The Genomics of Placenta Evolution in Livebearing Fish PDF Download
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Author:
Publisher:
ISBN: 9789464470376
Category :
Languages : en
Pages : 174
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Book Description
Author:
Publisher:
ISBN: 9789464470376
Category :
Languages : en
Pages : 174
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Book Description
Author: Amanda Inez Banet
Publisher:
ISBN:
Category : Desert topminnows
Languages : en
Pages : 121
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Book Description
Placental matrotrophy has evolved independently in many lineages, which is indicative of strong selection. Several ad-hoc hypotheses and one mathematical model have been proposed to explain its evolution, but little experimental data exists to support these claims. Recent studies have attempted to find correlates between placental matrotrophy and other life history traits, but the only common correlate found was a reduction in reproductive allocation (RA). Here I report on three studies. The first two focus on the Trexler-DeAngelis model for the evolution of matrotrophy. In chapter one, I use closely related placental and non-placental species from the northern clade of Poeciliopsis to test an assumption imperative to the model, that placental species abort a subset of developing offspring in low food conditions. The results show no evidence of abortion due to food level. Instead, placental species appear to be tethered to a brood once initiated, and sacrifice body condition to maintain reproduction when resources are restricted. However, an alternative explanation for these results is that the pattern of resource allocation is a function other life history traits, rather than placentation alone. Chapter two distinguishes between these alternatives, by performing a similar experiment on the southern clade of Poeciliopsis, which has the opposite relationship between life history traits and placentation seen in the northern clade. The results mirror those from the northern clade, indicating reproductive mode, rather than life history, dictates the pattern of resource allocation. This further adds to the difficulties of explaining the evolution of the placenta within the constraints of the Trexler-DeAngelis model. The third study characterizes locomotor consequences related to differences in reproductive allocation using the Trinidadian Guppy (Poecilia reticulata), because placentation is correlated with a reduction in reproductive allocation. Females with the highest RA were less streamlined, had lower escape velocities, and had to work harder during prolonged swimming. In low predation natural habitat, these same females were restricted to habitat with slower moving water, while females with lower RAs were able to use faster flows, which are thought to be preferred feeding grounds. All high predation fish used slow moving water, irrespective of RA.
Author: Richard Van Der Laan
Publisher:
ISBN: 9781775575740
Category : Fishes
Languages : en
Pages : 230
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Book Description
The family-group names of animals (superfamily, family, subfamily, supertribe, tribe and subtribe) are regulated by the International Code of Zoological Nomenclature. Family names are particularly important because they are among the most widely used of all technical animal names. Apart from using the correct family-group name according to the Code, it is also important to use one unique universal name (with a fixed spelling) to avoid confusion. We have compiled a list of familygroup names for Recent fishes, applied the rules of the Code and, if possible, tried to conserve the names in prevailing recent practice. We list all of the family-group names found to date for Recent fishes (N=2625), together with their author(s) and year of publication. This list can be used in assigning the correct family-group name to a genus or a group of genera. With this publication we contribute to the usage of correct, universal family-group names in the classification of, and for communication about, Recent fishes.
Author: Zhiyuan Gong
Publisher: World Scientific
ISBN: 9814482854
Category : Science
Languages : en
Pages : 684
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Book Description
The zebrafish is the most important fish model in developmental and genetic analyses. This book contains 19 review articles covering a broad spectrum of topics, from development to genetic tools. The contents range from early development, the role of maternal factors and gastrulation, to tissue differentiation and organogenesis, such as development of the organizer, notochord, floor plate, nervous system, somites, muscle, skeleton and endoderm. The genetic tools cover morpholino knock-down, transgenics, fish cloning, transposons and genome evolution. The book also includes two chapters on genome mapping and embryonic stem cells in medaka, another important model fish. Summarizing the state-of-the-art studies of the zebrafish model and focusing on the molecular aspects of development, this book is a valuable reference for students learning the basic aspects of the zebrafish model, and for researchers seeking resources in zebrafish research.
Author: Michael L. Power
Publisher: JHU Press
ISBN: 1421406438
Category : Science
Languages : en
Pages : 280
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Book Description
As the active interface of the most biologically intimate connection between two living organisms, a mother and her fetus, the placenta is crucial to human evolution and survival. Michael L. Power and Jay Schulkin explore the more than 100 million years of evolution that led to the human placenta and, in so doing, they help unravel the mysteries of human life's first moments. Starting with some of the earliest events that have influenced the path of placental evolution in mammals and progressing to the specifics of the human placenta, this book examines modern gestation within an evolutionary framework. Human beings are a successful species and our numbers have increased dramatically since our earliest days on Earth. However, human fetal development is fraught with poor outcomes for both the mother and fetus that appear to be, if not unique, far more common in humans than in other mammals. High rates of early pregnancy loss, nausea and vomiting during pregnancy, preeclampsia and related maternal hypertension, and preterm birth are rare or absent in other mammals yet not unusual in humans. Power and Schulkin explain why this apparent contradiction exists and address such topics as how the placenta regulates and coordinates the metabolism, growth, and development of both mother and fetus, the placenta’s role in protecting a fetus from the mother’s immune system, and placental diseases. In the process, they reveal the vital importance of this organ—which is composed mostly of fetal cells—for us as individuals and as a species. -- Errol R. Norwitz, Tufts University School of Medicine and Tufts Medical Center
Author: Michael Warren Guernsey
