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Ontogeny
Kinds of Ontogeny Selected AbstractsRELATIVE ROLE OF GENETIC DETERMINATION AND PLASTIC RESPONSE DURING ONTOGENY FOR SHELL-SHAPE TRAITS SUBJECTED TO DIVERSIFYING SELECTIONEVOLUTION, Issue 5 2009Paula Conde-Padín We studied the relative role of genetic determination versus plastic response for traits involved in ecological adaptation of two ecotypes of Littorina saxatilis living at different shore levels. To investigate the magnitude of the plastic response across ontogeny, we compared morphological data from individuals grown in the laboratory and taken from the wild at three developmental stages: shelled embryos, juveniles, and adults. The results indicate that most shell shape variation (72,99%) in adaptive traits (globosity and aperture of the shell) is explained by the ecotype irrespective of the growth environment, suggesting that direct genetic determination is the main factor responsible for the process of adaptation in the wild. There was a tendency for the contribution of plasticity to increase over ontogeny but, in general, the direction of the plastic response did not suggest that this was adaptive. [source] SPATIOTEMPORAL REORGANIZATION OF GROWTH RATES IN THE EVOLUTION OF ONTOGENYEVOLUTION, Issue 4 2000Miriam L. Zelditch Abstract. Heterochrony, evolutionary changes in rate or timing of development producing parallelism between ontogeny and phylogeny, is viewed as the most common type of evolutionary change in development. Alternative hypotheses such as heterotopy, evolutionary change in the spatial patterning of development, are rarely entertained. We examine the evidence for heterochrony and heterotopy in the evolution of body shape in two clades of piranhas. One of these is the sole case of heterochrony previously reported in the group; the others were previously interpreted as cases of heterotopy. To compare ontogenies of shape, we computed ontogenetic trajectories of shape by multivariate regression of geometric shape variables (i.e., partial warp scores and shape coordinates) on centroid size. Rates of development relative to developmental age and angles between the trajectories were compared statistically. We found a significant difference in developmental rate between species of Serrasalmus, suggesting that heterochrony is a partial explanation for the evolution of body shape, but we also found a significant difference between their ontogenetic transformations; the direction of the difference between them suggests that heterotopy also plays a role in this group. In Pygocentrus we found no difference in developmental rate among species, but we did find a difference in the ontogenies, suggesting that heterotopy, but not heterochrony, is the developmental basis for shape diversification in this group. The prevalence of heterotopy as a source of evolutionary novelty remains largely unexplored and will not become clear until the search for developmental explanations looks beyond heterochrony. [source] THE LOWER CAMBRIAN EODISCOID TRILOBITE CALODISCUS LOBATUS FROM SWEDEN: MORPHOLOGY, ONTOGENY AND DISTRIBUTIONPALAEONTOLOGY, Issue 3 2009PETER CEDERSTRÖM Abstract:, Several thousand disarticulated remains together with a few complete enrolled specimens of the lower Cambrian eodiscoid trilobite Calodiscus lobatus (Hall, 1847) have been collected at two outcrop areas in Sweden. The material reveals new details of morphology and morphogenesis during ontogenetic development. Size-frequency analyses show that the material from the Fånån rivulet in Jämtland, central Sweden, represents a natural population dominated by juveniles, whereas the material from Gislövshammar in Scania, southern Sweden, has been sorted during postmortem transport. Three stages of protaspid development can be traced and defined as well as all subsequent ontogenetic stages for the cephalon, hypostome and pygidium. The early meraspid pygidium has a pronounced larval notch, which persists, though becoming progressively less distinct in later meraspides. The number of axial rings in the transitory pygidium increases throughout meraspid development until a third and final thoracic segment is liberated. During ontogeny the articulating half-rings are strongly developed, and both meraspides and holaspides were capable of full sphaeroidal enrollment and outstretched postures. The hypostome undergoes some dramatic modifications; in M0 the anterior margin is axe-shaped, by M1 the area of attachment greatly decreases and the hypostome becomes more elongated and pear-shaped, before attaining its adult form, which has an overall resemblance to that of polymerid trilobites. During ontogeny, the hypostome changes from a conterminant attachment to a natant condition, thereby mirroring hypostomal evolution within trilobites generally. The morphology, ontogeny, enrollment, hypostomal development and the presence of calcified protaspides suggest polymerid rather than agnostoid affinities of the eodiscoids. [source] ONTOGENY AND RELATIONSHIPS OF THE TRILOBITE PSEUDOPETIGURUS PRANTL AND P,IBYLPALAEONTOLOGY, Issue 3 2006YUAN WENWEI Abstract:, The ontogeny of Pseudopetigurus deprati Turvey et al., 2006 from the Ordovician Dawan Formation (Arenigian), Anhui Province, South China, is described. The presence of an anterior cranidial border in Pseudopetigurus is recognized for the first time. On account of the short (tr.), spindle-shaped anterior border, and the distinct, steeply inclined, wall-like pygidial margin, Pseudopetigurus is assigned to the family Dimeropygidae, the first genus of this family endemic to Gondwana. It has previously been regarded as a member of family Isocolidae. Cladistic analysis of species assigned to Dimeropygidae supports the monophyly of a clade including Dimeropyge, Dimeropygiella, Ischyrotoma, Pseudohystricurus and Pseudopetigurus, which may represent a subfamily Dimeropyginae. The distribution of Dimeropyginae shows a predominantly palaeotropical distribution, while the Gondwana Pseudopetigurus must have diverged from the dimeropygine common ancestor in pre-Arenigian time. [source] Ontogeny of vasotocin-expressing cells in zebrafish: Selective requirement for the transcriptional regulators orthopedia and single-minded 1 in the preoptic areaDEVELOPMENTAL DYNAMICS, Issue 4 2008Jennifer L. Eaton Abstract The neurohypophysial peptide arginine vasotocin, and its mammalian ortholog arginine vasopressin, influence a wide range of physiological and behavioral responses, including aspects of sexual and social behaviors, osmoregulation, stress response, metabolism, blood pressure, and circadian rhythms. Here, we demonstrate that, in zebrafish (Danio rerio), the vasotocin precursor gene arginine vasotocin-neurophysin (avt) is expressed in two domains in the developing embryo: the dorsal preoptic area and the ventral hypothalamus. In the dorsal preoptic area, avt -expressing cells are intermingled with isotocin-neurophysin (ist) -expressing cells, and these neurons project to the neurohypophysis (posterior pituitary). In the dorsal preoptic area, the transcriptional regulators orthopedia b (otpb) and simple-minded 1 (sim1) are required for expression of both avt and ist. In contrast, otp and sim1 are not required for avt expression in the ventral hypothalamus. Thus, the development of these two avt expression domains is influenced by separate gene regulatory networks. Developmental Dynamics 237:995,1005, 2008. © 2008 Wiley-Liss, Inc. [source] Ontogeny of tyrosine hydroxylase mRNA expression in mid- and forebrain: Neuromeric pattern and novel positive regionsDEVELOPMENTAL DYNAMICS, Issue 3 2005Faustino Marín Abstract Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the synthesis of catecholamines and, thus, critical in determining the catecholaminergic phenotype. In this study, we have examined the expression of TH mRNA by in situ hybridization in the embryonic mouse forebrain and midbrain and have mapped its localization according to the neuromeric pattern. We find that early in embryonic development, 10 to 12 days post coitum (dpc), TH mRNA is expressed in ample continuous regions of the neuroepithelium, extending across several neuromeres. However, from 12.5 dpc onward, the expression becomes restricted to discrete regions, which correspond to the dopaminergic nuclei (A8 to A15). In addition to these nuclei previously described, TH mRNA is also observed in regions that do not express this enzyme according to immunohistochemical studies. This difference in relation to protein expression pattern is consequent with the known posttranscriptional regulation of TH expression. The most representative example of a novel positive region is the conspicuous mRNA expression in both medial and lateral ganglionic eminences. This result agrees with reports describing the capacity of striatal stem cells (that is, located at the lateral ganglionic eminence) to become dopaminergic in vitro. Other regions include the isthmic mantle layer and the early floor plate of the midbrain,caudal forebrain. On the whole, the expression map we have obtained opens new perspectives for evolutionary/comparative studies, as well as for therapeutic approaches looking for potentially dopaminergic cells. Developmental Dynamics 234:709,717, 2005. © 2005 Wiley-Liss, Inc. [source] Ontogeny of energy homeostatic pathways via neuroendocrine signaling in Atlantic salmonDEVELOPMENTAL NEUROBIOLOGY, Issue 9 2010Anne-Grethe Gamst Moen Abstract Leptin and ghrelin are known to regulate energy homeostasis via hypothalamic neuropeptide signaling in mammals. Recent studies have discovered that these hormones exist in teleosts, however, very little is known concerning their role during teleost ontogeny. Here, we have examined the steady state levels of leptins, ghrelins, their target neuropetides and several growth factors during Atlantic salmon development. Initial experiments revealed differential expression of leptin genes and ghrelin isoforms during embryogenesis. In larvae, equal upregulation of ghrl1 and ghrl2 was observed just prior to exogenous feeding while a surge of lepa1 occurred one week after first-feeding. Subsequent dissection of the embryos and larvae showed that lepa1, cart, pomca1, and agrp are supplied as maternal transcripts. The earliest zygotic expression was observed for lepa1 and cart at 320 day degrees. By 400 day degrees, this expression was localized to the head and coincided with upregulation of ghrl2 and npy. Over the hatching period growth factor signaling predominated. The ghrelin surge prior to first-feeding was exclusively localized in the internal organs and coincided with upregulation of npy and agrp in the head and agrp in the trunk. One week after exogenous feeding was established major peaks were detected in the head for lepa1 and pomca1 with increasing levels of cart, while lepa1 was also significantly expressed in the trunk. By integrating theses data into an ontogenetic model, we suggest that the mediation of Atlantic salmon energy homeostatic pathways via endocrine and neuropeptide signaling retains putative features of the mammalian system. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 649,658, 2010 [source] Ontogeny of urine preference and its relationship to NH4Cl preference and sodium hunger in suckling rat pupsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2005Micah Leshem Abstract We chart the postnatal ontogeny of urine preference in the suckling rat. Twelve-day-old sucklings, when offered urine, NH4Cl, or NaCl, ingest more urine and NH4Cl than NaCl. When rendered sodium hungry by ivc renin or by sodium depletion, these sucklings prefer urine and NH4Cl to NaCl, dilute urine, or an NaCl and KCl mineral mix equimolar to urine; however, by 18 days of age, urine and NH4Cl are no longer preferred to NaCl. Hence, urine preference in the suckling may be specific and preparatory for the variety of purposes urine preference serves in the adult rat, and it might guide the pup to urinary sodium in the nest. Since preference for urine and NH4Cl covary during postnatal development, the high preference for NH4Cl in midterm sucklings might be because its ammonium flavor is similar to urine. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 111,117, 2005. [source] Ontogeny of Acoustic and Feeding Behaviour in the Grey Gurnard, Eutrigla gurnardusETHOLOGY, Issue 3 2005M. Clara P. Amorim Although sound production in teleost fish is often associated with territorial behaviour, little is known of fish acoustic behaviour in other agonistic contexts such as competitive feeding and how it changes during ontogeny. The grey gurnard, Eutrigla gurnardus, frequently emits knock and grunt sounds during competitive feeding and seems to adopt both contest and scramble tactics under defensible resource conditions. Here we examine, for the first time, the effect of fish size on sound production and agonistic behaviour during competitive feeding. We have made sound (alone) and video (synchronized image and sound) recordings of grey gurnards during competitive feeding interactions. Experimental fish ranged from small juveniles to large adults and were grouped in four size classes: 10,15, 15,20, 25,30 and 30,40 cm in total length. We show that, in this species, both sound production and feeding behaviour change with fish size. Sound production rate decreased in larger fish. Sound duration, pulse duration and the number of pulses increased whereas the peak frequency decreased with fish size, in both sound types (knocks and grunts). Interaction rate and the frequency of agonistic behaviour decreased with increasing fish size during competitive feeding sessions. The proportion of feeding interactions accompanied by sound production was similar in all size classes. However, the proportion of interactions accompanied by knocks (less aggressive sounds) and by grunts (more aggressive) increased and decreased with fish size, respectively. Taken together, these results suggest that smaller grey gurnards compete for food by contest tactics whereas larger specimens predominantly scramble for food, probably because body size gives an advantage in locating, capturing and handling prey. We further suggest that sounds emitted during feeding may potentially give information on the motivation and ability of the individual to compete for food resources. [source] Ontogeny of sexual dimorphism via tissue duplication in an ostracod (Crustacea)EVOLUTION AND DEVELOPMENT, Issue 2 2009Ajna S. Rivera SUMMARY The adaptive significance of specific sexual dimorphism is well studied. However, the evolutionary history and ontogenic origins of the dimorphism are often unknown. As dimorphism represents two phenotypes generated from relatively similar genotypes, it is of interest to understand both its evolutionary and developmental/genetic underpinnings. Here, we present the first ontogenetic examination of the eyes of philomedid ostracods (Crustacea), which exhibit extremely sexually dimorphic lateral eyes. Adult male philomedids have large compound lateral eyes, whereas females have rudimentary lateral eyes. First, we show that eye dimorphism is unlikely to be due to additional genes present on a male-specific chromosome because karyotype analysis suggests philomedids are XX/XO. We then examine the ontogeny of eye development and find that in at least two species of Euphilomedes, this dimorphism is not generated solely by differences in tissue growth rates, as has been commonly shown for sexually dimorphic characters of other species. Instead, the dimorphism appears to arise during development via tissue duplication, where a single tissue becomes two, perhaps with different developmental potentials. The second eye field is only observed in male Euphilomedes, producing most of the adult eye tissue. We point out that tissue duplication is a developmental process with evolutionary implications because novel characters could evolve via alternative modification of the duplicated fields, analogous to the origin of new genes by gene duplication and alternative modification. Depending on the evolutionary history of the duplicated field, it may have either facilitated or directly caused the observed sexual dimorphism of philomedid ostracods. [source] Ontogeny of escape swimming performance in the spotted salamanderFUNCTIONAL ECOLOGY, Issue 3 2010Tobias Landberg Summary 1.,The life stage suffering the highest predation rate is expected to have the highest escape performance unless developmental or functional constraints interfere. Peak aquatic escape performance in ephemeral pond-breeding amphibians is expected to develop early in the larval period, and metamorphosis is expected to reduce or completely disrupt aquatic escape performance. In anurans, exceptionally low escape performance during metamorphosis creates selection favouring rapid metamorphosis , which minimizes the time individuals spend in the vulnerable transition between tadpole and frog. 2.,We investigated the development of aquatic escape performance in the spotted salamander, Ambystoma maculatum (Shaw, 1802), from embryonic development through metamorphosis. We expected performance to peak early in the larval period as hatchlings face high rates of predation but embryos must first develop escape behaviours. We also tested whether escape performance during metamorphosis was intermediate, as predicted by tail fin resorption, or lower than larvae and adults indicating a major physiological disruption. 3.,Escape performance shows a complex ontogeny that is first positively influenced by embryonic and early larval development and then negatively correlated with tail resorption and body size. Escape distance was the only performance metric not affected by life stage. In contrast, both escape velocity and duration showed ontogenetic peaks early in the larval period with the lowest performance found in early embryos and adults and intermediate performance during metamorphosis. 4.,This pattern suggests that metamorphosis does not impose a major physiological disruption on escape performance. Because spotted salamanders do not pass through a frog-like ,ontogenetic performance valley' during metamorphosis, they may be less subject than anurans to selection favouring rapid metamorphosis. 