Modeling incubation temperature: the effects of incubator design, embryonic development, and egg size

A simple model to describe the relationship between the temperature of the developing embryo, incubator temperature, embryo heat production, and thermal conductivity of the egg and surrounding air is presented. During early incubation, embryo temperature is slightly lower than incubator temperature because of evaporative cooling. However, from midincubation onwards, metabolic heat production from the embryo raises embryo temperature above incubator temperature. The extent of the rise in embryo temperature depends on thermal conductivity, which, in turn, is mainly influenced by the air speed over the egg. The importance of air speed and restrictions to air flow within artificial incubators is discussed. Exact determinations of optimum incubation temperatures from studies reported in the literature are difficult because only incubator temperatures are reported. Embryo temperatures can differ from incubator temperature because of differences in thermal conductivity between different incubation systems and differences between incubators in their ability to control temperatures uniformly. It is suggested that shell surface temperatures are monitored in experiments to investigate temperature effects to allow consistent comparisons between trials. Monitoring shell temperatures would also make it easier to translate optimum temperatures derived in small experimental incubators to the large commercial incubators used by the poultry industry. The relationship between egg temperature, the metabolism of the developing embryo and egg size is discussed.     

Heart rate during development in the turtle embryo: effect of temperature

Growth and development can occur over a wide range of physical conditions in reptiles. Cardiovascular function must be critical to this ability. However, information on cardiovascular function in developing reptiles is lacking. Previous work indicated that in reptiles the effects of temperature on growth and metabolism are largely restricted to early development. This study examined whether the previously observed effects of temperature and different perinatal patterns of metabolism observed in amniotic vertebrates are correlated with cardiovascular function. Embryonic and hatchling carcass mass, heart mass and heart rate (HR) were compared for snapping turtle eggs (Chelydra serpentina) incubated at 24 degrees and 29 degrees C. Incubation time was shorter at 29 degrees C (56.2 days) than at 24 degrees C (71.1 days). Carcass and heart growth showed a sigmoidal pattern at both temperatures. However, cardiac growth showed a relative decrease as incubation proceeded. Incubation temperature significantly affected the HR pattern during development. The HR of embryos incubated at 24 degrees C was constant for most of incubation (51.8 +/- 4.8 min-1). A small decrease was observed just prior to and a large decrease immediately following hatching (posthatch, 22.3 +/- 4.1 min-1). At 29 degrees C embryonic HR was greater than at 24 degrees C early in development (72.3 +/- 3 min-1). The HR steadily decreased to values equivalent to those at 24 degrees C. The HRs of 24 degrees C and 29 degrees C hatchlings were not different. Cardiac output (estimated as the product of heart mass and HR) increased rapidly during early development and then slowed dramatically at both temperatures. These data are consistent with the suggestion that temperature exerts its effects primarily early in development. Furthermore, the changes in cardiovascular function are correlated with metabolic changes in hatching vertebrates.     

Oviposition and incubation environmental effects on embryonic diapause in a ground cricket

PURPOSE: Recent studies document the value of early combined modality therapy of small cell lung cancer, but also indicate that early thoracic radiation adds to myelosuppression and can complicate further chemotherapy. Other studies indicate that simultaneous use of growth factors with thoracic radiation may be deleterious. However, temporal separation of growth factor use from cytotoxic therapy may allow dose intensity to be maintained/enhanced during combined modality treatment. We sought to integrate filgrastim into a novel chemoradiation regimen for patients with limited small cell lung cancer using an approach that separated growth factor administration from both chemotherapy and thoracic radiation. METHODS AND MATERIALS: Twenty-seven patients with limited disease small cell lung cancer were enrolled in a Phase I trial of cisplatin, ifosfamide/mesna, oral etoposide, and thoracic radiation (1.5 Gy b.i.d. x 30 fractions days 1-19 cycle 1) +/- filgrastim (5 microg/kg/day). Filgrastim was given on days 20-25 of cycle 1 after completion of radiation and following completion of oral etoposide in subsequent cycles. The primary end point was determination of maximum tolerated dose (MTD) of chemotherapy. Serial cohorts were treated with and without filgrastim. RESULTS: Because of dose-limiting thrombocytopenia, primarily, and nonhematologic toxicity, the MTDs with and without filgrastim were identical (cisplatin 20 mg/m2 i.v. and ifosfamide 1200 mg/m2 i.v., both given days 1-3, and etoposide 40 mg/m2 p.o. days 1-14). Filgrastim use shortened the duration of neutropenia at the MTD (median 4 vs. 7 days), but was not associated with a reduction in febrile neutropenia. Although growth factor administration did not allow dose escalation of this regimen, it did allow chemotherapy doses to be maintained at the MTD more frequently through four cycles of therapy. In the 24 evaluable patients, the overall response rate was 100% (71% partial and 29% complete). CONCLUSIONS: Despite careful attention to the timing of growth factor with chemoradiation, the administration of filgrastim with this regimen did not allow dose escalation. As in many other recent studies of hematopoietic growth factors given prophylactically with chemotherapy, the duration of neutropenia at the MTD was shortened and the need for dose reduction throughout treatment was reduced in patients receiving filgrastim at the MTD.     

