Showing papers on "Incubation published in 1998"
TL;DR: The combined data suggest that energy starvation induces a response similar to that triggered by oligotrophy, which seems to play a key role in the observed phenomena of long-term survival and development of general stress resistance of starved cultures of E. faecalis.
Abstract: The ability of Enterococcus faecalis to metabolically adapt to an oligotrophic environment has been analyzed. E. faecalis is able to survive for prolonged periods under conditions of complete starvation established by incubation in tap water. During incubation in this microcosm, cells developed a rippled cell surface with irregular shapes. Exponentially growing cells survived to the same extent as cells starved for glucose prior to exposure to the multiple nutrient deficient stress. Chloramphenicol treatment during incubation in tap water led to a rapid decline in plate counts for exponentially growing cells but showed progressively reduced influence on stationary-phase cells harvested after different times of glucose starvation. During incubation in the oligotrophic environment, cells from the exponential-growth phase and early-stationary phase became progressively more resistant to other environmental stresses (heat [62°C], acid [pH 3.3], UV254 nm light [180 J/m2], and sodium hypochlorite [0.05%]) until they reached a maximum of survival characteristic for each treatment. In contrast, cells starved of glucose for 24 h did not become more resistant to the different treatments during incubation in tap water. Our combined data suggest that energy starvation induces a response similar to that triggered by oligotrophy. Analysis of protein synthesis by two-dimensional gel electrophoresis revealed the enhanced synthesis of 51 proteins which were induced in the oligotrophic environment. A comparison of these oligotrophy-inducible proteins with the 42 glucose starvation-induced polypeptides (J. C. Giard, A. Hartke, S. Flahaut, P. Boutibonnes, and Y. Auffray, Res. Microbiol. 148:27–35, 1997) showed that 16 are common between the two different starvation conditions. These proteins and the corresponding genes seem to play a key role in the observed phenomena of long-term survival and development of general stress resistance of starved cultures of E. faecalis.
156 citations
TL;DR: Incubation temperatures in loggerhead sea turtle (Caretta caretta) nests were examined as a method for predicting hatchling sex ratios and during the thermosensitive period, temperatures in the center of the egg mass were significantly higher than...
Abstract: Incubation temperatures in loggerhead sea turtle (Caretta caretta) nests were examined as a method for predicting hatchling sex ratios. Incubation temperatures were recorded in 40 nests that were laid on Hutchinson Island, Florida. Small temperature data loggers were placed directly in nests (in the center of the egg mass) and were programmed to record temperature every 1.2 h for the entire incubation period. Nests laid during the early, middle, and late portions of the peak nesting period (June and July) were examined. The nests were equally distributed on an untreated beach and a beach that had been artificially supplemented with sand to compensate for erosion. Three nests received multiple data loggers to assess temperature variation within the nest. The average daily temperatures within these nests varied from a maximum of 2.1°C at the top of the egg chamber to a minimum of 0.4°C at the bottom. During the thermosensitive period, temperatures in the center of the egg mass were significantly higher than...
88 citations
TL;DR: The data demonstrate the development of a protective redistribution of the cardiac output in response to hypoxia in the chick embryo from day 10 of incubation.
Abstract: 1 The fetus develops cardiovascular adaptations to protect vital organs in situations such as hypoxia and asphyxia These include bradycardia, increased systemic blood pressure and redistribution of the cardiac output The extent to which they involve maternal or placenta influences is not known The objective of the present work was to study the cardiac output distribution in response to hypoxia in the chick embryo, which is independent of the mother 2 Fertilized eggs were studied at three incubation times (10-13 days, 14-16 days and 17-19 days of a normal incubation time of 21 days) Eggs were placed in a Plexiglass box in which the oxygen concentration could be changed Eggs were opened at the air cell and a chorioallantoic vein was catheterized Cardiac output distribution was measured with 15 micron fluorescent microspheres injected during normoxia, during the last minute of a 5 min period of hypoxia and after 5 min of subsequent reoxygenation 3 Hypoxia caused a redistribution of the cardiac output in favour of heart (+17 to +160 % of baseline) and brain (+21 to +57 % of baseline) at the expense of liver (-3 to -65 % of baseline), yolk-sac (-46 to -77 % of baseline) and carcass (-6 to -33 % of baseline) 4 The magnitude of the changes in cardiac output distribution to the heart, brain, liver and carcass in response to hypoxia increased with advancing incubation time 5 The data demonstrate the development of a protective redistribution of the cardiac output in response to hypoxia in the chick embryo from day 10 of incubation
85 citations
TL;DR: It is concluded that different ventilation levels during incubation interact with total incubation time and thereby influence ascites susceptibility.
