Microbial community dynamics and evaluation of bioremediation strategies in oil-impacted salt marsh sediment microcosms

Microbial community dynamics in wetlands microcosms emended with commercial products (surfactant, a biological agent, and nutrients) designed to enhance bioremediation was followed for 3 months. The effectiveness of enhanced degradation was assessed by determining residual concentrations of individual petroleum hydrocarbons by GC/MS. The size and composition of the sediment microbial community was assessed using a variety of indices, including bacterial plate counts, MPNs, and DNA hybridizations with domain- and group-specific oligonucleotide probes. The addition of inorganic nutrients was the most effective treatment for the enhancement of oil degradation, resulting in marked degradation of petroleum alkanes and a lesser extent of degradation of aromatic oil constituents. The enhanced degradation was associated with increases in the amount of extractable microbial DNA and Streptomyces in the sediment, although not with increased viable counts (plate counts, MPN). Bacteria introduced with one of the proprietary products were still detected in the microcosms after 3 months, but were not a major quantitative constituent of the community. The biological product enhanced oil degradation relative to the control, but to a lesser extent than the nutrient additions alone. In contrast, application of the surfactant to the oil-impacted sediment decreased oil degradation. Journal of Industrial Microbiology & Biotechnology (2001) 27, 72–79. Received 18 March 2001/ Accepted in revised form 09 June 2001     

A novel regulatory element in the dnmt1 gene that responds to co-activation by Rb and c-Jun

Rb, c-Jun and dnmt1 play critical roles in the process of cellular differentiation. We demonstrate that a regulatory region of murine dnmt1 contains an element which is responsible for transactivation by Rb and c-Jun in P19 embryocarcinoma cells which is not observed in Y1 adrenocarcinoma cells. During differentiation of P19 cells, the induction of Rb and c-Jun coincides with an increase of dnmt1 mRNA. Using linker scanning mutagenesis we identify the element that is responsible for this activation to be a non-canonical AP-1 site. Our data is an example of how a proto-oncogene activates its downstream effectors by recruiting a tumor suppressor. This interaction of Rb and a proto-oncogene might play an important role in differentiation. The responsiveness of dnmt1 to this type of signal is consistent with an important role for regulated expression of dnmt1 during cellular differentiation.     

Impaired Th2 development and increased mortality during Schistosoma mansoni infection in the absence of CD40/CD154 interaction

The role of CD40/CD154 interaction during infection has primarily focused on pathogens that drive inflammatory Th1 responses. In this study, we show that CD40/CD154 interaction is a fundamental requirement for Th2 response development to the parasitic helminth Schistosoma mansoni. Compared with infected wild-type mice, greatly reduced levels of Th2-associated cytokines were measured both in vitro and in vivo, and no IgE or IgG1 was detected in infected CD154(-/-) mice. In the absence of an overt Th2 response, no exaggerated Th1 response was mounted by CD154(-/-) mice. Infected CD154(-/-) mice suffered severe morbidity and mortality, even though parasitemias in wild-type and CD154(-/-) mice did not differ significantly. These data indicate that CD40/CD154 interaction is required to allow development of a Th2-dominated immune response to S. mansoni and support the view that failure to develop such a response can have fatal consequences.     

Sexual and apomictic reproduction in Hieracium subgenus pilosella are closely interrelated developmental pathways

Seed formation in flowering plants requires meiosis of the megaspore mother cell (MMC) inside the ovule, selection of a megaspore that undergoes mitosis to form an embryo sac, and double fertilization to initiate embryo and endosperm formation. During apomixis, or asexual seed formation, in Hieracium ovules, a somatic aposporous initial (AI) cell divides to form a structurally variable aposporous embryo sac and embryo. This entire process, including endosperm development, is fertilization independent. Introduction of reproductive tissue marker genes into sexual and apomictic Hieracium showed that AI cells do not express a MMC marker. Spatial and temporal gene expression patterns of other introduced genes were conserved commencing with the first nuclear division of the AI cell in apomicts and the mitotic initiation of embryo sac formation in sexual plants. Conservation in expression patterns also occurred during embryo and endosperm development, indicating that sexuality and apomixis are interrelated pathways that share regulatory components. The induction of a modified sexual reproduction program in AI cells may enable the manifestation of apomixis in HIERACIUM:     

