Showing papers by "University of Costa Rica published in 1980"

Estudio comparativo de venenos de ejemplares recién nacidos y adultos de Bothrops asper

Abstract: This paper is a comparative study of venoms of newborn and adult specimens of Bothrops asper from two Costa Rican populations: San Carlos, in the Atlantic versant and Puriscal in the Pacifico Comparison was on a basis of determination of the following effects: hemorrhage, myonecrosis, edema, proteolysis, hemolysis, and lethality, as well as neutralization of the lethal effect by polyvalent antivenom. Biochemical and immunochemical comparisons were done by mean s of electrophoresis, immunoelectrophoresis, and immunodiffusion. There are marked differences between newborn and adult venoms from both regions in electrophoretic and immunoelectrophoretic patterns, although the immunodiffusion plates showed an almost identical pattern. Venoms from newborn specimens are more proteolytic, hemorrhagic, edema-forming and lethal, whereas those of adult specimens are more hemolytic and induce a stronger myonecrotic action, characterized by a myolitic type of necrosis. Antivenom neutralizes the lethality of all venoms with similar ED50.Venoms of adult specimens from both regions showed a slight variation in the immunoelectrophoretic pattern, but a complete identity in immunodiffusion plates. Adult venoms from San Carlos are more hemorrhagic, and myonecrotic, whereas those of Puriscal are more proteolytic, having similar lethality, edema-forming activity, and hemolytic effect. The same differences were observed when venoms from newborn specimens from both populations were compared.

Polinizacion en bactris gasipaes h. B. K. (palmae)

Abstract: A study on pollination of the pejibaye palm (Bactris gasipaes H.B .K.) was carried out in Costa Rica at two localities with different·ecological conditions (San Isidro de El General and Guapiles) during two flowering seasons (1976-1977 and 1977-1978). In San Isidro de El General the flowering peak comes in February during the dry season and in Guapiles it takes; place in July under steady rains. These climatic differences alter to a certain degree the importance of insect and wind pollination as described below.This monoecius palm bears both pistilate and staminate flowers; in the same inflorescence. It has a pollination cycle of three days. Female anthesis coincides with the opening of the bract at approximately 5:30 p.m. on the first day of the cycle. These pistilate flowers retain some degree of fertility up to when male anthesis occurs 24 hours later. This completes the second day of the cycle. Some of the pollen released at the time of male anthesis remains on the rachillae of the inflorescence until the following morning, i.e., the third day of the cycle, when it is sufficiently dried to be carried away by the wind. There are three agents responsible for pollination in pejibaye: insects, wind and gravity.Pollination by the curculionid Derelomus palmarum Champ. is the most important. These insects arrive at a freshly opened inflorescence carrying pollen from one more mature that is undergoing male anthesis. Several aspects of insect pollination indicate a certain degree of specialized coevolution between Derelomus and Bactris. Wind as a pollination agent is less effective, however, because of the random distribution of the pollen and its rapidly diminishing concentration within a short distance. Wind is essentially the only agent which transmits the pollen present on the rachillae on the morning of the third day of the cycle. Both of these types of pollination favor exogamy, but some geitonogamy will also occur.Pollination by gravity takes place during male anthesis on the second day, favoring endogamy. Its effectiveness however, is greatly reduced by two factors: one, the prior exposure of the female flowers to pollen from insects and wind and, second, to the presence of a genetic self incompatibility system.The cromosome number (2n=28) and the germination of pollen on a 5% glucose solution are reported.

The Analgesic and Hypothermic Effects of Nefopam, Morphine, Aspirin, Diphenhydramine, and Placebo

Abstract: One hundred and ninety-six hospitalized patients were randomly assigned to one of eight treatment groups consisting of oral or intramuscular analgesics and placebo. Patients were monitored for 6 hours for pain relief, vital signs, and side effects. No statistically significant differences in pain intensity or relief were seen for nefopam (Acupan), diphenhydramine (Benadryl), aspirin, or placebo despite a numerically higher score for nefopam. This is attributed to an unexpectantly high placebo response. Significant pain relief and reduction of pain intensity were seen with both parenteral nefopam and morphine. Side effect incidence, in general, paralleled analgesic efficacy and was higher in patients receiving parenteral drugs. An early hypothermic effect was noted with oral and parenteral nefopam, aspirin, and morphine. Lower temperatures persisted to a statistically significant degree only in nefopam-treated patients.

The dependence of crude papain yields on different collection ('tapping') procedures for papaya latex.

Abstract: The yields of fresh papaya latex, dry latex (crude papain) and proteolytic activity were studied with respect to fruit age (1.5–3 months); sex of the tree (those which produce fruit: female and hermaphrodite); time (5:30 a.m.-2:00 p.m.) of latex collection; pattern and frequency of fruit incisions. The yields from 250 randomly selected trees (750 fruits) were investigated under these different conditions. Yields of fresh latex are frequently unreliable guides to yields of proteolytic activity. In contrast to the literature recommendations, the yields of crude papain from female and hermaphrodite trees and during different periods of the day were similar. The proteolytic activity differs significantly with time of collection only with hermaphrodite trees. The proteolytic activity of hermaphrodite crude papain is usually less than that from females (under some conditions only 60% of that from females). Yields of crude papain were higher in older fruits (2.5–3 months) from both sexes. The proteolytic activity of the crude papain was highest in the younger fruits (1.5–2 months) from female trees (30% higher than from older fruits); these activity differences with age were not significant with hermaphrodite trees. No significant differences in crude papain yields were encountered using three or six incisions per fruit at weekly intervals. The optimum procedure is to tap 2.5–3-month-old fruit of both sexes with three incisions between dawn and the start of rains in early afternoon, at about 4-day intervals.

Structural differentiation of the meiotic and mitotic chromosomes of the salamander, Ambystoma macrodactylum

Abstract: The lampbrush chromosomes of the long-toed salamander, Ambystoma macrodactylum Baird, have been analysed and a map of the oocyte genome prepared. The location of C-bands and cold-induced-constrictions has been established in mitotic chromosomes and compared with the location of marker structures and chiasmata in several lampbrush bivalents. In the lampbrush chromosomes, C-bands are tentatively correlated with sphere-organizing loci and with regions of low chiasma frequency; cold-induced-constrictions are tentatively correlated with regions of high chiasma frequency. In general, in this salamander, C-bands do not coincide in position with cold-induced-constrictions. We have compared our results with those obtained by Callan (1966) in his investigation of chromosomes of the axolotl, Ambystoma mexicanum, and we present an analysis of the similarities and differences that are visible in the chromosome sets of these two ambystomatid species.

Los líquenes como indicadores de la contaminación atmosférica en el área metropolitana de San José, Costa Rica

Abstract: Lichens were used as air pollution indicators in the metropolitan area of San Jose, Costa Rica. Trasplants showed a positive correlation between the percentage of dead cells in the thallus and the ketone soluble substances deposited on it. Those parts of the city where pollution is greatest (industrial areas and heavy traffic) were also the ones where lichens suffered the most, and in some extreme cases the thallus died after 8 months of exposure. Besides this transplant experiment, the coverage of Parmelia lichens on the bark of several tree species was determined in some areas of the city. The results of these observations suggest that the city of San Jose has three different kinds of air environment in relation to lichen survival: normal, transitional and desertic, as reported for other cities of the world. The most frequent air pollutants in San Jose are: CO, C02 , C2H5OH, Cl2, HCI, H2S, H3PO4, H2CrO4, NO, NH3, NH4 Cl, SO2 and Zn.

Arañas terafósidas de Costa Rica (Araneae: Theraphosidae). III. Sphaerobothria, Aphonopelma, Pterinopelma, Citharacanthus, Crypsidromus y Stichoplastus

Abstract: Thirteen species of theraphosid spiders ("tarantulas") are described as new. Sphaerobothria hoffmani and Aphonopelma seemanni are redescribed and the male of S. seemanni is described for the first time. It is argued that the genera discussed here, which are traditionally placed in separate subfamilies (Grammostolinae and Isehnocolinae) should be grouped. Common features to these genera are the shape of the bulb (distally atenuated and curved ventrally), spermatheea divided in two portions by a deep notch, and coxa I with anterior side covered by conic spinules. The feature formerly used to separate the two groups is not consistent within genera. Keys, diagnosis and explanations to figures are included in an English Appendix.

