EFFECTS OF COMPETITION AND DISTURBANCE ON THE RESPROUTING PERFORMANCE OF THE MEDITERRANEAN SHRUB ERICA MULTIFLORA L. (ERICACEAE)

Two field experiments were designed to evaluate the importance of competition, fire, repeated disturbance, and their interactions on the vegetative and reproductive performance of the Mediterranean shrub Erica multiflora over a 2.5-yr period. In a burn experiment, fire was applied to the ground-level stumps of previously clipped 13-yr-old plants with a propane torch and competition was diminished by removal of neighboring plants. Fire resulted in a reduction of sprout vigor and biomass of flowers; mature neighbors also reduced E. multiflora sprout vigor and flowering. The interaction between fire and competition was nonsignificant. In a stand burned by a wildfire we studied the effects of regenerating neighbors on target plants by removing all neighbors or only Quercus coccifera, the most dominant species in the burned stand. In this stand we also simulated herbivory by repeatedly clipping the sprouts of E. multiflora. Regenerating neighbors did not affect target plant sprout vigor after the wildfire, but did cause a decrease in the biomass of flowers per plant. Survival decreased after repeated clipping but was not affected by neighborhood treatment. The results suggest that the importance of competition on resprouting vigor was temporally variable. Variables related to plant size rather than species determined competitive superiority: resprouting neighbors did not affect resprouting performance of target plants, but mature neighbors did. In nature, fire may directly reduce vegetative and reproductive biomass by the heating effect. But it may have an indirect positive effect on biomass, by reducing competition among plants. Frequent disturbances that removed aboveground biomass of E. multiflora had a detrimental effect on target plant survival independent of neighborhood effect.     

Application of immunoprecipitation techniques to the diagnosis of cutaneous and extracutaneous forms of sporotrichosis

Sporotrichosis is a mycosis which in our country has been described as only producing cutaneous and subcutaneous infections; in other countries it has been reported as causing pulmonary, bone, joint and meningeal infections.Possibly the systemic form also occurs in Venezuela since, along with the causative agent, all other factors considered as predisposing to systemic infection exist here.Through immunodiffusion (ID) and immunoelectrophoresis (IEP) and using a filamentous form metabolic antigen from Sporothrix schenckii, we were able to demonstrate precipitating antibodies against this fungus both in patients with cutaneous sporotrichosis, diagnosed by culture of the infecting agent, and in patients with pulmonary lesions. The IEP test showed the presence of an anodic arc which we have called the S arc, which could be one of the specific antigens of S. schenckii.

---

Resumen En Venezuela, el diagnóstico de la esporotricosis solo se plantea ante lesiones cutáneas y subcutáneas, sin embargo, no deja de llamar la atención que siendo esta micosis la más frecuente en nuestro medio y existiendo concomitantemente en la población todos los factores predisponentes para que el S. schenckii invada órganos internos, estas localizaciones no han sido descritas.La incorporación del antígeno del S. schenckii para detectar anticuerpos circulantes en la ID en nuestros estudios serológicos de rutina, nos permitió observar la presencia de bandas de precipitación contra este antígeno en sueros de pacientes con lesiones pulmonares, igualmente fueron detectados anticuerpos en pacientes con esporotricosis cutáneas diagnosticadas por cultivo.El estudio de la estructura antigénica de este hongo, puso de manifiesto la presencia de un arco de localización anódica, que podría ser producido por uno de los antígenos específicos de este hongo; este arco que denominamos S fue visualizado en todos los casos positivos de esporotricosis cutáneas, al ser estudiados sus sueros en la IEF.Los estudios realizados en sueros de pacientes con lesiones pulmonares pusieron de manifiesto anticuerpos precipitantes en la ID e IEF, con las caractéristicas de evidenciar más de una línea de precipitación en la ID y un arco S más largo en la IEF, pudiendo ser esto originado por mayor producción de anticuerpos circulantes. Se plantea la necesidad de obtener el cultivo del S. schenckii de las posibles lesiones extracutáneas de esta micosis.

     

Determination of the minimal inhibitory concentration of Amphotericin B and Miconazole for 21 strains of Aspergillus

The susceptibility of 21 strains ofAspergillus (11 ofA. fumigatus, 8 ofA. niger, and 2 ofA. flavus) isolated from human pathologic specimens to Amphotericin B and Miconazole has been comparatively studied. Determination of the minimal inhibitory concentration of both drugs in a liquid medium showed a noticeably variability for the different strains. The values obtained for Amphotericin B varied between 0.25g/ml (2 strains) and 1.25g/ml (5 strains) after 48 hours, and between 1.25g/ml (1 strain) and 50g/ml (1 strain) after 10 days. For Miconazole the results varied between 0.1g/ml (1 strain) and 25g/ml (1 strain) after 48 hours of incubation, and between 0.5g/ml (5 strains) and > 100g/ml after 10 days. The variability of these results indicates the usefulness of carrying ourin vitro sensitivity studies whenever it is possible.     

