The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Dita B Vizoso - One of the best experts on this subject based on the ideXlab platform.
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Phenotypic plasticity in sperm production rate: there’s more to it than Testis Size
Evolutionary Ecology, 2007Co-Authors: Lukas Schärer, Dita B VizosoAbstract:Evolutionary theory predicts that males should produce more sperm when sperm competition is high. Because sperm production rate is difficult to measure in most organisms, comparative and experimental studies have typically used Testis Size instead, while assuming a good correspondence between Testis Size and sperm production rate. Here we evaluate this common assumption using the marine flatworm Macrostomum lignano , in which we can estimate sperm production rate because the accumulation of produced sperm can be observed in vivo. In earlier studies we have shown that Testis Size is phenotypically plastic in M. lignano : worms can be induced to make larger testes by raising them in groups instead of pairs, and these larger testes have a higher cell proliferation activity (i.e. they are more energetically costly). Here we demonstrate that worms with such experimentally enlarged testes have a higher sperm production rate. Moreover, although Testis Size and sperm production rate were related linearly, worms with experimentally enlarged testes had a higher sperm production rate per unit Testis Size (i.e. a higher spermatogenic efficiency). We thus show that phenotypically plastic adjustment of sperm production rate includes a component that is independent of Testis Size. We discuss possible reasons for this novel finding, and suggest that the relationship between Testis Size and sperm production needs to be evaluated in other species as well.
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Phenotypic plasticity in sperm production rate: there's more to it than Testis Size
Evolutionary Ecology, 2006Co-Authors: Lukas Schärer, Dita B VizosoAbstract:Evolutionary theory predicts that males should produce more sperm when sperm competition is high. Because sperm production rate is difficult to measure in most organisms, comparative and experimental studies have typically used Testis Size instead, while assuming a good correspondence between Testis Size and sperm production rate. Here we evaluate this common assumption using the marine flatworm Macrostomum lignano, in which we can estimate sperm production rate because the accumulation of produced sperm can be observed in vivo. In earlier studies we have shown that Testis Size is phenotypically plastic in M. lignano: worms can be induced to make larger testes by raising them in groups instead of pairs, and these larger testes have a higher cell proliferation activity (i.e. they are more energetically costly). Here we demonstrate that worms with such experimentally enlarged testes have a higher sperm production rate. Moreover, although Testis Size and sperm production rate were related linearly, worms with experimentally enlarged testes had a higher sperm production rate per unit Testis Size (i.e. a higher spermatogenic efficiency). We thus show that phenotypically plastic adjustment of sperm production rate includes a component that is independent of Testis Size. We discuss possible reasons for this novel finding, and suggest that the relationship between Testis Size and sperm production needs to be evaluated in other species as well.
Lukas Schärer - One of the best experts on this subject based on the ideXlab platform.
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Phenotypic plasticity in sperm production rate: there’s more to it than Testis Size
Evolutionary Ecology, 2007Co-Authors: Lukas Schärer, Dita B VizosoAbstract:Evolutionary theory predicts that males should produce more sperm when sperm competition is high. Because sperm production rate is difficult to measure in most organisms, comparative and experimental studies have typically used Testis Size instead, while assuming a good correspondence between Testis Size and sperm production rate. Here we evaluate this common assumption using the marine flatworm Macrostomum lignano , in which we can estimate sperm production rate because the accumulation of produced sperm can be observed in vivo. In earlier studies we have shown that Testis Size is phenotypically plastic in M. lignano : worms can be induced to make larger testes by raising them in groups instead of pairs, and these larger testes have a higher cell proliferation activity (i.e. they are more energetically costly). Here we demonstrate that worms with such experimentally enlarged testes have a higher sperm production rate. Moreover, although Testis Size and sperm production rate were related linearly, worms with experimentally enlarged testes had a higher sperm production rate per unit Testis Size (i.e. a higher spermatogenic efficiency). We thus show that phenotypically plastic adjustment of sperm production rate includes a component that is independent of Testis Size. We discuss possible reasons for this novel finding, and suggest that the relationship between Testis Size and sperm production needs to be evaluated in other species as well.
