Effects of Wolf Spiders' Captive Environment on Their Locomotor and Exploratory Behaviours.

Here I detail the effects of the abiotic/captive environment of an adult wandering spider, Pardosa saltans (Lycosidae) on its behaviour. These studies focused on spiders collected as adults in their natural environment and spiders developed in the laboratory under controlled conditions. Wild-caught spiders were tested either immediately after capture or after being housed for 15 days post-collection. Laboratory reared spiders were kept in different environments: small or large space combined with the presence or absence of litter. Two tests evaluated by sex show the influence of these rearing conditions: an open-field test and a radial-arm maze test. The results show that wild caught spiders of both sexes tested immediately after capture weighed significantly less and were significantly more active than spiders housed in the laboratory for 15 days and spiders reared in the laboratory. Laboratory conditions induced a positive impact on body mass and negative impact on behaviour activities. The locomotor and exploratory activities of spiders of both sexes kept in container without substrate showed lower. My results suggest that the physical enrichment of the environment can reduce these negative effects for females, but not for males that seem to be more affected by being reared under controlled conditions.

Transport pathways of hydrocarbon and free fatty acids to the cuticle in arthropods and hypothetical models in spiders.

Cuticular lipids in terrestrial arthropods are not only essential for desiccation resistance; they also play an important role as chemical signals for intra- and interspecific communication (pheromones and kairomones, respectively). Most of the studies on cuticular lipid research was dedicated to one class of arthropods, the insects. This type of research on the class arachnids is poorly developed, and the majority of studies has listed the compounds present in cuticular extracts, and, in some cases, compared the lipid profiles of different life stages (juveniles, adults). Consequently, we reviewed in relation to lipids description, biosynthesis, and transport of spiders. To illustrate a novel concept of lipid transportation, a scheme is now presented to show the hypothetical transport pathways of hydrocarbon and free fatty acids to cuticle in spiders. These concepts are taken from the knowledge of different arachnids to obtain a general illustration on the biosynthesis and transport of hemolymphatic lipids to the cuticle in spider.

Variations of cocoon external lipids during wolf spiderlings' development.

This study presents the first characterisation of the silk lipids of the cocoons of a wolf spider (Pardosa saltans). Wolf spiders' maternal behaviour is complex and involves guarding a cocoon for several weeks, and so cocoons must emit cues to ensure their care and the development of juveniles. We investigated cues associated with the cocoon silk. We assessed qualitative changes of the lipid contents and the composition of cocoon silk in relation to the development of P. saltans wolf spider juveniles. Gas chromatography-mass spectrometry of P. saltans' cocoon silk revealed 62 different lipid compounds. The compounds were aliphatic alcohols, glycerides, fatty acids and their methylesters containing 13-29 carbon atoms. We reveal for the first time the presence of ethanolamides and phytosterol on cocoon silk. Qualitative and quantitative changes occur during the embryonic period, as some polar compounds, such as diglycerides and ethanolamides, disappeared while hydrocarbons emerge, and fatty acids disappeared later during the post-embryonic period. Qualitative and/or quantitative changes could play a role in tactochemical communication between mothers and their cocoon. However, mothers do not modify their behaviour in relation to the developmental stage of their cocoon. Mothers' behaviour appears to be linked to both internal (physiological state) and external mechanisms (signals from the cocoon).

Age and egg-sac loss determine maternal behaviour and locomotor activity of wolf spiders (Araneae, Lycosidae).

