Morphofunctional status of the adrenal cortex in female silver foxes and the effect of domestication and photoperiodic conditions

Studies on 7-day-old and 8-month-old female silver foxes indicate that additional photostimulation affects to a various extent morphological and functional condition of the adrenal cortex in animals selected and unselected for the domestication type of behaviour. In relatively wild foxes, additional illumination stimulated the activity of the reticular zone, whereas in domesticated animals the same photoperiod increased the activity in the fascicular zone. It is suggested that selection of silver foxes for the domestication type of behaviour affects the sensitivity of the adrenals to external illumination.     

Genetics and phenogenetics of hormonal characteristics of animals. VIII. Analysis of the variability of the corticosteroid function of the adrenal cortex of silver foxes during their domestication

The contribution of genetic and environmental components in phenotype variety of corticosteroid adrenal function was studied in undomesticated and domesticated silver foxes during postnatal ontogenesis. The variation of basal and stress plasma corticosteroid level in animals aged 2, 4, 6, 8 months and in vitro secretion of the adrenal gland at the age 8 months was analysed. Significant genotype-depended variability was only demonstrated in undomesticated foxes under stress stimulation conditions. This phenomenon is manifested from the fourth month of life. However, significant genotype-depended variability was already revealed under basal conditions in domesticated foxes, on initial steps of postnatal ontogenesis. The peculiarities of genetic variability of adrenocortical function in foxes selected for domestication are discussed.     

On the origin of a domesticated species: Identifying the parent population of Russian silver foxes (Vulpes vulpes)

The foxes at Novosibirsk, Russia, are the only population of domesticated foxes in the world. These domesticated foxes originated from farm-bred silver foxes (Vulpes vulpes), whose genetic source is unknown. In this study we examined the origin of the domesticated strain of foxes and two other farm-bred fox populations (aggressive and unselected) maintained in Novosibirsk. To identify the phylogenetic origin of these populations we sequenced two regions of mtDNA, cytochrome b and D-loop, from 24 Novosibirsk foxes (8 foxes from each population) and compared them with corresponding sequences of native red foxes from Europe, Asia, Alaska and Western Canada, Eastern Canada, and the Western Mountains of the USA. We identified seven cytochrome b - D-loop haplotypes in Novosibirsk populations, four of which were previously observed in Eastern North America. The three remaining haplotypes differed by one or two base change from the most common haplotype in Eastern Canada. Φ(ST) analysis showed significant differentiation between Novosibirsk populations and red fox populations from all geographic regions except Eastern Canada. No haplotypes of Eurasian origin were identified in the Novosibirsk populations. These results are consistent with historical records indicating that the original breeding stock of farm-bred foxes originated from Prince Edward Island, Canada. Mitochondrial DNA data together with historical records indicate two stages in the selection of domesticated foxes: the first includes captive breeding for ~50 years with unconscious selection for behaviour; the second corresponds to over 50 further years of intensive selection for tame behaviour.     

The composition and antibacterial activity of essential oils in three Ocimum species growing in Romania

In this study the glandular hair morphology, chemical composition and antimicrobial activity of the essential oils from three Ocimum species have been investigated (Ocimum basilicum L. var. Genovese, O. gratissimum and O. tenuiflorum). The indumentum shows little variation among the investigated species with both glandular and non-glandular hairs presents. Glandular hairs on the three species are peltate and capitate (with various cell numbers in the stalk and gland). The samples of essential oils obtained from the plant aerial organs by hydrodistillation have been analyzed by GC-MS. Linalool (65.38%, 74.22%, 38.60%), eugenol (5.26%, 3.47%, 10.20%) and tau-cadinol (8.18%, 3.47%, 10.20%) appear as the main components in Ocimum basilicum L. var. Genovese, O. gratissimum and O. tenuiflorum. The oils also contain lower levels of α-bergamotene, 1,8-cineole, germacrene D, β-ocimene, α-caryophyllene, camphor, and α-guaiene. All essential oils showed antibacterial activity against Staphylococcus aureus and Escherichia coli depending on their concentration. Ocimum basilicum L. var. Genovese oil produced the strongest antibacterial effect on S. aureus and E. coli.     

