Aspects Of Sexual Dimorphism Research Articles

Environmental experiences shape sexually dimorphic neuronal circuits and behaviour.

Dimorphic traits, shaped by both natural and sexual selection, ensure optimal fitness and survival of the organism. This includes neuronal circuits that are largely affected by different experiences and environmental conditions. Recent evidence suggests that sexual dimorphism of neuronal circuits extends to different levels such as neuronal activity, connectivity and molecular topography that manifest in response to various experiences, including chemical exposures, starvation and stress. In this review, we propose some common principles that govern experience-dependent sexually dimorphic circuits in both vertebrate and invertebrate organisms. While sexually dimorphic neuronal circuits are predetermined, they have to maintain a certain level of fluidity to be adaptive to different experiences. The first layer of dimorphism is at the level of the neuronal circuit, which appears to be dictated by sex-biased transcription factors. This could subsequently lead to differences in the second layer of regulation namely connectivity and synaptic properties. The third regulator of experience-dependent responses is the receptor level, where dimorphic expression patterns determine the primary sensory encoding. We also highlight missing pieces in this field and propose future directions that can shed light onto novel aspects of sexual dimorphism with potential benefits to sex-specific therapeutic approaches. Thus, sexual identity and experience simultaneously determine behaviours that ultimately result in the maximal survival success.

Are there any gender differences in pain perception? Clinical and experimental studies in oncology

The review considers and analyzes scientific literature on gender differences in the incidence of pain syndromes, perception of clinical pain, including that in cancer patients and in experimental oncology. The literature highlights theoretical basis, some biological mechanisms and practical results associated with gender differences. Chronic pain no longer performs a protective function and is not biologically appropriate. The review presents results of experimental studies demonstrating the important role of sex hormones and regulatory systems of a living organism in the mechanisms of development, distribution and perception of pain. Some aspects of sexual dimorphism in the processes of nociception and antinociception are covered. We present the data on the causes of chronic pain syndrome and its perception in cancer patients of both sexes indicating genetically determined sexual reactivity of the body which causes an imbalance in the function of peripheral nervous system and CNS under the influence of prolonged permanent pain in a living organism. Various pain effects have been shown to cause changes in the main types of metabolism, mobilization of adaptive metabolic mechanisms, and tissue damage. Conclusions. The high prevalence of chronic pain in both women and men with cancer, heavy humanitarian and social and economic burden explains a significant increase in fundamental and clinical research in this direction.
 
 

Вариабельность одонтометрических показателей в аспекте полового диморфизма

Вариабельность одонтометрических показателей в аспекте полового диморфизма

Wing morphometrics of Aedes (Ochlerotatus) albifasciatus (Macquart, 1838) (Diptera: Culicidae) from different climatic regions of Argentina

BackgroundGene flow restrictions between populations of Aedes albifasciatus, the vector of Western equine encephalitis and Dirophilaria immitis, have been described in the central region of Argentina. Genetic and eco-physiological variations usually result in local forms reflecting the climatic regions. Mosquito wings and their different parts have ecological functions in flight and communication. Therefore, wing shape could be considered an aspect of sexual dimorphism, and its eco-physiological responses can be expressed as morphological changes induced by the environment.MethodsTo compare the geographical and sexual variations with respect to wing shape and size in two Ae. albifasciatus populations from contrasting climates of Argentina (temperate: Buenos Aires, and the arid steppe of Patagonia: Sarmiento), the wings of adults reared in thermal trays at different constant temperatures (10–29 °C) were analyzed.ResultsThe wing size of Ae. albifasciatus showed inverse linear relationships with the rearing thermal condition and higher slope for Buenos Aires. In the cool range (10–17 °C), geographical size variations responded to the converse Bergmann’s rule, where Buenos Aires individuals were larger than those from Sarmiento. Sexual shape dimorphism occurred in both populations while geographical variation in shape was observed in both sexes.ConclusionsBuenos Aires individuals showed greater response sensitivity with respect to the size-temperature relation than those from Sarmiento. The converse Bergmann’s rule in size variation could be due to a higher development rate in Sarmiento to produce more cohorts in the limited favorable season. The shape could be more relevant with respect to the size in the study of population structures due to the size being more liable to vary due to changes in the environment. The geographical variations with respect to morphology could be favored by the isolation between populations and adaptations to the environmental conditions. Our results demonstrate that the shape and size of wing provide useful phenotypic information for studies related to sexual and environmental adaptations.

Allometry and Sexual Dimorphism in the Human Pelvis.

