Dietary TH 6040 alters composition and enzyme activity of housefly larval cuticle

Housefly larvae of 2 days of age were allowed to grow in media containing 0, 0.4, 1.0, or 2.5 ppm TH 6040[1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea] for 3 days prior to analysis of the cuticle for structural components (chitin and protein) or enzymes important in cuticle formation (chitinase and phenoloxidase). As the TH 6040 concentration is increased, the amount of chitin is progressively reduced such that, at 2.5 ppm TH 6040, the level is only 25% of normal. The amount of cuticle protein is unaffected so the protein: chitin ratio increases from 3.4 in the control larvae to 14.3 in 2.5 ppm-treated larvae, an alteration which probably affects the elasticity and firmness of the endocuticle. Dietary TH 6040 at 1.0 ppm increases the cuticle chitinase activity to about 180% and the cuticle phenoloxidase activity to 155% as compared with control larvae, with a further chitinase activity increase to 240% of normal at 2.5 ppm TH 6040. These enzyme changes are expected to hamper the build-up or maintenance of the cuticle chitin and enhance sclerotization of the exocuticle.     

Use of personal protective equipment in a radiology room at a veterinary teaching hospital

The use of personal protective equipment by veterinary workers during radiographic imaging is inconsistent. While the self‐reported use of leaded aprons and thyroid shields approaches 100% in some studies, the use of leaded gloves and eyeglasses is much lower. Previous studies describing personal protective equipment use are based on self‐reporting. Objectives of this prospective, observational study were to describe use of leaded personal protective equipment during radiographic imaging by veterinary workers, and to compare observed use with self‐reported use. Use of leaded personal protective equipment during radiographic imaging by veterinary workers was observed over a 10 week period using two motion‐triggered video cameras, and a questionnaire was then completed by workers on their use of personal protective equipment. Workers restrained the animal during 91.8% (753/820) of exposures. An apron and a securely closed thyroid shield were worn for >99% of studies. Gloves were used correctly for 43.6% (156/358) of radiographic studies. Leaded eyeglasses were worn for 1.7% (6/358) of studies. Correct glove use was more frequent during regular working hours than after‐hours for both veterinarians (odds ratio 32.7, P = 0.001) and veterinary students (odds ratio 75.1, P < 0.001). The number of workers in the room was lower when animals were sedated (P = 0.002) or anesthetized (P = 0.017). Workers overestimated their frequency of glove use (P <0.001). In conclusion, workers use personal protective equipment less frequently in an unsupervised environment, and overestimate their use of personal protective equipment. Use of sedation or anesthesia decreases worker exposure to ionizing radiation.     

DPX-MP062—a potent compound for controlling the Egyptian cotton leafworm Spodoptera littoralis (Boisd.)

The effects of DPX-MP062 [methyl 7-chloro-2,3,4a,5-tetrahydro-2-[methoxycarbonyl(4-trifluoromethoxyphenyl)carbamoyl] indeno[1,2-e][1,3,4] oxadiazine-4a-carboxylate] a broad-spectrum insecticide with a novel mode of action, on the Egyptian cotton leafworm, Spodoptera littoralis, were studied in laboratory experiments. Egg hatch was affected by high concentrations (125 mg AI litre^-1) of DPX-MP062. Larvae that hatched from treated eggs were significantly affected at concentrations of 12·5 mg AI litre^-1 and greater. Larvae were fed castor bean leaves treated with DPX-MP062; 1st-instar larvae were the most susceptible development stage. Pupation and adult formation were determined in assays with 5th-instar larvae. There was strong suppression of adult formation; 65 and 91% at 0·5 and 0·75 mg AI litre^-1, respectively. Highly affected larvae died before pupation; slightly affected ones reached pupation 2–4 days later, were smaller than larvae in the untreated control, and were sometimes unable to develop into normal adults. Comparatively high concentrations (50 and 100 mg AI litre^-1) of the test compound were necessary to affect adults by ingestion, but no effects from contact application could be determined at a concentration of 100 mg AI litre^-1. © 1998 Society of Chemical Industry     

Penaeus monodon larvae can be protected from Vibrio harveyi infection by pre‐emptive treatment of a rearing system with antagonistic or non‐antagonistic bacterial probiotics

