bluuebunny/crossref_metadata_2025 huggingface dataset:
Crustal seismic velocity and density structure of the Intermontane and Coast belts, southwestern Cordillera
Authors: Spence George D , McLean Nancy A
Published: April 2011

Seismic refraction - wide-angle reflection data were recorded along a 450 km profile across the Intermontane, Coast, and Insular belts of the Canadian Cordillera. Crust and upper mantle structure was interpreted from traveltime inversion and forward-amplitude modelling, and the resultant seismic velocities were used to constrain modelling of the Bouguer gravity data along the profile. A high-velocity, high-density block in the upper 8 km of crust was interpreted as the subsurface extension of Harrison terrane; the Harrison fault at its eastern boundary may extend to at least 8 km depth and perhaps 20 km. Throughout the crust, both seismic velocities and densities are in general high beneath the Insular belt, low beneath the Coast and western Intermontane belts, and intermediate beneath the eastern Intermontane belt. However, densities are unusually low in the lower crust beneath the Coast belt (2800 kg/m3), relative to velocities (6.6-6.8 km/s). This indicates that Coast belt plutonic material is present throughout the crust; strong upper mantle reflectivity, previously interpreted on a Lithoprobe reflection line beneath the western Coast belt, may be high-density residue associated with the unusually low density plutonic material. Based on gravity data, Wrangellia must terminate sharply against the western edge of the Coast belt. In the lower crust, the lowest seismic velocities are found vertically beneath the surface trace of the Fraser fault, where velocities just above the Moho only reach 6.5 km/s, in contrast with 6.8 km/s beneath the western Coast belt and eastern Intermontane belt. This provides support for a subvertical geometry for the Fraser fault, perhaps with a broad zone of diffuse shearing in the lower crust. At this location, the Fraser fault does not appear to vertically offset the Moho, which is well-constrained at a uniform depth of km east of the Harrison fault.
Selective replacement of mollusk shell by chlorite, Lower Cretaceous Longarm Formation, Queen Charlotte Islands, British Columbia
Authors: Haggart James W , Bustin R Marc
Published: April 2011

The shells of molluscan megafauna from Lower Cretaceous coarse-clastic strata of Queen Charlotte Islands, British Columbia, principally ammonites and inoceramid bivalves, commonly show partial replacement alteration to fibrous, Mg- and Fe-rich chlorite. Although Cretaceous volcanic strata are very rare on Queen Charlotte Islands, strata containing the altered shells are generally rich in mafic volcanic detritus, derived from older and widespread Triassic basalts; these basalts are considered to be the source of the Mg and Fe cations present in the chloritic shells. Differences in degree of alteration to chlorite are attributed to local variations in Cretaceous sandstone permeability.
Receiver-function studies in the Trans-Hudson Orogen, Saskatchewan
Authors: Zelt B C , Ellis R M
Published: April 2011

Teleseismic events were recorded on an array of three-component broadband and short-period seismographs in the Trans-Hudson Orogen over a period of almost 3 years. Receiver functions calculated from these data were used in a forward-modelling study to derive the local shear-wave velocity structure beneath 20 stations. Station FFC (Flin Flon), located within the Flin Flon belt, was one of two stations situated on bedrock and produced the highest quality receiver functions. The FFC velocity model correlates well with an interpretation of nearby reflection data and features a distinct lower crust interpreted as Archean basement which cores the entire Reindeer Zone. Both radial and tangential receiver functions at FFC show strong evidence for a northeasterly dipping shallow boundary within rocks of the Flin Flon belt with a dip angle of 20°. Total crustal thickness is 37 km. Eighteen stations are situated on Phanerozoic sedimentary cover ranging in thickness from 0.4 km to greater than 2 km. Receiver functions at these stations display prominent high-amplitude, low-frequency reverberations that obscure more subtle phases associated with deeper structure. Because of this, only the gross crustal velocity structure can be constrained by modelling. Depth to Moho, which is 40-43 km at most stations, is the most strongly constrained feature. Stations with relatively thick crust within the Glennie domain suggest a connection between two regions of thick crust previously inferred from reflection and refraction data. This crustal root, presumably associated with a structural culmination imaged by reflection data and cored by Archean basement, is confined to the southwestern Glennie domain. One-dimensional modelling results show that the reverberations can be explained by a thin layer (<0.7 km) at the top of the sediments with a very high Poisson's ratio (0.4-0.48). The degree to which later arrivals are affected by reverberations is directly related to the parameters of this uppermost layer. We present the results of synthetic studies that demonstrate the sensitivity of receiver functions to this type of feature.
Structural history of the Manitouwadge greenstone belt and its volcanogenic Cu-Zn massive sulphide deposits, Wawa subprovince, south-central Superior Province
Authors: Peterson Virginia L , Zaleski Eva
Published: April 2011

