Revista de Biologia Tropical

In a bacteriological study on samples of bivalves, mud and surface waters from the Gulf of Nicoya, Costa Rica, 18 strains of non-01 Vibrio cholerae and 50 of V. mimicus were isolated. The samples were enriched in alkaline peptone water, and streaked on MacConkey and inositol-brilliant green bile agars. Biochemical and serological tests were used for their identification. Both species were isolated from all sampling sites (Lepanto, Jicaral and Puntarenas) with either of the two agar media, even though these were not specific for vibrios.

Brassavola inhabits a wide altitude range and habitat types from Northern Mexico to Northern Argentina. Classification schemes in plants have normally used vegetative and floral characters, but when species are very similar, as in this genus, conflicts arise in species delimitation, and alternative methods should be applied. In this study we explored the taxonomic and phylogenetic value of the anatomical structure of leaves in Brassavola; as ingroup, seven species of Brassavola were considered, and as an outgroup Guarianthe skinneri, Laelia anceps, Rhyncholaelia digbyana and Rhyncholaelia glauca were evaluated. Leaf anatomical characters were studied in freehand cross sections of the middle portion with a light microscope. Ten vegetative anatomical characters were selected and coded for the phylogenetic analysis. Phylogenetic reconstruction was carried out under maximum parsimony using the program NONA through WinClada. Overall, Brassavola species reveal a wide variety of anatomical characters, many of them associated with xeromorphic plants: thick cuticle, hypodermis and cells of the mesophyll with spiral thickenings in the secondary wall. Moreover, mesophyll is either homogeneous or heterogeneous, often with extravascular bundles of fibers near the epidermis at both terete and flat leaves. All vascular bundles are collateral, arranged in more than one row in the mesophyll. The phylogenetic analysis did not resolve internal relationships of the genus; we obtained a polytomy, indicating that the anatomical characters by themselves have little phylogenetic value in Brassavola. We concluded that few anatomical characters are phylogenetically important; however, they would provide more support to elucidate the phylogenetic relantionships in the Orchidaceae and other plant groups if they are used in conjunction with morphological and/or molecular characters.

Bacteria from several groups of marine organisms were isolated and, using direct antibiograms, identified those that produce antibacterial substances, using a human pathogenic strain of Staphylococcus aureus ATCC6538 as revealing microorganism. Bacteria which produce substances that inhibited S. aureus growth were identified through morphological, physiological and biochemical tests. Out of 290 bacteria, 54 (18.6%) inhibited the growth of S. aureus, but only 27 survived for identification. Bivalves, sponges and corals were the most represented from which 41.2, 33.3 and 29.7%, respectively, produced antibacterial substances of the isolated bacteria in each group. The marine species with highest proportions of these bacteria were the hard coral Madracis decactis (62.5%), the sponges Cliona sp. (57.1%) and the octocoral Plexaura flexuosa (50.0%). Out of the 27 strains that produced antibacterial substances, 51.8% were Aeromonas spp. and 14.8% Vibrio spp. Marine bacteria that produce antibacterial substances are abundant, most belong in the Vibrionacea group and were isolated mainly from corals and bivalve mollusks.

A survey was conducted in 30 fields located at three different altitudes in Cartago, Costa Rica's main potato producing area. Twenty plants were sampled per farm, for a total of 600 samples with 200 samples per altitude. ELISA was used with commercial reagents to independently test for PVX, PVY, PVM, PVA, PVS, PLRV, PMTV, PAMV, PVV, PVT, APLV, APMoV and TRSV. The presence of the following viruses was determined: PVX (77 %), PAMV (62 %), PLRV (42 %), TRSV (42 %), PVT (39 %), PVV (37 %), PMTV (31%), PVY (30 %), PVS (19 %), PVM (13 %), PVA (8 %), and APMoV (8%). APLV was not detected in any sample. This is the first report in Costa Rica of the presence of the viruses PMTV, PAMV, PVV, PVT and APMoV. A high viral incidence in the tuber seed production area as well as a high rate of mixed infections is reported.

