Research Reports from the Programme for Belize Archaeological Project, Volume Three

Table of Contents : Archaeological Investigations of the Programme for Belize Archaeological Project: An Introduction to Volume Three / by Fred Valdez, Jr. and Rissa M. Trachman (p.1-6) -- Mount Allison University: The 2008 Archaeological Program in Northwest Belize / by Grant Aylesworth and Brent Suttie (p.7-14) -- Excavations (2008) at the Los Pisos Courtyard, La Milpa, Belize / by Maria Martinez (p.15-34) -- Investigations (2008) at La Milpa, Belize: Plaza A, Structure 4 / by Rissa M. Trachman (p.35-40) -- An Overview of Archaeological Investigations at Plaza B, La Milpa: The 2008 Field Season / by Brett Houk, Débora Trein, and Gregory Zaro (p.41-60) -- Excavations at La Milp, Belize: Structure 22 / by Gregory Zaro (p.61-70) -- Overview of the 2008 Excavations at Structures 23 and 27, Plaza B, La Milpa, Belize / by Antonio Padilla and Shannon M. Smith (p.71-80) -- Preliminary Investigations East and West of the Acropolis, La Milpa, Belize: The 2008 Field Season / by Brandon S. Lewis (p.81-84) -- The 2008 Field Season at Group A of the Medicinal Trail Site, Northwestern Belize / by David M. Hyde (p.85-96) -- A Late Preclassic Burial at Medicinal Trail: Excavation and Analysis of Burial 3 / by Angeliki Kalamara Cavazos (p.97-110) -- Group B of the Medicinal Trail Site: Select Excavations at Operation 12 / by Deanna M. (p.111-114) -- Group B of the Medicinal Trail Site: Operation 12 (Lots A, Q, and R) / by Lauri McInnis Martin (p.115-120) -- Operation 15: Berm Structures and Water Management at Medicinal Trail (RB 62), Belize / by Erin E. Gill (p.121-126) -- Medicinal Trail Archaeology: Investigations at Operation 13 / by Maia Dedrick (p.127-142) -- Excavations at the Medicinal Trail Site (2008): Operation 14 / by Madelyn Percy (p.143-144) -- RB 70: The 2008 Investigations (p.145-148) -- Excavations at La Milpa Easts and the Aguada Lagunita Elusiva: The 2008 Field Season / by Estella Weiss-Krejci (p.149-168) -- Plan for Phase Two Research at Wari Camp (RB 56): Household, Neighborhood, and Ward in the Prehispanic Maya City / by Laura Levi (p.167-176) -- Experimental Pottery Studies in Belize / by Sharon Hankins (p.177)Texas Archeological Research Laborator

Postsynaptic α1-Adrenergic vasoconstriction is impaired in young patients with vasovagal syncope and is corrected by nitric oxide synthase inhibition

BACKGROUND: Syncope is a sudden transient loss of consciousness and postural tone with spontaneous recovery; the most common form is vasovagal syncope (VVS). During VVS, gravitational pooling excessively reduces central blood volume and cardiac output. In VVS, as in hemorrhage, impaired adrenergic vasoconstriction and venoconstriction result in hypotension. We hypothesized that impaired adrenergic responsiveness because of excess nitric oxide can be reversed by reducing nitric oxide. METHODS AND RESULTS: We recorded cardiopulmonary dynamics in supine syncope patients and healthy volunteers (aged 15-27 years) challenged with a dose-response using the α1-agonist phenylephrine (PE), with and without the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine, monoacetate salt (L-NMMA). Systolic and diastolic pressures among control and VVS were the same, although they increased after L-NMMA and saline+PE (volume and pressor control for L-NMMA). Heart rate was significantly reduced by L-NMMA (P<0.05) for control and VVS compared with baseline, but there was no significant difference in heart rate between L-NMMA and saline+PE. Cardiac output and splanchnic blood flow were reduced by L-NMMA for control and VVS (P<0.05) compared with baseline, while total peripheral resistance increased (P<0.05). PE dose-response for splanchnic flow and resistance were blunted for VVS compared with control after saline+PE, but enhanced after L-NMMA (P<0.001). Postsynaptic α1-adrenergic vasoconstrictive impairment was greatest in the splanchnic vasculature, and splanchnic blood flow was unaffected by PE. Forearm and calf α1-adrenergic vasoconstriction were unimpaired in VVS and unaffected by L-NMMA. CONCLUSIONS: Impaired postsynaptic α1-adrenergic vasoconstriction in young adults with VVS can be corrected by nitric oxide synthase inhibition, demonstrated with our use of L-NMMA

Expression, purification and characterisation of recombinant peptide:N-glycosidase F. : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Biochemistry at Massey University