Abstract: Embryos from ascites sensitive (AS) and resistant lines (AR) were subjected during the third week of incubation to a high CO2 (0.4%) (HC) or normal CO2 level of 0.2% (NC) in the incubators. The effect on embryonic and hatching parameters and growth, ascites sensitivity and related physiological parameters was followed. At NC conditions AR embryos hatch earlier than AS ones but this difference completely disappeared under HC condition, since hatching time of the AS line was reduced. Moreover, AS embryos showed slightly lower T4 and T3 levels than AR embryos. Embryos of both lines incubated at HC had higher plasma T3 concentrations than those incubated at NC. Chickens that had been incubated at HC level showed less ascites mortality than those incubated at NC. RV/TV ratios were higher in NC birds compared with HC ones. It is concluded that different ventilation levels during incubation interact with total incubation time and thereby influence ascites susceptibility.
79 citations
TL;DR: Investigation of intraspecific variation in incubation behaviour of wild Eurasian kestrels in Finland found that patterns of hatching asynchrony could be predicted from patterns of incubation, consistent with the idea that females have much control over hatching patterns.
64 citations
TL;DR: In this paper, the suitability of different in vitro and in situ methods to estimate the extent and rate of degradation in the rumen of sun-cured hays with a crude protein and neutral-detergent fibre contents ranging from 57 to 207 kg −1 and 428 to 744kg −1 dry-matter (DM) respectively, were studied.
59 citations
TL;DR: Temperature was monitored in three natural nests, and oxygen and carbon dioxide partial pressure monitored in one natural nest of the broad-shelled river turtle, Chelodina expansa, throughout incubation, and after heavy rain during the last 3 months of incubation the nest became moderately hypoxic and hypercapnic for several successive days.
Abstract: Temperature was monitored in three natural nests, and oxygen and carbon dioxide partial pressure monitored in one natural nest of the broad-shelled river turtle, Chelodina expansa, throughout incubation. Nest temperature decreased after nest construction in autumn, remained low during winter and gradually increased in spring to a maximum in summer. In a nest where temperature was recorded every hour, temperature typically fluctuated through a 2 degrees C cycle on a daily basis throughout the entire incubation period, and the nest always heated faster than it cooled. Oxygen and carbon dioxide partial pressures in this nest were similar to soil oxygen and carbon dioxide partial pressures for the first 5 months of incubation, but nest respiratory gas tensions deviated from the surrounding soil over the last three months of incubation. Nest respiratory gas tensions were not greatly different from those in the atmosphere above the ground except after periods of rain. After heavy rain during the last 3 months of incubation the nest became moderately hypoxic (P-O2 similar to 100 Torr) and hypercapnic (P-CO2 similar to 50 Torr) for several successive days. These short periods of hypoxia and hypercapnia were not lethal.
59 citations
TL;DR: Time-dependent modifications of neutrophil oxidative metabolism seem to be correlated with intracellular concentrations, and might be related neither to azithromycin cellular toxicity, nor to superoxide scavenging properties.
Abstract: Several antimicrobial agents have already been investigated relating to their influence on neutrophil ROS generation. Azithromycin provides, a dose-related anti-oxidant effect, after 15 min incubation, with the stimulating agent FMLP, as well with PMA or S. aureus. This finding was however obtained with concentrations not considered in therapeutics. Since short incubation times are not representative of the physiological situation, and since azithromycin is characterized by prolonged high concentrations within phagocytes, the same experiments were performed over 2 and 4 h exposures. A time-dependent anti-oxidant effect was then reported. The maximum effect was obtained with PMA (IC50 were 856 and 30 micrograms/ml for 15 min and 4 h incubation times respectively). Time-dependent modifications of neutrophil oxidative metabolism seem to be correlated with intracellular concentrations. Depressed oxidative metabolism might be related neither to azithromycin cellular toxicity, nor to superoxide scavenging properties. By increasing exposure periods, therapeutic concentrations could therefore lead to an anti-inflammatory effect, potentially of clinical interest since associated with bacteriostatic activity.
54 citations
TL;DR: The Brisbane river turtle Emydura signata lays hard-shelled eggs and hatchling mass was unaffected by the amount of water gained or lost during incubation, and Hatchling mass and dimensions and total embryonic energy expenditure was directly proportional to initial egg mass.
