bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ergodic elements for actions of Lie groups
Authors: Gutschera K. Robert 
Published: September 2008

AbstractGiven a connected Lie group G acting ergodically on a space S with finite invariant measure, one can ask when G will contain single elements (or one-parameter subgroups) that still act ergodically. For a compact simple group or the isometry group of the plane, or any group projecting onto such groups, an ergodic action may have no ergodic elements, but for any other connected Lie group ergodic elements will exist. The proof uses the unitary representation theory of Lie groups and Lie group structure theory.
New limiting notions of the IP type in the enveloping semigroup
Authors: Haddad Kamel N. 
Published: September 2008

AbstractAn IP set in ℕ is a subset of ℕ which coincides with the set of finite sums taken from an infinite sequence in ℕ with not necessarily distinct terms. It has been established by H. Furstenberg and others that there is a rich connection between IP sets and idempotents in the enveloping semigroup E(X) of a compact metric dynamical system. Our aim in this paper is to further develop this program by considering special elements of E(X) with various IP properties.
Minimal actions of semisimple groups
Authors: Stuck Garrett 
Published: September 2008

AbstractWe show that a C0 minimal action of a semisimple Lie group without compact factors is either locally free or induced from a minimal action of a proper parabolic subgroup. We describe the orbit structure of the action restricted to a maximal compact subgroup, and then apply this to minimal actions in low dimension. We give some examples, applications, and open problems.
Mutant knots with symmetry
Authors: MORTON H. R. 
Published: September 2008

AbstractMutant knots, in the sense of Conway, are known to share the same Homfly polynomial. Their 2-string satellites also share the same Homfly polynomial, but in general theirm-string satellites can have different Homfly polynomials form> 2. We show that, under conditions of extra symmetry on the constituent 2-tangles, the directedm-string satellites of mutants share the same Homfly polynomial form< 6 in general, and for all choices ofmwhen the satellite is based on a cable knot pattern.We give examples of mutants with extra symmetry whose Homfly polynomials of some 6-string satellites are different, by comparing their quantumsl(3) invariants.
On the mean square formula of the error term in the Dirichlet divisor problem
Authors: LAU YUK-KAM , TSANG KAI-MAN 
Published: September 2008

AbstractLet F(x) be the remainder term in the mean square formula of the error term Δ(t) in the Dirichlet divisor problem. We improve on the upper estimate of F(x) obtained by Preissmann around twenty years ago. The method is robust, which applies to the same problem for the error terms in the circle problem and the mean square formula of the Riemann zeta-function.
The Bott cofiber sequence in deformation K-theory and simultaneous similarity in U(n)
Authors: LAWSON TYLER 
Published: September 2008

AbstractWe show that there is a homotopy cofiber sequence of spectra relating Carlsson's deformation K-theory of a group G to its “deformation representation ring,” analogous to the Bott periodicity sequence relating connective K-theory to ordinary homology. We then apply this to study simultaneous similarity of unitary matrices.
Some factors influencing electrolyte leakage from maize (Zea mays L.) kernels
Authors: Bruggink H. , Kraak H. L. , Dijkema M. H. G. E. , Bekendam J. 
Published: September 2008

AbstractEven though the embryo of a maize (Zea mays L.) kernel contributes relatively little to total kernel weight, it is a main source of electrolytes which leach from the kernel during imbibition. Ageing of maize kernels for 18 days at 40°C and a moisture content of about 15% results in an increase of electrolyte leakage which almost exclusively originates from the embryo. The effect of ageing is most apparent after prolonged periods of imbibition. Mechanical damage increases leakage early during imbibition, the effect of damage being considerably larger for aged than for unaged kernels. The large amount of electrolytes measured after the first hour of imbibition of undamaged kernels comes mainly from the pericarp. The electrolyte content of the pericarp is variety dependent and may interfere with quality testing by conductivity measurements.
Seed quality, cotyledon elongation at suboptimal temperatures, and the yield of onion
Authors: Wheeler T. R. , Ellis R. H. 
Published: September 2008

