Dimorphic Expression Research Articles

Cartilaginous Fishes Provide Insights into the Origin, Diversification, and Sexually Dimorphic Expression of Vertebrate Estrogen Receptor Genes.

Vertebrate estrogen receptors (ERs) perform numerous cell signaling and transcriptional regulatory functions. ERɑ (Esr1) and ERβ (Esr2) likely evolved from an ancestral receptor that duplicated and diverged at the protein and cis-regulatory levels, but the evolutionary history of ERs, including the timing of proposed duplications, remains unresolved. Here we report on identification of two distinct ERs in cartilaginous fishes and demonstrate their orthology to ERα and ERβ. Phylogenetic analyses place the ERα/ERβ duplication near the base of crown gnathostomes (jawed vertebrates). We find that ERα and ERβ from little skate (Leucoraja erinacea) and mammals share key subtype-specific residues, indicating conserved protein evolution. In contrast, jawless fishes have multiple non-orthologous Esr genes that arose by parallel duplications. Esr1 and Esr2 are expressed in subtype-specific and sexually dimorphic patterns in skate embryos, suggesting that ERs might have functioned in sexually dimorphic development before the divergence of cartilaginous and bony fishes.

A fool’s mission? A test of three common assumptions in dental metric analyses

Three aspects of metric variation in the permanent dentition of humans are often simply accepted as true. The first is that formation of the permanent dentition occurs within morphogenetic fields broadly associated with tooth type and jaw. The second is that dental development of among females is characterized by a higher degree of ontogenetic buffering relative to males. The third is that expression of sex dimorphism in permanent tooth size is expressed uniformly among well-nourished human populations. This study tests these assumptions through an examination of mesiodistal and buccolingual dimensions of all non-canine permanent teeth, except third molars, among 2,709 living individuals of 15 ethnic groups from South Asia. With sexes pooled, only one in four contrasts of variance among key versus distal teeth within dental fields are significantly heterogeneous, while one in four contrasts yield higher levels of variance among key teeth relative to their distal counterparts within a dental field. Such results weaken considerably orthodox applications of Butler’s dental field theory. When samples are the unit of analysis, male samples are marked by fewer dental fields with significantly heterogeneous levels of variance between key and distal members, while males and females are affected equally by significantly heterogeneous variation between key and distal members when dental fields are the unit of analysis. Such results suggest males and females are equally buffered against environmental perturbations that affect odontometric variation. One-way ANOVA indicates that a tooth’s position within a dental field ac-counts for 15.5% to 23.1% of the observed varia-tion in tooth size, while two-way ANOVA reveals that when sex is added as a second factor, the percentage of variance in tooth size explained increases from 16.7% to 30.8%, an improvement of 27.2%. Such results indicate sex dimorphism in tooth size varies in both patterning and in magnitude among these samples, thereby explaining why discriminant functions developed for one population often perform more poorly when applied to other populations.

Past experience shapes sexually dimorphic neuronal wiring through monoaminergic signalling.

Differences in female and male brains exist across the animal kingdom and extend from molecular to anatomical features. We show here that sexually dimorphic anatomy, gene expression, and function in the nervous system can be modulated by past experiences. In the nematode C. elegans, sexual differentiation entails the sex-specific synaptic pruning of synaptic connections between sex-shared neurons, giving rise to sexually dimorphic circuits in adult animals 1. We discovered that starvation during juvenile stages is memorized in males to suppress the emergence of sexually dimorphic synaptic connectivity. These circuit changes confer increased chemosensory responsiveness in adult males following juvenile starvation. We find that an octopamine-mediated starvation signal dampens serotonin production to convey the memory of starvation. Serotonin production is monitored by a 5-HT1A serotonin receptor homolog which acts cell-autonomously to promote the pruning of sexually dimorphic synaptic connectivity under well-fed conditions. Our studies demonstrate how life history can impact neurotransmitter production, synaptic connectivity, and behavioral output in a sexually dimorphic circuit.

