Showing papers by "University of Los Andes published in 1968"
TL;DR: Since fitness associated with the capacity to retain normality, normal development goes hand inhand with natural selection to establish a gene complex with a type of development most likely to produce an adaptive phenotype, it is speculated that the type of gene control for normal development is probably that of Landauer’s modifiers.
Abstract: Results are presented the induction of phenodeviants with temperature changes during everyday for four generations. The results were compared with the fitness of 3 of studied. From this comparison stems the following conclusion: since fitness associated with the capacity to retain normality, normal development goes hand inhand with natural selection to establish a gene complex with a type of development most likely to produce an adaptive phenotype. The appearance of phenodeviants is a sign that such a complex is getting disrupted either by inbreeding or by hybridization. It is speculated that the type of gene control for normal development is probably that of Landauer’s modifiers, the presence of which ensures normality for the individuals.
51 citations
TL;DR: Comparison of the trypanosome counts from the peripheral blood of mice, maintained at the two temperatures, indicates that a high environmental temperature protects the mice against the virulent effects of thetrypanosomes.
24 citations
TL;DR: During the past 10 yr no arthropod-borne relapsing fevers have been reported from Colombia but there have been several suspicious cases in the department of Santander, where O. rudis is not uncommon8.
Abstract: ALTHOUGH recurrent and relapsing fevers occur in Colombia, the aetiological agents are seldom diagnosed From Colombia only two of the six recognized forms of arthropod-borne relapsing fevers have been reported: epidemic cosmopolitan relapsing fever caused by Borrelia recurrentis (synonyms B obermeiri, B novyi) and transmitted by lice (Pediculus humanus), and the endemic central and South American form of relapsing fever caused by B venezuelensis (synonym B neotropicalis) transmitted in nature to man, monkeys and marsupials by the soft ticks (Ornithodorosrudis, O talaje, O turcicate, O rostrata and O megnini) During the past 10 yr no arthropod-borne relapsing fevers have been reported from Colombia but there have been several suspicious cases in the department of Santander, where O rudis is not uncommon8
21 citations
TL;DR: Inoculation into various tissue culture cell-lines showed that L-929 cells gave the best results, and that the use of tissue cultures was a simple, efficient and rapid method for the identification of C. neoformans.
Abstract: Cryptococcus neoformans was isolated from the organs of 5 Colombian bats. The organism was recovered from the liver and intestine of 3 Carollia perspicillata from Tibu, and from the intestine and spleen of 2 Pteronotus psiolotis from Cartagena. C. neoformans has not been previously recorded from bats. Inoculation into various tissue culture cell-lines showed that L-929 cells gave the best results, and that the use of tissue cultures was a simple, efficient and rapid method for the identification of C. neoformans. All 5 strains of C. neoformans were virulent for CFW mice.
15 citations
TL;DR: A new large trypanosome was found in the blood of 19 Artibeus lituratus and 2 Phyllostomus hastatus bats and is described as Trypanosoma pifanoi, which is not capable of infecting mice, tissue culture cells, Carollia perspicillata bats, or triatomids, but is able to infect A.lituratus bats.
Abstract: SYNOPSIS. A new large trypanosome was found in the blood of 19 Artibeus lituratus and 2 Phyllostomus hastatus bats. The monomorphic trypanosome resembles Trypanosoma megadermae in some respects, but differs from it in that it is larger and has a short flagellum, both extremities are very tapered, the kinetoplast is very close to a small nucleus and there is a greater distance between the kinetoplast and the posterior extremity of the body. In diphasic blood-agar cultures there is a great variety of odd multiplication forms not described from other trypanosome cultures, but some simulate T. cruzi. This trypanosome is not capable of infecting mice, tissue culture cells, Carollia perspicillata bats, or triatomids, but is able to infect A. lituratus bats. Culture forms of the trypanosome inoculated intra-coelomically are pathogenic for several species of triatomids, and multiply in the hemolymph of Rhodnius prolizus, often producing forms similar to crithidiae of T. rangeli. Culture forms of the trypanosome seem to have common antigens with T. cruzi. This new species is described as Trypanosoma pifanoi.
15 citations
TL;DR: The unsporulated oocysts in the bat feces are 30.9–24.0 by 28.2 μ (near 28.8 × 26.1 μ), and their outstanding feature is the pronounced pitting of the thick brownish oocyst wall.
Abstract: SYNOPSIS. Eimeria eumopos n. sp. (Coccidiida, Eimeriidae) from a Colombian bat Eumops trumbulli (Chiroptera, Molossidae) is described. This is the first recorded coccidium in a bat from the western hemisphere, and the sixth bat coccidium species described to date. The unsporulated oocysts in the bat feces are 30.9–24.0 by 28.9–23.2 μ (near 28.8 × 26.1 μ). Their outstanding feature is the pronounced pitting of the thick brownish oocyst wall.
