Short communication: Domesticated and wild fathead minnows differ in growth and thermal tolerance.

Many populations have evolved in response to laboratory environments (lack of predators, continual food availability, etc.). Another potential agent of selection in the lab is exposure to constant thermal environments. Here, we examined changes in growth, critical thermal maximum (CTmax), and food consumption under constant (25 °C) and fluctuating (22-28 °C and 19-31 °C) conditions in two populations of fathead minnows, Pimephales promelas: one that has been kept in a laboratory setting for over 120 generations (~40 years) and a corresponding wild one. We found that under thermal fluctuations, domesticated fathead minnows grew faster than their wild counterparts, but also exhibited lower thermal tolerance. Food consumption was significantly higher in the lab population under the constant and large fluctuation thermal treatments. Our results suggest that the lab population has adjusted to the stable conditions in the laboratory and that we should carefully apply lessons learned in the lab to wild populations.

Horizontal transfer and finalization of a reliable detection method for the olive fruit fly endosymbiont, Candidatus Erwinia dacicola.

BACKGROUND: The olive fly, Bactrocera oleae, is the most important insect pest in olive production, causing economic damage to olive crops worldwide. In addition to extensive research on B. oleae control methods, scientists have devoted much effort in the last century to understanding olive fly endosymbiosis with a bacterium eventually identified as Candidatus Erwinia dacicola. This bacterium plays a relevant role in olive fly fitness. It is vertically transmitted, and it benefits both larvae and adults in wild populations; however, the endosymbiont is not present in lab colonies, probably due to the antibiotics and preservatives required for the preparation of artificial diets. Endosymbiont transfer from wild B. oleae populations to laboratory-reared ones allows olive fly mass-rearing, thus producing more competitive flies for future Sterile Insect Technique (SIT) applications. RESULTS: We tested the hypothesis that Ca. E. dacicola might be transmitted from wild, naturally symbiotic adults to laboratory-reared flies. Several trials have been performed with different contamination sources of Ca. E. dacicola, such as ripe olives and gelled water contaminated by wild flies, wax domes containing eggs laid by wild females, cages dirtied by faeces dropped by wild flies and matings between lab and wild adults. PCR-DGGE, performed with the primer set 63F-GC/518R, demonstrated that the transfer of the endosymbiont from wild flies to lab-reared ones occurred only in the case of cohabitation. CONCLUSIONS: Cohabitation of symbiotic wild flies and non-symbiotic lab flies allows the transfer of Ca. E. dacicola through adults. Moreover, PCR-DGGE performed with the primer set 63F-GC/518R was shown to be a consistent method for screening Ca. E. dacicola, also showing the potential to distinguish between the two haplotypes (htA and htB). This study represents the first successful attempt at horizontal transfer of Ca. E. dacicola and the first step in acquiring a better understanding of the endosymbiont physiology and its relationship with the olive fly. Our research also represents a starting point for the development of a laboratory symbiotic olive fly colony, improving perspectives for future applications of the Sterile Insect Technique.

Effects of a Covert Infection with Phthorimaea operculella granulovirus in Insect Populations of Phthorimaea operculella.

Virus infections of insects can easily stay undetected, neither showing typical signs of a disease, nor being lethal. Such a stable and most of the time covert infection with Phthorimaea operculella granulovirus (PhopGV) was detected in a Phthorimaea operculella laboratory colony, which originated from Italy (Phop-IT). This covert virus (named PhopGV-R) was isolated, purified and characterized at the genetic level by full genome sequencing. Furthermore, the insect colony Phop-IT was used to study the crowding effect, double infection with other PhopGV isolates (CR3 and GR1), and co-infection exclusion. An infection with a second homologous virus (PhopGV-CR3) activated the covert virus, while a co-infection with another virus isolate (PhopGV-GR1) led to its suppression. This study shows that stable virus infections can be common for insect populations and have an impact on population dynamics because they can suppress or enable co-infection with another virus isolate of the same species.

