Implications Of Sexual Dimorphism Research Articles

Phenotype and energy metabolism differ between osteoarthritic chondrocytes from male compared to female patients: Implications for sexual dimorphism in osteoarthritis development?

ObjectivesThe prevalence and severity of knee osteoarthritis (OA) are greater in females than males. The purpose of this study was to determine whether there is an underlying difference in the biology of OA chondrocytes between males and females. MethodsChondrocytes were obtained following knee arthroplasty from male and female patients with primary OA. Phenotype marker expression, glucose and fat consumption, and rates of glycolysis and oxidative phosphorylation were compared between females and males. RNAi was used to determine the consequences of differential expression of Sry-box transcription factor 9 (SOX9) and PGC1α between males and females. ResultsOA chondrocytes from male donors showed elevated RNA and protein levels of SOX9, elevated COL2A1 protein synthesis, higher glucose consumption, and higher usage of glycolysis compared to females. OA chondrocytes from females had higher PGC1α protein levels, higher fat consumption, and higher oxidative energy metabolism than males. Knockdown of SOX9 reduced expression of COL2A1 to a greater extent in male OA chondrocytes than females whereas knockdown of PGC1α reduced COL2A1 expression in females but not males. Expression of ACAN and the glycolytic enzyme PGK1 was also reduced in males but not females following SOX9 knockdown. ConclusionsOA chondrocyte phenotype and energy metabolism differ between males and females. Our results indicate transcriptional control of COL2A1 differs between the two. Differences in chondrocyte biology between males and females imply the underlying mechanisms involved in OA may also differ, highlighting the need to consider sex and gender when investigating pathogenesis and potential treatments for OA.

Covariation Between Body Size, Sacral Slope, and Pelvic Shape in Humans: Implications for Sexual Dimorphism

This study tests for a significant relationship between bony pelvic shape, body size, and sacral slope (SS), or the angled position of the sacrum within the pelvis. Typically, human males exhibit narrow pelves and narrow greater sciatic notches (GSNs) with shorter posterior aspects and posteriorly located apexes. Females typically exhibit wide pelves and wide GSNs with expanded posterior aspects that appear to contribute to spacious birth canals. Although these morphological differences are often attributed to obstetric selection, the proximate mechanisms responsible for pelvic dimorphism are unclear.I analyzed previously recorded pelvic shape data for 46 male and 52 female American white individuals aged 19–70 years from the Hamann‐Todd collection. Three‐dimensional landmark coordinate data for the left pelvis is stored in the Dryad repository (2015 PNAS 112:5655–5660). I began geometric morphometric analyses by estimating missing landmarks using thin‐plate spline interpolation in R Geomorph. After reflecting paired landmarks across the midplane to yield 125 total landmarks, I completed a Generalized Procrustes Analysis (GPA) of the entire symmetrized pelvis. SS is defined by the angle between a transverse plane and the first sacral cranial endplate. Body size is represented by recorded stature and body breadth of the first sacral vertebra (S1) as a proxy for body mass. Using both R Geomporph and Morpho, two‐block partial least squares analyses in the total, female, and male samples tested the relationship between a block comprised of stature, S1 body breadth, and SS, with each variable standardized by z‐score transformation, and a second block of 85 GPA‐aligned coordinates representing right and left coxal shape.In the total sample, coxal shape significantly covaries with SS and the body size variables (SA1 r‐pls: 0.718, p=0.001), with body size variables showing greater loading, or influence in the relationship compared to SS. As body size increases and SS decreases, the GSN exhibits a shorter posterior aspect, and the pelvis shows greater superoinferior expansion. Female coxal shape significantly covaries with SS and the body size variables (SA1 r‐pls: 0.579, p=0.036), with SS being the greatest loading on the first singular axis. Male coxal shape also significantly covaries with SS and the body size variables (SA1 r‐pls: 0.626, p=0.014 (Morpho)), but with S1 body breadth being the greatest loading on the first singular axis. In both the female and male analyses, as SS increases and body size decreases, the GSN exhibits a relatively expanded posterior aspect and the breadth between the left and right anterior superior iliac spines appears relatively greater. Among females, the pelvic inlet also appears relatively mediolaterally narrow with increased SS. Overall, results indicate that body size and SS relate to GSN shape and orientation of the coxal bones. SS affects how upper body mass is transmitted to the pelvis. This study therefore suggests that trunk biomechanical factors influence pelvic shape variation, including patterns of dimorphism.

