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Michael B Thompson - One of the best experts on this subject based on the ideXlab platform.
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changes to the uterine epithelium during the reproductive cycle of two Viviparous Lizard species niveoscincus spp
Acta Zoologica, 2015Co-Authors: Qiong Wu, Michael B Thompson, Cameron K Fong, Christopher R MurphyAbstract:We investigated morphological differences in uterine epithelia of the reproductive cycle between two closely related Viviparous skinks, Niveoscincus metallicus (lecithotrophic) and Niveoscincus ocellatus (placentotrophic), which have similar placental complexity but different degrees of placentotrophy. Scanning (SEM) and transmission electron microscopy (TEM) revealed that the uterine surface of non-reproductive females of both species is mainly covered by ciliated cells. As vitellogenesis begins, the uterine epithelium consists of ciliated and non-ciliated cells under a thin glycocalyx. Microvilli are greatly reduced at mid-pregnancy, and the uterus differentiates into two structurally distinct regions: the chorioallantoic and the omphaloplacenta. At late stages of pregnancy, the uterine epithelium of chorioallantoic placenta in both species is further ridged, forming a knobbly uterine surface. The ultrastructural evidence between N. metallicus and N. ocellatus cannot strictly account for the distinct differences in their placentotrophy; as yet unexplored molecular nutrient transport mechanisms that are not reflected in uterine ultrastructure must play significant roles in nutrient transportation. Characteristics consistent with a plasma membrane transformation were confirmed in both species.
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tyrosine phosphorylated proteins in the reproductive tract of the Viviparous Lizard eulamprus tympanum and the oviparous Lizard lampropholis guichenoti
Comparative Biochemistry and Physiology B, 2006Co-Authors: Murray Thomson, Jacquie F Herbert, Michael B ThompsonAbstract:Plastic changes occur in the morphology of the uterus at various stages of the reproductive cycle in both oviparous and Viviparous Lizards and these may be influenced by estrogen. Estrogen driven phosphorylation of effector proteins on tyrosine residues plays a major role in the plastic modulation of uterine anatomy and physiology in vertebrates. We used electrophoresis and Western blotting to characterize the phosphotyrosine protein profiles at various stages of the reproductive pathway in an oviparous Lizard Lampropholis guichenoti and a Viviparous Lizard Eulamprus tympanum. L. guichenoti displayed major bands in the 200-35 kDa range and a triplet of bands of molecular masses 61 kDa, 52 kDa and 48 kDa in 50% of specimens and a 38 kDa band in all specimens. In contrast, E. tympanum samples all displayed a single major band at 40 kDa, which was significantly elevated at the early pregnancy stage. Somewhat paradoxically, the Viviparous species, which has the more complex uterine epithelial changes during pregnancy, has the fewest phosphotyrosine bands, so how tyrosine phosphorylation is affected during the evolution of viviparity is not clear.
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thermal biology of a Viviparous Lizard with temperature dependant sex determination
Journal of Thermal Biology, 2006Co-Authors: Kylie A Robert, Michael B Thompson, Frank SeebacherAbstract:Abstract 1. Eulamprus tytmpanum can attain mean selected temperatures achieved in the laboratory under field conditions, but the proportion of time at that temperature is restricted under natural conditions. 2. Females actively thermoregulate in the field, although the efficiency of thermoregulation is restricted by environmental constraints. 3. Gravid females in more favourable habitats in the period encompassing the middle third of development (the assumed sex determining period) select higher temperatures, with lower variance and have greater thermoregulatory efficiency than during the rest of pregnancy, thus thermoregulating more precisely during this period.