Effects of pulsed ultrasound on embryonic development: an in vitro study

Precursor CD4+ T cells develop into effector Th1 and Th2 cells that play a central role in the immune response. We show that the JNK MAP kinase pathway is induced in Th1 but not in Th2 effector cells upon antigen stimulation. Further, the differentiation of precursor CD4+ T cells into effector Th1 but not Th2 cells is impaired in JNK2-deficient mice. The inability of IL-12 to differentiate JNK2-deficient CD4+ T cells fully into effector Th1 cells is caused by a defect in IFNgamma production during the early stages of differentiation. The addition of exogenous IFNgamma during differentiation restores IL-12-mediated Th1 polarization in the JNK2-deficient mice. The JNK MAP kinase signaling pathway, therefore, plays an important role in the balance of Th1 and Th2 immune responses.     

Effects of thyroid hormone on embryonic oligodendrocyte precursor cell development in vivo and in vitro

The oligodendrocyte precursor cell divides a limited number of times before terminal differentiation. The timing of differentiation depends on both intracellular mechanisms and extracellular signals, including mitogens that stimulate proliferation and signals such as thyroid hormone (TH) and retinoic acid (RA) that help trigger the cells to stop dividing and differentiate. We show here that, both in vivo and in vitro, TH is required for the normal development of rodent optic nerve oligodendrocytes, although in its absence some oligodendrocyte development still occurs, perhaps promoted by signals from axons. We also demonstrate that TH from both mother and pup plays a part in oligodendrocyte development in vivo. Finally, we show that precursors in embryonic nerve cultures differ from those in postnatal cultures in two ways: they respond much better to TH than to RA, and they respond more slowly to TH, suggesting that oligodendrocyte precursor cells mature during their early development.     

Active brood care in an amphipod: influences of embryonic development, temperature and oxygen

Female amphipods (Crustacea) carry their fertilized eggs in an external brood pouch until the fully formed juveniles emerge (passive brood care). They may also direct specific maternal activities towards the brood (active brood care). We show that Crangonyx pseudogracilis, which typically populates fresh-waters subject to wide fluctuations in temperature and dissolved oxygen, engages in a highly responsive form of active brood care. This involves a flexing motion by the female that expands the brood pouch and increases the suspension of the eggs in the surrounding medium, accompanied by ventilation of the brood pouch and the 'cycling' of eggs therein. Females also selectively eject nonviable eggs from their broods. We investigated the expression of this brood care behaviour in relation to intrinsic and extrinsic factors relevant to the development of broods. The time spent by females in this behaviour initially increased as embryos developed, but decreased once advanced embryos began to self-ventilate and to have a heart pulse. In addition, both increased temperature and decreased oxygen concentration resulted in increased levels of brooding behaviour. We thus propose that this behaviour functions to ameliorate the microclimate of the brood pouch and serves the changing metabolic demand of the brood, as influenced by the interaction of embryonic development with temperature/dissolved oxygen regime. In addition, this behaviour may be a key adaptation facilitating the success of this North American species as an invader of disturbed and polluted freshwaters in Europe and elsewhere. Evidence is emerging that other amphipods associated with harsh environmental conditions also show such active maternal brood care. Copyright 1998 The Association for the Study of Animal Behaviour.     

