Staphylococcus aureus proteins differentially recognized by the ovine immune response in mastitis or nasal carriage

Staphylococcus aureus is an opportunistic pathogen in dairy ruminants where it is found in healthy carriage and can be a major cause of mastitis. A better knowledge of the host-pathogen interactions is needed to tackle this serious animal health problem. This study aimed at identifying S. aureus proteins differentially expressed by S. aureus in nasal colonization versus mastitis. Serological proteome analysis (SERPA) was used to examine protein samples prepared from culture supernatants of S. aureus strains originally isolated from gangrenous mastitis and nasal carriage (O11) or subclinical mastitis (O46) and to compare patterns of immune-reactive proteins. These staphylococcal proteins were revealed by sera obtained from ewes suffering from S. aureus mastitis and by sera obtained from healthy nulliparous ewes (i.e. no lactation and no mastitis or other symptoms) that were nasally colonized by S. aureus. Altogether 49 staphylococcal immune-reactive proteins were identified in this study. Patterns of proteins revealed by sera from infected- or healthy carrier- animals were comparable and analysis singled out one immune-reactive protein, N-acetylmuramyl-L-alanine amidase, which was recognized by each of the 6 sera from infected animals, when tested individually, and not by the sera of healthy carriers. This is the first study that compares the S. aureus seroproteome in colonization versus mastitis context in ruminants. These results open avenues for studies aiming at a better understanding of the balance between infection and commensal lifestyle in this opportunistic pathogen and at new prevention strategies.     

Generating optical Schrödinger kittens for quantum information processing

We present a detailed experimental analysis of a free-propagating light pulse prepared in a "Schr?dinger kitten" state, which is defined as a quantum superposition of "classical" coherent states with small amplitudes. This kitten state is generated by subtracting one photon from a squeezed vacuum beam, and it clearly presents a negative Wigner function. The predicted influence of the experimental parameters is in excellent agreement with the experimental results. The amplitude of the coherent states can be amplified to transform our "Schr?dinger kittens" into bigger Schr?dinger cats, providing an essential tool for quantum information processing.     

Penetrating ocular gunshot injury in a Labrador Retriever

A 3½‐year‐old, female (spayed) working black Labrador Retriever was referred to the Unit of Comparative Ophthalmology at the Animal Health Trust after a penetrating lead gunshot injury to the right eye. Clinical examination revealed penetrating injuries to the right cornea, left lateral canthus, and left forelimb. Radiography revealed the presence of multiple metallic foreign bodies in the head and one in the left forelimb. B‐mode ocular ultrasonography confirmed the presence of an intraocular metallic foreign body within the posterior tunics of the right eye. Medical treatment of the right eye over a period of 1 month resulted in a comfortable, visual eye. Long‐term follow‐up over 4½ years revealed a slow deterioration in vision because of progressive lens opacification and the presence of a localized area of chorioretinopathy.     

Ouch! A cross‐sectional study investigating self‐reported human exposure to dog bites in rural and urban households in southern Ontario,Canada

This study investigated self‐reported dog bites in humans in rural and urban households in southern Ontario, Canada. Our objectives were to determine, and compare, the incidence of dog bites in rural and urban households, and to describe the profile of bite victims, biting dogs, and the proportion of biting dogs that respondents self‐reported as being not up to date on rabies vaccination. We conducted a cross‐sectional observational study using an online questionnaire. The 2,006 respondents, each representing one household, included 1,002 rural and 1,004 urban residences. The incidence risk of at least one person in the household being bitten over the previous year in rural households (6.09% per year) was less than in urban households (10.76% per year). In 53.20% of households from which at least one person had been bitten within the past year, only a single person had been bitten. Mostly, victims were 25 to 34 years old (21.67%), male (54.19%), and playing with or interacting with the biting dog at the time of the incident (59.11%). Most biting dogs were 3 to 5 years old (32.02%), males (53.69%), and unleashed (76.85%). Based on self‐reporting by respondents, 83.33% of respondent‐owned biting dogs were vaccinated against rabies at the time of the biting incident. Irrespective of dog ownership, the odds of an individual in a rural household being bitten by a dog were 0.53 (95% CI: 0.38–0.73) the odds for an individual in an urban household. Dog bites constitute a serious, yet preventable, public health concern that requires targeted, community‐specific efforts. Public health organizations could consider findings in developing messaging, particularly as we highlight biting dogs reported by their owners as not up to date on rabies vaccination.     