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hoxa10 like proteins in the reproductive tract of the Viviparous Lizard eulamprus tympanum and the oviparous Lizard lampropholis guichenoti
Comparative Biochemistry and Physiology B, 2005Co-Authors: Murray Thomson, Jacquie F Herbert, Christopher R Murphy, Michael B ThompsonAbstract:Abstract The gene HoxA10 and its protein product are essential for the formation of the extensions of the plasma membrane called uterodomes or pinopods in mammalian uterine epithelia. In mice, the presence of the HoxA10 protein and uterodomes is needed for uterine receptivity to blastocyst implantation. The Viviparous Lizard Eulamprus tympanum displays uterodomes whereas the oviparous Lizard Lampropholis guichenoti does not. To explore the theory that HoxA10 is involved in the formation of uterodomes we investigated whether HoxA10 immunoreactive proteins were present in both species during their reproductive cycles. Oviduct proteins from vitellogenic, gravid or non-reproductive L. guichenoti ( n = 19) and E. tympanum ( n = 28) were separated by electrophoresis and analysed by Western blot and specific antibodies to HoxA10. E. tympanum displayed HoxA10 immunoreactive bands at 59 and 63 kDa in 20 out of the 28 samples. All of the L. guichenoti samples displayed HoxA10 immunoreactive bands, 18 had bands at 59 and 64 kDa and 1 animal had a single band at 59 kDa. There were no significant differences in the level of HoxA10 immunoreactivity between the different stages of reproductive cycle in either species. The different molecular mass of the larger band in L. guichenoti (64 kDa) compared to E. tympanum (63 kDa) indicates that the two Lizards express different isoforms of the HoxA10-like proteins and it will be interesting in future studies to determine whether there are differences in the biological activity of the proteins that regulate different physiological functions in the uterus of Viviparous and oviparous Lizards.
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cyto epitheliochorial placenta of the Viviparous Lizard pseudemoia entrecasteauxii a new placental morphotype
Journal of Morphology, 2005Co-Authors: Susan M Adams, Michael B Thompson, Joanna M Biazik, Christopher R MurphyAbstract:The structural features of the uterine epithelium of the chorioallantoic placenta and omphalloplacenta in the Viviparous Australian skink, Pseudemoia entrecasteauxii, were investigated using SEM and TEM techniques. In particular, the structural characteristics that would allow interpretation of function were analyzed, particularly those of gas exchange in the chorioallantoic placenta and histotrophy in the omphaloplacenta. Pseudemoia entrecasteauxii has a complex placenta consisting of a placentome, paraplacentome, and omphaloplacenta. The paraplacentome has a well-vascularized lamina propria in which projecting uterine capillaries displace the overlying uterine epithelial cells, reducing them to attenuated cytoplasmic extensions. Associated cell nuclei and organelles are lost from this region, to provide a capillary lumen to uterine lumen barrier of 0.5–1.0 μm. Hence, the paraplacentome is likely a prominent site for gaseous exchange via simple diffusion. The omphaloplacenta has a similar cytology to that of the placentome, but the uterine epithelial cells are hypertrophied and the apical plasma membrane actively secretes vesicles into the uterine lumen. The omphaloplacenta shows features that are associated with histotrophic transport of nutrients via vesicle secretion, very similar to that of lipid apocrine secretion. The placentome consists of cuboidal cells in the uterine epithelium, with large centrally located nuclei overlying the well-vascularized lamina propria. Although the placentome has a similar cytological structure to that of the omphaloplacenta, granules or active vesicle secretion were not observed. Thus, the placentome may be associated with histotrophy, but not via apocrine secretion. Squamate placentation is epitheliochorial; however, we propose a new term be used to describe the type of placentation in P. entrecasteauxii: “cyto-epitheliochorial,” because of the extreme attenuation of uterine epithelial cells of the paraplacentome. J. Morphol. © 2005 Wiley-Liss, Inc.
Susan M Jones - One of the best experts on this subject based on the ideXlab platform.
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response to gonadotropin releasing hormone challenge seasonal variation in steroid production in a Viviparous Lizard tiliqua nigrolutea
General and Comparative Endocrinology, 2017Co-Authors: A Edwards, Susan M JonesAbstract:The hypothalamic–pituitary–gonadal axis plays a central role in the regulation of gamete maturation, sex steroid production and the stimulation of reproductive behaviours in vertebrates. In seasonal breeders, the timely activation and deactivation of this control system is important to ensure successful reproduction: this process is not well understood in species which breed irregularly. Males of the Viviparous blotched blue-tongued Lizard, Tiliqua nigrolutea, breed annually, while females display a multiennial cycle. We investigated seasonal variation in hypothalamic–pituitary–gonadal axis responsiveness in both sexes of T. nigrolutea. We measured changes in plasma concentrations of testosterone and estrogen in response to a single intraperitoneal injection of a GnRH agonist, chicken-II LH–RH, at three reproductively distinct times of year. Plasma testosterone concentrations in males were significantly increased during gonadal quiescence, but not initial or final spermatogenesis. There was no estrogen response in males at any time of year. Conversely, in females, there was an increase in plasma testosterone, but not estrogen, concentration, in reproductively quiescent females several months in advance of a successful pregnancy. These results indicate clear variation in HPG axis activity with sex, season and reproductive condition in this seasonally breeding Viviparous Lizard. This study opens the way for further investigation into the mechanisms by which internal (body condition) and external seasonal cues (temperature and photoperiod) are coordinated to regulate reproduction in irregularly-breeding reptiles.
