The rate of oxygen consumption during embryogenesis of Lymnaea stagnalis (Gastropoda)

We studied the rate of oxygen consumption by the Lymnaea stagnalis embryos. The rate of oxygen consumption increased consistently during embryogenesis. The volume specific rate of oxygen consumption increased initially from the early cleavage stages until the gastrula stage and then decreased gradually to the eclosion of snails. There are three periods in embryogenesis of L. stagnalis, which differ in the coefficients of allometric dependence between the rate of oxygen consumption and volume of embryos: (1) early embryogenesis, when the increase in the rate of oxygen consumption is not accompanied by the growth of volume of the embryos; (2) larval period (trochophore and veliger stages; exponential coefficient k = 0.514), and (3) postlarval period (exponential coefficient k = 0.206).     

Rate of oxygen consumption during embryonic development of great ramshorn <Emphasis Type="Italic">Planorbarius corneus</Emphasis> (Gastropoda)

Energy metabolism is studied in great ramshorn Planorbarius corneus during embryonic development. It is shown that the rate of oxygen consumption is constantly increasing in the process of embryogenesis. The respiration intensity (rate of the oxygen consumption per unit of the embryo volume) initially increases and then slowly decreases until eclosion. At the early stages of development until the early trochophore stage, the embryo is not growing, and, thus, the change in the rate of oxygen consumption during this period is not associated with the change of the embryo volume. Reduction in the intensity of respiration begins simultaneously with the beginning of the growth of the embryo at the stage of the middle trochophore. Starting from the middle trochophore and until eclosion, an association between oxygen consumption rate and volume of the embryo can be described with an allometric equation with exponential coefficient equal to approximately 0.23.     

Physiological development of the embryonic and larval crayfish heart

The cardiovascular system is the first system to become functional in a developing animal and must perform key physiological functions even as it develops and grows. The ontogeny of cardiac physiology was studied throughout embryonic and larval developmental stages in the red swamp crayfish Procambarus clarkii using videomicroscopic dimensional analysis. The heart begins to contract by day 13 of development (at 25 degrees C, 20 kPa O(2)). Cardiac output is primarily regulated by changes in heart rate because stroke volume remains relatively constant throughout embryogenesis. Prior to eclosion, heart rate and cardiac output decreased significantly. Previous data suggest that the decrease in cardiac parameters prior to hatching may be due to an oxygen limitation to the embryo. Throughout development, metabolizing mass and embryonic oxygen consumption increased, while egg surface area remained constant. The surface area of the egg membrane is a constraint on gas exchange; this limitation, in combination with the increasing oxygen demand of the embryo, results in an inadequate diffusive supply of oxygen to developing tissues. To determine if the decrease in cardiac function was the result of an internal hypoxia experienced during late embryonic development, early and late-stage embryos were exposed to hyperoxic water (PO(2) = 40 kPa O(2)). Heart rate in late-stage embryos exposed to hyperoxic water increased significantly over control values, which suggests that the suppression in cardiac function observed in late-stage embryos is due to a limited oxygen supply.     

Oxygen consumption during embryonic development of the annual fish Nothobranchius korthausae with special reference to diapause

The oxygen consumption of Nothobranchius korthausae eggs in different developmental stages, including diapause II and III, was measured. Oxygen consumption increases exponentially during embryonic development. In diapause II and III there is a drop in oxygen consumption, which attains a minimal level in diapause II after 3 weeks and in diapause III after 2 weeks. During early development the embryos can escape from hypoxic stress by entering diapause I and II. During late embryogenesis embryos in diapause III can escape from hypoxic stress by hatching. We conclude that survival of annual fish embryos is enhanced during conditions of low oxygen concentration by reduced oxygen consumption rates during diapause.     

