Quantification of healthy and atretic germ cells and follicles in the developing and post-natal ovary of the South American plains vizcacha, Lagostomus maximus: evidence of continuous rise of the germinal reserve.
Inserra, P I F; Leopardo, N P; Willis, M A; Freysselinard, A L; Vitullo, A D
The female germ line in mammals is subjected to massive cell death that eliminates 60-85% of the germinal reserve by birth and continues from birth to adulthood until the exhaustion of the germinal pool. Germ cell demise occurs mainly through apoptosis by means of a biased expression in favour of pro-apoptotic members of the BCL2 gene family. By contrast, the South American plains vizcacha, Lagostomus maximus, exhibits sustained expression of the anti-apoptotic BCL2 gene throughout gestation and a low incidence of germ cell apoptosis. This led to the proposal that, in the absence of death mechanisms other than apoptosis, the female germ line should increase continuously from foetal life until after birth. In this study, we quantified all healthy germ cells and follicles in the ovaries of L. maximus from early foetal life to day 60 after birth using unbiased stereological methods and detected apoptosis by labelling with TUNEL assay. The healthy germ cell population increased continuously from early-developing ovary reaching a 50 times higher population number by the end of gestation. TUNEL-positive germ cells were develops in the absence of constitutive massive germ cell elimination.
Ortiz, P. E.
Full Text Available A micromammal archaeological sequence (2120 f 120 to 780 f 100 years BP from Inca Cueva 5 site (23" 05' S - 65" 27' W; 3700 m.a.s.l., Jujuy Province, Argentina was studied. The following mammalian taxa were recorded: Order Didelphimorphia, Family Didelphidae, Thylamys cf. T. pallidior; Order Rodentia, Family Muridae, Akodon cf. A. albiventer, Andinomys edax, Auliscomys sublimis, Calomys lepidus, Neotomys ebriosus, Phyllotis sp.; Family Caviidae, Cavia cf. C. tschudii, Galea musteloides; Family Abrocomidae, Abrocoma cinerea; Family Chinchillidae, Lagidium viscacia; Family Octodontidae, Octodontomys gliroides. The taphonomy indicates that the sequence is an owl pellet accumulation inside the cave. The general landscape corresponds to the oriental border of the Puna steppe, with scattered shrub and low brush vegetation. Near the site there are small tree groups of Polylepis australis as well as small streams covered with grass and ciperaceous vegetation known as Â«vegasÂ». Al1 the recorded taxa at Inca Cueva 5 exist today in Puna and Prepuna environments from Jujuy and Salta Provinces and southem Bolivia, excepting Cavia cf. C. tschudii. The modem records of this species in northem Argentina and southern Bolivia come from localities with high montane bunchgrass prairies and forests of the humid Yungas phytogeographical region. The presence of this species in the sequence suggests wetter climatic conditions on this region when the archaeological site was originated. Later drier conditions, caused probably by anthropic influence in the last 500 years, produced the retraction of Cavia tschudii to the moist eastern side of the Andes and its disappeareance of the Puna areas.El sitio arqueológico Inca Cueva 5 se encuentra en la provincia de Jujuy, Argentina, en el borde oriental de la región de la Puna (23" 05' S - 65" 27' W; 3700 m s n m y está fechado entre 2120 f 120 y 780 f 100 años radiocarbónicos AP. El estudio de una pequeña muestra de
Hofreiter, Michael; Betancourt, Julio L.; Sbriller, Alicia Pelliza; Markgraf, Vera; McDonald, H. Gregory
Advancements in ancient DNA analyses now permit comparative molecular and morphological studies of extinct animal dung commonly preserved in caves of semiarid regions. These new techniques are showcased using a unique dung deposit preserved in a late glacial vizcacha (Lagidium sp.) midden from a limestone cave in southwestern Argentina (38.5° S). Phylogenetic analyses of the mitochondrial DNA show that the dung originated from a small ground sloth species not yet represented by skeletal material in the region, and not closely related to any of the four previously sequenced extinct and extant sloth species. Analyses of pollen and plant cuticles, as well as analyses of the chloroplast DNA, show that the Cuchillo Curá ground sloth browsed on many of the same herb, grass, and shrub genera common at the site today, and that its habitat was treeless Patagonian scrub-steppe. We envision a day when molecular analyses are used routinely to supplement morphological identifications and possibly to provide a time-lapse view of molecular diversification.
Jose L. Hierro; Kenneth L. Clark; Lyn C. Branch; Diego Villarreal
Although native herbivores can alter fire regimes by consuming herbaceous vegetation that serves as fine fuel and, less commonly, accumulating fuel as nest material and other structures, simultaneous considerations of contrasting effects of herbivores on fire have scarcely been addressed. We proposed that a colonial rodent, vizcacha (Lagostomus maximus...
