Oscillations and sparsening of odor representations in the mushroom body

In the insect olfactory system, oscillatory synchronization is functionally relevant and reflects the coherent activation of dynamic neural assemblies. We examined the role of such oscillatory synchronization in information transfer between networks in this system. The antennal lobe is the obligatory relay for olfactory afferent signals and generates oscillatory output. The mushroom body is responsible for formation and retrieval of olfactory and other memories. The format of odor representations differs significantly across these structures. Whereas representations are dense, dynamic, and seemingly redundant in the antennal lobe, they are sparse and carried by more selective neurons in the mushroom body. This transformation relies on a combination of oscillatory dynamics and intrinsic and circuit properties that act together to selectively filter and synthesize the output from the antennal lobe. These results provide direct support for the functional relevance of correlation codes and shed some light on the role of oscillatory synchronization in sensory networks.     

Normalization for sparse encoding of odors by a wide-field interneuron

Sparse coding presents practical advantages for sensory representations and memory storage. In the insect olfactory system, the representation of general odors is dense in the antennal lobes but sparse in the mushroom bodies, only one synapse downstream. In locusts, this transformation relies on the oscillatory structure of antennal lobe output, feed-forward inhibitory circuits, intrinsic properties of mushroom body neurons, and connectivity between antennal lobe and mushroom bodies. Here we show the existence of a normalizing negative-feedback loop within the mushroom body to maintain sparse output over a wide range of input conditions. This loop consists of an identifiable "giant" nonspiking inhibitory interneuron with ubiquitous connectivity and graded release properties.     

Correlates of diet quality in the Quebec population

OBJECTIVE: To determine the correlates of a high-fat diet in urban, suburban and rural areas of Quebec, Canada. DESIGN: A secondary analysis of data collected as part of a 5-year multi-factorial, multi-setting, community-intervention project. SETTING: Urban, suburban and rural settings of the province of Quebec, 1997. SUBJECTS: Data were analysed from a sample of 5214 participants (2227 males, 2987 females). A food-frequency questionnaire was completed and a global index of food quality was calculated. Logistic regression was used to identify correlates of a diet high in total fats, saturated fat and cholesterol. RESULTS: In both genders, lower level of education, smoking status, French and English languages compared with other languages spoken at home, and a rural environment were associated with poor diet quality. Having no intention to eat low-fat dairy products more often was associated with a high-fat diet. In men, obesity (body mass index >/=30 kg m(-2)) and absence of reported health problems were correlates of a high-fat diet, while, in women, lower physical activity was a correlate. CONCLUSIONS: Future health interventions in Quebec should target people with low education, smokers and those living in a rural environment. Obese men and sedentary women should have access to specific dietetic resources.     

Spaced plant evaluation of Mediterranean germplasm collections of perennial ryegrass

Summary A sample of 50 wild populations of perennial ryegrass (12 from northern Italy and 38 from Corsica) was tested with controls as spaced plant nurseries in two locations in France. Multivariate analyses, such as principal component analysis, hierarchical clustering and factorial discriminant analysis were used to describe the genetic variability of such Mediterranean material.On the whole, Mediterranean populations do not appear to be more promosing than the north European varieties. However, some populations from Corsica could be used to develop genetic resources for the Mediterranean area.The interest of each cluster is discussed and geographical repartition of clusters is shown on country maps.The factorial discriminant analysis gives a linear discriminant Fisher function which clearely discriminates two groups of populations according to their country of origin.     

IBD-based QTL detection in inbred pedigrees: A case study of cereal breeding programs

Mapping quantitative trait loci in plants is usually conducted using a population derived from a cross between two lines. The power of such QTL detection and mapping strategies and the estimation of the effects highly depend on the choice of the two parental lines. Thus, the QTL detected in such populations only represent a small part of the genetic architecture of the trait. Besides, the effects of only two alleles are characterized, which is of limited interest to the breeder. On the other hand, common pedigree breeding material remains unexploited for QTL mapping. From a pre-breeding perspective, the utilization of the good quality phenotypic data generated by breeders can be improved through the search and manipulation of QTL. The development of statistical techniques suitable for QTL mapping in general conventional breeding populations is thus challenging. In this study, we extend QTL mapping methodology to a generalized framework, based on a two-step IBD variance component approach, applicable to any type of breeding population coming from inbred parents. The proposed developments attempt to make full use of any inferable relatedness information between the parents. The power and accuracy of this method were assessed on simulated data mimicking conventional breeding programs in cereals, in an effort to reproduce actual conditions of marker and gene allelic frequencies across the parental lines. A wide range of breeding scenarios and of genetic architectures was explored. We demonstrated that taking into account the estimable relatedness between the parents significantly improved the power and accuracy of the QTL parameter estimations. This revised version was published online in July 2006 with corrections to the Cover Date.     

