Kekkon5 is an extracellular regulator of BMP signaling

AbstractPrecise spatial and temporal control of Drosophila Bone Morphogenetic Protein (BMP) signaling is achieved by a host of extracellular factors that modulate ligand distribution and activity. Here we describe Kekkon5 (Kek5), a transmembrane protein containing leucine-rich repeats (LRRs), as a novel regulator of BMP signaling in Drosophila. We find that loss or gain of kek5 disrupts crossvein development and alters the early profile of phosphorylated Mad and dSRF in presumptive crossvein cells. kek5 phenotypic effects closely mimic those observed with Short gastrulation (Sog), but do not completely recapitulate the effects of dominant negative BMP receptors. We further demonstrate that Kek5 is able to antagonize the BMP ligand Glass bottom boat (Gbb) and that the Kek5 LRRs are required for BMP inhibitory activity, while the Ig domain is dispensable in this context. Our identification of Kek5 as a modulator of BMP signaling supports the emerging notion that LIG proteins function as diverse regulators of cellular communication

Automated Calibration of Electrochemical Oxygen Sensors for Use in Compost Bedded Pack Barns

The objective of this study was to develop an automated calibration process for a galvanic cell type oxygen sensor. The manufacturer recommended a two-point calibration at room temperature; however, testing revealed that the response was not linear when both the temperature and oxygen concentrations varied. Thus, additional points were needed to generate a representative calibration equation and to reduce the sensor prediction interval. The calibration process needed to be capable of automatically recording sensor response (voltage) at an array of temperatures and oxygen concentrations. Calibration gases were used to precisely control the oxygen concentration inside a small manifold, and an electronically controlled water bath was used to regulate the sensor and gas temperature. A custom computer program controlled the sampling order and the data collection process. The responses for three sensors were recorded at six temperature (10°C, 20°C, 30°C, 40°C, 50°C, and 60°C) and five oxygen concentration (0%, 5%, 10%, 15%, and 20% O2 absolute) combinations, for a total of 30 measurements per calibration. Calibration data were used to create a second-degree polynomial model with oxygen sensor voltage and temperature as input parameters, which reduced the prediction interval by over 1% O2 for each of the three sensors tested. The resulting prediction intervals ranged between 0.75% and 0.95% O2. Three sensors were mounted in a prototype oxygen probe and tested under controlled conditions to demonstrate the ability to measure oxygen concentration versus depth in a composting environment

Population adaptation for genetic algorithm-based cognitive radios

Abstract — Genetic algorithms are best suited for optimization problems involving large search spaces. The problem space encountered when optimizing the transmission parameters of an agile or cognitive radio for a given wireless environment and set of performance objectives can become prohibitively large due to the high number of parameters and their many possible values. Recent research has demonstrated that genetic algorithms are a viable implementation technique for cognitive radio engines. However, the time required for the genetic algorithms to come to a solution substantionally increases as the system complexity grows. In this paper, we present a population adaptation technique for genetic algorithms that takes advantage of the information from previous cognition cycles in order to reduce the time required to reach an optimal decision. Our simulation results demonstrate that the amount of information from the previous cognition cycle can be determined from the environmental variation factor (EVF), which represents the amount of change in the environment parameters since the previous cognition cycle. I

Field Guide to Exhumed Major Faults in Southern California

This field guide provides an overview of exposures and provides a field trip guide to localities of exhumed faults in southern California. We focus on exposures of faults that are documented or inferred to be exhumed from seismogenic depths. The goal of this guidebook is to provide geoscientists who are interested in fault zone mechanics and earthquake processes a summary of the results of the work on these sites

