scholarly journals Sex determination in mammalian germ cells: extrinsic versus intrinsic factors

Reproduction ◽  
2010 ◽  
Vol 139 (6) ◽  
pp. 943-958 ◽  
Author(s):  
Josephine Bowles ◽  
Peter Koopman
Keyword(s):  
Germ Cells ◽  
Critical Time ◽  
Fetal Life ◽  
Extrinsic Factors ◽  
Intrinsic Factors ◽  
Fetal Testis ◽  
Time Period ◽  
Full Complement ◽  
Fetal Ovary ◽  
Male Specific

Mammalian germ cells do not determine their sexual fate based on their XX or XY chromosomal constitution. Instead, sexual fate is dependent on the gonadal environment in which they develop. In a fetal testis, germ cells commit to the spermatogenic programme of development during fetal life, although they do not enter meiosis until puberty. In a fetal ovary, germ cells commit to oogenesis by entering prophase of meiosis I. Although it was believed previously that germ cells are pre-programmed to enter meiosis unless they are actively prevented from doing so, recent results indicate that meiosis is triggered by a signaling molecule, retinoic acid (RA). Meiosis is avoided in the fetal testis because a male-specifically expressed enzyme actively degrades RA during the critical time period. Additional extrinsic factors are likely to influence sexual fate of the germ cells, and in particular, we postulate that an additional male-specific fate-determining factor or factors is involved. The full complement of intrinsic factors that underlie the competence of gonadal germ cells to respond to RA and other extrinsic factors is yet to be defined.

scholarly journals Meiosis Initiates In The Fetal Ovary Of Mice Lacking All Retinoic Acid Receptor Isotypes

2019 ◽  
Author(s):  
Nadège Vernet ◽  
Manuel Mark ◽  
Diana Condrea ◽  
Betty Féret ◽  
Muriel Klopfenstein ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Germ Cells ◽  
Congenital Abnormalities ◽  
Retinoic Acid Receptor ◽  
Current Model ◽  
Fetal Life ◽  
Genetic Approach ◽  
Molecular Signal ◽  
Fetal Ovary ◽  
Multiple Congenital Abnormalities

AbstractGametes are generated through a specialized cell differentiation process, meiosis which, in most mammals, is initiated in ovaries during fetal life. It is widely admitted that all-trans retinoic acid (ATRA) is the molecular signal triggering meiosis initiation in mouse female germ cells, but a genetic approach in which ATRA synthesis is impaired disputes this proposal. In the present study, we investigated the contribution of endogenous ATRA to meiosis by analyzing fetuses lacking all RARs ubiquitously, obtained through a tamoxifen-inducible cre recombinase-mediated gene targeting approach. Efficient ablation of RAR-coding genes was assessed by the multiple congenital abnormalities displayed by the mutant fetuses. Unexpectedly, their germ cells robustly expressed STRA8, REC8, SYCP1 and SYCP3, showing that RAR are actually dispensable up to the zygotene stage of meiotic prophase I. Thus our study goes against the current model according to which meiosis is triggered by endogenous ATRA in the developing ovary and revives the identification of the meiosis-preventing substance synthesized by CYP26B1 in the fetal testis.

scholarly journals Differential Expression of Two Estrogen Receptor β Isoforms in the Human Fetal Testis during the Second Trimester of Pregnancy

2003 ◽  
Vol 88 (1) ◽  
pp. 424-432 ◽  
Author(s):  
Terri L. Gaskell ◽  
Lynne L. L. Robinson ◽  
Nigel P. Groome ◽  
Richard A. Anderson ◽  
Philippa T. K. Saunders
Keyword(s):  
Germ Cells ◽  
Reproductive Tract ◽  
Somatic Cells ◽  
Dominant Negative ◽  
Fetal Life ◽  
Second Trimester ◽  
Wild Type ◽  
Rt Pcr ◽  
Estrogen Action ◽  
Fetal Testis