The effect of methyl-containing supplements during pregnancy on the phenotypic modification of offspring hair color in rats

The effect of methyl supplements to the diet of pregnant homozygous (AAHH) female rats with agouti coat color mated with homozygous (aahh) males on the phenotypic modification of the coat color of their heterozygous offspring (AaHh) has been studied. Comparative morphological analysis of the main parameters of hair that determine coat color, including the total length of hairs of different types and the length of the upper black (eumelanin) and light (pheomelanin) parts of awn hairs has been performed. The pattern of pigment granule distribution among hair layers has been analyzed. The melanin content of the hair has been determined using electron spin resonance (ESR). Although all offspring have a typical agouti coat color (alternating black and light portions of hair), 39% of them have a darker coat color than control and other experimental rats have. The main differences between the offspring with darkened and standard coat colors are accounted for by the ratio between the eumelanin and pheomelanin portions of awn hairs. In darkened offspring, this ratio is significantly higher than in control rats. The possible mechanisms of the phenotypic modification of agouti coat color in experimental animals are discussed.     

Genetic Architecture of Tameness in a Rat Model of Animal Domestication

A common feature of domestic animals is tameness—i.e., they tolerate and are unafraid of human presence and handling. To gain insight into the genetic basis of tameness and aggression, we studied an intercross between two lines of rats (Rattus norvegicus) selected over >60 generations for increased tameness and increased aggression against humans, respectively. We measured 45 traits, including tameness and aggression, anxiety-related traits, organ weights, and levels of serum components in >700 rats from an intercross population. Using 201 genetic markers, we identified two significant quantitative trait loci (QTL) for tameness. These loci overlap with QTL for adrenal gland weight and for anxiety-related traits and are part of a five-locus epistatic network influencing tameness. An additional QTL influences the occurrence of white coat spots, but shows no significant effect on tameness. The loci described here are important starting points for finding the genes that cause tameness in these rats and potentially in domestic animals in general.ANIMAL domestication marked a turning point in human prehistory (Diamond 2002), and domestic animals have been the subject of research for many years (Darwin 1868). Recently, genetic studies have shed light on when, where, and how often a range of animal species were domesticated (Troy et al. 2001; Vila et al. 2001; Savolainen et al. 2002; Larson et al. 2005; Driscoll et al. 2007; Eriksson et al. 2008; Naderi et al. 2008). With the exception of coat color (e.g., Pielberg et al. 2008) and skin pigmentation (Eriksson et al. 2008), little is known about what occurred genetically during animal domestication. At what genes were allelic variants selected for by would-be practitioners of animal husbandry? Although domestic animals differ from each other in many ways, they all share the trait of tameness—i.e., they tolerate and sometimes even seek human presence and handling. Almost nothing is currently known about the genetic basis of tameness.In a series of studies initiated by D. K. Belyaev, researchers at the Institute for Cytology and Genetics in Novosibirsk (Russia) have subjected several mammalian species to a process of experimental domestication (Trut 1999). These studies, some of them ongoing for several decades, involve selection for tame and aggressive behavior in lines of animals derived from wild populations. They include a fox population that has been “domesticated” to such an extent that the tame foxes are now similar to dogs in some respects (Hare et al. 2005). They also include a population of wild-caught rats (Rattus norvegicus) that was selected for either reduced or enhanced aggression toward humans over >60 generations (Belyaev and Borodin 1982). To select the animals, their response to an approaching human hand was observed, and the rats showing the least and the most aggressive behavior were allowed to mate within the two lines, respectively. The initial response to selection was rapid and then slowed, so that little change in behavior from generation to generation has been observed in the last 10–15 generations, although the selection regime has been continued to the present. Today, the “tame” rats are completely unafraid of humans, they tolerate handling and being picked up, and they sometimes approach a human in a nonaggressive manner. By contrast, the “aggressive” rats ferociously attack or flee from an approaching human hand.To study the genetic basis of tameness we have established populations of both rat lines in Leipzig. In their new environment, the rats maintained their behavioral differences in response to humans, and these differences were not influenced by postnatal maternal factors (Albert et al. 2008). In addition, the rat lines differ in a number of other behavioral, anatomical, and physiological traits, raising the question whether these traits are influenced by the same loci as tameness and aggression toward humans.Many domestic animals display conspicuous coat color variations not found in their wild relatives. Prominent examples include the white color variants in dogs, pigs, cows, horses, and chickens. In laboratory rats, it has been proposed that “coat color genes” may account for many of the differences associated with domestication (Keeler and King 1942). It is thus interesting that individuals with white spots appeared in both the tame foxes (Trut 1999) and the tame rats (Trut et al. 2000) at higher frequency than in the corresponding aggressive lines, although they were absent or rare in the founding fox and rat populations, and although they were not selected for. The rat populations studied here provide an excellent opportunity to examine whether tameness is influenced by the same loci as white coat spotting.In this study, we crossed the two rat lines and bred >700 intercross animals. A broad set of behavioral, anatomical, and physiological traits was measured, and a genomewide set of genetic markers was used to identify genomic regions (quantitative trait loci, QTL) that influence tameness as well as other traits that differ between the lines, including white spots.     

