Alejandro Moyaho

Grooming and yawning trace adjustment to unfamiliar environments in laboratory Sprague-Dawley rats ( Rattus norvegicus).

The authors studied grooming and yawning caused by mild stress in laboratory Sprague-Dawley rats (Rattus norvegicus). Two groups received 3 and 6 sequences of 5 foot shocks at random intervals (RI) and fixed intervals (FI), respectively. A 3rd group was not shocked (NS). The groups were exposed for 60 min twice. Grooming did not differ among groups, but yawning diminished with RI. Yawning increased and grooming decreased with the 2nd exposure, except in RI in which grooming increased. In NS and FI, grooming prevailed during the first 20 and 30 min, respectively, whereas yawning dominated the remainder of the time. In RI, grooming occurred more than yawning. An upward shift on this scale causes grooming to substitute yawning, whereas a downward shift causes the reverse effect.

Single Delivery of an Adeno-Associated Viral Construct to Transfer the CASQ2 Gene to Knock-In Mice Affected by Catecholaminergic Polymorphic Ventricular Tachycardia Is Able to Cure the Disease From Birth to Advanced Age

Background— Catecholaminergic polymorphic ventricular tachycardia is an inherited arrhythmogenic disorder characterized by sudden cardiac death in children. Drug therapy is still insufficient to provide full protection against cardiac arrest, and the use of implantable defibrillators in the pediatric population is limited by side effects. There is therefore a need to explore the curative potential of gene therapy for this disease. We investigated the efficacy and durability of viral gene transfer of the calsequestrin 2 (CASQ2) wild-type gene in a catecholaminergic polymorphic ventricular tachycardia knock-in mouse model carrying the CASQ2R33Q/R33Q (R33Q) mutation. Methods and Results— We engineered an adeno-associated viral vector serotype 9 (AAV9) containing cDNA of CASQ2 wild-type (AAV9-CASQ2) plus the green fluorescent protein (GFP) gene to infect newborn R33Q mice studied by in vivo and in vitro protocols at 6, 9, and 12 months to investigate the ability of the infection to prevent the disease and adult R33Q mice studied after 2 months to assess whether the AAV9-CASQ2 delivery could revert the catecholaminergic polymorphic ventricular tachycardia phenotype. In both protocols, we observed the restoration of physiological expression and interaction of CASQ2, junctin, and triadin; the rescue of electrophysiological and ultrastructural abnormalities in calcium release units present in R33Q mice; and the lack of life-threatening arrhythmias. Conclusions— Our data demonstrate that viral gene transfer of wild-type CASQ2 into the heart of R33Q mice prevents and reverts severe manifestations of catecholaminergic polymorphic ventricular tachycardia and that this curative effect lasts for 1 year after a single injection of the vector, thus posing the rationale for the design of a clinical trial.

Behavioral differences between selectively bred rats: D1 versus D2 receptors in yawning and grooming.

We used SKF 38393 and quinpirole for determining whether activation of D(1) and D(2) receptors, respectively, is involved in behaviors of rats selectively bred for high or low rates of yawning. After injection of SKF 38393, yawning diminished more markedly in high-yawning (HY) than in low-yawning (LY) rats, whereas this drug increased the number and duration of grooming episodes similarly in both strains. After injection of quinpirole, yawning increased more markedly in HY than in LY rats, whereas this drug decreased the number and duration of grooming episodes similarly in both rat strains. After coadministration of SKF 38393 and quinpirole, yawning increased similarly in both rat strains, whereas the combination of drugs failed to reliably affect grooming behavior. We interpret our findings as indicating that D(2) receptors are more important than D(1) receptors for differences in yawning behavior between HY and LY rats.