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placental and embryonic tissues exhibit aromatase activity in the Viviparous Lizard niveoscincus metallicus
General and Comparative Endocrinology, 2014Co-Authors: Laura M Parsley, E Wapstra, Susan M JonesAbstract:Aromatase is a key regulator of circulating testosterone (T) and 17-β-oestradiol (E2), two steroids which are critical to the development, maintenance and function of reproductive tissues. The role of aromatase in sexual differentiation in oviparous (egg-laying) reptiles is well understood, yet has never been explored in Viviparous (live-bearing) reptiles. As a first step towards understanding the functions of aromatase during gestation in Viviparous reptiles, we measured aromatase activity in maternal and embryonic tissues at three stages of gestation in the Viviparous skink, Niveoscincus metallicus. Maternal ovaries and adrenals maintained high aromatase activity throughout gestation. During the early phases of embryonic development, placental aromatase activity was comparable to that in maternal ovaries, but declined significantly at progressive stages of gestation. Aromatase activity in the developing brains and gonads of embryos was comparable with measurements in oviparous reptiles. Aromatase activity in the developing brains peaked mid development, and declined to low levels in late stage embryos. Aromatase activity in the embryonic gonads was low at embryonic stage 29–34, but increased significantly at mid-development and then remained high in late stage embryos. We conclude that ovarian estrogen synthesis is supplemented by placental aromatase activity and that maternal adrenals provide an auxiliary source of sex steroid. The pattern of change in aromatase activity in embryonic brains and gonads suggests that brain aromatase is important during sexual differentiation, and that embryonic gonads are increasingly steroidogenic as development progresses. Our data indicate vital roles of aromatase in gestation and development in Viviparous Lizards.
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In utero exposure to the oestrogen mimic diethylstilbestrol disrupts gonadal development in a Viviparous reptile.
Reproduction Fertility and Development, 2014Co-Authors: Laura M Parsley, Erik Wapstra, Susan M JonesAbstract:The ubiquitous presence of endocrine-disrupting chemicals (EDCs) in the environment is of major concern. Studies on oviparous reptiles have significantly advanced knowledge in this field; however, 30% of reptilian species are Viviparous (live-bearing), a parity mode in which both yolk and a placenta support embryonic development, thus exposure to EDCs may occur via multiple routes. In this first study of endocrine disruption in a Viviparous Lizard (Niveoscincus metallicus), we aimed to identify effects of the oestrogen mimic diethylstilbestrol (DES) on gonadal development. At the initiation of sexual differentiation, pregnant N. metallicus were treated with a single dose of DES at 100 or 10 µg kg–1, a vehicle solvent or received no treatment. There was no dose-response effect, but the testes of male neonates born to DES-exposed mothers showed reduced organisation of seminiferous tubules and a lack of germ cells compared with those from control groups. The ovaries of female neonates born to DES-exposed mothers exhibited phenotypic abnormalities of ovarian structure, oocytes and follicles compared with controls. The results indicate that, in Viviparous Lizards, maternal exposure to oestrogenic EDCs during gestation may have profound consequences for offspring reproductive fitness.