Among soil microorganisms, Actinomycetes play an important role in the sustainability of natural and agricultural systems: decomposition of organic matter; degradation of recalcitrant compounds like lignin; nitrogen fixation; degradation of agricultural chemicals and biological control in plants and animals. We evaluated their diversity in soils under three different vegetation covers (pasture, tropical primary forest and stubble) at two depths in the Southern Colombian Amazon border. We collected five replicates per vegetation type (in each, three samples at 0-20cm and three at 20-30cm; for a total of 30 samples). Abundance and phenotypic diversity were determined by plate counting. Genomic DNA was extracted from the isolates: the 16s rDNA gene was amplified with specific primers, and its genetic diversity was estimated by means of an amplified restriction analysis (ARDRA). Actynomicetes abundance varied with vegetation and depth, possibly reflecting presence of earthworms, macro-fauna and physico-chemical characteristics associated to fertility, as well as organic matter, total bases, and optimal capacity to cationic interchange. Primary forests had the highest diversity. Sixteen morpho-types (six genera) were identified; Streptomyces was the most abundant everywhere. The heterogeneity ofARDRA patterns prevented species identification because of the intra-species variability in sequences of 16s rDNA operons. This community is a biological indicator of landscape alteration and could include new bio-active compounds of pharmaceutical interest.

Recent reports indicate that populations of the black sea urchin Diadema antillarum are slowly coming back in several localities in the Caribbean after 15 years of absence. In La Parguera, Puerto Rico, urchins were totally absent from reef localities until 1996, when isolated, medium size individuals were observed in shallow reef habitats. To assess the status (distribution, densities and size structure) of populations of D. antillarum 17 years after the die-off, twelve 20 m2 (10 x 2 m) band transects in each of four depth interval (0-3, 3-7, 7-11 and >11 m) in each of four fringing coral reefs, and six-eight band-transects in each of two depth intervals (0-3 and >3 m) in three lagoonal mounds were surveyed in 2001. All urchins present in the band transects in two depth intervals (0-3 and 3-8 m) were collected and measured (test diameter) in situ to determine the average size and size (age) structure of populations. Overall, average densities were low and not significantly different (F = 1.29, p = 0.125) across reef sites (0.83-1.39 ind/m2) and the seagrass mounds (1.09 +/- 0.6-1.30 +/- 0.6 ind/m2). Urchins were only found in the shallow areas (<3 m) on the seagrass mounds where they formed tight aggregations during daytime. Densities decreased significantly with increasing depth (r2 = -0.60) in reef sites and were significantly higher (F = 5.97, p < 0.001) in shallow reef platforms (0.89 +/- 0.69 - 1.98 +/- 0.65 ind/m2) (0-3 m), and the upper fore-reef (0.56 +/- 0.14 - 2.33 +/- 1.1 ind/m2) habitats (3-7m), compared to deeper (> 7 m) habitats (0.01 +/- 0.02 - 0.88 +/- 1.06 ind/m2). Enrique reef had a significantly higher (K-W, H = 165.19, p < 0.001) population average size (Median = 7.7) compared to all other sites. Populations in the sea grass mounds were dominated by midsize to large individuals. Within reefs, the average size did not vary significantly across depth intervals with medium to large size urchins dominating. Higher number of aggregations and higher number of urchins per aggregation were correlated with low complexity (rugosity) habitats (Pearson's r = -0.772, p < 0.001 and r = -0.778, p < 0.001 respectively), which supports the idea that this behavior provides protection. Although average densities were well below pre-mass-mortality densities in Puerto Rico, results of this study indicate that Diadema seem to be making a slow come back in La Parguera.