Sexual dimorphism in the human pelvis has evolved in response to several jointly acting selection regimes that result from the pelvis' multiple roles in locomotion and childbirth, among others. Because human males are, on average, taller than females, some aspects of sexual dimorphism in pelvis shape might result from allometry, the association between stature and pelvis shape across individuals. In this study, they aimed to disentangle and quantify the two components contributing to pelvic sex differences: the allometric component, which emerges as a consequence of dimorphism in stature, and the remaining non-allometric sexual dimorphism component. A geometric morphometric analysis of a dense set of 3D landmarks, measured on 99 female and male adult individuals was conducted. While pelvis size was similar in both sexes, the average differences in pelvis shape reflected the well-documented pattern of sexual dimorphism. There was almost no overlap between females and males in shape space. Their analysis showed that pelvis size and shape were similarly associated with stature in both sexes. It was found that dimorphism in the height-to-width ratio of the pelvis and in the orientation of the iliac blades was largely allometric, whereas dimorphism in the subpubic angle and the relative size and distance of the acetabula was largely non-allometric. It was concluded that, in contrast to the overall pelvic proportions, sexual dimorphism in the birth-relevant pelvic dimensions was mainly of non-allometric origin and was presumably mediated via steroid hormone secretion during puberty. Anat Rec, 300:698-705, 2017. © 2017 Wiley Periodicals, Inc.

Physical education of the students: traditions, trends of development

1. Grets, I.A. (2012), Record sporting achievements of women in aspect of sexual dimorphism, dissertation, St. Petersburg. 2. Ilyin, E.P. (2008), Differential psychophysiology of the man and woman, Labyrinth, St. Petersburg. 3. Iordanskaya, F.A. (2012), the Man and the woman in an elite sport (a problem of sexual dimorphism): monograph, Soviet sports, Moscow. 4. Lubysheva, L.I. (2000), “Woman and sports: social aspect”, Theory and practice of physical culture, No. 6, pp. 13-16. 5. Stambulova, N.B. (1999), Psychology of sports career, dissertation, St. Petersburg. 6. Tristan, V.G. (2013), Psychophysiological bases of female sports. Manual, publishing house Educational and sports center of Moskomsport, Moscow. 7. Hudadov, N.A. (1968), Psychological training of the boxer, Physical culture and sports, Moscow. Контактная информация: V.V.Lisitsyn@yandex.ru

Reduction of sexual dimorphism in stream-resident forms of three-spined stickleback Gasterosteus aculeatus.

Sexual dimorphism in geometric body shape and external morphology was compared between marine and stream-resident forms of three-spined stickleback Gasterosteus aculeatus collected from North America and Japan. Some aspects of sexual dimorphism were shared between ecotypes: males had larger heads than females with no significant effect of ecotype on the magnitude of sexual dimorphism. By contrast, a significant sex-by-ecotype interaction was found for body depth. Males tended to have deeper bodies than females in both forms, but the magnitude of sexual dimorphism was reduced in stream-resident forms. Although females were generally larger in standard length and had larger pelvic girdles, significant sexual dimorphism in these traits was not consistently found across populations or ecotypes. These results suggest that some aspects of sexual dimorphism were shared between ecotypes, while others were unique to each population. The results further suggest that ecology may influence the evolution of sexual dimorphism in some external morphological traits, such as body depth.

Meiotic Checkpoints: Repair or Removal?

Defects in meiosis can produce different checkpoint responses in female and male animals, suggesting that meiotic checkpoints exhibit sexual dimorphism. A recent study in Caenorhabditis elegans indicates that meiotic checkpoint activation is similar between the sexes and the primary difference lies in the downstream consequences.

Sex of the cell dictates its response: differential gene expression and sensitivity to cell death inducing stress in male and female cells

Sexual dimorphisms are typically attributed to the hormonal differences arising once sex differentiation has occurred. However, in some sexually dimorphic diseases that differ in frequency but not severity, the differences cannot be logically connected to the sex hormones. Therefore, we asked whether any aspect of sexual dimorphism could be attributed to chromosomal rather than hormonal differences. Cells taken from mice at d 10.5 postconception (PC) before sexual differentiation, at d 17.5 PC after the first embryonic assertion of sexual hormones, and at postnatal day 17 (puberty) were cultured and exposed to 400 microM ethanol or 20 microM camptothecin or to infection with influenza A virus (multiplicity of infection of 5). The results showed that untreated male and female cells of the same age grew at similar rates and manifested similar morphology. However, they responded differently to the applied stressors, even before the production of fetal sex hormones. Furthermore, microarray and qPCR analyses of the whole 10.5 PC embryos also revealed differences in gene expression between male and female tissues. Likewise, the exposure of cells isolated from fetuses and adolescent mice to the stressors and/or sex hormones yielded expression patterns that reflected chromosomal sex, with ethanol feminizing male cells and masculinizing female cells. We conclude that cells differ innately according to sex irrespective of their history of exposure to sex hormones. These differences may have consequences in the course of sexually dimorphic diseases and their therapy.

