Desert crossing strategies of migrant songbirds vary between and within species.

Each year, billions of songbirds cross large ecological barriers during their migration. Understanding how they perform this incredible task is crucial to predict how global change may threaten the safety of such journeys. Earlier studies based on radar suggested that most songbirds cross deserts in intermittent flights at high altitude, stopping in the desert during the day, while recent tracking with light loggers suggested diurnal prolongation of nocturnal flights and common non-stop flights for some species. We analyzed light intensity and temperature data obtained from geolocation loggers deployed on 130 individuals of ten migratory songbird species, and show that a large variety of strategies for crossing deserts exists between, but also sometimes within species. Diurnal stopover in the desert is a common strategy in autumn, while most species prolonged some nocturnal flights into the day. Non-stop flights over the desert occurred more frequently in spring than in autumn, and more frequently in foliage gleaners. Temperature recordings suggest that songbirds crossed deserts with flight bouts performed at various altitudes according to species and season, along a gradient ranging from low above ground in autumn to probably >2000 m above ground level, and possibly at higher altitude in spring. High-altitude flights are therefore not the general rule for crossing deserts in migrant songbirds. We conclude that a diversity of migration strategies exists for desert crossing among songbirds, with variations between but also within species.

Unravelling migration connectivity reveals unsustainable hunting of the declining ortolan bunting.

In France, illegal hunting of the endangered ortolan bunting Emberiza hortulana has been defended for the sake of tradition and gastronomy. Hunters argued that ortolan buntings trapped in southwest France originate from large and stable populations across the whole of Europe. Yet, the European Commission referred France to the Court of Justice of the European Union (EU) in December 2016 for infringements to legislation (IP/16/4213). To better assess the impact of hunting in France, we combined Pan-European data from archival light loggers, stable isotopes, and genetics to determine the migration strategy of the species across continents. Ortolan buntings migrating through France come from northern and western populations, which are small, fragmented and declining. Population viability modeling further revealed that harvesting in southwest France is far from sustainable and increases extinction risk. These results provide the sufficient scientific evidence for justifying the ban on ortolan harvesting in France.

Effects of dietary phytoestrogens on plasma testosterone and triiodothyronine (T3) levels in male goat kids.

BACKGROUND: Exposure to xenoestrogens in humans and animals has gained increasing attention due to the effects of these compounds on reproduction. The present study was undertaken to investigate the influence of low-dose dietary phytoestrogen exposure, i.e. a mixture of genistein, daidzein, biochanin A and formononetin, on the establishment of testosterone production during puberty in male goat kids. METHODS: Goat kids at the age of 3 months received either a standard diet or a diet supplemented with phytoestrogens (3-4 mg/kg/day) for approximately 3 months. Plasma testosterone and total and free triiodothyronine (T3) concentrations were determined weekly. Testicular levels of testosterone and cAMP were measured at the end of the experiment. Repeated measurement analysis of variance using the MIXED procedure on the generated averages, according to the Statistical Analysis System program package (Release 6.12, 1996, SAS Institute Inc., Cary, NC, USA) was carried out. RESULTS: No significant difference in plasma testosterone concentration between the groups was detected during the first 7 weeks. However, at the age of 5 months (i.e. October 1, week 8) phytoestrogen-treated animals showed significantly higher testosterone concentrations than control animals (37.5 nmol/l vs 19.1 nmol/l). This elevation was preceded by a rise in plasma total T3 that occurred on September 17 (week 6). A slightly higher concentration of free T3 was detected in the phytoestrogen group at the same time point, but it was not until October 8 and 15 (week 9 and 10) that a significant difference was found between the groups. At the termination of the experiment, testicular cAMP levels were significantly lower in goats fed a phytoestrogen-supplemented diet. Phytoestrogen-fed animals also had lower plasma and testicular testosterone concentrations, but these differences were not statistically significant. CONCLUSION: Our findings suggest that phytoestrogens can stimulate testosterone synthesis during puberty in male goats by increasing the secretion of T3; a hormone known to stimulate Leydig cell steroidogenesis. It is possible that feedback signalling underlies the tendency towards decreased steroid production at the end of the experiment.

