Sierra Nevada snow melt from SMS-2

A film loop from SMS-2 imagery shows snow melt over the Sierra Nevadas from May 10 to July 8, 1975. The sequence indicates a successful application of geostationary satellite data for monitoring dynamic hydrologic conditions

Long-Term Changes in Sea Surface Temperature Off the Coast of Central California and Monterey Bay from 1920 to 2014: Are They Commensurate?

We examine to what extent the waters of Monterey Bay act independently of those along the central California coast. Sea surface temperatures (SSTs) from 1920 to 2014 from the central California coast and Monterey Bay were analyzed for long-term trends. To estimate the trends, singular spectrum analysis and empirical mode decomposition were employed. Between 1920 and 1940, long-term trends inside and outside Monterey Bay revealed rapidly increasing temperatures. After 1940 trends inside the bay indicate that temperatures increased from ~1950 for the next 40 years, peaking around 1990, and then decreased rapidly through 2013. Offshore, temperatures increased to the early 1960s, after which they decreased until 2014. El Nino episodes, the Pacific decadal oscillation (PDO), and increased coastal upwelling contribute to the long-term trends. Also, the impact of regime shifts associated with the PDO may be sustained for decades. Overall, the differences in the trends inside and outside Monterey Bay are significant only during summer where large-scale processes dominate offshore, and smaller-scale processes are important in and around the bay. Finally, our results suggest that waters inside the bay, although they co-vary with the waters further offshore, often appear to behave independently based on the long-term trends

Enzymatic DNA molecules

The present invention discloses deoxyribonucleic acid enzymes--catalytic or enzymatic DNA molecules--capable of cleaving nucleic acid sequences or molecules, particularly RNA, in a site-specific manner, as well as compositions including same. Methods of making and using the disclosed enzymes and compositions are also disclosed

Examination of the structural and functional versatility of glmS ribozymes by using in vitro selection

Self-cleaving ribozymes associated with the glmS genes of many Gram-positive bacteria are activated by binding to glucosamine-6-phosphate (GlcN6P). Representatives of the glmS ribozyme class function as metabolite-sensing riboswitches whose self-cleavage activities down-regulate the expression of GlmS enzymes that synthesizes GlcN6P. As with other riboswitches, natural glmS ribozyme isolates are highly specific for their target metabolite. Other small molecules closely related to GlcN6P, such as glucose-6-phosphate, cannot activate self-cleavage. We applied in vitro selection methods in an attempt to identify variants of a Bacillus cereus glmS ribozyme that expand the range of compounds that induce self-cleavage. In addition, we sought to increase the number of variant ribozymes of this class to further examine the proposed secondary structure model. Although numerous variant ribozymes were obtained that efficiently self-cleave, none exhibited changes in target specificity. These findings are consistent with the hypothesis that GlcN6P is used by the ribozyme as a coenzyme for RNA cleavage, rather than an allosteric effector

The distributions, mechanisms, and structures of metabolite-binding riboswitches

Phylogenetic analyses revealed insights into the distribution of riboswitch classes in different microbial groups, and structural analyses led to updated aptamer structure models and insights into the mechanism of these non-coding RNA structures

A 30-Year History of the Tides and Currents in Elkhorn Slough, California

Elkhorn Slough was first exposed to the waters of Monterey Bay with the construction of Moss Landing Harbor in 1946. It follows a 10-km path inland from Moss Landing Harbor. Today, it is a habitat and sanctuary for a wide variety of marine mammals, fish, and seabirds. The currents, tides and physical properties of Elkhorn Slough have been observed since 1970. It is an ebb-dominated estuary due to the asymmetric rise and fall of the tides which produces ebb currents that dominate. Tidal distortion increases inland due to frictional effects and extensive mud flats and Salicornia marsh. Tidal distortion also produces overtides and compound tides. Tidal elevations and currents often reveal the characteristics of a standing wave system. The temperature and salinity of lower Elkhorn Slough reflect the influence of Monterey Bay waters, whereas the upper Slough is more sensitive to local processes. Maximum tidal currents in Elkhorn Slough have increased from ∼75 to ∼150 cm/s since 1970. This increase is primarily due to the change in tidal prism which has increased from ∼2.5 to ∼7.6 × 106 m3 between 1956 and 2003. Finally, this increase is due to both man-made changes and continued tidal erosion

