771 resultados para skull ontogeny
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The pattern of change in shape during postnatal development in skulls of punare (Thrichomys apereoides) skulls, was studied by geometric morphometric techniques. Skull shape observed in T. apereoides varied both with size and age, but variation in size explains most of the overall change in shape. Differences in shape observed among the eight age categories showed that main changes in shape occurred principally between the first and second age categories. Among the other age classes, changes became less pronounced leading to elongation of the snout and the mid-face and narrowing of the basicranium. The change in global shape resulted in lateral compression of the skull. Despite the high level of integration observed, localized transformations dominated the ontogenetic changes in shape indicating the presence of two large scale cranium components-the orofacial and the basicranial region. The ontogenetic pattern in this species seems to follow the same trends observed in the initial phases of development.
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We studied ontogenetic variation in the shape of the skull among species of Caiman using principal component analysis. Comparison of multivariate allometric coefficients and ontogenetic trends between size and shape reveals that C. sclerops and C. yacare have similar ontogenetic processes, and they are more related to each other than either is to C. latirostris. Allometric relationships of the characters measured are similar in all species studied. The greater differences were in the width measurements, with higher coefficients in shape (second principal component) for C. latirostris, and length measurements with higher coefficients in shape for C. yacare and C. sclerops. The ontogenetic process leading to change in skull shape in the group seems to be plesiomorphic for elongation and derived for broadening. Statistical comparison of the ontogenetic trends with models of allometric heterochrony suggests that C. latirostris has diverged from the other species by a neotenic process, and that C. sclerops is separated from C. yacare by ontogenetic scaling (progenesis).
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Despite the fact that heterochronic processes seem to be an important process determining morphological evolution of the delphinid skull, previous workers have not found allometric scaling as relevant factor in the differentiation within the genus Sotalia. Here we analyzed the skull ontogeny of the estuarine dolphin S. guianensis and investigate differential growth and shape changes of two cranial regions the neurocranium and the face in order to evaluate the relevance of cranial compartmentalization on the ontogeny of this structure. Our results show that, even though both cranial regions stop growing at adulthood, the face has higher initial growth rates than the neurocranium. The rate of shape changes is also different for both regions, with the face showing a initially higher, but rapidly decreasing rate of change, while the neurocranium shows a slow decreasing rate, leading to persistent and localized shape changes throughout adult life, a pattern that could be related to epigenetic regional factors. The pattern of ontogenetic shape change described here is similar to those described for other groups of Delphinidae and also match intra and interspecific variation found within the family, suggesting that mosaic heterochrony could be an important factor in the morphological evolution of this group. (C) 2012 Deutsche Gesellschaft fur Saugetierkunde. Published by Elsevier GmbH. All rights reserved.
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The study of the contributions of different bones to the formation of the skeleton in birds is necessary: (1) to establish homologies in comparative anatomy; (2) to delimit each bone structure correctly, mainly in relation to the skull and mandible where the bones are fused to each other in adults; and (3) to standardize nomenclature in avian osteology. In this paper at least one young specimen belonging to each sub-family of Cuculidae was examined in order to identify each bone in terms of boundaries and contributions to skull and mandible formation. These cuckoos specimens were also compared with adults and young of turacos and hoatzin. The results show little variation of skull and jaw among the young cuckoos studied compared with the variations among adult specimens. However, it provides new suggestions for the boundaries and nomenclature of certain osseous structures in the skull and mandible of birds, specifically fissura zona flexoria craniofacialis, prominetia frontoparietalis, crista temporalis transversa, processus squamosalis, fossa laterosphenoidalis, tuberculum laterosphenoidale and processus retroangularis. This study also provides more reliable homologies for use in cladistic analysis and above all it contributes to the phylogenetic position of Cuculidae within Neognathae, specifically the skull formation suggest that turacos and hoatzin are more similar to each other than either is to the cuckoos. © 2005 Taylor & Francis.
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The ontogeny of muscarinic receptors was studied in human fetal striatum, brainstem, and cerebellum to investigate general principles of synaptogenesis as well as the physiological balance between various chemical synapses during development in a given region of the brain. [3H]Quinuclidinyl benzilate ([-'H]QNB) binding was assayed in total particulate fraction (TPF) from various parts of brain. In the corpus striatum, QNB binding sites are present at 16 weeks of gestation (average concentration 180 fmol/mg protein of TPF), slowly increase up to 24 weeks (average concentration 217 fmol/mg protein), and rapidly increase during the third trimester to 480 fmol/mg protein of TPF. In contrast, dopaminergic receptors exist as two subpopulations. one with low affinity and the other with high affinity up to the 24th week of gestation; all of them acquire the highaffinity characteristic during the third trimester. In brainstem, the muscarinic receptors show maximum concentration by 16 weeks of age (360 fmolimg protein of TPF). Subsequently the muscarinic receptor concentration shows a gradual decline in the brainstem. In cerebellum, except for a slight increase at 24 weeks (average concentration 90 fmol/mg protein of TPF), the receptor concentration remained nearly constant at about 60-70 fmolimg protein of TPF throughout fetal life. This study demonstrates that the ontogeny of muscarinic receptors varies among the different regions, and the patterns observed suggest that receptor formation occurs principally in the third trimester. Also noteworthy is the finding that the QNB binding sites decreased in all regions of the human brain during adult life. Key Words: Cholinergic muscarinic receptors-Quinuclidinyl benzilate-Corpus striaturn-Brainstem-Cerebellum. Ravikumar B. V. and Sastry P. S. Cholinergic muscarinic receptors in human fetal brain: Ontogeny of [3H]quinuclidinyl benzilate binding sites in corpus striatum, brainstem, and cerebellum. J. Neurochem. 45, 1948- 1950 (1985).
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We evaluated the development of the exocrine pancreas in 16 healthy preterm infants (29.3 ± 1.6 weeks). The infants were fed breast milk with formula supplements (n=8) or formula alone (n=8). Growth was monitored weekly for 12 weeks then at 3, 6, 9, 12 months. At the same intervals sera were determined for pancreatic lipase and cationic trypsinogen. In addition, cord blood samples were analysed from another 33 preterm (27.6 ± 5.2 weeks) and 75 healthy full-term infants. Serum pancreatic lipase in the cord blood of term (3.7 ± 0.4 μg/l) and preterm infants (1.8 ± 0.2 μg/l) was significantly below values reported for older children (10.5 ± 0.9 μg/l; p < 0.001). In the preterm infant, serum lipase was also significantly lower than values obtained at term (p < 0.001). At birth, serum trypsinogen for preterm (16.8 ± 1.3 μg/l) and term infants (23.3 ± 1.9 μg/l) were below those for older children (31.4 ± 3.7 μg/l; p < 0.05). Over the first 3 weeks of life, serum lipase and trypsinogen increased significantly. From 3 weeks to 12 months of age, serum trypsinogen values remained unchanged, but serum lipase increased dramatically after 10 weeks of age. Thus, at 6 and 12 months of age, the preterm infants had significantly higher serum lipase values than infants of the same age born at term. These two pancreatic enzymes appear to show independent age-related maturation in infants born before term. The rate of maturation of lipase appears to be accelerated by exposure to the extrauterine environment.
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The introgression of domestic dog genes into dingo populations threatens the genetic integrity of 'pure' dingoes. However, dingo conservation efforts are hampered by difficulties in distinguishing between dingoes and hybrids in the field. This study evaluates consistency in the status of hybridisation (i.e. dingo, hybrid or dog) assigned by genetic analyses, skull morphology and visual assessments. Of the 56 south-east Queensland animals sampled, 39 (69.6%) were assigned the same status by all three methods, 10 (17.9%) by genetic and skull methods, four (7.1%) by genetic and visual methods; and two (3.6%) by skull and visual methods. Pair-wise comparisons identified a significant relationship between genetic and skull methods, but not between either of these and visual methods. Results from surveying 13 experienced wild dog managers showed that hybrids were more easily identified by visual characters than were dingoes. A more reliable visual assessment can be developed through determining the relationship between (1) genetics and phenotype by sampling wild dog populations and (2) the expression of visual characteristics from different proportions and breeds of domestic dog genes by breeding trials. Culling obvious hybrids based on visual characteristics, such as sable and patchy coat colours, should slow the process of hybridisation.