Evans, Ben J; Upham, Nathan S; Golding, Goeffrey B; Ojeda, Ricardo A; Ojeda, Agustina A
The genome of the red vizcacha rat (Rodentia, Octodontidae, Tympanoctomys barrerae) is the largest of all mammals, and about double the size of their close relative, the mountain vizcacha rat Octomys mimax, even though the lineages that gave rise to these species diverged from each other only about 5 Ma. The mechanism for this rapid genome expansion is controversial, and hypothesized to be a consequence of whole genome duplication or accumulation of repetitive elements. To test these alternative but nonexclusive hypotheses, we gathered and evaluated evidence from whole transcriptome and whole genome sequences of T. barrerae and O. mimax. We recovered support for genome expansion due to accumulation of a diverse assemblage of repetitive elements, which represent about one half and one fifth of the genomes of T. barrerae and O. mimax, respectively, but we found no strong signal of whole genome duplication. In both species, repetitive sequences were rare in transcribed regions as compared with the rest of the genome, and mostly had no close match to annotated repetitive sequences from other rodents. These findings raise new questions about the genomic dynamics of these repetitive elements, their connection to widespread chromosomal fissions that occurred in the T. barrerae ancestor, and their fitness effects-including during the evolution of hypersaline dietary tolerance in T. barrerae. ©The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.
Holmgren, C.A.; Betancourt, J.L.; Rylander, K.A.; Roque, J.; Tovar, O.; Zeballos, H.; Linares, E.; Quade, Jay
Rodent (Abrocoma, Lagidium, Phyllotis) middens collected from 2350 to 2750 m elevation near Arequipa, Peru (16??S), provide an ???9600-yr vegetation history of the northern Atacama Desert, based on identification of >50 species of plant macrofossils. These midden floras show considerable stability throughout the Holocene, with slightly more mesophytic plant assemblages in the middle Holocene. Unlike the southwestern United States, rodent middens of mid-Holocene age are common. In the Arequipa area, the midden record does not reflect any effects of a mid-Holocene mega drought proposed from the extreme lowstand (100 m below modern levels, >6000 to 3500 yr B.P.) of Lake Titicaca, only 200 km east of Arequipa. This is perhaps not surprising, given other evidence for wetter summers on the Pacific slope of the Andes during the middle Holocene as well as the poor correlation of summer rainfall among modern weather stations in the central AndesAtacama Desert. The apparent difference in paleoclimatic reconstructions suggests that it is premature to relate changes observed during the Holocene to changes in El Nin??o Southern Oscillation modes. ?? 2001 University of Washington.
Celis, C.; Sepulveda, S. A.; Castruccio, A.; Lara, M.
Debris and mudflows are some of the main geological hazards in the mountain foothills of Central Chile. The risk of flows triggered in the basins of ravines that drain the Andean frontal range into the capital city, Santiago, increases with time due to accelerated urban expansion. Susceptibility assessments were made by several authors to detect the main active ravines in the area. Macul and San Ramon ravines have a high to medium debris flow susceptibility, whereas Lo Cañas, Apoquindo and Las Vizcachas ravines have a medium to low debris flow susceptibility. This study emphasizes in delimiting the potential hazardous zones using the numerical simulation program RAMMS-Debris Flows with the Voellmy model approach, and the debris-flow model LAHARZ. This is carried out by back-calculating the frictional parameters in the depositional zone with a known event as the debris and mudflows in Macul and San Ramon ravines, on May 3rd, 1993, for the RAMMS approach. In the same scenario, we calibrate the coefficients to match conditions of the mountain foothills of Santiago for the LAHARZ model. We use the information obtained for every main ravine in the study area, mainly for the similarity in slopes and material transported. Simulations were made for the worst-case scenario, caused by the combination of intense rainfall storms, a high 0°C isotherm level and material availability in the basins where the flows are triggered. The results show that the runout distances are well simulated, therefore a debris-flow hazard map could be developed with these models. Correlation issues concerning the run-up, deposit thickness and transversal areas are reported. Hence, the models do not represent entirely the complexity of the phenomenon, but they are a reliable approximation for preliminary hazard maps.
