bluuebunny/crossref_metadata_2025 huggingface dataset:
Functions of orexins in peripheral tissues
Authors: Heinonen M. V. , Purhonen A. K. , Mäkelä K. A. , Herzig K. H.
Published: February 2008

Orexin A (OXA) and orexin B were originally isolated as hypothalamic peptides regulating sleep, wakefulness and feeding. However, growing evidence suggests that orexins have major functions also in the peripheral tissues. Central orexigenic pathways originating from medulla activate the hypothalamus–pituitary axis and can influence the sympathetic tone. Orexins and their receptors are widely dispersed throughout the intestine, where orexin receptors are regulated by the nutritional status, affect insulin secretion and intestinal motility. Although the primary source of the peptide has not been elucidated, OXA is detected in plasma and its level varies in response to the metabolic state. In this review, we focus on the current knowledge on peripheral functions of orexins and discuss possible endocrine, paracrine and neurocrine roles.
The impact of adenotonsillectomy on children’s quality of life
Authors: Schwentner I. , Schmutzhard J. , Schwentner C. , Abraham I. , Höfer S. , Sprinzl G.M.
Published: February 2008

Objectives:  Although adenotonsillectomy is one of the most frequently performed surgical procedures in the pediatric population, there is little known about its impact on Health‐related Quality of Life (HRQL). The aim of this study was to measure children’s HRQL‐benefit after adenotonsillectomy.

Design and setting:  The study was carried out as a retrospective postal survey utilising a proxy rating.

Participants:  In total, 447 parents of children who underwent adenotonsillectomy for the indication of chronic tonsillitis were included. 43% (n = 191) of the parents returned completed surveys.

Main outcome measures:  To quantify the benefit after pediatric adenotonsillectomy the Glasgow Children’s Benefit Inventory (GCBI) was used.

Results:  Mean GCBI‐total score was 21 ± 19 (−8 to 77), showing an improvement in all GCBIsubscales.

Conclusions:  Adenotonsillectomy is a highly effective approach to treat children with tonsil disease. It has a positive impact on children’s HRQL and other areas not directly associated with their tonsil disease. Moreover, this improvement in HRQL is durable and not temporary.
Long‐term categorical auditory performance and speech intelligibility in Mandarin‐speaking prelingually deaf children with early cochlear implantation in Taiwan
Authors: Wu C.‐M. , Sun Y.‐S. , Liu T.‐C.
Published: February 2008

Keypoints

• We evaluated the long‐term development of categorical auditory performance and speech intelligibility rating of Mandarin‐speaking prelingually deaf children within 5 years after early cochlear implantation.

• The categorical auditory performance increased after cochlear implantation, the median categorical auditory performance after 1 year of implantation was 4 and became 7 three years after implantation. The median categorical auditory performance remained to be 7 till 5 years after implantation.

• There was significant difference in categorical auditory performance category between ‘before implantation’ and ‘1 year after implantation’, also between ‘1 year after implantation’ and ‘3 years after implantation’. But no significant difference was found between 3 years and 5 years after implantation.

• The median speech intelligibility rating before implantation was 1. After 2 years of implantation, the median speech intelligibility rating became 4. Significant difference was found between these two time points. Three years after implantation, the median speech intelligibility rating improved to 5 and maintained at that level till 5 years after implantation.

• Eighty‐one per cent (17/21) of our subjects reached the maximal category (7) of categorical auditory performance 5 years after implantation. Eighty‐one percent (17/21) of our subjects achieved the highest category (5) of speech intelligibility rating 5 years after implantation.
Endoscopic transsphenoidal surgery for cholesterol granulomas involving the petrous apex
Authors: Georgalas C. , Kania R. , Guichard J.‐P. , Sauvaget E. , Tran Ba Huy P. , Herman P.
Published: February 2008

Key points

• Surgery for cholesterol granulomas involving the petrous apex has traditionally been performed via a lateral skull base approach.

• We present a case‐series of four cholesterol granulomas treated through the endoscopic–transsphenoid approach over the last 10 years.

• Drainage was successful and symptomatic improvement was obtained in all cases (follow‐up 6 months–10 years).

• Primary ‘sphenoid’ lesions, which can be widely drained and remain marsupialised, should be differentiated from primary ‘petrous’ lesions that can be removed safely through the sphenoid sinus only in case of extension medial to the internal carotid artery (ICA).

• We feel that the endoscopic transsphenoidal approach is a safe and effective way to access cholesterol granulomas of the petrous apex.
A preliminary study of simple voice assessment in a routine clinical setting to predict vocal cord paralysis after thyroid or parathyroid surgery
Authors: Hanna B.C. , Brooker D.S.
Published: February 2008

Objective:  To determine if a simple assessment of vocal cord function performed in a routine clinical setting can predict vocal cord paralysis on laryngoscopy in patients following thyroid or parathyroid surgery.

Method:  Prospective observational cohort study of patients undergoing thyroid or parathyroid surgery. Vocal cord function was assessed in terms of an abnormality of voice or cough reported by the patient or detected by the examiner. Laryngoscopy was performed by indirect mirror examination or fibreoptic nasopharyngolaryngoscopy. Examiners included otolaryngology consultants, registrars, senior house officers and a general practioner with a special interest in otolaryngology. The patient was often examined by a different clinician before and after surgery.

