Endonucléases de restriction: isolement et identification d'une souche d'adénovirus canin de type 1

For the first time in Quebec, a type 1 canine adenovirus was isolated in cell culture and typed by restriction endonuclease analysis. This virus originated from the internal organs of a young dog killed by a severe respiratory disease without showing any sign of hepatitis.     

Shifting the natural spring–summer breeding season of the Australian freshwater crayfish Cherax quadricarinatus into the winter by environmental manipulations

Ninety sexually mature Cherax quadricarinatus females were exposed to various combinations of photoperiod and temperature for 2 months during the summer. Females were randomly assigned to either “winter” “semi-winter” or “summer” simulation treatments. In the “winter” treatment, crayfish were exposed to a simulated winter photoperiod (gradual decrease from 14L:10D to 10L:14D, 4 weeks at short day length followed by gradual increase to 14L:10D) and temperature (gradual decrease from 27 to 15 °C, held for 4 weeks, and then gradual increase to 27 °C). In the “semi-winter” treatment, crayfish were exposed to a simulated winter photoperiod and a summer temperature (27–29 °C). In the “summer” treatment, the crayfish were exposed to summer water temperatures and a photoperiod of 14L:10D. Following the 2 months of conditioning, the females were stocked for 7 months in small groups with males under environmental conditions similar to those of the “summer” treatment. All females were individually tagged and molting and spawning events were monitored. Females exposed to “semi-winter” conditioning in the summer, demonstrated a threefold increase in the rate of first spawning during the winter (December–February) compared with the other females. Crayfish breeders can easily implement these findings since shifting the breeding season into the winter only requires shortening of the photoperiod in the summer. The stocking of ponds in the spring with large nursed juveniles that hatched from eggs spawned in the winter, would allow the attainment of market size at the end of the limited growout season in temperate zones.     

Atmospheric bismuth-212: measurement and some geophysical applications

The concentrations of lead-212 and its short-lived daughter bismuth-212 in air near the ground were determined simultaneously by adaptation of the immersed-filter, delayed-coincidence technique of Assaf and Gat to measurement of the 3 x 10-(7)-second bismuth-212 and polonium-212 pair. The radioactive disequilibrium between lead-212 and bismuth-212 depends strongly on the efficiency of the ground in acting as a sink for these nuclides. This efficiency is low under dry conditions.     

Differences between tight and loose cultures: a 33-nation study

With data from 33 nations, we illustrate the differences between cultures that are tight (have many strong norms and a low tolerance of deviant behavior) versus loose (have weak social norms and a high tolerance of deviant behavior). Tightness-looseness is part of a complex, loosely integrated multilevel system that comprises distal ecological and historical threats (e.g., high population density, resource scarcity, a history of territorial conflict, and disease and environmental threats), broad versus narrow socialization in societal institutions (e.g., autocracy, media regulations), the strength of everyday recurring situations, and micro-level psychological affordances (e.g., prevention self-guides, high regulatory strength, need for structure). This research advances knowledge that can foster cross-cultural understanding in a world of increasing global interdependence and has implications for modeling cultural change.     

Concerns regarding the scientific evidence informing impact risk assessment and management recommendations for invasive birds

Invasive species can be a major threat to biodiversity and economy. Given the large number of introduced invasive species and the limited resources available, a rigorous assessment of the potential impact of these species is of vital importance for prioritizing management programs. Often, general scoring systems in which certain criteria are used to assess the impact of an invader along several impact categories are applied to obtain a ranking of troublesome invaders. Likewise, Kumschick and Nentwig (2010) provided a first categorization of invasive bird impacts in Europe, and argued that several invasive birds should be eradicated because of the threat they pose to biodiversity.This is surprising, as recent reviews suggest that there is little evidence that invasive birds strongly impact biodiversity. We therefore re-evaluated this risk assessment. We found that in the majority of cases, the evidence presented to support impact claims is weak, as they are generally not based on direct scientific research but on often anecdotal observations relating to small areas only. Moreover, even if all claims would materialize, this does not necessarily justify a call for eradication. Previous experiences with eradications have learnt that a feasibility study, encompassing all aspects of biological invasions (including public opinion and possible benefits of the invader) is critical for the achievement of any strategy against invasive species. This is essential, as ill-conceived calls for eradication could result in a public backlash, causing funding agencies and managers to shy away from the problems posed by invasive species.     

