Hormonal Induction Research Articles

Clinical management of an ectopic egg in a Timneh African grey parrot (Psittacus erithacus timneh)

A 13-year-old female Timneh African grey parrot (Psittacus erithacus timneh) was evaluated because of the presence of a bald patch of skin caudal to the sternum and increased territorial and nesting behavior of 2 weeks' duration. Whole-body radiography revealed a mineralized egg of normal size and shape. However, no oviposition occurred, and the bird had no signs consistent with dystocia. After 7 days, repeated radiography revealed that the egg had rotated by approximately 180° along its short axis, leading to a diagnosis of ectopic egg retention, which was supported by the results of ultrasonography. Surgical removal of the ectopic egg was performed by means of a ventral midline approach 14 days after administration of leuprolide acetate (800 μg/kg [364 μg/lb], IM). No intracoelomic abnormalities, such as coelomitis or oviductal disease, were diagnosed, and the bird recovered without complications. Physical examination and whole-body radiography at 8 months and a follow-up phone call with the owner at 16 months after surgical treatment revealed no evidence of ectopic egg recurrence or reproductive behavior. Clinical management of ectopic egg retention differs considerably from treatment of intraoviductal egg binding. Therefore, careful evaluation of avian patients with radiographic evidence of egg binding should be performed to avoid possible iatrogenic deterioration of the patient's condition, secondary to inappropriate treatment attempts such as hormonal induction of oviposition or attempts to remove the retained egg via the cloaca. Repeated radiography and ultrasonography and close monitoring of the patient's general condition as well as the lack of clinical signs consistent with dystocia will facilitate the diagnosis of ectopic egg retention.

Thyroid hormone induction of adult stem cell formation during postembryonic development: An essential role of sonic hedgehog signaling mediated cell‐cell interaction

Adult organ‐specific stem cells are essential for organ homeostasis and tissue repair and regeneration, but the underlying mechanism for their development is unclear. Intestinal remodeling during frog metamorphosis offers a unique opportunity to study the formation of such stem cells during vertebrate development. During the transition from an herbivorous tadpole to a carnivorous frog, the intestine is completely remodeled with the larval epithelial cells undergo apoptosis and are replaced by adult epithelial cells developed de novo. The entire metamorphic process is under the control of thyroid hormone. We have shown that adult epithelial stem cells are induced by thyroid hormone through dedifferentiation of some larval epithelial cells. Interestingly, thyroid hormone action in larval epithelial cells alone can induce the formation of putative precursors of the adult stem cells, the formation of the stem cells and their eventual differentiation into the adult epithelium require thyroid hormone action in the nonepithelial tissues as well. This latter action is likely through the connective tissue, leading to the formation of proper stem cell niche. We will further provide evidence that sonic hedgehog signaling, which is induced by thyroid hormone, is one important pathway that mediates the cell‐cell interaction for the formation of the adult intestinal stem cells during this process.

Ovulatory follicle dysfunction in lactating dairy cows after treatment with Folltropin-V at the onset of luteolysis

