Molecular characterization of novel red green nonsulfur bacteria from five distinct hot spring communities in Yellowstone National Park.

We characterized and compared five geographically isolated hot springs with distinct red-layer communities in Yellowstone National Park. Individual red-layer communities were observed to thrive in temperatures ranging from 35 to 60 degrees C and at pH 7 to 9. All communities were dominated by red filamentous bacteria and contained bacteriochlorophyll a (Bchl a), suggesting that they represented novel green nonsulfur (GNS) bacteria. The in vivo absorption spectra of individual sites were different, with two sites showing unusual Bchl a protein absorption bands beyond 900 nm. We prepared and analyzed 16S rRNA libraries from all of these sites by using a combination of general bacterial primers and new GNS-specific primers described here. These studies confirmed the presence of novel GNS-like bacteria in all five communities. All GNS-like clones were most similar to Roseiflexus castenholzii, a red filamentous bacterium from Japan that also contains only Bchl a. Phylogenies constructed by using GNS-like clones from Yellowstone red-layer communities suggest the presence of a moderately diverse new "red" cluster within the GNS lineage. Within this cluster, at least two well-supported subclusters emerged: YRL-A was most similar to Roseiflexus and YRL-B appeared to be novel, containing no known isolates. While these patterns showed some site specificity, they did not correlate with observed Bchl a spectrum differences or obvious features of the habitat.     

Genetic divergence, speciation and biogeography of Mustelus (sharks) in the central Indo-Pacific and Australasia

The shark genus Mustelus is speciose, commercially important and systematically troublesome. We use a molecular approach combining inter and intra-specific data to investigate Mustelus species in the central Indo-Pacific and Australasia. Our analysis supports two Mustelus clades, one comprising species with no white spots and a placental reproductive mode and a second clade of white spotted, aplacental species. Levels of genetic divergence are low, especially among species in the white spotted, aplacental clade and this should be taken into account when employing molecular data to delineate species. Our data support the hypothesis of a radiation following dispersal from a northern hemisphere ancestor. Molecular dating suggests that localised speciation in Australasia may have occurred during the Pleistocene. We propose that some of the difficulties associated with Mustelus systematics relate to a recent radiation, particularly in the Australasian region.     

Molecular Characterization of Novel Red Green Nonsulfur Bacteria from Five Distinct Hot Spring Communities in Yellowstone National Park

We characterized and compared five geographically isolated hot springs with distinct red-layer communities in Yellowstone National Park. Individual red-layer communities were observed to thrive in temperatures ranging from 35 to 60°C and at pH 7 to 9. All communities were dominated by red filamentous bacteria and contained bacteriochlorophyll a (Bchl a), suggesting that they represented novel green nonsulfur (GNS) bacteria. The in vivo absorption spectra of individual sites were different, with two sites showing unusual Bchl a protein absorption bands beyond 900 nm. We prepared and analyzed 16S rRNA libraries from all of these sites by using a combination of general bacterial primers and new GNS-specific primers described here. These studies confirmed the presence of novel GNS-like bacteria in all five communities. All GNS-like clones were most similar to Roseiflexus castenholzii, a red filamentous bacterium from Japan that also contains only Bchl a. Phylogenies constructed by using GNS-like clones from Yellowstone red-layer communities suggest the presence of a moderately diverse new “red” cluster within the GNS lineage. Within this cluster, at least two well-supported subclusters emerged: YRL-A was most similar to Roseiflexus and YRL-B appeared to be novel, containing no known isolates. While these patterns showed some site specificity, they did not correlate with observed Bchl a spectrum differences or obvious features of the habitat.     

Adaptive and Maladaptive Correlates of Repetitive Behavior and Restricted Interests in Persons with Down Syndrome and Developmentally-Matched Typical Children: A Two-Year Longitudinal Sequential Design

We examined the course of repetitive behavior and restricted interests (RBRI) in children with and without Down syndrome (DS) over a two-year time period. Forty-two typically-developing children and 43 persons with DS represented two mental age (MA) levels: “younger” 2–4 years; “older” 5–11 years. For typically developing younger children some aspects of RBRI increased from Time 1 to Time 2. In older children, these aspects remained stable or decreased over the two-year period. For participants with DS, RBRI remained stable or increased over time. Time 1 RBRI predicted Time 2 adaptive behavior (measured by the Vineland Scales) in typically developing children, whereas for participants with DS, Time 1 RBRI predicted poor adaptive outcome (Child Behavior Checklist) at Time 2. The results add to the body of literature examining the adaptive and maladaptive nature of repetitive behavior.     

