Cloning, characterization, and sequence analysis of the clcE gene encoding the maleylacetate reductase of Pseudomonas sp. strain B13.

A 3,167-bp PstI fragment of genomic DNA from Pseudomonas sp. strain B13 was cloned and sequenced. The gene clcE consists of 1,059 nucleotides encoding a protein of 352 amino acids with a calculated mass of 37,769 Da which showed maleylacetate reductase activity. The protein had significant sequence similarities with the polypeptides encoded by tcbF of pP51 (59.4% identical positions), tfdF of pJP4 (55.1%), and tftE of Burkholderia cepacia AC1100 (53.1%). The function of TcbF as maleylacetate reductase was established by an enzyme assay.     

Immobilized purple bacteria for light-driven H2 production from starch and potato fermentation effluents

The goal of the study was to show that immobilized purple bacteria could photoproduce H(2) using dark fermentation effluent (FE) as substrate. Simple pretreatment of an inexpensive glass-fiber matrix accelerated the immobilization process. Photobioreactors (PhBR) containing immobilized Rhodobacter sphaeroides GL produced 0.128 L H(2) h(-1) L(-1) of PhBR volume (0.570 L h(-1) L(-1) of matrix) for up to 3 months when continuously fed artificial media with volatile fatty acids (VFAs) or FE from potato and starch fermentations. Hydrogen production was insensitive to NH(4)(+) up to 1 mM and saturated at 8 mM lactate or 1.5% potato FE (diluted in water and supplemented with critical micronutrients). The efficiency of VFA transformation to H(2) was 50-70% of theoretical. At nonlimiting substrate concentrations in artificial media or FE, acetate was utilized before butyrate. High volumetric rates of continuous H(2) photoproduction and stability of the process are advantages of using immobilized cultures. Use of H(2) photoproduction as a polishing step in the treatment of FEs from dark fermentations increased the total amount of H(2) produced from 0.9 to 4.7 mol mol(-1) glucose equivalent in the original potato homogenate.     

Production costs and animal welfare for four stylized hog production systems

Nonhuman animal welfare is arguably the most contentious issue facing the hog industry. Animal advocacy groups influence the regulation of hog farms and induce some consumers to demand more humane pork products. Hog producers are understandably reluctant to improve animal well being unless the premium they extract exceeds the corresponding increase in cost. To better understand the relationship between animal welfare and production costs under different farm systems, this study investigates 4 stylized hog production systems. The results show that increasing animal welfare for all hogs in the United States will increase retail pork prices by a maximum of 2% for a small welfare increase and 5% for a large welfare increase. The cost of banning gestation crates measured by this study is lower than the consumer willingness-to-pay from other studies.     

The Energy Return on Investment for Algal Biocrude: Results for a Research Production Facility

This study is an experimental determination of the energy return on investment (EROI) for algal biocrude production at a research facility at the University of Texas at Austin (UT). During the period of this assessment, algae were grown at several cultivation scales and processed using centrifugation for harvesting, electromechanical cell lysing, and a microporous hollow fiber membrane contactor for lipid separation. The separated algal lipids represent a biocrude product that could be refined into fuel and the post-extraction biomass could be converted to methane. To determine the EROI, a second-order analysis was conducted, which includes direct and indirect energy flows, but does not include energy expenses associated with capital investments. The EROI for the production process evaluated here was significantly less than 1, however, the majority of the energy consumption resulted from non-optimized growth conditions. While the experimental results do not represent an expected typical case EROI for algal fuels, the approach and end-to-end experimental determination of the different inputs and outputs provides a useful outline of the important parameters to consider in such an analysis. The Experimental Case results are the first known experimental energy balance for an integrated algal biocrude production facility, and as such, are expected to be helpful for setting research and development priorities. In addition to the Experimental Case (based on direct measurements), three analytical cases were considered in this work: (1) a Reduced (Inputs) Case, (2) a Highly Productive Case, and (3) a Literature Model. The Reduced (Inputs) Case and the Highly Productive Case speculate the energy use for a similar system in an improved, commercial-scale production setting. The Literature Model is populated with relevant data that have previously been reported in the literature. For the Experimental Case, Reduced Case, Highly Productive Case, and Literature Model, the estimated second-order EROI was 9.2?×?10^?4, 0.074, 0.22, and 0.35, respectively. These results were dominated by growth inputs (96%, 89%, 87%, and 61% of the total energy requirement, respectively). Furthermore, the EROI was adjusted using quality factors that were calculated according to the price of each input, yielding a quality-adjusted EROI that parallels a partial financial return on investment analysis. For the Experimental Case, the Reduced Case, and the Highly Productive Case, the quality-adjusted EROI was 9.2?×?10^?5, 0.013, and 0.36, respectively.     

