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Angela M. Watson Janice E. Chambers 《Journal of biochemical and molecular toxicology》1996,11(6):263-268
Aliesterases (carboxylesterases) are serine esterases that can serve a protective role for the target acetylcholinesterase (AChE) during organophosphorus insecticide intoxication because the former esterases are alternate phosphorylation sites. The levels of aliesterase activity in liver and plasma and AChE activity in brain regions were investigated after the intravenous administration of paraoxon (P = O) into female rats. The rats were pretreated intraperitoneally with β-naphthoflavone (BNF), which decreases hepatic aliesterase activity following a 3 day in vivo treatment, and/or tri-o-totyl phosphate (TOTP) to inhibit aliesterases. The liver aliesterases were inhibited less by P = O in BNF-treated rats than in control rats, which suggests that either BNF exposure may have resulted in aliesterases that are less sensitive to P = O inhibition or BNF may have altered P = O's availability. The BNF treatment did not seem to alter the degree of inhibition of the brain AChE activity following the low dosage of paraoxon (0.04 mg/kg). However, the brain AChE activity in the P = O/TOTP/BNF-treated rats was lower than that in the P = O/TOTP-treated rats, suggesting that BNF also caused changes in systems affecting the disposition of P = O in addition to the changes in the hepatic aliesterases. At the high dosage of paraoxon (0.12 mg/kg), the AChE and aliesterase activities showed a pattern similar to that of the low dosage. This suggests that the aliesterases, as altered by BNF exposure, even when nearly completely inhibited, did not alter the response of the target enzyme, AChE, and, therefore, the magnitude of the toxic response. © 1997 John Wiley & Sons, Inc. J Biochem Toxicol 11: 263–268, 1997. 相似文献
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The adult habits and emergence of Dolania americana (Ephemeroptera: Behningiidae) were studied at the Blackwater River in Northwestern Florida. The adult life is crepuscular, beginning about 1½ hrs before sunrise with emergence of male subimagos. Males molt to imagos, female subimagos emerge, males and females mate, and females begin to oviposit in a fairly precise time sequence over the following hour. Only a few adults survive past sunrise. Females never molt to imagos and are polymorphic. Emergence is seasonal and begins between the end of April and the middle of May, depending on climatic conditions. Emergence is photoperiodically entrained. Water temperature is a phase setter and light intensity acts as a synchronizer. 相似文献
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Janice A. Williams Simon Y. Long Xiankun Zeng Kathleen Kuehl April M. Babka Neil M. Davis Jun Liu John C. Trefry Sharon Daye Paul R. Facemire Patrick L. Iversen Sina Bavari Margaret L. Pitt Farooq Nasar 《PLoS neglected tropical diseases》2022,16(5)
Eastern equine encephalitis virus (EEEV) is mosquito-borne virus that produces fatal encephalitis in humans. We recently conducted a first of its kind study to investigate EEEV clinical disease course following aerosol challenge in a cynomolgus macaque model utilizing the state-of-the-art telemetry to measure critical physiological parameters. Here, we report the results of a comprehensive pathology study of NHP tissues collected at euthanasia to gain insights into EEEV pathogenesis. Viral RNA and proteins as well as microscopic lesions were absent in the visceral organs. In contrast, viral RNA and proteins were readily detected throughout the brain including autonomic nervous system (ANS) control centers and spinal cord. However, despite presence of viral RNA and proteins, majority of the brain and spinal cord tissues exhibited minimal or no microscopic lesions. The virus tropism was restricted primarily to neurons, and virus particles (~61–68 nm) were present within axons of neurons and throughout the extracellular spaces. However, active virus replication was absent or minimal in majority of the brain and was limited to regions proximal to the olfactory tract. These data suggest that EEEV initially replicates in/near the olfactory bulb following aerosol challenge and is rapidly transported to distal regions of the brain by exploiting the neuronal axonal transport system to facilitate neuron-to-neuron spread. Once within the brain, the virus gains access to the ANS control centers likely leading to disruption and/or dysregulation of critical physiological parameters to produce severe disease. Moreover, the absence of microscopic lesions strongly suggests that the underlying mechanism of EEEV pathogenesis is due to neuronal dysfunction rather than neuronal death. This study is the first comprehensive investigation into EEEV pathology in a NHP model and will provide significant insights into the evaluation of countermeasure. 相似文献
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Ormenese S de Almeida Engler J De Groodt R De Veylder L Inzé D Jacqmard A 《Annals of botany》2004,93(5):575-580
BACKGROUND AND AIMS: Kip-related-proteins (KRPs), negative regulators of cell division, have recently been discovered in plants but their in planta function is as yet unclear. In this study the spatial expression of all seven KRP genes in shoot apices of Arabidopsis thaliana were compared. METHODS: In situ hybridization analyses were performed on longitudinal sections of shoot apices from 2-month-old Arabidopsis plants. KEY RESULTS: The study provides evidence for different expression pattern groups. KRP1 and KRP2 expression is restricted to the endoreduplicating tissues. In contrast, KRP4 and KRP5 expression is mainly restricted to mitotically dividing cells. KRP3, KRP6 and KRP7 can be found in both mitotically dividing and endoreduplicating cells. CONCLUSION: The results suggest differential roles for the distinct KRPs. KRP1 and KRP2 might specifically be involved in the establishment of polyploidy. In contrast, KRP4 and KRP5 might be involved in regulating the progression through the mitotic cell cycle. KRP3, KRP6 and KRP7 might have a function in both types of cell cycle. 相似文献
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Bailey JS Rave-Harel N McGillivray SM Coss D Mellon PL 《Molecular endocrinology (Baltimore, Md.)》2004,18(5):1158-1170
FSH is critical for normal reproductive function in both males and females. Activin, a member of the TGFbeta family of growth factors, is an important regulator of FSH expression, but little is known about the molecular mechanisms through which it acts. We used transient transfections into the immortalized gonadotrope cell line LbetaT2 to identify three regions (at -973/-962, -167, and -134) of the ovine FSH beta-subunit gene that are required for full activin response. All three regions contain homology to consensus binding sites for Smad proteins, the intracellular mediators of TGFbeta family signaling. Mutation of the distal site reduces activin responsiveness, whereas mutation of either proximal site profoundly disrupts activin regulation of the FSHbeta gene. These sites specifically bind LbetaT2 nuclear proteins in EMSAs, and the -973/-962 site binds Smad4 protein. Interestingly, the protein complex binding to the -134 site contains Smad4 in association with the homeodomain proteins Pbx1 and Prep1. Using glutathione S-transferase interaction assays, we demonstrate that Pbx1 and Prep1 interact with Smads 2 and 3 as well. The two proximal activin response elements are well conserved across species, and Pbx1 and Prep1 proteins bind to the mouse gene in vivo. Furthermore, mutation of either proximal site abrogates activin responsiveness of a mouse FSHbeta reporter gene as well, confirming their functional conservation. Our studies provide a basis for understanding activin regulation of FSHbeta gene expression and identify Pbx1 and Prep1 as Smad partners and novel mediators of activin action. 相似文献