AbstractCotyledon length in onion (Allium cepa, cv. White Lisbon) was linearly related to time from radicle emergence until the formation of the cotyledon hook, but thereafter increased exponentially with time. Within each phase the rate of cotyledon elongation was linearly related to temperature, and these relations were similar among seeds from several percentiles of the germinating populations of three contrasting seed lots. The mean base temperature was 1.4°C. These thermal time relations closely predicted the elongation of cotyledons of seedlings from cohorts of early- and lategerminators from a further lot of this cultivar at two suboptimal temperatures. Eleven cohorts of seedlings from seeds of differing quality were transplanted to the field on both the same date and at the same time from visible germination. The plants were harvested 59 days later. No effect of seed quality on mean plant weight, mean bulb diameter, or interplant variation in bulb diameter was detected. It is concluded that the rate of pre- and post-emergence seedling growth in onion is independent of environmentally induced differences in seed quality (seed vigour). Thus, any effect of this factor on plant size or crop yield, at a given density, is solely a function of time to germinate.
Imbibitional injury in maize seed independent of chilling temperature
Authors: Bochicchio A. , Coradeschi M. A. , Zienna P. , Bertolini M. , Vazzana C. 
Published: September 2008

AbstractLow and high moisture kernels and embryos were imbibed by soaking in distilled water at 5°C and 25°C. Leaching of seeds and embryos was measured by ion conductivity of imbibition water after fixed time intervals. Imbibed kernels were placed on moist filter paper after 1 h imbibition and embryos on a solid culture medium after 15 min imbibition and germinated at 25°C. Primary root length was measured 3 days after germination.The leakage from seeds or embryos was correlated with the velocity of water uptake but did not show its highest values when low moisture seeds or embryos were imbibed at chilling temperature. Furthermore germination was apparently not affected by imbibitional chilling of either low moisture content seeds or embryos. In one of the three genotypes tested (B73) seedlings from low moisture content seeds imbibed at 5°C showed a reduction of the primary root growth. However, this reduction was also seen in seedlings from low moisture B73 seeds imbided at 25°C and resulting in higher level of leaching. Thus, injury by imbibition of low moisture seeds appears independent of chilling temperature and not due to loss of semipermeability of membrane lipids. Our results suggest that, in the case of embryos, water inrush into the cells reaches levels injurious for membrane integrity independently of the two moisture contents and temperature considered.
Biochemical events during germination and early growth of somatic embryos and seed of interior spruce (Picea glauca engelmannicomplex)
Authors: Cyr D. R. , Webster F. B. , Roberts D. R. 
Published: September 2008

AbstractUtilization of lipid and protein storage reserves was examined during germination and early growth of somatic and excised seed embryosin vitro, and seed of interior spruce. High germination frequencies were recorded for somatic and excised seed embryos, and elongation of radicles and hypocotyls observed for both embryo types. Although elongation of the embryo types differed (i.e. somatic ≤ excised seed < seed), fresh weight gain was similar. Utilization of triglycerides in somatic embryos was more rapid than in excised seed and seed embryos, thus it appeared to be under embryo infuence. By contrast, depletion of storage proteins appeared to be influenced by the megagametophyte, with hydrolysis in somatic and excised seed embryos preceding that of the seed embryo by 2 days. Differential utilization of the storage reserves was temporally associated with differences in growth patterns of somatic and seed embryos. The evidence presented indicates that thein vitrogermination medium does not entirely supplant the role of the megagametophyte during germination and early growth. The relevance of these results to artificial seed technology is discussed.
The sensitivity of germinatingTriticum durumL. kernels to saline environment
Authors: Petruzzelli L. , Melillo M. T. , Bleve-Zacheo T. , Marano B. , Taranto G. 
Published: September 2008

