Breeding population size of a fragmented population of a Costa Rican dry forest tree species.

Pollen immigration can offset the effects of genetic drift and inbreeding in small populations. To understand the genetic consequences of forest fragmentation, estimates of pollen flow into remnant fragments are essential. Such estimates are straightforward for plants with singly sired, multiseeded fruits, since the pollen donor genotype for each fruit can be unambiguously reconstructed through full-sib genealogical analyses. Allozyme analyses were used to estimate pollen donor numbers from the progeny of fruits of the tropical dry forest tree Enterolobium cyclocarpum in a small (9.8 ha) fragmented population (N = 11) over three reproductive seasons (1994, 1995, and 1996). These analyses indicate that each tree receives pollen from many pollen donors. When data are pooled for the site, estimated maximum pollen donor pool sizes in all years exceed the number of individuals (56) in the 227 ha study area. Although unidentified pollen donors may be located as close as 250 m to the study trees, the number of unidentified pollen donors indicates that individuals in this forest fragment are part of a large network of reproductively active individuals.     

Relationship of genetically modified crops with the environment and health of the Costa Rican human population

Genetic engineering and the food derived from genetically modified crops (GMCs) have been the center of debate worldwide, as has occurred historically with the advent of new technologies. Questions are derived from the potential impact of GMCs to the environment and the safety of the products to the consumers. In relation to the first inquiry, practice has been oriented to a case-by-case-study, according to the own characteristics of the GMC, in order to minimize its impact in the environment. Scientific studies in diverse latitudes of the world have demonstrated that GMCs in the market showed no adverse effects related to this issue. In relation to food derived from the GMCs, rigorous evaluation protocols have been developed and approved by FAO and WHO to guarantee the innocuousness of these products. Up to the moment, no contraindications for human health have been pointed out for the products that are available today in the market. In the particular case of Costa Rica, the country has established since the 90s a regulatory biosafety framework for the management of the GMCs, safeguarding the biodiversity of the country and the health of consumers. At the same time the country has made significant public and private investments in the field that allowed the country to obtain a leading position in biosafety in the region and genetic engineering research at national research centers. Any attempt to restrict or prohibit these activities in the country, will put in risk the previously described investment, will affect the generation of new knowledge for decision making and the leadership in the field, preventing the benefits derived from this promising technology.     

Observations on the plankton of some Costa Rican lakes

We sampled 30 lakes in Costa Rica in the wet season (July–August) of 1991 for phytoplankton (with integrated and whole water samples), and 17 for zooplankton (with net tows). Taxa of plankton and community richness were poorly related to geography, morphology, chemistry, and other biota. Neither the zooplankton nor the phytoplankton appeared to influence the composition of the other, and neither were apparently influenced by the presence of fish.Phytoplankton richness reflected primarily sampling method, but also tended to decrease with elevation and with Secchi disk depth, and tended to increase with pH and alkalinity. Chlorophytes were the most abundant division in 14 lakes; these lakes tended to be unstratified, turbid, and located at higher elevation. Diatoms were common in 4 of the 7 lakes with elevated silica (over 30 ppm). Each lake showed at least a 3 : 1 dominance by copepods, cladocera, or insect larvae. Copepods dominated 7 of the 17 lakes, most of which were shallow, turbid, and had low alkalinity. Cladocera dominated 7 lakes that were typically deeper and located at low-to mid-elevations. Insect larvae dominated two small, turbid lakes.     

Relationship of upper body fat distribution to serum glucose and lipids in a Costa Rican population

Present models of the relation between subcutaneous fat distribution and serum biochemistries have been based largely on U.S. White populations. To determine interpopulational differences in that relation, we measured 68 clinically normal adult Costa Ricans aged 17-32. Data collected included six skinfolds: triceps, subscapular, suprailiac, umbilical, anterior mid-thigh, and medial calf; height, weight, and four fasting serum parameters: glucose, triglyceride, cholesterol, and high-density lipoprotein (HDL). Correlations between standardized skinfold ratios and biochemistries were highest--on the order of 0.40-0.50--for upper-lower body contrasts to triglyceride and cholesterol in males and to glucose and HDL in females. Canonical correlation analysis, with body mass index partialed out, found significant correlations for the first male variate and the first two female variates. The first male variate was positively weighted on subscapular fatness and on triglyceride and cholesterol, respectively. The two female skinfold variates were positively weighted on subscapular and on outer limbs, respectively, while their corresponding biochemical variates were weighted on glucose and triglyceride and on cholesterol and HDL, respectively. These findings are generally consistent with those based on U.S. populations but suggest that in non-Anglo populations, upper trunk fatness may be more relevant than anterior waist fatness to biochemical dysfunction.     