Testicular cancer is more common in individuals with disorders of the male reproductive tract. It has been suggested that inappropriate exposure to estrogens during fetal life may have an impact on maturation of testicular germ cells that are the cells of origin of the majority of testis cancers. The aim of the present study was to establish whether human fetal germ cells (gonocytes) are a potential target of estrogen action. To address this issue, we used RT-PCR and immunohistochemistry to examine the pattern of expression of estrogen receptors (ERα, ERβ, and ERβ2 variant) in human fetal testes at 12–19 wk gestation. ERα, mRNA, and protein were not detected in any of the fetal testes. In contrast, using an antibody directed against the hinge domain of ERβ expression was detected in multiple testicular nuclei. RT-PCR with primers specific for full-length wild-type ERβ (ERβ1) or the ERβ2 variant formed by splicing of an alternative eighth exon, was performed on whole-tissue extracts and materials recovered by laser capture and revealed that mRNAs for both isoforms were expressed. Immunohistochemistry with isotype-specific monoclonal antibodies showed that ERβ1 was low/undetectable in gonocytes, whereas these cells expressed the highest levels of ERβ2, compared with other testicular cell types. Both ERβ1 and ERβ2 were detected in some but not all Sertoli cells, peritubular cells, and other interstitial cells including those tentatively identified as Leydig cells. Our immunohistochemical results demonstrate that during the second trimester, some but not all somatic cells within the human fetal testis express wild-type ERβ (ERβ1) protein and/or the variant isoform of ERβ (ERβ2) that lacks amino acids essential for binding of estradiol. ERβ2 protein was readily detectable in fetal gonocytes, whereas ERβ1 was not. We did not detect expression of ERα. The expression of ERβ2, a variant proposed act as a dominant negative receptor, might prevent estrogen action in gonocytes. We suggest that during this period of fetal life, estrogenic ligands are most likely to act on somatic cells that contain ERβ1 protein.

Institutional Environment, Entrepreneurial Self-Efficacy and Entrepreneurial Intention of Company Employees

1970 ◽  
Vol 3 (1) ◽  
pp. 1-9
Author(s):  
Devi Angrahini Anni Lembana ◽  
Yu Yu Chang ◽  
Wen Ke Liang
Keyword(s):  
Self Efficacy ◽  
Institutional Environment ◽  
Practical Experience ◽  
Entrepreneurial Intention ◽  
Entrepreneurial Intentions ◽  
New Venture ◽  
Hierarchical Regression ◽  
Market Demand ◽  
Extrinsic Factors ◽  
Intrinsic Factors

From the intentionality-based view, individuals' actual behaviors to initiate a new venture is driven by their entrepreneurial intentions. Company employees have accumulated professionalism and practical experience, which both enable them to discover some unmet market demand and industrial gaps. However, in establishing a new business, not everyone with certain knowledge or expertise has the desire to become an entrepreneur. Prior research has shown that entrepreneurial intentions are under the profound influences of intrinsic factors and extrinsic factors. On the one hand, entrepreneurial self-efficacy is one of the key psychological states that makes someone dare to initiate entrepreneurial activities. Institutional environment, on the other hand, can either enhance and hinder an individuals' entrepreneurial motivation by offering incentives or causing barriers. Little work has been done to understand how the institutional environment and entrepreneurial self-efficacy jointly affect company employees' intention to quit their job and start an enterprising career. By using hierarchical regression on a sample of 325 Indonesian company employees, this paper shows that the entrepreneurial cognition and entrepreneurial self-efficacy are positively related to employees' entrepreneurial intentions. Also, entrepreneurial self-efficacy strengthens the effect of normative Approval on entrepreneurial intention, whereas the regulatory Support from Government is detrimental to company employees' intention to start a new venture regardless the entrepreneurial self-efficacy is high or low.

scholarly journals Absence of X-chromosome dosage compensation in the primordial germ cells of Drosophila embryos

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryoma Ota ◽  
Makoto Hayashi ◽  
Shumpei Morita ◽  
Hiroki Miura ◽  
Satoru Kobayashi
Keyword(s):  
X Chromosome ◽  
Germ Cells ◽  
Dosage Compensation ◽  
Sex Chromosome ◽  
Primordial Germ Cells ◽  
Histone H4 ◽  
X Chromosomes ◽  
Essential Components ◽  
Msl Complex ◽  
Male Specific

AbstractDosage compensation is a mechanism that equalizes sex chromosome gene expression between the sexes. In Drosophila, individuals with two X chromosomes (XX) become female, whereas males have one X chromosome (XY). In males, dosage compensation of the X chromosome in the soma is achieved by five proteins and two non-coding RNAs, which assemble into the male-specific lethal (MSL) complex to upregulate X-linked genes twofold. By contrast, it remains unclear whether dosage compensation occurs in the germline. To address this issue, we performed transcriptome analysis of male and female primordial germ cells (PGCs). We found that the expression levels of X-linked genes were approximately twofold higher in female PGCs than in male PGCs. Acetylation of lysine residue 16 on histone H4 (H4K16ac), which is catalyzed by the MSL complex, was undetectable in these cells. In male PGCs, hyperactivation of X-linked genes and H4K16ac were induced by overexpression of the essential components of the MSL complex, which were expressed at very low levels in PGCs. Together, these findings indicate that failure of MSL complex formation results in the absence of X-chromosome dosage compensation in male PGCs.

