-In the present study, the morphology, color pattern, chromosomal complement and aspects of meiosis in natural populations at the borders of the distributions of Mepraia gajardoi Frías et al and Mepraia spinolai (Porter) are described. The males of these bordering populations are brachypterous or macropterous, while females are always micropterous. Morphological and cytogenetic data indicated that the populations that border the distributions of M. gajardoi and M. spinolai, belong to a different species of parapatric origin. (Sagua et al 2000, Canals et al 2001, Carvajal et al 2007, Botto-Mahan et al 2008. This disease is important in the Neotropical region with nearly 16 million people infected, and another 90 million at risk of contracting the disease, especially in rural areas (Schofi eld et al 1982, Schofi eld 1994.Mepraia gajardoi differs from M. spinolai in body color, morphology, genitalia and karyotype. Females of both species are invariably wingless (micropterous). Males of M. gajardoi are always winged (brachypterous), whereas males of M. spinolai may be winged (macropterous, brachypterous) or wingless (micropterous) (Mazza et al 1940, Neiva & Lent 1940, Lent & Jurberg 1967. Reciprocal crossbreeding experiments showed that the two species are reproductively isolated (Frías et al 1998).The karyotypes of both species are formed by 20 autosomes and an X1 X2 Y sex system. However, males of M. gajardoi have a large Y chromosome, whereas those of M. spinolai are polymorphic for a small neo-Y chromosome, which may have originated by a fracture of the large holocentric Y chromosome of M. gajardoi (Frías & Atria 1998). Also, a particular heteropycnotic chromocenter, typical of M. spinolai, differentiates this species from M. gajardoi. It is formed by sex chromosomes surrounded by several autosomal heteropycnotic dots. Other heteropycnotic regions outside this chromocenter can also be observed (Frías & Atria 1998, Perez et al 2004 In the present study, I report the morphological traits of adults and the chromosomal complement of populations of Mepraia species bordering the distribution of M. gajardoi and M. spinolai, with a discussion of their mode of speciation. Material and MethodsPopulations studied. The specimens examined were collected during the summer of 1996 by D Frías and A Alviña, and during spring, in November 2002, by D Frías, from region III of Atacama and region II of Antofagasta (Fig 1). The former region is located in the Parque Nacional Pan
Neo-Darwinian explanations of organic evolution have settled on mutation as the principal factor in producing evolutionary novelty. Mechanistic characterizations have been also biased by the classic dogma of molecular biology, where only proteins regulate gene expression. This together with the rearrangement of genetic information, in terms of genes and chromosomes, was considered the cornerstone of evolution at the level of natural populations. This predominant view excluded both alternative explanations and phenomenologies that did not fit its paradigm. With the discovery of non-coding RNAs (ncRNAs) and their role in the control of genetic expression, new mechanisms arose providing heuristic power to complementary explanations to evolutionary processes overwhelmed by mainstream genocentric views. Viruses, epimutation, paramutation, splicing, and RNA editing have been revealed as paramount functions in genetic variations, phenotypic plasticity, and diversity. This article discusses how current epigenetic advances on ncRNAs have changed the vision of the mechanisms that generate variation, how organism-environment interaction can no longer be underestimated as a driver of organic evolution, and how it is now part of the transgenerational inheritance and evolution of species.
Despite current advances on the relevance of environmental cues and epigenetic mechanisms in biological processes, including behavior, little attention has been paid to the potential link between epigenetic influences and educational sciences. For instance, could the learning environment and stress determine epigenetic marking, affecting students' behavior development? Could this have consequences on educational outcomes? So far, it has been shown that environmental stress influences neurological processes and behavior both in humans and rats. Through epigenetic mechanisms, offspring from stressed individuals develop altered behavior without any exposure to traumatizing experiences. Methylated DNA and noncoding RNAs regulate neurological processes such as synaptic plasticity and brain cortex development in children. The malfunctioning of these processes is associated with several neurological disorders, and these findings open up new avenues for the design of enriched environments for education and therapy. In this article, we discuss current cases of stress and behavioral disorders found in youngsters, and highlight the importance of considering epigenetic processes affecting the development of cognitive abilities and learning within the educational environment and for the development of teaching methodologies.
The origin of genes is one of the most enigmatic events in the origin of life. It has been suggested that noncoding (nc) RNA was probably a precursor in the formation of the first polypeptide, and also at the origin of the first manifestation of life and genes. ncRNAs are also becoming central for understanding gene expression and silencing. Indeed, before the discovery of ncRNAs, proteins were viewed as the major molecules in the regulation of gene expression and gene silencing; however, recent findings suggest that ncRNA also plays an important role in gene expression. Reverse transcription of RNA viruses and their integration into the genome of eukaryotes and also their relationship with the ncRNA suggest that their origin is basal in genome evolution, and also probably constitute the first mechanism of gene regulation. I am to review the different roles of ncRNAs in the framework of gene evolution, as well as the importance of ncRNAs and viruses in the epigenesis and in the non-Mendelian model of heredity and evolution.
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