Results:  Eighty‐six patients participated in the study between August 2003 and July 2004. Eleven had a change in their voice postoperatively and one patient had difficulty coughing. Six of these patients had a vocal cord paralysis. A further five apparently asymptomatic patients had a vocal cord paralysis. The positive predictive value of voice assessment for vocal cord paralysis was 55%.

Conclusion:  In a routine clinical setting where the assessment of vocal cord function is often reported by different clinicians of varying experience at each patient attendance, the assessment of a patient’s voice following thyroid or parathyroid surgery is not adequately predictive of vocal cord paralysis on indirect laryngoscopy or fibreoptic nasopharyngolaryngoscopy. Further study is required to determine reasons for this.
Evaluation of clinician‐operated sonography and fine‐needle aspiration in the assessment of salivary gland tumours
Authors: Kraft M. , Lang F. , Mihaescu A. , Wolfensberger M.
Published: February 2008

Objectives:  To evaluate the combination of ultrasound (US) + fine‐needle aspiration (FNA) in the assessment of salivary gland tumours in the hands of the otolaryngologist.

Design:  A retrospective review of case notes was performed.

Setting:  Two university teaching hospitals in Switzerland.

Participants:  One hundred and three patients with a total of 106 focal masses of the salivary glands were included. Clinician‐operated US + FNA were the first line of investigation for these lesions. All patients underwent surgical excision of the lesion, which allowed for confirmation of diagnosis by histopathology in 104 lesions and by laboratory testing in two lesions.

Main outcome measures:  Primary – diagnostic accuracy in identifying true salivary gland neoplasms and detecting malignancy. Secondary – predicting an approximate and specific diagnosis in these tumours.

Results:  The combination of US + FNA achieved a diagnostic accuracy of 99% in identifying and differentiating true salivary gland neoplasms from tumour‐like lesions. In detecting malignancy, this combination permitted an accuracy of 98%. An approximate diagnosis was possible in 89%, and a specific diagnosis in 69% of our patients.

Conclusions:  Due to economic factors and a high diagnostic accuracy, the combination of US + FNA represents the investigation method of choice for most salivary gland tumours. We suggest that the otolaryngologist be employed in carrying out these procedures, as is already the rule in other medical specialties, while computed tomography and magnetic resonance imaging should be reserved to those few lesions, which cannot be delineated completely by sonography.
Stripping in the New Millennium: Thinking about Trends in Exotic Dance and Dancers’ Lives
Authors: Bradley Mindy S.
Published: February 2008

With the increasing presence of sex and sexuality in American popular culture, the stripping industry is undoubtedly undergoing important subcultural and organizational transition. What are the implications of these changes for the individuals involved? The current paper reviews much of the literature on exotic dance to consider the potential transformations in the organization of the sex industry and how these changes may impact the lives of those involved. Specifically, I note some key differences in the literature that suggest how exotic dance has shifted. I then pose some questions for empirical inquiry. I argue that transformations in the exotic industry are creating new opportunities and challenges for women, and may be particularly deleterious for poor and minority women. I call for sociologists to investigate the consequences of organizational transferal in sexual labor, reevaluate the dynamics of agency and exploitation, and consider the potential differential impact of these trends on poor women and women of color.
Rapid natural selection for resistance to an introduced parasite of rainbow trout
Authors: Miller Mark P. , Vincent E. Richard
Published: February 2008

Introduced species and infectious diseases both independently pose challenges for the preservation of existing biodiversity. However, native species or disease hosts are by no means ‘unarmed’ when faced with novel environmental challenges, provided that adequate adaptive genetic variation exists to mount effective evolutionary responses. In this study, we examined the consequences of the recently introduced parasite and causative agent of whirling disease (Myxobolus cerebralis) in a wild rainbow trout (Oncorhynchus mykiss) population from Harrison Lake, Montana (USA). Consistent with the parasite’s age‐specific effects, juvenile rainbow trout recruitment into Harrison Lake was substantially reduced following parasite detection in 1995. However, experimental data suggest that natural selection has rapidly reduced whirling disease susceptibility within the population over time. The rapid observed temporal change in resistance patterns argues that the standing genetic variation for parasite resistance facilitated this process. Our findings ultimately underscore the importance of preserving genetic diversity to ensure that species of economic importance or of conservation concern have maximal chances for persistence in future changing environments.
An eigenvalue problem for the biharmonic operator on ℤ2‐symmetric regions
Authors: Pereira Antônio L. , Pereira Marcone C.
Published: February 2008

In this work we show that the eigenvalues of the Dirichlet problem for the biharmonic operator are generically simple in the set of ℤ2‐symmetric regions of ℝn, n⩾2, with a suitable topology. To accomplish this, we combine Baire's lemma, a generalised version of the transversality theorem, due to Henry [Perturbation of the boundary in boundary value problems of PDEs, London Mathematical Society Lecture Note Series 318 (Cambridge University Press, 2005)], and the method of rapidly oscillating functions developed in [A. L. Pereira and M. C. Pereira, Mat. Contemp. 27 (2004) 225–241].
Finite Element Simulation of Orthogonal Metal Cutting
Authors: Shih A. J.
Published: February 2008

The development and implementation of a plane-strain finite element method for the simulation of orthogonal metal cutting with continuous chip formation are presented. Detailed work-material modeling, including the effects of elasticity, viscoplasticity, temperature, large strain, and high strain-rate, is used to simulate the material deformation during the cutting process. The unbalanced force reduction method and sticking-sliding friction behavior are implemented to analyze the cutting process. The deformation of the finite element mesh and comparisons of residual stress distributions with X-ray diffraction measurements are presented. Simulation results along the primary and secondary deformation zones and under the cut surface, e.g., the normal and shear stresses, temperature, strain-rate, etc., are presented revealing insight into the metal cutting process.
The Dynamics of Closed-Die Forging With Mechanical Presses
Authors: Scrutton R. F. , Marasco A.
Published: February 2008

The kinetic energies of the crank mechanism and anvil and flash material are considered in order to develop a relation between forging load and the velocity of the upper die. Theoretical results are compared with published data. The dynamics of flash formation are also considered. When a larger flywheel is used, forging loads may be calculated in terms of the changes in energy of the flywheel. Hence, the ratio of press capacity to forging load is an important factor in the mechanics of forging.
Recursive Calibration of Industrial Manipulators by Adaptive Filtering
Authors: Yao Y. L. , Wu S. M.
Published: February 2008

The calibration scheme of robot forward kinematics presented in this paper has a number of features. Firstly, robot kinematic errors are modeled in a recursive format and as such, the number of measurements that need to be taken for calibration can be determined by studying the rate of convergence of estimation error covariance. Secondly, a simplified adaptive filtering algorithm is used to deal with unknown measurement noise statistics and unknown robot motion repeatability characteristics in estimating the kinematic errors. Thirdly, a laser interferometry system is used to measure positions of a robot end-effector in world coordinates. The measurement system was implemented in experiments involving a three degree-of-freedom gantry robot. The adaptive filtering of the experimental data identified 0.5 to 1.5 percent errors in representative kinematic parameters of the given robot by taking into account measurement noise and robot repeatability.
Magnetar-Like Emission from the Young Pulsar in Kes 75
Authors: Gavriil F. P. , Gonzalez M. E. , Gotthelf E. V. , Kaspi V. M. , Livingstone M. A. , Woods P. M.
Published: February 2008

We report the detection of magnetar-like x-ray bursts from the young pulsar PSR J1846–0258, at the center of the supernova remnant Kes 75. This pulsar, long thought to be exclusively rotation-powered, has an inferred surface dipolar magnetic field of 4.9 × 10
13
gauss, which is higher than those of the vast majority of rotation-powered pulsars, but lower than those of the approximately 12 previously identified magnetars. The bursts were accompanied by a sudden flux increase and an unprecedented change in timing behavior. These phenomena lower the magnetic and rotational thresholds associated with magnetar-like behavior and suggest that in neutron stars there exists a continuum of magnetic activity that increases with inferred magnetic field strength.
Energy Gaps and Kohn Anomalies in Elemental Superconductors
Authors: Aynajian P. , Keller T. , Boeri L. , Shapiro S. M. , Habicht K. , Keimer B.
Published: February 2008

The momentum and temperature dependence of the lifetimes of acoustic phonons in the elemental superconductors lead and niobium were determined by resonant spin-echo spectroscopy with neutrons. In both elements, the superconducting energy gap extracted from these measurements was found to converge with sharp anomalies originating from Fermi-surface nesting (Kohn anomalies) at low temperatures. The results indicate electron many-body correlations beyond the standard theoretical framework for conventional superconductivity. A possible mechanism is the interplay between superconductivity and spin- or charge-density-wave fluctuations, which may induce dynamical nesting of the Fermi surface.
Video-Rate Far-Field Optical Nanoscopy Dissects Synaptic Vesicle Movement
Authors: Westphal Volker , Rizzoli Silvio O. , Lauterbach Marcel A. , Kamin Dirk , Jahn Reinhard , Hell Stefan W.
Published: February 2008

We present video-rate (28 frames per second) far-field optical imaging with a focal spot size of 62 nanometers in living cells. Fluorescently labeled synaptic vesicles inside the axons of cultured neurons were recorded with stimulated emission depletion (STED) microscopy in a 2.5-micrometer by 1.8-micrometer field of view. By reducing the cross-sectional area of the focal spot by about a factor of 18 below the diffraction limit (260 nanometers), STED allowed us to map and describe the vesicle mobility within the highly confined space of synaptic boutons. Although restricted within boutons, the vesicle movement was substantially faster in nonbouton areas, consistent with the observation that a sizable vesicle pool continuously transits through the axons. Our study demonstrates the emerging ability of optical microscopy to investigate intracellular physiological processes on the nanoscale in real time.
Detection of New
arr-4
and
arr-5
Gene Cassettes in Clinical
Pseudomonas aeruginosa
and
Klebsiella pneumoniae
Strains from Brazil
Authors: Fonseca Érica Lourenço da , Freitas Fernanda dos Santos , Amorim José Carlos de , Vicente Ana Carolina Paulo
Published: February 2008

New
arr
alleles emerged in class 1 integrons from a clinical
Pseudomonas aeruginosa
strain (
arr-4
) and four
Klebsiella pneumoniae
strains (
arr-5
) in Brazil/American continent.
arr-4
was preceded by
aacA7
-
catB3
, whereas
arr-5
was the unique cassette. The putative proteins shared 75% (Arr-5) and 78% (Arr-4) identities with Arr-2.
Effect of Polysorbate 80 on Oritavancin Binding to Plastic Surfaces: Implications for Susceptibility Testing
Authors: Arhin Francis F. , Sarmiento Ingrid , Belley Adam , McKay Geoffrey A. , Draghi Deborah C. , Grover Parveen , Sahm Daniel F. , Parr Thomas R. , Moeck Gregory
Published: February 2008