10 citations
TL;DR: Twenty three strains of a yeast-like fungus were recovered from the organs of 19 Colombian bats belonging to 4 species and appeared to be an as yet undescribed species of Candida, classified as a new Candida and proposed for the name Candida chiropterorum.
Abstract: Twenty three strains of a yeast-like fungus were recovered from the organs of 19 Colombian bats belonging to 4 species (Carollia perspicillata, Desmodus rotundus, Mormo@s megal@hylla and Natalus tumidirostris) from a large cave inhabited by thousands of bats located near the village of San Gil (Santander), Colombia. Soft ticks (Antricola mexicanus), present in large numbers in the cave as well as the guano were also positive for the same fungus. This fungus has not been recovered from bats or guano in other parts of Colombia although more than 5000 bats from 206 localities in 27 departments have been examined. All of the strains were identical both physiologically and morphologically and appeared to be an as yet undescribed species of Candida. It has now been classified as a new Candida and we propose the name Candida chiropterorum. This fungus is very similar physiologically to the Candida ci/errii described by KREGER-VAN ~RIJ (1965) but is quite different in its morphology, as the size and shape of the blastospores are distinct (see Figs. A + B). The buds arise directly from the hyphae, and chlamydospores and large refractory bodies are present. It differs from the majori ty of Candida by its lack of fermentative capacity, and from C. brumptii, C. curvata, C. humicola, C. japonica, C. lipolytica, C. melinii, C. mesenterica, C. mycoderma, C. rugosa and C. zeylonoides by differences in sugar assimilation and from C. scotii in the assimilation of nitrate, and from all described Candida spp. in its morphology. The isolates were investigated using the methods described
9 citations
TL;DR: The results of a 5-year survey of air-borne fungus spores in Bogota, Colombia are given, citing number of fungus spores, genera, and the correlation of these to the amount of rainfall and wind velocity.
Abstract: The results of a 5 year survey of air-borne fungus spores in Bogota, Colombia are given, citing number of fungus spores, genera, and the correlation of these to the amount of rainfall and wind velocity. The results of this survey to similar studies made in other countries are discussed.
6 citations
TL;DR: The present article has made some statistical analyses in relation to the distribution of the genetic variants in various Colombian populations and the existence of overdominance in Drosophila.
Abstract: Cordeiro (1952) and Cordeiro and Dobzhansky (1954) have noticed that the same chromosome in different combinations can produce variable viability. Wallace and King (1952), Greenberg and Crow (1960), Hiraizumi and Crow (1960), and others have presented evidence to show that the drastic chromosomes were exerting average deleterious effects under heterozygous conditions. The works by Morton, Crow and Muller (1956) criticized mathematically by Li (1963a, b, c) and by Sanghvi (1963) emphasize a hypothesis which says that the general viability, mortality, or morbidity in outbred and inbred lines show a decrease in viability in heterozygous carriers for those deleterious genes. On the other hand, there are results by Masing (1938, 1939a), Berg (1942, 1943, 1944), and Wallace (1956, 1959, 1960, 1962) which indicate the existence of overdominance in Drosophila. Some authors, e.g., Berg (1942, 1943), have results which indicate that the appearance of lethals as deleterious, neutral, or heterotic in heterozygotes varied in different populations. Other authors, e.g., Wallace have suggested that chromosomes with deleterious effects on viability in homozygotes are often selectively advantageous when carried in heterozygous condition. In one of Wallace's papers (1962) he points out that most investigators have overlooked the fact that viability effects of lethal and semilethal chromosomes in heterozygous condition seem to depend upon the source of the homologous chromosome. The distribution of the genetic variants in various Colombian populations have already been presented (Hoenigsberg and de Navas, 1965). In the present article the authors have made some statistical analyses in or-
4 citations
01 Mar 1968
TL;DR: In this paper, a technique is given by which the set of all nonredundant paths, called proper flow paths, is uniquely determined in a communication net, which employs a direct and simple means of eliminating the redundancy in a pathfinding routine proposed previously by Paz, involving symbolic noncommutative multiplications among the entries of a modified vertex-adjacency matrix.
Abstract: In a communication net in which the maximum attainable flows are determined by the vertex capacities, there is, in general, a high degree of redundancy among the paths available for flow assignments in the net. A technique is given by which the set of all nonredundant paths, called proper flow paths, is uniquely determined. The method employs a direct and simple means of eliminating the redundancies in a pathfinding routine proposed previously by Paz, involving symbolic noncommutative multiplications among the entries of a modified vertex-adjacency matrix. A useful byproduct ensues with the immediate identification of vertexes which are not in any vertex cut set. This simplifies the problem of identifying all vertex cut sets in the net. A presentation of proper-flow-path theory in communication nets is included in the paper.
3 citations