scholarly journals Modulation of odour-guided behaviour in mosquitoes

2021 ◽  
Vol 383 (1) ◽  
pp. 195-206
Author(s):  
Sharon R. Hill ◽  
Rickard Ignell
Keyword(s):  
Functional Genomics ◽  
Life Stage ◽  
Blood Feeding ◽  
Model Systems ◽  
Extrinsic Factors ◽  
Intrinsic Factors ◽  
Host Seeking ◽  
Enhancing Resources ◽  
Maturation Age ◽  
Behavioural Repertoire

AbstractMosquitoes are emerging as model systems with which to study innate behaviours through neuroethology and functional genomics. Decades of work on these disease vectors have provided a solid behavioural framework describing the distinct repertoire of predominantly odour-mediated behaviours of female mosquitoes, and their dependence on life stage (intrinsic factors) and environmental cues (extrinsic factors). The purpose of this review is to provide an overview of how intrinsic factors, including adult maturation, age, nutritional status, and infection, affect the attraction to plants and feeding on plant fluids, host seeking, blood feeding, supplemental feeding behaviours, pre-oviposition behaviour, and oviposition in female mosquitoes. With the technological advancements in the recent two decades, we have gained a better understanding of which volatile organic compounds are used by mosquitoes to recognise and discriminate among various fitness-enhancing resources, and characterised their neural and molecular correlates. In this review, we present the state of the art of the peripheral olfactory system as described by the neural physiology, functional genomics, and genetics underlying the demonstrated changes in the behavioural repertoire in female mosquitoes. The review is meant as a summary introduction to the current conceptual thinking in the field.

scholarly journals Landscape Characteristics Based on Effectiveness of Wildlife Crossing Structures in South Korea

2021 ◽  
Vol 13 (2) ◽  
pp. 675
Author(s):  
Hyunjin Seo ◽  
Chulhyun Choi ◽  
Kyeongjun Lee ◽  
Donggul Woo
Keyword(s):  
Landscape Management ◽  
Spatial Pattern Analysis ◽  
Extrinsic Factors ◽  
Intrinsic Factors ◽  
Landscape Characteristics ◽  
Crossing Structures ◽  
Significant Difference ◽  
Management Plans ◽  
Wildlife Crossing Structures ◽  
Surrounding Landscape

Roads are notable and responsible for the loss of biodiversity and disruption of wildlife habitats connectivity. Wildlife crossing structures (WCS) help wildlife move between habitats by connecting fragmented habitats. Their effectiveness is affected by various factors. Here, to identify methods for improving the effectiveness of wildlife crossing structures, we controlled the effect of intrinsic factors, such as size, that are difficult to improve in an already installed area, and then, evaluated the differences in extrinsic factors using 12 landscape characteristics. Our results show that 18 wildlife crossing structures were selected with propensity-score (PS) matching method. The surrounding landscape characteristics differed between high-effectiveness wildlife crossing structures and low-effectiveness wildlife crossing structures. Particularly, there was a significant difference between the ‘statutory protected area’ and the ‘edge’ index of the morphological spatial pattern analysis among the landscape characteristic variables derived within 1 km2 of wildlife crossing structures. We empirically demonstrate that characteristics around highly effective WCS, statutory protected areas are widely distributed, and the ratio of edge of MSPA is low (within 1 km2). Therefore, an important outcome of our research is the demonstration that management of WCS itself is important, but conservation of surrounding habitats and landscape management plans are also significant.

Foraging behavior and predation success of the sand viper (Cerastes vipera)

2009 ◽  
Vol 87 (6) ◽  
pp. 520-528 ◽  
Author(s):  
Aziz Subach ◽  
Inon Scharf ◽  
Ofer Ovadia
Keyword(s):  
Length Ratio ◽  
Annual Rainfall ◽  
Activity Levels ◽  
Extrinsic Factors ◽  
Hunger Level ◽  
Intrinsic Factors ◽  
Thermal Range ◽  
Capture Success ◽  
Study Sites ◽  
Consequent Increase