In vitro feeding of Hyalomma lusitanicum ticks on artificial membranes.

In vitro feeding of ticks (Acari: Ixodidae) is an important means to study the biology of ticks and their vectorial capacity. Here, we have adapted the tick Hyalomma lusitanicum Koch to previously published silicone-based membranes for in vitro feeding. For comparison purposes data on pre-oviposition, oviposition and hatching from females engorged on animals were used. A total of 68 engorged females out of 169 were obtained; feeding duration and feeding behaviour were similar to that of ticks on live host animals, although the final weight achieved for membrane-fed ticks was lower than that of their animal-fed counterparts. Comparison of the time taken for egg production and hatching showed that pre-oviposition was faster for membrane-fed ticks (16 days) than for animal-fed ticks (36 days), whereas the duration of oviposition-hatching was the same for the two feeding methods (34 days). We also observed that seasonality has an influence on tick feeding success: the conditions in Spring/Summer accelerated the tick life cycle. It is concluded that relatively large numbers of homogeneous laboratory-raised Hyalomma ticks can be produced without feeding them on experimental animals.

Breeding protocol for the sand fly Nyssomyia neivai (Diptera: Psychodidae) in laboratory conditions.

The information in this protocol covers from the basic steps and material necessary to start a sand fly colony up to the specific details which are important to the success of a Nyssomyia neivai colony. The greatest problems in our colony of Ny. neivai were solved with specific care, for instance, using vermiculite and an adequate number of adults in oviposition containers; the control of fungus with the exact amount of diet for the larvae and humidity control; a second blood meal for females and control of the number of times animals are used for blood meals. Currently, our colony is at F22 generation.

Simplified membrane feeding of bloodsucking triatomines (Hemiptera: Reduviidae).

Laboratory-reared hematophagous triatomines that are the main vectors of Chagas disease are generally fed on small vertebrates or on blood-filled membrane devices. Such devices allow a large-scale rearing of these vectors without sacrificing host animals but are almost always expensive, fragile, not easily purchased, and usually difficult to use because they need to be sterilized before and carefully cleaned after each feeding. We present here a simple device to feed triatomines that is composed of a circular series of alternating short pieces of stainless steel and silicon tubing connected to a pump that circulates water heated at 50° C in a water bath. An unlubricated condom filled with 50ml of blood, is fixed around each steel tube section and placed onto the screened tops of containers with triatomines. Nymphs and adults access the blood source by climbing a vertical piece of folded filter paper. After feeding, each condom can be easily and safely removed and discarded. This device consists of simple, cheap, safe and robust components that can be easily purchased, assembled and used. Contamination during or after feeding is practically excluded. The technique is successfully used in our Laboratory for almost two years.

Points to Consider in Designing and Conducting Juvenile Toxicology Studies.

In support of a clinical trial in the pediatric population, available nonclinical and clinical data provide input on the study design and safety monitoring considerations. When the existing data are lacking to support the safety of the planned pediatric clinical trial, a juvenile animal toxicity study is likely required. Usually a single relevant species, preferably a rodent, is chosen as the species of choice, while a nonrodent species can be appropriate when scientifically justified. Juvenile toxicology studies, in general, are complicated both conceptually and logistically. Development in young animals is a continuous process with different organs maturing at different rates and time. Structural and functional maturational differences have been shown to affect drug safety. Key points to consider in conducting a juvenile toxicology study include a comparative development of the organ systems, differences in the pharmacokinetics/absorption, distribution, metabolism, excretion (PK/ADME) profiles of the drug between young animal and child, and logistical requirement in the juvenile study design. The purpose of this publication is to note pertinent points to consider when designing and conducting juvenile toxicology studies and to aid in future modifications and enhancements of these studies to enable a superior predictability of safety of medicines in the pediatric population.

