Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Crit Rev Biomed Eng ; 47(5): 427-436, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-32422032

RESUMO

Infertility is a worldwide problem affecting a large percentage of the population. Several products and techniques have been adopted to alleviate infertility condition, but the most recent and promising result was obtained through supplementation of probiotics. Continuous research on probiotics opened up a previously unknown area of its role as a modern medicine in improving fertility. New research findings suggest a profertility effect of several probiotics strains through alleviation of various fertility based disorders and modulation of the immune system. The goal of this review is to cover all the major fertility based disorders, particularly highlighting the role of probiotics in improving fertility through alleviation of such fertility based disorders.


Assuntos
Aptidão Genética/fisiologia , Sistema Imunitário/fisiologia , Infertilidade , Probióticos , Animais , Diabetes Mellitus , Suplementos Nutricionais , Modelos Animais de Doenças , Feminino , Humanos , Hiperlipidemias , Infertilidade/dietoterapia , Infertilidade/prevenção & controle , Masculino , Camundongos , Obesidade , Coelhos , Ratos , Estresse Psicológico
2.
PLoS One ; 8(12): e81140, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24324665

RESUMO

The reproductive success of a female plant in a dioecious species may be affected by pollen limitation and resource limitation. This study presents evidence that the reproductive success of the dioecious understorey tree species, Rhamnus davurica, is affected by the distance to the nearest male. The sex ratios were female-biased, although showing fluctuations in the three years of conducting the study. The mortality rate of females was higher than that of males indicating a trade-off between reproduction and survival. Altogether 49 females, designated as "focal females", were randomly selected for monitoring their reproductive status between April and October in 2010. But successful reproduction (meaning that the flowering female trees had fruit in the fruiting season) was observed only in 28 females in 2011 and 16 females in 2012. The method of path analysis was applied to determine the effect of topography, local competition and proximity to the nearest male on the fruit set of the females. In the three years of the study, elevation, competition and female size had no significant effect on the fruit set. The distance to the nearest male, however, had a significant effect on fruit set. Number of fruits and fruit set were decreased with increasing distance to the nearest male. It was possible to estimate maximum fruit set, based on the comparatively large dataset. The number of fruits and the fruit set are exponentially related to the distance to the nearest male and the relationships are described by an exponential model. The results of this study support the importance of pollen limitation on the reproductive success in Rhamnus davurica.


Assuntos
Flores/fisiologia , Aptidão Genética/fisiologia , Pólen/fisiologia , Rhamnus/fisiologia , Frutas/crescimento & desenvolvimento , Reprodução , Estações do Ano , Razão de Masculinidade , Árvores
3.
PLoS One ; 8(11): e80934, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24260515

RESUMO

Dimorphic cleistogamy is a specialized form of mixed mating system where a single plant produces both open, potentially outcrossed chasmogamous (CH) and closed, obligately self-pollinated cleistogamous (CL) flowers. Typically, CH flowers and seeds are bigger and energetically more costly than those of CL. Although the effects of inbreeding and floral dimorphism are critical to understanding the evolution and maintenance of cleistogamy, these effects have been repeatedly confounded. In an attempt to separate these effects, we compared the performance of progeny derived from the two floral morphs while controlling for the source of pollen. That is, flower type and pollen source effects were assessed by comparing the performance of progeny derived from selfed CH vs. CL and outcrossed CH vs. selfed CH flowers, respectively. The experiment was carried out with the herb Ruellia nudiflora under two contrasting light environments. Outcrossed progeny generally performed better than selfed progeny. However, inbreeding depression ranges from low (1%) to moderate (36%), with the greatest value detected under shaded conditions when cumulative fitness was used. Although flower type generally had less of an effect on progeny performance than pollen source did, the progeny derived from selfed CH flowers largely outperformed the progeny from CL flowers, but only under shaded conditions and when cumulative fitness was taken into account. On the other hand, the source of pollen and flower type influenced seed predation, with selfed CH progeny the most heavily attacked by predators. Therefore, the effects of pollen source and flower type are environment-dependant and seed predators may increase the genetic differences between progeny derived from CH and CL flowers. Inbreeding depression alone cannot account for the maintenance of a mixed mating system in R. nudiflora and other unidentified mechanisms must thus be involved.


