Nicotinic Agonists, Phorbol Esters, and Growth Factors Activate Two Extracellular Signal-Regulated Kinases, ERK1 and ERK2, in Bovine Chromaffin Cells

Treatment of bovine chromaffin cells with nicotinic agonists, phorbol esters, and growth factors increases protein kinase activity toward microtubule-associated protein-2 and myelin basic protein (MBP) in vitro. To characterize the kinases that are activated by these agents, we separated chromaffin cell proteins by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels into which MBP had been incorporated, allowed the proteins to renature, and then assayed MBP kinase activity by incubating the gels with [gamma-32P]ATP. Chromaffin cells contain a family of kinases that phosphorylate MBP in vitro. Two of these kinases, of M(r) 46,000 and 42,000 (PK46 and PK42), were activated by treatment of the cells with dimethylphenylpiperazinium (DMPP), phorbol 12,13-dibutyrate (PDBu), or insulin-like growth factor I (IGF-I). Activation of PK46 and PK42 by DMPP was dependent on extracellular Ca2+, whereas the effects of PDBu and IGF-I were Ca2+ independent. Down-regulation of protein kinase C by incubation of the cells with PDBu abolished the activation of PK46 and PK42 by DMPP, PDBu, and IGF-I. Staurosporine, a protein kinase C inhibitor, prevented the activation of PK46 and PK42 by DMPP and PDBu but did not block the activation of these kinases by IGF-I. Immunoblotting experiments with antiphosphotyrosine (anti-PTyr) antibodies demonstrated that agents that increased the kinase activities of PK46 and PK42 also increased the apparent PTyr content of M(r) 46,000 and 42,000 proteins. PK46 and PK42 comigrated with proteins that reacted with antibodies against extracellular signal-regulated kinases (ERKs). Thus, PK46 and PK42 appear to be the bovine homologues of ERK1 and ERK2.(ABSTRACT TRUNCATED AT 250 WORDS)     

Further evidence that ribavirin interacts with eIF4E

This commentary discusses the recent reports in RNA by Yan and colleagues and Westman and colleagues of the apparent failure of ribavirin to bind to recombinant eIF4E and inhibit 7-methyl guanosine cap-dependent exogenous mRNA translation of cell extracts in vitro. Measuring binding by using affinity chromatography of matrix-immobilized proteins and by using protein emission fluorescence spectroscopy in the presence of nucleotide ligands, as well as limitations of using cell extracts for the assessment of mechanisms of mRNA translation are discussed. Possible reasons for the discordant findings of Yan and colleagues and Westman and colleagues are suggested, and direct observation of the specific binding of ribavirin to eIF4E by using mass spectrometry is presented.     

The importance of cryptic species and subspecific populations in classic biological control of weeds: a North American perspective

Classical biological control of weeds depends on finding agents that are highly host-specific. This requires not only correctly understanding the identity of the target plant, sometimes to subspecific levels, in order to find suitable agents, but also identifying agents that are sufficiently specific to be safe and effective. Behavioral experiments and molecular genetic tools have revealed that some arthropod species previously thought to be polyphagous really consist of multiple cryptic species, host races or biotypes, some of which are more host-specific than others. Whereas true species are reproductively isolated, individuals from subspecific populations may potentially interbreed with those of other populations if they should encounter them. Furthermore, biotypes may consist of individuals sharing a genotype that is not fixed within a monophyletic group, and thus may not be evolutionarily stable. This raises the question of how such populations should be classified, and how to confirm the identity of live arthropods before releasing them as classical biological control agents. The existence of host races or cryptic species may greatly increase the number of prospective biological control agents available. However, it may also create new challenges for governmental regulation. These issues are discussed using pertinent examples, mainly from North America.     

Intracellular inclusions in epidermal cells of tobacco infected by tobacco rattle virus

Internal symptoms in epidermal cells of tobacco rattle virus infected tobacco were investigated. Ring-, elipsoid- and spindle-shaped inclusions were found in the period between the fourth and thirtieth day after inoculation of Samsun seedlings.     

Eiweißkristalloide in Kakteen-Virusträgern

Zusammenfassung Mit dem Gewebesaft vonOpuntia brasiliensis, die neben cytoplasmatischen Eiweißspindeln noch Zellkernkristalloide enthielt, wurde ein spindelfreiesEpiphyllum infiziert. Nach einiger Zeit (ca. 3 Wochen) erschienen im infiziertenEpiphyllum nicht mir die cytoplasmatischen Eiweißspindeln. sondern auch die Kernkristalloide.In den Vakuolen der erwähntenOpuntia wie auch in denen vonEpiphyllum wurden kristallinische Eiweißdrusen beobachtet, die auch als vom Virus bedingte Zelleinschlüsse aufgefaßt werden.     