FOXL2 and DMRT1L Are Yin and Yang Genes for Determining Timing of Sex Differentiation in the Bivalve Mollusk Patinopecten yessoensis.

Sex determination and differentiation have long been a research hotspot in metazoans. However, little is known about when and how sex differentiation occurs in most mollusks. In this study, we conducted a combined morphological and molecular study on sex differentiation in the Yesso scallop Patinopecten yessoensis. Histological examination on gonads from 5- to 13-month-old juveniles revealed that the morphological sex differentiation occurred at 10 months of age. To determine the onset of molecular sex differentiation, molecular markers were screened for early identification of sex. The gonadal expression profiles of eight candidate genes for sex determination or differentiation showed that only two genes displayed sexually dimorphic expression, with FOXL2 being abundant in ovaries and DMRT1L in testes. In situ hybridization revealed that both of them were detected in germ cells and follicle cells. We therefore developed LOG10(DMRT1L/FOXL2) for scallop sex identification and confirmed its feasibility in differentiated individuals. By tracing its changes in 5- to 13-month-old juveniles, molecular sex differentiation time was determined: some scallops differentiate early in September when they are 7 months old, and some do late in December when they are 10 months old. Two kinds of coexpression patterns were found between FOXL2 and DMRT1L: expected antagonism after differentiation and unexpected coordination before differentiation. Our results revealed that scallop sex differentiation co-occurs with the formation of follicles, and molecular sex differentiation is established prior to morphological sex differentiation. Our study will assist in a better understanding of the molecular mechanism underlying bivalve sex differentiation.

Sexually dimorphic behavior, neuronal activity, and gene expression in Chd8-mutant mice.

Autism spectrum disorders (ASDs) are four times more common in males than in females, but the underlying mechanisms are poorly understood. We characterized sexually dimorphic changes in mice carrying a heterozygous mutation in Chd8 (Chd8+/N2373K) that was first identified in human CHD8 (Asn2373LysfsX2), a strong ASD-risk gene that encodes a chromatin remodeler. Notably, although male mutant mice displayed a range of abnormal behaviors during pup, juvenile, and adult stages, including enhanced mother-seeking ultrasonic vocalization, enhanced attachment to reunited mothers, and isolation-induced self-grooming, their female counterparts do not. This behavioral divergence was associated with sexually dimorphic changes in neuronal activity, synaptic transmission, and transcriptomic profiles. Specifically, female mice displayed suppressed baseline neuronal excitation, enhanced inhibitory synaptic transmission and neuronal firing, and increased expression of genes associated with extracellular vesicles and the extracellular matrix. Our results suggest that a human CHD8 mutation leads to sexually dimorphic changes ranging from transcription to behavior in mice.

PDF-1 neuropeptide signaling regulates sexually dimorphic gene expression in shared sensory neurons of C. elegans.

Sexually dimorphic behaviors are a feature common to species across the animal kingdom, however how such behaviors are generated from mostly sex-shared nervous systems is not well understood. Building on our previous work which described the sexually dimorphic expression of a neuroendocrine ligand, DAF-7, and its role in behavioral decision-making in C. elegans (Hilbert and Kim, 2017), we show here that sex-specific expression of daf-7 is regulated by another neuroendocrine ligand, Pigment Dispersing Factor (PDF-1), which has previously been implicated in regulating male-specific behavior (Barrios et al., 2012). Our analysis revealed that PDF-1 signaling acts sex- and cell-specifically in the ASJ neurons to regulate the expression of daf-7, and we show that differences in PDFR-1 receptor activity account for the sex-specific effects of this pathway. Our data suggest that modulation of the sex-shared nervous system by a cascade of neuroendocrine signals can shape sexually dimorphic behaviors.

Characterization of the growth rate of adult wolffishes Anarhichas minor and A. lupus: Is avoidance of paternal care at the origin of the expression of a sexual size dimorphism?

Sexual size dimorphism (SSD) in wolffishes has never been unquestionably reported in previous fisheries or aquaculture studies. The sex-related growth patterns of 6+Anarhichas lupus and 3+A. minor (Norway (NW) and Québec (QC) populations) were monitored in replicates in a controlled environment over two successive spawning seasons (21 months). Overall growth achieved indicates the expression of male-biased SSD in males of A. lupus, A. minorqc and A. minornw, being 36.2, 34.0 and 19.6% heavier and 9.7 ± 0.3%, 5.8 ± 0.4% and 5.4 ± 0.2% longer respectively. Male and females A. minor of both populations started at 1 kg body weight and males ended up averaging 3.2–3.5 kg. Females from Norway and Canada reached 2 kg and 2.8 kg respectively, indicating a male growth advantage over female and a lessened expression of SSD in the Norwegian population. A. minornw achieved higher final weight and length in comparison to A. minorqc. In captivity, females underwent normal maturation cycles whereas males were free from egg-guarding duties, which most likely contributed to the expression of SSD benefiting males. In the wild, prolonged embryo paternal care duties, coupled with loss of teeth and reduced feeding during incubation, likely offset any substantial growth advantages for males. The observed reduction in female growth and condition factor values coincide consistently with maturation events. Female specific growth rate also showed more pronounced fluctuations, leading to the observation of a significant growth divergence. The sex-specific growth trajectories achieved in captivity are briefly compared with observations from fishery-based growth studies that not once reported conclusive sex differences. Our observations point to the behavioural and environmental sensitivity of SSD and to the rationale of sex control in wolffish cultivation to produce all male stocks and only rear the fastest-growing sex.

Gαi3 signaling is associated with sexual dimorphic expression of the clock-controlled output gene Dbp in murine liver.

The albumin D-box binding protein (DBP) is a member of the PAR bZip (proline and acidic amino acid-rich basic leucine zipper) transcription factor family and functions as important regulator of circadian core and output gene expression. Gene expression of DBP itself is under the control of E-box-dependent binding by the Bmal1-Clock heterodimer and CRE-dependent binding by the cAMP responsive element binding protein (CREB). However, the signaling mechanism mediating CREB-dependent regulation of DBP expression in the peripheral clock remains elusive. In this study, we examined the role of the GPCR (G-protein-coupled receptor)/Gαi3 (Galphai3) controlled cAMP-CREB signaling pathway in the regulation of hepatic expression of core clock and clock-regulated genes, including Dbp. Analysis of circadian gene expression revealed that rhythmicity of hepatic transcript levels of the majority of core clock (including Per1) and clock-regulated genes were not affected by Gαi3 deficiency. Consistently, the period length of primary Gαi3 deficient tail fibroblasts expressing a Bmal1-Luciferase reporter was not affected. Interestingly, however, Gαi3 deficient female but not male mice showed a tendentiously increased activation of CREB (nuclear pSer133-CREB) accompanied by an advanced peak in Dbp gene expression and elevated mRNA levels of the cytochrome P450 family member Cyp3a11, a target gene of DBP. Accordingly, selective inhibition of CREB led to a strongly decreased expression of DBP and CYP3A4 (human Cyp3a11 homologue) in HepG2 liver cells. In summary, our data suggest that the Gαi3-pCREB signalling pathway functions as a regulator of sexual-dimorphic expression of DBP and its xenobiotic target enzymes Cyp3a11/CYP3A4.

Tdrd1 is a germline-specific and sexually dimorphically expressed gene in Paralichthys olivaceus

