Locomotory Behavior of Water Striders with Amputated Legs

The stability of the body during locomotion is a fundamental requirement for walking animals. The mechanisms that coordinate leg movement patterns are even more complex at water-air interfaces. Water striders are agile creatures on the water surface, but they can be vulnerable to leg damage, which can impair their movement. One can assume the presence of certain compensatory biomechanical factors that are involved in the maintenance of postural balance lost after an amputation. Here, we studied changes in load distribution among the legs and assessed the effects of amputation on the locomotory behavior and postural defects that may increase the risk of locomotion failure. Apparently, amputees recover a stable posture by applying leg position modifications (e.g., widening the stance) and by load redistribution to the remaining legs. Water striders showed steering failure after amputation in all cases. Amputations affected locomotion by (1) altering motion features (e.g., shorter swing duration of midlegs), (2) functional constraints on legs, (3) shorter travelled distances, and (4) stronger deviations in the locomotion path. The legs functionally interact with each other, and removal of one leg has detrimental effects on the others. This research may assist the bioinspired design of aquatic robots.

Nicotinic acetylcholine receptors of the dorsal hippocampus and the basolateral amygdala are involved in ethanol-induced conditioned place preference

The purpose of this study was to evaluate whether nicotinic acetylcholine receptors of the dorsal hippocampus and the basolateral amygdala (BLA) can potentiate ethanol response in the conditioned place preference (CPP) paradigm. I.p. administration of different doses of ethanol (0.25-1 g/kg) did not induce CPP. However, the higher dose of the drug (1.5 g/kg i.p.) induced place aversion. Furthermore, microinjection of nicotine (0.5-1 microg/rat) into both CA1 regions (intra-CA1) and the BLA (intra-BLA) did not produce a significant CPP. Interestingly, intra-CA1 or -BLA administration of nicotine plus ethanol (0.5 g/kg) during conditioning phase significantly induced a strong CPP. Microinjection of mecamylamine, the nicotinic acetylcholine receptor antagonist, into the CA1 regions or into the BLA did not alter CPP. However, intra-CA1 or -BLA microinjection of mecamylamine (1-4 microg/rat) reversed the response induced by the microinjection of nicotine (1 microg/rat, intra-CA1 or -BLA) plus ethanol (0.5 g/kg i.p.) in the CPP paradigm. On the other hand, the microinjection of nicotine (0.5-1.5 microg/rat) into the BLA, but not into the CA1 regions before the testing phase potentiated the response of ethanol on the expression of conditioned place preference. Moreover, intra-CA1 administration of nicotine plus ethanol increased the locomotor activity on the test day which was reversed by pretreatment with mecamylamine, while other treatments had no effect on locomotor activity. It can be concluded that the activation of nicotinic acetylcholine receptors of the dorsal hippocampus and the basolateral amygdala can potentiate the ethanol response in the CPP paradigm.

A study of intraspecies variations of Indian gerbil, Tatera indica Hardwicke, 1807 (Muridae, Rodentia) in Eastern Border of Iran

In this study, 93 specimens of adult Indian Gerbil (Tatera indica) were collected by live-trap from different localities of Eastern Border of Iran. Specimens were collected among 3 populations from Torbat-e-Jam, Sistan and Chabahar with North longitude 60 degrees-61.5 degrees and East latitude 25.50 degrees-35.50 degrees. At first, external and cranial characters were measured and then ratio of measured characters to head and body length were calculated. It showed that there are differences in characters of Indian gerbils in various latitudes while ratio of measured characters to head and body length were compared between these 3 populations. These differences are more obvious in Chabahar so that 16 from 23 characters are significantly higher than those in Torbat-e-Jam and Sistan and 3 characters are significantly lower than those from two other localities. Also, 4 characters have no significant difference in these populations. The result of MANCOVA showed that there are no significant differences between sexes. This study tries to shed some more light on the effect of climate changes and height on morphometric changes of Indian gerbil in Eastern border of Iran.