Rayado Fino Virus Disease of Maize in the American Tropics

Abstract: Diseases are among the most important limiting factors in maize production in the American tropics, and ‘maize (corn) stunt’ has long been recognised as one of the major problems of the crop in this area. For several years the etiology of the disease was poorly understood, and several different symptoms were associated with maize stunt, which is now known to involve viruses and spiroplasmas. Rayado fino (Spanish for fine striping) virus (RFV) is presently recognised as a distinct pathogen within the maize stunt complex and has been shown to be responsible for the rayado fino disease, which is widespread and increasingly important in the American tropics. Symptoms, which are characterised by a fine chlorotic stipple striping of the leaf veins are generally mild, but reductions of yields are frequently appreciable. The cicadellid leafhopper Dalbulus maidis Delong & Wolcott, is the most important vector of the virus in the American tropics, although other species of leafhoppers have been indicated i...

Shoot vascular system and phyllotaxis of casuarina (casuarinaceae)

Abstract: In species of Casuarina with multileaved whorls, each stem vascular bundle divides radially into two at the site of a leaf trace separation, and the same two bundles rejoin acropetally to where the trace supplies a leaf. Such divisions are divisions of a single vascular bundle, and the rejoining of bundles forms a single bundle. Proposals that the extant primary vascular systems of dicotyledons may have been derived as in conifers are incorrect in so far as Casuarina is concerned, or the system has evolved beyond that so far proposed for dicotyledons. Reasons are offered, however, for considering that fernlike leaf gaps are not present. Leaf traces supply leaves at the first nodes distal to their origins. The ways by which an increase or decrease of stem bundles occur are described. Phyllotactic patterns range from helical (rare) to whorled. In the embryo, where leaves occur decussately, of certain species with multileaved whorls, and in the shoot apices of species with tetramerous whorls, slight differences in the levels of leaf attachments and the bending of leaf traces indicate the probable evolution of extant whorled phyllotaxies from one or more helical arrangements. Stages in the evolution are suggested. The leaves in most species with multileaved whorls are in true whorls. The original periderm of branchlets lies internally to the internodal traces and chlorenchyma, but is otherwise external to the vascular system. It is concluded that each leaf originates at its level of separation from the axis despite several structural features suggesting that the leaf bases have become congenitally adnate to the stem. THIS PAPER, originally intended to be the second in a series of three on the developmental vegetative anatomy of Casuarina, has been preceded by the first and third (Flores, 1977, 1978). This paper is partly concerned with the pattern of the primary vascular system of the branchlets and its conformity to the concept proposed by Beck and his associates (Namboodiri and Beck, 1968a,b,c; Beck, 1970; Devadas and Beck, 1971, 1972) and others (Dormer, 1945, 1972; Benzing, 1967a,b; Jensen, 1968) who have demonstrated that the angioI Received for publication 18 May 1979; revision accepted 31 August 1979. This investigation represents a portion of a dissertation submitted for the Ph.D. degree, University of California, Santa Barbara, California 93106. The research was supported by funds from the Department of Biological Sciences, University of California, Santa Barbara, California, and by a grant from the Chancellor's Patent Fund, University of California, Berkeley, California. The author is very grateful to Dr. L. A. S. Johnson, Director and Chief Botanist, Royal Botanic Gardens and National Herbarium, Sydney, Australia, for identifications to species of many of the samples used in this investigation. The author also acknowledges the assistance and suggestions offered by Dr. M. F. Moseley, Jr., and Ms. lelene B. Morrow, University of California, Santa Barbara, California, and Dr. D. R. Kaplan, University of California, Berkeley, California, during the investigation and the preparation of this manuscript. sperms they investigated have sympodial eusteles, or probable derivatives from such, which Namboodiri and Beck (1968c) consider similar to coniferous eusteles derived directly from protosteles without siphonostelic transitional stages. The paper also describes the incompletely evolved whorled vasculatures found in some species, relates the imperfections to the probable evolution of the morphological whorled phyllotaxy, and discusses these observations in the light of the formerly proposed ideas for the derivation of whorled phyllotaxy (Miquel, 1868; Poisson, 1871; Engler, 1892; Groom, 1909; Schoute, 1922, 1925; Jensen, 1968). Finally, the limit of the reduced leaf, long an unresolved problem, is discussed, especially in view of the relative positions of the trace and the periderm described herein. The older concepts that the gamophyllous leaf bases have become adnate to the stem (Loew, 1865; Cordemoy, 1923), or that they had become extended basipetally (Saunders, 1922), or that the leaf vascular supplies, which lie vertically in the cortex for one internode before bending wut to the leaf bases, are cortical bundles (Goppert, 1841; Morini, 1894, 1895) are discussed and found untenable. MATERIALS AND METHODS-The species, the number of samples of each species and the

