caused by less pronounced electrostatic attractions between TRF2 and DNA in Rap1 presence. Thus, Rap1 prompts more accurate and selective TRF2 recognition of telomeric DNA and TRF2 localization on single/double-strand DNA junctions. These quantitative functional studies contribute to the understanding of the selective recognition of telomeric DNA by the whole shelterin complex.     

Abundant Trimethylornithine Lipids and Specific Gene Sequences Are Indicative of Planctomycete Importance at the Oxic/Anoxic Interface in Sphagnum-Dominated Northern Wetlands

Northern wetlands make up a substantial terrestrial carbon sink and are often dominated by decay-resistant Sphagnum mosses. Recent studies have shown that planctomycetes appear to be involved in degradation of Sphagnum-derived debris. Novel trimethylornithine (TMO) lipids have recently been characterized as abundant lipids in various Sphagnum wetland planctomycete isolates, but their occurrence in the environment has not yet been confirmed. We applied a combined intact polar lipid (IPL) and molecular analysis of peat cores collected from two northern wetlands (Saxnäs Mosse [Sweden] and Obukhovskoye [Russia]) in order to investigate the preferred niche and abundance of TMO-producing planctomycetes. TMOs were present throughout the profiles of Sphagnum bogs, but their concentration peaked at the oxic/anoxic interface, which coincided with a maximum abundance of planctomycete-specific 16S rRNA gene sequences. The sequences detected at the oxic/anoxic interface were affiliated with the Isosphaera group, while sequences present in the anoxic peat layers were related to an uncultured planctomycete group. Pyrosequencing-based analysis identified Planctomycetes as the major bacterial group at the oxic/anoxic interface at the Obukhovskoye peat (54% of total 16S rRNA gene sequence reads), followed by Acidobacteria (19% reads), while in the Saxnäs Mosse peat, Acidobacteria were dominant (46%), and Planctomycetes contributed to 6% of the total reads. The detection of abundant TMO lipids in planctomycetes isolated from peat bogs and the lack of TMO production by cultures of acidobacteria suggest that planctomycetes are the producers of TMOs in peat bogs. The higher accumulation of TMOs at the oxic/anoxic interface and the change in the planctomycete community with depth suggest that these IPLs could be synthesized as a response to changing redox conditions at the oxic/anoxic interface.     

Measured voluntary avoidance behaviour during the 2009 A/H1N1 epidemic

Managing infectious disease is among the foremost challenges for public health policy. Interpersonal contacts play a critical role in infectious disease transmission, and recent advances in epidemiological theory suggest a central role for adaptive human behaviour with respect to changing contact patterns. However, theoretical studies cannot answer the following question: are individual responses to disease of sufficient magnitude to shape epidemiological dynamics and infectious disease risk? We provide empirical evidence that Americans voluntarily reduced their time spent in public places during the 2009 A/H1N1 swine flu, and that these behavioural shifts were of a magnitude capable of reducing the total number of cases. We simulate 10 years of epidemics (2003–2012) based on mixing patterns derived from individual time-use data to show that the mixing patterns in 2009 yield the lowest number of total infections relative to if the epidemic had occurred in any of the other nine years. The World Health Organization and other public health bodies have emphasized an important role for ‘distancing’ or non-pharmaceutical interventions. Our empirical results suggest that neglect for voluntary avoidance behaviour in epidemic models may overestimate the public health benefits of public social distancing policies.