The Carboxyl-Terminal Segment of Apolipoprotein A-V Undergoes a Lipid-Induced Conformational Change

Apolipoprotein (apo) A-V is a 343-residue, multidomain protein that plays an important role in regulation of plasma triglyceride homeostasis. Primary sequence analysis revealed a unique tetraproline sequence (Pro293-Pro296) near the carboxyl terminus of the protein. A peptide corresponding to the 48-residue segment beyond the tetraproline motif was generated from a recombinant apoA-V precursor wherein Pro295 was replaced by Met. Cyanogen bromide cleavage of the precursor protein, followed by negative affinity chromatography, yielded a purified peptide. Nondenaturing polyacrylamide gel electrophoresis verified that apoA-V(296-343) solubilizes phospholipid vesicles, forming a relatively heterogeneous population of reconstituted high-density lipoprotein with Stokes’ diameters\u3e17 nm. At the same time, apoA-V(296-343) failed to bind a spherical lipoprotein substrate in vitro. Far-UV circular dichroism spectroscopy revealed the peptide is unstructured in buffer yet adopts significant R-helical secondary structure in the presence of the lipid mimetic solvent trifluoroethanol (TFE; 50% v/v). Heteronuclear multidemensional NMR spectroscopy experiments were conducted with uniformly 15N- and 15N/13C-labeled peptide in 50% TFE. Peptide backbone assignment and secondary structure prediction using TALOSþ reveal the peptide adopts R-helix secondary structure from residues 309 to 334. In TFE, apoA-V(296-343) adopts an extended amphipathic R-helix, consistent with a role in lipoprotein binding as a component of full-length apoA-V

Audit Committee Accounting Expertise, Analyst Following, and Market Liquidity

We study the relation between audit committee accounting expertise, analyst following, and market liquidity. Our main results indicate that analyst following increases subsequent to the appointment of an accounting expert to the audit committee. We also provide evidence that accrual quality, as opposed to audit quality or management earnings forecasts, is the channel through which accounting expertise increases analyst following and improves analyst forecast properties. We also show that audit committee accounting expertise is related to higher trading volume and lower liquidity risk, supporting incentives for greater analyst following. Our study extends prior literature by providing evidence that audit committee accounting expertise enhances firms’ information environment beyond the effects it has on financial reporting quality or analysts’ forecast properties. Our study also complements the literature on determinants of analyst following and market liquidity, both of which are related to cost of capital. Results from our study should be useful to firms seeking to enhance analyst following and market liquidity

The Medio Creek Site (41BX1421): National Register Test Excavations, Bexar County Texas

During April 2001, the Center for Archaeological Research of The University of Texas at San Antonio conducted National Register of Historic Places eligibility testing for archeological site 41BX1421, located in southwest Bexar County, Texas, under contract with the Texas Department of Transportation. The investigations were conducted under Texas Antiquities Permit Number 2569. The Phase II testing fieldwork consisted of excavation of five test units across the site to investigate cultural deposits encountered during the previous survey phase. A single sheet midden consisting of burned limestone cobbles was encountered across the majority of the site. In concert with the archeological field investigations, the following special analyses and studies were performed to aid the determination of site integrity and eligibility: radiocarbon, lithic, aboriginal ceramic, vertebrate faunal. and magnetic sediment susceptibility. The synthesis of these analyses has provided adequate data to determine 41BX1421 ineligible for the National Register of Historic Places. It is therefore recommended that the Loop 1604 improvements proceed without further cultural resources investigations

Photochemistry in the arctic free troposphere: Ozone budget and its dependence on nitrogen oxides and the production rate of free radicals

Abstract. Local ozone production and loss rates for the arctic free troposphere (58–85 ◦ N, 1–6 km, February–May) during the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign were calculated using a constrained photochemical box model. Estimates were made to assess the importance of local photochemical ozone production relative to transport in accounting for the springtime maximum in arctic free tropospheric ozone. Ozone production and loss rates from our diel steady-state box model constrained by median observations were first compared to two point box models, one run to instantaneous steady-state and the other run to diel steady-state. A consistent picture of local ozone photochemistry was derived by all three box models suggesting that differences between the approaches were not critical. Our model-derived ozone production rates increased by a factor of 28 in the 1–3 km layer and a factor of 7 in the 3–6 km layer between February and May. The arctic ozone budget required net import of ozone into the arctic free troposphere throughout the campaign; however, the transport term exceeded the photochemical production only in the lower free troposphere (1–3 km) between February and March. Gross ozone production rates were calculated to increase linearly with NOx mixing ratios up to ∼300 pptv in February and for NOx mixing ratio

Camp Maxey IV Archaeological Testing of Six Sites, Lamar County, Texas

From June 14 through July 4, 2001, the Center for Archaeological Research of The University of Texas at San Antonio conducted National Register of Historic Places eligibility testing of six prehistoric archaeological sites (41LR190, 41LR194, 41LR196, 41LR200, 41LR258, and 41LR259) at Camp Maxey, Lamar County, Texas, under contract with the Texas Army National Guard. The investigations were conducted under Texas Antiquities Permit No. 2180. The Phase II testing fieldwork consisted of the excavation of twelve backhoe trenches and nineteen 1 x 1-m test units across the sites to investigate significant cultural deposits encountered during the previous survey phase. In concert with the archaeological field investigations, lithic and native ceramic analyses and magnetic sediment susceptibility studies were performed to aid in the determination of site integrity and eligibility. The synthesis of these analyses has provided adequate data to determine temporal integrity and recommendation of National Register eligibility for site 41LR190. Further cultural resources investigations in the form of Phase III data recovery excavations are thus recommended for this site prior to proposed development. Conversely, due to lack of significance criteria, sites 41LR194, 41LR196, 41LR200, 41LR258, and 41LR259 are recommended as ineligible for inclusion in the National Register and require no further cultural resources investigations

An investigation of South Pole HOx chemistry: Comparison of model results with ISCAT observations

Unexpected high levels of OH and NO were recorded at the South Pole (SP) Atmospheric Research Observatory during the 1998-99 ISCAT field study. Model simulations suggest a major photochemical linkage between observed OH and NO. A detailed comparison of the observations with model predictions revealed good agreement for OH at NO levels between 120 and 380 pptv. However, the model tended to overestimate OH for NO levels < 120 pptv, while it underestimated OH at levels > 380 pptv. The reasons for these deviations appear not to involve NO directly but rather HOx radical scavenging for the low NO conditions and additional HOx sources for the high NO conditions. Because of the elevated levels of NO and highly activated HOx photochemistry, the SP was found to be a strong net source of surface ozone. It is quite likely that the strong oxidizing environment found at the South Pole extends over the entire polar plateau