Effects of peroral insulin and glucose on circulating insulin-like growth factor-I, its binding proteins and thyroid hormones in neonatal calves

There is disagreement in the literature about the ability of neonatal calves to absorb perorally administered insulin. This study evaluated the absorption of a bolus of insulin administered alone or with an energy souce and its effects on the circulating insulin-like growth factor system and thyroid hormones in newborn Holstein-Friesian calves. Within 1 h of dosing, mean serum insulin and triiodothyronine (T3) concentrations had increased considerably, whether the insulin was applied alone (n = 4) or together with glucose (n = 4), accompanied by marked hypoglycemia. No significant changes were observed in control calves (n = 4) given the vehicle solution. Increased serum glucose and T3 concentrations with no change in insulinemia occurred in a 4th group of calves given glucose alone. At 32 h of age and after 3 meals of colostrum there were no differences in glycemia, insulinemia, or proteinemia among the 4 groups of calves examined. Mean serum insulin-like growth factor-I (IGF-I) tended to decrease over this period in the control group. The decrease was more pronounced in the insulin-treated group but absent in both groups that received glucose. These differences were associated with equivalent differences in abundance of the 40-45K IGF-binding protein-3 (IGFBP-3); however, lower molecular mass IGFBPs were not affected. The results show that a pharmacological peroral dose of insulin can lead to rapid systemic alterations in the IGF/IGFBP system in neonatal calves that can be modified by simultaneous administration of a small energy supply in the form of glucose.     

Effect of nicosulfuron on plant traits of Xanthium strumarium

Journal of Plant Diseases and Protection - Field experiments were conducted in 2008 and 2009 at the Experimental Field Institute Padinska Skela PKB Agroe-konomik, near Belgrade, to quantify effects...     

Application of a new sediment contact test with <Emphasis Type="Italic">Myriophyllum aquaticum</Emphasis> and of the aquatic <Emphasis Type="Italic">Lemna</Emphasis> test to assess the sediment quality of Lake Skadar

Goal, Scope and Background  Situated in the transboundary belt between Montenegro and Albania, Lake Skadar is the largest freshwater reservoir in Southeastern Europe. Because of the wide range of endemic, rare or endangered plant and animal species it supports, Lake Skadar and its extensive adjacent wetlands are internationally recognised as a site of significance and importance (Ramsar site). Within the last 10 to 20 years, Lake Skadar was exposed to intensive pollution. For the assessment of the ecotoxic load of the sediments sampled in Lake Skadar, a triad approach was recently applied. Overall, a complex spectrum of ecotoxic loads was elucidated. The aim of the present study was to use plant-based bioassays for assessing the sediment quality of Lake Skadar in order to facilitate and complement the triad test battery. The newly developed sediment contact test with Myriophyllum aquaticum and the aquatic growth inhibition test with Lemna minor were applied to native sediments and pore water, respectively, allowing the investigation of different toxicity-effects caused by particle-bound pollutants as well as pollutants in the interstitial water. This investigation is the first application of the novel sediment contact test with Myriophyllum aquaticum to lake sediments. Methods  Sediment samples were taken from nine selected sites at Lake Skadar and investigated by the sediment contact assay with Myriophyllum aquaticum. The pore water was extracted from these sediment samples to be analysed in the aquatic growth inhibition test with Lemna minor. The results of the sediment contact tests were compared with each other and with those of the aquatic growth inhibition test. Results and Discussion  Both applied macrophyte biotests revealed distinct changes in the growth behaviour of the two macrophytes subsequent to the exposure to the investigated natural sediments of Lake Skadar. The Myriophyllum sediment contact test revealed significant toxicity in the sediment samples from Radus and Kamenik, whereas the aquatic Lemna test showed inhibition effects for the samples from Sterbeq, Plavnica and Kamice. Data obtained with the newly developed Danio rerio contact test and the Arthrobacter globiformis contact test confirmed the Myriophyllum results. Analyses of the heavy metal content in the sediments revealed low or moderate contamination levels. Correlation analyses between the content of heavy metals in the sediments and growth inhibition of Myriophyllum aquaticum showed a significant correlation between Cr concentrations and growth inhibition. Comparable findings are available for a German river system. In contrast, no significant correlation between inhibition rates and concentration of metals could be observed with Lemna minor. Conclusions  It was shown that the newly developed sediment contact test with Myriophyllum aquaticum is applicable to lake sediments. In both the sediment contact test with Myriophyllum aquaticum on whole sediments and the aquatic growth inhibition test with Lemna minor on pore water, plant growth was influenced by the natural sediments and its components. Therefore, both test systems were found to be suitable for the detection of phytotoxic effects upon exposure to sediments. Myriophyllum aquaticum as test organism of the contact test grows directly in the sediment without an additional water-layer. Thus, it is able to detect toxicity caused by particle-bound phytotoxic substances as well as pore water-related contamination, while the floating Lemna minor can only detect effects emanating from pore water. Significant differences of the results were observed between these two test systems and, accordingly, the two different exposure scenarios. Hence, none of the tests can replace the other one and, as a consequence, both should be included into a test battery for the assessment of sediment toxicity. Recommendations and Perspectives  Both plant assays were shown to be reliable tools for the evaluation of the eco-toxicological risk potentials of pore water and solid-phase sediment. They should become a complement to the standardised test battery generally used for comprehensive hazard assessment. ESS-Submission Editor: Dr. Ulrike Kammann (ulrike.kammann@ifo.bfa-fisch.de)     