Effects of above-optimum growth temperature and cell morphology on thermotolerance of Listeria monocytogenes cells suspended in bovine milk

The thermotolerances of two different cell forms of Listeria monocytogenes (serotype 4b) grown at 37 and 42.8 degrees C in commercially pasteurized and laboratory-tyndallized whole milk (WM) were investigated. Test strains, after growth at 37 or 42.8 degreesC, were suspended in WM at concentrations of approximately 1.5 x 10(8) to 3.0 x 10(8) cells/ml and were then heated at 56, 60, and 63 degrees C for various exposure times. Survival was determined by enumeration on tryptone-soya-yeast extract agar and Listeria selective agar, and D values (decimal reduction times) and Z values (numbers of degrees Celsius required to cause a 10-fold change in the D value) were calculated. Higher average recovery and higher D values (i.e., seen as a 2.5- to 3-fold increase in thermotolerance) were obtained when cells were grown at 42.8 degrees C prior to heat treatment. A relationship was observed between thermotolerance and cell morphology of L. monocytogenes. Atypical Listeria cell types (consisting predominantly of long cell chains measuring up to 60 micron in length) associated with rough (R) culture variants were shown to be 1.2-fold more thermotolerant than the typical dispersed cell form associated with normal smooth (S) cultures (P 相似文献   

Effects of vibration on the grain morphology

Pairs of halogen lamps were heated simultaneously at various rates of temperature increase through the recrystallization temperature and were held for five hours at 120 volts. One lamp in each of 20 pairs was vibrated during lightup. Examination of the grain boundaries of the filaments revealed that 63 pct of the boundaries in the vibrated lamps were “transverse.” In the lamps not vibrated, 52 pct of the boundaries were “transverse.” The greater number of “trans- verse” grain boundaries in the vibrated lamps is attributed to grain boundary sliding, which generates additional energy to allow the grain boundary to overcome the restraint to migration provided by the strings of potassium bubbles in the lamp wire. Formerly with GE Corporate Research and Formerly with GE Corporate Research and Formerly with the Technology Division, GE Lighting, Nela Park, Formerly with the Technology Division, GE Lighting, Nela Park,     

Age-related effects of nerve growth factor on the morphology of embryonic sensory neurons in vitro

Studies of neonatal and adult mammals have shown that neuronal morphology is regulated in part by the availability of target-derived neurotrophic factor. To test whether the same is true for embryonic neurons, which are dependent on target-derived neurotrophic factors for survival, we grew neural crest-derived sensory neurons from the trigeminal ganglion of avian embryos of different ages in vitro in different concentrations of nerve growth factor (NGF) and measured the number of branch points and total length of the resulting arborizations. Although the size and complexity of arborizations increased with embryonic age up to embryonic day (E)14, neuronal morphology for embryos younger than E14 was unaffected by the concentration of NGF in the culture medium. However, beginning at E14, the stage at which trigeminal neurons start to lose their absolute requirement for NGF for survival, the neurons had significantly more branch points and larger arborizations in higher concentrations of NGF. Thus, it appears that the extent of neurite outgrowth in young embryos is independent of neurotrophic factor concentration; each neuron that receives enough neurotrophic factor to survive elaborates approximately the same size arbor. As trigeminal neurons mature and become less dependent on neurotrophic factor for survival, they acquire the ability to respond to neurotrophic factor with increased neurite growth and branching, as in neonates and adults.     

Effect of platelet activating factor on embryonic development and implantation in the mouse

Platelet activating factor (PAF) was administered to female mice in order to investigate its effect on ovulation rate and on oocyte quality including their in-vitro embryonic development, implantation and uterine receptivity. In experiment 1, 4-week-old female mice were assigned to receive PAF or phosphate buffered saline for 4 consecutive days. On the second day of this treatment, pregnant mares' serum gonadotrophin was administered and human chorionic gonadotrophin (HCG) 48 h later, after which copulation occurred. Oocytes were collected on the following day and evaluated. The mean number of oocytes and zygotes (two pronuclear stage embryos) recovered from the PAF-treated group was not different from the control group (31 versus 27), but the proportion of zygotes was higher in PAF-treated group than in controls (83 versus 68%, P < 0.05, PAF versus controls). Although the rate of in-vitro first cleavage was not different in the two groups (82 versus 69% respectively), hatching was higher in the PAF-treated group than control mice (99 versus 83%, P < 0.01). In experiment 2, the in-vitro developed blastocysts from experiment 1 were transferred into the uterus of day 3 pseudopregnant PAF-treated or control recipients. Three different combinations of intrauterine transfer were performed; PAF embryo to control recipient (PAF-->C: n = 19), control embryo to PAF recipient (C-->PAF: n = 19), and control embryo to control recipient (C-->C: n = 22). Implantation and abortion were assessed on day 19 posttransfer. The implantation rate of C-->PAF (23.7%) was lower than C-->C (31.1%, P < 0.05), but was not different from PAF-->C (31.2%). Further, C-->PAF showed a higher abortion rate per embryo (29.6%) than PAF-->C (12.7%, P < 0.05), but was not different from C-->C (24.4%). In the present study, PAF administration enables females to produce oocytes with a higher potential for fertilization, in-vitro development and implantation, but has a detrimental effect on uterine receptivity to embryos.     