Abstract: Incubation temperature and the amount of water taken up by eggs from the substrate during incubation affects hatchling size and morphology in many oviparous reptiles. The Brisbane river turtle Emydura signata lays hard-shelled eggs and hatchling mass was unaffected by the amount of water gained or lost during incubation. Constant temperature incubation of eggs at 24 degrees C, 26 degrees C, 28 degrees C and 31 degrees C had no effect on hatchling mass, yolk-free hatchling mass, residual yolk mass, carapace length, carapace width, plastron length or plastron width. However, hatchlings incubated at 26 degrees C and 28 degrees C had wider heads than hatchlings incubated at 24 degrees C and 31 degrees C. Incubation period varied inversely with incubation temperature, while the rate of increase in oxygen consumption during the first part of incubation and the peak rate of oxygen consumption varied directly with incubation temperature. The total amount of oxygen consumed during development and hatchling production cost was significantly greater at 24 degrees C than at 26 degrees C, 28 degrees C and 31 degrees C. Hatchling mass and dimensions and total embryonic energy expenditure was directly proportional to initial egg mass.
53 citations
TL;DR: The viability of the VNC (viable nonculturable) state was assessed by studying the reduction of tetrazolium salts INT (p‐iodonitrophenyl tetrazlium violet) and CTC (cyanoditolyl tetrazoium chloride) to their respective formazans and this was linked to the cellular respiration.
Abstract: Studies were conducted following the formation and characterization of the coccoid morphology of Helicobacter pylori. H. pylori ATCC43504 was incubated in brucella broth plus 2% fetal calf serum at three different temperatures: 37°C, room temperature and 4°C in a microaerophilic environment, and readings were taken at 2, 7, 15, 30 and 45 days. At control times, the total and the viable count, viability tests with tetrazolium salts, and ultrastructural studies were carried out. On solid media, H. pylori became nonculturable after 7 days of incubation at room temperature and 4°C, and after 15 days of incubation at 37°C. At these times of incubation, after subculturing in liquid medium under the same conditions, the growth of H. pylori was detected until the 15th day from cultures incubated at 4°C and until the 30th day from cultures stored at 37°C, and at room temperature. Ultrastructural studies showed a gradual reduction of integrity of bacterial cells that remained stable at 30 and 45 days of incubation: 30% of whole cells of bacteria incubated at 37°C and room temperature and 50% in bacteria incubated at 4°C. The viability of the VNC (viable nonculturable) state was assessed by studying the reduction of tetrazolium salts INT (p-iodonitrophenyl tetrazolium violet) and CTC (cyanoditolyl tetrazolium chloride) to their respective formazans and this was linked to the cellular respiration. At 45 days of incubation, when bacterial regrowth was not observed in solid or in liquid medium, different resuscitation methods were applied to evaluate a possible resuscitation of VNC H. pylori. No significant growth on solid medium was observed.
49 citations
TL;DR: Growth rates and survival of early juveniles were dependent upon incubation history, high growth being obtained only if rearing temperature exceeded the temperature of egg incubation, and temperature and growth efficiency were parabolic.
Abstract: The effects of temperature on the survival, growth rate and growth efficiency of larval and juvenile common wolffish, Anarhichas lupus L. were studied at 0–31 days and 9–12 months post-hatching, respectively. The influence of temperature regime during egg incubation on subsequent survival and growth was also examined. The fish were reared at constant water temperatures of 5, 8, 11 and 14°C, and all groups were fed dry pellets. At age 1 month, maximum growth rates were observed at 11 and 14°C. Growth rates and survival of early juveniles were dependent upon incubation history, high growth being obtained only if rearing temperature exceeded the temperature of egg incubation. In juveniles at age 9–12 months, the relationships between temperature and growth, and temperature and growth efficiency were parabolic: the optimum water temperatures for growth (Topt.G) and growth efficiency (Topt.GE) were 11°C and 9.7°C respectively. The growth rate and growth efficiency at these water temperatures were 0.9% day–1 and 0.45 g weight gain per g food offered, respectively. © Rapid Science Ltd. 1998
TL;DR: The results of the proposed three-compartment model indicate that the observed selectivity of accumulated porphyrins following topical application of ALA is mainly governed by an increased ALA penetration of the stratum corneum of the skin, an accelerated ALA uptake into the cell and a higher porphirin formation in tumour as compared to normal skin tissue, but not by a reduced ferrocheletase activity.
