The pleiotropic effect of selection for behavior on coat color in grey rats (Rattus norvegicus)

The effects of selection for a type of behavior relative to humans (tame and aggressive) on the intensity of coat color in agouti rats with the AAHH genotype were studied. Animals that were not under selection for behavior (wild animals) were used as the control. Morphometric analysis of the hair parameters that influence the intensity of coat color demonstrated that, on the one hand, polymorphism in the main coat color exists in the population of wild agouti rats, that is, both light and dark agouti animals exist. On the other hand, it was demonstrated that selection for a type of behavior in rats is accompanied by selection of animals that differ in the intensity of the main genetically identical coat color. Dark-colored animals are more prevelent among the aggressive animals, while light-colored animals prevail among tame animals. The association of the effects of selection for behavior with the modification of coat color is probably caused by the presence of common neurohormonal mechanisms for the regulation of these processes.     

Social cognitive evolution in captive foxes is a correlated by-product of experimental domestication

Dogs have an unusual ability for reading human communicative gestures (e.g., pointing) in comparison to either nonhuman primates (including chimpanzees) or wolves . Although this unusual communicative ability seems to have evolved during domestication , it is unclear whether this evolution occurred as a result of direct selection for this ability, as previously hypothesized , or as a correlated by-product of selection against fear and aggression toward humans--as is the case with a number of morphological and physiological changes associated with domestication . We show here that fox kits from an experimental population selectively bred over 45 years to approach humans fearlessly and nonaggressively (i.e., experimentally domesticated) are not only as skillful as dog puppies in using human gestures but are also more skilled than fox kits from a second, control population not bred for tame behavior (critically, neither population of foxes was ever bred or tested for their ability to use human gestures) . These results suggest that sociocognitive evolution has occurred in the experimental foxes, and possibly domestic dogs, as a correlated by-product of selection on systems mediating fear and aggression, and it is likely the observed social cognitive evolution did not require direct selection for improved social cognitive ability.     

Confirmation of a positive genetic relationship between pendulum movements,audiogenic epilepsy,catalepsy, and “Nervousness” in rats

Relationships between the predispositions to pendulum movements (PMs), catalepsy, and audiogenic epilepsy in the course of breeding for “nervousness” and freezing have been studied. A positive genetic relationship between PMs, catalepsy, and audiogenic epilepsy has been demonstrated. Eighty to ninety percent of rats selected for enhanced PMs (strain PM+) exhibit predisposition to audiogenic seizures, whereas this frequency in the PM-free strain (PM-) is 10–40%.     

The effects of prolonged selection for behavior on the stress response and activity of the reproductive system of male grey mice (Rattus norvegicus)

Two Norway rat (Rattus norvegicus) populations contrasting in behavior have been raised at the Institute of Cytology and Genetics, Novosibirsk, Russia with long-term selection for the absence or enhancement of an aggressive response towards humans. They are designated as tame and aggressive, respectively. In this work we investigated the effects of the selection on behavior, stress responsiveness, and function of testes in males of the 78th generation. It is shown that the difference between the strains in their response to humans remains the same as in previous generations. However, the differences in stress response and rate of maturation contradict earlier data. For the first time, we note a higher glucocorticoid-mediated response to restriction stress and retarded sexual maturation in tame rats compared to aggressive ones, according to morphometric indices of gonads and testosterone levels. It is conceivable that the change in selection effects is determined by the disjunction of the directions of selection for behavior and the modification of the stress response. This study is the first to characterize males recently (six or seven generations of propagation in captivity) caught in the wild with regard to the indices under consideration and used as a control group. Wild rats have the highest stress response and rate of sexual maturation as compared to those selected.     

Behavioral effects of bidirectional selection for behavior towards human in virgin and lactate Norway rats

Although numerous studies have demonstrated strong differences in behavioral, hormonal and neurobiological characteristics between male rats selected for elimination (tame) and enhancement (aggressive) of aggressiveness towards humans, few studies have examined changes in female behavior under this selection. The objective of the current work was to evaluate the effects of bidirectional selection for aggressiveness towards humans on behavioral profiles of virgin and lactating rats compared with the behavior in tame, aggressive and unselected (wild-type) females. The behavior of virgin females was studied using the light-dark box, the startle response test and the modified glove test. Tame females were less anxious and more tolerant towards humans than unselected and aggressive rats. Principal component analysis of all behavioral parameters produced three independent factors, explaining 66.37% of the total variability. The measures of behavior towards humans and the measures of anxiety mainly loaded on PC1 (first principal component) which separated the tame females from the unselected and aggressive ones. These data suggest the genetic correlation between the selected behavior towards humans and anxiety-related behavior in virgin rats. No significant effect of line was found for PC2 scores, associated with risk assessment behavior. Measurements of freezing behavior mainly loaded on PC3, and this component separated rats of different genetic groups from each other. The behavior of lactating rats was studied in maternal defense and pup retrieval tests. Females of selected lines did not significantly differ in behavioral measurements of these tests and were characterized by higher maternal motivation than unselected rats. It is suggested that long-term breeding of tame and aggressive rats in captivity has reduced the threshold for maternal behavior.     

