bluuebunny/crossref_metadata_2025 huggingface dataset:
Floraison et réversion chez Sinapis alba. I. Utilisation, pour l'étude de la mise à fleurs, du délai de floraison et du nombre de feuilles de l'axe principal et des axes latéraux
Authors: Bagnard Clémence
Published: October 2008

The four experiments described permit the following methodological conclusions to be derived: (1) The time required for flowering and the number of leaves preceding the first flower on the principal axis are both necessary to compare the effect of treatments on progress towards flowering. One can conclude that a factor is favorable or unfavorable, only if it entails for both measurements a modification in the same direction. (2) Lateral axes are equally usable even in a case in which the treatment involves a preinduction phase and in which the principal axis alone does not permit a conclusion. In some cases the effect of a factor may be more evident on the lateral axes than on the principal axis.
The influence of nitrogen and phosphorus levels on the phytotoxicity of phenolic compounds
Authors: Stowe Lawrence G. , Osborn Ann
Published: October 2008

The interaction between the phytotoxicity of certain phenolic compounds and deprivation of certain nutrients was investigated by means of a factorial experiment. Two concentrations of p-coumaric acid and two of vanillic acid were added to nutrient solutions containing various quantities of nitrogen and phosphorus, and these solutions were tested on barley plants in sand culture. Phenolic toxicity appears to depend intimately on nutrient concentrations; the phenolic acids were uniformly and significantly inhibitory only at low nutrient concentrations. Allelopathy with phenolics as chemical inhibitors seems most likely to occur in nutrient-poor soils.
Effect of carbon dioxide, oxygen, and dichlorophenyldimethylurea on the light-sensitive activity of xanthine dehydrogenase in cotyledons of Pharbitis nil
Authors: Nguyen J. , Cornic G. , Imhoff C. , Louason G.
Published: October 2008

The in vivo activity of xanthine dehydrogenase measured in cotyledons of Pharbitis nil depended on the environmental conditions to which plants had been subjected before measurement. The lowest value was obtained in plants placed under light (110 W m−2) in 21% O2 and 0.03% CO2, and represents approximately one fourth of the activity of the dark control. The activity could be increased in illuminated plants either when CO2 was removed from the atmosphere or when DCMU (dichlorophenyldimethylurea) was given to the cotyledons. The effect of DCMU on the level of in vivo activity of xanthine dehydrogenase was removed completely by a supply of sucrose to the cotyledons. Furthermore, it was shown that a reduction of the O2 concentration in CO2-free air surrounding the plants enhanced the activity of xanthine dehydrogenase in both illuminated and darkened plants.The results are discussed in relation to the mechanism by which photosynthetic activity could regulate the level of the activity of xanthine dehydrogenase.
Epipelic and epiphytic algal communities in Great Slave Lake
Authors: Moore James W.
Published: October 2008

Seasonal changes in the densities of epiphytic and epipelic algae were determined during 1975 and 1976 at two sites on the north shore of Great Slave Lake. The epiphyton waxed rapidly in May and reached maximum densities of 5–6 × 108 μm3/cm2 in June. Although densities remained high during the summer, they fell rapidly in October, followed by a secondary peak in November. The main species were Tabellaria flocculosa, Achnanthes minutissima, Achnanthes linearis, Gomphonema intricatum, and Lyngbya diguetii. The epipelon, consisting largely of Nitzschia palea, Nitzschia dissipata, Fragilaria construens, and Oscillatoria spp., also showed spring and fall peaks in densities, with maximum populations of 4.2 × 108 μm3/cm2 being recorded in June and July. The growing season for both communities was limited by the formation of ice in the fall, whereas the maximum standing crop of the flora was at least partially restricted by low nutrient levels (total phosphorus, 0.008 mg/L; total alkalinity, 30 mg/L).Seasonal changes in the density of epipelon were monitored during 1977 and 1978 at a third site on the north shore of the lake, where total phosphorus and total alkalinity ranged up to 0.010 and 94 mg/L, respectively. Prevalent taxa included Cymatopleura elliptica, Epithemia turgida, Rhopalodia gibba, Cymbella spp., and Nostoc spp. The growth cycles of the flora were again characterized by spring and fall peaks in numbers. Algal densities were, however, high (up to 2.3 × 109 μm3/cm2), possibly a reflection of nutrient availability.Samples of epiphyton and epipelon were taken at an additional seven sites in the east arm of the lake during June and July 1975. The main epiphytic species were Cocconeis placentula, Achnanthes minutissima, and Tabellaria flocculosa, while prevalent epipelic taxa included Navicula graciloides, Fragilaria vaucheriae, Tabellaria flocculosa, and Achnanthes minutissima. Densities were less than those recorded from the three sites on the north shore, again possibly a reflection of nutrient availability.
Nonrandom variation of gas exchange within arctic lichens
Authors: Nash III Thomas H. , Moser Thomas J. , Link Steven O.
Published: October 2008

Nonrandom variation in gas exchange of the three arctic lichens Cladonia rangiferina (L.) Wigg., Cladonia stellaris (Opiz) Brodo, and Parmelia separata Th. Fr. is documented through a combination of field and laboratory studies. The highest rates of both photosynthesis and respiration occur in the youngest, actively growing sections of the thalli and both parameters decrease progressively into the older sections. For the two Cladonia species gross photosynthesis is shown to vary directly as a function of chlorophyll a and b concentration as found in a vertical profile through the lichen mat.
The taxonomy of the highbush blueberry, Vaccinium corymbosum
Authors: Kloet S. P. Vander
Published: October 2008