Sampling and interpretation of psyllid nymph counts in potatoes

Development of effective management practices for insect pests relies heavily on sampling methods to accurately detect and quantify emerging populations. Herein we describe a novel method to extract and count nymphs of potato psyllid, Bactericera cockerelli (?ulc) (Hemiptera: Triozidae), from leaves in commercial fields of potato, Solanum tuberosum L. (Solanaceae). The proposed sampling method (referred to as the leaf washing method, LWM) consists of: (1) immersing samples of infested leaves in cold water to remove dust and sand; (2) immersing leaves in >85 °C water for 5 s; (3) extracting psyllid nymphs from heated water by passing it through a sampling unit composed of a funnel with a fine mesh‐organza fabric inside and attached to a vacuum pump; and (4) removing organza fabric and count psyllid nymphs under a stereoscope. With five sampling units operating simultaneously, one person is able to process and count immatures from about 400 leaf samples in two normal work days. As examples of applications, the LWM was used to characterize: (1) the vertical distribution of potato psyllid nymphs in the potato canopy; and (2) the spatio‐temporal distribution of potato psyllid nymphs in three potato varieties. Using LWM, we showed that psyllid nymphs were most predominant in the middle portion of the canopy and that spatio‐temporal distributions of nymphs varied among potato varieties.     

Structural,biochemical and biophysical characterization of four oxygen-evolving Photosystem II preparations from spinach

Four procedures utilizing different detergent and salt conditions were used to isolate oxygen-evolving Photosystem II (PS II) preparations from spinach thylakoid membranes. These PS II preparations have been characterized by freeze-fracture electron microscopy, SDS-polyacrylamide gel electrophoresis, steady-state and pulsed oxygen evolution, 77 K fluorescence, and room-temperature electron paramagnetic resonance. All of the O₂-evolving PS II samples were found to be highly purified grana membrane fractions composed of paired, appressed membrane fragments. The lumenal surfaces of the membranes and thus the O₂-evolving enzyme complex, are directly exposed to the external environment. Biochemical and biophysical analyses indicated that all four preparations are enriched in the chlorophyll $\text{a}\text{b-}\text{light-harvesting}$ complex and Photosystem II, and depleted to varying degrees in the stroma-associated components, Photosystem I and the CF₁-ATPase. The four PS II samples also varied in their cytochrome f content. All preparations showed enhanced stability of oxygen production and oxygen-rate electrode activity compared to control thylakoids, apparently promoted by low concentrations of residual detergent in the PS II preparations. A model is presented which summarizes the effects of the salt and detergent treatments on thylakoid structure and, consequently, on the configuration and composition of the oxygen-evolving PS II samples.     

Structural localization of the O2-evolving apparatus to multimeric (tetrameric) particles on the lumenal surface of freeze-etched photosynthetic membranes

Isolated appressed chloroplast membranes, highly enriched in photosystem II (PSII) activity, were examined by freeze-etch electron microscopy. The exposed surfaces of these Triton X-100 solubilized membrane fragments correspond to the lumenal or ESs surface of intact stacked thylakoid membrane regions (Dunahay, T. G., L. A. Staehelin, M. Seibert, P. D. Ogilvie, and S. P. Berg. 1984. Biochim. Biophys. Acta. 764:179-193). The sequential removal from this sample of three extrinsic proteins (17, 23, and 33 kD) associated with the O2-evolving apparatus and the concomitant loss of O2 evolution, was related to subtle changes in the height and substructure of characteristic multimeric (often tetrameric) particles that protrude from the ESs membrane surface. After removal of these proteins, the multimeric particles disappeared and dimeric particles of similar diameter but of lesser height (6.1 vs. 8.2 nm in the controls) were observed. Reconstitution of the depleted membrane fragments with the extrinsic proteins led to rebinding of the three proteins, to a 63% recovery of the control rates of O2 evolution, and to the reappearance of the larger multimeric particles. Analysis of the structural changes associated with the loss and rebinding of the extrinsic proteins is consistent with a stoichiometry of one PSII complex for either one or two copies of the 17-, 23-, and 33-kD proteins, and these are symmetrically arranged on the lumenal surface of the complex. These results demonstrate that the multimeric ESs particles correspond to part of the intact O2-evolving apparatus of PSII, thus confirming previous indirect studies relating these particles to PSII. The dimeric particles probably contain the rest of the O2-evolving complex.     

Cellular responses to methylcholanthrene; the role of benzpyrene hydroxylase in the binding of polycyclic hydrocarbon to cytosol macromolecules in fetal rat liver explants

Fetal rat liver was maintained in culture over a period of several days using a simple expiant technique. The addition of 3-methylcholanthrene to the expiants caused a reproducible “induction” of benzpyrene (BP) hydroxylase. In preincubated explants, a 4- to 6-fold elevation in enzyme activity was obtained within 24–36 hr.