The objective was to examine growth of the ovulatory follicle after FSH (Folltropin-V; Bioniche Animal Health, Belleville, Ontario, Canada) was given at the onset of induced luteolysis during a synchronization of ovulation protocol. Using GnRH or hCG for inducing ovulation enabled assessing ovulatory follicle responsiveness to an endogenous versus exogenous surge of LH activity. At 8 to 10 days after estrus (synchronized estrus = Day 0), lactating dairy cows received an Eazi-Breed CIDR (Pfizer Animal Health) plus 100 μg GnRH. After 7 days, controlled internal drug release devices (CIDRs) were removed, cows were given 500 μg cloprostenol, and then randomly allocated to receive 80 mg Folltropin-V (FSH; N = 19) or 4 mL sterile saline (SAL; N = 16). After 49 hours, FSH and SAL cows were randomly allocated to receive 100 μg GnRH or 3000 IU hCG. Five cows ovulated 30 to 42 hours (38.4 ± 1.2 hours) after FSH treatment. In the remaining FSH (N = 14) or SAL (N = 16) cows, ovulatory follicle size was similar at CIDR removal (14.5 ± 0.6 and 14.7 ± 0.6 mm, respectively; P = 0.85) and when GnRH/hCG was given (16.6 ± 0.6 and 17.7 ± 0.6 mm, respectively; P = 0.23). Estradiol-17β concentrations were lower in FSH cows at 36 and 49 hours after CIDR removal (FSH by time interaction, P < 0.005). After GnRH or hCG treatment, four FSH cows failed to ovulate. In cows exhibiting ovulation, the last recorded size of the ovulatory follicle was not influenced by FSH (18.1 ± 0.9 and 17.5 ± 0.6 mm for FSH and SAL, respectively; P = 0.59) or hormonal induction approach (18.4 ± 0.9 and 17.2 ± 0.7 mm for GnRH and hCG, respectively; P = 0.29). The interval from onset of luteolysis to ovulation and pharmaceutical induction to ovulation was shorter in FSH cows given GnRH (FSH by pharmaceutical inducer [GnRH vs. hCG] interaction; P = 0.01). Cows receiving GnRH had an LH surge; hCG-treated cows did not. Maximum LH concentrations were greater (P < 0.04) in SAL versus FSH cows after GnRH treatment (10.9 ± 1.2 vs. 6.7 ± 1.4 ng/mL, respectively). In three FSH cows failing to ovulate after GnRH treatment, the maximum LH concentration was <4 ng/mL. When analyzed from GnRH treatment, average time to LH maximum concentration was similar (P = 0.50) to values obtained in cows receiving FSH and GnRH and SAL and GnRH (1.7 ± 0.2 vs. 1.9 ± 0.1 hours, respectively). Interval to maximum hCG concentrations was shorter (P = 0.02) for cows receiving SAL versus FSH (8.0 ± 0.8 and 10.0 ± 0.8 hours for SAL and FSH, respectively). Ovulatory dysfunction of this magnitude highlighted the lack of suitability of Folltropin-V at a dose of 80 mg at the time of induction of luteolysis in fixed timed AI protocols.

Artificial fertilisation of cultured Senegalese sole (Solea senegalensis): Effects of the time of day of hormonal treatment on inducing ovulation

To develop a protocol for the hormonal induction of ovulation and artificial fertilisation in Senegalese sole, it is necessary to determine whether the time of day of the GnRHa injection influences the lapsed time to ovulation or the egg quality. Hormonal treatments were administered at 06:00, 12:00 and 19:00h. The time of ovulation was 42.5±0.6h following hormonal treatment, and there were no significant differences between groups. However, it was noted that the time of ovulation was the most homogeneous in Groups 6 and 12, and most females in these groups ovulated at 41 or 44h following hormonal treatment. Fertilisation rates were lower in fish injected at 19:00h than in those injected at 06:00 or 12:00h, and the largest number of larvae per kg of each female was obtained when the treatment was administered at 06:00. These results suggest that hormonal treatments should be applied in the early morning to promote the maximum number of good quality eggs.

Desempeño reproductivo del bocachico Prochilodus magdalenae inducido dos veces en un mismo año

