Timing of isolation from an enriched environment determines the level of aggressive behavior and sexual maturity in Siamese fighting fish (Betta splendens)

Background Teleost fish are known to respond to environmental manipulation, which makes them an ideal model animal for testing relationships between the environment and behavior. The Siamese fighting fish, Betta splendens, is a solitary, highly territorial fish that displays fierce stereotyped aggressive behavior toward conspecifics or members of other species. Adult fish, especially males, are generally housed in isolation in captivity. Here we report evidence that an enriched rearing environment can decrease the level of aggression in bettas and enable adults to be housed in groups. Results B. splendens individuals were hatched in our laboratory and raised in groups in an enriched environment. At the juvenile or subadult stage, some individuals were relocated to a poor environment and kept in isolation. To evaluate aggression, a mirror-image test was conducted at the juvenile, subadult, and adult stages for each fish, and body parameters as well as plasma concentrations of 11-ketotestosterone, estradiol, and cortisol were evaluated. Male and female adult bettas raised in a group showed lower levels of aggression than other adult fish. The magnitude of threatening behavior was greater in adult bettas isolated as subadults, whereas the magnitude of fighting behavior was grater in adult bettas isolated as juveniles. The influence of rearing conditions on behavior was greater in females than in males. Plasma cortisol concentrations of adult bettas isolated as subadults after the mirror-image test were higher than those in other experimental groups. Adult males isolated as subadults had significantly higher plasma concentrations of 11-ketotestosterone than males raised in a group and isolated as juveniles. Females isolated as subadults had a higher gonadosomatic index than females raised in a group and females isolated as juveniles. Conclusions These results indicate that bettas can be kept in a group under enriched environments and that the timing of isolation influences the aggression and sexual maturity of bettas. Female and male bettas responded differently to environmental manipulation. Judging from their level of sexual maturity, bettas isolated as subadults show proper development.

Environmental enrichment influences novelty reactivity, novelty preference, and anxiety via distinct genetic mechanisms in C57BL/6J and DBA/2J mice

Environmental factors such as stress drive the development of drug addiction in genetically vulnerable individuals; the genes underlying this vulnerability are unknown. One strategy for uncovering these genes is to study the impact of environmental manipulation on high-throughput phenotypes that predict drug use and addiction-like behaviors. In the present study, we assessed the viability of this approach by evaluating the relative effects of environmental enrichment and isolation housing on three high-throughput phenotypes known to predict variation on distinct aspects of intravenous drug self-administration. Prior to behavioral testing, male and female C57BL/6J and DBA/2J mice (BXD founders) were housed in enrichment or isolation for ten weeks beginning at weaning. Enrichment significantly reduced novelty reactivity; this effect was significantly more robust in C57BL/6J mice relative to DBA/2J mice. Enrichment significantly reduced novelty preference; this effect was significantly dependent on novel environment characteristics and was significantly more robust in DBA/2J mice relative to C57BL/6J mice. Enrichment significantly increased anxiety; this effect was not strain-dependent. Collectively, these data indicate that (1) environmental enrichment influences novelty reactivity, novelty preference, and anxiety via distinct genetic mechanisms in mice, and (2) the BXD panel can be used to discover the genetic and epigenetic mechanisms underlying this phenomenon.

Many roads to bacterial generalism

ABSTRACT The fundamental niches of bacteria can be defined along many environmental axes, including temperature tolerance and resources consumed, while interactions with other organisms can constrain (e.g. competition) or enlarge (e.g. cross-feeding) realized niches. Organisms are often categorized as generalists or specialists, corresponding to broad or narrow niche requirements, which can then be linked to their functional role in an ecosystem. We show how these terms are applied to bacteria, make predictions about how the type and extent of generalism displayed by an organism relates to its functional potential and discuss the value of collecting different types of generalist bacteria. We believe that new approaches that take advantage of both high-throughput sequencing and environmental manipulation can allow us to understand the many types of generalism found within both cultivated and yet-to-be-cultivated bacteria.

Spatial heterogeneity in resources alters selective dynamics in Drosophila melanogaster

Environmental features can alter the behaviours and phenotypes of organisms and populations evolving within them including the dynamics between natural and sexual selection. Experimental environmental manipulation, particularly when conducted in experiments where the dynamics of the purging of deleterious alleles are compared, has demonstrated both direct and indirect effects on the strength and direction of selection. However, many of these experiments are conducted with fairly simplistic environments when it is not always clear how or why particular forms of spatial heterogeneity may influence behaviour or selection. Using Drosophila melanogaster, we tested three different spatial environments designed to determine if spatial constraint of critical resources influences the efficiency of natural and sexual selection. We conducted two allele purging experiments to 1) assess the effects of these spatial treatments on the selective dynamics of six recessive mutations, and 2) determine how these dynamics changed when sexual selection was relaxed and the spatial area was reduced. We found that allele purging dynamics depended on spatial environment, however the patterns of purging rates between the environments differed across distinct deleterious mutations. We also found that for two of the mutations, the addition of sexual selection increased the purging rate.

Spawning of French grunts, Haemulon flavolineatum, in recirculating aquarium systems

Background Because the French grunt, Haemulon flavolineatum, is an ecologically important reef fish prized by both recreational anglers and public aquariums, the wild population requires limits on harvests. Yet, the environmental conditions conducive for French grunt spawning in aquarium settings is not well understood. Therefore, the goal of this study was to document the conditions leading to voluntary spawning and the number of eggs produced by French grunts without the use of hormones or artificial insemination. Methods We hypothesized and verified that it is possible for French grunts to spontaneously spawn in human care. Forty individuals were collected around the Florida Keys and haphazardly stocked in five recirculating seawater systems each containing two 250-L circular tanks. Over the course of 87 days, eggs were collected daily from each system and environmental parameters were monitored. Results Total daily number of eggs released ranged from 0 to 207,644 eggs. Of the observed environmental parameters, temperature and alkalinity had the greatest impact on number of eggs released. This study demonstrates that it is possible for French grunts to reproduce in captivity with little environmental manipulation, thus an ideal candidate to culture for the zoo/aquarium industry.

Nutraceuticals for Promoting Longevity

Objective: To summarize the main findings on nutraceuticals that slow aging processes by delaying and even preventing the development of multiple chronic diseases and improve productivity and quality of life in the elderly. Methods: Literature search of the relevant papers known to the authors was conducted. Results: The most robust environmental manipulation for extending lifespan is caloric restriction without malnutrition. Some nutraceuticals can mimic caloric restriction effects. This review will focus on the nutraceuticals that impact insulin-like growth factor 1 receptor signaling and sirtuin activity in mediating longevity and healthspan. Conclusion: Aging is considered to be synonymous with the appearance of major diseases and an overall decline in physical and mental performance. Caloric restriction is well established as a strategy to extend lifespan without malnutrition. A variety of nutraceuticals were reported to mimic the effect of caloric restriction by modulating the activity of insulin-like growth factor 1 receptor signaling and sirtuin activity and consequently promote longevity and healthspan.