Four hundred and ninety seven highbush blueberry specimens belonging to Vaccinium § Cyanococcus were collected from 56 sites in eastern North America. Numerical, cytological, and experimental analyses suggest that the highbush group should be recognized as a single polymorphic species, namely V. corymbosum L. Furthermore I postulate that the group originated in northern Florida from a hybrid swarm which resulted when V. tenellum came into contact with V. darrowii during the Pleistocene. At present the species is still acquiring characteristics through introgression with its lowbush congeners.
The effects of abscisic acid and vapor pressure deficit on leaf resistance of Paphiopedilum leeanum
Authors: Mayo James M. , Ehret Dave
Published: October 2008

Evidence is presented to show that 1 × 10−5 M abscisic acid reduces transpiration of Paphiopedilum leeanum by 42% and increases leaf resistance by 79%. Increasing vapor pressure deficit from 0.5 kPa to ca. 3.0 kPa increases leaf resistance from ca. 6 S cm−1 to ca. 10 S cm−1. These results are discussed in view of the lack of guard cell chlorophyll and the lack of K+ involvement in stomatal movement in this species.
Plant regeneration from cell cultures of Lotus corniculatus and the selection and characterization of 2,4-D tolerant cell lines
Authors: Swanson E. B. , Tomes D. T.
Published: October 2008

The isolation and characterization of a rapidly growing, friable, green, 2,4-D tolerant callus line of birdsfoot trefoil (Lotus corniculatus cv. Leo) is described. Differences in cell morphology, growth rate, totipotency, and 2,4-D tolerance were examined between selected and control callus stocks. Plants were regenerated from both the 2,4-D tolerant callus and from a number of callus lines which had been exposed to high 2,4-D levels. The selected plant populations are being maintained and increased by shoot tip culture.
Shoreline Erosion and Restabilization in the Southern Indian Lake Reservoir
Authors: Newbury R. W. , McCullough G. K.
Published: October 2008

Prior to a 3-m impoundment in 1976, bedrock comprised 76% of the shoreline of Southern Indian Lake in northern Manitoba. This was reduced to only 14% of the shoreline as the water level rose above the wave-washed zone and flooded into the predominantly fine-grained, frozen overburden materials. Twenty monitoring sites were surveyed annually to determine rates of permafrost melting and solifluction and shoreline erosion. The sequence of shoreline erosion in permafrost materials was found to be cyclic, consisting of melting and undercutting of the backshore zone, massive faulting of the overhanging shoreline, and removal of the melting and fractured debris. Rates of shoreline erosion varied widely, depending on the exposure of the site to wave action and the composition of the backshore materials. At sites in fine-grained frozen silts and clays, representative of over three quarters of the postimpoundment shoreline, rates of retreat of up to 12 m∙yr−1were observed. The total volume of shoreline materials removed varied from less than 1 to over 23 m3∙m shoreline length−1∙yr−1. Clearing of the forested backshore prior to flooding did not affect the erosion rates. The index of erosion based on the hindcast wave energy component perpendicular to the shoreline was 0.00035 m3∙t-m wave energy−1(0.036 m3∙MJ−1). The minimum period of restabilization of the shoreline based on the volume of backshore materials that must be eroded before bedrock conditions are reestablished was estimated to be 35 yr for three quarters of the shoreline surrounding the lake.
Effect of Impoundment and Diversion on the Sediment Budget and Nearshore Sedimentation of Southern Indian Lake
Authors: Hecky R. E. , McCullough G. K.
Published: October 2008

Shoreline erosion added an annual average of 4 × 106 t of mineral sediment per year to Southern Indian Lake (postimpoundment area, 2391 km2) during the first 3 yr of impoundment. This erosion increased sedimentary input to the lake by a factor of 20. The lake retained 90% of this eroded material within its basin, and 80–90% of the retained material was deposited nearshore. Despite the production of extremely fine constituent particle sizes, eroding shorelines generated predominantly large clay aggregates, initially transported offshore as bed load. During bed load transport, abrasion of clay aggregates produced fine particles that became suspended. Over 80% of the suspended load is lost to outflows from the lake because the suspended load is primarily fine silt and clay-sized particles, most of which do not settle even under winter ice cover. The extensive nearshore clay aggregate deposits are temporary, and net deposition in these areas will change to net erosion when input of sediment from eroding shorelines ceases. The effects of shoreline erosion on the lake's sediment regime will persist for decades.
Thermal and Optical Characteristics of Southern Indian Lake before, during, and after Impoundment and Churchill River Diversion
Authors: Hecky R. E.
Published: October 2008

In 1976 Southern Indian Lake, a large, shallow, multibasin lake on the Churchill River in northern Manitoba, was impounded. The mean annual water level was raised 3 m over the historic mean level to divert 875 m3∙s−1 by gravity flow from the lake into the Nelson River drainage. Five years of observation beginning 2 yr before the year of impoundment and continuing for 2 yr after impoundment indicate that lake temperatures, light available for photosynthesis, and Secchi disk transparencies have all declined. Increased mean depths, loss of riverine heat input because of diversion, and radiative losses because of back-scattering from increased concentrations of suspended solids have caused a significant 1–2 °C cooling of the different basins of the lake and increased the natural south to north temperature gradient during the lake's heating period. Winter temperatures also decreased significantly in South Bay, the point of diversion, because of increased inflow from a cooler region, increases in light scattering caused by higher concentrations of suspended solids derived from shoreline erosion accounted for the most significant changes in vertical extinction coefficients and Secchi disk depths. Increased extinction of light and increased mean depth significantly reduced the mean water column light intensity of the mixed layer. These changes in the thermal and optical characteristics after impoundment occurred concurrently with significant changes in the impoundment's biological communities.
Chironomidae (Diptera) Emerging from the Littoral Zone of Reservoirs, with Special Reference to Southern Indian Lake, Manitoba
Authors: Rosenberg David M. , Bilyj Bohdan , Wiens Allen P.
Published: October 2008