This study shows that the disease resistance and survival rate of Penaeus monodon in a larval rearing systems can be enhanced by supplementing with antagonistic or non‐antagonistic probiotics. The antagonistic mode of action of Pseudomonas MCCB 102 and MCCB 103 against vibrios was demonstrated in larval mesocosm with cultures having sufficient concentration of antagonistic compounds in their culture supernatant. Investigations on the antagonistic properties of Bacillus MCCB 101, Pseudomonas MCCB 102 and MCCB 103 and Arthrobacter MCCB 104 against Vibrio harveyi MCCB 111 under in vitro conditions revealed that Pseudomonas MCCB 102 and MCCB 103 were inhibitory to the pathogen. These inhibitory properties were further confirmed in the larval rearing systems of P. monodon. All these four probionts significantly improved larval survival in long‐term treatments as well as when challenged with a pathogenic strain of V. harveyi MCCB 111. We could demonstrate that Pseudomonas MCCB 102 and MCCB 103 accorded disease resistance and a higher survival rate in P. monodon larval rearing systems through active antagonism of vibrios, whereas Bacillus MCCB 101 and Arthrobacter MCCB 104 functioned as probiotics through immunostimulatory and digestive enzyme‐supporting modes of action.     

The response of pyriproxyfen-resistant and susceptible Bemisia tabaci Genn (Homoptera: Aleyrodidae) to pyriproxyfen and fenoxycarb alone and in combination with piperonyl butoxide

Pyriproxyfen was effective against susceptible Bemisia tabaci eggs at a LC₅₀ of 0.003 mg litre⁻¹ and against nymphs at 0.02 mg litre⁻¹. In comparison, eggs of a laboratory selected, pyriproxyfen-resistant B tabaci strain, originating in an Israeli greenhouse, exhibited 6500-fold resistance and nymphs exhibited 1100-fold resistance. Eggs and nymphs of a strain from an Israeli sunflower field exhibited 450 and 210-fold resistance in comparison to the susceptible standard. Fenoxycarb was generally less effective than pyriproxyfen against B tabaci eggs and nymphs but was unaffected by pyriproxyfen resistance. Piperonyl butoxide (PB) was antagonistic to pyriproxyfen, and this increased with increasing pyriproxyfen resistance. PB had no effect on the toxicity of fenoxycarb. Collectively, these data imply that the modes of action of pyriproxyfen and fenoxycarb are distinct, despite the structural similarities of these molecules. Possible reasons for the antagonism of PB against pyriproxyfen are discussed. © 1999 Society of Chemical Industry     

Seasonal water relations in four co-existing native shrub species from Northeastern Mexico

Seasonal xylem water potentials (Ψ, MPa) and their relationship to soil water content and evaporative demand components were studied in the shrub species Acacia amentacea, Celtis ehrenbergiana, Forestiera angustifolia, and Parkinsonia texana var. macra. Predawn (Ψpd) and midday (Ψmd) water potentials were estimated at 15 days intervals, between January 15 and October 30, 2009 using a Scholander pressure bomb at 06:00 h (predawn) and 14:00 h (midday), respectively. During the humid period, Ψpd ranged from ?0.30 MPa (C. ehrenbergiana), to ?0.90 MPa (P. texana). In contrast, over the driest period, Ψpd varied between ?2.18 (P. texana) and ?3.94 MPa (F. angustifolia). At midday, P. texana and F. angustifolia showed the highest (?1.14 MPa) and lowest (?3.38 MPa) Ψ values, respectively. Average soil water content accounted for 35 to 70% of the variation in predawn Ψ. Furthermore, both Ψ reflected the environmental conditions, as indicated by typical correlations observed. The studied shrub species exhibited what seem to be different strategies to avoid damage caused by drought. Thus, P. texana behaved rather as an isohydric plant able to deal well with severe, but short periods of drought. Under exceptionally dry environmental conditions, Ψpd undercut Ψmd values. Similar observations have been made by researchers studying plants in dry ecosystems. All studied native species are recommended for reforestation of the Tamaulipan shrublands, although C. ehrenbergiana and F. angustifolia seem to have limited tolerances for extreme water stress.     

