RESUMO
We report on a rapid, 32-channel reflectance-difference (RD) spectrometer with sub-second spectra acquisition times and ΔR/R sensitivity in the upper 10(-4) range. The spectrometer is based on a 50 kHz photo-elastic modulator for light polarization modulation and on a lock-in amplifier for signal harmonic analysis. Multichannel operation is allowed by multiplexing the 32 outputs of the spectrometer into the input of the lock-in amplifier. The spectrometer spans a wavelength range of 230 nm that can be tuned to cover E(1) and E(1) + Δ(1) transitions for a number of III-V semiconductors at epitaxial growth temperatures, including GaAs, InAs, AlAs, and their alloys. We present two examples of real-time measurements to demonstrate the performance of the RD spectrometer, namely, the evolution of the RD spectrum of GaAs (001) annealed at 500 °C and the time-dependent RD spectrum during the first stages of the epitaxial growth of In(0.3)Ga(0.7)As on GaAs (001) substrates.
RESUMO
Evidence is presented that treating the Drosophila female with chlorophyllin (CHLN) has a marked effect on the yield of dominant lethals induced by the irradiation of sperm. The yield is significantly greater in the embryonic period (between the egg and the first instar) and is significantly reduced in postembryonic stages compared with a sucrose control.
Assuntos
Clorofilídeos/farmacologia , Drosophila/embriologia , Drosophila/genética , Protetores contra Radiação/farmacologia , Espermatozoides/efeitos da radiação , Animais , Drosophila/efeitos dos fármacos , Feminino , Larva/efeitos dos fármacos , Masculino , Sacarose/farmacologiaRESUMO
The effect of chlorophyllin (CHLN) on the mutagenicity of four monofunctional alkylating agents (MFAAs) was evaluated in the wing spot test in Drosophila. Three of the compounds are direct-acting (ethylnitrosamine (ENU), methylnitrosourea (MNU), and methylmethanesulfonate (MMS)) and one indirect-acting (diethylnitrosamine, DEN). Results indicate that the mutagenicity of all four compounds is strongly inhibited by CHLN. The findings are not in agreement with the conclusion of Romert et al. (1992) that CHLN has no effect on the mutagenicity of direct acting MFFAs inferred from their work with MNU and ethylmethanesulfonate (EMS) in the V79 and Salmonella in vitro test systems. The results suggest the possibility that the action of CHLN need not include an inhibiting effect on metabolic activation.
Assuntos
Alquilantes/toxicidade , Antimutagênicos/farmacologia , Clorofilídeos/farmacologia , Drosophila/efeitos dos fármacos , Animais , Dietilnitrosamina/toxicidade , Relação Dose-Resposta a Droga , Drosophila/genética , Drosophila/metabolismo , Etilnitrosoureia/toxicidade , Feminino , Masculino , Metanossulfonato de Metila/toxicidade , Metilnitrosoureia/toxicidade , Mutagênese , Testes de Mutagenicidade , Asas de Animais/efeitos dos fármacosAssuntos
Ácido Ascórbico/farmacologia , Compostos de Cromo/farmacologia , Drosophila/efeitos dos fármacos , Raios gama , Mutagênese/efeitos dos fármacos , Animais , Drosophila/efeitos da radiação , Recombinação Genética/efeitos dos fármacos , Asas de Animais/efeitos dos fármacos , Asas de Animais/patologiaRESUMO
The sibling species Drosophila melanogaster and D. simulans were collected at Laguna Verde, Veracruz, Mexico. D. melanogaster was found in significantly greater frequency than was D. simulans. Ten isofemale lines of each species were tested for egg to adult viability, desiccation resistance, and vagility. D. melanogaster surpassed D. simulans in all three characteristics. The findings are discussed with reference to the climatic conditions at Laguna Verde and the expected effect of such an environment on the relative frequencies of these species. The dichotomous results in regard to desiccation resistance and vagility that were observed between recently collected D. melanogaster and the Oregon-R laboratory stock of that species are also discussed.
Assuntos
Drosophila melanogaster/genética , Drosophila/genética , Animais , Dessecação , Drosophila/isolamento & purificação , Drosophila/fisiologia , Drosophila melanogaster/isolamento & purificação , Drosophila melanogaster/fisiologia , Feminino , Locomoção , Masculino , México , Densidade Demográfica , Especificidade da EspécieRESUMO
With the worldwide proliferation of nuclear power plants has come the need to study the biological effects of the operation of the reactors on surrounding populations. We have begun a long-term study of the sibling species Drosophila melanogaster and D. simulans in the area of Laguna Verde in the state of Veracruz in Mexico. Laguna Verde, on the Gulf of Mexico about 75 km north of the city of Veracruz, is the location of the country's first nuclear power plant. This plant has not yet gone "on-line." The species have been collected from two sites, one of which is south of the reactor and is in the path of the prevailing north to south wind flow. The other collecting site is west of the plant. The species are being studied for the following: species frequency, desiccation resistance, vagility, proportion of larvae pupating, pupation height, and egg to adult survival after irradiation. To date we have noted both spatial and seasonal differences in a number of these characteristics. The information being gathered will serve as base-line data for monitoring the future operation of the nuclear power plant.
Assuntos
Drosophila/efeitos da radiação , Reatores Nucleares , Centrais Elétricas , Animais , Drosophila/genética , Feminino , Genética Populacional , Masculino , México , Pupa/efeitos da radiaçãoRESUMO
Four new gene arrangements of chromosome 3 of Drosophila pseudoobscura are reported, as well as an updated phylogenetic sequence of the inversion polymorphism in this species. Evidence that the Tree Line gene arrangement of chromosome 3 was the original form in D. pseudoobscura, and that Central Mexico is the center of distribution of this species is discussed.
Assuntos
Inversão Cromossômica , Drosophila/genética , Polimorfismo Genético , Animais , Mapeamento Cromossômico , Feminino , Masculino , México , Filogenia , Especificidade da EspécieRESUMO
We present in this paper two cases of auto-immune hemolytic anemie caused by ingestion of alpha-metildope Coombs' test positive. We suggest to make Coombs test to every patient in whose treatment has been included the use of alpha-metildope.
Assuntos
Anemia Hemolítica Autoimune/induzido quimicamente , Metildopa/efeitos adversos , Administração Oral , Adulto , Anemia Hemolítica Autoimune/imunologia , Climatério/efeitos dos fármacos , Teste de Coombs , Feminino , Humanos , Hipertensão/tratamento farmacológico , Masculino , Metildopa/administração & dosagem , Pessoa de Meia-IdadeRESUMO
Drosophila pseudoobscura populations of Central Mexico are chromosomally highly polymorphic. Five gene arangements in the third chromosome are endemic, including the two newly described in the present article. The phylogenetic tree of the gene arrangements known in the species is shown in Figure 1. The ones found in Central Mexico all belong to the Santa Cruz "phylad", while in the northern part of the species area both Santa Cruz and Standard phylads are widespread. Some inferences concerning the evolutionary history of the species are presented.