Development of hypogene and supergene alteration and copper mineralization patterns, Sar Cheshmeh porphyry copper deposits, Iran /

The formation of the Sar Cheshmeh porphyry Cu-Mo deposit is related to the culmination of calc-alkaline igneous activity in the Kerman region. The deposit comprises a suite of Late Cenozoic intrusive sub-volcanic and extrusive rocks emplaced into a folded series of Eocene andesitic lavas and pyroclastic sediments. The earliest stage of magmatism was emplacement of a large granodiorite stock about 29 m.y.b.p. This was followed by intrusion of two separate porphyritic bodies at 15 (Sar Cheshrneh porphyry) and 12 m.y.b.p. (Late porphyry) and a series of sub-volcanic dikes between 12 and 9 m.y.b.p. Magmatic activity terminated with multi-phase extrusion of a Pelean dacitic dome complex between 10 and 2.8 m.y.b.p. The country rocks and the earlier porphyritic intrusions are pervasively altered to biotite-rich potassium silicate (metasomatic and hydrothermal) sericite-clay, phyllic and chlorite-clay, argillic assemblages. These grade outwards to an extensive propylitic zone. Within the ore body, the later intra-. and post-mineral dikes only reach the propylitic grade. At least three different sets of quartz veins are present, including a sericite-chlorite-quartz set which locally retrogrades pervasive secondary biotite to sericite. In the hypogene zone, metasomatic and hydrothermal alteration is related to all stages of magmatism but copper mineralization and veining are restricted to a period of 15 to 9 m.y.b.p.related to the early intrusive phases. The copper mineralization and silicate alteration do not fit a simple annular ring model but have been greatly modified by, 1. The existence of an ititial, outer ring, of metasomatic alteration overprinted by an inner.ring of hydrothermal alteration and, 2. later extensive dilating effects of intra- and post-mineral dikes. The hydrothermal clay mineral assemblage in the hypogene zone is illite-chlorite-kaolinite-smectite (beidellite). Preliminary studies indicate that the amount of each of these clays varies vertically and that hydrothermal zonation of clay minerals is possible. However, these minerals alter to illite-kaolinite assemblages in the supergene sulfide zone and to more kaolinite-rich assemblages in the supergene leached zone. Hydrothermal biotite breaks down readily in the supergene zone and is not well preserved in surface outcrops. The distribution of copper minerals in the supergene sulfide enrichment zone is only partly related to rock type being more dependent on topography and the availability of fractures.

Geology of the Rankin Inlet area, Northwest Territories /

The Rankin Inlet area, on the west shore of Hudson Bay in the Northwest Territories, is in the Churchill Structural Province. Metamorphosed volcanic and sedimentary rocks, previously mapped as Archean and part of the Kaminak Group, underlie most of the area. The Rankin Inlet Group consists of greywacke, with minor conglomeratic greywacke, quartzite and dolomite, overlain by massive and pillowed basaltic flows. Gabbro sills intrude the sediments near the base of the volcanic sequence and three serpentinite sills outcrop at the base of the volcanic sequence. The sediments are in fault-contact with quartz monzonite to the south and were intruded by granitic rocks to the northwest. Two periods of folding were defined by the mapping. The first generation folds are recumbent isoclinal folds, with northwest-trending and northeast-dipping axial planes, formed through gravitational sliding. The second generation folds are symmetrically disposed about the axis of the granitic intrusion and have east-southeast trending and nearly vertical axial planes. Whole-rock analysis of 64 rock samples indicates that metasomatic alteration accompanied the intrusion of both the granitic rocks and the serpentinite. The volcanic rocks, gabbro and serpentinite were derived from a magma of oceanic tholeiitic affinities. The stratigraphic sequence and chemistry of the volcanic rocks of the Rankin Inlet Group indicate that this assemblage is correlative with the Hurwitz Group rather than the Kaminak Group and is therefore Aphebian in age.