卵形鲳鲹胚胎及早期仔鱼耗氧量的研究

运用SKW-3微量呼吸仪对卵形鲳鲹(Trachinotus ovatus)胚胎和早期仔鱼的耗氧量进行测定,研究温度、盐度及pH的变化对胚胎耗氧量和Cu²⁺、Cd²⁺等重金属离子对早期仔鱼的耗氧量的影响。结果表明:在(25±0.5)℃条件下,卵形鲳鲹胚胎和早期仔鱼的耗氧量均随着发育时间的延长总体上呈上升的趋势,胚胎耗氧量在出膜前达到最大值,其中以原肠期和出膜期耗氧量变化最为显著。胚胎耗氧量随着温度、盐度、pH的增大而逐渐升高,在水温25℃、盐度35和pH为8时耗氧量到达最大值,随后逐渐减小。随着Cu²⁺浓度的升高,早期仔鱼耗氧量呈先增大后减小,在0.01mg·L^-1时耗氧率最大:胚胎耗氧量随着Cd²⁺浓度的升高而逐渐降低。     

Effect of Temperature on the Rate of Oxygen Consumption during the Second Half of Embryonic and Early Postembryonic Development of European Pond Turtle <Emphasis Type="Italic">Emys orbicularis</Emphasis> (Reptilia: Emydidae)

Oxygen consumption by eggs of European pond turtle was determined at two constant incubation temperatures of 25 and 28°C during the second half of embryogenesis. During development at both temperatures, the rate of oxygen consumption initially increased to remain constant during the last quarter of embryogenesis. The difference between the rates of oxygen consumption at these temperatures decreased during the studied period. The coefficient Q₁₀ for the rate of oxygen consumption decreased from 9 to 1.7. At an incubation temperature of 28°C, the changes in the rate of oxygen consumption in response to a short-term temperature decrease to 25°C or increase to 30°C depended on the developmental stage and were most pronounced at the beginning of the studied period. During late embryonic and first 2.5 months of postembryonic development, the rate of oxygen consumption did not significantly differ after such temperature changes. The regulatory mechanisms formed during embryonic development are proposed to maintain the level of oxygen consumption during temperature changes.     

Adaptive specific features of energy metabolism in fish ontogenesis

A review of data on the pattern of change of the intensity of oxygen consumption during early ontogenesis of different fish species (rainbow trout, loach, zebrafish, carp, and grass carp) is provided. It has a similar pattern: this index increases in the period of embryonic and larval development and, after passing of larvae to an active feeding, it begins to gradually decline. This dynamics is determined by specific features of an increase in the rate of oxygen uptake and body weight in the course of early stages of fish ontogenesis. For determining optimal temperature conditions of development, a method of total (for a definite stage of development) oxygen uptake was suggested, which makes it possible to determine minimal energy expenditures necessary for the process of a particular stage of embryogenesis to take place. Analysis of temperature dependence of kinetic properties of enzymes with reference to the Michaelis constant (Km) for lactate dehydrogenase demonstrated that minimal Km, corresponding to maximal enzyme-substrate affinity, for embryos of different fish species differs in correspondence with differences in temperature conditions of development of these species in nature. For embryos of one species developing at changing temperature conditions (salmonids), this index changes in accordance with a temperature drift in nature.     

Effect of hormonal compounds on embryogenesis of the pond snail Lymnaea stagnalis (L., 1758)

Effect of preparations ofa peptide nature (pituitrin and oxytocin) and of a steroid nature (progesterone and hydrocortisone) on embryonic development of freshwater gastropod Lymnaea stagnalis (Mollusca, Gastropoda, Pulmonata) is described. The hormonal preparations used, which differed in chemical nature and physiological activity, may render diverse effects on embryogenesis of the studied mollusk. Of neurohormones, pituitrin rendered the most noticeable and principally stimulating effect. Oxytocin was incorporated in regulatory processes much later and its effect on the rate of realization of particular stages depended more on the quality of occurring changes. In final stages of development, this hormone principally inhibited growth and development of embryos. The female sex hormone progesterone rendered an expressed stimulatory effect, especially notable in later developmental stages of embryos. The hormone hydrocortisone stimulated initial stages of embryogenesis. Its effect was almost not expressed in the final stages. The discovered differences seem to be related both to the functional specificity of the investigated compounds and to specific traits of mechanisms of realization of their effects. A hypothesis is formulated: in gastropods, similarly to vertebrates, the hormones are systemic embryonic and postnatal inducers of differentiation processes.     

