Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 343
Filtrar
1.
J Exp Zool B Mol Dev Evol ; 336(6): 457-469, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34254734

RESUMO

Research focused on understanding the evolutionary factors that shape parity mode evolution among vertebrates have long focused on squamate reptiles (snakes and lizards), which contain all but one of the evolutionary transitions from oviparity to viviparity among extant amniotes. While most hypotheses have focused on the role of cool temperatures in favoring viviparity in thermoregulating snakes and lizards, there is a growing appreciation in the biogeographic literature for the importance of lower oxygen concentrations at high elevations for the evolution of parity mode. However, the physiological mechanisms underlying how hypoxia might reduce fitness, and how viviparity can alleviate this fitness decrement, has not been systematically evaluated. We qualitatively evaluated previous research on reproductive and developmental physiology, and found that (1) hypoxia can negatively affect fitness of squamate embryos, (2) oxygen availability in the circulatory system of adult lizards can be similar or greater than an egg, and (3) gravid females can possess adaptive phenotypic plasticity in response to hypoxia. These findings suggest that the impact of hypoxia on the development and physiology of oviparous and viviparous squamates would be a fruitful area of research for understanding the evolution of viviparity. To that end, we propose an integrative research program for studying hypoxia and the evolution of viviparity in squamates.


Assuntos
Altitude , Oxigênio , Répteis/fisiologia , Viviparidade não Mamífera/fisiologia , Animais , Evolução Biológica , Feminino , Répteis/embriologia
2.
J Exp Biol ; 224(13)2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-34170318

RESUMO

Nutrient transfer from mother to embryo is essential for reproduction in viviparous animals. In the viviparous teleost Xenotoca eiseni (family Goodeidae), the intraovarian embryo intakes the maternal component secreted into the ovarian fluid via the trophotaenia. Our previous study reported that the epithelial layer cells of the trophotaenia incorporate a maternal protein via vesicle trafficking. However, the molecules responsible for the absorption were still elusive. Here, we focused on Cubam (Cubilin-Amnionless) as a receptor involved in the absorption, and cathepsin L as a functional protease in the vesicles. Our results indicated that the Cubam receptor is distributed in the apical surface of the trophotaenia epithelium and then is taken into the intracellular vesicles. The trophotaenia possesses acidic organelles in epithelial layer cells and cathepsin L-dependent proteolysis activity. This evidence does not conflict with our hypothesis that receptor-mediated endocytosis and proteolysis play roles in maternal macromolecule absorption via the trophotaenia in viviparous teleosts. Such nutrient absorption involving endocytosis is not a specific trait in viviparous fish. Similar processes have been reported in the larval stage of oviparous fish or the suckling stage of viviparous mammals. Our findings suggest that the viviparous teleost acquired trophotaenia-based viviparity from a modification of the intestinal absorption system common in vertebrates. This is a fundamental study to understand the strategic variation of the reproductive system in vertebrates.


Assuntos
Ciprinodontiformes , Viviparidade não Mamífera , Animais , Endocitose , Feminino , Ovário , Oviparidade
3.
Mol Biol Evol ; 38(6): 2627-2638, 2021 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-33620468

RESUMO

The evolutionary origin of complex organs challenges empirical study because most organs evolved hundreds of millions of years ago. The placenta of live-bearing fish in the family Poeciliidae represents a unique opportunity to study the evolutionary origin of complex organs, because in this family a placenta evolved at least nine times independently. It is currently unknown whether this repeated evolution is accompanied by similar, repeated, genomic changes in placental species. Here, we compare whole genomes of 26 poeciliid species representing six out of nine independent origins of placentation. Evolutionary rate analysis revealed that the evolution of the placenta coincides with convergent shifts in the evolutionary rate of 78 protein-coding genes, mainly observed in transporter- and vesicle-located genes. Furthermore, differences in sequence conservation showed that placental evolution coincided with similar changes in 76 noncoding regulatory elements, occurring primarily around genes that regulate development. The unexpected high occurrence of GATA simple repeats in the regulatory elements suggests an important function for GATA repeats in developmental gene regulation. The distinction in molecular evolution observed, with protein-coding parallel changes more often found in metabolic and structural pathways, compared with regulatory change more frequently found in developmental pathways, offers a compelling model for complex trait evolution in general: changing the regulation of otherwise highly conserved developmental genes may allow for the evolution of complex traits.