Sea surface and remotely sensed temperatures off Cape Mendocino, California

During September 3 to 5, 1979, a multisensor oceanographic experiment was conducted off Cape Mendocino, California. The purpose of this experiment was to validate the use of remote sensing techniques over an area along the U.S. west coast where coasted upwelling is known to be intense. Remotely sensed mutlispectral data, including thermal infrared imagery, were collected above an upwelling feature off Cape Mendocino. Data were acquired from the TIRNOS-N and NOAA-6 polar orbiting satellites, the NASA Ames Research Center's high altitude U-2 aircraft, and a U.S. Coast Guard C-130 aircraft. Supporting surface truth data over the same feature were collected aboard the National Oceanic and Atmospheric Administration (NOAA) ship, OCEANOGRAPHER. Atmospheric soundings were also taken aboard the ship. The results indicate that shipboard measurements of sea surface temperatures can be reproduction within 1 C or better through remote observation of absolute infrared radiance values (whether measured aboard the NOAA polar orbiting satellite, the U-2 aircraft, or the Coast Guard aircraft) by using appropriate atmospheric corrections. Also, the patterns of sea surface temperature which were derived independently from the various remote platforms provide a consistent interpretation of the surface temperature field

Self-Incorporation of Coenzymes by Ribozymes

RNA molecules that are assembled from the four standard nucleotides contain a limited number of chemical functional groups, a characteristic that is generally thought to restrict the potential for catalysis by ribozymes. Although polypeptides carry a wider range of functional groups, many contemporary protein-based enzymes employ coenzymes to augment their capabilities. The coenzymes possess additional chemical moieties that can participate directly in catalysis and thereby enhance catalytic function. In this work, we demonstrate a mechanism by which ribozymes can supplement their limited repertoire of functional groups through RNAcatalyzed incorporation of various coenzymes and coenzyme analogues. The group I ribozyme of Tetrahymena thermophila normally mediates a phosphoester transfer reaction that results in the covalent attachment of guanosine to the ribozyme. Here, a shortened version of the ribozyme is shown to catalyze the self-incorporation of coenzymes and coenzyme analogues, such as NAD+ and dephosphorylated CoA-SH. Similar ribozyme activities may have played an important role in the "RNA world," when RNA enzymes are thought to have maintained a complex metabolism in the absence of proteins and would have benefited from the inclusion of additional functional groups

A DNA enzyme with Mg(2+)-Dependent RNA Phosphoesterase Activity

Previously we demonstrated that DNA can act as an enzyme in the Pb(2+)-dependent cleavage of an RNA phosphoester. This is a facile reaction, with an uncatalyzed rate for a typical RNA phosphoester of approx. 10(exp -4)/ min in the presence of 1 mM Pb(OAc)2 at pH 7.0 and 23 C. The Mg(2+) - dependent reaction is more difficult, with an uncatalyzed rate of approx. 10(exp -7)/ min under comparable conditions. Mg(2+) - dependent cleavage has special relevance to biology because it is compatible with intracellular conditions. Using in vitro selection, we sought to develop a family of phosphoester-cleaving DNA enzymes that operate in the presence of various divalent metals, focusing particularly on the Mg(2+) - dependent reaction. Results: We generated a population of greater than 10(exp 13) DNAs containing 40 random nucleotides and carried out repeated rounds of selective amplification, enriching for molecules that cleave a target RNA phosphoester in the presence of 1 mM Mg(2+), Mn(2+), Zn(2+) or Pb(2+). Examination of individual clones from the Mg(2+) lineage after the sixth round revealed a catalytic motif comprised of a three-stem junction.This motif was partially randomized and subjected to seven additional rounds of selective amplification, yielding catalysts with a rate of 0.01/ min. The optimized DNA catalyst was divided into separate substrate and enzyme domains and shown to have a similar level of activity under multiple turnover conditions. Conclusions: We have generated a Mg(2+) - dependent DNA enzyme that cleaves a target RNA phosphoester with a catalytic rate approx. 10(exp 5) - fold greater than that of the uncatalyzed reaction. This activity is compatible with intracellular conditions, raising the possibility that DNA enzymes might be made to operate in vivo

Engineered allosteric ribozymes that respond to specific divalent metal ions

In vitro selection was used to isolate five classes of allosteric hammerhead ribozymes that are triggered by binding to certain divalent metal ion effectors. Each of these ribozyme classes are similarly activated by Mn(2+), Fe(2+), Co(2+), Ni(2+), Zn(2+) and Cd(2+), but their allosteric binding sites reject other divalent metals such as Mg(2+), Ca(2+) and Sr(2+). Through a more comprehensive survey of cations, it was determined that some metal ions (Be(2+), Fe(3+), Al(3+), Ru(2+) and Dy(2+)) are extraordinarily disruptive to the RNA structure and function. Two classes of RNAs examined in greater detail make use of conserved nucleotides within the large internal bulges to form critical structures for allosteric function. One of these classes exhibits a metal-dependent increase in rate constant that indicates a requirement for the binding of two cation effectors. Additional findings suggest that, although complex allosteric functions can be exhibited by small RNAs, larger RNA molecules will probably be required to form binding pockets that are uniquely selective for individual cation effectors