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The yeast dynamin-like protein Vps1 has roles at multiple stages of membrane trafficking including Golgi to vacuole transport, endosomal recycling, endocytosis and in peroxisomal fission. While the majority of the Vps1 amino acid sequence shows a high level of identity with the classical mammalian dynamins, it does not contain a pleckstrin homology domain (PH domain). The Dyn1 PH domain has been shown to bind to lipids with a preference for PI(4,5)P2 and it is considered central to the function of Dyn1 in endocytosis. The lack of a PH domain in Vps1 has raised questions as to whether the protein can function directly in membrane fusion or fission events. Here we demonstrate that the region Insert B, located in a position equivalent to the dynamin PH domain, is able to bind directly to lipids and that mutation of three lysine residues reduces its capacity to interact with lipids, and in particular with PI(4,5)P2. The Vps1 KKK-AAA mutant shows more diffuse staining but does still show some localization to compartments adjacent to vacuoles and to endocytic sites suggesting that other factors are also involved in its recruitment. This mutant selectively blocks endocytosis, but is functional in other processes tested. While mutant Vps1 can localise to endocytic sites, the mutation results in a significant increase in the lifetime of the endocytic reporter Sla2 and a high proportion of defective scission events. Together our data indicate that the lipid binding capacity of the Insert B region of Vps1 contributes to the ability of the protein to associate with membranes and that its capacity to interact with PI(4,5)P2 is important in facilitating endocytic scission.

The Paleoproterozoic (Statherian) Thelon Basin is located in the Churchill Province of the Canadian Shield, formed following the Trans-Hudson Orogeny. Basin formation followed an interval of felsic volcanism and weathering of underlying bedrock. The diagenetic evolution of the Thelon lasted about one billion years and was punctuated by fluid movement influenced by tectonic events. Early quartz cements formed in well-sorted, quartz-rich facies during diagenetic stage 1; fluids in which these overgrowths formed had δ18O values near 0‰ (Vienna Standard Mean Ocean Water). Uranium-rich apatite cement (P1) also formed during diagenetic stage 1 indicating that oxygenated, uranium-bearing pore water was present in the basin early in its diagenetic history. Syntaxial quartz cement (Q1) formed in water with δ18O from −4 to −0.8‰ in diagenetic stage 2. Diagenetic stage 3 occurred when the Thelon Formation was at ca. 5 km depth, and was marked by extensive illitization, alteration of detrital grains, and uranium mineralization. Basin-wide, illite crystallized at ∼200 °C by fluids with δ18O values of 5–9‰ and δD values of −60 to −31‰, consistent with evolved basinal brines. Tectonism caused by the accretion of Nena at ca. 1600 Ma may have provided the mechanism for brine movement during deep burial. Diagenetic stage 4 is associated with fracturing and emplacement of mafic dikes at ca. 1300 Ma, quartz cement (Q3) in fractures and vugs, further illitization, and recrystallization of uraninite (U2). Q3 cements have fluid inclusions that suggest variable salinities, δ18O values of 1.5–9‰, and δD values of −97 to −83‰ for stage 4 brines. K-feldspar and Mg-chlorite formed during diagenetic stage 5 at ca. 1000 Ma in upper stratigraphic sequences, and in the west. These phases precipitated from low-temperature, isotopically distinct fluids. Their distribution indicates that the basin hydrostratigraphy remained partitioned for >600 Ma.

The family of dynamin proteins is known to function in many eukaryotic membrane fusion and fission events. The yeast dynamin-related protein Vps1 functions at several stages of membrane trafficking, including Golgi apparatus to endosome and vacuole, peroxisomal fission, and endocytic scission. We have previously shown that in its endocytic role, Vps1 functions with the amphiphysin heterodimer Rvs161/Rvs167 to facilitate scission and release of vesicles. Phosphoproteome studies of Saccharomyces cerevisiae have identified a phosphorylation site in Vps1 at serine 599. In this study, we confirmed this phosphorylation event, and we reveal that, like Rvs167, Vps1 can be phosphorylated by the yeast cyclin-associated kinase Pho85 in vivo and in vitro. The importance of this posttranslational modification was revealed when mutagenesis of S599 to a phosphomimetic or nonphosphorylatable form caused defects in endocytosis but not in other functions associated with Vps1. Mutation to nonphosphorylatable valine inhibited the Rvs167 interaction, while both S599V and S599D caused defects in vesicle scission, as shown by both live-cell imaging and electron microscopy of endocytic invaginations. Our data support a model in which phosphorylation and dephosphorylation of Vps1 promote distinct interactions and highlight the importance of such regulatory events in facilitating sequential progression of the endocytic process.