Formation of Multilayered Photosynthetic Biofilms in an Alkaline Thermal Spring in Yellowstone National Park,Wyoming

In this study, glass rods suspended at the air-water interface in the runoff channel of Fairy Geyser, Yellowstone National Park, WY, were used as a substratum to promote the development of biofilms that resembled multilayered mat communities in the splash zone at the geyser''s source. This approach enabled the establishment of the temporal relationship between the appearance of Cyanobacteria, which ultimately formed the outer green layer, and the development of a red underlayer containing Roseiflexus-like Chloroflexi. This is the first study to define time-dependent successional events involved in the development of differently colored layers within microbial mats associated with many thermal features in Yellowstone National Park. Initial (1-month) biofilms were localized below the air-water interface (60 to 70°C), and the majority of retrieved bacterial sequence types were similar to Synechococcus and Thermus isolates. Biofilms then shifted, becoming established at and above the air-water interface after 3 months. During winter sampling (6 to 8 months), distinct reddish orange microcolonies were observed, consistent with the appearance of Roseiflexus-like sequences and bacteriochlorophyll a pigment signatures. Additionally, populations of Cyanobacteria diversified to include both unicellular and filamentous cell and sequence types. Distinct green and red layers were observed at 13 months. Planctomycetes-like sequences were also retrieved in high abundance from final biofilm layers and winter samples. Finally, biomass associated with geyser vent water contained Roseiflexus-like sequence types, in addition to other high-abundance sequence types retrieved from biofilm samples, supporting the idea that geothermal water serves as an inoculum for these habitats.Biofilms are widely recognized as the way that most microbes exist in natural habitats (10-12), often developing into thick mats on various substrata associated with geysers and thermal springs in places such as Yellowstone National Park (53). In the first published microbiological studies of near-boiling pools in Yellowstone''s Lower Geyser Basin, an immersed glass slide approach was used to recover biofilm-forming microbial communities containing thermophilic Cyanobacteria, pink and yellow filaments, and many colorless rods (7, 8). Dispersal of microorganisms from biofilms has been investigated using 16S rRNA studies of geothermal vent source water and downstream travertine deposit samples at Angel Terrace, a carbonate spring in Mammoth Basin, Yellowstone National Park (18, 19). Using an artificial substrate and in situ kinetic apparatus at Angel Terrace, Kandianis et al. recently demonstrated that biomass serves as a catalyst in the precipitation of calcium carbonate (27). Regrowth of cyanobacterial mat communities after excision and removal at the alkaline Octopus Spring in the Lower Geyser Basin was investigated by Ferris et al. (16). In an effort to address how biofilms influence sinter formation, Cady and Farmer (9) observed that the presence of hyperthermophilic biofilms influenced the development of spicular geyserite by providing a preferred substratum for opaline silica precipitation. In a follow-up study, Blank et al. observed that communities in the subaqueous environment of alkaline, silica-depositing springs were similar to those associated with spicular geyserite at the air-water interface within the same spring (3). However, none of these studies has examined biofilm growth using artificial substrata to systematically evaluate community succession over time.Fairy Geyser represents a constantly erupting alkaline geothermal feature. Its vent waters (70 to 90°C) almost constantly erupt and splash, supporting the growth of extensive multilayered mat communities (35 to 60°C and pH 7.5 to 8.5) that form just above the water, on top of the sinter which surrounds the main geyser vent (5, 6). Fairy Geyser splash mats are composed of a green surface layer of Cyanobacteria and a red underlayer dominated by Roseiflexus-like Chloroflexi (5, 6). In monitoring Fairy Geyser since 1998, we have regularly observed the formation of similar multilayered photosynthetic microbial mats in splash zones at the cooler air-water interface (35 to 40°C) along the runoff channel or on debris that has fallen into the runoff channel (S. Boomer, unpublished results). Consequently, we hypothesized that solid substrata suspended in the Fairy Geyser runoff channel should support biofilm development and serve as a simple means for monitoring successional events over time, including the development of multilayered communities. Because Roseiflexus-like Chloroflexi from comparable red-layer communities in Yellowstone have been shown to be nonsulfur photoheterotrophs that metabolize under low-intensity light (6), we further hypothesized that red underlayer formation would require the presence of a shielding green layer and would thus form after initial colonization by Cyanobacteria. In addition to decreasing the light intensity, the photoautotrophic Cyanobacteria would provide organic compounds for the photoheterotrophic Chloroflexi, which typically consume cyanobacterial photosynthate in nature (40). Finally, we hypothesized that Roseiflexus-like Chloroflexi would be present in geothermal water at the vent source, providing an inoculum for substrata in the runoff channel.To test these hypotheses, we characterized the microbial community that accumulated at the air-water interface of sterile glass rods suspended in the thermal runoff at Fairy Geyser. Owing to environmental resource impact and winter access issues, this report encompasses two separate year-long studies. The first study (2004-2005) investigated the succession of the rod-associated communities during the first 3 months of colonization in the summer season, while the second study (2006-2007) investigated the succession after longer periods (6 to 8 months) of colonization during the winter season. In both cases, some replicates were maintained for 13 months, producing thick and gelatinous mat-like biofilms with outer green and inner red layering. For samples from all time points, we assessed biofilm accumulation by using microscopy, pigment analysis, and 16S rRNA studies, targeting both general bacteria and Chloroflexi. Although aforementioned Yellowstone biofilm studies have reported growing monolayers on artificial substrates or performed disturbance and recovery studies of existing mat systems in Yellowstone, this study represents the first report of multilayered photosynthetic mats being generated and studied in this manner.     

