RESUMEN
The gonad-inhibiting hormone (GIH) belongs to a neuropeptide family synthesized and released in an X-organ sinus gland complex of crustacean eyestalks. GIH inhibits crustacean ovarian maturation by suppressing vitellogenin (Vtg) synthesis, whereas estrogen is responsible for the stimulation of vitellogenesis (not established). In this study, the effects of 17ß-estradiol (E2, 10(-6) M), estrogen receptor antagonist tamoxifen (TAM, 10(-6), 10(-7), and 10(-8) M), and the environmental estrogen nonylphenol (NP, 1 µg/L and 100 µg/L) on LvGIH expression in the eyestalks of shrimp were determined by quantitative real-time PCR. Results showed that LvGIH expression decreased significantly during the L. vannamei ovarian maturation cycle. E2 and NP significantly reduced LvGIH transcripts in vivo, but TAM neutralized the inhibitory action of E2 in a dose-dependent manner (P < 0.05). In addition, the LvGIH expression levels decreased significantly in a time-dependent manner (P < 0.05) when ovary fragments were cultured in vitro with E2. The results of this study suggested that estrogen regulates GIH expression in L. vannamei eyestalks. E2 promoted ovarian development not only by directly upregulating vitellogenesis in the hepatopancreas, but it was also capable of downregulating LvGIH expression, which indirectly resulted in the stimulation of L. vannamei vitellogenesis.
Asunto(s)
Proteínas Portadoras/biosíntesis , Estradiol/farmacología , Hormonas de Invertebrados/biosíntesis , Penaeidae/efectos de los fármacos , Fenoles/farmacología , Animales , Proteínas Portadoras/genética , Antagonistas de Estrógenos/farmacología , Estrógenos/metabolismo , Femenino , Expresión Génica/efectos de los fármacos , Hormonas de Invertebrados/genética , Ovario/efectos de los fármacos , Ovario/metabolismo , Penaeidae/genética , Penaeidae/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Tamoxifeno/farmacología , Vitelogénesis/efectos de los fármacos , Vitelogeninas/metabolismoRESUMEN
The effects produced by the new synthetic carbamates ethyl-(4-bromophenyl) carbamate and ethyl-(4-chlorophenyl) carbamate on the acetylcholinesterase (AChE) activity, egg structure and reproductive organs of two Rhipicephalus microplus strains were evaluated. Inhibition kinetic parameters showed that the studied carbamates are weak inhibitors and have a low affinity for R. microplus AChE. Histologically, in oocytes from carbamate-treated engorged female ticks, a loss of shape, cytoplasmic vacuoles, decreased chorion deposition, alterations in cytoplasmic granularity and irregular membranes were observed. In oocyte germinal vesicles, a loss of shape, nucleolar fragmentation and membrane alterations with degenerative signs were observed. The ovarian epithelium was vacuolated, flattened, eroded and contained pyknotic nuclei. These alterations were observed from the first day and persisted and increased in severity until day 7 post-treatment. The ovaries from carbamate-treated ticks had fewer stage IV-V oocytes and more stage I-II oocytes. Additionally, eggs produced by the treated ticks had a modified appearance, decreased size, a reduced superficial waxy layer and a loss of viability. The results of this study show that the effects of carbamates on R. microplus were independent of AChE inhibition and show that the morphological alterations in the reproductive organs were due to carbamate actions on the vitellogenesis and viability of the ovarian cells.
