bluuebunny/crossref_metadata_2025 huggingface dataset:
The theory of a trapped degenerate mode resonator
Authors: Burdess J. S. , Gallacher B. J. , Grigg H. T. , Hu Z. X. , Dale C. , Keegan N. , Hedley J. , Fu C. , Spoors J.
Published: June 2017

Resonance based biosensors are used in the detection of biological molecules for medical diagnostics. Sensing in a liquid environment is very desirable for this application, but presents a significant challenge for resonators based upon conventional technologies. In this paper, the major originality lies in the development and exposition of a fundamental theory enabling design of an original elastic resonant sensor whose modes are engineered to simultaneously possess three separate but complementary dynamical properties: namely, (1) in-plane displacement of the free interface whereby the SH waves are uncoupled from the SV and P waves; (2) intrinsic modal trapping; and finally, (3) cyclic symmetry and modal degeneracy. The modal trapping is due to the physical configuration of the resonator resulting in an imaginary wavenumber for one region of the resonator. The wave will be evanescent in this region and propagating elsewhere. The fundamental principles are elucidated, and analytical techniques are presented that facilitate the efficient design of this unique class of device.
Electron Transport Chain Is Biochemically Linked to Pilus Assembly Required for Polymicrobial Interactions and Biofilm Formation in the Gram-Positive Actinobacterium
Actinomyces oris
Authors: Sanchez Belkys C. , Chang Chungyu , Wu Chenggang , Tran Bryan , Ton-That Hung
Published: June 2017

The Gram-positive actinobacteria
Actinomyces
spp. are key colonizers in the development of oral biofilms due to the inherent ability of
Actinomyces
to adhere to receptor polysaccharides on the surface of oral streptococci and host cells. This receptor-dependent bacterial interaction, or coaggregation, requires a unique sortase-catalyzed pilus consisting of the pilus shaft FimA and the coaggregation factor CafA forming the pilus tip. While the essential role of the sortase machine SrtC2 in pilus assembly, biofilm formation, and coaggregation has been established, little is known about
trans
-acting factors contributing to these processes. We report here a large-scale Tn
5
transposon screen for mutants defective in
Actinomyces oris
coaggregation with
Streptococcus oralis
. We obtained 33 independent clones, 13 of which completely failed to aggregate with
S. oralis
, and the remainder of which exhibited a range of phenotypes from severely to weakly defective coaggregation. The former had Tn
5
insertions in
fimA
,
cafA
, or
srtC2
, as expected; the latter were mapped to genes coding for uncharacterized proteins and various
nuo
genes encoding the NADH dehydrogenase subunits. Electron microscopy and biochemical analyses of mutants with nonpolar deletions of
nuo
genes and
ubiE
, a menaquinone C-methyltransferase-encoding gene downstream of the
nuo
locus, confirmed the pilus and coaggregation defects. Both
nuoA
and
ubiE
mutants were defective in oxidation of MdbA, the major oxidoreductase required for oxidative folding of pilus proteins. Furthermore, supplementation of the
ubiE
mutant with exogenous menaquinone-4 rescued the cell growth and pilus defects. Altogether, we propose that the
A. oris
electron transport chain is biochemically linked to pilus assembly via oxidative protein folding.

IMPORTANCE
The Gram-positive actinobacterium
A. oris
expresses adhesive pili, or fimbriae, that are essential to biofilm formation and
Actinomyces
interactions with other bacteria, termed coaggregation. While the critical role of the conserved sortase machine in pilus assembly and the disulfide bond-forming catalyst MdbA in oxidative folding of pilins has been established, little is known about other
trans
-acting factors involved in these processes. Using a Tn
5
transposon screen for mutants defective in coaggregation with
Streptococcus oralis
, we found that genetic disruption of the NADH dehydrogenase and menaquinone biosynthesis detrimentally alters pilus assembly. Further biochemical characterizations determined that menaquinone is important for reactivation of MdbA. This study supports the notion that the electron transport chain is biochemically linked to pilus assembly in
A. oris
via oxidative folding of pilin precursors.
Did the suicide barrier work after all? Revisiting the Bloor Viaduct natural experiment and its impact on suicide rates in Toronto
Authors: Sinyor Mark , Schaffer Ayal , Redelmeier Donald A , Kiss Alex , Nishikawa Yasunori , Cheung Amy H , Levitt Anthony J , Pirkis Jane
Published: June 2017

Objective

This research aims to determine the long-term impact of the Bloor Street Viaduct suicide barrier on rates of suicide in Toronto and whether media reporting had any impact on suicide rates.

Design

Natural experiment.

Setting

City of Toronto, Canada; records at the chief coroner’s office of Ontario 1993–2003 (11 years before the barrier) and 2004–2014 (11 years after the barrier).

Participants

5403 people who died by suicide in the city of Toronto.

Main outcome measure

Changes in yearly rates of suicide by jumping at Bloor Street Viaduct, other bridges including nearest comparison bridge and walking distance bridges, and buildings, and by other means.

Results

Suicide rates at the Bloor Street Viaduct declined from 9.0 deaths/year before the barrier to 0.1 deaths/year after the barrier (incidence rate ratio (IRR) 0.005, 95% CI 0.0005 to 0.19, p=0.002). Suicide deaths from bridges in Toronto also declined significantly (IRR 0.53, 95% CI 0.40 to 0.71, p<0.0001). Media reports about suicide at the Bloor Street Viaduct were associated with an increase in suicide-by-jumping from bridges the following year.