Assuntos
Acanthaceae/fisiologia , Flores/fisiologia , Aptidão Genética/fisiologia , Polinização/fisiologia , Autofertilização/fisiologia , Acanthaceae/parasitologia , Animais , Evolução Biológica , Meio Ambiente , Comportamento Alimentar/fisiologia , Flores/anatomia & histologia , Flores/parasitologia , Endogamia , Luz , México , Mariposas/fisiologia , Pólen/fisiologia , Comportamento Predatório/fisiologia , Reprodução , Sementes/parasitologia
4.
PLoS One ; 8(1): e53695, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23308277

RESUMO

BACKGROUND: Outcrossing is known to carry genetic advantages in comparison with inbreeding. In many cases, flowering plants develop a self-incompatibility mechanism, along with a floral component adaptation mechanism, to avoid self-pollination and to promote outbreeding. Orchids commonly have a lip in their flower that functions as the a visiting plate for insect pollinators. Aside from the lip, however, many species (including Coelogyne rigida) have sheaths around the axis of inflorescence. The function of these sheaths remains unknown, and has long been a puzzle to researchers. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the function of these sheaths in relation to the lip and the pollinators, as well as their role in the modes of pollination and reproduction of Coelogyne rigida in 30 flowering populations of orchids in the limestone area of Southeast Yunnan, China. We found that self-incompatible C. rigida developed specialized bird perches around the basal axis of inflorescence to attract sunbirds and to complement their behavioral tendency to change foraging locations frequently. This self-incompatibility mechanism operates separately from the floral component adaptation mechanism. This mechanism thus prevents bees from repeatedly visiting the floral lip of the same plant which, in turn, results in autogamy. In this way, instead of preventing autogamy, C. rigida responds to these negative effects through a highly efficient cross-pollination method that successfully transfers pollen to different plants. CONCLUSIONS: The proposed method ensures reproductive success, while offsetting the infertile self-pollination by insects, thereby reducing mating costs and addressing the lack of cross-pollination. The adaptation provides a novel and striking example of structural adaptation that promotes cross-pollination in angiosperms.


Assuntos
Adaptação Fisiológica , Aptidão Genética/fisiologia , Inflorescência/anatomia & histologia , Orchidaceae/anatomia & histologia , Reprodução/fisiologia , Animais , Abelhas , Aves/fisiologia , China , Comportamento Alimentar , Feminino , Inflorescência/fisiologia , Masculino , Orchidaceae/fisiologia , Pólen/fisiologia , Polinização , Vespas
5.
Aging Cell ; 11(6): 1046-54, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22978268

RESUMO

Women approaching advanced maternal age have extremely poor outcomes with both natural and assisted fertility. Moreover, the incidence of chromosomal abnormalities and birth defects increases with age. As of yet, there is no effective and practical strategy for delaying ovarian aging or improving oocyte quality. We demonstrate that the lifelong consumption of a diet rich in omega-3 fatty acids prolongs murine reproductive function into advanced maternal age, while a diet rich in omega-6 fatty acids is associated with very poor reproductive success at advanced maternal age. Furthermore, even short-term dietary treatment with a diet rich in omega-3 fatty acids initiated at the time of the normal age-related rapid decline in murine reproductive function is associated with improved oocyte quality, while short-term dietary treatment with omega-6 fatty acids results in very poor oocyte quality. Thus, omega-3 fatty acids may provide an effective and practical avenue for delaying ovarian aging and improving oocyte quality at advanced maternal age.


Assuntos
Envelhecimento/efeitos dos fármacos , Gorduras na Dieta/administração & dosagem , Ácidos Graxos Ômega-3/administração & dosagem , Aptidão Genética/efeitos dos fármacos , Oócitos/efeitos dos fármacos , Reprodução/efeitos dos fármacos , Administração Oral , Envelhecimento/fisiologia , Animais , Cruzamento , Óleo de Coco , Ácidos Graxos Ômega-6/administração & dosagem , Ácidos Graxos Ômega-6/efeitos adversos , Feminino , Aptidão Genética/fisiologia , Humanos , Tamanho da Ninhada de Vivíparos/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Oócitos/citologia , Oócitos/fisiologia , Óleos de Plantas/administração & dosagem , Reprodução/fisiologia , Óleo de Soja/administração & dosagem
6.
Acta Histochem ; 114(4): 342-8, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21798576

