bluuebunny/crossref_metadata_2025 huggingface dataset:
Conservation of leghemoglobin heterogeneity and structures in cultivated and wild soybean
Authors: Fuchsman W. H. , Palmer R. G.
Published: June 2017

The leghemoglobins from a genetically diverse selection of 69 cultivated soybean (Glycine max (L.) Merr.) cultivars and plant introductions and 18 wild soybean (Glycine soja Sieb. & Zucc.) plant introductions all consist of the same set of major leghemoglobins (a, c1, c2, c3), as determined by analytical isoelectric focusing. The conservation of both leghemoglobin heterogeneity and also all four major leghemoglobin structures provides strong circumstantial evidence that leghemoglobin heterogeneity is functional. Glycine max and G. soja produced the same leghemoglobins in the presence of Bradyrhizobium japonicum (Kirchner) Jordan and in the presence of fast-growing Rhizobium japonicum.
Growth and biomass allocation of Ruppia occidentalis in three lakes, differing in salinity
Authors: Husband Brian C. , Hickman Michael
Published: June 2017

The hypothesis that the growth and distribution of Ruppia occidentalis S. Wats. increases with increasing salinity in Alberta lakes was investigated by comparing populations of Ruppia from three lakes, spanning a wide range of total dissolved solids (0.3–6.2‰). Growth and biomass allocation of individuals were correlated with lake chemistry. Plants from the freshwater lake exhibited characters associated with moderate chemical deficiency, including decreased growth rate, decreased reproductive output, and high root:shoot ratios. The proportion of total dry weight decreased in roots and increased in shoots with salinity but varied little among depths within the lake. Changes in shoot dry weight were the result of vertical growth in the saline lakes but the result of horizontal growth through tiller production in the freshwater lake. Although salinity did not affect the reproductive effort in flowering individuals, the number of flowering individuals in the population increased with salinity. The frequency of occurrence and percentage cover of Ruppia within each lake reflect its respective growth rate and reproduction. The within-lake distributions are characterized by significant interactions between salinity and both depth distribution and substratum type. Saline conditions are required by Ruppia and not merely tolerated for maximum growth and reproduction. Its absence from many freshwater lakes is due most likely to chemical constraints on survival or on the competitive ability of Ruppia.
Growth of bean plants at elevated carbon dioxide concentrations
Authors: Jolliffe Peter A. , Ehret David L.
Published: June 2017

Plants of Phaseolus vulgaris L. cv. Pure Gold Wax were grown in controlled environment chambers at six CO2 concentrations ranging from 340 to 3000 μL L−1. Data for plant growth analysis were obtained from five harvests from 11 to 55 days after planting. Growth curves were fitted to the data using a cubic spline regression procedure. CO2 enrichment caused large and rapid increases in leaf dry weight, unit leaf rate, and specific leaf weight. Smaller responses included a decrease in leaf area ratio and an increase in leaf weight ratio. Root dry weight and leaf area were not significantly affected by CO2 treatments. Relative growth rate was initially higher in CO2-enriched plants and later declined; it may not be a suitable index for the evaluation of CO2 effects during long periods of growth. The results indicate that leaf formation and expansion were not limited by assimilate supply. Maximum growth and pod yield were obtained in plants grown at 1200 μL L−1 CO2.
Photosynthetic carbon dioxide exchange of bean plants grown at elevated carbon dioxide concentrations
Authors: Ehret David L. , Jolliffe Peter A.
Published: June 2017

Leaves of bean plants (Phaseolus vulgaris L. cv. Pure Gold Wax) grown in atmospheres enriched in CO2 (1400 μL L−1) showed a decrease in CO2 exchange capacity when compared with unenriched plants (340 μL L−1) measured at the same CO2 concentration. The decrease was not associated with changes in chlorophyll concentration or photorespiratory activity. The decrease was less evident in older leaves, in leaves maintained at low light intensity, and in those with reduced chlorophyll contents. Respiration rates in leaves of CO2-enriched plants increased only under conditions that caused a concurrent decrease in photosynthetic capacity. Enriched leaves had higher starch contents than unenriched leaves. The results were consistent with the idea that CO2 enrichment decreases photosynthetic capacity when photoassimilate supply exceeds sink demand.
Species composition and herbage production of mountain rangelands in northern British Columbia
Authors: Seip Dale R. , Bunnell Fred L.
Published: June 2017

Species composition and herbage production were determined for different range types used by ungulates in northern British Columbia. In addition, the effect of N fertilization on alpine grasslands was measured. Fire-induced subalpine grasslands produced much more herbage than other range types. Graminoid production, but not forb production, was greater in wet growing seasons. Fertilization of alpine ranges with 17–35 kg N/ha did not increase the herbage production.
An electrophoretic analysis of the seed proteins from Pinus monticola and eight other species of pine
Authors: Gifford David J.
Published: June 2017