Geochemistry and petrogenesis of the Proterozoic Pater metavolcanic suite, Spragge, Ontario /

The Pater metavolcanic suite (PVS) was extruded as part O'f the basal Pater Formation of the Huronian Supergroup ca. 2.4 Ga. They Ars classified as wi thin-plate tholeiites associated with an immature ri-fting episode, and are inter layered with associated vol cani clastic and metasedimentary units. Post-solidif ication alteration caused redistribution o-f the alkalies, Sr, Rb, Ba, Cu, and SiO^. Ce, Y, Zr, CFezOs (as total Fe), Al^Os, TiOa, and, PaOa are considered to have remained essentially immobile in least altered samples. Petrogenetic modelling indicates the PVS was derived from the partial melting of two geochemical ly similar sources in the sub-continental lithosphere. Fractionation was characterized by an oli vine-plagioclase assemblage and a sub-volcanic plagioclase-clinopyroxene assemblage. A comparative study indicates that enrichment of the postulated Huronian source cannot be reconciled by Archean contamination. Enrichment is thought to have been caused by hydrous veined metasomatic heterogeneities in the sub-continental lithosphere, generated by an Archean subduct ion event before 2.68 Ga.

Structural, stratigraphic and geochemical studies of the Horwood Peninsula - Gander Bay Area, Northeast Newfoundland /

The Horwood Peninsula - Gander Bay area is located at NE Newfoundland in the Botwood Zone (Williams et a1., 1974) or in the Dunnage Zone (Williams, 1979) of the Central Mobile Belt of the Newfoundland Appalachians. The area is underlain by Middle Ordovician to possible Lower Silurian rocks of the Davidsville and Indian Islands Groups, respectively. Three conformable formations named informally : the Mafic Volcanic Formation, the Greywacke and Siltstone Formation and the Black Slate Formation, have been recognized in the Davidsville Group. The Greywacke and the Black Slate Formations pass locally into a Melange Formation. From consideration of regional structure and abundant locally-derived mafic volcanic olisto- 1iths in the melange, it is considered to have originated by gravity sliding rather than thrusting. Four formations have been recognized in the Indian Islands Group. They mainly contain silty slate and phyllite, grey cherty siltstone, green to red micaceous siltstone and limestone horizons. Repetition of lithological units by F1 folding are well-demonstrated in one of formations in this Group. The major structure in this Group on the Horwood Peninsula is interpreted to be a synclinal complex. The lithology of this Group is different from the Botwood Group to the west and is probably Late Ordovician and/or Early Silurian in age. The effects of soft-sediment deformation can be seen from the lower part of the Davidsville Group to the middle part of the Indian Islands Group indicating continuous and/or episodic slumping and sliding activities throughout the whole area. However, no siginificant depOSitional and tectonic break that could be assigned to the Taconian Orogeny has been recognized in this study. Three periods of tectonic deformation were produced by the Acadian Orogeny. Double boudinage in thin dikes indicates a southeast-northwest sub-horizontal compression and main northeast-southwest sub-horizontal extension during the D1 deformation. A penetrative, axial planar slaty cleavage (Sl) and tight to isocJ.ina1 F1 folds are products of this deformation. The D2 and D3 deformations formed S2 and S3 fabrics associated with crenulations and kink bands which are well-shown in the slates and phyllites of the Indian Islands Group. The D2 and D3 deformations are the products of vertical and northeast-southwest horizontal shortening respectively. The inferred fault between the Ordovician slates (Davidsville Group) and the siltstones (Indian Islands Group) suggested by Williams (1963, 1964b, 1972, 1978) is absent. Formations can be followed without displacement across this inferred fault. Chemically, the pillow lavas, mafic agglomerates, tuff beds and diabase dikes are subdivided into three rock suites : (a) basaltic komatiite (Beaver Cove Assemblage), (b) tholeiitic basalt (diabase dikes), (c) alkaline basalt (Shoal Bay Assemblage). The high Ti02 , MgO, Ni contents and bimodal characteristic of the basaltic komatiite in the area are comparable to the Svartenhuk Peninsula at Baffin Bay and are interpreted to be the result of an abortive volcano-tectonic rift-zone in a rear-arc basin. Modal and chemical analyses of greywackes and siltstones show the trend of maturity of these rocks increasing from poorly sorted Ordovician greywackes to fairly well-sorted Silurian siltstones. Rock fragments in greywackes indicate source areas consisting of plagiogranite, low grade metamorphic rocks and ultramafic rocks. Rare sedimentary structures in both Groups indicate a southeasterly provenance. Trace element analyses of greywackes also reveal a possible island-arc affinity.

