Preliminary study on the activity of protease enzymes in Persian sturgeon (Acipenser persicus Borodin, 1897) larvae in response to different diets: effects on growth and survival

The specific activity of alkaline protease, trypsin and pepsin‐like enzymes was measured in yolk sac stage Acipenser persicus larvae and over a 1‐month feeding experiment using live Artemia nauplii (ND), formulated feed (FD) or mixed food (MD). Artemia nauplii group larvae showed significantly higher growth and survival during the first 15 days while FD larvae showed the lowest growth and survival. At day 30, MD larvae exhibited significantly higher growth than the ND group. Alkaline protease activity showed the lowest activity on day 15; the highest activity was observed in the MD group larvae. Pepsin‐like activity showed a drastic increase from day 1 to 5 in all treatments, but remained stable throughout the next 25 days, with the lowest and the highest activity in the FD treatment on day 10 and in the MD treatment on day 30 post‐feeding respectively. Trypsin‐like activity in group ND remained almost the same from day 5 to 30, whereas in groups MD and FD, it decreased significantly from day 10 to 30. The contribution of the naupliar proteases was moderate but effective. Additionally, better performance in Artemia fed sturgeon larvae may also be due to the structure and digestibility of proteins and the food intake stimulation by the nauplii.     

Efficacy of aluminum phosphide tablets to control Richardson’s ground squirrel (Spermophilus richardsonii) populations in southern Saskatchewan, Canada

The objective of this study was to assess, using a capture-recapture program, the effectiveness of aluminum phosphide tablets for control of Richardson’s ground squirrels (Spermophilus richardsonii) in southern Saskatchewan grasslands, from April to July 2007-2009. Aluminum phosphide tablets were tested in study plots in moist or dry soil conditions, where burrow openings had either been marked with a flag (to ensure that all openings would be found and treated) before treatment or left unmarked. In five study plots with moist soil conditions and flagged burrow openings, the mean control level was 80.9 (SD = 6.3) %. In two study plots with dry soil conditions and flagged burrow openings, and one study with moist soil conditions and unflagged burrow openings, control levels were < 60%. It is recommended that aluminum phosphide tablets be used to control Richardson’s ground squirrels in relatively small areas (i.e., < 5 ha) with moist soil conditions and flagged burrow openings, or in specific sites where there are still high concentrations of ground squirrels after an initial treatment with poison food baits.     

Assessment of effects on non-target plants from sulfonylurea herbicides using field approaches

Since their introduction in the early 1980s, there have been a number of field studies conducted to assess the effects of sulfonylurea herbicides on non-target plants (i.e. plants not labeled for use). In these studies a wide variety of plant response assessment techniques have been used to measure effects on non-target plants. This paper examines the relationship of short-term plant response measurements to plant productivity measurements such as yield or quality. Whether short-term plant response measurements have a practical degree of accuracy and precision appropriate for hazard assessment on non-target plants from sulfonylureas is discussed. A comprehensive review of published literature and unpublished field studies of the effects of sulfonylureas on the yield and quality of non-target plant species is reported. When this information is coupled with exposure factors and environmental fate characteristics, the risks to non-target plants from sulfonylureas are similar to those from other herbicides used at higher application rates. © 1998 SCI.     

Evolution of green coffee protein profiles with maturation and relationship to coffee cup quality

Coffee flavor is the product of a complex chain of chemical transformations. The green bean has only a faint odor that is not at all reminiscent of coffee aroma. It contains, however, all of the necessary precursors to generate the unmistakable coffee flavor during roasting. The levels and biochemical status of these precursors may vary in relation to genetic traits, environmental factors, maturation level, postharvest treatment, and storage. To improve our understanding of coffee flavor generation, the sensory and biochemical impact of maturation was assessed. Maturation clearly favored the development of high-quality flavor in the coffee brew. A specific subclass of green coffee beans, however, generated high-quality coffee flavor irrespective of maturation. Biochemical aspects were examined using a dynamic system: immature and mature green coffee suspensions were incubated under air or argon. On the analytical side, a specific pool of flavor precursors was monitored: chlorogenic acids, green coffee proteins, and free amino acids. A link between maturation, the redox behavior of green coffee suspensions, and their sensory scores was identified. Compared to ripe beans, unripe beans were found to be more sensitive to oxidation of chlorogenic acids. Aerobic incubation also triggered the fragmentation or digestion of the 11S seed storage protein and the release of free amino acids.     

