ABSTRACT
The aim of this research was to analyze the effect of different temperatures on physiological quality and relate the responses with the antioxidant activity of three lots of corn seeds. The seeds from three lots were exposed for 24h at temperatures of 15, 25, 35 and 40°C and then evaluated for percentage, speed index and first germination count, as well as early growth and activity of antioxidant enzymes in the seedlings. The experimental design was completely randomized with four replications, with subsequent polynomial regression analysis. The results showed that the seeds from the three lots of corn exposed to temperatures of 15 and 40°C, were of better high physiological quality (vigor), which explains the low activity of enzymes of the antioxidant defense system in these same temperatures. The antioxidant defense system is related to the physiological quality of corn seeds exposed to thermal stress.
O objetivo neste trabalho foi analisar o efeito de diferentes temperaturas na qualidade fisiológica e relacionar com a atividade antioxidante de três lotes de sementes de milho, as quais foram expostas por 24h às temperaturas de 15, 25, 35 e 40°C e, após, avaliadas quanto à porcentagem, índice de velocidade e primeira contagem de germinação, como também crescimento inicial e atividade de enzimas antioxidantes nas plântulas. O delineamento experimental foi inteiramente casualizado, com quatro repetições, com posterior análise de regressão polinomial. Os resultados evidenciaram que as sementes dos três lotes de milho, expostas às temperaturas de 15 e 40°C, foram de melhor qualidade fisiológica (vigor), o que explica a baixa atividade das enzimas do sistema de defesa antioxidante nessas mesmas temperaturas. O sistema de defesa antioxidante tem relação com a qualidade fisiológica de sementes de milho expostas ao estresse térmico.
ABSTRACT
In their journey through the oviduct some subpopulations of sperm are preserved in a reservoir, while others are negatively selected. Sperm binding glycoprotein (SBG) is a pig oviductal epithelial cell glycoprotein that produces, under capacitating conditions, acrosome alteration, p97 tyrosine-phosphorylation and reduction of the motility of sperm. In this paper, we show that SBG is accessible at the extracellular surface of the oviductal epithelial cells, supporting a sperm interaction biological role in situ. We analyze the possible dependence of the tyrosine-phosphorylation of p97 on the PKA mechanism, finding that apparently it is not PKA dependent. Also, after SBG treatment the phosphorylated proteins locate mainly at the detached periacrosomal region and at the tail of sperm; the latter may be related to SBG's motility reduction effect. The study of the time course effect of SBG on sperm as detected by chlortetracycline (CTC) staining and of its binding to sperm by immunodetection in conjunction with CTC, shows results in agreement with the hypothesis that this glycoprotein is involved in the alteration of acrosomes in a specific sperm subpopulation. The results suggest that SBG may be part of a mechanism for negative selection of sperm.
Subject(s)
Animals , Female , Male , Oviducts/metabolism , Seminal Plasma Proteins/physiology , Sperm Capacitation/physiology , Spermatozoa/physiology , Sus scrofa , Sperm-Ovum Interactions/physiologyABSTRACT
Chlortetracycline (CTC) fluorescent pattern, the ability to undergo acrosome reaction (AR) upon exposure to 10 µM calcium ionophore A23187 and vitality estimation were used to investigate the effect of the sulfated glycosaminoglycan heparin on the in vitro capacitation of porcine spermatozoa. Sperm incubation in capacitating medium (CM) supplemented with 10 mM heparin for up to 120 min, showed an increase in the number of capacitated sperm (B pattern) and acrosome reacted sperm (AR pattern), without affecting their viability. In this condition, spermatozoa were incubated in CM depleted of albumin, calcium, bicarbonate or combinations, in the presence of heparin. In either calcium or bicarbonate-free media, capacitation was only basal and did not show variations in the presence of heparin. In absence of albumin the presence of calcium and bicarbonate stimulated capacitation, which was further increased by the addition of heparin. These results suggest that heparin enhances in vitro capacitation of porcine sperm only under capacitating conditions. Additionally, when sperm were incubated with 100 µg/ml biotinylated heparin in the presence or absence of unlabeled heparin, we observed that heparin binding sites were located mostly on the acrosomal region of boar sperm in an specific and saturable manner. The in vitro effect of heparin described in this work indicates that sulfated glycosaminoglycans, which are normally present in the female reproductive tract, might play an important role in the fertilization process in porcines.
Subject(s)
Animals , Male , Heparin/pharmacology , Sperm Capacitation/drug effects , Spermatozoa/physiology , Chlortetracycline , Coloring Agents , Microscopy, Fluorescence , Sus scrofaABSTRACT
Se determina la actividad queratinolítica de cepas de Microsporum fulvum, aisladas de suelos de praderas, cuando se desarrollan sobre un sustrato queratinoso, con y sin aplicación de los herbicidas preemergentes: Atrazina, Metribuzín y Alachlor. De acuerdo a la valoración de los productos de reducción por sulfitólisis durante el proceso queratinolítico, éste se estimula al actuar Atrazina, sobre el sustrato de prueba, y está disminuído en el caso de Metribuzín y Alachlor
Subject(s)
In Vitro Techniques , Keratins , Microsporum , Soil Microbiology , ArgentinaABSTRACT
El objetivo de este trabajo es conocer la acción ejercida por concentraciones crecientes de herbicidas de presiembra (Metribuzin, Atrazina y Alachlor) sobre el crecimiento y la capacidad germinativa de Microsporum fulvum, Microsporum gypseum y Keratinomyces ajelloi. Comprobamos un efecto depresivo e inhibitorio de los biocidas sobre la germinación y el crecimiento de las cepas en estudio. Alachlor es el que presenta mayor poder inhibitorio y en menor grado Metribuzin y Atrazina. Además, comprobamos que eta acción ocurre sólo cuando los hongos se ponen en contacto con los herbicidas en medio de Sabouraud glucosa, que aparentemente los haría más disponibles a los propágulos fúngicos. Estos resultados nos indican la importancia que tienen, las interrelaciones entre distintas sustancias, en los efectos producidos sobre la micota de los suelos, resultando de que en estas experiencias nos aproximamos cada vez más a las condiciones presentes en los habitat naturales
Subject(s)
Arthrodermataceae/growth & development , Fungi/drug effects , Herbicides , In Vitro Techniques , Microsporum/growth & development , Soil Microbiology , Argentina , AtrazineABSTRACT
Informamos el primer aislamiento de Trichophyton georgiae y su forma sexuada Arthroderma ciferii en nuestro país. Se realizaron observaciones morfológicas, pruebas bioquimicas e inoculaciones experimentales en cobayos. Destacamos el hallazgo de este hongo en suelos de corrales de aves que presentó una elevada capacidad saprofítica competitiva en sustratos con queratinas provenientes de plumas. Además no produjo las lesiones típicas de los dermatofitos patógenos en cobayos y fue incapaz de crecer a 31-C