The adult chironomid fauna of the littoral zone of Southern Indian Lake (SIL) was compared with that of other similar reservoir studies. A total of 158 species of adult Chironomidae were collected from the littoral zone ([Formula: see text] depth) of SIL from 1977 to 1979, using submerged funnel traps. This number is the highest reported from reservoirs for which adult data are available. Chironomini usually were the most diverse group of Chironomidae in the reservoirs examined, accounting for approximately half the number of species collected. The abundances of Tanypodinae and Orthocladiinae appeared to decrease and increase, respectively, as reservoir trophic status changed from eutrophic to oligotrophic. Species of Chironomidae characteristic of littoral zones of new reservoirs were determined using a three-step procedure that revealed that Procladius culiciformis (Linn.), Endochironomus albipennis (Meig.), and Tanytarsus lugens Kieff. may be characteristic of reservoirs of the Palaearctic region; no species are characteristic of reservoirs of the Nearctic region; and Glyptotendipes paripes (Edw.) may be characteristic of reservoirs of both regions. Potential future research resulting from this work is discussed.
Increases in Fish Mercury Levels in Lakes Flooded by the Churchill River Diversion, Northern Manitoba
Authors: Bodaly R. A. , Hecky R. E. , Fudge R. J. P.
Published: October 2008

Reservoir creation has often been inferred as a cause of elevated fish mercury concentrations. Increases in fish muscle mercury levels, occurring coincidentally with flooding, are documented for three lakes affected by the Churchill River diversion for which pre- and post-impoundment data were available. For example, northern pike (Esox lucius) and walleye (Stizostedion vitreum vitreum) muscle mercury levels from Southern Indian Lake, which was increased in surface area by 21% by flooding in 1976, increased from baseline values of 0.2–0.3 μg∙g−1 prior to flooding to 0.5–1.0 μg∙g−1 in 1978–82. Muscle mercury levels from predatory species (northern pike and walleye) from all 10 lakes tested in the Churchill, Rat, and Burntwood valleys flooded by the Churchill diversion are near to or exceed the current export marketing limit of 1.0 μg∙g−1. Because mercury levels in fish from nearby unflooded lakes have not shown recent increases, atmospheric fallout of the metal does not appear to be the cause of the problem. Also, there are no known industrial sources of mercury in the area and no agricultural activity. Postimpoundment mercury levels in predatory fish appeared to be related to the flooded terrestrial area compared with preimpoundment lake area. They were highest (1.15–2.90 μg∙g−1) in Rat and Notigi lakes, which were increased in surface area by 282%, lower (0.60–1.53 μg∙g−1) in lakes immediately below Notigi Reservoir, increased in surface area by 31–37%, and lowest (0.45–1.03 μg∙g−1) in Southern Indian and Wuskwatim lakes, increased in surface area by 13–21%. Fish mercury levels responded quickly to impoundment, increasing noticeably within 2–3yr. Declines in mercury concentrations had not, in general, taken place within 5–8yr of impoundment, with the exception of lake whitefish (Coregonus clupeaformis) from Southern Indian Lake. It is hypothesized that observed fish mercury level increases were due to the bacterial methylation of naturally occurring mercury found in flooded soils.
Collapse of the Lake Whitefish (Coregonus clupeaformis) Fishery in Southern Indian Lake, Manitoba, following Lake Impoundment and River Diversion
Authors: Bodaly R. A. , Johnson T. W. D. , Fudge R. J. P. , Clayton J. W.
Published: October 2008

The lake whitefish (Coregonus clupeaformis) fishery of Southern Indian Lake (SIL) has undergone a general collapse since lake impoundment and Churchill River diversion in 1976. The fishery was substantial from its inception in 1941, with a mean annual whitefish catch of 333 500 kg over the 3 decades prior to lake impoundment. The whitefish catch prior to impoundment was composed almost exclusively (> 99%) of light colored, export (A) quality fish that were only lightly parasitized with the muscle cysts of Triaenophorus crassus. The market quality of the catch was maintained by selective fishing of certain lake basins and avoiding areas of the lake that were known to produce lower quality fish. Catch per unit of effort on traditional fishing grounds declined soon after impoundment to about one-half preflooding levels. Total catches were maintained at or near preimpoundment levels by major increases in total effort until 1982, when the whitefish catch fell to about one third of its preimpoundment mean. Fishermen also responded to declines in catch per unit of effort on traditional fishing grounds with a major geographic shift of effort into areas formerly avoided. As a result, darker colored, continental (B) quality whitefish comprised from 12 to 72% of the summer catch in the 4 yr following impoundment. Dark whitefish are less marketable because of color and because of higher rates of Triaenophorus infestation. The mean Triaenophorus cyst count in shipments has increased markedly since impoundment and the lake was reclassified from export (A) to continental (B) classification in 1982. Catch declines on traditional fishing grounds apparently reflect the emigration of fish to other SIL basins and/or to adjoining water bodies. Prior to lake impoundment, there were significant differences in glycerol-3-phosphate dehydrogenase allele frequencies from whitefish samples taken from four basins of SIL and an adjacent unconnected lake, but these differences were absent after impoundment. It is hypothesized that these stock redistributions were triggered by physical changes in SIL after lake impoundment.
Postimpoundment Winter Sedimentation and Survival of Lake Whitefish (Coregonus clupeaformis) Eggs in Southern Indian Lake, Manitoba
Authors: Fudge R. J. P. , Bodaly R. A.
Published: October 2008