PNGase F (Peptide-N4-(N-acetyl-D-glucosaminyl) asparagine amidase F) is an amidohydrolase isolated from the extracellular medium of the Gram-negative bacterium Flavobacterium meningosepticum. The 34.8-kDa enzyme catalyses the complete and intact cleavage of asparagine-linked oligosaccharide chains from their associated proteins. A T7 promoter-based E. coli expression system was developed in which PNGase F was expressed as a fusion protein with a leader sequence from the ompA gene. The hexa-histidine-tagged PNGase F was correctly processed and exported to the E. coli periplasm and had a calculated molecular weight of 36.2 kDa. A single step purification using immobilised metal affinity chromatography yielded 8 mg of pure protein per litre of culture. The sequence of the PNGase F coding region from the CDC strain 3352 of F. meningosepticum was found to differ from a published sequence from another strain of the bacterium (ATCC 33958) in 57 positions. These differences between the two strains result in eight amino acid substitutions, which are mostly conservative in nature and are on the surface of the protein. Moreover, three potential N-glycosylation sites not present in the ATCC strain 33958 were detected in CDC strain 3352. The recombinant enzyme has similar characteristics of the native enzyme with a pH optimum of 8.5 and is strongly inhibited by Ag+, Cu2+, Fe3+ ions but not by sulfhydryl-targeting agents such as DTT and NEM. This indicates inhibition by these ions is probably through interactions with a histidine residue at position 193 that may be involved in substrate recognition or catalysis. The specific activity of the native PNGase F is about four times that of the recombinant protein which may be contributed to inhibition by components of the CompleteTM protease inhibitor tablets used in the enzyme preparation or due to modifications for cloning and purification. Using a discontinuous assay and a non-labelled 11-mer ovalbumin-derived glycopeptide as substrate, a rough estimate of the Michaelis constant (Km) for the recombinant PNGase F was determined to be 2.1 μM. An intriguing observation with the activity assays was the apparent product inhibition of enzyme activity and the inhibitor may be either peptide and/or glycan components, which require further investigations into the cause of the inhibition

Development of an impact- and solvent-resistant thermoplastic composite matrix, phase 3

The polyimide from BTDA 1,6-hexanediamine and m-phenylenediamine was selected from a prior study for the present study. Methods to prepare prepreg which would provide low void composites at low molding pressures from the thermoplastic polyimide were studied. Cresol solutions of the polyimide were applied to a balanced weave carbon fabric and the cresol removed prior to composite molding. Low void composites were prepared from smoothed prepregs at high pressures (34.5 MPa) and temperatures as low as 260 C. Lower molding pressures lead to higher void composites. Need for a lower melt viscosity in the neat resin is suggested as a requirement to achieve low void composites at low pressures. Some mechanical properties are included

The emergence and fate of horizontally acquired genes in Escherichia coli

Bacterial species, and even strains within species, can vary greatly in their gene contents and metabolic capabilities. We examine the evolution of this diversity by assessing the distribution and ancestry of each gene in 13 sequenced isolates of Escherichia coli and Shigella. We focus on the emergence and demise of two specific classes of genes, ORFans (genes with no homologs in present databases) and HOPs (genes with distant homologs), since these genes, in contrast to most conserved ancestral sequences, are known to be a major source of the novel features in each strain. We find that the rates of gain and loss of these genes vary greatly among strains as well as through time, and that ORFans and HOPs show very different behavior with respect to their emergence and demise. Although HOPs, which mostly represent gene acquisitions from other bacteria, originate more frequently, ORFans are much more likely to persist. This difference suggests that many adaptive traits are conferred by completely novel genes that do not originate in other bacterial genomes. With respect to the demise of these acquired genes, we find that strains of Shigella lose genes, both by disruption events and by complete removal, at accelerated rates

Food-web structure in relation to environmental gradients and predator-prey ratios in tank-bromeliad ecosystems

Little is known of how linkage patterns between species change along environmental gradients. The small, spatially discrete food webs inhabiting tank-bromeliads provide an excellent opportunity to analyse patterns of community diversity and food-web topology (connectance, linkage density, nestedness) in relation to key environmental variables (habitat size, detrital resource, incident radiation) and predators: prey ratios. We sampled 365 bromeliads in a wide range of understorey environments in French Guiana and used gut contents of invertebrates to draw the corresponding 365 connectance webs. At the bromeliad scale, habitat size (water volume) determined the number of species that constitute food-web nodes, the proportion of predators, and food-web topology. The number of species as well as the proportion of predators within bromeliads declined from open to forested habitats, where the volume of water collected by bromeliads was generally lower because of rainfall interception by the canopy. A core group of microorganisms and generalist detritivores remained relatively constant across environments. This suggests that (i) a highly-connected core ensures food-web stability and key ecosystem functions across environments, and (ii) larger deviations in food-web structures can be expected following disturbance if detritivores share traits that determine responses to environmental changes. While linkage density and nestedness were lower in bromeliads in the forest than in open areas, experiments are needed to confirm a trend for lower food-web stability in the understorey of primary forests

Pit latrines and their impacts on groundwater quality: a systematic review.

BackgroundPit latrines are one of the most common human excreta disposal systems in low-income countries, and their use is on the rise as countries aim to meet the sanitation-related target of the Millennium Development Goals. There is concern, however, that discharges of chemical and microbial contaminants from pit latrines to groundwater may negatively affect human health.ObjectivesOur goals were to a) calculate global pit latrine coverage, b) systematically review empirical studies of the impacts of pit latrines on groundwater quality, c) evaluate latrine siting standards, and d) identify knowledge gaps regarding the potential for and consequences of groundwater contamination by latrines.MethodsWe used existing survey and population data to calculate global pit latrine coverage. We reviewed the scientific literature on the occurrence of contaminants originating from pit latrines and considered the factors affecting transport of these contaminants. Data were extracted from peer-reviewed articles, books, and reports identified using Web of ScienceSM, PubMed, Google, and document reference lists.DiscussionWe estimated that approximately 1.77 billion people use pit latrines as their primary means of sanitation. Studies of pit latrines and groundwater are limited and have generally focused on only a few indicator contaminants. Although groundwater contamination is frequently observed downstream of latrines, contaminant transport distances, recommendations based on empirical studies, and siting guidelines are variable and not well aligned with one another.ConclusionsIn order to improve environmental and human health, future research should examine a larger set of contextual variables, improve measurement approaches, and develop better criteria for siting pit latrines