Conclusions

The current study demonstrates that, over the long term, suicide-by-jumping declined in Toronto after the barrier with no associated increase in suicide by other means. That is, the barrier appears to have had its intended impact at preventing suicide despite a short-term rise in deaths at other bridges that was at least partially influenced by a media effect. Research examining barriers at other locations should interpret short-term results with caution.
A re-evaluation of North American Tephroseris and Sinosenecio (Asteraceae: Senecioneae) based on molecular and micromorphological data
Authors: Golden J L , Kim Y D , Bain J F
Published: June 2017

The recent transfer of the Queen Charlotte island endemic, Senecio newcombei Greene (Senecioneae: Asteraceae), to the Asiatic genus Sinosenecio extends the biogeographic range of Sinosenecio to North America and introduces a large amphi-Beringian gap in the distribution of the genus. However, the closely related genus Tephroseris includes a number of North American species with distributions in the vicinity of S. newcombei. We provide molecular sequence data from the ITS region of nuclear ribosomal DNA and micromorphological data from anther endothecial cells that indicate S. newcombei is closely related to North American Tephroseris species. However, the overall relationship between Sinosenecio and Tephroseris remains unresolved, so that transfer of S. newcombei to Tephroseris is not proposed.Key words: Tephroseris, Sinosenecio, phylogeny, ITS, anther endothecial cells.
Non-conspecificity ofCylindrocladium quinqueseptatumandCalonectria quinqueseptatabased on a β-tubulin gene phylogeny and morphology
Authors: Kang Ji-Chuan , Crous Pedro W , Old Kenneth M , Dudzinski Mark J
Published: June 2017

Cylindrocladium quinqueseptatum Boedijn & Reitsma was originally described from leaf spots of Hibiscus sabdariffa L. from Indonesia. This fungus infects many host plants in Southeast Asia and causes severe leaf blight disease of eucalypts. Calonectria quinqueseptata Figueiredo & Namek., which was described from leaf spots on Annona squamosa L. from Brazil, has been regarded as the teleomorph of Cy. quinqueseptatum. Based on morphology and on the phylogeny derived from the DNA sequence of a β-tubulin gene portion spanning several phylogenetically informative introns, the two respective ex-type cultures are shown to be distinct species. Furthermore, Calonectria reteaudii (Bugn.) C. Booth (anamorph Cy. reteaudii (Bugn.) Boesew.), which was described on Smithia bequaertii De Wild. from Vietnam, is shown to be morphologically identical to a comprehensive selection of isolates of Cy. quinqueseptatum from Southeast Asia, Australia, and Madagascar. As Cy. reteaudii represents an older name for Cy. quinqueseptatum, we suggest that the fungus causing widespread damage on eucalypts and other hosts in the above regions be referred to as Cy. reteaudii. Calonectria quinqueseptata should be retained for the fungus that thus far has been found only in Brazil.Key words: Cylindrocladium reteaudii, Eucalyptus, Hypocreales, phylogeny, systematics.
Plastid and seedling development in SAN-9789 [4-chloro-5-(methylamine)-2-(α,α,α-trifluoro-m-tolyl)-3-(2H)-pyridasinone]-treated etiolated bean seedlings
Authors: Pardo Anthony D. , Schiff Jerome A.
Published: June 2017

SAN 9789[4-chloro-5-(methylamine)-2-(α,α,α-trifluoro-m-tolyl)-3-(2H)-pyridasinone] inhibits carotenoid synthesis at the level of phytoene in Phaseolus vulgaris L. Although carotenoids are greatly reduced in the primary leaves, prolamellar bodies and thylakoid membranes are formed containing phototransformable protochlorophyll(ide). SAN 9789 also produces developmental effects similar to those of red light since seedlings treated in darkness are short, show plumular unhooking, formation of adventitious roots, expansion of primary leaves and full expansion of the first trifoliate leaf and first internode. The effect is not directly on phytochrome since far red light does not reverse the effect of SAN. If abscisic acid (ABA) is indeed formed from carotenoids, we may be observing the consequences of reduced levels of ABA leading to reduced ethylene production as occurs with red light. The first trifoliate leaf of SAN-treated plants contains practically no carotenoids (0.2%) compared with untreated 7-day-old, etiolated primary leaves yet shows normal development of etioplasts, prolamellar bodies, thylakoid membranes, and phototransformable protochlorophyll(ide). In Euglena, lack of carotenoids stops synthesis and assembly of other membrane components; in higher plants this type of regulation does not appear to operate.
Litter decomposition: measuring relative contributions of organic matter and nitrogen to forest soils
Authors: Aber John D. , Melillo Jerry M.
Published: June 2017

The relative contribution of different types of litter to the maintenance of soil organic matter and nitrogen levels cannot be determined from standard litter bag disappearance studies. By coupling measurements of weight loss with nitrogen dynamics and presenting results in a new format, estimates of both state of decay and percentage of material eventually transferred to lower soil horizons can be obtained.
Fungal parasites of rotifers: two new verticillate endoparasites with aerial conidiophores
Authors: Barron G. L.
Published: June 2017

Diheterospora rotiferorum and Diheterospora ovispora are described as new species endoparasitic on bdelloid rotifers belonging to Philodina and Adineta. In both species resting spores (aleuriospores) are produced underwater and disseminative spores (phialoconidia) are produced from aerial conidiophores. Verticillium reniformis and Acrostalagmus tagenophorus, also endoparasites of rotifers, are transferred to the genus Diheterospora.
Nematophagous fungi: a new Harposporium from soil
Authors: Barron G. L.
Published: June 2017

