bluuebunny/crossref_metadata_2025 huggingface dataset:
Symbiotic Innovation in the Oxymonad Streblomastix strix
Authors: LEANDER BRIAN S. , KEELING PATRICK J.
Published: July 2005

ABSTRACT. Streblomastix strix is an enigmatic oxymonad found exclusively in the hindgut of the damp‐wood termite Zootermopsis. Streblomastix has a number of unusual morphological characters and forms a complex but poorly understood symbiosis with epibiotic bacteria. Here we described the ultrastructure of S. strix, with emphasis on the axial cytoskeleton and cell‐cell associations, in its normal state and when treated with antibiotics. In untreated cells, epibiotic bacteria were orderly arranged end‐to‐end on six or seven longitudinal vanes, giving S. strix a stellate appearance in transverse section. The epibiotic bacteria were unusually long bacilli of at least three different morphotypes. Bacteria adhered to the oxymonad host by distinct cell‐cell junctions that protruded between the poles of adjacent epibiotic bacteria. Treating termites with the antibiotic carbenicillin led to the loss of most (but not all) of the bacteria and the transformation of 5. strix from a long slender cell to a teardrop‐shaped cell, where the axostyle was compacted and became bifurcated near the posterior end.
Phylogenetic Position of Species in the Genera Anoplophrya, Plagiotoma, and Nyctotheroides (Phylum Ciliophora), Endosymbiotic Ciliates of Annelids and Anurans
Authors: AFFA'A FÉLIX‐MARIE , HICKEY DONAL A. , STRÜDER‐KYPKE MICHAELA , LYNN DENIS H.
Published: July 2005

ABSTRACT. We have used small subunit rRNA gene sequences to determine the phylogenetic relationships of species in three genera of endosymbiotic ciliates. We have confirmed that the astome Anoplophrya marylandensis is related to ciliates in the Class Oligohy‐menophorea, supporting the view that astomes are derived from hymenostome‐like ancestors. We confirmed that Plagiotoma lumbrici, formerly considered to be a heterotrich, is a stichotrich spirotrich ciliate most closely related to Paraurostyla weissei in this analysis. Thus, the somatic polykinetids of Plagiotoma can be concluded to be cirri. We report the details of our isolation of Nyctotheroides deslierresae and Nyctotheroides parvus and confirm previous reports that these clevelandellids are related to the metopid and caeno‐morphid ciliates, now placed in the Class Armophorea.
Sodium‐dependent Transport of [3H](1d)chiro‐Inositol by Tetrahymena
Authors: KERSTING MICHAEL C. , RYALS PHILLIP E.
Published: July 2005

ABSTRACT. The transport characteristics of (1D)chiro‐inositol by the ciliate Tetrahymena were examined in competition studies employing [3H](1D)chiro‐inositol. (1D)chiro‐inositol transport was competed by unlabeled (1D)chiro‐inositol, myo‐inositol, scyllo‐inositol, and D‐glucose in a concentration‐dependent manner. Conversely, (1D)chiro‐inositol competed for [3H]myo‐ and [3H]scyllo‐inositol transport. Lineweaver‐Burke analysis of the competition data indicated a Km of 10.3 mM and a Bmax of 4.7 nmol/min/mg for (1D)chiro‐inositol. Transport of (1D)chiro‐inositol was inhibited by cytochalasin B, an inhibitor of facilitated glucose transporters, and phlorizin, an inhibitor of sodium‐dependent transporters. Removal of sodium from the radiolabeling buffer also inhibited uptake. The presence of 0.64 mM calcium or magnesium ions exerted negligible effects on transport, although potassium was inhibitory. [3H](1D)chiro‐Inositol was shown to be incorporated into Tetrahymena phosphoinositides.
Multiple Polymorphic Sites at the ITS and ATAN Loci in Cultured Isolates of Perkinsus marinus
Authors: BROWN GWYNNE D. , HUDSON KAREN L. , REECE KIMBERLY S.
Published: July 2005

ABSTRACT. Sequence analysis of genomic DNA from the protozoan parasite Perkinsus marinus at two loci revealed genetic polymorphisms within and among different cultured isolates. Genomic DNA from 12 Perkinsus marinus isolates was amplified at the internal transcribed spacer region and at an anonymous locus previously identified to contain polymorphisms by restriction fragment length polymorphism analysis. Fourteen polymorphic nucleotide positions were identified at the internal transcribed spacer region; eight in internal transcribed spacer I and six in internal transcribed spacer 2. Thirteen polymorphic nucleotide sites were identified within the anonymous locus. In some instances, more than three different sequences were observed at both the internal transcribed spacer region and at the anonymous locus from a single clonal isolate, suggesting the possibility of recombination in cultured cells and/or strand jumping during the polymerase chain reaction. Intra‐isolate sequence variation (3.46% for the anonymous locus and 3.08% for internal transcribed spacer 1) was in several cases as high as inter‐isolate sequence variation, even in one isolate where recombination was not evident. High intra‐ and inter‐isolate variation detected at both loci demonstrates the importance of determining the genetic variation of each locus prior to development of sequence‐based molecular diagnostics.
Evaluation of the Resistance of Euglena gracilis to Ion Beam Radiation
Authors: HAYASHI HIROTAKA , WADA SEIICHI , FUNAYAMA TOMOO , NARUMI ISSAY , KOBAYASHI YASUHIKO , WATANABE HIROSHI , FURUTA MASAKAZU , UEHARA KAKU
Published: July 2005