Not all germ cells are created equal: Aspects of sexual dimorphism in mammalian meiosis

The study of mammalian meiosis is complicated by the timing of meiotic events in females and by the intermingling of meiotic sub-stages with somatic cells in the gonad of both sexes. In addition, studies of mouse mutants for different meiotic regulators have revealed significant differences in the stringency of meiotic events in males versus females. This sexual dimorphism implies that the processes of recombination and homologous chromosome pairing, while being controlled by similar genetic pathways, are subject to different levels of checkpoint control in males and females. This review is focused on the emerging picture of sexual dimorphism exhibited by mammalian germ cells using evidence from the broad range of meiotic mutants now available in the mouse. Many of these mouse mutants display distinct differences in meiotic progression and/or dysfunction in males versus females, and their continued study will allow us to understand the molecular basis for the sex-specific differences observed during prophase I progression.

REPRODUCTIVE BIOLOGY OF A SOLITARY SUBTERRANEAN BATHYERGID RODENT, THE SILVERY MOLE-RAT (HELIOPHOBIUS ARGENTEOCINEREUS)

Aspects of sexual dimorphism, reproduction, postnatal development, and seasonality of breeding in a solitary bathyergid rodent, the silvery mole-rat ( Heliophobius argenteocinereus), as based on a field study in Malawi and on a study of animals kept in a laboratory, are reported here for the 1st time. Sex ratio in all animals ( n 5 173) did not differ from equality. Wild-captured males were heavier (190 6 58 g) than females (162 6 47 g). Mating took place during the cold and dry season (April‐July), and births occurred during the hot and dry season (August‐October). Mean gestation length was 95 6 8.5 days, and mean litter size was 3.2 6 0.9. The altricial neonates weighed 12.8 6 2.3 g and opened their eyes about 14 days after birth. Postnatal growth rate was slow with a mean growth constant of 0.01 and a mean maximum growth rate of 0.53 g/day. The reproductive biology of H. argenteocinereus reveals characteristics of both social and solitary bathyergids. Thus, parameters believed so far to be typical of social mole-rats, such as long pregnancy and slow postnatal development, can be found in solitary silvery mole-rats as well, calling for a reevaluation of the role of reproductive biology in shaping social life.

HOW TO COMPENSATE FOR COSTLY SEXUALLY SELECTED TAILS: THE ORIGIN OF SEXUALLY DIMORPHIC WINGS IN LONG-TAILED BIRDS.

Recent work on birds suggests that certain morphological differences between the sexes may have evolved as an indirect consequence of sexual selection because they offset the cost of bearing extravagant ornaments used for fighting or mate attraction. For example, long-tailed male sunbirds and widowbirds also have longer wings than females, perhaps to compensate for the aerodynamic costs of tail elaboration. We used comparative data from 57 species to investigate whether this link between sexual dimorphism in wing and tail length is widespread among long-tailed birds. We found that within long-tailed families, variation in the extent of tail dimorphism was associated with corresponding variation in wing dimorphism. One nonfunctional explanation of this result is simply that the growth of wings and tails is controlled by a common developmental mechanism, such that long-tailed individuals inevitably grow long wings as well. However, this hypothesis cannot account for a second pattern in our data set: as predicted by aerodynamic theory, we found that, comparing across long-tailed families, sexual dimorphism in wing length varied with tail shape as well as with sex differences in tail length. Thus, wing dimorphism was generally greater in species with aerodynamically costly graduated tails than in birds with cheaper, streamer-shaped tails. This result was not caused by confounding phylogenetic effects, because it persisted when phylogeny was controlled for, using an independent comparisons method. Our findings therefore confirm that certain aspects of sexual dimorphism may sometimes have evolved through selection for traits that reduce the costs of elaborate sexually selected characters. We suggest that future work aimed at understanding sexual selection by investigating patterns of sexual dimorphism should attempt to differentiate between the direct and indirect consequences of sexual selection.

The Sebright bantam chicken and the genetic control of extraglandular aromatase.

