bluuebunny/crossref_metadata_2025 huggingface dataset:
DELAYED PIGMENTATION AND ULTRAVIOLET ERYTHEMA*
Authors: van der Leun J. C.
Published: February 2008

Abstract— Some observations are discussed which bear upon the mutual relationship of U.V. erythema and delayed pigmentation. The location of the pigmentation with respect to the exposed skin area suggests that the pigmentation is influenced by the preceding vasodilations. The influence of the pigmentation on the sensitivity of the skin to ultraviolet radiation of different wavelengths appears to support the hypothesis of two distinct erythemal effects of U.V. radiation. This leads to an integration of some long‐known phenomena in the theoretical considerations.
Linear series and the existence of branched covers
Authors: Osserman Brian
Published: January 2008

In this paper, we use the perspective of linear series, and in particular results following from the degeneration tools of limit linear series, to give a number of new results on the existence and non-existence of tamely branched covers of the projective line in positive characteristic. Our results are both in terms of ramification indices and the sharper invariant of monodromy cycles, and the first class of results are obtained by intrinsically algebraic and positive-characteristic arguments.
Twisted sheaves and the period-index problem
Authors: Lieblich Max
Published: January 2008

We use twisted sheaves and their moduli spaces to study the Brauer group of a scheme. In particular, we (1) show how twisted methods can be efficiently used to re-prove the basic facts about the Brauer group and cohomological Brauer group (including Gabber’s theorem that they coincide for a separated union of two affine schemes), (2) give a new proof of de Jong’s period-index theorem for surfaces over algebraically closed fields, and (3) prove an analogous result for surfaces over finite fields. We also include a reduction of all period-index problems for Brauer groups of function fields over algebraically closed fields to characteristic zero, which (among other things) extends de Jong’s result to include classes of period divisible by the characteristic of the base field. Finally, we use the theory developed here to give counterexamples to a standard type of local-to-global conjecture for geometrically rational varieties over the function field of the projective plane.
On lattices in semi-stable representations: a proof of a conjecture of Breuil
Authors: Liu Tong
Published: January 2008

For p≥3 an odd prime and a nonnegative integer r≤p−2, we prove a conjecture of Breuil on lattices in semi-stable representations, that is, the anti-equivalence of categories between the category of strongly divisible lattices of weight r and the category of Galois stable $\mathbb {Z}_p$-lattices in semi-stable p-adic Galois representations with Hodge–Tate weights in {0,…,r}.
Experimental Investigation of the Submarine Crashback Maneuver
Authors: Bridges David H. , Donnelly Martin J. , Park Joel T.
Published: January 2008

In order to decelerate a forward-moving submarine rapidly, often the propeller of the submarine is placed abruptly into reverse rotation, causing the propeller to generate a thrust force in the direction opposite to the submarine’s motion. This maneuver is known as the “crashback” maneuver. During crashback, the relative flow velocities in the vicinity of the propeller lead to the creation of a ring vortex around the propeller. This vortex has an unsteady asymmetry, which produces off-axis forces and moments on the propeller that are transmitted to the submarine. Tests were conducted in the William B. Morgan Large Cavitation Channel using an existing submarine model and propeller. A range of steady crashback conditions with fixed tunnel and propeller speeds was investigated. The dimensionless force and moment data were found to collapse well when plotted against the parameter η, which is defined as the ratio of the actual propeller speed to the propeller speed required for self-propulsion in forward motion. Unsteady crashback maneuvers were also investigated with two different types of simulations in which propeller and tunnel speeds were allowed to vary. It was noted during these simulations that the peak out-of-plane force and moment coefficient magnitudes in some cases exceeded those observed during the steady crashback measurements. Flow visualization and LDV studies showed that the ring vortex structure varied from an elongated vortex structure centered downstream of the propeller to a more compact structure that was located nearer the propeller as η became more negative, up to η=−0.8. For more negative values of η, the vortex core appeared to move out toward the propeller tip.
Autogenous Suction to Prevent Laminar Boundary-Layer Separation
Authors: Atik Hediye , van Dommelen Leon
Published: January 2008

Boundary-layer separation can be prevented or delayed by sucking part of the boundary layer into the surface, but in a straightforward application the required hydraulics entail significant penalties in terms of weight and cost. By means of computational techniques, this paper explores the possibility of autogenous suction, in which the local pressure differences that lead to separation drive the suction used to prevent it. The chosen examples include steady and unsteady laminar flows around leading edges of thin airfoils. No fundamental theoretical limit to autogenous suction was found in the range of angles of attack that could be studied, but rapidly increasing suction volumes suggest that practical application will become increasingly difficult for more severe adverse pressure gradients.
Simulation of Shallow Flows in Nonuniform Open Channels
Authors: Liang Qiuhua
Published: January 2008

This paper presents a new formulation of the 2D shallow water equations, based on which a numerical model (referred to as NewChan) is developed for simulating complex flows in nonuniform open channels. The new shallow water equations mathematically balance the flux and source terms and can be directly applied to predict flows over irregular bed topography without any necessity for a special numerical treatment of source terms. The balanced governing equations are solved on uniform Cartesian grids using a finite-volume Godunov-type scheme, enabling automatic capture of transcritical flows. A high-order numerical scheme is achieved using a second-order Runge–Kutta integration method. A very simple immersed boundary approach is used to deal with an irregular domain geometry. This method can be easily implemented in a Cartesian model and does not have any influence on computational efficiency. The numerical model is validated against several benchmark tests. The computed results are compared with analytical solutions, previously published predictions, and experimental measurements and excellent agreements are achieved.
Genetic and Biochemical Characterization of OXA-63, a New Class D β-Lactamase fromBrachyspira pilosicoliBM4442
Authors: Meziane-Cherif Djalal , Lambert Thierry , Dupêchez Marine , Courvalin Patrice , Galimand Marc
Published: January 2008

