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R L Conner

Publications and source records attributed to R L Conner.

At least 19 recordsLinked to original sources
PubMed2003

Molecular cytogenetic discrimination and reaction to wheat streak mosaic virus and the wheat curl mite in Zhong series of wheat--Thinopyrum intermedium partial amphiploids.

Thinopyrum intermedium (2n = 6x = 42, JJJsJsSS) is potentially a useful source of resistance to wheat streak mosaic virus (WSMV) and its vector, the wheat curl mite (WCM). Five partial amphiploids, namely Zhong 1, Zhong 2, Zhong 3, Zhong 4, and Zhong 5, derived from Triticum aestivum x Thinopyrum intermedium crosses produced in China, were screened for WSMV and WCM resistance. Zhong 1 and Zhong 2 had high levels of resistance to WSMV and WCM. The other three partial amphiploids, Zhong 3, 4, and 5, were resistant to WSMV, but were susceptible to WCM. Genomic in situ hybridization (GISH) using a genomic DNA probe from Pseudoroegneria strigosa (SS, 2n = 14) demonstrated that two partial amphiploids, Zhong 1 and Zhong 2, have almost the identical 10 Th. intermedium chromosomes, including four Js, four J, and two S genome chromosomes. Both of them carry two pairs of J and a pair of Js genome chromosomes and two different translocations that were not observed in the other three Zhong lines. The partial amphiploids Zhong 3, 4, and 5 have another type of basic genomic composition, which is similar to a reconstituted alien genome consisting of four S and four Js genome chromosomes of Th. intermedium (Zhong 5 has two Js chromosomes plus two Js-W translocations) with six translocated chromosomes between S and Js or J genomes. All three lines carry a specific S-S-Js translocated chromosome, which might confer resistance to barley yellow dwarf virus (BYDV-PAV). The present study identified a specific Js2 chromosome present in all five of the Zhong lines, confirming that a Js chromosome carries WSMV resistance. Resistance to WCM may be linked with J or Js chromosomes. The discovery of high levels of resistance to both WSMV and WCM in Zhong 1 and Zhong 2 offers a useful source of resistance to both the virus and its vector for wheat breeding programs.

Agropyron↗
PubMed2000

Characterization of wheat-Thinopyrum partial amphiploids by meiotic analysis and genomic in situ hybridization.

A combination of genomic in situ hybridization (GISH) and meiotic pairing analysis of wheat-Thinopyrum partial amphiploids was employed to identify the genomic constitution and relationships between partial amphiploids derived from wheat and wheatgrass crosses. On the basis of similarities in the meiotic behavior and GISH patterns, the alien chromosomes of two of eight partial amphiploids, TAF46 and 'Otrastayuskaya 38', were judged to originate from Th. intermedium, whereas Th. ponticum was one of the parents of the other six partial amphiploids; PWM706, PWM206, PWM209, PWMIII, OK7211542, and Ag-wheat hybrid. Each of these partial amphiploids was found to contain a synthetic alien genome composed of different combinations of St-, J-, or Js-genome chromosomes. For relatedness of partial amphiploid lines, meiotic analysis of F1 hybrids and GISH results were generally complementary, but the latter offered greater precision in identifying constituent genomes.

Blotting, Southern↗
PubMed1998

Genome analysis of Thinopyrum intermedium and Thinopyrum ponticum using genomic in situ hybridization.