Harposporium arcuatum is described as a new endoparasitic nematode-destroying hyphomycete from soil. The conidia are long, very narrow, and semicircular in outline. Infection of the host is initiated by conidia germinating in the gut or lodging in the oesophagus. Resting spores were not found.
A new species of Kuehneola on Gymnosporia montana from India
Authors: Bagyanarayana G. , Rao K. Niranjan
Published: June 2017

Kuehneola ramacharii which parasitizes Gymnosporia montana (Wight & Am.) Benth. & Hook. f. is described as a new species. This is the first species of Kuehneola on members of the family Celastraceae. It is characterized by long teliospores with the number of cells in each teliospore being as high as 25 or more.
Influence of carbon supply on developmental kinetics of symbiotic and nonsymbiotic alfalfa cv. Algonquin through first flowering
Authors: Macdowall F. D. H.
Published: June 2017

Biphasic first-order growth kinetics of NO3-supported or symbiotic seedlings of Medicago sativa L. cv. Algonquin were followed over a range of light intensities and at two concentrations of CO2. The initial, [Formula: see text]-supported growth coefficients ([Formula: see text] or relative growth rate) decreased with decreasing light intensity, but those for symbiotic growth showed relief from high light inhibition by passing through a maximum [Formula: see text] at an intermediate light intensity. In low light intensity (60 μE∙m−2∙s−1) the low initial growth coefficient persisted to 40 days in Hoagland's solution, or for 58 days symbiotically at which time the corresponding biomass was reached. At high light intensity (550 μE∙m−2∙s−1) the initial values of [Formula: see text] were insensitive to the enrichment of CO2 (1325 μL∙L−1), but after 27 days values of [Formula: see text] were enhanced by the raised CO2 concentration. The initial growth phase, which is N limited at a high C supply, was followed by a phase of growth that was C limited at a high N supply. The symbiotic N supply, unlike the combined N supply, was dependent only on the C supply because when the CO2 concentration was raised the acceleration of symbiotic seedling growth equalled the maximum on [Formula: see text] nutrition. The results support a hypothesis that the change in kinetic phase is controlled by developmental morphogenesis independent of N source and C supply and that a plant pool of organic N metabolites plays a role in the regulation of the N metabolism that is involved in the growth effects.
Transamination, deamidation, and the utilisation of asparagine amino nitrogen in pea leaves
Authors: Ta Trung Chanh , Joy Kenneth W.
Published: June 2017

The fate of 15N from the amino group of labelled asparagine was followed in growing pea leaves, in the presence and absence of inhibitors of deamidation (DONV, 5-diazo-4-oxo-L-norvaline) and transamination (AOA, aminooxyacetate). The label was widely incorporated into various amino acids, especially aspartate, glutamate, alanine, and homoserine, as well as glycine and serine. Treatment with AOA considerably decreased the label of all these amino acids except aspartate, consistent with the production of the latter by deamidation of asparagine. This was confirmed by the use of DONV, which decreased aspartate labelling by over 70%; a similar decrease in glutamate labelling suggested that the latter was labelled predominantly by transamination of aspartate. In contrast, DONV had a much smaller effect on the labelling of alanine, homoserine, glycine, and serine, indicating a direct transfer of amino nitrogen from asparagine, rather than transfer from aspartate (or glutamate). The labelling of glycine and serine and the transfer of amino nitrogen to ammonia and glutamine (amide group) were consistent with a flow of asparagine nitrogen into the photorespiratory nitrogen cycle. During leaf expansion there was a decrease in the amount of asparagine metabolised, and a decreasing participation of deamidation as the leaf matured.
Penetration and infection of winter wheat leaves by Coprinus psychromorbidus under controlled environment conditions
Authors: Gaudet D. A. , Kokko E. G.
Published: June 2017

Infection and disease development by the snow mold pathogen Coprinus psychromorbidus Redhead & Traquair in winter wheat leaves in a controlled environment were studied by using light and scanning electron microscopy. Penetration of the leaf occurred exclusively through the stomata. Mycelial aggregates formed over stomata subsequent to penetration; proliferation of the mycelium to surrounding leaf tissues was restricted to the substomatal cavities until such an aggregate had formed. Spread of the pathogen within the leaf tissues coincided with collapse of cell walls and the disorganization and eventual loss of cell constituents. Pathogenesis appeared to be enzymatic in nature and near-total conversion of leaf tissues to fungal thallus was evident. Microsclerotium-like bodies (MSB) formed in epidermal cells as early as 3 weeks after inoculation with the pathogen. The hyphae of MSBs had a compact arrangement and dense cytoplasmic contents, but no definite pattern of organization was observed within the structure.
An aggressive vascular-inhabiting Phoma (Phoma tracheiphila f. sp. chrysanthemi nov. f. sp.) weakly pathogenic to chrysanthemum
Authors: Baker Kenneth F. , Davis Lily H. , Wilhelm Stephen , Snyder William C.
Published: June 2017