Tudor domain containing protein 1 (tdrd1) is a member of the Tudor family and has shown essential functions during embryogenesis and gametogenesis. In this study, we cloned the full length cDNA of Paralichthys olivaceus tdrd1 (Potdrd1). PoTDRD1 is a multidomain protein with an N-terminal MYND zinc finger domain, followed by four tandem extended Tudor domains. Sequence comparison, genomic structure, phylogenetic analyses and synteny analyses showed that Potdrd1 was homologous to those of other teleosts. In adult individuals, the expression of Potdrd1 was higher in testis than in ovary, demonstrating a sexually dimorphic gene expression pattern. In situ hybridization (ISH) showed that Potdrd1 mRNA was detected in oogonia and oocytes of ovary as well as in spermatogonia and spermatocytes of testis. In juveniles during gonad differentiation its expression level increased rapidly from 30 dph to 100 dph and showed obvious sexual dimorphism that was in accordance with the expression of anti-Mullerian hormone (amh). Potdrd1 mRNA was consistently detected during embryogenesis, and its level was higher from unfertilzed eggs to the blastula stage and subsequently decreased until hatching. When chimeric RNA containing green fluorescent protein (GFP) and 3′ untranslated regions (UTR) of Potdrd1 was microinjected into zebrafish fertilized eggs, the green fluorescence could be visualized only in putative PGCs. These results indicated that Potdrd1 is a germline specific and sexually dimorphic factor that potentially functionate in germline development and gametogenesis in Japanese flounder.

Stat5b Regulates Sexually Dimorphic Gene Expression in Zebrafish Liver.

Sexual size dimorphism is an interesting phenomenon occurred in many fish species. Wildtype zebrafish exhibits a significant sexual dimorphism in body size at the adult stage. Previous studies indicated that sexual size dimorphism was eliminated in stat5b-mutated zebrafish. Herein, the comparative transcriptome analysis was conducted to observe the genes and pathways involved in sexual size dimorphism. The number of male-biased and female-biased genes was much less in the liver of stat5b mutant zebrafish than in wildtype. Gene ontology (GO) enrichment and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis indicated that multiple pathways related to metabolism were affected upon loss of stat5b function. qRT-PCR results also validated that sexually dimorphic expression of a set of genes was lost when stat5b was mutated. Furthermore, the weighted correlation network analysis (WGCNA) detected many candidate genes related to the growth traits and stat5b function, such as greb1, lepr, and igf2b. Our data suggest that stat5b should regulate the sexually dimorphic gene expression in zebrafish liver and add in understanding of the molecular mechanisms underlying sexual size dimorphism in fish species.

Identification of genes involved in gonadal sex differentiation and the dimorphic expression pattern in Takifugu rubripes gonad at the early stage of sex differentiation.

Quantifying the expression of mRNAs in the gonads at the critical stage of molecular sex differentiation stage might help to clarify the regulatory network during early sex differentiation and provide new information on the role of sex-related genes in gonadal function. In this study, transcriptomic analysis of sex-related genes expression profiles in fugu gonads at 60 and 90days after hatching (dah) was conducted firstly, and a total of 112,504,991 clean reads, encompassing 28.35Gb of sequences were retrieved. Twenty-three thousand eight hundred ten genes were found to be expressed in juvenile fugu gonads, and we mainly focused on the differentially expressed genes that have the potential to be involved in the gonadal sex differentiation. For 60-dah juveniles, we identified 1014 genes that were upregulated in the ovary and 1570 that were upregulated in the testis. For 90-dah juveniles, we identified 1287 genes that were upregulated in the ovary and 1500 that were upregulated in the testis. The dimorphic expression patterns of 15 genes in gonads at 30 and 40dah were further investigate using qPCR. Cyp11b and star were expressed at higher levels in XY than in XX, while cyp11a1 and cyp19a1a were expressed at higher levels in XX than in XY at 30dah. At 40dah, the levels of gsdf, dmrt1, dmrt3, cyp11c1, star, and hsd3b expression were higher in XY, while the levels of foxl2, cyp19a1a, wnt9b, and foxD4 expression were higher in XX. Sox9, cyp11a1, cyp17a1, cyp17a2, and nr5a2 were expressed at similar levels in XX and XY at 40dah. This is the first report of gonadal transcriptome of fugu at early sex differentiation stage, and our results provide an archive for further study on molecular mechanism underlying sex differentiation in this species.

Sexually dimorphic gene expression in lactotroph pituitary tumours of different behaviours

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

A Distalless-responsive enhancer of the Hox gene Sex combs reduced is required for segment- and sex-specific sensory organ development in Drosophila.

Hox genes are involved in the patterning of animal body parts at multiple levels of regulatory hierarchies. Early expression of Hox genes in different domains along the embryonic anterior-posterior (A/P) axis in insects, vertebrates, and other animals establishes segmental or regional identity. However, Hox gene function is also required later in development for the patterning and morphogenesis of limbs and other organs. In Drosophila, spatiotemporal modulation of Sex combs reduced (Scr) expression within the first thoracic (T1) leg underlies the generation of segment- and sex-specific sense organ patterns. High Scr expression in defined domains of the T1 leg is required for the development of T1-specific transverse bristle rows in both sexes and sex combs in males, implying that the patterning of segment-specific sense organs involves incorporation of Scr into the leg development and sex determination gene networks. We sought to gain insight into this process by identifying the cis-and trans-regulatory factors that direct Scr expression during leg development. We have identified two cis-regulatory elements that control spatially modulated Scr expression within T1 legs. One of these enhancers directs sexually dimorphic expression and is required for the formation of T1-specific bristle patterns. We show that the Distalless and Engrailed homeodomain transcription factors act through sequences in this enhancer to establish elevated Scr expression in spatially defined domains. This enhancer functions to integrate Scr into the intrasegmental gene regulatory network, such that Scr serves as a link between leg patterning, sex determination, and sensory organ development.

Expression profiling of c-kit and its impact after esiRNA silencing during gonadal development in catfish

Receptor, c-Kit is a member of a family of growth factor receptors that have tyrosine kinase activity, and are involved in the transduction of growth regulatory signals across plasma membrane by activation of its ligand, kitl/scf. The present study analyzed mRNA and protein expression profiles of c-kit in the gonads of catfish, Clarias gariepinus, using real time PCR, in situ hybridization and immunohistochemistry. Tissue distribution analysis revealed higher expression mainly in the catfish gonads. Ontogeny studies showed minimal expression during early developmental stages and highest during 50–75 days post hatch, and the dimorphic expression in gonads decreased gradually till adulthood, which might suggest an important role for this gene around later stages of sex differentiation and gonadal development. Expression of c-kit was analyzed at various phases of gonadal cycle in both male and female, which showed minimal expression during the resting phase, and higher expression during the pre-spawning phase in male compared to females. In vitro and in vivo induction using human chorionic gonadotropin elevated the expression of c-kit indicating the regulatory influence of hypothalamo-hypophyseal axis. In vivo transient gene silencing using c-kit-esiRNA in adult catfish during gonadal recrudescence showed a decrease in c-kit expression, which affected the expression levels of germ cell meiotic marker sycp3, as well as several factors and steroidogenic enzyme genes that are involved in germ cell development. Decrease in the levels of 11-ketotestosterone and testosterone in serum were also observed after esiRNA silencing. The findings suggests that c-kit has an important role in the process of germ cell proliferation, development and maturation during gonadal development and recrudescence in catfish.

Sexually Dimorphic Ano2 Expression in Nodose Neurons Determines CCK‐mediated Satiation and Obesity in Heterozygote Male Mice

