Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
PLoS One ; 11(9): e0162344, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27622546

RESUMO

In the reproduction process of male and female fish, pituitary derived gonadotropins (GTHs) play a key role. To be able to specifically investigate certain functions of Luteinizing (LH) and Follicle stimulating hormone (FSH) in Russian sturgeon (Acipenser gueldenstaedtii; st), we produced recombinant variants of the hormones using the yeast Pichia pastoris as a protein production system. We accomplished to create in vitro biologically active heterodimeric glycoproteins consisting of two associated α- and ß-subunits in sufficient quantities. Three dimensional modelling of both GTHs was conducted in order to study the differences between the two GTHs. Antibodies were produced against the unique ß-subunit of each of the GTHs, in order to be used for immunohistochemical analysis and to develop an ELISA for blood and pituitary hormone quantification. This detection technique revealed the specific localization of the LH and FSH cells in the sturgeon pituitary and pointed out that both cell types are present in substantially higher numbers in mature males and females, compared to immature fish. With the newly attained option to prevent cross-contamination when investigating on the effects of GTH administration, we compared the steroidogeneic response (estradiol and 11-Keto testosterone (11-KT) in female and males, respectively) of recombinant stLH, stFSH, and carp pituitary extract in male and female sturgeon gonads at different developmental stages. Finally, we injected commercially available gonadotropin releasing hormones analog (GnRH) to mature females, and found a moderate effect on the development of ovarian follicles. Application of only testosterone (T) resulted in a significant increase in circulating levels of 11-KT whereas the combination of GnRH + T did not affect steroid levels at all. The response pattern for estradiol demonstrated a similar situation. FSH levels showed significant increases when GnRH + T was administered, while no changes were present in LH levels.


Assuntos
Peixes/fisiologia , Gonadotropinas Hipofisárias/fisiologia , Esteroides/fisiologia , Animais , Ensaio de Imunoadsorção Enzimática , Estradiol/metabolismo , Feminino , Hormônio Foliculoestimulante/química , Hormônio Foliculoestimulante/farmacologia , Hormônio Liberador de Gonadotropina/análogos & derivados , Hormônio Liberador de Gonadotropina/farmacologia , Gonadotropinas Hipofisárias/química , Hormônio Luteinizante/química , Hormônio Luteinizante/farmacologia , Masculino , Modelos Moleculares , Folículo Ovariano/efeitos dos fármacos , Folículo Ovariano/fisiologia , Hipófise/efeitos dos fármacos , Hipófise/fisiologia , Subunidades Proteicas , Proteínas Recombinantes/química , Proteínas Recombinantes/farmacologia , Testículo/efeitos dos fármacos , Testículo/fisiologia , Testosterona/análogos & derivados , Testosterona/metabolismo , Testosterona/farmacologia
2.
J Acoust Soc Am ; 122(1): 120-7, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17614471

RESUMO

This paper reports work on a nonpremixed half-dump combustor, in which methane is injected at the backward-facing step, and mixes and burns with the air flowing past the step in the unsteady recirculation zone. The flow and geometric parameters are widely varied, to gradually change from conditions of low-amplitude noise to excitation of high-amplitude discrete tones. The purpose of the work is to focus on the transition from the former condition to the latter, and to mark the onset of instability. Dimensionless groups such as the Helmholtz and Strouhal numbers are formed based on the observed dominant frequencies, whose variation with the air flow Reynolds number is used to identify the oscillations as those due to the natural acoustic modes or the vortex shedding process. High-speed chemiluminescence imaging reveals shedding of vortical structures in the flame zone. With variation in the conditions, flow-acoustic lock-on and transition from one vortex shedding mode to another is marked by nonlinearity in the corresponding amplitude variations. Such conditions are identified as the onset of instability in terms of the ratio of the flow time scale to the acoustic time scale and mapped against the operating fuel-air equivalence ratio of the combustor.


Assuntos
Incineração/instrumentação , Metano , Modelos Teóricos , Ruído , Movimentos do Ar , Desenho de Equipamento , Gases , Temperatura Alta , Movimento (Física) , Pressão , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA