Neurobiology of Reproduction in Molluscs

2017 ◽  
pp. 614-662 ◽  
Author(s):  
Carlo Di Cristo ◽  
Joris M. Koene
Keyword(s):  
Degrees Of Freedom ◽  
Sexual System ◽  
Female Reproduction ◽  
Male And Female ◽  
Neuroendocrine Control ◽  
Proximate Mechanism ◽  
Sexual Systems ◽  
Similarities And Differences ◽  
Evolutionary Pathways ◽  
Reproductive Processes

Ultimately, the outcome of successful reproduction—fertilization of eggs and production of surviving offspring—is relevant for how these processes evolve. However, a thorough understanding of the underlying, proximate mechanism is essential for interpreting evolutionary outcomes properly. Comparing neuroendocrine processes across different species, with different sexual systems, is one way of uncovering similarities and differences in regulation of their reproductive processes. Here, we provide an overview of the neuroendocrine control of reproductive processes in molluscs. In doing so, we also illustrate that it is relevant to consider the sexual system when addressing the neurobiology of reproduction. For example, our overview indicates that hermaphroditic molluscs seem to regulate their male and female reproduction via largely nonoverlapping neurobiological wiring and neuroendocrine substances, whereas this is not necessarily the case for separate-sexed molluscs. Clearly, this has implications for the available degrees of freedom within sexual systems in terms of evolutionary pathways.

scholarly journals Programming of the reproductive axis by hormonal and genetic manipulation in mice

Reproduction ◽  
2018 ◽  
Author(s):  
Susana B Rulli ◽  
María Julia Cambiasso ◽  
Laura D Ratner
Keyword(s):  
Sex Chromosome ◽  
Genetic Manipulation ◽  
Sex Differentiation ◽  
Reproductive Function ◽  
Gonadal Steroids ◽  
Critical Periods ◽  
Female Reproduction ◽  
Control Male ◽  
Male And Female ◽  
The Brain

In mammals, the reproductive function is controlled by the hypothalamic-pituitary-gonadal axis. During development, mechanisms mediated by gonadal steroids exert an imprinting at the hypothalamic-pituitary level, by establishing sexual differences in the circuits that control male and female reproduction. In rodents, the testicular production of androgens increases drastically during the fetal/neonatal stage. This process is essential for the masculinization of the reproductive tract, genitals and brain. The conversion of androgens to estrogens in the brain is crucial for the male sexual differentiation and behavior. Conversely, feminization of the brain occurs in the absence of high levels of gonadal steroids during the perinatal period in females. Potential genetic contribution to the differentiation of brain cells through direct effects of genes located on sex chromosomes is also relevant. In this review, we will focus on the phenotypic alterations that occur on the hypothalamic-pituitary-gonadal axis of transgenic mice with persistently elevated expression of the human chorionic gonadotropin hormone (hCG). Excess of endogenously synthesized gonadal steroids due to a constant hCG stimulation is able to disrupt the developmental programming of the hypothalamic-pituitary axis in both transgenic males and females. Locally produced estrogens by the hypothalamic aromatase might play a key role in the phenotype of these mice. The “four core genotypes” mouse model demonstrated a potential influence of sex chromosome genes in brain masculinization before critical periods of sex differentiation. Thus, hormonal and genetic factors interact to regulate the local production of the neurosteroids necessary for the programming of the male and female reproductive function.

Male and Female Reproduction in Penaeid Shrimps

2008 ◽  
pp. 427-455
Author(s):  
Shmulik Parnes ◽  
Shaul Raviv ◽  
Amir Sagi
Keyword(s):  
Female Reproduction ◽  
Male And Female ◽  
Penaeid Shrimps

Morphological and functional response to injury to the external urethral sphincter - similarities and differences between male and female rats

2014 ◽  
Vol 35 (3) ◽  
pp. 371-376
Author(s):  
Scheila F. C. Nascimento ◽  
Ana Paula S. Bispo ◽  
Katia Ramos Leite ◽  
Helio Plapler ◽  
Claudius Füllhase ◽  
...  
Keyword(s):  
Functional Response ◽  
Female Rats ◽  
Urethral Sphincter ◽  
External Urethral Sphincter ◽  
Male And Female ◽  
Male And Female Rats ◽  
Similarities And Differences

Masculine and feminine in a melting pot – A gendered perspective on substance abuse

2003 ◽  
Vol 20 (1) ◽  
pp. 5-19
Author(s):  
Karin Trulsson
Keyword(s):  
Substance Abuse ◽  
Residential Treatment ◽  
Role Model ◽  
Suicide Attempts ◽  
Melting Pot ◽  
Male And Female ◽  
Female Role Model ◽  
The Social ◽  
Similarities And Differences ◽  
Division Of Work