ABSTRACT. The resistance of Euglena (E.) gracilis to ionizing radiation was investigated using seven kinds of ion beams each with different energy characteristics. The minimum effective dose of the most lethal ion beams was 40 Gy. Given its substantially high resistance to heavy ion beams, E. gracilis possesses great potential in acting as an effective support system to produce food and regenerate oxygen in a space station. The lethal effect of ionizing radiation was dependent on the linear energy transfer value of the heavy ion beams, and reached a maximum at 196 keV/μm. This value was different from those obtained by previous irradiation experiments using mammalian and plant cells, suggesting that the radiation response of E. gracilis is distinct from that of mammalian and plant cells.
In Vitro Determination of Generation Times for Entodinium exiguum, Ophryoscolex purkynjei and Eudiplodinium maggii
Authors: DEHORITY BURK A.
Published: July 2005

ABSTRACT. Most previously reported generation times for rumen ciliate protozoa are longer than would be required to prevent their being flushed out of the rumen. In an earlier study from this lab, using a sequential transfer procedure, generation times between 12 and 13 h were determined for both Epidinium caudatum and Entodinium caudatum. This would permit these species to be maintained in a rumen with a fluid volume turnover rate as rapid as twice a day. In this study, generation times were estimated for Entodinium exiguum (13.2 h), Eudiplodinium maggii (26.8 h), and Ophryoscolex purkynjei (29 h), by sequential transfer at both 12 and 24 h time periods. The generation time for E. exiguum is lower than reported for this and other Entodinium species as determined by logarithmic growth from a small inoculum, but similar to that obtained for Ent. caudatum using sequential transfer. Eudiplodinium maggii and O. purkynjei generation times are similar to previous estimates of 24‐ and 24–48 h, respectively. However, it was observed that after an adaptation period of 36 to 48 h (generally 3–4 transfers) cell concentrations decreased and generation times were markedly decreased, i.e. 12.2 h for Ent. exiguum, 15.0 h for E. maggii and 12.8 h for O. purkynjei. In a separate study, varying both the concentration of Epidinium and the quantity of substrate fed per cell had no effect on generation time.
Differences between Brachiola (Nosema) algerae Isolates of Human and Insect Origin when Tested Using an In Vitro Spore Germination Assay anda Cultured Cell Infection Assay
Authors: KUCEROVA ZUZANA , MOURA HERCULES , VISVESVARA GOVINDA S. , LEITCH GORDON J.
Published: July 2005

ABSTRACT. Brachiola (Nosema) algerae is a microsporidian species generally believed to be an intracellular parasite of insects, especially mosquitoes. However, both mosquito and human isolates have been shown to infect mammalian cells. The present study was undertaken to determine if spores of two insect and two human isolates of B. algerae cultured at 30 °C and 37 °C differed in their ability to germinate and infect cultured green monkey kidney cells at these two temperatures. Spores from all four isolates exhibited an optimum pH of 9.5 for germination. Mercury (Hg2+) inhibited germination of all isolates equally. Germination of spores from all four isolates was significantly greater when the parasite was cultured at 30 °C than when cultured at 37 °C. However, spores from the insect isolates cultivated at 30 °C or 37 °C infected significantly fewer mammalian cells at 37 °C than did spores from the human isolates under the same conditions. Thus, there is no correlation between the effects of temperature on the germination and the infectivity of an isolate. In addition, while exposure of B. algerae to 37 °C has been reported to cause spore dysmorphism, we failed to observe any consistent ultrastructural changes that explained the greater infectivity of the human isolates at 37 °C.
Fourteen Morphotypes of Entodinium ovumrajae (Ophryoscolecidae, Entodiniomorphida) Found in the Dromedary Camel of Egypt
Authors: IMAI SOICHI , SHINNO TAKANOBU , IKE KAZUNORI , MORITA TATSUSHI , SELIM HATEM MOHAMED
Published: July 2005

ABSTRACT During a survey of the ciliate protozoal composition of the stomach contents of nine dromedary camels of Egypt, fourteen morphotypes of Entodinium ovumrajae, which has been considered as a species peculiar to camels, were found in six camels. Except for five morphotypes including one originally described as an independent species and its forms, these were newly detected. These morphotypes, divided into three groups, can be identified mainly by the morphology of their ectoplasmic processes. Each camel had on average, about five morphotypes of this species.
Analyses of the Ribosomal DNA Region in Nosema bombycis NIS 001
Authors: IIYAMA KAZUHIRO , CHIEDA YUUKA , YASUNAGA‐AOKI CHISA , HAYASAKA SHOJI , SHIMIZU SUSUMU
Published: July 2005

ABSTRACT Ribosomal DNA (rDNA) containing small subunit (SSU) rDNA and both flanking regions in the entomopathogenic microsporidian Nosema bombycis NIS 001 was amplified from genomic DNA with a primer set based on the sequence of an inverse polymerase chain reaction (PCR) ‐derived fragment. In this fragment, SSU rDNA was divided by a 618‐bp insert at nt 599, and 5S rDNA was located downstream of the SSU rDNA, fragmented by 284‐bp intergenic spacer. In addition, the 48‐bp 3′‐end of large subunit (LSU) rDNA was located 118 bp upstream of the fragmented SSU rDNA. In the amplicon, the region upstream of the LSU rDNA was a homologue of the C‐terminal CHARLIES transposon‐like element of human GTF2IRD2. In this organism, another fragmented SSU rDNA, which was divided by a 231‐bp insert at nt 50, was also detected. Both the intact (insertless) and fragmented SSU rDNAs clustered with LSU rDNA and 5S rDNA and the intergenic sequences between SSU rDNA and 5S rDNA were divergent in an organism. Reverse transcription (RT)‐PCR assay indicated that not only the intact SSU rDNA but also the fragmened SSU rDNA were transcribed in N. bombycis.
Body, Nuclear, and Ciliary Changes during Conjugation of Protospathidium serpens (Ciliophora, Haptoria)
Authors: XU KUIDONG , FOISSNER WILHELM
Published: July 2005