Growth and oxygen consumption in embryonic and early postembryonic development of European pond turtle <Emphasis Type="Italic">Emys orbicularis</Emphasis> (Reptilia: Emydidae)

Experiments on developing eggs of European pond turtle (Emys orbicularis) demonstrated S-shaped changes in the rate of oxygen consumption and body weight during embryonic development. The rate of oxygen consumption and weight progressively increased within 70 days after hatching. During embryogenesis, the mass-specific rate of oxygen consumption decreased. After hatching, it increased but then decreased to a certain level, which remained constant to the end of the studied period. We observed unidirectional changes in the mass-specific rate of oxygen consumption and specific weight gain during embryonic development and this pattern was maintained after hatching. The coefficients of the allometric relationship between oxygen consumption and body weight were a = 0.33 and k = 0.52 during embryonic development and a = 0.17 and k = 0.89 during postembryonic development.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 2, 2005, pp. 214–220.Original Russian Text Copyright © 2005 by Vladimirova, Alekseeva, Nechaeva.     

The growth and energy metabolism of <Emphasis Type="Italic">Lymnaea stagnalis</Emphasis> (Lymnaeidae,Gastropoda): I. Early postlarval period

The growth and the oxygen consumption rate of Lymnaea stagnalis were studied during the first ten weeks after hatching. It is shown that these processes are atypical during early ontogenesis in comparison with adult mollusks. The obtained data on linear (height of shell) and weight growth can be equally well approximated with the von Bertalanffy equation or exponential and power equations. Both linear and weight growth are characterized by an approximately constant specific rate associated with synchronous oscillations of a week period. The oscillations were observed also for the oxygen consumption rate, but of another period (about 2.6 weeks). On average the metabolic rate after the initial triple increase during the first three days remains stable. The power coefficient of the allometric dependence of the total weight on the shell height is significantly less than that of the adult.     

Effects of biotic and abiotic factors on the oxygen content of green sea turtle nests during embryogenesis

Several biotic and abiotic factors can influence nest oxygen content during embryogenesis. Several of these factors were determined during each developmental stage of green sea turtle embryos on Wan-an Island, Penghu Archipelago, Taiwan. We examined oxygen content in 7 nests in 2007 and 11 in 2008. Oxygen in the adjacent sand, total and viable clutch sizes, air, sand and nest temperatures, and sand characters of each nest were also determined. Oxygen content was lower in late stages than in the early and middle stages. It was also lower in the middle layer than in the upper and bottom layers. Nest temperature showed opposite trends, reaching its maximum value in late stages of development. Nest oxygen content was influenced by fraction of viable eggs, total clutch sizes, sand temperatures, maximum nest temperature and maximum change in the nest temperature during incubation. Clutch size during embryogenesis was the most influential factor overall. However, the major influential factors were different for different developmental stages. In the first half of the incubation, the development rate was low, and the change in the nest oxygen content was influenced mainly by the clutch size. During the second half, the rapid embryonic development rate became the dominant factor, and hatchling activities caused even greater oxygen consumption during the last stage of development.     

泥鳅和白鲢胚胎不同发育时期耗氧量的研究

泥鳅和白鲢胚胎发育时的耗氧量是随着发育进程而以指数函数方式在增长,其耗氧曲线显示出卵裂期、原肠期、神经胚期、肌肉效应期以及出膜期是5个呼吸代谢水平较高的时期,其中又以原肠期与出膜期对孵化环境溶氧的需求尤为突出。胚胎在发育过程中纳入氧的快慢与强弱,都直接或间接地反映出新陈代谢的速度以及营养物质不断地被氧化、消耗和能量传递的状况。因此,鱼类胚胎发育时耗氧的高低,无疑是其胚胎发育状况的一种生理指标。     

A hormonal misunderstanding in Acca sellowiana embryogenesis: levels of zygotic embryogenesis do not match those of somatic embryogenesis

Endogenous levels of IAA, ABA and four types of CKs were analyzed in zygotic and indirect (ISE) and direct somatic embryogenesis of Acca sellowiana. Zygotic and somatic embryos at different developmental stages were sampled for morphological and hormonal analysis. Both embryo types showed substantial asymmetry in hormone levels. Zygotic embryos displayed a conspicuous peak of IAA in early developmental stages. The results outlined the hormonal variations occurring during zygotic and somatic embryogenesis regarding the timing, nature and hormonal status involved in both processes. The short transient pulse of IAA observed on the 3rd day in culture was suggested to be involved with the signaling for the induction of somatic embryogenesis. Fertilized ovule development was associated with increased IAA levels 21?C24?days after pollination, followed by a sharp decrease in the cotyledonary stage, both in zygotic and somatic embryos. There was a prominent increase in ABA levels in cultures which generated ISE 24?C30?days after pollination, a period that corresponds to the heart and torpedo stages. The levels of total CKs (Z, [9R]Z, iP and [9R]iP) were also always higher in zygotic than in somatic embryogenesis. While zygotic embryogenesis was dominated by the presence of zeatin, the somatic process, contrarily, was characterized by a large variation of the other cytokinin forms and amounts studied. The above results, when taken together, could be related to the previously observed high frequency formation of anomalous somatic embryos formed in A. sellowiana, as well as to their low germination ability.     