Structural analysis of the Manitouwadge greenstone belt, integrated with detailed mapping and geochronological and petrographic studies, reveals a complex early deformation history that significantly modified the primary distribution of base-metal deposits and alteration zones. The (D3) Manitouwadge synform dominates the map pattern; however, penetrative fabric development and establishment of the tectono-stratigraphy of base-metal deposits mostly predated D3. The D1 Garnet Lake fault, which repeats mineralized horizons within a distinctive lithological sequence, is delineated locally by annealed mylonite. D1 planar fabrics are preserved locally in outcrop and thin section. D2 folding accompanied peak regional metamorphism at upper amphibolite facies. The F2 Agam Lake syncline repeats the volcanic sequence across the southern limb of the Manitouwadge synform. A map-scale F2 sheath fold deforms the Garnet Lake fault. Minor D2 structures include prevalent outcrop-scale folds, locally with sheath geometry, the dominant S2 foliation, and mineral lineations (parallel to fold axes). Northwest-southeast-directed D3 shortening produced the Manitouwadge synform and related regional folds without extensive penetrative fabric development. Flexural slip folding is evident in the inner hinge of the synform where rocks of differing competency are interlayered. Higher strain, stronger fabric development, and a component of simple shear were preferentially partitioned to fold limbs. Relative pre-D3 structural geometries in the inner hinge region of the Manitouwadge synform are not significantly complicated by D3 and younger deformation. Retrodeformation of the mineralized sequence shows systematic stratigraphic patterns in iron formation types, stacked massive sulphide orebodies, and alteration types that can be applied to exploration models.
Magnetic and compositional variations in Proterozoic mafic dykes in Finland, northern Fennoscandian shield
Authors: Airo Meri-Liisa
Published: April 2011

Proterozoic mafic dykes of both tholeiitic basaltic and more magnesian compositions from four areas in Finland have been studied for their magnetic and compositional variations to explain the variation in their aeromagnetic patterns. The highly magnetic more magnesian dykes are characterized with distinctive aeromagnetic anomalies, whereas the tholeiitic dykes are weakly magnetic and associated with faint magnetic signatures. To evaluate the factors that control the primary magnetization and the effects of later geological processes on their ferrimagnetic mineralogy, petrophysical properties of the dykes were correlated with their bulk mineral compositions. The role of ferric iron was of particular interest, as those iron-bearing silicates which participate in the reactions where titanomagnetites are formed or destroyed contain ferric iron in their crystal structures. The early crystallization of hydrous mafic silicates, biotite and amphibole, versus the anhydrous mafic silicate, clinopyroxene (augite), seems to be of key importance to formation of titanomagnetites. As clinopyroxenes can accommodate only minor amounts of ferric iron compared to hydrous mafic silicates, the excess ferric iron can be consumed to form primary titanomagnetites. Therefore it is concluded that the water vapour pressure at the emplacement depth of the dykes is most relevant in terms of the primary ferrimagnetic mineralogy. The originally high total magnetization of rocks that already contain abundant ferrimagnetic minerals will not be greatly changed in secondary processes, as the volume percentage of the secondary fine-grained magnetite is generally small. In addition, the total magnetization of the rocks that are originally deficient in titanomagnetites does not increase significantly.
Fluvial clastic sediment yield in Canada: scaled analysis
Authors: Church Michael , Ham Darren , Hassan Marwan , Slaymaker Olav
Published: April 2011

This report presents a set of maps of regional fluvial sediment yield in Canada, based mainly on the Water Survey of Canada archive of riverine suspended sediment observations. Regional scaling relations for the variation of suspended sediment load with drainage basin area are established to permit data to be adjusted to common areal bases for portrayal of regional variations. For most regions, the specific sediment yield increases downstream, indicating regional degradation of river valleys. In the southern prairies, however, regional aggradation is occurring, and in southern Ontario similar quantities of fluvial sediment are apparently being yielded, on average, over all scales in the landscape. A smoothed regional portrayal of the results is obtained by kriging, which also yields error estimates for locally predicted values of sediment yield. Maps are presented for the standard areas of 1 km2, 102 km2 (10 km × 10 km), and 104 km2 (102 km × 102 km).
Late Quaternary glacial history of Lake Hazen Basin and eastern Hazen Plateau, northern Ellesmere Island, Nunavut, Canada
Authors: Smith I Rod
Published: April 2011

The glacial history of the broad interior of northeastern Ellesmere Island is first documented here. Studies of glacial geomorphology and marine and lacustrine sedimentology indicate that the region was inundated by cold-based ice emanating from the Grant Land Mountains sector of the Innuitian Ice Sheet during the last glacial maximum. Retreat of coalescent, marine-based Ellesmere and Greenland ice from Robeson Channel had started by 10.1 ka BP and reached the mouths of many fiords along southeast Hazen Plateau by 8 ka BP. Proglacial meltwater channels emanating from plateau ice caps, crosscut lateral meltwater channels marking the retreat of Grant Land Mountain ice. The crosscutting is interpreted to reflect an early Holocene growth of plateau ice caps concurrent with the retreat of marine-based margins. This suggests that initial regional ice retreat was eustatically controlled. Stabilization of glacier margins at the heads of fiords occurred by 7.5-7 ka BP, after which land-based margins retreated as little as 10 km by 6 ka BP. Across much of northeastern Hazen Plateau, however, Grant Land Mountain ice retreated more rapidly. This more rapid retreat was accentuated by the impoundment of proglacial lakes against the plateau to the south and the subsequent breakup of ice by calving. Glaciers continued to occupy much of Lake Hazen Basin at 5.3 ka BP, after which they broke up rapidly in a proto-Lake Hazen, retreating to margins at, or behind, those of the present by 5 ka BP.
A 15 kHz cross-hole seismic survey across a fracture at the AECL Underground Research Laboratory
Authors: Hayles J G , Everitt R A , Woodcock D R
Published: April 2011