The gut peptide cholecystokinin (CCK) contributes to neurally mediated post prandial satiety. Our previous results indicate that high fat diet downregulates the CCK‐sensitive anoctamins (Ano1 and Ano2) that function as calcium‐activated chloride channels (CaCCs) in intestinal vagal afferents. Using Cre‐loxP system, we generated heterozygote (HET) Nav1.8CreAno2fl/WT mice. The endogenous Scn10a promoter drives Cre expression (Nav1.8Cre) selectively in sensory neurons of the nodose, dorsal root and trigeminal ganglia where loxP sites flanked Ano2 exon 12. The male HET mice exhibited an obese phenotype and decreased sensitivity to CCK. To assess the Ano2 expression in HET vs. control (Nav1.8Cre+/−) mice, we first did qRT‐PCR on whole nodose ganglia obtained under anesthesia at 50 weeks of age and found no significant difference in Ano2 mRNA expression (n=4, p>0.05). Ano2 gene may be expressed in non‐neuronal cells of nodose ganglia while Cre expression is selective to neurons. We measured Ano2 mRNAs in nodose neurons cultured for 16–18 hours using single cell qRT‐PCR. Cre positive neurons were 57% (12 of 21) in HET and 74% (29 of 39) in control, indicating a lower efficiency of Cre expression in HET. Correspondingly, Ano2 positive neurons were 48% (10 of 21) and 62% (24 of 39), respectively, indicating the Ano2 allelic deletion in HET. The combined Cre and Ano2 positivity in HET was 29% (6 of 21) vs. 54% (21 of 39) in control. Most importantly the Ano2 mRNA levels in HET neurons (n=10) were 20% of the levels measured in control neurons (n=24, p<0.05) (0.20±0.16 vs. 1.00±0.57). The Ano2 expression in individual nodose neurons of female mice did not show a reduction or even higher in HET (n=27) vs. control (n=28) (2.58±1.48 vs. 1.42±1.27, p>0.05). The female HET mice remained CCK sensitive indicating a sexual dimorphism. We conclude that differences in expression of Ano2 mRNA support our findings of CCK insensitivity and selective obesity in male but not female HET mice (HL14388).Support or Funding InformationNIH HL14388This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

StAR protein and steroidogenic enzyme expressions in the rat Harderian gland

The Harderian gland (HG) of the rat (Rattus norvegicus) secretes copious amounts of lipids, such as cholesterol. Here we report a study of the expressions of the StAR protein and key steroidogenic enzymes in the HG of male and female rats. The objective of the present investigation was to ascertain (a) whether the rat HG is involved in steroid production starting with cholesterol, and (b) whether the pattern of gene and protein expressions together with the enzymatic activities display sexual dimorphism. The results demonstrate, for the first time, the expression of StAR gene and protein, and Cyp11a1, Hsd3b1, Hsd17b3, Srd5a1, Srd5a2 and Cyp19a1 genes in the rat HG. StAR mRNA and protein expressions were much greater in males than in females. Immunohistochemical analysis demonstrated a non-homogeneous StAR distribution among glandular cells. Hsd17b3 and Cyp19a1 mRNA levels were higher in males than in females, whereas Srd5a1 mRNA levels were higher in females than in males. No significant differences were observed in mRNA levels of Cyp11a1, Hsd3b1 and Srd5a2 between sexes. Furthermore, the in vitro experiments demonstrated a higher 5α-reductase activity in the female as compared to the male HG vice versa a higher P450 aro activity in males as compared to females. These results suggest that the Harderian gland can be classified as a steroidogenic tissue because it synthesizes cholesterol, expresses StAR and steroidogenic enzymes involved in both androgen and estrogen synthesis. The dimorphic expression and activity of the steroidogenic enzymes may suggest sex-specific hormonal effects into the HG physiology.

Sexually Dimorphic Gene Expression of Skeletal Muscle Insulin‐Signalling Pathways Following Maternal Sildenafil Treatment of the Growth‐Restricted Ovine Fetus

Sexually Dimorphic Gene Expression of Skeletal Muscle Insulin‐Signalling Pathways Following Maternal Sildenafil Treatment of the Growth‐Restricted Ovine Fetus

Roles of Two Sox9 Genes during Gonadal Development in Japanese Flounder: Sex Differentiation, Spermatogenesis and Gonadal Function Maintenance.