Effects of stimulation on embryonic activity in the chick.

Studied the effects of stimulation on the stereotyped and coordinated movements in the chick (Rhode Island Red/Light Sussex hybrids) embryo using the type of stimulation (regular loud clicks) known to accelerate development and the time of hatching. The number of coordinated movements, the amount and approximate size of all activity, heart rates and, in 20-day embryos, respiration rates were assessed during 15-min control, stimulation, and no stimulation periods. Results show an increase in the number of coordinated movements, but not their size, and some changes in the heart and respiration rates after the onset of stimulation. Effects occurred mostly after several minutes' delay. It is suggested that this delay may be connected with the reciprocal relationship between the coordinated movements and random motility in that the former may be triggered more readily at times when the latter are suppressed. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Normal and abnormal embryonic development of the anorectum in human embryos

A keystone of the molecular reductionist approach to cellular biology is a specific deductive strategy relating genotype to phenotype-two distinct categories. This relationship is based on the assumption that the intermediary cellular network of actively transcribed genes and their regulatory elements is deterministic (i.e., a link between expression of a gene and a phenotypic trait can always be identified, and evolution of the network in time is predetermined). However, experimental data suggest that the relationship between genotype and phenotype is nonbijective (i.e., a gene can contribute to the emergence of more than just one phenotypic trait or a phenotypic trait can be determined by expression of several genes). This implies nonlinearity (i.e., lack of the proportional relationship between input and the outcome), complexity (i.e. emergence of the hierarchical network of multiple cross-interacting elements that is sensitive to initial conditions, possesses multiple equilibria, organizes spontaneously into different morphological patterns, and is controlled in dispersed rather than centralized manner), and quasi-determinism (i.e., coexistence of deterministic and nondeterministic events) of the network. Nonlinearity within the space of the cellular molecular events underlies the existence of a fractal structure within a number of metabolic processes, and patterns of tissue growth, which is measured experimentally as a fractal dimension. Because of its complexity, the same phenotype can be associated with a number of alternative sequences of cellular events. Moreover, the primary cause initiating phenotypic evolution of cells such as malignant transformation can be favored probabilistically, but not identified unequivocally. Thermodynamic fluctuations of energy rather than gene mutations, the material traits of the fluctuations alter both the molecular and informational structure of the network. Then, the interplay between deterministic chaos, complexity, self-organization, and natural selection drives formation of malignant phenotype. This concept offers a novel perspective for investigation of tumorigenesis without invalidating current molecular findings. The essay integrates the ideas of the sciences of complexity in a biological context.     

氧含量、温度与铋对易切削钢中MnS形貌的影响

运用热态实验、化学分析、扫描电镜分析、热力学计算等方法研究了全氧、温度和Bi元素对MnS夹杂物形貌的影响.结果表明, 钢中较高的氧含量、高温加热和Bi均可有效降低钢中夹杂物的长宽比, 并可以提高大粒径夹杂物的比例.统计分析发现, MnS夹杂物的长宽比随全氧含量升高而降低.无论在铸态钢或轧材中, 夹杂物的长宽比随着单个夹杂物的面积增大而增大.随热处理温度的升高, 钢中出现大粒径的夹杂物, 同时夹杂物的外围轮廓变得清晰.900℃和1200℃热处理后钢中面积0⁵μm²夹杂物长宽比低于2.0, 比加热前夹杂物长宽比降低了43%.热态实验发现T.O=2.2×10^-5、0.0010%Bi的易切削钢中, 面积0⁵μm²夹杂物长宽比低于1.6, 比900℃和1200℃热处理后的夹杂物的长宽比降低了20%以上.     

Effects of hydrogen on dislocation morphology in spheroidized steel

The effects of hydrogen on development of dislocation morphology in plastically deformed spheroidized steel was investigated. The presence of internal hydrogen leads to strain localization in the form of dense dislocation structure emanating from carbide particles. The strain localization “tail” is evolved through interaction of three different dislocation systems and lies along the pure shear direction. Micro-autoradiography results have shown that the strain localization “strain” is a a strong trap for hydrogen.