The storage and drying characteristics of papaya (Carica papaya L.) latex

Abstract: A range of latex storage and air drying conditions were studied with regard to the proteolytic activity of the dried latex (‘crude papain’). The optimum drying temperature is between 50–55°C, activity losses on drying can be restricted to about 7% under these conditions. The activity of crude papain is the same if it is derived either from exuded latex or from that portion (about 20% of latex yield) which coagulates on the fruit surface on tapping. Latex storage at tropical ambient for 2–24 h prior to drying (with or without exposure to sunlight) causes maximum losses of about 20% in the proteolytic activity of the crude papain. Sodium chloride addition has an anti-coagulating effect on latex and accelerates the later stages of drying. Contrary to earlier reports, this causes a decreased activity in the product, which may be related to changes in latex pH. Addition of EDTA or sodium bisulphite, singly or in combination, protects the latex activity (increases of 20–25% relative to controls).

Variations in population structure in the genus tetraclita (crustaceea : cirripedia) between temperate and tropical populations iii. T. Stalactifera in costa rica

Abstract: Studies on the population structure of the cirriped Tetraclita stalactifera were conducted at two localities in Bahia Ballena, Nicoya Peninsula, Costa Rica. The results indicate that reproduction occurs every year. Well-developed gonads are present from April through August, the nauplii being clearly defined in October and November. Release of larvae takes place in late November and early December. As in California, the individuals reproduce the year after they reach sexual maturity. The relative density is fairly constant through the year showing values slightly higher than those observed in northern populations. Mortality is heavy in the youngest size classes. It appears to be extemely low in individuals with a test diameter over 25 mm, in particular because of the lack of large predators.

Perturbative contributions to quark masses

Abstract: The contribution of lowest-order electromagnetic (or weak) corrections to quark masses in quantum chromodynamics is considered. It is found that each contribution to the running mass is calculable from physics well below the grand unified scale, as long as the number of quark flavors n/sub f/ is greater than or equal to eleven. The renormalization-group expression for the running mass is also derived, by use of Dyson's equation for the self-energy of the quark.

Ligiella, A New Genus for the Clathraceae

Abstract: Ligiella rodrigueziana, a new genus and species for the Clathraceae, is described from humus and rotten wood as its natural substrate. The receptacle is formed by five arms, although cross sections...

Two cases of hemoglobin New York in Costa Rica.

Abstract: Hemoglobin New York was first described by Ranney et al. (1) in a Chinese American family. It was also reported in Chinese subjects in Taiwan by Blackwell et al. (2).

Crisis, dependencia y contradiccionesde la psicología enAmérica Latina

Abstract: Resumen en: This paper presents a criticism of psyehology, and social psychology as is eurrently found in the more developed and the least developed countries. The...

Umbrina bussingi , a new sciaenid fish from the tropical eastern Pacific Ocean

Abstract: A new sciaenid fish from moderately deep water is described from the Pacific coast of Costa Rica. Umbrina bussingi is characterized by a relatively large eye, long pectoral fin, a single, laterally compressed mental barbel with an elliptical pore and a low dorsal fin-ray count. In addition, the new species differs from its eastern Pacific congeners in lacking oblique black stripes on the sides. U. bussingi differs from its western Atlantic cognate species U. milliae in its longer pelvic rays, dorsal rays subequal in length and lower dorsal and anal-fin counts.