NICMOS Imaging of the Nuclei of Arp 220

We report high resolution imaging of the ultraluminous infrared galaxy Arp 220 at 1.1, 1.6, and 2.22 microns with NICMOS on the HST. The diffraction-limited images at 0.1--0.2 arcsecond resolution clearly resolve both nuclei of the merging galaxy system and reveal for the first time a number of luminous star clusters in the circumnuclear envelope. The morphologies of both nuclei are strongly affected by dust obscuration, even at 2.2 microns : the primary nucleus (west) presents a crescent shape, concave to the south and the secondary (eastern) nucleus is bifurcated by a dust lane with the southern component being very reddened. In the western nucleus, the morphology of the 2.2 micron emission is most likely the result of obscuration by an opaque disk embedded within the nuclear star cluster. The morphology of the central starburst-cluster in the western nucleus is consistent with either a circumnuclear ring of star formation or a spherical cluster with the bottom half obscured by the embedded dust disk. Comparison of cm-wave radio continuum maps with the near-infrared images suggests that the radio nuclei lie in the dust disk on the west and near the highly reddened southern component of the eastern complex. The radio nuclei are separated by 0.98 arcseconds (corresponding to 364 pc at 77 Mpc) and the half-widths of the infrared nuclei are approximately 0.2-0.5 arcseconds. At least 8, unresolved infrared sources -- probably globular clusters -- are also seen in the circumnuclear envelope at radii 2-7 arcseconds . Their near-infrared colors do not significantly constrain their ages.Comment: LaTex, 15 pages with 1 gif figure and 5 postscript figures. ApJL accepte

Comparative Ultrastructure Of Digestive Diverticulae In Bathymodiolin Mussels: Discovery Of An Unknown Spherical Inclusion (Six) In Digestive Cells Of A Seep Mussel

Mussels in the genus Bathymodiolus host endosymbiotic bacteria in their gills, from which the mussel derives much of its nutrition. Bathymodiolin mussels also have functional digestive systems and, as in shallow-water mytilid mussels, cells of the digestive diverticulae are of two types: basophilic secretory cells and columnar digestive cells. Cellular contents of secretory and digestive cells of Bathymodiolus thermophilus and Bathymodiolus brevior from deep-sea hydrothermal vents are comparable to cellular contents of these cell types observed in shallow-water mytilids. In the seep mussel Bathymodiolus heckerae, cellular contents of columnar cells were anomalous, being dominated by an unknown cellular inclusion herein called spherical inclusion unknown or SIX. SIX was observed in all digestive cells and some basophilic cells of B. heckerae examined with TEM. It is a large (2-10-mu m diameter) and abundant (7 +/- 1.5 inclusions per epithelial cell section) inclusion, with a double external membrane and stacked internal lamellae. No microbial DNA was detected in digestive tubules of B. heckerae using molecular probes, preferential DNA amplification techniques, or DAPI staining, suggesting that SIX is not a unicellular parasite or symbiont. The ubiquity and abundance of SIX within cells of the digestive diverticula suggest that it has an important cellular function (positive or negative), yet to be determined

Molecular Gas in the Powerful Radio Nucleus of the Ultraluminous Infrared Galaxy PKS 1345+12

Millimeter CO(1-0) interferometry and high resolution, Hubble Space Telescope (HST) 1.1, 1.6, and 2.2 micron imaging of the radio compact galaxy PKS 1345+12 are presented. With an infrared luminosity of 2x10^{12} L_sun, PKS 1345+12 is a prime candidate for studying the link between the ultraluminous infrared galaxy phenomenon and radio galaxies. These new observations probe the molecular gas distribution and obscured nuclear regions of PKS 1345+12 and provide morphological support for the idea that the radio activity in powerful radio galaxies is triggered by the merger of gas rich galaxies. Two nuclei separated by 2" (4.0 kpc) are observed in the near-infrared; the extended southeastern nucleus has colors consistent with reddened starlight, and the compact northwestern nucleus has extremely red colors indicative of an optical quasar with a warm dust component. Further, the molecular gas, 3mm continuum, and radio emission are coincident with the redder nucleus, confirming that the northwestern nucleus is the site of the AGN and that the molecular gas is the likely fuel source.Comment: LaTex, 5 pages with 1 postscript and 1 jpg figure, ApJ Letters, in press (August 20, 1999