RESUMO

Hibiscus sabdariffa extract is a popular beverage in many tropical and sub-tropical countries. Although, Hibiscus tea is known for its medicinal effects for thousands of years, scientific evidence of its systemic safety is very limited. The current study aimed to assess the potential adverse effects of H. sabdariffa extract on sperm morphology and testicular ultrastructure of albino mice. Thirty adult male albino mice were divided into three equal groups and were given: (a) distilled water, (b) cold Hibiscus aqueous extract, and (c) boiled Hibiscus aqueous extract. Hibiscus extract was administered orally daily for 4 weeks in a dose of 200 mg/kg body weight/mouse. Twenty-four hours after the last treatment, mice were decapitated and the testes and epididymides were excised and processed for transmission electron microscopy to assess ultrastructural and sperm abnormalities. The results clearly demonstrate that aqueous extracts from dried calyx of H. sabdariffa, either cold or boiled, alter normal sperm morphology and testicular ultrastructure and adversely influence the male reproductive fertility in albino mice. The current data suggest that Hibiscus extract should be consumed with caution, and reasonable estimates of the human risk associated with its consumption should be provided.


Assuntos
Epididimo/ultraestrutura , Hibiscus/química , Extratos Vegetais/efeitos adversos , Espermatozoides/ultraestrutura , Testículo/ultraestrutura , Administração Oral , Animais , Epididimo/efeitos dos fármacos , Fertilidade/efeitos dos fármacos , Fertilidade/fisiologia , Flores/química , Aptidão Genética/efeitos dos fármacos , Aptidão Genética/fisiologia , Masculino , Camundongos , Microscopia Eletrônica de Transmissão , Extratos Vegetais/administração & dosagem , Espermatozoides/efeitos dos fármacos , Testículo/efeitos dos fármacos
7.
J Evol Biol ; 24(11): 2456-72, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21955089

RESUMO

In gynodioecious species, in which hermaphroditic and female plants co-occur, the maintenance of sexual polymorphism relies on the genetic determination of sex and on the relative fitness of the different phenotypes. Flower production, components of male fitness (pollen quantity and pollen quality) and female fitness (fruit and seed set) were measured in gynodioecious Beta vulgaris spp. maritima, in which sex is determined by interactions between cytoplasmic male sterility (CMS) genes and nuclear restorers of male fertility. The results suggested that (i) female had a marginal advantage over hermaphrodites in terms of flower production only, (ii) restored CMS hermaphrodites (carrying both CMS genes and nuclear restorers) suffered a slight decrease in fruit production compared to non-CMS hermaphrodites and (iii) restored CMS hermaphrodites were poor pollen producers compared to non-CMS hermaphrodites, probably as a consequence of complex determination of restoration. These observations potentially have important consequences for the conditions of maintenance of sexual polymorphism in B. vulgaris and are discussed in the light of existing theory on evolutionary dynamics of gynodioecy.


Assuntos
Beta vulgaris/fisiologia , Evolução Biológica , Aptidão Genética/fisiologia , Modelos Biológicos , Processos de Determinação Sexual/fisiologia , Beta vulgaris/genética , Flores/crescimento & desenvolvimento , França , Frutas/crescimento & desenvolvimento , Fatores Sexuais
8.
Ann Bot ; 108(1): 185-95, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21546431

RESUMO

BACKGROUND AND AIMS: Plants show patterns of spatial genetic differentiation reflecting gene flow mediated by pollen and seed dispersal and genotype × environment interactions. If patterns of genetic structure are determined largely by gene flow then they may be useful in predicting the likelihood of inbreeding or outbreeding depression but should be less useful if there is strong site-specific selection. For many Australian plants little is known about either their population genetics or the effects on mating systems of variation in pollen transfer distances. Experimental pollinations were used to compare the reproductive success of bird-adapted Grevillea mucronulata plants mated with individuals from a range of spatial scales. A hierarchical survey of microsatellite DNA variation was also conducted to describe the scale of population differentiation for neutral markers. METHODS: The effects of four pollen treatments on reproductive performance were compared. These treatments were characterized by transfer of pollen from (a) neighbouring adults; (b) an adjacent cluster of adults (30-50 m distant); (c) a distant cluster (>5 km distant); and (d) open pollination. Sets of 17·9 ± 3·3 leaves from each of 15 clusters of plants were genotyped and spatial autocorrelation and F statistics were used to describe patterns of genetic structure. KEY RESULTS: Grevillea mucronulata displayed evidence of both inbreeding and outbreeding depression, with 'intermediate' pollen producing consistently superior outcomes for most aspects of fitness including seed set, seed size, germination and seedling growth. Significant genotypic structuring was detected within clusters (spatial autocorrelation) and among adjacent clusters and clusters separated by >5 km distance (F(ST) = 0·07 and 0·10). CONCLUSIONS: The superior outcome of intermediate pollen transfer and genetic differentiation of adjacent clusters suggests that G. mucronulata selection disfavours matings among closely and distantly related neighbours. Moreover, the performance of open-pollinated seedlings was poor, implying that current mating patterns are suboptimal.