Oritavancin, a semisynthetic lipoglycopeptide with activity against gram-positive bacteria, has multiple mechanisms of action, including the inhibition of cell wall synthesis and the perturbation of the membrane potential. Approved guidelines for broth microdilution MIC assays with dalbavancin, another lipoglycopeptide, require inclusion of 0.002% polysorbate 80. To investigate the potential impact of polysorbate 80 on oritavancin susceptibility assays, we quantified the recovery of [
14
C]oritavancin from susceptibility assay plates with and without polysorbate 80 and examined the effect of the presence of polysorbate 80 on the oritavancin MICs for 301 clinical isolates from the genera
Staphylococcus
,
Enterococcus
, and
Streptococcus
. In the absence of polysorbate 80, [
14
C]oritavancin was rapidly lost from solution in susceptibility assay test plates: 9% of the input drug was recovered in broth at 1 h when [
14
C]oritavancin was tested at 1 μg/ml. Furthermore, proportionately greater losses were observed at lower oritavancin concentrations, suggesting saturable binding of oritavancin to surfaces. The inclusion of 0.002% polysorbate 80 or 2% lysed horse blood permitted the recovery of 80 to 100% [
14
C]oritavancin at 24 h for all drug concentrations tested. Concordantly, oritavancin MIC
90
s for streptococcal isolates, as determined in medium containing 2% lysed horse blood, were identical with and without polysorbate 80. In stark contrast, polysorbate 80 reduced the oritavancin MIC
90
s by 16- to 32-fold for clinical isolates of enterococci and staphylococci, which are typically cultured without blood. The results presented here provide evidence that the MIC data for oritavancin in the current literature significantly underestimate the potency of oritavancin in vitro. Moreover, the combination of data from MIC and [
14
C]oritavancin recovery studies supports the revision of the oritavancin broth microdilution method to include polysorbate 80 throughout the assay.
Activation et prolifération des cellules du mégagamétophyte de Taxus cultivé in vitro
Authors: Rohr René
Published: February 2008

The female gametophyte of Taxus was excised at the mature seed stage and was successfully grown in vitro without the embryo. The gametophyte tissue, which had large lipid reserves when placed into culture, showed cell dedifferentiation. In about 6% of cultures, unorganized, crumbly outgrowths were produced. After 2 months, a slow-growing, undifferentiated tissue was isolated. It contained some isolated tracheids, and, in most cells, a rough photosynthetic apparatus was apparent. [Journal translation]
Modifications électrophorétiques des protéines solubles foliaires de Suaeda maritima var. macrocarpa, Atriplex hortensis et Phaseolus vulgaris en relation avec la teneur en NaCl du milieu de culture
Authors: Billard J. P. , Binet P. , Boucaud J.
Published: February 2008

The study of the growth and metabolism of young plants grown in the presence of salt enables their classification according to their increasing sensitiveness to NaCl: Suaeda maritima (L.) Dum. var. macrocarpa Moq., Atriplex hortensis L. and Phaseolus vulgaris L. The influence of salinity on the evolution of soluble leaf proteins was compared in the three plants grown on culturing solutions more or less rich in salt. Examination of electrophoregrams emphasizes the qualitative stability of the protein macromolecules. The protenome of the obligate halophyte Suaeda maritima var. macrocarpa is characterised by its richness in high molecular weight proteins. With Atriplex hortensis, a salt-resistant plant, accumulating Na+ in its aerial organs, the salt induces a progressive increase of the synthesis of a high molecular weight proteinaceous fraction. In contrast, Phaseolus vulgaris, a plant very sensitive to NaCl, does not transport Na+ into the tissues analyzed. In this species the salt does not induce a detectable change in the soluble proteins. The increased synthesis or the preservation of the high molecular weight proteins in the resistant or halophilic plants could reflect an adaptation mechanism to hypersaline conditions.
Hymenostylium recurvirostrum var. insigne and Barbula amplexifolia in British Columbia, Canada
Authors: Zander Richard H. , Eckel P. M.
Published: February 2008

Hymenostylium recurvirostrum var. insigne (Dix.) Bartr. is reported new to the New World from British Columbia. Hymenostylium recurvirostrum var. cylindricum (Bartr.) Zander is a new combination. A key to the varieties of H. recurvirostrum is given. Barbula amplexifolia (Mitt.) Jaeg. is reported new to British Columbia.
First-year survival of Tsuga heterophylla without mycorrhizae and subsequent ectomycorrhizal development on decaying logs and mineral soil
Authors: Christy E. Jennifer , Sollins Phillip , Trappe James M.
Published: February 2008

Roots of western hemlock (Tsuga heterophylla) seedlings 1–5+ years old that had established naturally on logs in three states of decay or on mineral soil were compared for numbers and kinds of ectomycorrhizae. Mycobionts colonizing root systems included Cenococcum geophilum Fr., Piloderma croceum (Bres.) Erikss. & Hjorts., and four unidentified fungi distinguished by color and morphology. About half the seedlings surviving the first growing season (2–7 months) were nonmycorrhizal. Nonmycorrhizal seedlings were most frequent on the least decayed logs. However, mycotrophy appeared to be advantageous to hemlock; 1st-year mycorrhizal seedlings had shoots 60% longer and roots 47% longer than 1st-year nonmycorrhizal seedlings. All 2nd-year and older seedlings were mycorrhizal. The ability of western hemlock to survive the first growing season without mycorrhizae may contribute to its success in colonizing decaying logs, which may contain microsites devoid of effective ectomycorrhizal inocula.
Antheridiogen activity of Anemia mexicana
Authors: Nester J. E. , Schedlbauer M. D.
Published: February 2008