Consumo de leche por lactantes del area rural de puriscal costa rica 1978

Abstract: articulo (arbitrado), Universidad de Costa Rica, Instituto de Investigaciones en Salud (INISA). 1978

Bionomics of black flies (Diptera: Simuliidae) in Costa Rica. V. Description of Neomesomermis travisi sp. n. (Nematoda: Mermithidae)

Abstract: Neomesomermis travisi sp. n., a mermithid parasite of larvae of Simulium panamense and Simulium melallicum is described from Costa Rica, Central America. This species, the first mermithid described from the Neotropical Region, is very close to Neomesomermis flumenalis Welch, 1962 but can be differentiated by the distinct serrations on the tips of the spicules; those of N. flumenalis being distinctly smooth, and the tail of the female adults more bluntly rounded than in N. flumenalis. Narrow chords, small amphids, bulbous vagina, large eggs in two rows, and the genital structures of the male of N. travisi also differ from those of other, closely allied, Holoarctic species of Neomesomermis. Detailed measurements of taxonomically important structures of different life stages are presented and illustrated.

Estructura y función de los cromosomas plumulados

Abstract: Los cromosomas plumulados aparecen en los ovocitos de muchos organismos durante el diplotene de la meiosis. Cada una de las cromatidas de estos cromosomas consta de una fibra de desoxiribonucleo proteina que a intervalos regulares se arrolla sobre si dando origen a los cromomeros. Por lo general se asocian a cada cromomero dos, o un multiplo de dos asas, producto de una intensa transcripcion. Cada cromomero contiene varios cistrones, en contraste con lo encontrado en cromosomas politenicos de dipteros. Las asas representan unidades de transcripcion donde se copian secuencias repetidas y unicas. Cada cromomero podria constar de una familia de secuencias repetidas o simplemente de secuencias con un contenido similar de bases. Se han planteado varias hipotesis acerca del funcionamiento de los cromosomas plumulados, conocidas como la del "amo-esclavo", las de re programacion y las propuestas recientes de Cavalier-Smith. En esta revision se discuten estas hipotesis y con base en ellas se establecen predicciones que experimentos futuros decidirian cual de ellas explica en forma consistente el papel que juegan los cromosomas plumulados.

Variabilidad geográfica y alozímica en Neritina latissima (Gastropoda: Neritidae) en Costa Rica

Abstract: A phenotypic study of shell color and molecular variation in the loci glucose-6-phosphate dehydrogenase (G-6-PD) and glucosephosphate isomerase (GPO in the estuarine gastropod Neritina latissima in four populations in the Pacific coast of Puntarenas, Costa Rica, confirmed that the variation in frequencies of the different morphs is regulated through predation. There was no apparent effect of climate or any other environmental factor. Eight polymorphic alleles were detected in G -6 -PD and fourteen in GPI with starch gel electrophoresis. In both cases the allelic frequencies differ among populations, but there are unique variants in each. The average heterozygosity (H) per locus and per population is very high, ranging between 0.76 and 0.82 in G-6-PD and 0.78 to 0.87 in GPI. No apparent association was found between the allozirnic variation and the different phenotypes. Possible evolutionary implications on these results are discussed.

La herencia colonial de América Latina

Abstract: Numerosas estructuras que aun se mantienen en America Latina fueron establecidas o condicionadaspor las caracteristicas que revistio la dominacion espanola. Esta tesis de que nuestro retraso se debe en gran parte al proceso de colonizacion que impuso la Corona espanola, es sustentada por multiples historiadores; entre ellos Stanley y Barbara Stein, importantes profesores de la universidad de Princeton , quienes han realizado un amplio e interesante estudio del tema, en su libro la herencia colonial de America Latina. Uno de los objetivos de esta polemica obra es demostrar que el colonialismo perpetro patronesde dependencia externa tanto en la peninsula Iberica, como en sus posesiones de ultramar; patrones que no fueron destruidos en el momento de la independencia.