The detection of snail host habitats in liver fluke infected farms by use of plant indicators

Field investigations in 361 liver fluke infected cattle- or sheep-breeding farms on acid soil were carried out during thirty years in March and April to record indicator plants in relation to the category of site colonized by the intermediate host of liver fluke, the snail Galba truncatula. Seven types of snail zones and six species of indicator plants were recorded in the 7709 positive sites studied. The most frequent habitats were located at the peripheral extremities of open drainage furrows. Juncus acutiflorus, Juncus effusus, Glyceria fluitans, and Agrostis stolonifera were the indicator plants. Plant indicators were highly efficient (38-80% of variance explained) when used with the size of site area within a hydrographical zone. The identification of positive sites for G. truncatula is a key for controlling the intermediate host on pastures through biological control with predatory molluscs. The positive sites may be detected using a two-step method including first categorization of hydrographical zones and then, within a zone, use of one or several indicator plants (frequently J. acutiflorus).     

Combination Allopurinol and Antimony Treatment versus Antimony Alone and Allopurinol Alone in the Treatment of Canine Leishmaniasis (96 Cases)

The aim of the present study was to evaluate the long-term clinical outcome for dogs with leishmaniasis that were treated with 3 different protocols: combined treatment with antimony and allopurinol, antimony alone, or allopurinol alone. Ninety-six dogs included in this study were determined to have leishmaniasis on the basis of (1) clinical features, (2) identification of the parasite in smears of lymph node, bone marrow aspirates, or skin biopsies, and (3) specific immunofluorescent assay. Three groups of dogs were defined: 45 dogs (group 1) were treated with antimony (100 mg/kg s.c. q24h) given concurrently for 1 month with allopurinol (15 mg/kg p.o. q12h), and then allopurinol alone for 8 months at the same dosage; 40 dogs (group 2) were treated with antimony alone according to the manufacturer's instructions (200 mg/kg s.c. q24h at 2-day intervals for 3-6 months); and 11 dogs (group 3) were treated with allopurinol alone (15 mg/kg p.o. q12h for 1-20 months). Information concerning signalment, history, physical examination findings, serologic testing and number of dogs becoming seronegative, outcome for each treated dog (clinical cure versus failure), and long-term survival were recorded. The numbers of the clinical cures versus failures were significantly different among the 3 groups (chi2 = 17.77, P < .001), between groups 1 and 2 (chi2 = 8.02, P < .01), between groups 2 and 3 (chi2 = 11.00, P < .01), and between groups 1 and 3 (chi2 = 16.52, P < .001). No significant difference between groups 1 and 2 was noted in the type of failure (relapse or death), serologic test results, and number of survival years (chi2 = 2.79, P > .05). The results of the present study indicate that antimony in combination with allopurinol produces better results than antimony alone or allopurinol alone for the treatment of the canine leishmaniasis. With combination treatment, duration of treatment with antimony is shorter and long-term administration of allopurinol is well tolerated.     

Macro‐geographical differences influenced by family‐based expression on cultured pearl grade,shape and colour in the black‐lip ‘pearl oyster’ Pinctada margaritifera: a preliminary bi‐local case study in French Polynesia

In French Polynesia, the aquaculture of Pinctada margaritifera is carried out in numerous grow‐out sites, located over three archipelagos (Gambier, Society and Tuamotu). To evaluate the impact of macro‐geographical effects of these growing sites on pearl quality traits, five hatcheries produced families were used as homogeneous donor oysters in an experimental graft. The molluscs were then reared in two commercial locations: Tahaa Island (Society) and Rangiroa atoll (Tuamotu). At harvest, eight pearl quality traits were recorded and compared: surface defects, lustre, grade, circles, shape categories, darkness level, body and secondary colour and visual colour categories. Overall inter‐site comparison revealed that: (1) all traits were affected by grow‐out location except for lustre and round shape, and (2) a higher mean rate of valuable pearls was produced in Rangiroa. Indeed, for pearl grade, Rangiroa showed twice as many A‐B and less reject samples than Tahaa. This was related to the number of surface defects (grade component): in Rangiroa, twice as many pearls had no defects and less pearls had up to 10 defects. Concerning pearl shape, more circled and baroque pearls were found in Tahaa (+10%). For colour variation, 10% more pearls have an attractive green overtone in Rangiroa than in Tahaa, where more grey body colour were harvested. Lustre does not seem to be affected by these two culture site (except at a family scale). This is the first time P. margaritifera donor family have been shown to vary in the quality of pearls they produce depending on their grow‐out location.