Single and simultaneous exposure of acetylcholinesterase to diazinon, chlorpyrifos and their photodegradation products

In vitro inhibition of electric eel acetylcholinesterase (AChE) by single and simultaneous exposure to organophosphorus insecticides diazinon and chlorpyrifos, and their transformation products, formed due to photoinduced degradation, was investigated. Increasing concentrations of diazinon, chlorpyrifos and their oxidation products, diazoxon and chlorpyrifos-oxon, inhibited AChE in a concentration-dependent manner. IC₅₀ (20 min) values, obtained from the inhibition curves, were (in mol/l): (5.1 ± 0.3) × 10⁻⁸, (4.3 ± 0.2) × 10⁻⁶ and (3.0 ± 0.1) × 10⁻⁸ for diazoxon, chlorpyrifos and chlorpyrifos-oxon, respectively, while maximal diazinon concentration was lower than its IC₅₀ (20 min). Calculated K_I values, in mol/l, of 7.9 × 10⁻⁷, 9.6 × 10⁻⁶ and 4.3 × 10⁻⁷ were obtained for diazoxon, chlorpyrifos and chlorpyrifos-oxon, respectively. However, 2-isopropyl-4-methyl-6-pyrimidinol (IMP) and 3,5,6-trichloro-2-pyridinol, diazinon and chlorpyrifos hydrolysis products, did not noticeably affect the enzyme activity at all investigated concentrations. Additive inhibition effect was achieved for lower concentrations of the inhibitors (diazinon/diazoxon ?1 × 10⁻⁴/1 × 10⁻⁸ mol/l i.e., chlorpyrifos/chlorpyrifos-oxon ?2 × 10⁻⁶/3 × 10⁻⁸ mol/l), while an antagonistic effect was obtained for all higher concentrations of the organophosphates. Inhibitory power of 1 × 10⁻⁴ mol/l diazinon irradiated samples can be attributed mostly to the formation of diazoxon, while the presence of non-inhibiting photodegradation product IMP did not affect diazinon and diazoxon inhibitory efficiencies.     

Gene Flow from Herbicide-Resistant Sunflower Hybrids to Weedy Sunflower

Journal of Plant Diseases and Protection - Weedy forms of cultivated sunflower (Helianthus annuus) are invasive species widely distributed in several regions of the world and are commonly...     

Incidence and molecular characterization of potato leaf roll virus in seed potato production in Serbia

European Journal of Plant Pathology - The distribution and frequency of potato leaf roll virus in the four most important potato growing regions in Serbia were studied during the seven years...     

Morphophysiological traits and atrazine sensitivity in Chenopodium album L

BACKGROUND: A Chenopodium album L. biotype surviving in atrazine-treated Serbian corn fields (VC) was compared against atrazine-susceptible (S) and atrazine-resistant (R) standards.RESULTS: Atrazine (2 kg ha(-1)) killed S and VC shoot biomass 15 days after treatment (DAT), but R was only suppressed by 42% and survived 8 kg ha(-1). Atrazine at 2 kg ha(-1) only inhibited VC height by 60% as against 100 and 0% for S and R respectively. Chlorophyll fluorescence (Fv/Fm) and transpiration were insensitive to atrazine in R, but were inhibited by 90 and 100% in S and by 50 and 60% in VC respectively. Decline of Fv/Fm after 2 kg ha(-1) atrazine was stabilized at 3 DAT for the VC biotype.CONCLUSION: A toxicity mitigation mechanism could have facilitated VC survival in an atrazine-treated field. Further knowledge on this mechanism is needed to establish if surviving VC plants are indicators of atrazine resistance evolution in these Serbian corn fields. Variables related to foliar function provided better detection of weed mechanisms to survive herbicide action than the usual shoot biomass measurements.