Extremophiles as sources of inorganic bio-nanoparticles

Industrial use of nanotechnology in daily life has produced an emphasis on the safe and efficient production of nanoparticles (NPs). Traditional chemical oxidation and reduction methods are seen as inefficient, environmentally unsound, and often dangerous to those exposed and involved in NP manufacturing. However, utilizing microorganisms for biosynthesis of NPs allows efficient green production of a range of inorganic NPs, while maintaining specific size, shape, stability, and dispersity. Microorganisms living under harsh environmental conditions, called “Extremophiles,” are one group of microorganisms being utilized for this biosynthesis. Extremophiles’ unique living conditions have endowed them with various processes that enable NP biosynthesis. This includes a range of extremophiles: thermophiles, acidophilus, halophiles, psychrophiles, anaerobes, and some others. Fungi, bacteria, yeasts, and archaea, i.e. Ureibacillus thermosphaericus, and Geobacillus stearothermophilus, among others, have been established for NP biosynthesis. This article highlights the extremophiles and methods found to be viable candidates for the production of varying types of NPs, as well as interpreting selective methods used by the organisms to synthesize NPs.     

Studies on Ca2+-accumulating vesicles in oocytes of the snail Helix aspersa

Summary Ultrastructural, cytochemical and autoradiographic techniques were used to study the functional significance of Ca²⁺-accumulating vesicles in Helix aspersa oocytes. The organic material of these vesicles is capable of adsorbing calcium ions, thus removing them from the cytosol and forming osmotically inactive complexes that are concentrated in the core. Ca²⁺-accumulating vesicles likely act as subcellular detoxifying compartments that sequestrate excess cytosolic Ca²⁺ (and plausibly other metal cations) to maintain physiologically adequate ionic concentrations.Part of this paper was presented at the VII Congreso Nacional de Malacología (Sevilla, November 1988)     

Halocins: are they involved in the competition between halobacteria in saltern ponds?

Many representatives of the family Halobacteriaceae ("halobacteria") excrete halophilic bacteriocins (halocins) that inhibit the growth of other halobacteria. In spite of the fact that halocin production is widespread among the Halobacteriaceae, no information is available on their ecological significance. To test whether halocins may play a role in the interspecies competition between dif-ferent types of halobacteria in saltern crystallizer ponds inhabited by dense communities of these red halophiles, we assayed for halocins active against a variety of halobacteria in salterns from different locations worldwide. Detection of halocin activity was based on the inhibition of growth of indicator organisms on agar plates, the decreased incorporation of radiolabeled substrates, and microscopic examinations. No halocin activity was detected in any of the brines examined, in spite of the fact that halocin production was demonstrated in cultures of most microorganisms isolated from these brines. Thus, the contribution of halocins in the competition between different halobacteria in hypersaline aquatic environments is probably negligible. Received: July 29, 1999 / Accepted: October 18, 1999     

Rhizobium extracellular structures in the symbiosis

The extracellular and surface polysaccharides produced by Rhizobium species constitute a composite macromolecular interface between the bacterial cell and its environment. Several of these polysaccharides are involved in the complex series of interactions leading to the establishment of an effective Rhizobium-legume symbiosis. Extracellular heteropolysaccharides (EPSs) are found in culture supernatants, while capsular polysaccharides adhere to the cell surface. Cyclic (1–2)--d glucan is a periplasmic oligosaccharide that has also been found in the culture supernatants of some strains. The lipopolysaccharides (LPSs), which form part of the outer membrane and contain the O-somatic antigens, comprise the other major group of extracellular polysaccharides. In this review we will describe the major Rhizobium extracellular structures and their role in symbiosis with leguminous plants.The authors are with the Departamento de Microbiologia y Parasitologia, Facultad de Farmacia. Universidad de Sevilla, 41012 Sevilla, Spain     

Phylogeny of the tribe Colletieae (Rhamnaceae) – a sensitivity analysis of the plastid region trnL-trnF combined with morphology