I. Sexual Dimorphism in Feather Morphology NO ASPECT of sexual dimorphism is more striking or more variable among species than is the feathering pattern of birds. One such sexual difference involves the morphology of feathers. For example, in some birds the feathers of the male are longer and more deeply fringed than those of the female.1 Species in which such sexual differences are extreme include the lyre bird, the peacock, some types of hummingbird, and the domestic chicken (1). Owing to their accessibility, chickens have been the favored subjects for the study of relationships between gonadal function and feather structure, and it is customary to characterize the plumage of adult chickens as either henny or cocky (Fig. 1) (3). In the hen most feathers are short and straight and have a solid vane with many barbules and hence little fringing. In the rooster, in contrast, the neck hackle feathers, the feathers of the saddle (the median tail coverts), and the major tail coverts and great sickle feathers o...

Sexual dimorphism in the skull of minks Mustela vison, badgers Meles meles and otters Lutra lutra

Multiple-group principal component analysis and discriminant analysis were used to investigate the morphological differences between adult skulls of male and female minks, badgers and otters from Norway. The first principal component axis, calculated from the variance-covariance matrix of log-transformed data, was interpreted as a growth-free size axis in all three species, while the other components were interpreted as representing shape. Having largely separated size and shape variation, these two aspects of sexual dimorphism could be studied. The standardized component scores were subjected to an analysis of variance and discriminant analyses were performed on size-in and size-out data. Sexual dimorphism was disclosed on eight of the 12 components in minks and on seven of the 12 components in badgers and otters. In mink the multivariate differences were more due to size than to shape, whereas in badgers and otters most of the multivariate differences were due to shape, but the differences in size were also significant. The shape dimorphism was shown to be functionally related to jaw and neck muscles. The results were discussed in relation to recent theories to explain the evolutionary significance of sexual dimorphism in body size of mustelids. It was concluded that these theories do not fully explain the dimorphism found in the skulls of the moderately dimorphic badger and otter.

Harderian gland lipids of male and female golden hamsters

Abstract 1. 1. Cholesterol, fatty acid, alkyldiacylglycerol, phosphotidyl choline, phosphotidyl ethanolamine and an unidentified phospholipid were separated by thin-layer chromatography. 2. 2. Gas-liquid chromatography of the lipids showed that the predominant fatty acids in the female gland have chain lengths ranging from C16 to C20 while those of the male gland ranged from C10 to C20. 3. 3. The prevalence of C16:0 and C18:1 in the female contributes to an aspect of sexual dimorphism in the hamster Harderian gland not reported previously.

Ontogenetic aspects of sexual dimorphism and the primary immune response to sheep erythrocytes in hamsters from prepuberty through senescence.

Ontogeny of the primary response to sheep erythrocytes of age-matched groups of male and female hamsters was studied at various chronological ages ranging from prepuberty to senescence. Selected organs were likewise weighed upon sacrifice to obtain developmental patterns. Adrenal weights were higher in the male, and pituitary weights were higher in the female; for both organs typical dimorphism was demonstrable by 36 days. Spleen weight and index favored the female by 46 days. Immunological sex dimorphism first appeared in groups injected at 53 days and autopsied at 58 days and persisted through senescence. Sexual dimorphism of antibody-mediated immunity, previously shown to favor the female in both the primary and secondary immune responses, thus follows the dimorphism of total amount of splenic lymphoid tissue and occurs shortly after realization of sexual maturity in the male. These findings support our previous suggestion of the suppressive effect of androgens on the antibody-mediated immune responsiveness of the male hamster.

Notes on Sexual Dimorphism in Tail-Length in American Snakes

In a detailed analysis of certain aspects of sexual dimorphism in tail-length in snakes Klauber (1943:6) introduced a statistic called the of deSned as the difference between two means divided by half their sum. . Klauber used this hgure for comparing dimorphism in tail-length in different species and subspecies of snakes and noted (op. cit.:50-51): there is a rough correlationlong-tailed snakes do tend to have low sexual dimorphism and vice versa. In the short-tailed snakes the male sex organs would require a certain minimum space which would tend to increase dimorphism. On the other hand, the long-tailed snakes, in which the tails serve various useful purposes, such as for balance, propulsion, holding, or climbing, the necessity for the space for primary sex organs would obviously have a more incidental effect on tail length. The purposes of the present paper are to summarize additional data of the type given by Klauber and to add to his observations on the possible significance of the coefficient of divergence when applied to relative tail-length. Also, some unusual aspects of dimorphism in tail-length in the Texas Coral Snake (Alicrgrvx fGlviX5 tenere) are discussed.