The bees of Niagara: a test of the intermediate disturbance hypothesis /

This study examined the bee fauna of the Carolinian Zone in Ontario, Canada. In 2003, 15687 individuals from 152 species of bees were collected. Tliere were many rare species but few abundant species. There were three distinct bee seasons. The Niagara bee assemblage was less diverse compared to other Carolinian Zone assemblages and types of landscapes. This study also examined how anthropogenic disturbance affects the diversity of bee assemblages. The intermediate disturbance hypothesis (IDH) was tested by selecting field sites subject to low, intermediate, and high disturbance. Intermediate disturbance had the highest species richness (SR=1 15) and most bees (N=556I), followed by low disturbance (SR= 100, N=2975), then high disturbance (SR=72, N=1364), supporting the IDH. Increased species richness in areas of intermediate disturbance was due to higher abundance, possibly because more blooming flowers were found there. Bees were larger in high disturbance areas but smaller in areas of high and intermediate disturbance.

Diatoms as indicators of lake trophic status

Relationships between surface sediment diatom assemblages and lake trophic status were studied in 50 Canadian Precambrian Shield lakes in the Muskoka-Haliburton and southern Ontario regions. The purpose of this study was to develop mathematical regression models to infer lake trophic status from diatom assemblage data. To achieve this goal, however, additional investigations dealing with the evaluation of lake trophic status and the autecological features of key diatom species were carried out. Because a unifying index and classification for lake trophic status was not available, a new multiple index was developed in this study, by the computation of the physical, chemical and biological data from 85 south Ontario lakes. By using the new trophic parameter, the lake trophic level (TL) was determined: TL = 1.37 In[1 +(TP x Chl-a / SD)], where, TP=total phosphorus, Chl-a=chlorophyll-a and SD=Secchi depth. The boundaries between 7 lake trophic categories (Ultra-oligotrophic lakes: 0-0.24; Oligotrophic lakes: 0.241-1.8; Oligomesotrophic lakes: 1.813.0; Mesotrophic lakes: 3.01-4.20; Mesoeutrophic lakes: 4.21-5.4; Eutrophic lakes: 5.41-10 and Hyper-eutrophic lakes: above 10) were established. The new trophic parameter was more convenient for management of water quality, communication to the public and comparison with other lake trophic status indices than many of the previously published indices because the TL index attempts to Increase understanding of the characteristics of lakes and their comprehensive trophic states. It is more reasonable and clear for a unifying determination of true trophic states of lakes. Diatom specIes autecology analysis was central to this thesis. However, the autecological relationship of diatom species and lake trophic status had not previously been well documented. Based on the investigation of the diatom composition and variety of species abundance in 30 study lakes, the distribution optima of diatom species were determined. These determinations were based on a quantitative method called "weighted average" (Charles 1985). On this basis, the diatom species were classified into five trophic categories (oligotrophic, oligomesotrophic, mesotrophic, mesoeutrophic and eutrophic species groups). The resulting diatom trophic status autecological features were used in the regressIon analysis between diatom assemblages and lake trophic status. When the TL trophic level values of the 30 lakes were regressed against their fi ve corresponding diatom trophic groups, the two mathematical equations for expressing the assumed linear relationship between the diatom assemblages composition were determined by (1) uSIng a single regression technique: Trophic level of lake (TL) = 2.643 - 7.575 log (Index D) (r = 0.88 r2 = 0.77 P = 0.0001; n = 30) Where, Index D = (0% + OM% + M%)/(E% + ME% + M%); 4 (2) uSIng a' multiple regressIon technique: TL=4.285-0.076 0%- 0.055 OM% - 0.026 M% + 0.033 ME% + 0.065 E% (r=0.89, r2=0.792, P=O.OOOl, n=30) There was a significant correlation between measured and diatom inferred trophic levels both by single and multiple regressIon methods (P < 0.0001, n=20), when both models were applied to another 20 test lakes. Their correlation coefficients (r2 ) were also statistically significant (r2 >0.68, n=20). As such, the two transfer function models between diatoms and lake trophic status were validated. The two models obtained as noted above were developed using one group of lakes and then tested using an entirely different group of lakes. This study indicated that diatom assemblages are sensitive to lake trophic status. As indicators of lake trophic status, diatoms are especially useful in situations where no local trophic information is available and in studies of the paleotrophic history of lakes. Diatom autecological information was used to develop a theory assessing water quality and lake trophic status.

Petrography, Petrochemistry and petrogenesis of Huronian volcanic rocks of the Elliot Lake region, Ontario

In the Elliot lake region of northern Ontario, Yolcanlc lava piles represent the lowermost units of the Huronian SUpergroup. These rocks general1y trend east-west and belong to the Elliot lake Group. They are s1tuated on the north and south limbs or the QuIrke lake Syncline. The volcanIc rocks of this study contain a secondary minerai assemblage consisting of actinolite, biotite, chlorIte, eptdote/cllnozoislte tttanomagnettte and calcite characteristic of greenschist metamorphism. Compilation of data suggests that metamorphism of the volcanic rocks proceeded between 325- and 425-C and between 2.4 and 4.7 kb. Geochemtcally these lavas represent tholeiitic and calc-alkaline assemblages. The tholeiites are character1sttcally enriched tn Fe and Tt and consist mainly of basalts, basaltic andesites and andesites. These rocks are believed to have formed by the partIal melting of a peridottte source at low P-T. In contrast, the calc-alkaline rocks are depleted in Fe and TI, but show a signIficant enrichment In 51 and Zr; andesIte Is the major rock type for thIs assemblage. I·t Is postUlated that the calc-alkalIne sU1te of rocks was the result of eIther the partIal meltIng of abasaltic·magma at shallow depth, or the melttng of s1al1c crustal materIal due to the added we1ght of tholeiitIc material on an unstable crust and to downwarplng processes Inttlated by convection cells.

Geochemistry and petrogenesis of the McElroy and Larder Lake assemblages, Abitibi Greenstone Belt, Northeastern Ontario

The McElroy and Larder Lake assemblages, located in the southern Abitibi Greenstone Belt are two late Archean metavolcanic sequences having markedly contrasting physical characteristics arid are separated from one another by a regional fault. An assemblage is an informal term which describes stratified volcanic and/or sedimentary rock units built during a specific time period in a similar depositional or volcanic setting and are commonly bounded by faults, unconformities or intrusions. The petrology and petrogenesis of these assemblages have been investigated to determine if a genetic link exists between the two adjacent assemblages. The McElroy assemblage is homoclinal sequence of evolved massive and pillowed fl.ows, which except for the basal unit represents a progressively fractionated volcanic pile. From the base to the top of the assemblage the lithologies include Fe-tholeiitic, dendritic flows; komatiite basaltic, ultramafic flows; Mg-tholeiitic, leucogabbro; Mg-tholeiitic, massive flows and Fe-tholeiitic, pillowed flows. Massive flows range from coarse grained to aphanitic and are commonly plagioclase glomerophyric. The Larder Lake assemblage consists of komatiitic, Mg-rich and Fe-rich tholeiitic basalts, structurally disrupted by folds and faults. Tholeiitic rocks in the Larder Lake assemblage range from aphanitic to coarse grained massive and pillowed flows. Komatiitic flows contain both spinifex and massive textures. Geochemical variability within both assemblages is attributed to different petrogenetic histories. The lithologies of the McElroy assemblage were derived by partial melting of a primitive mantle source followed by various degrees of crystal fractionation. Partial melting of a primitive mantle source generated the ultramafic flows and possibly other flows in the assemblage. Fractionation of ultramafic flows may have also produced the more evolved McElroy lithologies. The highly evolved, basal, dendritic flow may represent the upper unit 3 of a missing volcanic pile in which continued magmatism generated the remaining McElroy lithologies. Alternatively, the dendritic flows may represent a primary lava derived from a low degree (10-15%) partial melt of a primitive mantle source which was followed by continued partial melting to generate the ultramafic flows. The Larder Lake lithologies were derived by partial melting of a komatiitic source followed by gabbroic fractionation. The tectonic environment for both assemblages is interpreted to be an oceanic arc setting. The McElroy assemblage lavas were generated in a mature back arc setting whereas the Larder Lake lithologies were produced during the early stages of komatiitc crust subduction. This setting is consistent with previous models involving plate tectonic processes for the generation of other metavolcanic assemblages in the Abitibi Greenstone Belt.

