Effects Of Reproductive Status Research Articles

Evaluating impact of season and corpus luteum cavitation on serum progesterone concentration and pregnancy in a Holstein dairy herd

The corpus luteum (CL) is vital to bovine reproduction and can present in 2 forms on ultrasound examination: homoge­neous or cavitary. Impact of CL cavitation on fertility in cattle has been debated. Many variables influence fertility includ­ing heat stress, but little is known regarding the impact of season and risk of association with a cavitary CL. The objec­tives of this study were to evaluate: (1) effect of CL form on serum progesterone, and (2) effect of reproductive status and season on the likelihood of diagnosing a cavitary CL. Blood from Holstein cows (n = 787) on a commercial dairy farm was collected (n = 1,062) at 39-45 days post-insemination. Some cows were sampled more than once. Corpora lutea were categorized as homogeneous or cavitary, and cows were diagnosed as either pregnant or non-pregnant via transrectal ultrasonography at time of blood collection. When adjusted for season and CL status, pregnant cows produced higher serum progesterone (6.880 ng/mL; 95% CI [6.606, 7.153]) than non-pregnant cows (4.664 ng/mL; 95% CI [4.398, 4.931], P < 0.001). When adjusted for progesterone levels and season, pregnant cows were 94.7% less likely (OR = 0.053, P < 0.001) to be diagnosed with a cavitary CL com­pared to non-pregnant cows. No difference was observed in serum progesterone by CL form (P = 0.393). Serum progester­one was significantly lower in summer than fall (P < 0.001), winter (P < 0.001) and spring (P = 0.005). Season did not impact likelihood of diagnosing a cavitary CL.

Pregnancy-induced oxidative stress and inflammation are not associated with impaired maternal neuronal activity or memory function.

Pregnancy is associated with neural and behavioral plasticity, systemic inflammation, and oxidative stress, yet the impact of inflammation and oxidative stress on maternal neural and behavioral plasticity during pregnancy is unclear. We hypothesized that healthy pregnancy transiently reduces learning and memory and these deficits are associated with pregnancy-induced elevations in inflammation and oxidative stress. Cognitive performance was tested with novel object recognition (recollective memory), Morris water maze (spatial memory), and open field (anxiety-like) behavior tasks in female Sprague-Dawley rats of varying reproductive states [nonpregnant (nulliparous), pregnant (near term), and 1-2 mo after pregnancy (primiparous); n = 7 or 8/group]. Plasma and CA1 proinflammatory cytokines were measured with a MILLIPLEX magnetic bead assay. Plasma oxidative stress was measured via advanced oxidation protein products (AOPP) assay. CA1 markers of oxidative stress, neuronal activity, and apoptosis were quantified via Western blot analysis. Our results demonstrate that CA1 oxidative stress-associated markers were elevated in pregnant compared with nulliparous rats (P ≤ 0.017) but there were equivalent levels in pregnant and primiparous rats. In contrast, reproductive state did not impact CA1 inflammatory cytokines, neuronal activity, or apoptosis. Likewise, there was no effect of reproductive state on recollective or spatial memory. Even so, spatial learning was impaired (P ≤ 0.007) whereas anxiety-like behavior (P ≤ 0.034) was reduced in primiparous rats. Overall, our data suggest that maternal hippocampal CA1 is protected from systemic inflammation but vulnerable to peripartum oxidative stress. Peripartum oxidative stress elevations, such as in pregnancy complications, may contribute to peripartum neural and behavioral plasticity.NEW & NOTEWORTHY Healthy pregnancy is associated with elevated maternal systemic and brain oxidative stress. During postpregnancy, brain oxidative stress remains elevated whereas systemic oxidative stress is resolved. This sustained maternal brain oxidative stress is associated with learning impairments and decreased anxiety-like behavior during the postpregnancy period.