Wolf spiders' (Lycosidae) maternal behaviour includes a specific phase called "egg brooding" which consists of guarding and carrying an egg-sac throughout the incubation period. The transport of an egg-sac can restrict mothers' exploratory and locomotor activity, in particular when foraging. The present study details the ontogeny of maternal behaviour and assesses the influence of age of egg-sac (or embryos' developmental stage) on vagrant wolf spider Pardosa saltans females' exploration and locomotion. We observed these spiders' maternal behaviour in the laboratory and evaluated their locomotor activity using a digital activity recording device. Our subjects were virgin females (without egg-sac) and first time mothers (with her egg-sac) who were divided into three groups. The first group of mothers were tested on the day the egg-sac was built (day 0), and the females of the other two groups were tested 10 or 15days after they had built their egg-sac. We evaluated the effects of the presence and the loss of egg-sac on mothers' activity. Pardosa saltans females' behaviour depended on mothers' physiological state and/or age of egg-sac (developmental stage of embryos). Virgin females' behaviour was not modified by the presence of an egg-sac in their environment. Mothers' reactions to the presence, the loss and the recovery of their egg-sac varied during the maternal cycle. Maternal behaviour changed with age of egg-sac, but the levels of locomotor activity of mothers with egg-sacs was similar to those of virgin females. Loss of egg-sac modified the maternal behaviour and locomotor activity of all mothers; these modifications were greater on "day 15" when embryos had emerged from eggs. All mothers were able to retrieve their egg-sacs and to re-attach them to their spinnerets.

Physiological costs during the first maternal care in the wolf spider Pardosa saltans (Araneae, Lycosidae).

Many arachnids like other terrestrial arthropods, provide extensive maternal care. Few studies have quantified the underlying physiological costs of maternal care. We investigated how maternal care affects the free-moving wolf spider's (Pardosa saltans) energy requirements. We described in detail their basic reproduction biology (i.e. carrying cocoon and young) and we evaluated the variation in the females' energy reserves during maternal care. Our results show that mothers guard eggs until hatching and then guard their spiderlings for 27-30 more days. Laboratory observations indicated that spiderlings start leaving the maternal abdomen gradually 5-7days after hatching. Females carry an egg sac (cocoon) that can weigh up to 77% of their post-reproduction weight and carry young that weigh 87-100% of their body mass. Females lost weight over time despite regular food intake, while carrying cocoon and young; but their weights increased gradually during the dispersal of young. The contributions of proteins, glucose and triglycerides to maintain females' energy were calculated. Their energetic state varied during maternal care, in particular lipid levels declined, during the care of spiderlings when the females' predatory behaviour was inhibited. Our results show that the maternal care provided by P. saltans females is particularly costly physiologically, during the 30days following egg sac formation and development of spiderlings, even when food is available.

Mares prefer the voices of highly fertile stallions.

We investigated the possibility that stallion whinnies, known to encode caller size, also encoded information about caller arousal and fertility, and the reactions of mares in relation to type of voice. Voice acoustic features are correlated with arousal and reproduction success, the lower-pitched the stallion's voice, the slower his heart beat and the higher his fertility. Females from three study groups preferred playbacks of low-pitched voices. Hence, females are attracted by frequencies encoding for large male size, calmness and high fertility. More work is needed to explore the relative importance of morpho-physiological features. Assortative mating may be involved as large females preferred voices of larger stallions. Our study contributes to basic and applied ongoing research on mammal reproduction, and questions the mechanisms used by females to detect males' fertility.

Long-life partners or sex friends? Impact of parental pair bond on offspring personality.

Previous investigations reported that some traits of parental relationships, including pair-bond duration or mate behavioural compatibility, influence subsequent offspring fitness by acting on their behaviour and growth and thus their early survival. We hypothesized that the development of a pair bond between sexual partners would have a prenatal influence. This study investigated the impact of two pairing managements on the egg characteristics and development of offspring of Japanese quail (Coturnix c. japonica). Thirty males and 30 females were paired either continuously (C; mates together all the time) or non-continuously (NC; pairs met only three times a week for 5 min). Separation-reunion tests evaluated parental pair bond. Egg yolk testosterone and androstenedione levels were evaluated, and the somatic and behavioural development of C and NC chicks was assessed. Our results revealed that members of C pairs were attached to their mates and, although no significant differences in androgen levels could be evidenced between egg sets, a higher proportion of C pairs' eggs were fertilized and their chicks appeared less emotive and more social. Our results revealed that the parental relationship can modulate the behavioural development of their offspring, probably via non-genetic effects, and this could play a major role in the emergence of inter-individual variability.