ABSTRACT We studied cell size and shape, nuclear changes, and the ciliary pattern during conjugation of Protospathidium serpens, using protargol impregnation and morphometry. Preliminary data were gathered from Epispathidium ascendens and Apertospathula armata. Conjugation of P. serpens is temporary, isogamic, and without preconjugation divisions. Pair formation is heteropolar, and the partners unite obliquely with the oral bulge. The body becomes smaller and broader during conjugation, but no basic changes occur in the ciliary pattern. Conjugation and nuclear reconstruction follow the usual mode of ciliates. However, some peculiarities occur: only two of the four synkaryon derivatives of the second synkaryon division enter the third division and generate four macronuclear anlagen. which fuse to a single, long macronucleus strand. During conjugation, E. ascendens unites obliquely as P. serpens, while A. armata can pair dorsal‐to‐dorsal surface, ventral‐to‐dorsal surface, or obliquely as P. serpens. The nuclear processes of these three species are also rather different, showing a considerable diversity in union modes and nuclear events of spathidiids; E. ascendens even has preconjugation division. Confirming previous data, the present study shows convincingly that most of the spathidiid nuclear variability is caused by reconstruction processes occurring in post‐dividers, exconjugants and, possibly, exautogamonts. When these specimens are removed from the populations, spathidiid species are as stable (or variable) as other ciliate species.
Establishment of a New Amphileptid Genus, Apoamphileptus nov. gen. (Ciliophora, Litostomatea, Pleurostomatida), with Description of a New Marine Species, Apoamphileptus robertsi nov. spec, from Qingdao, China
Authors: LIN XIAOFENG , SONG WEIBO
Published: July 2005

ABSTRACT A new pleurostomatid genus Apoamphileptus is described, which is diagnosed as: Belonging to the Amphileptidae with spica on right side; on each side of the cell, a single perioral kinety, which encircles the cytostome and does not extend to the posterior end of the cell; somatic kinetics of both sides near ventral margin shortened and forming a postoral suture; two to several extra fragments with densely arranged dikinetids located in anterior portion of left side. As the type species, the morphology and infraciliature of Apoamphileptus robertsi nov. spec., isolated from a shrimp‐farming pond near Qingdao (Tsingtao), China, have been investigated using living observations and the protargol silver impregnation method. The diagnosis for this new species is: Apoamphileptus 90–180 × 30–60 μm in vivo, body elongate pyriform‐shaped and slightly flattened; with one cross‐striated band along the cytostome; 2–6 (generally 4) large macronuclear nodules, one micronucleus; 33–43 right somatic kineties; left side 6–8 kinetics; two extra anterior fragments on left side; about 13 contractile vacuoles dispersed throughout whole body; extrusomes absent or not recognizable; marine habitat. Some morphologically related morphotypes are discussed and tabulated. Regarding the pattern of infraciliature and other morphological features, the well‐described fresh‐water species, Amphileptus claparediiStein, 1867 is believed to be a member of this new genus, hence a new combination is suggested: Apoamphileptus claparedii (Stein, 1867) nov. comb.
Unexpected Effects of Prey Dimensions and Morphologies on the Size Selective Feeding by Two Bacterivorous Flagellates (Ochromonas sp. and Spumella sp.)
Authors: PFANDL KARIN , POSCH THOMAS , BOENIGK JENS
Published: July 2005

ABSTRACT Current models on protistan size‐selective feeding assume that contact probability is the factor that largely explains observed food preferences. Contact probability is generally expected to be positively correlated with prey size and therefore to explain observed food selection for larger prey items. We critically tested these basic assumptions on size‐selective feeding using the interception‐feeding chrysomonad nanoflagellates Ochromonas sp. and Spumella sp. Mechanisms of differential feeding were studied during distinct stages of the selection process (i. e. contact probability, capture efficiency, ingestion efficiency, and differential digestion) by means of high‐resolution video microscopy. Food selection was investigated using a mixture of microspheres ranging from 0. 3–2. 2 μm in diam., as well as a mixed bacterial community. In contrast to current model assumptions, the contact probability was highest for microspheres of intermediate size (0. 9–1. 2 μm), but was not generally positively correlated with prey size over the whole prey size range. Capture and ingestion also proved to be involved in size selection: these patterns were also independent of the food concentration (p= 0.968 for Ochromonas, p= 0.971 for Spumella). Even though the capture rate was significantly higher for attached flagellates than for swimming flagellates (p < 0. 001), size selectivity was not affected (p > 0. 05). Our results indicate that: (i) size selection is not actively regulated by these flagellates, but is a passive process; (ii) contact probability is not generally positively correlated with prey size, but shows a maximum for intermediate‐sized prey in the prey size spectrum of 0. 3–2. 2 μm; and (iii) selection steps other than contact probability are crucial for size selection and should be integrated in models on size selection.
Sterol Composition of Pneumocystis jirovecii with Blocked 14α‐Demethylase Activity
Authors: GINER JOSÉ‐LUIS , ZHAO HUI , AMIT ZUNIKA , KANESHIRO EDNA S.
Published: July 2005

ABSTRACT Several drugs that interact with membrane sterols or inhibit their syntheses are effective in clearing a number of fungal infections. The AIDS‐associated lung infection caused by Pneumocystis jirovecii is not cleared by many of these therapies. Pneumocystis normally synthesizes distinct C28 and C29 24‐alkylsterols, but ergosterol, the major fungal sterol, is not among them. Two distinct sterol compositional phenotypes were previously observed in P. jirovecii. One was characterized by Δ7 C28 and C29 24‐alkylsterols with only low proportions of higher molecular mass components. In contrast, the other type was dominated by high C31 and C32 24‐alkylsterols, especially pneumocysterol. In the present study, 28 molecular species were elucidated by nuclear magnetic resonance analysis of a human lung specimen containing P. jirovecii representing the latter sterol profile phenotype. Fifteen of the 28 had the methyl group at C‐14 of the sterol nucleus and these represented 96% of the total sterol mass in the specimen (excluding cholesterol). These results strongly suggest that sterol 14α‐demethylase was blocked in these organisms. Twenty‐four of the 28 were 24‐alkylsterols, indicating that methylation of the C‐24 position of the sterol side chain by S‐adenosyl‐L‐methionine:sterol C‐24 methyl transferase was fully functional.
Exuviotrophic Apostome Ciliates from Crustaceans of St. Andrew Bay, Florida, and a Description of Gymnodinioides kozloffi n. sp.
Authors: LANDERS STEPHEN C.
Published: July 2005

ABSTRACT Gymnodinioides kozloffi n. sp. is described from the eelgrass broken‐back shrimp Hippolyte zostericola. The species is distinct from others in the apostome genus Gymnodinioides in that the trophont ciliature has a small group of kinetosomes located to the right of Kinety 9a, and Kinety 1 and 2 are divided. Other apostome morphologies are described from many decapod crustaceans from St. Andrew Bay, Florida, including Gymnodinioides inkystans, Hyalophysa chattoni, and variants of both H, chattoni and C. kozloffi. All of these apostome ciliates are exuviotrophic, found feeding on exuvial fluid within the exoskeleton of the host after ecdysis. The hosts surveyed for this study are the following: Callinectes sapidus, Eurypanopeus depressus, Hippolyte zostericola. Farfantepen‐aeus spp., Pataemonetes intermedius, Palaemonfloridanus, Portunus spp., Tozeuma carolinense, and Sicyonia laevigata, which revealed a number of new host‐apostome records
HSP90, Tubulin and Actin are Retained in the Tertiary Endosymbiont Genome of Kryptoperidinium foliaceum
Authors: McEWAN MICHELLE L. , KEELING PATRICK J.
Published: July 2005

ABSTRACT The dinoflagellate Kryptoperidinium foliaceum has replaced its ancestral peridinin‐containing plastid with a tucoxanthin‐containing diatom plastid via tertiary endosymbiosis. The diatom endosymbiont of K. foliaceum is much less reduced than well‐studied endosymbiotic intermediates, such as cryptophytes and chlorarachniophytes, where relict nuclear genomes are retained in secondary endosymbionts. The K. foliaceum endosymbiont retains a prominent nucleus, multiple four‐membrane plastids, and mitochondria, all within a relatively large volume of cytoplasm that is separated from the host cytoplasm by a single membrane. Here we report the first protein‐coding gene sequences from the K. foliaceum endosymbiont and host nuclear genomes. We have characterised genes for nucleus‐encoded cytosolic proteins, actin (from endosymbiont), alpha‐tubulin (from both), beta‐tubulin (from host), and HSP90 (from both), in addition to homologues from pennate diatoms Nitzschia thermalis and Phaeodactylum tricornutum. Phylogenetic reconstruction shows that the actin is diatom‐derived, the beta‐tubulin dinoflagellate‐derived, while both diatom‐ and dinoflagellate‐derived alpha‐tubulin and HSP90 genes were found. The base composition biases of these genes co‐varied with their phylogenetic position, suggesting that the genes still reside in their respective genomes. The presence of these genes implies they are still functional and more generally indicates that the endosymbiont is less genetically reduced than those of cryptophytes or chlorarachniophytes, raising the interesting question of whether any genes have transferred between the two nuclear genomes.
Phylogenetic Comparison of the Myxosporea Based on an Actin cDNA Isolated from Myxobolus cerebralis
Authors: KELLEY GARRY O. , BEAUCHAMP KATHERINE A. , HEDRICK RONALD P.
Published: July 2005

ABSTRACT The full‐length actin gene from Myxobolus cerebralis (Mcer Act‐1), the first characterized from representatives in the phylum Myxozoa, encodes a 378‐amino acid polypeptide with an estimated molecular weight of 41,580‐Da. A phylogenetic comparison found M. cerebralis to branch outside the metazoans. This finding contrasts with previous reports that suggest an evolutionary affinity of the Myxozoa with either the Bilateria or Cnidaria.
Identification of Single Nucleotide Mutations That Prevent Developmentally Programmed DNA Elimination in Paramecium tetraurelia
Authors: MATSUDA ATSUSHI , MAYER KIMBERLY M. , FORNEY JAMES D.
Published: July 2005

ABSTRACT The excision of internal eliminated sequences (IESs) occurs during the differentiation of a new somatic macronuclear genome in ciliated protozoa. In Paramecium tetraurelia, IESs show tew conserved features with the exception of an invariant 5′‐TA‐3′ dinucleotide that is part of an 8‐bp inverted terminal repeat consensus sequence with similarity to the ends of mariner/Tc1 transposons. We have isolated and analyzed two mutant cell lines that are defective in excision of individual IESs in the A‐51 surface antigen gene. Each cell line contains a mutation in the flanking 5′‐TA‐3′ dinucleotide of IES6435 and IES1835 creating a 5′‐CA‐3′ flanking sequence that prevents excision. The results demonstrate that the first position of the 5′‐TA‐3′ is required IES excision just as previous mutants have shown that the second position (the A residue) is required. Combining these results with other Paramecium IES mutants suggests that there are few positions essential for IES excision in Paramecium. Analysis of many IESs reveals that there is a strong bias against particular nucleotides at some positions near the IES termini. Some of these strongly biased positions correspond to known IES mutations, others correlate with unusual features of excision.
Urotricha psenneri n. sp. and Amphileptus piger (Vuxanovici, 1962) n. comb., Two Planktonic Ciliates (Protozoa, Ciliophora) from an Oligotrophic Lake in Austria
Authors: SONNTAG BETTINA , FOISSNER WILHELM
Published: July 2005

ABSTRACT Two euplanktonic ciliates, Urotricha psenneri n. sp. (Prostomatida) and Amphileptus piger (Vuxanovici, 1962) n. comb. (Pleurostomatida), were discovered in the surface plankton of the oligotrophic Lake Traunsee in Austria. Their morphology and infra‐ciliature were studied in live cells as well as in specimens impregnated with protargol and silver nitrate. Urotricha psenneri is a small urotrichid, less than 50 μm length and with a single caudal cilium. It is unique in having (i) a massive oral basket projecting as a conspicuous bulge with cylindrical microfibrillar annulus and (ii) a curved brosse row 1 in the broad, barren circumoral area. Amphileptus piger (Vuxanovici, 1962) is about 55 × 13 μm in vivo, has two macronuclear nodules with a single micronucleus in between in the posterior body half, has a single contractile vacuole with a terminal excretory pore, and few, but thick and thus highly conspicuous extrusomes. The amphileptid ciliary pattern (spica) is difficult to recognise due to the widely spaced basal bodies.
An Analysis of the Microsporidian Genus Brachiola, with Comparisons of Human and Insect Isolates of Brachiola algerae
Authors: CALI ANN , WEISS LOUIS M. , TAKVORIAN PETER M.
Published: July 2005

ABSTRACT The genus Brachiola is the newest microsporidian genus established for a human infection with the type species being B. vesicularum in skeletal muscle. Subsequently, the microsporidium, Nosema algerae, identified from mosquitoes, was added to this genus because of morphological and physiological similarities. The present report illustrates a confirmed case of Brachiola algerae infecting skeletal muscle in a 56‐year‐old woman who was being treated for rheumatoid arthritis with immunosuppressive drugs. In the following study, these two human‐infecting microsporidian species are ultrastructurally compared from human biopsy tissue. Additionally, Brachiola algerae from mosquitoes as reference B. algerae, was grown in athymic mice and compared to the human isolate in vivo, and in culture. B. algerae is morphologically identical in the host situations presented and different from B. vesicularum in human skeletal muscle. B. algerae has a consistently, slightly longer spore that typically contains one row of polar filament coils, while B. vesicularum typically contains two rows of polar filament coils and occasionally, one or three rows. In proliferative development, B. vesicularum forms protoplasmic extensions which do not occur on B. algerae, nor have they been reported on any other microsporidium. This report demonstrates that B. vesicularum and B. algerae are two different species of Brachiola that infect human skeletal muscle.
The Pelican Thrust Zone: basal detachment between the Archean Sask Craton and Paleoproterozoic Flin Flon  Glennie Complex, western Trans-Hudson Orogen
Authors: Ashton K E , Lewry J F , Heaman L M , Hartlaub R P , Stauffer M R , Tran H T
Published: July 2005

The Pelican Thrust Zone is a 37 km-wide recrystallized mylonite zone, along which Paleoproterozoic arc volcano-plutonic and derived sedimentary rocks of the Flin Flon  Glennie Complex were thrust over an Archean package (Jan Lake Complex) consisting of ca. 3.1 Ga calc-alkaline orthogneisses, pelitic migmatites, and a ca. 2.45 Ga tholeiitic charnockitenorite intrusive suite. A regional northeast-plunging stretching lineation and a variety of kinematic indicators imply southwesterly transport, matching that of other coeval shallower crustal-level structures observed throughout the northern Flin Flon Domain and southern flank of the Kisseynew Domain (e.g., SturgeonWeir and Annabel Lake shear zones). Subsequent east-side-up displacement on the Tabbernor Fault, together with domal fold interference, has exposed the Pelican Window and mantling mylonite zone, where it has been seismically profiled along Lithoprobe transects. Tectonic windows also expose Archean rocks in the Glennie Domain to the west, where similar southwest-verging, recrystallized mylonite zones have been documented. Together, these zones record collision and underplating of the Flin Flon  Glennie Complex by the Archean Sask Craton during prolonged protocontinentcontinent collision over a minimum 18261805 Ma interval.
Tectonic implications of new SHRIMP and TIMS UPb geochronology of rocks from the Sask Craton, Peter Lake Domain, and Hearne margin, Trans-Hudson Orogen, Saskatchewan
Authors: Rayner N M , Stern R A , Bickford M E
Published: July 2005

This study reports new sensitive high-resolution ion microprobe (SHRIMP) and thermal ionization mass spectrometry (TIMS) UPb geochronological data for thirteen rocks from the Archean to Paleoproterozic Sask Craton, the Peter Lake Domain and Hearne margin, Saskatchewan. Seven samples from the exposed Sask Craton in both the Glennie Domain and Pelican Window record zircon growth between 2425 and 2525 Ma and at ~1800 Ma. Older precursor material has been identified, most notably a refined crystallization age of 3117 Ma for a sample of quartzofeldspatic gneiss ("Q-gneiss") in the Pelican Window, which also experienced ca. 2450 Ma zircon growth. Three samples from the Peter Lake Domain and a sample from the Linn Island inlier of the Wollaston Domain yield ages of ~2575 Ma. One sample from the Peter Lake Domain is distinctly older, yielding an age of 2640 Ma, but also displays zircon growth at 2575 Ma. The simplest interpretation of these data is that the Peter Lake Domain is likely a part of the Hearne margin, although the significance and distribution of 2575 Ma ages within the larger Hearne craton is unclear. Conversely, the age range of most samples from the Sask Craton is distinctly younger than those of the Peter Lake and Hearne margin rocks. We suggest that 2.45 Ga was a major episode of magmatic reworking of older material within the Sask Craton, which includes, but is not restricted to, 3.1 Ga precursors. These ages do not coincide with typical ages reported from the Superior craton and thus the data, although limited, support an exotic origin for the Sask Craton.
Origin of the Archean Sask craton and its extent within the Trans-Hudson orogen: evidence from Pb and Nd isotopic compositions of basement rocks and post-orogenic intrusions
Authors: Bickford M E , Mock T D , Steinhart III W E , Collerson K D , Lewry J F
Published: July 2005