The purpose of this article is to describe similarities and differences between female and male substance abuse and to discuss what implications these may have or should have for treatment. The article mainly draws on qualitative social research. The material consists of a theoretic overview of Scandinavian empirical interdisciplinary research on male and female substance abuse. The focus is on marginalised abusers, who are the main targets of society's measures and interventions. The theoretical framework is built mainly on gender studies, but such terms as class and culture are also used. The analysis of the similarities and differences between male and female substance abuse is based on the concepts of gender contract, social ideal, gendered division of work, and socialisation (Hirdman 1988). As far as drugs are concerned, the social ideal is zero tolerance for both genders. In contrast, controlled use of alcohol is tolerated, while the social norm is that male drinking is more acceptable than female drinking. The fact that female drinking is considered more condemnable than male drinking contributes to the worse self-esteem and the higher prevalence of depression and suicide attempts among women. The requirements of “respectability”, care duties and sexual control that are imposed on women from the working- class perspective (Skeggs 1997) increase the demands made of women, whose substance abuse also tends to be associated with a greater sexual availability. The gendered division of work traditionally gives the main responsibility for home and children to the woman. In general, women to a greater extent than men make efforts to fulfil this ideal by stopping or controlling their substance abuse during pregnancy and the time they spend with children. However, there are also examples of both ‘oppositional’ men who shoulder the main responsibility for home and children and of ‘emancipated’ women who hand over the responsibility to the man and other close persons and in the case of which drug abuse can be seen as a part of the emancipation process. It has been possible to compensate for inadequate socialisation, i.e. the teen-age years that many women have “lost” due to substance abuse, by residential treatment of addicted women. Research findings indicate that abusers with poor treatment outcomes in residential treatment that is mainly given to men call for the same kind of treatment as that given to women. It has also been shown that the treatment of women does not meet the needs of women who have rejected the traditional female role model. Both new masculinities (Connell 1996) and new feminities emerge in a society in which masculine and feminine are in a melting pot. This involves a risk that men and women who do not adapt to the traditional role model become losers with regard to substance abuse services in the same way as the most marginalised abusers. Less attention is also being devoted to them in substance abuse research. Accordingly, research from both the gender and the class perspective could open up new perspectives and paths for the treatment of substance abusers.

scholarly journals Outbreeding and inbreeding strategies in herbaceous-shrubby communities in the Venezuelan Gran Sabana Plateau

AoB Plants ◽  
2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Nelson Ramírez ◽  
Omaira Hokche
Keyword(s):  
Plant Species ◽  
Carbon Metabolism ◽  
Life Form ◽  
Sex Expression ◽  
Perennial Herb ◽  
Sexual System ◽  
Dioecious Species ◽  
Successional Stage ◽  
Sexual Systems ◽  
Perennial Herbs

Abstract Breeding system, sexual system, temporal variation in sex expression and herkogamy were evaluated in seven herbaceous-shrubby communities from the Gran Sabana Plateau, Venezuela. This analysis was conducted considering the life form, substrate type, succulence, carbon metabolism, nutritional relation, successional stage, pollination system specificity and endemism of plant species. Of the 348 plant species studied, 73.8 % were hermaphrodite, 16.9 % were monoecious and 9.2 % were dioecious. Plant sexual systems such as dichogamy and herkogamy were associated with life form, nutritional relations, carbon metabolism and pollination systems. Most species were adichogamous, followed by protandrous and protogynous. Protandry was high for perennial herbs, annual herbs and trees, and protogyny was most frequent in perennial herbs. Protandrous and protogynous species were frequently anemophilous. Herkogamy was higher than non-herkogamy. Herkogamy was higher for trees, shrubs and liana; higher in monophilous and lower in anemophilous species. Most of the hermaphrodites were herkogamous and adichogamous species. In contrast, monoecy were commonly perennial herb and dichogamous species and frequently associated with anemophily. Dioecious species were trees and shrubs and with polyphilous pollination. Dioecy was the most frequent sexual system for endemic species. Hermaphrodite species were similarly distributed across plant communities. Monoecy was slightly higher for savanna and fallow than the other communities, and dioecy was higher for shrublands and secondary bushland. Most plant species were non-agamospermous, non-spontaneous self-pollinated and xenogamous. Partially self-incompatible dominated, followed by self-incompatible, partially cross-incompatible and the lowest frequency corresponded to cross-incompatible species. All these results are discussed in the context of evolutionary and ecological trends.

Sign in / Sign up

Export Citation Format

Share Document