Genomic in situ hybridization (GISH) using genomic DNA probes from Thinopyrum elongatum (Host) D.R. Dewey (genome E, 2n = 14), Thinopyrum bessarabicum (Savul. & Rayss) A. Löve (genome J, 2n = 14), and Pseudoroegneria strigosa (M. Bieb.) A. Löve (genome S, 2n = 14), was used to examine the genomic constitution of Thinopyrum intermedium (Host) Barkworth & D.R. Dewey (2n = 6x = 42) and Thinopyrum ponticum (Podp.) Barkworth & D.R. Dewey (2n = 10x = 70). Evidence from GISH indicated that hexaploid Th, intermedium contained the J, Js, and S genomes, in which the J genome was related to the E genome of Th. elongatum and the J genome of Th. bessarabicum. The S genome was homologous to the S genome of Ps. strigosa, while the Js genome referred to modified J- or E-type chromosomes distinguished by the presence of S genome specific sequences close to the centromere. Decaploid Th. ponticum had only the two basic genomes J and Js. The Js genome present in Th. intermedium and Th. ponticum was homologous with E or J genomes, but was quite distinct at centromeric regions, which can strongly hybridize with the S genome DNA probe. Based on GISH results, the genomic formula of Th. intermedium was redesignated JJsS and that of Th. ponticum was redesignated JJJJsJs. The finding of a close relationship among S, J, and Js genomes provides valuable markers for molecular cytogenetic analyses using S genome DNA probes to monitor the transfer of useful traits from Th. intermedium and Th. ponticum to wheat.

Centromere↗
PubMed1990

Nimodipine alters acquisition of a visual discrimination task in chicks.

Chicks 5 days old received intraperitoneal injections of nimodipine 30 min before training on either a visual discrimination task (0, 0.5, 1.0, or 5.0 mg/kg) or a test of separation-induced distress vocalizations (0, 0.5, or 2.5 mg/kg). Chicks receiving 1.0 mg/kg nimodipine made significantly fewer visual discrimination errors than vehicle controls by trials 41-60, but did not differ from controls 24 h later. Chicks in the 5 mg/kg group made significantly more errors when compared to controls both during acquisition of the task and during retention. Nimodipine did not alter separation-induced distress vocalizations at any of the doses tested, suggesting that nimodipine's effects on learning cannot be attributed to a reduction in separation distress. These data indicate that nimodipine's facilitation of learning in young subjects is dose dependent, but nimodipine failed to enhance retention.

Age Factors↗
PubMed1989

Opiate effects on social behavior of juvenile dogs as a function of social deprivation.

The relationship between opioids and social behavior was examined by administering morphine (an opioid agonist) and naloxone (an opioid antagonist) to juvenile dogs and measuring various social behaviors (e.g., tail wagging) in a large room. Drugs were administered following social deprivation and nondeprivation. It was hypothesized that morphine would ease effects of social deprivation while naloxone would result in behavior typical of untreated socially-deprived dogs. Social deprivation (24 hr) resulted in more contact with the experimenter and increased tail wagging relative to nondeprivation. Morphine (0.25 mg/kg) resulted in more contacts with the experimenter and entrances into the "experimenter's area" relative to vehicle injections. Further, morphine decreased and naloxone increased tail wagging in the dog's area and there was a significant social condition X drug interaction for that measure. Naloxone (0.25 mg/kg) increased wagging following nondeprivation while morphine decreased wagging following deprivation. These data support the hypotheses that social deprivation can increase social behaviors, and that social behavior is regulated by activity in brain opioid systems.

Animals↗
PubMed1989

The presence of acyl-CoA: cholesterol acyltransferase in Tetrahymena pyriformis W.

1. The esterification of cholesterol was studied in Tetrahymena pyriformis an organism which does not synthesize sterols nor are sterols required for growth. 2. Microsomes catalyzed the esterification of cholesterol in the presence of oleoyl-CoA but not oleic acid or lecithin. 3. The enzyme has a similar sterol substrate specificity to that of mammalian acyl-CoA: cholesterol acyltransferase (ACAT) and was inhibited by the specific ACAT inhibitor 58-035. 4. The enzyme is constitutive since activity was observed in cells grown in sterol-free medium when cholesterol was added to the in vitro assay.

Animals↗
PubMed1989

Microinjections of leupeptin in the frontal cortex or dorsal hippocampus block spatial learning in the rat.

Adult male Long-Evans hooded rats were given bilateral microinjections of 18 mM leupeptin or saline through cannulae implanted with tips aimed at the frontal cortex or CA1 or CA3 hippocampal cell fields. Five minutes following injections animals were allowed to complete an eight-arm radial maze. The acquisition criterion required that the animal make 7 correct choices of the first 8, and 8 correct choices of the first 10, for five consecutive sessions. Leupeptin slowed acquisition of the eight-arm radial maze task when injected into the CA1 and CA3 hippocampal fields or the frontal cortex, but did not influence spontaneous activity. These results suggest that earlier reports of the amnestic effect of leupeptin when administered into the lateral cerebral ventricle may have been due to effects within the cortex and hippocampus. The present experiment represents the first attempt to identify behaviorally those brain areas in which leupeptin acts to alter learning.