The STR (AAAAT)n within intron 1 of the TP53 locus was screened in 17 populations from 3 main ethnic groups: Europeans, Asiatics, and Africans, and from the hybrid population of Costa Rica (1968 samples). Three alleles, 126/7 (bp/copies of the repeat), 131/8 and 136/9 were the most prevalent in all populations. Other alleles rarely reached frequencies of 10% or higher. Observed heterozygosities ranged between 0.351 and 0.829. Patterns of diversity fit well with both the geographic origin of the samples and the history of the populations screened. A statistical test suggests that single-step mutational events have been the main mechanism producing new alleles at this locus. Fixation indexes (R(ST)) for this marker showed an effect of population subdivision on divergence only within the Asiatic group; they were insensitive at the level of major ethnic groups as well as within Africans and within Europeans.

Cecal microorganisms of mice were categorized and enumerated weekly during the developmental cycle of infection with the whipworm, Trichuris muris. The cecal bacterial population consisted of Escherichia coli, Proteus spp, Acinetobacter lwoffi (Mima polymorpha), aerobic lactobacilli, staphylococci, enterococci, and anaerobes (bacteroides, streptococci, and lactobacilli) in control and T. muris-infected mice. The aerobic lactobacilli and the anaerobes constituted the greatest number of organisms in both groups. In week three there was a decrease in the number of these organisms, and in week four fewer of these and of all other organisms in the worm-infected mice when compared to controls. The most significantly reduced bacterial counts were observed during the period of T. muris self-cure.

Plasma concentration of progesterone and 17beta-estradiol of black-rumped agouti (Dasyprocta prymnolopha) during the estrous cycle. The agouti is a game animal that have been raised in captivity for conservation and sustainability purposes. However, the management of wild animals in an intensive breeding system requires an assertive knowledge of its reproductive parameters, one of the most important features for production improvement. Besides, little information is available regarding changes in reproductive hormone profiles in agouti. The objective of this study was to evaluate the hormonal profile of progesterone and 17beta-estradiol during the estrous cycle of the agouti (Dasyprocta prymnolopha). The hormones were analyzed by radioimmunoassay. Blood samples were collected without sedation twice a week. The concentrations of progesterone were as follows: proestrus 0.78 +/- 0.39 ng/ml, estrus 2.83 +/- 2.34 ng/ml, metestrus 1.49 +/- 1.24 ng/ml, diestrus 3.71 +/- 1.48 ng/ml. In the estrous phase, an increase in the progesterone level was observed during a period of 24h. The average 17 beta-estradiol levels were as follows: proestrus 2 030.98 +/- 961.00 pg/ml, estrus 1 910.56 +/- 650.54 pg/ml, metestrus 1 724.83 +/- 767.28 pg/ml, diestrus 1 939.94 +/- 725.29 pg/ml. The current results suggest that the progesterone plasma concentration during the estrous cycle in the agouti has a similar increasing, stabilizing and decreasing pattern, as in domestic mammals. Agoutis have two phases of follicular development, as two periods of 17beta-estradiol peaks were observed, the first one in the metestrus and the second during the proestrus. Spontaneous ovulation seems to occur after the progesterone peak, possibly indicating that this hormone is associated with the ovulatory process. A more detailed investigation is needed for better understanding of how progesterone influences ovulation. Studies on the involvement of progesterone in follicular rupture can be carried out, using steroid biosynthesis inhibitors and observing the effect of this hormone on ovarian activity of proteolytic enzymes in the follicular wall.

Tylosurus pacificus (Steindachner, 1876) is confirmed to have full species rank based on: 1) sympatry with T. acus melanotus at Isla Gorgona and in Panamá; 2) level of morphological differentiation in numbers of vertebrae, dorsal and anal fin rays; and 3) level of mtDNA differentiation. The eastern Pacific agujon needlefish is found from the Gulf of California, Mexico, to Peru, including the Galápagos Islands.

A study of consanguinity and population structure was carried out in a sample of 498 consanguineous (MC) and 570 non-consanguineous matings (MNC) in the Parrish of Dota, Costa Rica, during a period of 75 years. The inbreeding coefficient (F) shows fluctuations in time (476 to 194 x 10(-5) with an increase from 1888 to 1917, followed by a decrease in the last years but remains high in nonmigrant marriages. There is a high frequency of unions among second cousins. The endogamy percentage is high, greater in MC (80%) than in MNC (61%). Exogamy tends to diminish with time among both types of union. Effects of age distributions in the groups was not found. Marital and migrational distances are short and tend to become shorter in the final periods. There is a positive correlation (r = 0.71; p less than 0.05) between these distances in MC but not in MNC; distances are shorter in MC. Immigration is minimal and reduced to short distances. Post-marital movement is intense (37%) and involves greater distances. Emigratory behavior is identical in MC and MNC.