Maternal methyl-containing dietary supplementation alters the ability to learn in adult rats in swimming Morris test

Maternal choline diet influences the spatial learning processes. In this work, the learning ability of adult progeny of mothers who had received methyl diet enriched with choline and betain during pregnancy and lactation was studied in Morris test. The introduction of the diet to pregnant rats resulted in an increase in the time of search for invisible platform and time of swimming near the pool walls in offsprings, which meant a worsening of their learning ability. It was also found that change in platform searching strategy was not associated with an increase in anxiety of male rats. Possible involvement of maternal methyl diet in the change of expression of genes which control development of the nervous system is discussed.     

The effect of methyl supplements during pregnancy on the phenotypic modification of offspring agouti coat color in rats

The effect of methyl supplements to the diet of pregnant homozygous (AAHH) female rats with agouti coat color mated with homozygous (aahh) males on the phenotypic modification of the coat color of their heterozygous offspring (AaHh) has been studied. Comparative morphological analysis of the main parameters of hair that determine coat color, including the total length of hairs of different types and the length of the upper black (eumelanin) and light (pheomelanin) parts of awn hairs has been performed. The pattern of pigment granule distribution among hair layers has been analyzed. The melanin content of the hair has been determined using electron spin resonance (ESR). Although all offspring have a typical agouti coat color (alternating black and light portions of hair), 39% of them have a darker coat color than control and other experimental rats have. The main differences between the offspring with darkened and standard coat colors are accounted for by the ratio between the eumelanin and pheomelanin portions of awn hairs. In darkened offspring, this ratio is significantly higher than in control rats. The possible mechanisms of the phenotypic modification of agouti coat color in experimental animals are discussed.     

Single-nucleotide polymorphism,linkage disequilibrium and geographic structure in the malaria parasite <Emphasis Type="Italic">Plasmodium vivax</Emphasis>: prospects for genome-wide association studies

Background

The ideal malaria parasite populations for initial mapping of genomic regions contributing to phenotypes such as drug resistance and virulence, through genome-wide association studies, are those with high genetic diversity, allowing for numerous informative markers, and rare meiotic recombination, allowing for strong linkage disequilibrium (LD) between markers and phenotype-determining loci. However, levels of genetic diversity and LD in field populations of the major human malaria parasite P. vivax remain little characterized.

Results

We examined single-nucleotide polymorphisms (SNPs) and LD patterns across a 100-kb chromosome segment of P. vivax in 238 field isolates from areas of low to moderate malaria endemicity in South America and Asia, where LD tends to be more extensive than in holoendemic populations, and in two monkey-adapted strains (Salvador-I, from El Salvador, and Belem, from Brazil). We found varying levels of SNP diversity and LD across populations, with the highest diversity and strongest LD in the area of lowest malaria transmission. We found several clusters of contiguous markers with rare meiotic recombination and characterized a relatively conserved haplotype structure among populations, suggesting the existence of recombination hotspots in the genome region analyzed. Both silent and nonsynonymous SNPs revealed substantial between-population differentiation, which accounted for ~40% of the overall genetic diversity observed. Although parasites clustered according to their continental origin, we found evidence for substructure within the Brazilian population of P. vivax. We also explored between-population differentiation patterns revealed by loci putatively affected by natural selection and found marked geographic variation in frequencies of nucleotide substitutions at the pvmdr-1 locus, putatively associated with drug resistance.

Conclusion

These findings support the feasibility of genome-wide association studies in carefully selected populations of P. vivax, using relatively low densities of markers, but underscore the risk of false positives caused by population structure at both local and regional levels.See commentary: http://www.biomedcentral.com/1741-7007/8/90