A form of Phoma tracheiphila (Petri) Kant. & Gik., newly designated as f. sp. chrysanthemi Baker et al., massively invades the phloem and xylem and to a lesser extent the cortex and pith of chrysanthemum plants but causes only slight injury in the first season. However, infected plants either produce weak shoots the following year or commonly fail to resume growth. Injury appears to result from depletion of photosynthates and nutrients rather than from vascular plugging or toxins. Infection occurs through intact roots or through wounds of roots or stems, and the pathogen spreads to the top of 120-cm stems in 3 months. Infection occurs readily from 10–29.4 but most abundantly at 10–21° C. Mycelial development in the stems is retarded at 10 and is optimal at 21° C. This Phoma decline disease was prevalent in commercial and home chrysanthemum plantings in California in 1948–1956, but it has since been controlled by the annual planting of healthy cuttings in fumigated soil, as practiced for control of verticillium wilt. In home gardens the disease may cause severe losses if plants are grown as perennials, but if healthy cuttings are planted annually, the disease will be minimal even in plants grown in infested soil. The pathogen is indistinguishable morphologically from Phoma tracheiphila f. sp. tracheiphila Baker et al., cause of "mal secco" of citrus, but will not infect sour orange or rough lemon plants.
Effets de faibles abaissements de température sur la différenciation de l'oosphère et sur les processus de fécondation chez le Marsilea vestita (Ptéridophytes)
Authors: Chenou Éliane , Kuligowski Janine , Ferrand Michèle
Published: June 2017

Male and female gametes of Marsilea vestita were subjected to weak cooling periods (24° C/16° C or 24° C/12° C) of 1–4 h during the ultimate stage of gametogenesis. Effects of these suboptimal temperatures were observed on the organization of the oosphere on fertilization, and further development of the embryos. The changes observed varied with cold intensity and were proportional to the exposure time. The last steps of archegonogenesis were delayed (16° C) or even totally inhibited (12° C). The female gamete structure generally exhibited the following changes: the fertilization cone was enlarged, the cytoplasm more or less vacuolated, and organelles redistributed towards peripheral regions. Furthermore, the presence of chromatic fragments within the cytoplasm (12° C) suggests that the last division of female gametogenesis was strongly affected. In these gametes, fertilization was always reduced. When it occurred, the treatment considerably slowed down the different stages, allowing a better understanding of the male nucleus reactions during its migration. The percentage of embryos able to grow decreased proportionally to the length of cold exposure (16° C). After exposure of the gametes to 12° C, most embryos did not survive.
Pollen morphology of Ligusticum (Apiaceae) in Canada
Authors: Hebda Richard J.
Published: June 2017

The pollen morphology of the four Canadian taxa of Ligusticum (L. calderi, L. canbyi, L. scothicum ssp. scothicum, and L. scothicum ssp. hultenii) was studied under the light microscope and compared with that of other Apiaceae common on the Pacific coast of British Columbia and adjacent Alaska. Ligusticum calderi and L. canbyi compose one pollen type with a subrhomboidal outline in equatorial view and a triangular outline in polar view with pores located at the apices of the amb. Endopores are X-, H-, or dumbbell-shaped. The L. scothicum type is rectangular in equatorial view and circular in polar view, with pores arranged on the circumference. Endopores are usually rectangular to oval. Ligusticum calderi pollen is larger and thus distinct from L. canbyi pollen. All other Apiaceae pollen types examined are distinct from the L. calderi type because their pores are positioned between the lobes of the amb and because of differences in other characters. Since L. calderi pollen is readily separated from other Apiaceae on the British Columbia coast, it can be used to study the history of this geographically restricted species and the possibly refugial species associated with it. The size differences between L. calderi and L. canbyi pollen suggest that they are distinct species.
Premières données sur l'activité photosynthétique de quelques algues subaériennes vivant en milieux très peu éclairés
Authors: Leclerc Jean-Claude
Published: June 2017

The photosynthetic activity of three sciaphilous algae (including two cavernicolous ones) was measured with a Clark electrode in the air, by light minus dark differences in the rates of [Formula: see text] under laboratory and near natural physical conditions. Photosynthesis versus light intensity curves showed a sharp slope at low light and a suddenly lower slope at medium intensities; this is interpretable as the Kok effect. This phenomenon is stronger with cavernicolous algae than with less sciaphilous plants. High yield activity of the three studied algae was observed only in the naturally encountered range of light intensity. A seasonal adaptation of light activity was shown but not a daily one.
Développement floral chez Eragrotis tef : dynamique des gamétophytogenèses
Authors: Longly B. , Rabau T. , Louant B. P.
Published: June 2017

A calendar of reproductive events is established in Eragrostis tef (Zucc.) Trotter, a sexual tetraploid Ethiopian cereal, using the microsporogenesis and microgametogenesis as reference scales to which the female gametophytogenesis is related. The absolute frequency is noted for each correlation brought out (microgametogenesis–megagametogenesis). The frequencies of all the female stages found at a same level of anther development are also specified. This preliminary work is done within the scope of an interspecific hybridization program which aims at transferring, to E. tef, genes responsible for the apomictic character present in the genus.
Reproductive schedule of Medicago lupulina (Leguminosae) in a patchy environment
Authors: Pavone L. V. , Reader R. J.
Published: June 2017

Reproductive schedules for cohorts of Medicago lupulina seedlings were compared in adjacent habitats, distinguished by the presence or absence of a ground cover of mosses. The objective of the study was to determine how the reproductive schedule of a single taxon changes in a patchy environment (i.e., where risk of death changes with habitat type). The mortality rate was higher where mosses were absent, probably because of increased drought stress. In both habitats some plants reproduced for the first time in their second growing season, but the percentage reproducing for the first time in their third or fourth growing season was greater at moss-covered sites (15%) than at moss-free sites (4%). Fewer plants reproduced either once or repeatedly in the moss-free habitat (10% once, 1% repeatedly) than in the moss-covered habitat (18% once, 7% repeatedly). However, the mean number of seeds produced per plant was greater at moss-free sites (0–93) than at moss-covered sites (0–27). These results indicate that the timing, frequency, and amount of reproduction will all change where a species experiences different microhabitats within a patchy environment.
Fructan in winter wheat, triticale, and fall rye cultivars of varying cold hardiness
Authors: Suzuki Michio , Nass H. G.
Published: June 2017

Eight winter wheat, one triticale, and three fall rye cultivars with mean lethal temperature (LT50) values from −5.5 to −20.0 °C were harvested in late November and analyzed for fructans. Fructose, sucrose, and oligofructans with a degree of polymerization (DP) of 6 or lower were found in all cultivars. The concentration of DP 4 fructan was higher than that of DP 5 in winter wheat and triticale, while the opposite trend was found in fall rye. Fructans with a DP of 7 or higher (high DP fructans) were found at high concentrations in hardy winter wheat and fall rye. The high DP fructan was very low or negligible in the least hardy winter wheat cultivar 'Super X'. Fructans in winter cereals consisted mainly of inulin type with a β-2-1 linkage. The activity of phlein sucrase, which catalyzes synthesis of phlein, was much lower in winter cereals compared with phlein-rich grasses. It was concluded that high DP fructans of inulin type in basal top tissues of winter cereals were more closely associated with freezing resistance than low DP fructans.
Developmental anatomy of the shoot apex of leptosporangiate ferns. II. Leaf ontogeny of Adiantum capillus-veneris (Adiantaceae)
Authors: Imaichi Ryoko
Published: June 2017

Early leaf development of Adiantum capillus-veneris L. was examined with special reference to the origin of constituent cells of the leaf. At the earliest stage of leaf development, an enlarged superficial cell (leaf initial cell) occurs in the fourth or fifth cell packet derived from the shoot apical cell and divides to form a leaf apical cell. At the same time, cells surrounding the enlarged cell, which are not derivatives of it, also divide to form the basal part of a leaf primordium. Unlike the situation in leaves of other ferns, the leaf apical cell does not divide actively during early development, while the basal cells divide frequently from the beginning. The major part of a fairly developed leaf primordium therefore consists of derivatives of the basal cells. The leaf primordium is multicellular in origin in the sense that its distal part is derived from the enlarged superficial cell and its basal part from the cells surrounding the enlarged superficial cell.
Effects of polyamines, polyamine precursors, and polyamine biosynthetic inhibitors on somatic embryogenesis from eggplant (Solarium melongena) cotyledons
Authors: Fobert Pierre R. , Webb David T.
Published: June 2017

Eggplant (Solarium melongena L.) cotyledons grown on Murashige and Skoog medium with naphthaleneacetic acid formed callus, roots, and somatic embryos. Low levels of naphthaleneacetic acid (0.1 – 0.5 mg L−1) favoored rhizogenesis, intermediate levels (1.0 – 5.0 mg L−1) favoured embryogenesis, and high levels (10 – 50 mg L−1) favoured callogenesis. Addition of polyamines or their precursors did not induce morphogenesis on medium containing no growth regulator, nor did it affect embryogenesis on medium containing naphthaleneacetic acid, except at the highest concentrations tested, which were inhibitory. Enzyme-activated inhibitors of putrescine synthesis significantly reduced embryogenesis and stimulated rhizogenesis. α-Difluoromethylornithine was more potent in inhibiting embryogenesis and stimulating rhizogenesis than was α-difluoromethylarginine. α-Difluoromethylarginine did not inhibit growth and α-difluoromethylornithine stimulated growth. Addition of putrescine with α-difluoromethylornithine restored embryogenesis to control levels and reduced rhizogenesis. Competitive inhibitors of polyamine synthesis had nonspecific effects. Compared with seedling cotyledons, expiants grown on 5.0 mg naphthaleneacetic acid per litre contained slightly less free soluble putrescine and about the same amount of spermidine. At day 8, free putrescine and spermidine levels were higher in explants grown on naphthaleneacetic acid than in those grown on medium containing no growth regulator. Addition of α-difluoromethylornithine greatly reduced the putrescine and spermidine titres of the explants. Application of putrescine with α-difluoromethylornithine dramatically increased putrescine titres but not spermidine titres. Although the results suggest a role for polyamines in eggplant somatic embryogenesis, they do not support the hypothesis that polyamines act as auxin- or cytokinin-like growth regulators or as second messengers for auxin in this system.
Action de la lumière blanche et de quelques radiations monochromatiques sur la morphogenèse in vitro du Linum usitatissimum
Authors: Zine Rokia , Chlyah Hassan , Chlyah Averil , Jacques Roger
Published: June 2017

Bud neoformation from hypocotyl segments of flax grown in vitro was stimulated when the quantity of light was increased up to about 57.6 J cm−2 d−1 after which it remained almost unchanged. The spectral dependence for four wavelengths chosen in the visible range was similar to maximal absorption of chlorophyll, with one peak in blue light and another in red light. Photosynthesis by the mother plants, before excision, as well as by the explants was necessary for optimal neoformation of buds in hypocotyl segments. However, photosynthesis by the explant seemed to be the most conducive to shoot morphogenesis. A sucrose supplement could only partially replace photosynthesis before or after explant culture. The addition of amino acids and vitamins or organic acids with sucrose did not replace photosynthetic activity of the explants. A treatment with 3-(3,4-dichlorophenyl)-1,1-dimethylurea strongly reduced shoot formation, whereas 3-amino-1,2,4-triazole had no inhibitory effect.
Modifications morphologiques de l'Épinette blanche soumise à la sédimentation éolienne en milieu dunaire, Québec subarctique
Authors: Filion Louise , Marin Pierre
Published: June 2017