The major storage proteins of mature Pinus monticola Dougl. seed megagametophytes are crystalloids and are only completely soluble in buffer solutions if sodium dodecyl sulphate is present. These insoluble proteins-constitute 50% of the storage reserve in the seed. Crystalloid proteins are found in embryonic axes also and are a major protein reserve in mature seeds from all other Pinus species examined. These proteins in their nonreduced form have molecular masses of 51 – 55 kilodaltons (kDa) and in reduced form migrate on polyacrylamide gels as two distinct groups of proteins, one in the molecular mass range 31 – 34.5 kDa and the other in the 21.5 – 22.5 kDa range. The pine crystalloid proteins are not glycosylated and have similar solubility, structural, and size characteristics to crystalloid proteins found in other seed types, such as Ricinus communis and Cucurbita species. However, they are immunologically different from the crystalloid proteins of R. communis. In general, the soluble protein gel profiles vary considerably among the species. Some similarities do exist; in particular, a group of proteins in the 27 – 29.5 kDa molecular mass regions of polyacrylamide gels is common to all Pinus species examined. The soluble proteins are not glycosylated.
Postpollination placental development of a diploid Solatium tuberosum
Authors: Olson A. Randall
Published: June 2017

Gynoecial placentation of Solanum tuberosum L. is axile with each parenchymatous placenta covered with numerous ovules. Three days after pollination, mitotic activity in the placental surface and subjacent layers initiates tissue proliferations, which develop between the ovules. Continued cell division and subsequent cell enlargement result in expanded placental projections, which separate the developing seeds from one another and form an interface with the inner pericarp within 10 – 12 days after pollination. Eventually, the placenta fills the remaining ovarian locular space and embeds the seeds.
Resistance of hardwood vessels to degradation by white rot Basidiomycetes
Authors: Blanchette Robert A. , Obst John R. , Hedges John I. , Weliky Karen
Published: June 2017

White stringy rot, an unusual type of selective fungal decay, can be found in wood of some dicotyledonous angiosperms. Stages of advanced decay consist of a mass of vessel elements with only remnants of other cells adhering to the vessel walls. Degradation by various white rot Basidiomycetes causes loss of fibers, fiber tracheids, and parenchyma cells but not vessels. In wood of Acacia koa var. koa with a white pocket rot caused by Phellinus kawakamii, fibers and parenchyma cells were preferentially delignified. After extensive lignin removal the cellulose remaining in the secondary wall was degraded. Large vessel elements remained relatively intact after other cells were completely degraded. The resistance of vessels to degradation appears to be due to their high ligninxarbohydrate ratio, lignin monomer composition, and cell wall morphology.
Studies in Crataegus (Rosaceae, Maloideae). XIX. Breeding behavior in Ontario Crataegus series Rotundifoliae
Authors: Smith P. G. , Phipps J. B.
Published: June 2017

Ontario members of Crataegus series Rotundifoliae display breeding behavior that is characteristic of apomictic taxa. Based on a series of analyses, including histological studies of ovule development, chromosome counts, pollen stainability and pollination studies, and phenological analyses, it appears that most of the Ontario Rotundifoliae are tetraploid (2n = 2x = 68), self-fertile, pseudogamous, facultative apomicts. Some triploid (2n = 3x = 51) apomicts are also present in C. dodgei var. flavida (Sarg.) Smith & Phipps. The results presented are congruent with previous studies of Crataegus cytogenetics. Moreover, these results have assisted the taxonomic analysis of the series by permitting the identification of predominantly apomictic microspecies as well as possible hybrid taxa.
Comportement en croisement des haploïdes doublés de cacaoyers (Theobroma cacao)
Authors: Lanaud C. , Lachenaud Ph. , Sounigo O.
Published: June 2017

The crossing value of double haploids (DH) of cacao has been studied for vegetative characters 1 or 3 months after sowing and a 1.5 year after planting, as well as for quantitative characters observed on the first two harvests. Families arising from DH × heterozygote crosses have been compared to crosses between the original parents of the DH and the same heterozygous parents. When the families came from reciprocal crosses the existence of reciprocal effects was observed. Except for the first stages of observation, DH with a higher crossing value than that of their parents have been found. The fact that the behaviour of the original parents is relatively similar to that of the DH they give rise to, justifies the assumption that classical selection might be useful in the search for good parental DH. With regard to the choice of the direction of the cross, the female HD parents seem to be unfavourable only for those vegetative characters linked to the earliest stages. This effect later disappears. For initial yields, the structure of the homozygous or heterozygous parent does not seem to influence the within-family variances, and families arising from DH × DH crosses are as heterogeneous as those obtained from crosses between two heterozygous parents. Thus, the homogenization of the offsprings through the use of DH will only be effective for characters which are very stable in the habitat.
Genome rearrangements during Anabaena heterocyst differentiation
Authors: Golden James W.
Published: June 2017

The filamentous cyanobacterium Anabaena sp. PCC 7120 produces specialized, terminally differentiated cells called heterocysts that are the sites of nitrogen fixation. The genome of Anabaena undergoes at least two specific developmentally regulated DNA rearrangements during heterocyst differentiation. One rearrangement involves the nitrogen-fixation genes nifH, nifD, and nifK. During heterocyst differentiation, an 11-kilobase (kb) DNA element is excised from the 3′ coding region of the nifD gene by site-specific recombination within 11 base pair, directly repeated sequences present at the ends of the element. The excision results in formation of a complete nifD coding sequence and allows transcription of all three genes from a single promoter upstream of nifH. The gene xisA, located at one end of the 11-kb element, is believed to encode the site-specific recombinase responsible for excision of the element from the nifD gene. A second DNA rearrangement occurs close to the 5′ end of the nifS gene and results in placing the genes rbcL and rbcS approximately 10 kb from the nif gene cluster. This rearrangement is also a deletion from the chromosome but involves a significantly larger segment of the genome, 55 kb. The genomic breakpoints of the nifS rearrangement have been cloned and sequenced. The recombination sites show no homology to those involved in the nifD rearrangement. This suggests that each rearrangement is catalyzed by a different site-specific recombination system and that the two arrangements may be independently regulated.
The developmental patterns of endo-β-1,4-glucanase and β-glucosidase of Chaetomium erraticum
Authors: Sandhu D. K. , Puri R.
Published: June 2017