Animals↗
PubMed1987

Unidirectional co-stimulation by a non-mating strain of Tetrahymena thermophila.

We report that a fatty acid auxotroph of Tetrahymena thermophila (RH179E1) fails to mate, yet retains the ability to co-stimulate normal cells unidirectionally. Thus, co-stimulation can be analyzed experimentally in the absence of pair formation. We show that the co-stimulation of normal cells of one mating type is sufficient to shorten the waiting period for pair formation of those cells with initiated cells. This is the first evidence that co-stimulation causes a hyperinduction of mating reactivity in T. thermophila, generating in turn a positive feedback mechanism for (presumably) gamone production. Co-stimulation by the variant strain is at a maximum after 3-4 h of exposure when the variant and wild-type cells are at a ratio of 1:1. When mixed with wild-type cells, RH179E1 induces the formation of progeny (at low frequency) which inherit exclusively genetic material of the wild-type cells.

Animals↗
PubMed1987

Perinatal leupeptin retards subsequent acquisition of a visual discrimination task in chicks.

Recent discoveries that calcium sensitive proteases (calpains) may play an important role in memory led to investigation of the effects of leupeptin, a calpain inhibitor, on learning. Intracerebral injections of either 0.9% saline, 80 micrograms aprotinin, 306 micrograms glutamate, or 8 or 80 micrograms leupeptin were administered to 95 two-day-old chicks. On Day 10 posthatch, animals were then tested on a task requiring discriminations between pebbles and food pellets. Chicks receiving 8 or 80 micrograms leupeptin or 306 micrograms glutamate were found to be deficient in acquiring the task. Aprotinin, a control serine protease inhibitor, did not retard discrimination learning. None of the drugs tested altered body weight or gross visual skills. These results suggest that retardation produced by leupeptin is not due to nonspecific changes in protease activity, visual competency, or growth. The reported results confirm earlier reports of leupeptin-induced memory impairments in rats.

Animals↗
PubMed1984

Fatty acid desaturase specificity of Tetrahymena.

The ciliate, Tetrahymena, was provided a supplement of the fatty acid [1-14 C]18:2 delta 6.9. After a period of growth the cells were claimed, the lipids extracted, the polar lipids recovered and the mild alkali-labile fatty acid methyl esters generated. The fatty acids were resolved by high pressure liquid chromatography (HPLC), the 18:3 delta 6.9,12(gamma-linolenic acid) was recovered and its identity verified by high pressure liquid chromatography (HPLC), gas liquid chromatography (GLC), hydrogenation and oxidation. Fifty-three percent of the cell-associated label was found in gamma-linolenic acid; thus, a delta 12 fatty acid desaturase converts the 6,9 octadecadienoic acid to the 6,9,12 derivative. No carboxyl or methyl terminus restriction appears on delta 9 monoenoic or dienoic fatty acid desaturation in this cell as is found in higher plants and animals.

Chromatography, High Pressure Liquid↗
PubMed1982

A comparison of the biological properties of androst-5-en-3 beta-ol, a series of (20R)-n-alkylpregn-5-en-3 beta-ols and 21-isopentylcholesterol with those of cholesterol.

The delta 5-sterol, androst-5-en-3 beta-ol, which has no side chain at C-17, did not permit molting of the insect Heliothis zea, growth of either the protozoan Tetrahymena pyriformis, or the yeast Saccharomyces cerevisiae adapted to anaerobic conditions, nor was the sterol esterified by a mammalian microsomal ACAT preparation. However, the sterol did form a liposome with egg lecithin and, when fed to mice, did inhibit hepatic cholesterol synthesis. 21-Isopentylcholesterol also formed a liposome but neither supported the growth of the yeast nor was metabolized by the protozoan. When sterols, 20(R)-n-alkylpregn-5-en-3 beta-ols, with side chains of varying lengths were added to the medium of the protozoan, maximal esterification with fatty acids occurred with the 20(R)-n-pentyl derivative, and maximal inhibition of tetrahymanol formation occurred with the n-butyl, n-pentyl, and n-hexyl derivatives. In all of the assays cholesterol showed a positive response, either permitting molting or growth, being metabolized, inhibiting sterol or tetrahymanol synthesis, or forming a liposome.