The phylogenetic relationships within the tribe Colletieae (Rhamnaceae) were examined combining data from a previous morphological analysis with data from the trnL intron and trnL-F spacer. Previous studies have failed to confirm monophyly of the genus Discaria, the only genus of the tribe with an amphiantarctic distribution. The data set was analyzed using direct optimization as implemented in the computer program POY. Direct optimization searches for multiple optimal sequence alignments and is therefore well suited for analyzing DNA sequences including ambiguous alignable regions as found in the present study. Eight different costs were used for treating the indel information. Indels were treated as single events, equal to a fifth character state, or strings of gaps were treated as single events using different costs for opening a gap and extending the gap. The optimal cost set was selected by use of both character-based and topological congruence measures. Both congruence measures agreed upon a single optimal cost set. The resulting tree generally agrees with the current taxonomic treatment of the tribe Colletieae that recognizes six genera out of which three are monotypic. However, monophyly of Discaria was not supported and the results strongly suggest segregating D. nana and D. trinervis, and re-establishing the genus Ochetophila.We are grateful to the curator of the Herbario Gaspar Xuárez, Universidad de Buenos Aires (BAA), and to the curators of the Botanic Garden of the University of Copenhagen, Botanischer Garten und Botanisches Museum Berlin-Dahlem, Jardín Botánico Lucien Hauman (Facultad de Agronomía de la Universidad de Buenos Aires), Rancho Santa Ana Botanic Garden, and Royal Botanic Gardens, Melbourne, for permission to use material from their collections. María Elena Arce, María Martha Bianchi, Eugenia Chaia, and Neville Walsh kindly provided freshly collected material. We also thank Pablo A. Goloboff, Niels Klazenga, Pauline Y. Ladiges, Martín Ramírez, Ole Seberg, Llywela Williams, and two anonymous reviewers for critically reading earlier drafts of this paper. This work was supported in part by grants TG 028 (Universidad de Buenos Aires) and PIP 4027/96 (CONICET) to D. Medan. The University of Copenhagen supported Lone Aagesen (Ph.D. grant). Jürgen Kellermann received a Ph.D.-scholarship from the University of Melbourne.     

Organellar DNA restriction fragment length polymorphism (RFLP) and nuclear random amplified polymorphic DNA (RAPD) analyses of morphotypes of Gracilaria (Gracilariales,Rhodophyta) from Chile

The extreme phenotypic variability recognized among the species of Gracilaria has highlighted the need for the application of refined methods to help solve taxa identifications. In Chile, there still exists uncertainty about the exact number of Gracilaria species. Our investigations are centered on DNA analyses of morphotypes collected from different geographical locations, namely Lenga and Isla Santa María, Region VIII (36°00 S to 38°00 S), and Maullín, Region X (39°30 S to 43°40 S). These two regions of Chile are considered as areas of confluence of G. chilensis, G. verrucosa, and a species of Gracilariopsis. In this study four morphotypes, from a natural bed located in Maullín, were analyzed for RFLP of plastid DNA and the results compared with data of four morphotypes from a bed in Lenga. The DNA banding patterns from each enzyme digest were identical irrespective of morphotypes and/or locations. In an attempt to unravel the nature of the morphological differences found among Lenga and Maullín morphotypes, RAPD analyses of nuclear DNA were also performed; however, no polymorphism has been found yet. Therefore, the data of this study, as well as concurrent data from preliminary interfertility tests, suggest that all morphotypes belong to a single taxon, Gracilaria chilensis.Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas     

Characterization of two extracellular proteases fromLeuconostoc oenos

Two extracellular proteolytic activities were characterized fromLeuconostoc oenos isolated from Argentinian wines. Both activities were maximal with autoclaved grape juice as substrate. The temperature and pH optima for the two proteolytic activities were different (30 and 40°C, and pH 4.0 and 5.5, respectively). Both enzymes were thermostable and their activities were unaltered by heating at 70°C for 15 min. Metal ions were not required for the activities. Neither enzyme appeared to be a serine protease but both were strongly inhibited by cysteine and -mercaptoethanol, indicating the involvement of disulphide bridges.The authors are with the Centro de Referencia para Lactobacilos (CERELA), Chacabuco 145, 4000 Tucumán, Argentina M.E. Farías and M.C. Manca De Nadra are also with the Facultad de Bioquímica, Quimica y Farmacia, Universidad Nacional de Tucumán, 4000 Tucumán, Argentina.     