Flooding of Southern Indian Lake for hydroelectric power development has resulted in extensive wave erosion of glacio-lacustrine clay shore material and greatly increased suspended sediment levels. Winter sedimentation on spawning grounds of lake whitefish (Coregonus clupeaformis) ranged from 0.03 to 0.14 g dry wt sediment∙cm−2. This deposited a layer 1–4 mm in depth. The sediment, low in organic content, was categorized as silty clay. The effect of this winter sedimentation on survival of whitefish eggs was tested at four sites over a range of winter sedimentation rates. Three of the sites were whitefish spawning areas. Egg survival was significantly higher for eggs incubated in cages designed to minimize exposure to sedimentation compared with survival in cages allowing full exposure to sedimentation. Winter sedimentation rates and whitefish egg survival were negatively correlated for cages designed to minimize exposure to sedimentation, while egg survival in the exposed cages was uniformly low.
Postimpoundment Change in Financial Performance of the Southern Indian Lake Commercial Fishery
Authors: Wagner M. W.
Published: October 2008

Since impoundment of Southern Indian Lake in 1976, two economic surveys of the summer fishery have been carried out in 1977 and 1980. These surveys revealed a decrease in cash flow per fishing enterprise of 66%, from $3362 to $1141 (1980$), so that by 1980 the average enterprise could not meet its capital costs. The reduction in cash flow was mainly attributable to decreased gross revenues, due to decreased catch per unit effort on traditional fishing grounds, an increase in the proportion of lower grade whitefish in the catch, and a decrease in the average number of days spent fishing per enterprise. Consideration of a freight subsidy paid to fishermen further accented the decrease in financial performance. It is projected that by 1981 economic viability had worsened further.
Environmental Impact Prediction and Assessment: the Southern Indian Lake Experience
Authors: Hecky R. E. , Newbury R. W. , Bodaly R. A. , Patalas K. , Rosenberg D. M.
Published: October 2008

The impoundment of Southern Indian Lake (SIL) and diversion from the lake of the Churchill River in northern Manitoba, Canada, were the subjects of two independent environmental impact statements. Subsequently, a case study measured change in the limnological and biological characteristics of the lake after development. Comparison of pre- and post-impoundment observations allows an assessment of the predictive capability that was applied to the lake by the preimpact statements. Predictions related to the physical environment, e.g. increased shoreline erosion, littoral sedimentation, higher turbidity, and decreased light penetration and visibility, were qualitatively correct; however, an unpredicted decrease in water temperature also occurred. Increased phosphorus availability and light limitation of primary production were also correctly forecasted in a qualitative manner. These aspects will be quantitatively predictable in future reservoirs because of studies at SIL and elsewhere. Biological responses above the primary trophic level were mostly not predicted or predicted incorrectly. Unpredicted changes that were especially significant to the fishery were rapid declines in the quantity and quality of whitefish (Coregonus clupeaformis) catch, increases in mercury concentrations in fish, and the need for extensive compensation programs to keep the fishery economically viable. Testable hypotheses to explain all unpredicted events have been formulated but require experimental verification. The paradigm of reservoir ecosystem development that is present in the literature requires reformulation if future environmental impact analyses of reservoirs are to be improved.
Increasing the physical markers of wheat chromosomes using SSRs as FISH probes
Authors: Cuadrado Angeles , Cardoso Milena , Jouve Nicolás
Published: October 2008

In plants the marker sequences used to identify chromosomes are mainly repetitive DNA probes. Simple sequence repeats (SSRs) are major components of many plant genomes and could be good markers for chromosome identification. In a previous work, we reported the physical distribution of 4 oligonucleotides, (AG)12, (CAT)5, (AAC)5, and (AAG)5, on Triticum aestivum L. chromosomes. The distinctive distribution pattern found suggested that SSR in situ hybridization is useful as a diagnostic tool in wheat cytogenetics. To check whether that finding is generally applicable, we analyzed the chromosomal distribution of the rest of the 14 possible classes of di- and tri-nucleotide repeats by FISH. A detailed knowledge of the sequence content of hexaploid wheat chromatin was acquired based on the hybridization signals, which also provide a rich set of chromosome markers for chromosome identification. Except for (AT)10 and (GC)10, for which the chromosomal distribution could not be accurately determined, and (AC)8 and (GCC)5, which were found dispersed throughout the chromosomes, the remaining repeats were observed as clusters on specific chromosome sites. (AGG)5, (CAC)5, (ACG)5, (AAT)5, and (CAG)5 exhibited a preferential distribution in the pericentromeric regions of the B genome chromosomes. The richest patterns of intercalary signals on several A and B genome chromosomes were produced by (ACT)5. A karyotype based on the SSR probes providing the best FISH patterns was constructed for T. aestivum ‘Chinese Spring’.
Mitochondrial genome organization and phylogeny of two vespid wasps
Authors: Cameron Stephen L. , Dowton Mark , Castro Lyda R. , Ruberu Kalani , Whiting Michael F. , Austin Andy D. , Diement Kieren , Stevens Julia
Published: October 2008