The present investigation deals with the production of extracellular and intracellular endoglucanase and β-glucosidase enzymes and the study of their multiple molecular forms in Chaetomium erraticum. When C. erraticum was grown on carboxymethyl cellulose as the sole carbon source, more than 90% of the endoglucanase was extracellular, while most of the β-glucosidase was intracellular. However, the relative distribution of these enzymes varied with the age of the culture. Two forms of each of endoglucanase (EG-I, EG-II) and β-glucosidase (βGlu-I, βGlu-II) were detected after 4 and 6 days of incubation, respectively. Additional intracellular forms of endoglucanase and β-glucosidase i.e., EG-III and βGlu-III, appeared at later stages, when perithecia developed, indicating that EG-III and βGlu-III are related to the development of perithecia. These multiple molecular forms were further differentiated by their response to temperature, pH, ethylenediaminetetraacetic acid, and metal ions.
Cytogenetic studies of leafy spurge, Euphorbia esula, and its allies (Euphorbiaceae)
Authors: Stahevitch A. E. , Crompton C. W. , Wojtas W. A.
Published: June 2017

Cytological and cytogenetic studies were carried out on populations of leafy spurge (Euphorbia esula L. s.l.) and its allies primarily from North America but also from Europe. Chromosome numbers were determined for 126 samples of E. esula, 11 of E. cyparissias L., 1 of the hybrid (E. ×pseudoesula Schur) between these two species, and 1 of E. agraria Bieb. All plants of E. esula were hexaploid. Of the total, 125 leafy spurge accessions had a chromosome number of n = 30; 1 of n = 25++. Very few meiotic abnormalities were observed. Euphorbia cyparissias was primarily tetraploid (n = 20), although occasional diploids (n = 10) were encountered. Tetraploids were fertile; diploids were sterile. The hybrid between the two foregoing species had a chromosome number of n = 25, indicating that the E. cyparissias parent was a tetraploid; meiosis in the hybrid was abnormal. Euphorbia agraria was found to have a gametic number of n = 20, which is the first chromosome number determination for this species; meiosis was normal. Artificial crosses were made successfully between 31 accessions of leafy spurge. Seed germination of the F1 progeny slightly exceeded that reported for natural populations, and meiosis was normal. Pollen stability studies were carried out on herbarium material. Stainability was 100% for most of the samples studied. Extensive pollen size polymorphism was found. It is suggested that this phenomenon supports the hypothesis that E. esula is of allopolyploid origin. No cytological or cytogenetic basis was found for considering the leafy spurge accessions examined in this study as other than as a single, albeit somewhat polymorphic, species.
The distribution of Agrostis gigantea and Poa pratensis in relation to some environmental factors on a mine-tailings area at Copper Cliff, Ontario
Authors: McLaughlin B. E. , Crowder A. A.
Published: June 2017

The distribution of two dominant species of grass was related to selected soil characteristics on revegetated Cu–Ni tailings at Copper Cliff, Ont. The tailings area had a wet zone dominated by Agrostis gigantea, a dry zone dominated by Poa pratensis, and an overlapping zone of both grasses. In the overlapping zone the biomass–cover index of both species was lower than in their specific zones. pH ranged from 3.3 to 6.7, and sites of Poa pratensis were generally above pH 5. Tailings Fe, extractable by ammonium acetate, ranged from 5 to 344, Cu from 5 to 15, and Ni from 5 to 80 μg∙g−1. There were significant differences in Fe, Cu, and Ni between the Agrostis and Poa zones, and between Poa pratensis sites in the Poa and overlapping zones. Concentrations of metal in roots of Agrostis gigantea were 2.7 × 103–46.4 × 103, 216–1289, and 108–826 μg∙g−1 for Fe, Cu, and Ni, respectively; in Poa pratensis root concentrations of metal were 2.2 × 103–20.3 × 103, 100–1589, and 99–795 μg∙g−1 for Fe, Cu, and Ni, respectively. Significant differences in Fe and Cu in roots were found between the Agrostis and Poa zones, and within the overlapping zone. Nickel in roots differed significantly only in roots of Agrostis gigantea from the Agrostis and overlapping zones. Key words: Fe, Cu, Ni, roots; tailings; Agrostis gigantea, Poa pratensis; zonation.
Competition between native and immigrant Polygonum congeners
Authors: Collins B. , Wein G.R.
Published: June 2017

Coexistence of annual herbs Polygonum punctatum, a native, and Polygonum caespitosum, an immigrant, may result from (i) niche differentiation that reduces or avoids competition, (ii) competitive equivalence for shared resources, or (iii) interaction between a strong competitor and a species that tolerates competition. We investigated competitive interactions between the Polygonum congeners in a greenhouse experiment using plants grown from seed to seed set. Thinning profiles of monocultures were density dependent but did not differ between the species in monocultures. Biomass allocation to root, shoot, and racemes was not influenced by competition from conspecifics or congeners. Mature plant height and raceme production of both species were negatively affected by congener density; however, the species were not competitively equivalent. Polygonum caespitosum was suppressed into the shorter heights in mixture pots but produced more racemes at all but the greatest congener densities. Key words: competition, coexistence, annual herbs, immigrant.
Gradient analysis of old spruce – fir forests of the Great Smoky Mountains circa 1935
Authors: Busing R.T. , White P.S. , MacKenzie M.D.
Published: June 2017