5.,Functional implications of phenotypic variation should be considered in an ontogenetic framework because the relationship between body size and escape performance can be reversed on either side of an ontogenetic performance peak. The assumption that metamorphosis radically disrupts basic functions such as predator evasion does not seem universally warranted and suggests examination of ontogenetic performance trajectories in a diversity of animals with complex life cycles. [source] Ontogeny of human hepatic cytochromes P450JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 4 2007Ronald N. Hines Abstract Significant changes in drug-metabolizing enzyme (DME) expression occur during ontogeny. Such changes can have a profound effect on therapeutic efficacy in the fetus and child, as well as the risk for adverse drug reactions. To gain a better understanding of DME ontogeny, enzyme contents for six key cytochromes P450 were measured in 240 human liver samples representing ages from 8 weeks gestation to 18 years. Where possible, both quantitative western blotting and activity assays with probe substrates were performed. Although oversimplified, the DME can be grouped into one of three categories. As typified by CYP3A7, some enzymes are expressed at their highest level during the first trimester and either remain at high concentrations or decrease during gestation and are silenced or expressed at low levels within 1,2 years after birth. These data cause one to query whether these enzymes have an important endogenous function. Representatives of a second group, CYP3A5 and CYP2C19, are expressed at relatively constant levels throughout gestation. Postnatal increases in CYP2C19 are observed within the first year, but not for CYP3A5. CYP2C9, 2E1, and 3A4 are more typical of a third group of enzymes that are not expressed or are expressed at low levels in the fetus with the onset of expression generally in either the second or third trimester. Substantial increases in expression are observed within the first 1,2 years after birth; however, considerable interindividual variability is observed in the immediate postnatal (1,6 months) onset or increase in expression of these enzymes, often resulting in a window of hypervariability. © 2007 Wiley Periodicals, Inc. J Biochem Mol Toxicol 21:169,175, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20179 [source] Floral Ontogeny of Two Species in Magnolia L.JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 10 2006Feng-Xia Xu Abstract Floral ontogeny is described in two species of genus Magnolia (Magnoliaceae), Magnolia albosericea Chun et C. Tsoong, and M. amoena Cheng, representing subgenus Magnolia and subgenus Yulania in Magnolia, by using scanning electron microscope (SEM). The sequence of initiation of floral organs is from proximal to distal. The three distinct outermost and middle organs are initiated in sequence, but ultimately form a single whorl, thus their ontogeny is consistent with a sepal interpretation. The last three tepals (petals) alternate with the preceding tepal whorl. The members of androecium and gynoecium arise spirally, although the androecium shows some intermediacy between a spiral and whorled arrangement. The carpel primordia initiate in group of four to five. The order of stamen initiation within each tier is not determined. The floral ontogeny is remarkably homogeneous between the subgenus Magnolia and subgenus Yulania that does not support the resuming of genus Yulania. (Managing editor: Wei Wang) [source] Ontogeny of the complex sperm in the macrostomid flatworm Macrostomum lignano (Macrostomorpha, Rhabditophora)JOURNAL OF MORPHOLOGY, Issue 2 2009Maxime Willems Abstract Spermiogenesis in Macrostomum lignano (Macrostomorpha, Rhabditophora) is described using light- and electron microscopy of the successive stages in sperm development. Ovoid spermatids develop to highly complex, elongated sperm possessing an undulating distal (anterior) process (or "feeler"), bristles, and a proximal (posterior) brush. In particular, we present a detailed account of the morphology and ontogeny of the bristles, describing for the first time the formation of a highly specialized bristle complex consisting of several parts. This complex is ultimately reduced when sperm are mature. The implications of the development of this bristle complex on both sperm maturation and the evolution and function of the bristles are discussed. The assumed homology between bristles and flagellae questioned. J. Morphol., 2009. © 2008 Wiley-Liss, Inc. [source] Pelvic growth: Ontogeny of size and shape sexual dimorphism in rat pelvesJOURNAL OF MORPHOLOGY, Issue 1 2007S. Berdnikovs Abstract The mammalian pelvis is sexually dimorphic with respect to both size and shape. Yet little is known about the differences in postnatal growth and bone remodeling that generate adult sexual dimorphism in pelvic bones. We used Sprague-Dawley laboratory rats (Rattus norvegicus), a species that exhibits gross pelvic size and shape dimorphism, as a model to quantify pelvic morphology throughout ontogeny. We employed landmark-based geometric morphometrics methodology on digitized landmarks from radiographs to test for sexual dimorphism in size and shape, and to examine differences in the rates, magnitudes, and directional patterns of shape change during growth. On the basis of statistical significance testing, the sexes became different with respect to pelvic shape by 36 days of age, earlier than the onset of size dimorphism (45 days), although visible shape differences were observed as early as at 22 days. Males achieved larger pelvic sizes by growing faster throughout ontogeny. However, the rates of shape change in the pelvis were greater in females for nearly all time intervals scrutinized. We found that trajectories of shape change were parallel in the two sexes until age of 45 days, suggesting that both sexes underwent similar bone remodeling until puberty. After 45 days, but before reproductive maturity, shape change trajectories diverged because of specific changes in the female pelvic shape, possibly due to the influence of estrogens. Pattern of male pelvic bone remodeling remained the same throughout ontogeny, suggesting that androgen effects on male pelvic morphology were constant and did not contribute to specific shape changes at puberty. These results could be used to direct additional research on the mechanisms that generate skeletal dimorphisms at different levels of biological organization. J. Morphol., 2006. © 2006 Wiley-Liss, Inc. [source] Ontogeny and homology of the claustra in Otophysan Ostariophysi (Teleostei)JOURNAL OF MORPHOLOGY, Issue 8 2006Ralf Britz Abstract We studied the ontogeny of the claustrum comparatively in representatives of all otophysan subgroups. The claustrum of cypriniforms has a cartilaginous precursor, the claustral cartilage, which subsequently ossifies perichondrally at its anterior face and develops an extensive lamina of membrane bone. The membrane bone component of the claustrum and its close association with the atrium sinus imparis, a perilymphatic space of the Weberian apparatus, are both synapomorphies of cypriniforms. The characiform claustrum is not preformed in cartilage and originates as a membrane bone ossification, a putative synapomorphy of that taxon. Among siluriforms, the