Synthesis of novel terpenophenol-chlorin conjugates and evaluation of their membranotropic and membrane-protecting properties

A series of conjugates has been synthesized by the reaction of methylpheophorbide a with ortho-alkylaminomethyl derivatives of 2-isobornyl-4-methylphenol; the terpenophenol fragment in the conjugates is attached to the methylpheophorbide a macrocycle by an amide bond formed upon the amidation of the 13(2)-ester group. A scanning electron microscopy study of the surface structure of erythrocytes incubated with these compounds confirmed their ability to interact with the cell membrane. It was found, based on the ability of the conjugates to inhibit the H₂O₂-induced hemolysis of erythrocytes and slow down the accumulation of the secondary lipid peroxidation products, that they possess membrane-protecting and antioxidant properties.     

Effect of Low Doses (5-40 cGy) of Gamma-irradiation on Lifespan and Stress-related Genes Expression Profile in Drosophila melanogaster

Studying of the effects of low doses of γ-irradiation is a crucial issue in different areas of interest, from environmental safety and industrial monitoring to aerospace and medicine. The goal of this work is to identify changes of lifespan and expression stress-sensitive genes in Drosophila melanogaster, exposed to low doses of γ-irradiation (5 – 40 cGy) on the imaginal stage of development. Although some changes in life extensity in males were identified (the effect of hormesis after the exposure to 5, 10 and 40 cGy) as well as in females (the effect of hormesis after the exposure to 5 and 40 cGy), they were not caused by the organism “physiological” changes. This means that the observed changes in life expectancy are not related to the changes of organism physiological functions after the exposure to low doses of ionizing radiation. The identified changes in gene expression are not dose-dependent, there is not any proportionality between dose and its impact on expression. These results reflect nonlinear effects of low dose radiation and sex-specific radio-resistance of the postmitotic cell state of Drosophila melanogaster imago.     

Effects of maternal methyl-supplement diet on hippocampal glucocorticoid receptor mRNA expression in rats selected for behavior

In the present work, we study glucocorticoid receptor (GR) gene expression in gray rats selected for aggressive and domestic behavior, as well as in offspring of mothers with methyl-supplemented diet during pregnancy. Tame selection is associated with increased GR mRNA expression as compared with aggressive rats, whereas maternal methyl-supplemented diet inhibits GR activity in tame rats. GR gene promoter methylation is an important way of altering GR expression.     

Serological survey for viral pathogens in Turkish rodents

Wild rodents (n = 330) were trapped around the villages of Altindere and Co?andere (Ma?ka, Trabzon Province), Ayder, Ortan, and Yolkiyi (Camlihem?in, Rize Province), and Bozdag (Odemi?, Izmir Province) in northeastern and western Turkey during April 2004. Samples were tested for arenavirus, hantavirus, and cowpox virus (family Poxviridae, genus Orthopoxvirus, CPXV) antibodies by using immunofluorescence assays (IFAs). Antibodies against arenaviruses were found in eight of 330 (2.4%) rodents. Arenavirus sero-positive animals were found from all study sites. Antibodies to Puumala virus (family Bunyaviridae, genus Hantavirus, PUUV) were detected in four of 65 Microtus voles tested. Of the PUUV-IFA-positive voles, one Microtus guentheri lydius was caught from Izmir, and one Microtus roberti and two Microtus rossiaemeridionalis were captured near Trabzon. All 264 Apodemus spp. mice tested negative for antibodies to Saaremaa virus (family Bunyaviridae, genus Hantavirus, SAAV); the single Dryomys nitedula tested negative for both PUUV and SAAV antibodies. Only one (0.3%) of the rodents, an Apodemus sylvaticus from Trabzon area, tested seropositive to CPXV. This is the first serologic survey for rodent-borne viruses in their natural hosts in Turkey. Although these preliminary results support presence of several virus groups with zoonotic potential, additional studies are needed to identify the specific viruses that are present in these populations.