The response of old-growth spruce – fir vegetation to environmental gradients was investigated using 1930s plot data from the Great Smoky Mountains. Gradients related to forest composition and position of the ecotone with the deciduous forest were identified using canonical correspondence analysis (CCA) and their role in vegetation response to climate change was considered. The data were subsequently stratified into three elevation classes and ordinated separately using CCA to identify gradients at various elevations. The effect of elevation on tree stratum composition and structure was profound. Secondary gradients influencing the tree stratum included slope aspect, potential solar radiation, and topographic position. Abies fraseri basal area and density were high above 1800 m elevation. Comparable basal area levels of Picea rubens were attained at elevations ranging from 1400 to 1900 m. Total stand basal area and density increased with elevation. The importance of topographic position increased with elevation, while that of slope aspect and potential solar radiation decreased. Presumably, the increasing incidence of cloud cover with elevation diminished the effect of slope aspect and potential solar radiation at higher elevations. The transition from deciduous forest occurred in the 1300 – 1600 m elevation range. A substantial proportion (24%) of plots had mixed composition (30 – 70% spruce – fir by basal area), suggesting that the ecotone is not abrupt in old-growth forest. Environmental variables other than elevation did not have a strong effect on ecotone position. Attempts to infer long-term ecotone dynamics along the elevation gradient based on species size-class data were inconclusive. Key words: Abies fraseri, gradient analysis, Great Smoky Mountains, old-growth forest, Picea rubens, spruce – fir forest.
Comparison between conidial development in Sporendocladia bactrospora and Phialocephala virens
Authors: Mouton Marnel , Wingfield Michael J.
Published: June 2017

Conidium development was studied and compared in Sporendocladia bactrospora (thought to resemble Chalara spp.) and in Phialocephala virens. Techniques used in the study include bright field and fluorescence microscopy, as well as scanning and transmission electron microscopy. Sporendocladia bactrospora had cylindrical conidia produced in true chains from phialidic conidiogenous cells with long cylindrical collarettes. An area of wall building activity at the base of the conidiogenous cell was characterized by secretory vesicles indicating ring wall building development. In Phialocephala virens, conidia were formed by apical wall building and distinct periclinal thickening was evident. From this study it was possible to confirm the fact that Phialocephala s.l. can clearly be divided into two distinct groups on the basis of conidium development. Key words: apical wall building, conidiogenesis, Phialocephala, ring wall building, Sporendocladia.
Staining of paraffin-embedded plant material in safranin and fast green without prior removal of the paraffin
Authors: Ma Yilun , Sawhney V.K. , Steeves T.A.
Published: June 2017

A rapid and efficient method for staining sections of paraffin-embedded plant tissues in safranin and fast green without prior removal of the paraffin is described. The quality of the resulting preparations is equal to, or better than, that obtained by conventional methods. This method results in substantial saving of time and expense. Key words: staining technique, paraffin, safranin, fast green.
Biotic interactions and the population dynamics of the long-lived columnar cactus Neobuxbaumia tetetzo in the Tehuacán Valley, Mexico
Authors: Godínez-Alvarez Héctor , Valiente-Banuet Alfonso , Banuet Leopoldo Valiente
Published: June 2017

The giant columnar cactus Neobuxbaumia tetetzo (Coulter) Backeberg is the dominant species of a vegetation type locally called "tetechera" that occupies ca. 400 km2 in the Tehuacán Valley. As a way to analyse the role of biotic interactions on the population dynamics of this species, we conducted an elasticity analysis, using matrix models elaborated from field data, to determine the finite rate of increase and the critical stages of the life cycle that were related to the biotic interactions occurring during these stages. Although the estimated finite rate of increase did not differ from unity there were significant differences between the actual and predicted size distributions. Elasticity analysis showed that survivorship was the most important life-history parameter to the finite rate of increase. Because survivorship depends on the presence of nurse plants, our results emphasise the importance of positive interactions on the population dynamics of long-lived columnar cacti.Key words: biotic interactions, Cactaceae, deserts, matrix models, population dynamics.
Pollen development in relation to phenological stages of inflorescence expansion inAmelanchier alnifolia(saskatoon), with a comparison with buds forced out of dormancy
Authors: Sumner Michael J , Remphrey William R , Martin Richard
Published: June 2017

A relationship was developed between phenological stages of inflorescence expansion and the internal development of pollen within the anther of Amelanchier alnifolia Nutt. flowers. The major microscopic events associated with microsporogenesis and microgametogenesis were correlated with seven stages of external inflorescence development in both natural buds and those forced from dormancy in different concentrations of gibberellin at various times of the year. In fall and early spring, it was found that gibberellin at a concentration of 2.5 mg/L forced buds to produce inflorescences that most resembled those from natural field populations. However, it was not possible to force flower buds to develop all the way to anthesis. Flower bud development stopped when the pollen was at the binucleate stage. Despite this limitation, the ability to force buds increases the time frame for the study of many aspects of the reproductive biology of A. alnifolia.Key words: microsporogenesis, microgametogenesis, gibberellin, GA, flowering.
Biomass and carbon pool of two bogs in the Experimental Lakes Area, northwestern Ontario
Authors: Dyck Barbara S , Shay Jennifer M
Published: June 2017

