Interacting influence of light and size on aboveground biomass distribution in sub-boreal conifer saplings with contrasting shade tolerance

Plant size often influences shade tolerance but relatively few studies have considered the functional response of taller plants to contrasting light environments. Several boreal and sub-boreal Abies, Picea and Pinus species were studied along a light (0-90% full sunlight) and size (30-400-cm high) gradient to examine the interactive influence of tree size and light availability on aboveground biomass distribution. Sampling was conducted in two regions of Canada: (A) British Columbia, for Abies lasiocarpa (Hook.) Nutt., the Picea glauca (Moench.) Voss x P. engelmannii Parry ex. Engelm. complex and Pinus contorta Dougl. var. latifolia Engelm.; and (B) Quebec, for Abies balsamea (L.) Mill., Picea glauca (Moench. Voss) and Pinus banksiana (Lamb.). All biomass distribution traits investigated varied with size, and most showed a significant interaction with both size and light, which resulted in increasing divergences among light classes as size increased. For example, the proportion of needle mass decreased as size increased but the rate of decrease was much greater in saplings growing at below 10% full sunlight. Needle area ratio (total needle area:aboveground mass) followed a similar pattern, but decreased more rapidly with increasing tree size for small trees up to 1 m tall. The proportion of needle biomass (needle mass ratio) was always lower in taller trees (i.e., > 1 m tall) than in small trees (< 1 m tall) and increasingly so at the lowest solar irradiances (0-10% full sunlight). Thus, extrapolating the functional response to light from small seedling to taller individuals is not always appropriate.     

Residual toxicity of two insecticides on three field populations of Lygus lineolaris (Hemiptera: Miridae) collected along the St Lawrence valley in eastern Canada

Insecticides are still the single main pest control method employed today by most growers to mitigate damage done by the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae). In eastern Canada, the complex agricultural ecosystem, which may be described as a mosaic of farmlands dispersed among natural habitats (forest, prairies), allows tarnished plant bug adults to fly and move from sprayed to non-sprayed areas. In 2004 (late August to early September), three populations of L. lineolaris were collected from three mixed vegetation strips adjacent to orchards and vineyards along the St Lawrence valley: the Niagara Peninsula (Ontario), Dunham (Quebec) and La Pocatière (Quebec). Assays were done in the laboratory by confining adults in glass vials coated with dried residues. The estimated LC(50) values for the three populations varied from 11.2 to 16.8 x 10(-5) g L(-1) for azinphos-methyl and from 0.8 to 1.4 x 10(-5) g L(-1) for cypermethrin. In contrast to the Mississippi delta, no tolerance to insecticides was found in the populations collected. Possible explanations for this non-tolerance to insecticides includes a very low selection pressure as a result of the reduced number of insecticide treatments done in the context of the diversified agricultural landscapes encountered in eastern Canada which allow movements of adults from treated to non-treated areas.     

Crystal structure of the low-pH form of the vesicular stomatitis virus glycoprotein G

The vesicular stomatitis virus has an atypical membrane fusion glycoprotein (G) exhibiting a pH-dependent equilibrium between two forms at the virus surface. Membrane fusion is triggered during the transition from the high- to low-pH form. The structure of G in its low-pH form shows the classic hairpin conformation observed in all other fusion proteins in their postfusion conformation, in spite of a novel fold combining features of fusion proteins from classes I and II. The structure provides a framework for understanding the reversibility of the G conformational change. Unexpectedly, G is homologous to gB of herpesviruses, which raises important questions on viral evolution.     

Correlation between a proteolytic method and a radioimmunoassay for porcine serum pepsinogen concentrations

The measurement of serum pepsinogen concentrations by enzymatic method and immunoassay provides diagnostic values and should be helpful in the detection of gastric diseases related to a rise of blood pepsinogen. In the present study, the correlation between a conventional enzymatic method and a recently developed radioimmunoassay (RIA) for serum pepsinogen A was investigated. A total of 123 sera samples of porcine foetuses (n = 28), adult healthy pigs (n = 56), pigs with parakeratosis (n = 25) and pigs with ulceration of the pars oesophagea (n = 14) were tested. Overall, there was a slight correlation between the two methods (r = 0.60). In relation to individual animal groups, the correlations (r) were 0.39 (P>0.05), 0.74 (P<0.001), 0.19 (P>0.05) and 0.34 (P>0.05) in foetuses, healthy pigs, pigs with parakeratosis and pigs with ulcers, respectively. In both methods, pepsinogen concentrations (means+/-SE) were significantly higher (P<0.05) in pigs with parakeratosis (1778 +/- 86.00 mUTyr/L; 690 +/- 53.00 ng/mL) and in pigs with ulcers (2026 +/- 153.00 mUTyr/L; 1747 +/- 94.00 ng/mL) when compared to healthy pigs (935 +/- 58.00 mUTyr/L; 275 +/- 35.00 ng/mL). The proteolytic method gave a significant increased activity (P<0.05) in foetuses (1150 +/- 82.00 mUTyr/L) vs. (935 +/- 58.00 mUTyr/L) in healthy adult pigs, indicating an additional proteolytic activity in the sera of foetuses or neonates.     

Impact of storage position on oxygen ingress through different closures into wine bottles

Wine bottle aging is extremely dependent on the oxygen barrier properties of closures. Kinetics of oxygen ingress through different closures into bottles was measured by a nondestructive colorimetric method from 0.25 to 2.5 mL of oxygen. After 12, 24, and 36 months of storage, only the control (glass bottle ampule) was airtight. Other closures displayed different oxygen ingress rates, which were clearly influenced by the closure type and were independent of bottle storage position (upright, laid down) for most of the closures tested, at least during the first 24 months of the experiment under controlled conditions. The oxygen ingress rates into bottles were lowest in screw caps and "technical" corks, intermediate in conventional natural cork stoppers, and highest in the synthetic closures.     