Colloid droplets in the magnocellular secretory neurons of the reptilian hypothalamus: An immunocytochemical and lectin-histochemical study

Summary The immunocytochemical and lectin-binding properties of the magnocellular neurosecretory neurons in the hypothalamus of 2 reptilian species, the snake Natrix maura and the lizard Liolaemus cyanogaster, were investigated. Particular attention was paid to the secretory droplets present in these neurons. Antisera against bovine neurophysins I+II, arginine-vasotocin, and mesotocin were used. The following lectins were applied: concanavalin A (Con A), wheat-germ agglutinin (WGA), and Limax flavus agglutinin (LFA). Adjacent 1-m-thick methacrylate sections were used to investigate the same secretory neuron and the same colloid droplets with all three antisera and all three lectins. Several sections were treated with trypsin and urea before immunostaining or lectin binding. Con A bound to both vasotocin- and mesotocin-immunoreactive neurons, WGA exclusively to vasotocin neurons; neither of these neurons reacted with LFA. The colloid droplets were present in vasotocin neurons but absent in the mesotocin neurons. These secretory droplets showed an affinity for Con A but not for WGA, and reacted with antisera against neurophysins and vasotocin. In Natrix maura, the colloid droplets became reactive with Con A and the antisera used only after pretreatment of the sections with trypsin and urea. Within the hypothalamo-neurohypophyseal system, antiserum against vasotocin and WGA revealed the same fiber bundles. It is concluded (i) that in reptiles the vasotocin-neurophysin precursor is glycosylated, (ii) that vasotocin neurons have the exclusive capacity to form colloid droplets, and (iii) that these droplets are an intracisternal (RER) storage form of the vasotocin-neurophysin precursor.This work was partially supported by Grants BOJA 27/9/88 from the Dirección General de Universidades e Investigación de Junta de Andalucía and DGICYT PB87-0710 from the Comisión Interministerial de Ciencia y Tecnología, Madrid, to P.F.-LL.; and Grant 89-01 from the Dirección de Investigaciones, Universidad Austral de Chile, to E.M.R.     

Seasonal variation of carrageenans in tetrasporic,cystocarpic and ‘sterile’ stages of Gigartina skottsbergii S. et G. (Rhodophyta,Gigartinales)

Cystocarpic and sterile plants of Gigartina skottsbergii produce -carrageenans, while tetrasporophytes produce -carrageenans. No seasonal variation in the carrageenan yields in the three stages was evident. Yields were clearly higher in cystocarpic (34.1–64.7%) and sterile samples (32.3–71.8%) than in tetrasporic plants (10.1–34.0%). Chemical characteristics of the polysaccharides for any stage are the same throughout the year.The authors are Research Members of the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.The authors are Research Members of the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.     

Conserved and variable regions in the chromosomal and extrachromosomal DNA of halobacteria

Summary Total DNA from Halobacterium halobium and other halobacteria strains is separated into two fractions, FI and FII, which differ in their G+C content. FI DNA, which represents the major part of the genome is highly conserved in all purple-membrane-forming halobacteria. Fraction II (FII) consists in H. halobium of three DNA specimen: (a) the previously isolated plasmid pHH1, (b) a heterogeneous set of ccc-DNA molecules present in the cell in low copies, termed minor-circular DNA (MCD) and (c) a new type of more A-T rich DNA segments (chromosomal islands) which, as described here and by Pfeifer and Betlach (1985), are integrated in FI. Sequences homologous to pHH1 occur only in Halobacterium species closely related to H. halobium (like H. cutirubrum), whereas MCD sequences are present in all purple-membrane-forming halobacteria. The sequences of the newly identified chromosomal islands are only found like pHH1, in Halobacterium species, closely related to H. halobium. Total DNA from square halobacteria exhibits no extended homologies to FI or FII DNA from H. halobium. The only common DNA sequences found in all halobacteria are certain insertion elements (ISH), such as ISH26. Based on these data, halobacteria can be subdivided in at least three major groups.Dedicated to Prof. Dr. F. Lingens to his 60th anniversary     

Immuno- and lectin-electron-microscopic investigation of the neural lobe of the hypophysis in the snake Natrix maura