Spiroplasma species in the Costa Rican highlands: implications for biogeography and biodiversity

More than 1,000 Spiroplasma isolates have been obtained from horse flies and deer flies (Diptera:Tabanidae) in the United States and Canada. However, the spiroplasma biota of Central America is poorly known. In August of 1995 and 1998, 13 isolates were obtained in 14 attempts from horse flies of a single species, Poeciloderas quadripunctatus, taken in the Costa Rican highlands (1,100–2,000 m). The majority of the “isolates” proved to be mixtures of two or more Spiroplasma species, but after filter cloning, single strains emerged that were designated as representatives of the 13 accessions. Six distinct spiroplasma serogroups were identified from these isolations. Three of the strains are putative new species with no serological relationship to any other Spiroplasma species. A fourth strain is a putative new species that may be distantly related to S. helicoides, a southeastern U.S. species. These four strains are accorded herein status as representatives of new serogroups: strain BARC 4886 (group XXXV); strain BARC 4900 (group XXXVI); strain BARC 4908 (group XXXVII); and GSU5450 (group XXXVIII). A fifth Spiroplasma species was very closely related to S. lineolae, known previously only from the Georgia (U.S.) coast. The sixth was most closely related to subgroup VIII-3, known from Texas and the southeastern U.S. Discovery of six spiroplasma species in only 13 attempted isolations reflects diversity seldom equaled in southeast Georgia, and never elsewhere in the U.S. These results are consistent with a hypothesis that spiroplasma diversity increases from north (Nova Scotia) to south (Georgia and Costa Rica). The discovery of significant affinity between some spiroplasmas of the southeastern U.S. and the Costa Rican highlands was unexpected, but may reflect a climatically complex Pleistocene history.

Genetics of hereditary motor and sensory neuropathy and the Costa Rican contribution

Hereditary motor and sensory neuropathy (HMSN) or Charcot-Marie-Tooth disease (CMT) is the most common hereditary illness of the peripheral nervous system. The genetics and the physiopathological aspects of the disease clarified until know, are here summarized. More than twenty genes and ten additional loci have been related with HMSN. These findings contribute to understand the metabolism of peripheral nerves and give the basis for molecular diagnostics and future therapy. Several Costa Rican families with CMT have been identified, specially with axonal forms. Two families present mutations in the myelin protein zero gene (IMPZ). In addition, linkage have been found between the disease and locus 19q13.3 in an extended family, and a mutation segregating with the disease is present in a candidate gene of the critical interval. Costa Rica has several advantages for genetical studies, that can contribute importantly in the generation of knowledge in the neurogenetical field.     

Karyotype study of 5 species of Costa Rican snakes of the colubrid family

The karyotypes of five species of colubrid snakes from Costa Rica are as follows: Imantodes cenchoa and Drymobius margaritiferus have a diploid number of 36, with 16 macro- and 20 microchromosomes. The fourth pair is heteromorphic in females of I. cenchoa, with a metacentric Z and a submetacentric W chromosomes. Karyotypes of Erythrolampius bizonus and Leimadophis epinephalus have 28 chromosomes, without a clearcut separation between macro- and microchromosomes. In the case of E. bizomus, the fourth pair contains the sex chromosomes Z and W, both are submetacentric, but the W is smaller. Xenedon rabdocephalus has a diploid number of 34 chromosomes (22 macro- and 12 microchromosomes); pair 3 is heteromorphic in females, with a submetacentric Z and a smaller metacentric W. The karyotype of X. rabdocephalus may be derived from a primitive karyotype by means of reduction in the number of microchromosomes and centric fissions of two pairs of metacentric autosomes.     

Farmers of the Golden Bean: Costa Rican Households and the Global Coffee Economy

Farmers of the Golden Bean: Costa Rican Households and the Global Coffee Economy. Deborah Sick. Dekalb: Northern Illinois University Press, 1999. 169 pp.     

Long-term comparison of the fish community in a Costa Rican rocky shore marine reserve