Causes and consequences of pre-hibernation body mass in golden-mantled ground squirrels (Callospermophilus lateralis)

Abstract Mammals that cope with harsh environmental conditions by hibernating show seasonal variation in body mass, as fat reserves are accumulated during summer and depleted during winter. In hibernating species, pre-hibernation mass is often considered a key phenotypic trait that can influence future survival and reproductive success—yet we know little about how variation in environmental conditions and seasonality affect pre-hibernation mass. We used 30 years of demographic data from a high-elevation population of golden-mantled ground squirrels (Callospermophilus lateralis) to identify life history and environmental variables that influenced pre-hibernation mass in females. Additionally, we determined if pre-hibernation mass influenced overwinter survival or subsequent reproduction. Growth curves revealed female-biased size dimorphism in body mass; adult mass was not attained until age 2 years, so we considered 3 age classes of females: juveniles, yearlings, and adults (≥2 years). We found that earlier snow melt during spring is associated with higher subsequent pre-hibernation body mass for yearlings and adults, and that juveniles emerging earlier from their natal burrows had higher pre-hibernation masses than later-emerging juveniles. Estimates of food quantity or quality did not affect pre-hibernation mass for any age class, nor was there an effect of reproductive status. Juvenile females with greater pre-hibernation mass were more likely to survive overwinter and reproduce as yearlings, but we found no such effect for yearlings or adult females. We did not find an effect of snow depth or winter duration on either survival or reproduction. Our results indicate that time appears to be the key variable for golden-mantled ground squirrels to acquire sufficient body mass to survive and reproduce, but the effects vary by age class.

Effects of reproductive status on behavioral and neural responses to isolated pup stimuli in female California mice

The transition to motherhood in mammals is marked by changes in females’ perception of and responsiveness to sensory stimuli from infants. Our understanding of maternally induced sensory plasticity relies most heavily on studies in uniparental, promiscuous house mice and rats, which may not be representative of rodent species with different life histories. We exposed biparental, monogamous California mouse (Peromyscus californicus) mothers and ovariectomized virgin females to one of four acoustic and olfactory stimulus combinations (Control: clean cotton and white noise; Call: clean cotton and pup vocalizations; Odor: pup-scented cotton and white noise; Call + Odor: pup-scented cotton and pup vocalizations) and quantified females’ behavior and Fos expression in select brain regions. Behavior did not differ between mothers and ovariectomized virgins. Among mothers, however, those exposed to the Control condition took the longest to sniff the odor stimulus, and mothers exposed to the Odor condition were quicker to sniff the odor ball compared to those in the Call condition. Behavior did not differ among ovariectomized virgins exposed to the different conditions. Fos expression differed across conditions only in the anterior hypothalamic nucleus (AHN), which responds to aversive stimuli: among mothers, the Control condition elicited the highest AHN Fos and Call + Odor elicited the lowest. Among ovariectomized virgin females, Call elicited the lowest Fos in the AHN. Thus, reproductive status in California mice alters females’ behavioral responses to stimuli from pups, especially odors, and results in the inhibition of defense circuitry in response to pup stimuli.

Effect of Reproductive Status on Some Biochemical Parameters in American Shad

The pattern of some blood biochemical parameters of adult American shad (Alosa sapidissima) was investigated during their reproductive cycle. A total of 288 sub adult broodstocks were captured between October 2015 and September 2016, in which ten brood stock for each developmental stage were selected based on similar length and weight to evaluate the overall health status of the fishes. The results showed that the serum levels of total protein (TP), albumin (Alb), globulin (Glb), glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (ALT), low-density lipoprotein (LDL), high-density lipoprotein (HDL), plasma glucose (Glu), triglycerides (TG), total cholesterol (TC), Ca2+ and P of the American shad brood stock (females and males) significantly increased as their gonads developed, reaching the highest at stages IV and V, after which that the above mentioned parameters substantially decreased at stage VI. The TC and TG levels in females significantly increased from stage II to stage V, and then the levels began to decrease after spawning (stage VI), but there was no significant difference between TC and TG levels in male shad. With the development of the gonads, the plasma glucose (Glu), superoxide dismutase (SOD), catalase (CAT), and lysozyme (LZM) levels in both male and female brood stocks showed different degrees of decline, especially, in stages V (spawning period) and VI (postnatal period), these parameters significantly decreased. The results of this study indicate that the physiological parameters, such as blood glucose level, blood lipid level and antioxidant capacity, of American shad brood stocks, especially females, show varying degrees of reduction during reproduction, which suggests that nutritional imbalance significantly reduces immunity during the postnatal period.