Summary By the use of lectin histochemistry, and immunocytochemistry with antisera against bovine neurophysins I and II (NPs), arginine vasotocin (AVT) and mesotocin (MST), the neural lobe of the hypophysis in the snake Natrix maura was investigated at the light- and electron-microscopic levels. While paraldehyde-fuchsin stained virtually all neurosecretory endings, the periodic acid-Schiff reaction revealed only a portion of these elements. Furthermore, concanavalin-A and wheat-germ agglutinin lectins reacted with some but not all terminals. While in electron micrographs lectin-positive neurosecretory endings displayed medium-sized, pale neurosecretory granules, those from lectinnegative endings were larger and denser. The antiserum against the two NPs revealed the entire population of neurosecretory endings. The antiserum to AVT stained more numerous fiber elements than the antiserum to MST. Ultrastructurally, correlations concerning size and electron density can be found, on the one hand, between AVT-immunoreactive and lectin-positive neurosecretory granules and, on the other hand, between MST-immunoreactive and lectinnegative granules. The use of immuno-electron microscopy for the characterization of the different endings in the neural lobe and the presence of carbohydrates in some of them is discussed.This work was supported by the Directión General de Universidades e Investigación de la Junta de Andalucía (Grant BOJA 27/9/88) and the Direction General de Investigación Científica y Técnica (DGICYT Grant PB87 0710) Espaa     

Plant genes induced in the Rhizobium-legume symbiosis

Rhizobium, Bradyrhizobium and Azorhizobium can elicit the formation of N₂-fixing nodules on the roots or stems of their leguminous host plants. The nodule formation involves several developmental steps determined by different sets of genes from both partners, the gene expression being temporally and spatially coordinated. The plant proteins that are specifically synthesised during the formation and function of the nodule are called nodulins. The nodulins that are expressed before the onset of N₂ fixation are termed early nodulins. These proteins are probably involved in the infection process as well as in nodule morphogenesis rather than in nodule function. The nodulins expressed just before or during N₂ fixation are termed late nodulins and they participate in the function of the nodule by creating the physiological conditions required for nitrogen fixation, ammonium assimilation and transport. In this review we will describe nodulins, nodulin genes and the relationship between nodulin gene expression and nodule development. The study of nodulin gene expression may provide insight into root-nodule development and the mechanism of communication between bacteria and host plant.J.A. Muñoz and A.J. Palomares are with the Departamento de Microbiologia y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain. P. Ratet is with the Institut des Sciences Végétales, CNRS, Avenue de la Terrasse, F-91198 Gif-sur-Yvette, Fance     

Small heat shock proteins from extremophiles: a review

Many microorganisms from extreme environments have been well characterized, and increasing access to genomic sequence data has recently allowed the analysis of the protein families related to stress responses. Heat shock proteins appear to be ubiquitous in extremophiles. In this review, we focus on the family of small heat shock proteins (sHSPs) from extremophiles, which are -crystallin homologues. Like the -crystallin eye lens proteins, sHSPs act as molecular chaperones and prevent aggregation of denatured proteins under heat and desiccation stress. Many putative sHSP homologues have been identified in the genomic sequences of all classes of extremophiles. Current studies of shsp gene expression have revealed mechanisms of regulation and activity distinct from other known hsp gene regulation systems. Biochemical studies on sHSPs are limited to thermophilic and hyperthermophilic organisms, and the only two available crystal structures of sHSPs from Methanocaldococcus jannaschii, a hyperthermophilic archaeon and a mesophilic eukaryote, have contributed significantly to an understanding of the mechanisms of action of sHSPs, although many aspects remain unclear.Communicated by D.A. Cowan     

Analisis de 6000 especímenes micológicos Sintesis estadística. — Comentarios

Resumen En este trabajo se estudia en la Parte I todo el material procedente de especímenes clínicos.En primer lugar se estudian las cepas aisladas de Micosis Superficiales o Dermatomicosis.En segundo lugar, los hongos levuriformes del género Candida procedentes de materiales clínicos varios.En tercer lugar los agentes de Micosis Profundas, y finalmente los hongos del aire de Caracas que tienen interes alergológico.Los resultados de todo aparecen en los cuadros sinópticos adjuntos.

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Summary In this part of our work we deal with fungi of clinical interest.Firstly, we study specimens isolated from dermatomycoses.Secondly, yeast-like fungi of the genusCandida of clinical origin.Thirdly, fungi producing systemic mycoses and lastly, air-borne fungi of allergic interest from Caracas and its surroundings.

