F. Dessi - Academia.edu (original) (raw)
Papers by F. Dessi
Italian Journal of Zoology, 2009
Genetica, 2010
In sexually dimorphic species, partners can assess heritable mate quality by analyzing costly sex... more In sexually dimorphic species, partners can assess heritable mate quality by analyzing costly sexual ornaments in terms of their dimension and possibly of their symmetry. In vertebrates an important aspect of genetic quality is the efficiency of the immune system, and in particular the Major Histocompatibility Complex (MHC). If ornaments are honest advertisements of pathogen resistance (good genes), in line with the Hamilton-Zuk hypothesis, a correlation between ornament expression and MHC profiles should exist. We tested this hypothesis in the common pheasant Phasianus colchicus by comparing male ornament characteristics (wattle and spur size, and wattle fluctuating asymmetry) with a portion of exon 2 of the class IIB MHC genes containing 19 putative antigen recognition sites. A total of 8 new alleles was observed in the MHCPhco exon IIB. We found significant differences in the occurrence of MHC genotypes between males carrying large or small wattles. Homozygous genotypes predicted large wattle males more correctly than small wattle males. The association between the dimension of the spur and the occurrence of MHC genotypes was marginally significant, however, we did not find any significant association between MHC genotypes and asymmetry. Our results suggest that female pheasants may use the ornament size as a cue to evaluate male quality and thus choose males carrying particular MHC profiles.
Ethology Ecology & Evolution, 2007
Recent studies suggest that atrazine (ATZ), a triazine herbicide widely used and frequently detec... more Recent studies suggest that atrazine (ATZ), a triazine herbicide widely used and frequently detected in ground and surface water, is able to affect estrogen production by inducing aromatase, the enzyme that converts androgen into estrogen, an essential transformation occurring at the CNS level for maturation and expression of behaviour. In the present study we evaluated the effects of environmentally relevant doses of ATZ on somatic growth and early behavioural ontogeny, a crucial stage in shaping future behaviour. For this purpose we observed mice born to mothers exposed to 1 or 100 µg/kg ATZ during pregnancy and lactation. We studied, between postnatal day 2 to 15, the righting reflex, cliff aversion, forepaw grasping, auditory startle, eyelid and ear opening, and ultrasound vocalizations. In both sexes ATZ effects were evident, on body weight at birth, on the maturation of righting and grasping reflexes, and on the rate of emission and the spectrographic characteristics of ultrasound vocalizations. Dosage level appeared to be particularly relevant because, in some cases, the lower ATZ exposure was more effective than the higher one in modifying behavioural response. The latter finding suggests that this compound, similarly to many others endocrine disruptors, does not follow a linear dose-response curve, and that, as a consequence, its effects should be studied carefully at very low doses. Our results, compatible with ATZ properties, suggest caution in the use of a chemical agent that may, even at low doses, interfere with brain development and differentiation, inducing alterations of the developmental trajectories of behaviours. key worDs: atrazine, neonatal behaviour, vocalizations, mice, endocrine disruptors, aromatase.
It has now been established that a large number of man-made and natural chemicals are capable of ... more It has now been established that a large number of man-made and natural chemicals are capable of interfering with the action of natural hormones. In this category ''endocrine disruptors'' such as the herbicide atrazine, when administered at ecological low doses (1 or 100 mg/kg per day) from gestational day 14 to postnatal day 21, provided a clear dimorphic neurodegenerative pattern in some brain areas of the domestic mouse (Mus musculus). Indeed, the high concentration (100 mg/kg per day) with respect to the low concentration (1 mg/kg per day) induced relevant neuronal damage in extrahypothalamic sites, such as the cortical and striatal areas in both sexes. Marked alterations in other areas, including the hippocampal and hypothalamic nuclei, were mostly typical of the female. At the neuronal level, the neuropeptide somatostatin, specific for the secretion of growth hormone, seemed to be a major target of atrazine effects, as demonstrated by evident subtype 2,3,5 receptor mRNA differences of this neuropeptide, at least for the first two subtypes. In particular, a very strong ( p < 0.001) upregulation of subtype 2 expressing neurons was detected in female hypothalamic areas, specifically the suprachiasmatic nucleus, whereas a similar downregulatory trend was reported for some extrahypothalamic areas such as the striatum. Interestingly, very strong upregulatory and downregulatory actions were detected for neurons expressing subtype 3 in male hypothalamic and amygdalar regions and in the cortical and hippocampal areas, respectively. Overall, it appears that these first neurotoxicological effects of atrazine are very likely linked to dimorphic expression patterns of specific somatostatin subtypes in discrete but key hypothalamic and extrahypothalamic areas of Mus musculus.
Animal Behaviour
Aggression is potentially disruptive for social groups. Although individuals witnessing a conflic... more Aggression is potentially disruptive for social groups. Although individuals witnessing a conflict are not directly threatened by aggressive interactions, the aftermath of aggression appears to be a period of social instability. We expected bystanders to respond to conflicts by affiliating with other group members and so reducing social tension. To test this hypothesis we collected data on two captive groups of Tonkean macaques, Macaca tonkeana. After an agonistic interaction, the behaviours of focal individuals uninvolved in the conflict were recorded over 5 min postconflict periods, for comparison with baseline periods. The results showed that bystanders were more likely to show affiliation during postconflict periods than in baselines. We found that affiliation occurred more frequently between individuals linked by friendship, whereas no significant effect of kinship appeared, which may be related to the open social relationships reported in Tonkean macaques. Females initiated af...