Effect of Reproductive Status and Body Mass Index on Serum Concentrations of Thyroid Hormones and Thyroid-stimulating Hormone in Women in Zaria, Northern Nigeria

Effect of Reproductive Status and Body Mass Index on Serum Concentrations of Thyroid Hormones and Thyroid-stimulating Hormone in Women in Zaria, Northern Nigeria

Ecological Factors Mediate Immunity and Parasitic Co-Infection in Sea Fan Octocorals.

The interplay among environment, demography, and host-parasite interactions is a challenging frontier. In the ocean, fundamental changes are occurring due to anthropogenic pressures, including increased disease outbreaks on coral reefs. These outbreaks include multiple parasites, calling into question how host immunity functions in this complex milieu. Our work investigates the interplay of factors influencing co-infection in the Caribbean sea fan octocoral, Gorgonia ventalina, using metrics of the innate immune response: cellular immunity and expression of candidate immune genes. We used existing copepod infections and live pathogen inoculation with the Aspergillus sydowii fungus, detecting increased expression of the immune recognition gene Tachylectin 5A (T5A) in response to both parasites. Cellular immunity increased by 8.16% in copepod infections compared to controls and single Aspergillus infections. We also detected activation of cellular immunity in reef populations, with a 13.6% increase during copepod infections. Cellular immunity was similar in the field and in the lab, increasing with copepod infections and not the fungus. Amoebocyte density and the expression of T5A and a matrix metalloproteinase (MMP) gene were also positively correlated across all treatments and colonies, irrespective of parasitic infection. We then assessed the scaling of immune metrics to population-level disease patterns and found random co-occurrence of copepods and fungus across 15 reefs in Puerto Rico. The results suggest immune activation by parasites may not alter parasite co-occurrence if factors other than immunity prevail in structuring parasite infection. We assessed non-immune factors in the field and found that sea fan colony size predicted infection by the copepod parasite. Moreover, the effect of infection on immunity was small relative to that of site differences and live coral cover, and similar to the effect of reproductive status. While additional immune data would shed light on the extent of this pattern, ecological factors may play a larger role than immunity in controlling parasite patterns in the wild. Parsing the effects of immunity and ecological factors in octocoral co-infection shows how disease depends on more than one host and one parasite and explores the application of co-infection research to a colonial marine organism.

The Effects of Reproductive Status and Water Temperature on the Caloric Intake of Tursiops truncatus

The Effects of Reproductive Status and Water Temperature on the Caloric Intake of Tursiops truncatus

Reproductive state and choline intake influence enrichment of plasma lysophosphatidylcholine-DHA: a post hoc analysis of a controlled feeding trial.

The major facilitator superfamily domain 2a protein was identified recently as a lysophosphatidylcholine (LPC) symporter with high affinity for LPC species enriched with DHA (LPC-DHA). To test the hypothesis that reproductive state and choline intake influence plasma LPC-DHA, we performed a post hoc analysis of samples available through 10weeks of a previously conducted feeding study, which provided two doses of choline (480 and 930mg/d) to non-pregnant (n 21), third-trimester pregnant (n 26), and lactating (n 24) women; all participants consumed 200mg of supplemental DHA and 22% of their daily choline intake as 2H-labelled choline. The effects of reproductive state and choline intake on total LPC-DHA (expressed as a percentage of LPC) and plasma enrichments of labelled LPC and LPC-DHA were assessed using mixed and generalised linear models. Reproductive state interacted with time (P=0·001) to influence total LPC-DHA, which significantly increased by week 10 in non-pregnant women, but not in pregnant or lactating women. Contrary to total LPC-DHA, patterns of labelled LPC-DHA enrichments were discordant between pregnant and lactating women (P<0·05), suggestive of unique, reproductive state-specific mechanisms that result in reduced production and/or enhanced clearance of LPC-DHA during pregnancy and lactation. Regardless of the reproductive state, women consuming 930 v. 480mg choline per d exhibited no change in total LPC-DHA but higher d3-LPC-DHA (P=0·02), indicating that higher choline intakes favour the production of LPC-DHA from the phosphatidylethanolamine N-methyltransferase pathway of phosphatidylcholine biosynthesis. Our results warrant further investigation into the effect of reproductive state and dietary choline on LPC-DHA dynamics and its contribution to DHA status.

