RESUMO
Viviparous (live-bearing) vertebrates have evolved repeatedly within otherwise oviparous (egg-laying) clades. Over two-thirds of these changes in vertebrate reproductive parity mode happened in squamate reptiles, where the transition has happened between 98 and 129 times. The transition from oviparity to viviparity requires numerous physiological, morphological, and immunological changes to the female reproductive tract, including eggshell reduction, delayed oviposition, placental development for supply of water and nutrition to the embryo by the mother, enhanced gas exchange, and suppression of maternal immune rejection of the embryo. We performed genomic and transcriptomic analyses of a closely related oviparous-viviparous pair of lizards (Phrynocephalus przewalskii and Phrynocephalus vlangalii) to examine these transitions. Expression patterns of maternal oviduct through reproductive development of the egg and embryo differ markedly between the two species. We found changes in expression patterns of appropriate genes that account for each of the major aspects of the oviparity to viviparity transition. In addition, we compared the gene sequences in transcriptomes of four oviparous-viviparous pairs of lizards in different genera (Phrynocephalus, Eremias, Scincella, and Sphenomorphus) to look for possible gene convergence at the sequence level. We discovered low levels of convergence in both amino acid replacement and evolutionary rate shift. This suggests that most of the changes that produce the oviparity-viviparity transition are changes in gene expression, so occasional reversals to oviparity from viviparity may not be as difficult to achieve as has been previously suggested.
Assuntos
Evolução Molecular , Oviparidade/genética , Transcriptoma/genética , Viviparidade não Mamífera/genética , Animais , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Genômica , Lagartos/genética , Lagartos/crescimento & desenvolvimento , Filogenia , Placentação/genética , Gravidez , Reprodução/genética , Serpentes/genética , Serpentes/crescimento & desenvolvimentoRESUMO
The development of efficient sequencing techniques has resulted in large numbers of genomes being available for evolutionary studies. However, only one genome is available for all amphibians, that of Xenopus tropicalis, which is distantly related from the majority of frogs. More than 96% of frogs belong to the Neobatrachia, and no genome exists for this group. This dearth of amphibian genomes greatly restricts genomic studies of amphibians and, more generally, our understanding of tetrapod genome evolution. To fill this gap, we provide the de novo genome of a Tibetan Plateau frog, Nanorana parkeri, and compare it to that of X. tropicalis and other vertebrates. This genome encodes more than 20,000 protein-coding genes, a number similar to that of Xenopus. Although the genome size of Nanorana is considerably larger than that of Xenopus (2.3 vs. 1.5 Gb), most of the difference is due to the respective number of transposable elements in the two genomes. The two frogs exhibit considerable conserved whole-genome synteny despite having diverged approximately 266 Ma, indicating a slow rate of DNA structural evolution in anurans. Multigenome synteny blocks further show that amphibians have fewer interchromosomal rearrangements than mammals but have a comparable rate of intrachromosomal rearrangements. Our analysis also identifies 11 Mb of anuran-specific highly conserved elements that will be useful for comparative genomic analyses of frogs. The Nanorana genome offers an improved understanding of evolution of tetrapod genomes and also provides a genomic reference for other evolutionary studies.
Assuntos
Anuros/genética , Evolução Molecular , Genoma/genética , Animais , Sequência de Bases , Galinhas/genética , Cromossomos/genética , Elementos de DNA Transponíveis/genética , Feminino , Humanos , Família Multigênica , Sintenia/genética , TibetRESUMO
OBJECTIVE: To search for a simple and effective surgical approach to the management of moderate to severe pediatric concealed penis in children. METHODS: We used Devine's technique via incision between the penis and scrotum in the treatment of 68 cases of moderate to severe pediatric concealed penis. The patients were aged 3 -13 (mean 6.5) years, 30 with moderate and 38 with severe pediatric concealed penis. RESULTS: This strategy achieved good near- and long-term effects and satisfactory appearance of the penis, which was similar to that of circumcision. At 3 months after surgery, the penile length was 3 - 5.2 cm, averaging (2.35 +/- 0.35) cm. CONCLUSION: Devine's technique via incision between the penis and scrotum is a simple and effective surgical option for moderate to severe pediatric concealed penis in children.