This study was undertaken to estimate the aboveground biomass and carbon pool of plant communities in two bogs: one to be experimentally flooded to simulate a hydroelectric reservoir and the other left unflooded as a reference. The biomass of trees, saplings, and tall shrubs was estimated using allometric regression equations, while that of tree and tall shrub seedlings, low shrubs, herbs, bryophytes, and litter was harvested from 0.25-m2 plots. The eight communities were open or treed in low to high densities with Picea mariana (Mill.) BSP. and sparse Larix laricina (Du Roi) K. Koch. Aboveground community biomass (excluding litter) ranged from 7189 ± 924 (mean ± SE) to 72 909 ± 20 627 kg·ha-1, and litter ranged from 1181 ± 548 to 7664 ± 2848 kg·ha-1. Mean carbon concentration in the plant material analyzed ranged from 430 to 540 mg C·g-1. Carbon concentration of leaves in woody species was higher than in branches and stems. Carbon pool estimates (excluding litter) for the communities ranged from 3140 ± 480 to 35 010 ± 8890 kg C·ha-1. Community carbon per unit area as a percentage of biomass per unit area ranged from 44 to 48%. The available carbon pool (including litter and excluding tree branches and stems) of communities in the experimental bog ranged from 6386 to 9907 kg C·ha-1. Low shrubs, dominated by Chamaedaphne calyculata (L.) Moench in wetter, more open communities and Ledum groenlandicum Oeder in drier, more densely treed communities, composed 34-53% of the available carbon pool. Litter was the largest contributor (33%) to the available carbon pool in the most densely treed community, and bryophytes (mostly Sphagnum angustifolium (C. Jens. ex Russ.) C. Jens. in Tolf and Sphagnum fallax (Klinggr.) Klinggr., 46%) in the sedge community. The available carbon pool in aboveground vegetation of the experimental bog was estimated to be 1.17 × 105 kg C, approximately 12% of the estimated carbon pool in the peat.Key words: biomass, bog, carbon, experimental reservoir.
Studies in the Alismataceae. X. Floral organogenesis in Luronium natans (L.) Raf.
Authors: Charlton W A
Published: June 2017

Floral organogenesis of Luronium natans (L.) Raf. occurs at first in an alternating trimerous pattern typical of Alismataceae, with the formation of three sepals, then three bulges, corresponding to the petal-stamen primordia described in some other Alismataceae, alternating with the sepals. A petal is initiated on each bulge and a pair of stamens is initiated either on it or close to it. After this, development no longer follows a trimerous plan. Six carpels are initiated in positions alternating with the six stamens, and further carpels may then arise above and between the first six. The carpels ultimately lie in a whorled arrangement if there are only six; if more, they may appear whorled or irregularly arranged. After the initiation of the stamen pairs, floral organ primordia appear simply to be positioned between pre-existing primordia as in other phyllotactic systems. It is suggested that the number of carpel primordia formed is probably determined by the size of primordia relative to the floral apex, and the extent of continued growth of the floral apex. Luronium reinforces the concept that a form of trimery is fundamental for the Alismataceae up to the formation of three stamen pairs and adds to the possibilities for variation after this point. It is suggested for the Alismataceae in general that, according to taxon, trimerous development may be terminated at any point after the initiation of the stamen pairs, and after this the primordia are positioned individually in relation to pre-existing primordia. The switch from stamen to carpel initiation is not necessarily correlated with these phyllotactic changes.
Breeding system in the cleistogamous species Centaurea melitensis (Asteraceae)
Authors: Porras Rafael , Muñoz Álvarez Jesús Miguel
Published: June 2017

Cleistogamy involves structural, developmental, and functional differences between the open (chasmogamous) and closed (cleistogamous) floral forms produced by a species. Functional differences relate to the breeding system: progeny is obtained partly by obligate selfing, cleistogamous flowers and, at least potentially, by outcrossing, chasmogamous flowers. This study addresses theoretical predictions about the breeding system in Centaurea melitensis L. Comparative analysis of cleistogamous and chasmogamous flower heads produced by this species was based on studies of the morphological features of floral capitula, fruit production, pollen/ovule ratio, pollinators, stigma receptivity, and pollen-tube growth in the absence of pollinators. As expected, cleistogamous heads displayed characteristics typical of an obligate selfing flower. However, two apparently contradictory trends were discerned in chasmogamous heads: (i) a very high selfing rate and own-pollen germination at a very early stage in floral ontogeny, both of which are characteristic of an autogamous breeding system, and (ii) pollinator presence, morphological characteristics, and pollen/ovule ratio consistent with a xenogamous breeding system. Further study is required to determine the outcrossing rate in these capitula.
Annual dormancy cycles in Lesquerella fendleri (Brassicaceae) seeds stored under both field and laboratory conditions
Authors: Hyatt Laura A , Evans Ann S , Baskin Carol C
Published: June 2017