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interpopulational variation in costs of reproduction related to pregnancy in a Viviparous Lizard
Ethology Ecology & Evolution, 2012Co-Authors: Keisuke Itonaga, E Wapstra, A Edwards, Susan M JonesAbstract:Interpopulational variation in reproductive costs may affect variation in life history traits including reproductive investment (i.e. clutch mass relative to either maternal body mass or length). While the relationships between reproductive investment and costs of reproduction, especially costs to mobility, have been well studied in squamate reptiles, how these costs relate to investment and explain patterns within and between populations is not always straightforward. In the present study, we examined the relationship between reproductive investment and costs of reproduction (gravid and postpartum sprint speeds and maternal postpartum body condition) in two populations of a Viviparous skink, Pseudemoia entrecasteauxii living in different habitat types. We found that costs of reproduction (i.e. impact on gravid and postpartum sprint speeds) depended on the interaction between relative reproductive burden (RRB) and population. There was no link between relative clutch mass (RCM) and maternal sprint speeds. Maternal postpartum body condition was not related to either RRB or RCM for either population. Gravid females living in the open habitat population showed significantly slower sprint speed compared with the same females immediately postparturition, and other gravid females living in a closed habitat population. Such females are likely to experience a higher cost of reproduction in terms of changes in sprint speed as well as exposure to predators and may show a behavioural shift to crypsis in order to compensate for locomotor impairment and to reduce the risk of predation. We suggest that factors which relate to costs of reproduction (i.e. sprint speeds) are complex and may involve multiple factors such as reproductive investment and habitat characteristics.
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effects of maternal basking and food quantity during gestation provide evidence for the selective advantage of matrotrophy in a Viviparous Lizard
PLOS ONE, 2012Co-Authors: Keisuke Itonaga, Susan M Jones, E WapstraAbstract:The evolution of matrotrophy (i.e., direct supply of nutrients by the mother during gestation) may be associated with high maternal energy availability during gestation. However, we lack knowledge about the selective advantages of matrotrophic viviparity (live-bearing) in reptiles. In reptiles, the interaction between body temperature and food intake affect maternal net energy gain. In the present study, we examined the effects of basking and food availability (2 by 2 factorial design) during gestation on offspring phenotype in a matrotrophic Viviparous Lizard (Pseudemoia entrecasteauxii). Subsequently, we investigated if the maternal effects were context-dependent using offspring growth rate as an indicator of the adaptive significance of matrotrophy. Offspring were exposed either to the same thermal conditions as their mothers experienced or to thermal conditions different from those experienced by their mothers. We provide the first evidence that an interaction between maternal thermal and maternal food conditions during gestation strongly affects offspring phenotype, including date of birth, body size and performance ability, which affect offspring fitness. Offspring growth rate was dependent on offspring thermal conditions, but was not influenced by maternal effects or offspring sex. Matrotrophic viviparity provided gravid females with the means to enhance offspring fitness through greater energetic input to offspring when conditions allowed it (i.e., extended basking opportunity with high food availability). Therefore, we suggest that selective advantages of matrotrophic viviparity in P. entrecasteauxii may be associated with high maternal energy availability during gestation.
Louis J. Guillette - One of the best experts on this subject based on the ideXlab platform.
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interembryonic regions of the uterus of the Viviparous Lizard mabuya brachypoda squamata scincidae
Journal of Morphology, 2006Co-Authors: Mari Carmen Uribearanzabal, Arlette Hernandezfranyutti, Louis J. GuilletteAbstract:Analysis of the structure and physiology of the uterine incubation chambers of Viviparous squamates has provided insight concerning adaptations for gestation. However, the literature addressing the biology of the interembryonic regions of the uterus is very limited, presumably because it has been assumed that this area has little role in the development and support of embryos in Viviparous squamates. This study was undertaken to examine the histology of the interembryonic regions of Mabuya brachypoda, a Viviparous Lizard with microlecithal ova and consequently substantial matrotrophic activity. The incubation chambers are oval, distended zones of the uterus, adjacent to the interembryonic regions. The wall of the interembryonic regions includes: mucosa, formed by a cubodal or columnar epithelium with ciliated and nonciliated cells, and a lamina propria of vascularized connective tissue containing abundant acinar glands; myometrial smooth muscle consisting of inner circular and outer longitudinal layers; and serosa. The segment of the interembryonic region adjacent to the incubation chamber forms a transitional segment that displays folds of the mucosa that protrude into the uterine lumen. The limit of the incubation chamber is well defined by the long mucosal folds of the transitional segment. Long and thin extensions of extraembryonic membranes are present in the lumen of the transitional segment, outside of the incubation chamber region. The presence of abundant uterine glands and extraembryonic membranes in the interembryonic regions during gestation suggests uterine secretory activity and histotrophic transfer of nutrients to embryos in these regions. J. Morphol. © 2006 Wiley-Liss, Inc.