Dopaminergic dynamics underlying sex-specific cocaine reward

Although both males and females become addicted to cocaine, females transition to addiction faster and experience greater difficulties remaining abstinent. We demonstrate an oestrous cycle-dependent mechanism controlling increased cocaine reward in females. During oestrus, ventral tegmental area (VTA) dopamine neuron activity is enhanced and drives post translational modifications at the dopamine transporter (DAT) to increase the ability of cocaine to inhibit its function, an effect mediated by estradiol. Female mice conditioned to associate cocaine with contextual cues during oestrus have enhanced mesolimbic responses to these cues in the absence of drug. Using chemogenetic approaches, we increase VTA activity to mechanistically link oestrous cycle-dependent enhancement of VTA firing to enhanced cocaine affinity at DAT and subsequent reward processing. These data have implications for sexual dimorphism in addiction vulnerability and define a mechanism by which cellular activity results in protein alterations that contribute to dysfunctional learning and reward processing.

Sex-Related Differences in Pulmonary Function following 6 Months of Cigarette Exposure: Implications for Sexual Dimorphism in Mild COPD.

Female smokers have increased risk of chronic obstructive pulmonary disease (COPD) compared with male smokers who have a similar history of cigarette smoke exposure. We have shown previously that chronic smoke exposure for 6 months leads to increased airway wall remodeling in female C57BL/6 mice compared with male C57BL/6 mice. These differences, however, were not evident in female ovariectomized mice exposed to cigarette smoke. Herein, we report on the pulmonary function test results from the flexiVent system, which was used to determine the potential functional consequences of the histologic changes observed in these mice. We found that tissue damping (G) was increased in female compared to male or ovariectomized female mice after smoke exposure. At low oscillating frequencies, complex input resistance (Zrs) and impedance (Xrs) of the respiratory system was increased and decreased, respectively, in female but not in male or ovariectomized female mice after smoke exposure. Quasistatic pressure-volume curves revealed a reduction in inspiratory capacity in female mice but not in male or ovariectomized female mice after smoke exposure. The remaining lung function measurements including quasistatic compliance were similar amongst all groups. This is the first study characterizing a sexual dimorphism in respiratory functional properties in a mouse model of COPD. These findings demonstrate that increased airway remodeling in female mice following chronic smoke exposure is associated with increased tissue resistance in the peripheral airways. These data may explain the importance of female sex hormones and the increased risk of airway disease in female smokers.

Size-selective fishing of Palaemon serratus (Decapoda, Palaemonidae) in Wales, UK: implications of sexual dimorphism and reproductive biology for fisheries management and conservation

The common prawn (Palaemon serratus) supports a small-scale but economically important seasonal static-gear fishery in Cardigan Bay, Wales (UK). Due to a lack of statutory obligation and scientific evidence, the fishery has operated to date without any harvest-control rules that afford protection from overfishing. In response to fluctuations in landings and in pursuit of increased economic returns for their catch, some members of the fishing industry have adopted a size-selective harvesting regime, which we evaluate here using baseline data. Monthly samples were obtained from fishers operating out of five ports between October 2013 and May 2015 (N = 4233). All prawn were sexed, weighed and measured, whilst the fecundity of females was estimated for 273 (44%) individuals. Peak spawning occurred during the spring and females were estimated to undergo a ‘puberty moult’ at a carapace length (CL) of 7.7 mm, whilst functional maturity was estimated at a CL of 9.9 mm. The sampled population exhibited sexual dimorphism, with females attaining a greater size than males. The current harvesting regime results in a sex bias in landings as even large mature males remained under the recruitment size to the fishery, unlike the large mature females. The temporal trend in sex-ratio indicates a continual decrease in the catchability of female prawn through the fishing season; however, whether this is caused by depletion via fishing mortality or migratory behaviour is yet to be resolved. Here, we provide a comprehensive baseline evaluation of population biology and discuss the implications of our findings for fisheries management.

Alternative mating tactics and male mating success in two species of fiddler crab

The use of alternative male mating tactics can determine the strength of sexual selection on male traits and have implications for sexual dimorphism. We examined size-based mating success in two species of fiddler crabs where males use each of two alternative tactics to obtain matings. InUca annulipes, larger males were more successful when using the primary mating tactic (burrow mating) but the full size range of males mated when using the secondary tactic (surface mating). InUca urvillei, both burrow and surface mating males were larger than the average sized male in the population. Standardised directional selection gradients indicated that selection on male size was stronger inU. urvilleithanU. annulipes, reflecting the differences between species in male mating success. Our results also showed that sexual size dimorphism was greater in the species with stronger sexual selection on male size than in the species with weaker sexual selection.

Sex and the preimplantation embryo: implications of sexual dimorphism in the preimplantation period for maternal programming of embryonic development.