Patterns of germination over time were investigated in a short-lived desert perennial species, Lesquerella fendleri (Gray) S. Wats. Field-collected seeds were either buried in the field in cloth bags or stored in a glass jar under laboratory conditions. Regular germination tests were conducted under a range of alternating temperatures (buried seeds) or under differing water regimes (laboratory-stored seeds). Testing revealed Lesquerella fendleri to have an annual dormancy-nondormancy cycle, which was manifest regardless of seed storage conditions, suggesting that cycles may be partially endogenously regulated. Increasing seed germinability in field-stored seeds (maximum of 30% in year 1 and 95% in year 2) leads to the formation of a seed bank for at least 1 year and enhances the possibility of spreading germination events through time. This allows parent plants to maximize fitness in randomly fluctuating environments. The existence of two seedling flushes in the field and single germinability peaks in growth chambers suggests that dormancy cycling may support the formation of a metapopulation with subpopulations which are, although physically intermingled, genetically distinct.
Suffusion susceptibility investigation by energy-based method and statistical analysis
Authors: Le Van Thao , Marot Didier , Rochim Abdul , Bendahmane Fateh , Nguyen Hong Hai
Published: June 2017

Internal erosion is one of the main causes of instabilities within hydraulic earth structures. Four internal erosion processes can be distinguished, and this study deals with the process of suffusion, which corresponds to the coupled processes of detachment–transport–filtration of the soil’s fine fraction between the coarse fraction. Because of the great length of earth structures and the heterogeneities of soils, it is very difficult to characterize the suffusion susceptibility of the different soils. Nevertheless, a statistical analysis can be performed to optimize the experimental campaign. By using a dedicated erodimeter, an experimental program was set up to study suffusion susceptibility of 31 specimens of nonplastic and low-plasticity soils. The suffusion susceptibility is determined by the erosion resistance index, which relates the total loss of mass with the total energy expended by the seepage flow. Fourteen physical parameters are selected, and a multi-variate statistical analysis leads to a correlation between the erosion resistance index and all these parameters. A statistical analysis is performed to identify the main parameters and to focus on those that can easily be measured on existing structures. By distinguishing gap-graded and widely graded soils, two correlations are proposed to estimate the erosion resistance index.
MicroRNA-101-2-5p targets the ApoB gene in the liver of chicken (Gallus Gallus)
Authors: Ma Zheng , Li Hong , Zheng Hang , Jiang Keren , Jia Lijuan , Yan Fengbin , Tian Yadong , Kang Xiangtao , Wang Yanbin , Liu Xiaojun
Published: June 2017

Apolipoprotein B (ApoB) is a major protein component of plasma lipoproteins. It is involved in many important biological processes such as lipid transportation, enzyme activity regulation, and receptor recognition. Extensive studies have shown that the expression of ApoB is regulated at multiple levels. However, the regulation of ApoB expression by microRNAs (miRNAs) still remains unknown. In the present study, identified are miRNAs that are predicted to interact with ApoB in chicken. The predicted relationship between the identified miRNAs and ApoB was verified through dual luciferase reporter assay in chicken DF1 cells, and the effect of miRNAs on ApoB expression was analyzed in chicken embryo hepatocytes stimulated by 17β-estradiol. The results show that miR-101-2-5p was predicted to interact with ApoB. Dual luciferase reporter assay together with the miR-101-2-5p mimics study demostrate that ApoB is the target of miR-101-2-5p, which suppresses the expression of ApoB through binding with the 3′UTR of ApoB. Our experiments suggest that miR-101-2-5p might be involved in lipid metabolism through binding to the 3′UTR of ApoB in the liver of egg-laying chickens.
Vacuum degeneracy in massive gravity: Multiplicity of fundamental scales
Authors: Arraut Ivan , Chelabi Kaddour
Published: June 2017

The presence of Nambu–Goldstone bosons introduce a natural degeneracy inside the vacuum solutions of the nonlinear formulations of massive gravity in the same spirit of the [Formula: see text]-models. When the gravitational effects are taken into account, and the observers are located at any distance with respect to the source, this degeneracy corresponds to a multiplicity (flow) of the fundamental scales of the theory. The different values of the fundamental scales are connected to each other through the broken generators of the theory.
SPUTTER-GROWN Sb-DOPED SILICON NANOCRYSTALS EMBEDDED IN SILICON-RICH CARBIDE FOR Si HETEROJUNCTION SOLAR CELLS
Authors: CHEN XIAOBO , TANG YU , HAO JIABO
Published: June 2017

Sb-doped silicon nanocrystals (Si–NCs) films were fabricated by magnetron co-sputtering combined with rapid-thermal annealing. The effects of Sb content on the structural and electrical properties of the films were studied. The dot size increased with the increasing Sb content, and could be correlated to the effect of Sb-induced crystallization. The variation in the concentration of Sb shows a significant impact on the film properties, where as doped with 0.8[Formula: see text]at.% of Sb exhibited major property improvements when compared with other films. By employing Sb-doped Si–NCs films as emitter layers, Si–NCs/monocrystalline silicon heterojunction solar cells were fabricated and the effect of the Sb doping concentration on the photovoltaic properties was studied. It is found that the doping level in the Si–NCs layer is a key factor in determining the short-circuit current density and power conversion efficiency (PCE). With an optimized doping concentration of 0.8[Formula: see text]at.% of Sb, a maximal PCE of 7.10% was obtained. This study indicates that the Sb-doped Si–NCs can be good candidates for all-silicon tandem solar cells.
Bioinspired Hydrogels to Engineer Cancer Microenvironments
Authors: Park Kyung Min , Lewis Daniel , Gerecht Sharon
Published: June 2017

