Germline stem cell maintenance as a proximate mechanism of life‐history trade‐offs?

Kaczmarczyk, Angela N.; Kopp, Artyom

doi:10.1002/bies.201000085

Cited by 9 publications

(11 citation statements)

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“…The Drosophila germ line has provided an excellent system for investigating the relationship between organismal aging and age-related changes in stem cell behavior [23], [24], [25], [26], [27], [28], [29]. Aging results in a decline in spermatogenesis, which can be attributed, at least in part, to a significant decrease in the average number of GSCs that progress through the cell cycle more slowly [25], [28], [30].…”

Section: Introductionmentioning

confidence: 99%

Efficiency of Spermatogonial Dedifferentiation during Aging

Wong

Jones

2012

PLoS ONE

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BackgroundAdult stem cells are critical for tissue homeostasis; therefore, the mechanisms utilized to maintain an adequate stem cell pool are important for the survival of an individual. In Drosophila, one mechanism utilized to replace lost germline stem cells (GSCs) is dedifferentiation of early progenitor cells. However, the average number of male GSCs decreases with age, suggesting that stem cell replacement may become compromised in older flies.Methodology/Principal FindingsUsing a temperature sensitive allelic combination of Stat92E to control dedifferentiation, we found that germline dedifferentiation is remarkably efficient in older males; somatic cells are also effectively replaced. Surprisingly, although the number of somatic cyst cells also declines with age, the proliferation rate of early somatic cells, including cyst stem cells (CySCs) increases.ConclusionsThese data indicate that defects in spermatogonial dedifferentiation are not likely to contribute significantly to an aging-related decline in GSCs. In addition, our findings highlight differences in the ways GSCs and CySCs age. Strategies to initiate or enhance the ability of endogenous, differentiating progenitor cells to replace lost stem cells could provide a powerful and novel strategy for maintaining tissue homeostasis and an alternative to tissue replacement therapy in older individuals.

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Section: Introductionmentioning

confidence: 99%

Efficiency of Spermatogonial Dedifferentiation during Aging

Wong

Jones

2012

PLoS ONE

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“…In D. melanogaster , the numbers of germline stem cells in the testes vary with both age (Wang & Jones, ) and diet (McLeod, Wang, Wong, & Jones, ; Wang, McLeod, & Jones, ). Thus, stem cells can respond directly to the nutritional status and thus represent a potential avenue for coordinating diet and fertility (Kaczmarczyk & Kopp, ; Moore, ). We are working to identify cell markers such that we can directly assess germline stem cell dynamics rather than using the indirect measure of transit amplification division rates.…”

Section: Discussionmentioning

confidence: 99%

“…Ultimately, sperm availability depends on the germline, cells set aside for the production of gametes (Extavour, 2013;Moore, 2014). Males have the potential, through germline stem cells, to modulate sperm production (Kaczmarczyk & Kopp, 2011;Moore, 2014;Ramm & Schärer, 2014). While we have many studies examining the developmental and genetic controls on germline stem cells, these cells are rarely examined in an evolutionary context.…”

Section: Introductionmentioning

confidence: 99%

A study of the transit amplification divisions during spermatogenesis in Oncopetus fasciatus to assess plasticity in sperm numbers or sperm viability under different diets

Duxbury

Weathersby

Sanchez

et al. 2018

Ecology and Evolution

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Oncopeltus fasciatus males fed the ancestral diet of milkweed seeds prioritize reproduction over lifespan as evidenced by higher rates of fertility and shorter lifespans than males from the same population fed the adapted diet of sunflower seeds. We examined the proximate mechanisms by which milkweed‐fed males maintained late‐life fertility. We tested the hypothesis that older milkweed‐fed males maintained fertility by producing more, higher quality sperm. Our results, that older males have more sperm, but their sperm do not have higher viability, are in general agreement with other recent studies on how nutrition affects male fertility in insects. We further examined the mechanisms by which sperm are produced by examining the progression of spermatogonial cells through the cell cycle during the transit amplification divisions. We demonstrated that diet affects the likelihood of a spermatocyst being in the S‐phase or M‐phase of the cell cycle. Given work in model systems, these results have implications for subtle effects on sperm quality either through replication stress or epigenetic markers. Thus, viability may not be the best marker for sperm quality and more work is called for on the mechanisms by which the germline and the production of sperm mediate the cost of reproduction.