Investigating the potential of thecamoebians (testate amoebae) as bio-indicators of impact of oil sands mining operations on freshwater environments in Northeastern Alberta, Canada

Thecamoebian (testate amoeba) species diversity and assemblages in reclamation wetlands and lakes in northeastern Alberta respond to chemical and physical parameters associated with oil sands extraction. Ecosystems more impacted by OSPM (oil sands process-affected material) contain sparse, low-diversity populations dominated by centropyxid taxa and Arcella vulgaris. More abundant and diverse thecamoebian populations rich in difflugiid species characterize environments with lower OSPM concentrations. These shelled protists respond quickly to environmental change, allowing year-to-year variations in OSPM impact to be recorded. Their fossil record thus provides corporations with interests in the Athabasca Oil Sands with a potential means of measuring the progression of highlyimpacted aquatic environments to more natural wetlands. Development of this metric required investigation of controls on their fossil assemblage (e.g. seasonal variability, fossilization potential) and their biogeographic distribution, not only in the constructed lakes and wetlands on the oil sands leases, but also in natural environments across Alberta.

City of the Falls clippings, 1833, n.d.

The clippings describe the City of the Falls and its attempts by its shareholders to sell lots to this newly developing city. The venture by shareholders W. Allan, James Buchanan, Thomas Clark, J.H. Dunn, Thomas Dixon, General Murray, James Robinson, Samuel Street and William Witla intended to favourably position their city as a destination for “affording an easy approach for the annual assemblage of the Fashionable, the Learned and the Great”. The venture failed due to the building of the Buffalo and Niagara Falls railway.

Entering Youthwork Through Love's Many Pathways: A Poetic Rendition

Entering Youth work Through Love's Many Pathways is a text that wanders and digresses to places where, through poetic inquiry and a Spinozist and Sufi framework, the concepts of immanence, love and becoming can be explored. This thesis is framed as a walk through which the researcher / youth worker along with the reader, traverses through five pathways that she considers necessary in cultivating a meaningful relationship with the youth: opening, strength, listening, trust and unconditional compassion. By means of engaging the “self”, this thesis approaches youth work as a field that is relational and socially interconnected. In this sense, this poetic inquiry seeks to rupture predictable patterns of behaviour. One of the ways I do this is through found poetry. Through this specific form of poetic inquiry, I bring together various voices, an assemblage – Rumi, Rilke, Whitman, Lalla, Mirabai and Song of Songs – in order to find my voice and by extension, to help the youth find their voice through a human connection that goes beyond colour, race, gender etc. In other words, my aim is to actualize the experiences of becoming youth worker while being in a field of immanence where similarities are understood and differences respected. My hope is that this project may offer an example of understanding, celebration, and engagement of our mutual differences, while still being able to relate to one another through the many pathways of love.

