Prenatal alcohol exposure reduces the proportion of newly produced neurons and glia in the dentate gyrus of the hippocampus in female rats

Prenatal alcohol exposure (PAE) alters adult neurogenesis and the neurogenic response to stress in male rats. As the effects of stress on neurogenesis are sexually dimorphic, the present study investigated the effects of PAE on adult hippocampal neurogenesis under both nonstressed and stressed conditions in female rats. Pregnant females were assigned to one of three prenatal treatments: (1) alcohol (PAE)—liquid alcohol (ethanol) diet ad libitum (36% ethanol-derived calories); (2) pair-fed—isocaloric liquid diet, with maltose–dextrin substituted for ethanol, in the amount consumed by a PAE partner (g/kg body wt/day of gestation); and (3) control—lab chow ad libitum. Female offspring were assigned to either nonstressed (undisturbed) or stressed (repeated restraint stress for 9 days) conditions. On day 10, all rats were injected with bromodeoxyuridine (BrdU) and perfused either 24 hours (cell proliferation) or 3 weeks (cell survival) later. We found that PAE did not significantly alter cell proliferation or survival, whereas females from the pair-fed condition exhibited elevated levels of cell survival compared to control females. Importantly, however, the proportion of both new neurons and new glial cells in the hippocampal dentate gyrus was reduced in PAE compared to control females. Exposure to stress did not alter neurogenesis in any of the prenatal treatment groups. In summary, compared to females from the control condition, prenatal dietary restriction enhanced the survival of new neurons, whereas PAE altered the differentiation of newly produced cells in the adult dentate gyrus. Alterations in hippocampal neurogenesis following PAE may contribute to learning and memory deficits seen in individuals with fetal alcohol spectrum disorders.     

Oral pioglitazone ameliorates fructose-induced peripheral insulin resistance and hippocampal gliosis but not restores inhibited hippocampal adult neurogenesis

Diet-associated insulin resistance (IR) is intimately correlated with the progression of metabolic syndrome and hippocampal dysfunction. Pioglitazone (PIO), a selective peroxisome proliferator-activated receptor gamma (PPARγ) agonist, has been applied to enhance insulin sensitivity. With limited permeability to blood-brain-barrier, it is unclear that whether oral PIO available to cure both the peripheral IR and the impairment in the hippocampus. We evaluated the levels of peripheral and hippocampal IR via the homeostatic model assessment of insulin resistance and hippocampal IRS-1/Akt phosphorylation, respectively, of Wistar Kyoto rats fed with a regular chew or high fructose diet (HFD) for 12 weeks. Gavage with PIO (30 mg/kg/day, 2 weeks) significantly reduced the peripheral IR and reversed the level of hippocampal PPARγ. Moreover, HFD-activated microglia and astrocyte were effectively relieved by PIO. The suppressed brain-derived neurotrophic factor, CaMKIIα, and postsynaptic density protein 95 in the hippocampus were effectively reversed by PIO. However, the hippocampal IR and inhibition of adult neurogenesis in dentate gyrus were not restored by PIO. Together, PIO oral application may reverse the HFD-induced peripheral IR and maintain the existed neuronal circuit by ameliorating glial activation and enhancing synaptic density through BDNF but failed to restore adult neurogenesis in the hippocampus.     

Social isolation impairs adult neurogenesis in the limbic system and alters behaviors in female prairie voles

Disruptions in the social environment, such as social isolation, are distressing and can induce various behavioral and neural changes in the distressed animal. We conducted a series of experiments to test the hypothesis that long-term social isolation affects brain plasticity and alters behavior in the highly social prairie vole (Microtus ochrogaster). In Experiment 1, adult female prairie voles were injected with a cell division marker, 5-bromo-2′-deoxyuridine (BrdU), and then same-sex pair-housed (control) or single-housed (isolation) for 6 weeks. Social isolation reduced cell proliferation, survival, and neuronal differentiation and altered cell death in the dentate gyrus of the hippocampus and the amygdala. In addition, social isolation reduced cell proliferation in the medial preoptic area and cell survival in the ventromedial hypothalamus. These data suggest that long-term social isolation affects distinct stages of adult neurogenesis in specific limbic brain regions. In Experiment 2, isolated females displayed higher levels of anxiety-like behaviors in both the open field and elevated plus maze tests and higher levels of depression-like behavior in the forced swim test than controls. Further, isolated females showed a higher level of affiliative behavior than controls, but the two groups did not differ in social recognition memory. Together, our data suggest that social isolation not only impairs cell proliferation, survival, and neuronal differentiation in limbic brain areas, but also alters anxiety-like, depression-like, and affiliative behaviors in adult female prairie voles. These data warrant further investigation of a possible link between altered neurogenesis within the limbic system and behavioral changes.     

Developmental fluoxetine exposure increases behavioral despair and alters epigenetic regulation of the hippocampal BDNF gene in adult female offspring

A growing number of infants are exposed to selective serotonin reuptake inhibitor (SSRI) medications during the perinatal period. Perinatal exposure to SSRI medications alter neuroplasticity and increase depressive- and anxiety-related behaviors, particularly in male offspring as little work has been done in female offspring to date. The long-term effects of SSRI on development can also differ with previous exposure to prenatal stress, a model of maternal depression. Because of the limited work done on the role of developmental SSRI exposure on neurobehavioral outcomes in female offspring, the aim of the present study was to investigate how developmental fluoxetine exposure affects anxiety and depression-like behavior, as well as the regulation of hippocampal brain-derived neurotrophic factor (BDNF) signaling in the hippocampus of adult female offspring. To do this female Sprague–Dawley rat offspring were exposed to prenatal stress and fluoxetine via the dam, for a total of four groups of female offspring: 1) No Stress + Vehicle, 2) No Stress + Fluoxetine, 3) Prenatal Stress + Vehicle, and 4) Prenatal Stress + Fluoxetine. Primary results show that, in adult female offspring, developmental SSRI exposure significantly increases behavioral despair measures on the forced swim test, decreases hippocampal BDNF exon IV mRNA levels, and increases levels of the repressive histone 3 lysine 27 tri-methylated mark at the corresponding promoter. There was also a significant negative correlation between hippocampal BDNF exon IV mRNA levels and immobility in the forced swim test. No effects of prenatal stress or developmental fluoxetine exposure were seen on tests of anxiety-like behavior. This research provides important evidence for the long-term programming effects of early-life exposure to SSRIs on female offspring, particularily with regard to affect–related behaviors and their underlying molecular mechanisms.     

Cold tolerance of the maize orange leafhopper,Cicadulina bipunctata

Cicadulina bipunctata was originally distributed in tropical and subtropical regions of the Old World. This leafhopper recently expanded its distribution area to southern parts of temperate Japan. In this study, factors affecting the overwintering ability of C. bipunctata were examined. A series of laboratory experiments revealed that cold acclimation at 15 °C for 7 days enhanced the cold tolerance of C. bipunctata to the same level as an overwintering population, adult females were more tolerant of cold temperature than adult males, and survival of acclimated adult females was highly dependent on temperature from −5 to 5 °C and exposure duration to the temperature. The temperature of crystallization of adult females was approximately −19 °C but temperatures in southern temperate Japan rarely dropped below −10 °C in the winter, indicating that overwintering C. bipunctata adults in temperate Japan are not killed by freezing injury but by indirect chilling injury caused by long-term exposure to moderately low temperatures. An overwintering generation of C. bipunctata had extremely low overwinter survival (<1%) in temperate Japan; however, based on winter temperature ranges, there are additional areas amenable to expansion of C. bipunctata in temperate Japan.     

