Incubation

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

Release of Free Fatty Acids and Loss of Hill Activity by Aging Spinach Chloroplasts

Abstract: The free fatty acid content of spinach chloroplasts, isolated at pH 5.8 to 8.0, has been found to vary between 3.1 and 5.5% of the total chloroplast fatty acids. When chloroplasts were incubated at room temperature for 2 hours, the free fatty acids increased by 42% and the Hill activity decreased by 70%. After 2 hours of incubation at 37°, the free fatty acids increased about 3-fold and the Hill activity decreased to almost 0. The addition of crystalline bovine serum albumin largely prevented the loss of Hill activity at room temperature and at 5°, but had little effect during incubation at 37°. Both the release of free fatty acids and the loss of Hill activity were pH dependent. The losses were the least during incubation at pH 5.8 and the greatest during incubation at pH 8.0. The major free fatty acids released at pH 5.8 were saturated, while those released at pH 7.0 or 8.0 were mainly the unsaturated acids, α-linolenic acid and hexadecatrienoic acid.

The Influence of Female Age, Body Mass, and Ambient Conditions on Redhead Incubation Constancy

Abstract: Incubation constancy, i.e., the proportion of time on the nest, of female Red-heads (Aythya americana) was examined during the summers of 1995 and 1996 in relation to female age, body mass, and ambient conditions. Redhead females exhibited one of the lowest incubation constancy (82%) among duck species (Anatidae), coupled with a comparatively high number of incubation recesses per day. Low constancy was not due to excessive disturbance at the nest or reduced maternal investment in the clutch, but was probably related to energetic constraints of the female imposed by laying parasitic eggs prior to nesting. As in most other duck species, incubation constancy decreased over the incubation period. Age, mass, and maximum daily temperature, and the interactions of initiation day X age and mass X date significantly influenced daily incubation constancy. Constancy was higher for older females and for females of lower body mass and was lower on days with higher maximum daily temperatures.

Multiple mechanisms of reversed hatching asynchrony in rockhopper penguins

Abstract: Brood reduction in birds is frequently associated with hatching asynchrony, wherein incubation commences before clutch completion, causing last-laid eggs to hatch after earlier eggs. In crested penguins (Eudyptes spp.), second-laid eggs typically hatch before first-laid eggs, but the mechanisms behind this reversal are unknown. Through a multifactor field experiment with rockhopper penguins (Eudyptes chrysocome Forster 1781), I examined several factors that might influence incubation length : laying order (smaller first-laid eggs vs. larger second-laid eggs) ; incubation onset (exposure to immediate vs. delayed incubation) ; intraclutch dimorphism (incubated with an equal-sized vs. larger nest mate) ; laying date ; egg mass ; and egg composition (yolk and albumen content). Three of these factors - laying order, intraclutch dimorphism and laying date-contributed significantly to variation in incubation length ; first-laid eggs produced early in the season and incubated with a larger nest mate took longest to hatch. Differences in incubation onset did not contribute to incubation length when tested independently. The albumen content of both first and second eggs increased in proportion to fresh egg mass, but egg mass had no effect on incubation length. Although Eudyptes parents can potentially adjust the degree of hatching asynchrony through variation in egg position, the effects of laying date and laying order are probably beyond facultative control. Together, these effects may contribute to the unique reversal in both hatching asynchrony and egg-size dimorphism characteristic of crested penguins.