UPb zircon ages from the exposed Sask craton are 24503100 Ma, from the Peter Lake Domain 25752640 Ma, and from rocks of the Trans-Hudson orogen 18401880 Ma. UPb monazite and zircon ages of post-orogenic pegmatites and aplites are 17701800 Ma. Common Pb and SmNd isotopic compositions of post-orogenic intrusions, as probes of crust beneath the orogen, were compared to Sask craton rocks and ca. 1850 Ma orogenic rocks to infer the origin and subsurface distribution of the Sask craton within the internides of the Trans-Hudson orogen. Results show that post-orogenic intrusions within most of the Glennie Domain and Hanson Lake block were derived, at least in part, from Archean source materials, demonstrating that the Sask craton lies beneath Paleoproterozoic orogenic rocks present at the surface. In contrast, common Pb and SmNd isotopic compositions from pegmatites and aplites of the La Ronge Domain are essentially identical with those of the Paleoproterozoic orogenic rocks into which they are intruded, indicating derivation by partial melting of similar rocks. Thus, if the Sask craton extended to the west beneath the La Ronge Domain, it was beneath the zone of melting that produced the post-orogenic intrusions, making it unlikely that the Sask craton is a detached part of the Hearne craton. Many samples from the Sask craton have elevated 208Pb/204Pb ratios, unlike Superior craton or Hearne craton rocks, suggesting that the Sask craton was derived from an exotic source, such as the Wyoming craton, which shares similar elevated 208Pb/204Pb ratios.
High-temperature, low-pressure metamorphism in the Kisseynew domain, Trans-Hudson orogen: crustal anatexis due to tectonic thickening?
Authors: White Donald J
Published: July 2005

The Kisseynew domain within the central Trans-Hudson orogen constitutes a high-temperature (T) and low- to mediumpressure (P) metasedimentary belt characterized by uniform peak metamorphic conditions of 750 ± 50 °C and 56 kbar (1 kbar = 100 MPa). To investigate the thermal evolution of the Kisseynew domain 1-dimensional thermal modelling was conducted for a range of thermal parameters, including the effects of exhumation and incorporating current information about the crustal architecture. The results show that tectonic thickening of the sedimentary pile to ~40 km, consistent with present-day thickness estimates and erosional levels, is capable of producing enough crustal heating to melt the base of the sedimentary pile, advect heat to shallower crustal levels, and produce the observed PT conditions. Deep-seated mantle heat sources, though not excluded, are not required.
Heat flow, thermal regime, and elastic thickness of the lithosphere in the Trans-Hudson Orogen
Authors: Mareschal J C , Jaupart C , Rolandone F , Gariépy C , Fowler C MR , Bienfait G , Carbonne C , Lapointe R
Published: July 2005

Heat flow studies on the exposed part of the Trans-Hudson Orogen (THO) in northern Manitoba and Saskatchewan allow constraints on crustal composition and lithosphere structure. The average of all heat flow values in the THO is the same as in other geological provinces of the Canadian Shield. However, where juvenile crust is exposed, heat flow is on average lower than in the Superior and Grenville provinces (37 vs. 41 mW m2). Heat flow increases towards the surrounding Archean provinces, RaeHearne to the west, Sask to the south, and Superior to the east. There are strong differences in heat flow within and between the belts of the THO. The poor correlation between heat flow and heat production in the rocks exposed at the surface implies that these differences involve a large fraction of the crustal column. One new heat flow determination confirms the existence of a ``cold spot'' around the town of Lynn Lake in the northern part of the THO. Heat flow data in the Kisseynew and Glennie domains remain sparse, but they indicate that this low heat flow region extends as far south as the Flin Flon  Snow Lake Belt. The Lynn Lake Belt is underlain by poorly radiogenic rocks, possibly Kisseynew-type crust with oceanic basement. Northward increase in heat flow along the Thompson Belt is consistent with the view that the belt is thrust over Kisseynew-type basement only in the south. Heat flow increases southward in the Paleozoic basin because of higher heat production in basement rocks, probably from the Sask craton. We used the low heat flow regions to obtain an upper bound of 15 mW m2 for the mantle heat flow in the THO. The effective elastic thickness of the lithosphere can be determined from the coherence between the topography and the Bouguer gravity. The effective elastic thickness is high (>40 km) thoughout the Canadian Shield and is highest in the central part of the shield, in particular in the Lynn Lake region. There seems to be a negative correlation between elastic thickness and heat flow in the central and western Canadian Shield. This indicates that, even in stable continents, the elastic thickness is largely controlled by the lithospheric temperatures that depend strongly on crustal heat generation and hence crustal structure.
Accretion history of the Trans-Hudson Orogen in Manitoba and Saskatchewan from paleomagnetism
Authors: Symons David TA , Harris Michael J
Published: July 2005