Capsule walls as barriers to oxygen availability: Implications for the development of brooded embryos by the estuarine gastropod Crepipatella dilatata (Calyptraeidae)

Encapsulation of developing embryos imposes potential restrictions, because the capsule wall must allow for adequate inward diffusion of oxygen and for increased diffusion of oxygen as metabolic demand increases with continued development. Samples of egg capsules from the gastropod Crepipatella dilatata were used to document surface characteristics, composition of the different capsule wall layers, and alterations in wall thickness during development. The diffusion coefficient and capsule wall permeability were determined experimentally for capsules containing embryos at different developmental stages. We also determined oxygen consumption rates for various embryonic stages and for nurse eggs, which provide food for embryos during development. The capsule wall of C. dilatata possesses 2 differentiated layers: the external capsular wall (ECW) and the internal capsular wall (ICW). The ECW is compact and fibrous, features that remain invariable during development, and lacks surface features that might make some portions of the capsule wall more permeable to oxygen than others. On the other hand, the ICW is initially spongy and thick, but significantly decreases in thickness over time, particularly before the embryos begin feeding on nurse eggs. Although the capsule wall is a serious barrier to diffusion, permeability to oxygen increases over time by 112% due to the dramatic thinning of the inner capsule wall layer. Nurse eggs consume oxygen but at very low rates, supporting the idea that they correspond to living embryonic cells that have stopped their development. Respiration measurements indicated that embryos are initially supplied with enough oxygen within the egg capsules to carry out the activities characteristic of embryogenesis, even though the capsular walls show their maximum thickness and lowest permeability at this time. However, as the embryo develops its velum and becomes more active, capsule wall thickness decreases and capsule permeability to oxygen increases. Correspondingly, the oxygen demands of metamorphosed but still encapsulated specimens are approximately 135% higher than those of pre-metamorphosed sibling embryos.     

High efficiency adventive embryogenesis on somatic embryos of anther,filament and immature proembryo origin in horse-chestnut (Aesculus hippocastanum L.) tissue culture

Adventive embryogenesis was successfully induced in cultures of zygotic and somatic embryos on MS medium supplemented with BA and NAA. A procedure has been proved successful for the in vitro multiplication of somatic embryos regenerated at low frequencies from filament and callus cultures. The occurrence and rate of adventive embryogenesis did not depend on the origin of the primary embryos (zygotic and somatic), but did depend on the developmental stage. Primary embryos are capable of embryogenesis in each of the different phases of embryogenesis, though the rate is different. BA concentrations of 22–44 M increased the rate of adventive embryogenesis and accelerated the development of embryos. The highest proliferation rate (22–25x/5 weeks) was achieved at hormone concentrations of 44 M BA and 5.4 M NAA.Abbreviations BA benzyladenine - CH casein hydrolysate - CM coconut milk - 2,4-D dichlorophenoxyacetic acid - MS Murashige & Skoog medium - WPM woody plant medium - NAA 1-naphtaleneacetic acid     

Dynamics of body mass and oxygen consumption in the ribbed newt <Emphasis Type="Italic">Pleurodeles waltl</Emphasis> ontogenesis: 1. Endotrophic development

The correlation between parameters of growth and energy metabolism in the example of embryonic and larval development of the ribbed newt Pleurodeles waltl has been studied. The wet body mass increases five times during this period due to water absorption by developing tissues and the yolk, and the dry mass decreases 1.18 times. The highest mass-specific growth rate and mass-specific rate of oxygen consumption of developing tissues was noticed at the 33rd stage of embryogenesis (13th–14th day of development). These indexes decreased after the hatching, but increased after larvae switched to external nutrition. Comparison of the studied parameters has identified a similar features in alteration of mass-specific growth rate, mass-specific rate of oxygen consumption, and watering of developing tissues in early development of the ribbed newt.     

