Incubation

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

Incubation temperature affects hatchling growth but not sexual phenotype in the Chinese soft-shelled turtle, Pelodiscus sinensis (Trionychidae)

Abstract: Eggs of Pelodiscus sinensis were incubated under one fluctuating and four constant temperatures, and hatchlings from different incubation temperatures were maintained under identical conditions to assess the effects of incubation temperature on sexual phenotype and hatchling growth. The incubation length decreased as temperature increased, but it did not differ between sexes within each temperature treatment. Hatching success was higher at intermediate temperatures (28 ◦ C, 30 ◦ Ca nd the fl uctuating temperature regime) than at low (24 ◦ C) and high (34 ◦ C) temperatures. The sex ratio of hatchlings did not differ from equality within each temperature treatment. Thus, our data support previous work that P. sinensis does not have temperature-dependent sex determination, and add evidence for the prediction that turtles within the Trionychidae have genotypic sex determination exclusively. Incubation temperature affected hatchling mass, with hatchlings from intermediate incubation temperatures being heavier than those from low (24 ◦ C) and high (34 ◦ C) incubation temperatures. Hatching size was not a predictor of post-hatching growth. Incubation temperature affected hatchling growth, with hatchlings from 24 ◦ Co verall growing faster than did hatchlings from higher incubation temperatures. The influence of incubation temperature on hatchling growth was well buffered within the range of constant temperatures from 28 ◦ Ct o 34 ◦ C. Fluctuating incubation temperatures augmented male growth but reduced female growth, as female embryos were more vulnerable to extremely high temperatures.

17β-Estradiol modulates endothelin-1 expression and release in human endothelial cells

Abstract: Objective: In this study the role of 17β-estradiol (E2) in the regulation of endothelin-1 (ET-1) mRNA expression and secretion was investigated in cultured human umbilical vein endothelial cells (HUVECs). Methods: Endothelial cells were either deprived of or treated with 17β-estradiol (10−9, 10−7 M) for 48 h. After the incubation, the effect of E2 on ET-1 gene expression was evaluated by Northern blot analysis. ET-1 release into the media was measured by radioimmunoassay after 6 h of incubation under basal conditions and upon stimulation with thrombin (4 U/ml). In addition, the cyclic guanosine 5′-monophosphate (cGMP) content of cells was assayed by immunoassay. In order to exclude the role of nitric oxide (NO) in E2-induced effects on endothelin-1 gene expression and secretion, nitric oxide synthase (NOS) inhibitor, N -nitro l-arginine methyl ester (1 mM) (l-NAME) was added to the media of some cultures. Results: Incubation of HUVECs with 10−9 and 10−7 M E2 for 48 h resulted in a 30 and 47% inhibition of ET-1 mRNA expression, respectively. Incubation with E2 also decreased the basal and thrombin-stimulated ET-1 release while increasing the cGMP content of cells significantly. NOS inhibitor l-NAME increased the release of ET-1 from E2-incubated cells but did not alter the ET-1 release from hormone-deprived cells. However, ET-1 secretion of E2-treated cells were significantly less than the deprived ones. Northern blot analyses also demonstrated that inhibition of NOS only partly attenuated the effect of E2 on ET-1 gene expression. In the presence of l-NAME, treatment with 10−7 M E2 caused a 12% decrease in ET-1 gene expression. Conclusion: The results demonstrate that E2 may play both direct and indirect role in regulation of ET-1 gene expression and production in human endothelial cells. E2-induced increase in NO but decrease in ET-1 production may partly explain the mechanism of the protective effects of the hormone on the cardiovascular system.

Incubation temperature influences survival in a small passerine bird

Abstract: In birds parental incubation behaviour is an important factor shaping the environmental conditions under which the embryos develop, and sub-optimal incubation temperatures are known to negatively affect early growth and development. It is less well known if variation in incubation temperature can impose life-long differences in individual performance and survival. In the present study we investigated the effects of incubation temperature on long-term survival in a small passerine bird. Using our captive population of the zebra finch Taeniopygia guttata we artificially incubated eggs at three biologically relevant temperatures (35.9, 37.0 and 37.9°C) for two-thirds of the incubation period and then monitored individual lifespan of the hatched chicks for two and a half years. We found that individuals from eggs incubated under the lowest temperature exhibited significantly lower long-term survival compared to those which had been incubated at the highest temperature. Our results show that incubation temperature in birds, and thus parental incubation behaviour, play an important role in shaping the life-history trajectories of offspring.

Cyclic AMP and amine effects on phosphorylation of specific protein in abdominal ganglion of Aplysia californica; localization and kinetic analysis

Abstract: Incubation of abdominal ganglia, obtained from Aplysia californica weighing 120--260 g, with octopamine or serotonin led to marked increases in cAMP (cyclic adenosine 3′,5′-monophosphate) levels after 10 min of incubation; these increases were blocked by phentolamine and methysergide, respectively. Incubation for 21 hr with octopamine also produced an elevation in cAMP levels but prolonged incubation with serotonin did not. Both these amines increased incorporation of 32P or 33P into a specific protein with apparent molecular weight of 118,000, upon incubation with the ganglion for 21 hr. The selective effect on this phosphoprotein was previously shown to be blocked by phentolamine (for octopamine effect) or methysergide (for serotonin effect) and could be mimicked by addition of dibutyryl cAMP to the medium. Incubation for more than 15 hr was required to generate a stable phosphoprotein pattern in which 5 phosphoprotein peaks could be reliably identified on polyacrylamide gels. With shorter incubations there was marked variability between ganglia with respect to the proteins which incorporated radioactive phosphate. The dibutyryl cAMP effect on phosphorylation of specific protein could not be demonstrated with incubations shorter than 15 hr. The specific effect on the phosphoprotein with molecular weight 118,000 was not observed in a number of large identified cells removed from the ganglion after 21 hr of incubation with radioactive phosphate and dibutyryl cAMP. The effect was also not observed in connective nerves and the bag cell clusters, but was consistently present in that portion of the ganglion remaining after these dissections. Upon subcellular fractionation the phenomenon was not observed in a crude nuclear fraction but was consistently present in a crude mitochondrial fraction. All these results are consistent with the possibility that the change in phosphoprotein metabolism produced by dibutryl cAMP may be localized in the neuropil, which contains all the synaptic contacts in this ganglion.

