Deriving respiratory cell types from stem cells

The reported pluripotential capabilities of many human stem cell types has made them an attractive area of research, given the belief they may hold considerable therapeutic potential for treating a wide range of human diseases and injuries. Although the bulk of stem cell based research has focused on developing procedures for the treatment of pancreatic, neural, cardiovascular and haematopoietic diseases, the potential for deriving respiratory cell types from stem cells for treatment of respiratory specific diseases has also been explored. It is suggested that stem cell derivatives may be used for lung replacement/regeneration therapeutics and high though-put pharmacological screening strategies for a variety of respiratory injuries and diseases including: cystic fibrosis, chronic obstructive pulmonary disease, respiratory distress syndrome, pulmonary fibrosis and pulmonary edema. This review will explore recent progress in characterizing adult respiratory and bone marrow derived stem cells with respiratory potential as well as the endogenous mechanisms directing the homing of these cells to the diseased and injured lung. In addition, the potential for embryonic stem cell based therapies in this domain as well as the histological, anatomical and molecular aspects of respiratory development will be summarized.     

Assessment and Clinical Utility of a Non-Next-Generation Sequencing-Based Non-Invasive Prenatal Testing Technology

Background: Rolling-circle replication (RCR) is a novel technology that has not been applied to cell-free DNA (cfDNA) testing until recently. Given the cost and simplicity advantages of this technology compared to other platforms currently used in cfDNA analysis, an assessment of RCR in clinical laboratories was performed. Here, we present the first validation study from clinical laboratories utilizing RCR technology. Methods: 831 samples from spontaneously pregnant women carrying a singleton fetus, and 25 synthetic samples, were analyzed for the fetal risk of trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13), by three laboratories on three continents. All the screen-positive pregnancies were provided post-test genetic counseling and confirmatory diagnostic invasive testing (e.g., amniocentesis). The screen-negative pregnancies were routinely evaluated at birth for fetal aneuploidies, using newborn examinations, and any suspected aneuploidies would have been offered diagnostic testing or confirmed with karyotyping. Results: The study found rolling-circle replication to be a highly viable technology for the clinical assessment of fetal aneuploidies, with 100% sensitivity for T21 (95% CI: 82.35–100.00%); 100.00% sensitivity for T18 (71.51–100.00%); and 100.00% sensitivity for T13 analyses (66.37–100.00%). The specificities were >99% for each trisomy (99.7% (99.01–99.97%) for T21; 99.5% (98.62–99.85%) for T18; 99.7% (99.03–99.97%) for T13), along with a first-pass no-call rate of 0.93%. Conclusions: The study showed that using a rolling-circle replication-based cfDNA system for the evaluation of the common aneuploidies would provide greater accuracy and clinical utility compared to conventional biochemical screening, and it would provide comparable results to other reported cfDNA methodologies.     

Superantigen-induced regulatory T cells display different suppressive functions in the presence or absence of natural CD4+CD25+ regulatory T cells in vivo

Repeated exposures to both microbial and innocuous Ags in vivo have been reported to both eliminate and tolerize T cells after their initial activation and expansion. The remaining tolerant T cells have been shown to suppress the response of naive T cells in vitro. This feature is reminiscent of natural CD4(+)CD25(+) regulatory T cells. However, it is not known whether the regulatory function of in vivo-tolerized T cells is similar to the function of natural CD4(+)CD25(+) regulatory T cells. In this study, we demonstrate that CD4(+)CD25(+) as well as CD4(+)CD25(-) T cells isolated from mice treated with superantigen three consecutive times to induce tolerance were functionally comparable to natural CD4(+)CD25(+) regulatory T cells, albeit more potent. The different subpopulations of in vivo-tolerized CD4(+) T cells efficiently down-modulated costimulatory molecules on dendritic cells, and their suppressive functions were strictly cell contact dependent. Importantly, we demonstrate that conventional CD4(+)CD25(-) T cells could also be induced to acquire regulatory functions by the same regimen in the absence of natural regulatory T cells in vivo, but that such regulatory cells were functionally different.     

Hydrogenases and Hydrogen Metabolism of Cyanobacteria

Cyanobacteria may possess several enzymes that are directly involved in dihydrogen metabolism: nitrogenase(s) catalyzing the production of hydrogen concomitantly with the reduction of dinitrogen to ammonia, an uptake hydrogenase (encoded by hupSL) catalyzing the consumption of hydrogen produced by the nitrogenase, and a bidirectional hydrogenase (encoded by hoxFUYH) which has the capacity to both take up and produce hydrogen. This review summarizes our knowledge about cyanobacterial hydrogenases, focusing on recent progress since the first molecular information was published in 1995. It presents the molecular knowledge about cyanobacterial hupSL and hoxFUYH, their corresponding gene products, and their accessory genes before finishing with an applied aspect—the use of cyanobacteria in a biological, renewable production of the future energy carrier molecular hydrogen. In addition to scientific publications, information from three cyanobacterial genomes, the unicellular Synechocystis strain PCC 6803 and the filamentous heterocystous Anabaena strain PCC 7120 and Nostoc punctiforme (PCC 73102/ATCC 29133) is included.     

Lactobacillus reuteri Prevents Diet-Induced Obesity,but not Atherosclerosis,in a Strain Dependent Fashion in Apoe?/? Mice

Objective

To investigate whether the specific strains of Lactobacillus reuteri modulates the metabolic syndrome in Apoe−/− mice.

Methods

8 week-old Apoe−/− mice were subdivided into four groups who received either L. reuteri ATCC PTA 4659 (ATCC), DSM 17938 (DSM), L6798, or no bacterial supplement in the drinking water for 12 weeks. The mice were fed a high-fat Western diet with 0.2% cholesterol and body weights were monitored weekly. At the end of the study, oral glucose and insulin tolerance tests were conducted. In addition, adipose and liver weights were recorded along with analyses of mRNA expression of ileal Angiopoietin-like protein 4 (Angptl4), the macrophage marker F4/80 encoded by the gene Emr1 and liver Acetyl-CoA carboxylase 1 (Acc1), Fatty acid synthase (Fas) and Carnitine palmitoyltransferase 1a (Cpt1a). Atherosclerosis was assessed in the aortic root region of the heart.

Results and Conclusions

Mice receiving L. reuteri ATCC gained significantly less body weight than the control mice, whereas the L6798 mice gained significantly more. Adipose and liver weights were also reduced in the ATCC group. Serum insulin levels were lower in the ATCC group, but no significant effects were observed in the glucose or insulin tolerance tests. Lipogenic genes in the liver were not altered by any of the bacterial treatments, however, increased expression of Cpt1a was found in the ATCC group, indicating increased β-oxidation. Correspondingly, the liver trended towards having lower fat content. There were no effects on inflammatory markers, blood cholesterol or atherosclerosis. In conclusion, the probiotic L. reuteri strain ATCC PTA 4659 partly prevented diet-induced obesity, possibly via a previously unknown mechanism of inducing liver expression of Cpt1a.     

The small RNA repertoire of Dictyostelium discoideum and its regulation by components of the RNAi pathway

Small RNAs play crucial roles in regulation of gene expression in many eukaryotes. Here, we report the cloning and characterization of 18–26 nt RNAs in the social amoeba Dictyostelium discoideum. This survey uncovered developmentally regulated microRNA candidates whose biogenesis, at least in one case, is dependent on a Dicer homolog, DrnB. Furthermore, we identified a large number of 21 nt RNAs originating from the DIRS-1 retrotransposon, clusters of which have been suggested to constitute centromeres. Small RNAs from another retrotransposon, Skipper, were significantly up-regulated in strains depleted of the second Dicer-like protein, DrnA, and a putative RNA-dependent RNA polymerase, RrpC. In contrast, the expression of DIRS-1 small RNAs was not altered in any of the analyzed strains. This suggests the presence of multiple RNAi pathways in D. discoideum. In addition, we isolated several small RNAs with antisense complementarity to mRNAs. Three of these mRNAs are developmentally regulated. Interestingly, all three corresponding genes express longer antisense RNAs from which the small RNAs may originate. In at least one case, the longer antisense RNA is complementary to the spliced but not the unspliced pre-mRNA, indicating synthesis by an RNA-dependent RNA polymerase.     

Heterotachy processes in rhodophyte-derived secondhand plastid genes: Implications for addressing the origin and evolution of dinoflagellate plastids

Serial transfer of plastids from one eukaryotic host to another is the key process involved in evolution of secondhand plastids. Such transfers drastically change the environment of the plastids and hence the selection regimes, presumably leading to changes over time in the characteristics of plastid gene evolution and to misleading phylogenetic inferences. About half of the dinoflagellate protists species are photosynthetic and unique in harboring a diversity of plastids acquired from a wide range of eukaryotic algae. They are therefore ideal for studying evolutionary processes of plastids gained through secondary and tertiary endosymbioses. In the light of these processes, we have evaluated the origin of 2 types of dinoflagellate plastids, containing the peridinin or 19'-hexanoyloxyfucoxanthin (19'-HNOF) pigments, by inferring the phylogeny using "covarion" evolutionary models allowing the pattern of among-site rate variation to change over time. Our investigations of genes from secondary and tertiary plastids derived from the rhodophyte plastid lineage clearly reveal "heterotachy" processes characterized as stationary covarion substitution patterns and changes in proportion of variable sites across sequences. Failure to accommodate covarion-like substitution patterns can have strong effects on the plastid tree topology. Importantly, multigene analyses performed with probabilistic methods using among-site rate and covarion models of evolution conflict with proposed single origin of the peridinin- and 19'-HNOF-containing plastids, suggesting that analysis of secondhand plastids can be hampered by convergence in the evolutionary signature of the plastid DNA sequences. Another type of sequence convergence was detected at protein level involving the psaA gene. Excluding the psaA sequence from a concatenated protein alignment grouped the peridinin plastid with haptophytes, congruent with all DNA trees. Altogether, taking account of complex processes involved in the evolution of dinoflagellate plastid sequences (both at the DNA and amino acid level), we demonstrate the difficulty of excluding independent, tertiary origin for both the peridinin and 19'-HNOF plastids involving engulfment of haptophyte-like algae. In addition, the refined topologies suggest the red algal order, Porphyridales, as the endosymbiont ancestor of the secondary plastids in cryptophytes, haptophytes, and heterokonts.     

The potential for large carnivores to act as biodiversity surrogates in southern Africa

Biodiversity in southern Africa is globally extraordinary but threatened by human activities. Although there are considerable biodiversity conservation initiatives within the region, no one has yet assessed the potential use of large carnivores in such actions. Surrogate approaches have often been suggested as one such way of capitalizing on large carnivores. Here we review the suitability of the large carnivore guild (i.e., brown hyaena Hyaena hyaena, spotted hyaena Crocuta crocutta, cheetah Acinonyx jubatus, leopard Panthera pardus, lion Panthea leo and African wild dog Lycaon pictus) to act as surrogate species for biodiversity conservation in southern Africa. We suggest that the guild must be complete for the large carnivores to fully provide their role as ecological keystones. The potential for large carnivores to act as umbrella and indicator species seems limited. However, self-sustaining populations of large carnivores may be useful indicators of unfragmented landscapes. Moreover, diversity within the large carnivore guild may reflect overall biodiversity. Although the global appeal of the large African carnivores makes them important international flagships, we stress that international conservation funding must be linked to local communities for them to be important also locally. In summary, we suggest that the flagship value of these large carnivores should be used to promote biodiversity conservation in the region, and that the suggested relationship between large carnivore diversity and overall biodiversity is empirically tested. Finally we suggest that direct conservation activities should focus on enhancing the keystone values of large carnivores through complete guild conservation and restoration.     

Oxygen-depleted surfaces: a new antifouling technology

A novel, non-toxic strategy to combat marine biofouling is presented. The technology is paint with additions of up to 43% of industrial protein. Through microbial degradation of the protein component, an oxygen-depleted layer rapidly forms in a 0.2 mm layer close to the paint surface. With the present paint formulations, a stable, O₂-depleted layer can persist for 16 weeks. Barnacle larvae (cyprids) did not settle on panels where oxygen saturation was <20%, and cyprids were killed when exposed to O₂-free water for more than 1 h. It is also shown that the O₂-depleted layer will rapidly reform (within 15 min) after exposure to turbulent flow. Field exposure of panels for 16 weeks showed that paint with protein reduced fouling by barnacles and bryozoans by 80% and close to 100%, respectively. The results suggest that this novel technology may be developed into a non-toxic alternative to copper-based antifouling paints, especially for pleasure boats in sensitive environments. There is clearly potential for further development of the paint formulation, and a full-scale test on a boat-hull suggested that service-life under realistic operations needs to be improved.