Activity levels and foraging success of ectotherms are dependent both on extrinsic factors (e.g., ambient temperature) and intrinsic factors (e.g., hunger level). We focus here on activity and foraging of sand vipers ( Cerastes vipera (L., 1758)) (Squamata: Viperidae) in the northwestern Negev desert of Israel. Viper activity is bounded by a specific thermal range, but within this range, temperature does not affect the distance moved. Movement distances are, however, positively correlated with relative humidity. The capture success of lizards, the main prey of this viper, is strongly related both to movement distances of the snake and to the number of the lizard burrows scanned. Body size and shape have a direct effect on the number of burrows scanned and on the number of lizards captured. The increase in capture success with size is probably due to the consequent increase in the range of prey items the sand viper can subdue or handle. Vipers are larger and have a higher mass to length ratio in one of the three study sites, characterized by higher mean annual rainfall and vegetation cover. Finally, females tend to have a higher mass to length ratio than males, which may provide some space within the female body for reproductive materials such as eggs.

scholarly journals Conserved and divergent patterns of expression of DAZL, VASA and OCT4 in the germ cells of the human fetal ovary and testis

2007 ◽  
Vol 7 (1) ◽  
pp. 136 ◽  
Author(s):  
Richard A Anderson ◽  
Norma Fulton ◽  
Gillian Cowan ◽  
Shona Coutts ◽  
Philippa TK Saunders
Keyword(s):  
Germ Cells ◽  
Fetal Ovary

Maternal care and environmental enrichment influences on serotonin knockout mice with implications for a gene x stress model of autism

2019 ◽  
Author(s):  
◽  
Briana M. Kille
Keyword(s):  
Serotonin Transporter ◽  
Maternal Care ◽  
Environmental Enrichment ◽  
Environmental Influence ◽  
Repetitive Behavior ◽  
Critical Time ◽  
University Of Missouri ◽  
Time Period ◽  
Maternal Genotype ◽  
The University

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Previous research has shown a genetic variant in the serotonin transporter gene (Slc6a4) can increase the severity of a person's reaction to stress. This variant interacts with environmental stressors resulting in poorer health outcomes. Previous studies have also found that stressing pregnant mothers who carry the variant can result in an increased likelihood of autism diagnosis for the child. This maternal genotype x prenatal stress interaction has been modeled in the serotonin transporter knockout (SERT KO) mouse--dams genetically modified to mimic humans carrying the short allele were stressed during pregnancy resulting in offspring showing altered social behavior, repetitive behavior, and anxiety behavior. The first study included in this dissertation attempted to replicate this model while using a foster dam paradigm to avoid potential maternal care confounds. Surprisingly, the results showed that equalizing maternal care equalized several group differences in behavior. It is theorized that this is due to elimination of the neonatal insult from poor maternal care that would correspond to a human prenatal insult during a previously identified critical time period. The second study explored the potential effects environmentally enriched home cages on anxiety like behaviors of SERT KO mice. The study showed that all animals, regardless of genotype, showed fewer anxiety like behaviors in the open field assay. Together, these studies expand on our understanding of environmental influence on SERT KO mice used in translational studies.

Individual Variation in the Strength of Territory Defense in Male Song Sparrows: Correlates of Age, Territory Tenure, and Neighbor Aggressiveness

Behaviour ◽  
2004 ◽  
Vol 141 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Jeremy Hyman ◽  
Melissa Hughes ◽  
Stephen Nowicki ◽  
William Searcy
Keyword(s):  
Individual Differences ◽  
Reproductive Success ◽  
Extrinsic Factors ◽  
Territory Defense ◽  
Intrinsic Factors ◽  
Territorial Aggression ◽  
Male Song ◽  
Song Sparrows ◽  
Territory Owner ◽  
Older Males

AbstractIn many species, the ability to defend a territory is essential for a male to obtain any reproductive success at all, and even among territorial individuals, variation in the strength of territory defense could have a significant impact on how much reproductive success is obtained. Previous studies have documented consistent individual differences in the vigor with which male song sparrows (Melospiza melodia) defend their territories, as measured by the strength of their reactions to territorial intrusions simulated through song playback. Variation in the strength of defense could reflect intrinsic differences among individuals in their resource holding potential (RHP), or variation in extrinsic factors. In this study, we examined whether variation in the strength of territory defense corresponds to differences in intrinsic factors such as the age or experience of the territory owner, the extrinsic factor of the level of aggression shown by neighbours, or both. Results indicate that males that previously held territories on the study site, regardless of whether they were holding the same territory as the previous year, show higher levels of territory defense than males that are new to the study site, and, assuming that returning males are older males, suggest that age is more important than experience on a specific territory in determining strength of territory defense. In addition, we found evidence that males with high levels of territorial aggression tend to be spatially clustered. The pattern observed suggests that a combination of intrinsic and extrinsic factors contribute to the expression of individual differences in territorial aggression.

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