AbstractOsmotic and ionic effects of NaCl were investigated in germinating wheat. Approximately isotonic solutions of NaCl and sorbitol inhibited germination and seedling growth to similar degrees. When dry kernels were pre-imbibed in salt for 24 h and then transferred to water, germination was equivalent to that of kernels imbibed continuously in water and the development of embryos was delayed to about the same extent as kernels pre-imbibed in sorbitol for 24 h. Measurements of water uptake, respiration, biosynthetic activities and rubidium uptake in embryos dissected from grains imbibed in NaCI or sorbitol for the first 24 h demonstrated that salt supplied to dry kernels closely mimicked sorbitol in counteracting the reactivation of embryo metabolism. No toxic effects of salt were observed when dry kernels were pre-imbibed in very high NaCI concentrations for 24 h and then transferred to water, even though embryo sodium contents increased considerably. Ultrastructural observations of embryo tissue further showed that salt influx into dry grains did not produce ion-specific damage in cell organization. On the other hand, salt specific effects became evident when the 24 h salt exposure was applied to kernels pre-hydrated for 24 h and, even more, for 30 h. We conclude that in wheat the inhibition of germination by salt corresponds to that induced by an osmoticum, provided that the caryopsis has not reached the stage of germination associated with active embryo expansion.
Purification and characterization of an aspartyl proteinase from dry jack pine seeds
Authors: Bourgeois Jacqueline , Malek L. 
Published: September 2008

AbstractA high-molecular-weight aspartyl proteinase complex, sensitive to pepstatin A was purified to near electrophoretic homogeneity from dry seeds ofjack pine (Pinus banksiana, Lamb.). Two partial activities, endo-and exo-proteinolytic, were associated with the complex, judged by the analysis of haemoglobin hydrolysis products. The high activity of this enzyme in dry jack pine seed suggests a possible function in early germination.
The development of seed quality in spring barley in four environments. I. Germination and longevity
Authors: Filho C. Pieta , Ellis R. H. 
Published: September 2008

AbstractSeed development and changes in germination ability and longevity were monitored in control and shaded spring barley (Hordeum vulgareL.)crops grown in two contrasting years. Shading reduced seed dry matter accumulation rates by 24–28% and delayed maturation drying slightly, but had little effect (0–2 d) on the timing of physiological maturity (end of the seed-filling period); final seed dry weights were 76–85% of controls. Moisture contents (wb) at physiological maturity were 48–55%; final mean seed dry weights in the controls were 40.9 mg(S.E. 0.6) in 1988 and 35.2 mg (S.E. 0.5) in 1989. Shading had little orno effect on germination ability or longevity in either year. Seeds fromthe first harvest were viable when dried below 15% moisture content despite being only 34% (1988) to 63% (1989) filled; desiccation promoted germination. Maximum germination achieved after forced desiccation occurredin seeds harvested 7–10 d (1989) to 11–13 d (1988) after physiological maturity, with little subsequent change during the following 14 (1988) or 27 d (1989). Longevity continued to increase during development until a maximum was reached 18–20 d (1988) to 27 d (1989) after physiological maturity (at moisture contents on the mother plant of 18–19% and 14–15%, respectively). In both years, the longevity of these seeds was greater (P<0.005) than that of seeds harvested either subsequently or earlier at physiological maturity. The results contradict the hypothesis that maximum seed quality coincides with physiological maturity and thereafter declines. Rather, maximum seed quality was attained close to when barley seed crops can be combine harvested The subsequent decline in potential longevity on the maternal plant in the field was quantitatively similar to that expected during post-harvest storage.
Isolation and characterization of an expressed napin gene fromBrassica rapa
Authors: Kridl Jean C. , McCarter David W. , Rose Ronald E. , Scherer Donna E. , Knutzon Deborah S. , Radke Sharon E. , Knauf Vic C. 
Published: September 2008

