Changes in the Intensity of Respiration during Ontogenesis of Some Invertebrates

We studied the dynamic of respiration intensity during ontogenesis of flat worms (Dugesia tigrina), molluscs (Anodonta piscinalis and Viviparus viviparus, and insects (Leptinotarsa decemlineata). In planarians that reproduce vegetatively, the intensity of respiration increases just after fission and decreases at the subsequent phases of growth. In A. piscinalis, this index of metabolism increases during embryonic and early larval development and decreases at the later developmental stages. In V. viviparus, which develops in the female genital tract, the intensity of respiration remains unchanged during embryogenesis and decreases during late embryogenesis and subsequent phases of growth. In L. decemlineata, the intensity of respiration increases during embryonic and early larval development and then decreases to undergo cyclic changes times to molts. This index markedly decreases in the pupae, increases in the beginning of imaginal period, and then again decreases.     

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.     

Dynamics of the intensity of respiration in early embryogenesis of amphibians

We studied growth and respiration rate during early ontogenesis of the axolotl Ambystoma mexicanum, Bosca's newt Triturus waltlii, the green toad Bufo viridis, and the smooth clawed frog Xenopus laevis. The respiration rate in these amphibian species increases during embryonal and larval development, peaks after transition to active feeding, and decreases at later stages of ontogenesis. The patterns of dynamics of this energy metabolism index in tailed and tailless amphibians have some differences related to their specific development. The changes in respiration rate in the embryos and larvae are correlated with the concentrations of mitochondria.     

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.     

Respiration rate dynamics during early ontogenesis in amphibians

We studied growth and respiration rate during early ontogenesis of the axolotlAmbystoma mexicanum, Bosca’s newtTriturus waltlii, the green toadBufo viridis, and the smooth clawed frogXenopus laevis. The respiration rate in these amphibian species increases during embryonal and larval development, peaks after transition to active feeding, and decreases at later stages of ontogenesis. The patterns of dynamics of this energy metabolism, index in tailed and tailless amphibians have some differences related to their specific development. The changes in respiration rate in the embryos and larvae are correlated with the concentrations of mitochondria.     

A comparative ontogenetic study of respiration and oxidative phosphorylation of chicken myocardium mitochondria

When adding alpha-ketoglutarate and glutamate the intensity of respiration by the myocardium mitochondria increases gradually from the 15th day of embryonic development till the chicken hatching out. In the presence of succinate respiration of mitochondria of 15- and 20-day embryos and 5-day chickens is almost the same and decreases noticeably in adult chickens. When the above-mentioned substrates are added the value of P/O gradually decreases during the chicken development.     

Ratio of concentration of ions of uni- and bivalent metals in the tissues of developing chick embryos and 1-day-old chickens]

The ratio of concentrations Na+/K+ decreases in the brain and liver and increases in the cardiac muscle during the chick embryogenesis. The maximum concentration of Ca2+ was noted in the tissues under study on 14th day of chick embryonic development and its content decreased reliably at the subsequent stages. The concentration of Mg2+ in the tissues under study decreased during the embryogenesis as well.     

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.     

Deviation of the living system from the stationary state during oogenesis

Summary The changes in respiration and glycolysis of whole oocytes and homogenates of oocytes during oogenesis have been studied.The respiration rate of whole oocytes increases during oocyte growth and decreases during oocyte maturation. The respiration rate of homogenates also increases during oocyte growth and does not change during egg maturation. At all oogenesis stages the respiration rate of homogenates is higher than the respiration rate of whole oocytes.Respiration intensity increases during the small growth stage and decreases during the following stages of oogenesis. Respiration intensity of homogenates under optimal conditions changes in a similar way. Respiration intensity under physiological conditions diminishes during oogenesis from 70% at the small growth stage to 42% in unfertilised eggs.The rate of glycolysis in whole oocytes and homogenates of oocytes increases during the growth period of oocytes but does not change during egg maturation.Glycolysis intensity of the whole oocytes increases at the large growth stage—stage of cytoplasmic vacuolisation—and becomes less during the following stages. Glycolysis intensity in homogenates under optimal conditions is much higher than the glycolysis intensity of whole oocytes and it decreases slightly during oogenesis. The efficiency of glycolysis in oocytes under physiological conditions is very low. It increases from the stage of cytoplasmic vacuolisation (3.6%) to the stage at which vitellogenesis starts (20%) and diminishes at the following stages.The data obtained are considered in the light of the Prigogine and Wiame interpretation of a thermodynamic theory of development.     