Androstenols↗
PubMed1982

The effect of temperature on glyceryl ethers in Tetrahymena pyriformis W.

The effect of temperature on the ether content of the glycerophospholipids of Tetrahymena pyriformis W was examined. The only ether detected was 1-O-hexadecyl glycerol (alpha-chimyl alcohol). The data provide evidence that the class 1-O-alkyl-2-acyl-sn-glycero-3-(2-aminoethyl)-phosphate (1-alkyl PsE), in addition to the previously reported 1-O-alkyl-2-acyl-sn-glycero-3-(2-aminoethyl)-phosphonate (1-alkyl PnE) and 1-O-alkyl-2-acyl-sn-glycero-3-phosphorylcholine (1-alkyl PC), exists in this ciliate species. A comparison was made of the ether content of the glycerophospholipids from cells grown at 15 degrees and 28.5 degrees C. An elevation in the amount of ether was noted in all glycerophospholipids at the lower temperature with the largest proportional change in 1-alkyl PsE. Tetrahymena species have a high gamma-linolenic acid content in the sn-1 position of the glycerophospholipids in addition to the usual saturated acids and ether. The replacement at low temperature of gamma-linolenic acid by a saturated hydrocarbon at the sn-1 position of the glycerophospholipids of Tetrahymena pyriformis W should increase the microviscosity of the membranes; thus, it is difficult to envision this alteration in the glycerophospholipids as an adaptive change beneficial for growth. These findings are in direct contrast to the situation in Tetrahymena thermophila where the percentage of ether glycerophospholipids increases at the expense of gamma-linolenate as the temperature rises.

Animals↗
PubMed1981

Metabolism of odd-numbered, normal fatty acids in Tetrahymena pyriformis W.

Tetrahymena pyriformis W cells were grown with short- and long-chain, odd and even normal fatty acid supplements. Tris acetate addition had no effect on the fatty acyl composition of the glycerophospholipids or sphingolipids, while Tris propionate supplementation led to a marked increase in odd normal fatty acids at the expense of even normal acids in both classes of complex lipids. This enhancement of odd normal acids permitted the identification of 17:1 delta 9(n), 17:2 delta 6,9(n), 17:2 delta 9,12(n), 17:3 delta 6,9,12(n), 19:1 delta 9(n), 19:2 delta 9,12(n) and 19:3 delta 6,9,12(n) by oxidation with periodate-permanganate and examination of the short-chain fragments. Supplementation with pentadecanoic acid (15:0(n)) led to an increase in the proportions of normal C15, C17 and C19 acids. The increase in C15 acids primarily reflected a rise in 15:0(n), whereas the rise in the levels of C17 and C19 acids was accounted for by an elevation of unsaturated acids. Growth with heptadecanoic acid (17:0(n)) resulted in substantial increases in unsaturated normal C17 and C19 fatty acids, while nonadecanoic acid (19:0(n)) addition led only to an increase in the proportion of unsaturated C19 acids. Retroconversion of these saturated, odd normal long chain fatty acid supplements was limited. Supplementation with arachidic acid (20:0(n)) resulted in only a marginal increase (1.4%) in normal C20 fatty acids of both the glycerophospholipids and the mild alkali labile neutral lipids and provided no evidence that desaturation occurred. The release of 14CO2 from [1-14C]arachidic acid when incubated with the ciliates indicated that this long-chain saturate is accumulated, activated and degraded. Normal C16-C19 saturated fatty acids are substrates for the delta 9 desaturase. The delta 11 isomers arise by chain elongation. Normal C16-C19 delta 9 monoenoic acids are substrates for the delta 12 desaturase. Normal C16-C18 delta 9 monoenes, normal C16-C19 delta 9,12 dienes and 18:1 delta 11(n) are desaturated at the C-6,7 position.