Algal and protozoan response to Holocene climate change and anthropogenic impact: a case study from Sluice Pond, MA

Sluice Pond is a small (18 ha) and deep (Zmax 20.0 m) partially meromictic, pond in Lynn, Massachusetts that contains a diverse dinocyst record since the early Holocene. High dinocyst concentrations, including morphotypes not previously described, as well as the preservation of several specimens of cellulosic thecae are attributed to low dissolved oxygen (DO) in the basin. The fossil protozoan record supports the interpretation- thecamoebians were unable to colonize the basin until the middle Holocene and only became abundant when the drought-induced lowstand oxygenated the bottom waters. Protozoans tolerant of low DO became abundant through the late Holocene as water levels rose and cultural eutrophication produced a sharp increase in biochemical oxygen demand (BOD) beginning in the 17th century. Recent sediments contain a dominance of Peridinium willei, indicating cultural eutrophication and the planktonic ciliate Codonella cratera and the thecamoebian Cucurbitella tricuspis in the deep basin. Above the chemocline however, a diverse difflugiid thecamoebian assemblage is present.

DINOFLAGELLATE CYSTS FROM THE LATEST MIOCENE THROUGH MIDDLE PLEISTOCENE OF THE CARIBBEAN SEA, ODP SITE 1000: BIOSTRATIGRAPHY, PALEOCEANOGRAPHY, AND SHOALING OF THE CENTRAL AMERICAN SEAWAY

This is the first detailed study of organic-walled dinoflagellate cysts (dinocysts) and acritarchs for the latest Miocene–Middle Pleistocene of Ocean Drilling Program Site 1000 in the Caribbean Sea. Well-preserved and moderately diverse dinocysts and other palynomorphs reflect the interplay between neritic (carbonate-platform sourced) and oceanic species. The dinocyst biostratigraphy is tied to an existing marine isotope stratigraphy for the interval 5.5–2.2 Ma. For the interval 5.5–3.8 Ma, palynological samples are coupled to published sea-surface temperature estimates based on planktonic foraminiferal Mg/Ca. Changes in dinocyst assemblage composition are noted at ca. 4.6 Ma when shoaling of the Central American Seaway caused a temperature rise in the Caribbean, ca. 3.8–3.6 Ma, during the cold Marine Isotope Stage M2 when pronounced warming occurred, at ca. 2.7 Ma where possible weak cooling may reflect the onset of Northern Hemisphere glaciation, and in the Middle Pleistocene presumably reflecting global cooling and sea-level fall.

Investigating Microbial Trace-fossils and Abiotic Alteration in Hydrovolcanic Tuffs of the Fort Rock Volcanic Field, Oregon

Microbial ichnofossils in volcanic rocks provide a significant record of subsurface microbes and potentially extraterrestrial biosignatures. Here, the textures, mineralogy, and geochemistry of two continental basaltic hydrovolcanic deposits - Reed Rocks and Black Hills - in the Fort Rock Volcanic Field (FRVF) are investigated. Methods include petrographic microscopy, micro and powder X-ray diffraction, SEM/BSE/EDF imaging, energy dispersive spectroscopy, stable isotopes, and X-ray fluorescence. Petrographic analysis revealed granular and tubular textures with biogenic morphologies that include terminal enlargements, septate divisions, branching forms, spiral filaments, and ovoid bodies resembling endolithic microborings described in ocean basalts. They display evidence of behaviour and a geologic context expressing their relative age and syngenicity. Differences in abiotic alteration and the abundance/morphotype assemblage of putative microborings between the sites indicate that water/rock ratio, fluid composition and flux, temperature and secondary phase formation are influences on microboring formation. This study is the first report of reputed endolithic microborings in basalts erupted in a continental lacustrine setting.