claustrum is present only in more basal groups and originates as an elongate cartilage that ossifies in a characteristic ventrodorsal direction, possibly a synapomorphy of catfishes. Gymnotiforms lack the claustral cartilage and claustrum. We review all previous hypothesis of claustrum homology in light of the above findings and conclude that the most plausible hypothesis is the one originally proposed by Bloch ([1900] Jen Z Naturw 34:1,64) that claustra are homologs of the supradorsals of the first vertebra. J. Morphol. © 2006 Wiley-Liss, Inc. [source] Ontogeny of Plurihormonal Cells in the Anterior Pituitary of the Mouse, as Studied by Means of Hormone mRNA Detection in Single CellsJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2002E. Seuntjens Abstract The expression of mRNA of growth hormone (GH), prolactin (PRL), pro-opiomelanocortin (POMC) and the common glycoprotein hormone ,-subunit (,GSU) was studied by means of single cell reverse transcriptase-polymerase chain reaction in male mouse pituitary cells at key time points of fetal and postnatal development: embryonic day 16 (E16); postnatal day 1 (P1) and young-adult age (P38). At E16, the hormone mRNAs examined were detectable, although only in 44% of total cells. Most of the hormone-positive cells expressed only one of the tested hormone mRNAs (monohormonal) but 14% of them contained more than one hormone mRNA (plurihormonal cells). Combinations of GH mRNA with PRL mRNA, of ,GSU mRNA with GH and/or PRL mRNA and of POMC mRNA with GH and/or PRL mRNA or ,GSU mRNA were found. As expected, the proportion of hormone-positive cells rose as the mouse aged. The proportions of plurihormonal cells followed a developmental pattern independent of that of monohormonal cells and characteristic for each hormone mRNA examined. Cells coexpressing POMC mRNA with GH or PRL mRNA significantly rose in proportion between E16 and P1, while the proportion of cells coexpressing GH and PRL mRNA markedly increased between P1 and P38. The occurrence of cells displaying combined expression of ,GSU mRNA with GH and/or PRL mRNA did not significantly change during development. Remarkably, the population of cells expressing PRL mRNA only, was larger at E16 than at P1 and expanded again thereafter. In conclusion, the normal mouse pituitary develops a cell population that is capable of expressing multiple hormone mRNAs, thereby combining typical phenotypes of different cell lineages. These plurihormonal cells are already present during embryonic life. This population is of potential physiological relevance because development-related factors appear to determine which hormone mRNAs are preferentially coexpressed. Coexpression of multiple hormone mRNAs may represent a mechanism to respond to temporally increased endocrine demands. The data also suggest that the control of combined hormone expression is different from that of single hormone expression, raising questions about the current view on pituitary cell lineage specifications. [source] Ontogeny of the Enhanced Fetal-Ethanol-Induced Behavioral and Neurophysiologic Olfactory Response to Ethanol OdorALCOHOLISM, Issue 2 2010Amber M. Eade Background:, Studies report a fundamental relationship between chemosensory function and the responsiveness to ethanol, its component orosensory qualities, and its odor as a consequence of fetal ethanol exposure. Regarding odor, fetal exposed rats display enhanced olfactory neural and behavioral responses to ethanol odor at postnatal (P) day 15. Although these consequences are absent in adults (P90), the behavioral effect has been shown to persist into adolescence (P37). Given the developmental timing of these observations, we explored the decay in the response to ethanol odor by examining ages between P37 and young adulthood. Moreover, we sought to determine whether the P15 neurophysiologic effect persists, at least, to P40. Methods:, Behavioral and olfactory epithelial (OE) responses of fetal ethanol exposed and control rats were tested at P40, P50, P60, or P70. Whole-body plethysmography was used to quantify each animal's innate behavioral response to ethanol odor. We then mapped the odorant-induced activity across the OE in response to different odorants, including ethanol, using optical recording methods. Results:, Relative to controls, ethanol exposed animals showed an enhanced behavioral response to ethanol odor that, while significant at each age, decreased in magnitude. These results, in conjunction with previous findings, permitted the development of an ontologic odor response model of fetal exposure. The fitted model exemplifies that odor-mediated effects exist at birth, peak in adolescence and then decline, becoming absent by P90. There was no evidence of an effect on the odor response of the OE at any age tested. Conclusions:, Fetal exposure yields an enhanced behavioral response to ethanol odor that peaks in adolescence and wanes through young adulthood. This occurs absent an enhanced response of the OE. This latter finding suggests that by P40 the OE returns to an ethanol "neutral" status and that central mechanisms, such as ethanol-induced alterations in olfactory bulb circuitry, underlie the enhanced behavioral response. Our study provides a more comprehensive understanding of the ontogeny of fetal-ethanol-induced olfactory functional plasticity and the behavioral response to ethanol odor. [source] Ethanol-Mediated Fetal Dysmorphology and its Relationship to the Ontogeny of Maternal Liver MetallothioneinALCOHOLISM, Issue 6 2009Peter Coyle Background:, Fetal zinc (Zn) deficiency arising from ethanol-induction of the Zn-binding protein metallothionein (MT) in the mother's liver has been proposed as a mechanism of teratogenicity. Here, we determine the ontogeny of MT and Zn homeostasis in rats and mice and then examine the effect of acute ethanol exposure in early embryonic development on this relationship. The protective effect of Zn against ethanol-mediated fetal dysmorphology is also examined. Methods:, Study 1: Maternal liver MT and Zn homeostasis was determined in Sprague,Dawley rats and C57BL/6J mice throughout gestation. Study 2: Rats were administered ethanol (25% in saline, intraperitoneal 0.015 ml/g) or vehicle alone on gestational day (GD) 9. Maternal liver MT and Zn, and plasma Zn was determined over the ensuing 24 hours. Study 3: Pregnant rats were treated with ethanol