Italian Journal of Zoology, 2009
Genetica, 2010
In sexually dimorphic species, partners can assess heritable mate quality by analyzing costly sex... more In sexually dimorphic species, partners can assess heritable mate quality by analyzing costly sexual ornaments in terms of their dimension and possibly of their symmetry. In vertebrates an important aspect of genetic quality is the efficiency of the immune system, and in particular the Major Histocompatibility Complex (MHC). If ornaments are honest advertisements of pathogen resistance (good genes), in line with the Hamilton-Zuk hypothesis, a correlation between ornament expression and MHC profiles should exist. We tested this hypothesis in the common pheasant Phasianus colchicus by comparing male ornament characteristics (wattle and spur size, and wattle fluctuating asymmetry) with a portion of exon 2 of the class IIB MHC genes containing 19 putative antigen recognition sites. A total of 8 new alleles was observed in the MHCPhco exon IIB. We found significant differences in the occurrence of MHC genotypes between males carrying large or small wattles. Homozygous genotypes predicted large wattle males more correctly than small wattle males. The association between the dimension of the spur and the occurrence of MHC genotypes was marginally significant, however, we did not find any significant association between MHC genotypes and asymmetry. Our results suggest that female pheasants may use the ornament size as a cue to evaluate male quality and thus choose males carrying particular MHC profiles.
Ethology Ecology & Evolution, 2007
Recent studies suggest that atrazine (ATZ), a triazine herbicide widely used and frequently detec... more Recent studies suggest that atrazine (ATZ), a triazine herbicide widely used and frequently detected in ground and surface water, is able to affect estrogen production by inducing aromatase, the enzyme that converts androgen into estrogen, an essential transformation occurring at the CNS level for maturation and expression of behaviour. In the present study we evaluated the effects of environmentally relevant doses of ATZ on somatic growth and early behavioural ontogeny, a crucial stage in shaping future behaviour. For this purpose we observed mice born to mothers exposed to 1 or 100 µg/kg ATZ during pregnancy and lactation. We studied, between postnatal day 2 to 15, the righting reflex, cliff aversion, forepaw grasping, auditory startle, eyelid and ear opening, and ultrasound vocalizations. In both sexes ATZ effects were evident, on body weight at birth, on the maturation of righting and grasping reflexes, and on the rate of emission and the spectrographic characteristics of ultrasound vocalizations. Dosage level appeared to be particularly relevant because, in some cases, the lower ATZ exposure was more effective than the higher one in modifying behavioural response. The latter finding suggests that this compound, similarly to many others endocrine disruptors, does not follow a linear dose-response curve, and that, as a consequence, its effects should be studied carefully at very low doses. Our results, compatible with ATZ properties, suggest caution in the use of a chemical agent that may, even at low doses, interfere with brain development and differentiation, inducing alterations of the developmental trajectories of behaviours. key worDs: atrazine, neonatal behaviour, vocalizations, mice, endocrine disruptors, aromatase.
It has now been established that a large number of man-made and natural chemicals are capable of ... more It has now been established that a large number of man-made and natural chemicals are capable of interfering with the action of natural hormones. In this category ''endocrine disruptors'' such as the herbicide atrazine, when administered at ecological low doses (1 or 100 mg/kg per day) from gestational day 14 to postnatal day 21, provided a clear dimorphic neurodegenerative pattern in some brain areas of the domestic mouse (Mus musculus). Indeed, the high concentration (100 mg/kg per day) with respect to the low concentration (1 mg/kg per day) induced relevant neuronal damage in extrahypothalamic sites, such as the cortical and striatal areas in both sexes. Marked alterations in other areas, including the hippocampal and hypothalamic nuclei, were mostly typical of the female. At the neuronal level, the neuropeptide somatostatin, specific for the secretion of growth hormone, seemed to be a major target of atrazine effects, as demonstrated by evident subtype 2,3,5 receptor mRNA differences of this neuropeptide, at least for the first two subtypes. In particular, a very strong ( p < 0.001) upregulation of subtype 2 expressing neurons was detected in female hypothalamic areas, specifically the suprachiasmatic nucleus, whereas a similar downregulatory trend was reported for some extrahypothalamic areas such as the striatum. Interestingly, very strong upregulatory and downregulatory actions were detected for neurons expressing subtype 3 in male hypothalamic and amygdalar regions and in the cortical and hippocampal areas, respectively. Overall, it appears that these first neurotoxicological effects of atrazine are very likely linked to dimorphic expression patterns of specific somatostatin subtypes in discrete but key hypothalamic and extrahypothalamic areas of Mus musculus.
Animal Behaviour
Aggression is potentially disruptive for social groups. Although individuals witnessing a conflic... more Aggression is potentially disruptive for social groups. Although individuals witnessing a conflict are not directly threatened by aggressive interactions, the aftermath of aggression appears to be a period of social instability. We expected bystanders to respond to conflicts by affiliating with other group members and so reducing social tension. To test this hypothesis we collected data on two captive groups of Tonkean macaques, Macaca tonkeana. After an agonistic interaction, the behaviours of focal individuals uninvolved in the conflict were recorded over 5 min postconflict periods, for comparison with baseline periods. The results showed that bystanders were more likely to show affiliation during postconflict periods than in baselines. We found that affiliation occurred more frequently between individuals linked by friendship, whereas no significant effect of kinship appeared, which may be related to the open social relationships reported in Tonkean macaques. Females initiated af...