Assuntos
Evolução Biológica , Genoma , Placenta , Poecilia/genética , Viviparidade não Mamífera/genética , Substituição de Aminoácidos , Animais , Feminino , Gravidez , Seleção Genética
4.
J Exp Biol ; 224(Pt 6)2021 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-33568441

RESUMO

An exceptional case of parallel evolution between lizards and eutherian mammals occurs in the evolution of viviparity. In the lizard genus Mabuya, viviparity provided the environment for the evolution of yolk-reduced eggs and obligate placentotrophy. One major event that favored the evolution of placentation was the reduction of the eggshell. As with all oviparous reptiles, lizard embryos obtain calcium from both the eggshell and egg yolk. Therefore, the loss of the eggshell likely imposes a constraint for the conservation of the egg yolk, which can only be obviated by the evolution of alternative mechanisms for the transport of calcium directly from the mother. The molecular and cellular mechanisms employed to solve these constraints, in a lizard with only a rudimentary eggshell such as Mabuya, are poorly understood. Here, we used RT-qPCR on placental and uterine samples during different stages of gestation in Mabuya, and demonstrate that transcripts of the calcium transporters trpv6, cabp28k, cabp9k and pmca are expressed and gradually increase in abundance through pregnancy stages, reaching their maximum expression when bone mineralization occurs. Furthermore, CABP28K/9K proteins were studied by immunofluorescence, demonstrating expression in specific regions of the mature placenta. Our results indicate that the machinery for calcium transportation in the Mabuya placenta was co-opted from other tissues elsewhere in the vertebrate bodyplan. Thus, the calcium transportation machinery in the placenta of Mabuya evolved in parallel with the mammalian placenta by redeploying the expression of similar calcium transporter genes.


Assuntos
Lagartos , Animais , Evolução Biológica , Cálcio , Eutérios , Feminino , Lagartos/genética , Placenta , Gravidez , Viviparidade não Mamífera
5.
J Morphol ; 282(4): 533-542, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33486767

RESUMO

During embryogenesis, teleost females do not develop Müllerian ducts, which form the oviducts in all other vertebrates. Thus, when they reach sexual maturity they do not have oviducts. In viviparous teleosts, the lack of oviducts means that the development of the embryos occurs as an intraovarian gestation, unique among vertebrates. The ovary is an unpaired hollow organ whose cavity is continuous with the caudal portion, the gonoduct, characterized by the absence of germinal cells, which opens to the exterior at the gonopore. The gonoduct attains essential function as a barrier between the germinal region of the ovary and the exterior during all reproductive stages. This study describes the functional morphology of the gonoduct in the viviparous teleost Cnesterodon decemmaculatus during non-gestation (previtellogenesis and vitellogenesis) and gestation. The ovaries were processed using histological techniques and stained with hematoxylin-eosin, and periodic acid Schiff. The gonoduct has two regions: cephalic and caudal, and is formed by three histological layers, which are, from inside to the periphery: (a) tunica mucosa; (b) tunica muscularis; and (c) tunica serosa. In the cephalic region there are mucosal folds extending into the lumen and forming a structure similar to a cervix. The histology of the gonoduct indicates essential functions, that is, (a) the control of the luminal diameter in the limit to the germinal region of the ovary by the presence of a cervix; (b) during insemination the gonoduct receives the spermatozoa, may store and transport them to the germinal region; (c) the presence of melano-macrophage centers indicates support of immunological processes, especially during gestation when these centers increase in size; (d) production of exocrine secretions; and (e) it is the birth canal, internally lined by an ciliated epithelium and surrounded by smooth musclesboth tissues supposedly supporting the birth process.