The characteristic growth forms of white spruce (Picea glauca (Moench) Voss) were studied within a dune located north of Whapmagoostui (Subarctic Québec). Thirty-two trees (14 living and 18 dead) were excavated and their morphology and ring patterns are described. Adventitious root development at the base of buried stems and spindle-like trunks (diameter smaller at collar than at higher levels) were the most important morphological modifications in response to slow sedimentation rates (close to 5 – 6 cm/year), as long as total sedimentation did not exceed a depth of approximately 1.25 m. The decrease in radial growth with depth was most likely due to low temperatures caused by long-lasting snow lenses within the niveoeolian sediment during the growing season. Tree dieback occurred when the sedimentation rate rose to 8 cm/year. The combined weight of sand and buried snow caused severe mechanical damage to the trees (e.g. branch and stem breakage). Life expectancy of tall trees was about 50 years under such high stress conditions. The dune moves towards the north at a rate of 0.74 m/year. The mean sedimentation rate is 7.65 cm/year. These values are similar to those found in coastal dunes in Finland. The ultimate fate of these trees is death through dune displacement.
Quantitative genetic variation and natural selection in Cleome serrulata growing along a mild soil moisture gradient
Authors: Farris Michael A.
Published: June 2017

The purpose of this study was to determine the potential for evolutionary change for several growth characters in a natural population of the annual plant Cleome serrulata Pursh by measuring directional selection pressures and quantitative genetic variation. The population grew along a mild soil moisture gradient, which allowed changes in selection pressures along the environmental gradient to be assessed. Directional selection pressures were calculated for initial height, height growth rate, initial leaf number, and leaf production rate for the wet and dry halves of the population separately. Narrow-sense heritabilities and genetic correlation estimates for these four variables, along with seed mass and emergence time, were estimated in the greenhouse from the offspring of controlled crosses. Selection pressures varied among phenotypic characters for different fitness components and subpopulations. Viability selection on the four characters was similar in the wet and dry subpopulations, with faster height growth rates being favored. Fecundity selection on all four characters was quite different in the wet and dry subpopulations. Overall, there was significant net positive selection on height characters in the dry subpopulation and on leaf number characters in the wet subpopulation. Height characters had lower heritabilities than leaf number characters but showed stronger maternal effects. Initial size measures showed negative genetic correlations with growth rates. The results suggested that these morphological characters had a greater impact on fitness in wetter areas, while physiological characters were more important in the drier areas.
The Eremomycetaceae (Ascomycotina)
Authors: Malloch David , Sigler Lynne
Published: June 2017

The Eremomycetaceae is shown to contain three species: Eremomyces bilateralis Malloch & Cain, Rhexothecium globosum Samson & Mouchacca, and Pithoascus langeronii von Arx, which is treated as a new combination in Eremomyces. The family is characterized by members having pseudoparenchymatous ascomatal initials, cleistothecia, clavate to ovoid evanescent asci, and one-celled hyaline to pale brown ascospores. Two of the three species have Arthrographis-like or Trichosporiella-like anamorphs. The pseudoparenchymatous ascomatal initials characteristic of this family strongly suggest that it should be included in the class Loculoascomycetes.
Aspen and pine leaf litter decomposition in laboratory microcosms. I. Linear versus exponential models of decay
Authors: Taylor Barry R. , Parkinson Dennis
Published: June 2017

Leaf litter of trembling aspen (Populus tremuloides Michx.) and lodgepole–jack pine (Pinus contorta Loud, × P. banksiana Lamb.) was decomposed in laboratory microcosms at 2, 10, 18, or 26 °C and three watering rates (15, 30, or 60 mL∙week−1) for 16 weeks. Aspen litter lost 5.0–37.3% of original mass, and pine litter lost 7.8–14.9%. Decay curves fit a sample linear model equally as well as the negative exponential model regardless of temperature or moisture conditions or species of litter. A general explanation of circumstances promoting apparently linear mass loss from decaying plant litter is derived from these data, a survey of the literature, and the assumption that all decay curves are ultimately curvilinear. Mass loss rates are expected to appear linear from slowly decaying substrates such as bole wood or when decay of rapidly decomposing substrates is not followed past the inflection point of the curve. Climatic variables that favour decomposer activity are hypothesized to increase the concavity of decay curves, while adverse conditions do the opposite.
Sydowia semenospora sp.nov. and its anamorph on amabilis fir
Authors: Funk A. , Finck K. E.
Published: June 2017

Sydowia semenospora sp.nov. (anamorph: Sclerophoma semenospora Funk) is described from amabilis fir (Abies amabilis (Dougl.) Forbes) on Vancouver Island, B.C., Canada.
The effect of mechanical impedance on ethylene production by maize roots
Authors: Whalen Maureen C.
Published: June 2017

The role of ethylene in mediating the response of primary roots of Zea mays cv. Merit to experimentally imposed mechanical impedance was examined. Root elongation was stimulated during the first 100 min of impedance. Within 300 min, impedance inhibited ethylene evolution while simultaneously stimulating 1-aminocyclopropane-1-carboxylic acid production. The root cap is not necessary for the observed impedance-mediated inhibition in ethylene, and ethylene evolution was not stimulated by excising root caps. Ethylene synthesis in roots is normally controlled by the production of 1-aminocyclopropane-1-carboxylic acid.
Leptoxyphium : Pycnide ou synnéma?
Authors: Roquebert Marie-France , Bury Edith
Published: June 2017

