Calcium, calmodulin, and CaMKII requirement for initiation of centrosome duplication in Xenopus egg extracts

Aberrant centrosome duplication is observed in many tumor cells and may contribute to genomic instability through the formation of multipolar mitotic spindles. Cyclin-dependent kinase 2 (Cdk2) is required for multiple rounds of centrosome duplication in Xenopus egg extracts but not for the initial round of replication. Egg extracts undergo periodic oscillations in the level of free calcium. We show here that chelation of calcium in egg extracts or specific inactivation of calcium/calmodulin-dependent protein kinase II (CaMKII) blocks even initial centrosome duplication, whereas inactivation of Cdk2 does not. Duplication can be restored to inhibited extracts by addition of CaMKII and calmodulin. These results indicate that calcium, calmodulin, and CaMKII are required for an essential step in initiation of centrosome duplication. Our data suggest that calcium oscillations in the cell cycle may be linked to centrosome duplication.     

Chemical Usurpation of a Nest by Paper Wasp Parasites

The paper wasp Polistes atrimandibularis is an obligatory social parasite of another Polistes species, P. biglumis bimaculatus. To control the host nest, the parasite sequentially changes the composition of its chemical signature, the cuticular hydrocarbons, during the colonial cycle. Gas chromatography-mass spectrometry of the cuticular hydrocarbons at every stage of the cycle showed that the parasite can switch on and off an entire chemical family, namely, the unsaturated hydrocarbons. In this way the parasite can match the host signature at a critical moment of the colonial cycle.     

Effects of IGF‐1 on In Vitro Culture of Bovine Preantral Follicles are Dose‐Dependent

This study aimed at assessing the effect of different concentrations of the growth factor similar to insulin 1 (IGF‐1) in the development, survival and ultrastructure of the bovine preantral follicles cultured in situ. Fragments of bovine ovarian cortical tissue were cultured during 1 and 7 days in 1 ml of α‐MEM⁺, supplemented with different concentrations of human recombinant IGF‐1 (0, 30, 70 and 100 ng/ml), in an incubator at 37°C and 5% of CO₂ in 24‐well plates with total replacement of the medium every 2 days. Non‐cultured ovarian fragments (control) and ovarian fragments cultured during 1 and 7 days were processed for classic histology, mechanical isolation and electron transmission microscopy (ETM). Parameters such as normality, viability, activation, development, diameter and ultrastructure were evaluated. All statistical analyses were carried out using sas Version 9.2. The results showed that the percentage of follicles morphologically normal in the IGF‐1 30 ng/ml treatment was similar to the fresh control (p > 0.05) both on the day 1 and on the day 7 of in vitro culture. In the viability analysis, the cultured treatments maintained the percentage of viable follicles during the entire culture period (p > 0.05). After 7 days of culture, the IGF‐1 30 ng/ml treatment showed higher percentages of developing follicles (48.33%) than those of the fresh control (22.22%) and the cultured treatments (p < 0.05). Also, after 7 days of culture, IGF‐1 30 ng/ml presented a higher follicular diameter when compared to the control and other concentrations of IGF‐1 tested. Ultrastructurally, the non‐cultured control and IGF‐1 30 ng/ml, after 7 days of culture, showed conserved oocytes, nuclei and organelles. Hence, it is concluded that IGF‐1 30 ng/ml was the most efficient concentration for the development of bovine preantral follicles cultured in vitro.     

Clearance of para-aminohippuric acid in wethers consuming locoweed

AIM: To validate the use of para-aminohippuric acid (PAH) as a marker for measuring blood flow in wethers consuming a mixed diet of locoweed and blue grama hay.

METHODS: Fourteen sheep, stratified by bodyweight (BW), were assigned to one of three treatments: 0.8 mg swainsonine (SW)/kg BW (HI), 0.2 mg SW/kg BW (LO), and no SW (Control). Sheep were fed various ratios of locoweed and blue grama hay to deliver SW treatments, for 28 days prior to infusion of PAH. Concentrations of SW and activities of alkaline phosphatase (Alk-P) and aspartate aminotransferase (AST) in serum were measured to confirm exposure to SW and subclinical intoxication. A single 20-ml injection of 5% PAH was delivered into the jugular vein after subclinical intoxication had been achieved. Blood samples were collected and serum analysed for PAH immediately prior to injection, then every 5 min from 5–30 min, and every 10 min from 30–60 min, following injection of PAH.