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We have evaluated the potential of a formulated diet as a replacement for live and fresh feeds for 7-day post-hatch Panulirus ornatus phyllosomata and also investigated the effect of conditioning phyllosomata for 14-21 days on live feeds prior to weaning onto a 100% formulated diet. In the first trial, the highest survival (>55%) was consistently shown by phyllosomata fed a diet consisting of a 50% combination of Artemia nauplii and 50% Greenshell mussel, followed by phyllosomata fed 50% Artemia nauplii and 50% formulated diet and, thirdly, by those receiving 100% Artemia nauplii. The second trial assessed the replacement of on-grown Artemia with proportions of formulated diet and Greenshell mussel that differed from those used in trial 1. Phyllosomata fed a 75% combination of formulated diet and 25% on-grown Artemia and 50% on-grown Artemia and 50% Greenshell mussel consistently showed the highest survival (>75%). Combinations of Greenshell mussel and formulated diet resulted in significantly (P < 0.05) reduced survival. In trial 3, phyllosomata were conditioned for 14, 18 or 21 days on Artemia nauplii prior to weaning onto a 100% formulated diet, which resulted in survival rates that were negatively related to the duration of feeding Artemia nauplii. In the final trial, phyllosomata were conditioned for 14 days on live on-grown Artemia prior to weaning onto one of three formulated diets (one diet with 44% CP and two diets with 50%). Phyllosomata fed a 44% CP diet consistently showed the highest survival (>35%) among all treatments, while those fed a 50%-squid CP diet showed a significant (P < 0.05) increase in mortality at day 24. The results of these trials demonstrate that hatcheries can potentially replace 75% of live on-grown Artemia with a formulated diet 7 days after hatch. The poor performance associated with feeding combinations of Greenshell mussel and formulated diet, and 100% formulated diet as well as conditioning phyllosomata for 14-21 days on live feeds prior to weaning onto a formulated diet highlights the importance of providing Artemia to stimulate feeding.
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Predation forms one of the main selective forces in nature and in a vast number of prey species the behavioural responses form the main way to avoid predation. World wide numerous captive breeding programs are used to produce fish and other animal species for conservational reintroductions. However, rearing animals in the absence of predators in captivity has been shown to weaken their predator avoidance skills and lead to behavioural divergence between wild and captive-bred populations. In my thesis I studied the effects of predator odour exposures on antipredator behavioural and physiological responses of captive reared Saimaa Arctic charr. This charr population is the most endangered fish population in Finland and a sample of the remaining population has been taken to captive breeding and used for an extensive reintroduction program. Lowered responsiveness to predators is probably one of the major reasons for the poor survival probability of the charr after release into the wild. The main aims of my thesis were to explore the reasons for behavioural phenotypic variation in this charr population and whether naïve charr young could be trained to recognise their natural predators. The predator species in my thesis were burbot (Lota lota) and pikeperch (Sander lucioperca). In my thesis I showed that the captive-bred charr responded to chemical cues from burbot and pikeperch, but the magnitude of responses was linked to the predator species. The burbot odour increased the spatial odour avoidance of the charr young. On the other hand, in the pikeperch treatment charr reduced their relative swimming activity and tended to show more freezing behaviour relative to the burbot treatment. It seems evident that these different responses are related to the different hunting tactics of predator species. Furthermore, I detected wide between-family differences in antipredator responsiveness (i.e. inherited variation in antipredator behaviours) in this captive stock. Detected differences were greater in the response towards burbot than towards pikeperch. These results, in addition to predator-specific antipredator responses, suggest that there is a clear inherited component in antipredator responsiveness in Saimaa charr population and that the detected inherited differences could explain a part of the behavioural phenotypic variation in this population. In my thesis I also found out that both social learning and direct exposure to live predators enhance the antipredator responsiveness of charr young. In addition, I obtained indications that predator odour exposures (i.e. life-skills training) in alevin and fry stages can fine-tune the innate antipredator responsiveness of charr. Thus, all these methods have the potential to enhance the innate antipredator responsiveness of naïve charr young, possibly also improving the post-release survival of these trained individuals in the wild. However, the next logical phase would be to carry out large scale survival studies in the wild to test this hypothesis. Finally, the results of my thesis emphasize that possible long-term life-skills training methods should take into account not only the behavioural but also the physiological effects of training.