Bone tissue content of TGF-beta2 changes with time in human heterotopic ossification after total hip arthroplasty.

Transforming growth factor beta isoforms (TGF-beta(1), TGF-beta(2), and TGF-beta(3)) most likely play a role in bone physiology, but little is known about their relative importance in normal as well as in heterotopic bone. This study focused on possible differences in the localization and relative content of different TGF beta isoforms in heterotopic ossifications (HO) by comparing HOs, which have developed less than 17 months (immature HOs) with those developed 3-9 years (mature HOs). The HOs were harvested after total hip arthroplasty (THA) during revision surgery. The HO samples were decalcified, embedded in paraffin and sectioned. Azan staining was used to evaluate histological structure of the ossifications and immunohistochemical analysis was performed to estimate the localization of three TGF beta isoforms in the HOs. Comparison of different TGF beta isoforms in the immature and the mature ossifications showed that the content of TGF-beta(2) was decreased by almost three times in the mature HO as compared to the immature HO (p = 0.0064). The proportions of other isoforms in HOs did not differ significantly. This study shows that the relative importance of TGF betas change with HO development.

Mono-(2-ethylhexyl) phthalate stimulates basal steroidogenesis by a cAMP-independent mechanism in mouse gonadal cells of both sexes.

Phthalates are widely used as plasticizers in a number of daily-life products. In this study, we investigated the influence of mono-(2-ethylhexyl) phthalate (MEHP), the active metabolite of the frequently used plasticizer di-(2-ethylhexyl) phthalate (DEHP), on gonadal steroidogenesis in vitro. MEHP (25-100 microM) stimulated basal steroid synthesis in a concentration-dependent manner in immortalized mouse Leydig tumor cells (MLTC-1). The stimulatory effect was also detected in KK-1 granulosa tumor cells. MEHP exposure did not influence cAMP or StAR protein levels and induced a gene expression profile of key steroidogenic proteins different from the one induced by human chorionic gonadotropin (hCG). Simultaneous treatment with MEHP and a p450scc inhibitor (aminoglutethimide) indicated that MEHP exerts its main stimulatory effect prior to pregnenolone formation. MEHP (10-100 microM) up-regulated hormone-sensitive lipase and 3-hydroxy-3-methylglutaryl coenzyme A reductase, suggesting that MEHP increases the amount of cholesterol available for steroidogenesis. Our data suggest that MEHP, besides its known inhibitory effect on hCG action, can directly stimulate gonadal steroidogenesis in both sexes through a cAMP- and StAR-independent mechanism. The anti-steroidogenic effect of DEHP has been proposed to cause developmental disorders such as hypospadias and cryptorchidism, whereas a stimulation of steroid synthesis may prematurely initiate the onset of puberty and theoretically affect the hypothalamic-pituitary-gonadal axis.

Phosphorylation and inactivation of glycogen synthase kinase-3 by soluble kit ligand in mouse oocytes during early follicular development.

Communication between mammalian oocytes and their surrounding granulosa cells through the Kit-Kit ligand (KL, or stem cell factor, SCF) system has been shown to be crucial for follicular development. Our previous studies (Reddy et al. 2005, Liu et al. 2006) have indicated that the intra-oocyte KL-Kit-PI3 kinase (PI3K)-Akt-Foxo3a cascade may play an important role in follicular activation and early development. In the present study, using in situ hybridization and in vitro culture of growing oocytes from 8-day-old postnatal mice, we have demonstrated that another Akt substrate, glycogen synthase kinase-3 (GSK-3), is expressed in growing oocytes. Also, treatment of cultured mouse oocytes with soluble KL not only leads to increased Akt kinase activity in the oocytes, which can phosphorylate recombinant GSK-3 in vitro, but also leads to phosphorylation of oocyte GSK-3alpha and GSK-3beta, which can result in the inactivation of GSK-3 function in oocytes. In addition, we have shown that the regulation of GSK-3alpha and GSK-3beta in cultured oocytes by soluble KL is accomplished through PI3K, since the PI3K-specific inhibitor LY294002 completely abolished the KL-induced phosphorylation of GSK-3alpha and GSK-3beta. Moreover, blockage of the Kit signaling pathway by a Kit function-blocking antibody, ACK2, resulted in reduced phosphorylation of GSK-3. Taken together, our data suggest that the cascade from granulosa cell-derived KL to Kit-PI3K-Akt-GSK-3 in oocytes may take part in regulation of oocyte growth and early ovarian follicular development.

