Incubation

About: Incubation is a research topic. Over the lifetime, 5748 publications have been published within this topic receiving 126541 citations.

The Effects of Reducing Conditions, Medium, pH, Temperature, and Time on in Vitro Excystation of Cryptosporidium

Abstract: . Whereas excystation of sporozoites from oocysts of most coccidian species requires exposure to reducing conditions followed by pancreatic enzymes and bile salts, sporozoites of a bovine isolate of Cryptosporidium excysted without exposure to either reducing conditions or to pancreatic enzymes and bile salts. Without prior exposure to reducing conditions, a high percent excysted after incubation in a mixture of trypsin and bile salts in Ringer's solution; fewer excysted after incubation in tap water, even fewer after incubation in salt solutions, and none after incubation in saliva. Excystation, generally greater at pH 7.6 than at pH 6.0 and at 37°C than at 20°C, was observed as early as 1 h after incubation in water or the trypsin-bile mixture. These findings provide circumstantial evidence that oocysts of Cryptosporidium can excyst in extraintestinal sites and liberate sporozoites that can initiate autoinfection.

Influence of Temperature of Incubation and Type of Growth Medium on Pigmentation in Serratia marcescens

Abstract: Maximal amounts of prodigiosin were synthesized in either minimal or complete medium after incubation of cultures at 27 C for 7 days. Biosynthesis of prodigiosin began earlier and the range of temperature for formation was greater in complete medium. No prodigiosin was formed in either medium when cultures were incubated at 38 C; however, after a shift to 27 C, pigmentation ensued, provided the period of incubation at 38 C was not longer than 36 hr for minimal medium or 48 hr for complete medium. Washed, nonpigmented cells grown in either medium at 38 C for 72 hr could synthesize prodigiosin when suspended in saline at 27 C when casein hydrolysate was added. These suspensions produced less prodigiosin at a slower rate than did cultures growing in casein hydrolysate at 27 C without prior incubation at 38 C. Optimal concentration of casein hydrolysate for pigment formation by suspensions was 0.4%; optimal temperature was 27 C. Anaerobic incubation, shift back to 38 C, killing cells by heating, or chloramphenicol (25 mug/ml) inhibited pigmentation. Suspensions of washed cells forming pigment reached pH 8.0 to 8.3 rapidly and maintained this pH throughout incubation for 7 days. Measurements of viable count and of protein, plus other data, indicated that cellular multiplication did not occur in suspensions of washed cells during pigment formation. By this procedure utilizing a shift down in temperature, biosynthesis of prodigiosin by washed cells could be separated from multiplication of bacteria.

Temperature‐sensitive periods of sex determination in a lizard: Similarities with turtles and crocodilians

Abstract: The sex of leopard geckoes is determined by incubation temperature. This study identified their temperature-sensitive period of sex determination by incubating embryos at a male-producing temperature (32°C) and a female-producing temperature (26°C) for various intervals of development and comparing the sex ratios from the different experiments. Eggs incubated at 26° for 14 days (to stage 32) could still develop as either sex, but eggs incubated 30 days (through stage 34) necessarily became female; incubation at 32° did not guarantee male development until 20 days of incubation (to stage 37). The temperature-sensitive period of irreversible sex determination therefore lies between stages 32–37 and occupies much of the first half of development. The temperature-sensitive period in geckoes is similar to those in turtles and alligators, which are only distantly related to geckoes, but the reasons for these similarities are obscure.

Regulation of alternative oxidase gene expression in soybean.

Abstract: Soybean (Glycine max cv. Stevens) suspension cells were used to investigate the expression of the alternative oxidase (Aox) multigene family. Suspension cells displayed very high rates of cyanide-insensitive respiration, but Aox3 was the only isoform detected in untreated cells. Incubation with antimycin A, citrate, salicylic acid or at low temperature (10 °C) specifically induced the accumulation of the Aox1 isoform. Aox2 was not observed under any conditions in the cells. Increases in Aox1 protein correlated with increases in Aox1 mRNA. Treatment of soybean cotyledons with norflurazon also induced expression of Aox1. Reactive oxygen species (ROS) were detected upon incubation of cells with antimycin, salicylic acid or at low temperature, but not during incubation with citrate. Aox1 induction by citrate, but not by antimycin, was prevented by including the protein kinase inhibitor staurosporine in the medium. The results suggest that multiple pathways exist in soybean to regulate expression of Aox genes and that Aox1 specifically is induced by a variety of stress and metabolic conditions via at least two independent signal transduction pathways.