Rôle du système rénine-angiotensine intrarénal dans l’hypertension et les dommages rénaux chez les souris transgéniques diabétiques

Plusieurs expériences et études cliniques ont démontré que l’activation du système rénine-angiotensine (RAS) peut induire l’hypertension, un facteur de risque majeur pour les maladies cardiovasculaires et rénales. L’angiotensinogène (Agt) est l’unique substrat du RAS. Cependant, il n’a pas encore été démontré si l’activation du RAS intrarénal peut à elle seule induire des dommages rénaux, indépendamment de l’hypertension systémique, et ainsi jouer un rôle prépondérant dans la progression de la néphropathie diabétique. Afin d’explorer le rôle du RAS intrarénal dans les dommages rénaux, un diabète a été induit par l’injection de streptozotocin chez des souris transgéniques (Tg) surexprimant l’Agt de rat dans les cellules des tubules proximaux du rein (RPTC). Les souris Tg diabétiques ont été traitées soit avec des inhibiteurs du RAS (perindopril et losartan), de l’insuline ou une combinaison des deux pour 4 semaines avant d’être euthanasiées. Pour une autre étude, des souris Tg non-diabétiques ont été traitées soit avec des inhibiteurs du RAS, l’hydralazine (vasodilatateur) ou l’apocynine (inhibiteur de la NADPH oxydase) pour une période de 8 semaines avant l’euthanasie. Des souris non-Tg ont été utilisées comme contrôles. Des cellules immortalisées de tubule proximal de rat (IRPTC) transfectées de manière stable avec un plasmide contenant l’Agt ou un plasmide contrôle ont été employées comme modèle in vitro. Nos résultats ont démontré que les souris Tg présentaient une augmentation significative de la pression systolique, l’albuminurie, l’apoptose des RPTC et l’expression de gènes pro-apoptotiques par rapport aux souris non-Tg. Les mêmes changements ont été observés chez les souris Tg diabétiques par rapport aux souris non-Tg diabétiques. L’insuline et/ou les inhibiteurs du RAS ont permis d’atténuer ces changements, sauf l’hypertension qui n’était réduite que par les inhibiteurs du RAS. Chez les IRPTC transfectées avec l’Agt in vitro, les hautes concentrations de glucose augmentent l’apoptose et l’activité de la caspase-3 par rapport aux cellules contrôles et l’insuline et/ou les inhibiteurs du RAS empêchent ces augmentations. En plus des changements physiologiques, les RPTC des souris Tg présentent aussi une augmentation significative de la production des espèces réactive de l’oxygène (ROS) et de l’activité de la NADPH oxydase, ainsi qu’une augmentation de l’expression du facteur de croissance transformant-beta 1 (TGF-β1), de l’inhibiteur activateur du plasminogène de type 1 (PAI-1), des protéines de la matrice extracellulaire, du collagène de type IV et de la sousunité p47 de la NADPH oxydase. Le traitement des souris Tg avec l’apocynine et le perindopril a permis d’améliorer tous ces changements, sauf l’hypertension qui n’était pas corrigée par l’apocynine. D’autre part, l’hydralazine a prévenu l’hypertension, sans modifier l’albuminurie, l’apoptose des RPTC ou l’expression des gènes pro-apoptotiques. Ces résultats montrent bien que l’activation du RAS intrarénal et l’hyperglycémie agissent de concert pour induire l’albuminurie et l’apoptose des RPTC, indépendamment de l’hypertension systémique. La génération des ROS via l’activation de la NADPH oxydase induit en partie l’action du RAS intrarénal sur l’apoptose des RPTC, la fibrose tubulo-interstitielle et l’albuminurie chez les souris Tg. D’autre part, une expérience en cours a tenté d’encore mieux délimiter les effets de l’activation du RAS intrarénal, tout en éliminant la néphrotoxicité du STZ. Pour cette étude, les souris Tg surexprimant l’Agt de rat dans leurs RPTC ont été croisées aux souris Ins2Akita, un modèle spontané de diabète de type I, afin de générer des souris Akita-rAgt-Tg. Les résultats préliminaires indiquent que le RAS intrarénal est activé dans les souris Akita et que la combinaison avec l’hyperglycémie induit du stress du réticulum endoplasmique (ER) dans les RPTC in vivo. Le stress du ER contribue à l’apoptose des RPTC observée dans le diabète, à tout le moins dans le modèle Akita. Le traitement avec des inhibiteurs du RAS permet d’atténuer certains des dommanges rénaux observés dans les souris Akita-rAgt-Tg.