Brachyspira pilosicoliBM4442, isolated from the feces of a patient with diarrhea at the Hospital Saint-Michel in Paris, was resistant to oxacillin (MIC > 256 μg/ml) but remained susceptible to cephalosporins and to the combination of amoxicillin and clavulanic acid. Cloning and sequencing of the corresponding resistance determinant revealed a coding sequence of 807 bp encoding a new class D β-lactamase named OXA-63. TheblaOXA-63gene was chromosomally located and not part of a transposon or of an integron. OXA-63 shared 54% identity with FUS-1 (OXA-85), an oxacillinase fromFusobacterium nucleatumsubsp.polymorphum, and 25 to 44% identity with other class D β-lactamases (DBLs) and contained all the conserved structural motifs of DBLs.Escherichia colicarrying theblaOXA-63gene exhibited resistance to benzylpenicillin and amoxicillin but remained susceptible to amoxicillin in combination with clavulanic acid. Mature OXA-63 consisted of a 31.5-kDa polypeptide and appeared to be dimeric. Kinetic analysis revealed that OXA-63 exhibited a narrow substrate profile, hydrolyzing oxacillin, benzylpenicillin, and ampicillin with catalytic efficiencies of 980, 250, and 150 mM−1s−1, respectively. The enzyme did not apparently interact with oxyimino-cephalosporins, imipenem, or aztreonam. Unlike FUS-1 and other DBLs, OXA-63 was strongly inhibited by clavulanic acid (50% inhibitory concentration [IC50] of 2 μM) and tazobactam (IC50of 0.16 μM) and exhibited low susceptibility to NaCl (IC50of >2 M). OXA-63 is the first DBL described for the anaerobic spirocheteB. pilosicoli.
Combination Echinocandin-Polyene Treatment of Murine Mucormycosis
Authors: Ibrahim Ashraf S. , Gebremariam Teclegiorgis , Fu Yue , Edwards John E. , Spellberg Brad
Published: January 2008

We previously found that caspofungin synergized with amphotericin B lipid complex in treating murine mucormycosis. We now report a similarly enhanced activity of liposomal amphotericin combined with micafungin or anidulafungin in mice with disseminated mucormycosis. The efficacy of combination echinocandin-polyene therapy for mucormycosis is a class effect.
Induction of L1 and L2 β-Lactamase Production inStenotrophomonas maltophiliaIs Dependent on an AmpR-Type Regulator
Authors: Okazaki Aki , Avison Matthew B.
Published: January 2008

A divergently orientedampRhas been located upstream ofblaL2inStenotrophomonas maltophilia. AmpR is necessary for L1 and L2 β-lactamase induction in response to β-lactam challenge, and activation of AmpR is sufficient to induce L1 and L2 production. L1 induction requires more activation of AmpR than does L2 induction.
Clinical Response and Outcome of Infection with
Salmonella enterica
Serotype Typhi with Decreased Susceptibility to Fluoroquinolones: a United States FoodNet Multicenter Retrospective Cohort Study
Authors: Crump John A. , Kretsinger Katrina , Gay Kathryn , Hoekstra R. Michael , Vugia Duc J. , Hurd Sharon , Segler Susan D. , Megginson Melanie , Luedeman L. Jeffrey , Shiferaw Beletshachew , Hanna Samir S. , Joyce Kevin W. , Mintz Eric D. , Angulo Frederick J.
Published: January 2008

Patients with typhoid fever due to
Salmonella enterica
serotype Typhi strains for which fluoroquinolones MICs are elevated yet that are classified as susceptible by the current interpretive criteria of the Clinical and Laboratory Standards Institute may not respond adequately to fluoroquinolone therapy. Patients from seven U.S. states with invasive
Salmonella
serotype Typhi infection between 1999 and 2002 were enrolled in a multicenter retrospective cohort study. Patients infected with
Salmonella
serotype Typhi isolates with ciprofloxacin MICs of 0.12 to 1 μg/ml (decreased ciprofloxacin susceptibility but not resistant to ciprofloxacin [DCS]) were compared with patients infected with isolates with ciprofloxacin MICs <0.12 μg/ml for fever clearance time and treatment failure. Of 71 patients, 30 (43%) were female and 24 (34%) were infected with
Salmonella
serotype Typhi with DCS; the median age was 14 years (range, 1 to 51 years). Twenty-one (88%) of 24 isolates with DCS were resistant to nalidixic acid. The median antimicrobial-related fever clearance times in the DCS and non-DCS groups were 92 h (range, 21 to 373 h) and 72 h (range, 19 to 264 h) (
P
= 0.010), respectively, and the fluoroquinolone-related fever clearance times in the DCS and non-DCS groups were 90 h (range, 9 to 373 h) and 64 h (range, 34 to 204 h) (
P
= 0.153), respectively. Four (17%) of 24 patients in the DCS group and 2 (4%) of 46 patients in the non-DCS group (relative risk, 2.5; 95% confidence interval, 1.2 to 5.1) experienced treatment failure. Associations persisted after adjustment for potential confounders. We demonstrate that patients infected with
Salmonella
serotype Typhi isolates with DCS show evidence of a longer time to fever clearance and more frequent treatment failure. Nalidixic acid screening does not detect all isolates with DCS.
Direct Binding of Human NK Cell Natural Cytotoxicity Receptor NKp44 to the Surfaces of Mycobacteria and Other Bacteria
Authors: Esin Semih , Batoni Giovanna , Counoupas Claudio , Stringaro Annarita , Brancatisano Franca Lisa , Colone Marisa , Maisetta Giuseppantonio , Florio Walter , Arancia Giuseppe , Campa Mario
Published: January 2008