Incubation as a Reproductive Cost in Female Wood Ducks

Abstract: -We investigated the effects of body mass of incubating female Wood Ducks (Aix sponsa) on aspects of their current and future reproduction, and we examined factors that affect length of the incubation period. During three breeding seasons, body mass of female Wood Ducks averaged 578.0 g early and 553.3 g late in the incubation period. Body mass at the start of incubation was not related to either hatching success or length of the incubation period. In one of three years, females that were heavy at the end of incubation survived better to the next breeding season than those that were light. Reduced survival of light females in one year coincided with a greater loss of body mass in that year relative to other years, which indicates that incubation can be an important reproductive cost to female Wood Ducks. There were no relationships between body mass at the end of incubation and date of nesting or clutch size in the next breeding season. Partial correlations between clutch mass and length of incubation that controlled for date of nesting indicated a positive association between clutch mass and incubation length in every year. This relationship was evident only for parasitic nests (i.e. nests in which more than one female was laying eggs). Increased length of the incubation period associated with larger clutch mass represents a potential cost of intraspecific nest parasitism not previously recognized. Received 26 December 1989, accepted 17 June 1990. INCUBATING birds must provide the proper thermal environment for embryonic development. Simultaneously they must maintain their body condition so that survival and subsequent reproduction are not affected adversely. Time for feeding is restricted during incubation, which often makes it difficult for incubating individuals to meet daily metabolic costs (see Drent et al. 1985). Some avian species have adjusted to the demands of incubation by having biparental incubation (Eisner 1960, Feare 1984). In other species, males provide incubating females with food (Lyon and Montgomerie 1985, Nilsson and Smith 1988). In waterfowl (Anatidae), females of large-bodied species generally begin incubation with large energy reserves and are more attentive during incubation than females of small-bodied species, because largebodied females spend less time feeding (review in Afton and Paulus 1990). Small anatids depend on exogenous foods to meet most metabolic demands during incubation and take two 2 Present address: Maryland Department of Natural Resources, P.O. Box. 68, Wye Mills, Maryland 21679 USA. to three recesses each day to forage (Afton 1980, Hohman 1986). Successful development of bird eggs occurs within a relatively narrow range of incubation temperatures (White and Kinney 1974). Cooling of eggs increases as ambient temperature decreases, and as time away from the nest by incubating individuals increases (Caldwell and Cornwell 1975, Afton 1979). Short-term declines in egg temperature, however, apparently have little effect on hatching success (Vleck 1981, Haftorn 1988). Nevertheless, a decrease in average egg temperature may lengthen the incubation period, which exposes the nest to greater risk of predation and increases the energy expended by developing embryos (Vleck et al. 1980, Booth 1987). Greater amounts of energy used by embryos of precocial species before hatching may decrease the size of residual yolk reserves that are important to newly hatched chicks for maintenance and growth (Peach and Thomas 1986). Many species of birds modify activity patterns during incubation in response to variation in weather and food availability (Caldwell and Cornwell 1975, Cartar and Montgomerie 1985, 756 The Auk 107: 756-764. October 1990 This content downloaded from 157.55.39.124 on Mon, 16 Jan 2017 18:11:55 UTC All use subject to http://about.jstor.org/terms October 1990] Incubation Costs of Wood Ducks 757 Drent et al. 1985). Large-bodied species are affected less by environmental factors than smallbodied species (Afton 1980). Flexibility of incubation patterns within and among species suggests there is a tradeoff between maintaining body condition during incubation and providing eggs with a suitable environment for development. If time and energy constraints are important during incubation, then attentiveness at the nest should increase as body condition or food availability increases, assuming that greater attentiveness shortens the incubation period and increases hatching success (Martin 1987). Several studies support this idea. Aldrich and Raveling (1983) reported that female Canada Geese (Branta canadensis moffitti) that began incubation in good condition spent more time on the nest and had shorter incubation periods than females in poor condition. In years when food was abundant, European Starlings (Sturnus vulgaris) spent less time feeding, and some females were able to incubate without assistance from their mates (Drent et al. 1985). Female Blue Tits (Parus caeruleus) that were given a food supplement during incubation had shorter incubation periods and greater hatching success than females that were not provisioned (Nilsson and Smith 1988). Loss of body mass during incubation may reflect the need to provide constant care for developing embryos (Sherry et al. 1980), or it may enable females to reduce wingloading and to conserve energy during brood rearing (Freed 1981). However, a critical body mass certainly exists for individuals during incubation. Below that threshold, birds either spend more time feeding (Aldrich and Raveling 1983) or they abandon the nest (Drent 1975, Ankney and MacInnes 1978, Jones 1987). Body mass of female waterfowl during the annual cycle typically is lowest at the end of incubation (Afton and Paulus 1990). Ability of individuals to balance the conflicting demands of incubation may influence current and future reproductive suc-