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seasonal variation in ovarian histology of the Viviparous Lizard sceloporus torquatus torquatus
Journal of Morphology, 1995Co-Authors: Maria Del Carmen A Uribe, Maria Elodia Mendez Omana, Josee Gonzalez Quintero, Louis J. GuilletteAbstract:Changes in ovarian histology during the reproductive cycle of the Viviparous Lizard Sceloporus torquatus torquatus are described. In general, the variation in follicular histology observed during the seasonal cycle is similar to that of other Lizards. Sceloporus t. torquatus exhibits a cycle in which small, previtellogenic follicles exist in the ovary from December to August. Vitellogenesis occurs between September and November, followed by ovulation from late November to early December. Parturition occurs the following spring. After ovulation, the remaining follicular cells form the corpus luteum and luteolysis did not occur until April-May. Follicular atresia is commonly observed in previtellogenic follicles with polymorphic granulosa, but occurs less frequently in follicles during late vitellogenesis. There are two germinal beds in each ovary. The yolk nucleus is evident in young oocytes as is a vacuolated ooplasma prior to vitellogenesis. Extensive polymorphism is observed in yolk platelets. Mast cells and secretory cells are observed in the thecal layer of the follicular wall as are melanocytes in the ovarian stroma. © 1995 Wiley-Liss, Inc.
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differential atresia of ovarian follicles and its effect on the clutch size of two populations of the Viviparous Lizard sceloporus mucronatus
Functional Ecology, 1993Co-Authors: F Mendezde R La Cruz, Louis J. Guillette, Villagransanta M CruzAbstract:The phenomenon of follicular atresia, defined as the death of ovarian follicles prior to ovulation, has seldom been noted in the ecological literature as a major factor in the proximate control of clutch size, but it has been demonstrated that it influences clutch size in many Lizard species. Follicular atresia was examined by analysing the difference between the number of vitellogenic follicles recruited at the onset of reproductive activity and the number of in utero embryos in females of the Viviparous Lizard Sceloporus mucronatus; with female body size factored out, the number of vitellogenic follicles recruited from the germinal beds was not different between populations whereas clutch size was significantly different between the populations
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physiological cost of pregnancy in a Viviparous Lizard sceloporus jarrovi
Journal of Experimental Zoology, 1992Co-Authors: Vincent G Demarco, Louis J. GuilletteAbstract:The Vo2 (standard metabolic rate; cc · h−1) of pregnant Sceloporus jarrovi increases to a maximum near term. Immediately following parturition, Vo2 decreases sharply. Approximately 93.6% of the Vo2 of late pregnant S. jarrovi is due to litter and non-reproductive female Vo2. The difference between measures of the Vo2 of late pregnant Lizards and late pregnant Vo2 estimated by summing litter and nonreproductive Vo2 (6.4%) represents the physiological cost of maintaining a litter. This estimate of the physiological cost of pregnancy in S. jarrovi is similar to that reported for mammals; however, it is lower than other estimates of the cost of pregnancy in reptiles. Estimates of litter metabolism were obtained by measuring maximum embryo metabolism, using an in vitro technique and multiplying embryo Vo2 by litter size. These results suggest that others have overestimated the physiological cost of pregnancy in reptiles because maximum litter Vo2 has been underestimated. Others have suggested that viviparity is an expensive mode of reproduction because the physiological cost of supporting a litter is an important component of an individual's reproductive effort. Data presented here support the alternative hypotheses that the cost of supporting a litter is not high and constitutes a small fraction of the energy apportioned into reproduction. © 1992 Wiley-Liss, Inc.