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The placenta is a unique extra-embryonic organ that facilitates pregnancy in many live-bearing animals. Placentas exhibit great morphological diversity both within mammals, but also in many different vertebrate lineages where the placenta evolved independently. Despite this diversity in structure, all placentas must allow for nutrient provisioning, gas exchange, waste removal, endocrine maintenance of pregnancy and protection from pathogens to achieve a successful pregnancy. While these functions are conserved, we know less about how this similarity extends to the molecular level. Here I investigate this using the Tammar wallaby and Poeciliopsis fishes as models. First, I utilize transcriptome sequencing in the tammar wallaby to provide evidence that the classification of therian mammals into eutherian (placental) and marsupial (pouch-bearing) based upon having a 'true' placenta is inaccurate. We show that the tammar yolk sac, often argued to be the cognate of the eutherian yolk sac, is surprisingly similar to the mouse and human placenta. Furthermore, immunofluorescence in tammar placenta demonstrates protein localization of genes known to be essential for eutherian placentation to distinct cell layers of the tammar placenta. This striking molecular conservation suggests that although the marsupial placenta is morphologically simple, it represents a 'true' placenta reminiscent of the most complex eutherian forms. Once we solidify that the tammar wallaby does indeed have a eutherian-like placenta, we examine the evolution of placentation and lactation as strategies for nourishing young. Marsupial biologists have hypothesized that these processes are involved in an evolutionary tradeoff and, as a result, marsupials favored the development of complex lactation while eutherians favored complex placentation to support fetal survival. Interestingly, we find that many of the genetic programs involved in lactation and placentation have been shared, co-opted and exchanged during evolution. These genetic programs have been shifted in both directions: from lactation to placentation and from placentation to lactation. Overall, the recycling of genetic programs to optimize nourishment strategies in each species is a novel finding and surprisingly suggests that placentation and lactation are similar processes. Next, I study Poeciliopsis, a unique genus of live-bearing fish that have evolved placental structures at least three times independently. The maternal follicle is a key component of these structures; it envelops yolk rich eggs and is morphologically simple in non-placental species, but has elaborate villous structures in placental species. Through sequencing the follicle transcriptome of a placental, P. retropinna, and non-placental, 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 exchange between maternal-fetal 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 only placental species show follicle expression of Prolactin. Taken together, we suggest that all Poeciliopsis follicles are poised for placenta function, but require expression of key genes to form villi.
Author: Marcelo Nolla Pires
Publisher:
ISBN:
Category : Desert topminnows
Languages : en
Pages : 508
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Author:
Publisher:
ISBN: 9789463956277
Category :
Languages : en
Pages : 226
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Book Description
Understanding the evolution of complex traits is of fundamental interest to scientists and non-scientists alike. The placenta is an excellent example of a complex trait that has evolved repeatedly throughout the animal kingdom. This repeated evolution and ongoing elaboration appears to point towards an adaptive advantage to specific environmental conditions; however, this potential benefit is currently insufficiently understood. In this thesis, I attempt to shed light on the causes and consequences of placental evolution by drawing on insights from the live-bearing fish family Poeciliidae.
Author: Bruce Turner
Publisher: Springer Science & Business Media
ISBN: 1468446525
Category : Science
Languages : en
Pages : 651
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Book Description
It is my hope that this collection of reviews can be profitably read by all who are interested in evolutionary biology. However, I would like to specifically target it for two disparate groups of biologists seldom men tioned in the same sentence, classical ichthyologists and molecular biologists. Since classical times, and perhaps even before, ichthyologists have stood in awe at the tremendous diversity of fishes. The bulk of effort in the field has always been directed toward understanding this diversity, i. e. , extracting from it a coherent picture of evolutionary processes and lineages. This effort has, in turn, always been overwhelmingly based upon morphological comparisons. The practical advantages of such compari sons, especially the ease with which morphological data can be had from preserved museum specimens, are manifold. But considered objectively (outside its context of "tradition"), morphological analysis alone is a poor tool for probing evolutionary processes or elucidating relationships. The concepts of "relationship" and of "evolution" are inherently genetic ones, and the genetic bases of morphological traits are seldom known in detail and frequently unknown entirely. Earlier in this century, several workers, notably Gordon, Kosswig, Schmidt, and, in his salad years, Carl Hubbs, pioneered the application of genetic techniques and modes of reasoning to ichthyology. While certain that most contemporary ichth yologists are familiar with this body of work, I am almost equally certain that few of them regard it as pertinent to their own efforts.
Author: Edward Bo-yi Chuong
Publisher:
ISBN:
Category :
Languages : en
Pages :
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The placenta plays a fundamental role supporting pregnancy in all mammals, but exhibits unexpected and striking morphological and physiological variation across species. The rapid evolutionary diversification of the mammalian placenta is hypothesized to be a product of recurrent genetic conflict between parent and offspring. In this work, I investigate the genetic basis of rapid placenta evolution by using high-throughput genomic approaches, and address three major issues in placental biology. First, given that highly conserved genes govern placental development, the molecular mechanisms underlying the rapid diversification of placental morphology have remained unresolved. Our study reveals that the genome-wide regulatory landscape of placental development is highly divergent between closely related species, strongly implicating non-coding regulatory evolution as the major force driving placental morphological diversity. Second, endogenous retroviruses (ERVs) that are normally repressed throughout the embryo are rampantly expressed in the placenta, but the biological rationale--if any-- behind this apparent paradox has been unclear. We demonstrate that species-specific ERVs serve as a major source of functional enhancers during placental development, which provides a clear mechanism where placental ERV activity may facilitate the evolutionary diversification of placental morphology. Finally, our findings suggest a novel evolutionary model where placental ERVs provide an adaptive benefit under parent-offspring conflict. Given that genetic conflict predicts rapid diversifying evolution to maintain maximal fitness, we propose that placental ERVs act to dramatically increase the developmental evolvability of the placenta by serving as a rapidly evolving, epigenetically restricted source of polymorphic regulatory elements.
