Low slip rates and long-term preservation of geomorphic features in Central Asia

In order to understand the dynamics of the India Asia collision zone, it is important to know the strain distribution in Central Asia, whose determination relies on the slip rates for active faults. Many previous slip-rate estimates of faults in Central Asia were based on the assumption that offset landforms are younger than the Last Glacial Maximum (approximately 20 kyr ago). In contrast, here we present surface exposure ages of 40 to 170 kyr, obtained using cosmogenic nuclide dating, for a series of terraces near a thrust at the northern margin of the Tibetan Plateau. Combined with the tectonic offset, the ages imply a long-term slip rate of only about 0.35 mm x yr(-1) for the active thrust, an order of magnitude lower than rates obtained from the assumption that the terraces formed after the Last Glacial Maximum. Our data demonstrate that the preservation potential of geomorphic features in Central Asia is higher than commonly assumed.     

Diatom floristics and succession in a peat bog near Lily Lake, Summit County, Utah

Diatoms from core samples obtained from the edge of Lily Lake, Summit County, Utah, were studied. Populations from each 15 cm of the core and niche metrics of the important species were analyzed. This study demonstrates four periods of history in the lake as mirrored by the diatom populations. The first period was mesotrophic and alkaline. This graded into an acidic, dystrophic period which in turn yielded again to a mesotrophic alkaline period. The most recent period can be characterized by a return to dystrophy.     

Environmental interaction in summer algal communities of Utah Lake

Utah Lake is a shallow eutrophic lake in central Utah. It is characterized by high nutrient and silt loads and by large algal blooms in late summer and early fall. Phytoplankton samples and environmental data were taken from June through August 1974. Phytoplankton species were identified and then quantified in a Palmer counting cell. Environmental continuum theory was employed to describe algal succession, and regression analysis was used to discover interactions between algal communities and the environment. Phytoplankton communities in June were characterized by high species diversity. As the lake environment became stressed in late summer due to higher turbidity, nutrient levels, pH, and available inorganic carbon species diversity decreased. By August, the phytoplankton flora was composed essentially of only two species, Ceratium hirundinella and Aphanizomenon flos - aquae.     

Subaerial algae of Navajo National Monument, Arizona

Samples from soils and other xeric substrates in Navajo National Monument, Navajo County, Arizona, were collected in 1978. After being moistened with deionized water for three days, these samples were analyzed for algae. Thirty algal taxa were identified. Five species of filamentous Cyanophyta comprised the majority of the biomass. Diatoms were ubiquitous in the soils although low in density. Diatom floras were very similar throughout the monument. Well-developed algal crusts were common in sites where grazing and excessive litter were absent.     

Influence of cryptogamic crusts on moisture relationships of soils in Navajo National Monument, Arizona

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New records and comprehensive list of the algal taxa of Utah Lake, Utah, USA

Utah Lake is a slightly saline ecosystem containing more than 700 algal taxa. During the past decade a total of 106 algal taxa has been found that has not previously been reported in this water. These new records are reported herein, together with a comprehensive listing of all algal taxa reported from Utah Lake to date.         

Altered proteostasis in aging and heat shock response in C. elegans revealed by analysis of the global and de novo synthesized proteome

Protein misfolding and aggregation as a consequence of impaired protein homeostasis (proteostasis) not only characterizes numerous age-related diseases but also the aging process itself. Functionally related to the aging process are, among others, ribosomal proteins, suggesting an intimate link between proteostasis and aging. We determined by iTRAQ quantitative proteomic analysis in C. elegans how the proteome changes with age and in response to heat shock. Levels of ribosomal proteins and mitochondrial chaperones were decreased in aged animals, supporting the notion that proteostasis is altered during aging. Mitochondrial enzymes of the tricarboxylic acid cycle and the electron transport chain were also reduced, consistent with an age-associated energy impairment. Moreover, we observed an age-associated decline in the heat shock response. In order to determine how protein synthesis is altered in aging and in response to heat shock, we complemented our global analysis by determining the de novo proteome. For that, we established a novel method that enables both the visualization and identification of de novo synthesized proteins, by incorporating the non-canonical methionine analogue, azidohomoalanine (AHA), into the nascent polypeptides, followed by reacting the azide group of AHA by ‘click chemistry’ with an alkyne-labeled tag. Our analysis of AHA-tagged peptides demonstrated that the decreased abundance of, for example, ribosomal proteins in aged animals is not solely due to degradation but also reflects a relative decrease in their synthesis. Interestingly, although the net rate of protein synthesis is reduced in aged animals, our analyses indicate that the synthesis of certain proteins such as the vitellogenins increases with age.     

Diatoms in recent bottom sediments and trophic status of eight lakes and reservoirs in northeastern Utah

Recent bottom sediments of eight lakes and reservoirs in northeastern Utah were examined. One hundred and sixty-four diatom taxa were identified and their relative abundances determined. Seven stand associations were evident by cluster analysis of similarity indices. These association patterns mirrored trophic status of the waters. Shannon-Wiener species diversity values were also determined. The diversities fell in patterns that were similar to the stand associations determined by cluster analysis. The most prevalent diatom taxa encountered in this study were found mostly in eutrophic waters. These taxa included Stephanodiscus astraea, Stephanodiscus astraea var. minutula, Asterionella formosa, and Fragilaria crotonensis. A wide variety of other taxa dominated various mesotrophic and oligotrophic sites.         

Occurrence of Phaedactylum Tricornutum in the Great Salt Lake, Utah, USA

The diatom Phaedactylum tricornutum Bohlin forms blooms in the south arm of the Great Salt Lake, Utah, during cool months. This represents the first report of this taxon from Utah and the first from nonmarine waters in the United States.     

Cryptogamic soil crusts: seasonal variation in algal populations in the Tintic Mountains, Juab County, Utah

The soil algae in the Tintic Mountains, Juab County, Utah, was studied over a one-year period in 1982 and 1983. Fluorescence microscopy was used to measure algal density in samples directly from the field. A total of 30 algal taxa was observed, blue-green algae being most abundant both in terms of density and number of species. Algal density showed peaks in late fall and late spring. Minima were present in September 1982 and July 1983. Several weak correlations between algal density and climatic data existed. In general algae correlated positively with precipitation and negatively with temperature. A combination of low precipitation and hot temperatures was likely responsible for the low density observed in July. The Chrysophyta followed slightly different trends than the other algal groups, having minima in early October 1982 and late August 1983. Field observations indicated that the degree of algal crusting varied noticeably over a period of one year, with highest abundance of hummocking in spring. Heavy summer thunderstorms destroyed algal crusting during July and August of 1983, though absolute density of algae increased during this time in response to the extra moisture.