Gametophytes of two populations of Anemia mexicana Klotzsch exhibited antheridiogen activity. All gametophytes grown as monospore cultures produced organized meristems and only archegonia, although spore size and days from sowing until germination, meristem organization, and archegonia formation varied. In multispore cultures, gametophytes were either antheridiate or archegoniate, indicating that gametophyte interactions are necessary for antheridia formation. When old media extracts from multispore cultures of A. mexicana gametophytes were incorporated into new media, precocious antheridia were formed by A. mexicana and Lygodium japonicum but not by A. phyllitidis, Pteridium aquilinum, or Ceratopteris thalictroides. Few antheridia were initiated by A. mexicana gametophytes under red light, suggesting that antheridiogen could not completely overcome a block to antheridium formation. Spores of A. mexicana, A. phyllitidis, and L. japonicum, but not P. aquilinum and C. thalictroides, germinated in the dark in response to old media extracts incorporated into the basal medium. Thus, antheridiogen activity of A. mexicana is limited to schizaeaceous species of ferns.
Adaptation for herbicide tolerance in populations of Avena fatua
Authors: Jana S. , Naylor J. M.
Published: February 2008

A study was conducted to determine whether recurrent treatment of wild oat populations with triallate results in increased tolerance of this herbicide. Among several parameters of seedling growth investigated, percentage emergence, seedling survival, and length of the first leaf were found to be most useful in assessing response to this compound. The results revealed a substantial within-population variability for tolerance. Evidence is presented that recurrent herbicide treatment of wild oat populations by the methods commonly used in the control of this weed species in western Canada results in increased tolerance of triallate.
Anthocyanin polymorphisms in Mimulus guttatus
Authors: Griffiths A. J. F. , Carey Ken , Ganders Fred R.
Published: February 2008

Three anthocyanin polymorphisms in Mimulus guttatus DC. have been described and analysed genetically. These involved leaf blotches, calyx dots, and general deposition of anthocyanin. In the case of leaf blotches two plants with sharply contrasting leaf blotches were analysed and it was shown that the blotch phenotype in each is due to the same gene, probably the dominant gene identified in a previous study, here called L. (The difference between the plants must be ascribed to other complex genetic modifiers.) The presence or absence of calyx dots was shown to be due to a pair of alleles, C (presence) and c (absence). The presence or absence of general anthocyanin deposition in the stems petioles and calyces is controlled by the alleles A (presence) and a (absence). Whereas the expression of L is less in warm conditions, the expression of A is enhanced by exposure to the sun.
Absorption de sodium, calcium et potassium lors d'interactions ioniques au cours de la phase de germination de Raphanus sativus
Authors: Guerrier Gilles
Published: February 2008

Na+–K+ and Na+–Ca2+ interactions are measured by mineral analysis of germinating plantlets of radish (Raphanus sativus L.) in nutritive solutions enriched in these three elements. With high concentrations of CaCl2, more than 2.5 mM, the absorption of sodium is stimulated especially when there is a high percentage of this element in the external solution. On the other hand, KCl brings about a decrease in the sodium content in the hypocotyl, cotyledons and root; no one organ is affected. Only the uptake of sodium is modified not its transport, which is always proportional to the quantity absorbed. The absorption of calcium and potassium does not evolve in proportion to their external amounts, and the inhibition of accumulation of these elements by sodium is not dependent on the concentration of NaCl. The uptake of calcium is more inhibited than that of potassium which varies with the quantities of KCl and NaCl in the germination medium. Thus, potassium inhibits the uptake of sodium more than sodium inhibits that of potassium. However, whereas the absorption of sodium is only slightly modified by calcium, the absorption of calcium depends highly on the concentration of sodium.
Effects of temperature on leaf growth in corn (Zea mays)
Authors: Thiagarajah M. R. , Hunt L. A.
Published: February 2008

Effects of temperature on certain leaf-growth characteristics are described for corn (Zea mays L.) hybrid A498 × CG10 grown at 62 nE cm−2 s−1 irradiance (400–700 nm). The rate of leaf expansion declined from a maximum at the earliest measurement stage to zero sometime after the ligule was exserted. The number of visible leaves with actively growing laminae at any stage of ontogeny was constant over day/night temperatures of 15/10, 25/20, 30/25, and 35/30 °C, but increased from three to six between the appearance of the 7th and 13th leaves. Rate of leaf appearance was increased by temperature, from 0.19 leaves per day at 15/10 °C to 0.58 leaves per day at 30/25 °C. However, rate of leaf appearance only increased to 0.60 leaves per day at 35/30 °C. Areas of successive leaves increased to 842 cm−2 at (optimal) 25/20 °C and 772 cm−2 at 30/25 °C for leaf 11, and then decreased to leaf 15. Specific leaf weight (lamina weight/lamina area) increased throughout ontogeny and decreased with increasing temperature.
Genetic control of β-amylase isozymes in common or hexaploid wheat (Triticum aestivum)
Authors: Joudrier P. , Gobin G.
Published: February 2008

Examination of seeds of parents and F1 and F2 hybrids of the crosses 'Vilmorin 23' × '61.5.3.2.' and 'Fournil' × 'Yaktana' and the reciprocal crosses showed that the C1, C2, and C3 components of the β-amylase zymogram, determined by polyacrylamide slab electrophoresis are each controlled by a pair of alleles. From the results of the second cross 'Fournil' × 'Yaktana,' a linkage study between these genes was undertaken. From previous work, we know that components C1 are located on chromosome 4 Aβ and C3 on chromosome 4 DL. We conclude that genes for C1 and C2 components are tightly linked on the same chromosome (4 Aβ).
Spatial pattern, floral sex ratios, and fecundity in dioecious Aralia nudicaulis (Araliaceae)
Authors: Barrett Spencer C. H. , Thomson James D.
Published: February 2008

Aralia nudicaulis L. (Araliaceae) is a perennial understory herb of the boreal forest which forms large clones by means of an extensive subterranean rhizome system. Populations are dioecious and pollinated primarily by bumble bees. To examine the relationships between the spatial pattern of sexual morphs and female fecundity, all flowering ramets were mapped in a 1-ha block of spruce–fir forest in central New Brunswick and the fecundity of females determined. Within the block, A. nudicaulis exhibited a 2.5:1 sex ratio of male/female flowering ramets. Ramets of the sexual morphs were negatively associated owing to cloning and a reduced likelihood of flowering in female ramets under dense canopy compared with males. Pattern analysis of the sex ratio of flowering ramets revealed a monotonic decline in variance with block size indicating that samples of sex ratio using small quadrats are likely to give misleading estimates for this species. The fecundity of females exhibited no systematic positional variation within the forest block. In most cases fecundity was not correlated with male and female flowering density, ramet sex ratio, and several subjectively estimated habitat variables. It is proposed that the long flight distances of pollinators, pollen carry-over, and the predominance of male flowers at the site interact to dampen out spatial effects on fecundity.
A comparative study of spore germination of some Isoetes species of northeastern North America
Authors: Kott L. S. , Britton D. M.
Published: February 2008

Germination of megaspores and microspores of five Isoetes species is described. Under laboratory conditions spore samples were subjected to cold, cool, and warm temperatures for 12 weeks to establish the role of these conditions on the subsequent percent germination and the rate of germination. It was found that taxa with higher chromosome numbers (decaploid, I. macrospora; tetraploids, I. tuckermanii and I. riparia) showed higher overall megaspore germination in the 70-day test period, for both cold and control samples. Microspore samples under the same temperature regimes had higher overall germination amongst tetraploid species. Results also showed that I. macrospora and I. tuckermanii megaspores germinated without a cold pretreatment, while I. acadiensis, I. riparia, and I. echinospora required a cold period to germinate. Microspore samples of I. echinospora (diploid) did not need to be treated with cold to germinate but the rate and final percent of germination was greatly increased if the spores were subjected to cold first. Isoetes riparia microspores required a cold period for germination while those of I. tuckermanii and I. macrospora did not. The cold period served to delay germination of microspores of both of these species during the cold period and also for some days afterwards. The germination data on both types of spores in these laboratory conditions showed interesting time correlations of behaviour between the microspores and megaspores of each species.
A taxonomic survey of the gasteroid, auricularioid Heterobasidiomycetes
Authors: Oberwinkler F. , Bandoni R. J.
Published: February 2008

Morphology and taxonomy of the gasteroid, auricularioid heterobasidiomycetous fungi are discussed, as are relationships to other Heterobasidiomycetes. A new order, the Atractiellales, and three families, Hoehnelomycetaceae, Chionosphaeraceae fam. nov., and Phleogenaceae are recognized. Five genera are disposed within these families as follows: Agaricostilbum and Atractiella, Hoehnelomycetaceae; Stilbum and Chionosphaera, Chionosphaeraceae; Phleogena, Phleogenaceae. A genus of uncertain disposition, Pachnocybe is also discussed. New combinations proposed are Agaricostilbum hyphaenes (Har. & Pat.) Oberw. & Bandoni comb. nov. (= Pilacre hyphaenes Har. & Pat.); Atractiella delectans (Möller) Oberw. & Bandoni comb. nov. (= Pilacrelladelectans Möller); Atractiella solani (Cohn & Schroeter) Oberw. & Bandoni comb. nov. (= Pilacrella solani (Cohn & Schroet.)
Variability in spikelet disarticulation in Agropyron species
Authors: Sharma H. C. , Gill B. S.
Published: February 2008

Thirty-six Agropyron species were divided into six shattering groups based on the pattern of spikelet disarticulation at maturity. Species containing S, SH, SY, J, or JX genomes had the same shattering pattern and were put in shattering group 1. Spikelet disarticulation patterns of shattering groups 3, 4, and 5 were found to be distributed in C, E, and Ju genomes, respectively. In general, shattering pattens were consistent with genetic groups and classification based on genomic affinities.
Biogeography of lodgepole pine
Authors: Wheeler Nicholas C. , Guries Raymond P.
Published: February 2008

Lodgepole pine has been a component of the western North America flora throughout recent geological history although its present widespread distribution may be a relatively recent phenomenon (Late Pleistocene). The differentiation of populations within and between subspecies, and the distribution of rare alleles, both suggest that at the time of maximal Wisconsin glacial advance lodgepole pine was restricted to a number of refugia in the western United States, the islands along the north Pacific coast, and in an unglaciated region of the west-central Yukon. Subsequent to glacial retreat, lodgepole pine migrated to its present range with northern and southern interior populations meeting in northern British Columbia, possibly within the last 4000 years.
Seed banks in five boreal forest stands originating between 1810 and 1963
Authors: Granström Anders
Published: February 2008