The importance of relative humidity and trophic resources in governing ecological niche of the invasive carabid beetle Merizodus soledadinus in the Kerguelen archipelago

Comprehensive studies to identify species-specific drivers of survival to environmental stress, reproduction, growth, and recruitment are vital to gaining a better understanding of the main ecological factors shaping species habitat distribution and dispersal routes. The present study performed a field-based assessment of habitat distribution in the invasive carabid beetle Merizodus soledadinus for the Kerguelen archipelago. The results emphasised humid habitats as a key element of the insect’s realised niche. In addition, insects faced food and water stress during dispersal events. We evaluated quantitatively how water availability and trophic resources governed the spatial distribution of this invasive predatory insect at Îles Kerguelen. Food and water stress survival durations [in 100%, 70%, and 30% relative humidity (RH) conditions] and changes in a set of primary metabolic compounds (metabolomics) were determined. Adult M. soledadinus supplied with water ad libitum were highly tolerant to prolonged starvation (LT₅₀ = 51.7 ± 6.2 d). However, food-deprived insect survival decreased rapidly in moderate (70% RH, LT₅₀ = 30.37 ± 1.39 h) and low (30% RH, LT₅₀ = 13.03 ± 0.48 h) RH conditions. Consistently, body water content decreased rapidly in insects exposed to 70% and 30% RH. Metabolic variation evidenced the effects of food deprivation in control insects (exposed to 100% RH), which exhibited a progressive decline of most glycolytic sugars and tricarboxylic acid cycle intermediates. Most metabolite levels were elevated levels during the first few hours of exposure to 30% and 70% RH. Augmented alanine and lactate levels suggested a shift to anaerobic metabolism. Simultaneously, peaks in threonine and glycolytic sugars pointed to metabolic disruption and a progressive physiological breakdown in dehydrating individuals. Overall, the results of our study indicate that the geographic distribution of M. soledadinus populations is highly dependent on habitat RH and water accessibility.     

Effect of different levels of concentrate allowances on rumen fluid pH,nutrient digestion,nitrogen retention and growth performance of weaner lambs

This experiment was conducted for 90 d to assess the effect of feeding graded levels of concentrate allowance on rumen fermentation characteristics, performance and nutrient utilisation of weaner lambs on restricted or high concentrate allowance using 60 weaner lambs of initial average live weight of 13.90 kg BW in a randomized design. The experimental treatments were 15 or 25 g kg⁻¹ BW or ad libitum concentrate allowance. Roughage source which contained Khejri (Prosopis cineratia) and Siris (Albizia lebback) leaves in 50:50 ratio was offered ad libitum to all the animals. Lambs supplemented with 15 g or ad libitum concentrate had similar dry matter intake (4.2 kg/100 kg BW) but significantly (p < 0.01) lower than 25 g concentrate supplemented group (4.9 kg/100 kg BW). Organic matter and CP intakes increased with increasing concentrate supplementation. Apparent digestibilities of dry matter, organic matter, CP, NDF, ADF and cellulose were significantly (p < 0.01) higher in ad libitum concentrate supplemented than 15 and 25 g concentrate supplemented lambs. Daily ME intake was significantly (p < 0.05) higher in 25 g and ad libitum concentrate supplemented lambs while ME intake kg⁻¹ gain was lower in ad libitum concentrate supplemented lambs (57 MJ kg⁻¹ gain) than those supplemented with 15 or 25 g concentrate (91 MJ kg⁻¹ gain). Generally, average daily gain increased with increasing levels of concentrate supplementation. Ad libitum concentrate supplemented lambs had significantly (p < 0.01) higher daily gains (151 g) than 15 and 25 g concentrate supplemented lambs (77 and 98 g, respectively). Feed efficiency was similar for 15 and 25 g concentrate supplemented lambs but significantly (p < 0.01) lower than the ad libitum concentrate supplemented lambs. All animals were in positive N-balance and the N-balance increased with increasing concentrate supplementation. Mean rumen fluid pH was significantly (6.6, p < 0.01) lower in ad libitum concentrate supplemented lambs compared to 15 or 25 g concentrate fed lambs (6.9). Rumen NH₃-N and total-N-concentrations peaked at 3 h post-feeding. Optimum rumen fluid pH, better nutrient digestibilities, higher N-retention improved growth by 49% of ad libitum concentrate fed lambs.     