Developmental Expression of Ecdysone-Related Genes Associated With Metamorphic Changes During Midgut Remodeling of Silkworm Bombyx mori (Lepidoptera:Bombycidae).

Steroid hormone 20-hydroxyecdysone is known as the systemic regulators of insect cells; however, how to impact the fate and function of mature and stem cells is unclear. For the first time, we report ecdysone regulatory cascades in both mature midgut cell and stem cell fractions related to developmental events by using histological, immunohistochemical, biochemical and gene expression analysis methods. Ecdysone receptor-B1 (EcR-B1) and ultraspiracle 1 (USP-1) mRNAs were detected mainly in mature cells during programmed cell death (PCD). Lowered E75A and probably BR-C Z4 in mature cells appear to provide a signal to the initiation of PCD. E74B, E75B and BR-C Z2 seem to be early response genes which are involved in preparatory phase of cell death. It is likely that ßFTZ-F1, E74A and BR-C Z1 are probably associated with execution of death. EcR-A and USP2 mRNAs were found in stem cells during remodeling processes but EcR-B1, USP1 and E74B genes imply an important role during initial phase of metamorphic events in stem cells. BHR3 mRNAs were determined abundantly in stem cells suggesting its primary role in differentiation. All of these results showed the determination the cell fate in Bombyx mori (Linnaeus) midgut depends on type of ecdysone receptor isoforms and ecdysone-related transcription factors.

A comparison of adult body size between captive and wild vervet monkeys (Chlorocebus aethiops sabaeus) on the island of St. Kitts.

Weight and 34 morphological measurements were obtained from 103 vervet monkeys living either in the wild or in captive colonies derived from the wild populations on the island of St. Kitts in the Eastern Caribbean. All measures were taken during the same week, eliminating bias that might result from changing seasonal environmental conditions. Vervets on St. Kitts are all descended from a small number of individuals brought to the island approximately 400 years ago from West Africa, thus eliminating bias that might result from subspecific size differences. We conducted a principal components analysis (PCA) and compared individual traits between captive and wild adult animals. Morphological measures such as body, arm, and leg length did not differ significantly between animals living in the wild and animals in captivity. Weight and measures indicating condition-including body mass index (BMI), chest, thigh, and upper arm girth were all higher for animals living in captivity. More consistent available food is probably the cause of differences in measures reflecting condition.

Sexual maturation of the Mongolian gerbil (Meriones unguiculatus): a histological, hormonal and spermatic evaluation.

This study determined the phases of sexual development of the male Mongolian gerbil (Meriones unguiculatus) based on an integrative analysis of testicular morphology, hormonal data and sperm parameters. Male gerbils were analysed at 1, 7, 14, 21, 28, 35, 42, 50, 60, 70, 90, 100 and 120 days of age. Body, testicular and epididymal weights increased up to Day 70, 60 and 90, respectively. The impuberal phase, characterised by the presence of gonocytes, extended until Day 14. The prepubertal period lasted until Day 42, when puberty was achieved and a drastic increase in serum testosterone levels, mature adult Leydig cells and elongated spermatids was observed. Gerbils at 60 days of age showed a remarkable number of spermatozoa in the testis, epididymidis caput/corpus and cauda, and at Day 70 the maximum daily sperm production was reached. However, the gerbil may be considered sexually mature only from Day 90 onward, when sperm reserves become stable. The total transit time of spermatozoa along the epididymis of sexually mature gerbils was 11 days, with 1 day in the caput/corpus and 10 days in the cauda. These data cover a lacuna regarding the reproductive parameters of this rodent and provide foundations for its use in testicular toxicology studies.

Captive Care, Raising, and Breeding of the Veiled Chameleon (Chamaeleo calyptratus).