We sequenced the entire mitochondrial genome of Abispa ephippium (Hymenoptera: Vespoidea: Vespidae: Eumeninae) and most of the mitochondrial genome of Polistes humilis synoecus (Hymenoptera: Vespoidea: Vespidae: Polistinae). The arrangement of genes differed between the two genomes and also differed slightly from that inferred to be ancestral for the Hymenoptera. The genome organization for both vespids is different from that of all other mitochondrial genomes previously reported. A number of tRNA gene rearrangements were identified that represent potential synapomorphies for a subset of the Vespidae. Analysis of all available hymenopteran mitochondrial genome sequences recovered an uncontroversial phylogeny, one consistent with analyses of other types of data.
New resources for studying the rose flowering process
Authors: Foucher Fabrice , Chevalier Michel , Corre Christophe , Soufflet-Freslon Vanessa , Legeai Fabrice , Hibrand-Saint Oyant Laurence
Published: October 2008

Knowledge of the flowering process — an important trait in ornamental plants such as roses — is necessary for efficient control of flowering. This study was carried out to develop and characterize new resources to gain further insight into floral control in rose. We studied floral initiation in a nonrecurrent blooming rose (hybrid of Rosa wichurana ) and a recurrent blooming rose ( Rosa hybrida Black Baccara®). In Black Baccara®, floral initiation took place rapidly after bud burst, whereas in the greenhouse R. wichurana remained vegetative. During floral initiation, the apex enlarged and domed quickly and concomitantly. This is the first description of this transition between the vegetative and floral bud stages in rose. From these vegetative and pre-floral tissues, two cDNA libraries were constructed and 5000 ESTs sequenced. By collecting our ESTs and those available in public databases, we developed a comprehensive database representing ~5000 unique sequences after clustering. By screening this database for candidate genes involved in the flowering process, we identified 13 genes potentially involved in gibberellic acid signalling, photoperiod pathways, and floral development. Based on expression data, we put forward different hypotheses on the control of flowering in rose (photoperiod control and involvement of gibberellins) relative to what is already known in Arabidopsis .
Natural polyploidy inVanilla planifolia(Orchidaceae)
Authors: Bory Séverine , Catrice Olivier , Brown Spencer , Leitch Ilia J. , Gigant Rodolphe , Chiroleu Frédéric , Grisoni Michel , Duval Marie-France , Besse Pascale
Published: October 2008

Vanilla planifolia accessions cultivated in Reunion Island display important phenotypic variation, but little genetic diversity is demonstrated by AFLP and SSR markers. This study, based on analyses of flow cytometry data, Feulgen microdensitometry data, chromosome counts, and stomatal length measurements, was performed to determine whether polyploidy could be responsible for some of the intraspecific phenotypic variation observed. Vanilla planifolia exhibited an important variation in somatic chromosome number in root cells, as well as endoreplication as revealed by flow cytometry. Nevertheless, the 2C-values of the 50 accessions studied segregated into three distinct groups averaging 5.03 pg (for most accessions), 7.67 pg (for the ‘Stérile’ phenotypes), and 10.00 pg (for the ‘Grosse Vanille’ phenotypes). For the three groups, chromosome numbers varied from 16 to 32, 16 to 38, and 22 to 54 chromosomes per cell, respectively. The stomatal length showed a significant variation from 37.75 µm to 48.25 µm. Given that 2C-values, mean chromosome numbers, and stomatal lengths were positively correlated and that ‘Stérile’ and ‘Grosse Vanille’ accessions were indistinguishable from ‘Classique’ accessions using molecular markers, the occurrence of recent autotriploid and autotetraploid types in Reunion Island is supported. This is the first report showing evidence of a recent autopolyploidy in V. planifolia contributing to the phenotypic variation observed in this species.
Structural and expressional divergence of genes encoding O-methyltransferase in wheat
Authors: Jung Je Hyeong , Hong Min Jeong , Kim Dae Yeon , Kim Jae Yoon , Heo Hwa Young , Kim Tae Ho , Jang Cheol Seong , Seo Yong Weon
Published: October 2008

Enzymatic methylation, which is catalyzed by the large number of O-methyltransferases (OMTs), is one of the important reactions in the flow of primary and (or) secondary metabolism. In a previous study, the gene TaOMT1 was induced by Hessian fly infestation of a wheat–rye translocation line. In this study we considered other wheat OMT genes — TaOMT3, TaOMT4, and TaOMT5 —  using a bioinformatics approach and examined the TaOMT genes for their genomic organization, tissue-specific expression, responses to abiotic stresses and hormones, and cis-elements. There appeared to be a homoeologous relationship between TaOMT4 (6DS) and TaOMT5 (6BS), whereas TaOMT1 and TaOMT3 were placed on chromosome arms 7BL and 5DL, respectively. Differences in the tissue-specific, constitutive, and stress-inducible expression patterns among the TaOMT genes were found in both healthy and stressed plants. A number of cis-elements, which are potentially correlated with the responses of the TaOMT genes, were detected in the analysis of the TaOMT promoter sequences. In addition, evolutionary perspectives of the TaOMT genes are discussed. The nucleotide sequences have been deposited in the GenBank database under accession Nos. AAP23942 (TaCOMT1), EF423610 (TaOMT5), EF423611 (TaOMT4), EF423612 (TaOMT3), EU831287 (5′ upstream of TaOMT1), EU831288 (5′ upstream of TaOMT3), EU831289 (5′ upstream of TaOMT4), and EU831290 (5′ upstream of TaOMT5).
The effects of different sit- and curl-up positions on activation of abdominal and hip flexor musculature
Authors: Parfrey Kevin C. , Docherty David , Workman R. Chad , Behm David G.
Published: October 2008