A 15 kHz cross-hole seismic tomography survey was completed between two boreholes that cross a well-known subvertical fracture called the "Room 209 fracture" on the 240 Level of the Atomic Energy of Canada Limited Underground Research Laboratory. This survey measured in situ P- and S-wave velocity and amplitude relations across the fracture between the two boreholes. A velocity anisotropy of about 1.5% (peak-to-peak) exists in the rock mass for both P and S waves. Consistently faster velocities were observed for rays oriented roughly parallel to the Room 209 fracture. This anisotropy is consistent with geological and geotechnical models of microcrack populations for the region. Tomographic velocity images for both the P- and S-waves show a distinct change across the fracture. Higher velocities occur east of the fracture, whereas lower velocities occur to the west. The velocity differences indicate minor changes in the rock structure from one side of the fracture to the other which correlate with observed differences in alteration and fracture frequency. There is a slight reduction in velocity at the fracture itself. A study of seismic amplitudes was also completed. A weak anisotropy also exists in the amplitude data, with higher amplitudes for rays that parallel the fracture direction. The P-wave attenuation ranges between 0.03 and 0.7 dB/m across the survey panel. The region of the fracture shows a subtle increase in the P-wave attenuation of about 0.04 dB/m above the local background. These measurements provide a useful demonstration of the sensitivity of the technique. The results correlate well with geological models and simple physical models for seismic wave propagation in sparsely fractured granite.
The climate of North America and adjacent ocean waters ca. 6 ka
Authors: Gajewski K , Vance Robert , Sawada M , Fung Inez , Gignac L Dennis , Halsey Linda , John Jasmin , Maisongrande Philippe , Mandell P , Mudie Peta J , Richard Pierre JH , Sherin A G , Soroko Jason , Vitt Dale H
Published: April 2011

The climate of North America and the adjacent ocean at 6000 BP was estimated using five independent approaches. Using pollen data, the terrestrial climate was estimated by the movement of ecozone boundaries and by the method of modern analogues. Both analyses indicate warmer temperatures in the western Great Lakes area and the northern Great Plains. A model of Sphagnum-dominated peatland initiation, when forced by Canadian Climate Model 6 ka output projected a cooler and (or) wetter climate for continental western North America. Contrary to this, a reconstruction of the distribution of Sphagnum-dominated peatlands in western Canada indicates that they were located north of their modern distribution, suggesting warmer and (or) drier conditions at 6000 BP. This interpretation is strengthened by observations of lower lake levels at 6000 BP in western Canada. This drier climate may have been associated with warmer conditions as indicated by the quantitative climate reconstructions. In general, eastern North America was drier, while western North America was warmer and drier at 6 ka compared to the present. A model of vegetation and carbon storage, when forced using 6 ka Canadian Climate Model and pollen-based climate reconstructions, showed an increase in area covered by boreal forest, extending north and south of the present location. This was not, however, verified by the fossil data. Additionally, the model showed little total change in carbon storage at 6 ka in the terrestrial biosphere. Estimated sea surface temperatures off eastern Canada suggest warmer surface waters at 6 ka, in agreement with reconstructions based on terrestrial records from the eastern seaboard.
Cretaceous intrusions in the Commerce Mountain and adjacent areas of southeastern British Columbia and southwestern Alberta
Authors: Goble R J , Treves S B , Murray V M
Published: April 2011

An older oversaturated monzonitic and a younger undersaturated syenitic suite of Cretaceous igneous rocks are present at Commerce Mountain and adjacent areas of the southern Canadian Rockies. The undersaturated suite consists of foid-bearing alkali feldspar syenite and trachyte, with lesser amounts of phonolite and foid syenite. Normative data indicate a higher degree of undersaturation attributable to the presence of garnet. Sr and Nd isotopic data are consistent with generation of the magma by partial melting of an enriched source in the upper mantle or the lower continental crust; Pb isotopic data are more consistent with a source in the lower continental crust. High Sr and Ba concentrations in analcime-bearing alkali feldspar megacrysts support early crystallization at high pressure. Replacement of the analcime by muscovite suggests emplacement and continued crystallization at shallow depth under low pressures, at which the analcime was unstable. Prior to emplacement in the upper crust, the Commerce Mountain suite evolved in composition from mafic analcime-bearing perthite syenite to felsic analcime-nepheline-bearing perthite syenite to nepheline (micro)monzosyenite and to analcime (micro)syenite compositionally similar to analcime phonolites found in adjacent areas. Extensive metamorphic-metasomatic alteration suggests that Commerce Mountain was a volcanic center, possibly associated with the eruption of the Crowsnest Formation volcanic rocks.
The 3-D crustal structure in the Manicouagan region: new seismic and gravity constraints
Authors: Eaton David W , Hynes Andrew
Published: April 2011