RESUMENObjetivo. Evaluar el desempeño reproductivo del bocachico (Prochilodus magdalenae) sometido a dos inducciones hormonales con extracto pituitario de carpa (EPC) en un mismo año. Materiales y métodos. 23 hembras, en fase de maduración final, fueron inducidas con 5mg EPC/Kg de peso vivo, en dos aplicaciones, inicialmente 10% y doce horas después 90% restante. A los machos fue aplicado 80% de la dosis total de las hembras. Resultados. Después de la primera inducción hormonal, las hembras estuvieron aptas nuevamente a los 97.6±12.4 días. El índice de ovulación en ambas inducciones fue de 0.91 (21/23). La fecundidad absoluta (g-ovocitos/hembra) no presentó diferencias significativa entre la primera y segunda inducción (36.2 y 44.6 g-ovocitos/hembra, respectivamente) (p&gt;0.05); pero cuando se expresó en número de ovocitos/hembra se observó diferencia significativa (p&lt;0.05), siendo mayor en la primera inducción (53535 ovocitos/hembra) que en la segunda (40658 ovocitos/hembra). La fecundidad relativa, expresada tanto en g-ovocitos/Kg-hembra como ovocitos/Kg-hembra, mostraron diferencia significativa, siendo mayor en la primera inducción (p&lt;0.05). La tasa de fecundación (73.9±19.6%) y eclosión (56.9±17.9%) fueron mayores en la primera inducción, comparadas con la segunda (55.6±21.1% y 35.6±20.7%, respectivamente) (p&lt;0.05). Conclusiones. Después de una inducción hormonal se requiere de aproximadamente tres meses para que una hembra de bocachico alcance nuevamente la maduración final y esté apta para una nueva inducción hormonal. El índice de ovulación no fue afectado por una segunda inducción en un mismo año, pero la fecundidad absoluta y relativa puede disminuirse entre 24 y 66% y las tasas de fecundación y eclosión entre 23 y 36%.

Interactions of the ubiquitous octamer-binding transcription factor-1 with both the signal transducer and activator of transcription 5 and the glucocorticoid receptor mediate prolactin and glucocorticoid-induced β-casein gene expression in mammary epithelial cells

Regulation of milk protein gene expression by lactogenic hormones (prolactin and glucocorticoids) provides an attractive model for studying the mechanisms by which protein and steroid hormones synergistically regulate gene expression. β-Casein is one of the major milk proteins and its expression in mammary epithelial cells is stimulated by lactogenic hormones. The signal transducer and activator of transcription 5 and glucocorticoid receptor are essential downstream mediators of prolactin and glucocorticoid signaling, respectively. Previous studies have shown that mutating the octamer-binding site of the β-casein gene proximal promoter dramatically reduces the hormonal induction of the promoter activity. However, little is known about the underlying molecular mechanisms. In this report, we show that lactogenic hormones rapidly induce the binding of octamer-binding transcription factor-1 to the β-casein promoter and this induction is not mediated by either increasing the expression of octamer-binding transcription factor-1 or inducing its translocation to the nucleus. Rather, lactogenic hormones induce physical interactions between the octamer-binding transcription factor-1, signal transducer and activator of transcription 5, and glucocorticoid receptor to form a ternary complex, and these interactions enhance or stabilize the binding of these transcription factors to the promoter. Abolishing these interactions significantly reduces the hormonal induction of β-casein gene transcription. Thus, our study indicates that octamer-binding transcription factor-1 may serve as a master regulator that facilitates the DNA binding of both signal transducer and activator of transcription 5 and glucocorticoid receptor in hormone-induced β-casein expression, and defines a novel mechanism of regulation of tissue-specific gene expression by the ubiquitous octamer-binding transcription factor-1.

Sex differences in activated corticotropin-releasing factor neurons within stress-related neurocircuitry and hypothalamic–pituitary–adrenocortical axis hormones following restraint in rats