Assuntos
Ciprinodontiformes/anatomia & histologia , Gônadas/anatomia & histologia , Viviparidade não Mamífera , Animais , Desenvolvimento Embrionário , Epitélio/anatomia & histologia , Feminino , Masculino , Melanócitos/citologia , Ovário/anatomia & histologia , Reprodução/fisiologia , Espermatozoides/citologia , Vitelogênese/fisiologia
6.
J Fish Biol ; 98(3): 784-790, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33230841

RESUMO

Nitrogen stable isotopes ratios (δ15 N) were determined for selected tissues (muscle, liver, blood and yolk) of pregnant females and their embryos of a placental viviparous species, the Pacific sharpnose shark (Rhizoprionodon longurio), and a yolk-sac viviparous species, the speckled guitarfish (Pseudobatos glaucostigmus). The R. longurio embryo tissues were 15 N enriched compared to the same tissues in the pregnant female, using the difference in δ15 N (Δδ15 N) between embryo and adult. Mean Δδ15 N was 2.17‰ in muscle, 4.39‰ in liver and 0.80‰ in blood. For P. glaucostigmus, embryo liver tissue was significantly 15 N enriched in comparison with liver of the pregnant female (Δδ15 N mean = 1.22‰), whereas embryo muscle was 15 N depleted relative to the muscle of the pregnant female (Δδ15 N mean = -1.22‰). Both species presented a significant positive linear relationship between Δδ15 N and embryo total length (LT ). The results indicated that embryos have different Δδ15 N depending on their reproductive strategy, tissue type analysed and embryo LT .


Assuntos
Isótopos de Nitrogênio/metabolismo , Reprodução/fisiologia , Tubarões/fisiologia , Viviparidade não Mamífera/fisiologia , Animais , Feminino , Músculos/metabolismo , Isótopos de Nitrogênio/análise , Tubarões/classificação
7.
Artigo em Inglês | MEDLINE | ID: mdl-33348020

RESUMO

Interactions between the environment and maternal and embryonic physiology can have critical ramifications for early-life phenotypes and survival in a range of species. A major component of the environment-maternal-embryonic nexus is the regulation of embryonic heart rate, which can have important ramifications for developmental phenology, but remains relatively unexplored in viviparous reptiles. The goal of this study was to test for a relationship between embryonic heart rate and maternal body temperature in two species of viviparous garter snakes. The embryonic heart rates of Thamnophis elegans and T. sirtalis were assessed using a field-portable ultrasound. For both T. elegans and T. sirtalis, embryonic heart rate was strongly correlated to maternal temperature. Interestingly, there was also a strong correlation between embryonic and maternal heart rate that was most likely mediated by a common response to maternal body temperature, in spite of the effects of handling during ultrasound on maternal heart rate. Furthermore, embryos at earlier developmental stages had lower heart rates. To our knowledge, this study is the first to explore embryonic heart rate in viviparous reptiles, providing a foundation for future work using ultrasonography to test ecological and evolutionary hypotheses related to developmental dynamics in free-ranging viviparous species.


Assuntos
Colubridae/fisiologia , Frequência Cardíaca Fetal , Viviparidade não Mamífera/fisiologia , Animais , Feminino , Gravidez , Ultrassonografia
8.
Mol Phylogenet Evol ; 158: 107060, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33383174

RESUMO

Most of the present knowledge on animal reproductive mode evolution, and possible factors driving transitions between oviparity and viviparity is based on studies on vertebrates. The species rich door snail (Clausiliidae) subfamily Phaedusinae represents a suitable and unique model for further examining parity evolution, as three different strategies, oviparity, viviparity, and the intermediate mode of embryo-retention, occur in this group. The present study reconstructs the evolution of reproductive strategies in Phaedusinae based on time-calibrated molecular phylogenetics, reproductive mode examinations and ancestral state reconstruction. Our phylogenetic analysis employing multiple mitochondrial and nuclear markers identified a well-supported clade (including the tribes Phaedusini and Serrulinini) that contains species exhibiting various reproductive strategies. This clade evolved from an oviparous most recent common ancestor according to our reconstruction. All non-oviparous taxa are confined to a highly supported subclade, coinciding with the tribe Phaedusini. Both oviparity and viviparity occur frequently in different lineages of this subclade that are not closely related. During Phaedusini diversification, multiple transitions in reproductive strategy must have taken place, which could have been promoted by a high fitness of embryo-retaining species. The evolutionary success of this group might result from the maintenance of various strategies.


