Re-significación de la representación matemática en niños de grado tercero de primaria en una institución educativa pública de Santiago De Cali (Colombia)

En este artículo se busca analizar la re-significación de la representación matemática en niños de grado tercero de primaria en una institución educativa pública de Santiago de Cali. Por lo tanto, se exploró inicialmente el significado que tenían los estudiantes sobre qué son las matemáticas y se registró la información. A continuación, se implementó una tarea matemática basada en una comprensión lectora (poema), la cual es diferente de las actividades tradicionales utilizadas en el salón de clase y nuevamente surgió la pregunta sobre qué son las matemáticas. Finalmente, se indagó sobre qué les pareció la actividad en su totalidad, se recolectó la información y se organizó en una base de datos para su posterior interpretación. El análisis del material recolectado se realizó utilizando el método de análisis de contenido de Bardin (2002), pero se implementaron modificaciones, las cuales fueron propuestas por el investigador

Mosaic Genome Architecture of the Anopheles gambiae Species Complex

Attempts over the last three decades to reconstruct the phylogenetic history of the Anopheles gambiae species complex have been important for developing better strategies to control malaria transmission.We used fingerprint genotyping data from 414 field-collected female mosquitoes at 42 microsatellite loci to infer the evolutionary relationships of four species in the A. gambiae complex, the two major malaria vectors A. gambiae sensu stricto (A. gambiae s.s.) and A. arabiensis, as well as two minor vectors, A. merus and A. melas.We identify six taxonomic units, including a clear separation of West and East Africa A. gambiae s.s. S molecular forms. We show that the phylogenetic relationships vary widely between different genomic regions, thus demonstrating the mosaic nature of the genome of these species. The two major malaria vectors are closely related and closer to A. merus than to A. melas at the genome-wide level, which is also true if only autosomes are considered. However, within the Xag inversion region of the X chromosome, the M and two S molecular forms are most similar to A. merus. Near the X centromere, outside the Xag region, the two S forms are highly dissimilar to the other taxa. Furthermore, our data suggest that the centromeric region of chromosome 3 is a strong discriminator between the major and minor malaria vectors.Although further studies are needed to elucidate the basis of the phylogenetic variation among the different regions of the genome, the preponderance of sympatric admixtures among taxa strongly favor introgression of different genomic regions between species, rather than lineage sorting of ancestral polymorphism, as a possible mechanism

Accumulation and Rapid Decay of Non-LTR Retrotransposons in the Genome of the Three-Spine Stickleback

The diversity and abundance of non–long terminal repeat (LTR) retrotransposons (nLTR-RT) differ drastically among vertebrate genomes. At one extreme, the genome of placental mammals is littered with hundreds of thousands of copies resulting from the activity of a single clade of nLTR-RT, the L1 clade. In contrast, fish genomes contain a much more diverse repertoire of nLTR-RT, represented by numerous active clades and families. Yet, the number of nLTR-RT copies in teleostean fish is two orders of magnitude smaller than in mammals. The vast majority of insertions appear to be very recent, suggesting that nLTR-RT do not accumulate in fish genomes. This pattern had previously been explained by a high rate of turnover, in which the insertion of new elements is offset by the selective loss of deleterious inserts. The turnover model was proposed because of the similarity between fish and Drosophila genomes with regard to their nLTR-RT profile. However, it is unclear if this model applies to fish. In fact, a previous study performed on the puffer fish suggested that transposable element insertions behave as neutral alleles. Here we examined the dynamics of amplification of nLTR-RT in the three-spine stickleback (Gasterosteus aculeatus). In this species, the vast majority of nLTR-RT insertions are relatively young, as suggested by their low level of divergence. Contrary to expectations, a majority of these insertions are fixed in lake and oceanic populations; thus, nLTR-RT do indeed accumulate in the genome of their fish host. This is not to say that nLTR-RTs are fully neutral, as the lack of fixed long elements in this genome suggests a deleterious effect related to their length. This analysis does not support the turnover model and strongly suggests that a much higher rate of DNA loss in fish than in mammals is responsible for the relatively small number of nLTR-RT copies and for the scarcity of ancient elements in fish genomes. We further demonstrate that nLTR-RT decay in fish occurs mostly through large deletions and not by the accumulation of small deletions

Fructose-driven glycolysis supports anoxia resistance in the naked mole-rat

The African naked mole-rat’s ($\textit{Heterocephalus glaber}$) social and subterranean lifestyle generates a hypoxic niche. Under experimental conditions, naked mole-rats tolerate hours of extreme hypoxia and survive 18 minutes of total oxygen deprivation (anoxia) without apparent injury. During anoxia, the naked mole-rat switches to anaerobic metabolism fueled by fructose, which is actively accumulated and metabolized to lactate in the brain. Global expression of the GLUT5 fructose transporter and high levels of ketohexokinase were identified as molecular signatures of fructose metabolism. Fructose-driven glycolytic respiration in naked mole-rat tissues avoids feedback inhibition of glycolysis via phosphofructokinase, supporting viability. The metabolic rewiring of glycolysis can circumvent the normally lethal effects of oxygen deprivation, a mechanism that could be harnessed to minimize hypoxic damage in human disease.Work was supported aEuropean Research Council (294678), the Deutsche Forschungsgemeinschaft SFB 665 and Go865/9-1, NSF (grant #0744979 ), NIH (grants HL71626 and HL606

Extreme Resistance to Hypercapnia-Induced Pulmonary Edema of the African Naked Mole-Rat

The African naked-mole rat lives chronically in a hypercapnia due to many individuals living together in small enclosed burrows. At extreme hypercapnia, pulmonary edema is induced in many terrestrial mammals. The present study aim was to examine the resistance naked mole-rats have to the physiological effects of hypercapnia and determine the mechanism of hypercapnia-induced pulmonary edema. We found extreme hypercapnia was unable to induce pulmonary edema in naked mole-rats. Previously, their cutaneous c-fibers were found to be insensitive to acid stimuli and this was thought to be an adaptation to hypercapnia acidosis. Pulmonary c-fibers release the peptide substance P that can induce pulmonary edema. A related peptide, hemokinin-1, has the same endogenous receptor, neurokinin 1, and is also present within the lungs. We predicted that naked mole-rats in response to hypercapnia would have attenuated release of substance P and hemokinin-1 within their lungs. Surprisingly, naked mole-rats had no detectable amount of substance P or hemokinin-1 in lavage fluid at control or after 30% CO2 exposure. We further studied the function of pulmonary c-fiber acid sensitivity in hypercapnia-induced pulmonary edema. Mice that lack channels expressed by c-fibers that are acid sensitive, TrpV1 and ASIC3, were exposed to extreme hypercapnia. We found that the absence of these channels had no effect on hypercapnia-induced pulmonary edema. We also used mice that lacked substance P gene, tac1, expression and found significant increased edema that was counter to our original hypothesis. The volatile anesthetic isoflurane has previously been found to have anti-inflammatory effect on pulmonary induced inflammation. We used isoflurane in conjunction with acute 30% CO2 exposure in mice. We found that isoflurane greatly attenuated hypercapnia-induced edema and abolished the increased release of substance P and hemokinin-1 in lung lavage fluid of wild-type mice. These results indicated that hypercapnia-induced pulmonary edema may not be mediated by the acid-sensitivity of pulmonary c-fibers but may involve hemokinin-1. For the first time, isoflurane was found to attenuate hypercapnia-induced pulmonary edema. The absence of detectable substance P and hemokinin-1 within the naked mole-rat lungs may be part of their adaptation for living in hypercapnia