\u03a9-3 fatty acids-supplementary in gestation alleviates neuroinflammation and modulates neurochemistry in rats

BackgroundThe mechanisms underlying the association between immune activation and postpartum depression remained elusive. Although Ω-3 fatty acids possess anti-inflammatory properties, there is limited evidence directly linking the modulating effects of Ω-3 fatty acids on neuroimmune and neurochemistry to the antidepressant actions.MethodsA between-groups design was used to assess the effects of reproductive status (virgin or parous) and Ω-3 fatty acids content (control and supplementary). Serum inflammatory cytokine levels (IL-1a, IL-1β, IL-2, IL-6, IL-12, TNF-a, IFN-γ) were evaluated using the Bio-Plex Luminex System. Moreover, we also measured the protein levels of Purinergic type 2X7 receptor (P2X7R), NOD-like receptor pyrin domain containing 3 (NLRP3) and Nuclear factor-kappaB (NF-κB). Lastly, we assessed the function of various neurotransmitter systems to link the inflammatory response and neurotransmitter metabolism.ResultsPro-inflammatory cyrokines, including IL-1a, IL-6, TNF-a and IFN-γ were markedly induced in the serum of parous rats, although no significantly depressive-like behavior was found. Meanwhile, NLRP3 and NF-κB were decreased in certain brain areas. Moreover, gestational stress significantly induced neurochemical disturbance, which is partly restored by Ω-3 fatty acids supplementation.ConclusionsThese findings strengthen the link between inflammation, neurochemistry and postpartum depression, and further provide novel insights into the antidepressant effect of Ω-3 fatty acids.

Escape behavior in gravid and non-gravid females of Gonatodes albogularis (Squamata: Sphaerodactylidae)

Escape behavior in gravid and non-gravid females of Gonatodes albogularis (Squamata: Sphaerodactylidae). Theoretical models of predator-prey relationships describe tradeoffs between energetic and other costs of escape, effectiveness of escape behavior, and predation risk. These models predict that an animal will fee when the expected ftness cost due to risk of predation becomes equal to the the cost of the escape or post-encounter ftness is maximized, depending on the model. In this framework, several individual and ecological variables have been shown to affect escape patterns, but the effect of reproductive status has been studied in few species. We assess differences in escape behavior between gravid and non-gravid females of Gonatodes albogularis. Lizards were surveyed by applying a free search method along independent transects. For each lizard, we determined reproductive status as gravid or non-gravid and recorded several variables related to escape behavior. We made a discriminant function analysis to see whether the state of individuals affect escape behavior. Our results show that the escape variables distance fed, the fnal distance and the distance to refuge differ between gravid and non-gravid females. These fndings support predictions based on risk and cost, but do not support models of fight initiation distance. Such differences could be related to a physiological process known as behavioral compensation, through which some individuals (gravid females in our case) modify their behavior to offset predation risk. Further studies are needed to see if behavioral compensation can be explained in terms of adaptive processes in G. albogularis.

Motherhood and infant contact regulate neuroplasticity in the serotonergic midbrain dorsal raphe