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Résumé Dans la première partie de ce travail, on étudie tout le matériel d'intérêt médical.En premier lieu, les souches isolées de matériel clinique de Mycoses Superficielles ou Dermatomycoses.En deuxième lieu, les champignons lévuriformes du genre Candida provenant de matériaux cliniques variés.En troisième lieu, les Agents de Mycoses Profondes et, finalement, les champignons contenus dans l'air de Caracas intéressant la Mycologie Allergique.

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(Trabajo de la Sección de Micología del Instituto Nacional de Higiene)

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Trabajo presentado al IV Congreso Venezolano de Tisiología y Neumonología, Valencia, Diciembre 1959.

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Jefe de Sección Micología. — Instituto Nacional de Higiene. Jefe de Sección Micología.-Hospital Universitario. Profesor de la Catedra de Micología.-Escuela de Bioanálisis Fac. de Medicina U C V.

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Directora de la Micoteca Nacional.-Seccion de Micología, Instituto Nacional de Higiene.     

Yearly reproductive activity of Limnoperna fortunei (Bivalvia) as inferred from the occurrence of its larvae in the plankton of the lower Paraná river and the Río de la Plata estuary (Argentina)

Densities of planktonic larvae of the Asian freshwater invasive pest bivalve Limnoperna fortunei (Dunker) were monitored weekly between 19 September 1997 and 22 January 1999 at two sites: the Paraná de las Palmas river, ca. 130 km north of Buenos Aires (33°57.5 S, 59°12.5 W), and a coastal station on the Río de la Plata estuary, in Buenos Aires (34°33.5 S, 58°24.5 W). Very variable but generally high (up to 25000–35000 ind. m^–3) concentrations were recorded at both sites in September 1997-April 1998, and again in August 1998–January 1999, suggesting continuous reproduction during these months. In May through July 1998 larval densities were generally below 100-200 ind. m^–3. The threshold temperature level associated with the onset and termination of reproduction was ca. 16–17 °C. With the exception of August-September 1998, when Río de la Plata temperatures were below 16.7 °C and larval concentrations less than 1000 ind. m^–3, whereas those of the Paraná were above 16.7 °C, with 1300–13000 larvae m^–3, coupling between the two sites investigated was generally good. Since its invasion in Argentina around 1990, L. fortunei has rapidly become a major nuisance for industrial and power plants located along the lower Paraná and Río de la Plata. The fact that the mollusc produces larvae during 9 months per year greatly hinders its control.     

Culture conditions for enhanced cellulase production by a native strain of Penicillium purpurogenum

A cellulolytic wild-type strain of Penicillium purpurogenum was isolated from a soil sample in southern Chile. It grew best at 28°C from an inoculum of 4×10⁷ spores/100 ml medium. Highest endoglucanase activity was with Sigmacell as carbon source and corn steep liquor as nitrogen source. Wheat bran enhanced the production of endoglucanase and -glucosidase. The enzymes in the crude supernatants were stable up to 50°C and between pH 4.4 and 5.6 for 48 h.J.Steiner and C. Socha are with the Facultad de Ciencias Quimicas y Farmacéuticas, Universidad de Chile, Casilla 233, Santiago 1, Chile; J. Eyzaguirre is with the Laboratorio de Bioquímica, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.     

Phylogenetic analysis of Theobroma (Sterculiaceae) based on Kunitz-like trypsin inhibitor sequences