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The purpose of this work was to elucidate the ontogeny of interleukin-10 (IL-10) secretion from newborn mononuclear cells (MCs), and to examine its relation to the secretion of interferon-g (IFN-g) and immunoglobulins (Igs). The initial hypothesis was that the decreased immunoglobulin (Ig) synthesis of newborn babies was the result of immature cytokine synthesis regulation, which would lead to excessive IL-10 production, leading in turn to suppressed IFN-g secretion. Altogether 57 full-term newborns and 34 adult volunteers were enrolled. Additionally, surface marker compositions of 29 premature babies were included. Enzyme-linked immunoassays were used to determine the amount of secreted IL-10, IFN-g, and Igs, and the surface marker composition of MC were analyzed with a FACScan flow cytometer. The three most important findings were: 1. Cord blood MC, including CD5+ B cells, are able to secrete IL-10. However, when compared with adults, the secretion of IL-10 was decreased. This indicates that reasons other than excessive IL-10 secretion are responsible of reduced IFN-g secretion in newborns. 2. As illustrated by the IL-10 and IFN-g secretion pattern, newborn cytokine profile was skewed towards the Th2 type. However, approximately 25% of newborns had an adult like cytokine profile with both good IL10 and IFN-g secretion, demonstrating that fullterm newborns are not an immunologically homogenous group at the time of birth. 3. There were significant differences in the surface marker composition of MCs between individual neonates. While gestational age correlated with the proportion of some MC types, it is evident that there are many other maternal and fetal factors that influence the maturity and nature of lymphocyte subpopulations in individual neonates. In conclusion, the reduced ability of neonates to secrete Ig and IFN-g is not a consequence of high IL-10 secretion. However, individual newborns differ significantly in their ability to secrete cytokines as well as Igs.
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Eighteen corpora striata from normal human foetal brains ranging in gestational age from 16 to 40 weeks and five from post natal brains ranging from 23 days to 42 years were analysed for the ontogeny of dopamine receptors using [3H]spiperone as the ligand and 10 mM dopamine hydrochloride was used in blanks. Spiperone binding sites were characterized in a 40-week-old foetal brain to be dopamine receptors by the following criteria: (1) It was localized in a crude mitochondrial pellet that included synaptosomes; (2) binding was saturable at 0.8 nM concentration; (3) dopaminergic antagonists spiperone, haloperidol, pimozide, trifluperazine and chlorpromazine competed for the binding with IC50 values in the range of 0.3–14 nM while agonists—apomorphine and dopamine gave IC50 values of 2.5 and 10 μM, respectively suggesting a D2 type receptor.Epinephrine and norepinephrine inhibited the binding much less efficiently while mianserin at 10 μM and serotonin at 1 mM concentration did not inhibit the binding. Bimolecular association and dissociation rate constants for the reversible binding were 5.7 × 108 M−1 min−1 and 5.0 × 10−2 min−1, respectively. Equilibrium dissociation constant was 87 pM and the KD obtained by saturation binding was 73 pM.During the foetal age 16 to 40 weeks, the receptor concentration remained in the range of 38–60 fmol/mg protein or 570–1080 fmol/g striatum but it increased two-fold postnatally reaching a maximum at 5 years Significantly, at lower foetal ages (16–24 weeks) the [3H]spiperone binding sites exhibited a heterogeneity with a high (KD, 13–85 pM) and a low (KD, 1.2–4.6 nM) affinity component, the former accounting for 13–24% of the total binding sites. This heterogeneity persisted even when sulpiride was used as a displacer. The number of high affinity sites increased from 16 weeks to 24 weeks and after 28 weeks of gestation, all the binding sites showed only a single high affinity.GTP decreased the agonist affinity as observed by dopamine competition of [3H]spiperone binding in 20-week-old foetal striata and at all subsequent ages. GTP increased IC50 values of dopamine 2 to 4.5 fold and Hill coefficients were also increased becoming closer to one suggesting that the dopamine receptor was susceptible to regulation from foetal life onwards.