Abstract: The knowledge of the exact time course of a photosensitizer in tumour and surrounding host tissue is fundamental for effective photodynamic therapy (PDT) and fluorescence-based diagnosis. In this study the time course of porphyrin fluorescence following topical application of 5-aminolaevulinic acid (ALA) using different formulations, concentrations and incubation times has been measured in amelanotic melanomas (A-Mel-3) (n = 54) grown in transparent dorsal skinfold chambers of Syrian golden hamsters and in human basal cell carcinomas (BCCs) (n = 40) in vivo. To simulate the accumulation of ALA-induced protoporphyrin IX (Pp IX), a three-compartment model has been developed and rate constants have been determined. The kinetics of both the A-Mel-3 tumours and the BCCs show a significantly higher fluorescence intensity in tumour as compared to normal surrounding host tissue. Maximal fluorescence intensity in A-Mel-3 tumours as a percentage of the reference standard used occurs 150 min post incubation (p.i.) using a 1, 3 or 10% (vol.) ALA solution buffered to pH 7.4 and 1 h incubation time. After a 4 h incubation time maximal fluorescence intensity in tumour is measured shortly p.i. A concentration of 10% ALA does not increase the fluorescence intensity as compared to 3% ALA following 4 h incubation, but either 3 or 10% ALA yields a significantly higher fluorescence after 4 h incubation time as compared to 1 h. The fluorescence intensity following an 8 h incubation reaches its maximum directly p.i. for all concentrations and then decreases exponentially. The fluorescence intensity in the surrounding host tissue shows no statistically significant difference regarding concentration or incubation time. At least during the first hour p.i., the fluorescence intensity measured in the surrounding tissue is lower as compared to that in the tumour in all groups. 24 h after topical application hardly any fluorescence is detectable in tumour or surrounding host tissue in all experimental groups. Incubating human BCCs with a 20% ALA cream (water-in-oil emulsion) or a 20% ALA gel (containing 40% dimethyl sulfoxide) for approximately 2 h yields a similar fluorescence intensity directly after incubation for either cream or gel. However, while yielding a maximum 120 min p.i. with cream, the fluorescence intensity increases for a longer time (about 2-3 h p.i.) and up to higher values using the gel formulation. In surrounding normal skin, cream as well as gel formulation yields a similar fluorescence intensity directly after incubation. Afterwards the fluorescence intensity decreases slowly using the cream whereas a further increase of the fluorescence intensity is measured in the normal skin with a maximum 240 min p.i. using the gel formulation. The results of the proposed three-compartment model indicate that the observed selectivity of accumulated porphyrins following topical application of ALA is mainly governed by an increased ALA penetration of the stratum corneum of the skin, an accelerated ALA uptake into the cell and a higher porphyrin formation in tumour as compared to normal skin tissue, but not by a reduced ferrocheletase activity.
TL;DR: Prolonged or repeated exposures were more toxic than a single one hour exposure, but due to the higher sensitivity to prolonged exposure of several tumor cell lines, prolonged treatment yielded a more favorable in vitro therapeutic index.
TL;DR: The in vitro effect of progressive oxygen decrease on the growth and morphology of Helicobacter pylori was studied and clusters were progressively larger, depending on the reduction of oxygen concentration, since the aggregation phenomenon can be the expression of a hypothesized mechanism of protection among bacterial cells.
Abstract: The in vitro effect of progressive oxygen decrease on the growth and morphology of Helicobacter pylori was studied. H. pylori ATCC 43504 was used for the experiments. The strain inoculated in Brucella broth plus fetal calf serum was incubated under a controlled atmosphere with oxygen concentration from 5 to 0%. CFU ml−1 and bacterial morphology were detected at the time of spreading and at 24 h, 72 h, 7 days and 14 days. A detailed ultrastructural investigation of the bacterial cells, grown in different experimental conditions, was performed by scanning electron microscopy. Oxygen deprivation produced a rapid reduction of CFU ml−1. In particular, a significant reduction of viable bacteria was recorded at 72 h of incubation in the presence of 1% oxygen and anaerobiosis, and 0 CFU ml−1 was found after 7 days of incubation at the above mentioned oxygen concentrations. The coccoid phenotype was already prevalent after 24 h of incubation with a progressive tendency to aggregate in clusters. These clusters were progressively larger, depending on the reduction of oxygen concentration, since the aggregation phenomenon can be the expression of a hypothesized mechanism of protection among bacterial cells.
TL;DR: Both the loss of L-selectin expression on CD34 cells occurring upon freeze–thawing, the emergence of apoptosis, as well as the recovery of L -selectinexpression on non-apoptotic cells varies largely between individual leucapheresis samples, and therefore it is concluded that such processes should be considered when correlations with clinical outcome after transplantation are made.