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effects of arachidonic acid prostaglandin f2α prostaglandin e2 and arginine vasotocin on induction of birth in vivo and in vitro in a Viviparous Lizard sceloporus jarrovi
General and Comparative Endocrinology, 1992Co-Authors: Louis J. Guillette, Vincent G Demarco, Brent D Palmer, Greg R MassonAbstract:Abstract The ability of arachidonic acid (AA) and prostaglandins of the two series to induce parturition in vivo and oviducal contraction in vitro was studied in the Viviparous Lizard Sceloporus jarrovi . Injection of PGF 2α , PGE 2 , or AA during late pregnancy stimulated parturition within 2 hr in a threshold-dependent fashion. In contrast, during mid pregnancy, females did not respond. Surgically removed and cultured oviducts from females in late pregnancy gave “birth” in response to AA, PGF 2α , and PGE 2 . Oviducts from S. jarrovi in mid pregnancy responded to PGF 2α but not to AA. Addition of arginine vasotocin, a potent stimulator of PG synthesis, either alone or with AA to oviduct cultures stimulated rapid and complete birth in vitro from oviducts obtained from late, but not mid pregnant, females. Stage of pregnancy mediates the response of the Lizard oviduct to prostaglandin stimulation.
S D Bradshaw - One of the best experts on this subject based on the ideXlab platform.
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in vitro uterine contractions in the Viviparous Lizard tiliqua rugosa effects of gestation and steroid pretreatment in vivo
General and Comparative Endocrinology, 1992Co-Authors: B Fergusson, S D BradshawAbstract:Uterine contractility was investigated in the Viviparous Lizard Tiliqua rugosa. Arginine vasotocin (AVT) induces rhythmic contractions in vitro in strips of uterine tissue from ovariectomized female T. rugosa. The strength of these contractions was related to the dosage of AVT and reduced by pretreatment in vivo with both progesterone and estradiol-17β. The frequency of spontaneous and AVT-induced contractions was enhanced by estradiol-17β pretreatment. The strength of AVT-induced contractions in pregnant females was not significantly different from that recorded in nonpregnant females. Spontaneous rhythmic contractions were present only in pregnant females. Ovariectomy did not affect either spontaneous or AVT-induced contractions in pregnant females. The data indicate that ovarian steroids modulate uterine contractility in T. rugosa. It is suggested that, following a decline in plasma progesterone levels, estrogen may be involved in the onset of parturition.
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plasma arginine vasotocin progesterone and luteal development during pregnancy in the Viviparous Lizard tiliqua rugosa
General and Comparative Endocrinology, 1991Co-Authors: B Fergusson, S D BradshawAbstract:Abstract The relationship between plasma levels of arginine vasotocin (AVT), progesterone, and corpus luteum formation and degeneration was studied in the Viviparous Lizard Tiliqua rugosa . Hormone levels were monitored in free-ranging, pregnant females which were located for sampling by means of attached radio transmitters. There was an increase in plasma AVT levels in the 30 days immediately prior to parturition. Concurrent with this event was a decline in plasma progesterone levels from relatively high levels in mid-term to basal levels prior to parturition. This is associated with degenerative changes in the corpus luteum which include pyknosis of the nuclei of the cells of the cell mass and increasing prevalence of intercellular spaces, while the thecal layer became increasingly compacted. Ovariectomy experiments indicate that the major source of progesterone during pregnancy in T. rugosa is ovarian.
Brian K Speake - One of the best experts on this subject based on the ideXlab platform.
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evidence for placental transfer of lipids during gestation in the Viviparous Lizard pseudemoia entrecasteauxii
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2004Co-Authors: Brian K Speake, Jacquie F Herbert, Michael B ThompsonAbstract:Abstract During gestation in the Viviparous Lizard Pseudemoia entrecasteauxii , the fetus obtains nutrients from two sources: uptake of yolk components from the retained egg (lecithotrophy) and transfer of nutrients from the maternal circulation via the placenta (placentotrophy). Although net placentotrophy in this species is indicated by the observation that the neonate contains 1.7 times more dry matter than the egg, the placental transfer of lipid has not been previously demonstrated. Lipid analysis was performed on newly ovulated eggs and on neonates. The weight of total lipid per neonate (8.2±0.5 mg) is significantly ( P =0.049) greater than that in the egg (6.8±0.4 mg), indicating that the placenta must contribute some lipid to the fetus. On the assumption that 50% of the lipid delivered to the fetus from either source is oxidized for energy, it is calculated that the placenta accounts for 58.5% of the fetal lipid requirements, with the remaining 41.5% being derived from the egg. The fatty acid compositions of the triacylglycerol and phospholipid recovered in the neonatal tissue differ substantially from those of the egg. In particular, the proportions of 18:2 n −6 and 18:3 n −3 are far lower in the neonatal lipids compared with the egg lipids. On the other hand, the proportion of 22:6 n −3 in the phospholipid of the neonate is six times higher than in the phospholipid of the egg. The absolute amount (mg) of 22:6 n −3 recovered in the total lipid of the neonate is 3.8 times greater than the amount initially present in the egg. By comparison, the amount of total fatty acid in neonatal lipid is 1.2 times greater than the amount in the egg. Thus, there is a preferential use of 22:6 n −3 for tissue phospholipid synthesis during development. We conclude that there is net transfer of fatty acids across the placenta to the fetus of P. entrecasteauxii and a high degree of selectivity in the use of the various fatty acids for fetal tissue lipid synthesis.