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“…The InR/TOR system coordinates cell growth and proliferation with the animal's nutritional status. If, as in other systems (Kaczmarczyk and Kopp, 2010), insulin peptides and receptors are key agents in stem cell maintenance and proliferation, it could be anticipated that loss of function mutants or RNAi against homologues to planarian genes for insulin, insulin receptors and transducers, or a reduced TOR signalling would lead, even in well fed animals, to a decrease in neoblast and germ stem cell (GSC) numbers and to enhance late reproduction and longevity. Conversely, constitutive or sustained activation of components of these pathways would lead to increasing numbers of neoblasts and GSC even during periods of severe starvation and to early reproduction and short lifespans.…”

Section: The Ontogenetic Origin Of Neoblasts: Where Do They Come From?mentioning

confidence: 99%

The planarian neoblast: the rambling history of its origin and some current black boxes

Baguñà¹

2012

Int. J. Dev. Biol.

140

111

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First described by Randolph in 1897, the nature and main features of planarian neoblasts have a long rambling history. While their morphologically undifferentiated features have long been recognized, their origin and actual role during regeneration have been highly debated. Here I summarize the main stages of this rambling history: 1) undifferentiated, wandering cells of uncertain origin with a main, albeit undefined, role in regeneration (1890-1940s); 2) quiescent, undifferentiated cells whose main function is to build the blastema during regeneration, an idea which culminated in the 'neoblast theory' of the French School (1940-1960); 3) neoblasts as temporal, undifferentiated cells arising by dedifferentiation from differentiated cells (the 'cell dedifferentiation theory'; 1960-1980s); 4) a new paradigm, starting in the late 1970s-early 1980s, that brought together the role of neoblasts as the main cell for regeneration, with its more important role as somatic stem cells for the daily wear and tear of tissues and as the source of germ cells; and 5) more recent developments that culminate in the report of rescuing lethally irradiated planarians by injection of single neoblasts, which makes of neoblasts an unrivaled toti-, pluripotent somatic stem cell system in the Animal Kingdom. I finally discuss some "black boxes" regarding neoblasts which still baffle us, namely their phylogenetic and ontogenetic origins, their role in body size control, how their pool is regulated during growth and degrowth, the logic of their proliferative control, and some 'old' long-sought missing tools. KEY WORDS: planarian, neoblast, totipotency, dedifferentiation, stem cell A general overview of cell potency during developmentThe developmental potential of cells within embryos, and by extension in adult organisms has been one of the biggest riddles in Developmental Biology. A large amount of observations and experiments soon made clear that egg cells and early blastomeres in most phyla are totipotent cells (cells able to give rise to all cell types including germ cells). It also became evident that as development goes on, such potentialities, however ample, become restricted. After the morula stage in mammals, cells of the inner cell mass and from the outer trophoblasts are no longer totipotent but pluripotent (able to give rise to cell types of all three germ layers or to the placenta, respectively). Later, embryonic germ layers segregate. Embryonic outer cells (ectoderm), give rise to several epidermal derivatives together with central nervous system and neural crest cell types but not to any embryonic inner cells, or endoderm derivatives, and vice versa. Such cells are considered multipotent (able to give rise to several cell types). The final stage, the adult Int. J. Dev. Biol. 56: [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] doi: 10.1387/ijdb.113463jb organism, is formed of thousands, millions, billions, or trillions of cells of different types (over 200-300 in complex vertebrates) patter...

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Germline stem cell maintenance as a proximate mechanism of life‐history trade‐offs?

Cited by 9 publications

References 64 publications

Efficiency of Spermatogonial Dedifferentiation during Aging

Efficiency of Spermatogonial Dedifferentiation during Aging

A study of the transit amplification divisions during spermatogenesis in Oncopetus fasciatus to assess plasticity in sperm numbers or sperm viability under different diets

The planarian neoblast: the rambling history of its origin and some current black boxes

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