The effects of early and adult social environment on zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) behavior

Because early social experience can have a profound effect on later mate and social choices, the availability of options and decisions made early in development can have major effects on adult behavior. Herein, we use strain differences among zebrafish, Danio rerio, as an experimental tool to test the effects of social experience on behavior. By manipulating the strain composition of groups in which the subject fish are housed at different ages, we tested (1) whether mixing with dissimilar individuals influenced subsequent behavior, (2) whether prolonged mixing during the juvenile stage had a more pronounced effect than a shorter period of mixing during adulthood and (3) whether mixing had a lasting effect after animals were resorted into groups of same strain animals. We found that social experience had a profound impact on social behavior. Both Nadia and TM1 individuals engaged in more frequent biting after having been in mixed strain groups compared to pure strain groups. This was true of groups mixed as juveniles, as well as adults, indicating that this response was not dependent on exposure during a critical developmental period. Also, TM1 fish (but not Nadia) having recently been housed in mixed-strain groups were more willing to leave the immediate vicinity of a shoal than were TM1 fish raised in pure strain groups. This change was more pronounced in groups mixed as juveniles than as adults. In addition, the observed changes persisted after mixed groups were separated into pure strain groups for a month. Other behavioral measures including Activity Level, Predator Response and Stress Recovery were unaffected by previous social experience.     

Increased behavioral and neuronal sensitivity to sex pheromone after brief odor experience in a moth

Plasticity in the response to stimuli related to food and oviposition cues is well documented in insects. However, responses to cues related to reproduction, for example, sex pheromones, are considered to be innate and thus not affected by experience. Here we show that brief preexposure to sex pheromones, without ensuing reward, lowers the threshold for behavioral response and augments the sensitivity in antennal lobe interneurons to pheromone compared with naive male moths. Thus, the sex pheromone system in insects can be modulated by experience. In addition, we show that the behavioral attraction to sex pheromone increases after preexposure in a time-dependent manner: a short-term effect, possibly a form of sensitization, and a long-term effect after more than 24 h. The behavioral long-term effect is paralleled by an increase in sensitivity of interneurons in the primary olfactory center, whereas the peripheral olfactory system does not change its sensitivity. We hypothesize that short-term sensitization to sex pheromone serves as a kind of alert system, whereas the long-term effect improves male performance when reproductively active females are present.     

Species differences in tumour responses to cancer chemotherapy

Despite advances in chemotherapy, radiotherapy and targeted drug development, cancer remains a disease of high morbidity and mortality. The treatment of human cancer patients with chemotherapy has become commonplace and accepted over the past 100 years. In recent years, and with a similar incidence of cancer to people, the use of cancer chemotherapy drugs in veterinary patients such as the dog has also become accepted clinical practice. The poor predictability of tumour responses to cancer chemotherapy drugs in rodent models means that the standard drug development pathway is costly, both in terms of money and time, leading to many drugs failing in Phase I and II clinical trials. This has led to the suggestion that naturally occurring cancers in pet dogs may offer an alternative model system to inform rational drug development in human oncology. In this review, we will explore the species variation in tumour responses to conventional chemotherapy and highlight our understanding of the differences in pharmacodynamics, pharmacokinetics and pharmacogenomics between humans and dogs. Finally, we explore the potential hurdles that need to be overcome to gain the greatest value from comparative oncology studies.     

Characterization of acute phase proteins and oxidative stress response to road transportation in the dog

Haptoglobin (Hp), serum amyloid A (SAA), C-reactive protein (CRP), white blood cells (WBC), reactive oxygen metabolites (ROMs), the antioxidant barrier (Oxy-adsorbent) and thiol groups of plasma compounds (SHp) were measured in ten dogs that had been transported a distance of about 230 km within 2 h (experimental group) and in ten dogs that had not been subjected to road transportation (control group). Blood was collected via cephalic venipuncture before road transportation (T0), after road transportation (T1), and more than 6 (T6) and 24 (T24) hours after road transportation in the experimental group (Group A) and at the same time points in the control group (Group B). The GLM (general linear model) Repeated Measures procedure showed a significant difference between the two groups (P<0.0001) and a significant rise (P<0.0001) in the concentrations of Hp, SAA, CRP, WBC, ROMs, Oxy-adsorbent and SHp after road transportation in Group A, underlining that physiological and homeostatic mechanisms are modified differently at various sampling times.     