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nutrient uptake by embryos of the australian Viviparous Lizard eulamprus tympanum
Physiological and Biochemical Zoology, 2001Co-Authors: Michael B Thompson, Brian K Speake, Kylie J Russell, Ruth J MccartneyAbstract:Abstract Eulamprus tympanum is a high‐altitude Viviparous Lizard that was probably used to help define a Type I chorioallantoic placenta. In this article, we (1) describe the net transport of nutrients across the placenta of E. tympanum, and (2) compare placental uptake in E. tympanum with a previous study of Eulamprus quoyii, which occurs in warmer environments, to assess the potential importance of thermal regime on placentotrophy. Freshly ovulated eggs are \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $387.3\pm 19.7$ \end{do...
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placental nutrition in the Viviparous Lizard niveoscincus metallicus the influence of placental type
The Journal of Experimental Biology, 1999Co-Authors: M B Thompson, Brian K Speake, Ruth J Mccartney, J R Stewart, K J Russell, P F SuraiAbstract:The ion, energy, lipid, nitrogen and fat-soluble vitamin contents of freshly ovulated eggs and neonates of the Viviparous Lizard Niveoscincus metallicus were measured to quantify uptake of nutrients across the placenta. This species is particularly interesting because it has a chorio-allantoic placenta that is intermediate in complexity compared to Viviparous species that have been the focus of other studies. Newly ovulated eggs have a wet mass of 79.6+/−4.6 mg and a dry mass of 41.8+/−2.8 mg, compared to the neonates that have a wet mass of 224.2+/−8.2 mg and dry mass of 37.9+/−1.2 mg. Thus, there is no significant net uptake of dry matter across the placenta. Neonates have significantly less lipid (6.2+/−0.4 mg) than eggs (12.7+/−0.5 mg), but no significant difference in nitrogen (4.1+/−0.3 mg) compared to eggs (4.5+/−0.2 mg). Energy densities reflect the protein and lipid composition and the relative dry masses of the eggs and neonates. There is significantly more energy (1029.1+/−80.0 J) in the egg than in the neonate (858.2+/−38.6 J). The increase in the ash content of the neonates (2.9+/−0.2 mg) compared to fresh eggs (2.1+/−0.3 mg) was not significant, even though there was an approximately threefold increase in the amount of sodium (0.11+/−0.01 mg in neonates, 0.34+/−0.01 mg in eggs) and potassium (0.12+/−0.017 in neonates, 0.40+/−0.01 mg in eggs) in neonates compared to eggs. There was no significant uptake of calcium and magnesium during development. The egg lipids consisted of triacylglycerol (66.7+/−2.3 %), phospholipid (18.9+/−0.7 %), cholesteryl ester (4.9+/−1.6 %) and free cholesterol (5.6+/−1.5 %). The egg phospholipid contained comparatively high proportions of arachidonic and eicosapentanoic acids but low levels of docosahexaenoic acid (DHA), whereas the phospholipid of the neonate was greatly enriched in DHA. In the egg, the predominant vitamin E was (α)-tocopherol (62.6+/−3.4 mg g(−)(1)), although there was some (γ)-tocotrienol (3.5+/−0.3 mg g(−)(1)), and vitamin A was present (1.5+/−0.2 mg g(−)(1)). The ratio of neonate dry mass to egg dry mass of N. metallicus (0.91) lies between that of species with type I (0.78) and type III (1.70) chorio-allantoic placentae, confirming our conclusion that the placenta of N. metallicus is functionally intermediate, as well as intermediate in complexity, between these other two types.