Despite their role in supporting diverse marine fish communities, tropical rocky shores and reefs have attracted less research and fewer targeted conservation efforts compared to coral reefs. We studied fish community composition in Playa Blanca Marine Reserve (9 degrees 40' N - 84 degrees 40' W), a rocky shore site on the central Pacific coast of Costa Rica. We conducted visual surveys of fishes along six strip transects soon after the area was designated a marine reserve in 1995, then again in 2006 following an eleven-year period of complete protection. We recorded a total of 31 406 sightings of 72 species from 30 families. Pomacentrids (42.5%), labrids (16.6%) and haemulids (14.8%) dominated the community, accounting for > 70% of total fish abundance. In comparison to other sites in the region, the fish community was more similar to one reported from Bahia Honda, Panama (7 degrees 50' N - 81 degrees 35 W) than from the geographically more proximate Culebra Bay, Costa Rica (10 degrees 45' N - 85 degrees 43 W). Sixty-one species from 26 families were recorded in 1995; sixty-nine species from 28 families in 2006. Our results suggest that the Playa Blanca Marine Reserve is fulfilling its conservation role. Average fish abundance, species richness and Shannon's index of community diversity were greater in 2006 than 1995, and fish community composition varied significantly within each transect among years. Much of the change in community composition among years resulted from spatial and temporal variation in the abundance of a few dominant species, including Abudefduf troschelli, Thalassoma lucasanum, Chromis atrilobata, and Stegastes flavilatus/acapulcoensis. Of the 48 species/species groups recorded in both years, 37 (77%) were more abundant in 2006 than 1995, and several species recorded as uncommon or rare in 1995 were more frequent and abundant in 2006. Fish community composition and the abundance of some species changed in the reserve over time, but further study is needed to determine the role of small-scale marine reserves in the conservation of tropical marine biodiversity.     

Variability at 15 autosomal microsatellite DNA loci in Russian population

The paper presents allele frequencies at 15 STR loci (D3S1358, vWA, FGA, TH01, TPOX, CSFIPO, D5S818, D13S317, D7S820, D16S539, D2Sl338, D8S1179, D21S1l, D18S51, D19S433), used in forensic medicine, in Russian sample (n = 176) representing population of the European part of the Russian Federation. The combined power of discrimination (PD) and the combined power of exclusion (PE) for the 15 STR loci were 0.999 999 999 999 999 986 and 0.999 999 331 310 171 000, respectively. The data obtained for allele and genotype frequencies conformed to Hardy-Weinberg expectations. According to the presented data, loci D2S1338, D18S51, D21Sll and FGA are the most informative markers for Russians. The data obtained may be used as reference database for forensic medicine laboratories in Russian Federation.     

Polymorphisms at VNTR loci suggest homogeneity of the white population of Utah

Apparent departure from equilibrium of genetic parameters measured for multiallelic single-locus markers such as VNTR (variable number of tandem repeat) loci has been suggested as evidence of underlying heterogeneity of the tested population. Using allele frequency distributions at eight VNTR loci from the white population of Utah, we show that the observed number of alleles and the gene diversity at each locus are congruent according to expectations of the neutral mutation model. This demonstrates the genetic homogeneity of the white population of Utah with reference to the allele (total and rare) frequency distribution at eight VNTR loci. The importance of such procedures is discussed in the context of using VNTR polymorphism data for forensic and medicolegal applications. Recommendations for reporting population data for hypervariable loci are also made to aid potential users in conducting similar analyses.     

Microclimatic parameters influencing nitrogen fixation in the phyllosphere in a Costa Rican premontane rain forest

The acetylene reduction method was used to measure nitrogen fixation in the phyllosphere of attached leaves of different phorophytes under natural conditions in a premontane rain forest in Costa Rica. Maximum rates of nitrogen fixation (26 ng N · cm⁻² leaf area · h⁻¹) – mainly due to the activity of two species of Scytonema (Cyanobacteria) – were measured in the rainy season in bright sunlight. Rates of nitrogen fixation were correlated with the leaf area covered by Scytonema. In periods without precipitation the fixation activity decreased to zero within 2–3 days. As long as the epiphylls were sufficiently supplied with water, other microclimatic factors like temperature and light intensity also influenced nitrogen fixation rates, but to a lesser extent. Relative humidity and species of phorophyte showed no direct influence. It was concluded that the most important factor for nitrogen fixation in the phyllosphere was the availability of liquid water. Linking these results to meteorological data, the input of nitrogen by biological nitrogen fixation in the phyllosphere in the investigation area was estimated to be as much as 1.6 ± 0.8 kg N · ha⁻¹ · year⁻¹ per unit of leaf area index (LAI). For an LAI of 2 for the understory the nitrogen input would vary between 2 and 5 kg N · ha⁻¹ · year⁻¹. This work also demonstrates the importance of detailed knowledge of variation in microclimate throughout the year as a basis for extrapolation of the annual nitrogen input. Received: 21 December 1997 / Accepted: 14 June 1998     

A PCR-based method for identification of lactobacilli at the genus level

The zoonotic Listeria monocytogenes is mainly transmitted to humans by the food-borne route. This bacterium was often found in the environment of food processing plants. Therefore the aims of this study were (i) the identification of environmental factors associated with L. monocytogenes contamination on working and non-working surfaces in poultry or pork processing plants and (ii) the understanding of its survival in such environments. The physicochemical risk profiles showed that a surface in resin or plastic, rather than uneven, with organic residues, with a neutral pH, a low temperature and a high hygrometry was associated with L. monocytogenes contamination.     