Lithoprobe's sponsorship has led to the acquisition of paleomagnetic data from ~20 units throughout the Paleoproterozoic Trans-Hudson Orogen (THO) of Saskatchewan and Manitoba, essentially the first such data for the region. Discussed summarily in this paper, they provide an initial framework for the THO's tectonic evolution. They show that the Archean Hearne and Superior cratons were at subtropical and subpolar paleolatitudes, respectively, at ~1875 Ma, with the Lynn Lake  LaRonge arc midway between them in the Manikewan Ocean. By ~1855 Ma, this ocean was still ~5500 ± 700 km wide, and its seafloor was subducting northwestward under the Hearne craton and pericratonic Peter Lake domain margin with the coeval development of an Andean-type continental magmatic arc, the WathamanChipewyan batholith. Between ~1855 and ~1810 Ma, coalescing apparent polar wander path (APWP) segments record closing of the ocean at a rate of ~12 cm/a, trapping and accreting the several separate intervening terranes (Flin Flon, Hanson Lake, Lynn Lake  LaRonge, Rottenstone, and presumably also other THO terranes). From ~1815 to ~1775 Ma, the assembled terranes drifted as a coherent craton, yielding a stillstand and hairpin in the APWP.
Flin Flon Belt seismic anisotropy: elastic symmetry, heterogeneity, and shear-wave splitting
Authors: Cholach Pavlo Y , Molyneux Joseph B , Schmitt Douglas R
Published: July 2005

Laboratory measurements of compressional- and shear-wave velocities, and shear-wave splitting have been carried out on a set of upper greenschist  lower amphibolite facies of metasediments and metavolcanics and plutonic rocks from two ductile shear zones in the Flin Flon Belt (FFB) of the Trans-Hudson Orogen (THO). Selected metamorphic rocks vary in composition from felsic to mafic. Test sites with outcrops of sheared metamorphic rocks were correlated with a series of inclined seismic reflectors possibly extending from the midcrust and intersecting a well-mapped shear zone at the surface. Determination of the lithological and physical properties of highly deformed metamorphic rocks is essential for proper interpretation of the nature of observed seismic reflectors. To investigate the anisotropic properties of the rocks, compressional velocity was measured at confining pressure up to 300 MPa in three mutually orthogonal directions aligned with respect to visible textural features. In addition, on selected samples, shear-wave velocity was measured at two orthogonal polarizations for each of three propagation directions to determine shear-wave splitting. The seismic heterogeneity of hand specimens was also investigated by measuring P- and S-wave velocities on several cores cut in the same direction. Observed compressional-wave anisotropy varied from quasi-isotropic to 24%. Maximum observed shear-wave splitting reaches a value of 0.77 km/s at confining pressure of 300 MPa. The pressure invariance of observed P-wave anisotropy and shear-wave splitting indicates that intrinsic anisotropy due to the lattice-preferred orientation (LPO) of highly anisotropic minerals, such as mica and hornblende, is mainly responsible for the measured seismic anisotropy.
Geophysical transect across a Paleoproterozoic continentcontinent collision zone: The Trans-Hudson Orogen
Authors: White D J , Thomas M D , Jones A G , Hope J , Németh B , Hajnal Z
Published: July 2005

A summary and comparison of geophysical data and models for the Trans-Hudson Orogen in northern Manitoba and Saskatchewan are presented. Magnetic total field and Bouguer gravity maps are used to define the along-strike extension of geological domains of the orogen exposed on the Canadian Shield, and a two-dimensional density model is produced, which accounts for the observed variations of the Bouguer gravity field across the orogen. An 800-km-long crustal section across the entire continentcontinent collision zone, including the edges of the bounding cratonic blocks, is presented. It incorporates seismic reflectivity, seismic velocities, resistivity, and density models. Key results include (1) evidence for west-vergent crustal stacking and exhumation in the eastern Trans-Hudson Orogen in the form of preserved Moho topography and the presence of higher grade (higher velocity) rocks in the hanging wall of an east-dipping crustal stack; (2) definition of the eastward extent of the Archean Sask craton in the subsurface based on distinct lower crustal properties; and (3) 400 m of present-day surface topography and 68 km of relief on the Moho are isostatically compensated mainly within the upper mantle by a westward increase in upper mantle temperatures by 40155 °C and (or) 16107 km of thinning of the mantle lithosphere.
Correlation Chart of the evolution of the Trans-Hudson Orogen  ManitobaSaskatchewan segment
Authors: Ansdell Kevin M , Heaman Larry M , Machado Nuno , Stern Richard A , Corrigan David , Bickford Pat , Annesley Irving R , Böhm Christian O , Zwanzig Herman V , Bailes Al H , Syme Ric , Corkery Tim , Ashton Ken E , Maxeiner Ralf O , Yeo Gary M , Delaney Gary D
Published: July 2005

A correlation chart showing the evolution of the ManitobaSaskatchewan segment of the Paleoproterozoic Trans-Hudson Orogen (THO) has been constructed based on available geochronological and isotopic data. Geological, petrological, geochemical, and structural data have also been incorporated into the correlation chart to provide finer detail and to allow comparison of specific tectonic events. The chart also emphasizes that the bounding Archean cratons (Superior, Hearne, Sask) have been significantly affected by Paleoproterozoic events, and it is hoped that this chart will also facilitate comparison with other Paleoproterozoic orogens in North America and beyond.
A database of physical properties of rocks from the Trans-Hudson Orogen, Canada
Authors: Fowler C MR , Stead D , Pandit B I , Janser B W , Nisbet E G , Nover G
Published: July 2005

A physical properties database of rock types from the Trans-Hudson Orogen provides information for interpretation of geophysical surveys over the Trans-Hudson Orogen. Measurements have been made on 320 samples (all reduced to core) representing metamorphosed Archaean and juvenile Proterozoic orogenic rocks. Water saturated densities were generally between 2600 and 3100 kg m3. In most cases, the porosity was < 1%. Except for a few samples, magnetic susceptibility ranged from 20 to 4000 × 106 SI units. P- and S-wave velocities were made under maximum uniaxial stress and triaxial stresses equivalent to depths of ca. 4 km. P- and S-wave velocities measured were 57 km s1 and 34 km s1, respectively. Electrical resistivity measurements were made at room temperature from 5 Hz to 10 kHz after samples were oven dried and after saturation in solutions with salinity between 0.0 and 1.0 mol/L. Increasing salinity caused a reduction in resistivity. The porosityresistivity data is in reasonable overall agreement with Archie's Law for all rock types. A minimum value of 50 Ω m was obtained from samples not containing significant sulphide minerals or graphite. For sulphide and graphite-bearing samples, resistivity was as low as 1 Ω m. The resistivity data are consistent with the hypothesis that North American Central Plains (NACP) conductivity anomaly could be due to the presence of graphite- and (or) sulphide-rich bodies or saline pore fluids in the crust. Thermal conductivity measurements made using a "divided-bar" apparatus yielded values between 1 and 5 W m1 K1.
Electromagnetic image of the Trans-Hudson orogen  THO94 transect
Authors: Garcia Xavier , Jones Alan G
Published: July 2005