Expression of A152T human tau causes age‐dependent neuronal dysfunction and loss in transgenic mice

A152T‐variant human tau (hTau‐A152T) increases risk for tauopathies, including Alzheimer's disease. Comparing mice with regulatable expression of hTau‐A152T or wild‐type hTau (hTau‐WT), we find age‐dependent neuronal loss, cognitive impairments, and spontaneous nonconvulsive epileptiform activity primarily in hTau‐A152T mice. However, overexpression of either hTau species enhances neuronal responses to electrical stimulation of synaptic inputs and to an epileptogenic chemical. hTau‐A152T mice have higher hTau protein/mRNA ratios in brain, suggesting that A152T increases production or decreases clearance of hTau protein. Despite their functional abnormalities, aging hTau‐A152T mice show no evidence for accumulation of insoluble tau aggregates, suggesting that their dysfunctions are caused by soluble tau. In human amyloid precursor protein (hAPP) transgenic mice, co‐expression of hTau‐A152T enhances risk of early death and epileptic activity, suggesting copathogenic interactions between hTau‐A152T and amyloid‐β peptides or other hAPP metabolites. Thus, the A152T substitution may augment risk for neurodegenerative diseases by increasing hTau protein levels, promoting network hyperexcitability, and synergizing with the adverse effects of other pathogenic factors.     

Expansion of Multipotent Stem Cells from the Adult Human Brain

The discovery of stem cells in the adult human brain has revealed new possible scenarios for treatment of the sick or injured brain. Both clinical use of and preclinical research on human adult neural stem cells have, however, been seriously hampered by the fact that it has been impossible to passage these cells more than a very few times and with little expansion of cell numbers. Having explored a number of alternative culturing conditions we here present an efficient method for the establishment and propagation of human brain stem cells from whatever brain tissue samples we have tried. We describe virtually unlimited expansion of an authentic stem cell phenotype. Pluripotency proteins Sox2 and Oct4 are expressed without artificial induction. For the first time multipotency of adult human brain-derived stem cells is demonstrated beyond tissue boundaries. We characterize these cells in detail in vitro including microarray and proteomic approaches. Whilst clarification of these cells’ behavior is ongoing, results so far portend well for the future repair of tissues by transplantation of an adult patient’s own-derived stem cells.     

Different associations of apoE gene polymorphism with metabolic syndrome in the Vojvodina Province (Serbia)

The metabolic syndrome (MetS) is a polygenic multifactorial metabolic disorder with strong socioeconomic influence. MetS has became a worldwide epidemic, that directly increases the risk of cardiovascular diseases and type 2 diabetes mellitus. The human apoE gene, coding Apolipoprotein E, has three common polymorphisms in human population: e2, e3 and e4, which are proved to be associated with impaired lipid metabolism. The contribution of apoE polymorphism to MetS disorders has not been investigated previously in Vojvodina Province, region with the highest number of obese people in Serbia. The aim of this study was to evaluate apoE gene polymorphism in relation to MetS disorders. The healthy control group of 30 individuals and 63 MetS patients were examined for apoE variants in relation to biochemical and anthropometric parameters. The genotypes were determined by PCR–RFLP. Regarding all parameters, significantly higher values were detected in MetS group compared to control. The MetS group of patients had significantly higher frequency of e4 allele. In addition, positive relation was revealed between e4 allele presence and all measured parameters. It was found that the e4 allele was related with a significantly increased OR of MetS disorders according to the International Diabetes Federation definition. These results suggested that e4 allele may act as a one of determinants for development of metabolic syndrome.     

Changes in the hypothalamo-pituitary-adrenocortical and hypothalamo-pituitary-thyroid axes in diabetic rats acclimated to moderate hyperthermic environment

We examined the effect of acclimation to moderate hyperthermic environment on the ACTH, TSH, T₃, T₄ and corticosterone level, as well as the relative weight of hypophysis, thyroid and adrenal glands in streptozotocin-diabetic rats. Increased activity of the hypothalamo-pituitary-adrenocortical (HPA) axis has been demonstrated in diabetic animals, whereas insulin treatment restores the changes. Heat acclimation reduces the level of ACTH and corticosterone in control animals and moderates the hormonal disturbances caused by diabetes. Simultaneously, our study revealed impairment in the activity of the hypothalamo-pituitary-thyroid (HPT) axis. Acclimation to 35±1 °C resulted in significantly lower T₃ and T₄ levels in control, diabetic and insulin-treated animals. Relative weight of the hypophysis, thyroid and adrenal glands is decreased in heat-acclimated rats. Our assumption is that there might be a cross tolerance between diabetes and heat acclimation on a hormonal level.