AbstractAn expressed napin storage protein gene fromBrassica rapa, BcNA1, has been cloned and sequenced. The gene is a member of a family of four to seven napin genes inB. rapaand is highly expressed in developing seeds. An expression cassette containing the DNA flanking the napin coding region of BcNA1 has been engineered and demonstrated to function appropriately, as compared with the gene's endogenous expression, in transgenic rapeseed using the β-glucuronidase reporter gene. TheB. rapaBcNA1 gene and aB. napusnapin gene, gNa, share extremely high nucleotide homology not only throughout their coding regions, but over a DNA locus comprising 4.3 kb. We suggest the gNa gene was contributed by the originalB. rapaprogenitor of the amphidiploidB. napus.
Evidence for inhibitor involvement in thermodormancy of Grand Rapids lettuce seeds
Authors: Small J. G. Chris , Gutterman Yitzchak 
Published: September 2008

AbstractProlonged imbibition and incubation of lettuce seeds at a supraoptimal temperature induces secondary dormancy. Such seeds no longer germinate when returned to conditions optimal for germination of non-dormant seeds. The possibility that inhibitors are involved in the induction of thermodormancy was investigated.Washing of thermodormant seeds restored germination to a small extent. However, continuous leaching of seeds during high-temperature treatment with distilled water, largely prevented the induction of thermodormancy. Such seeds were qualitatively similar to nondormant seeds, i.e. they required only light to germinate at a lower temperature and germinated in the dark if given GA3. The germination water from thermodormant seeds inhibited the germination of non-dormant lettuce seeds. The inhibition was not an osmotic effect. Absorbance in the ultraviolet region was higher in germination water from thermodormant seeds than that of non-dormant seeds. It is concluded that inhibitors are involved in the induction of thermodormancy of lettuce seeds.
DNA ligase activity in deteriorated maize embryo axes during germination: a model relating defects in DNA metabolism in seeds to loss of germinability
Authors: Vázquez Edgar , Montiel Fernando , Vázquez-Ramos Jorge M. 
Published: September 2008

AbstractChromosome integrity and DNA polymerase activity are negatively affected by improper storage of maize seeds. We have extended our studies on the effect of improper storage on DNA metabolism by analysing the effect of hot–dry and hot–humid conditions on DNA ligase activity. An assay to measure ligase activity was established by using linearized plasmid DNA as substrate and protein extracts from maize axes. Optimal conditions were established for thein vitroassay. Enzyme activity was importantly reduced under both storage conditions. Activity recovered 6–9 h after imbibition. A model for loss of viability and vigour due to damage of DNA metabolism is proposed.
Seed development in the recalcitrant speciesQuercus roburL.: germinability and desiccation tolerance
Authors: Finch-Savage W. E. 
Published: September 2008

AbstractChanges in germination and desiccation sensitivity were measured throughout the seed expansion phase of development in fruits ofQuercus roburL. The onset of a reduction in sensitivity to desiccation during development on the tree coincided with acquisition of the capacity for seed germination on moist sand substrate. Tolerance of desiccation then increased throughout development to shedding, but viability was still lost at a relatively high moisture content, and seeds did not therefore pass through a fully desiccation-tolerant phase. These data suggest that desiccation sensitivity inQ. roburmay have resulted from the premature termination of development.No desiccation was required to initiate germination in prematurely harvested fruits orseeds. Germination rate of seeds on moist sand increased at successive harvests during development, and was also increased by presoaking seeds in water. Variation in germination rate following shedding was not related to seed size or moisture content, but was affected by shedding date. This effect was not observed when the pericarp was removed.
Short-term aerated hydration for the improvement of seed quality in Brassica oleracea L
Authors: Thornton J. M. , Powell A. A. 
Published: September 2008