Assuntos
Evolução Biológica , Reprodução/genética , Caramujos/fisiologia , Viviparidade não Mamífera , Animais , Feminino , Mitocôndrias/genética , Oviparidade/genética , Filogenia , Caramujos/classificação , Viviparidade não Mamífera/genética
9.
J Exp Biol ; 223(Pt 19)2020 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-33046578

RESUMO

One of the greatest current threats to biodiversity is climate change. However, understanding of organismal responses to fluctuations in temperature and water availability is currently lacking, especially during fundamental life-history stages such as reproduction. To further explore how temperature and water availability impact maternal physiology and reproductive output, we used the viviparous form of the European common lizard (Zootoca vivipara) in a two-by-two factorial design manipulating both hydric and thermal conditions, for the first time. We collected blood samples and morphological measurements during early pregnancy and post-parturition to investigate how water availability, temperature and a combination of the two influence maternal phenology, morphology, physiology and reproductive output. We observed that dehydration during gestation negatively affects maternal physiological condition (lower mass gain, higher tail reserve mobilization) but has little effect on reproductive output. These effects are mainly additive to temperature regimes, with a proportional increase in maternal costs in warmer environments. Our study demonstrates the importance of considering combined effects of water and temperature when investigating organismal responses to climate changes, especially during periods crucial for species survival such as reproduction.


Assuntos
Lagartos , Animais , Reprodução , Temperatura , Viviparidade não Mamífera , Água
10.
J Helminthol ; 94: e198, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32998783

RESUMO

Edible viviparid snails are suspected to be the source of human echinostomiasis in Thailand, but little is known about the prevalence of viviparid snail parasitization by echinostomes in snails sold for human consumption in wet markets. Here, the prevalence of echinostome metacercariae and the association between parasitic intensity and host size, as well as the relationship to host species, were investigated. In total, 1100 viviparid snails belonging to four species (Cipangopaludina annandalei, Filopaludina martensi martensi, F. sumatrensis polygramma and F. doliaris) were obtained from wet markets in Chiang Rai Province, Northern Thailand. All snail species were found to be infected with echinostome metacercariae with total prevalence and mean intensity values of 16.5% and 16.4, respectively. The metacercariae of the avian trematode, Thapariella anastomusa were found in Filopaludina spp. snails. Interestingly, C. annandalei identified in this study had not previously been considered a food source and this is the first report of echinostome metacercaria in this snail species. Results confirmed the role of C. annandalei as the second intermediate host of the trematode; however, the species identity of these echinostomes remains unclear. Comparative morphology of these metacercariae and their adult stage require further study, and molecular markers are necessary to confirm their identification. Prevalence and intensity of echinostomes metacercariae was significantly associated with snail species.


Assuntos
Água Doce/parasitologia , Metacercárias/isolamento & purificação , Caramujos/parasitologia , Trematódeos/isolamento & purificação , Zoonoses/parasitologia , Zoonoses/transmissão , Animais , Feminino , Parasitologia de Alimentos , Humanos , Metacercárias/anatomia & histologia , Tailândia , Trematódeos/classificação , Viviparidade não Mamífera
11.
J Comp Physiol B ; 190(6): 795-809, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32951106

RESUMO

Early developmental environments influence life-history traits and survival of reptiles. In fact, rising global temperatures have already caused widespread extinctions among lizards. Viviparous species might be more susceptible to increasing temperatures because of their inability to meet their energetic demands following rapid environmental changes. Nevertheless, we do not yet fully understand how lizards with different reproductive modes can respond to climate change. We investigated the effect of both maternal thermal environment during pregnancy and incubation temperature on hatchling morphology and physiological performance of two populations of the lizard Saiphos equalis differing in their mode of reproduction, to test whether reproductive mode affects the ability to buffer against rising temperatures. Gravid females from both populations were subjected to current or projected end-of-century (future) thermal environments, to evaluate differences in the body size, growth rate, thermal preference, and locomotor performance of their offspring. Our results show that independently of the mode of reproduction, high temperatures accelerated gestation periods. Thermal environments did not affect hatchling thermal preference, but viviparous hatchlings consistently preferred lower temperatures. Unlike viviparous lizards, oviparous hatchlings incubated under future temperatures were smaller and had a lower growth rate compared to current-incubated hatchlings. Finally, thermal environments did not affect hatchling endurance and speed when controlling for body size. Our results show that global warming is likely to have a negative impact on S. equalis, but suggest that some of its effects may be ameliorated by maternal responses during pregnancy, particularly in viviparous populations.


Assuntos
Lagartos/fisiologia , Temperatura , Animais , Tamanho Corporal , Meio Ambiente , Feminino , Lagartos/crescimento & desenvolvimento , Locomoção , Oviparidade , Reprodução , Viviparidade não Mamífera
12.
Sci Rep ; 10(1): 14744, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32901062

RESUMO

The reduction in fecundity associated with the evolution of viviparity may have far-reaching implications for the ecology, demography, and evolution of populations. The evolution of a polygamous behaviour (e.g. polyandry) may counteract some of the effects underlying a lower fecundity, such as the reduction in genetic diversity. Comparing patterns of multiple paternity between reproductive modes allows us to understand how viviparity accounts for the trade-off between offspring quality and quantity. We analysed genetic patterns of paternity and offspring genetic diversity across 42 families from two modes of viviparity in a reproductive polymorphic species, Salamandra salamandra. This species shows an ancestral (larviparity: large clutches of free aquatic larvae), and a derived reproductive mode (pueriparity: smaller clutches of larger terrestrial juveniles). Our results confirm the existence of multiple paternity in pueriparous salamanders. Furthermore, we show the evolution of pueriparity maintains, and even increases, the occurrence of multiple paternity and the number of sires compared to larviparity, though we did not find a clear effect on genetic diversity. High incidence of multiple paternity in pueriparous populations might arise as a mechanism to avoid fertilization failures and to ensure reproductive success, and thus has important implications in highly isolated populations with small broods.


Assuntos
Evolução Biológica , Paternidade , Reprodução , Urodelos/fisiologia , Viviparidade não Mamífera , Animais , Comportamento Animal , Feminino , Masculino , Repetições de Microssatélites , Comportamento Sexual Animal , Urodelos/genética
13.
Placenta ; 97: 26-28, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32792058

RESUMO

BACKGROUND: The Greenland shark is renowned for its great longevity, yet little is known about its reproduction. METHODS: We supplemented the sparse information on this species by extrapolation from observations on other members of the sleeper shark family and the order Squaliformes. RESULTS AND CONCLUSION: The Greenland shark is viviparous and a single observation suggests a litter size of about ten. The gestation period is unknown, but embryos reach a length of around 40 cm at birth. Nutrition is derived from the yolk sac with minimal histotrophy. The surface area of the uterus is increased by villi that presumably increase in length with advancing gestation. These villi are not likely to be secretory but play a key role in the oxygen supply to the embryo. We argue that the ability of the uterus to supply oxygen is a limiting factor for litter size, which is not likely to exceed the small number reported in this and other sleeper sharks.


Assuntos
Longevidade/fisiologia , Reprodução/fisiologia , Viviparidade não Mamífera/fisiologia , Animais , Feminino , Tamanho da Ninhada de Vivíparos/fisiologia , Tubarões
14.
Genome Biol Evol ; 12(11): 1953-1960, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-32835354

RESUMO

Squamate reptiles exhibit high variation in their phenotypic traits and geographical distributions and are therefore fascinating taxa for evolutionary and ecological research. However, genomic resources are very limited for this group of species, consequently inhibiting research efforts. To address this gap, we assembled a high-quality genome of the common lizard, Zootoca vivipara (Lacertidae), using a combination of high coverage Illumina (shotgun and mate-pair) and PacBio sequencing data, coupled with RNAseq data and genetic linkage map generation. The 1.46-Gb genome assembly has a scaffold N50 of 11.52 Mb with N50 contig size of 220.4 kb and only 2.96% gaps. A BUSCO analysis indicates that 97.7% of the single-copy Tetrapoda orthologs were recovered in the assembly. In total, 19,829 gene models were annotated to the genome using a combination of ab initio and homology-based methods. To improve the chromosome-level assembly, we generated a high-density linkage map from wild-caught families and developed a novel analytical pipeline to accommodate multiple paternity and unknown father genotypes. We successfully anchored and oriented almost 90% of the genome on 19 linkage groups. This annotated and oriented chromosome-level reference genome represents a valuable resource to facilitate evolutionary studies in squamate reptiles.


