Predatory behavior under monocular and binocular conditions in the semiterrestrial crab Neohelice granulata.

Introduction: Neohelice granulata crabs live in mudflats where they prey upon smaller crabs. Predatory behavior can be elicited in the laboratory by a dummy moving at ground level in an artificial arena. Previous research found that crabs do not use apparent dummy size nor its retinal speed as a criterion to initiate attacks, relying instead on actual size and distance to the target. To estimate the distance to an object on the ground, Neohelice could rely on angular declination below the horizon or, since they are broad-fronted with eye stalks far apart, on stereopsis. Unlike other animals, binocular vision does not widen the visual field of crabs since they already cover 360° monocularly. There exist nonetheless areas of the eye with increased resolution. Methods: We tested how predatory responses towards the dummy changed when animals' vision was monocular (one eye occluded by opaque black paint) compared to binocular. Results: Even though monocular crabs could still perform predatory behaviors, we found a steep reduction in the number of attacks. Predatory performance defined by the probability of completing the attacks and the success rate (the probability of making contact with the dummy once the attack was initiated) was impaired too. Monocular crabs tended to use frontal, ballistic jumps (lunge behavior) less, and the accuracy of those attacks was reduced. Monocular crabs used prey interception (moving toward the dummy while it approached the crab) more frequently, favoring attacks when the dummy was ipsilateral to the viewing eye. Instead, binocular crabs' responses were balanced in the right and left hemifields. Both groups mainly approached the dummy using the lateral field of view, securing speed of response. Conclusion: Although two eyes are not strictly necessary for eliciting predatory responses, binocularity is associated with more frequent and precise attacks.

Induction Versus Maintenance Immunosuppression After Intestinal Transplant: Determining Which Treatment Most Impacts Long-Term Patient And Graft Survival.

OBJECTIVES: Immunosuppressive strategies for intestinal transplant have changed over time. However, specific intestinal transplant-oriented protocols and reports on long-term maintenance regimens are scarce. Our objective was to evaluate the impact of 2 different initial immunosuppressive protocols based on thymoglobulin (group A) and basiliximab (anti-interleukin 2 antibody) (group B) and of changes to maintenance immunosuppression over long-term follow-up in intestinal transplant recipients. MATERIALS AND METHODS: We performed a retrospective analysis of a prospectively established protocol for intestinal transplant immunosuppression, conducted between May 2006 and December 2020. We analyzed 51 intestinal transplant recipients, with 6 patients excluded because of early death or graft loss. Acute cellular rejection frequency and grade, number of acute cellular rejection episodes, time to the first acute cellular rejection episode, response to treatment, number of patients who progressed to chronic allograft rejection, kidney function, infections, incidence of posttransplant lymphoproliferative disorder and graft-versus-host disease, and patient and graft survival were analyzed. RESULTS: In the study groups, there were 87 acute cellular rejection episodes in 45 patients (33 in group A and 54 in group B). We found degree of acute cellular rejection to be mild in 45 patients, moderate in 18, and severe in 24 (not significant between groups). Our comparison of induction therapy (thymoglobulin [group A] vs interleukin 2 antibody [group B]) did not show any statistical difference during clinical followup. Long-term review showed that all patients were on tacrolimus. Five-year patient and graft survival rates were 62% and 45% for group A and 54% and 46% for group B, respectively (not significant). CONCLUSIONS: Long-term patient and graft outcomes reflected the use of an individualized follow-up with adjustments and changes in immunosuppressive medications according to the patient's clinical course and complications rather than based on the induction immunosuppressive protocol used.

Evidence for effects on thermoregulation after acute oral exposure to type I and type II pyrethroids in infant rats.

Most pyrethroid (PYR) insecticides may be classified either as type-I compounds, which produce whole body tremors and hyperthermia, or type-II compounds, which produce salivation, choreoathetosis, and hypothermia (i.e., producing T and CS neurobehavioral syndromes, respectively). This classification is based on clinical observations in adult rats and mice after intracerebroventricular or intravascular administration of highly effective acute (bolus) doses. PYR neurotoxicity in infant animals is not characterized as much as in adult animals. Endpoints informing on vital determinants of mammal's maturation, such as body temperature may help recognizing age-related differences in susceptibility to PYRs. In this work, body temperature (Tb) was monitored at 30-min intervals after acute oral exposure to T-syndrome PYR bifenthrin (BIF), CS-syndrome PYR cypermethrin (CYPM), and a BIF­CYPM mixture in weanling rats by using a subcutaneous temperature monitoring system. In both single-compound assays, a time- and dose-related decline of Tb was the most evident impact on thermoregulation observed starting at ~2­3 h after dosing.Moreover, 15­18 mg/kg BIF induced a mild increase in Tb before the hypothermic action was apparent. The lowest effective dose for temperature perturbation was 15mg/kg for BIF and 10mg/kg for CYPM, and moderate neurobehavioral alterations were evident at 12 and 10mg/kg, respectively. When low effective doses of BIF and CYPM were co-administered mild behavioral effects and a transient increase in Tb (p=0.02) were observed at 1­2 h, and no Tb decline was apparent afterwards compared to control animals. Noteworthy, the hypothermic action of BIF in infant rats was quite different from the hyperthermia consistently reported in studies using mature animals. Our results suggest that body temperature monitoring may be useful as a complementary assessment to reveal qualitative age-specific pesticide effects in rats.

Elevated serotonin is involved in hyperactivity but not in the paradoxical effect of amphetamine in mice neonatally lesioned with 6-hydroxydopamine.

The neonatal lesion with 6-hydroxydopamine (6-OHDA) in rodents induces juvenile hyperactivity and paradoxical hypolocomotor response to psychostimulants, in striking contrast to what is observed when similar lesions are carried out in adults. The early disruption of central dopaminergic pathways is followed by increased striatal serotonin (5-HT) contents although the functional role of this neurodevelopmental adaptation remains unclear. The aim of the present study is to investigate the participation of this neurochemical imbalance in the main behavioral phenotypes of this model. To this end, mice received a neonatal administration of 6-OHDA that induced an 80% striatal dopamine depletion together with 70% increase in 5-HT. Serotoninergic hyperinnervation was evidenced further by increased [(3)H] citalopram autoradiographic binding and 5-HT transporter immunohistochemistry in striatal sections. To investigate whether elevated 5-HT was implicated in hyperactivity, we treated control and 6-OHDA neonatally lesioned mice with the selective irreversible tryptophan hydroxylase inhibitor p-chlorophenylalanine (PCPA) to induce 5-HT depletion. Normalization of striatal 5-HT in 6-OHDA neonatally lesioned mice to control levels reversed hyperactivity to normal locomotor scores, whereas the same extent of 5-HT depletion did not affect spontaneous locomotor activity of control mice. In turn, the paradoxical response to amphetamine in neonatal DA-depleted mice was not prevented by PCPA treatment. Taken together, our results suggest that the increased striatal 5-HT that follows neonatal DA depletion is involved in hyperlocomotor behavior but not in the paradoxical calming response to amphetamine observed in this mouse model.