Electron impact ionization of hydrogen-like molybdenum ions

The electron impact ionization cross sections of hydrogen-like molybdenum ions were measured with an electron beam ion trap at the electron energies of 49.4, 64.4 and 79.6 keV The results are 2.82(22) x 10(-23), 3.13(29) x 10(-23) and 3.23(51) x 10(-23) cm(2), respectively. These results are compared with the experimental results measured previously. The agreement with the results obtained with, scaling formulae is also discussed.

Identification and Development of Enzymes Associated With the Sperm Inner Acrosomal Membrane and Their Function during Fertilization

In order for mammalian fertilization to transpire, spermatozoa must transit through the female reproductive tract and penetrate the outer investments of the oocyte: the cumulus oophorus and the zona pellucida. In order to penetrate the oocyte, spermatozoa must undergo the acrosome reaction. The acrosome reaction results in the exposure of the inner acrosomal membrane (IAM) and proteins that coat it to the extracellular environment. After the acrosome reaction, the IAM becomes the leading edge of spermatozoa undergoing progressive movement. Thus the enzymes which effect lysis of the oocyte investments ought to be located on the IAM. An objective of this study was to identify and characterize enzymatic activity detected on the IAM and provide evidence that they play a role in fertilization. This study also describes procedures for fractionating spermatozoa and isolating the IAM and proteins on its intra- and extra-vesicular surfaces, and describes their development during male gametogenesis. Since the IAM is exposed to the extracellular environment and oviductal milieu after the acrosome reaction, this study also sought to characterize interactions and relationships between factors in the oviductal environment and the enzymes identified on the IAM. The data presented provide evidence that MMP2 and acrosin are co-localized on the IAM, originate from the Golgi apparatus in gametogenesis, and suggest they cooperate in their function. Their localization and results of in vitro fertilization suggests they have a function in zona pellucida penetration. The data also provide evidence that plasminogen, originating from the oviductal epithelium and/or cumulus-oocyte complex, is present in the immediate environment of sperm-egg initial contact and penetration. Additionally, plasminogen interacts with MMP2 and enhances its enzymatic action on the IAM. The data also provide evidence that MMP2 has an important function in penetration of the cumulus oophorus. Holistically, this thesis provides evidence that enzymes on the IAM, originating from the Golgi apparatus in development, have an important function in penetration of the outer investments of the oocyte, and are aided in penetration by plasminogen in the female reproductive tract.

The DUB/USP17 deubiquitinating enzymes: A gene family within a tandemly repeated sequence, is also embedded within the copy number variable Beta-defensin cluste

Background: The DUB/USP17 subfamily of deubiquitinating enzymes were originally identified as immediate early genes induced in response to cytokine stimulation in mice (DUB-1, DUB-1A, DUB-2, DUB-2A). Subsequently we have identified a number of human family members and shown that one of these (DUB-3) is also cytokine inducible. We originally showed that constitutive expression of DUB-3 can block cell proliferation and more recently we have demonstrated that this is due to its regulation of the ubiquitination and activity of the 'CAAX' box protease RCE1.

Results: Here we demonstrate that the human DUB/USP17 family members are found on both chromosome 4p16.1, within a block of tandem repeats, and on chromosome 8p23.1, embedded within the copy number variable betadefensin cluster. In addition, we show that the multiple genes observed in humans and other distantly related mammals have arisen due to the independent expansion of an ancestral sequence within each species. However, it is also apparent when sequences from humans and the more closely related chimpanzee are compared, that duplication events have taken place prior to these species separating.

Conclusions: The observation that the DUB/USP17 genes, which can influence cell growth and survival, have evolved from an unstable ancestral sequence which has undergone multiple and varied duplications in the species examined marks this as a unique family. In addition, their presence within the beta-defensin repeat raises the question whether they may contribute to the influence of this repeat on immune related conditions.

Combining bio- and chemo-catalysis: from enzymes to cells, from petroleum to biomass

In the future, biomass will continue to emerge as a viable source of chemicals. The development of new industries that utilize bio-renewables provides opportunities for innovation. For example, bio- and chemo-catalysts can be combined in 'one pot' to prepare chemicals of commercial value. This has been demonstrated using isolated enzymes and whole cells for a variety of chemical transformations. The one-pot approach has been successfully adopted to convert chemicals derived from biomass, and, in our opinion, it has an important role to play in the design of a more sustainable chemical industry. To implement new one-pot bio- and chemo-catalytic processes, issues of incompatibility must be overcome; the strategies for which are discussed in this opinion article.

Resonance Raman and surface-enhanced resonance Raman studies of polymer-modified electrodes which mimic heme enzymes

Iron-5,10,15,20-tetraphenylporphyrin (FeTPP) has been incorporated into films of a coordinating hydrogel polymer support medium, poly(gamma-ethyl-L-glutamate) (PEG) functionalised with imidazole pendant arms (PEG-Im), and studied in situ on silver electrodes using a combination of both resonance Raman (RR) and surface-enhanced resonance Raman (SERR) spectroscopy. The SERR spectra give information on the portion of the film close to the electrode surface while RR spectra probe the