Summary Actin is critical for endocytosis in yeast cells, and also in mammalian cells under tension. However, questions remain as to how force generated through actin polymerization is transmitted to the plasma membrane to drive invagination and scission. Here, we reveal that the yeast dynamin Vps1 binds and bundles filamentous actin. Mutational analysis of Vps1 in a helix of the stalk domain identifies a mutant RR457-458EE that binds actin more weakly. In vivo analysis of Vps1 function demonstrates that the mutation disrupts endocytosis but not other functions of Vps1 such as vacuolar trafficking or peroxisome fission. The mutant Vps1 is stably expressed in cells and co-localizes with the endocytic reporters Abp1 and the amphiphysin Rvs167. Detailed analysis of individual endocytic patch behavior indicates that the mutation causes aberrant movements in later stages of endocytosis, consistent with a scission defect. Ultrastructural analysis of yeast cells using electron microscopy reveals a significant increase in invagination depth, further supporting a role for the Vps1-actin interaction during scission. In vitro analysis of the mutant protein demonstrates that—like wild-type Vps1—it is able to form oligomeric rings, but, critically, it has lost its ability to bundle actin filaments into higher-order structures. A model is proposed in which actin filaments bind Vps1 during invagination, and this interaction is important to transduce the force of actin polymerization to the membrane to drive successful scission., Graphical Abstract, Highlights • Yeast dynamin Vps1 forms oligomeric rings that bind and bundle F-actin in vitro • Mutations in the Vps1 stalk region disrupt actin binding and bundling • The Vps1 RR-EE actin binding mutant has defects in endocytic scission in vivo, Palmer et al. reveal that the yeast dynamin Vps1 is able to form oligomeric rings that can directly interact with and bundle F-actin. Defects in the Vps1-actin interaction confer endocytic scission defects in vivo.

The Paleoproterozoic Thelon Basin in Nunavat, Canada, is one of several large quartz-dominated sedimentary basins developed on Paleoproterozoic and Archean rocks of the Canadian Shield. Coarse-grained quartz to sub-feldspathic sandstones and conglomerates of the Thelon Formation comprise the basin fill. Detrital zircons from the Thelon Formation have LAM-ICP-MS 207 Pb – 206 Pb ages ranging from 3.94 to 1.78 Ga, but most are Neoarchean (2.70–2.50 Ga). The δ 18 O values of quartz range from 7.7 to 13.9‰, and are typically 10–12‰. Ages, U/Zr ratios, and oxygen isotopic compositions of detrital quartz are consistent with a predominantly Neoarchean metasedimentary source, such as surrounds the eastern Thelon Basin and comprises the bulk of basement rocks within the Rae domain. The three stratigraphic sequences of the Thelon Formation have δ 18 O ranges for detrital quartz and zircon ages that further constrain the source areas and support previous sequence-stratigraphic interpretations. The lower sequence contains reworked siltstone and sandstone clasts and 2.50–1.85 Ga zircons indicating a contribution from Paleoproterozoic terranes. Detrital quartz δ 18 O values range from 9.8 to 13.9‰, indicating a metamorphic source also, which is consistent with a proximal source for the lower sequence. The middle sequence contains zircons exhibiting the widest range of ages (3.94–1.78 Ga). A >3.4 Ga Paleoarchean zircon population, cannot be correlated to the immediately surrounding basement and therefore indicates a distal source, possibly in the order of 1000–2000 km away. The upper sequence contains relatively few zircons due to extensive alteration but ages are predominantly early Paleoproterozoic and Neoarchean. The upper sequence strata contain the lowest δ 18 O values of quartz, indicating an influx of granitic material late in the depositional history of the basin. The geochronology and geochemistry of detrital grains within the Thelon Formation indicate that the source areas evolved from predominantly proximal to distal, and back to proximal as the basin filled.