Our previous studies demonstrated that
Mycobacterium bovis
bacillus Calmette-Guérin (BCG) can directly interact with human NK cells and induce the proliferation, gamma interferon production, and cytotoxic activity of such cells without the need for accessory cells. Thus, the aim of the present study was to identify the putative receptor(s) responsible for the recognition of BCG by human NK cells and potentially involved in the activation of NK cells. To this end, we first investigated the surface expression of three NK cell-activating receptors belonging to the natural cytoxicity receptor (NCR) family on highly purified human NK cells upon in vitro direct stimulation with BCG. An induction of the surface expression of NKp44, but not of NKp30 or NKp46, was observed after 3 and 4 days of in vitro stimulation with live BCG. The NKp44 induction involved mainly a particular NK cell subset expressing the CD56 marker at high density, CD56
bright
. In order to establish whether NKp44 could directly bind to BCG, whole BCG cells were stained with soluble forms of the three NCRs chimeric for the human immunoglobulin G (IgG) Fc fragment (NKp30-Fc, NKp44-Fc, NKp46-Fc), followed by incubation with a phycoerythrin (PE)-conjugated goat anti-human IgG antibody. Analysis by flow cytometry of the complexes revealed a higher PE fluorescence intensity for BCG incubated with NKp44-Fc than for BCG incubated with NKp30-Fc, NKp46-Fc, or negative controls. The binding of NKp44-Fc to the BCG surface was confirmed with immunogold labeling using transmission electron microscopy, suggesting the presence of a putative ligand(s) for human NKp44 on the BCG cell wall. Similar binding assays performed on a number of gram-positive and gram-negative bacteria revealed a pattern of NKp44-Fc binding restricted to members of the genus
Mycobacterium
, to the mycobacterium-related species
Nocardia farcinica
, and to
Pseudomonas aeruginosa
. Altogether, the results obtained indicate, for the first time, that at least one member of the NCR family (NKp44) may be involved in the direct recognition of bacterial pathogens by human NK cells.
Fetal Responses during Placental Malaria Modify the Risk of Low Birth Weight
Authors: Kabyemela Edward R. , Fried Michal , Kurtis Jonathan D. , Mutabingwa Theonest K. , Duffy Patrick E.
Published: January 2008

Inflammation during placental malaria (PM) is associated with low birth weight (LBW), especially during the first pregnancy, but the relative contribution of maternal or fetal factors that mediate this effect remains unclear and the role of gamma interferon (IFN-γ) has been controversial. We examined the relationship of maternal and cord plasma levels of IFN-γ, tumor necrosis factor alpha, interleukin-10, ferritin, and leptin to birth weight for Tanzanian women delivering in an area where there is a high rate of malaria transmission. The placental levels of inflammatory cytokines, including IFN-γ, increased significantly during PM in primigravid and multigravid women but not in secundigravid women. PM also increased maternal peripheral levels of all inflammatory markers except IFN-γ but had strikingly little effect on cord levels of these proteins. In a multivariate analysis, placental IFN-γ was negatively associated (P= 0.01) and cord ferritin was positively associated (P< 0.0001) with birth weight in infected (PM-positive [PM+]) first-time mothers. This relationship was not observed in other mothers, consistent with the epidemiology of PM and disease. Cord leptin had a strong positive relationship with birth weight in offspring of PM-negative women (P= 0.02 toP< 0.0001) but not in offspring of PM+women (all differences were not significant) in the three gravidity groups. The results confirmed that placental IFN-γ is related to LBW due to PM during first pregnancies and suggest that fetal ferritin plays a protective role. Because fetal cells are a source of placental IFN-γ and cord ferritin, the fetal response to PM may modify the risk of LBW.
Recent advances in Clostridium difficile-associated disease
Authors: Monaghan T , Boswell T , Mahida Y R
Published: February 2008

The main purpose of this article is to review recent developments in the management of acute and recurrent Clostridium difficile-associated disease, with consideration of existing and new antibiotic and non-antibiotic agents for treatment. Details of the current developmental stage of new agents are provided and the role of surgery in the management of severe disease is discussed. Infection control measures considered comprise prudent use of antimicrobials, prevention of cross-infection and surveillance. Other topics that are covered include the recent emergence of an epidemic hypervirulent strain, pathogenesis, clinical presentation and approaches to rapid diagnosis and assessment of the colonic disease.
Seasonal patterns of soil respiration in intact and clear-cut northern hardwood forests
Authors: Toland David E. , Zak Donald R.
Published: February 2008

