No abstract

During mitosis the interconnected Golgi complex of animal cells breaks down to produce both finely dispersed elements and discrete vesiculotubular structures. The endoplasmic reticulum (ER) plays a controversial role in generating these partitioning intermediates and here we highlight the importance of mitotic ER export arrest in this process. We show that experimental inhibition of ER export (by microinjecting dominant negative Sar1 mutant proteins) is sufficient to induce and maintain transformation of Golgi cisternae to vesiculotubular remnants during interphase and telophase, respectively. We also show that buds on the ER, ER exit sites and COPII vesicles are markedly depleted in mitotic cells and COPII components Sec23p, Sec24p, Sec13p and Sec31p redistribute into the cytosol, indicating ER export is inhibited at an early stage. Finally, we find a markedly uneven distribution of Golgi residents over residual exit sites of metaphase cells, consistent with tubulovesicular Golgi remnants arising by fragmentation rather than redistribution via the ER. Together, these results suggest selective recycling of Golgi residents, combined with prebudding cessation of ER export, induces transformation of Golgi cisternae to vesiculotubular remnants in mitotic cells. The vesiculotubular Golgi remnants, containing populations of slow or nonrecycling Golgi components, arise by fragmentation of a depleted Golgi ribbon independently from the ER.

The effects of Cenozoic compression within the Faroe-Shetland Basin and surrounding areas are mainly manifested in the form of growth folds. The scale and orientation of the folds varies significantly, with axial trace lengths ranging between less than 10 to over 250 km and trends including east, NE-, NNE-, ENW-, NNW-and WNW. The NE-trending features are the most numerous, though they are mainly restricted to the NE Faroe-Shetland Basin where an inherited Caledonian structural grain is most prevalent. Limited evidence exists for late Paleocene and early Eocene activity along the Wyville Thomson Ridge, whereas mid-late Eocene and Oligocene fold growth is more common in the SW Faroe-Shetland Basin. Although the effects of well-defined early-mid Miocene deformation appear to be mainly constrained to the NE Faroe-Shetland Basin, this phase of activity is also inferred to have been responsible for major growth of the Wyville Thomson Ridge. Early Pliocene fold growth is observed within the Faroe-Shetland Basin and adjacent areas, with raised seabed profiles over some of the anticlinal features suggesting that the effects of compressional stress continue at the present day. Despite the variation in trend and size of growth folds, there is, we believe, similarity in their local mechanism of emplacement, with buttressing of sedimentary successions against pre-existing basement architecture and igneous intrusions being of particular significance. However, the lack of obvious spatial or temporal pattern to fold growth development within the NE Atlantic margin as a whole mitigates against a single regional driving mechanism being able to explain the current distribution, orientation and timing of the folds.There have been numerous studies of the causes, nature, timing and effects of Cenozoic compression within the NE Atlantic margin, particularly in the Vøring Basin offshore Norway (e.g. Blystad et al.

The Lower Cretaceous Captain Sandstone Member of the Inner Moray Firth has significant potential for the injection and storage of anthropogenic CO 2 in saline aquifer parts of the formation. Pre-existing faults constitute a potential risk to storage security owing to the elevated pore pressures likely to result from large-scale fluid injection. Determination of the regional in situ stresses permits mapping of the stress tensor affecting these faults. Either normal or strike-slip faulting conditions are suggested to be prevalent, with the maximum horizontal stress orientated 33°-213°. Slip-tendency analysis indicates that some fault segments are close to being critically stressed under strike-slip stress conditions, with small pore-pressure perturbations of approximately 1.5 MPa potentially causing reactivation of those faults. Greater pore-pressure increases of approximately 5 MPa would be required to reactivate optimally orientated faults under normal faulting or transitional normal/strike-slip faulting conditions at average reservoir depths. The results provide a useful indication of the fault geometries most susceptible to reactivation under current stress conditions. To account for uncertainty in principal stress magnitudes, high differential stresses have been assumed, providing conservative fault-stability estimates. Detailed geological models and data pertaining to pore pressure, rock mechanics and stress will be required to more accurately investigate fault stability.

Seismic mapping of key Palaeozoic surfaces in the East Irish Sea-North Channel region has been incorporated into a review of hydrocarbon prospectivity. The major Carboniferous basinal and inversion elements are identified, allowing an assessment of the principal kitchens for hydrocarbon generation and possible migration paths. A major Carboniferous tilt-block is identified beneath the central part of the (Permian to Mesozoic) East Irish Sea Basin (EISB), bounded by carbonate platforms to south and north. The importance of the Bowland Shale Formation as the key source rock is reaffirmed, the Pennine Coal Measures having been eroded over wide areas as a result of Variscan inversion and erosion prior to Permian deposition. Peak generation from the Bowland source rock coincided with maximum burial of the system in late Jurassic/early Cretaceous time. A multiphase history of Variscan inversion has generated numerous structural traps whose potential remains essentially unexplored. Leakage of hydrocarbons from these into the overlying Triassic Ormskirk Sandstone reservoirs is likely to have occurred on a number of occasions, but currently unknown is how much resource remains in place below the Base-Permian unconformity. Poor permeability in the Pennsylvanian strata beneath the Triassic fields is a significant risk; the same may not be true in the less deeply buried marginal areas of the EISB, where additional potential plays are present in Mississippian carbonate platforms and latest Pennsylvanian clastic sedimentary rocks. Outside the EISB, the North Channel, Solway and Peel basins also contain Devonian and/or Carboniferous rocks. There have however been no discoveries, largely a consequence of the absence of a high quality source rock and a regional seal comparable to the Mercia Mudstone Group and Permian evaporites of the Cumbrian Coast Group in the EISB. The productive oil and gas fields of the EISB evidence a working, Carboniferous-sourced petroleum system. Whilst a great deal may be known of the Triassic reservoir and seal (Meadows et al. 1997), little is known about Carboniferous and Permian petroleum systems at depth and in adjacent basins, that may offer significant additional potential. Following the Wood Review (2014), Palaeozoic plays, including that of the greater Irish Sea area were identified as priority for building regional digital datasets and stimulating exploration. In response, the 21 st Century Exploration Roadmap: Palaeozoic Project running from 2014-2016 and openly released in 2017, undertook regional scale seismic and well interpretation, source and reservoir screening studies and basin modelling. This paper provides a re-interpretation of the structural history of the greater Irish Sea, and its influence on potential Carboniferous and Permian prospectivity including the marginal basins. The Carboniferous structure and stratigraphy of the UK sector of the East Irish Sea-North Channel region has been reviewed using all available well and seismic reflection data. The project interpreted about 40,0...