Papers by Humberto González
Genotype and virulence correlation within Mexican stocks of Trypanosoma cruzi isolated from patients
Acta Tropica, 1998
Five Trypanosoma cruzi stocks were isolated from infected patients in the central state of Jalisc... more Five Trypanosoma cruzi stocks were isolated from infected patients in the central state of Jalisco, Mexico. Parasites were isolated by direct inoculation of infected blood into BALB/c mice. The five stocks of T. cruzi were analyzed for in vitro growth, and for virulence and parasitic load in vivo. Furthermore, a genetic analysis based on restriction fragment length polymorphism associated with a repetitive element from the rRNA gene spacer was performed. No differences in in vitro growth or in parasitic load in vivo were found among the stocks. While three stocks showed low virulence for mice, the other two stocks killed 80 and 100% of the infected mice. In addition, Southern blot of total DNA hybridized with a repetitive element from the rRNA gene spacer showed two clearly distinct patterns that correlated with the observed ability of the stocks to kill infected mice. Our results show a correlation among the ability to kill BALB/c mice, the genetic pattern and clinical symptoms produced by the different stocks in the infected patients.
Composition, biomass and potential grazing impact of the crustacean and pelagic tunicates in the northern Humboldt Current area off Chile:differences between El Niño and non-El Niño years
Marine Ecology-progress Series, 2000
ABSTRACT A multi-disciplinary research program was conducted in the northern Humboldt Current Sys... more ABSTRACT A multi-disciplinary research program was conducted in the northern Humboldt Current System in a 80 x 80 nautical mile area off Antofagasta, northern Chile (23°S) on 3 occasions: before the 1997/98 El Nino event (January 1997), and during the onset and maximum periods of the event (July 1997 and January 1998, respectively). As a part of this program, the trophodynamic role of pelagic tunicates (salps and appendicularians), as well as the crustacean zooplankton, divided into 3 size classes (large- [euphausiids], medium- [large calanoid copepods] and small-size animals [small calanoid and cyclopoid copepods]) were assessed. One of the most conspicuous physical processes was the deepening of the thermocline during the El Nino event, which in turn led to suppression of nutrient enrichment by upwelling events and low chlorophyll a (chl a) concentrations in the study area. Chl a and particulate organic carbon (POC) values were higher near the coast, and coastal/oceanic gradients were greater in the case of chl a. High chl a (100 to 160 mg m -2) and POC (11 to 17 g m -2) concentrations were usually found associated with bays and/or capes within 40 nautical miles of the coast. In contrast, oceanic areas showed low concentrations throughout the study. Small calanoid and cyclopoid copepods represented only a minor fraction of the total crustacean zooplankton carbon (4 to 20%), although they often accounted for a relatively large portion of the total ingestion (26 to 68%) of the crustacean zooplankton community. Euphausiids represented a large fraction of total crustacean zooplankton carbon (28 to 73%), and accounted for between 5 and 61% of total crustacean zooplankton grazing. Ingestion rate as a percentage of body carbon was negatively correlated with animal size, varying between 4% in euphausiids (17 mm) and 123% in small calanoid copepods (0.8 to 1.7 mm). A comparison of estimated dally respiration rates and dally carbon ingestion rates indicated that ingestion of phytoplankton would have exceeded respiratory demands for both large and small calanoid copepods during all 3 sampling periods. In contrast, ingestion of phytoplankton failed to account for the respiratory needs of the euphausiids. This, together with microscopical observations, led to the conclusion that euphausiids utilised other sources of carbon such as detritus, micro- and mesozooplankton in addition to phytoplankton. Crustacean zooplankton showed a significant grazing impact, removing from 10 to 34% of primary production (PP). Salps of the species Salpa fusiformis were present in dense aggregates that could have removed up to 60% of PP during January 1997. On average, the grazing impact of this species was approximately one-half (16%) that of the whole crustacean zooplankton community combined (34%). We did not find any significant difference in zooplankton biomass between January 1997 (non-El Nino) and January 1998 (El Nino), with average biomasses of 24.6 and 21.4 mg dry wt m -3, respectively. There was, however, a shift in the size spectrum of crustacean zooplankton towards small-sized copepods between January 1997 (60 mg C m -2) and January 1998 (186 mg C m -2).
Marine Ecology-progress Series, 2001
Large numbers of gelatinous zooplankton were collected off Mejillones Peninsula, Chile (Humboldt ... more Large numbers of gelatinous zooplankton were collected off Mejillones Peninsula, Chile (Humboldt Current System) in January 1997 during an oceanographic cruise. The area was characterized by the mixing of 3 water masses and the development of coastal upwelling. Siphonophores were the predominant group at most of the stations and the calycophoran Bassia bassensis was overwhelmingly the most abundant species. Five group associations were distinguishable in relation to the water masses identified. Siphonophores were associated with Subtropical Surface Water, the ctenophore Pleurobrachia sp. with Subantarctic Water, the pelagic tunicate Salpa fusiformis with Equatorial Subsurface Water, an assemblage of all gelatinous groups with mixed waters, and a low occurrence of gelatinous groups with upwelled Equatorial Subsurface Water. Molluscs were the group least associated with any water mass. The potential percentage of small copepods removed by B. bassensis ranged between 2.9 and 69.3%. Our results indicate that B. bassensis was the most important secondary predator in the top 50 m of the water column, and could therefore have had a significant trophic impact on the population of small copepods off the Mejillones Peninsula during the sampling period, where small copepods constituted 80.6% of the total mesozooplankton community. This siphonophore potentially ingested an average of 17.3% of the total copepod biomass.
Desde la antropología se ha abordado ampliamente el tema de la muerte. Autores como Marc Augé, Je... more Desde la antropología se ha abordado ampliamente el tema de la muerte. Autores como Marc Augé, Jean Baudrillard, o Philippe Ariès, reflexionan sobre la actual "ausencia" de la presencia de la muerte en nuestras sociedades. También tenemos los estudios del ya clásico Thomas Louis-Vincent donde aborda los distintos tipos de muerte. Dentro de la antropología de nuestro país es de destacar autores como Caro Baroja o Miguel Barandiarán quienes nos sitúan en la primera parte del siglo veinte abordando las costumbres dentro de la cultura vasca en relación al rito funerario. Por su parte, Marcial Gondar, en el contexto cultural gallego, se aproxima al estudio de dos aspectos de la muerte: el aspecto relacionado con el rito y el mundo de su representación mental en el mismo. Si bien son más los autores que trabajan la temática, sólo nombro algunos de ellos. En mi aportación abordaré en el tema de la muerte de forma comparativa a dos culturas: la vasca y la gallega, profundizando en su mundo de representación mental a lo largo de todo el siglo veinte y a nivel intergeneracional. Por ello, voy a presentar en este trabajo, la importancia de las creencias para abordar la situaciones no sólo ya con enfermos terminales sino con la enfermedad en sí misma, debido a que ésta despierta de un modo u otro la alerta de la muerte.
Uploads
Papers by Humberto González