Women may be more vulnerable to certain stress-related psychiatric illnesses than men due to differences in hypothalamic–pituitary–adrenocortical (HPA) axis function. To investigate potential sex differences in forebrain regions associated with HPA axis activation in rats, these experiments utilized acute exposure to a psychological stressor. Male and female rats in various stages of the estrous cycle were exposed to 30min of restraint, producing a robust HPA axis hormonal response in all animals, the magnitude of which was significantly higher in female rats. Although both male and female animals displayed equivalent c-fos expression in many brain regions known to be involved in the detection of threatening stimuli, three regions had significantly higher expression in females: the paraventricular nucleus of the hypothalamus (PVN), the anteroventral division of the bed nucleus of the stria terminalis (BSTav), and the medial preoptic area (MPOA). Dual fluorescence in situ hybridization analysis of neurons containing c-fos and corticotropin-releasing factor (CRF) mRNA in these regions revealed significantly more c-fos and CRF single-labeled neurons, as well as significantly more double-labeled neurons in females. Surprisingly, there was no effect of the estrous cycle on any measure analyzed, and an additional experiment revealed no demonstrable effect of estradiol replacement following ovariectomy on HPA axis hormone induction following stress. Taken together, these data suggest sex differences in HPA axis activation in response to perceived threat may be influenced by specific populations of CRF neurons in key stress-related brain regions, the BSTav, MPOA, and PVN, which may be independent of circulating sex steroids.

Dynamics of ovarian maturation during the reproductive cycle of Metynnis maculatus, a reservoir invasive fish species (Teleostei: Characiformes)

In this study, we evaluated the dynamics of ovarian maturation and the spawning processes during the reproductive cycle of Metynnis maculatus. Adult females (n = 36) were collected bimonthly between April 2010 and March 2011. The mean gonadosomatic index (GSI) was determined, ovarian and blood samples were submitted for morphometric evaluation and the steroid plasma concentration was determined by ELISA. This species demonstrated asynchronous ovarian development with multiple spawns. This study revealed that, although defined as a multiple spawning species, the ovaries of M. maculatus have a pattern of development with a predominance of vitellogenesis between April and August and have an intensification in spawning in September; in October, a drop in the mean GSI values occurred, and the highest frequencies of post-ovulatory follicles (POFs) were observed. We observed a positive correlation between the POF and the levels of 17α-hydroxyprogesterone. Metynnis maculatus has the potential to be used as a source of pituitary tissue for the preparation of crude extracts for hormonal induction; the theoretical period for use is from September to December, but specific studies to determine the feasibility of this approach must be conducted.

Growth stimulation and induction of systemic resistance in tomato against early and late blight by Bacillus subtilis OTPB1 or Trichoderma harzianum OTPB3

The plant growth -promoting rhizobacteria and fungi are known to enhance growth and induce systemic defense responses in plants. The efficacy of Bacillus subtilis OTPB1 and Trichoderma harzianum OTPB3 were evaluated for in vitro antibiosis to Alternaria solani and Phytophthora infestans, growth stimulation, and induction of systemic resistance in tomato seedlings against early and late blight. Cell suspensions of OTPB1 or spore suspensions of OTPB3 were incorporated into plastic pots containing tomato seed var. Arka vikas and data were recorded 30days after inoculation. Both isolates inhibited mycelium growth of A. solani and P. infestans under in vitro conditions and significantly increased root and shoot growth, leaf area and seedling vigour index in tomato. The levels of indole-3-acetic acid (IAA) and gibberellic acid (GA3) were increased significantly in roots of seedlings treated by OTPB1 or OTPB3 by 29.12% and 45.82% or 54.34% and 67.59%, respectively, as compared to uninoculated controls. Treatment with OTPB1 or OTPB3 enhanced the levels of defense–related enzymes including peroxidase, polyphenol oxidase and superoxide dismutase in tomato plants. This study also showed that in addition to plant growth and antibiosis, OTPB1 and OTPB3 enhanced systemic resistance in tomato seedlings through induction of growth hormones and defense enzymes. The use of OTPB1 or OTPB3 in raising disease-free and quality tomato seedlings in pot trays is discussed.