Analysis of intestinal cell proliferation after guanethidine-induced sympathectomy

Summary Guanethidine-induced sympathectomy in the rat during the neonatal period (injection of 20 g/g body weight every 48 h from day of birth until day 14) produces an absolute reduction in the number of sympathetic ganglion cells, but no significant alteration of body weight. Superior cervical ganglia show 79.8 % fewer cell bodies at 15 days and 92.3 % at 45 days; coeliac ganglia exhibit an 81.0 % reduction at 15 days and 89.6 % at 45 days in guanethidine-treated rats as compared to normal controls. The sympathetic ganglion cells that remain after treatment have an abnormal morphological appearance with distended mitochondria and depletion of endoplasmic reticulum. Sympathectomy produces a prolongation of the generation cycle time (Tc) as measured by the colchicine-induced mitotic arrest technique, and a decrease in labelling, mitotic, and migration indices. In addition, sympathectomy suppresses the amplitude of the circadian rhythm in mitotic activity. The general suppression of this activity in the intestinal epithelium is more pronounced in the jejunum and ileum than in the duodenum. Variation in the effectiveness of sympathectomy on the inhibition of intestinal cell proliferation may be related to segmental differences in cell proliferation, to segmental differences in innervation, and/or to segmental variation in the effectiveness of guanethidine.Supported by N.I.H. grant DE04557 to R.M.K. and N.I.H. grant 5-SO1-RR5373 to the University of Kansas Medical Center. The authors wish to acknowledge Charles A. Brownley, CIBA-Geigy, Summit New Jersey, U.S.A. for the gift of guanethidine-sulfate     

Partial deletion of 4p16 band in a ring chromosome and wolf syndrome

Summary A new case of ring chromosome 4 in a 2-day-old female child with multiple malformations is described. By means of the GTG-banding technique, a karyotype 46,XX,r(4), (p16q35) was determined. The characteristics of the child's karyotype and the relationship with the structure of the chromosome, especially the location of the deletion that produces the syndrome, are compared with previous reports.     

Two more "private" polymorphisms of Amerindian tribes: LDHb GUA-1 and ACP1 B GUA-1 in the Guaymi in Panama.

A survey of Guaymi Indians of Panama for the occurrence of genetic variants of 25 proteins of the erythrocytes and sera have revealed, in addition to seven well-known genetic polymorphisms, four rare variants and two "private polymorphisms," the latter involving erythrocyte acid phosphatase and lactate dehydrogenase. The significance of such private polymorphisms in tribal populations to the interpretation of rare variants in civilized populations is emphasized.     

Morphological changes in strains of Aspergillus flavus link ex fries and Aspergillus parasiticus speare related with aflatoxin production

Two strains ofAspergillus flavus Linkex Fr. and two strains ofA. parasiticus Speare were cultured on crushed moist wheat (Triticum durum var. Pané no. 247) for aflatoxin production studies in correlation with morphological changes. The toxicogenic strains were adapted to the substratum by means of successive transfers at regular intervals (72 h.)The amount aflatoxins synthesized by the toxicogenic strains decreased gradually after succesive subculturing. The decrease was accompanied by marked morphological changes. One of the strains studied,A. flavus NRRL 3251, lost completly the capacity of aflatoxin synthesis after several subcultures, presenting at the same time strong morphological variations.A. flavus CBS 120.62 also lost its toxicogenicity after six subcultures.     

A stereological analysis of developing egg chambers in the honeybee queen,Apis mellifera

Summary A polytrophic ovariole of the queen honeybee, Apis mellifera, is composed of a linear series of increasingly mature egg chambers, each consisting of an oocyte, an interconnected cluster of nurse cells, and a covering layer of follicle cells. This study describes changes in the volume of each of these components, as a function of the position of the egg chamber in the ovariole. An oocyte increases in volume from approximately 8.9 × 10³ m³ to approximately 9.6 × 10⁶ m³ over an average series of 20 egg chambers.     

Birefringence determination of magnetic moments of magnetotactic bacteria

A birefringence technique is used to determine the average magnetic moments <μ> of magnetotactic bacteria in culture. Differences in <μ> are noted between live and dead bacteria, as well as between normal density and high density samples of live bacteria.