The evolutionary success of higher plants relies on a very short gametophytic phase, which underlies the sexual reproduction cycle. Sexual plant reproduction takes place in special organs of the flower: pollen, the male gametophyte, is released from the anthers and then adheres, grows and interacts along various tissues of the female organs, collectively known as the pistil. Finally, it fertilizes the female gametophyte, the embryo sac. Pollen is released as bi or tricellular, highly de-hydrated and presumably containing all the biochemical components and transcripts to germinate. Upon hydration on the female tissues, it develops a cytoplasmic extension, the pollen tube, which is one of the fastest growing cells in nature. Pollen is completely "ready-to-go", but despite this seemingly simple reaction, very complex interactions take place with the female tissues. In higher animals, genetic mechanisms for sex determination establish striking developmental differences between males and females. In contrast, most higher plant species develop both male and female structures within the same flower, allowing self-fertilization. Outcrossing is ensured by self-incompatibility mechanisms, which evolved under precise genetic control, controlling self-recognition and cell-to-cell interaction. Equally important is pollen selection along the female tissues, where interactions between different cell types with inherent signalling properties correspond to check-points to ensure fertilization. Last but not least, pollen-pistil interaction occurs in a way that enables the correct targeting of the pollen tubes to the receptive ovules. In this review, we cover the basic mechanisms underlying sexual plant reproduction, from the structural and cellular determinants, to the most recent genetic advances.

Reproductive isolation is pivotal to maintain species separation and it can be achieved through a plethora of mechanisms. In addition, the development of barriers to gamete interaction may drive speciation. Such barriers to interspecific gamete interaction can be prezygotic or postzygotic. Considering the great diversity in animal species, it is easy to assume that regulation of the early steps of fertilization is critical to maintain species identity. One prezygotic mechanism that is often mentioned in the literature is that gamete interaction is limited to gametes of the same species. But do gametes of all animals interact in a species-specific way? Are gamete interactions completely species-specific or perhaps just species-restricted? In species in which species-restrictions have been described, is the interspecies barrier at one major step in the fertilization process or is it a combination of partially restricted steps that together lead to a block in interspecific fertilization? Are the mechanisms used to avoid interspecific crosses different between free-spawning organisms and those with internal fertilization? This review will address these questions, focusing on prezygotic barriers, and will describe what is known about the molecular biology that may account for species-limited gamete recognition and fertilization.

The hydrogel behavior of pectins and pectin localization on apertures strongly suggest that pectins act like "valves" for water entry, enabling a regulated process of water uptake into the dehydrated pollen grain. We propose that this regulation evolved in terms of achieving the correct self-organization of molecules and cellular components to resume metabolism and pollen tube growth, especially in species that are subject to demanding environmental water stress.

No abstract

This article encompasses an underlying notion of personal identities and processes of interaction, which distinguish essentialist identity from relational identity in contexts involving subjects, fields of possibilities, and cultural metamorphosis. It addresses the idea of the individual and her/his transformations: “I am who I want to be if I can be that person.” Any one of us could hypothetically have been someone else. The question of the reconstruction of individual identities is a vital aspect in the relationship between objective social conditions and what each person subjectively does with them, in terms of auto-construction. The complexity of this question reflects the idea of a cultural kaleidoscope, in which similar social conditions experienced by different individuals can produce differentiated identities. The title and structure of this text also seek to encompass the idea that in a personal life story, the subject lives between various spheres and sociocultural contexts, with a composite, mestizo, and superimposed or displaced identity, in each context. This occurs as the result of a cultural metamorphosis, which is constructed both by the individual as well as by heterogeneous influences between the context of the starting and finishing points at a given moment. This complex process of cultural metamorphosis—the fruit of interweaving subjective and objective forces—reveals a new dimension: the truly composite nature of personal identities.

Edible coatings supplemented with essential oil components have been investigated to control spoilage microorganisms. In this study, the survival of Listeria monocytogenes and Salmonella enterica serovar Typhimurium on apples treated with edible coatings based on sodium alginate (2%) (ECs) and supplemented with essential oil components, namely eugenol (Eug) at 0.2% or in combination with 0.1% (v/v) of Eug and citral (Cit) at 0.15% was determined. Both bacterial pathogens were exposed on apples treated with ECs supplemented with Eug or Eug + Cit and challenged with gastrointestinal fluids and their survival was examined. Both pathogens were able to survive on the surface of ‘Bravo de Esmolfe’ apple. The use of ECs in fresh-cut fruits impaired the survival of both bacterial populations over 72 h at 4 °C. The exposure of the pathogens on apples with ECs supplemented with Eug and Cit and challenged with gastrointestinal fluids significantly reduced their survival. This study evidences that the use of alginate edible coating enriched with Eug or the combination of Eug and Cit can contribute to the safer consumption of minimally processed fruits.

Communication skills have been considered a strategic asset for any kind of organization. However, technical-oriented enterprises usually emphasize the virtues of a cluster of technical competences and technological resources availability. So, this paper aimed to discuss communication skills development beyond technical communication in a high technology and technical-based operation, such as ground and flight operations. To do so, this article describes some tragic-ending cases in commercial aviation in which the poor quality of interpersonal communication was identified as the one of the most influential causes of the aircraft, or at least that was seen as a compelling force for creating the perfect backdrop for a disaster involving civilian aircrafts. Methodological procedures were basically addressed to a qualitative approach, supported by a documental research considering some of the most documented cases of aircraft accidents reported by the Aviation System Safety Report, issued by Federal Aviation Administration (FAA), USA, as well as reports of accidents provided by The National Transportation Safety Board (NTSB), USA,

info:eu-repo/semantics/publishedVersio