Infertility caused by retardation of follicular development in mice with oocyte-specific expression of Foxo3a.

In recent years, mammalian oocytes have been proposed to have important roles in the orchestration of ovarian follicular development and fertility. To determine whether intra-oocyte Foxo3a, a component of the phosphatidylinositol 3-kinase (PI3K) signaling pathway, influences follicular development and female fertility, a transgenic mouse model was generated with constitutively active Foxo3a expressed in oocytes. We found that the female transgenic mice were infertile, which was caused by retarded oocyte growth and follicular development, and anovulation. Further mechanistic studies revealed that the constitutively active Foxo3a in oocytes caused a dramatic reduction in the expression of bone morphogenic protein 15 (Bmp15), connexin 37 and connexin 43, which are important molecules for the establishment of paracrine and gap junction communications in follicles. Foxo3a was also found to facilitate the nuclear localization of p27(kip1) in oocytes, a cyclin-dependent kinase (Cdk) inhibitor that may serve to inhibit oocyte growth. The results from the current study indicate that Foxo3a is an important intra-oocyte signaling molecule that negatively regulates oocyte growth and follicular development. Our study may therefore give some insight into oocyte-borne genetic aberrations that cause defects in follicular development and anovulation in human diseases, such as premature ovarian failure.

Differential effects of cadmium on the gene expression of seven-transmembrane-spanning receptors and GAPDH in the rat testis.

Cadmium (Cd) is a widely spread toxicant with endocrine disrupting properties. Under experimental conditions it suppresses sex steroid synthesis in the male as well as the female. Testicular steroidogenesis is primarily regulated by gonadotropins, but is also influenced by catecholamines. We have previously shown that Cd exposure affects rat testosterone synthesis by down-regulating luteinizing hormone (LH) receptor mRNA expression. In this study, rats were given 10 micromol/kg Cd subcutaneously and sacrificed 0.48-144 h later. We investigated the effects of Cd on testicular gene expression of two adrenergic receptors. In addition, mRNA levels of the androgen-regulated house keeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were measured. In contrast to the suppressive influence on LH receptor expression Cd lacked effect on the expression of alpha(1A)- and beta(2)-adrenergic receptors. GAPDH gene expression, on the other hand, was up-regulated 1.6-fold after exposure to 10 micromol/kg Cd. These data suggest that the influence of Cd on testicular gene expression involves a specific effect on the LH receptor and not a general effect on seven-transmembrane-spanning receptors. Also, data indicate that the increased expression of GAPDH may be secondary to Cd-induced testosterone deprivation, suggesting future studies of androgen-regulated genes in the toxicity of Cd.

Control of mammalian oocyte growth and early follicular development by the oocyte PI3 kinase pathway: new roles for an old timer.

A large amount of information has accumulated over the past decade on how gonadotropins, steroid hormones and growth factors regulate development of the mammalian ovarian follicle. Moreover, the bi-directional communication between mammalian oocytes and their surrounding somatic (granulosa) cells has also been shown to be crucial for this process. The intra-ovarian factors, or more specifically, the intra-oocyte signaling pathways that control oocyte growth and early follicular development are largely unknown, however. Based on both in vitro studies and in vivo functional studies using gene-modified mouse models, this review focuses on the key features of the phosphatidylinositol 3 kinase (PI3K) pathway in growing mouse oocytes and on the novel functions of the oocyte PI3K pathway in controlling mammalian oocyte growth and follicular development that have come to light only recently. We propose that the PI3K pathway in the oocyte, which is activated by granulosa cell-produced Kit ligand (KL) via the oocyte-surface receptor Kit, may serve as an intra-oocyte network that regulates both oocyte growth and the early development of ovarian follicles.

Experimental sepsis: characteristics of activated macrophages and apoptotic cells in the rat spleen.

Sepsis, being characterized by massive translocation of bacteria into tissues, induces the suppression of the function of both leukocytes and macrophages. The aim of the study was to count activated macrophages (AMs) and apoptotic (Ao) cells in the rat spleen during the period of experimental sepsis and to clarify the associations of these parameters with each other and with leukocyte migration and bacterial translocation into different organs. The Wistar rats were intraperitoneally inoculated with Escherichia coli (E. coli) and were sacrificed after 2, 6, 24, 48, and 120 h. Bacteria and leukocytes in tissues were specifically stained. AMs were identified by immunohistological staining and Ao cells by the TUNEL assay. The high counts of E. coli at 6 h were strongly associated with a low level of the total counts of leukocytes, accompanied by the high translocation of microbes into tissues. In the spleen, lymphocytes, macrophages, and neutrophils with pyknotic nuclei were identified. The count of AMs was highest at 24 h after the inoculation with E. coli; at the same time the Ao cell count began to rise and achieved the highest level 24 h later. Our investigation indicates that the molecular peculiarities of macrophages and their responses to the inflammation process are tissue-specific. In the spleen the activation process involving hematopoietic cells and macrophages was remarkable at the late stage of sepsis, characterized by a high count of Ao cells.

Helicobacter pylori substantially increases oxidative stress in indomethacin-exposed rat gastric mucosa.

Helicobacter pylori (H. pylori) often play an important role in the pathogenesis of gastritis, peptic ulcer, and probably also gastric cancer. Reactive oxygen species (ROS) produced by this bacterium may be one of the crucial factors whereby oxidative stress can play a role in the pathogenesis of ulcer disease. The aim of this study was to assess ROS activity and glutathione redox status, a principal cellular redox sensor, in H. pylori-associated indomethacin-induced gastric ulcers in rats. Gastric lesion was produced by intragastric administration of indomethacin (7 mg/kg) for three days followed by administration of H. pylori suspension (density 10(9) colony forming units). Animals receiving indomethacin only or followed by administration of H. pylori suspension were sacrificed after 11 and 18 days. ROS activity was assessed by the level of lipid peroxidation (LPO) and the glutathione redox status by the ratio between oxidized and reduced glutathione (GSSG/GSH). Indomethacin did not significantly increase the level of LPO and the GSSG/GSH ratio. When H. pylori suspension was given together with indomethacin the LPO was increased both on days 11 and 18 and GSSG/GSH on day 18. H. pylori, thus, substantially increases glutathione redox ratio and lipid peroxidation in gastric mucosa, which may play an important role in the pathological mechanisms of this bacterium. The findings support the idea that dietary antioxidants could be beneficial in combination therapy for eradication of H. pylori.

Electron microscope immunocytochemical localization of cyclooxygenase-1 and -2 in pseudopregnant rat corpus luteum during luteolysis.

Prostaglandins converted from arachidonic acid by cyclooxygenases play an important regulatory role in regression of the corpus luteum. To reveal luteal distribution of cyclooxygenase isoforms during luteolysis, an electron microscope immunocytochemical study was performed. Cyclooxygenase-1 and -2 were found both in luteal steroid-producing and interstitial cells on days 13, 15 and 18 of the adult pseudopregnant rat. Cyclooxygenase-2 immunolabelling was predominantly seen in non-luteal cells. The two enzymes were localized in similar fashion to the plasma membrane, rough and smooth endoplasmic reticulum, lipid bodies and mitochondria, but differently in the nuclear compartment. Cyclooxygenase-1 labelling was found only in the perinuclear region, while cyclooxygenase-2 was localized to the nuclear envelope, region of condensed heterochromatin as well as at the perimeter of the heterochromatin. Nuclear residence may indicate additional roles for cyclooxygenase-2 in regulating gene expression. Identification of both enzymes on lipid bodies suggests that these inclusions may be involved in luteal prostanoid production.

Pronounced induction of testicular PGF(2 alpha) and suppression of testosterone by cadmium-prevention by zinc.

In order to investigate the effects of cadmium (Cd) on testicular prostaglandin F(2 alpha) (PGF(2 alpha)) production, adult male Sprague-Dawley rats were exposed to CdCl(2) by subcutaneous injections. Dose-response as well as temporal-response experiments were performed, and PGF(2 alpha) levels were determined by radioimmunoassay (RIA). The highest cadmium dose (10 micromol/kg) caused a dramatic elevation of testicular PGF(2 alpha), which was established to occur 48 h after exposure. At this point of time, cadmium-treated animals displayed PGF(2 alpha) levels 16.7 times higher than saline-injected controls. No significant differences were found with the lower doses used (1 and 5 micromol/kg). In addition, the influence of pre-treatment with zinc (Zn) was assessed. The very strong stimulatory effect on PGF(2 alpha) synthesis (22.3-fold) detected after exposure to 20 micromol/kg cadmium, was completely absent in the group given zinc (1 mmol/kg) prior to cadmium exposure. Plasma testosterone concentrations were determined in the three experiments, and all groups with strongly elevated PGF(2 alpha) levels showed drastically lowered concentrations of testosterone. Zinc pre-treatment abolished not only the cadmium-induced rise in PGF(2 alpha) but also the testosterone reduction. Additionally, cadmium was found to inhibit the expression of steroidogenic acute regulatory protein (StAR), which is responsible for the rate-limiting step in steroidogenesis. The present findings establish that cadmium can cause a strong induction of testicular PGF(2 alpha) production, which might help to explain the well-known antisteroidogenic effect of this heavy metal. Such an inhibitory effect could be due to reduced levels of StAR.

Alpha B-crystallin in corpora lutea of pseudopregnant rat.

Localization sites and labeling intensity of alphaB-crystallin in corpus luteum (CL) of pseudopregnant rats has been studied using postembedding light and electron microscopical immunohistochemistry. At days 2 and 18 alphaB-crystallin labeling was found to be significantly higher compared with the luteal maintenance period (days 6 and 10). alphaB-crystallin localized both to luteal and interstitial cells of CL. At light microscopical level alphaB-crystallin labeling decreased during CL life span in the central area of luteal cells cytoplasm and increased in the peri-plasmalemmal area. Interstitial cells labeling was found to increase at day 6, followed by almost complete disappearance during functional luteolysis (days 15 and 18). Our results at electron microscopical level showed alphaB-crystallin to localize in cytoplasm with close relationship with endoplasmic reticulum, Golgi apparatus, mitochondria and also in nuclei of luteal and interstitial cells. At day 2 labeling of luteal cells was abundant in cytoplasm but weak in nuclei. During the luteal maintenance period and functional luteolysis labeling in luteal cells was relocalized to the peri-plasmalemmal and perinuclear areas. Labeling in nuclei of luteal cells was weak. At the same time (day 6) interstitial cells including nuclei showed strong labeling, which was significantly decreased during luteolysis. Immunohistochemically detectable tubulin decreased in CL tissue during CL life span allowing to suggest that alphaB-crystallin acts as chaperone, one possible role of which is to stabilize the cytoskeleton in different CL cell types during CL formation and active functioning.

Cadmium-induced decrement of the LH receptor expression and cAMP levels in the testis of rats.

Cadmium (Cd) is a widespread environmental pollutant, characterized by its ability to affect various organs. Adverse effect of Cd on the testis including decreased testosterone production are well-known phenomena, but the cellular events explaining these effects have not yet been established. In the present study the initial steps of gonadotropin mediated testosterone biosynthesis were examined in vivo in rats, in relation to Cd dose and time after injection. In the dose-response experiment Male Sprague-Dawley rats received a single subcutaneous (s.c.) injection of CdCl(2) (1, 5 or 10 micromol/kg body weight) and were sacrificed 48 h after injection. A statistically significant decrease in luteinizing hormone (LH) receptor mRNA level in the testicular tissue was demonstrated at the highest dose (10 micromol/kg). In the temporal-response experiment rats were given 10 micromol/kg of CdCl(2) s.c. and sacrificed 0.48, 4.8, 48 or 144 h after injection. LH receptor mRNA levels as well as cyclic adenosine monophosphate (cAMP) levels were found to be significantly lowered at 48 and 144 h. These observations of the mechanisms whereby Cd exerts its effect on the initial steps of testosterone biosynthesis are the first from in vivo experiments.