The developmental program of the embryo displays a plasticity that can result in long-acting effects that extend into postnatal life. In mammals, adult phenotype can be altered by changes in the maternal environment during the preimplantation period. One characteristic of developmental programming during this time is that the change in adult phenotype is often different for female offspring than for male offspring. In this paper, we propose the hypothesis that sexual dimorphism in preimplantation programming is mediated, at least in part, by sex-specific responses of embryos to maternal regulatory molecules whose secretion is dependent on the maternal environment. The strongest evidence for this idea comes from the study of colony-stimulating factor 2 (CSF2). Expression of CSF2 from the oviduct and endometrium is modified by environmental factors of the mother, in particular seminal plasma and obesity. Additionally, CSF2 alters several properties of the preimplantation embryo and has been shown to alleviate negative consequences of culture of mouse embryos on postnatal phenotype in a sex-dependent manner. In cattle, exposure of preimplantation bovine embryos to CSF2 causes sex-specific changes in gene expression, interferon-τ secretion and DNA methylation later in pregnancy (day 15 of gestation). It is likely that several embryokines can alter postnatal phenotype through actions directed towards the preimplantation embryo. Identification of these molecules and elucidation of the mechanisms by which sexually-disparate programming is established will lead to new insights into the control and manipulation of embryonic development.

Sexual size dimorphism in calanoid copepods (Centropagidae) from Patagonia (Argentina)

Calanoid copepods of the genus Boeckella and Parabroteas (P. sarsi) are dominant in zooplankton communities of Patagonian lakes and ponds. This study addresses the occurrence of sexual size dimorphism in calanoid copepods of the genus Boeckella and in the monospecific genus Parabroteas occurring in 12 lakes and ponds of Patagonia (Argentina). The morphometric analysis performed showed that in all the species studied the female is larger than the male, although the difference in size among sexes was found to be variable between species. Interestingly, all species showed significant intraspecific stability in their sexual size dimorphism despite potential differences in their environments regarding predation pressure, environmental stability (permanent or temporary waters) and altitude distribution of populations. Finally, we discuss the potential implications of sexual dimorphism in terms of resource use and vulnerability to predation among other environmental forces which may play a role in promoting larger female to male size.

Sexual dimorphism in the squirrel monkey, Saimiri sciureus (Linnaeus, 1758) and Saimiri ustus (I. Geoffroy, 1844) (Primates, Cebidae)

Causes and implications of sexual dimorphism have been studied in several different primates using a variety of morphological characters such as body weight, canine length, coat color and ornamentation. Here we describe a peculiar coat color characteristic in the squirrel monkey that is present only in adult females over five years old and which increases with age. Neither males nor young animals manifest this phenomenon, which is characterized by a spot of black hairs located anteriorly to the external ear (pinna). This characteristic could be used to discriminate adult females of Saimiri sciureus in the wild without the need of capture techniques.

Surface Remodelling of the Facial Skeleton in Juvenile Macaca mulatta: Implications for Sexual Dimorphism

Surface Remodelling of the Facial Skeleton in Juvenile Macaca mulatta: Implications for Sexual Dimorphism

Degrees of sexual dimorphism in Cebus and other new world monkeys

Sexual dimorphism in primate species expresses the effects of phylogeny, life history, behavior, and ontogeny. The causes and implications of sexual dimorphism have been studied in several different primates using a variety of morphological databases such as body weight, canine length, and coat color and ornamentation. In addition to these different patterns of dimorphism, the degree to which a species is dimorphic results from a variety of possible causes. In this study we test the general hypothesis that a species highly dimorphic for one size-based index of dimorphism will be equally dimorphic (relative to other species) for other size-based indices. Specifically, the degree and pattern of sexual dimorphism in Cebus and several other New World monkey species is measured using craniometric data as a substitute for the troublesome range of variation in body weight estimates. In general, the rank ordering of species for dimorphism ratios differs considerably across neural vs. non-neural functional domains of the cranium. The relative degree of sexual dimorphism in different functional regions of the cranium is affected by the independent action of natural selection on those regions. Regions of the cranium upon which natural selection is presumed to have acted within a species show greater degrees of dimorphism than do the same regions in closely related taxa. Within Cebus, C. apella is consistently more dimorphic than other Cebus species for facial measurements, but not for neural or body weight measurements. The pattern in C. apella indicates no single best measurement of the degree of dimorphism in a species; rather, the relative degree of dimorphism applies only to the region being measured and may be enhanced by other selective pressures on morphology. Am J Phys Anthropol 107:243–256, 1998. © 1998 Wiley-Liss, Inc.

Ecological and Social Implications of Sexual Dimorphism in Five Melanerpine Woodpeckers

Sexual differences within species have provided material for debate on a number of issues. Recently, several reports have indicated the ecological importance of sexual dimorphism in certain species, primarily birds (c.f. Amadon 1950, 1959; Cade 1960; Ward 1965; Sibley 1957; Selander 1966) and lizards (Schoener 1967, 1968, 1970). These discussions have indicated certain relationships between sexual differences in size of trophic appendages and specialization in foraging patterns. This report considers the ecological effects of sexual dimorphism as related to foraging behavior in five species of melanerpine woodpeckers and suggests certain social implications of such differences which have thus far received little attention.