Showing papers by "Federal University of São Carlos published in 1977"

Electrophoretic studies on polyploid amphibians—I. 6-phosphogluconate dehydrogenase (6-PGD)

Abstract: 1. 1. Mobility, activity and number of 6-PGD electrophoretic bands of the diploid and the tetraploid Odontophrynus americanus frogs are the same. This confirms previous cytological findings that, although genes are duplicated in number in the tetraploid, diploidization did not yet occur. Thus, locus duplication cannot be detected in O. americanus (4n). 2. 2. The 6-PGD of the triploid hybrids follows a trisomic mendelian pattern with two codominant alleles. Three bands were found: maternal (AA), hybrid intermediate (AC) and paternal (CC) with an intensity ratio of 4:4:1, respectively. 3. 3. The hypotheses on gene regulation in diploid, triploid and tetraploid Odontophrynus are discussed.

Electrophoretic studies on polyploid amphibians—III. Lack of locus duplication evidences through tetraploidization

Abstract: 1. 1. An investigation of 9 enzymatic systems by starch-gel and polyacrylamide electrophoreses in the tetraploid and diploid species Odontophrynus americanus and O. cultripes is presented. The electrophoretic patterns of five enzymes in the glucose-metabolizing system (critical enzymes) and 4 enzymes (peripheral enzymes) which were not directly involved in the above-mentioned system are compared which resulted in the conclusion that the diploid and tetraploid populations of O. americanus are identical in mobility and number of bands. 2. 2. Comparison between the tetrapoloid O. americanus and a closely related diploid species O. cultripes shows that the critical enzymes, ODH and ADH, exhibit equal number of bands. Most enzymes studied differ in the relative mobility of their bands, with the exception of HBDH, ADH and ODH. 3. 3. Polymorphism is detected for the tetrazolium oxidase (TO), due to two alleles F and S, both in the diploid and tetraploid species of O. americanus and in O. cultripes . The tetraploid O. americanus differs from the diploid species in having two extra phenotypes, suggesting a tetrasomic mode of inheritance. Electrophoreses of individual oocytes show that, in the tetraploid O. americanus , the four genes for TO are active in each cell. 4. 4. Our present results support the assumption that O. americanus 4n is a recent autotetraploid. Gene duplications detected in the tetraploid are prior to polyploidy.

Correlations and Plasmons in Quasi‐One‐Dimensional Metals

Abstract: The longitudinal dielectric function for a quasi-one-dimensional electron gas is obtained in a self-consistent field approximation (SCFA) scheme. Short range correlations arising from both, Coulomb and exchange effects through a local field correction depending on the pair-correlation function are included. The structure factor and the dielectric function are determined in a self-consistent scheme. Numerical results are presented for the structure factor, the static pair-correlation function, the plasmon dispersion and the compressibility. It is found that in the high density limit the results for the structure factor and the pair-correlation function are the same as given by Girardeau's exact expression. The plasmon dispersion curves indicate the onset of a minimum for xs ⪆ 7, in contrast with the RPA results. For values of xs in this region, the compressibility values become negative, indicating a possible instability of the system. In both RPA and SCFA results the plasmon modes are not Landau damped in contrast to isotropic metals. La fonction dieletrique longitudinale pour un gaz d'electrons unidimensionel a ete obtenue dans un schema d'approximation de champ auto-consistent (SCFA). On a inch des correlations a petite distance, originees par des effets d'echange et coulombiens, moyennant une correction de champ local qui depend de la function de correlation a paires. Le facteur de structure et la fonction dielectrique ont ete determines dans un sche ma auto-consistent. On a presente les resultats numeriques pour le facteur de structure, la fonction de correlation, la dispersion des plasmons et la compressibilite. On a ete trouve que, dans la limite de haute densite, les resultats concernant le facteur de structure et la fonction de correlation de paires sont les měmes que ceux obtenus par l'expression exacte de Girardeau. Les courbes de dispersion de plasmons indiquent l'apparition d'un minimum pour xs ⪆ 7, en contrastant avec les resultats RPA. Pour valeurs de xs dans cette region, les valeurs de la compressibilite devient negatives, indiquant une possible instabilite du systeme. Dans les resultats RPA et SCFA les modes de plasmons lie sont pas du tipe Landau amorti comme dam le cas des metaux isotropiques.

Electrophoretic studies on polyploid amphibians—II. Peptidases

Abstract: 1. 1. Starch gel electrophoresis associated with a specific staining method revealed the occurrence of four distinct peptidases in diploid and tetraploid O. americanus and three in O. cultripes. These enzymes can be distinguished on the basis of substrate specificity and electrophoretic mobility. 2. 2. The distribution of the different peptidases in diploid and tetraploid populations of O. americanus and O. cultripes tissues suggests homology among three of these peptidases. Mobility, activity and number of peptidases in diploid and tetraploid O. americanus are the same. 3. 3. Pep 3 of O. americanus, not detected in O. cultripes, seems to be a gene duplication product which arose after the separation of the evolving lines of the two species, since this peptidase is also detected in the diploid O. americanus. 4. 4. The results show an increase of locus number which, however, cannot be explained as locus duplication of previously duplicated genes by polyploidy. 5. 5. In terms of tissue distribution and substrate specificity, no homology between Odontophrynus and human peptidases could be assumed.

Ultra-estrutura das glândulas anexas ao ferrão de Camponotus rufipes (Fabricius) (Hymenoptera - Formicidae)

Abstract: As glândulas anexas ao ferrao de Camponotus rufipes sao bem desenvolvidas e compostas de uma glândula acida com tres regioes distintas: dois filamentos livres, uma regiao convoluta formada por um tubo resultante da uniao dos dois filamentos, extremamente dobrado e um reservatorio, e alem desta uma glândula basica em forma de saco bifido. A ultra-estrutura dessas glândulas mostrou que a glândula acida apresenta celulas de origem ectodermica que formam o reservatorio e uma intima que coleta a secrecao das celulas secretoras que formam um epitelio em torno dos filamentos livres e tubulo convoluto. As celulas secretoras, provavelmente tambem de origem ectodermica, tem maior atividade na regiao livre dos filamentos, onde o Golgi e muito desenvolvido e secrecao de baixa densidade eletronica se acumula em vacuolos. A secrecao e coletada por canaliculos que se originam na intima e percorrem cavidades resultantes da invaginacao de sua membrana plasmica, providas de microvilosidades. Na porcao convoluta, a “secrecao” presente, parece se originar de modificacoes dos mitocondrios. A glândula basica e tambem de origem ectodermica. Nas formigas estudadas acha-se provavelmente em degeneracao.

The Ultrasonic attenuation due to Cu+ substitutional ions in KCl

Abstract: The ultrasonic attenuation in KCl single crystals doped with Cu+ is measured from 80 to 300 K with several frequencies in the MHz range. The shape factor of the elastic dipole tensor is found to be 0·077. The parameters for dipole relaxation τ = 10−13 s and H = 0·175 eV are in agreement with previous ITC measurements. Die Ultraschalldampfung in mit Cu+ dotierten KCl-Einkristallen wird zwischen 80 und 300 K bei verschiedenen Frequenzen im MHz-Bereich gemessen. Der Formfaktor des elastischen Dipol-tensors wird zu 0,077 bestimmt. Die Parameter der Dipolrelaxation τ = 10−13 s und H = 0,175 eV sind in Ubereinstimmung mit fruheren ITC-Messungen.