Incubation

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

Physiological Characterization of Viable-but-Nonculturable Campylobacter jejuni Cells

Abstract: Campylobacter jejuni is a pathogenic, microaerophilic, gram-negative, mesophilic bacterium. Three strains isolated from humans with enteric campylobacteriosis were able to survive at high population levels (10(7) cells ml-1) as viable-but-nonculturable (VBNC) forms in microcosm water. The VBNC forms of the three C. jejuni strains were enumerated and characterized by using 5-cyano-2,3-ditolyl tetrazolium chloride-4',6-diamino-2-phenylindole staining. Cellular volume, adenylate energy charge, internal pH, intracellular potassium concentration, and membrane potential values were determined in stationary-phase cell suspensions after 48 h of culture on Columbia agar and after 1 to 30 days of incubation in microcosm water and compared. A notable increase in cell volume was observed with the VBNC state; the average cell volumes were 1.73 microliter mg of protein-1 for the culturable form and 10.96 microliter mg of protein-1 after 30 days of incubation in microcosm water. Both the internal potassium content and the membrane potential were significantly lower in the VBNC state than in the culturable state. Culturable cells were able to maintain a difference of 0.6 to 0.9 pH unit between the internal and external pH values; with VBNC cells this difference decreased progressively with time of incubation in microcosm water. Measurements of the cellular adenylate nucleotide concentrations revealed that the cells had a low adenylate energy charge (0.66 to 0.26) after 1 day of incubation in microcosm water, and AMP was the only nucleotide detected in the three strains after 30 days of incubation in microcosm water.

The influence of natural incubation environments on the phenotypic traits of hatchling lizards

Abstract: Laboratory studies have shown that incubation environments can affect mor- phological and behavioral phenotypes of hatchling lizards, but the relevance of this result to natural populations remains unclear. We monitored thermal regimes during the incubation period in 19 natural nests of scincid lizards (Bassiana duperreyi) in montane southeastern Australia, and experimentally translocated eggs among nests to remove the confounding of "nest of origin" (including genetic) factors with incubation conditions. We removed the eggs from the field shortly before hatching, and assessed the hatchlings' phenotypes (body size, shape, locomotor performance). Most of the effects seen after laboratory incubation were also seen after incubation in natural nests. Hatchling phenotypes were affected by incubation conditions as well as by "nest of origin" factors and an interaction between the two. Both the mean and the variance of incubation temperatures affected hatchling phenotypes, with male and female hatchlings differing in their norms of reaction. We found no evidence that a female's choice of nest site depends on the specific norms of reaction of her own offspring. Overall, incubation temperatures induced approximately half as much variance in hatchling phenotypes as did "nest-of-origin" effects. We conclude that incu- bation-induced phenotypic plasticity in hatchling reptiles may be important in the natural environment, as well as in the laboratory.

Patterns of Metabolism and Growth in Avian Embryos

Abstract: Metabolic rates of embryos of precocial birds increase rapidly until about 80% through incubation, then increase slowly remain constant or even decline. In altricial species, embryo metabolic rates increase continuously and at an accelerating rate through out incubation. Total energy cost of development is higher in precocial than in altricial species. Growth patterns of altricial and precocial embryos differ in the same way as does metabolic rate. Embryo growth rates decline late in incubation in precocial species, but increase continuously in altricial species. Embryo metabolic rate in cal/hr (P) is related to embryo mass in grams (M) and growth rate in grams/day (GR) by the equation P = 12.17GR + 1.66M + 1.81. The energy cost of growth in avian embryos is 292 cal/g. The energy cost of maintenance is 1.66 cal/g hr and appeals to be independent of embryo mass. Differences in growth patterns account for the observed differences in metabolic rates and total energy costs of development. High energy costs of maintenance account for high total developmental costs in piecocial species and in species that have unusually long incubation periods.

Experimental cooling during incubation leads to reduced innate immunity and body condition in nestling tree swallows

Abstract: Nest microclimate can have strong effects that can carry over to later life-history stages. We experimentally cooled the nests of tree swallows (Tachycineta bicolor). Females incubating in cooled nests reduced incubation time and allowed egg temperatures to drop, leading to extended incubation periods. We partially cross-fostered nestlings to test carry-over effects of cooling during incubation on nestling innate constitutive immunity, assessed through bacteria killing ability (BKA) of blood. Nestlings that had been cooled as eggs showed a lower ability to kill bacteria than control nestlings, regardless of the treatment of their foster mother. However, there was no effect of treatment of rearing females on nestling BKA in control nestlings, even though cooled females made significantly fewer feeding visits than did control females. This suggests that the effect of cooling occurred during incubation and was not due to carry-over effects on nestling condition. Nestlings that were exposed to experimental cooling as embryos had lower residual body mass and absolute body mass at all four ages measured. Our results indicate that environmental conditions and trade-offs experienced during one stage of development can have important carry-over effects on later life-history stages.