The adult brain shows remarkable neuroplasticity in response to hormones and the socioemotional modifications that they influence. In females with reproductive and maternal experience, this neuroplasticity includes the birth and death of cells in several forebrain regions involved in maternal caregiving and postpartum affective state. Such plasticity in midbrain sites critical for these behavioral and emotional processes has never been examined, though. By visualizing bromodeoxyuridine (BrdU) to label mitotic cells, NeuroD for neuronal precursors, and TUNEL to identify dying cells, we found that the midbrain dorsal raphe nucleus (DR, the source of most ascending serotoninergic projections) exhibited significant neuroplasticity in response to motherhood. Specifically, BrdU analyses revealed that DR newborn cell survival (but not proliferation) was regulated by reproductive state, such that cells born early postpartum were less likely to survive 12 days to reach the late postpartum period compared to cells born during late pregnancy that survived 12 days to reach the early postpartum period. Many of the surviving cells in the DR were NeuN immunoreactive, suggesting a neuronal phenotype. Consistent with these findings, late postpartum rats had fewer NeuroD-immunoreactive DR cells than early postpartum rats. Maternal experience contributed to the late postpartum reduction in DR newborn cell survival because removing the litter at parturition increased cell survival as well as reduced cell death. Unlike cytogenesis in the maternal hippocampus, which is reduced by circulating glucocorticoids, DR newborn cell survival was unaffected by postpartum adrenalectomy. These effects of reproductive state and motherhood on DR plasticity were associated with concurrent changes in DR levels of serotonin's precursor, 5-HTP, and its metabolite, 5-HIAA. Our results demonstrate for the first time that cytogenesis occurs in the midbrain DR of any adult mammal, that DR plasticity is influenced by female reproductive state and maternal experience, and that this plasticity is accompanied by changes in DR serotonergic function. Because serotonin is critical for postpartum caregiving behaviors and maternal affective state, plasticity in the DR may contribute to the neurochemical changes necessary for successful motherhood.

Effect of pregnancy and correlation of weight and heart rate with electrocardiographic parameters in the American Miniature Horse

ABSTRACT There are studies on electrocardiogram (ECG) in several breeds of horses, which highlights the growing importance of cardiology in this species. But few authors have addressed the influence of pregnancy on the cardiac physiology of the mare, and specifically, there are no studies on the Mini-horse breed, as well as no correlation of body weight (BW) and heart rate (HR) with electrocardiographic parameters in this breed. The aims of this study were to determine the effects of pregnancy on ECG parameters and to examine the relationships between these variables and body weight (BW) and heart rate (HR). A total of 203 animals were used, including 143 females (66 pregnant) and 60 males. Electrocardiographic examinations were performed by computerized electrocardiogram (TEB), and the parameters were evaluated in six leads in the frontal plane (Lead I, II, III, aVR, aVL and aVF) and base-apex (BA). BW was inversely proportional to HR, which in turn showed an inverse relationship with the duration of the P-wave and the PR and QT intervals. The P-wave amplitude (lead II) was higher in pregnant animals than in non-pregnant animals. The effect of reproductive status should be monitored by ECG throughout the entire gestational period. The 66 pregnant mares in this study were examined during the first third of their pregnancies, thus, few differences were observed between pregnant and non-pregnant animals.

Sex steroid profiles in zebra finches: Effects of reproductive state and domestication

The zebra finch is a common model organism in neuroscience, endocrinology, and ethology. Zebra finches are generally considered opportunistic breeders, but the extent of their opportunism depends on the predictability of their habitat. This plasticity in the timing of breeding raises the question of how domestication, a process that increases environmental predictability, has affected their reproductive physiology. Here, we compared circulating steroid levels in various “strains” of zebra finches. In Study 1, using radioimmunoassay, we examined circulating testosterone levels in several strains of zebra finches (males and females). Subjects were wild or captive (Captive Wild-Caught, Wild-Derived, or Domesticated). In Study 2, using liquid chromatography–tandem mass spectrometry (LC–MS/MS), we examined circulating sex steroid profiles in wild and domesticated zebra finches (males and females). In Study 1, circulating testosterone levels in males differed across strains. In Study 2, six steroids were detectable in plasma from wild zebra finches (pregnenolone, progesterone, dehydroepiandrosterone (DHEA), testosterone, androsterone, and 5α-dihydrotestosterone (5α-DHT)). Only pregnenolone and progesterone levels changed across reproductive states in wild finches. Compared to wild zebra finches, domesticated zebra finches had elevated levels of circulating pregnenolone, progesterone, DHEA, testosterone, androstenedione, and androsterone. These data suggest that domestication has profoundly altered the endocrinology of this common model organism. These results have implications for interpreting studies of domesticated zebra finches, as well as studies of other domesticated species.