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Phenotypic plasticity in sperm production rate: there's more to it than Testis Size
Evolutionary Ecology, 2006Co-Authors: Lukas Schärer, Dita B VizosoAbstract:Evolutionary theory predicts that males should produce more sperm when sperm competition is high. Because sperm production rate is difficult to measure in most organisms, comparative and experimental studies have typically used Testis Size instead, while assuming a good correspondence between Testis Size and sperm production rate. Here we evaluate this common assumption using the marine flatworm Macrostomum lignano, in which we can estimate sperm production rate because the accumulation of produced sperm can be observed in vivo. In earlier studies we have shown that Testis Size is phenotypically plastic in M. lignano: worms can be induced to make larger testes by raising them in groups instead of pairs, and these larger testes have a higher cell proliferation activity (i.e. they are more energetically costly). Here we demonstrate that worms with such experimentally enlarged testes have a higher sperm production rate. Moreover, although Testis Size and sperm production rate were related linearly, worms with experimentally enlarged testes had a higher sperm production rate per unit Testis Size (i.e. a higher spermatogenic efficiency). We thus show that phenotypically plastic adjustment of sperm production rate includes a component that is independent of Testis Size. We discuss possible reasons for this novel finding, and suggest that the relationship between Testis Size and sperm production needs to be evaluated in other species as well.
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Bigger testes do work more: experimental evidence that Testis Size reflects testicular cell proliferation activity in the marine invertebrate, the free-living flatworm Macrostomum sp.
Behavioral Ecology and Sociobiology, 2004Co-Authors: Lukas Schärer, Peter Ladurner, Reinhard M. RiegerAbstract:Evolutionary theory predicts that more resources are allocated to sperm production when sperm competition is high. This prediction is supported by both comparative and experimental data on static measures of male allocation, such as Testis and ejaculate Size. However, resource allocation is a dynamic process, and it is therefore important to evaluate if the static measures reflect this. Such an evaluation has to our knowledge never been done. Immunocytochemical labelling with bromodeoxyuridine (BrdU) allows visualisation of cells in S-phase. BrdU becomes incorporated into cells if, and only if, they are actively undergoing DNA duplication, which is a dynamic process. The number of BrdU-positive cells in the Testis can hence serve as a dynamic measure of male allocation, i.e. testicular activity. We evaluate the relationship between Testis Size and testicular activity in the marine flatworm Macrostomum sp. In a previous study, we showed that Testis Size is phenotypically plastic in this species, and that worms make larger testes when they are raised in larger groups. We use this plasticity to experimentally produce variation in Testis Size, and demonstrate that larger testes are associated with higher testicular activity. Moreover, Testis Size and testicular activity were related linearly. We have thus, for the first time, shown that Testis Size is a good measure of resource allocation to the male function. Moreover, increased testicular activity is probably one of the first steps in the upregulation of sperm production. It is thus expected that testicular activity is a more sensitive measure of short-term variation in male allocation than the commonly used static measures.
Kosuke Kojo - One of the best experts on this subject based on the ideXlab platform.
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Genome-wide association study of semen volume, sperm concentration, Testis Size, and plasma inhibin B levels.