It takes a mouth to eat and a nose to breathe: abnormal oral respiration affects neonates' oral competence and systemic adaptation.

Mammalian, including human, neonates are considered to be obligate nose breathers. When constrained to breathe through their mouth in response to obstructed or closed nasal passages, the effects are pervasive and profound, and sometimes last into adulthood. The present paper briefly surveys neonates' and infants' responses to this atypical mobilisation of the mouth for breathing and focuses on comparisons between human newborns and infants and the neonatal rat model. We present the effects of forced oral breathing on neonatal rats induced by experimental nasal obstruction. We assessed the multilevel consequences on physiological, structural, and behavioural variables, both during and after the obstruction episode. The effects of the compensatory mobilisation of oral resources for breathing are discussed in the light of the adaptive development of oromotor functions.

Craniofacial development and physiological state after early oral breathing in rats.

In this study we determined whether craniofacial development in rats could be influenced by an early temporary (3 d) nasal obstruction associated with forced oral breathing. The rats were killed at specific time points after surgery. Plasma samples were taken for biochemical analyses, and cephalometric measurements were performed. Shortly after nasal obstruction, the vertical nasomaxillary complex and the longitudinal skull base proved to be smaller in both sexes of test rats compared with controls. This was maintained in male rats but not in female rats. In female rats, only the longitudinal skull base remained somewhat shorter as the animals grew older. Reversible nasal obstruction was further associated with reduced dimensions of the olfactory bulbs lasting into adulthood and an initial decrease in lung weight. One day after implementing nasal obstruction, basal corticosterone levels had increased (by over 1,000%) and stayed at a high level in female rats. In male rats, however, the corticosterone level seemed to return to normal by day 90. Oral breathing was also associated with a lower level of thyroid hormone, especially at the shorter term intervals in both sexes. We conclude that a 3-d nasal obstruction period in young rats leads to long-term hormonal changes and to craniofacial structural adaptation.

Juvenile development, ecdysteroids and hemolymph level of metabolites in the spider Brachypelma albopilosum (Theraphosidae).

In the present work, juvenile development and physiological state of mygalomorph Brachypelma albopilosum were investigated by means of individual rearing under controlled conditions. Males required 4-5 years for development from first juvenile instar to adulthood, passing through 8 to 12 juvenile molts. Females developed to adults in 5-6 years with a variable juvenile molt number from 9 to 13. The development and growth of males and females took place in a similar way until the last juvenile molt leading to subadults. Ecdysteroids, total lipid, cholesterol, and protein concentrations increased along with the different development instars in both males and females. After the last juvenile molt, spiders presented morphological and biochemical sex differences. Subadult and adulthood males were smaller in size and weight than females; hemolymph levels of ecdysteroids, total lipids, cholesterol, and glucose were higher in males. These physiological and biochemical differences can be correlated to the different sexual development between males and females.

Effects of short term forced oral breathing: physiological changes and structural adaptation of diaphragm and orofacial muscles in rats.

OBJECTIVE: We studied adaptation of diaphragm and orofacial muscles as well as hormonal responses to forced oral breathing (lasting for only 4 days) following reversible bilateral nasal obstruction performed on day 8 post-natal male rats. DESIGN: Muscle myosin heavy chain (MHC) composition and hormone levels were analysed during two periods: 1 and 3 days after obstruction (days 9 and 11 post-natal), and following 3 months recovery with nasal breathing (90 days, adult). RESULTS: Diaphragm muscle showed significant increases in adult isoforms (MHC 1, 2a) in oral breathing group versus control. We observed increases in MHC neonatal and adult type 1 isoforms in muscles involved with oral breathing, masseter superficialis and anterior digastric. No changes were observed in the levator nasolabialis muscle involved with nasal breathing. Reversible nasal obstruction was associated with reduced growth of the olfactory bulbs lasting into adulthood, and an initial decrease in lung growth followed by recovery at 90 days. Adrenal hypertrophy was observed after 1 day of nasal obstruction and lasted into adulthood. The "stress" hormone response was variable, increased (over 1000%) during the obstruction but normal by adulthood. An increase in plasma testosterone was observed during the obstruction, and a decrease in thyroid hormone levels throughout. CONCLUSIONS: Very short term nasal obstruction, i.e. forced oral breathing, leads to long term hormonal changes and respiratory muscle fibre adaptation.

