Bovine trophoblastic cell vesicle attachment to polarized endometrial epithelial cells in vitro

Summary Interactions between bovine trophoblastic cell vesicles and bovine endometrial epithelial cells were investigated by light and electron microscopy and lectin histochemistry in a cell culture model of early blastocyst attachment. Primary lines of bovine endometrial epithelial cells were polarized by subculturing on substrata and maintaining cultures at the air-medium interface. Trophoblastic cell vesicles were obtained from elongated Day 14 blastocysts. In co-cultures, trophoblastic cell vesicles adhered to endometrial epithelial cells through microvillus interdigitation and formation of primitive membrane junctional complexes. After 3 d in co-culture, a multilayered cellular plaque formed at the trophoblastic cell-endometrial epithelial cell interface. The type of cells contributing to this local proliferative response could not be identified specifically as trophoblastic or endometrial cells, and areas of membrane fusion between cells were noted. Ultrastructural features of vesicle adhesion in cultures were similar to features of conceptus attachment in vivo. Lectins bound to apical membranes of trophoblastic cells and endometrial epithelial cells in all locations except contact sites between vesicles and endometrial cells. These findings suggest that local cellular proliferation and membrane fusion between trophoblastic and endometrial epithelial cells may be early events in conceptus implantation in the cow and these events can be reproduced in culture. This work was supported by a grant from U.S. Department of Agriculture Animal Health and Disease Program, Washington, DC.     

An engineered human IgG1 antibody with longer serum half-life

The serum half-life of IgG Abs is regulated by the neonatal Fc receptor (FcRn). By binding to FcRn in endosomes, IgG Abs are salvaged from lysosomal degradation and recycled to the circulation. Several studies have demonstrated a correlation between the binding affinity of IgG Abs to FcRn and their serum half-lives in mice, including engineered Ab fragments with longer serum half-lives. Our recent study extended this correlation to human IgG2 Ab variants in primates. In the current study, several human IgG1 mutants with increased binding affinity to human FcRn at pH 6.0 were generated that retained pH-dependent release. A pharmacokinetics study in rhesus monkeys of one of the IgG1 variants indicated that its serum half-life was approximately 2.5-fold longer than the wild-type Ab. Ag binding was unaffected by the Fc mutations, while several effector functions appeared to be minimally altered. These properties suggest that engineered Abs with longer serum half-lives may prove to be effective therapeutics in humans.     

Soil organic carbon stocks in estuarine and marine mangrove ecosystems are driven by nutrient colimitation of P and N

Mangroves play an important role in carbon sequestration, but soil organic carbon (SOC) stocks differ between marine and estuarine mangroves, suggesting differing processes and drivers of SOC accumulation. Here, we compared undegraded and degraded marine and estuarine mangroves in a regional approach across the Indonesian archipelago for their SOC stocks and evaluated possible drivers imposed by nutrient limitations along the land‐to‐sea gradients. SOC stocks in natural marine mangroves (271–572 Mg ha^?1 m^?1) were much higher than under estuarine mangroves (100–315 Mg ha^?1 m^?1) with a further decrease caused by degradation to 80–132 Mg ha^?1 m^?1. Soils differed in C/N ratio (marine: 29–64; estuarine: 9–28), δ¹⁵N (marine: ?0.6 to 0.7‰; estuarine: 2.5 to 7.2‰), and plant‐available P (marine: 2.3–6.3 mg kg^?1; estuarine: 0.16–1.8 mg kg^?1). We found N and P supply of sea‐oriented mangroves primarily met by dominating symbiotic N₂ fixation from air and P import from sea, while mangroves on the landward gradient increasingly covered their demand in N and P from allochthonous sources and SOM recycling. Pioneer plants favored by degradation further increased nutrient recycling from soil resulting in smaller SOC stocks in the topsoil. These processes explained the differences in SOC stocks along the land‐to‐sea gradient in each mangrove type as well as the SOC stock differences observed between estuarine and marine mangrove ecosystems. This first large‐scale evaluation of drivers of SOC stocks under mangroves thus suggests a continuum in mangrove functioning across scales and ecotypes and additionally provides viable proxies for carbon stock estimations in PES or REDD schemes.     

Polymorphism in NOD2, Crohn's disease, and susceptibility to pulmonary tuberculosis

The nucleotide oligomerization binding domain 2 gene (NOD2) encodes an intracellular receptor for bacterial components, which is expressed in monocytes and is associated with Crohn's Disease (CD). This finding, along with epidemiological evidence, supports a role for infection in the pathogenesis of CD. Speculation that mycobacteria are involved in CD led us to investigate NOD2 in susceptibility to tuberculosis (TB), a global public health problem caused by Mycobacterium tuberculosis. CD-associated NOD2 variants were absent in a case-control study of 640 Gambians, where CD is rare. Novel NOD2 promoter polymorphisms were identified but showed no association with TB in this African population sample.     

