Erythropoietin prevents PC12 cells from 1-methyl-4-phenylpyridinium ion-induced apoptosis via the Akt/GSK-3β/caspase-3 mediated signaling pathway

Apoptosis is a contributing cause of dopaminergic neuron loss in Parkinson disease. Recent work has shown that erythropoietin (EPO) offers protection against apoptosis in a wide variety of tissues. We demonstrate that exposure of PC12 cells to 1-methyl-4-phenylpyridinium ion (MPP⁺) with recombinant human EPO, significantly decreased apoptosis as measured by TUNEL and caspase-3 activity when compared to MPP⁺ treatment alone. EPO induced sustained phosphorylation of Akt and its substrate, GSK-3β, reduced caspase-3 activities in PC12 cells. The anti-apoptotic effect of EPO was abrogated by co-treatment with LY294002, the specific blocker of phosphatidylinositol 3-kinase (PI3K). The effects of EPO on GSK-3β and caspase-3 activities were also blocked by LY294002. LiCl, the inhibitor of GSK-3β, downregulated the caspase-3 activity and blocked the apoptosis induced by MPP⁺. Finally, we determined that EPO transiently activated the ERK signaling pathway, but PD98059, a specific inhibitor of ERK, does not alter the survival effect of EPO in this model system. Thus, these findings indicate that EPO protects against apoptosis in PC12 cells exposed to MPP⁺, through the Akt/GSK-3β/caspase-3 signaling pathway, but the ERK pathway is not involved in the EPO-dependent survival enhancing effect in this model system. The authors Yan Wu and You Shang are equally contributed to this work.     

A genetic linkage map of Pacific white shrimp (<Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>): sex-linked microsatellite markers and high recombination rates

Pacific white shrimp (Litopenaeus vannamei) is the leading species farmed in the Western Hemisphere and an economically important aquaculture species in China. In this project, a genetic linkage map was constructed using amplified fragment length polymorphism (AFLP) and microsatellite markers. One hundred and eight select AFLP primer combinations and 30 polymorphic microsatellite markers produced 2071 markers that were polymorphic in either of the parents and segregated in the progeny. Of these segregating markers, 319 were mapped to 45 linkage groups of the female framework map, covering a total of 4134.4 cM; and 267 markers were assigned to 45 linkage groups of the male map, covering a total of 3220.9 cM. High recombination rates were found in both parental maps. A sex-linked microsatellite marker was mapped on the female map with 6.6 cM to sex and a LOD of 17.8, two other microsatellite markers were also linked with both 8.6 cM to sex and LOD score of 14.3 and 16.4. The genetic maps presented here will serve as a basis for the construction of a high-resolution genetic map, quantitative trait loci (QTLs) detection, marker-assisted selection (MAS) and comparative genome mapping.     

Neuroprotection and free radical scavenging effects of <Emphasis Type="Italic">Osmanthus fragrans</Emphasis>

The ethanol extract of dried flowers Osmanthus fragrans (OFE) was assessed for free radical scavenging effects measured by the bleaching of the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical, scavenging of the hydroxyl anion, investigation of the ferric reducing/antioxidant power (FRAP) and lipid-peroxidation inhibition in rat tissues. OFE contained a high amount of total flavonoid and polyphenol. OFE presented the effects in the metal reducing power, FRAP assay with IC₅₀ values of 0.23 μg/ml, and 7.74 μg/ml, respectively. OFE presented similar activities toward the DPPH and hydroxyl anion scavenging ability with IC₅₀ values of 10 μg/ml. OFE with IC₅₀ values between 46 and 97 μg/ml inhibited lipid peroxidation initiated by ferrous chloride in rat brain, liver, heart and kidney mitochodrias. Moreover, the neuroprotective activity of OFE was investigated under different insults (glutamate, arachidonic acid, and 6-hydroxydopamine) in Wistar rat primary cortical neurons. OFE with EC₅₀ values between 66 and 165 μg/ml attenuated the neurotoxicity on MTT and LDH assays. In addition, the AKT protein expression of excitotoxicity and oxidative stress was displayed by western blotting analysis. OFE could up-regulate the glutamate and 6-OHDA decreased AKT expression. This is the first demonstration of the neuroprotective, free radical scavenging and anti-oxidative effects of O. fragrans.     