Inhibition of Grooming by Pilocarpine Differs in High- and Low-Yawning Sublines of Sprague-Dawley Rats

A comparative study of the effect of pilocarpine, a muscarinic receptor agonist, on grooming, scored during 45 min via a time-sampling procedure, was carried out on two sublines of male rats selectively bred for high-(HY) and low-yawning (LY) frequency. In one condition, we introduced rats in a novel cage and observed them immediately after receiving an I.P. injection of pilocarpine (0.5-3.75 mg/Kg) or an equivalent volume of saline. Besides grooming, the occurrence of yawns was continuously recorded. In the other condition, we immersed rats in water for 60 s, then they received an I.P. injection of pilocarpine (3.75 mg/Kg) or an equivalent volume of saline and we placed them in an open field, in which we recorded the number of crossed squares. Grooming scores were significantly higher in the condition after water immersion than in the novel situation; in both conditions HY had a grooming response higher than that of LY rats. Pilocarpine produced a dose-dependent inhibition of novelty-induced grooming in HY rats, whereas LY grooming was reduced only with the highest dose. In contrast, yawning increased in a dose-dependent manner with HY rats curve over that of LY animals, except for the highest dose. Pilocarpine inhibited water immersion-induced grooming in both sublines of rats, but it did not reduce grooming as much as it did in the novel condition. Pilocarpine affected distinctly each of the components of grooming, without inhibiting animals locomotor activity. The results indicate that HY rats also have a higher number of grooms than LY rats, and because grooming and yawning can appear after stressful circumstances, HY rats may be used to study the role that both behaviors could have in counteracting the effects of stress. Similarly, HY animals might be utilized to study the underlying neurochemical mechanisms of grooming. This study also indicates that the cholinergic systems exert an inhibitory influence on grooming which contrasts with the excitatory effect on yawning.

Predation risk is associated with the geographic variation of a sexually selected trait in a viviparous fish (Xenotoca variata)

Male secondary sexual traits may increase the risk of predation because mating signals make them conspicuous to predators and hamper evasive manoeuvres. Males of Xenotoca variata, a viviparous freshwater fish, show on their flanks bright and colourful spots (speckles), the number of which varies geographically. In this study, the association of this variation with the presence of the piscivorous snake Thamnophis melanogaster, which co-occurs with X. variata, was investigated. A test was also done to establish whether the snake distinguishes between male fish with contrasting numbers of speckles and if the perception of speckles is influenced by water turbidity. The amount of speckling and the prevalence of snakes in key localities was assessed by using one-way mirrors, and the effect of speckles on the predatory responsiveness of snakes was evaluated by presenting them with pairs of male fish in clear and in turbid water. In localities where snakes were infrequent there was a tendency for male fish to have many speckles. The snakes preferentially approached the males with more speckles than the males with fewer speckles. The direction of the preference did not change with the conditions of the water, but the magnitude was stronger in clear water than in turbid water. The snakes also approached first the males with more speckles. These findings indicate that predation risk by T. melanogaster may select against speckles and produce population differentiation.

Smell facilitates auditory contagious yawning in stranger rats

Most vertebrates yawn in situations ranging from relaxation to tension, but only humans and other primate species that show mental state attribution skills have been convincingly shown to display yawn contagion. Whether complex forms of empathy are necessary for yawn contagion to occur is still unclear. As empathy is a phylogenetically continuous trait, simple forms of empathy, such as emotional contagion, might be sufficient for non-primate species to show contagious yawning. In this study, we exposed pairs of male rats, which were selected for high yawning, with each other through a perforated wall and found that olfactory cues stimulated yawning, whereas visual cues inhibited it. Unexpectedly, cage-mate rats failed to show yawn contagion, although they did show correlated emotional reactivity. In contrast, stranger rats showed auditory contagious yawning and greater rates of smell-facilitated auditory contagious yawning, although they did not show correlated emotional reactivity. Strikingly, they did not show contagious yawning to rats from a low-yawning strain. These findings indicate that contagious yawning may be a widespread trait amongst vertebrates and that mechanisms other than empathy may be involved. We suggest that a communicatory function of yawning may be the mechanism responsible for yawn contagion in rats, as contagiousness was strain-specific and increased with olfactory cues, which are involved in mutual recognition.

