A unique zinc finger protein is associated preferentially with active ecdysone-responsive loci in Drosophila

Using an immunochemical approach, we have identified a unique antigen, PEP (protein on ecdysone puffs), which is associated in third-instar larvae with the active ecdysone-regulated loci on polytene chromosomes; PEP is not associated with most intermolt puffs and is found on some, but not all, heat shock-induced puffs. The distribution pattern changes with changing puffing patterns in the developmental program. We have screened an expression library and recovered a cDNA clone encoding PEP. PEP possesses multiple potential nucleic acid- and protein- binding regions: a glycine- and asparagine-rich amino terminus, four zinc finger motifs, two very acidic segments, two short basic stretches, and an alanine- and proline-rich carboxyl terminus. The Pep gene maps by in situ hybridization to the cytological locus 74F, adjacent to the early ecdysone-responsive region; however, the gene is not regulated by ecdysone at the level of transcription. The pattern of Pep expression through development suggests that maternal Pep gene transcripts are supplied to the embryo, and that the abundance of Pep gene transcripts decreases to a lower, fairly constant level thereafter. This unusual protein may play a role in the process of gene activation, or possibly in RNA processing, for a defined set of developmentally regulated loci. Keywords: Drosophila-, ecdysone puffs; locus 74F; polytene chromosomes; zinc finger

Statistics of soliton-bearing systems with additive noise

We present a consistent method to calculate the probability distribution of soliton parameters in systems with additive noise. Even though a weak noise is considered, we are interested in probabilities of large fluctuations (generally non-Gaussian) which are beyond perturbation theory. Our method is a further development of the instanton formalism (method of optimal fluctuation) based on a saddle-point approximation in the path integral. We first solve a fundamental problem of soliton statistics governing by noisy Nonlinear Schr\"odinger Equation (NSE). We then apply our method to optical soliton transmission systems using signal control elements (filters, amplitude and phase modulators).Comment: 4 pages. Submitted to PR

An actin-related protein in Drosophila colocalizes with heterochromatin protein 1 in pericentric heterochromatin

The actin-related proteins have been identified by virtue of their sequence similarity to actin. While their structures are thought to be closely homologous to actin, they exhibit a far greater range of functional diversity. We have localized the Drosophila actin-related protein, Arp4, to the nucleus. It is most abundant during embryogenesis but is expressed at all developmental stages. Within the nucleus Arp4 is primarily localized to the centric heterochromatin. Polytene chromosome spreads indicate it is also present at much lower levels in numerous euchromatic bands. The only other protein in Drosophila reported to be primarily localized to centric heterochromatin in polytene nuclei is heterochromatin protein 1 (HP1), which genetic evidence has linked to heterochromatin-mediated gene silencing and alterations in chromatin structure. The relationship between Arp4 and heterochromatin protein 1 (HP1) was investigated by labeling embryos and larval tissues with antibodies to Arp4 and HP1. Arp4 and HP1 exhibit almost superimposable heterochromatin localization patterns, remain associated with the heterochromatin throughout prepupal development, and exhibit similar changes in localization during the cell cycle. Polytene chromosome spreads indicate that the set of euchromatic bands labeled by each antibody overlap but are not identical. Arp4 and HP1 in parallel undergo several shifts in their nuclear localization patterns during embryogenesis, shifts that correlate with developmental changes in nuclear functions. The significance of their colocalization was further tested by examining nuclei that express mutant forms of HP1. In these nuclei the localization patterns of HP1 and Arp4 are altered in parallel fashion. The morphological, developmental and genetic data suggest that, like HP1, Arp4 may have a role in heterochromatin functions. Keywords: Chromatin, Actin-related protein, Drosophila, Heterochromatin-protein 1, Position effect variegatio

Preliminary Heat Capacity and Vapor Pressure Measurements of 2D 4He on ZYX Graphite

We report preliminary heat capacity and vapor pressure measurements of the first and second layers of 4He adsorbed on ZYX graphite. ZYX is known to have much better crystallinity than Grafoil, the most commonly-used exfoliated graphite substrate, such as a ten-times larger platelet size. This allows us to distinguish different phases in 2D helium-4 much more clearly and may provide qualitatively different insights into this system. We found a significantly asymmetric density-dependence of the heat-capacity peak associated with the 1/3 phase formation comparing with that obtained with Grafoil. The 2nd-layer promotion density is determined as 11.8+-0.3 nm-2 from the heat-capacity measurement of low density samples in the 2nd layer and vapor pressure measurement.Comment: 7 pages, 7 figures, accepted for publication in JLTP - QFS201

Nutrient Improvements in Chesapeake Bay: Direct Effect of Load Reductions and Implications for Coastal Management

In Chesapeake Bay in the United States, decades of management efforts have resulted in modest reductions of nutrient loads from the watershed, but the corresponding improvements in estuarine water quality have not consistently followed. Generalized additive models were used to directly link river flows and nutrient loads from the watershed to nutrient trends in the estuary on a station-by-station basis, which allowed for identification of exactly when and where responses are happening. Results show that Chesapeake Bay’s total nitrogen and total phosphorus conditions are mostly improving after accounting for variation in freshwater flow. Almost all of these improving nutrient concentrations in the estuary can be explained by reductions in watershed loads entering through 16 rivers and 145 nearby point sources, with the nearby point source reductions being slightly more effective at explaining estuarine nutrient trends. Overall, these two major types of loads from multiple locations across the watershed are together necessary and responsible for the improving estuarine nutrient conditions, a finding that is highly relevant to managing valuable estuarine resources worldwide

Non-Gaussian statistics of an optical soliton in the presence of amplified spontaneous emission

A study was performed on non-Gaussian statistics of an optical soliton in the presence of amplified spontaneous emission. An approach based on the Fokker-Planck equation was applied to study the optical soliton parameters in the presence of additive noise. The rigorous method not only allowed to reproduce and justify the classical Gordon-Haus formula but also led to new exact results