The flux of CO2 from forest soils is controlled by the respiration of plant roots and soil microorganisms, the rates of which are likely to change following forest harvesting. Root respiration should decrease, whereas microbial respiration should increase, in response to warmer soil temperatures and greater soil C availability following removal of the overstory. We investigated the influence of forest harvesting on seasonal patterns of soil respiration in two different northern hardwood ecosystems. One ecosystem was dominated in the overstory by Acersaccharum Marsh, and Quercusrubra L., and the other by A. saccharum and Tiliaamericana L.; two stands were studied in each ecosystem type. We measured daily rates of soil respiration using the soda-lime technique. Averaged across ecosystems, daily rates of soil respiration did not significantly differ between intact and clear-cut plots, nor did they differ between ecosystems or sites nested within ecosystems. Peak daily rates ranged from 2.75 to 3.00 g CO2-C•m−2•day−1 during mid to late summer in both intact and clear-cut plots. Soil temperature accounted for 43 and 58% of the variation in daily rates for intact and clear-cut plots, respectively. Annual soil respiration rates in intact (478 g CO2-C•m−2•year−1) and clear-cut (470 g CO2-C•m−1•year−1) plots did not differ significantly. Our results suggest that greater rates of microbial respiration in clear-cut plots proportionally offset a decrease in root respiration following clear-cut harvest.
An antigonadotropin from the ovaries of the insect Rhodnius prolixus Stål.
Authors: Huebner E. , Davey K. G.
Published: January 2008

Direct evidence from implant experiments indicates that the presence of mature eggs within the pedicels of Rhodnius prolixus virgin females results in the release of an antigonadotropin. This factor appears to prevent the normal gonadotropin induced patency of the follicular epithelium, thereby inhibiting vitellogenesis.
The ultrastructure of the cuticle of the nematode Syphacia obvelata (Rudolphi, 1802). I. The body cuticle of larvae, males,and females, and observations on its development
Authors: Dick T. A. , Wright K. A.
Published: January 2008

The body cuticle of Syphacia obvelata (Rudolphi, 1802) has been examined with light and electron microscopy through larval and adult stages. In all stages the cuticle consists of a cortex, and median and basal zones. Material showing transverse striations with 180–220 Å periodicity (striated material) occurs in the median zone of larvae and young adults. However, progressive growth and deposition of more striated material results in the cuticle of older females appearing markedly different from the cuticle of the short-lived males. Striated material is concluded to be formed of bands of approximately circular discs. Overlap of such bands produces the various patterns seen in sections. Similarities between methods of formation of striated material and other cuticular components are noted between molting periods and the growth phase of females. The presence of intracuticular tubules and external longitudinal ridges is noted.
Molluscs as indicators of late- and post-glacial climatic history in Alberta
Authors: Harris S. A. , Pip E.
Published: January 2008

Molluscs dated from 13 000 radiocarbon years B.P. to the present day were sampled at sites throughout southwestern Alberta. The ratio of southern forms (those presently occurring only south of 55°N) to northward-ranging species (those also occurring north of 55°N) in the major chronological sediment zones reflected the main climatic trends of the period. A study of present-day ecological preferences of the species allowed speculation on successional status of past terrestrial vegetation, agreeing satisfactorily with a previously published pollen diagram from central Alberta. Three major climatic periods could be identified: (1) a warming trend with precipitation higher than that of today from the beginning of the Laurentide ice retreat until about 9000 radiocarbon years B.P., (2) still warmer but drier conditions 9000 to 7000 radiocarbon years B.P., and (3) gradual cooling and drying until present-day conditions.
A female sea lamprey (Petromyzon marinus) with a true anal fin, and the question of the presence of an anal fin in Petromyzonidae
Authors: Vladykov Vadim D.
Published: January 2008

Description is given of a female sea lamprey (Petromyzon marinus) 498 mm long, which had a true anal fin, 31 mm in length supported by about 30 cartilaginous rays. The question of the presence of an anal fin in Petromyzonidae is also discussed.
Incubation of rabbit embryos in silicone rubber tubing within the abdominal cavity
Authors: Cole W. D. , King G. J.
Published: January 2008

This study was designed to investigate the feasibility of maintaining rabbit embryos suspended in tissue culture medium 199 + rabbit serum (1:1) within silicone rubber tubing placed in the abdominal cavity of rabbits. In one experiment embryos were collected from one oviduct, placed in silicone rubber tubes, and returned to the abdominal cavity of the donor for 24 or 48 h. Comparison of the 223 embryos placed in the tubes and the 186 control embryos from the intact oviducts showed that the development of the manipulated embryos was retarded.A comparison between embryos incubated intraabdominally within mature male or pseudopregnant rabbits showed no significant difference between the treatments after 24 or 48 h (P > 0.05). The viability of embryos maintained in the silicone rubber tubes was assessed by subsequent transfer into recipient does. Three successful transfers out of six attempts were achieved after embryos had been cultured for 48 h in the abdominal cavity of pseudopregnant females. The results suggest that long-distance transport of embryos contained within silicone rubber tubes placed in the abdominal cavity of laboratory animals might be possible.
Transmission of parasites with reference to the strongyles of domestic sheep and cattle
Authors: Gibbs H. C.
Published: January 2008

Transmission of the strongylid nematodes of domestic ruminants involves the interaction of a number of factors. First are those factors in the initial host, which significantly influence the biological processes of the parasite involved in the production of infective stages. Secondly, since transmission involves a period when the infective stages are external to the host, environmental factors exert an important influence on the free-living phase of their development. Thirdly, when the infective stages gain access to a new host, parasite-host interactions influence establishment and reproduction of the parasite.These interrelationships influence the seasonal parasite distribution and ensure the persistence of infection in the host.
Effects of antibiotics on feeding and development of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae)
Authors: Srivastava P. N. , Auclair J. L.
Published: January 2008

Four antibiotics were individually incorporated into holidic diets that were fed to the pea aphid, Acyrthosiphon pisum (Harris). Streptomycin and penicillin at 0.01% had little effect on growth, but reduced fecundity and survival. Chloromycetin and neomycin at 0.01% greatly reduced growth and survival, and aphids did not reach the adult stage. Higher concentrations (0.1%) of streptomycin and penicillin significantly reduced growth and survival, and no adults were produced if continued on penicillin. However, such a high concentration did not seem to inflict irrecoverable damages, since when aphids that were fed for 7 days on 0.1% streptomycin and penicillin were returned to antibiotic-free (control) diets they gained weight, reached maturity, and reproduced, although progeny survival was very low.Streptomycin appeared to be phagostimulatory, whereas penicillin and chloromycetin acted as feeding deterrents. First-instar larvae on the control diet, and on diets containing 0.1% streptomycin, penicillin, and chloromycetin in 24 h ingested 95.4, 120.8, 45.4, and 35.7 μg per aphid, respectively. It is suggested that these three antibiotics caused only partial damage to the symbiotes of the aphid, and that the poor growth, survival, and fecundity associated in the first generation with high concentrations of either penicillin or chloromycetin resulted mainly from a lower rate of diet intake.
Use of sentinel ducks in epizootiological studies of anatid blood protozoa
Authors: Herman Carlton M. , Bennett Gordon F.
Published: January 2008

Sentinel ducks exposed to natural infection during three summers (1972–1974) at the Tintamarre National Wildlife Area in New Brunswick, Canada, developed parasitemias with Leucocytozoon simondi and Haemoproteus nettionis. Leucocytozoon appeared as early as mid-June and active transmission was evident until the end of July. The level of parasitemia attained was low. Very few deaths were attributable to the infection. Haemoproteus was not evident until mid-July and active transmission continued until mid-August. Geese exposed at one site developed much more intense infection with L. simondi than developed in the sentinel ducks. No Haemoproteus was evident in these geese.
Consumption and utilization of various host plants by Melanoplus bivittatus (Say) and M. femurrubrum (DeGeer) (Orthoptera: Acrididae)
Authors: Bailey C. G. , Mukerji M. K.
Published: January 2008

Nymphal stages of Melanoplus bivittatus (Say) and M. femurrubrum (DeGeer) that were reared on five plant diets fed and grew at different rates. Differential mortality was obtained among the two species reared on the various diets, with the highest occurring in those feeding on alfalfa. On all plants a direct linear relationship was obtained between rate of food consumption and rate of growth, and slopes varied from 0.18 to 0.25 in M. bivittatus and from 0.14 to 0.18 in M. femurrubrum. The approximate digestibility on the various plants were all in the range of 41 to 47% for M. bivittatus and 37 to 48% for M. femurrubrum. The efficiency of conversion of digested food to body tissue (ECD) varied from 35 to 44% in M. bivittatus and from 33 to 44% in M. femurrubrum. The efficiency of conversion of ingested food to body tissue (ECI) varied from 15 to 18% in M. bivittatus, and from 15 to 19% in M. femurrubrum. Egg production in M. bivittatus varied from 196 on corn to 450 on radish; it was lower in M. femurrubrum, and varied from 162 on corn to 336 on the mixed diet.
Temperature-induced meristic variation among three homozygous genotypes (clones) of the self-fertilizing fish Rivulus marmoratus
Authors: Harrington Jr. R. W. , Crossman Jr. R. A.
Published: January 2008

Embryos of clones DS, NA, and M were reared at sustained temperatures of 19, 25, and 31 °C. Diverse evidence indicates a closer genetic affinity between DS and NA than between either and M. DS and NA converged and M diverged regarding thermal responses of vertebrae, and anal and pelvic rays; DS and M converged and NA diverged regarding responses of pectoral, caudal, and dorsal rays. For vertebrae and pectoral rays, response curves were declivous; for caudal rays, inverted-V shaped; for anal rays, upright-V shaped (NA), inverted-V shaped (DS), declivous (M); for dorsal rays, declivous (NA), upright-V shaped (DS and M); for pelvic rays, subhorizontal (DS and NA), inverted-V shaped (M). The vertebral response curves of DS and NA diverged at 25 °C, converging at 19 and 31 °C. Caudal counts increased between 31 and 25 °C, caudal and precaudal, between 25 and 19 °C. Vertebral differences (as percentage of the midpoint count) exceeded any of previous experiments on species other than R. marmoratus. At 19 and 31 °C pelvic fins are often lacking, but never in outbreeding R. cylindraceus. Response curves except vertebral ones differed qualitatively between these species. Many kinds of variations, and proportions of phenotypic differences due to genotypic and environmental differences and their interactions are compared.
The effect of diet on queen rearing by caged worker honeybees
Authors: Peng Ying-Shin , Jay S. C.
Published: January 2008

Groups of 400, 5-day-old nurse bees were used to rear queens in cages in the laboratory; seven different diets were fed to the nurse bees. The development of the hypopharyngeal glands of the nurse bees, their queen-rearing ability, and the brood production of the queens that they reared were used to evaluate these diets. Diets of stored pollen fortified with amino acids or vitamins, and of fresh pollen had similar effects on the development of the hypopharyngeal glands. The hypopharyngeal glands of nurse bees fed pollen substitute, pollen supplement, or stored pollen degenerated with age, and queen rearing by these groups was low. Queens reared by nurse bees fed stored pollen with amino acids or vitamins produced large amounts of brood, but significantly less than those queens reared by bees fed diets with fresh pollen.
The fine structure of the nervous tissue of the metacestode of Hymenolepis microstoma
Authors: Webb Rodney A. , Davey Kenneth G.
Published: January 2008

The cytology of the nervous tissue of the metacestode of Hymenolepis microstoma was studied by electron microscopy. The small (3–5 μm) nerve cell bodies are smooth to irregular in outline, possessing one to several neurites that form synapses in the neuropile. Each neuronal perikaryon contains a single nucleus with a single nucleolus, numerous free ribosomes, occasional polyribosomes, small numbers of β-glycogen granules, multivesicular bodies, mitochondria, complex (coated or alveolate) vesicles, one or more Golgi complexes, and variable numbers of vesicles. Microtubules and microfilaments, however, are absent from the perikaryon. Subsurface cisternae are well developed; the inner faces of them are studded with ribosomes. Five types of vesicles, believed to contain neurotransmitter and (or) neurosecretion were identified on the basis of vesicle osmophilia and size distribution. On the basis of vesicle content, four nerve cell types were identified: sensory neurons, two putative interneurons, and one neuronal type possessing characteristics of both interneurons and motor neurons.
Preference and selection of prey by creek chub (Semotilus atromaculatus) inhabiting the Mink River, Manitoba
Authors: (Buck) Newsome G. E. , Gee J. H.
Published: January 2008

In the Mink River, Manitoba, adult creek chub were observed to be selective feeders consuming brook stickleback in early summer and crayfish in late summer despite an abundance of other potential prey fishes, particularly johnny darters and a number of cyprinids. Laboratory experiments conducted to investigate preference, utilizing creek chub from two isolated populations, Mink River and Norquay Channel, Manitoba, demonstrated that both brook stickleback and crayfish were preferred least, ranking behind johnny darters and two species of cyprinids, pearl dace, and common shiners, respectively. Subsequent experiments were conducted to examine a number of possible factors which might reduce or increase the accessibility of potential prey species. Results revealed that the johnny darter, although preferred, was protected from predation by creek chub by the presence of a rocky substrate. Similarly the presence of simulated rooted aquatic vegetation reduced the accessibility of brook stickleback. The inaccessibility of cyprinids was not attributable to a pheromone-induced fright reaction but possibly to their countershading.
Etude morphologique des larves de Lestes eurinus Say (Odonata: Lestidae), élevées en laboratoire
Authors: Pellerin Pierre , Pilon Jean-Guy
Published: January 2008

Laboratory rearing of Lestes eurinus enabled us to obtain larvae in the latter instars which seem to be morphologically similar to those in the field. The 16 exuviae series that we obtained enabled us to describe briefly the morphological changes taking place during larval growth, for the first time in this species. We discuss briefly the usefulness of these criteria in the determination of the larval instars of this species.
Seasonal changes in the circadian period of the lake chub, Couesius plumbeus
Authors: Kavaliers Martin
Published: January 2008

Systematic seasonal and annual changes are present in the length of the circadian period, τ, of the lake chub, Couesius plumbeus. Maximum and minimum period values of 28.1 and 24.8 h were recorded under constant darkness from fish obtained at the times of the winter and summer solstices, respectively. There was an asymmetric annual pattern in the τ values obtained from the increasing and decreasing photoperiods of spring and fall. Annual variations in τ were relatively independent of temperature. They were interpreted as being aftereffects of natural photoperiodic entrainment. Relations of annual changes in the length of the period to models of circadian organization and entrainment are examined.
Effect of salinity on the osmoregulatory cells in the tracheal gills of the stonefly nymph, Paragnetina media (Plecoptera: Perlidae)
Authors: Kapoor N. N.
Published: January 2008

The ultrastructure of the osmoregulatory cells in the integument of the stonefly nymph, Paragnetina media, shows changes in media hypotonic, isotonic, and hypertonic to the hemolymph. Exposure to hypotonic concentration results in an increase in the plasma membrane folds, mitochondria, and microtubules in the cytoplasm. In isotonic and hypertonic concentrations, the cells show cellular disorganization and apparent loss in their function. These results suggest that the structural changes in the osmoregulatory cells are related to the osmotic condition of the medium, and these cells probably act as extrarenal sites for the absorption of ions from the hypoosmotic medium.
The central mudminnow, Umbra limi (Kirtland), a habitat specialist and resource generalist
Authors: Martin-Bergmann Kathleen A. , Gee John H.
Published: January 2008

The central mudminnow, Umbra limi (Kirtland), successfully inhabits a variable and unpredictable environment in southern Manitoba streams. Umbra accomplishes this by specializing in habitat and generalizing in resources utilized and life history strategies displayed. Mudminnows are restricted to still waters and show a preference for a variety of cover types. They are morphologically, physiologically, and behaviourally specialized for this habitat. Umbra limi inhabits areas subjected to hypoxia and all sizes are able to use both atmospheric and aquatic respiration. Mudminnows are euryphagic carnivores that eat aquatic and terrestrial invertebrates and fish. They feed from a variety of locations (benthic, midwater, and surface) and organisms attached to vegetation are included in the diet. Activity patterns (including feeding) vary daily and seasonally. Differences in rate of growth, age at first maturity, gonadal development, and survival occur between sexes. Individual and population variability is apparent. Spawning time varies and there is evidence for delayed spawning under unfavourable conditions.
Comparisons of body reserve buildup and use in several groups of Canada geese
Authors: Mainguy S. K. , Thomas V. G.
Published: January 2008