Genotype-dependent effect of ACTH1–24 on grooming and yawning in two inbred strains of rats

It has long been known that the intracerebroventricular administration of ACTH1-24 increases the duration of grooming episodes and the frequency of yawning in rats. The objective of this study was to investigate in what way these episodes are prolonged and whether and to what extent genotype influences such effects. We compared the effect of increasing doses of intracerebroventricular injections of ACTH1-24 on grooming and yawning in males of two inbred strains of Sprague-Dawley rats with distinct yawning frequency, high-yawning (HY) and low-yawning (LY). In LY rats the duration of grooming episodes increased, while in HY rats grooming episodes augmented both in number and duration. In LY rats the duration of grooming components increased likewise, in HY rats however, neither the number nor the duration of the components changed. The grooming rate in both strains of rats was slowed, though more so in LY than in HY rats. Yawning increased in LY rats but not in HY rats. We conclude therefore that ACTH1-24 increases the duration of grooming episodes by slowing the grooming rate according to genotype, and may or may not alter the frequency of yawning.

Female vibration discourages male courtship behaviour in the Amarillo fish (Girardinichthys multiradiatus)

Amarillo fish females (Girardinichthys multiradiatus) vibrate when conspecific males approach them; the reason behind this behaviour is unclear. Hypotheses are that females vibrate either to avoid aggression from males or to court them. We prevented females from vibrating by temporarily blocking their lateral line organs and eyes, on the assumption that they rely on these senses to detect approaching males. Females with the lateral line organs obstructed vibrated less frequently than females with the lateral line intact, indicating that the mechanosensory lateral line system is necessary for perceiving approaching males. Males displayed more courtship behaviour to sighted females with the lateral line organs obstructed than to sighted females with the lateral line intact. A general tendency indicated that the less the females vibrated the more the males courted them. These findings indicate that female vibration discourages male courtship behaviour.

Genetic and littermate influences on yawning in two selectively bred strains of rats

This study was made to separate genetic from postnatal maternal influences on yawning in two strains of Sprague-Dawley rats selected for high- (HY) and low-yawning frequency (LY). Foster mothers of the two strains reared litters of pups in the four possible combinations and yawning was recorded in a novel environment when the adult offspring were 75-day-old. Yawning frequency of males and females was affected by pup strain but not by the strain of the foster mothers, when litter size was made constant; HY adult offspring yawned more than LY adult offspring. Yawning frequency was higher in HY male offspring than in HY female offspring. An interaction term between pup sex and the strain of the foster mothers revealed that while males reared by LY mothers yawned more than males reared by HY mothers, females reared by HY mothers yawned more than females reared by LY mothers. Mean frequency of yawning increased with the sex ratio of HY litters. These findings indicate that genetic and genotype-correlated littermate effects influence yawning frequency of adult offspring in response to a novel environment.

Females of a viviparous fish (Skiffia multipunctata) reject males with black colouration

This study investigated whether male body colour is a trait upon which females of Skiffiamultipunctata, a viviparous fish of the subfamily Goodeinae, base their choice of potential mate. About 60% of the males in the study had black patches on the sides of their bodies and/or dorsal fins. Patches varied in number, size and distribution. Most males (70% of the fish in the study) had diffuse orange colouration on their flanks, mainly on the peduncle. The hypothesis was that, after controlling for differences in body size, females would choose males with more black or orange colouration than males with less exaggerated patches of colour. However, in contrast to this hypothesis, females preferentially approached the males with less black colouration. Since orange colouration did not have a significant effect on female response, and there was no correlation between black and orange colours on the males in the study, females rejected males with more black colouration rather than preferring males with more orange or other visible colours. These findings indicate that sexual selection by female mate choice is not driving black or orange male body colouration in Skiffia multipunctata.