A note on the social compatibility of an all-male group of hamadryas baboons (Papio hamadryas)

In captive primates, the formation of all-male groups is used as a management tool to deal with surplus males. In the wild, hamadryas baboons ( Papio hamadryas ) live in multilevel societies consisting of reproductive one-male/multi-female units, clans, bands and troops. The social compatibility of all-male groups of hamadryas baboons has not been studied thus far. Here we examined the social compatibility of an all-male group of hamadryas baboons as compared to adult males of a mixed-sex group by focusing on social interactions. Additionally we studied the behavioural effects of reproductive status to evaluate whether surgical castration can assist in the social housing of surplus hamadryas baboons. The results indicate that intact males (n=3) in an all-male group show fairly similar behavioural profiles compared with intact males (n=3) in a mixed-sex group, although they are less often observed in social proximity. Furthermore, intact males within an all-male group engaged less in affiliative and submissive behaviours than castrated males (n=3) within the same group. Overall, our results suggest that the formation of an all-male group of hamadryas baboons can be a feasible management tool in housing surplus males, and that submissive behaviours as expressed by castrated males may contribute positively to the social stability of all-male groups.

The relationship of dominance, reproductive state and stress in female horses (Equus caballus)

Maintaining a dominant position in a hierarchy requires energetically expensive aggressive displays and physical exertion. Lab based winner–loser studies, often conducted with individuals from non-social species, have shown that subordinates have higher stress hormone levels than dominant individuals. However, in wild studies on cooperative breeders, displays of aggression used to maintain dominance status are associated with elevated stress hormone levels. The effect of reproductive state on dominance and stress has not been addressed within either of these situations. The purpose of this study was to examine physiological stress levels in relation to dominance rank and reproductive state in a non-cooperative breeder and herbivore, the domestic horse. The social interactions and measured faecal glucocorticoids were recorded in pastured, female horses that were either lactating or non-lactating. While faecal glucocorticoid metabolite level did not differ between reproductive state and rank, activity behaviour demonstrated significant differences between reproductive states. Higher energetic requirements of lactation were reflected in significantly longer bouts of eating and significantly less time spent alert and socializing. As non-cooperative breeders, the social nature of horses does not limit their reproduction or resource acquisition based upon rank, and therefore does not fit with the dominance-stress hypothesis or subordinate-stress hypothesis and instead supports a rank-independent stress hypothesis.

Oxidative stress in response to natural and experimentally elevated reproductive effort is tissue dependent

Summary Oxidative stress is a potential proximal physiological cost of reproduction. Detecting this cost may be performed in several different ways – manipulating reproductive status, correlating natural variations in effort to oxidative stress or manipulating reproductive effort. Here, we manipulated reproductive status and studied oxidative stress due to natural and experimental variation in reproductive effort in Brandt's voles (Lasiopodomys brandtii), using a variety of markers and tissues. We measured markers of oxidative stress in lactating (raising 6 to 8 offspring) and non‐reproductive voles (Experiment I) and found that a marker of oxidative protection [serum total‐superoxide dismutase (SOD) activity] was reduced, and a marker of oxidative damage (protein carbonyls) was increased, in the serum, in lactating compared with non‐reproductive voles. However, protein carbonyls in the liver were lower in lactating compared with non‐reproductive voles, consistent with increased liver SOD activity. Lipid damage [malonaldehyde (MDA)] in both serum and liver was unrelated to reproductive status. We compared these markers of oxidative stress between natural large (n ≥ 9) and small litter sizes (n ≤ 5; Experiment II), and between manipulated large (11–13) and small litter sizes (2–3; Experiment III) and found that liver MDA and SOD activity was higher in voles with natural large compared with natural small litter sizes, but there were no differences in other markers. There was no effect of litter size on all measures when it was experimentally manipulated. The effects of reproductive status on oxidative stress were critically dependent on the exact markers and tissues used. The effects of natural variation in reproductive effort suggested that there might be an oxidative stress cost associated with large litter sizes, but this effect was not replicated in the experimentally manipulated litters.

