Reproductive Biology in Egg-Laying Mammals

@article{Grtzner2008ReproductiveBI,
  title={Reproductive Biology in Egg-Laying Mammals},
  author={Frank Gr{\"u}tzner and Brett Nixon and R.C. Jones},
  journal={Sexual Development},
  year={2008},
  volume={2},
  pages={115 - 127}
}
The duck-billed platypus and short-beaked echidna are iconic species in Australia. Their morphology and physiology have puzzled scientists all over the world for more than 200 years. Recent genetic studies, particularly the platypus whole-genome sequencing project, have revealed the molecular basis of some of the extraordinary characteristics of monotremes. This and other works demonstrate the great value of research on our most distantly related mammalian relatives for comparative genomics and… Expand
The enigma of the platypus genome
TLDR
Some of the key findings of the analysis of the platypus genome are discussed and point to new findings and future research directions, which illustrate the broad impact of the monotreme biology and mammalian genome evolution. Expand
Platypus Genome Provides Unique Insights into Early Mammalian Evolution and Monotreme Biology
TLDR
The recently completed draft genome of the duck-billed platypus fills this gap in comparative genomics, and provides unique insights into the evolution of mammalian genes, regulatory mechanisms and nonprotein-coding sequences. Expand
Evolution and Organization of Monotreme Sex Chromosomes
TLDR
Monotremes have an unusually complex sex chromosome system which shares extensive homology to bird sex chromosomes and no homologies to sex chromosomes in other mammals, which raises fundamental questions about its evolution, meiotic organization and dosage compensation and about sex determination in monotremees. Expand
Monotremes provide a key to understanding the evolutionary significance of epididymal sperm maturation.
TLDR
It is suggested that this intriguing cooperative strategy used by monotreme sperm represents an early form of epididymal maturation that appears to have been elaborated upon during the evolution of higher mammals, possibly as an adaptation for sperm competition. Expand
Copulatory and Postcopulatory Sexual Selection in Primates
  • A. Dixson
  • Biology, Medicine
  • Folia Primatologica
  • 2018
TLDR
Current knowledge of sperm competition and cryptic choice in primates and other mammals is reviewed and the relevance of these comparative studies to the understanding of human reproduction and evolution is discussed. Expand
Molecular insights into the divergence and diversity of post-testicular maturation strategies
TLDR
Here, literature pertaining to the nature and the physiological role of epididymal maturation and subsequent capacitation in comparative vertebrate taxa including representative species from the avian, reptilian, and mammalian lineages are reviewed. Expand
Sperm Competition, Sexual Selection, and the Diverse Reproductive Biology of Osteoglossiformes.
TLDR
It is suggested that the patterns seen in osteoglossiform reproduction are a microcosm of teleost reproductive diversity, potentially signifying the genetic plasticity that contributed to the adaptive radiation ofteleost fishes. Expand
Gonadal Asymmetry and Sex Determination in Birds
TLDR
The morphological development and molecular basis of this unusual asymmetry in the chick embryo are described, the implications for avian sex determination are considered, and the possible biological reasons why many birds have adopted a single-ovary system are discussed. Expand
Platypus chain reaction: directional and ordered meiotic pairing of the multiple sex chromosome chain in Ornithorhynchus anatinus.
TLDR
This work has analysed the pairing dynamics of specific sex chromosome pseudoautosomal regions in platypus spermatocytes during prophase of meiosis I and shows a highly coordinated pairing process that begins at the terminal Y5 chromosome and completes with the union of sex chromosomes X1Y1. Expand
The Testatin/Cres subgroup of family 2 cystatins in sexual development
TLDR
The evolutionary origin of the Testatin/Cres subgroup genes to the split between Marsupials and placental mammals is localized and a model for the evolution of these genes illustrates that they constitute a dynamic group of genes, which has undergone several gene expansions. Expand
...
1
2
3
...

References

SHOWING 1-10 OF 130 REFERENCES
Echidna: Extraordinary Egg-Laying Mammal
TLDR
The authors reveal some fascinating new findings, showing how echidnas are masters of their environment, and not simply some sort of mammal ‘test model’ that went wrong. Expand
Adaptations of the short-beaked echidna Tachyglossus aculateus for sperm production, particularly in an arid environment.
TLDR
It is suggested that T. aculateus is also specialised for sperm competition, and the size of their testes and number of extragonadal sperm compared with other mammals are indicative that they are involved in sperm competition. Expand
Bird-like sex chromosomes of platypus imply recent origin of mammal sex chromosomes.
In therian mammals (placentals and marsupials), sex is determined by an XX female: XY male system, in which a gene (SRY) on the Y affects male determination. There is no equivalent in other amniotes,Expand
The multiple sex chromosomes of platypus and echidna are not completely identical and several share homology with the avian Z
TLDR
A comparative study of platypus and echidna by chromosome painting and comparative gene mapping shows that monotremes have a unique XY sex chromosome system that shares some homology with the avian Z. Expand
A platypus' eye view of the mammalian genome.
TLDR
This work has confirmed the traditional interpretation that the monotreme genome is the earliest offshoot of the mammalian lineage, and the proposal to sequence the platypus genome has been received enthusiastically by the genomics community. Expand
Spermiogenesis and spermiation in a monotreme mammal, the platypus, Ornithorhynchus anatinus
TLDR
The ultrastructure of 16 steps of spermatid development is described and provides a basis for determining the kinetics of sPermatogenesis. Expand
How did the platypus get its sex chromosome chain? A comparison of meiotic multiples and sex chromosomes in plants and animals
TLDR
It is concluded that the evolutionary conservation of the chain in monotremes, the structural properties of the translocated chromosomes and the highly accurate segregation at meiosis make the platypus system remarkably different from meiotic multiples in other species. Expand
Sex determination in platypus and echidna: autosomal location of SOX3 confirms the absence of SRY from monotremes
TLDR
The autosomal localization of SOX3 in monotreme mammals, as well as non-mammal vertebrates, implies that SRY is absent in Prototheria and evolved later in the therian lineage 210-180 million years ago, implying sex determination in platypus and echidna must therefore depend on another male-determining gene(s) on the Y chromosomes, or on the different dosage of a gene on the X chromosomes. Expand
Postnatal development of the reproductive system in the grey short-tailed opossum, Monodelphis domestica
TLDR
In summary, postnatal reproductive tract development and gonadal descent has been examined in this important biomedical model, where differentiation of the wolffian and müllerian ducts takes place after gonadal differentiation, according to the normal eutherian pattern. Expand
Trophoblast and hypoblast in the monotreme, marsupial and eutherian mammal: evolution and origins
  • L. Selwood, Martin H. Johnson
  • Biology, Medicine
  • BioEssays : news and reviews in molecular, cellular and developmental biology
  • 2006
TLDR
It is suggested that the gross differences can be explained by two relatively small evolutionary timing changes affecting cell adhesion patterns and the polarisation of developmentally significant information. Expand
...
1
2
3
4
5
...