Abstract: Several studies have pointed out that L-selectin on CD34-positive cells plays a role in haematopoietic reconstitution after peripheral blood stem cell (PBSC) transplantation. Since it is known that a decrease in L-selectin expression in lymphocytes and granulocytes can be induced by a variety of stress situations, we have investigated in this study whether the freeze-thawing procedure, used in PBSC transplantation, would affect L-selectin expression on CD34+ stem cells. Flow cytometry was performed by labelling the cells with anti-CD34 (HPCA2 PE) and anti-CD62L (FMC46 FITC). The leucapheresis procedure itself caused a slight decrease of L-selectin expression on CD34 cells in 11 out of 12 cases (mean decrease of the percentage of positive cells 11.9; range 6-23). A much larger decrease was found upon freeze-thawing: a mean of 39% (range 4-78% in 27 cases) compared to fresh material. To determine if L-selectin expression might be up-regulated after cryopreservation, thawed transplant samples (n = 11) were incubated at 37 degrees C in RPMI with 10% FCS at 5% CO2. Already early in the course of incubation two CD34-positive populations appeared in the blast region, characterized by either a low or high forward scatter. Simultaneous viability staining with the DNA dye 7-Amino Actinomycin D and the DNA/RNA dye Syto16 revealed that the population with low forward scatter was apoptotic while the population with the high forward scatter was non-apoptotic. The latter population is considered to be most relevant for transplantation. In this population an increase of L-selectin expression after overnight incubation was observed in 8/11 samples up to values of 46-120% of the values of the fresh nonfrozen samples. In addition, the mean fluorescence intensity was significantly increased in 10/11 cases. Kinetic experiments with shorter incubation times revealed that only part of the leucapheresis samples (two out of 8) showed an increase of L-selectin expression within 4 h. In addition, a decrease of L-selectin expression was found upon CD34 purification from fresh leucapheresis material by magnetic isolation (decrease ranging from 59 to 92%, n = 5). In contrast to frozen samples, L-selectin reappearance was seen already within 4 h of incubation in all samples. Both the loss of L-selectin expression on CD34 cells occurring upon freeze-thawing, the emergence of apoptosis, as well as the recovery of L-selectin expression on non-apoptotic cells varies largely between individual leucapheresis samples, and therefore it is concluded that such processes should be considered when correlations with clinical outcome after transplantation are made.
TL;DR: For all treatment types, there was a clear shift in the CLPP during decomposition; during incubation, the relative utilization of carbohydrates decreased and the usage of amino acids increased respectively.
Abstract: Microbial biomass, basal respiration, and community level physiological profiles (CLPP) based on substrate utilization were studied during the decomposition of maize litter under different simulated soil management systems. Laboratory experiments were conducted on agricultural soil samples from Denmark, Germany, and Italy. Maize litter was either placed on soil surface (mulched) or mixed into soil (incorporated) to simulate two soil management types: tillage and no-tillage. Control samples lacking maize litter were also investigated. All soil samples were incubated at 14°C for 52 weeks. Microbial parameters were assessed after 2, 4, 8, 16, 32, and 52 weeks of incubation. During incubation, we found a significant decrease in microbial biomass C in the soils amended with litter. For all treatment types, there was a clear shift in the CLPP during decomposition; during incubation, the relative utilization of carbohydrates decreased and the usage of amino acids increased respectively. After 52 weeks of incubation, the CLPP from all treatment types were very similar.
TL;DR: Redhead females exhibited one of the lowest incubation constancy among duck species (Anatidae), coupled with a comparatively high number of incubation recesses per day, and was higher for older females and for females of lower body mass and was lower on days with higher maximum daily temperatures.
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.
TL;DR: It is revealed that severe aberrations occurring at early stages may recover and malformations occurringAt early blastula stages should be used with prudence and not as a direct and consistent indicator of poor egg viability.
TL;DR: It is argued that in nature the incubation of eggs around the pivotal temperature is probably more frequent than generally recognized and leads to either phenotypic adult females or phenotypesic adult males, even though the embryonic testis may present various degrees of intersexuality, including ovotestes as documented in artificial incubation.
Abstract: Most turtles have temperature-dependent sex determination. With the intention to preserve endan- gered and threatened species, two management tools have been suggested: artificial incubation at either male- or female-producing temperatures and introduction of many more females than males into popula- tions by manipulating incubation temperatures to favor the production of female embryos. The use of estro- gens during incubation has also been proposed to induce the development of females. We argue that in na- ture the incubation of eggs around the pivotal temperature is probably more frequent than generally recognized and leads to either phenotypic adult females or phenotypic adult males, even though the embry- onic testis may present various degrees of intersexuality, including ovotestes as documented in artificial incu- bation. Observations of the turtle Emys orbicularis show that, after hatching, ovotestes tend to evolve into tes- tes by regression, total or partial, of the ovarian-like cortex. Testes with some immature oocytes at their surface have been observed in adult turtles, and they produce spermatozoa. Therefore, gonadal intersexuality apparently does not hinder the reproductive male function in adults. We draw attention to the danger of es- trogenic treatment of embryos to produce females. In many cases, such treatment induces thin gonads ("hy- pogonads") in which the volume of both cortex and medulla are reduced. Exogenous estrogens may also re- sult in the arrest of lengthening of the Mullerian ducts and sometimes in the opening of their caudal end in the Wolffian ducts. Either process results in the inability of adult females to evacuate eggs from oviducts. We modeled the long-term effects of introducing in a population a strongly female-biased primary sex ratio (20 females to 1 male) for 30 years. Taking into account a genetic component of sex determination, as exempli- fied by the results of incubation at pivotal temperature, such a manipulation favors masculinizing alleles. When the manipulation is stopped, the primary sex ratio, as well as the adult sex ratio, becomes male- biased—a result contrary to that expected—and the population size decreases. We recommend actions that protect adult populations and nesting sites and that improve the natural conditions of incubation in these sites rather than attempts to manipulate sex ratios.