The purpose of this study was to evaluate abdominal muscle activation with variations in trunk flexion (sit or curl up) positions, including the protocol currently used by the Canadian Society of Exercise Physiology (CSEP) Health and Fitness Program. Electromyographic (EMG) data were collected during isometric contractions from the upper rectus abdominis (URA), lower rectus abdominis (LRA), external obliques (EO), lower abdominal stabilizers (LAS), rectus femoris (RF), and the biceps femoris (BF) in 14 subjects. Sit-up positions were varied and randomized through 3 variables: the distance the hand traveled along the floor (5, 10, or 15 cm), bent knee or extended knee, and fixed or non-fixed feet. In regard to the distance the hand traveled along the floor, the 10 cm position produced the highest activation of the LRA (p = 0.02), the 5 cm distance produced the lowest RF activation (p = 0.001), and the 15 cm distance produced the lowest activation of the URA (p = 0.001). There was no significant difference between bent-knee and extended-leg sit-up positions; however, there was a trend (p = 0.1) showing that the bent-knee sit-up position produced higher levels of LAS activation and lower levels of RF activation. Foot fixation resulted in significantly lower activation levels of all abdominal sites and higher levels for the RF (p < 0.0001). The technique used for the CSEP Health and Fitness program partial curl- or sit-up test produced the highest or equal activation levels for all abdominal muscle sites.
What is the influence of menopausal status on metabolic profile, eating behaviors, and perceived health of obese women after weight reduction?
Authors: Riesco Eléonor , Roussel Michel , Lemoine Sophie , Garnier Sophie , Sanguignol Frédéric , Mauriège Pascale
Published: October 2008

The duration of the numerous weight-loss studies that combine physical activity and diet varies from 3 to 14 months, and these studies have often considered pre- and postmenopausal women separately. The purpose of this study was to compare the effects of a 3-week weight-reducing program that combines caloric restriction and exercise on the metabolic profile, eating behaviors, and perceived health of sedentary obese pre- and postmenopausal women, after adjustment for age. In 10 pre- and 22 postmenopausal women, before and after weight loss, body composition, fasting lipid-lipoprotein profile, glucose and insulin levels, eating behaviors, and perceived health state were assessed. Body mass index, fat mass, and waist girth decreased after weight reduction in both groups (p < 0.0001). Reductions in fasting serum cholesterol and low-density lipoprotein-cholesterol levels were greater in pre- than in postmenopausal women (p < 0.0001), whereas triacylglycerol, glucose, and high-density lipoprotein-cholesterol levels decreased similarly in both groups (p < 0.05). Neither fasting insulin nor free fatty-acid concentrations were modified after weight loss in either group. Disinhibition (p < 0.005) and hunger scores on the three-factor eating questionnaire (TFEQ) (p < 0.05) and the state-anxiety score on the state–trait anxiety inventory (STAI) questionnaire (p < 0.0005) decreased in both groups, but restriction (TFEQ) increased (p < 0.01) and trait anxiety (STAI) decreased (p < 0.001) after weight reduction only in premenopausal women. Improvements in selected lipid-lipoprotein indices, eating behaviors, and perceived health-state components were better in pre- than in postmenopausal women, suggesting that menopausal status has an influence on some metabolic and behavioral responses to weight loss.
Protective effect of sodium selenite and zinc sulfate on intensive swimming-induced testicular gamatogenic and steroidogenic disorders in mature male rats
Authors: Jana Kuladip , Samanta Pravat K. , Manna Indranil , Ghosh Prasanta , Singh Narendra , Khetan Ramawatar P. , Ray Binoy R.
Published: October 2008

To investigate the ameliorative potential of sodium selenite and zinc sulfate on intensive-swimming-induced testicular disorders, 48 Wistar male rats (age, 4 months; mass, 146.2 ± 3.6 g) were randomly divided into 4 groups: the unexercised-control group (n = 12); the exercised group (n = 12); the control supplemented group (n = 12); and the exercised supplemented group (n = 12). For 10 weeks, the exercised rats underwent a protocol that consisted of 4 h·d–1swimming, for 6 d·week–1; the control rats did not exercise. For 10 weeks, both the supplemented groups received an oral daily dose of a combination of sodium selenite and zinc sulfate (6  and 3 mg·kg body mass–1, respectively). After 10 weeks, a significant reduction (p < 0.05) was seen in rats in the exercised group, compared with rats in both control groups, in paired testicular masses; in epididymal sperm count; in testicular Δ5, 3β-hydroxysteroid dehydrogenase (HSD) and 17β-HSD; in plasma levels of testosterone, luteinizing hormone, follicle-stimulating hormone, and prolactin; in the numbers of preleptotine spermatocytes, midpachytene spermatocytes, and stage 7 spermatids of the stage VII seminiferous epithelium cycle; and in fertility performance. As well, a significant increase (p < 0.05) was seen in the exercised group, compared with both control groups, in plasma corticosterone levels and in testicular content of malondialdehyde and catalase activity. At the same time, there was a significant reduction (p < 0.05) in the exercised group, compared with both control groups, in plasma concentrations of zinc and selenium; in the testicular content of glutathione (GSH), the glutathione and glutathione disulphide (GSSG) ratio, ascorbic acid, and α-tocopherol; and in testicular activities of superoxide dismutase, glutathione-peroxidase, and glutathione-S-transferase in the testes. No significant changes were seen in the number of spermatogonia-A from the stage VII seminiferous epithelium cycle or the testicular content of GSSG among the groups. Sodium selenite and zinc sulfate supplementation significantly protected against exercise-induced testicular gamatogenic and spermatogenic disorders, prevented testicular oxidative stress, and increased antioxidant status. It can be concluded that intensive-swimming-induced oxidative stress causes dysfunctions in the male reproductive system, which can be protected by the coadministration of sodium selenite and zinc sulfate.
Protection of heart and skeletal muscle by heat shock proteins
Authors: Tupling A. Russell
Published: October 2008

