Biologia Celular

Biologia Celular

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Alarcon M.V.,Hortofruticultura | Lloret P.G.,Biologia Celular | Salguero J.,Fisiologia Vegetal
Plant signaling & behavior | Year: 2014

Auxin and ethylene have been largely reported to reduce root elongation in maize primary root. However the effects of auxin are greater than those caused by ethylene. Although auxin stimulates ethylene biosynthesis through the specific increase of ACC synthase, the auxin inhibitory effect on root elongation is not mediated by the auxin-induced increase of ethylene production. Recently it has been demonstrated that root inhibition by the application of the synthetic auxin NAA (1-naphtalenacetic acid) is increased if combined with the ethylene precursor ACC (1-aminocyclopropane-1-carboxilic acid) when both compounds are applied at very low concentrations.   Root elongation is basically the result of two processes: a) cell divisions in the meristem where meristematic cells continuously generate new cells and b) subsequently polarized growth by elongation along the root axis as cells leave the meristem and enter the root elongation zone. Our results indicate that exogenous auxin reduced both root elongation and epidermal cell length. In a different way, ethylene at very low concentrations only inhibited root elongation without affecting significantly epidermal cell length. However, these concentrations of ethylene increased the inhibitory effect of auxin on root elongation and cell length. Consequently the results support the hypothesis that ethylene acts synergistically with auxin in the regulation of root elongation and that inhibition by both hormones is due, at least partially, to the reduction of cell length in the epidermal layer.

Bonfleur M.L.,Biologia Celular | Vanzela E.C.,Biologia Celular | Ribeiro R.A.,Biologia Celular | de Gabriel Dorighello G.,Biologia Celular | And 5 more authors.
Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids | Year: 2010

We investigated whether primary hypercholesterolaemia per se affects glucose homeostasis and insulin secretion in low-density lipoprotein receptor knockout mice (LDLR -/-). Glucose plasma levels were increased and insulin decreased in LDLR -/- compared to the wild-type mice. LDLR -/- mice presented impaired glucose tolerance, but normal whole body insulin sensitivity. The dose-response curve of glucose-stimulated insulin secretion was shifted to the right in LDLR -/- islets. Significant reductions in insulin secretion in response to l-leucine or 2-ketoisocaproic acid were also observed in LDLR -/-. Islet morphometric parameters, total insulin and DNA content were similar in both groups. Glucose uptake and oxidation were reduced in LDLR -/- islets. Removal of cholesterol from LDLR -/- islets corrected glucose-stimulated insulin secretion. These results indicate that enhanced membrane cholesterol content due to hypercholesterolaemia leads to a lower insulin secretion and glucose intolerance without affecting body insulin sensitivity. This represents an additional risk factor for diabetes and atherosclerosis in primary hypercholesterolaemia. © 2009 Elsevier B.V. All rights reserved.

Sanchez-Calvo J.M.,Hospital Of Jerez | Barbero G.R.,University of Cádiz | Guerrero-Vasquez G.,University of Cádiz | Duran A.G.,University of Cádiz | And 4 more authors.
Medicinal Chemistry Research | Year: 2016

The synthesis of 1,4-naphthoquinone derivatives is of great interest since these compounds exhibit strong activity as antimalarial, antibacterial, antifungal and anticancer agents. A series of 50 naphthoquinone derivatives was synthesized and evaluated for antibacterial and antifungal activity against Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Candida krusei, Candida parapsilosis and Cryptococcus neoformans using the broth microdilution method. The Candida species were the most susceptible microorganisms. Halogen derivatives of 1,4-naphthoquinone presented strong activity, e.g., 2-bromo-5-hydroxy-1,4-naphthoquinone, which exhibited inhibition at an MIC of 16 µg/mL in S. aureus, and 2-chloro-5,8-dihydroxy-1,4-naphthoquinone, with an MIC of 2 µg/mL in C. krusei. These compounds showed higher activity against fungi, but the antibacterial activities were very low. The study of structure–activity relationships is very important in the search for new antimicrobial drugs due to the limited therapeutic arsenal. © 2016 Springer Science+Business Media New York

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