Recent research has demonstrated that tumor microenvironments play pivotal roles in tumor development and metastasis through various physical, chemical, and biological factors, including extracellular matrix (ECM) composition, matrix remodeling, oxygen tension, pH, cytokines, and matrix stiffness. An emerging trend in cancer research involves the creation of engineered three-dimensional tumor models using bioinspired hydrogels that accurately recapitulate the native tumor microenvironment. With recent advances in materials engineering, many researchers are developing engineered tumor models, which are promising platforms for the study of cancer biology and for screening of therapeutic agents for better clinical outcomes. In this review, we discuss the development and use of polymeric hydrogel materials to engineer native tumor ECMs for cancer research, focusing on emerging technologies in cancer engineering that aim to accelerate clinical outcomes.
The proinflammatory cytokine tumor necrosis factor-α excites subfornical organ neurons
Authors: Simpson Nick J. , Ferguson Alastair V.
Published: June 2017

Tumor necrosis factor-α (TNF-α) is a proinflammatory cytokine implicated in cardiovascular and autonomic regulation via actions in the central nervous system. TNF-α−/− mice do not develop angiotensin II (ANG II)-induced hypertension, and administration of TNF-α into the bloodstream of rats increases blood pressure and sympathetic tone. Recent studies have shown that lesion of the subfornical organ (SFO) attenuates the hypertensive and autonomic effects of TNF-α, while direct administration of TNF-α into the SFO increases blood pressure, suggesting the SFO to be a key site for the actions of TNF-α. Therefore, we used patch-clamp techniques to examine both acute and long-term effects of TNF-α on the excitability of Sprague-Dawley rat SFO neurons. It was observed that acute bath application of TNF-α depolarized SFO neurons and subsequently increased action potential firing rate. Furthermore, the magnitude of depolarization and the proportion of depolarized SFO neurons were concentration dependent. Interestingly, following 24-h incubation with TNF-α, the basal firing rate of the SFO neurons was increased and the rheobase was decreased, suggesting that TNF-α elevates SFO neuron excitability. This effect was likely mediated by the transient sodium current, as TNF-α increased the magnitude of the current and lowered its threshold of activation. In contrast, TNF-α did not appear to modulate either the delayed rectifier potassium current or the transient potassium current. These data suggest that acute and long-term TNF-α exposure elevates SFO neuron activity, providing a basis for TNF-α hypertensive and sympathetic effects.

NEW & NOTEWORTHY Considerable recent evidence has suggested important links between inflammation and the pathological mechanisms underlying hypertension. The present study describes cellular mechanisms through which acute and long-term exposure of tumor necrosis factor-α (TNF-α) influences the activity of subfornical organ neurons by modulating the voltage-gated transient Na+ current. This provides critical new information regarding the specific pathological mechanisms through which inflammation and TNF-α in particular may result in the development of hypertension.
Multipass Turning Operation Process Optimization Using Hybrid Genetic Simulated Annealing Algorithm
Authors: Jabri Abdelouahhab , El Barkany Abdellah , El Khalfi Ahmed
Published: June 2017

For years, there has been increasing attention placed on the metal removal processes such as turning and milling operations; researchers from different areas focused on cutting conditions optimization. Cutting conditions optimization is a crucial step in Computer Aided Process Planning (CAPP); it aims to select optimal cutting parameters (such as cutting speed, feed rate, depth of cut, and number of passes) since these parameters affect production cost as well as production deadline. This paper deals with multipass turning operation optimization using a proposed Hybrid Genetic Simulated Annealing Algorithm (HSAGA). The SA-based local search is properly embedded into a GA search mechanism in order to move the GA away from being closed within local optima. The unit production cost is considered in this work as objective function to minimize under different practical and operational constraints. Taguchi method is then used to calibrate the parameters of proposed optimization approach. Finally, different results obtained by various optimization algorithms are compared to the obtained solution and the proposed hybrid evolutionary technique optimization has proved its effectiveness over other algorithms.
Effects of Tumor Necrosis Factor-α on Morphology and Mechanical Properties of HCT116 Human Colon Cancer Cells Investigated by Atomic Force Microscopy
Authors: Liu Huiqing , Wang Nan , Zhang Zhe , Wang Hongda , Du Jun , Tang Jilin
Published: June 2017

Chronic inflammation orchestrates the tumor microenvironment and is strongly associated with cancer. Tumor necrosis factor-α (TNFα) is involved in tumor invasion and metastasis by inducing epithelial to mesenchymal transition (EMT). This process is defined by the loss of epithelial characteristics and gain of mesenchymal traits. The mechanisms of TNFα-induced EMT in cancer cells have been well studied. However, mechanical properties have not yet been probed. In this work, atomic force microscopy (AFM) was applied to investigate the morphology and mechanical properties of EMT in HCT116 human colon cancer cells. A remarkable morphological change from cobblestone shape to spindle-like morphology was observed. In parallel, AFM images showed that the cellular cytoskeleton was rearranged from a cortical to a stress-fiber pattern. Moreover, cell stiffness measurements indicated that Young’s modulus of cells gradually reduced from 1 to 3 days with TNFα-treatment, but it has an apparent increase after 4 days of treatment compared with that for 3 days. Additionally, Young’s modulus of the cells treated with TNFα for 4 days is slightly larger than that for 1 or 2 days, but still less than that of the untreated cells. Our work contributes to a better understanding of colorectal cancer metastasis induced by inflammation.
Association between Hemoglobin Levels and Diabetic Peripheral Neuropathy in Patients with Type 2 Diabetes: A Cross-Sectional Study Using Electronic Health Records
Authors: Yang Jun , Yan Pi-jun , Wan Qin , Li Hua
Published: June 2017