Trypsin inhibitor gene sequences were used to investigate the phylogenetic relationships among Theobroma and Herrania species, considered as sister-groups, with particular interest on the monophyly and infra-generic relationships of Theobroma. The presumed amino acid sequences of 23 analyzed samples, from 11 Theobroma and three Herrania species, comprising all sections from both genera, demonstrated a high similarity with a previously characterized T. cacao Kunitz trypsin inhibitor. The trypsin inhibitor gene accumulated mutations at faster rate than prior analyzed nuclear or chloroplastic genes. None of the sequences presented introns. The phylogeny of the trypsin inhibitor sequences was congruent with the phylogenetic hypotheses of the Theobroma and Herrania species based on morphology. The monophyly of Theobroma was not strongly supported, corroborating previously described absence of obvious synapomorphies for Theobroma. The species grouped consistently according to genus and section. The monophyly of all Theobroma sections was supported, except for section Glossopetalum, which was paraphyletic to section Andropetalum. Evidences sustain that T. mammosum may be included into section Glossopetalum. The potential use of trypsin inhibitor gene sequences in phylogenetic studies of Theobroma was demonstrated.We acknowledge the financial support by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); International Foundation of Science (IFS), and the permission from Empresa Brasileira de Pesquisas Agropecuária (EMBRAPA); Comissão Executiva do Plano da Lavoura Cacaueira (CEPLAC) to use the plant material. We thank the useful comments from the reviewers.     

State of water in extremely halophilic bacteria: Heat of dilution ofHalobacterium halobium

Summary Heat of dilution ofHalobacterium halobium was measured when thick pastes of the bacteria, harvested throughout a complete growth cycle, were lysed by mixing with 40 times their volume of water in a microcalorimeter. A series of comparative measurements was made with pastes of bacteria previously disrupted by freezing and thawing but otherwise identical to the pastes of whole bacteria. The frozen-thawed pastes gave endothermic values some 18% greater than those obtained with intact bacteria; the difference was highly significant. Evidence was obtained that the mechanical component of bursting did not contribute to the difference between whole and lysed bacteria. On the other hand, when a correction was applied for heat of mixing of intracellular salts with extracellular NaCl, such as occurs when the bacteria lyse, the difference between whole and disrupted organisms was largely eliminated from exponential phase halobacteria but not from those harvested in stationary phase. It is concluded that there is no evidence, as reflected in heat of dilution, of abnormal solution properties of the cytosol of young halobacteria, which are rich in potassium. On the other hand, and paradoxically, some doubt remains about stationary phase organisms whose cytosol has a much higher Na⁺ content (and Na/K⁺ ratio) than the cytosol of exponential phase bacteria.     

Regional peculiarities of some deep mycoses

Summary Some observations suggest that some deep mycoses would show epidemiological and clinical dissimilarities in different countries.In some tropical zones the atypical, non lymphangitic, fixed forms of sporotrichosis are more frequently reported than the lymphangitic, typical forms. This difference has been ascribed to the uneven ability of the reporting authors to recognize the atypical forms, to early or late diagnosis as the lymphangitis has a tendency to disappear 3 to 4 months after the infection, to an inhibitory effect of high ambient temperatures on the growth of the fungus in the tissues and to reinfections in partially resistant people.The frequency of chromoblastomycosis coincides with its predominance in the lower limbs and therefore some causes of susceptibility to infection of the skin of the lower limbs are analized: non use of footwear, unbalanced diets, parasitic diseases and modifications of reactivity due to specific and non-specific sensitization.Some records are indicative that the first stage of the infection byNocardia brasiliensis may be a chancriform syndrome with lymphangitis showing a tendency toward self-limitation. The same causes which have been considered favorable for the development of chromoblastomycosis might have an influence on the frequency of mycetomas.Several factors may have an influence on the characteristics of histoplasmosis: presence or abscence of starlings, permanently high ambient temperature and humidity or alternance of warm-humid and cold seasons, early or late infection of children.Dissimilarities in the features of South American blastomycosis in different countries have still not been reported with accuracy. The frequency offer remarkable differences and the disease is recorded especially in subtropical humid areas of continental Latin America. The habitat of the fungus is unknown.

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Peculiaridades regionales de algunas micosis profundas