AbstractSeeds of the Brussels sprouts cultivar Asmer Aries and the cauliflower cultivar Hipop were subjected to ageing at 20% moisture content and 45°C for 24 or 30 h, respectively; all seeds retained high germination after ageing. Aerated hydration of unaged and aged seeds of both cultivars for 4–8 h at a range of temperatures (10–30°C), followed by drying, resulted in improved performance, except that germination percentage and rate of cauliflower were lower at 10°C. Thus, all treated seeds showed greater germination rate and seedling root length than the control, which may have resulted from the advancement of the process of germination. The deleterious effect of aerated hydration at 10°C on cauliflower could be explained by damage due to rapid imbibition; seeds that had imbibed slowly to close to full imbibition (41% moisture content) before aerated hydration showed no decrease in germination. The improvement of aged seeds after aerated hydration was also revealed by higher germination after the controlled-deterioration test, which indicated less deterioration in treated seeds. Furthermore, the optimum improvements for all seeds were observed at 25°C and were greater when the water was aerated than non-aerated. These observations indicate the activation of metabolic repair processes during aerated hydration, leading to a reversal of the deterioration sustained during ageing.
Leek (Allium porrum L.) seed development and germination
Authors: Gray D. , Steckel J. R. A. , Hands L. J. 
Published: September 2008

AbstractThe effects of development of leek seeds at 20/10°, 25/15° and 30/20°C (day/night) and drying of seed harvested at different developmental stages on subsequent performance were examined in each of 3 years. An increase in temperature from 20/10° to 30/20°C reduced mean seed weight from 2.90 to 2.55 mg as a result of a reduction in the duration of seed growth from 80 to 55 days; seed growth rate was unaffected. Seed moisture content reached a minimum, up to 35 days after the attainment of maximum seed dry weight and 115, 90 and 70 days after anthesis at 20/10°, 25/15° and 30/20°C, respectively. The curves relating seed moisture to time for each temperature regime were mapped onto a single line accounting for >90% of the variation in moisture content, using accumulated day-degrees >6°C instead of chronological time. Seeds were capable of germinating when seed moisture contents were >60% (fresh weight basis), but maximum viability and minimum mean time to germination were not attained until seed moisture contents at harvest had fallen to 20–30%. Germination was little affected by temperature of seed development. Drying immature seeds increased percentage germination. Growing seeds at 30/20°C and drying at 35°C and 30% RH raised the upper temperature limit of germination compared with growing at 20/10°C and drying at 15°C and 30% RH.
Tonoplast and plasma membrane ATPases from maize lines of high or low vigour
Authors: Sánchez-Nieto S. , Rodríguez-Sotres R. , González-Romo P. , Bernal-Lugo I. , Gavilanes-Ruíz M. 
Published: September 2008

AbstractThe effectiveness of ATPase in germinated seed may play an important role in the vigour of germination. The activities of tonoplast and plasma membrane ATPases in two maize (Zea maysL.) lines with different vigour of germination were determined. ATP hydrolysis was measured in microsomal fractions from coleoptiles along with the responses to specific inhibitors for the plasma membrane, tonoplast and mitochondrial ATPases as well as for acid phosphatase. Nitrate-sensitive ATPase activity was 1.5–3.0 times lower in the low-vigour line than in the high-vigour line. Kinetic analysis of ATP hydrolysis at different substrate concentrations revealed the existence of two enzymes in the microsomal fractions of the two lines. TheVmaxof enzyme 1 in the low-vigour line was a third of that in the high-vigour line. This enzyme was identified as the nitrate-sensitive or tonoplast ATPase on the basis of measurements of ATP hydrolysis in the presence of specific inhibitors at high (8.12mm) and low (0.77mm) ATP concentrations.
Trypsin inhibitors inPisum: variation in amount and pattern of accumulation in developing seed
Authors: Domoney C. , Welham T. 
Published: September 2008

AbstractA survey ofPisumgenotypes for seed trypsin inhibitors revealed a tenfold range in the extent of inhibition. Approximately 90% of trypsin inhibitory activity was associated with two albumin fractions in selected variant lines. The differences among extreme variants were consistent in three environments, between two sources of trypsin tested and whether expressed on a unit protein or dry weight basis.A study of the appearance of trypsin inhibitors during seed development in selected highand low-inhibitor lines showed differences in the accumulation pattern of active inhibitors. An endogenous protease was identified inPisumseed protein preparations, whosein vitrotrypsin-like activity was predominant in protein from early stages of seed development, when little or no trypsin inhibitor was present. However, there was no correlation between the amount of this protease and the extent of trypsin inhibitory activity in lines that varied for inhibitor content.