Developmental regulation of energy metabolism in Caenorhabditis elegans

Changes in energy metabolism during larval development in Caenorhabditis elegans have been investigated using phosphorus nuclear magnetic resonance (31P NMR). The relative concentrations of ATP, ADP, AMP, sugar phosphates, and other metabolites were observed to change during larval development, producing stage-specific spectra. These spectra are consistent with enzyme assays for isocitrate dehydrogenase and isocitrate lyase, indicating that high activity of the glyoxylate pathway during embryonic development decreases during the first larval (L1) stage, and respiration during the L2, L3, and L4 stages occurs preferentially through the TCA cycle. Metabolic strategies were further studied using mutants that are predisposed to enter the dauer stage, a developmentally arrested third-stage larva formed under conditions of overcrowding and limited food. After the L1 molt, energy metabolism in animals destined to become dauer larvae diverges from that of animals committed to growth. Relative to the L1, the L2 larvae committed to growth exhibit increased isocitrate dehydrogenase activity as well as increases in ATP and other high-energy phosphates, but predauer (L2d) larvae exhibit declining enzyme activities and declining levels of high-energy phosphates. The predominant phosphorus NMR signal in dauer larva extracts corresponds to inorganic phosphate. We conclude that metabolism is regulated during C. elegans larval development, with a major transition apparent after the L1 stage. This transition does not occur in larvae destined to form dauer larvae.     

FGF signalling: diverse roles during early vertebrate embryogenesis

Fibroblast growth factor (FGF) signalling has been implicated during several phases of early embryogenesis, including the patterning of the embryonic axes, the induction and/or maintenance of several cell lineages and the coordination of morphogenetic movements. Here, we summarise our current understanding of the regulation and roles of FGF signalling during early vertebrate development.     

Relationships among salinity, egg size, embryonic development, and larval biomass in the estuarine crab Chasmagnathus granulata Dana, 1851

We studied interrelationships between initial egg size and biomass, duration of embryogenesis at different salinities, and initial larval biomass in an estuarine crab, Chasmagnathus granulata. Ovigerous females were maintained at three different salinities (15‰, 20‰ and 32‰); initial egg size (mean diameter), biomass (dry weight, carbon and nitrogen) as well as changes in egg size, embryonic development duration, and initial larval biomass were measured.

Initial egg size varied significantly among broods from different females maintained under identical environmental conditions. Eggs from females maintained at 15‰ had on average higher biomass and larger diameter. We hypothesise that this is a plastic response to salinity, which may have an adaptive value, i.e. it may increase the survivorship during postembryonic development. The degree of change in egg diameter during the embryonic development depended on salinity: eggs in a late developmental stage were at 15‰ significantly larger and had smaller increment than those incubated at higher salinities. Development duration was longer at 15‰, but this was significant only for the intermediate embryonic stages. Initial larval biomass depended on initial egg size and on biomass loss during embryogenesis. Larvae with high initial biomass originated either from those eggs that had, already from egg laying, a high initial biomass (reflecting individual variability under identical conditions), or from those developing at a high salinity (32‰), where embryonic biomass losses were generally minimum. Our results show that both individual variability in the provisioning of eggs with yolk and the salinity prevailing during the embryonic development are important factors causing variability in the initial larval biomass of C. granulata, and thus, in early larval survival and growth.     

Growth and respiration of embryos and larvae of the rabbittish Siganus randalli (Pisces, Siganidae)

Growth and respiration of larval rabbitfish from Guam were examined. Larvae were reared from eggs in 2- to 10-ton tanks and were fed rotifers, Anemia , and artificial feed in succession as development proceeded through metamorphosis. Growth in length was rapid during the 12 h after hatching, then slowed until the larvae began to feed. The yolk sac was usually absorbed by 36 h after hatching. Rates of respiration of larvae and eggs were determined with a dissolved oxygen electrode at various times through development. Larval metabolism increased steadily during the embryonic stages culminating in a metabolic burst immediately after hatching. Respiration rates remained relatively stable from shortly after hatching until the onset of exogenous feeding, after which respiration rates increased with larval size. The respiration rates of post-yolk-sac larvae scaled isometrically with larval dry mass. Daily growth of feeding larvae was 27 to 28% of larval dry mass.     

Identification of adult midgut precursors in Drosophila

The adult Drosophila midgut is thought to arise from an endodermal rudiment specified during embryogenesis. Previous studies have reported the presence of individual cells termed adult midgut precursors (AMPs) as well as “midgut islands” or “islets” in embryonic and larval midgut tissue. Yet the precise relationship between progenitor cell populations and the cells of the adult midgut has not been characterized. Using a combination of molecular markers and directed cell lineage tracing, we provide evidence that the adult midgut arises from a molecularly distinct population of single cells present by the embryonic/larval transition. AMPs reside in a distinct basal position in the larval midgut where they remain through all subsequent larval and pupal stages and into adulthood. At least five phases of AMP activity are associated with the stepwise process of midgut formation. Our data shows that during larval stages AMPs give rise to the presumptive adult epithelium; during pupal stages AMPs contribute to the final size, cell number and form. Finally, a genetic screen has led to the identification of the Ecdysone receptor as a regulator of AMP expansion.     

Respiration and glycolysis in the liver of developing chick embryos and chicks]

Oxygen uptake in liver slices remains constant between the 12th and the 17th days of embryonic development, being equal to that in 30-60-day chicks. During the transition from allantoic respiration to the pulmonary one, oxygen consumption decreases, the decrease being observed up to the end of embryonic period. After hatching, oxygen consumption increases 4-5-fold to the 6-7th and decreases up to the initial level at the 10th day. Respiration of mitochondria isolated from the liver and concentration of cytochromes in mitochondria remain constant. The value P/O is the lowest, whereas catalase activity is the highest during hatching. The intensity of anaerobic glycolysis changes similarly to that of respiration.     

Independent temporal expression of two N-substituted aminoacyl-tRNA hydrolases during the development of Artemia salina.

Encysted embryos of the crustacean Artemia salina contain an enzymatic activity which hydrolyzes N-acetylphenylalanyl-tRNA to N-acetylphenylalanine and tRNA. The enzyme apparently does not hydrolyze other free or N-substituted aminoacyl-tRNAs. The levels of this enzyme do not significantly change during embryonic and early larval development. In contrast, an unspecific hydrolase active on several N-substituted aminoacyl-tRNAs is practically absent in the encysted embryos and during embryogenesis and appears abruptly during larval development. The independent temporal expression of these two hydrolases during Artemia salina differentiation makes this organism siuitable for the study of the physiological role of these enzymes.     

Compensating for delayed hatching across consecutive life‐history stages in an amphibian

Environmental conditions experienced early in the ontogeny can have a strong impact on individual fitness and performance later in life. Organisms may counteract the negative effects of poor developmental conditions by developing compensatory responses in growth and development. However, previous studies on compensatory responses have largely ignored the effects that poor embryonic conditions could have during the later life stages. In this study, we examined the effects of artificially delayed development in early life over two later life history transitions by investigating the compensatory growth of larval moor frogs Rana arvalis in response to temperature variation during embryonic development, and the associated costs during the larval ′and postmetamorphic stages. Low temperature during embryonic stage lead to delayed hatching at smaller size. The groups with delayed embryonic development showed strong compensatory growth during the larval stage, and reached similar metamorphic size than the controls in a shorter time. However, the most strongly delayed group was not able to fully catch up the total development time. These compensatory responses were found in the absence of photoperiod cues indicating that the delay in embryonic development was sufficient to initiate the compensatory response in larval growth and development. No apparent costs of compensatory growth were detected in terms of morphology or locomotor performance at the juvenile stage. We found that compensatory responses can be activated as early as at the embryonic stage and extend over several consecutive life history transitions, mitigating the effects of poor conditions experienced early in development. Potential short‐term costs in natural environments and the occurrence of long‐term costs, which prevent the generalisation of a faster larval life style, are discussed.     

Continuity versus split and reconstitution: exploring the molecular developmental corollaries of insect eye primordium evolution

Holometabolous insects like Drosophila proceed through two phases of visual system development. The embryonic phase generates simple eyes of the larva. The postembryonic phase produces the adult specific compound eyes during late larval development and pupation. In primitive insects, by contrast, eye development persists seemingly continuously from embryogenesis through the end of postembryogenesis. Comparative literature suggests that the evolutionary transition from continuous to biphasic eye development occurred via transient developmental arrest. This review investigates how the developmental arrest model relates to the gene networks regulating larval and adult eye development in Drosophila, and embryonic compound eye development in primitive insects. Consistent with the developmental arrest model, the available data suggest that the determination of the anlage of the rudimentary Drosophila larval eye is homologous to the embryonic specification of the juvenile compound eye in directly developing insects while the Drosophila compound eye primordium is evolutionarily related to the yet little studied stem cell based postembryonic eye primordium of primitive insects.     

Distribution of cells containing FMRFamide-related molecules in the embryonic development of Ophryotrocha labronica (Polychaeta: Dorvilleidae)

Abstract. The timing and spatial distribution of cells containing FMRFamide-related molecules in the embryogenesis of the polychaete Ophryotrocha labronica were studied immunocytochemically. FMRFamide-like molecules emerge early during embryonic development. They are found at the one-cell stage, are asymmetrically distributed in the first phases of cleavage, associated with gastrular movements, and label the central nervous system morphogenesis. Moreover, during embryogenesis, the pattern of gut cells with the FMRFamide-like phenotype that is present in adults is already established. The early occurrence of FMRFamide-like molecules in O. labronica suggests that these molecules are involved as pre-nervous growth signals in the regulation of basic neuronal cell behaviors.