Cryptosporidium parvum and Cryptosporidium hominis are two related species of apicomplexan protozoa responsible for the majority of human cases of cryptosporidiosis. In spite of their considerable public health impact, little is known about the population structures of these species. In this study, a battery of C. parvum and C. hominis isolates from seven countries was genotyped using a nine-locus DNA subtyping scheme. To assess the existence of geographical partitions, the multilocus genotype data were mined using a cluster analysis based on the nearest-neighbor principle. Within each country, the population genetic structures were explored by combining diversity statistical tests, linkage disequilibrium, and eBURST analysis. For both parasite species, a quasi-complete phylogenetic segregation was observed among the countries. Cluster analysis accurately identified recently introduced isolates. Rather than conforming to a strict paradigm of either a clonal or a panmictic population structure, data are consistent with a flexible reproductive strategy characterized by the cooccurrence of both propagation patterns. The relative contribution of each pattern appears to vary between the regions, perhaps dependent on the prevailing ecological determinants of transmission.
An emerging strategy for controlling porosity in disordered materials is to employ a removable template during synthesis. We present here a theoretical description of adsorption in a templated porous material modeled as a collection of particles formed by an equilibrium quench of a binary mixture of matrix and template particles and subsequent removal of the template component. We show, using the replica method, that an adsorbed phase in the templated material is just the s=0 limit of a special s+2 component replica system. We present a set of Ornstein–Zernike equations relating the correlation functions of the matrix, template, and adsorbate components, solve these equations for the case of hard sphere interactions within the Percus–Yevick closure, and evaluate the system thermodynamics via the compressibility route. We also present a grand canonical Monte Carlo simulation of this model system and find good agreement between theory and simulation. We show that for systems of constant matrix+template volume fraction, templating always enhances adsorption and this enhancement is most pronounced when the template/matrix ratio is low and/or the template size is small.
Rab38 is a rat Hermansky-Pudlak syndrome gene that plays an important role in surfactant homeostasis in alveolar type II (ATII) pneumocytes. We examined Rab38 function in regulating lamellar body (LB) morphology in ATII cells. Quantitative electron microscopy revealed that LBs in ATII cells were ∼77% larger in Rab38-null fawn-hooded hypertension (FHH) than control Sprague-Dawley (SD) rats. Rab38 protein expression was restricted in lung epithelial cells but was not found in primary endothelial cells. In SD ATII cells, Rab38 protein level gradually declined during 5 days in culture. Importantly, endogenous Rab38 was present in LB fractions purified from SD rat lungs, and transiently expressed enhanced green fluorescent protein (EGFP)-tagged Rab38 labeled only the limiting membranes of a subpopulation (∼30%) of LBs in cultured ATII cells. This selective targeting was abolished by point mutations to EGFP-Rab38 and was not shared by Rab7 and Rab4b, which also function in the ATII cells. Using confocal microscopy, we established a method for quantitative evaluation of the enlarged LB phenotype temporally preserved in cultured FHH ATII cells. A direct causal relationship was established when the enlarged LB phenotype was reserved and then rescued by transiently reexpressed EGFP-Rab38 in cultured FHH ATII cells. This rescuing effect was associated with dynamic EGFP-Rab38 targeting to and on LB limiting membranes. We conclude that Rab38 plays an indispensible role in maintaining LB morphology and surfactant homeostasis in ATII pneumocytes.
A series of carbon-based binary single-atom catalysts of Fe and Ni coordinated by nitrogen are fabricated using a glucose-chelating method. Depending on the Ni/Fe content, they exhibit a wide-range of controllable CO/H 2 ratio from 0.14 to 10.86, which is meaningful to specific chemical processes. The durability of the catalyst is evaluated over an 8-hour period with no significant degradation of activity. The variation of the faradaic efficiency with Ni/Fe content is justified by density-functional-theory based calculation of the reaction barrier in both hydrogen evolution and CO 2 reduction reactions.
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