and Zn (s.c. 2.5 ,g Zn/g) on GD9 and fetal dysmorphology was assessed on GD 19. Results:, Study 1: Maternal liver MT began to rise around GD 9 peaking on GD 15 before falling to nonpregnant levels around term. The pregnancy-related increase in MT was associated with a fall in plasma Zn which was significantly lower on GD 15 thereafter returning to nonpregnant levels by parturition. Study 2: Ethanol administered to pregnant rats on GD 9 resulted in a 10-fold induction of MT in the maternal liver and was associated with a 33% rise in liver Zn and a 30% fall in plasma Zn, 16 hours after treatment. Study 3: Ethanol treatment on GD 9 resulted in a significant increase in craniofacial malformations which were prevented by concurrent Zn treatment. Conclusions:, The findings indicate that maternal liver MT levels are lowest in early gestation (before GD 10) making this a sensitive period where ethanol-induction of MT can affect fetal Zn homeostasis and cause fetal dysmorphology. The study further provides evidence of a protective role for Zn against ethanol-mediated teratogenicity. [source] Acute, Rapid, and Chronic Tolerance During Ontogeny: Observations When Equating Ethanol Perturbation Across AgeALCOHOLISM, Issue 9 2001Marisa M. Silveri Background: Sensitivity to the motor-impairing and hypnotic effects of ethanol (EtOH) increases notably during development. Less is known, however, about the ontogeny of EtOH tolerance and the ontogenetic relationship among different types of tolerance. Consequently, we compared the ontogenetic development of acute, rapid, and chronic tolerance to EtOH-induced motor impairment and hypothermia in a swim task. Methods: Preweanling, adolescent, and adult female and male Sprague-Dawley rats were given chronic saline (control group), five daily EtOH exposures before EtOH on test day (chronic group), one EtOH exposure before test day (rapid group), or EtOH exposure only on test day (acute groups). Separate groups of animals in the acute groups were tested at 15, 60, or 105 min after injection to estimate acute tolerance development via calculating slopes of the linear regression of impairment relative to brain alcohol levels at each postinjection interval. Initial EtOH perturbation of swim performance was equated across age by varying EtOH dose. Results: Acute tolerance was evident to the motor-impairing effects of EtOH at all ages. When impairment was indexed relative to brain alcohol levels, rapid and chronic tolerance to the motor-impairing effects of EtOH on latency to reach the start was seen across age, although this tolerance tended to be more pronounced in adults. Somewhat different ontogenetic patterns of tolerance development were observed with EtOH-induced hypothermia, a dependent measure for which EtOH perturbation was not equated across age. Conclusions: The degree of initial perturbation by EtOH seems to be an important predictor of tolerance expression during ontogeny. That is, ontogenetic profiles of tolerance development differ significantly when EtOH-induced motor impairment is equated across age rather than dose of EtOH administered . The role of target response measures and context stress should also be considered when exploring ontogenetic expression of EtOH tolerance. [source] Ontogeny and sexual dimorphism in booted macaques (Macaca ochreata)JOURNAL OF ZOOLOGY, Issue 1 2005Michael A. Schillaci Abstract Ontogeny and sexual dimorphism have been important topics of investigation among researchers interested in the life history and ecology of non-human primates. It has been suggested that sex differences in the duration of growth are primarily, but not entirely, responsible for the sexual dimorphism observed in primate species with multimale,multifemale social structure, such as that seen in macaque monkeys (subfamily Cercopithecinae). Sexual dimorphism and growth was investigated in a wild population of booted macaques Macaca ochreata from Sulawesi, Indonesia. The results of our investigation suggest that the observed dimorphism in this population is primarily a product of greatly increased growth rates in dentally mature young adult males, in addition to prolonged male growth. This pattern of male growth may be an adaptive response to reduce the risk of adult male aggression before obligatory male emigration, and to facilitate competition for females soon after immigration into a new social group. [source] Ontogeny and life-history strategy of Barycrinus (Crinoidea, Mississippian)LETHAIA, Issue 2 2009KATHY A. HOLLIS Discovery of an encrusting juvenile holdfast assigned to the Mississippian crinoid Barycrinus demonstrates that this stalked crinoid had a complex life history. The free-swimming larva settled to become a hard substratum encrusting juvenile, which broke free to become a free-living adult rooted into an unconsolidated substratum. Furthermore, additional small, encrusting holdfast types suggest that this was a common life-history strategy among Mississippian crinoids and, perhaps, blastoids. [source] Ontogeny of the androgen receptor expression in the fetal and postnatal testis: Its relevance on Sertoli cell maturation and the onset of adult spermatogenesisMICROSCOPY RESEARCH AND TECHNIQUE, Issue 11 2009Rodolfo A. Rey Abstract From fetal life to adulthood, the testis evolves through maturational phases showing specific morphologic and functional features in its different compartments. The seminiferous cords contain Sertoli and germ cells, surrounded by peritubular cells, and the interstitial tissue contains Leydig cells and connective tissue. Sertoli cells secrete anti-Müllerian hormone (AMH), whereas Leydig cells secrete androgens. In the fetal and early postnatal testis, Leydig cells actively secrete androgens. Sertoli cells are morphologically and functionally immature,e.g., they secrete high levels of AMH,and germ cells proliferate by mitosis but do not enter meiosis. During infancy and childhood, Leydig cells regress and testosterone secretion declines dramatically. Sertoli cells remain immature and spermatogenesis is arrested at the premeiotic stage. At puberty, Leydig cells differentiate again, and testosterone concentration increases and provokes Sertoli cell maturation,e.g., down-regulation of AMH expression,and germ cells undergo meiosis, the hallmark of adult spermatogenesis driving to sperm production. An intriguing feature of testicular development is that, although testosterone production is as active in the fetal and early postnatal periods as in puberty, Sertoli cells and spermatogenesis remain immature until pubertal onset. Here, we review the ontogeny of the androgen receptor expression in the testis and its impact on Sertoli cell maturation and the onset of pubertal spermatogenesis. We show that the absence of androgen receptor expression in Sertoli cells underlies a physiological stage of androgen insensitivity within the male gonad in the fetal and early postnatal periods. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc. [source] Ontogeny of robusticity of craniofacial traits in modern humans: A study of South American populationsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010Paula N. Gonzalez Abstract To date, differences in craniofacial robusticity among modern and fossil humans have been primarily addressed by analyzing adult individuals; thus, the developmental basis of such differentiation remains poorly understood. This article aims to analyze the ontogenetic development of craniofacial robusticity in human populations from South America. Geometric morphometric methods were used to describe cranial traits in lateral view by using landmarks and semilandmarks. We compare the patterns of variation among populations obtained with subadults and adults to determine whether population-specific differences are evident at early postnatal ontogeny, compare ontogenetic allometric trajectories to ascertain whether changes in the ontogeny of shape contribute to the differentiation of adult morphologies, and estimate the amount of size change that occurs during growth along each population-specific trajectory. The results obtained indicate that the pattern of interpopulation variation in shape and size is already established at the age of 5 years, meaning that processes acting early during ontogeny contribute to the adult variation. The ontogenetic allometric trajectories are not parallel among all samples, suggesting the divergence in the size-related shape changes. Finally, the extension of ontogenetic trajectories also seems to contribute to shape variation observed among adults. Am J Phys Anthropol 2010. © 2009 Wiley-Liss, Inc. [source] Effects of Temperature Regime Through Premetamorphic Ontogeny on Shape of the Chondrocranium in the American Toad, Anaxyrus americanusTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 7 2008Michael E. Jorgensen Abstract If one considers the substantial amount of information that exists about phenotypic plasticity in amphibians, it is surprising that few studies have examined abiotic factors that influence phenotype through ontogeny. Phenotypic change and stability of morphology are artifacts of organisms that bear significant relevance to evolution within and among taxonomic groups. Here, we examine development as a phenotypically plastic aspect of larval anurans. Fertilized eggs of the American Toad, Anaxyrus (= Bufo) americanus (Holbrook, 1836), were obtained from two pairs of adults, and larvae were reared in four temperature treatments (constant Mean, constant High, constant Low, and Fluctuating regime [Low night,High day]); developmental series were collected from each treatment, representing larvae of this species from Gosner Stages 28,40. Cleared and stained larvae were analyzed with landmark-based geometric morphometric methods to facilitate examination of differences in overall shape change of the larval chondrocranium through ontogeny, as a result of developmental temperature or temperature regime. Changes in shape of the chondrocranium and in amount and direction of phenotypic change through ontogeny were found in response to temperature treatment and temperature regime. Mean chondrocranial shape of the Fluctuating regime was more similar to the consensus shape of the overall data set than were those of all other treatments. Given that differences in amount and direction of shape change were observed among these treatments and throughout ontogeny, one should consider the affects of abiotic factors (such as temperature) when rearing larval anurans for studies of developmental morphology. Anat Rec, 291:818-826, 2008. © 2008 Wiley-Liss, Inc. [source] Ontogeny and phyletic size change in living and fossil lemursAMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2010Matthew J. Ravosa Abstract Lemurs are notable for encompassing the range of body-size variation for all primates past and present,close to four orders of magnitude. Benefiting from the phylogenetic proximity of subfossil lemurs to smaller-bodied living forms, we employ allometric data from the skull to probe the ontogenetic bases of size differentiation and morphological diversity across these clades. Building upon prior pairwise comparisons between sister taxa, we performed the first clade-wide analyses of craniomandibular growth allometries in 359 specimens from 10 lemuroids and 176 specimens from 8 indrioids. Ontogenetic trajectories for extant forms were used as a criterion of subtraction to evaluate morphological variation, and putative adaptations among sister taxa. In other words, do species-level differences in skull form result from the differential extension of common patterns of relative growth? In lemuroids, a pervasive pattern of ontogenetic scaling is observed for facial dimensions in all genera, with three genera also sharing relative growth trajectories for jaw proportions (Lemur, Eulemur, Varecia). Differences in masticatory growth and form characterizing Hapalemur and fossil Pachylemur likely reflect dietary factors. Pervasive ontogenetic scaling characterizes the facial skull in extant Indri, Avahi, and Propithecus, as well as their larger, extinct sister taxa Mesopropithecus and Babakotia. Significant interspecific differences are observed in the allometry of indrioid masticatory proportions, with variation in the mechanical advantage of the jaw adductors and stress-resisting elements correlated with diet. As the growth series and adult data are largely coincidental in each clade, interspecific variation in facial form may result from selection for body-size differentiation among sister taxa. Those cases where trajectories are discordant identify potential dietary adaptations linked to variation in masticatory forces during chewing and biting. Although such dissociations highlight selection to uncouple shared ancestral growth patterns, they occur largely via transpositions and retention of primitive size-shape covariation patterns or relative growth coefficients. Am. J. Primatol. 