Genomic imbalances are confined to non-proliferating cells in paediatric patients with acute myeloid leukaemia and a normal or incomplete karyotype

Leukaemia is often associated with genetic alterations such as translocations, amplifications and deletions, and recurrent chromosome abnormalities are used as markers of diagnostic and prognostic relevance. However, a proportion of acute myeloid leukaemia (AML) cases have an apparently normal karyotype despite comprehensive cytogenetic analysis. Based on conventional cytogenetic analysis of banded chromosomes, we selected a series of 23 paediatric patients with acute myeloid leukaemia and performed whole genome array comparative genome hybridization (aCGH) using DNA samples derived from the same patients. Imbalances involving large chromosomal regions or entire chromosomes were detected by aCGH in seven of the patients studied. Results were validated by fluorescence in situ hybridization (FISH) to both interphase nuclei and metaphase chromosomes using appropriate bacterial artificial chromosome (BAC) probes. The majority of these copy number alterations (CNAs) were confirmed by FISH and found to localize to the interphase rather than metaphase nuclei. Furthermore, the proliferative states of the cells analyzed by FISH were tested by immunofluorescence using an antibody against the proliferation marker pKi67. Interestingly, these experiments showed that, in the vast majority of cases, the changes appeared to be confined to interphase nuclei in a non-proliferative status.     

Regulation of the xylan-degrading apparatus of Cellvibrio japonicus by a novel two-component system

The microbial degradation of lignocellulose biomass is not only an important biological process but is of increasing industrial significance in the bioenergy sector. The mechanism by which the plant cell wall, an insoluble composite structure, activates the extensive repertoire of microbial hydrolytic enzymes required to catalyze its degradation is poorly understood. Here we have used a transposon mutagenesis strategy to identify a genetic locus, consisting of two genes that modulate the expression of xylan side chain-degrading enzymes in the saprophytic bacterium Cellvibrio japonicus. Significantly, the locus encodes a two-component signaling system, designated AbfS (sensor histidine kinase) and AbfR (response regulator). The AbfR/S two-component system is required to activate the expression of the suite of enzymes that remove the numerous side chains from xylan, but not the xylanases that hydrolyze the beta1,4-linked xylose polymeric backbone of this polysaccharide. Studies on the recombinant sensor domain of AbfS (AbfS(SD)) showed that it bound to decorated xylans and arabinoxylo-oligosaccharides, but not to undecorated xylo-oligosaccharides or other plant structural polysaccharides/oligosaccharides. The crystal structure of AbfS(SD) was determined to a resolution of 2.6A(.) The overall fold of AbfS(SD) is that of a classical Per Arndt Sim domain with a central antiparallel four-stranded beta-sheet flanked by alpha-helices. Our data expand the number of molecules known to bind to the sensor domain of two-component histidine kinases to include complex carbohydrates. The biological rationale for a regulatory system that induces enzymes that remove the side chains of xylan, but not the hydrolases that cleave the backbone of the polysaccharide, is discussed.     

Genetic Connectivity among Populations of an Endangered Snake Species from Southeastern Australia (Hoplocephalus bungaroides, Elapidae)

For endangered species that persist as apparently isolated populations within a previously more extensive range, the degree of genetic exchange between those populations is critical to conservation and management. A lack of gene flow can exacerbate impacts of threatening processes and delay or prevent colonization of sites after local extirpation. The broad-headed snake, Hoplocephalus bungaroides, is a small venomous species restricted to a handful of disjunct reserves near Sydney, Australia. Mark-recapture studies have indicated low vagility for this ambush predator, suggesting that gene flow also may be low. However, our analyses of 11 microsatellite loci from 163 snakes collected in Morton National Park, from six sites within a 10-km diameter, suggest relatively high rates of gene flow among sites. Most populations exchange genes with each other, with one large population serving as a source area and smaller populations apparently acting as sinks. About half of the juvenile snakes, for which we could reliably infer parentage, were collected from populations other than those in which we collected their putative parents. As expected from the snakes' reliance on rocky outcrops during cooler months of the year, most gene flow appears to be along sandstone plateaux rather than across the densely forested valleys that separate plateaux. The unexpectedly high rates of gene flow on a landscape scale are encouraging for future conservation of this endangered taxon. For example, wildlife managers could conserve broad-headed snakes by restoring habitats near extant source populations in areas predicted to be least affected by future climate change.