Assessment of selenium bioavailability from high-selenium spirulina subfractions in selenium-deficient rats

It was previously found that the bioavailability of Se from Se-rich spirulina (SeSp) was lower than that from selenite or selenomethionine when fed to Se-deficient rats. The present study examined the bioavailability of Se from SeSp subfractions: a pellet (P) issuing from the centrifugation of a suspension of broken SeSp and a retentate (R) resulting from ultrafiltration of the supernatant through a 30 kDa exclusion membrane. Animals were fed a torula yeast based diet with no Se (deficients) or supplemented with 75 microg of Se/kg of diet as sodium selenite (controls) for 42 days. Se-deficient rats were then repleted for 56 days with Se (75 microg/kg of diet) supplied as sodium selenite, SeSp, P, or R. During this period, controls continued to receive sodium selenite. Speciation of Se in subfractions showed that the majority was present in the form of high molecular weight compounds; free selenomethionine was only a minor constituent. Gross absorption of Se from sodium selenite, P, and R was not different and was higher than from SeSp. Only retentate allowed full replenishment of Se concentration in liver and kidney (as did sodium selenite) and glutathione peroxidase (GSHPx) activity in liver, kidney, plasma, and erythrocytes. The bioavailabilities of Se in retentate, as assessed by slope ratio analysis using selenite as a reference Se, were 89 and 112% in the tissue Se content and 106-133% in the GSHPx activities. SeSp and P exhibited a gross bioavailability of <100%. These results indicate that Se in retentate is highly bioavailable and represents an interesting source of Se for food supplementation.     

Focusing beyond the diffraction limit with far-field time reversal

We present an approach for subwavelength focusing of microwaves using both a time-reversal mirror placed in the far field and a random distribution of scatterers placed in the near field of the focusing point. The far-field time-reversal mirror is used to build the time-reversed wave field, which interacts with the random medium to regenerate not only the propagating waves but also the evanescent waves required to refocus below the diffraction limit. Focal spots as small as one-thirtieth of a wavelength are described. We present one example of an application to telecommunications, which shows enhancement of the information transmission rate by a factor of 3.     

Contribution of the life-history traits of a plant pathogen to the development of field epidemics

The pathogenicity-related traits of biotrophic plant pathogens are usually measured on the individual host plant, at the scale of a single pathogen life cycle, whereas epidemic development in the field encompasses a succession of cycles. It remains unclear which traits make the greatest contribution to pathogen fitness in the field and to epidemic severity. The objective of this study was to determine the contributions of elementary pathogenicity traits to epidemic development in field conditions. We challenged a set of wheat cultivars with three different leaf rust isolates, under both controlled and field conditions, in 3 consecutive years. Infection efficiency, latent period, lesion size, spore production per lesion and spore production capacity were measured in the greenhouse, whereas disease severity was measured in the field. Most, but not all, of the pathogenicity traits were related to each other. All traits contributed to epidemic development in the field, but to different extents. Surprisingly, lesion size and spore production per lesion were inversely correlated with epidemic severity. Conversely, there was a strong positive correlation between spore production capacity and pathogen fitness in the field, in accordance with the concept of propagule pressure as a strong determinant of invasion success. Severe epidemics were mostly associated with small lesions with a high spore production capacity, high infection efficiency and a short latent period.     

Grueneberg ganglion cells mediate alarm pheromone detection in mice

Alarm pheromones (APs) are widely used throughout the plant and animal kingdoms. Species such as fish, insects, and mammals signal danger to conspecifics by releasing volatile alarm molecules. Thus far, neither the chemicals, their bodily source, nor the sensory system involved in their detection have been isolated or identified in mammals. We found that APs are recognized by the Grueneberg ganglion (GG), a recently discovered olfactory subsystem. We showed with electron microscopy that GG neurons bear primary cilia, with cell bodies ensheathed by glial cells. APs evoked calcium responses in GG neurons in vitro and induced freezing behavior in vivo, which completely disappeared when the GG degenerated after axotomy. We conclude that mice detect APs through the activation of olfactory GG neurons.