Genomewide linkage analysis in Costa Rican families implicates chromosome 15q14 as a candidate region for OCD

Obsessive compulsive disorder (OCD) has a complex etiology that encompasses both genetic and environmental factors. However, to date, despite the identification of several promising candidate genes and linkage regions, the genetic causes of OCD are largely unknown. The objective of this study was to conduct linkage studies of childhood-onset OCD, which is thought to have the strongest genetic etiology, in several OCD-affected families from the genetically isolated population of the Central Valley of Costa Rica (CVCR). The authors used parametric and non-parametric approaches to conduct genome-wide linkage analyses using 5,786 single nucleotide repeat polymorphisms (SNPs) in three CVCR families with multiple childhood-onset OCD-affected individuals. We identified areas of suggestive linkage (LOD score ≥ 2) on chromosomes 1p21, 15q14, 16q24, and 17p12. The strongest evidence for linkage was on chromosome 15q14 (LOD = 3.13), identified using parametric linkage analysis with a recessive model, and overlapping a region identified in a prior linkage study using a Caucasian population. Each CVCR family had a haplotype that co-segregated with OCD across a ~7 Mbp interval within this region, which contains 18 identified brain expressed genes, several of which are potentially relevant to OCD. Exonic sequencing of the strongest candidate gene in this region, the ryanodine receptor 3 (RYR3), identified several genetic variants of potential interest, although none co-segregated with OCD in all three families. These findings provide evidence that chromosome 15q14 is linked to OCD in families from the CVCR, and supports previous findings to suggest that this region may contain one or more OCD susceptibility loci.     

Pollen dispersal and genetic structure of the tropical tree Dipteryx panamensis in a fragmented Costa Rican landscape

In the face of widespread deforestation, the conservation of rainforest trees relies increasingly on their ability to maintain reproductive processes in fragmented landscapes. Here, we analysed nine microsatellite loci for 218 adults and 325 progeny of the tree Dipteryx panamensis in Costa Rica. Pollen dispersal distances, genetic diversity, genetic structure and spatial autocorrelation were determined for populations in four habitats: continuous forest, forest fragments, pastures adjacent to fragments and isolated pastures. We predicted longer but less frequent pollen movements among increasingly isolated trees. This pattern would lead to lower outcrossing rates for pasture trees, as well as lower genetic diversity and increased structure and spatial autocorrelation among their progeny. Results generally followed these expectations, with the shortest pollen dispersal among continuous forest trees (240 m), moderate distances for fragment (343 m) and adjacent pasture (317 m) populations, and distances of up to 2.3 km in isolated pastures (mean: 557 m). Variance around pollen dispersal estimates also increased with fragmentation, suggesting altered pollination conditions. Outcrossing rates were lower for pasture trees and we found greater spatial autocorrelation and genetic structure among their progeny, as well as a trend towards lower heterozygosity. Paternal reproductive dominance, the pollen contributions from individual fathers, did not vary among habitats, but we did document asymmetric pollen flow between pasture and adjacent fragment populations. We conclude that long-distance pollen dispersal helps maintain gene flow for D. panamensis in this fragmented landscape, but pasture and isolated pasture populations are still at risk of long-term genetic erosion.     

Polymorphism of trinucleotide repeats at loci FRAXA and FRAXE in the population of Tomsk

Polymorphism of CGG and GCC trinucleotide repeats, whose expansions at the FRAXA and FRAXE loci have been identified as causative mutations in two forms of mental retardation, was studied in Slavic population of Tomsk. At the FRAXA locus a total of 31 allelic variants ranging from 8 to 56 copies of CGG repeat with two modal classes of 28-29 and 18-20 repeat units (with the frequencies of 24.6 and 11.5% respectively) were revealed. Compared to other populations, this locus was characterized by unusually high frequency of intermediate alleles with the sizes of more than 40 CGG repeat units (12.4%). Since intermediate repeats of the FRAXA locus were more prone to instability than normal alleles, it was suggested that Slavic population of Siberia had higher risk of the development of FMR1 dynamic mutations, giving rise to the Martin-Bell syndrome. The FRAXE allele frequency distribution was demonstrated to be normal with 18 allelic variants ranging from 9 to 27 GCC repeat units. In the population of Tomsk this locus had higher than in other populations frequency (26.7%) of short (less than 15 repeat units in size) alleles. In addition, in the Tomsk population both loci were characterized by high level of heterozygosity and low frequencies of modal allele classes. These results can be explained by the high level of outbreeding typical of the population of Siberia.