Julio L. Betancourt
Full Text Available Las zonas áridas y semiáridas de Sudamérica carecen de registros históricos exhaustivos de vegetación y clima, a pesar de la utilidad que ellos representan para el establecimiento de condiciones basales y tasas naturales de variabilidad en procesos abióticos y bióticos. Fuentes comúnmente utilizadas en el estudio de paleovegetación como el polen, son escasas en zonas áridas y semiáridas en Sudamérica, lo que se refleja en el limitado número de estudios vegetacionales durante el Cuaternario Tardío. El vacío existente en el conocimiento de la historia vegetacional de esta zona podría ser remediado gracias al descubrimiento y análisis de paleomadrigueras de roedores en ambientes rocosos. Estos depósitos, producidos por roedores de los géneros Lagidium, Phyllotis, Abrocoma y Octodontomys y posiblemente otros, son ricos en restos vegetales como ramas, hojas, polen o cutículas; y restos animales como fecas, huesos o insectos. Las paleomadrigueras de roedores han sido extensamente utilizadas en el estudio de zonas áridas en Norteamérica, donde más de 2.500 registros producidos por roedores del género Neotoma han sido analizadas desde 1960, permitiendo reconstruir una detallada historia de cambios vegetacionales y climáticos de los últimos 40.000 años en el suroeste de Norteamérica. Investigaciones recientes han revelado la presencia de paleomadrigueras en la pre-puna, los desiertos del Monte y Patagonia del oeste argentino, el desierto de Atacama al norte de Chile y sur del Perú, el matorral Mediterráneo de Chile central, y la Puna del Altiplano Andino. Estos hallazgos fortalecen el gran potencial que dichos depósitos tienen para reconstruir la vegetación y el clima en Sudamérica. Con el fin de aportar elementos para la detección, uso y análisis de paleomadrigueras de roedores, entregamos una síntesis de los depósitos registrados hasta la fecha en Sudamérica, así como una descripción de sus probables agentes
ESO, the European Southern Observatory, in reply to questions raised by the media would like to clarify its position with regard to recent events which concern the land on which the Paranal mountain is situated. THE DECISION TO BUILD THE VLT AT PARANAL In December 1987, the Council  of the European Southern Observatory decided to build the largest optical telescope in the world, the 16-metre equivalent Very Large Telescope (VLT) , before the end of the century and at a total cost that was expected to approach 500 million DEM. Already several years before that, ESO had started a search for the best possible site for this new giant telescope. At the time of Council's decision, intensive investigations at various sites in the Chilean Atacama desert had effectively narrowed down the choice to two possibilities, the Vizcachas mountain near La Silla, and the Paranal mountain, located approx. 130 km south of Antofagasta, the capital of the Chilean Region II. The meteorological data measured by the ESO teams favoured Paranal, especially in terms of number of clear nights and amount of turbulence in the atmosphere. However, while Vizcachas is situated on land that had earlier been acquired by ESO, this was not the case for the Paranal mountain. ESO was therefore very pleased to learn in 1988 that the Chilean government had decided to donate an area of 725 sq. km around Paranal to this Organisation, on the condition that it would be decided within the next five years to construct the VLT at this site. The size of this land is dictated by the need to avoid any activities (e.g., mining) which may adversely influence the exceedingly sensitive astronomical observations with the VLT. The offer was gratefully accepted by the ESO Council and in November 1988 ESO became owner of the land. After further detailed considerations of the scientific and technical implications, the ESO Council during its December 1990 meeting decided to construct the VLT on Paranal , thus
parameters had to be taken into account as well, such as the costs of construction and operations, and the operational and scientific synergy with other major facilities (VLT/VLTI, VISTA, VST, ALMA and SKA etc). In March 2010, the ESO Council was provided with a preliminary report with the main conclusions from the E-ELT Site Selection Advisory Committee . These conclusions confirmed that all the sites examined in the final shortlist (Armazones, Ventarrones, Tolonchar and Vizcachas in Chile, and La Palma in Spain) have very good conditions for astronomical observing, each one with its particular strengths. The technical report concluded that Cerro Armazones, near Paranal, stands out as the clearly preferred site, because it has the best balance of sky quality for all the factors considered and can be operated in an integrated fashion with ESO's Paranal Observatory. Cerro Armazones and Paranal share the same ideal conditions for astronomical observations. In particular, over 320 nights are clear per year. Taking into account the very clear recommendation of the Site Selection Advisory Committee and all other relevant aspects, especially the scientific quality of the site, Council has now endorsed the choice of Cerro Armazones as the E-ELT baseline site . "Adding the transformational scientific capabilities of the E-ELT to the already tremendously powerful integrated VLT observatory guarantees the long-term future of Paranal as the most advanced optical/infrared observatory in the world and further strengthens ESO's position as the world-leading organisation for ground-based astronomy," says de Zeeuw. In anticipation of the choice of Cerro Armazones as the future site of the E-ELT and to facilitate and support the project, the Chilean Government has agreed to donate to ESO a substantial tract of land contiguous to ESO's Paranal property and containing Armazones in order to ensure the continued protection of the site against all adverse influences, in particular light