Validation of an immunohistochemical assay for bovine cysticercosis, with comparison to a standard histological method

The larval stage (syn Cysticercus bovis) of the human tapeworm Taenia saginata causes cysticercosis in cattle, which has both aesthetic and food safety implications to consumers of beef. A monoclonal antibody-based immunohistochemical (IHC) assay developed to improve postmortem diagnosis of this parasite and a standard histological method were assessed to determine their fitness for intended use. Sections from 169 known-positive specimens of T. saginata from experimentally or naturally infected cattle, and from 30 known-negative specimens and lesions of various etiologies from non-infected cattle, were tested. The IHC assay identified significantly more known positive bovine cysticerci than the histological method (91.7% and 38.5%, respectively). Positive IHC staining occurred on sections from other cestode species, but should not affect the diagnostic specificity of this assay for bovine cysticercosis, due to the different host and/or tissue preferences amongst these parasites. Use of the IHC assay should improve the reliability of diagnosing lesions caused by degenerated cysticerci, facilitating more effective and efficient control of bovine cysticercosis.     

Sensitivity and specificity of radiography for detection of elbow incongruity in clinical patients

Elbow incongruity is an important factor regarding the treatment and prognosis of elbow dysplasia. Our purpose was to determine the sensitivity and specificity for radiographic detection of elbow incongruity in clinical patients, to establish inter- and intraobserver variation for different parameters, and to evaluate the possibility of radiographic grading of incongruity. Standard radiographic projections were acquired from 29 incongruent and nine congruent elbows of dogs of various ages and breeds. Computed tomography (CT) was used to diagnose and grade the incongruity. All radiographs were evaluated by four observers for detection and grading of elbow incongruity. Sensitivity, specificity, inter- and intraobserver variability were calculated. The mean sensitivity for detection of incongruity was very good (88.8%) with a mean specificity of 91.7%. Correct grading of incongruity was difficult. The radioulnar step and the widening of the humeroulnar and humeroradial joint space were seen most frequently. Intraobserver and interobserver variability were fair to excellent (Kappa = 0.372-0.809), depending on the investigated parameters. Radiography is valuable to screen for elbow incongruity. In over 91% of the patients, a clear distinction could be made between a congruent and an incongruent joint grading was not possible.     

In vitro validation of a new respiratory ultrasonic plethysmograph

Objective The in‐vitro validation of a novel Respiratory Ultrasonic Plethysmography (RUP) system designed to detect circumference changes of rib cage and abdominal compartments in large and small animals. Study design Experimental in vitro study. Methods The experimental system includes two compliant fluid‐filled rubber tubes functioning as ultrasonic waveguides. Each has an ultrasonic transmitter and a detector at the opposing ends. Sensor length can be individually adapted in the range of 0.15–2 m. Data are downloaded to a computer at a sampling rate of 10 or 100 Hz. Measurements have a resolution of 0.3 mm. Baseline stability, linearity and repeatability were investigated with dedicated experiments. The base line drift was tested measuring a fixed distance for 2 hours continuously and then 18 hours later. A hand‐operated horse thorax dummy (elliptically shaped, circumference 1.73 m) was used to compare waveforms of RUP with a respiratory inductive plethysmograph (RIP). The electromagnetic interference was tested by approaching metallic objects. Results Baseline drift and repeatability (10 repeated steps of 1.6% and 6.6% elongations and contractions) were within ± 0.3 mm. The response of the system for tube stretching up to 11% of total length was linear with a coefficient of determination for linearity of 0.998. In contrast to RIP, electromagnetic interference could not be observed with RUP. Conclusions and clinical relevance The low baseline drift and the lack of electromagnetic interference favours the use of RUP compared to an RIP device when studying the breathing pattern and end expiratory lung volume changes in conscious and anaesthetized animals.     

Anomalous Pregnancies during Late Embryonic/Early Foetal Period in High Producing Dairy Cows

This study analyses anomalous cases of gestation ending in pregnancy loss during the early foetal period and their effect on progesterone and plasma pregnancy-associated glycoprotein-1 (PAG-1) concentrations. Data derived from a large-scale ultrasound pregnancy diagnosis programme in high producing dairy cows. Over a 3-year period (2004–2007), a very low incidence (0.5%: 15 of 3094) of anomalous pregnancies was recorded. The results revealed that the following anomalies were detected on days 35–41 of gestation in cows carrying singletons with one single corpus luteum: embryo death in eight cows (0.3%); and embryo in the uterine horn contralateral to the corpus luteum in seven cows (0.2%). All these animals suffered pregnancy loss during the early foetal period. In cows carrying dead embryos, no signs of conceptus degeneration were observed on pregnancy diagnosis. Amnion size (approximately 25 mm diameter) and uterine horn fluid contents were estimated to be similar to those of the normal pregnant cows in this period. In the contralateral gestations, live embryos were observed in all ultrasound checks before pregnancy loss. Uterine fluid contents increased in the two cows in which gestation continued for more than a week. In the cases of embryo death but not in those of contralateral gestation, a drop in PAG-1 levels was noted prior to pregnancy loss. Two cows carrying dead embryos increased with time allantoic fluid contents. The PAG-1 values increased with time in one cow bearing a dead embryo (from 2.31 to 6.79 ng/ml) and in two of the contralateral gestations (from 1.66 to 2.33 ng/ml and from 0.39 to 6.79 ng/ml, respectively). Results of this study indicate that the foetal membranes continue to undergo some activity following embryo death, and that contralateral pregnancy may determine failure of the gestation process.