Asunto(s)
Acetilcolinesterasa/metabolismo , Rhipicephalus/efectos de los fármacos , Uretano/farmacología , Animales , Supervivencia Celular/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Femenino , Oocitos/efectos de los fármacos , Ovario/efectos de los fármacos , Óvulo/efectos de los fármacos , Vitelogénesis/efectos de los fármacosRESUMEN
Rhipicephalus sanguineus are bloodsucking ectoparasites, whose main host is the domestic dog, thus being present in urban areas and closely located to people. Eventually, this tick species parasitize humans and can become a potential vector of infectious diseases. Methods to control this type of pest have been the focus of many research groups worldwide. The use of natural products is increasingly considered nowadays, due to the low toxicity levels to the host and low waste generation to the environment. This study tested the effect of ricinoleic acid esters from castor oil (as an potential acaricide) on the reproductive system of R. sanguineus females, more specifically on the vitellogenesis process. For this, two groups were established: the control group (CG) and the treatment group (TG) with five rabbits in each (New Zealand White), used as hosts. NaCl and ester were added to rabbits' food and offered to the hosts. After full engorgement, the females were collected and had their ovaries extracted. The ticks ovaries were submitted to histochemical techniques so the effects of esters could be observed over polysaccharides, proteins and lipids yolk. Changes in the deposition of yolk components were observed. This caused modifications on elements of polysaccharide origin and on glycoprotein compounds, interfering in the final yolk synthesis and compromising the development of the future embryo.
Asunto(s)
Antiparasitarios/farmacología , Aceite de Ricino/química , Ésteres/farmacología , Rhipicephalus sanguineus/efectos de los fármacos , Animales , Femenino , Oocitos/efectos de los fármacos , Vitelogénesis/efectos de los fármacosRESUMEN
During reproduction vitellogenin (VTG) is transported to vitellogenic oocytes as a precursor of egg yolk lipovitellin (LV). As VTG synthesis is affected by environmental stressors, it is widely used as biomarker in endocrine disruption studies. However, it has seldom been employed to evaluate invertebrate hydrocarbon pollution. An ELISA with anti-LV antibody was developed to evaluate the impact of water-soluble fraction of crude oil (WSF) on Macrobrachium borellii vitellogenesis. Prawn VTG concentration was within the range reported for other crustaceans; LV values were positively correlated with gonadosomatic index (GSI). Females at different vitellogenic stages were exposed to a sub-lethal concentration of WSF for 7 days. Exposed animals with GSI>7 increased their VTG and LV titer as compared to control organisms (190% and 140%, respectively). VTG levels in M. borellii were upregulated and highly sensitive to WSF exposure. This assay could be employed as a biomarker for freshwater hydrocarbon pollution.
Asunto(s)
Proteínas del Huevo/metabolismo , Contaminación por Petróleo/análisis , Petróleo/toxicidad , Vitelogeninas/metabolismo , Contaminantes Químicos del Agua/toxicidad , Animales , Biomarcadores/metabolismo , Monitoreo del Ambiente/métodos , Femenino , Palaemonidae/efectos de los fármacos , Palaemonidae/metabolismo , Petróleo/análisis , Contaminación por Petróleo/estadística & datos numéricos , Vitelogénesis/efectos de los fármacos , Contaminantes Químicos del Agua/análisisRESUMEN
The present study revealed unheard of data about the action of aqueous extracts of neem leaves (Azadirachta indica) on the vitellogenesis of Rhipicephalus sanguineus ticks, proving that these extracts in 10 and 20% concentrations do not have the potential to kill the females; however, in lower concentrations (10%) provokes great morphological alterations in germinative cells such as the emergence of extended cytoplasmic vacuolization areas as well as the fragmentation of the germinal vesicle, even in those oocytes which were in initial stages of development (I-III), showing that neem is a potent agent which acts impeding one of the main metabolic stages of the ticks, i.e., the reproduction. In oocytes in final stages of development (IV-V) azadirachtin (neem's active principle) caused significant reduction in the size and quantity of proteic granules of the yolk and the inversion of their localization where the smaller granules before inside the cell (normal oocyte) were posteriorly observed in the periphery, and the bigger ones in the central region. Thus, the study showed that the alterations found both in the oocytes and in the pedicel cells indicated that azadirachtin acts on the process of tick's reproduction and signalizes that this plant can be used in the future to control ticks with the advantage of not being aggressive to nontarget organism or the environment. Furthermore, data here obtained showed that the most significant efficiency of the aqueous extract of neem is related to the concentration of 10%, proving that higher doses would not be so efficient.