72:161,172, 2010. © 2009 Wiley-Liss, Inc. [source] Ontogeny of the shi drum Umbrina cirrosa (Linnaeus 1758), a candidate new species for aquacultureAQUACULTURE RESEARCH, Issue 13 2005Giorgos Koumoundouros Abstract The ontogeny of shi drum Umbrina cirrosa (Linnaeus 1758), a candidate new species for aquaculture, was studied throughout the entire larval phase. Geometric morphometric analysis revealed two clear inflection points (7.0 and 12.7 mm total length, TL) in the shape ontogeny of this species, separating the studied period into three phases of different allometric priorities. Spline graphs demonstrated that the major non-uniform shape ontogeny correlated with the development of the fins, the anterior dorsal area of the body, the caudal peduncle, the eye and the mouth. Concerning the morphological features, shi drum larvae are characterized by an upward anterior bending of the notochord. The ontogeny of the fins began with the formation of the pectoral buds (2.9 mm TL), continued with the notochord flexion (4.3 mm TL, associated with the caudal fin development), the appearance of the pelvic buds, the first anal rays (4.5 mm TL) and the first dorsal rays (4.8 mm TL). Shi drum juveniles presented 25 vertebrae and the following dominant fin types: D XI,23, AII,6, VI,5, P17 and C17. [source] Ontogeny of immune system organs in northern bluefin tuna (Thunnus orientalis, Temminck and Schlegel 1844)AQUACULTURE RESEARCH, Issue 1 2003M Watts Abstract Serial sections, prepared from 0.5 to 30 days posthatch (dph) larval and juvenile Thunnus orientalis (Temminck & Schlegel 1844), were stained with haematoxylin and eosin and examined by light microscopy for immune organ development. The early kidney was present at 0.5 dph, undifferentiated stem cells began to appear at 2 dph, and by 7 dph occasional small lymphocytes were present. The thymus was first obvious at 5 dph, located above the fourth branchial arch, small lymphocytes appeared at 7 dph, and by 15 dph an outer thymocytic zone and an inner epithelioid zone were visible. The progenitor spleen was present at 2 dph, located close to the gut, and by 12 dph it consisted of a mass of sinusoids filled with red blood cells, and remained mainly erythroid throughout the period studied. These results suggest that development of immune organs in this species is precocious relative to other marine teleosts. [source] SPATIOTEMPORAL REORGANIZATION OF GROWTH RATES IN THE EVOLUTION OF ONTOGENYEVOLUTION, Issue 4 2000Miriam L. Zelditch Abstract. Heterochrony, evolutionary changes in rate or timing of development producing parallelism between ontogeny and phylogeny, is viewed as the most common type of evolutionary change in development. Alternative hypotheses such as heterotopy, evolutionary change in the spatial patterning of development, are rarely entertained. We examine the evidence for heterochrony and heterotopy in the evolution of body shape in two clades of piranhas. One of these is the sole case of heterochrony previously reported in the group; the others were previously interpreted as cases of heterotopy. To compare ontogenies of shape, we computed ontogenetic trajectories of shape by multivariate regression of geometric shape variables (i.e., partial warp scores and shape coordinates) on centroid size. Rates of development relative to developmental age and angles between the trajectories were compared statistically. We found a significant difference in developmental rate between species of Serrasalmus, suggesting that heterochrony is a partial explanation for the evolution of body shape, but we also found a significant difference between their ontogenetic transformations; the direction of the difference between them suggests that heterotopy also plays a role in this group. In Pygocentrus we found no difference in developmental rate among species, but we did find a difference in the ontogenies, suggesting that heterotopy, but not heterochrony, is the developmental basis for shape diversification in this group. The prevalence of heterotopy as a source of evolutionary novelty remains largely unexplored and will not become clear until the search for developmental explanations looks beyond heterochrony. [source] Spatial and Temporal Ontogenies of Glutathione Peroxidase and Glutathione Disulfide Reductase During Development of the Prenatal RatJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 4 2001Hyungsuk Choe Abstract Spatial and temporal expression and regulation of the antioxidant enzymes, glutathione peroxidase (GSH-Px), glutathione disulfide reductase (GSSG-Rd) may be important in determining cell-specific susceptibility to embryotoxicants. Creation of tissue-specific ontogenies for antioxidant enzyme activities during development is an important first step in understanding regulatory relationships. Early organogenesis-stage embryos were grouped according to the somite number (GD 9,13), and fetuses were evaluated by gestational day (GD 14,21). GSH-Px activities in the visceral yolk sac (VYS) increased on consecutive days from GD 9 to GD 13, representing a 5.7-fold increase during this period of development. GSH-Px activities in VYS decreased after GD 13, ultimately constituting a 37% decrease at GD 21. Head, heart, and trunk specific activities generally increased from GD 9 to GD 13 albeit not to the same magnitude as detected in the VYS. GSSG-Rd activities showed substantial increases in the VYS from GD 9 to GD 13, 6.3-fold and decreased thereafter to 50% by GD 21. The greatest changes in enzyme activities were noted in the period between GD 10 and GD 11, where the embryo establishes an active cardiovascular system and begins to convert to aerobic metabolism. Generally, from GD 14,21, embryonic organ GSH-Px and GSSG-Rd activities either remained constant or increased as gestation progressed. These studies suggest the importance of the VYS in dealing with ROS and protecting the embryo. Furthermore, understanding the consequences of lower antioxidant activities during organogenesis may help to pinpoint periods of teratogenic susceptibility to xenobiotics and increased oxygen. © 2001 John Wiley & Sons, Inc. J Biochem Mol Toxicol 15:197,206, 2001 [source] | ||||||||||||||||||||||||||||||||||||||||||||||