Bovine coronavirus in neonatal calf diarrhoea in Iran

Partial gene sequencing for the bovine coronavirus at the World Genebank is available for many countries, which are distributed unevenly in five continents, but so far, no sequencing of strains has been recorded in Iran. One hundred ninety-four stool samples from calves with diarrhoea less than one-month old were collected from five different geographical regions of country in order to detect coronavirus and characterize it if coronavirus was found. Samples were screened for the presence of BCoV by using a commercially available ELISA kit. Furthermore, RT-PCR was carried out on positive samples for confirmation of the presence of N and S specific genes. Sequencing and phylogenetic analysis was carried out following RT-PCR tests. 7.2% of samples, were positive for BCoV and all stool samples from the South-West, Northeast and West regions of Iran were negative. The results showed that all the strains of coronavirus identified in Iran were completely in independent clusters and that they did not stand in the same cluster as any of the strains identified in other parts of the world. The strains from Iran were quite different from strains in other parts of the world but from the point of similarity these viruses showed some similarities to the European strains, such as those found in France, Croatia, Denmark and Sweden

Bovine cryptosporidiosis: impact, host-parasite interaction and control strategies

International audienceAbstractGastrointestinal disease caused by the apicomplexan parasite Cryptosporidium parvum is one of the most important diseases of young ruminant livestock, particularly neonatal calves. Infected animals may suffer from profuse watery diarrhoea, dehydration and in severe cases death can occur. At present, effective therapeutic and preventative measures are not available and a better understanding of the host–pathogen interactions is required. Cryptosporidium parvum is also an important zoonotic pathogen causing severe disease in people, with young children being particularly vulnerable. Our knowledge of the immune responses induced by Cryptosporidium parasites in clinically relevant hosts is very limited. This review discusses the impact of bovine cryptosporidiosis and describes how a thorough understanding of the host–pathogen interactions may help to identify novel prevention and control strategies

Observation of optical pumping effects in collinear atomic beam - laser beam(s) interaction

The detection of optical resonances by observation of the fluorescence light emitted from a fast atomic beam of Na interacting with a collinear laser beam is limited in sensitivity by optical pumping processes. In the experiment reported here, we take advantage of the optical pumping by using a second collinear laser beam, achieving then a gain in fluorescence signal. The effects of the lasers power and polarization on line shapes have been studied in the single laser excitation case as well as in the two laser beams one.La sensibilite de la méthode de détection des résonances optiques par observation de la fluorescence émise par un jet rapide en excitation colineaire, est limitée par le pompage optique. Dans l' expérience décrite ici, nous tirons parti de ce pompage optique en détectant les résonances optiques à l'aide d'un second laser colinéaire, réalisant ainsi un gain sensible en signal de fluorescence. Les effets de la polarisation et de la puissance des faisceaux laser ont été étudiés aussi bien dans le cas de l'excitation d'atomes de Na par un seul laser que par deux lasers

Two methods for nuclear spin determination in collinear laser spectroscopy: classical rf magnetic resonance and observation of the Larmor precession

Measurement of nuclear spin in the collinear laser spectroscopy method has been investigated using a fast sodium atomic beam excited collinearly by a C.W. single mode dye laser beam. The atomic magnetic moments are first aligned by optical pumping process, then they interact with a static magnetic field H0. The magnetic alignment of the atomic system just at the exit of the magnetic field is monitored by the laser induced fluorescence. Upon varying the amplitude of H0, the fluorescence signal presents a fringed structure. This structure is due to the Larmor precession of the aligned magnetic moments around H0, and therefore it is a signature of the spin involved. The modulation patterns corresponding to different relative orientations of H0 and light polarization direction, are fitted by an analytical formula. In a second step, a classical magnetic resonance experiment with a static magnetic field and a radiofrequency field has been performed. The monocinetic character of our fast atomic beam allowed us to observe, even at high r.f. power, resonances line shapes in agreement with the Majorana formula.Nous décrivons des expériences de mesure de spin nucléaire, réalisées sur un jet atomique rapide de Na excité colinéairement par un laser à colorant continu et monomode. Deux méthodes ont été employées. Dans l'une d'elles, on fait interagir un champ magnétique statique H0 avec les atomes du jet dont les moments magnétiques ont été préalablement alignés par le pompage optique provoqué par la lumière. L'état magnétique du système atomique à la sortie du champ magnétique est analysé par l'intermédiaire de la fluorescence induite par le laser. Lorsque l'on fait varier l'amplitude de H0, le signal de fluorescence présente une structure de franges qui est due à la précession de Larmor des moments magnétiques autour de H0 ; cette structure dépend donc du spin nucléaire des atomes. Les signaux enregistrés pour différentes orientations relatives de H0 et de la direction de polarisation de la lumière s'accordent avec les résultats de calculs analytiques. La deuxième méthode est la méthode de résonance magnétique classique en présence d'un champ statique et d'un champ radiofréquence. A cause du caractère monocinétique de notre jet atomique rapide, nous avons pu observer, en champ r.f. fort, les profils de raies de résonance prévus par la théorie de Rabi et Majorana

Optical resonance detection by field ionization of Rydberg state in colinear laser spectroscopy

New efficient non-optical detection methods of optical resonances in colinear laser spectroscopy are described. A first method uses the field ionization of a Rydberg state populated by means of two lasers : one is single frequency and interacts colinearly with the fast atomic beam, the other one is multimode and interacts perpendicularly. By detecting, at resonance, the produced ions instead of the fluorescence photons, an overall efficiency of 1.1 x 10 -5 has been obtained, which is comparable to the usual sensitivity limit reached by the laser induced fluorescence method. A second similar experiment uses two single mode dye lasers both interacting colinearly with the fast atomic beam. Compared to the first technique an increase of the sensitivity by two orders of magnitude has been obtained (corresponding to an efficiency of 1.2 x 10- 3). Application to the study of on line produced short-lived isotopes is discussed.Deux nouvelles méthodes efficaces, et non optiques, de détection de résonance optique en spectroscopie colinéaire sont décrites. La première méthode utilise l'ionisation par champ d'un état de Rydberg peuplé à l'aide de deux lasers : le premier est monomode et interagit colinéairement avec le jet d'atomes rapides et le second est multimode et interagit perpendiculairement. En détectant, à la résonance, les ions produits à la place des photons de fluorescence, on obtient une efficacité de 1,1 x 10-5 qui est comparable à la limite de sensibilité habituellement atteinte par la méthode de fluorescence induite par laser. Une deuxième expérience similaire utilise deux lasers à colorant monomodes tous deux interagissant colinéairement avec le faisceau d'atomes rapides. Par comparaison avec la première méthode, on obtient un accroissement de la sensibilité de deux ordres de grandeur (correspondant à une efficacité de 1,2 x 10-3). L'application de ces méthodes à l'étude d'isotopes de courte durée de vie, produits en ligne, est examinée