The mode of action of thidiazuron: auxins,indoleamines, and ion channels in the regeneration of <Emphasis Type="Italic">Echinacea purpurea</Emphasis> L.

The biochemical mechanisms underlying thidiazuron (TDZ)-induced regeneration in plant cells have not been clearly elucidated. Exposure of leaf explants of Echinacea purpurea to a medium containing TDZ results in undifferentiated cell proliferation and differentiated growth as mixed shoot organogenesis and somatic embryogenesis. The current studies were undertaken to determine the potential roles of auxin, indoleamines, and ion signaling in the dedifferentiation and redifferentiation of plant cells. E. purpurea leaf explants were found to contain auxin and the related indoleamine neurotransmitters, melatonin, and serotonin. The levels of these endogenous indoleamines were increased by exposure to TDZ associated with the induction of regeneration. The auxin-transport inhibitor 2,3,5-triiodobenzoic acid and auxin action inhibitor, p-chlorophenoxyisobutyric acid decreased the TDZ-induced regeneration but increased concentrations of endogenous serotonin and melatonin. As well, inhibitors of calcium and sodium transport significantly reduced TDZ-induced morphogenesis while increasing endogenous indoleamine content. These data indicate that TDZ-induced regeneration is the manifestation of a metabolic cascade that includes an initial signaling event, accumulation, and transport of endogenous plant signals such as auxin and melatonin, a system of secondary messengers, and a concurrent stress response.     

Travelling Waves of Attached and Detached Cells in a Wound-Healing Cell Migration Assay

During a wound-healing cell migration assay experiment, cells are observed to detach and undergo mitosis before reattaching as a pair of cells on the substrate. During experiments with mice 3T3 fibroblasts, cell detachment can be confined to the wavefront region or it can occur over the whole wave profile. A multi-species continuum approach to modelling a wound-healing assay is taken to account for this phenomenon. The first cell population is composed of attached motile cells, while the second population is composed of detached immotile cells undergoing mitosis and returning to the migrating population after successful division. The first model describes cell division occurring only in the wavefront region, while a second model describes cell division over the whole of the scrape wound. The first model reverts to the Fisher equation when the reattachment rate relative to the detachment rate is large, while the second case does not revert to the Fisher equation in any limit. The models yield travelling wave solutions. The minimum wave speed is slower than the minimum Fisher wave speed and its dependence on the cell detachment and reattachment rate parameters is analysed. Approximate travelling wave profiles of the two cell populations are determined asymptotically under certain parameter regimes.     

Cocaine withdrawal and neuro-adaptations in ion channel function

Chronic exposure to psychostimulants induces neuro-adaptations in ion channel function of dopamine (DA)-innervated cells localized within the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc). Although neuroplasticity in ion channel function is initially found in drug-sensitized animals, it has recently been believed to underlie the withdrawal effects of cocaine, including craving that leads to relapse in human addicts. Recent studies have also revealed remarkable differences in altered ion channel activities between mPFC pyramidal neurons and medium spiny NAc neurons in cocaine-withdrawn animals. In response to psychostimulant or certain “excitatory” stimuli, increased intrinsic excitability is found in mPFC pyramidal neurons, whereas decreased excitability is observed in medium spiny NAc cells in drug-withdrawn animals compared to drug-free control animals. These changes in ion channel function are modulated by interrupted DA/Ca²⁺ signaling with decreased DA D2 receptor function but increased D1 receptor signaling. More importantly, they are correlated to behavioral changes in cocaine-withdrawn human addicts and sensitized animals. Based on growing evidence, researchers have proposed that cocaine-induced neuro-adaptations in ion channel activity and DA/Ca²⁺ signaling in mPFC pyramidal neurons and medium spiny NAc cells may be the fundamental cellular mechanism underlying the cocaine withdrawal effects observed in human addicts.     