Vaccination of calves with Mycobacteria bovis Bacilli Calmete Guerin (BCG) induced rapid increase in the proportion of peripheral blood γδ T cells

Changes in the proportion of peripheral blood T cell subsets after subcutaneous inoculation of cattle with Mycobacterium bovis Bacille Calmette-Guerin (BCG) were studied. Calves were injected with approximately 8 × 10⁶ BCG bacillus and blood samples collected at weekly intervals for flow-cytometric analyses to determine the proportion of CD4⁺, CD8⁺ and γδ T cells. In addition, whole blood samples were stimulated in vitro with M. bovis purified protein derivative (PPD) and the secreted IFN-γ quantified by ELISA. Results showed cellular and cytokine changes which could be categorized into three phases. The first phase occurred within the first 2 weeks after vaccination involving an increase in proportion of WC1⁺ γδ T cells and a concomitant increase in the secretion of IFN-γ. These two responses peaked at 2 weeks and waned thereafter. The second phase involved an increase in the CD4/CD8 ratio as a result of an increase in the proportion of CD4⁺ T cells between 4 and 6 weeks. The third phase involved a decrease in the CD4/CD8 ratio due to an increase in the proportion of CD8⁺ T cells between 8 and 10 weeks. Surprisingly, the IFN-γ response was associated with changes in the γδ rather than the CD4⁺ or CD8⁺ T cells, suggesting that this cytokine was secreted by γδ-T cells. These results are consistent with the reported ability of γδ T cells to act rapidly and bridging the innate and classically adaptive immune responses.     

Total Oxidative status of Mouse Vitrified Pre-Antral Follicles with Pre-Treatment of Alpha Lipoic Acid

Background: Cryopreservation of pre-antral follicles is a hopeful technique to preserve female fertility. The aim of the present study was to evaluate reactive oxygen species (ROS) and total antioxidant capacity (TAC) levels of mouse vitrified pre-antral follicles in the presence of alpha lipoic acid (ALA). Methods: Isolated pre-antral follicles (140–150 µm in diameter) were divided into vitrified–warmed and fresh groups. Each group was subjected to in vitro maturation with or without ALA for 12 days, followed by adding human chronic gonadotropin to induce ovulation. In vitro fertilization was performed to evaluate their developmental competence. In parallel, the amount of ROS and TAC were assessed after 0, 24, 48, 72, and 96 h of culture by 2'',7''-dichlorofluorescin assay and ferric reducing/antioxidant power assay, respectively. Results: The respective rates of survival, antrum formation, and metaphase II oocytes were significantly higher in ALA-supplemented groups compared to the groups not treated with ALA. TAC and ROS levels were significantly decreased and increased, respectively during the culture period up to 96 h in the absence of ALA in both vitrified and non-vitrified samples. However, with pretreatment of ALA, TAC levels were increased significantly and remained constant up to 96 h in vitrified-warmed pre-antral follicles, while ROS levels completely returned to the level of starting point after 96 h of culture in the presence of ALA. Conclusion: Pretreatment of ALA positively influences development of pre-antral follicles in vitrified and non-vitrified samples through increasing follicular TAC level and decreasing ROS levels. Key Words: Vitrification, Pre-antral follicle, Alpha lipoic acid (ALA), Reactive oxygen species (ROS), Total antioxidant capacity (TAC)     

Evaluation of Deammonification Process by Response Surface Models

The influence of the operational variables on the Anammox process has been generally researched considering each variable separately. However, the optimization of the process also requires the identification of the more significant variables and their possible interactions. Response surface models were successfully applied to evaluate the performance of the Anammox process in a deammonification system (i.e., one-stage biofilm Anammox process) taking into account the combined effects caused by two sets of three variables. Specific Anammox activity was measured by a manometric method and used as the response variable. The obtained models pointed out that the significant variables were the temperature, the value of pH, and the ratio between the unionized species of the substrates (free ammonia and free nitrous acid (FA/FNA)). There were interactions among them caused by chemical equilibriums. Total nitrogen concentration and ammonium concentration were found to be not significant in the tested range. According to the models, the optimum values of temperature, pH, and free ammonia to free nitrous acid ratio within the test ranges were, respectively, 30°C, 7.0, and 0.3. Further research at higher temperatures and lower values of pH and FA/FNA ratios would be necessary in order to find the absolute optimum conditions for the process. The obtained model can be also useful in order to develop control strategies that take into account the significant variables and their optimum ranges. A strategy to control deammonification reactors has been proposed, according to the results of the modeling.