Asunto(s)
Acaricidas/farmacología , Azadirachta/química , Extractos Vegetales/farmacología , Rhipicephalus sanguineus/efectos de los fármacos , Vitelogénesis/efectos de los fármacos , Animales , Femenino , Masculino , Oocitos/citología , Oocitos/efectos de los fármacos , Oocitos/crecimiento & desarrollo , Hojas de la Planta/química , Rhipicephalus sanguineus/crecimiento & desarrollo , Rhipicephalus sanguineus/fisiologíaRESUMEN
This study examines the effects of ricinoleic acid esters from Ricinus communis castor oil on the vitellogenesis of Rhipicephalus sanguineus ticks attached to hosts that were fed with commercial rabbit food containing these esters. The oocytes of ticks from the treatment group (TG) showed cytoplasmic changes that inhibited the development of oocytes I and II to the advanced stages (IV and V) in addition to preventing the maturation of oocytes V, resulting in small ones. In addition, sperm was not observed in ampoules. Our findings confirm the acaricide potential of ricinoleic acid esters.
Asunto(s)
Oocitos/efectos de los fármacos , Rhipicephalus sanguineus/efectos de los fármacos , Ácidos Ricinoleicos/farmacología , Ricinus/química , Vitelogénesis/efectos de los fármacos , Alimentación Animal , Animales , Aceite de Ricino/química , Ésteres , Femenino , Oocitos/metabolismo , Ovario/citología , Ovario/efectos de los fármacos , Conejos , Rhipicephalus sanguineus/fisiología , Ácidos Ricinoleicos/administración & dosificaciónRESUMEN
This study investigated the effects of different doses of 17-beta-estradiol (E(2)) in Rhamdia quelen. Groups of males exposed to different doses of E(2) (0.1 mg kg(-)(1), 1 mg kg(-)(1) and 10 mg kg(-)(1)) were compared with non-exposed male and female fish groups. Among the considered biomarkers, no significant differences were observed for micronuclei test, reduced glutathione concentration and lipid peroxidation. All E(2)-treated individuals had decreased glutathione S-transferase activity. Increased catalase and superoxide dismutase activities, increased vitellogenin expression and decreased metallothionein concentration were observed in males treated with the highest dose. Liver of all test groups showed necrotic areas, but cytoplasm vacuolization was again found only in the individuals exposed to highest dose. E(2) causes deleterious hepatic effects to R. quelen, and vitellogenin expression, catalase and superoxide dismutase activity and metallothionein concentration represent appropriate biomarkers for studying E(2) effects. Additionally, the response of some biomarkers was similar in males exposed to E(2) and unexposed females, and therefore exposure to endocrine disruptors may cause consequences for fish populations.
Asunto(s)
Bagres/fisiología , Estradiol/toxicidad , Vitelogénesis/efectos de los fármacos , Contaminantes Químicos del Agua/toxicidad , Animales , Western Blotting , Catalasa/metabolismo , Relación Dosis-Respuesta a Droga , Electroforesis en Gel de Poliacrilamida , Estrógenos/toxicidad , Femenino , Agua Dulce , Glutatión/metabolismo , Glutatión Peroxidasa/metabolismo , Glutatión Transferasa/metabolismo , Peroxidación de Lípido/efectos de los fármacos , Hígado/efectos de los fármacos , Hígado/metabolismo , Hígado/patología , Masculino , Metalotioneína/metabolismo , Pruebas de Micronúcleos , Necrosis , Superóxido Dismutasa/metabolismo , Vitelogénesis/fisiología , Vitelogeninas/metabolismoRESUMEN
The ovary of the tick Rhipicephalus sanguineus consists of a wall of epithelial cells and a large number of oocytes in five different developmental stages (I-V), which are attached to the wall by a pedicel. The present study provides ultrastructural information on the effects (dose-response) of the acaricide fipronil (Frontline) on ovaries of semi-engorged females of R. sanguineus, as well as it demonstrates some possible defense mechanisms used by oocytes to protect themselves against this chemical agent. Individuals were divided into four groups. Group I was used as control while groups II, III and IV were treated with fipronil at the concentrations of 1, 5 and 10 ppm, respectively. Fipronil at the concentration of 10 ppm had the strongest effect on the development of oocytes. At this concentration, even oocytes that reached the final developmental stage exhibited damaged cell structures. Moreover, the observation in fipronil-treated R. sanguineus ticks of damaged cellular components such as plasmic membrane, mitochondria and protein granules (due to alteration in the protein synthesis), and cellular defense mechanisms such as increase in the amount of cytoplasmic microtubules and large amounts of digestive vacuoles and myelin figures, were only possible by means of ultrastructure.
