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General and Comparative Endocrinology

K J MacLeod, M J Sheriff, D C Ensminger, D A S Owen, T Langkilde
Organisms are continuously encountering both predictable and unpredictable ecological stressors within their environment. The activation of the hypothalamic-pituitary-adrenal (stress) axis is a fundamental process allowing animals to cope with and respond to such encounters. A main consequence of HPA axis activation is the release of glucocorticoid hormones. Although short-term glucocorticoid elevations lead to changes in physiological and behavioral processes that are often adaptive, our understanding of fitness consequences of repeated acute elevations in glucocorticoid hormones over a longer time period is largely lacking...
July 14, 2018: General and Comparative Endocrinology
Xixi Song, Hongchao Jiao, Jingpeng Zhao, Xiaojuan Wang, Hai Lin
Ghrelin is one of the most important appetite regulating peptides, involved in the regulation of energy homeostasis. The role of ghrelin on the appetite and fat metabolism in chickens is different from that of ghrelin in mammals. Glucocorticoids and insulin are important hormones and work differently in energy regulation of body. In this study, the effects of dexamethasone (DEX, 2.0 mg/kg BW), subcutaneous insulin injection (40 µg/kg BW), and glucose load on ghrelin secretion and expression were determined in broilers...
July 14, 2018: General and Comparative Endocrinology
Robert de Bruijn, L Michael Romero
Changes in the environment related to inclement weather can threaten survival and reproductive success both through direct adverse exposure and indirectly by decreasing food availability. Glucocorticoids, released during activation of the hypothalamic-pituitary-adrenal axis as part of the stress response, are an important candidate for linking vertebrate coping mechanisms to weather. This review attempts to determine if there is a consensus response of glucocorticoids to exposure to weather-related stimuli, including food availability, precipitation, temperature and barometric pressure...
July 14, 2018: General and Comparative Endocrinology
Dennis Kolosov, Michael J O'Donnell
Excretion in insects is accomplished by the combined actions of the Malpighian tubules (MTs) and hindgut, which together form the functional kidney. MTs of many insect groups consist of principal cells (PC) and secondary cells (SC). In most insect groups SCs are reported to secrete ions from haemolymph into the tubule lumen. Paradoxically, SCs in the MTs of the lepidopteran cabbage looper T. ni are used to reabsorb Na+ and K+ back into haemolymph. The current study was designed to investigate the effects and mode of action of the lepidopteran kinin, Helicokinin (HK), on ion transport in the SC-containing region of MT of T...
July 14, 2018: General and Comparative Endocrinology
D E K Campbell, V S Langlois
A series of ex vivo exposures using testicular and ovarian tissues of sexually mature Western clawed frogs (Silurana tropicalis) were designed to examine molecular mechanisms of thyroid hormone (TH) and androgen crosstalk sans hypophyseal feedback as well as investigate potential sex-specific differences. Tissues were exposed ex vivo to either triiodothyronine (T3), iopanoic acid (IOP), one co-treatment of IOP + 5α-dihydrotestosterone (5α-DHT), 5α-DHT, 5β-dihydrotestosterone (5β-DHT), or testosterone (T)...
July 7, 2018: General and Comparative Endocrinology
I T Moore, B J Vernasco, C Escallón, T W Small, T B Ryder, B M Horton
Studies of birds have greatly advanced our understanding of how testosterone modulates complex phenotypes, specifically its role in mediating male reproductive and associated behaviors. Yet most of the foundational studies have been limited to northern latitude breeding species despite the fact that they represent only a small fraction of worldwide avian diversity. In contrast, phylogenetic, life-history, and mating system diversity all reach their apex in neotropical avifauna and yet these birds, along with more southern latitude species, remain very poorly understood from an endocrine perspective...
July 7, 2018: General and Comparative Endocrinology
Juan Ignacio Fernandino, Ricardo Shohei Hattori
The high biodiversity of fish in the Neotropical region contrasts with scarce or biased studies on the mechanisms involved in the sex determination in members of this fauna. In this review, we attempted to compile the information available on determination, differentiation, and manipulation of sex for Neotropical species, with special focus on silversides and other two speciose groups, known as characins (Characiformes) and catfishes (Siluriformes). Currently, there is plenty of information available on chromosomal sex determination systems, which includes both male and female heterogamety with many variations, and sex chromosomes evolution at the macro chromosomal level...
July 7, 2018: General and Comparative Endocrinology
G M J Costa, A L Sousa, A F A Figueiredo, S M S N Lacerda, L R França
Undifferentiated spermatogonia (Aund ) or spermatogonial stem cells (SSCs) are committed to the establishment and maintenance of spermatogenesis and fertility throughout a male's life and are located in a highly specialized microenvironment called niche that regulates their fate. Although several studies have been developed on SSCs in mammalian testis, little is known about other vertebrate classes. The present study is the first to perform a more detailed investigation on the spermatogonial cells and their niche in a reptilian species...
June 29, 2018: General and Comparative Endocrinology
Yuji Mushirobira, Osamu Nishimiya, Jun Nagata, Takashi Todo, Akihiko Hara, Benjamin J Reading, Naoshi Hiramatsu
Transcription of vitellogenin (vtg) genes are initiated when estradiol-17β (E2 )-estrogen receptor (ER) complexes bind estrogen response elements (ERE) located in the gene promoter region. Transcriptional regulation of dual vtg subtypes (major salmonid A-type vtg: vtgAs; minor C-type vtg: vtgC) by E2 was investigated under co-expression of a potential major transcriptional factor, erα1, in cutthroat trout. Two forms of trout vtgAs promoters (1 and 2) and one vtgC promoter were sequenced. These promoters structurally differ based on the number of EREs present...
June 29, 2018: General and Comparative Endocrinology
Gai Mei Du, Bi Ping Luo, Zhi Hua Hu, Jie Ge Wu, Wen Mei Yan, Zheng Qiang Han, Yu Hong Zhang, Mao Jun Liu
Ghrelin is implicated in the regulation of gastric functional development. The octanoylation of ghrelin is critical for its physiological functions which dependent upon ghrelin O-acyltransferase (GOAT) catalyzation. To investigate the effect of GOAT on gastric acid secretion and expression of ghrelin in vitro. Primary cultures of gastric mucosal cells were challenged with 1.5×10-5 , 1.5×10-4 and 1.5×10-3 mol/ml GO-CoA-Tat (The GOAT inhibitor), respectively, for 24 h in order to further clarify the effect of GOAT on H+ -K+ -ATPase activity...
June 29, 2018: General and Comparative Endocrinology
A Rawat, R Chaube, K P Joy
Investigations on the role of the reproductive hormones on VT receptor gene expression are lacking in teleosts. Previously we reported that gonadotropin and steroid hormones modulate the secretion and gene expression of brain and ovarian vasotocin (VT) in the catfish Heteropneustes fossilis. In continuation, in the present study we investigated the role of estradiol-17β (E2 ), the maturation-inducing steroid (MIS) 17α, 20β-dihydroxy-4-pregnen-3-one (17,20β-DP), and human chorionic gonadotropin (hCG) on the expression of VT receptor genes (v1a1, v1a2 and v2a) in the brain and ovary of the catfish in early (previtellogenic, preparatory) and late (post vitellogenic, prespawning) phases of the ovarian cycle...
June 28, 2018: General and Comparative Endocrinology
Namya Mellouk, Christelle Ramé, Joël Delaveau, Christophe Rat, Eric Maurer, Pascal Froment, Joëlle Dupont
In broiler chickens, the intense genetic selection for rapid growth has resulted in an increase in growth rate and fat deposition. Adipose tissue is now recognized as an important endocrine organ that secretes a variety of factors including adipokines. However, the expression pattern of these adipokines is unclear in chicken embryo development. In the present study, we determined the expression profile of three novel adipokines, NAMPT, RARRES2 and ADIPOQ, and their cognate receptors in metabolic tissues (liver, muscles and adipose tissue) of chicken embryo/chicks from 15 days of incubation (E15) to hatching (D0)...
June 25, 2018: General and Comparative Endocrinology
Peter W Sorensen, Christopher Appelt, Norman E Stacey, Fredrick Wm Goetz, Alan R Brash
This study tested the hypothesis that blood-borne prostaglandin F2α (PGF2α ) produced at the time of ovulation by female goldfish, a typical scramble-spawning, egg-laying cyprinid fish, functions as a hormone which stimulates female sexual receptivity, behavior, and pheromone release, thereby synchronizing female mating behavior with egg availability. We conducted 5 experiments. First, we tested whether PGF2α is found in the blood of female fish and if it increases at the time of ovulation. Using gas chromatography-mass spectrometry, we found that circulating PGF2α was approximately 1 ng/ml prior to ovulation, increased over 50-fold within 3 h of ovulation and returned to preovulatory values after spawning and egg release...
June 22, 2018: General and Comparative Endocrinology
Ángela Gárriz, Pamela S Del Fresno, Pedro Carriquiriborde, Leandro A Miranda
Some heavy metals related to human activities were measured in the water of Chascomús lake. The maximum concentrations were: 0.23 μg/L for Cd, 4.28 μg/L for Cr, 22.09 μg/L for Cu, 2.49 μg/L for Ni, 3.24 μg/L for Pb and 210.76 μg/L for Zn. The values of Cd, Cr, Cr, Pb and Zn were above the Argentine National Guidelines for the Protection of the Aquatic life. The analysis of gonadal condition of pejerrey fish (Odontesthes bonariensis) from this lake did not revealed any reproductive damages. However, exposures with environmental concentrations of Cd, Cr, Cu and Zn under laboratory conditions of pejerrey males (14 days), caused a significant increase of the expression of the three variants of gnrh in the brain (within Cd exposure) and a decrease in cyp19a1b mRNA (within Cu exposure)...
June 22, 2018: General and Comparative Endocrinology
Cristina Velasco, Ayelén M Blanco, Suraj Unniappan, José L Soengas
We hypothesize that peptide YY (PYY) is involved in the metabolic regulation of food intake in fish. Therefore, we assessed in rainbow trout (Oncorhynchus mykiss) the effects of intracerebroventricular treatment with 10 ng/g PYY1-36 on food intake, expression of neuropeptides involved in food intake control, and the activity of fatty acid-sensing systems. The administration of PYY1-36 caused a significant reduction in food intake up to 24 hours post-treatment. This anorectic action is associated with changes 2h after treatment in mRNA abundance of neuropeptides involved in metabolic regulation of food intake in hypothalamus (decreased NPY and raised CART values) and hindbrain (increased POMCa1 values)...
June 22, 2018: General and Comparative Endocrinology
Uriel Koziol
Tardigrades are a key group for understanding the evolution of the Ecdysozoa, a large clade of molting animals that also includes arthropods and nematodes. However, little is known about most aspects of their basic biology. Neuropeptide and peptide hormone signaling has been extensively studied in arthropods and nematodes (particularly regarding their roles in molting in arthropods), but very little is known about neuropeptide signaling in other ecdysozoans. In this work, different strategies were used to search for neuropeptide and peptide hormone precursors in the genomes of the tardigrades Hypsibius dujardini and Ramazzottius varieornatus...
June 20, 2018: General and Comparative Endocrinology
John P Chang, Hamid R Habibi
No abstract text is available yet for this article.
June 20, 2018: General and Comparative Endocrinology
Marieke K Jones, Lauren E Reiter, Michael P Gilmore, Elizabeth W Freeman, Nucharin Songsasen
The maned wolf is a threatened canid species native to South America. Previous studies have suggested the species exhibits induced ovulation. In captive breeding facilities, reproductive success is low while rates of neonatal mortality are high. Females that are not recommended for breeding are frequently housed together. However there has never been a systematic study of the reproductive consequences of co-housing females. This study was conducted for three purposes, to: (1) corroborate the presence of induced ovulation, (2) determine whether elevated cortisol is implicated in neonatal pup mortality, and (3) evaluate the endocrine correlates of group housed females...
June 15, 2018: General and Comparative Endocrinology
Todd R Robeck, Jason L Blum, Karen J Steinman, Jill R Ratner, Don R Bergfelt, Justine K O'Brien
The circulating pattern of immunoreactive relaxin and progestagens based on monthly and gestational stage (early, mid, late) profiles were determined during pregnancies that resulted in live calves (LIVE, n = 30), stillbirths (STILLB, n = 3), abortions (ABORT, n = 5) and presumptive false pregnancies (FALSE, n = 8), and during the follicular (n = 34) and luteal phases (n = 58). Monthly LIVE relaxin concentrations steadily increased during gestation, but values did not significantly exceed those of the luteal phase until 10 months prior to parturition, peaking during the final month at 2,356 ng/ml...
June 15, 2018: General and Comparative Endocrinology
Lucas A Zena, Danielle Dillon, Kathleen E Hunt, Carlos A Navas, Kênia C Bícego, C Loren Buck
The tegu lizard Salvator merianae is a large, widely distributed teiid lizard endemic to South America that exhibits annual cycles of high activity during the spring and summer, and hibernation during winter. This pattern of activity and hibernation is accompanied by profound seasonal changes in physiology and behavior, including endothermy during the austral spring. The unusual combination of seasonal endothermy, hibernation and oviparity, in a non-avian, non-mammalian species, makes S. merianae an interesting subject for study of comparative aspects of endocrine regulation of seasonal changes in physiology...
June 15, 2018: General and Comparative Endocrinology
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