Effect of partial harvesting strategies on Artemia biomass production in Vietnamese salt works

The effect of partial harvest strategies on the production of Artemia biomass was evaluated for 12 weeks under Vietnamese salt farm conditions. The initial stocking density was 100 nauplii L^?1. After 3 weeks of inoculation, Artemia adults were partially harvested at intervals of 1, 3, 6 and 9 days starting with an initial quantity of 30 kg ha^?1 day^?1 at first harvest, and then the quantity of harvestable biomass was adjusted according to the standing stock present in the culture pond, combined with the time needed to harvest these quantities and with the weight of biomass harvested in each pond. The results showed that in most cases, the total densities were not significantly different among harvesting frequencies (P>0.05). However, a relatively higher Artemia adult density and its standing stock were better maintained in the 3‐day than in the 1‐day interval, and were significantly higher compared with the other two harvesting frequencies. The total biomass yields were the highest (1587 kg ha^?1) in the 3‐day harvesting interval, followed by 1‐, 6‐ and 9‐day harvesting interludes, corresponding to 1323, 1091 and 975 kg ha^?1 respectively. However, no statistical difference was observed between the 1‐ and the 3‐day interval as well as between the 6‐ and the 9‐day harvest schemes (P>0.05). The results of this study suggest that partial harvest of Artemia biomass performed every 3 days appears to be an appropriate strategy to enhance biomass productivity.     

Multi-atom resonant photoemission: A method for determining near-neighbor atomic identities and bonding

Measurements and theoretical calculations are reported for an interatomic multi-atom resonant photoemission (MARPE) effect that permits direct determination of near-neighbor atomic identities (atomic numbers). MARPE occurs when the photon energy is tuned to a core-level absorption edge of an atom neighboring the emitting atom, with the emitting level having a lower binding energy than the resonant level. Large peak-intensity enhancements of 33 to 105 percent and energy-integrated effects of 11 to 29 percent were seen in three metal oxides. MARPE should also be sensitive to bond distance, bonding type, and magnetic order, and be observable via the secondary processes of x-ray fluorescence and Auger decay.     

Atomic Force Microscopy (AFM) Study of Interactions of HMW Subunits of Wheat Glutenin

Atomic force microscopy (AFM) has been used to study the noncovalent interactions of alkylated HMW subunit 1Dx5 and a M _r 58,000 peptide derived from the central repetitive domain. Both protein and peptide align side‐by‐side to form fibrils, the HMW subunit forming a branched network, and the peptide forming linear rods. The N‐ and C‐terminal domains of the subunit would, therefore, appear to contain regions that interact through noncovalent interactions in the absence of disulfide bond formation. These regions may be of importance in facilitating disulfide bond formation during protein body development.     

Application of thermometric titrations to the study of soil organic matter. I. Simple polyelectrolytes

An introduction to the technique of thermometric titrimetry is provided and its special potentialities for the study of humic substances are discussed. As a prelude to the investigation of the complicated humic systems, the relatively simple polyelectrolytes, PAA and PMA, were first studied. Thermometric titration of these polymeric acids with sodium hydroxide solution gave good end points. Thermometric titration of the salts of these acids with various transition metal ions gave end point breaks corresponding stoichiometrically to charge neutralization of the polyelectrolyte. These thermometric titrations involving the transition metal ions are compared with the corresponding nephelometric titrations.