Animals↗
PubMed1981

Steric effects at C-20 and C-24 on the metabolism of sterols by Tetrahymena pyriformis.

Cultures of Tetrahymena pyriformis were incubated with various sterols and the extent of dehydrogenation at C-7 and C-22 was determined. The sterols incubated were desmosterol, 22-dehydrodesmosterol, 24-methyldesmosterol, 24 alpha-methylcholesterol (campesterol), 24-methylene-cholesterol, isohalosterol (26,27-bisnorcampesterol, also known as 24,24-dimethylchol-5-en-e beta-ol, a naturally occurring C26-sterol), and 20-isohalosterol. 20-Isohalosterol was not metabolized, while products with delta 7- and delta 22-bonds were formed from isohalosterol and all of the other sterols studied. This confirms an earlier conclusion, based on results with 20-isocholesterol and cholesterol, that inversion of the configuration from 20(R) to 20(S) completely prevents metabolism both in the nucleus and the side chain. On the other hand, changes in the electronics or stereochemistry at C-24 had a direct affect only on metabolism in the side chain. The presence of a methyl group at C-24 reduced the yield of metabolites with a delta 22-bond relative to those with a delta 7-bond producing an accumulation of 7-dehydro metabolite. A double bond at position-24 counteracted this steric effect, presumably by enhancing the rate of dehydrogenation, and a delta 24(28)-bond was more effect than was a delta 24(25)-bond.

Animals↗
PubMed1980

The effects of branching, oxygen, and chain length in the side chain of sterols on their metabolism by Tetrahymena pyriformis.

The ciliated protozoan Tetrahymena pyriformis was incubated with delta 5-sterols which has side chains varying in degree of branching, polarity, and length. Branching at neither end of the side chain was obligatory for metabolism, although removal of C-21 did have a small quantitative effect. Both 21-norcholesterol and sterols lacking a terminal gem-dimethyl group, e.g. 26 (or 27)-norcholesterol, underwent conversion to the corresponding delta 5,7,22-trienols. However, replacement of C-21 with oxygen (20 xi-hydroxy- and 20-keto-21-norcholesterol) was very deleterious. In particular, introduction of a delta 22-bond was abolished, and dehydrogenation in Ring B was strongly reduced. The overall length of the side chain which permitted maximal metabolism corresponded closely to that in cholesterol and other natural sterols. Maximal metabolism was observed only with sterols bearing side chains which had 5 or 6 carbon atoms (other than C-21) attached to C-20. The extent of metabolism fell gradually to zero as the length of the chain was increased or decreased. No metabolism at all occurred with side chains of no carbon atoms (pregn-5-en-3 beta-ol) or as many as 12 carbon atoms (20(R)-n-dodecylpregn-5-en-3 beta-ol) on C-20 other than C-21. Dehydrogenation in the side chain was more sensitive to chain length than was dehydrogenation in Ring B. The data presented here reinforce the view that the enzymes involved in sterol metabolism are actually directed toward binding with sterols. Furthermore, since the sterols become components of the ciliary membrane of this protozoan, the observed structural requirements for metabolism presumably reflect the structural requirements for membrane architecture; and the evidence presented then suggests that the natural length of the sterol side chain is governed by the sterol's membranous function.

Animals↗
PubMed1979

The effect of temperature on unsaturated fatty acid loss in Tetrahymena pyriformis.

Cultures of Tetrahymena pyriformis W incorporate exogenous 3-[14C]-cilienic acid and gamma-[1(-14)C] linolenic acid, terminal products of unsaturated fatty acid synthesis, into glycerophosphatides without randomization of the radiolabel. There was no difference in the rate of loss of each of the two acids at 15 or 28.5 degrees C. Differential turnover of these fatty acids, therefore, does not appear to be the cause of the shift in fatty acid pattern observed with temperature reduction.

Fatty Acids, Unsaturated↗