The viable seed content of soil samples from five coniferous forest stands in northern Sweden, aged 16–169 years, was determined by means of germination trials. The soil samples were separated into five fractions: three organic horizons and two mineral soil horizons. Seedlings of 15 phanerogam species emerged, representing densities of 239–763 seeds/m2 in the soils from the different stands. The depth distributions of the seeds varied with both plant species and forest stand. Most seeds were found at various depths in the humus layer, but in one stand an appreciable seed density of Luzula pilosa was present in the mineral soil. Most of the seedlings belonged to plant species present in the vegetation or with good means of dispersal. The depth distribution data, however, suggest that Luzula pilosa in particular may have a persistent seed bank. The role of persistent seeds in the vegetational composition of the boreal forest is discussed.
Branching patterns in Trichomanes and Cardiomanes (hymenophyllaceous ferns)
Authors: Hébant-Mauri R.
Published: February 2008

Previous observations on Trichomanes with thick stems and axillary buds are compared with those recently obtained from species with slender stems and extraaxillary buds and also from Cardiomanes. In all species, leaves arise from typical two-sided apical cells and buds are initiated adjacent to them in cauline tissues, laterally on the apical meristem. Three different localizations of buds occur (axillary, extraaxillary, and intermediate) and result in different orientations of the whole lateral system (= leaf + bud). Each different arrangement is visible as early as the initiation stage. The leaf apical cell faces the bud initials in all cases. Growth does not interfere with relative orientation of the organs but greatly changes the vertical position of the buds, which may be borne on the stem near leaf insertion or at the leaf base. These results illustrate the necessity of accurate observation of the ontogenetic origin of lateral organs to define them.
Stomatal control of water use efficiency in poplar clones and hybrids
Authors: Blake T. J. , Tschaplinski T. J. , Eastham A.
Published: February 2008

Water use efficiency (WUE, the ratio of dry matter produced to water used in transpiration) was studied in 17 poplar clones and hybrids. Although WUE could not be predicted from the poplar group alone, water efficiency was found to vary in different poplar genotypes. For example, a balsam poplar, Populus maximowiczii M-4 (section Tacamahaca), and a white poplar clone, P. alba A-499 (section Leuce), had twice the dry matter production per unit of water transpired compared with another clone of P. maximowiczii (M-13) and a Cottonwood clone, P. nigra N-80 (section Aegeiros), which showed low WUE. The reduced transpiration in water-efficient clones per unit of dry matter produced was associated with a higher stomatal resistance on the abaxial leaf surface. However, the physiological and morphological basis of WUE varied in different clones. Water-efficient clones exhibited one or more of the following adaptations restricting water loss: (i) conspicuous cuticular ledges or hairs above the pore openings of stomata, (ii) earlier partial stomatal opening in the morning, and (iii) smaller stomata and a lower stomatal frequency on the adaxial surface of the upper leaves. Poplar clones of low WUE exhibited less stomatal control of transpiration as a result of lower stomatal resistances and they lacked the above adaptations. Relative ranking of genotypes could not be predicted from either dry matter productivity or transpiration rate alone although the most water efficient clones generally exhibited lower transpiration rates compared with less efficient clones.
Expansion récente du mélèze à la limite des forêts (Québec nordique)
Authors: Morin Alain , Payette Serge
Published: February 2008

The contact between tamarack stands and tundra sites, located at the forest limit and at the tree line (Leaf River, Northern Québec), represents colonization ecotones where tree populations react to climatic change. At the forest limit, the ecotones are about 20 m wide and are supporting most of the young tamarack populations established from nearby forest seed bearers. Tamarack seedlings and saplings established mostly on moss carpets between 1940 and 1970 during the recent climatic warming. At the altitudinal and the latitudinal tree lines, seedling establishment was rather unimportant, considering the very low tamarack density and the absence of black spruce seedlings. The recent climatic warming had probably influenced the consolidation of preexisting tree populations more than the position of the tree line.
Niche diversification of Sphagnum relative to environmental factors in northern Minnesota peatlands
Authors: Vitt Dale H. , Slack Nancy G.
Published: February 2008

The peatlands sampled in this study are located in northern Minnesota and include 32 stands positioned in seven sites in the Red Lake peatland and Lake Itasca areas. Surface water chemistry ranges from pH values of 4.6 to 7.4, with corrected conductivity of 53 to 476 μohms cm−1 and calcium of 6.9 to 44.5 ppm. Six broad physiognomic landscape units are delimited based on quantitative analysis of the vegetation; these range from ombrotrophic ovoid islands to strongly minerotrophic forested fens. These landscape units can best be further divided or themselves characterized by the dominant Sphagnum species. Calculations of niche breadth across eight microhabitat axes and niche overlap for four microhabitat axes (pH, corrected conductivity, height above H2O level, and shade) for 13 species of Sphagnum suggest independent species utilization of the gradients. Among the mire-expanse species, niche breadths become narrower from hollow to hummock along calcium and pH gradients, whereas broadest niche breadths are present for midhummock species along the height gradient. For the taxonomically close species, S. fallax and S. angustifolium, niche overlap is greatest for conductivity and pH, whereas overlap is least along the height gradient. Quantification of niche breadth and niche overlap indicates considerable niche diversification along these microhabitat gradients, with individual species interacting independently to different gradients. These differing niche breadths along several different gradients suggest that these species of Sphagnum are largely equilibrium species, not opportunistic ones. In general, niche overlap is smaller in mire habitats where an abundance of bryophytes coexist with Sphagnum and highest in mire-expanse situations where Sphagnum is dominant.
Lake Wabamun, Alta.: a paleoenvironmental study
Authors: Hickman M. , Schweger C. E. , Habgood T.
Published: February 2008