Resumen Algunas observaciones son sugestivas en el sentido de que algunas micosis profundas mostrarían diferencias epidemiológicas y clínicas en diferentes países.En algunas zonas tropicales cálidas las formas atípicas, no linfangíticas, fijas, de la esporotricosis son más frecuentemente registradas que las formas lifangíticas, típicas. Esta diferencia ha sido atribuída a la desigual habilidad de los diferentes autores para reconocer las formas atípicas, al diagnóstico precoz o tardío dado que la linfangítis tiende a desaparecer 3 a 4 meses despues de la infección, a un efecto inhibitorio de elevadas temperaturas ambientales sobre la vida del hongo en los tejidos y a reinfecciones en poblaciones parcialmente resistentes.La frecuencia de la cromoblastomicosis coincide con su predominancia en los miembros inferiores y en consecuencia se analiza algunas causas de susceptibilidad a la infección de la piel de las extremidades inferiores: no uso de calzado, dietas carenciadas, enfermedades parasitarias y modificaciones de la reactividad debida a sensibilización específica e inespecífica.Existen observaciones que indican que el primer estadio de la infección porNocardia brasiliensis puede ser un sindrome chancriforme con linfangitis con tendencia a auto-limitación. Las mismas causas que han sido consideradas como favos recedoras del desarrollo de la cromoblastomicosis podrían tener influencia en los micetomas y su frecuancia.Varios factores pueden tener influencia en las características de la histoplasmosis: pululación o ausencia de estorninos, temperaturas permanentemente delevadas y alto grado higrométrico en algunos países y alternancia de estaciones en otros, infección temprana o tardía de los niños.Diferencias en aspectos de la blastomicosis sudamericana en diferentes países aún no han sido relatadas con precisión. La frecuencia ofrece notables divergencias y la enfermedad es registrada especialmente en zonas sub-tropicales húmedas de América Latina continental. El habitat de su agente es desconocido.

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Read at the Official Meeting of The Medical Mycological Society of the Americas held in Mexico D. F., August 8, 1970.     

Micetomas y procesos premicetomatosos en el Uruguay

Resumen La casuística uruguaya incluye 5 casos de micetomas y 5 procesos considerados premicetomatosos.Los micetomas fueron producidos por mohos en 2 oportunidades y por nocardias en las 3 restantes. Los mohos responsables fueron Scedosporium apiospermum en un caso y Rubromadurella langeroni en el otro aunque aquí el autor no obtuvo cultivos. Nocardia asteroides fué el agente de 2 casos de micetomas mientras que en el tercero no se lograron cultivos.Tres micetomas pudieron ser diagnosticados en una etapa bien temprana consiguiéndose curaciones fáciles por procedimientos médicos o quirúrgicos. En los 2 restantes el diagnóstico fué tardío y hubo que recurrir a la amputación del miembro afectado.A propósito del micetoma de miembro superior por S. apiospermum se propone hablar de una nueva forma clínica de micetoma: la forma linfangítica.Los procesos premicetomatosos incluyen 3 casos de nocardiasis linfangitica de miembros superiores por N. brasiliensis, un absceso de hombro por la misma especie y una artritis tibiotarsiana fistulizada por N. asteroides. Todos ellos fueron curados en cortos espacios de tiempo.El diagnóstico precoz del micetoma y cuadros clínicos relacionados en el Uruguay se atribuye a la consulta médica temprana lo que a su vez sería consecuencia primaria de la no existencia de obstáculos de importancia en las comunicaciones entre un sitio y otro del territorio nacional.

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Summary Five cases of mycetomas and 5 premycetomatous lesions have been recorded in Uruguay.Two mycetomas were produced by fungi and three by nocardias. The causal fungi were identified as Scedosporium apiospermum in one case and Rubromadurella langeroni in the other. Nocardia asteroides was isolated from 2 cases and no cultures were obtained from the remaining one.Three mycetomas were diagnosed in an early stage of development and easy cures were obtained through medical or surgical procedures. In the other two cases the diagnosis was made in a late stage and the final result was amputation.A new clinical form of mycetoma called lymphangitic is proposed after describing a patient with mycetoma of the forearm and arm by S. apiospermum.Premycetomatous lesions included 3 cases of lymphangitic nocardiasis of the arm by N. brasiliensis, an abscess of the shoulder by the same species and an arthritis of the ankle by N. asteroides. All were cured after short periods of therapy.The usual early diagnosis of mycetomas and related diseases un Uruguay is considered to be the result of a prompt medical consultation due mainly to the abscence of important geographical obstacles in the Country.

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Se analiza la casuística uruguaya de micetomas y procesos premicetomatosos junto a sus agentes causales.A propósito de un micetoma de miembro superior por Scedosporium apiospermum se propone una nueva forma clinica de micetoma: la forma linfangítica.Se destaca la importancia del diagnóstico precoz del micetoma y el por qué ello es factible en el Uruguay.