TL;DR: There is no evidence of temperature compensation in growth or development during embryonic development of E. signata eggs by incubating eggs of the Brisbane river turtle Emydura signata under four different temperature regimes, constant temperatures of 24°C and 31°C throughout incubation, and two swapped‐tempera‐ture treatments where incubation temperature was changed approximately halfway through incubation.
Abstract: Freshwater turtle eggs are normally subjected to fluctuations in incubation temperature during natural incubation. Because of this, developing embryos may make physiological adjustments to growth and metabolism in response to incubation at different temperatures. I tested this hypothesis by incubating eggs of the Brisbane river turtle Emydura signata under four different temperature regimes, constant temperatures of 24 degrees C and 31 degrees C throughout incubation, and two swapped-temperature treatments where incubation temperature was changed approximately halfway through incubation. Incubation at 31 degrees C took 42 d, and incubation at 24 degrees C took 78 d, with intermediate incubation periods for the swapped-temperature treatments. Hatchling mass, hatchling size, and total oxygen consumed during development were similar for all incubation regimes. The pattern of oxygen consumption during the last phase of incubation as reflected by rate of increase of oxygen consumption, peak oxygen consumption, and fall in oxygen consumption before hatching was determined solely by the incubation temperature during the last phase of incubation; that is, incubation temperature during the first phase of incubation had no influence on these factors. Thus there is no evidence of temperature compensation in growth or development during embryonic development of E. signata eggs.
TL;DR: Evidence is presented that incubation temperature affects emergence and post-hatching behavior of pine snakes that could influence survival in the weeks before hibernation and hatchlings from nests with low incubation temperatures could be expected to have lower survival in nature.
Abstract: Incubation temperature in ectothermic vertebrates affects incubation periods, and in some reptiles it affects sex ratios and behavior. I present evidence that incubation temperature affects emergence and post-hatching behavior of pine snakes (Pituophis melanoleucus) that could influence survival in the weeks before hibernation. Hatchlings incubated at low temperatures remained in the nest longer, had fewer alternate nest openings, and fewer underground tunnels to hide in than did hatchlings from warmer temperatures. These conditions could render hatchlings from low-temperature nests more vulnerable to predation because, if a nest is opened, they are not inside tunnels where they would be protected. Hatchlings from nests incubated at low temperatures took longer to find shade during a thermoregulation test, and were less likely to move about in search of other cover than were those from higher-incubation-temperature artificial nests. Similarly, hatchlings from nests with low incubation temperatures were less responsive to a predatory stimulus and had a longer latency to strike than other hatchlings. Taken together, hatchlings from nests with low incubation temperatures might be less able to avoid predators and find shade than those from nests incubated at higher temperatures, and thus could be expected to have lower survival in nature.
TL;DR: The toxic effects of incubation under 95%O2:5%CO2 on human spermatozoa result from increased endogenous ROS production, mostly from leukocytes, and high ROS levels inhibit sperm function, with the stimulated acrosome reaction being more susceptible than motility parameters.
Abstract: incubated under 95%N2:5%CO2 (P < 0.001, repeated measures analysis of variance), but the degree of inhibition did not increase after more prolonged incubation periods (up to 6 h). The addition of the antioxidants catalase and superoxide dismutase prevented the inhibitory effect of 95%O2:5%CO2. Leukocyte removal from samples prior to 95%O2:5%CO2 incubation preserved the ability of the spermatozoa to acrosome react. Sperm motility parameters were less affected by 95%O2:5%CO2 but track velocity was 64.1 mm/s K 1.96 after 2 h incubation under 95%N2:5%CO2 compared with 54.7 mm/s K 1.41 after 2 h incubation under 95%O2:5%CO2 (P < 0.05, repeated measures analysis of variance). Sperm samples that did not generate detectable ROS were not affected by 95%O2:5%CO2. The toxic effects of incubation under 95%O2:5%CO2 on human spermatozoa result from increased endogenous ROS production, mostly from leukocytes. High ROS levels inhibit sperm function, with the stimulated acrosome reaction being more susceptible than motility parameters.