Structural and developmental analysis of Leptoxyphium sp. conidiomata shows that these consist of aggregated hyphae that develop a conidiogenous cavity near the apex. They have both pycnidial and synnematal characters. This lack of specific differences between synnemata and pycnidia emphasizes the artificial character of the previously established distinction between Coelomycètes and Hyphomycetes.
A morphological comparison of Scirpus acutus and S. validus in southern Manitoba
Authors: Shay Jennifer M. , Macaulay A. J. , Frego K. A.
Published: June 2017

Sixty stands of Scirpus acutus Muhl. and S. validus Vahl from five areas in southern Manitoba were examined to determine (i) whether the two were morphologically distinguishable within the region studied and, if so, (ii) which morphological characters were the most useful to separate them. Thirteen characters were measured on pressed and living specimens. From these, six bimodally distributed characters were objectively selected to calculate a biometric index for each specimen. Mean indices for 56 stands were separable into two groups, indicating that they contained pure populations of one taxon. Three stands had mixed populations, and one contained morphologically intermediate individuals. The two taxa can be consistently identified using a combination of six characters. Scirpus acutus has an inflorescence < 47 mm long, less than seven primary rays, no secondary rays, clusters of more than five spikelets, aerenchymal lacunae < 0.9 mm in diameter, and dark green culms in fresh specimens. In contrast, S. validus has inflorescences > 80 mm long, more than 13 primary rays, secondary, tertiary, and occasionally quaternary rays present, spikelets generally in clusters of one to three, aerenchymal lacunae > 1.5 mm in diameter, and light green culms in fresh specimens. Data from Manitoba populations support their status as separate species.
An example of an included gynoecium in Dicranostigma (Papaveraceae)
Authors: Bokenfohr Sheila M. , Cass David D.
Published: June 2017

Our study of gynoecial morphology in Dicranostigma included a single case of a small, ovule-bearing gynoecium within the large, external two-carpellate gynoecium. The large external gyneocium has parietal placentation without intrusions, many ovules, an open style, and a two-lobed stigma. The internal gynoecium is unicarpellate, has abnormal stigma lobing and maturation, smaller ovules, and a dense covering of trichomes on its placenta. The internal gynoecium is continuous with the central portion of the receptacle. This is a rare event, which probably resulted from prolonged activity of the floral apex.
Molecular relationships in subtribe Brassicinae (Cruciferae, tribe Brassiceae)
Authors: Warwick S.I. , Black L.D.
Published: June 2017

Restriction-site variation for 17 endonucleases was compared in the large single-copy region of the chloroplast genome in 74 taxa of the genera Brassica, Coincya, Diplotaxis, Eruca, Erucastrwn, Hirschfeldia, Raphanus, Sinapidendron, Sinapis, and Trachystoma (subtribe Brassicinae, tribe Brassiceae, Cruciferae). A total of 422 restriction-site mutations was observed, with 228 (54%) showing variation among taxa. Phylogenetic analyses indicated a clear division of the subtribe into two main lineages designated here as Rapa–Oleracea and Nigra. Polyphyly was evident in five genera (Brassica, Diplotaxis, Erucastrum, Sinapis, and Trachystoma) as indicated by their placement in both lineages and (or) further separation into groups within a lineage. The genera Coincya, Hirschfeldia, and Sinapidendron were monophyletic within the Nigra lineage, as were Eruca and Raphanus in the Rapa–Oleracea lineage. Four major groups were recognized within each lineage. The lowest levels of chloroplast DNA divergence were observed among taxa belonging to the same cytodeme or crossing group and were highest for Brassica rapa and Brassica oleracea versus Brassica nigra at 2.10–3.91% and 2.00–3.78%, respectively. The chloroplast DNA data were incongruent with traditional taxonomic circumscription of 5 of the 10 genera but concordant with other data sets that support the close genetic relatedness of all 10 genera. Key words: Brassica, Coincya, Erucastrum, Sinapidendron, Trachystoma, chloroplast DNA restriction-site variation.
A new Ophiostoma species associated with bark beetles infesting Norway spruce
Authors: Kirschner R , Oberwinkler F
Published: June 2017

During a survey of fungi associated with bark beetles in Germany, an undescribed species of Ophiostoma was isolated that differs from the other species of the genus by having pigmented, aseptate, convergent ostiolar hyphae, cucullate, sheathed ascospores, and a Hyalorhinocladiella anamorph. The species is described as Ophiostoma neglectum Kirschner & Oberwinkler. It is rarely associated with primary bark beetles but often associated with secondary bark beetles mainly infesting Norway spruce.Key words: Ophiostoma neglectum, Hyalorhinocladiella, secondary bark beetles, Picea abies, Pinus sylvestris, conidial development.
Comparison of mitochondrial and cytosolic tRNA nucleotidyltransferases fromTriticum aestivum
Authors: Vicaretti Raffaela , Joyce Paul BM
Published: June 2017

Here we report the partial purification and characterization of wheat mitochondrial ATP (CTP):tRNA nucleotidyltransferase (EC 2.7.7.25). Our purification scheme involves ammonium sulfate fractionation and chromatography on anion-exchange, hydroxyapatite, and affinity columns. Our results indicate that the enzyme is stable over a broad range of temperatures with highest activity at 37°C. High activity is seen at alkaline pH with a maximum at pH 9. The enzyme exhibits maximal activity in the presence of 10 mM MgCl2and is inhibited by (at least) 100 mM NaCl. We also show that a second form of this enzyme exists in the wheat cytosolic fraction. This enzyme shares many features with the mitochondrial enzyme but differs from the mitochondrial enzyme in its elution profile from hydroxyapatite and in its response to manganese.Key words: tRNA nucleotidyltransferase, wheat, mitochondria.
Allongement et morphologie de pousses annuelles issues de greffe chez le noyer commun, Juglans regia L. cv. Lara (Juglandaceae)
Authors: Sabatier Sylvie , Barthélémy Daniel , Ducousso Isabelle , Germain Eric
Published: June 2017