Folate deprivation induces cell cycle arrest at G0/G1 phase and apoptosis in hippocampal neuron cells through down-regulation of IGF-1 signaling pathway

Folate deficiency contributes to impaired adult hippocampal neurogenesis, yet the mechanisms remain unclear. Here we use HT-22 hippocampal neuron cells as model to investigate the effect of folate deprivation (FD) on cell proliferation and apoptosis, and to elucidate the underlying mechanism. FD caused cell cycle arrest at G0/G1 phase and increased the rate of apoptosis, which was associated with disrupted expression of folate transport and methyl transfer genes. FOLR1 and SLC46A1 were (P < 0.01) down-regulated, while SLC19A1 was up-regulated (P < 0.01) in FD group. FD cells exhibited significantly (P < 0.05) higher protein content of BHMT, MAT2b and DNMT3a, as well as increased SAM/SAH concentrations and global DNA hypermethylation. The expression of the total and all the 3 classes of IGF-1 mRNA variants was significantly (P < 0.01) down-regulated and IGF-1 concentration was decreased (P < 0.05) in the culture media. IGF-1 signaling pathway was also compromised with diminished activation (P < 0.05) of STAT3, AKT and mTOR. CpG hypermethylation was detected in the promoter regions of IGF-1 and FOLR1 genes, while higher SLC19A1 mRNA corresponded to hypomethylation of its promoter. IGF-1 supplementation in FD media significantly abolished FD-induced decrease in cell viability. However, IGF-1 had limited effect in rescuing the cell phenotype when added 24 h after FD. Taken together, down-regulation of IGF-1 expression and signaling is involved in FD-induced cell cycle arrest and apoptosis in HT-22 hippocampal neuron cells, which is associated with an abnormal activation of methyl transfer pathway and hypermethylation of IGF-1 gene promoter.     

Unbiased sex-specific survival in Alpine chamois

Many polygynous ungulates show higher mortality of males than of females, because of the intense male–male competition during the rut and the costs associated with the development of sexual-size dimorphism. In the weakly dimorphic Alpine chamois Rupicapra rupicapra the occurrence of differential sex-specific survival strategies is controversial. To date, only two studies investigated the survivorship of males and females in this species, producing conflicting results: these works, based on the use of life tables, require confirmation from researches carried out on living populations. We assessed the survival pattern of a protected Alpine chamois population in the Swiss National Park, where 116 individuals were marked and monitored over 13 years (1996–2008). We tested for sex-, age- and year-dependence of survival by means of capture-mark-resight models. Resighting probabilities were sex-dependent, and survival rates were time-dependent. Females had higher resighting probabilities (0.84) than males (0.74). All over the time periods, sex had a weak influence on survival probability (males = 0.91; females = 0.92) and survival rates remained surprisingly high until late age (1 year = 0.90; 2–7 years = 0.91; 8+ years = 0.92). The growing evidence for a high adult survival and a weak differential mortality of the two sexes, together with the highly seasonal sexual-size dimorphism observed for Alpine chamois, might indicate the occurrence of a unique conservative survival strategy in both sexes and a low-risk mating strategy by males.     

Prolactin administration during early postnatal life decreases hippocampal and olfactory bulb neurogenesis and results in depressive-like behavior in adulthood

Tight regulation of hormone and neurochemical milieu during developmental periods is critical for adequate physiological functions. For instance, activation of peptide systems during early life stress induces morphological changes in the brain resulting in depression and anxiety disorders. Prolactin (PRL) exerts different actions within the brain; it regulates neurogenesis and modulates neuroendocrine functions in the adult. However, PRL effects during early postnatal life are hardly known. Therefore, we examined whether neonatal administration of PRL influences cell survival in the hippocampal dentate gyrus (DG) and in the olfactory bulb (OB) and whether such influence results in behavioral consequences in adulthood. PRL-treated rat pups (13 mg/kg; PND1 to PND14), injected with BrdU at postnatal day 5 (PND5), showed a decrease in the density of DG BrdU/DCX and BrdU/NeuN-positive cells that survive at PND15. Similarly, PRL treatment decreased the density of BrdU + cells in the OB compared with VEH. Fluorojade B analysis showed no significant changes in the amount of cell death in the DG between the groups. Postnatal PRL administration induced a passive coping strategy in the forced swimming test in male and female adult rats when compared with control and vehicle groups. Corticosterone endogenous levels at PND12 were not affected by PRL or VEH treatment. Altogether, these results suggest that opposed to its effects in the adult, postnatal PRL treatment affects neurogenesis and results in psychopathology later in life. High PRL levels, as observed in neonates under several pathological states, might contribute to detrimental effects on the developing brain.     

Thyroxine administration prevents matrilineal intergenerational consequences of in utero ethanol exposure in rats

The neurodevelopmental fetal alcohol spectrum disorder (FASD) is characterized by cognitive and behavioral deficits in the offspring. Conferring the deficits to the next generation would increase overall FASD disease burden and prevention of this transmission could be highly significant. Prior studies showed the reversal of these behavioral deficits by low dose thyroxine (T4) supplementation to the ethanol-consuming mothers. Here we aim to identify whether prenatal ethanol (PE) exposure impairs hippocampus-dependent learning and memory in the second-generation (F2) progeny, and whether T4 administration to the ethanol-consuming dam can prevent it. Sprague-Dawley (S) dams received control diets (ad libitum and nutritional control) or ethanol containing liquid diet with and without simultaneous T4 (0.3 mg/L diet) administration. Their offspring (SS F1) were mated with naive Brown Norway (B) males and females generating the SB F2 and BS F2 progeny. Hippocampus-dependent contextual fear memory and hippocampal expression of the thyroid hormone-regulated type 3 deiodinase, (Dio3) and neurogranin (Nrgn) were assessed. SS F1 PE-exposed females and their SB F2 progeny exhibited fear memory deficits. T4 administration to the mothers of F1 females reversed these deficits. Although SS F1 PE-exposed males also experienced fear memory deficit, this was neither transmitted to their BS F2 offspring nor reversed by prenatal T4 treatment. Hippocampal Dio3 and Nrgn expression showed similar pattern of changes. Grandmaternal ethanol consumption during pregnancy affects fear memory of the matrilineal second-generation progeny. Low dose T4 supplementation prevents this process likely via altering allele-specific and total expression of Dio3 in the hippocampus.     

Responses of the estuarine copepod Pseudodiaptomus annandalei to diatom polyunsaturated aldehydes: Reproduction,survival and postembryonic development

The euryhaline calanoid copepod Pseudodiaptomus annandalei perennially occurs in tropical and subtropical brackish water ecosystems and harbors supporting harmful algal blooms. In the present paper we provide a quantitative assessment of the influence of the diatom-derived poly-unsaturated aldehyde (PUA), 2-trans-4-trans-decadienal on demographic traits of P. annandalei. The survival and reproduction of P. annandalei were recorded in life table experiments, using a cohort of adult males and females exposed to a range of concentrations (0.75, 1.5, 3 and 4.5 μM) of decadienal. Higher mortality of female cohorts and lower reproduction were recorded with increasing concentrations of decadienal (3 and 4.5 μM). The estimated survival time for cohort females (control: 9.7 days; 4.5 μM decadienal: 4.7 days) and developmental stages of copepods (control: 10.5 days; 4.5 μM decadienal: 1.0 days) in decadienal applied medium (Isochrysis galbana + decadienal) was significantly lower than those in control (only I. galbana). Detrimental effects further eroded recruitment by increasing naupliar mortality and impairing copepodite development to adulthood. Since P. annandalei is widely used in the aquaculture industry in Asia, the present results call for a limited use of PUA producing diatoms as algal food to avoid impairing copepod reproduction and development.     