Squamate reptiles comprise approximately one-third of all living amniotes. In most of these species, it is difficult to study gastrulation and neurulation because the embryos are at a late stage of development at the time of oviposition. This is not the case, however, in veiled chameleons (Chamaeleo calyptratus), which are increasingly being used as a model organism to study these and other developmental and evolutionary phenomena. Originating from the Arabian Peninsula, veiled chameleons are arboreal specialists that possess extensive morphological specializations for climbing. They naturally inhabit semitropical habitats, but they also have an almost 30-yr history of being bred in captivity. Veiled chameleons breed readily and do not require a period of cooling to induce the reproductive cycle, and females can produce ∼45-90 eggs multiple times per year. Thus, compared with other reptiles, relatively few animals are needed to maintain a productive breeding colony. Herein, we present the conditions, equipment, and techniques required for proper husbandry and breeding of veiled chameleons within a laboratory environment.

Choosing the right species in research.

When designing animal studies, investigators must choose a species that is appropriate for the research. In this paper, the author examines various criteria that can be used to guide this selection. He discusses the concepts of phylogenetic group and sentience and finds them not to be useful in the selection of appropriate species in biomedical research. He identifies other criteria that are more useful as justifications for species selection, including susceptibility to a targeted disease process, tendency to engage in a targeted behavior, suitable size for the experimental techniques to be used, presence of a large body of data relevant to the study, species specificity (the species itself is the target of the research), intergenerational interval, similarity to humans, contractual specification and existing guidelines. He proposes that investigators should use these justifications, and perhaps others, to choose the most scientifically appropriate species for animal studies.

Introducing improvements in the mass rearing of the housefly: biological, morphometric and genetic characterization of laboratory strains.

Understanding the biology of the housefly (Musca domestica L.) is crucial for the development of mass-rearing protocols in order to use this insect as a degradation agent for livestock waste. In this study, the biological and genetic differences between different laboratory strains of M. domestica were analysed. Additionally, hybrids were obtained by mixing the strains and their biological parameters were also measured. The three strains of M. domestica presented differences in their biological and morphological parameters, the main differences were: size, egg production and developmental time. The strain A (specimens from Central Europe) had the best qualities to be used in mass-rearing conditions: it produced the largest quantities of eggs (5.77±0.38 eggs per female per day), the individuals were larger (12.62±0.22 mg) and its developmental time was shorter (15.22±0.21 days). However, the strain C (specimens from SW Europe) produced the fewest eggs (3.15±0.42 eggs per female per day) and needed 18.16±0.49 days to develop from larva to adult, whilst the females from strain B (from South America) produced 4.25±0.47 eggs per day and needed 17.11±0.36 days to complete its development. Genetic analysis of the original laboratory strains showed four different mtDNA cytochrome c oxidase subunit I haplotypes. Statistical parsimony network analysis showed that the SW Europe and South-American strains shared haplotypes, whereas the Central Europe strain did not. Upon hybridizing the strains, variations in egg production and in developmental time were observed in between hybrids and pure strains, and when mixing Central European and South-American strains only males were obtained.

Juvenile development of Callinectes danae Smith, 1869 (Crustacea, Decapoda, Brachyura, Portunidae) under laboratory conditions.

The juvenile development of Callinectes danae was investigated from megalopae obtained in neuston samples at Ubatuba, São Paulo, Brazil. The individuals were raised in the laboratory under constant temperature (25 ± 1°C), filtered sea water from the collection location (35‰), and natural photoperiod. Newly hatched Artemia sp. nauplii were offered as food on a daily basis and ornamental-fish food was also provided for the juveniles from the 4th stage on. Twelve stages of the juvenile phase were obtained. The main morphological features that allowed recognition of the first juvenile stage were drawn and described. All the subsequent stages obtained were examined and measured, and the main changes in relation to the first stage were recorded. Sexual dimorphism becomes apparent from the fourth juvenile stage onwards. Some appendages and morphological features proved to be of great importance in the identification of species, including the number of segments of the antennal flagellum and the number of setae on the maxilla and on the 1st, 2nd and 3rd maxillipeds. These can probably be used for future comparisons and species identifications.

