Diverse Brain Myeloid Expression Profiles Reveal Distinct Microglial Activation States and Aspects of Alzheimer’s Disease Not Evident in Mouse Models

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Isolation and Characterization of A Metal-resistant Pseudomonas Aeruginosa Strain

Summary The use of microorganisms to remove heavy metals from industrial effluent is an area of extensive research and development. Attempts have been made to isolate and characterize metal-resistant microorganisms from treated oil mill industry effluent wastewater samples. The metal-resistant organisms that showed values of minimum inhibitory concentration towards metals (Cd, Cr, Ni and Pb) ranging from 100 to 800 ppm level were screened. A potent metal-resistant organism, isolate BC15 from the wastewater samples was tentatively identified as Pseudomonas sp. Detailed analysis of morphological, biochemical and 16S rDNA sequence of the isolate revealed that it is closely related to Pseudomonas aeruginosa (94%). Pseudomonas BC15 was capable of absorbing 93% Ni, 65% Pb, 50% Cd and 30% Cr within 48 h from the medium containing 100 mg of each heavy metal per liter. The multiple metal tolerance of this strain was also associated with resistance to antibiotics such as ampicillin, tetracycline, chloramphenicol, erythromycin, kanamycin and streptomycin.     

Variations in the level of enzyme activity and immunolocalization of calcium-dependent protein kinases in the phloem of different cucumber organs

Calcium-dependent protein kinases (CDPKs) constitute a unique family of enzymes in plants that are characterized by a C-terminal calmodulin (CaM)-like domain. Through protein kinase assays, we have examined the levels of cucumber calcium-dependent kinase (CsCDPK) activity in various organs of cucumber seedlings and plants. The activity of CsCDPK was highest in cucumber plant leaves followed by seedling roots and hypocotyls; however, cucumber plant flowers, seedling cotyledons, and hooks had levels that were barely detectable. The CsCDPKs were immunolocalized using polyclonal antibodies that are highly specific against a part of the kinase domain of a calcium-dependent protein kinase (CsCDPKS) in the phloem sieve elements (SEs) in various organs of cucumber. In addition, this study indicates the presence of CsCDPKs in organelle-like bodies associated with the plasma membrane of sieve elements in mature stems and roots as well as in the storage bodies of immature seeds. These findings are discussed in terms of the likely roles played by CDPKs in the signal transduction pathways for Ca2+-regulated phloem transport of assimilates from leaves to various organs during growth and development of cucumber seedlings and plants.     

Induction of chitinase activity by exogenous cytokinins in excised dark-grown cucumber cotyledons: involvement of Ca and staurosporine-sensitive protein kinase(s) in cytokinin signaling

Cotyledons were excised from 7-day-old dark-grown cucumber seedlings and treated with water, benzyladenine (BA), kinetin (K), zeatin (Z), or zeatin riboside (ZR) in dark after endogenous cytokinin depletion. We have compared changes in chitinase (EC. 3.2.1.14) activity induced by these cytokinins. We find that the activities of chitinase and its isoforms increase by approximately 3- to 6-fold following BA, Z, and ZR treatments. Among these treatments, Z was more effective. K was totally ineffective in inducing chitinase activity. Immunoblot analysis suggests that the cytokinin Z-induction of enzyme activity is due to the induction of higher chitinase protein levels and not the activation of existing enzyme. Furthermore, the Z-induced chitinase activity and its protein accumulation were completely inhibited by the protein kinase inhibitor staurosporine, whereas the protein phosphatase inhibitor sodium fluoride was not effective in such inhibitions. Treatment of cotyledons with extemal CaCl₂ and calcium ionophore increased the basal chitinase activity by 6- and 5-fold, respectively. Moreover, the effects of staurosporine, sodium fluoride, and Ca²⁺ on Z-induced chitinase activity correlate with their effects on chitinase protein levels. Taken together, our data suggests Ca²⁺ and staurosporine-sensitive protein kinase(s) as components of the cytokinin transduction machinery involving induction of chitinase in cucumber.     

Plasmid-mediated degradation of o- and p-phthalate by Pseudomonas fluorescens

A Pseudomonas fluorescens strain SKP3 capable of utilizing both phthalic acid and terephthalic acid as sole source of carbon and energy was isolated by enrichment technique. Phthalic acid, terephthalic acid and protocatechuic acid were easily oxidized by both phthalate-grown and glucose-grown cells without a lag period. Phthalic acid is metabolized through the ortho cleavage pathway and terephthalic acid through the meta cleavage pathway and the enzymes of the two pathways are constitutive in nature. A large plasmid of approximately 140kb in size was found to be involved in the degradation of phthalates. The catabolic plasmid pSKL was transferable to different hosts.