In the Humber Arm area of the western Newfoundland Appalachians, four distinct stratigraphic successions derived from the Laurentian continental margin are exposed. Each succession is believed to be characteristic of a separate thrust sheet. The platform sheet represents the ancient Laurentian shelf and its foreland basin cover; the Watsons Brook sheet is characterized by a succession including shelf-margin carbonates overlying foreland basin clastics; the Corner Brook sheet comprises continental slope and rise clastic and carbonate sedimentary rocks of the Humber Arm Supergroup; and the Woods Island sheet includes clastics of the Blow Me Down Brook formation that overlie mafic volcanics. Sheets are subdivided by thrusts into tectonic slices. Disrupted units and mélange, with scaly S1 foliation, are found along the boundaries of some slices. Thrust sheets and related structures have been deformed by F2 folds with axial planar S2 cleavage. S1 scaly foliations are transposed into parallelism with S2. There is a transition in the style of F2 folds across the area, from upright and subhorizontal in the west to overturned folds with west-dipping axial planes and steeply raking or reclined fold hinges in the east. Strongly curved fold hinges may reflect later shearing along the S2 surfaces, producing sheath-like fold geometries. Shear zones close to the east edge of the outcrop of the Watsons Brook sheet display kinematic indicators indicating both D2 reverse-sense and D3 normal-sense dip-slip shears. Subsequent events produced L4 and L5 crenulation lineations on the S2 surfaces. At minimum, several tens of kilometres of shortening affected the part of the margin preserved in the Humber Arm area; true shortening and transport amounts may have been much larger.

Deformed terrigenous and carbonate sedimentary rocks representing the early Paleozoic Laurentian continental margin form a series of elongate, fault-bounded blocks that plunge north beneath the Humber Arm Allochthon in the Stephenville area, west Newfoundland Appalachians. The continental shelf succession was folded and thrust-faulted after emplacement of the Humber Arm Allochthon. In the west of the area, Table Mountain is cut by a "pop-up" structure bounded by downward-converging reverse faults. Structures at the east margin of Table Mountain indicate both dextral and reverse slip. The Phillips Brook Structure, farther east, contains multiple, fault-bounded carbonate slices; one slice, carried by the West Blanche Brook fault, is thrust over the Humber Arm Allochthon. The western edge of the Indian Head massif, consisting of Grenville basement, is also a thrust contact. These reverse faults and thrusts, which cut the carbonate succession and postdate emplacement of the Humber Arm Allochthon, are in turn overprinted by structures formed during dextral strike-slip motion. Unconformable Early Carboniferous cover postdates most of the deformation. Cross-sections indicate shortening of a few kilometres, and basement was clearly involved in the deformation. The Port au Port Peninsula, immediately to the west, records a history of Acadian inversion of Taconian basins. The prevalence of pop-up structures and mappable variations within the stratigraphic units forming the top of the carbonate succession indicate that a complex geometry of Taconian horsts and grabens was inverted during post-Taconian (?Acadian) shortening and dextral strike-slip motion. These relationships suggest a variety of attractive targets in petroleum exploration.

The Humber Zone of the western Newfoundland Appalachians represents the early Paleozoic Laurentian margin established by Neoproterozoic rifting. After a period of passive margin thermal subsidence, Taconian deformation began in the Early Ordovician with westward thrusting. Subsequently, an extensive foreland basin developed beneath the Gulf of St. Lawrence. It records rapid Late Ordovician to Early Silurian subsidence; mid-Silurian erosion; and renewed Late Silurian to Devonian subsidence. The Humber Zone was traversed by Lithoprobe seismic reflection profiles. Within the external part of the orogen, seismic reflections in the upper crustal section appear more coherent where seismic lines are parallel to fold hinges. Some subhorizontal reflectors are interpreted as thrust sheets of shelf limestone, but others probably represent intrabasement structures. A group of moderately northwest-dipping reflections probably represents late extensional shear zones. On the Baie Verte Peninsula, low-angle reflections passing beneath the Baie Verte Line are probably also late extensional shears, possibly reactivating earlier thrusts. Tectonism in the Humber Zone probably began with attempted eastward subduction of the Laurentian margin. Deep burial of the margin, accompanied by eclogite-facies metamorphism, probably coincided with rapid subsidence in the foreland basin. Later Barrovian metamorphism was associated with cleavage development and east-directed shear, and with dextral oblique slip, in Baie Verte Peninsula. Later Silurian sinistral transpression with thrusting east of the Baie Verte Line was followed by dextral transpression to transtension. "Acadian" thrusting dominated the western margin of the orogen in the Devonian and possibly earliest Carboniferous.