Influence of resource levels, organic compounds and laboratory colonization on interspecific competition between the Asian tiger mosquito Aedes albopictus (Stegomyia albopicta) and the southern house mosquito Culex quinquefasciatus.

The mosquitoes Aedes albopictus (Stegomyia albopicta) (Skuse) and Culex quinquefasciatus (Say) (Diptera: Culicidae) are common inhabitants of tyres and other artificial containers, which constitute important peridomestic mosquito breeding habitats. We tested the hypotheses that interspecific resource competition between the larvae of these species is asymmetrical, that the concentration of chemicals associated with decomposing detritus affects the competitive outcomes of these species, and that wild and colonized strains of Cx. quinquefasciatus are affected differently by competition with Ae. albopictus. We conducted two laboratory competition experiments wherein we measured survivorship and estimated population growth (λ') in both species under multiple mixed-species densities. Under varying resource levels, competition was asymmetrical: Ae. albopictus caused competitive reductions or exclusions of Cx. quinquefasciatus under conditions of limited resources. In a second experiment, which used both wild and colonized strains of Cx. quinquefasciatus, organic chemical compounds associated with decomposing detritus did not affect the competitive outcome. The colonized strain of Cx. quinquefasciatus had greater survivorship and adult mass, and faster development times than the wild strain, but both strains were similarly affected by competition with Ae. albopictus. Competition between these species may have important consequences for vector population dynamics, especially in areas in which tyres and artificial containers constitute the majority of mosquito breeding habitats.

Phenotypic variation of the housefly, Musca domestica: amounts and patterns of wing shape asymmetry in wild populations and laboratory colonies.

Musca domestica L. (Diptera: Muscidae) is a vector of a range variety of pathogens infecting humans and animals. During a year, housefly experiences serial population bottlenecks resulted in reduction of genetic diversity. Population structure has also been subjected to different selection regimes created by insect control programs and pest management. Both environmental and genetic disturbances can affect developmental stability, which is often reflected in morphological traits as asymmetry. Since developmental stability is of great adaptive importance, the aim of this study was to examine fluctuating asymmetry (FA), as a measure of developmental instability, in both wild populations and laboratory colonies of M. domestica. The amount and pattern of wing shape FA was compared among samples within each of two groups (laboratory and wild) and between groups. Firstly, the amount of FA does not differ significantly among samples within the group and neither does it differ between groups. Regarding the mean shape of FA, contrary to non-significant difference within the wild population group and among some colonies, the significant difference between groups was found. These results suggest that the laboratory colonies and wild samples differ in buffering mechanisms to perturbations during development. Hence, inbreeding and stochastic processes, mechanisms dominating in the laboratory-bred samples contributed to significant changes in FA of wing shape. Secondly, general patterns of left-right displacements of landmarks across both studied sample groups are consistent. Observed consistent direction of FA implies high degrees of wing integration. Thus, our findings shed light on developmental buffering processes important for population persistence in the environmental change and genetic stress influence on M. domestica.

Adolescent sleep patterns in humans and laboratory animals.

This article is part of a Special Issue "Puberty and Adolescence". One of the defining characteristics of adolescence in humans is a large shift in the timing and structure of sleep. Some of these changes are easily observable at the behavioral level, such as a shift in sleep patterns from a relatively morning to a relatively evening chronotype. However, there are equally large changes in the underlying architecture of sleep, including a >60% decrease in slow brain wave activity, which may reflect cortical pruning. In this review we examine the developmental forces driving adolescent sleep patterns using a cross-species comparison. We find that behavioral and physiological sleep parameters change during adolescence in non-human mammalian species, ranging from primates to rodents, in a manner that is often hormone-dependent. However, the overt appearance of these changes is species-specific, with polyphasic sleepers, such as rodents, showing a phase-advance in sleep timing and consolidation of daily sleep/wake rhythms. Using the classic two-process model of sleep regulation, we demonstrate via a series of simulations that many of the species-specific characteristics of adolescent sleep patterns can be explained by a universal decrease in the build-up and dissipation of sleep pressure. Moreover, and counterintuitively, we find that these changes do not necessitate a large decrease in overall sleep need, fitting the adolescent sleep literature. We compare these results to our previous review detailing evidence for adolescent changes in the regulation of sleep by the circadian timekeeping system (Hagenauer and Lee, 2012), and suggest that both processes may be responsible for adolescent sleep patterns.