Correlation Between Antifungal Agent Phenazine-1-Carboxylic Acid and Pyoluteorin Biosynthesis in <Emphasis Type=Italic>Pseudomonas</Emphasis> sp. M18

Biosynthesis and secretion of two different types of antifungal compound [phenazine-1-carboxylic acid (PCA) and pyoluteorin (Plt) in Pseudomonas sp. M18] contribute to its suppression of soil-borne root pathogens. To better understand the correlation between two antifungal agents in secondary metabolism, a DNA fragment covering partial pltC and pltD coding sequences was obtained by screening the genomic library of Pseudomonas sp. M18. A mutant, M18T, was then constructed by insertion of the aacC1 gene cassette (encoding gentamycin resistance). With the same methods, one PCA biosynthetic gene cluster was insertionally inactivated and a mutant M18Z1 was created. The mutant strain M18T produces no Plt and the same amount of PCA in comparison with the wild-type strain M18. The mutant M18Z1, however, produces less PCA but more Plt than the wild-type strain M18. According to the documented data on strain M18, it is suggested that production of PCA is not influenced by Plt yield, but Plt biosynthesis is influenced by an alteration of PCA production.     

Nematophagous fungus <Emphasis Type="Italic">Paecilomyces lilacinus</Emphasis> (Thom) Samson is also a biological agent for control of greenhouse insects and mite pests

Pathogenicity of nematophagous fungus Paecilomyces lilacinus (Thom) Samson in control of the most destructive greenhouse pests such as: greenhouse whitefly, Trialeurodes vaporariorum, glasshouse red spider mite, Tetranychus urticae, the cotton aphid, Aphis gossypii and western flower thrips, Frankliniella occidentalis was examined in laboratory and pot experiments. The fungus showed the greatest efficacy in controlling winged and wingless forms of the cotton aphid. The cotton aphid’s population was almost totally eliminated. In controlling the greenhouse whitefly, P. lilacinus was most successful when applied against nymphal growth stages (L₃-L₄). Control of the western flower thrips was most efficient against prepupal and pupal stages when the fungus was applied as a water spore suspension to the soil. When the fungus was applied at temperatures below 10 °C, it was able to reduce a glasshouse red spider mite population by 60%.     

Kinetics of albumin- and alpha-fetoprotein-production during rat liver development

Synthesis of most of the plasma proteins is one of the main functions of the hepatocytes. Albumin synthesis is quantitatively the most abundant. In the present study we investigated albumin- and alpha-fetoprotein-gene-expression, and the function of the secretory apparatus during rat liver development. To this purpose we used the method of radioactive biosynthetic labeling of newly synthesized albumin and alpha-fetoprotein (AFP) to monitor the secretory capacity of endodermal cells derived from ventral foregut region (embryonic day 10, E10), and of embryonic and fetal hepatoblasts. Synthesis and secretion of albumin and AFP were already detected in the low numbered ventral foregut endodermal cells; fibrinogen synthesis was detectable in the E12 hepatoblasts, which were in higher number. The whole secretory machinery was functional from the earliest stages of liver development, and the speed of secretion was comparable with that of the adult hepatocytes. There was almost 4-fold increase of hepatoblasts cell volume in fetal stage compared with embryonic stage. The model used suggests that the hepatocyte secretory apparatus is already functional before the emergence of the liver bud. This is the first comparative report to analyze the hepatocyte secretory function, cell proliferation and cell volume during liver development.     

Prins and C-PRINS: Promising tools for the physical mapping of the lupin genome

Two molecular cytogenetics methods, PRINS (primed in situ DNA labeling) and C-PRINS (cycling PRINS), were optimized for the physical mapping of several types of DNA sequences on the mitotic chromosomes of the narrow-leafed lupin (Lupinus angustifolius L.). The fragment of the FokI element from Vicia faba was localised by indirect PRINS reaction. Two other sequences, fragments of the coding sequences of L. luteus and of L. angustifolius, were localised by indirect C-PRINS. These techniques are faster and more sensitive than FISH, and they allowed the mapping of short DNA fragments. The data obtained shows that both types of PRINS are valuable tools for chromosome identification in lupin.