Performance and carcass traits in the diallel crossing of pacu and tambaqui

With the purpose of evaluating the changes and the degree of heterosis on performance and carcass traits of fish from the diallel crossing between Pacu and Tambaqui, four genetic groups were generated through hormonal induction: pacu, tambaqui, tambacu and paqui. For 196 days, 400 juveniles of each genetic group were stocked in a pond divided into four parts of equal size, one for each group. At the end of this period, when the fish weighed on average 1024 g (±115.52 g), 20 specimens of each genetic group were sampled, weighed, measured: head length; standard length; body height; and width; and also processed resulting in following body yield: viscera; carcass; head; fillet; rib; residue and skin yields. There was positive heterosis for body weight, viscera and skin yield and head measures and negative heterosis for carcass and filet yield and body width, indicating that the hybrids have better performance on weight gain, but are inferior in relation to the carcass conformation.

Introduction of modern endocrine techniques for the production of monosex population of fishes

Of the techniques available to mass-produce a sterile or monosex population, the hormonal induction of sex reversal is the most widely practiced. This paper presents the synthesis of works done on sex reversal using 17α methyltestosterone (17αMT), 17β estradiol, non-steroidal aromatase inhibitors (AIs) and oestrogen receptor agonist, tamoxifen in commercially important aquaculture species mossambique tilapia Oreochromis mossambicus, Nile tilapia Oreochromis niloticus, common carp Cyprinus carpio, mahseer Tor putitora and African catfish Clarias gariepinus. Results on sex reversal for producing female T. putitora delineated that treatment to fry of T. putitora 60days post fertilization (60dpf) with 17β estradiol (150mg/kg feed) fetched 69.5% female population. Further, raised temperature (23±1°C) five degrees above ambient temperature brought about 37.5% female populations which was above the control (24.4% females). Feeding tilapia O. mossambicus fry after yolk sac absorption stage (8dpf) with 17αMT incorporated diet (35mg/kg feed) under long photoperiod (16L:8D) for 60days obtained 100% sex reversed males with excellent growth. Treatment with tamoxifen and letrozole (200mg/kg feed) to fingerlings of C. carpio and O. niloticus for 60days brought about 82.5% and 98.5% masculinization with increased level of testosterone (T). Letrozole treatments to C. gariepinus significantly (p<0.001) increased T level to 1197.76±18.79pg/ml when treatment was given through feed for 60days and 1470.5±20.76pg/ml via intraperitoneal injection. There was significant deviation in sex ratio leading to high level of masculinization in different aquaculture species with treatments of hormones and AIs.

Correction: Hormonal Induction of Polo-Like Kinases (Plks) and Impact of Plk2 on Cell Cycle Progression in the Rat Ovary

Correction: Hormonal Induction of Polo-Like Kinases (Plks) and Impact of Plk2 on Cell Cycle Progression in the Rat Ovary

FOXO1 Transcription Factor Inhibits Luteinizing Hormone β Gene Expression in Pituitary Gonadotrope Cells

Synthesis of luteinizing hormone (LH) is tightly controlled by a complex network of hormonal signaling pathways that can be modulated by metabolic cues, such as insulin. One group of candidate genes that may be regulated by insulin signaling in pituitary gonadotrope cells is the FOXO subfamily of forkhead transcription factors. In this study we investigated whether FOXO1 is expressed in gonadotropes and if it can modulate LH β-subunit (Lhb) gene expression. We demonstrated that FOXO1 is expressed in murine gonadotrope cells and that insulin signaling increased FOXO1 phosphorylation and cytoplasmic localization in a PI3K-dependent manner. We also showed that FOXO1 repressed basal transcription and gonadotropin-releasing hormone (GnRH) induction of both the murine and human LHB genes in LβT2 cells, suggesting that FOXO1 regulation of LHB transcription may be conserved between rodents and humans. Although we did not detect FOXO1 binding to the proximal Lhb promoter, the FOXO1 DNA binding domain was necessary for the suppression, suggesting that FOXO1 exerts its effect through protein-protein interactions with transcription factors/cofactors required for Lhb gene expression. FOXO1 repression mapped to the proximal Lhb promoter containing steroidogenic factor 1 (SF1), pituitary homeobox 1 (PTX1), and early growth response protein 1 (EGR1) binding elements. Additionally, FOXO1 blocked induction of the Lhb promoter with overexpressed SF1, PTX1, and EGR1, indicating that FOXO1 repression occurs via these transcription factors but not through regulation of their promoters. In summary, we demonstrate that FOXO1 phosphorylation and cellular localization is regulated by insulin signaling in gonadotropes and that FOXO1 inhibits Lhb transcription. Our study also suggests that FOXO1 may play an important role in controlling LH levels in response to metabolic cues.

Ovulation rates and twinning birth following Follicle Stimulating Hormone (FSH) treatment at differents stages of estrus cycle

Twinning rate could be increased through genetically approach or through hormonal induction approach. The aim of this study was to observe the effect of first injection of FSH initiated on the ovulation rate. The experiment design was completely randomized with 3 different time of FSH was initiated as treatment using 12 lactating dairy cattle. Injection of FSH was initiated at day 2 (Treatment I), day 10 (Treatment II) and at day 18 (Treatment III) of estrus cycle. A total of 6 ml Folltropin (Equivalent 120 mg FSH) was intramussculary injected in decreasing dossis method twice a day with 12 hours interval for 4 days. Blood was collected on day 12 of estrus cycle for progesterone level. Data recorded were the diameter of ovary (DO), total corpus luteum (TCL), concentration of progesterone (P), percentage of pregnancy and number of birth. The means DO, TCL and P were significantly (P < 0.05) higher after injection (2.0 cm; 2.1 and 1.6 ng/ml) than those before injection (1.4 cm, 1.0 dan 0.6 ng/ml). The time of first injection of FSH was initiated, significantly affect the ovulation rate. The mean DO, TCL and P were significantly higher (P < 0.01) in treatment II (2.6 cm; 4.0 and 2.9 ng/ml) than those in treatments I (1.9 cm; 1.3 and 0.9 ng/ml) or in treatment III (1.6 cm; 1.3 and 0.9 ng/ml). There was no significant diference between treatment I and III. The percentage of pregnant were 25.0; 75.0 and 25.0 for treatments I; II and III respectively. One twin birth and 1 single birth were obtained in treatments II but only one single birth for each treatment I and III. Number of CL were positively correlated with the concentration of progesterone but were not fully useful for prediction number of birth. In conclusion, the dairy cattle gave a better response to exogenous gonadotropin hormone when the first injection was initiated at day 10 of estrus cycle. Key Words : Hormone, FSH, Estrus Cycle, Ovulation, Twin Birth

Correction: Hormonal Induction of Polo-Like Kinases (Plks) and Impact of Plk2 on Cell Cycle Progression in the Rat Ovary

Correction: Hormonal Induction of Polo-Like Kinases (Plks) and Impact of Plk2 on Cell Cycle Progression in the Rat Ovary

Androgen Initiates Sertoli Cell Tight Junction Formation in the Hypogonadal (hpg) Mouse1

Sertoli cell tight junctions (TJs) form at puberty as a major component of the blood-testis barrier (BTB), which is essential for spermatogenesis. This study characterized the hormonal induction of functional Sertoli cell TJ formation in vivo using the gonadotropin-deficient hypogonadal (hpg) mouse that displays prepubertal spermatogenic arrest. Androgen actions were determined in hpg mice treated for 2 or 10 days with dihydrotestosterone (DHT). Follicle-stimulating hormone (FSH) actions were studied in hpg mice expressing transgenic human FSH (hpg+tgFSH) with or without DHT treatment. TJ formation was examined by mRNA expression and immunolocalization of TJ proteins claudin-3 and claudin-11, and barrier functionality was examined by biotin tracer permeability. Immunolocalization of claudin-3 and claudin-11 was extensive at wild-type (wt) Sertoli cell TJs, which functionally excluded permeability tracer. In contrast, seminiferous tubules of hpg testes lacked claudin-3, but claudin-11 protein was present in adluminal regions of Sertoli cells. Biotin tracer permeated throughout these tubules, demonstrating dysfunctional TJs. In hpg+tgFSH testes, claudin-3 was generally absent, but claudin-11 had redistributed basally toward the TJs, where function was variable. In hpg testes, DHT treatment stimulated the redistribution of claudin-11 protein toward the basal region of Sertoli cells by Day 2, increased Cldn3 and Cldn11 mRNA expression, then induced the formation of functional TJs containing both proteins by Day 10. In hpg+tgFSH testes, TJ protein redistribution was accelerated and functional TJs formed by Day 2 of DHT treatment. We conclude that androgen stimulates initial Sertoli cell TJ formation and function in mice, whereas FSH activity is insufficient alone, but augments androgen-induced TJ function.

Fatty Acid Oxidation and Hormone-Induced Meiotic Resumption in Mouse Oocytes.

Previous results from our lab showed that fatty acid oxidation (FAO) is required for the pharmacological induction of meiotic maturation in mouse oocytes in vitro. The results indicated that treatment of meiotically arrested oocytes with AICAR, an activator of AMP-activated protein kinase (AMPK), led to germinal vesicle breakdown (GVB) by stimulating FAO. Since AMPK mediates the meiosis-inducing action of hormones, the present study was carried out to examine the role of FAO in hormonal induction of meiotic resumption. For all experiments, 3-week-old C57BL/6J X SJL/J F1 mice were primed with 5 IU PMSG and for most experiments cumulus-cell-enclosed oocytes (CEO) were harvested two days later for experimentation. The culture medium used for all experiments was MEM supplemented with BSA and pyruvate. CEO kept in meiotic arrest with dibutyryl cyclic AMP (dbcAMP) were stimulated to mature in vitro by FSH or Amphiregulin and exposed to increasing concentrations of Etomoxir, Mercaptoacetate or Malonyl CoA, all inhibitors of FAO. Whereas Etomoxir and Mercaptoacetate are pharmacological inhibitors, Malonyl CoA is a physiological inhibitor produced from acetyl CoA by the enzyme acetyl CoA carboxylase. In all cases, these inhibitors significantly blocked the stimulatory effect of FSH and Amphiregulin on meiotic resumption, in many cases, to control levels. FAO inhibitors also blocked GVB in cultured follicles stimulated with hCG. On the other hand, addition of the fatty acid palmitate increased the percentage of maturation in FSH-treated CEO. To further examine this relationship, we have developed a hanging drop assay for FAO that measures the production of 14CO2 from 14C-palmitate during 4.5 h culture. Initial results show activity in spontaneously maturing CEO that is significantly augmented by hormonal stimulation. Taken together, our data indicate that fatty acid oxidation is a vital component of meiotic maturation induced by physiological signals.

Hormonal Induction of Polo-Like Kinases (Plks) and Impact of Plk2 on Cell Cycle Progression in the Rat Ovary

The highly conserved polo-like kinases (Plks) are potent regulators of multiple functions in the cell cycle before and during mitotic cell division. We investigated the expression pattern of Plk genes and their potential role(s) in the rat ovary during the periovulatory period. Plk2 and Plk3 were highly induced both in intact ovaries and granulosa cells in vivo after treatment with the luteinizing hormone (LH) agonist, human chorionic gonadotropin (hCG). In vitro, hCG stimulated the expression of Plk2 in granulosa cells, but not Plk3. This induction of Plk2 expression was mimicked by both forskolin and phorbol 12 myristate 13-acetate (PMA). Moreover, Plk2 expression was reduced by inhibitors of prostaglandin synthesis or the EGF pathway, but not by progesterone receptor antagonist (RU486) treatment. At the promoter level, mutation of the Sp1 binding sequence abolished the transcriptional activity of the Plk2 gene. ChIP assays also revealed the interaction of endogenous Sp1 protein in the Plk2 promoter region. Functionally, the over-expression of Plk2 and Plk3 arrested granulosa cells at the G0/G1 phase of the cell cycle. In contrast, the knockdown of Plk2 expression in granulosa cells decreased the number of cells in the G0/G1 stage of the cell cycle, but increased granulosa cell viability. In summary, hCG induced Plk2 and Plk3 expression in the rat ovary. Prostaglandins and the EGF signaling pathway are involved in regulating Plk2 expression. The transcription factor Sp1 is important for Plk2 transcriptional up-regulation. Our findings suggest that the increase in Plk2 and Plk3 expression contributes to the cell cycle arrest of granulosa cells which is important for the luteinization of granulosa cells during the periovulatory period.

Nutritional and Hormonal Induction of Fatty Liver Syndrome and Effects of Dietary Lipotropic Factors in Egg-type Male Chicks.

This experiment was conducted with male chicks to investigate the influence of hormones and nutrients on the development of fatty liver syndrome (FLS) as well as the effects of dietary lipotropic factors on hepatic fat accumulation and lipogenic enzyme gene expression. A total of two-hundred sixteen 4-wk-old Hy-Line male chicks were divided into six groups and fed an experimental diet (T1, low-energy diet with low levels of lipotropic factors; T2, high-energy diet with low levels of lipotropic factors; T3 and T5, low-energy diet with high levels of lipotropic factors; T4 and T6, high-energy diet with high levels of lipotropic factors) for six weeks. The chicks in T5 and T6 groups were treated with intramuscular injections of estradiol benzoate for three days prior to biopsy and clinical analysis of FLS. Chicks treated with estrogen had significantly greater liver weights than untreated chicks. The abdominal fat contents were increased in chicks consuming high-energy diets as compared to those consuming low-energy diets. Treatment with estrogen significantly increased the concentrations of serum cholesterol, triacylglycerol and phospholipid (p<0.05). The hepatic triacylglycerol levels were tenfold higher in the estrogen treated chicks than in the untreated chicks. There were no significant differences in malondialdehyde levels between the treatment groups. Estrogen treatment dramatically increased the levels of fatty acid synthetase, acetyl-CoA carboxylase and ApoB mRNA. The results indicated that treatment with exogenous estrogen in growing male chicks induced hepatic fat accumulation, which might be partially due to increased lipogenic enzyme gene expression.

QUALIDADE DE GAMETAS COM A TÉCNICA DE ENDOSCOPIA EM CURIMBA (Prochilodus lineatus)

Endoscopy can facilitate for fish and allows the performance of sexed accurately, even if its use is still restricted. The curimba is a rheophilic species of fish, used in experiments as a model species for migratory fish. This study aimed to enable the use of the endoscope in sexing breeding curimba and determine whether the technique alters the reproductive rates. Curimbas 16 were examined, in which sex was identified by the introduction of the pore urogenital endoscope for viewing the gonads. The endoscope used (model Multi-Purpose Rigid ™, Karl Storz, Germany) had a 30° angle with 2.7 mm diameter and 18 cm in length. Hormonal induction was performed 20 days after application of the technique, the females received two doses of crude extract of carp pituitary (CECP) of 0.4 and 4.0 mg / kg of fish, with an interval of 12 hours and the males receiving a single dose of 4.0 mg / kg of fish CECP, when the second application in females. After 12 hours, we proceeded to the extrusion of the gametes, which was removed a semen sample for evaluation of morphology, rate (%) and duration (seconds) motility and sperm concentration. For the females took place evaluating the weight of spawning and collecting a sample of oocytes to evaluate the position of the germinal vesicle and oocyte diameter. It can be observed that 100% of males and 62% of female spawned. In addition, all reproductive indices were considered within the standards expected for the species. It follows that the endoscope can be used efficiently in sexing and evaluating the degree of maturation prior to spawning season, without changing the reproductive efficiency of Fish.