Changes in proximate body composition were analyzed in nonmigratory giant Canada geese (Branta canadensis maxima) from Toronto, Ont. (43°37′N, 79°20′W), collected during early and late egg laying in 1980 and 1981, and during incubation and moult in 1981. Early nesting geese had more fat, though not more protein, than late nesting birds in both years. Geese collected in 1981 had more fat and protein than geese collected in 1980. Early and late laying females in both years lost on average 198 g (26%) of fat and 34 g (5%) of protein from the beginning to the end of laying. Fifty-eight percent of the fat reserves possessed at the beginning of laying were lost during incubation. Fat reserves of prelaying Branta canadensis interior nesting on the James Bay lowland (53°15′N, 82°09′W) in 1980 were 9% greater than those of B. c. maxima nesting in Southern Ontario. During the moult at Toronto, Canada geese lost weight from flight muscles while gaining weight in other muscles and in fat. This pattern is seen in waterfowl moulting at several latitudes, and indicates that geese moulting in both southern and northern latitudes probably rely on nutrients in food rather than in body tissues to supply growing feathers.
Crepidostomum opeongoensis n.sp. (Digenea: Allocreadiidae) from Hexagenia limbata (Serville in Guerin) in Algonquin Park, Ontario, Canada
Authors: Caira J. N.
Published: January 2008

A new species of papillose allocreadiid is described from the abdominal haemocoel of a male nymph of Hexagenia limbata from Lake Opeongo in Algonquin Park, Ontario, Canada. Crepidostomum opeongoensis n.sp. resembles Crepidostomum latum (Pigulewsky, 1931) Hopkins, 1933 and Crepidostomum brevivitellum Hopkins, 1934 in having vitellaria confined to the hindbody, but differs by possessing dorsolateral papillae of the oral sucker that are twice as wide as the dorsomedial papillae. Crepidostomum opeongoensis is further distinguished from C. latum by an oral sucker that is larger rather than smaller than the acetabulum, a body that is twice as large, and a cirrus sac that extends posterior to the acetabulum rather than ending at the midlevel of the acetabulum. It is further distinguished from C. brevivitellum by its longer ventral papillae, greater post-testicular space, and hindbody that widens rather than tapers. The discovery of ovigerous worms of C. opeongoensis in an insect is discussed in relation to other such species in the family.
Cortical microtubular structures of the ciliate Lepidotrachelophyllum fornicis Nicholls &Lynn, 1984 and phytogeny of the litostomate ciliates
Authors: Lynn Denis H. , Nicholls Kenneth H.
Published: January 2008

The somatic and oral cortical ultrastructure of Lepidotrachelophyllum fornicis Nicholls &Lynn, 1984 are described. The somatic kinetids are monokinetids whose fibrillar associates include the following: (i) a kinetodesmal fibril which originates near triplets 6, 7, and 8 and extends laterally and to the right at an angle of about 45° to the longitudinal axis of the kinety; (ii) a postciliary ribbon which originates in dense material near triplet 9 and extends posteriorly and to the right; (iii) a primary transverse ribbon which originates near triplets 3, 4, and 5 and extends to the left and anteriorly; (iv) a secondary transverse ribbon which originates near triplet 5 and curves to extend to the lateral left; and (v) a ribbon of rootlet microtubules which originates on the left at the base of the kinetosome. The oral kinetids are dikinetids. The ciliated posterior kinetosome has the following: (i) a postciliary ribbon which extends posteriorly and to the right; and (ii) a transverse ribbon which extends only a short distance anteriorly. The nonciliated anterior kinetosome has the following: (i) a single postciliary microtubule; (ii) a large transverse ribbon which extends into the oral cone; and (iii) near its base a hexagonal nematodesma. The cytopharyngeal apparatus or rhabdos is described and a schematic figure is presented. The cellular mechanisms underlying body shape changes and food vacuole formation and the phylogeny of the class Litostomatea are discussed.
The protozoan parasites of fish from two lakes in Algonquin Park, Ontario
Authors: Li Lianxiang , Desser Sherwin S.
Published: January 2008

The parasitic Protozoa of seven species of freshwater fish (the cyprinids Notropis cornutus, Notropis heterolepis, Notemigonus crysoleucas, and Semotilus atromaculatus; the percid Perca flavescens; the centrarchid Lepomis gibbosus; and the salmonid Salvelinus fontinalis) are described from Lake Sasajewun and Lake Opeongo, Algonquin Park, Ontario. The parasites include 1 species of Hexamita, 6 species of Goussia, 2 species of Eimeria, 3 species of Octosporella, 30 species of Myxosporea, and 9 species of Ciliata. Fifteen new species are described: Goussia notropicum, Goussia notemigonica, Sphaerospora diminuta, Myxobolus heterolepis, Myxobolus lepomicus, Myxobolus paralintoni, Myxobolus gibbosus, Myxobolus wellerae, Myxobolus schuberti, Myxobolus pseudokoi, Myxobolus pellicdes, Thelohanellus oviformis, Myxobilatus semotilii, Trichodina opeongoensis, and Apiosoma triangularis. The relative distribution of the parasites and their prevalence in fish from the two lakes, and the global distribution of protozoan parasites of fish are discussed.
Three new species of Octosporella (Protozoa: Coccidia) from cyprinid fish in Algonquin Park, Ontario
Authors: Li Lianxiang , Desser Sherwin S.
Published: January 2008

Among the protozoan parasites observed in cyprinid fish from Lake Sasajewun and Lake Opeongo, Algonquin Park, Ontario, were coccidian parasites with oocysts containing eight sporocysts, each of which housed two sporozoites. Three new species of Octosporella Ray and Raghavachari, 1942 are described: Octosporella notropis sp. n. from the intestine, spleen, and swim bladder of the common shiner, Notropis cornutus (Mitchill), and Octosporella opeongoensis sp. n. and Octosporella sasajewunensis sp. n. from the swim bladder of the golden shiner, Notemigonus crysoleucas (Mitchill). The present report represents the first time parasites of this genus have been recorded from fish.
Habitat use and abundance of deer mice: interactions with meadow voles and red-backed voles
Authors: Galindo Carlos , Krebs Charles J.
Published: January 2008

In this study we investigated the influence of competitive interactions on the use of habitats and relative abundance of deer mice (Peromyscus maniculatus). If interspecific competition is influencing the habitat use and relative abundance of deer mice, then removal or introduction of potential competitors will change habitat use and abundance of this species. During the first field season we removed meadow voles (Microtus pennsylvanicus) to look at the effect on the contiguous population of deer mouse. The removal of one species had no effect on the other species' distribution or demography. In the second field season, meadow voles declined to very low numbers and we used their natural fluctuation as a removal experiment. Deer mouse populations were not affected even when the natural decline of meadow voles was more effective in maintaining the sedge meadow free of voles than the previous removal manipulation was. During the 3rd year, meadow voles colonized two areas of forest where deer mice had been alone the previous two field seasons. Red-backed voles (Clethrionomys rutilus), in turn, increased from very low numbers in four grids. Neither meadow voles nor red-backed voles affected the spatial distribution or abundance of deer mice. The results of this study indicate that competitive interactions have no influence on the use of habitats and relative abundance of the common species of small mammals in the southwestern Yukon.
Ultrastructural changes in the oocyst wall during excystation of Cryptosporidium parvum (Apicomplexa; Eucoccidiorida)
Authors: Reduker David W. , Speer C. A. , Blixt John A.
Published: January 2008

Cryptosporidium parvum oocysts were obtained from the feces of naturally infected calves and the oocyst wall was examined ultrastructurally. The oocyst wall averaged 49.7 nm thick and was composed of two layers. The outer layer was irregular in thickness, averaging 10 nm. A thin, electron-lucent space (2.5 nm) was interposed between the outer and inner layers. The inner layer had an outer (11.6 nm) and an inner (25.8 nm) zone. A suture that extended partway around the oocyst was observed within the inner layer of the oocyst wall. The suture underwent dissolution during excystation.
Scale structure and taxonomy of some species of Raphidocystis, Raphidiophrys, and Pompholyxophrys (Heliozoea) including descriptions of six new taxa
Authors: Nicholls K. H. , Dürrschmidt M.
Published: January 2008

Sixteen taxa of the genera Raphidocystis, Raphidiophrys, and Pompholyxophrys from freshwater habitats in Canada, Chile, and New Zealand were studied by light and electron microscopy. Six taxa are described as new: Raphidocystis glabra, Raphidiophrys minuta, Raphidiophrys orbicularis ssp. orbicularis, R. orbicularis ssp. ovalis, Pompholyxophrys stellata, and P. ossea. New information on scale structure and arrangement based on scanning and transmission electron microscopy amplifies the taxonomic descriptions of Raphidiophrys ambigua, R. pallida, R. elegans, R. intermedia, R. marginata, R. symmetrica, Pompholyxophrys punicea, P. exigua, and P. ovuligera, which were previously imperfectly known by light microscopy only.
Are brightly coloured male ducks selectively shot by duck hunters?
Authors: Metz Karen J. , Ankney C. Davison
Published: January 2008

In many species of ducks, males are harvested at higher rates than females. Several studies have suggested that particular aspects of the birds' biology may account for this difference, but few studies have attempted to determine the effect of hunter behaviour on the differential vulnerability. The objective of this study was to determine if the bright plumage of male ducks was related to greater hunting mortality. Ducks shot from pairs at Long Point Waterfowl Management Unit, Ontario, from September 25 to November 26, 1987, were examined, and questions were asked of hunters who brought the ducks into the Waterfowl Management Unit's check station. Sixty-one percent of ducks shot from pairs were mallards, green-winged teal, or ring-necked ducks. A significant interaction occurred between the degree of dichromatism of plumage and which sex of duck was shot. Approximately equal numbers of males and females were shot when males resembled females. However, when males obtained their full, bright, alternate plumage, a significantly greater proportion of males were shot regardless of which sex was leading. These data suggest that hunters select, consciously or unconsciously, the more distinctive male when he is accompanied by a female. Characteristics of hunters' behaviour while hunting are pertinent to assessing current waterfowl management programs.
Phallodrilus aquaedulcis Hrabě, 1960, a meiobenthic freshwater oligochaete (Tubificidae) previously known only from Europe, recorded from the Niagara River, North America
Authors: Farara Dennis G. , Erséus Christer
Published: January 2008

During a base-line investigation of benthic invertebrates of the Niagara River, North America, in 1983, a meiobenthic tubificid, Phallodrilus aquaedulcis, was discovered. The species was previously reported only from the River Weser in Germany, and from inland caves in Spain and France. Because the new specimens deviate morphologically from the original description, a redescription using the new material is presented.