Integrins modulate Sog activity in the Drosophila wing

Morphogenesis of the Drosophila wing depends on a series of cell-cell and cell-extracellular matrix interactions. During pupal wing development, two secreted proteins, encoded by the short gastrulation (sog) and decapentaplegic (dpp) genes, vie to position wing veins in the center of broad provein territories. Expression of the Bmp4 homolog dpp in vein cells is counteracted by expression of the Bmp antagonist sog in intervein cells, which results in the formation of straight veins of precise width. We screened for genetic interactions between sog and genes encoding a variety of extracellular components and uncovered interactions between sog and myospheroid (mys), multiple edematous wing (mew) and scab (scb), which encode betaPS, alphaPS1 and alphaPS3 integrin subunits, respectively. Clonal analysis reveals that integrin mutations affect the trajectory of veins inside the provein domain and/or their width and that misexpression of sog can alter the behavior of cells in such clones. In addition, we show that a low molecular weight form of Sog protein binds to alphaPS1betaPS. We find that Sog can diffuse from its intervein site of production into adjacent provein domains, but only on the dorsal surface of the wing, where Sog interacts functionally with integrins. Finally, we show that Sog diffusion into provein regions and the reticular pattern of extracellular Sog distribution in wild-type wings requires mys and mew function. We propose that integrins act by binding and possibly regulating the activity/availability of different forms of Sog during pupal development through an adhesion independent mechanism.     

Chitinolytic activity of endophytic Streptomyces and potential for biocontrol

Aims: Biological sources for the control of plant pathogenic fungi remain an important objective for sustainable agricultural practices. Actinomycetes are used extensively in the pharmaceutical industry and agriculture owing to their great diversity in enzyme production. In the present study, therefore, we evaluated chitinase production by endophytic actinomycetes and the potential of this for control of phytopathogenic fungi. Methods and Results: Endophytic Streptomyces were grown on minimum medium supplemented with chitin, and chitinase production was quantified. The strains were screened for any activity towards phytopathogenic fungi and oomycetes by a dual‐culture in vitro assay. The correlation between chitinase production and pathogen inhibition was calculated and further confirmed on Colletotrichum sublineolum cell walls by scanning electron microscopy. Conclusions: This paper reports a genetic correlation between chitinase production and the biocontrol potential of endophytic actinomycetes in an antagonistic interaction with different phytopathogens, suggesting that this control could occur inside the host plant. Significance and Impact of the Study: A genetic correlation between chitinase production and pathogen inhibition was demonstrated. Our results provide an enhanced understanding of endophytic Streptomyces and its potential as a biocontrol agent. The implications and applications of these data for biocontrol are discussed.     

The Psychedelic State Induced by Ayahuasca Modulates the Activity and Connectivity of the Default Mode Network

The experiences induced by psychedelics share a wide variety of subjective features, related to the complex changes in perception and cognition induced by this class of drugs. A remarkable increase in introspection is at the core of these altered states of consciousness. Self-oriented mental activity has been consistently linked to the Default Mode Network (DMN), a set of brain regions more active during rest than during the execution of a goal-directed task. Here we used fMRI technique to inspect the DMN during the psychedelic state induced by Ayahuasca in ten experienced subjects. Ayahuasca is a potion traditionally used by Amazonian Amerindians composed by a mixture of compounds that increase monoaminergic transmission. In particular, we examined whether Ayahuasca changes the activity and connectivity of the DMN and the connection between the DMN and the task-positive network (TPN). Ayahuasca caused a significant decrease in activity through most parts of the DMN, including its most consistent hubs: the Posterior Cingulate Cortex (PCC)/Precuneus and the medial Prefrontal Cortex (mPFC). Functional connectivity within the PCC/Precuneus decreased after Ayahuasca intake. No significant change was observed in the DMN-TPN orthogonality. Altogether, our results support the notion that the altered state of consciousness induced by Ayahuasca, like those induced by psilocybin (another serotonergic psychedelic), meditation and sleep, is linked to the modulation of the activity and the connectivity of the DMN.     

Yellow Fever 17DD Vaccine Virus Infection Causes Detectable Changes in Chicken Embryos

The yellow fever (YF) 17D vaccine is one of the most effective human vaccines ever created. The YF vaccine has been produced since 1937 in embryonated chicken eggs inoculated with the YF 17D virus. Yet, little information is available about the infection mechanism of YF 17DD virus in this biological model. To better understand this mechanism, we infected embryos of Gallus gallus domesticus and analyzed their histopathology after 72 hours of YF infection. Some embryos showed few apoptotic bodies in infected tissues, suggesting mild focal infection processes. Confocal and super-resolution microscopic analysis allowed us to identify as targets of viral infection: skeletal muscle cells, cardiomyocytes, nervous system cells, renal tubular epithelium, lung parenchyma, and fibroblasts associated with connective tissue in the perichondrium and dermis. The virus replication was heaviest in muscle tissues. In all of these specimens, RT-PCR methods confirmed the presence of replicative intermediate and genomic YF RNA. This clearer characterization of cell targets in chicken embryos paves the way for future development of a new YF vaccine based on a new cell culture system.