Asunto(s)
Insecticidas/toxicidad , Ovario/efectos de los fármacos , Ovario/ultraestructura , Pirazoles/toxicidad , Reproducción/efectos de los fármacos , Garrapatas/fisiología , Animales , Femenino , Microscopía Electrónica de Transmisión , Oocitos/efectos de los fármacos , Oocitos/ultraestructura , Orgánulos/efectos de los fármacos , Orgánulos/ultraestructura , Ovario/citología , Vitelogénesis/efectos de los fármacosRESUMEN
Vitellogenin (Vtg), 17beta-estradiol (E2) and testosterone (T) were used as biomarkers of endocrine disruption in mature male nile tilapia (Oreochromis niloticus) from three lakes (Rio, Enmedio and Limon) in Chiapas, Mexico. Vitellogenesis induction was found in tilapias from Rio and Limon, moderately high E(2) levels in Rio and Limon tilapias, compared with controls (cultured tilapias). Significant correlations between benzo(a)pyrene (BaP) metabolites and hexachlorobenzene (HCB) with Vtg and E(2) were found. The results of this study indicate that endocrine disruption exists in tilapias from Rio and Limon lakes, and that exposure to HCB and BaP could be causing these alterations.
Asunto(s)
Disruptores Endocrinos/toxicidad , Estradiol/sangre , Hidrocarburos Clorados/toxicidad , Hidrocarburos Policíclicos Aromáticos/toxicidad , Tilapia/sangre , Vitelogeninas/sangre , Contaminantes Químicos del Agua/toxicidad , Animales , Benzo(a)pireno/metabolismo , Benzo(a)pireno/toxicidad , Hexaclorobenceno/metabolismo , Hexaclorobenceno/toxicidad , Masculino , México , Tilapia/fisiología , Vitelogénesis/efectos de los fármacosRESUMEN
Previous work on in vitro culturing of silkmoth (Bombyx mori) ovarian follicles has shown that starting from middle vitellogenesis, follicles develop according to an endogenous developmental program that does not require the presence of extra-ovarian factors. In this paper, we are reporting on our investigation for a possible involvement of autocrine/paracrine signaling by prostaglandins in the control of silkmoth ovarian follicle development. Using an initial rapid test that evaluates the formation of a protective eggshell around the oocyte, we are showing that aspirin and indomethacin, potent inhibitors of prostaglandin biosynthesis, block the transition of cultured vitellogenic follicles into choriogenesis. More detailed studies involving analyses of temporal expression patterns of genes known to be expressed in follicular epithelium cells at specific stages of ovarian development revealed that inhibition of prostaglandin biosynthesis arrests stages of follicle development from middle vitellogenesis to late choriogenesis. The arrest could be reversed by the addition of exogenous prostaglandins or cAMP into the culture media leading to the conclusion that the production of prostaglandins triggers cAMP-mediated intracellular signaling that allows the developmental progression of the follicles. Finally, because neither prostaglandins nor cAMP is capable of rescuing a developmental block effected at mid-vitellogenesis by the ecdysone agonist tebufenozide, we are proposing that prostaglandins have a role in the maintenance of normal physiological homeostasis in the ovarian follicles rather than a more specific role in developmental decision-making at distinct stages of follicle development.