Journal of human genetics, 2020Co-Authors: Youichi Sato, Atsushi Tajima, Misaki Kiguchi, Suzu Kogusuri, Aki Fujii, Takehiro Sato, Shiari Nozawa, Miki Yoshiike, Makiko Mieno, Kosuke KojoAbstract:Semen quality is affected by environmental factors, endocrine function abnormalities, and genetic factors. A GWAS recently identified ERBB4 at 2q34 as a genetic locus associated with sperm motility. However, GWASs for human semen volume and sperm concentration have not been conducted. In addition, Testis Size also reportedly correlates with semen quality, and it is important to identify genes that affect Testis Size. Reproductive hormones also play an important role in spermatogenesis. To date, genetic loci associated with plasma testosterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels have been identified using GWASs. However, GWASs have not identified any relevant loci for plasma inhibin B levels. We conducted a two-stage GWAS using 811 Japanese men in a discovery stage followed by a replication stage using an additional 721 Japanese men. The results of the discovery and replication stages were combined into a meta-analysis. After setting a suggestive significance threshold for P values
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genome wide association study of semen volume sperm concentration Testis Size and plasma inhibin b levels
Journal of Human Genetics, 2020Co-Authors: Youichi Sato, Atsushi Tajima, Misaki Kiguchi, Suzu Kogusuri, Aki Fujii, Takehiro Sato, Shiari Nozawa, Miki Yoshiike, Makiko Mieno, Kosuke KojoAbstract:Semen quality is affected by environmental factors, endocrine function abnormalities, and genetic factors. A GWAS recently identified ERBB4 at 2q34 as a genetic locus associated with sperm motility. However, GWASs for human semen volume and sperm concentration have not been conducted. In addition, Testis Size also reportedly correlates with semen quality, and it is important to identify genes that affect Testis Size. Reproductive hormones also play an important role in spermatogenesis. To date, genetic loci associated with plasma testosterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels have been identified using GWASs. However, GWASs have not identified any relevant loci for plasma inhibin B levels. We conducted a two-stage GWAS using 811 Japanese men in a discovery stage followed by a replication stage using an additional 721 Japanese men. The results of the discovery and replication stages were combined into a meta-analysis. After setting a suggestive significance threshold for P values < 5 × 10−6 in the discovery stage, we identified ten regions with SNPs (semen volume: one, sperm concentration: three, testes Size: two, and inhibin B: four). We selected only the most significant SNP in each region for replication genotyping. Combined discovery and replication results in the meta-analysis showed that the locus 12q21.31 associated with plasma inhibin B levels (rs11116724) had the most significant association (P = 5.7 × 10−8). The LRRIQ1 and TSPAN19 genes are located in the 12q21.31 region. This study provides new susceptibility variants that contribute to plasma inhibin B levels.
Youichi Sato - One of the best experts on this subject based on the ideXlab platform.
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Genome-wide association study of semen volume, sperm concentration, Testis Size, and plasma inhibin B levels.
Journal of human genetics, 2020Co-Authors: Youichi Sato, Atsushi Tajima, Misaki Kiguchi, Suzu Kogusuri, Aki Fujii, Takehiro Sato, Shiari Nozawa, Miki Yoshiike, Makiko Mieno, Kosuke KojoAbstract:Semen quality is affected by environmental factors, endocrine function abnormalities, and genetic factors. A GWAS recently identified ERBB4 at 2q34 as a genetic locus associated with sperm motility. However, GWASs for human semen volume and sperm concentration have not been conducted. In addition, Testis Size also reportedly correlates with semen quality, and it is important to identify genes that affect Testis Size. Reproductive hormones also play an important role in spermatogenesis. To date, genetic loci associated with plasma testosterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels have been identified using GWASs. However, GWASs have not identified any relevant loci for plasma inhibin B levels. We conducted a two-stage GWAS using 811 Japanese men in a discovery stage followed by a replication stage using an additional 721 Japanese men. The results of the discovery and replication stages were combined into a meta-analysis. After setting a suggestive significance threshold for P values
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genome wide association study of semen volume sperm concentration Testis Size and plasma inhibin b levels
Journal of Human Genetics, 2020Co-Authors: Youichi Sato, Atsushi Tajima, Misaki Kiguchi, Suzu Kogusuri, Aki Fujii, Takehiro Sato, Shiari Nozawa, Miki Yoshiike, Makiko Mieno, Kosuke KojoAbstract:Semen quality is affected by environmental factors, endocrine function abnormalities, and genetic factors. A GWAS recently identified ERBB4 at 2q34 as a genetic locus associated with sperm motility. However, GWASs for human semen volume and sperm concentration have not been conducted. In addition, Testis Size also reportedly correlates with semen quality, and it is important to identify genes that affect Testis Size. Reproductive hormones also play an important role in spermatogenesis. To date, genetic loci associated with plasma testosterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels have been identified using GWASs. However, GWASs have not identified any relevant loci for plasma inhibin B levels. We conducted a two-stage GWAS using 811 Japanese men in a discovery stage followed by a replication stage using an additional 721 Japanese men. The results of the discovery and replication stages were combined into a meta-analysis. After setting a suggestive significance threshold for P values < 5 × 10−6 in the discovery stage, we identified ten regions with SNPs (semen volume: one, sperm concentration: three, testes Size: two, and inhibin B: four). We selected only the most significant SNP in each region for replication genotyping. Combined discovery and replication results in the meta-analysis showed that the locus 12q21.31 associated with plasma inhibin B levels (rs11116724) had the most significant association (P = 5.7 × 10−8). The LRRIQ1 and TSPAN19 genes are located in the 12q21.31 region. This study provides new susceptibility variants that contribute to plasma inhibin B levels.
