The Control of Reactive Oxygen Species Influences Porcine Oocyte In Vitro Maturation

The aim of this study was to examine the effect of varying intracellular reactive oxygen species (ROS) levels during oocyte in vitro maturation with enzymatic ROS production systems (xanthine + xanthine oxidase or xanthine + xanthine oxidase + catalase), scavenger systems (catalase or superoxide dismutase + catalase) or cysteine on porcine oocyte maturation. Oocyte ROS levels showed an increase when H₂O₂ or O₂?^‐ production systems were added to the culture medium (p < 0.05). On the other hand, the presence of ROS scavengers in the maturation medium did not modify oocyte ROS levels compared with the control after 48 h of maturation, but the addition of cysteine induced a decrease in oocyte ROS levels (p < 0.05). The ROS production systems used in this work did not modified the percentage of oocyte nuclear maturation, but increased the decondensation of sperm head (p < 0.05) and decreased the pronuclear formation (p < 0.05). In turn, the addition of O₂?^‐ and H₂O₂ scavenging systems during in vitro maturation did not modify the percentage of oocytes reaching metaphase II nor the oocytes with decondensed sperm head or pronuclei after fertilization. However, both parameters increased in the presence of cysteine (p < 0.05). The exogenous generation of O₂?^‐ and H₂O₂ during oocyte in vitro maturation would not affect nuclear maturation or later sperm penetration, but most of the spermatozoa cannot progress to form the pronuclei after fusion with the oocyte. The decrease in endogenous ROS levels by the addition of cysteine would improve pronuclear formation after sperm penetration.     

Pesticide use and residues on Queensland wool

Objective To determine practices for control of louse infestation and blowfly strike in Queensland sheep flocks that are associated with organophosphorous and synthetic pyrethroid residues on wool.
Design Information on residues was obtained from a survey of Queensland wool clips. Information on pesticide use was obtained from a trace-back postal survey. The association between pesticide use and residues was assessed using generalised linear models, controlling for potential confounding by flock location.
Procedure Between 1995 and 1997 Queensland wool clips were randomly sampled. Samples were tested for the presence and amount (mg per kg of greasy wool) of organophosphorous and synthetic pyrethroid pesticides. A questionnaire seeking information on flock characteristics and pesticide use was sent to the manager of each flock from which a wool sample was tested.
Results The median amount of OP and SP residue was 0.8 and 0.25 mg/kg, respectively, and 91 and 95% of wool samples contained < 8 mg/kg of OP and SP residues, respectively. The frequency of OP pesticide use for louse control was significantly (P = 0.005) associated with mean OP residue amount, and the timing of SP use for louse control, in relation to shearing, was significantly (P < 0.001) associated with mean SP residue amount.
Conclusion Most Queensland wool clips have acceptable amounts of residues after the use of OP and SP pesticides, but wool growers can further reduce residues by effectively controlling louse infestation with pesticide applications early after shearing and the use of non-chemical methods of ectoparasite control.     

Effects of Nitrogen Rate and Harvest Moisture Content on Physicochemical Properties and Milling Yields of Rice

Field studies were conducted from 2011 to 2013 near Stuttgart, Arkansas. The impacts of nitrogen rate (0, 45, 90, 135, and 180 kg of N/ha) and harvest moisture content (HMC) (23, 19, and 15%, wet basis) on physicochemical properties and milling yields were determined. Trends were similar for the cultivars evaluated: Cheniere, CL XL745, and Wells. Milled rice yields were only minimally impacted by either N rate or HMC level. Increasing N rate reduced kernel length and thickness of brown rice, chalkiness of brown rice and head rice, and viscosities of head rice flour, and it increased brown rice and head rice crude protein content and head rice yield (HRY). In terms of milling yields and head rice functionality, these data suggest that N rates as low as 90 kg of N/ha could be utilized, should production recommendations be changed. Significant interactions between N rate and HMC level were infrequent and were associated with the 0 kg of N/ha rate, unrealistic for rice production. Decreasing HMC from 23 to 19% reduced kernel length and thickness and increased crude protein content and chalkiness; further decreasing HMC to 15% also increased kernel fissuring and decreased HRY.     

Detection of castor contamination by real-time polymerase chain reaction

Due to the potential for intentional contamination of food with crude preparations containing ricin, a real-time PCR method was developed for the detection of castor plant material in ground beef. One primer pair was identified and confirmed to be castor-specific and efficient for amplification of ricin in DNA extracts from castor or beef matrices. Of three different DNA extraction protocols compared, the hexadecyltrimethylammonium bromide (CTAB) method yielded the highest quality of DNA for QPCR assay. The detection limit for castor contamination in ground beef samples was <0.001% (<10 microg of castor acetone powder per gram of beef, corresponding to 0.5 microg of ricin), indicating excellent sensitivity for the assay, well below the threshold for oral toxicity.