RESUMEN
Arbuscular mycorrhizal (AM) fungi are key components of most agricultural ecosystems. Therefore, understanding the impact of agricultural practices on their community structure is essential to improve nutrient mobilization and reduce plant stress in the field. The effects of five different organic or mineral sources of phosphorus (P) for a maize-soybean rotation system on AM fungal diversity in roots and soil were assessed over a 3-year period. Total DNA was extracted from root and soil samples collected at three different plant growth stages. An 18S rRNA gene fragment was amplified and taxa were detected and identified using denaturing gradient gel electrophoresis followed by sequencing. AM fungal biomass was estimated by fatty acid methyl ester analysis. Soil P fertility parameters were also monitored and analyzed for possible changes related with fertilization or growth stages. Seven AM fungal ribotypes were detected. Fertilization significantly modified soil P flux, but had barely any effect on AM fungi community structure or biomass. There was no difference in the AM fungal community between plant growth stages. Specific ribotypes could not be significantly associated to P treatment. Ribotypes were associated with root or soil samples with variable detection frequencies between seasons. AM fungal biomass remained stable throughout the growing seasons. This study demonstrated that roots and soil host distinct AM fungal communities and that these are very temporally stable. The influence of contrasting forms of P fertilizers was not significant over 3 years of crop rotation.
Asunto(s)
Biodiversidad , Fertilizantes , Glycine max/microbiología , Micorrizas/efectos de los fármacos , Raíces de Plantas/microbiología , Microbiología del Suelo , Zea mays/microbiología , Análisis por Conglomerados , ADN de Hongos/química , ADN de Hongos/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Hongos , Genes de ARNr , Datos de Secuencia Molecular , Micorrizas/clasificación , Micorrizas/genética , Filogenia , ARN de Hongos/genética , ARN Ribosómico 18S/genética , Análisis de Secuencia de ADNRESUMEN
Normal human synovial cells are cultivated in vitro; they actively multiply and fibroblast-like cells with structural characteristics of intermediate synoviocytes are obtained. In view of analyzing some functional aspects of this cell line, their endocytotic capacities have been studied. They also have been cultivated in a medium deprived of serum; a new cell type develops ("dendritic cells"). The latter are analyzed (cell division, endocytosis). As a comparison, human pulmonary fibroblasts (W I 38 line) and mouse macrophages are cultivated and studied under the same experimental conditions.
Asunto(s)
Membrana Sinovial/citología , Técnicas de Cultivo , Endocitosis , Humanos , Membrana Sinovial/crecimiento & desarrolloRESUMEN
A new thiopyrimidine derivative has been synthesized. It can inhibit cell multiplication in Chick embryo fibroblasts, in Mouse Ehrlich ascites tumor cells and in Rat hepatoma cells (line Rueber) cultivated in vitro.
Asunto(s)
Mitosis/efectos de los fármacos , Pirimidinas/farmacología , Compuestos de Sulfhidrilo/farmacología , Animales , Carcinoma de Ehrlich/tratamiento farmacológico , Embrión de Pollo , Depresión Química , Fibroblastos/efectos de los fármacos , Técnicas In Vitro , Neoplasias Hepáticas Experimentales/tratamiento farmacológico , Ratones , Pirimidinas/uso terapéutico , Ratas , Relación Estructura-Actividad , Compuestos de Sulfhidrilo/uso terapéuticoAsunto(s)
Antineoplásicos/farmacología , Carcinoma de Ehrlich/tratamiento farmacológico , Fibroblastos/efectos de los fármacos , Animales , Antineoplásicos/uso terapéutico , Carcinoma de Ehrlich/ultraestructura , Pollos , ADN/análisis , ADN/biosíntesis , Histocitoquímica , Ratones , ARN/análisis , ARN/biosíntesis , RatasRESUMEN
Chick embryo fibroblasts cultivated in vitro and Ehrlich ascites tumor cells (in vivo or in vitro) have been treated with amphotericin B. Cell multiplication is strongly inhibited. Large clear zones appear in the fibroblast nucleoi (phase-contrast and electron-microscope observations). Many treated fibroblasts and tumour cells have a high DNA content (pre-mitotic or polyploid level; measurements by cytophotometry). However, the RNA content (cytophotometry) and the total protein content (cytophotometry and micro-interferometry) are relatively low in the tumour cells. As shown by autoradiography, DNA synthesis is active but RNA synthesis and, in some cases, protein synthesis are inhibited. Due to this unbalanced growth, the cells cannot divide.