TL;DR: The effects of laboratory incubation on P form distribution and phosphomonoesterase activity in a forest soil recently affected by a wildfire were compared with its effects on these properties of an unburnt soil from an adjacent plot as mentioned in this paper.
Abstract: The effects of laboratory incubation on P form distribution and phosphomonoesterase activity in a forest soil recently affected by a wildfire (B) were compared with its effects on these properties of an unburnt soil from an adjacent plot (UB). Samples of surface (0–5 cm) and subsurface (5–10 cm) layers of both soils were incubated at 75% field capacity and 28°C for 11 wk. After 0, 1, 2, 4, 6 and 11 weeks, samples were withdrawn and fractionated and the P contents of fractions from corresponding layers were compared. The 0–5 cm layer was most severely affected by the fire, which caused oxidation of organic P (P o ) and a marked decrease in the content of residual P (P r ). The major process occurring during the incubation of this layer was microbial immobilization of inorganic P (P i ) in organic forms. By contrast, the 5–10 cm layer behaved similarly to the UB soil during incubation: essentially, P r was transformed into rapid turnover P o (NaHCO 3 -extractable P o +NaOH-extractable P o ), and P i was occluded. After destruction of the enzyme due to burning, both layers of the B soil exhibited a very low initial rate of phosphomonoesterase activity. The failure of the enzyme activity to increase during incubation coincided with high labile P i concentrations, suggesting that microbial synthesis of new phosphomonoesterase enzyme was repressed.
TL;DR: The weights and characteristics of the Pectoralis superficialis, Semimembranosus, and Gastrocnemius of male and female chicken embryos at 16 and 20 d of incubation suggest that the muscles of male embryos have more but smaller, myofibers than females, which may be responsible for the sex difference in embryo weight and provide the framework for the greater posthatching muscle growth.
TL;DR: Only active immunization using GST-tPRL induced higher antibody titers as well as full prevention of incubation behavior expression in turkey hens, indicating that such a pharmacological approach is of great practical interest, although its uses need to be carefully evaluated under commercial conditions.
TL;DR: It is suggested that the observed suspension of embryonic development was the result of a temperature dependent reduction in metabolism according to a Q10∼2, which is typical of an ectothermic organism.
Abstract: The effect(s) of finite exposure(s) to 22.0 °C on embryo weight gain, 3rd tarsus length, transfer of lipid from the yolk and uptake of specific lipid components by the liver, were measured in the chick embryo. Embryo growth was completely suspended over the period of temperature reduction, but resumed unimpaired when the optimum temperature of 37.5 °C was restored. Two successive periods of embryonic exposure to 22.0 °C (36 h at d 3 followed by 24 at d 10) were additive in their effect on growth retardation. Embryos subjected to temperature reductions on d 3 of incubation displayed significant changes in lipid concentrations and polyunsaturated fatty acid profiles within the liver when measured at d 18 of incubation. Yolk lipid uptake was significantly reduced but not suspended by embryonic exposure to 22.0 °C. It is suggested that the observed suspension of embryonic development was the result of a temperature dependent reduction in metabolism according to a Q10∼2, which is typical of an ectothermic organism.
TL;DR: TIRFS measurements are suggested to be an appropriate tool for the examination of the plasma membrane‐associated photosensitizer fraction in living cells.
Abstract: Fluorescence spectra, fluorescence decay kinetics, photobleaching kinetics and photodynamic efficacy of protoporphyrin IX (PP) were investigated in endothelial cells in vitro after different incubation times. Fluorescence spectra and photobleaching kinetics were determined during total internal reflection (TIR) illumination or epi-illumination. Because penetration depth of the excitation light during TIR illumination was limited to about 100 nm, plasma membrane-associated PP was almost selectively examined. Spectra obtained by TIR fluorescence spectroscopy (FS) showed a very low background, whereas spectra obtained by epi-illumination exhibited considerable background by autofluorescence and scattered light. For photobleaching kinetics during TIR illumination after 1 h or 24 h incubation, a biexponential fluorescence decrease was observed with a rapidly and a slowly bleaching portion. After 1 h incubation, the rapidly bleaching portion was the predominant fraction, whereas after 24 h incubation comparable relative amounts of the rapidly and slowly bleaching portion were determined. The rapidly and slowly bleaching portion were assigned to PP monomers and aggregated species in close vicinity to the plasma membrane. Fluorescence decay measurements after epi-illumination support the decrease of PP monomers within the whole cell with increasing incubation time. In contrast to TIR illumination, photobleaching of PP during epi-illumination was characterized by slow monoexponential fluorescence decrease after 1 h or 24 h incubation. Photodynamic efficacy of PP using epi-illumination was found to depend strongly on incubation time. Considerable cell inactivation was determined for short incubation times (1 h or 3 h), whereas photodynamic efficacy was diminished for longer incubation times. Reduced photodynamic efficacy after long incubation times was assigned to the lower amount of photodynamically active monomers determined close to the plasma membrane as well as within the whole cell. In conclusion, TIRFS measurements are suggested to be an appropriate tool for the examination of the plasma membrane-associated photosensitizer fraction in living cells.
