The impact of the insecticide chlorpyrifos (CPF) on the mammalian digestive system has been poorly described. The present study aimed at evaluating the effect of chronic, low-dose exposure to CPF on the composition of the gut microbiota in a Simulator of the Human Intestinal Microbial Ecosystem: the SHIME and in rats. The SHIME comprises six reactor vessels (stomach to colon). The colonic segments were inoculated with feces from healthy humans. Then, the simulator was exposed to a daily dose of 1 mg of CPF for 30 days. The changes over time in the populations of bacteria were examined at different time points: prior to pesticide exposure (as a control) and after exposure. In parallel, pregnant rats were gavaged daily with 1 mg/kg of CPF (or vehicle) until the pups were weaned. Next, the rats were gavaged with same dose of CPF until 60 days of age (adulthood). Then, samples of different parts of the digestive tract were collected under sterile conditions for microbiological assessment. Chronic, low-dose exposure to CPF in the SHIME and in the rat was found to induce dysbiosis in the microbial community with, in particular, proliferation of subpopulations of some strains and a decrease in the numbers of others bacteria. In compliance with European guidelines, the use of the SHIME in vitro tool would help to (1) elucidate the final health effect of toxic agents and (2) minimize (though not fully replace) animal testing. Indeed, certain parameters would still have to be studied further in vivo.

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The effects of 1,2-propanediol, a cryoprotectant used for the freezing of embryos, were tested on the organization of microtubules and microfilaments in mouse oocytes arrested in metaphase II. At low doses (less than or equal to 1.0 M), 1,2-propanediol induced disorganization of the meiotic spindle but at 1.5 M and higher, it stabilized the spindle. Cytoplasmic asters were observed at all doses tested. An extensive network of free microtubules was observed at 1.0 M and 2.0 M 1,2-propanediol, the former having the stronger disruptive effect on the spindle. Higher doses of 1,2-propanediol (greater than or equal to 1.5 M) caused the oocytes to form cytoplasmic blebs. These blebs lacked detectable cortical microfilaments. In contrast, the microfilament-rich area of the cell cortex overlying the meiotic spindle was not modified.

Lyme borreliosis is the most common tick-borne disease in the northern hemisphere. In Europe, it is transmitted by Ixodes ticks that carry bacteria belonging to the Borrelia burgdorferi sensu lato complex. The objective of this work was to explore eco-epidemiological factors of Lyme borreliosis in peri-urban forests of France (Sénart, Notre-Dame and Rambouillet). We investigated whether the introduction of Tamias sibiricus in Sénart could alter the density of infected ticks. Moreover, the density and tick infection were investigated according to the tree species found in various patches of Sénart forest. For this purpose, ticks were sampled during 3 years. In the Sénart forest, the density of nymph and adult ticks showed no significant difference between 2008, 2009 and 2011. The nymph density varied significantly as a function of the month of collection. Regarding the nymphs, a higher rate of infection and infected density were found in 2009. Plots with chipmunks (C) presented a lower density of both nymphs and adult ticks than plots without chipmunks (NC) did. A higher rate of infection of nymphs with Borrelia was seen in C plots. The prevalence of the various species of Borrelia was also found to vary between C and NC plots with the year of the collect. The presence of chestnut trees positively influenced the density of both nymphs and adults. The infected nymph density showed a significant difference depending on the peri-urban forest studied, Sénart being higher than Rambouillet. The prevalence of Borrelia species also differed between the various forests studied. Concerning the putative role that Tamias sibiricus may play in the transmission of Borrelia, our results suggest that its presence is correlated with a higher rate of infection of questing ticks by Borrelia genospecies and if its population increases, it could play a significant role in the risk of transmission of Lyme borreliosis.

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Fibronectin (FN) immunolocalization and ultrastructural observations of epidermal-dermal cell interactions during skin regeneration of the cichlid fish Hemichromis bimaculatus after scale removal were carried out for a healing period of 48 h. On control samples after scale removal, FN was localized on the surface of a thin cellular sheet, the scale-pocket lining (SPL), separating the dermis from the scale-associated cells. A layer of extracellular matrix, constituting a basement membrane, was observed on the SPL surface. Study of wound healing showed that in less than 1 h epithelial cells spread rapidly over the undamaged SPL surface on which FN was still present after the scale was removed. It appeared that this FN can be damaged or lost if the area is exposed to the exterior water for more than one hour. When epithelial continuity was re-established, an epithelial-SPL space was formed and was progressively filled by an electron-dense extracellular matrix. No basement membrane was defined until both tissues were separated by dermal cells about 30 h after the wound was inflicted. FN is detected in the epithelial-SPL interface from 12 h to 30 h after scale removal. Therefore, in normal skin, specific localization of FN in the interface between the scale-associated cells and the outer surface of the SPL cells can be implicated in the attachment between the scale and the SPL surface favoring a flexibility of scale movement during swimming. In addition, FN could play an important role as a major extracellular matrix protein during wound-healing after scale removal. fibronectin / fish skin / epidermal-dermal interactions / wound healing

The zygotic expression of the eve1 gene is restricted to the ventral and lateral cells of the marginal zone. At later stages, the mRNAs are localized in the most posterior part of the extending tail tip. An eve1 clone (pcZf14), containing a poly-A tail, has been isolated. In order to address eve1 gene function, pcZf14 transcript injections into zebrafish embryos have been performed. The injection into uncleaved eggs of a synthetic eve1 mRNA (12 pg), which encodes a protein of approximately 28 kd, produces embryos with anterior-posterior (A-P) axis defects and the formation of additional axial structures. The first category of 24 h phenotypes (87%) mainly displays a gradual decrease in anterior structures. This is comparable to previous phenotypes observed following Xhox3 messenger injection either in Xenopus or in zebrafish that have been classified according to the index of axis deficiency (zf-IAD). These phenotypes result in anomalies of the development of the neural keel, from microphthalmia to acephaly. The second category (13%) corresponds to the phenotypes described above together with truncal or caudal supernumerary structures. Additional truncal structures are the most prominent of these duplicated phenotypes, displaying a "zipper" shape of axial structures including neural keels and notochords. Caudal duplication presents no evident axis supernumerary structures. The observation of these phenotypes suggests an important role for the eve1 gene in mesodermal cell specification and in the development of the posterior region, and more particularly of the most posterior tail tip where endogenous eve1 messengers are found.