Assuntos
Cromossomos , Genoma , Lagartos/genética , Processos de Determinação Sexual , Viviparidade não Mamífera/genética , Animais , Feminino , Masculino
15.
Gen Comp Endocrinol ; 295: 113530, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32526330

RESUMO

The neotropical genus Mabuya are obligate placentotrophic viviparous lizards, which have a short vitellogenesis that produces microlecithal oocytes and a prolonged time of gestation (9 to 10 months). The hormonal control of female reproductive activity during follicular growth and pregnancy has not been studied, although it is known that the corpus luteum can produce progesterone, but regresses early in pregnancy, being replaced in this function by the placenta. Through enzyme immunoassay (EIA) we measured the plasma concentrations of estradiol (E2) and progesterone (P4) in females of a population of Mabuya sp at different stages of their reproductive cycle. Previously, we confirmed the presence of P4 in plasma by high-performance liquid chromatography methods with diode-array detector ultraviolet (HPLC-DAD-UV). The average concentration values of E2 and P4 were compared among reproductive stages and their dynamics were related to what is known in other oviparous and viviparous amniotes. The plasma E2 concentrations of Mabuya sp. are below the levels found in other viviparous reptiles, probably related to the substantial reduction of its follicular growth phase. Its highest concentration was detected during vitellogenesis, related to its function in the growth and maturation of the ovarian follicles and oviduct preparation for pregnancy; lower levels were observed during pregnancy, but they increase at the end when a new vitellogenesis event begins and massive placental maternal-fetal nutrient transfer occurs. High concentrations of P4 were found during pregnancy, related to its function in the maintenance of the developing embryos within the oviduct. The highest levels of P4 were found at early gestation, then they descend from mid-gestation to the end of gestation. Although some characteristics of hormonal control related to the high level of placentotrophy were observed in this species, the changes in plasma sex steroid concentrations during the reproductive cycle in females of Mabuya sp. follow patterns seen in other viviparous amniotes.


Assuntos
Estradiol/sangue , Lagartos/sangue , Lagartos/fisiologia , Placenta/metabolismo , Progesterona/sangue , Reprodução/fisiologia , Viviparidade não Mamífera , Animais , Cromatografia Líquida de Alta Pressão , Feminino , Imunoensaio , Gravidez , Reprodutibilidade dos Testes
16.
Mol Biol Evol ; 37(9): 2679-2690, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32421768

RESUMO

Placentation evolved many times independently in vertebrates. Although the core functions of all placentas are similar, we know less about how this similarity extends to the molecular level. Here, we study Poeciliopsis, a unique genus of live-bearing fish that have independently evolved complex placental structures at least three times. The maternal follicle is a key component of these structures. It envelops yolk-rich eggs and is morphologically simple in lecithotrophic species but has elaborate villous structures in matrotrophic species. Through sequencing, the follicle transcriptome of a matrotrophic, Poeciliopsis retropinna, and lecithotrophic, P. turrubarensis, species we found genes known to be critical for placenta function expressed in both species despite their difference in complexity. Additionally, when we compare the transcriptome of different river populations of P. retropinna, known to vary in maternal provisioning, we find differential expression of secretory genes expressed specifically in the top layer of villi cells in the maternal follicle. This provides some of the first evidence that the placental structures of Poeciliopsis function using a secretory mechanism rather than direct contact with maternal circulation. Finally, when we look at the expression of placenta proteins at the maternal-fetal interface of a larger sampling of Poeciliopsis species, we find expression of key maternal and fetal placenta proteins in their cognate tissue types of all species, but follicle expression of prolactin is restricted to only matrotrophic species. Taken together, we suggest that all Poeciliopsis follicles are poised for placenta function but require expression of key genes to form secretory villi.


Assuntos
Evolução Biológica , Ciprinodontiformes/metabolismo , Placentação , Viviparidade não Mamífera , Animais , Ciprinodontiformes/anatomia & histologia , Feminino , Gravidez , Proteínas da Gravidez/metabolismo , Prolactina/metabolismo , Via Secretória/genética , Transcriptoma
17.
Sci Rep ; 10(1): 7378, 2020 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-32355302

RESUMO

In viviparous (live-bearing) animals, embryos face an embryo-specific defecation issue: faecal elimination in utero can cause fatal contamination of the embryonic environment. Our data from the viviparous red stingray (Hemitrygon akajei) reveals how viviparous elasmobranchs circumvent this issue. The exit of the embryonic intestine is maintained closed until close to birth, which allows the accumulation of faeces in the embryonic body. Faecal accumulation abilities are increased by (1) the large intestine size (represents about 400-600% of an adult intestine, proportionally), and (2) the modification in the intestinal inner wall structure, specialized to increase water uptake from the faecal matter. According to the literature, faecal accumulation may occur in embryos of the lamniform white shark as well. The reproductive biology of myliobatiform stingrays and lamniform sharks is characterized by the onset of oral feeding before birth (i.e. drinking of uterine milk and eating of sibling eggs, respectively), which is expected to result in the production of large amounts of faeces during gestation. The strong ability of faecal accumulation in these lineages is therefore likely an adaptation to their unique embryonic nutrition mechanism.


Assuntos
Embrião não Mamífero , Fezes , Rajidae , Viviparidade não Mamífera/fisiologia , Animais , Embrião não Mamífero/anatomia & histologia , Embrião não Mamífero/embriologia , Feminino , Rajidae/anatomia & histologia , Rajidae/fisiologia
18.
Genome Biol Evol ; 12(6): 924-930, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32433751

RESUMO

The water skinks Eulamprus tympanum and Eulamprus heatwolei show thermally induced sex determination where elevated temperatures give rise to male offspring. Paradoxically, Eulamprus species reproduce in temperatures of 12-15 °C making them outliers when compared with reptiles that use temperature as a cue for sex determination. Moreover, these two species are among the very few viviparous reptiles reported to have thermally induced sex determination. Thus, we tested whether these skinks possess undetected sex chromosomes with thermal override. We produced transcriptome and genome data for E. heatwolei. We found that E. heatwolei presents XY chromosomes that include 14 gametologs with regulatory functions. The Y chromosomal region is 79-116 Myr old and shared between water and spotted skinks. Our work provides clear evidence that climate could be useful to predict the type of sex determination systems in reptiles and it also indicates that viviparity is strictly associated with sex chromosomes.


Assuntos
Lagartos/genética , Cromossomos Sexuais , Processos de Determinação Sexual , Viviparidade não Mamífera/genética , Animais , Feminino , Masculino
19.
Placenta ; 95: 26-32, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32452399

RESUMO

In 1926, the German biologist Johanna (Hanni) Hrabowski published a study of the morphology and development of the fetal placenta in lizards that has proven to be of historical importance. Her anatomical descriptions and interpretations identified developmental patterns that differ from other amniotes -- features now recognized as unique attributes of squamate (lizards and snakes) development. Her 1926 monograph presented the first histological comparison of fetal membranes in closely-related oviparous and viviparous reptiles, thereby establishing a comparative framework for understanding placental specializations for viviparity. Hrabowski reported that yolk sac development did not differ between oviparous and viviparous species. The novel, shared components of yolk sac development she identified are now recognized as the foundation for the unique yolk sac placenta of reptiles, the omphaloplacenta. In addition, Hrabowski's extensive ontogenetic sampling and the detail and accuracy of her anatomical descriptions set high standards for subsequent studies of comparative evolutionary embryology.


Assuntos
Membranas Extraembrionárias/anatomia & histologia , Lagartos/anatomia & histologia , Placenta/anatomia & histologia , Anatomia Comparada/história , Animais , Evolução Biológica , Feminino , História do Século XX , Placentação , Gravidez , Viviparidade não Mamífera
20.
Biosci Rep ; 40(4)2020 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-32285916

RESUMO

The Major Histocompatibility Complex (MHC), as a family of highly polymorphic genes associated with immunity in the genome of the vertebrate, has become an important indicator for assessing the evolutionary potential of wildlife. In order to better protect Zootoca vivipara in the Greater Khingan Range and Lesser Khingan Range, to understand the genetic structure of Z. vivipara, and to explore the mechanism and phylogenetic relationship of the gene polymorphisms, the MHC molecular marker method was used to analyze Z. vivipara population. Forty-seven alleles were obtained from four populations. The four populations were highly polymorphic, rich in genetic information, and had significant genetic diversity. There were certain inbreeding phenomena. There was a high degree of genetic differentiation among populations, which was caused by genetic drift and natural selection. The sequence undergoes genetic duplication and recombination. The existence of trans-species polymorphism was found in the constructed phylogenetic tree. The present study provides a theoretical basis for species protection of Z. vivipara.


Assuntos
Genes MHC Classe I/genética , Deriva Genética , Lagartos/genética , Alelos , Distribuição Animal , Animais , China , Conservação dos Recursos Naturais , Feminino , Geografia , Endogamia , Masculino , Filogenia , Polimorfismo Genético , Seleção Genética , Viviparidade não Mamífera
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...