The release of genetically engineered organisms into the environment has raised concerns about their potential ecological impact. In this study, genetically engineered Erwinia carotovora strains expressing varying levels of reduced phytopathogenicity and wildtype E. carotovora strains were used in aquatic and soil microcosms to assess the survival, intraspecific competition, and effects upon specific groups of indigenous bacteria. In aquatic microcosms, the densities of Erwinia genetically engineered organisms (GEMs) and wildtype strains declined and fell below the detectable limit of plate counts 15 d after the microcosms were inoculated. In aquatic microcosms, engineered E. carotovora did not exhibit a competitive advantage over the wildtype. The effect of engineered and wildtype E. carotovora on densities of total and selected bacteria was not significantly different. Treatment with engineered E. carotovora did not change biomass values of the receiving community but did cause a transitory increase in metabolic activity. In aquatic microcosms, the inability of genetically engineered E. carotovora to persist, displace resident species, or affect the metabolic activity of aquatic communities indicates the low risk of adverse ecological consequences in aquatic ecosystems. Unlike previous investigations involving soil microcosms, densities of both the genetically engineered and wildtype E. carotovora remained at detectable levels over 60 d in both agricultural clay and forest loam soils. The type of soil significantly affected the survival of the GEM and the wildtype. The sorptive properties of clay particles, as well as low concentrations of soil nutrients and organic matter, may have contributed to the unexpected patterns of GEM and wildtype survival.

Common methods of assessing the biological impact of point source discharge involve a census of organisms above and below the discharge. The identification and enumeration of organisms necessary for this approach can be time consuming and costly. When microbial communities are used, identification and enumeration are often impossible because the majority of species are identifiable only when cultured and most native species cannot be cultured. As such, little is known about the response of nonculturable aquatic microbial communities to anthropogenic changes. We isolated aquatic microbial DNA from colonized artificial substrates in two streams receiving industrial waste. DNA was isolated from the microbial communities upstream and downstream of the discharges and the similarity of these communities were compared by DNA-DNA hybridization. These novel estimates of impact were compared to more conventional estimates based on a component of the microbial communities that could be readily identified, the protozoans. Protozoan species were identified and similarity between upstream and downstream stations was assessed using Jaccard's similarity index.

The recent publication of Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy has generated much scientific, public, and political discussion. Although the book emphasizes the restoration of entire aquatic ecosystems, discussion of senescent dams and human-made reservoirs is absent. The important societal and ecological roles of reservoirs warrant a closer examination of the potential ecological restoration of aging reservoirs. Problems with long-term reservoir management include lack of long-term management strategies, sedimentation, hazardous waste accumulation, impacts of recreational use, and the creation of new aquatic and riparian habitats. Policy conflicts may arise when habitats created in the reservoir are destroyed to restore the downstream habitats or when created habitats upstream undergo successional changes that impact the commercial or recreational value of the reservoir. Rare or endangered species may also create similar conflicts. The establishment of an ecological restoration bonding program that includes environmental education and conservation prior to new dam construction may aid in resolving potential conflicts in the future.

Vps1 is the yeast dynamin-like protein that functions during several membrane trafficking events including traffic from Golgi to vacuole, endosomal recycling and endocytosis. Vps1 can also function in peroxisomal fission indicating that its ability to drive membrane fission is relatively promiscuous. It has been of interest therefore that several mutations have been identified in Vps1 that only disrupt its endocytic function. Most recently, disruption of the interaction with actin through mutation of residues in one of the central stalk α helices (RR457,458 EE) has been shown to disrupt endocytosis and cause an accumulation of highly elongated invaginations in cells. This data supports the idea that an interaction between Vps1 and actin is important to drive the scission stage in endocytosis. Another Vps1 mutant generated in the study was vps1 E461K. Here we show data demonstrating that the E461K mutation also disrupts endocytosis but at an early stage, resulting in inhibition of the invagination step itself.

Increased population pressure and human activities have significantly altered the effectiveness of functions of ecosystems ("ecosystem services") at the local and regional scale. Of primary importance is the decrease in water quality due to urban storm water runoff. A number of communities have initiated restoration strategies to improve water quality standards. One such strategy is the incorporation of riparian walkways with native flora. As a result of such restoration efforts, habitats for native fauna have improved, and the number and diversity of wildlife have increased in urban settings. Restoration of urban habitats also provides social and economic benefits to the surrounding community. Efforts to mitigate the loss of ecological resources by restoring native habitats on lots that cannot be developed or on abandoned lots hold a high, unrealized potential. Habitat restoration not only provides natural diversions to urban surroundings, but also enlightens and educates individual citizens about the importance of balanced ecosystems and the role of humans within ecosystems. Education is the primary step toward creating ecologically sustainable communities. Images p452-a