This introduction includes a brief description of 4 papers that were prepared after the symposium The stress response in muscle: mechanisms and functional implications, which was presented at the Canadian Society for Exercise Physiology (CSEP) annual meeting in the autumn of 2006. These papers discuss the role heat-shock proteins (HSPs) play in protecting both cardiac and skeletal muscle from ischemic injury, contraction-induced injury, and aging, and focus on the molecular basis for the cytoprotective effects of HSPs.
Heat shock proteins 27 and 70 regulating angiotensin II-induced NF-κB: a possible connection to blood pressure control?
Authors: Voegeli Tracy S. , Wintink Amanda J. , Chen Yu , Currie R. William
Published: October 2008

Heat shock proteins (HSPs) are critical for cell survival and have several mechanisms of action. HSPs regulate protein folding, suppress apoptosis, and regulate anti-oxidative activity. In addition, HSPs are involved in the regulation of the pro-inflammatory transcription factor nuclear factor (NF)-κB. When angiotensin (Ang) II is infused into rats, there is a significant increase in systolic blood pressure, and NF-κB is activated in the heart. If rats are heat shocked to induce the heat shock response and HSPs before Ang II infusion, there is a significant suppression of both the Ang II-induced increase in blood pressure and NF-κB activation in the heart. Although the role of specific HSPs in the regulation of NF-κB is unclear, several HSPs, including Hsp27 and Hsp70, are thought to be involved in the regulation of Ang II-induced NF-κB. The role of Hsp27 and Hsp70 in NF-κB activation is reviewed here, along with evidence suggesting that HSPs regulate Ang II-induced blood pressure through the regulation of NF-κB.
Heat shock proteins and exercise: a primer
Authors: Noble Earl G. , Milne Kevin J. , Melling C.W. James
Published: October 2008

Heat shock proteins (HSPs) are, in general, prosurvival molecules within the cellular environment, and the overexpression of even just 1 family of HSPs can lead to protection against and improvements after a variety of stressors. Not surprisingly, a fertile area of study has grown out of effors to exploit the innate biologic behaviour of HSPs. Exercise, because of the inherent physiologic stresses associated with it, is but 1 stimulus that can result in a robust increase in various HSPs in several tissues, not the least of which happen to be the heart and skeletal muscle. The purpose of this review is to introduce the reader to the major HSP families, the control of their expression, and some of their biologic functions, specifically with respect to the influence of exercise. Moreover, as the first in a series of reviews from a common symposium, we will briefly introduce the concepts presented by the other authors, which include the effects of different exercise paradigms on skeletal muscle HSPs in the adult and aged systems, HSPs as regulators of inflammation, and the ion channel stabilizing effects of HSPs.
Maximal and submaximal aerobic fitness in postmenopausal women: influence of hormone-replacement therapy
Authors: Stathokostas Liza , Kowalchuk John M. , Petrella Robert J. , Paterson Donald H.
Published: October 2008

The purpose of this study was to examine whether maximal and submaximal aerobic fitness parameters (peak oxygen consumption and ventilatory threshold, respectively) are affected by hormone-replacement therapy (HRT) in moderately active postmenopausal women. Forty healthy, active, postmenopausal women (21 taking HRT, mean age 62 ± 5 years; 19 not taking HRT, mean age 62 ± 7 years) met the peak oxygen consumption criteria during a cycle ergometer test (15 W ramp) and achieved volitional fatigue. Breath-by-breath measurement was used to determine peak oxygen consumption and to estimate ventilatory threshold. There were no differences in characteristics (age, body mass, height, body mass index, leisure-time physical activity) between the non-HRT and HRT groups, nor were there any differences in responses to maximal exercise, with an observed peak oxygen consumption (mL·kg–1·min–1) of 22.9 ± 3.8 in the non-HRT group and 22.0 ± 4.7 in the HRT group. There was also no difference in submaximal aerobic capacity, with ventilatory threshold values (mL·kg–1·min–1) of 16.7 ± 3.4 in the non-HRT group and 15.6 ± 3.2 in the HRT group. In a sample of healthy moderately active postmenopausal women, there was no difference in maximal or submaximal aerobic fitness parameters beteen the HRT and non-HRT groups.
Wheelchair propulsion: effects of experience and push strategy on efficiency and perceived exertion
Authors: Lenton John P. , Fowler Neil E. , van der Woude Lucas , Goosey-Tolfrey Victoria L.
Published: October 2008

