Super-resolution microscopy reveals LINC complex recruitment at nuclear indentation sites.

Increasing evidences show that the actin cytoskeleton is a key parameter of the nuclear remodeling process in response to the modifications of cellular morphology. However, detailed information on the interaction between the actin cytoskeleton and the nuclear lamina was still lacking. We addressed this question by constraining endothelial cells on rectangular fibronectin-coated micropatterns and then using Structured Illumination Microscopy (SIM) to observe the interactions between actin stress fibers, nuclear lamina and LINC complexes at a super-resolution scale. Our results show that tension in apical actin stress fibers leads to deep nuclear indentations that significantly deform the nuclear lamina. Interestingly, indented nuclear zones are characterized by a local enrichment of LINC complexes, which anchor apical actin fibers to the nuclear lamina. Moreover, our findings indicate that nuclear indentations induce the formation of segregated domains of condensed chromatin. However, nuclear indentations and condensed chromatin domains are not irreversible processes and both can relax in absence of tension in apical actin stress fibers.

Anxiety in adult female mice following perinatal exposure to chlorpyrifos.

Epidemiologic studies suggested a possible link between prenatal exposure to organophosphate insecticides (OP) and long-term mental delay and some behavioral troubles. Experimental studies in rats and mice have confirmed that a relatively short exposure to low doses of OP such as chlorpyrifos (CPF) during specific perinatal periods decreased anxiety-like behaviors. In the present study, we report that chronic perinatal exposure (GD15-PND14) to low doses of CPF leads to an increase (and not a decrease) in anxiety-like behaviors of female mouse offspring. Pregnant or lactating female mice were exposed to CPF (0.2; 1; or 5 mg/kg day) by oral treatment during 18 consecutive days. Following a recovery period of several weeks, the anxiety of adult female offspring was determined using neurobehavioral tests (elevated plus-maze and light/dark box tests). Our results showed that CPF-exposed female offspring were more anxious than controls. In addition, the magnitude of anxiety profile alterations depended on the level of exposure to CPF during gestation and lactation with a maximal effect observed at the 1 mg/kg day dose. Our results confirm that OP exposure during the perinatal period can induce long-term alterations in mouse anxiety-like behaviors and suggest that the routes of administration and the duration of OP exposure during brain development may be factors to consider when studying the development of anxiety.

Effects of lesions of nucleus taeniae on appetitive and consummatory aspects of male sexual behavior in Japanese quail.

Neurochemical, hodological and functional criteria suggest that the nucleus taeniae and parts of the adjacent archistriatum represent the avian homologue of parts of the mammalian amygdaloid complex. It has been proposed in particular that the nucleus taeniae is the homologue of the mammalian medial amygdala. In male quail, relatively large lesions to the posterior/medial archistriatum selectively decrease the expression of appetitive sexual behavior in a manner reminiscent of similar manipulations involving the medial amygdala in mammals. We investigated the effects of discrete lesions restricted to nucleus taeniae and of lesions to an adjacent part of the archistriatum (pars intermedium ventralis, AIv) on the expression of appetitive (ASB) and consummatory (CSB) aspects of male sexual behavior. ASB was measured by a learned social proximity response (after copulation a male quail stands in front of a window providing visual access to a female) and by the frequency of rhythmic cloacal sphincter movements. CSB was assessed by the frequency of mount attempts (MA) and cloacal contact movements (CCM). Lesions confined to nucleus taeniae and to AIv did not influence the acquisition or the maintenance of the two responses indicative of ASB. In contrast, lesions of nucleus taeniae significantly increased the occurrence frequencies of MA and CCM when administered before the beginning of behavior testing and increased the frequency of MA only when performed on sexually experienced subjects. No effect of AIv lesions could be detected. The discrepancy between these results and previous experiments in quail might reflect procedural differences, but more probably differences in locations of the lesions that were restricted in the current study to the anterior part of taeniae. Those in the Thompson study were in the posterior part of this nucleus. These findings indicate that there is a larger degree of functional heterogeneity in the nucleus taeniae than previously thought. The effects of taeniae lesions suggest that this nucleus, similar to the medial amygdala in mammals, might be implicated in the control of sexual satiety.