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Social insects are characterized by reproductive caste differentiation of colony members into one or a small number of fertile queens and a large number of sterile workers. The evolutionary origin and maintenance of such sterile workers remains an enduring puzzle in insect sociobiology. Here, we studied ovarian development in over 600 freshly eclosed, isolated, virgin female Ropalidia marginata wasps, maintained in the laboratory. The wasps differed greatly both in the time taken to develop their ovaries and in the magnitude of ovarian development despite having similar access to resources. All females started with no ovarian development at day zero, and the percentage of individuals with at least one oocyte at any stage of development increased gradually across age, reached 100% at 100. days and decreased slightly thereafter. Approximately 40% of the females failed to develop ovaries within the average ecological lifespan of the species. Age, body size and adult feeding rate, when considered together, were the most important factors governing ovarian development. We suggest that such flexibility and variation in the potential and timing of reproductive development may physiologically predispose females to accept worker roles and thus provide a gateway to worker ontogeny and the evolution of sociality.
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The ontogeny of haematopoiesis in the perciform fish, spot Leiostomus xanthurus, differed from that reported as the norm for fishes, as exemplified by the cypriniform zebrafish Danio rerio, and observed in the batrachoidiform oyster toadfish Opsanus tau. Erythropoiesis in spot was first evident in the head kidney of yolk-sac larvae 3 days after hatching (DAH). No embryonic intermediate cell mass (ICM) of primitive stem cells or blood islands on the yolk were apparent within embryos. Erythrocytes were first evident in circulation near the completion of yolk absorption, c. 5 DAH, when larvae were c. 20 mm notochord length (LN). Erythrocyte abundance increased rapidly with larval development for c. 14 to 16 DAH, then became highly variable following changes in cardiac chamber morphology and volume. Erythrocytic haemoglobin (Hb) was not detected within whole larvae until they were 12 DAH or c. 31 mm LN, well after yolk and oil-globule absorption. The Hb was not quantified until larvae were >47 DAH or >7 mm standard length. The delayed appearance of erythrocytes and Hb in spot was similar to that reported for other marine fishes with small embryos and larvae. In oyster toadfish, a marine teleost that exhibits large embryos and larvae, the ICM and Hb were first evident in two bilateral slips of erythropoietic tissue in the embryos, c. 5 days after fertilization. Soon thereafter, erythrocytes were evident in the heart, and peripheral and vitelline circulation. Initial haematopoiesis in oyster toadfish conformed with that described for zebrafish. While the genes that code for the development of haematopoiesis are conserved among vertebrates, gene expression lacks phylogenetic pattern among fishes and appears to conform more closely with phenotypic expression related to physiological and ecological influences of overall body size and environmental oxygen availability.
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Ontogenetic patterns in the percent dry weight (%DW) and energy density (joules per gram of wet weight) were studied in the early life stages of the subtropical estuarine and marine gray snapper Lutjanus griseus and the warmtemperate estuarine and marine spotted seatrout Cynoscion nebulosus. The %DW was variable for individuals of both species but increased significantly through larval to juvenile stages (<20% for fish ,50 mm standard length to 20–30% for fish >50 mm). The lipid percentage, which was determined only for gray snapper, was also variable between individuals but showed significant increase with body size. Strong relationships between percent dry weight and energy density were evident for both species; however, the slopes of regressions were significantly lower than in general multispecies models, demonstrating the need for species- and stagespecific energy density data in bioenergetics models.