Assuntos
Aptidão Genética/fisiologia , Variação Genética , Pólen/fisiologia , Proteaceae/fisiologia , Dispersão de Sementes/fisiologia , Sementes/fisiologia , Animais , Austrália , Aves/fisiologia , Cruzamento , DNA de Plantas/genética , Meio Ambiente , Fluxo Gênico , Genética Populacional , Genótipo , Germinação/genética , Desequilíbrio de Ligação , Repetições de Microssatélites/genética , Pólen/genética , Polinização , Proteaceae/genética , Reprodução , Plântula/genética , Sementes/genética
9.
Biochem Soc Trans ; 38(2): 588-92, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20298226

RESUMO

Many flowering plants are hermaphrodite, posing the problem of self-fertilization and the subsequent loss of the genetic fitness of the offspring. To prevent this, many plants have developed a genetically controlled mechanism called self-incompatibility (SI). When the male and female S-determinants match, self (incompatible) pollen is recognized and rejected before fertilization can occur. In poppy (Papaver rhoeas), the pistil S-determinant (PrsS) is a small secreted protein that interacts with incompatible pollen, initiating a Ca(2+)-dependent signalling network. SI triggers several downstream events, including depolymerization of the cytoskeleton, phosphorylation of two soluble inorganic pyrophosphatases and an MAPK (mitogen-activated protein kinase). This culminates in PCD (programmed cell death) involving several caspase-like activities. The recent discovery of the Papaver pollen S-determinant PrpS marks a significant step forward in the understanding of the Papaver SI system. PrpS encodes a ~20 kDa predicted transmembrane protein which has no homology with known proteins. It is specifically expressed in pollen, linked to the pistil S-determinant, and displays the high polymorphism expected of an S-locus determinant. The present review focuses on the discovery and characterization of PrpS which strongly support the hypothesis that Papaver SI is triggered by the interaction of PrsS and PrpS.


Assuntos
Endogamia , Papaver/fisiologia , Proteínas de Plantas/genética , Pólen/genética , Polinização/genética , Clonagem Molecular , Flores/genética , Flores/metabolismo , Flores/fisiologia , Aptidão Genética/fisiologia , Modelos Biológicos , Óvulo Vegetal/fisiologia , Papaver/genética , Proteínas de Plantas/isolamento & purificação , Proteínas de Plantas/metabolismo , Proteínas de Plantas/fisiologia , Pólen/fisiologia
10.
Biol Rev Camb Philos Soc ; 85(3): 607-23, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20039865

RESUMO

Melatonin is a molecule present in a multitude of taxa and may be ubiquitous in organisms. It has been found in bacteria, unicellular eukaryotes, macroalgae, fungi, plants and animals. A primary biological function of melatonin in primitive unicellular organisms is in antioxidant defence to protect against toxic free radical damage. During evolution, melatonin has been adopted by multicellular organisms to perform many other biological functions. These functions likely include the chemical expression of darkness in vertebrates, environmental tolerance in fungi and plants, sexual signaling in birds and fish, seasonal reproductive regulation in photoperiodic mammals, and immunomodulation and anti-inflammatory activity in all vertebrates tested. Moreover, its waning production during aging may indicate senescence in terms of a bio-clock in many organisms. Conversely, high melatonin levels can serve as a signal of vitality and health. The multiple biological functions of melatonin can partially be attributed to its unconventional metabolism which is comprised of multi-enzymatic, pseudo-enzymatic and non-enzymatic pathways. As a result, several bioactive metabolites of melatonin are formed during its metabolism and some of the presumed biological functions of melatonin reported to date may, in fact, be mediated by these metabolites. The changing biological roles of melatonin seem to have evolved from its primary function as an antioxidant.


Assuntos
Evolução Biológica , Regulação da Expressão Gênica/fisiologia , Aptidão Genética/fisiologia , Preferência de Acasalamento Animal/fisiologia , Melatonina/metabolismo , Transdução de Sinais/fisiologia , Animais , Antioxidantes/metabolismo , Escuridão , Aptidão Genética/genética , Melatonina/genética , Plantas/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA