Search results for "Sexual differentiation"
showing 10 items of 14 documents
Maternal effects in quail and zebra finches: behavior and hormones.
2013
8 pages; International audience; Maternal effects are influences of parents on offspring phenotype occurring through pathways other than inherited DNA. In birds, two important routes for such transmission are parental behavior and non-DNA egg constituents such as yolk hormones. Offspring traits subject to parental effects include behavior and endocrine function. Research from the Adkins-Regan lab has used three avian species to investigate maternal effects related to hormones and behavior. Experiments with chickens and Japanese quail have shown that maternal sex steroids can influence sex determination to produce biased offspring sex ratios. Because all birds have a ZZ/ZW chromosomal sex de…
Gonadal sexual differentiation of European sea bass (Dicentrarchus labrax, L. 1758) of fingerlings in different size classes
2016
This report describes a study of the gonad differentiation in fingerlings of European sea bass (Dicentrarchus labrax) belonging to different size groups. Fishes were divided into four groups according to their weight: Group 1 (4.5 ± 0.7 g), Group 2 (9.2 ± 0.8 g), Group 3 (14.8 ± 1.8 g), and Group 4 (21.8 ± 2.3 g). In all groups, low percentages of undifferentiated or early sexually differentiated fish were found. Higher percentages of fully differentiated ovaries were found in Groups 1 and 3. Fully differentiated testes occurred in 90% of Group 4. Ninety percent of fish in Group 2 had gonads with intratesticular oocytes. This highlights the occurrence of intersexual cases and suggests that …
The maternal hormone in the male brain: Sexually dimorphic distribution of prolactin signalling in the mouse brain.
2018
Research of the central actions of prolactin is highly focused on females, but this hormone has also documented roles in male physiology and behaviour. Here, we provide the first description of the pattern of prolactin-derived signalling in the male mouse brain, employing the immunostaining of phosphorylated signal transducer and activator of transcription 5 (pSTAT5) after exogenous prolactin administration. Next, we explore possible sexually dimorphic differences by comparing pSTAT5 immunoreactivity in prolactin-supplemented males and females. We also assess the role of testosterone in the regulation of central prolactin signalling in males by comparing intact with castrated prolactin-supp…
Heterochronic differentiation of sexual dimorphs among Jurassic ammonite species
1997
Ontogenetic and then heterochronic approaches are used here to analyze sexual differentiation within two well-known Jurassic dimorphic species. This analysis compares two ways of determining the relative biological age of ammonites, one using size (diameter) and the other the number of septa as a proxy of age. The shape standard is established from factor analysis of morphological and growth parameters. Size-age-shape relationships are analyzed on the basis of a new heterochronic representation. When diameter is used as a proxy of age, microconch morphs are globally considered to be progenetic compared with macroconch morphs. When size and age are determined separately and shape is included…
Case of unilateral wing formation in the female of the glowwormLampyris noctiluca
2003
On July 27, 1999, the first author found a unilaterally winged adult glowworm in a park in the city of Mainz. Except for the wings on the left side, the specimen exhibited female characteristics that extended to external sexual appendages, the lantern and the gonads. The internal organization showed some remarkable differences between right (wingless) and left (winged) side. The right ovary contained three times more mature eggs than the left side and the volume of the corpus allatum of this side was about one-third larger than that of the left side. This suggests that aptery and egg maturation are affected by corpus allatum activity, i.e., juvenile hormone production. The findings do not s…
Detection of a synthetic sex steroid in the American crocodile (Crocodylus acutus): Evidence for a novel environmental androgen
2017
Endocrine-disrupting contaminants (EDC's) are well known to alter sexual differentiation among vertebrates via estrogenic effects during development, particularly in organisms characterized by temperature-dependent sex determination. However, substances producing androgenic effects typically lack potency when tested in laboratory settings and are virtually unstudied in field settings. Here, we assay levels of a synthetic androgen, 17a-methyltestosterone (MT), in a heavily male-biased population of American crocodiles in the Tempisque River Basin of Costa Rica based on the recent hypothesis that this chemical is an EDC in developing crocodilian embryos. The presence of MT was documented in a…
Intralocus sexual conflict for fitness: sexually antagonistic alleles for testosterone
2011
Intralocus sexual conflict occurs when a trait encoded by the same genetic locus in the two sexes has different optima in males and females. Such conflict is widespread across taxa, however, the shared phenotypic traits that mediate the conflict are largely unknown. We examined whether the sex hormone, testosterone (T), that controls sexual differentiation, contributes to sexually antagonistic fitness variation in the bank vole, Myodes glareolus . We compared (opposite-sex) sibling reproductive fitness in the bank vole after creating divergent selection lines for T. This study shows that selection for T was differentially associated with son versus daughter reproductive success, causing a …
Sex-related effects in the superhydrophobic properties of damselfly wings in young and old Calopteryx splendens.
2013
Numerous sex-related morphological adaptations are connected to reproductive behavior in animals. For example, females of some insect species can submerge during oviposition, which may lead to sex-related adaptations in the hydrophobicity (water-repellency) due to specialization of certain morphological structures. On the other hand, ageing can cause changes in hydrophobicity of the surface, because the morphological structures can wear with age. Here, we investigated sex-and age-related differences in wing hydrophobicity and in morphology (spine density, wax cover characteristics, size of females' pseudopterostigma) potentially related to hydrophobicity of Calopteryx splendens damselflies.…
No evidence of androgenic hormone from the testes of the glowworm, Lampyris noctiluca.
2005
The widely accepted concept, stating that insects have no true sex hormones, and that primary as well as secondary sex characteristics are controlled by the genetic inventory of each single cell, is challenged by the report of Naisse, J. [1966a. Controle endocrinien de la differenciation sexuelle chez l'Insecte Lampyris noctiluca (Coleoptere Malacoderme Lampyride). I. Role androgene des testicules, Arch. Biol. Liege, 77, 139-201] on the discovery of an androgenic hormone in the glowworm, Lampyris noctiluca. This case is of special interest, since it may point to an ancestral mode of sex differentiation in arthropods, considering that androgenic hormones have been discovered and characterize…
Effects of feminizing microsporidia on the masculinizing function of the androgenic gland in Gammarus duebeni
2013
Feminizing parasites enhance their vertical transmission to the host offspring by converting genetic male hosts into phenotypic females. Crustacea are the only invertebrates where sexual differentiation is controlled by a specialised endocrine organ, the androgenic gland, rather than by the gonads. We showed that a feminizing microsporidian Microsporidium sp. inhibits androgenic gland differentiation. We investigated the effect of Microsporidium sp. and a second feminizing microsporidium, Nosema granulosis, on the masculinizing function of the androgenic gland in Gammarus duebeni. Androgenic gland implants had a masculinizing effect on the sexual characteristics and sexual behaviour of reci…