Results from paleoenvironmental investigations of Lake Wabamun, Alta. (longitudes 114°26′ and 114°44′ W; latitudes 50°30′ and 53°35′ N), show that the sedimentary record spans the Holocene period in the case of the core taken from the deepest portion of the lake (the Seba core), while the record from the shallow Moonlight Bay spans a somewhat shorter interval. Basically, the lake has changed little during the last 4000 years except for increases in submersed hydrophytes in Moonlight Bay and undoubtedly other shallow regions of the lake. Production, too, has changed little during this interval except in Moonlight Bay, where hydrophytes and benthic algae contributed more to the sedimentary organic matter and fossil pigments. The deposition of the Mt. Mazama tephra in the catchment area and lake at 6600 years BP may have had a profound effect upon the lake. Increased turbidity occurred. This together with climatic changes including increased precipitation and catchment-area instability caused rapid infilling of the lake and low production. Moreover, prior to deposition of the tephra layer, water levels were lower and the water was more saline with Ruppia present, a feature found in other lakes in Alberta during the Hypsithermal period. Finally, prior to this period the lake was similar to its present day condition except during its very beginning when more turbid conditions prevailed.
The vegetation and water chemistry of four oligotrophic basin mires in northwestern Ontario
Authors: Vitt Dale H. , Bayley Suzanne
Published: February 2008

Four small oligotrophic basin mires on the Precambrian Shield were quantitatively analyzed for vegetation patterns and surface water and groundwater chemistry. Mean concentrations of ions in the surface waters of all vegetation stands indicate these mires to be characterized by low calcium content (0.6–1.9 mg Ca L−1), low corrected conductivity (12–31 μmho cm−1 (1 mho = 1 S)), and relatively high pH (4.0–5.7). Mire 224 is dominated by Chamaedaphne calyculata, Scheuchzeria palustris, and Carex oligosperma. The surface water mean determinations are Ca, 1.10 ± 0.51 mg L−1; Mg, 0.57 ± 0.2 mg L−1; corrected conductivity, 16.7 ± 4.2 μmho cm−1; and pH 4.37. Abundance patterns of the dominant Carex species can be correlated with pH of the surface water of the mire. Mire 239 is characterized by Smilacina trifolia, Ledum groenlandicum, and Carex trisperma. The mean surface water determinations are Ca, 1.53 ± 0.36 mg L−1; Mg, 0.59 mg L−1; corrected conductivity, 21.2 ± 2.0 μmho cm−1; and pH 4.0. Significant differences in pH, Ca, and Mg occur between the interior and edge portions of this bog. Water chemistry from portions burned in 1974 showed no difference from unburned portions. The vegetation of mire 661 contains a sequence of communities positioned relative to the inflow streams, with a Myrica gale – Alnus rugosa community followed by a zone dominated by Picea mariana then a Larix laricina zone and then by an open Sphagnum papillosum – Menyanthes trifoliata lake edge zone. More ombrotrophic areas are dominated by Sphagnum fuscum. Ca, Mg, and Fe concentrations, pH, and corrected conductivity were reduced through this sequence. Comparison of weekly samples of water entering and leaving this mire in 1981 showed a reduction of Ca, Mg, SO4, NO3 N, alkalinity, and pH.
Étude comparée de l'ultrastructure des stomates ouverts et fermés chez le Tradescantia virginiana
Authors: Couot-Gastelier J. , Laffray D. , Louguet P.
Published: February 2008

Guard cells and subsidiary cells of Tradescantia virginiana L. were examined with transmission and scanning electron microscopy. No plasmodesmata occur in the walls between the guard cells and the subsidiary cells. The numerous mitochondria suggest that guard cells are very active. Numerous small vacuoles were observed in closed stomata, whereas few and large vacuoles were present in opened stomata. A specialized peripheral reticulum and some invaginations containing cytoplasm were observed in chloroplasts of opened stomata. This increase of effective surface of the membrane presumably allows a rapid exchange of substances to or from the chloroplast. This was not observed in mesophyll plastids. The structures described are discussed in relation to guard cell physiology.
Vesicular–arbuscular endomycorrhizal inoculum production. I. Exploratory experiments with beans (Phaseolus vulgaris) in nutrient flow culture
Authors: Mosse B. , Thompson J. P.
Published: February 2008

A system is described in which typical vesicular–arbuscular (VA) mycorrhizal infections were produced in bean plants (Phaseolus vulgaris) grown in trays in which the roots were bathed in a shallow layer of recirculating nutrient solution (nutrient film technique, NFT). Infections were compared in solutions containing 1, 3, and 8 mg∙L−1 P, bonemeal, and rock phosphate. The infectivity of the NFT-grown mycorrhizal roots was tested using 1.2, 0.24, and 0.05 g of fresh root inoculum on maize and bean seedlings. The inoculum had good infectivity and even 0.05 g produced 5–10% infection in test seedlings after 6 weeks.