Extension growth, number of internodes of the main stem, and sylleptic branches were recorded weekly during the 1994 growing season on 1-year-old Juglans regia L. cv. Lara scions. Date of sylleptic branch production and branch position on the main stem were also recorded. Two main stem types were distinguished according to their growth pattern: continuous or rhythmic over one growing season. Three sylleptic branch types were distinguished in relation with their growth pattern and morphology: (i) long shoots elongated in two growth flushes that showed a zone of short internodes above the first internode or hypopodium, (ii) long shoots elongated in one flush only with long internodes above the hypopodium, and (iii) short shoots corresponding with the elongated hypopodium only. Each type of sylleptic shoot is generally produced at a different growth period. Main stems developed sylleptic branches when their growth rate was higher than 17 cm/week. On the median part of the main stem, sylleptic long shoots were distributed according to a basipetal gradient of increasing vigour (extension duration, length, and number of internodes). Sylleptic short shoots were generally localized above long shoots.
Isoetes ×echtuckerii, hyb. nov., a new triploid quillwort from northeastern North America
Authors: Brunton Daniel F , Britton Donald M
Published: June 2017

A new interspecific Isoetes hybrid, I. echinospora Dur. × I. tuckermanii A. Br., is described from northeastern North America by means of cytology and the scanning electron microscopy of spores. Isoetes ×echtuckerii D.F. Brunton and D.M. Britton, hyb. nov., is the name proposed for this taxon. It is triploid, produces only aborted, sterile spores and has spore ornamentation intermediate between that of its putative parents. Populations have been identified in eastern Canada and the adjacent United States of America growing in association with one or both parents in shallow, fresh water along oligotrophic lake and river shores. Key words: Isoetes ×echtuckerii, interspecific hybrid, Canada, United States of America.
Study of rotational bands and electromagnetic properties of odd mass 153−159Eu
Authors: Pandit Rakesh K. , Slathia Barun , Devi Rani , Khosa S. K.
Published: June 2017

Some positive and negative parity energy bands of odd-A isotopes of Europium [Formula: see text] have been studied within the Projected Shell Model (PSM) framework. Calculated excitation energy spectra, transition energies, E2 and M1 transition probabilities, quadrupole and magnetic moments are compared with experimental data wherever available. Reasonably good agreement is obtained with the observed data.
Periapical Status and Quality of Root Canal Fillings in a Moroccan Subpopulation
Authors: El Merini Hafsa , Amarir Hind , Lamzawaq Amine , Hamza Mouna
Published: June 2017

Aim. The aim of the study was to assess the prevalence of apical periodontitis (AP) and quality of root canal fillings in an adult Moroccan subpopulation. Methods. In the study 508 patients were included, attending the Conservative Dentistry Clinic at the Faculty of Dentistry of Casablanca. 508 panoramic and 709 periapical radiographs were observed. The periapical status of all teeth (with the exception of third molars) was examined according to Ørstavik’s periapical index. The statistical analysis was performed with the software Epi Info Version 6.04dfr, April 2001. Results. A total of 12719 teeth were examined. 45.3% of patients had apical periodontitis. 4.2% of teeth were treated endodontically and 70.4% of these treatments were inadequate. 91,5% with inadequate endodontic treatment presented apical periodontitis, while only 8,2% with adequate endodontic treatment had apical periodontitis. The lower molars and the upper premolars were the most affected teeth. The presence of apical periodontitis was correlated significantly with insufficient root canal fillings (p<0.05). Conclusions. The present study found a high prevalence of apical periodontitis in this Moroccan population. Inadequate root canal fillings were associated with an increased prevalence of apical periodontitis.
MicroRNAs and Autophagy: Fine Players in the Control of Chondrocyte Homeostatic Activities in Osteoarthritis
Authors: D’Adamo Stefania , Cetrullo Silvia , Minguzzi Manuela , Silvestri Ylenia , Borzì Rosa Maria , Flamigni Flavio
Published: June 2017

Osteoarthritis (OA) is a debilitating degenerative disease of the articular cartilage with a multifactorial etiology. Aging, the main risk factor for OA development, is associated with a systemic oxidative and inflammatory phenotype. Autophagy is a central housekeeping system that plays an antiaging role by supporting the clearance of senescence‐associated alterations of macromolecules and organelles. Autophagy deficiency has been related to OA pathogenesis because of the accumulation of cellular defects in chondrocytes. Microribonucleic acids (microRNAs or miRs) are a well‐established class of posttranscriptional modulators belonging to the family of noncoding RNAs that have been identified as key players in the regulation of cellular processes, such as autophagy, by targeting their own cognate mRNAs. Here, we present a state‐of‐the‐art literature review on the role of miRs and autophagy in the scenario of OA pathogenesis. In addition, a comprehensive survey has been performed on the functional connections of the miR network and the autophagy pathway in OA by using “microRNA,” “autophagy,” and “osteoarthritis” as key words. Discussion of available evidence sheds light on some aspects that need further investigation in order to reach a more comprehensive view of the potential of this topic in OA.