RESULTS: Effective delivery of SW was evident from the greater concentrations of SW measured in the serum of HI compared with LO animals (p<0.05). No significant differences were detected in the rate of elimination (range 0.097–0.108 L/min), elimination half-life (range 6.62–7.24 min), apparent volume of distribution for the central compartment (range 7.14–9.72 L), and clearance (range 0.73–0.92 L/min) of PAH, between treatments.

CONCLUSIONS: Subclinical intoxication with SW did not affect the pharmacokinetics of PAH. Thus, use of downstream dilution of PAH is a valid method to determine the rate of blood flow in nutrient flux experiments that involve consumption of locoweed.     

Behavioural and EEG changes in sheep in response to painful acute electrical stimuli

Objective To measure acute pain in sheep, based on a human pain model, and examined changes in both electroencephalogram frequency spectrum and behavioural responses to increased electrical stimulation in sheep. Design Analysis of variance (treatment and animal effects) for stimulus intensity where each animal received each electric shock treatment given in the order 0, 5,10 and 20 mA. Procedure Eight sheep with electrodes implanted over the surface of the brain were examined for escape-avoidance and electroencephalogram responses to four levels of electrical stimulation from 0–20 mA. Results With increasing stimulus intensity at the time of feeding, the sheep were more hesitant to return to the feeder or remain near the feeder following stimulation. There was little difference between the 0 and 5 mA stimuli for any of the behaviour variables (P > 0.05). However, there were marked increases in the time taken to re-approach the feeder after receiving an electric shock of 5 mA and of 20 mA (P < 0.05; mean values 3 and 119 s, respectively) and remaining near the feeder for 5 s (P < 0.001; mean values 10 and 167 s, respectively). Following the stimulus, there was an overall increase in the electroencephalogram power spectrum in the first four seconds, which then rapidly returned to normal. In particular, the 20 mA stimulus resulted in higher absolute power values than in the control (0 mA) treatment for delta 2 (P < 0.001), theta 1 (P < 0.05), theta 2 (P < 0.05), alpha 1 (P < 0.001), alpha 2 (P < 0.001) and beta 1 (P < 0.01) band-widths. Similarly, for the 10 mA stimulus, the absolute power values were greater than the control treatment for delta 2 (P < 0.05), alpha 1 (P < 0.01), alpha 2 (P < 0.001) and beta 1 (P < 0.01) bandwidths. Conclusion The experiment suggests that a human acute pain model is applicable to sheep and that these electroencephalogram changes may provide a good measure of acute pain in sheep.     

Fasciola hepatica infection in farmed emus (Dromaius novaehollandiae)

Objective To describe two cases of infection with Fasciola hepatica i n young farmed emus, subacute and chronic fasci-olosis and a response to treatment of the flock with albenda-zole.
Procedure Gross lesions were found at necropsy and hepatic lesions in microscopic examination. The parasite recovered from one emu was identified by its morphological characteristics and an egg count reduction test was carried out after treatment of the flock with albendazole.
Results Hepatic lesions resembling subacute and chronic fasciolosis of ruminants were identified. An adult fluke was recovered from the liver of one of the birds and was identified as F hepatica . The eggs of the fluke were irregular in shape and size. No fluke eggs were identifiable in faeces of live emus 10 days after treatment of the flock with albendazole at a dose of 10 mg/kg.
Conclusions This is the first reported case of infection with F hepatica i n farmed emus and the first report of the occurrence of Fasciola infection is the class Aves. The irregular shape and size of the eggs may be attributable to infection of an aberrant host. Treatment with albendazole eliminated eggs from the faeces of the flock.     

Superior check ligament desmotomy for treatment of superficial digital flexor tendonitis in Thoroughbred and Standardbred horses

Summary Bilateral superior check ligament desmotomy was performed on 31 Thoroughbred and 17 Standardbred horses as the sole method of treatment for superficial digital flexor tendonitis. Horses resumed racing between 6 and 19 months after surgery. Horses that were able to compete in 5 or more races without injury to the tendon again were considered to have had a successful return to racing. Twenty-five Thoroughbreds were suitable for later study and 13 of these (52%) raced on 5 or more occasions. Fifteen Standardbreds were suitable for later study and 10 of these (66%) raced on 5 or more occasions. Within the racing industry it is generally thought that about 20 to 30% of horses with superficial digital flexor tendonitis can return to racing after a prolonged rest. The results of this study suggest that bilateral superior check ligament desmotomy may improve the prognosis for a horse returning to racing after injury to the superficial digital flexor tendon.