Effect of reproductive status on hypothalamic–pituitary–adrenal (HPA) activity and reactivity in male California mice (Peromyscus californicus)

Previous studies indicate that reproductive condition can alter stress response and glucocorticoid release. Although the functional significance of hypothalamic–pituitary–adrenal (HPA) axis modulation by breeding condition is not fully understood, one possible explanation is the behavior hypothesis, which states that an animal's need to express parental behavior may be driving modulation of the HPA axis. This possibility is consistent with findings of blunted activity and reactivity of the HPA axis in lactating female mammals; however, effects of reproductive status on HPA function have not been well characterized in male mammals that express parental behavior. Therefore, we tested this hypothesis in the monogamous and biparental California mouse. Several aspects of HPA activity were compared in males from three reproductive conditions: virgin males (housed with another male), non-breeding males (housed with a tubally ligated female), and first-time fathers (housed with a female and their first litter of pups). In light of the behavior hypothesis we predicted that new fathers would differ from virgin and non-breeding males in several aspects of HPA function and corticosterone (CORT) output: decreased amplitude of the diurnal rhythm in CORT, a blunted CORT increase following predator-odor stress, increased sensitivity to glucocorticoid negative feedback, and/or a blunted CORT response to pharmacological stimulation. In addition, we predicted that first-time fathers would be more resistant to CORT-induced suppression of testosterone secretion, as testosterone is important for paternal behavior in this species. We found that virgin males, non-breeding males and first-time fathers did not display any CORT differences in diurnal rhythm, response to a predator-odor stressor, or response to pharmacological suppression or stimulation. Additionally, there were no differences in circulating testosterone concentrations. Adrenal mass was, however, significantly lower in new fathers than in virgin or non-breeding males. These results suggest that the behavior hypothesis does not explain HPA function across reproductive conditions in male California mice.

Effect of reproductive status, magnetic field exposure and photoperiod on temporal organization in air-gulping activity in Clarias batrachus

The present study examined effects of pulsed magnetic field exposure (daily one hour magnetic field exposure at two times, 08:00–09:00 h and 16:00–17:00 h, 4000 Gauss) and continuous magnetic field exposure (4000 Gauss) for 30 days under LD (12:12), LL, and DD on temporal organization in air gulping activity in Indian freshwater catfish, Clarias batrachus, during different phases of its annual reproductive cycle. The air-gulping activity was monitored manually for about 15 minutes at four time-points (08:00 h, 12:00 h, 14:00 h, and 16:00 h) in each group. Time of day, photoperiod and magnetic field exposure all produced statistically significant effects on air-gulping activity during different phases of the annual reproductive cycle, excluding the spawning phase. The changes due to magnetic field exposure did not depend upon photoperiod. During most of the phases of the reproductive cycle, an increase or decrease in air-gulping activity was observed under DD and LL, respectively. It is concluded that air-gulping activity in C. batrachus exhibits daily variation, and that magnetic field exposure and photoperiod both produce modulatory effects on such activity.

A fecundity cost of (walking) mobility in an insect

Evolutionary theory predicts trade-offs between fecundity and mobility, but there is substantial lack of empirical evidence if and how basic mobility relates to fitness costs. In a field experiment, we investigated fecundity costs of mobility in a non-migratory, wing-monomorphic grasshopper, Stenobothrus lineatus, and at the same time tested for possible effects of reproductive state (egg-load) on the mobility. For 10 days, body weight and activity radius of 60 females were recorded daily and oviposition events were inferred from abrupt weight losses. We found a strong and significant relationship between the individual mobility and the time between egg pods laid (interpod period). Individual egg-laying was reduced by a rate of 0.36 eggs per day with each meter increase in mean daily activity radius. The trade-off was not biased by the size of the females, that is, constitution did not positively influence both offspring number and mobility. Egg-load had no significant influence on the individual distances travelled. We could demonstrate that mobility – as induced and selected for by foraging, thermoregulation, predator escape, shelter seeking, and reproduction – can be directly paid off by fecundity. This direct consequence of mobility on individual fitness was detected for the first time in a walking insect.