Objective. To investigate the relationship between hemoglobin levels and diabetic peripheral neuropathy (DPN) in type 2 diabetes mellitus (T2DM).Methods. 1511 patients with T2DM were included in the study. DPN was diagnosed based on symptoms, signs, and laboratory tests. Hemoglobin was defined as both a continuous variable and a quartile category variable. We compared patient characteristics between the no diabetic peripheral neuropathy (NDPN) and DPN groups. Logistic regression was conducted to investigate the association of DPN with hemoglobin in all T2DM patients. Linear regression was also performed to investigate the impact of hemoglobin on the vibrating perception threshold (VPT).Results. Compared with the NDPN group, hemoglobin level in the DPN group was significantly lower (118.54 ± 16.91 versus 131.62 ± 18.32 g/L,P<0.01). The prevalence of DPN increased by 50.1% (95% CI: 42.2–57.0%;P<0.001) per standard deviation decrease in hemoglobin. Compared to the highest quartile of hemoglobin, the lower quartiles were associated with a significantly increased risk of DPN in the entire T2DM population (allP<0.01). A per unit decrease in hemoglobin leads to a 0.12 (95% CI: 0.07–0.168) unit increase in VPT after adjustment for possible confounders (P<0.001).Conclusions. Lower hemoglobin levels were associated with increased prevalence of DPN and higher VPT.
Lattice Dynamics of Gd1−xYxMn2O5 Investigated by Infrared Spectroscopy
Authors: Ahmad Javed , Mansoor Jawaria , Rehmani Mehr Khalid , Jamil M. Tufiq , Bukhari Syed Hamad
Published: June 2017

We present infrared (IR) reflectivity of Gd1-xYxMn2O5 with x = 0, 0.2, 0.4, 0.6, 0.8, and 1 in the frequency range 30–1000 cm−1. A total of 18 IR active phonons were observed for GdMn2O5 (x=0) and three additional phonons have been observed with increasing x, marking a total of 21 phonons in YMn2O5 (x=1). A systematic investigation was performed to map out the structural distortion through the lattice vibration and discuss the consequences of frequency shifts in phonon modes. In addition, we have calculated the real part of optical conductivity (σ1(ω)) which reflects the semiconducting nature of Gd1-xYxMn2O5.
Bone Marrow Mesenchymal Stem Cells Inhibit the Function of Dendritic Cells by Secreting Galectin-1
Authors: Zhang Yue , Ge Xia-hui , Guo Xue-Jun , Guan Si-bin , Li Xiao-ming , Gu Wen , Xu Wei-guo
Published: June 2017

This study aimed to investigate whether bone marrow-derived mesenchymal stem cells (BM-MSCs) can inhibit function of dendritic cells (DCs) by secreting Galectin-1 (Gal-1). BM-MSCs have been shown to inhibit the maturation and function of DCs, further inhibiting the activation and proliferation of T cells. However, the detailed mechanism remains unknown. In this current study, MSCs and DCs derived from mouse bone marrow were cocultured using Transwell culture plates under different in vitro conditions. The results showed that as the ratio of MSC to DC of the coculture system increased and the coculture time of the two cells prolonged, the concentrations of Gal-1, interleukin- (IL-) 10, and IL-12 in the supernatants were increased and the protein expression of Gal-1 on and within DCs was also enhanced. The phosphorylation of extracellular signal-regulated kinase (ERK) pathway in DCs was boosted, whereas p38 mitogen-activated protein kinase (MAPK) pathway phosphorylation was weakened. Meanwhile, the expression of costimulatory molecules on the surface of DCs was decreased, and the proliferative effect of DCs on allogeneic T cells was also decreased. Therefore, this present study indicated that Gal-1 secreted from MSCs upregulated expression of Gal-1 and stimulated formation of tolerance immunophenotype on DCs, where the underlying mechanism was the regulation of the MAPK signaling pathway in DCs, thereby inhibiting the function of DCs.
Effects of Hyperglycemia on Vascular Smooth Muscle Ca2+Signaling
Authors: El-Najjar Nahed , Kulkarni Rashmi P. , Nader Nancy , Hodeify Rawad , Machaca Khaled
Published: June 2017

Diabetes is a complex disease that is characterized with hyperglycemia, dyslipidemia, and insulin resistance. These pathologies are associated with significant cardiovascular implications that affect both the macro- and microvasculature. It is therefore important to understand the effects of various pathologies associated with diabetes on the vasculature. Here we directly test the effects of hyperglycemia on vascular smooth muscle (VSM) Ca2+signaling in an isolated in vitro system using the A7r5 rat aortic cell line as a model. We find that prolonged exposure of A7r5 cells to hyperglycemia (weeks) is associated with changes to Ca2+signaling, including most prominently an inhibition of the passive ER Ca2+leak and the sarcoplasmic reticulum Ca2+-ATPase (SERCA). To translate these findings to the in vivo condition, we used primary VSM cells from normal and diabetic subjects and find that only the inhibition of the ER Ca2+leaks replicates in cells from diabetic donors. These results show that prolonged hyperglycemia in isolation alters the Ca2+signaling machinery in VSM cells. However, these alterations are not readily translatable to the whole organism situation where alterations to the Ca2+signaling machinery are different.