Shiari Nozawa - One of the best experts on this subject based on the ideXlab platform.
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Genome-wide association study of semen volume, sperm concentration, Testis Size, and plasma inhibin B levels.
Journal of human genetics, 2020Co-Authors: Youichi Sato, Atsushi Tajima, Misaki Kiguchi, Suzu Kogusuri, Aki Fujii, Takehiro Sato, Shiari Nozawa, Miki Yoshiike, Makiko Mieno, Kosuke KojoAbstract:Semen quality is affected by environmental factors, endocrine function abnormalities, and genetic factors. A GWAS recently identified ERBB4 at 2q34 as a genetic locus associated with sperm motility. However, GWASs for human semen volume and sperm concentration have not been conducted. In addition, Testis Size also reportedly correlates with semen quality, and it is important to identify genes that affect Testis Size. Reproductive hormones also play an important role in spermatogenesis. To date, genetic loci associated with plasma testosterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels have been identified using GWASs. However, GWASs have not identified any relevant loci for plasma inhibin B levels. We conducted a two-stage GWAS using 811 Japanese men in a discovery stage followed by a replication stage using an additional 721 Japanese men. The results of the discovery and replication stages were combined into a meta-analysis. After setting a suggestive significance threshold for P values
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genome wide association study of semen volume sperm concentration Testis Size and plasma inhibin b levels
Journal of Human Genetics, 2020Co-Authors: Youichi Sato, Atsushi Tajima, Misaki Kiguchi, Suzu Kogusuri, Aki Fujii, Takehiro Sato, Shiari Nozawa, Miki Yoshiike, Makiko Mieno, Kosuke KojoAbstract:Semen quality is affected by environmental factors, endocrine function abnormalities, and genetic factors. A GWAS recently identified ERBB4 at 2q34 as a genetic locus associated with sperm motility. However, GWASs for human semen volume and sperm concentration have not been conducted. In addition, Testis Size also reportedly correlates with semen quality, and it is important to identify genes that affect Testis Size. Reproductive hormones also play an important role in spermatogenesis. To date, genetic loci associated with plasma testosterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels have been identified using GWASs. However, GWASs have not identified any relevant loci for plasma inhibin B levels. We conducted a two-stage GWAS using 811 Japanese men in a discovery stage followed by a replication stage using an additional 721 Japanese men. The results of the discovery and replication stages were combined into a meta-analysis. After setting a suggestive significance threshold for P values < 5 × 10−6 in the discovery stage, we identified ten regions with SNPs (semen volume: one, sperm concentration: three, testes Size: two, and inhibin B: four). We selected only the most significant SNP in each region for replication genotyping. Combined discovery and replication results in the meta-analysis showed that the locus 12q21.31 associated with plasma inhibin B levels (rs11116724) had the most significant association (P = 5.7 × 10−8). The LRRIQ1 and TSPAN19 genes are located in the 12q21.31 region. This study provides new susceptibility variants that contribute to plasma inhibin B levels.