In vitro digestibility of α-casozepine, a benzodiazepine-like peptide from bovine casein, and biological activity of its main proteolytic fragment.

α-Casozepine is a peptide, corresponding to the sequence 91-100 of the bovine α(s1)-casein, displaying anxiolytic activity in the rat. The α(s1)-casein tryptic hydrolysate containing this peptide decreases stress effects after oral administration in various species including man. Therefore, the stability of this peptide toward gastric and pancreatic proteases has been assessed by using pepsin, chymotrypsin/trypsin, Corolase PP, pepsin followed by chymotrypsin/trypsin or pepsin followed by Corolase PP. α-Casozepine was slowly degraded by chymotrypsin, much more sensitive to pepsin and Corolase PP but not completely destroyed after 4 h kinetics. The bonds in the region 91 to 95 of the α-casozepine were totally resistant to hydrolysis by all studied proteases. Surprisingly, a fragment, corresponding to the sequence 91-97 and found in all the hydrolysis media in significant amount, possessed an anxiolytic activity in three behavioral tests measuring this parameter. This peptide could participate in the in vivo activity of α-casozepine.

Agonistic interactions, cuticular and hemolymphatic lipid variations during the foraging period in spider females Brachypelma albopilosa (Theraphosidae).

Agonistic behaviour and lipid state were examined in tarantula Brachypelma albopilosa females during the foraging period. Modulation of the agonistic behaviour of females was not connected to their body size. Results show that the agonistic pattern of females differed significantly from the predation pattern at the behavioural and lipid levels. Aggressive-foraging females had low predation behaviour. Quantitative lipid changes were observed in relation to agonistic behaviour and predation. The total lipid index was studied by colorimetric methods, and lipid compounds were analyzed by gas chromatography-mass spectrometry in cuticle and hemolymph of females. The lipid components were free fatty acids, methyl esters, cholesterol, and long-chain aliphatic hydrocarbons. Methyl esters were much more abundant in cuticular lipids; unsaturated free fatty acids (linoleic and oleic acids) and methyl esters (methyl linoleate and methyl stearate) predominated in the hemolymph. Spider aggression was positively correlated with lipid concentration (cholesterol, fatty acids, methyl esters and hydrocarbons) in the hemolymph and the levels of cuticular fatty acids. Lipid levels are hypothesized to have evolved as a regulatory factor of predation and agonistic behaviours in tarantula females.

Mother-pup interactions during a short olfactory deprivation period in young rats.

The effects of short-term bilateral naris occlusion (inducing olfactory deprivation) on mother-pup interactions, suckling behavior and hormonal status during post-natal development in Wistar rats were studied. Bilateral naris occlusion was performed on 8-day-old rat pups and its effects were evaluated at Day 9 and at Day 15. The narins opened spontaneously between Day 12 and 14. Olfactory-deprived pups exhibited a greater level of corticosterone at both ages versus untreated or sham animals. Olfactory deprivation via naris occlusion, in young rats, alters mother-pup interactions with a decrease in the duration of mother-pup retrieving and an increase in pup licking. Olfactory-deprived pups showed also a lower mean duration of nursing and a decrease in nipple attachment, which appeared related to difficulties in finding the nipple. Olfactory-deprived pups had difficulty recognizing their nest. These behavioral alterations were accompanied by a diminution in milk ingested and growth retardation associated with a reduced level of thyroxin at both 9 and 15 days of age.