Use of electron microscopy and an enzyme-linked immunosorbent assay for the detection of rotaviruses in neonatal calf diarrhea.

Electron microscopy and an enzyme-linked immunosorbent assay were compared for the diagnosis of rotaviruses associated with neonatal calf diarrhea. One hundred percent correlation was observed when 125 samples were tested by both techniques. Both techniques were equally efficient in detecting rotaviruses. The enzyme-linked immunosorbent assay was more sensitive but being specific could not detect other viruses.     

Reducing preharvest drop of ‘Temple’ orange fruits by 2,4-D — Role of cellulase in the calyx abscission zone

One or two treatments of 2,4-D (18 p.p.m.) applied to ‘Temple’ orange trees during the last 6 weeks before the regular picking-period in late January, successfully reduced natural preharvest fruit abscission, allowing picking to be delayed by at least one month, and thus producing better external and internal fruit quality. It has been demonstrated for the first time that the delaying effect of auxin treatment on preharvest abscission was directly related to the decrease in the activity of endo- and exo-cellular cellulase. Most of the increase in cellulase activity during the abscission process was, however, due mainly to the activity of exo-cellular cellulase. When frost occurred a few days after application of 2,4-D, the auxin treatment significantly decreased total cellulase activity, thus reducing fruit abscission.The data proved that, except for the difference in the length of time between application and the onset of the hormone effect, the control mechanism of 2,4-D on abscission and on cellulase activity in intact fruit is similar to that previously reported for fruit explants.     

Serology of bovine parainfluenza virus type 3: comparison of the enzyme linked immunosorbent assay and hemagglutination inhibition.

An enzyme linked immunosorbent assay (ELISA) for the detection of antibody to bovine parainfluenza virus type 3 has been compared with the hemagglutination inhibition test on 130 field sera, and seven other paired sera showing a significant raise of titers. The ELISA was found to be four to 64 times more sensitive than the hemagglutination inhibition test and the two tests demonstrated a good correlation.     

Inner structures of some coronaviruses.

When treated with formaldehyde, Tween 80, sodium oleate and Nonidet P-40, avian infectious bronchitis virus, porcine transmissible gastroenteritis virus, neonatal calf diarrhea coronavirus, porcine hemagglutinating encephalomyelitis virus as well as the human coronavirus show similar inner structures by negative staining. The first one is an inner membranous bag. This structure could be evaginated following treatments used and does not show the characteristic projections of coronaviruses. Subsequently, the inner fold could be separated from the outer membrane at the point of junction between these two membranes. Each virus does not react in the same way to the action of the different products. The transmissible gastroenteritis virus appears more sensitive to treatments than other viruses. On the other hand, the hemagglutinating encephalomyelitis virus is the most resistant. The variable sensitivities of these viruses are not related to the type of host-cells. Also, a second internal structure, which is more dense than the viral particle, encircles partially the aperture of the internal tongue-shaped structure and seems to emerge from the viral particle through the aperture of the inner bag.     

Detection of bovine coronavirus and type A rotavirus in neonatal calf diarrhea and winter dysentery of cattle in Quebec: evaluation of three diagnostic methods.

The use of direct electron microscopy, enzyme-linked immunosorbent assay, and protein A-gold immunoelectron microscopy for the identification of bovine coronavirus and type A rotavirus were examined. Two hundred and forty-nine samples from diarrheic calves and winter dysenteric cattle from seven geographic areas in Quebec were examined for the presence of viruses by direct electron microscopy of negatively stained preparations. In addition, all the samples were analyzed by enzyme-linked immunosorbent assay, and a random selection of 47 samples were also analyzed by protein A-gold immunoelectron microscopy. Thirty-nine percent of samples examined by direct electron microscopy contained viral particles; bovine coronavirus and type A rotavirus were the most common viruses involved. Overall agreement between any two of the methods used compared favorably with results obtained by others using similar methods. The presence of coronavirus and rotavirus in fecal samples obtained from neonatal calves and the presence of coronavirus in samples from winter dysenteric adult cattle suggested their etiological roles in the respective diseases. Furthermore, results from protein A-gold immunoelectron microscopy of coronavirus-like particles implied that a different coronavirus or some other viruses might be involved in these diseases. Finally, the efficiency of direct electron microscopy, enzyme-linked immunosorbent assay and protein A-gold immunoelectron microscopy as diagnostic tools is discussed.