Socioeconomic status,human papillomavirus,and overall survival in head and neck squamous cell carcinomas in Toronto,Canada

BackgroundDespite universal healthcare in some countries, lower socioeconomic status (SES) has been associated with worse cancer survival. The influence of SES on head and neck cancer (HNC) survival is of immense interest, since SES is associated with the risk and prognostic factors associated with this disease.Patients and methodsNewly diagnosed HNC patients from 2003 to 2010 (n = 2124) were identified at Toronto’s Princess Margaret Cancer Centre. Principal component analysis was used to calculate a composite score using neighbourhood-level SES variables obtained from the 2006 Canada Census. Associations of SES with overall survival were evaluated in HNC subsets and by p16 status (surrogate for human papillomavirus).ResultsSES score was higher for oral cavity (n = 423) and p16-positive oropharyngeal cancer (OPC, n = 404) patients compared with other disease sites. Lower SES was associated with worse survival [HR 1.14 (1.06–1.22), p = 0.0002], larger tumor staging (p < 0.001), current smoking (p < 0.0001), heavier alcohol consumption (p < 0.0001), and greater comorbidity (p < 0.0002), but not with treatment regimen (p > 0.20). After adjusting for age, sex, and stage, the lowest SES quintile was associated with the worst survival only for OPC patients [HR 1.66 (1.09–2.53), n = 832], primarily in the p16-negative subset [HR 1.63 (0.96–2.79)]. The predictive ability of the prognostic models improved when smoking/alcohol was added to the model (c-index 0.71 vs. 0.69), but addition of SES did not (c-index 0.69).ConclusionSES was associated with survival, but this effect was lost after accounting for other factors (age, sex, TNM stage, smoking/alcohol). Lower SES was associated with greater smoking, alcohol consumption, comorbidity, and stage.     

Aneuploidy assessed by DNA index influences the effect of iron status on plasma and/or supernatant cytokine levels and progression of cells through the cell cycle in a mouse model

Aneuploidy, a condition associated with altered chromosome number, hence DNA index, is frequently seen in many diseases including cancers and affects immunity. Iron, an essential nutrient for humans, modulates the immune function and the proliferation of normal and cancer cells. To determine whether impaired immunity seen in iron-deficient subjects may be related to aneuploidy, we measured spleen cell DNA index, percent of cells in different phases of the cell cycle, plasma and/or supernatant IL-2, IL-10, IL-12, and interferon-gamma in control, pair-fed, iron-deficient, and iron-replete mice (N = 20–22/group). The test and control diets differed only in iron content (0.09 mmol/kg versus 0.9 mmol/kg) and were fed for 68 days. Mean levels of hemoglobin and liver iron stores of iron-deficient and iron-replete mice were 40–60% lower than those of control and pair-fed mice (P < 0.05). Mean plasma levels of IL-10, interferon-gamma and percent of cells in S + G2/M phases were lower in mice with than in those without aneuploidy (P < 0.05). Lowest plasma IL-12 and interferon-gamma concentrations were observed in iron-deficient mice with aneuploidy. Mean percents of cultures with aneuploidy and DNA indexes were higher in iron-deficient and iron-replete than in control and pair-fed mice likely due to delayed cell division (P < 0.05). Aneuploidy decreased the concentration of IL-2 and interferon-gamma in baseline cultures while it increased that of interferon-gamma in anti-CD3 treated cultures. Aneuploidic indexes negatively correlated with cytokine levels, percents of cells in S + G2/M phases and indicators of iron status (P < 0.05). Although chromosome cytogenetics was not performed, for the first time, we report that increased aneuploidy rate may modulate the immune function during iron-deficiency.     

Stage- and sex-specific heat tolerance in the yellow dung fly Scathophaga stercoraria

Thermal tolerance varies at all hierarchical levels of biological organization: among species, populations, individuals, and even within individuals. Age- or developmental stage- and sex-specific thermal effects have received relatively little attention in the literature, despite being crucial for understanding thermal adaptation in nature and responses to global warming. We document stage- and sex- specific heat tolerance in the yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae), a species common throughout the northern hemisphere that generally favours cool climates. Exposure of eggs to temperatures up to 32 °C did not affect larval hatching rate, but subsequent egg-to-adult survival at a benign temperature was reduced. Permanent transfer from benign (18 °C) to hot temperatures (up to 31 °C) at different larval and pupal stages strongly decreased egg-to-adult survival, though survival continuously improved the later the transfer occurred. Temporary transfer for only two days increased mortality more weakly, survival being lowest when temperature stress was imposed early during the larval or pupal stages. Adult flies provided with sugar and water tolerated 31 °C longer than previously thought (5 days in males to 9 days in females). Eggs were thus less susceptible to thermal stress than larvae, pupae or adults, in agreement with the hypothesis that more mobile stages require less physiological protection against heat because they can behaviourally thermoregulate. The probability of mating, of laying a clutch, and hatching success were generally independently reduced by exposure of females or males to warm temperatures (24 °C) during the juvenile or adult stages, with some interactions evident. High temperature stress thus affects survival differentially depending on when it occurs during the juvenile or the pre-reproductive adult life stage, and affects reproductive success via the mating behaviour of both sexes, female physiology in terms of oviposition, and fertility via sperm and/or egg quality. Our results illustrate that temperature stress, even when moderate and temporary, during early development can have profound lethal and non-lethal fitness-consequences later in life.     

Biology and thermal requirements of Chrysoperla genanigra (Neuroptera: Chrysopidae) reared on Sitotroga cerealella (Lepidoptera: Gelechiidae) eggs

Chrysoperla genanigra Freitas is a common green lacewing associated with melon pests in the Northeastern Brazil. All life stages of this recently described species were studied under a range of constant temperature conditions (17, 21, 25, 29, 33, 35 and 37 °C), a photoperiod of 12 h:12 h (L:D) and 70 ± 10% relative humidity. Adults of C. genanigra were fed on a diet consisting of a 1:1 (v/v) mixture of brewer’s yeast and honey, while larvae were provided with eggs of Sitotroga cerealella (Olivier) ad libitum. The duration of preimaginal development of the species was inversely proportional to temperature and ranged from approximately 63 days at 17 °C to 15 days at 35 °C. The percentage of adult emergence varied from 6.7% at 17 °C to 76.7% at 25 °C, although no larvae were able to complete development at 37 °C. The lower thermal threshold for total preimaginal development was approximately 10.8 °C and the thermal requirement was 336.7 degree-days. Egg production, along with the longevity of both males and females, were significantly affected by temperature. It is concluded that the best temperature for rearing C. genanigra is 25 °C, with the lowest preimaginal mortality and the highest egg production (992.7 eggs/female).     

Genetic variation in fertility of heat-stressed male mice

The damaging effects of heat stress on male fertility are evident in developing spermatozoa expressed in ejaculates 18–28 days post-stress in mice. Our objectives were to: (1) assess genetic variation in fertility of heat-stressed male mice and (2) determine response to selection for fertility after heat stress in male mice. Mature male mice were exposed to heat stress (35 ± 1 °C; n = 50) or control (21 ± 1 °C; n = 10) conditions for 24 h (day 0) and then hemicastrated for tissue collection. Two periods of mating tests followed, period 1 (from days 3 to 11) when no reductions in fertility were anticipated, and period 2 (days 18–26) when variation in fertility was expected. Period 2 pregnant females were sacrificed in late gestation. Males were indexed by multiplying overall mean ovulation rate by pre-implantation survival and number of pregnant period 2 mates. The five highest and five lowest ranking males were identified as heat stress resistant and susceptible, respectively. Resistant males were 61.2 units superior in the index, 57.5% greater in pregnancy rate, and 57.6 total fetuses greater than susceptible males. Progeny of resistant sires were superior to progeny of susceptible sires in estimated breeding value by 4.5 units for the index, 4.1% for pregnancy rate, and 5.2 fetuses (P < 0.0001). Heritability estimates for the index, pregnancy rate, and number of fetuses ranged from 0.09 to 0.13, suggesting male fertility following heat stress is heritable and responds to selection.     