Effects of short term forced oral breathing in rat pups on weight gain, hydration and stress.

Nasal obstruction is a risk factor in sleep-disordered breathing with a negative impact on the quality of life in humans. We investigated hydration changes produced by short term reversible, bilateral, nasal obstruction in young developing rat pups. Physiological parameters of growth (weight gain and gastric content weight) and dehydration were analyzed during two periods; during nasal obstruction at post-natal day 8 (days 9, 11 and 13), plus 7 and 90 days after recovery of nasal breathing (day 15 and adulthood). Body weight gain in oral breathing rat pups was slower compared to controls. Gastric weight was decreased significantly only in oral breathing rat pups on days 9 and 11 while plasma osmolality and vasopressin levels increased (indicators of dehydration). There were no differences between controls and treated rat pups by day 15, or at adulthood. Short term nasal obstruction-induced forced oral breathing, decreased gastric content which had a negative impact on growth and blood glucose concentration in the short term for female rat pups. Plasma corticosterone levels increased during the dehydration but were normal in males by 90 days. This could be a model for blocked nose syndrome in the newborn. Possible long term consequences on development are discussed.

Increased ROS production: a component of the longevity equation in the male mygalomorph, Brachypelma albopilosa.

BACKGROUND: The diversity of longevities encountered in wildlife is one of the most intriguing problems in biology. Evolutionary biologists have proposed different theories to explain how longevity variability may be driven by bad genes expression in late life or by gene pleiotropic effects. This reflexion has stimulated, in the last ten years, an active research on the proximal mechanisms that can shape lifespan. Reactive oxygen species (ROS), i.e., the by-products of oxidative metabolism, have emerged as the main proximate cause of ageing. Because ROS are mainly produced by the mitochondria, their production is linked to metabolic rate, and this may explain the differences in longevity between large and small species. However, their implication in the sex difference in longevity within a species has never been tested, despite the fact that these differences are widespread in the animal kingdom. METHODOLOGY/PRINCIPAL FINDINGS: Mitochondrial superoxide production of hemolymph immune cells and antioxidant and oxidative damages plasma levels were measured in adult male and female B. albopilosa at different ages. We found that female spiders are producing less mitochondrial superoxide, are better protected against oxidative attack and are then suffering less oxidative damages than males at adulthood. CONCLUSIONS/SIGNIFICANCE: In tarantulas, once reaching sexual maturity, males have a life expectancy reduced to 1 to 2 years, while females can still live for 20 years, in spite of the fact that females continue to grow and moult. This study evidences an increased exposure of males to oxidative stress due to an increase in mitochondrial superoxide production and a decrease in hemolymph antioxidant defences. Such a phenomenon is likely to be part of the explanation for the sharp reduction of longevity accompanying male tarantula maturity. This opens several fundamental research roads in the future to better understand how reproduction and longevity are linked in an original ageing model.

Differences in Brachypelma albopilosa (Theraphosidae) hemolymph proteome between subadult and adult females.

The changes in the hemolymph proteome of mygalomorph Brachypelma albopilosa females were examined for the first time in relation to their developmental stage (subadult and adult period). Seven distinct subunits of hemocyanin (a, b, c, d, e, f, and g chains), as well as actin were clearly identified and their sequence partly characterized using a combination of one- and two-dimensional gel electrophoresis and mass spectrometry. The different structures determined along with possible post-translational modifications may reflect a role of hemocyanin in molting, immunity, and reproduction. In addition, despite no precise identification, additional peptide sequences from eight protein bands (four bands >200 kDa and four bands in the 95-200 kDa mass range) were determined. As reported in other spider species, the putative corresponding structures are the coagulogen protein and/or lipoproteins (HDL-1, HDL-2, VHDL) for which quantitative differences between adult and subadult individuals could be related to the molting process and/or cuticle lipid and protein composition according to the developmental stage.