Climate change,uncertainty, and natural resource management

Climate change and its associated uncertainties are of concern to natural resource managers. Although aspects of climate change may be novel (e.g., system change and nonstationarity), natural resource managers have long dealt with uncertainties and have developed corresponding approaches to decision-making. Adaptive resource management is an application of structured decision-making for recurrent decision problems with uncertainty, focusing on management objectives, and the reduction of uncertainty over time. We identified 4 types of uncertainty that characterize problems in natural resource management. We examined ways in which climate change is expected to exacerbate these uncertainties, as well as potential approaches to dealing with them. As a case study, we examined North American waterfowl harvest management and considered problems anticipated to result from climate change and potential solutions. Despite challenges expected to accompany the use of adaptive resource management to address problems associated with climate change, we conclude that adaptive resource management approaches will be the methods of choice for managers trying to deal with the uncertainties of climate change. © 2010 The Wildlife Society.     

Genetic data show that Carcharhinus tilstoni is not confined to the tropics, highlighting the importance of a multifaceted approach to species identification

This study shows a range extension for the Australian blacktip shark Carcharhinus tilstoni, which was believed to be restricted to Australia's tropical waters, of >1000 km into temperate waters, revealing its vulnerability to a wider commercial fishery.     

Virulence of Candida albicans mutants toward larval Galleria mellonella (Insecta, Lepidoptera, Galleridae)

Culture medium affected the virulence of a strain of Candida albicans toward Galleria mellonella larvae, but the yeast growth rates in yeast extract - peptone - dextrose broth and synthetic Galleria serum were not correlated with yeast virulence. Virulent C. albicans grew rapidly in larval serum, whereas, it limited nodulation and continued development in vivo, producing toxins that damaged the hemocytes and fat body. Nonpathogenic yeast-phase cells grew slowly in larval serum but induced extensively melanized nodules in vivo and developed no further. There was no discernible relationship in 14 exo-enzymes between the virulent and avirulent yeast strains and virulence. The avirulent myosin-I-defective yeast cells were rapidly removed from the hemolymph in vivo because of lysozyme-mediated yeast agglutination and the possible binding of the yeast cells by lysozyme and apolipophorin-III. Both lysozyme and apolipophorin-III are proteins that bind beta-1,3-glucan. Finally, insects with nonpathogenic C. albicans exhibited induced immunity and were more resistant to candidiasis from the wild-type yeast cells than were noninduced insects.     

Characterization of novel bacteriochlorophyll-a-containing red filaments from alkaline hot springs in Yellowstone National Park

Novel red, filamentous, gliding bacteria formed deep red layers in several alkaline hot springs in Yellowstone National Park. Filaments contained densely layered intracellular membranes and bacteriochlorophyll a. The in vivo absorption spectrum of the red layer filaments was distinct from other phototrophs, with unusual bacteriochlorophyll a signature peaks in the near-infrared (IR) region (807 nm and 911 nm). These absorption peaks were similar to the wavelengths penetrating to the red layer of the mats as measured with in situ spectroradiometry. The filaments also demonstrated maximal photosynthetic uptake of radiolabeled carbon sources at these wavelengths. The red layer filaments displayed anoxygenic photoheterotrophy, as evidenced by the specific incorporation of acetate, not bicarbonate, and by the absence of oxygen production. Photoheterotrophy was unaffected by sulfide and oxygen, but was diminished by high-intensity visible light. Near-IR radiation supported photoheterotrophy. Morphologically and spectrally similar filaments were observed in several springs in Yellowstone National Park, including Octopus Spring. Taken together, these data suggest that the red layer filaments are most similar to the photoheterotroph, Heliothrix oregonensis. Notable differences include mat position and coloration, absorption spectra, and prominent intracellular membranes.