Cell proliferation and survival in the mating circuit of adult male hamsters: Effects of testosterone and sexual behavior

The transient actions of gonadal steroids on the adult brain facilitate social behaviors, including reproduction. In male rodents, testosterone acts in the posterior medial amygdala (MeP) and medial preoptic area (MPOA) to promote mating. Adult neurogenesis occurs in both regions. The current study determined if testosterone and/or sexual behavior promote cell proliferation and survival in MeP and MPOA. Two experiments were conducted using the thymidine analog BrdU. First, gonad-intact and castrated male hamsters (n = 6/group) were compared 24 h or 7 weeks after BrdU. In MeP, testosterone-stimulated cell proliferation 24 h after BrdU (intact: 22.8 ± 3.9 cells/mm², castrate: 13.2 ± 1.4 cells/mm²). Testosterone did not promote cell proliferation in MPOA. Seven weeks after BrdU, cell survival was sparse in both regions (MeP: 2.5 ± 0.6 and MPOA: 1.7 ± 0.2 cells/mm²), and was not enhanced by testosterone. In Experiment 2, gonad-intact sexually-experienced animals were mated weekly to determine if regular neural activation enhances cell survival 7 weeks after BrdU in MeP and MPOA. Weekly mating failed to increase cell survival in MeP (8.1 ± 1.6 vs. 9.9 ± 3.2 cells/mm²) or MPOA (3.9 ± 0.7 vs. 3.4 ± 0.3 cells/mm²). Furthermore, mating at the time of BrdU injection did not stimulate cell proliferation in MeP (8.9 ± 1.7 vs. 8.1 ± 1.6 cells/mm²) or MPOA (3.6 ± 0.5 vs. 3.9 ± 0.7 cells/mm²). Taken together, our results demonstrate a limited capacity for neurogenesis in the mating circuitry. Specifically, cell proliferation in MeP and MPOA are differentially influenced by testosterone, and the birth and survival of new cells in either region are not enhanced by reproductive activity.     

Prenatal Stress Inhibits Hippocampal Neurogenesis but Spares Olfactory Bulb Neurogenesis

The dentate gyrus (DG) and the olfactory bulb (OB) are two regions of the adult brain in which new neurons are integrated daily in the existing networks. It is clearly established that these newborn neurons are implicated in specific functions sustained by these regions and that different factors can influence neurogenesis in both structures. Among these, life events, particularly occurring during early life, were shown to profoundly affect adult hippocampal neurogenesis and its associated functions like spatial learning, but data regarding their impact on adult bulbar neurogenesis are lacking. We hypothesized that prenatal stress could interfere with the development of the olfactory system, which takes place during the prenatal period, leading to alterations in adult bulbar neurogenesis and in olfactory capacities. To test this hypothesis we exposed pregnant C57Bl/6J mice to gestational restraint stress and evaluated behavioral and anatomic consequences in adult male offspring.We report that prenatal stress has no impact on adult bulbar neurogenesis, and does not alter olfactory functions in adult male mice. However, it decreases cell proliferation and neurogenesis in the DG of the hippocampus, thus confirming previous reports on rats. Altogether our data support a selective and cross-species long-term impact of prenatal stress on neurogenesis.     

Temperature-dependent development of overwintering Sericinus montela Gray (Lepidoptera: Papilionidae) pupae and its validation

The developmental time and survival of overwintering Sericinus montela Gray pupae were studied at four constant temperatures (15.0, 20.0, 25.0, and 30.0 °C), 40 ± 10% relative humidity, and 10:14 h light:dark cycle. The developmental time of both sexes decreased with increasing temperature between 15.0 °C (70.18 days for females and 55.28 days for males) and 30.0 °C (19.60 days for females and 13.78 days for males). The development periods of females were longer than those of males at each constant temperature. The relationship between the developmental rate and temperature was fitted by a linear model and a nonlinear developmental rate model (Lactin 1). The mortality of overwintered S. montela pupae was lowest at 25.0 °C (16.7%) and highest at 15.0 °C (36.7%). The lower developmental thresholds were 12.38 and 12.16 °C for females and males, respectively. The distribution of development completion for females and males was described by the two-parameter Weibull distribution equation (r² = 0.87 for females and r² = 0.94 for males). The date for the cumulative 50% adult emergence was within one or two days of that predicted using the Lactin 1 model. The temperature-dependent developmental model for S. montela could be applied to predict the timing of spring emergence in different geographical locations and will be helpful in developing a full-cycle phenology model for S. montela.