Lithoprobe line 55 represents an oblique seismic crossing of tectonic domains in the Manicouagan region of the Grenville Province in eastern Quebec that has provided a basis for construction of a 3-D model of crustal structure. Reprocessing of the seismic profile presented here has enhanced the imaging of prominent, out-of-the-plane reflection zones that originate from high-pressure metamorphic rocks northwest of the line. We show that after conventional migration the apparent dips of out-of-plane reflections can be compared with regional foliation trends, but the reflection orientations, in themselves, provide only weak constraints on the orientation of out-of-plane of reflectors. We describe and implement several graphical techniques to estimate reflector orientation near large bends in the profile. Using a prestack processing technique, we find poorly resolved but shallow dips and approximately eastward strike directions for reflections from Berthé, Hart Jaune, and Tshenukutish terranes near Relais Gabriel. While many of these seismically derived attitude measurements are broadly consistent with existing 3-D structural models, some discrepancies have yet to be fully resolved. The Bouguer gravity field in this area is dominated by several intense anomalies, including the Grenville Front gravity low and the Manicouagan Plateau gravity high. The residual gravity field, obtained by subtracting the predicted anomalies for these features from the Bouguer gravity field, provides evidence in support of a lateral basement ramp.
Global water balance and atmospheric water vapour transport at last glacial maximum: climate simulations with the Canadian Climate Centre for Modelling and Analysis atmospheric general circulation model
Authors: Vettoretti G , Peltier W R , McFarlane N A
Published: April 2011

A series of new simulations of the climate state at last glacial maximum has been performed using the Canadian second-generation atmospheric general circulation model and are described herein. The primary goal has been to assess the dynamic changes in the global water balance and water vapour transport that were characteristic of the climate state during this epoch of Earth's history. We pay special attention to comparisons of the atmospheric model simulations of last glacial maximum climate with those produced with a much simpler coupled energy balance-ice-sheet model, which has been designed to simulate the late Pleistocene cycle of glacial-interglacial ice volume variations. Our analyses, using the atmospheric model, demonstrate that the vigour of the hydrological cycle was markedly decreased under last glacial maximum conditions, as would be expected on the simplest thermodynamic grounds. The primary components of the hydrological cycle in the atmospheric model, namely precipitation and evaporation, constitute essential mechanisms that control ice-sheet mass balance. We also investigate changes in the Northern Hemisphere stationary wave patterns, as well as changes in the total and eddy moisture transport by the global circulation at last glacial maximum to illustrate the role played by the dynamics of the atmosphere in the maintenance of the Northern Hemisphere ice sheets. In particular, we find that the enhancement of the stationary wave pattern along with the convergence in atmospheric water vapour transport produces increased cooling and snow accumulation at last glacial maximum over the southeastern lobes of the Laurentide Ice Sheet. This suggests an explanation for the previously unexplained extension of these lobes deep into the New England states.
Glaciological reconstruction of the Laurentide Ice Sheet: physical processes and modelling challenges
Authors: Marshall Shawn J , Tarasov Lev , Clarke Garry K.C , Peltier W Richard
Published: April 2011

Current understanding of Pleistocene ice-sheet history is based on collective inferences from three separate avenues of study: (1) the geologic and paleoceanographic records, (2) the isostatic record, and (3) the behaviour of contemporary glaciers and ice sheets. The geologic record provides good constraint on the areal extent of former ice sheets, while isostatic deflection patterns provide important information about late-glacial ice-sheet thickness. The picture emerging from geologic and isostatic deductions is suggestive of a thin and mobile Laurentide Ice Sheet relative to present-day Greenland and Antarctica. We model Laurentide Ice Sheet evolution through a glacial cycle to explore the glaciological mechanisms that are required to replicate the geologic and isostatic evidence. A number of glaciological processes important to the ice-sheet evolution are not fully understood, including marine-based ice dynamics, iceberg calving, rheologic properties of ice, and basal flow dynamics. We present a spectrum of glacial cycle simulations with different treatments of poorly constrained physical processes. We conclude that glaciological model reconstructions can only be reconciled with the late-glacial geologic record of a thin, low-sloping Laurentide Ice Sheet by invoking (1) extremely deformable ice, (2) widespread basal flow, or (3) paleoclimate-ice-sheet fluctuations which give last glacial maximum ice sheets that are far from equilibrium.
Introduction of the D-genome chromosomes from bread wheat into hexaploid triticale with a complete rye genome
Authors: Lukaszewski A. J. , Apolinarska B. , Gustafson J. P.
Published: April 2011

Hexaploid triticale (× Triticosecale Wittmack) lines selected from the progeny of octoploid × tetraploid triticale hybrids were karyotyped using C-banding. The number of D-genome chromosome pairs substituted for A- and (or) B-genome chromosomes ranged from 0 to 4, averaging 2.1 substitutions per line. Every D-genome chromosome was present in at least 1 of the 70 lines analyzed. The most frequent were chromosomes 3D and 6D, followed by 1D. Of the 14 possible substitutions, 12 were present in the homozygous condition, 1 (4D/4B) was still segregating, and 6D/6B was absent. With the exception of one 1D/1R substitution and one 7RS/4DS translocation, all lines had a complete rye genome.

Key words: triticale, chromosome substitutions, D genome.
The association of a gene for leaf rust resistance with the chromosome 7D suppressor of stem rust resistance in common wheat
Authors: Dyck P. L.
Published: April 2011

Backcross lines of gene LrT2 for resistance to leaf rust in the common wheat (Triticum aestivum L.) 'Thatcher' unexpectedly show improved resistance to stem rust compared with that of the recurrent parent. Genetic–cytogenetic evidence indicates that LrT2 is on chromosome 7D, which is known to carry the "suppressor" gene(s) that prevent the expression of stem rust resistance conferred by other genes in 'Canthatch'. Thus, LrT2 may be a nonsuppressing allele of the suppressor gene(s) or be closely linked to such an allele. LrT2 has been designated Lr34.

Key words: Triticum, wheat, rust resistance.
Cytology of triploid and pentaploid hybrids of Elymus trachycaulus × Pseudoroegneria spicata and P. spicata ssp. inermis
Authors: Aung Taing , Walton P. D.
Published: April 2011

Emasculated clones of tetraploid and octaploid Elymus trachycaulus crossed with Pseudoroegneria spicata yielded 69 triploids and 13 pentaploid hybrids. The triploid hybrids were morphologically intermediate between the parental species but the pentaploid hybrids resembled E. trachycaulus more closely than P. spicata. A very high degree of plant size variability (very weak to very vigorous) was observed among the 50 triploids that survived to maturity. The variability among the pentaploids, though apparent, was not high. Mean chromosome associations among the selected eight triploids varied from low multivalent formation at meiosis (7.60 I + 6.18 II + 0.24 III + 0.08 IV) to high multivalent-forming meiosis (7.28 I + 5.66 II + 0.32 III + 0.36 IV). The bivalent configurations in these triploids were attributed to homoeologous pairing between the S1 genome of P. spicata and S genomes of E. trachycaulus and the multivalents indicated intergenomal and intragenomal pairings. Mean chromosome associations of 5.22 I + 11.94 II + 1.97 III in 78.7% and 7 I + 14 II in 21.3% of the 150 cells were distributed among the three pentaploid hybrids. The low frequency of trivalents and the absence of multivalents higher than trivalent configurations suggest that homoeologous pairing was substantially reduced and there was no intergenomal and intragenomal pairing in these 2n = 35 x hybrids. Fourteen triploids and three pentaploid hybrids were produced from 4x and 8x forms of E. trachycaulus and P. spicata spp. inermis crosses. The triploids were intermediate between the parents but the pentaploids were more similar to E. trachycaulus. Mean chromosome associations in the triploids (6.020 I + 5.315 II + 0.554 III + 0.235 IV + 0.250 V + 0.048 VI + 0.03 VII) and in the pentaploids (3.50 I + 10.18 II + 3.54 III + 0.13 IV) indicated a very high degree of intergenomal and intragenomal pairing in the triploids; nevertheless, it was greatly reduced in the pentaploids. The Pseudoroegneria spicata ssp. inermis genome may have gene(s) that affect a high degree of intergenomal and intragenomal pairing in triploid hybrids with E. trachycaulus. However, in pentaploid hybrids (SS HH S2) the S and H genomes of E. trachycaulus in double dose seem to have restored its regular meiotic bahaviour, at least partially, and reduced homoeologous pairing as well as intergenomal and intragenomal pairing.

Key words: Elymus trachycaulus, Pseudoroegneria spicata, regular meiotic behaviour, double dose, intergenomal pairing, intragenomal pairing.
Production, morphology, and cytogenetics of intergeneric hybrids of Elymus L. species with Triticum aestivum L. and their backcross derivatives
Authors: Yen Yang , Liu Dajun
Published: April 2011

Elymus canadensis L. (2n = 28, SSHH), E. dahuricus Turcz. ex Griseb. (2n = 42, SSHH??), and E. cylindricus (Franch.) Honda (2n = 42, SSHH??) were successfully hybridized with Triticum aestivum L. cv. Chinese Spring (2n = 42, AABBDD) by in vivo – in vitro embryo culture. The F1 hybrids were male sterile and morphologically intermediate to their parents. The average numbers of associated chromosome arms per cell were 0.24, 2.04, and 0.65, and the mean arm association frequencies were 0.0086, 0.0486, and 0.0155, respectively. The first backcross derivatives all resulted from fusion of an euploid, hypoploid, or hyperploid unreduced F1 female gamete with a normal male gamete of common wheat. They had average numbers of associated arms per cell of 27.10, 24.36, and 23.84, and average chromosome arm association frequencies of 0.644, 0.580, and 0.568, respectively. First backcross derivatives were male sterile but morphologically, closer to their wheat parents. This study shows that no homologous genomes exist between Elymus and Triticum and that gene transfer between these two genera would be very difficult but not impossible.

Key words: cytogenetics, Elymus L., Triticum L., hybrid (intergeneric).
Cytomixis in Agropyron cristatum
Authors: Bauchan Gary R. , Linkous Li-Ching Wang , Tai William
Published: April 2011

An Agropyron cristatum plant (CB-9-41), crested wheat grass, and its vegetative clones have been identified that contain pollen mother cells that have a gain or a loss in chromatin (DNA). CB-9-41 was identified during the course of an experiment to determine the effectiveness of colchicine on the doubling of the chromosome complement. The seeds that produced this plant were presoaked and then treated with a 0.1% aqueous solution of colchicine for 12 h. All stages of meiosis were studied in the original colchicine-treated plant and three vegetative clones that were obtained 17 years later. Approximately 40% of the pollen mother cells had meiotic irregularities. These irregularities were caused by multipolar meiosis (23%), precocious separation of bivalents at metaphase (8%), inversions (6%), and cytomixis (11%). The gain or loss of chromatin occurred as a result of cytomixis.

Key words: crested wheat grass, extragenomic chromatin, multipolar meiosis, colchicine.
Synthetic and natural hybrids of Psathyrostachys huashanica
Authors: Wang Richard R. -C.
Published: April 2011

Three synthetic hybrids and two natural hybrids involving Psathyrostachys huashanica are reported. Gross spike morphology of the hybrids of Pseudoroegneria cognata and Pseudoroegneria spicata ssp. inermis with P. hauashanica was not as indicative of hybridity as in other hybrids involving P. huashanica. Meiotic analyses of these two synthetic hybrids confirmed that little homology exists between the genomes S and Nh. Coenocytism in the hybrids P. huashanica × Secale montanum led to the formation of pseudomicrospores in nondehiscent anthers. No metaphase through telophase chromosome stages could be observed and thus the relationship between genomes Nh and R could not be assessed. Intermediate spike morphology of, and the sterility in, natural hybrids of P. huashanica with P. fragilis and P. juncea substantiated their hybridity. High meiotic pairing in hybrids between P. huashanica and P. fragilis, averaging 1.03 I + 6.48 II, indicated a close relationship between the two species. Occasional high pairing and frequent abnormal meiosis, manifested by degenerating prophase pollen mother cells (PMCs) and empty anthers lacking PMCs of later stages, in the hybrid P. huashanica × P. juncea suggested a more distant relationship between the parental species. It is concluded that P. fragilis is more closely related to P. huashanica than P. juncea.

Key words: hybrid (intergeneric), hybrid (interspecific), genome, coenocyte, chromosome diminution, Psathyrostachys, Pseudoroegneria, Secale.
Inheritance of some physiological factors of productivity in barley
Authors: Sarrafi A. , Planchon C. , Ecochard R. , Sioud Y.
Published: April 2011

Reciprocal crosses were made among seven barley genotypes of diverse origin. Parents and 42 F1's were grown in a randomized block design with four replications in the greenhouse. Chlorophyll fluorescence activity of the penultimate leaf (below flag leaf) of the main stem at flowering were measured for each plant. Leaf blade area and its duration were also determined for the above-mentioned leaves. "Leaf blade area × leaf life duration" was also used as a trait. Results of diallel analysis showed that both general and specific combining abilities were significant for all the characters studied. General combining ability values and effects were usually more important than those of specific combining ability, showing the importance of additive genetic control for the traits. Reciprocal effects were significant only for chlorophyll fluorescence activity. Narrow sense heritability values for leaf area, leaf duration, and its chlorophyll fluorescence activity were 87.9, 66.8, and 77.4%, respectively.

Key words: combining ability, reciprocal effect, heritability, fluorescence, leaf area.
A gene involved in the resistance of wheat to wheatgrass powdery mildew fungus
Authors: Tosa Y. , Tsujimoto H. , Ogura H.
Published: April 2011

A gene for resistance to Erysiphe graminis was detected in the common wheat cultivars 'Norin 4', 'Norin 26', 'Norin 29', 'Shin-chunaga', and 'Penjamo 62', using a hybrid culture derived from E. graminis f.sp. agropyri × E. graminis f.sp. tritici. The gene was located on chromosome 1D and designated Pm10. Pm10 was considered to be involved in the resistance of wheat to the wheatgrass powdery mildew fungus.

Key words: wheat, resistance, powdery mildew, Erysiphe graminis.
Colchicine-induced desynaptic mutations in Lathyrus odoratus L. and L. pratensis L.
Authors: Khawaja H. I. T. , Ellis J. R.
Published: April 2011

Partially desynaptic mutant plants were observed in colchicine-treated, undoubled Lathyrus odoratus (2n = 14) and L. pratensis (2n = 14) and also in a L. odoratus (C1) seedling with 2n = 27 and in a triploid (C0) L. pratensis (2n = 21). The affected plants showed varying numbers of univalents at metaphase I and reduced fertility. A total of seven independent cases of desynapsis were observed. In diploid L. odoratus the cytology of one of the mutants was recorded for three consecutive generations and all the plants showed partial desynapsis. This suggested that the mutant plants were true breeding and the cytological abnormality was an inherited trait. Inheritance studies in partially and totally desynaptic mutant lines of diploid L. odoratus indicated that the two mutations were monogenic recessive, nonallelic, and not linked.

Key words: Lathyrus, desynaptic mutation.
Karyological identification of two taxa of the Anopheles balabacensis complex from Burma
Authors: May Khin
Published: April 2011

Giemsa and Hoechst staining of neuroblast chromosomes were used to identify two strains of the Anopheles balabacensis complex from Burma. The laboratory colony of Kwan-ka-thaung (KKT) strain is shown to correspond to A. dirus A, while the laboratory colony of Taikkyi (TKK) strain corresponds to A. dirus C as defined by earlier studies on material from Thailand.

Key words: Anopheles chromosomes, A. dirus A, A. dirus C.
Suppression of homologous pairing between chromosomes of A and B genomes of 4x and 6x wheats by Hordeum californicum Covas and Stebbins
Authors: Balyan H. S. , Fedak G.
Published: April 2011

Three hybrids of Triticum turgidum cv. Ma with Hordeum californicum × T. aestivum cv. Chinese Spring amphiploid were obtained at a frequency of 1.6% of the pollinated florets. Meiotic analysis of the hybrid plants revealed an average chiasma frequency per pollen mother cell ranging from 15.27 to 17.60. The lower than expected chromosome pairing in the hybrid plants was attributed to the suppression of pairing between homologous wheat chromosomes by pairing regulatory gene(s) in H. californicum.Key words: intergeneric hybrids, Hordeum californicum, Triticum turgidum, meiosis, chromosome pairing.
Relation between loss of chromosome associations at metaphase I and interference estimates in rye
Authors: Roca A. , Naranjo T. , Goicoechea P. G. , Giraldez R.
Published: April 2011

Interference between metaphase I associations (bonds) in specific segments of the chromosomes involved in translocation T242W of rye has been studied. Different values of coincidence were obtained at mid- and late metaphase I for all segment pairs analyzed. At mid-metaphase I there is negative interference between segments opposite to the translocation breakpoint and there is no cross-centromere interference. At late metaphase I there is negative interference in all these segment pairs. The comparison between mid- and late metaphase I cells also indicated that the frequency with which some of these segments are associated decreases along this stage. The possible causes of this decrease and its relation to the differences in coincidence estimates are discussed.Key words: Secale cereale L., translocations, chiasma interference.
Cytological evidence bearing on the origin of the B genome in polyploid wheats
Authors: Kerby K. , Kuspira J.
Published: April 2011

To help elucidate the origin of the B genome in polyploid wheats, karyotypes of Triticum turgidum, Triticum monoccum, and all six purported B genome donors were compared. The analysis utilized a common cytological procedure that employed the most advanced equipment for the measurement of chromosome lengths at metaphase in root tip cells. A comparison of the karyotypes of T. turgidum and T. monococcum permitted the identification of B genome chromosomes of T. turgidum. These consist of two SAT pairs, one ST pair, three SM pairs, and one M pair of homologues. Comparisons of the chromosomes of the B genome of T. turgidum with the karyotypes of the six putative B genome donors showed that only the karyotype of Aegilops searsii was similar to the one deduced for the donor of the B genome in T. turgidum, suggesting that Ae. searsii is, therefore, the most likely donor of the B genome to the polyploid wheats. Support for this conclusion has been derived from geographic, DNA-hybridization, karyotype, morphological, and protein data reported since 1977. Reasons why the B genome donor has not been unequivocally identified are discussed.Key words: phylogeny, karyotypes, Triticum turgidum, Triticum monococcum, B genome, B genome donors.
Chromosomal pairing in deer mice heterozygous for the presence of heterochromatic short arms
Authors: Hale David W. , Greenbaum Ira F.
Published: April 2011

The pattern of chromosomal pairing was analyzed in male deer mice (Peromyscus maniculatus and Peromyscus sitkensis) heterozygous for the presence of heterochromatic short arms. G- and C-banding of somatic metaphases indicated that the presence of heterochromatic short arms increased the length of chromosome 4 by 15% in P. sitkensis and that of chromosome 8 by 9% in P. maniculatus. Analysis of silver-stained late zygotene and early pachytene nuclei revealed a low frequency of unequal axial lengths in the synaptonemal complexes corresponding to the heteromorphic bivalents. All mid- and late pachytene nuclei, however, exhibited fully paired synaptonemal complexes with equalized axial lengths. These observations suggest the existence of an adjustment mechanism which functions to equalize the lengths of the two axes of the heteromorphic synaptonemal complex.Key words: synaptonemal complex, Peromyscus, heterochromatin, chromosomal polymorphism, synaptic adjustment.
Visualization of kinetochores in mammalian meiotic preparations and observations of argentophilic differences between mitotic and meiotic kinetochores
Authors: Sudman Philip D. , Greenbaum Ira F.
Published: April 2011

Brief staining with AgNO3 was found to differentially stain the kinetochores of chromosomes from diakinesis – metaphase I and metaphase II nuclei of mammals. The results differ from those of Giemsa-stained or C-banded preparations as the silver-stained meiotic kinetochores are clearly distinguishable from both constitutive heterochromatin and euchromatin. Silver-staining is presented as a valuable method for the staining of meiotic material because it allows for the positive identification of centromeric position and orientation with respect to chiasmata. The nonargentophilic nature of the centromere (kinetochore) region of spermatogonial metaphase chromosomes in some species suggests a fundamental structural difference between mitotic and meiotic kinetochores.Key words: kinetochore, meiosis, mammal.
Nonrandom transition from asymmetrical to symmetrical hybrid DNA during meiotic recombination
Authors: Kalogeropoulos Angelos , Rossignol Jean-Luc
Published: April 2011

During meiotic recombination, in the b2 gene of Ascobolus immersus hybrid DNA can be formed either on only one (asymmetrical hybrid DNA) or on both (symmetrical hybrid DNA) interacting chromatids. The two phases can be found in the same meiosis, involving the same two interacting chromatids with the symmetrical phase located on the right with regard to the asymmetrical one. We show that the transition from the asymmetrical to the symmetrical phase occurs in a defined region located within the left part of the gene, which is closer to the initiation region. Once formed, the symmetrical hybrid DNA phase seems always to extend to the rightmost mutation sites. This contrasts with asymmetrical hybrid DNA extension, which when it stays in asymmetrical form, may stop within the gene.Key words: Ascobolus immersus, heteroduplex DNA distribution.
Distributed strain sensing for structural monitoring applications
Authors: DeMerchant Michael , Brown Anthony , Smith Jeff , Bao Xiaoyi , Bremner Theodore
Published: April 2011

Strain sensors are a valuable tool for assessing the health of structures. The University of New Brunswick, in conjunction with ISIS Canada, is developing a distributed fibre optic strain sensor based on Brillouin scattering. This sensor can provide a virtually unlimited number of measurement points using a single optical fibre. A description of the operating principles of the system is given, along with a summary of laboratory test results. Strain measurement accuracy as high as approximately ±11 µε has been demonstrated at 1 m spatial resolution. Spatial resolutions as short as 100 mm can be used, although with decreased strain measurement accuracy. Future development of the technology will include an enhancement allowing both strain and temperature to be measured simultaneously.Key words: strain sensor, fibre optics, distributed sensing, structural monitoring, Brillouin scattering.
On the failure modes and strength of steel-wood-steel bolted timber connections loaded parallel-to-grain
Authors: Quenneville J HP , Mohammad M
Published: April 2011

The current Canadian code provisions for the design of timber bolted connections were essentially developed based on connections showing a ductile behavior and then further modified to account for situations where connections fail in a brittle way. An experimental study was undertaken to evaluate the strength of bolted connections specifically experiencing a brittle mode of failure. Specimens consisting of steel-wood-steel connections with either 19.1 mm or 12.7 mm bolts were tested in tension. Test variables included end distance, bolt spacing, row spacing, number of bolts per row, number of rows, thickness and species of wood member, glulam or sawn lumber members. Connections were tested to the ultimate to observe possible modes of failure as variables were changed. Results show that the current Canadian standard approach to evaluate the resistance of timber bolted connections is not optimal although conservative. Brittle modes of failure such as row shear-out, group tear-out, and splitting were observed. The resistances calculated using the O86.1 design provisions are as little as a third as compared to tested results. Also, the design equations do not allow the designer to take advantage of the increases in strength as a result of increases in row spacing, as observed in tests. Analysis of the results show that the longitudinal shear stress at failure is related to a parameter which is a function of the smaller distance (end distance or bolt spacing) and the specimen thickness. This relation was used to formulate design equations to predict the row shear-out and group tear-out strengths of glulam specimens using the specified strength values listed in O86.1. As well, it was found that Mode I of the European yield model is the only ductile ultimate failure mode and that other equations for bearing failure can be neglected. In this paper, the research program is described, results are presented, and an alternate design approach is proposed to predict the failure mode and the ultimate strength of steel-wood-steel bolted connection groups.Key words: bolt, connection, strength, failure, design, code, ductile, brittle.
Traitement des eaux usées par coagulation-floculation avec recirculation des boues chimiques : Évaluation et validation à grande échelle
Authors: Monette Frédéric , Brière François G , Létourneau Michel , Duchesne Marc , Hausler Robert
Published: April 2011

Two sequences of tests were carried out at the Centre d'épuration Rive-Sud wastewater treatment plant (Longueuil, Que.) to evaluate the performances of a coagulation-flocculation process with chemical sludge recycling. The tests consisted in following the evolution of the quality of the treated water when two flowsheets are supplied simultaneously in parallel with the same wastewater, one flowsheet incorporating the sludge recycling process. Results showed that the recycled sludge contributes significantly to water degradation compared with a classical coagulation-flocculation system. These results do not corroborate the previous work done by Monette et al. (F. Monette et al. Canadian Journal of Civil Engineering, 27: 702-718, 719-734, 2000). The problems observed are explained by inadequate plant installations for sludge recycling. High coagulant concentrations also limit the gains in efficiency associated with recyling. The process reacts rapidly to wastewater loading and reagent modifications. The recycled sludge conditioning is slightly more difficult because of the small particles created by recycling pump turbulence. Finally, turbidity measurements in the flocculator water tank could be used as an excellent indicator for sludge recycling load estimation.Key words: recycling, sludge, coagulation-flocculation, treatment, wastewater, full scale.
Traitement des eaux usées par coagulation-floculation avec recirculation des boues chimiques : Influence des réactifs
Authors: Monette Frédéric , Brière François G , Létourneau Michel , Duchesne Marc , Hausler Robert
Published: April 2011

Three series of tests were carried out at laboratory and pilot levels to examine the functions of reagents (coagulant, flocculant, sludge) involved in a coagulation-flocculation process with chemical sludge recycling. Results showed that the recycled sludge participates favourably in the process. The gains in efficiency are particularely significant for lower coagulant concentrations when flocculant concentration is not limitative. The pollutant removal increases with the sludge recycling load but seems reversible and dependent on coagulant concentration. Results also revealed the advantages of recycling sludge before injecting coagulant. To decrease the total chemical costs at a wastewater treatment plant, the strategy must focus on diminishing the coagulant concentration and increasing the flocculant concentration while maintaining a sufficient recycling sludge load to ensure gains in efficiency.Key words: recycling, sludge, preformed flocs, reagents, coagulation-flocculation, treatment, wastewater.
Shear in plain, bed joint reinforced, and post-tensioned masonry
Authors: Lissel Shelley L , Shrive Nigel G , Page Adrian W
Published: April 2011

Masonry is cost competitive on a life cycle basis with other forms of construction, and should therefore be considered as a structural material more frequently by both architects and engineers. Post-tensioned geometric sections of masonry are structurally efficient wall systems. Post-tensioning with carbon fibre reinforced polymer (CFRP) is an attractive solution to potential corrosion problems with unbonded tendons. Tests on CFRP post-tensioned diaphragm walls have revealed that shear strength in prestressed masonry is an area deserving more study and improvement. The tests also showed that the bonding pattern of the masonry at the web-flange junction can have a substantial effect on the resulting strength of that connection. A test series to evaluate the effects of prestress force and bed reinforcement on shear strength has been carried out and a summary of the results is presented here. Tests to determine the effect of bonding pattern on the strength of the web-flange connection have also been conducted.Key words: post-tensioning, masonry, shear, FRP tendons, corrosion-free.