Efficient embryonic culture method for the Japanese striped snake,Elaphe quadrivirgata,and its early developmental stages

The morphogenesis of snake embryos is an elusive yet fascinating research target for developmental biologists. However, few data exist on development of early snake embryo due to limited availability of pregnant snakes, and the need to harvest early stage embryos directly from pregnant snakes before oviposition without knowing the date of fertilization. We established an ex vivo culture method for early snake embryos using the Japanese striped snake, Elaphe quadrivirgata. This method, which we named “sausage‐style (SS) culture”, allows us to harvest snake embryos at specific stages for each experiment. Using this SS culture system, we calculated somite formation rate at early stages before oviposition. The average somite formation rate between 6/7 and 12/13 somite stages was 145.9 min, between 60/70 and 80/91 somite stages 42.4 min, and between 113–115 and 126/127 somite stages 71 min. Thus, somite formation rate that we observed during early snake embryogenesis was changed over time. We also describe a developmental staging series for E. quadrivirgata. This is the first report of a developmental series of early snake embryogenesis prior to oviposition by full‐color images with high‐resolution. We propose that the SS culture system is an easy method for treating early snake embryos ex vivo.     

Regulation of Gene Expression in Developing Zea mays Embryos: Protein Synthesis during Embryogenesis and Early Germination of Maize

Polypeptides synthesized in dissected embryos of Zea mays at different stages of embryogenesis and early germination have been characterized by their migration in two-dimensional gel electrophoresis. This analysis has been carried out with in vivo labeled polypeptides from excised embryos and with proteins synthesized in vitro in the rabbit reticulocyte system directed by poly(A⁺) RNA isolated from the different developmental stages. We have identified three main sets of expressed polypeptides: (a) embryonic set: this group of polypeptides is synthesized in young and mature embryos but not in early germination; (b) maturation set: this group of polypeptides is not present in young embryos and appears during the maturation period. Some of these polypeptides are still present in early germination while others disappear from stored mRNAs in dry embryos. One particular group from this set can be induced prematurely in young embryos by incubation with abscisic acid; and (c) germination set: this group of polypeptides is not expressed in the maturation period and appears after brief imbibition of the dry embryos.     

Respiration rates of subitaneous eggs from a marine calanoid copepod: monitored by nanorespirometry

The oxygen consumption rate during embryogenesis of Acartia tonsa subitaneous eggs were measured at different temperatures (10, 15, 17, 21, 24 and 28°C) with nanorespirometry. The oxygen consumption was constant during the embryogenesis but increased rapidly at hatching time. The mean ± SD oxygen consumption rate increased exponentially with temperature and ranged from 0.09 ± 0.04 (10°C) to 0.54 ± 0.09 nmol O₂ egg⁻¹ h⁻¹ (28°C). The mean ± SD Q₁₀-value was 2.51 ± 0.15. Calculations of energy consumption during embryogenesis ranged from 1.86 to 18.28 mJ depending on temperature and development time. We conclude that the effect of temperature on oxygen consumption rate was far less important than the prolonged development time when calculating the energy consumed during embryogenesis.     

Relationship between production of carrot somatic embryos and dissolved oxygen concentration in liquid culture

To evaluate the relationship between somatic embryogenesis and dissolved oxygen concentration, somatic embryo cultures of carrot (Daucus carota L.) were cultured under various dissolved oxygen concentration levels (bubble free aeration with 4%, 7%, 20%, 30%, and 40% oxygen in flasks). The system used allows dissolved oxygen concentration control without bubble aeration or mixing speed modification. The total number of somatic embryos was not affected by the dissolved oxygen (DO) concentration tested. Even if globular-stage embryos were induced at a low level of oxygen aeration, heart-stage embryo formation was still repressed. Oxygen enrichment (20%, 30% and 40% oxygen) enhanced torpedo and cotyledonary-stage embryo production. The oxygen-enriched aeration was effective in promoting the growth of the late developmental stages. Sugar consumption did not increase when the oxygen concentration was enriched above the ambient level. The number of heart-stage embryos increased as oxygen concentration increased up to the 7% level, while above the 20% level no change in production was observed. The production of cotyledonary-stage embryos was directly related to oxygen concentration. These results support that oxygen-enriched aeration provides oxygen to the low oxygen areas in somatic embryo. After the heat-stage embryos, which were grown at the 7% level were transferred to a flask with ambient, they developed an elongated root part and eventually grew to normal plantlets. This revised version was published online in June 2006 with corrections to the Cover Date.