Tagosodes orizicolus Muir (Homoptera: Delphacidae), the endemic delphacid species of tropical America carries yeast-like symbiotes (YLS) in the abdominal fat bodies and the ovarial tissues, like other rice planthoppers of Asia. These YLS are obligate symbiotes, which are transmitted transovarially, and maintain a mutualistic relationship with the insect host. This characteristic has made in vitro culture and classification of YLS rather difficult using conventional methods. Nevertheless, microorganisms of similar characteristics have been successfully classified by using molecular taxonomy. In the present work, the YLS of Tagosodes orizicolus (YLSTo) were purified on Percoll gradients, and specific segments of 18S rDNA were amplified by PCR, cloned and sequenced. Sequences were aligned by means of the CLUSTAL V (DNASTAR) program; phylogenetic trees were constructed with the Phylogeny Inference Package (PHYLIP), showing that YLSTo belong to the fungi class Pyrenomycetes, phylum Ascomycota. Similarities between 98% and 100% were observed among YLS of the rice delphacids Tagosodes orizicolus, Nilaparvata lugens, Laodelphax striatellus and Sogatella fur cifera, and between 89.8% and 90.8% when comparing the above to YLS of the aphid Hamiltonaphis styraci. These comparisons revealed that delphacid YLS are a highly conserved monophyletic group within the Pyrenomycetes and are closely related to Hypomyces chrysospermus.

Two laboratory maintenance systems of Trypanosoma rangeli were compared. The maintenance by weekly subinoculations in Tobie's culture medium and the intrafemoral inoculation of Rhodnius prolixus with cultured flagellates, resulted in loss of infectivity of the metacyclic salivarian trypomastigotes for mice, ten months after maintenance in culture. With the system of cyclical passes through culture-Rhodnius-mouse-culture-Rhodnius, the infectivity of the metacyclic trypomastigotes for mice, was maintained during the three years of the experiment. The number and percentage of metacyclic trypomastigotes formed in the salivary glands of R. prolixus, previously inoculated intrafemorally or intracoelomically with culture forms of T. rangeli, did not show correlation with the inoculated dose, however the inoculated quantity demonstrated a direct relation with the mortality rate of the insects. The results indicate that T. rangeli requires an adequate maintenance system, so that under experimental condition the biological characteristics, normally expressed under natural conditions, are conserved.

The name Albula nemoptera (Fowler, 1911) is currently applied to the Shafted, or Threadfin, Bonefish (Albuliformes: Albulidae) inhabiting the tropical coastal waters of both the western Atlantic and eastern Pacific. In the present paper I provide a brief review of the taxonomy and nomenclature of A. nemoptera, and argue that the available morphological, biogeographical and molecular evidence supports resurrecting the name A. pacifica (Beebe, 1942) for the population ofA. nemoptera from the eastern Pacific.

The spreading of knowledge depends on the access to the information and its immediate use. Models are useful to explain specific phenomena. The scientific community accepts some models in Biology after a period of time, once it has evidence to support it. The model of the structure and function of the DNA proposed by Watson & Crick (1953) was not the exception, since a few years later the DNA model was finally accepted. In Costa Rica, DNA function was first mentioned in 1970, in the magazine Biologia Tropical (Tropical Biology Magazine), more than 15 years after its first publication in a scientific journal. An opposite situation occurs with technical innovations. If the efficiency of a new scientific technique is proved in a compelling way, then the acceptance by the community comes swiftly. This was the case of the polymerase chain reaction, or PCR. The first PCR machine in Costa Rica arrived in 1991, only three years after its publication.