Evaporative Cooler Use Influences Temporal Indoor Relative Humidity but Not Dust Mite Allergen Levels in Homes in a Semi-Arid Climate

Concerns about energy consumption and climate change make residential evaporative coolers a popular alternative to central air conditioning in arid and semi-arid climates. However, evaporative coolers have been shown to significantly increase indoor relative humidity and dust mite allergen levels in some studies, while showing no association in other studies. Improved measurement of temporal fluctuations in indoor relative humidity may help identify factors that promote mite growth in homes in dry climates. Dust samples and continuous indoor relative humidity measurements were collected from homes with central air conditioning and homes with evaporative coolers in Utah. Samples were collected over two seasons, winter/spring (Jan–Apr) and summer (July–Sept), 2014. Dust samples were analyzed for Der p 1 and Der f 1 using a two-site monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) analysis. Housing characteristics including age of home, occupant density, and age of mattresses, furniture, and carpeting were also measured. Positive Der p 1 or Der f 1 samples were found in 25.0% of the homes and there was no difference in mean allergen levels by type of air conditioning. Indoor relative humidity was significantly higher in homes with evaporative coolers compared to those with central air conditioning during the summer. Homes with evaporative coolers also spent significantly more time during summer above 55.0% and 65.0% relative humidity compared to central air homes, but not above 75.0%. Findings from this study suggest that increased humidity from evaporative coolers may not be sufficient to exceed the critical equilibrium humidity or maintain humidity excursions for sufficient duration in relatively larger single-family homes in semi-arid climates to support mite growth and reproduction.     

Critical micelle concentrations of gangliosides

The micellar properties of mixed, bovine gangliosides and purified galactosyl-N-acetylacetylgalactosaminyl (N-acetylneuraminyl) galactosylglucosylceramide were studied by gel filtration, equilibrium dialysis, and band and boundary centrifugation in sucrose gradients. The dissociation of micelles is very slow (days) in water and required us to approach equilibrium by association of monomers rather than by the dissociation of micelles. The gangliosides were therefore first converted into very low molecular weight aggregates (1-3 molecules) by dissolving them in Me2SO. Galactosyl-N-acetylgalactosaminyl(N-acetylneuraminyl)galactosylglucosylceramide was then diluted into aqueous sucrose gradients and sedimented by the boundary centrifugation technique. This gave a sedimenting micelle and a nonsedimenting monomer concentration of (1-2) x 10-10 M (or less) which corresponds to the critical micelle concentration value. The mixed gangliosides revealed two micellar sizes (i.e., 10 and 4.5 S), the slower sedimenting species being formed from the larger one with time (days). The critical micelle concentration of the mixed gangliosides was found to be approximately 10-8 M by a gel filtration, equilibrium dialysis, and band centrifugation.     

The role of IFN in respiratory syncytial virus pathogenesis

Formalin-inactivated respiratory syncytial virus (RSV) vaccine preparations have been shown to cause enhanced disease in naive hosts following natural infection. In this study we demonstrate a similar pattern of enhanced disease severity following primary RSV infection of IFN-nonresponsive STAT1(-/-) mice. STAT1(-/-) mice showed markedly increased illness compared with wild-type BALB/c animals following RSV inoculation despite similar lung virus titers and rates of virus clearance. Histologically, STAT1(-/-) animals had eosinophilic and neutrophilic pulmonary infiltrates not present in wild-type or IFN-gamma(-/-)-infected mice. In cytokine analyses of infected lung tissue, IFN-gamma was induced in both STAT1(-/-) and wild-type mice, with preferential IL-4, IL-5, and IL-13 induction only in the STAT1(-/-) animals. Eotaxin was detected in the lungs of both wild-type and STAT1(-/-) mice following infection, with a 1.7-fold increase over wild-type in the STAT1(-/-) mice. Using a peptide epitope newly identified in the RSV fusion protein, we were able to demonstrate that wild-type memory CD4(+) T cells stimulated by this peptide produce primarily IFN-gamma, while STAT1(-/-)CD4(+) cells produce primarily IL-13. These findings suggest that STAT1 activation by both type I (alphabeta) and type II (gamma) IFNs plays an important role in establishing a protective, Th1 Ag-specific immune response to RSV infection.     

Design and in vivo immunogenicity of a polyvalent vaccine based on SIVmac regulatory genes

Most vaccine modalities for human immunodeficiency virus type 1 (HIV-1) tested for immunogenicity and efficacy in the SIVmac (simian immunodeficiency virus) macaque model do not include the viral regulatory proteins. Because viral regulatory proteins are expressed early during the virus life cycle and represent an additional source of antigens, their inclusion as a vaccine component may increase the overall virus-specific immune response in vaccinees. However, at least two of the early proteins, Tat and Nef, may be immunosuppressive, limiting their usefulness as components of an SIV vaccine. We have constructed a polyvalent chimeric protein in which the open reading frames for Tat and Nef have been reassorted and the nuclear localization sequence for Tat and Rev and the myristoylation site for Nef have been removed. The resulting DNA plasmid (pDNA-SIV-Retanef) (pDNA-SIV-RTN) encodes a protein of 55 kDa (Retanef) that localizes at the steady state in the cytoplasma of transfected cells. Both the DNA-SIV-RTN and the highly attenuated recombinant poxvirus vector NYVAC-SIV-RTN were demonstrated to be immunogenic in SIVmac251-infected macaques treated with ART as well as in naive macaques. An equivalent strategy may be used for the generation of polyvalent antigens encoding the regulatory proteins in a HIV-1 vaccine candidate.     

Phytate as the sole phosphate source for growth of Tetrahymena

Phytate, the storage form of phosphate in seeds and grains, is a major form of environmental phosphate loading from fertilizer inputs and agricultural runoff. We have investigated the ability of Tetrahymena populations to grow on phytate as their sole phosphate source. Populations grew equally well in chemically defined medium with phosphate and medium in which the phosphate was replaced with phytate in comparable concentrations between 0.5 mM and 6 mM. Intracellular phytate concentrations of cells grown in phytate showed a 4-6-fold increase over those grown in phosphate when measured during the late stage of exponential growth. These results demonstrate that phytate can provide a source of adequate phosphate for sustained growth in phytate-rich environments.     

Average niche breadths of species in lake macrophyte communities respond to ecological gradients variably in four regions on two continents

Different species’ niche breadths in relation to ecological gradients are infrequently examined within the same study and, moreover, species niche breadths have rarely been averaged to account for variation in entire ecological communities. We investigated how average environmental niche breadths (climate, water quality and climate–water quality niches) in aquatic macrophyte communities are related to ecological gradients (latitude, longitude, altitude, species richness and lake area) among four distinct regions (Finland, Sweden and US states of Minnesota and Wisconsin) on two continents. We found that correlations between the three different measures of average niche breadths and ecological gradients varied considerably among the study regions, with average climate and average water quality niche breadth models often showing opposite trends. However, consistent patterns were also found, such as widening of average climate niche breadths and narrowing of average water quality niche breadths of aquatic macrophytes along increasing latitudinal and altitudinal gradients. This result suggests that macrophyte species are generalists in relation to temperature variations at higher latitudes and altitudes, whereas species in southern, lowland lakes are more specialised. In contrast, aquatic macrophytes growing in more southern nutrient-rich lakes were generalists in relation to water quality, while specialist species are adapted to low-productivity conditions and are found in highland lakes. Our results emphasise that species niche breadths should not be studied using only coarse-scale data of species distributions and corresponding environmental conditions, but that investigations on different kinds of niche breadths (e.g., climate vs. local niches) also require finer resolution data at broad spatial extents.     

A plastome mutation affects processing of both chloroplast and nuclear DNA-encoded plastid proteins

Summary A bovine tRNA gene cluster has been characterized and the sequences of four tDNAs determined. Two of the tDNAs could encode tRNA^Ser _IGA, one tDNA^Ser _UGA, and the fourth tRNA^Gln _CUG. The three serine tDNAs representing the UCN codon isoacceptor family are almost identical. However, the sequence of the tDNA^Ser _TGA differs from a previously sequenced bovine tDNA^Ser _TGA at 12 positions (ca. 14%). This finding suggests that in the bovine genome, two subfamilies of genes might encode tRNA^Ser _UGA. It also raises the possibility that new genes for a specific UCN isoacceptor might arise from the genes of a different isoacceptor, and could explain previously observed differences between species in the anticodons of coevolving pairs of tRNAs^Ser _UCN. The gene cluster also contains complete and partial copies, and fragments, of the BCS (bovine consensus sequence) SINE (short interspersed nuclear element) family, six examples of which were sequenced. Some of these elements occur in close proximity to two of the serine tDNAs.     

The continuum concept remains a useful framework for studying mycorrhizal functioning

Background

Recent studies have questioned the validity of the mutualism-parasitism continuum of mycorrhizal function. This paper re-evaluates the continuum model and analyzes these concerns.

Scope and Conclusions

Three insights arise from this analysis. First, the continuum model defines mycorrhizal function as an emergent property of complex interactions. The model identifies resource trade and symbiotic control as key determinants of the costs and benefits of the symbiosis for plants and fungi, and the interaction of these factors with the environment ultimately controls mycorrhizal function. Second, analysis of carbon costs and phosphorus benefits is too narrow a focus to accurately predict mycorrhizal function. Analysis of plant and fungal fitness responses in ecologically and evolutionarily relevant systems are required to elucidate the full range of nutritional and non-nutritional factors embodied within mycorrhizal functioning. Finally, the definition of the term ‘parasitism’ has evolved. Some fields of science maintain the original definition of a nutritional relationship between host and parasite while other fields define it as a +/- fitness relationship. This has generated debate about whether the continuum of mycorrhizal functioning should properly be called a positive–negative response continuum or a mutualism-parasitism continuum. This controversy about semantics should be resolved, but it does not overturn the continuum concept.