The purpose of this study was to examine the role of wheeling experience on efficiency, metabolic cost, and differentiated ratings of perceived exertion (RPEs) during synchronous and asynchronous hand-rim propulsion with varying arm frequencies. Fourteen able-bodied (AB) male participants and 8 male wheelchair sportsmen (WS) performed tests of peak oxygen consumption for both propulsion modes. Subsequently, 2 series of five 4-min sub-maximal exercise bouts were completed at an individualized velocity (60% of peak oxygen consumption). Arm frequencies consisted of the freely chosen frequency (FCF), followed by 4 counter-balanced paced trials pushing at 60%, 80%, 120%, and 140% of the FCF. Efficiency indices (gross, GE; work, WE) were determined and peripheral (RPE-P), central (RPE-C), and overall (RPE-O) RPEs were recorded. The GE (6.4% vs. 8.4%) and WE (11.3% vs. 15.1%) were significantly higher in WS than in AB (p = 0.001). Trends in the oxygen consumption, GE, and WE data were similar in both groups, propulsion mode, and arm frequency. Data suggest that 80% FCF resulted in improved efficiency for both propulsion mode and group, although the differences between those arm frequencies immediately above and below were non-significant. Lower RPE scores corresponded with higher efficiency values. Regardless of group there were significant differences (p = 0.001) between the differentiated RPE measures, whereby RPE-P was on average always the highest score (13.1) and RPE-C the lowest (11.1; RPE-O was 12.2). In conclusion, despite the anticipated differences in efficiency between the WS and AB participants, this study confirmed that psycho-physiological measures produce similar trends to physiological measures with manipulations of both arm frequency and propulsion mode.
PGC-1α-mediated regulation of gene expression and metabolism: implications for nutrition and exercise prescriptions
Authors: Benton Carley R. , Wright David C. , Bonen Arend
Published: October 2008

The discovery 10 years ago of PGC-1α represented a major milestone towards understanding of the molecular processes regulating energy metabolism in many tissues, including skeletal muscle. PGC-1α orchestrates a metabolic program regulating oxidative lipid metabolism and insulin sensitivity. This is essentially the same metabolic program that is activated by exercise and down-regulated by sedentary lifestyles and high-fat diets, as well as in cases of obesity and type 2 diabetes. The present review examines the evidence in support of the key role for PGC-1α regulation of substrate metabolism and mitochondrial biogenesis in skeletal muscle. Surprisingly, studies with PGC-1α null and transgenic mice have revealed unexpected pathologies when PGC-1α is completely repressed (KO animals) or is massively overexpressed. In contrast, PGC-1α overexpression within normal physiological limits results in marked improvements in fatty acid oxidation and insulin-stimulated glucose transport. Exercise, sedentary lifestyles, and nutritional factors can regulate PGC-1α expression. We speculate that optimal targeting of PGC-1α upregulation, whether by diet, exercise, or a combination of both, could represent effective prophylactic or therapeutic means to improve insulin sensitivity. Indeed, using modern molecular tools, it may indeed be possible to prescribe optimally individualized nutrition and exercise programs.
Development and validation of exercise target heart rate zones for overweight and obese pregnant women
Authors: Davenport Margie H. , Charlesworth Sarah , Vanderspank Dana , Sopper Maggie M. , Mottola Michelle F.
Published: October 2008

Validated target heart rate (THR) zones for exercise prescription for overweight and obese pregnant women have not been developed. The purposes of this study were to determine if heart rate reserve (HRreserve) is best described by aerobic capacity at peak exercise or by aerobic capacity reserve (VO2 reserve) and to develop and validate THR zones for light-intensity exercise (20%–39%VO2 reserve) in sedentary overweight and obese pregnant women. One hundred six women between 16 and 20 weeks gestation with medical clearance performed a progressive treadmill test to volitional fatigue (peak). Data from every 4th subject were used for cross-validation. Two linear regression equations were performed for each subject, then pooled to obtain mean group values (± SD): %HRreserve vs. %VO2 peak and %HRreserve vs. %VO2 reserve. THR zones equivalent to 20%–39%VO2 reserve were developed and validated based on the strongest relationship. %HRreserve had a stronger linear relationship with %VO2 reserve (y = 1.046x –7.561; R2 = 0.741) than %VO2 peak (y = 1.259x –28.795; R2 = 0.604). Validated THR ranges for sedentary overweight and obese pregnant women are 102–124 beats·min–1 (20–29 years of age) and 101–120 beats·min–1 (30–39 years of age), representing an exercise intensity of 20%–39%VO2 reserve as recommended by the American College of Sports Medicine for previously sedentary pregnant women. Overweight and obese women who are medically prescreened can exercise during pregnancy within our validated THR zones. The relationship between HR and VO2 remains strong, but the two are not equivalent in this population group.
Mammalian DNMTs in the male germ line DNA ofDrosophila
Authors: Weyrich Alexandra , Tang Xiaojing , Xu Guoliang , Schrattenholz André , Hunzinger Christian , Hennig Wolfgang
Published: October 2008

It is controversial whether DNA methylation plays a functional role in Drosophila . We have studied testis DNA of Drosophila melanogaster Meigen, 1830 with antisera against 5-methylcytosine (5mC) and found no evidence for the presence of significant amounts of 5mC. Reactions occur only with 1 of 3 5mC antisera, but they are restricted to nuclear regions without detectable amounts of DNA. The antisera apparently cross-react with other nuclear components. If the murine de novo DNA methyltransferases, DNMT3A and DNMT3B, are expressed under the control of the spermatocyte-specific β2-tubulin promoter in testes, DNA methylation is not increased and no effects on the fertility of the fly are seen. DNA methylation has, therefore, no functional relevance in the male germ line of Drosophila.
X chromosome inactivation: heterogeneity of heterochromatin
Authors: Sidhu Sharan K. , Minks Jakub , Chang Samuel C. , Cotton Allison M. , Brown Carolyn J.
Published: October 2008

The silent X chromosome in mammalian females is a classic example of facultative heterochromatin, the term highlighting the compacted and inactive nature of the chromosome. However, it is now clear that the heterochromatin of the inactive X is not homogeneous — as indeed, not all genes on the inactive X are silenced. We summarize known features and events of X inactivation in different mouse and human model systems, and highlight the heterogeneity of chromatin along the inactive X. Characterizing this heterogeneity is likely to provide insight into the cis-acting sequences involved in X chromosome inactivation.