Asunto(s)
Bombyx/crecimiento & desarrollo , Folículo Ovárico/crecimiento & desarrollo , Prostaglandinas/fisiología , Transducción de Señal , Animales , Aspirina/farmacología , Bombyx/efectos de los fármacos , Bombyx/metabolismo , AMP Cíclico/farmacología , Inhibidores de la Ciclooxigenasa/farmacología , Ecdisona/agonistas , Femenino , Homeostasis , Hidrazinas/farmacología , Indometacina/farmacología , Folículo Ovárico/efectos de los fármacos , Folículo Ovárico/metabolismo , Prostaglandina-Endoperóxido Sintasas/metabolismo , Prostaglandinas/metabolismo , Prostaglandinas/farmacología , Vitelogénesis/efectos de los fármacosRESUMEN
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) expressing cells were detected in pituitary, brain and ovary of the Perciform cichlid fish Cichlasoma dimerus. This detection was carried out by immunohistochemistry (IHC) and Western blot techniques using antisera of the Cyprinodontiform Fundulus heteroclitus raised against the conservative region of the teleost betaFSH and the betaLH subunits. The estimated molecular weights were 24 kDa for LH and 19 and 15 kDa for FSH. In the adult pituitary, both cell types were distributed along mid and ventral zones of the proximal pars distalis (PPD, mid-immunoreactive cells), and along the ventral and dorsal external border of the pars intermedia (PI, high-immunoreactive cells). Double IHC showed that FSH and LH are mainly expressed in different pituitary cells. FSH cells were detected in the pituitary around day 21 after hatching (ah) (prior to sex differentiation), while LH cells were detected by day 60 ah (during the sexual differentiation period). A correlation between gonadal sex differentiation and FSH was demonstrated in a 15 days organ culture system. FSH and LH neurons were localized in the nucleus lateralis tuberis and their fibers project through the ventral hypothalamus, preoptic area and neurohypophysis. FSH neurons differentiated on day 21 ah, while LH neurons appeared on day 15 ah. In the ovary, the immunoreactivity for both FSH and LH was restricted to the cytoplasm of previtellogenic and early vitellogenic oocytes.
Asunto(s)
Cíclidos/embriología , Hormona Folículo Estimulante/metabolismo , Hormona Luteinizante/metabolismo , Ovario/embriología , Hipófisis/embriología , Diferenciación Sexual , Factores de Edad , Animales , Encéfalo/citología , Encéfalo/embriología , Encéfalo/metabolismo , Femenino , Hormona Folículo Estimulante/farmacología , Hormona Liberadora de Gonadotropina/metabolismo , Inmunohistoquímica , Masculino , Fibras Nerviosas/metabolismo , Técnicas de Cultivo de Órganos , Ovario/citología , Ovario/metabolismo , Hipófisis/citología , Hipófisis/metabolismo , Testículo/citología , Testículo/embriología , Testículo/metabolismo , Vitelogénesis/efectos de los fármacos , Vitelogénesis/fisiologíaRESUMEN
In order to investigate the mechanism by which o,p'-DDT disrupts endocrine functioning of Nile tilapia in vivo, the estrogenicity of o,p'-DDT was investigated in conjunction with 17beta-estradiol (E2) and tamoxifen. Mature, male tilapia were treated intraperitoneally with o,p'-DDT (60 mg/kg, one dose) or E2 (5 mg/kg, four doses) in the presence or absence of tamoxifen (5 mg/kg, six doses) for 12 days and then plasma vitellogenin (Vtg) (measured as alkaline-labile phosphorous), E2, and testosterone (T) were measured. Vtg levels were increased dramatically by E2 (1,744 +/- 171 microg/ml) and moderately by o,p'-DDT (82 +/- 15 microg/ml) compared with controls (23 +/- 3.5 microg/ml). Tamoxifen alone had no effect on Vtg production, but inhibited both E2 and o,p'-DDT stimulated vitellogenesis. T levels were reduced with E2 administration (1,688 +/- 383 pg/ml) and declined further with the combined treatment of E2 and tamoxifen (281 +/- 70 pg/ml), compared with controls (6,558 +/- 1,438 pg/ml). Tamoxifen or o,p'-DDT alone did not affect T levels, but their combined treatment did (2,069 +/- 647 pg/ml). The results of this study suggest that o,p'-DDT is weakly estrogenic in male tilapia, and that this activity may be mediated through the estrogen receptor.