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placental transfer of nutrients during gestation in the Viviparous Lizard pseudemoia spenceri
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 1999Co-Authors: Michael B Thompson, Brian K Speake, Kylie J Russell, James R Stewart, Ruth J MccartneyAbstract:Energy, ionic, protein and lipid contents and fatty acid profiles for the major lipid classes of freshly ovulated eggs and neonates of the Viviparous Lizard, Pseudemoia spenceri, were measured. Litter size is 1.7 ± 0.1, with larger females producing larger neonates. Placentotrophy results in approximately 23% more dry matter in the neonates than in the fresh egg. The increase in the quantity of protein and lipid during development is not significant and is reflected in the similarity of energy densities of eggs and neonates. As a percentage of dry matter, neonates have slightly lower proportions of lipid and protein than eggs because of significant uptake of ash, calcium, potassium and sodium, but not of magnesium, across the placenta. The amounts of triacylglycerol and phospholipid are not significantly different between the egg and the neonate, but neonates contain significantly more cholesterol and cholesteryl ester. The amounts of the major fatty acids, palmitic and oleic acids, recovered from the total lipids of the neonate do not differ significantly from the amounts present in the egg lipids, but the neonates contain significantly less linoleic and α-linolenic acids and more palmitoleic, stearic and arachidonic acids than the eggs. The amount of docosahexaenoic acid recovered from the lipids of the neonate is 2.6-times greater than the amount initially present in the egg. P. spenceri has a relatively larger egg and a smaller reliance on placentotrophy than other species in the same genus, all of which have a similar placental morphology. Nevertheless, the pattern of embryonic nutrition includes both obligative and facultative placentotrophy. All the major components of yolk of oviparous species are present in eggs of P. spenceri, but most are augmented during development by placental transfer.
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placental nutrition in a Viviparous Lizard pseudemoia pagenstecheri with a complex placenta
Journal of Zoology, 1999Co-Authors: Michael B Thompson, Brian K Speake, Kylie J Russell, Ruth J Mccartney, James R Stewart, P F SuraiAbstract:The composition of egg yolks and neonates of the Viviparous Lizard, Pseudemoia pagenstecheri, one of the most placentotrophic reptiles studied to date, are described. Neonates (43.3 ± 5.2 mg) have twice the dry mass of the initial eggs (22.0 ± 1.9 mg). The protein content of neonates (29.1 ± 1.1 mg) is more than twice that of eggs (12.2 ± 1.1 mg), while the energy content (908.1 ± 107.4 J) is 1.6 times higher than that of the egg (565.0 ± 42.9 J). The energy densities of eggs (27.5 kJ g−1) and neonates (23.1 ± 0.3 kJ g−1) are similar to the energy densities of eggs and neonates of oviparous species. The total ash per neonate (4.1 ± 0.4 mg) is three times greater than that of the egg contents (1.4 ± 0.2). Neonates contain significantly more calcium, sodium and potassium, but not magnesium, than do eggs. Thus, the placenta has a quantitatively important role in supplying nutrients for the embryo. The proportions of triacylglycerol (66%), phospholipid (19%), and free cholesterol (5%) in the eggs are similar to those in eggs of birds and crocodilians, but the proportion of cholesteryl esters (7%) is much higher in eggs of P. pagenstecheri. The proportion of docosahexaenoic acid in the egg phospholipid is relatively low (1.4%) but rises to 5.4% in the neonate. The eggs contain vitamin E (mainly in the form of α-tocopherol) and vitamin A, but no detectable carotenoids. The overall composition of the eggs is not substantially different from that of oviparous species, suggesting that the small egg size relative to neonate size is a result of a reduction in egg size rather than modification by omission of some nutrients from the yolk. The pattern of placental nutrient provision of P. pagenstecheri contains both an obligate and a facultative component suggesting that enhancement of offspring quality through facultative placentotrophy is a general characteristic of placental reptiles independent of pattern of embryonic nutrient provision.