TL;DR: The effect of the incubation temperature on heat resistance was constant at all heating temperatures tested and the higher heat resistance of cells grown at higher temperatures was not due to a greater capacity of heat damage repair.
Abstract: This paper examines the influence of growth temperature on thermal resistance of Listeria monocytogenes A TCC 15313. Regardless of the incubation temperature, the heat resistance of Listeria monocytogenes increased during incubation until the stationary phase of growth was reached. The maximum heat resistance of cells grown at 4C, 20C or 3 7C was attained after 14 days, 36 h and 18 h of incubation, respectively. After longer incubation times the heat resistance of cells grown at 4C and 20C did not change but that of cells grown at 37C decreased. The maximum heat resistance was usually greater at higher incubation temperatures. However, the magnitude of these differences depended on the pH and composition of heating media. By raising the incubation temperature from 4C to 3 7C, the D 62 value in pH 7 citrate-phosphate buffer increased from 0.13 to 0.34 min. However, when skimmed milk was used as menstruum this difference was not observed. Cells grown at 37C attained maximum heat resistance at pH 7 but those grown at 4C, at pH 6. The magnitude of the effect of the incubation temperature on heat resistance was constant at all heating temperatures tested (z = 6 ± 0.8C). The higher heat resistance of cells grown at higher temperatures was not due to a greater capacity of heat damage repair.
TL;DR: Results suggest that in addition to rapid embryonic development, cowbirds hatch before many hosts by disrupting incubation of smaller eggs and, possibly hatching early in response to stimuli from host eggs.
Abstract: Brown-headed Cowbird (Molothrus ater) eggs in natural nests hatch either before or at the same time as Yellow Warbler (Dendroica petechia) eggs despite being almost twice the size. Cowbird eggs may hatch before Yellow Warbler eggs because they (1) prolong the incubation of host eggs, (2) have more rapid embryonic development, or (3) hatch in response to stimuli from host eggs. We tested these hypotheses by comparing the incubation periods of cowbird eggs incubated in natural nests, incubated artificially in isolation from other eggs, and incubated artificially in clutches of Yellow Warbler eggs. Cowbird eggs incubated artificially in isolation from other eggs took significantly longer to hatch than either artificially incubated warbler eggs or naturally incubated cowbird eggs. The ratio of incubation period to egg volume was less for cowbirds than warblers, which indicates that cowbird embryos develop more rapidly relative to their size. The presence of a cowbird egg in natural nests significantly prolonged the incubation period of warbler eggs. Therefore, cowbird eggs appear to disrupt the incubation of smaller host eggs. Finally, the incubation periods of cowbird eggs incubated artificially in contact with warbler eggs were shorter, but not significantly so, than cowbird eggs incubated in isolation from other eggs. These results suggest that in addition to rapid embryonic development, cowbirds hatch before many hosts by disrupting incubation of smaller eggs and, possibly hatching early in response to stimuli from host eggs.
TL;DR: It is shown that it is possible to attain acceptable survival rates up to juvenile stage 2, even when eggs have been detached at the earliest time, in such a way that artificial incubation is used for more than three-quarters of the total duration of the embryonic development.
Abstract: One of the main limiting factors in the use of artificial incubation techniques on crayfish farms has been the widespread belief that eggs should be stripped from females in the late stages of embryogenesis. In order to disprove this idea, three different times for egg removal were tested in white-clawed crayfish, Austropotamobius pallipes (Lereboullet): (1) just before the gastrulation process (mean degree days= 335, 34 days after spawning); (2) when the embryo was between the closing of the blastopore and the appearance of mandibular rudiments (mean degree days= 524, 56 days after spawning); and (3) when the embryo had thoracic appendage rudiments (mean degree days= 810, 92 days after spawning). The results showed that it is possible to attain acceptable survival rates up to juvenile stage 2 (51%), even when eggs have been detached at the earliest time (34 days after spawning), in such a way that artificial incubation is used for more than three-quarters (75.7%) of the total duration of the embryonic development. Factors such as the incubation device, water quality and incubation conditions have a major influence on the success of the process. Finally, a critical period was observed during the last stages of development in the present study, particularly between the eyed stage and juvenile stage 2, with mortality rates of between 26.7% and 56%.