Primiparous females do not exhibit reduced maternal care in gray seals (Halichoerus grypus)

We compared the behaviors of primiparous and multiparous gray seal (Halichoerus grypus) females over the course of lactation to examine whether poorly developed maternal behaviors may play a role in the reduced lactation performance observed in primiparous females. Overall, primiparous females spent as much time interacting with their pups as multiparous females. The proportion of time spent nursing their pup increased significantly between early and peak lactation in both primiparous and multiparous females. Although there was no significant difference in the duration of nursing bouts as a function of reproductive status, primiparous females nursed significantly more frequently (bouts/hour) and, therefore, spent a significantly greater proportion of time nursing than multiparous females throughout lactation. Primiparous gray seal females were also significantly more active than multiparous females, however, the difference in activity represented only a small proportion of the overall time budget. We conclude that poorly developed maternal behaviors resulting from a lack of prior reproductive experience are unlikely to account for lower levels of milk energy transfer to pups in primiparous gray seals.     

Genetic evidence for multiple events of hybridization between wolves and domestic dogs in the Iberian Peninsula

Hybridization between wild species and their domestic counterparts may represent a major threat to natural populations. However, high genetic similarity between the hybridizing taxa makes the detection of hybrids a difficult task and may hinder attempts to assess the impact of hybridization in conservation biology. In this work, we used a combination of 42 autosomal microsatellites together with Y-chromosome microsatellite-defined haplotypes and mtDNA sequences to investigate the occurrence and dynamics of wolf-dog hybridization in the Iberian Peninsula. To do this, we applied a variety of Bayesian analyses and a parallel set of simulation studies to evaluate (i) the differences between Iberian wolves and dogs, (ii) the frequency and geographical distribution of hybridization and (iii) the directionality of hybridization. First, we show that Iberian wolves and dogs form two well-differentiated genetic entities, suggesting that introgressive hybridization is not a widespread phenomenon shaping both gene pools. Second, we found evidence for the existence of hybridization that is apparently restricted to more peripheral and recently expanded wolf populations. Third, we describe compelling evidence suggesting that the dynamics of hybridization in wolf populations is mediated by crosses between male dogs and female wolves. More importantly, the observation of a population showing the occurrence of a continuum of hybrid classes forming mixed packs may indicate that we have underestimated hybridization. If future studies confirm this pattern, then an intriguing avenue of research is to investigate how introgression from free-ranging domestic dogs is enabling wolf populations to adapt to the highly humanized habitats of southern Europe while still maintaining their genetic differentiation.     

Microsatellite characterization of Cimarron Uruguayo dogs

Various genetic markers, including microsatellites, have been used to analyze the genetic polymorphism and heterozygosity in canine breeds. In this work, we used nine microsatellite markers to investigate the genetic variability in Cimarron Uruguayo dogs, the only officially recognized native canine breed in Uruguay. DNA from 30 Cimarron Uruguayo dogs from northeastern and southern Uruguay was analyzed. The allelic frequencies for each microsatellite, the genetic variability and the consanguinity were calculated, as were the polymorphic information content (PIC) and the probability of exclusion (PE). All of the microsatellites studied were polymorphic. FH 2361, FH 2305 and PEZ 03 were the most informative, with PIC values > 0.7, in agreement with results for other canine breeds. The PE values for the markers were within the ranges previously described and were generally greater for microsatellites with higher PIC values. The heterozygosity value (0.649) was considered high since only nine microsatellites were analyzed. Compared with data for other breeds, the results obtained here indicate that Cimarron Uruguayo dogs have high genetic diversity.     

早期负性经历的表观遗传学研究进展

表观遗传学（epigenetics）是指不涉及DNA序列改变、可以通过有丝分裂和减数分裂进行遗传的基因表达变化的遗传学分支领域。目前研究主要集中在DNA甲基化、组蛋白密码、染色质重塑和非编码RNA调控等方面。早期负性经历是指个体出生早年所经历的不良生活事件,还包括个体出生前所经历的负性生活事件。大量研究表明早期负性经历对个体成年后的行为会造成明显影响。本文将综述早期负性经历中表观遗传的各种机制。