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11	Cyanobacterial Hydrogen Metabolism - Uptake Hydrogenase and Hydrogen Production by Nitrogenase in Filamentous Cyanobacteria Lindberg, Pia January 2003 (has links) Molecular hydrogen is a potential energy carrier for the future. Nitrogen-fixing cyanobacteria are a group of photosynthetic microorganisms with the inherent ability to produce molecular hydrogen via the enzyme complex nitrogenase. This hydrogen is not released, however, but is recaptured by the bacteria using an uptake hydrogenase. In this thesis, genes involved in cyanobacterial hydrogen metabolism were examined, and the possibility of employing genetically modified cyanobacteria for hydrogen production was investigated. Nostoc punctiforme PCC 73102 (ATCC 29133) is a nitrogen-fixing filamentous cyanobacterium containing an uptake hydrogenase encoded by hupSL. The transcription of hupSL was characterised, and putative regulatory elements in the region upstream of the transcription start site were identified. One of these, a binding motif for the global nitrogen regulator NtcA, was further investigated by mobility shift assays, and it was found that the motif is functional in binding NtcA. Also, a set of genes involved in maturation of hydrogenases was identified in N. punctiforme, the hypFCDEAB operon. These genes were found to be situated upstream of hupSL in the opposite direction, and they were preceded by a previously unknown open reading frame, that was found to be transcribed as part of the same operon. The potential for hydrogen production by filamentous cyanobacteria was investigated by studying mutant strains lacking an uptake hydrogenase. A mutant strain of N. punctiforme was constructed, where hupL was inactivated. It was found that cultures of this strain evolve hydrogen during nitrogen fixation. Gas exchange in the hupL- mutant and in wild type N. punctiforme was measured using a mass spectrometer, and conditions under which hydrogen production from the nitrogenase could be increased at the expense of nitrogen fixation were identified. Growth and hydrogen production in continuous cultures of a Hup- mutant of the related strain Nostoc PCC 7120 were also studied. This thesis advances the knowledge about cyanobacterial hydrogen metabolism and opens possibilities for further development of a process for hydrogen production using filamentous cyanobacteria. Microbiology cyanobacteria biohydrogen Nostoc hydrogen production hydrogen evolution hydrogen metabolism nitrogenase hydrogenase hydrogen uptake hydrogenase hupSL hydrogen uptake mutant uptake hydrogenase mutant photobioreactor hydrogenase accessory genes hyp transcription RT-PCR NtcA mass spectrometry heterocyst Mikrobiologi
12	Female-Specific Role of Ciliary Neurotrophic Factor in the Medial Amygdala in Promoting Stress Responses Jia, Cuihong, Gill, Wesley D., Lovins, Chiharu, Brown, Russell W., Hagg, Theo 01 March 2022 (has links) Ciliary neurotrophic factor (CNTF) is produced by astrocytes which have been implicated in regulating stress responses. We found that CNTF in the medial amygdala (MeA) promotes despair or passive coping, i.e., immobility in an acute forced swim stress, in female mice, while having no effect in males. Neutralizing CNTF antibody injected into the MeA of wildtype females reduced activation of downstream STAT3 (Y705) 24 and 48 h later. In concert, the antibody reduced immobility in the swim test in females and only after MeA injection, but not when injected in the central or basolateral amygdala. Antibody injected into the male MeA did not affect immobility. These data reveal a unique role of CNTF in female MeA in promoting despair or passive coping behavior. Moreover, 4 weeks of chronic unpredictable stress (CUS) increased immobility in the swim test and reduced sucrose preference in wildtype CNTF+/+, but not CNTF-/- littermate, females. Following CUS, 10 min of restraint stress increased plasma corticosterone levels only in CNTF+/+ females. In males, the CUS effects were present in both genotypes. Further, CUS increased CNTF expression in the MeA of female, but not male, mice. CUS did not alter CNTF in the female hippocampus, hypothalamus and bed nucleus of stria terminalis. This suggests that MeA CNTF has a female-specific role in promoting CUS-induced despair or passive coping, behavioral anhedonia and neuroendocrine responses. Compared to CNTF+/+ mice, CNTF-/- mice did not show differences in CUS-induced anxiety-like behavior and sensorimotor gating function as measured by elevated T-Maze, open field and pre-pulse inhibition of the acoustic startle response. Together, this study reveals a novel CNTF-mediated female-specific mechanism in stress responses and points to opportunities for developing treatments for stress-related disorders in women. anhedonia BLA basolateral amygdala BNST bed nucleus of stria terminalis CNTF ciliary neurotrophic factor CRF corticotropin releasing factor CUS chronic unpredictable stress CeA central amygdala Chronic unpredictable stress HPA hypothalamic-pituitary-adrenal Hyp hypothalamus IL-6 interleukin-6 LIF leukemia inhibitory factor MeA medial amygdala neuroendocrine response Neutralizing antibody PAG periaqueductal grey PTSD post-traumatic stress disorder PVN paraventricular nucleus passive stress-coping stereotaxic injection TNF tumor necrosis factor mPFC medial prefrontal cortex Biomedical Sciences

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Cyanobacterial Hydrogen Metabolism - Uptake Hydrogenase and Hydrogen Production by Nitrogenase in Filamentous Cyanobacteria

Female-Specific Role of Ciliary Neurotrophic Factor in the Medial Amygdala in Promoting Stress Responses