Application of Anderson sampler in studying airborne fungi in San Antonio,Texas

Some metabolites produced by fungi have been known to cause certain toxic effects to animals. With an attempt to elucidate the mode of action of the pigments in fungal mycelia, we performed a preliminary feeding-test usingMicrosporon cookei with exceptional pigment production and observed the pathological changes in some organs.     

Metazoan parasite communities of sentinel bluegill caged in two urbanizing streams, San Antonio, Texas

Urbanization has deleterious effects on water quality and biota in stream systems. This project used caged bluegill (Lepomis macrochirus) to assess metazoan fish parasite communities in 2 urbanizing streams of the upper San Antonio River Basin, Bexar County, Texas. Field studies on Leon and Salado creeks were conducted during late summer in 1999 and 2000. Juvenile bluegill, obtained from a local aquaculturist, were held in cages for 10-22 days at middle and lower watershed sites to expose them to in-stream conditions and to allow parasite communities to establish. After removal from cages, fish were examined for metazoan parasites. In 2000, wild Lepomis spp. also were collected at study sites for parasite assessment. In both years, physical and chemical water properties were monitored at each site. Of the 120 fish examined for parasites, 96.7% were infected by at least 1 organism from among the 11 parasitic taxa observed. For caged fish, both diversity and equitability of parasite communities tended to be lower at the more eutrophic downstream sites; accordingly, parasite diversity and equitability were inversely correlated with nitrate concentrations. Ectoparasites were more prevalent in caged fish and endoparasites were more abundant in wild fish. An Ergasilus sp. copepod and a Posthodiplostomum sp. trematode dominated the ecto- and endoparasite faunas, respectively. This study suggests that assessment of watershed health can benefit from comparative cage studies of parasite community development involving sentinel fish species.     

Social class,admixture, and skin color variation in Mexican-Americans and Anglo-Americans living in San Antonio,Texas

Social class may act in different ways as a barrier to gene flow in urban populations, depending on ethnicity. We test the hypothesis that biological variation is affected by social class subdivision using skin reflectance data collected for 393 Anglo-American and 930 Mexican-American adults in the major urban population of San Antonio, Texas. Two socioeconomic groups were sampled for the Anglo-American population: a middle-income transitional group and a high-income suburban group. In addition, we sampled a third socioeconomic group for Mexican-Americans: a low income barrio. Sex and age effects on skin color are minimal. Social class has no effect on skin color variation for Anglo-Americans, whereas there is a highly significant effect on social class subdivision for Mexican-Americans. Admixture estimates were derived from skin reflectance data and show that the proportion of native American ancestry decreases as social class increases.     

A methodological note on the relationship between infant mortality and socioeconomic status with evidence from San Antonio, Texas.

A number of previous studies have concluded from social area analyses of medium-size cities that there is no longer a significant correlation between socioeconomic status (SES) and infant mortality in the U.S. To determine if these findings were an artifact of too small samples, the total, neonatal, and postneonatal infant mortality rates were analyzed for 115 census tracts of San Antonio, Texas. The SES of each tract was measured by a score reflecting equally the variables of income, education, and occupation, and allowed assignment of the tracts to 1 of 4 socioeconomic rankings. All 3 infant mortality rates rose as SES decreased, with the most marked relationship being between SES and postneonatal rates. It was also found that of the 3 variables used to measure SES, income bore the strongest relationship to infant mortality. In general it should be noted that social area analysis of infant mortality is limited by the extreme reductions of sample size when additional variables are induced.     

On simulation of air temperature curve near the ground in presence of frosts in Valley of Perote (Mexico)

An exponential of the time function was used in order to model the air temperature curve near the ground after frost in the Valley of Perote (Mexico). From January to March 1989 air temperature was recorded with a telethermograph, and data from 22 frosts were used to adjust and evaluate the exponential function.     

The genetics of obesity in Mexican Americans: the evidence from genome scanning efforts in the San Antonio family heart study

Recent estimates indicate that approximately 18% of the population in the United States can be considered obese (defined as a body mass index [BMI] > or = 30), and this rate is even higher among ethnic populations such as Mexican Americans. This figure becomes very significant given the strong evidence for obesity as a major risk factor for a variety of chronic diseases including type 2 diabetes mellitus and coronary heart disease. The search for genes involved in the expression of obesity has been one of the focal points of the San Antonio Family Heart Study (SAFHS), a large, family-based study to examine the genetics of risk for atherosclerosis in Mexican Americans. To date, our genome scanning effort has reported two quantitative trait loci (QTLs) with pronounced effects on the expression of a variety of obesity--related phenotypes (e.g., leptin levels, fat mass, and BMI) located on chromosomes 2 and 8. We are currently working to further refine these signals and to identify the genes and allelic variants involved. Here, we summarize the latest results from our ongoing efforts to identify obesity genes in the San Antonio Family Heart Study.