The North American Central Plains (NACP) anomaly in enhanced electric conductivity and its relationship with the Paleoproterozoic Trans-Hudson orogen (THO) has been studied under the auspices of Lithoprobe for over a decade. The NACP anomaly was the first geophysical evidence of the existence of the THO beneath the Phanerozoic sediments of the Central Plains. This anomaly, detected geomagnetically in the late 1960s, has been the subject of a number magnetotelluric studies from the early 1980s. The PanCanadian and Geological Survey of Canada experiments in the 1980s and the Lithoprobe experiments in the 1990s together comprise four eastwest and one northsouth regional-scale profiles in Saskatchewan perpendicular to the strike of the orogen. In this paper, data from the northernmost line, coincident with seismic line S2B, are analysed and interpreted, and are shown to be key in determining the northern extension of the NACP anomaly. Dimensionality analysis confirms the rotation of deep crustal structures eastward to Hudson Bay, as earlier proposed on the basis of broad-scale geomagnetic studies. On this profile, as with the profile at the edge of the Paleozoic sediments, the NACP anomaly is imaged as lying within the La Ronge domain, in contact with the Rottenstone domain, and structurally above the Guncoat thrust, a late compressional feature. The location of the anomaly together with the surface geology suggests that the anomaly is caused either by sulphide mineralization concentrated in the hinges of folds, by graphite, or by a combination of both. Our interpretation of the data is consistent with that from other profiles, and suggests that the NACP anomaly was formed as a consequence of subduction and collisional processes involving northward subduction of the internides of the THO beneath the Hearne craton. On the southern part of this profile, a resistive structure is identified as the Sask craton, suggesting that Proterozoic rocks are above Archean rocks in the THO.
Electrical-resistivity imaging of the central Trans-Hudson orogen
Authors: Ferguson Ian J , Stevens Kevin M , Jones Alan G
Published: July 2005

Magnetotelluric (MT) measurements were made on a profile across the Trans-Hudson orogen in 1992 as part of the Lithoprobe transect. The present study includes analysis of results from a 300 km-long section of the profile in which allocthonous Paleoproterozoic juvenile terranes and arc rocks of the western Trans-Hudson orogen have been juxtaposed against the Archean Sask craton. Impedance tensor decomposition of data from the 40 MT sites in the area indicates a geoelectric strike of N28°E. Two-dimensional inversion of the data using a non-linear conjugate gradient algorithm provided images of the resistivity structure. Resistivity images reveal that the crust of the Sask craton is relatively resistive (>2000 Ω·m). In contrast, the rocks of the Flin Flon belt, Glennie domain, and La Ronge domain are mostly relatively conductive (<1001000 Ω·m). In the east of the study area, the images suggest that the Tabbernor fault juxtaposes more conductive rocks of the Glennie domain in the west against more resistive Archean rocks in the east in the upper 20 km of the crust. In the west of the study area, the images confirm that the North American Central Plains conductor occurs within westward-dipping rocks of the La Ronge domain. The resistivity images also reveal that the lower crust beneath the west of the Glennie domain, within a crustal culmination defined by seismic reflection data, is electrically conductive (<100 Ω·m). An explanation for the enhanced conductivity is that part of the lower crust beneath the western Glennie domain is of Proterozoic age. In this case, a possible source for the enhanced conductivity, based on its location at the edge of the Sask continental block, is Proterozoic ocean margin rocks.
Tectonic framework of a Paleoproterozoic arc-continent to continent-continent collisional zone, Trans-Hudson Orogen, from geological and seismic reflection studies
Authors: Corrigan D , Hajnal Z , Németh B , Lucas S B
Published: July 2005

Vertical incidence seismic data were collected along a 300 km-long profile across the northwestern flank of the Trans-Hudson Orogen in Saskatchewan (line S2b). The present study integrates the seismic data with previously published geological maps and recent results from the La Ronge  Lynn Lake Bridge Project that provide new constraints on the lithological, structural, and tectonic framework of this collisional zone. An interpretative section, based on the seismic reflectivity and surface geological constraints, is presented. The integrated data suggest the following key elements. (1) Although an early foreland-vergent accretion history is suggested by surficial geological constraints, the predominant fabric is reflected by penetrative hinterlandward vergence. (2) A zone of more reflective lower crust with hinterland-verging fabric may represent "fossil" reflectors from a pre-collisional accretionary phase. (3) The Archean to Paleoproterozoic Sask Craton may extend in the lower middle crust to at least beneath Rottenstone Domain, consistent with what is observed along strike on other Lithoprobe seismic profiles. (4) The Needle Falls and Parker Lake shear zones do not appear to be associated with obvious reflectors, consistent with observations from Reindeer Lake, suggesting that they merely rework the Wathaman Batholith intrusive margin and are not fundamental sutures. (5) The La Ronge and Rottenstone domains show nearly identical seismic properties, consistent with recent mapping results in the Reindeer Lake area that suggest that they are temporally and, at least in part, lithologically related in the area covered by, and to the east of, seismic line S2b.