Husbandry and breeding in the Octodon degu (Molina 1782).

The Octodon degu is a native rodent species from South America, which lives in colonies with a well-structured social organization grouping of 5-10 young and 2-5 adult animals sharing a burrow system. They show a temperature-dependent diurnal-crepuscular activity pattern. In nature they rarely survive 2 yr, mostly because of predation. However, in captivity, females reproduce for 4-4.5 yr, and both sexes live for 5-7 yr. Males remain fertile until death. Some care is required to maintain healthy degus, particularly breeding females. Here we describe husbandry and breeding guidelines from the experience of the University of Michigan degu colony. With the husbandry practices described here, 90% of pups born in our colony reach maturity (6 mo of age), and no diarrheal diseases are apparent in our adult population.

Determinants of inter-specific variation in basal metabolic rate.

Basal metabolic rate (BMR) is the rate of metabolism of a resting, postabsorptive, non-reproductive, adult bird or mammal, measured during the inactive circadian phase at a thermoneutral temperature. BMR is one of the most widely measured physiological traits, and data are available for over 1,200 species. With data available for such a wide range of species, BMR is a benchmark measurement in ecological and evolutionary physiology, and is often used as a reference against which other levels of metabolism are compared. Implicit in such comparisons is the assumption that BMR is invariant for a given species and that it therefore represents a stable point of comparison. However, BMR shows substantial variation between individuals, populations and species. Investigation of the ultimate (evolutionary) explanations for these differences remains an active area of inquiry, and explanation of size-related trends remains a contentious area. Whereas explanations for the scaling of BMR are generally mechanistic and claim ties to the first principles of chemistry and physics, investigations of mass-independent variation typically take an evolutionary perspective and have demonstrated that BMR is ultimately linked with a range of extrinsic variables including diet, habitat temperature, and net primary productivity. Here we review explanations for size-related and mass-independent variation in the BMR of animals, and suggest ways that the various explanations can be evaluated and integrated.

Determinants of intra-specific variation in basal metabolic rate.

Basal metabolic rate (BMR) provides a widely accepted benchmark of metabolic expenditure for endotherms under laboratory and natural conditions. While most studies examining BMR have concentrated on inter-specific variation, relatively less attention has been paid to the determinants of within-species variation. Even fewer studies have analysed the determinants of within-species BMR variation corrected for the strong influence of body mass by appropriate means (e.g. ANCOVA). Here, we review recent advancements in studies on the quantitative genetics of BMR and organ mass variation, along with their molecular genetics. Next, we decompose BMR variation at the organ, tissue and molecular level. We conclude that within-species variation in BMR and its components have a clear genetic signature, and are functionally linked to key metabolic process at all levels of biological organization. We highlight the need to integrate molecular genetics with conventional metabolic field studies to reveal the adaptive significance of metabolic variation. Since comparing gene expressions inter-specifically is problematic, within-species studies are more likely to inform us about the genetic underpinnings of BMR. We also urge for better integration of animal and medical research on BMR; the latter is quickly advancing thanks to the application of imaging technologies and 'omics' studies. We also suggest that much insight on the biochemical and molecular underpinnings of BMR variation can be gained from integrating studies on the mammalian target of rapamycin (mTOR), which appears to be the major regulatory pathway influencing the key molecular components of BMR.