The transcription factor sox9 has been implicated in cartilage formation and testis determination in mammals. Here, two duplicates of sox9 were found in Japanese flounder (Paralichthys olivaceus) named Posox9a and Posox9b, respectively. Phylogenetic and gene structure analyses revealed that Posox9a and Posox9b were homologous to that of teleosts and tetrapods. Quantitative real-time polymerase chain reaction (qRT-PCR) showed that both Posox9a and Posox9b expressed higher in testis than in ovary of adult tissues. The in situ hybridization (ISH) analysis of gonads showed that Posox9a and Posox9b mRNA were both detected in oocytes, Sertoli cells and spermatocytes. During sex differentiation, the expression of Posox9a exhibited obvious sexual dimorphic expression from 60 days after hatch (dah) with higher expression in male preferred individuals than female preferred individuals and increased gradually from 30 to 100 dah. A similar pattern was detected in Posox9b expression. After injection of androgen (17α-methyltestosterone) of different concentrations, the expression level of Posox9b increased significantly, whereas Posox9a did not change obviously. These results indicated that the two sox9 genes of Japanese flounder had converse functions in sex differentiation, whereas their differences in 17α-methyltestosterone administration were obvious and worthwhile for exploring evolutionary and adaptive significance. This study provided a foundation for further exploration of the roles of Posox9 genes during the sex determination and differentiation, spermatogenesis and gonadal function maintenance of Japanese flounder.

An interaction-driven cannibalistic reaction norm.

sCannibalism is induced in larval‐stage populations of the Hokkaido salamander, Hynobius retardatus, under the control of a cannibalism reaction norm. Here, I examined phenotypic expression under the cannibalism reaction norm, and how the induction of a cannibalistic morph under the norm leads to populational morphological diversification. I conducted a set of experiments in which density was manipulated to be either low or high. In the high‐density treatment, the populations become dimorphic with some individuals developing into the cannibal morph type. I performed an exploratory analysis based on geometric morphometrics and showed that shape characteristics differed between not only cannibal and noncannibal morph types in the high‐density treatment but also between those morph types and the solitary morph type in the low‐density treatment. Size and shape of cannibal and noncannibal individuals were found to be located at either end of a continuum of expression following a unique size–shape integration rule that was different from the rule governing the size and shape variations of the solitary morph type. This result implies that the high‐density‐driven inducible morphology of an individual is governed by a common integration rule during the development of dimorphism under the control of the cannibalism reaction norm. Phenotypic expression under the cannibalism reaction norm is driven not only by population density but also by social interactions among the members of a population: variation in the populational expression of dimorphism is associated with contingent social interaction events among population members. The induced cannibalistic morph thus reflects not only by contest‐type exploitative competition but also interference competition.

Sex differences in the late first trimester human placenta transcriptome

BackgroundDevelopment of the placenta during the late first trimester is critical to ensure normal growth and development of the fetus. Developmental differences in this window such as sex-specific variation are implicated in later placental disease states, yet gene expression at this time is poorly understood.MethodsRNA-sequencing was performed to characterize the transcriptome of 39 first trimester human placentas using chorionic villi following genetic testing (17 females, 22 males). Gene enrichment analysis was performed to find enriched canonical pathways and gene ontologies in the first trimester. DESeq2 was used to find sexually dimorphic gene expression. Patient demographics were analyzed for sex differences in fetal weight at time of chorionic villus sampling and birth.ResultsRNA-sequencing analyses detected 14,250 expressed genes, with chromosome 19 contributing the greatest proportion (973/2852, 34.1% of chromosome 19 genes) and Y chromosome contributing the least (16/568, 2.8%). Several placenta-enriched genes as well as histone-coding genes were identified to be unique to the first trimester and common to both sexes. Further, we identified 58 genes with significantly different expression between males and females: 25 X-linked, 15 Y-linked, and 18 autosomal genes. Genes that escape X inactivation were highly represented (59.1%) among X-linked genes upregulated in females. Many genes differentially expressed by sex consisted of X/Y gene pairs, suggesting that dosage compensation plays a role in sex differences. These X/Y pairs had roles in parallel, ancient canonical pathways important for eukaryotic cell growth and survival: chromatin modification, transcription, splicing, and translation.ConclusionsThis study is the first characterization of the late first trimester placenta transcriptome, highlighting similarities and differences among the sexes in ongoing human pregnancies resulting in live births. Sexual dimorphism may contribute to pregnancy outcomes, including fetal growth and birth weight, which was seen in our cohort, with males significantly heavier than females at birth. This transcriptome provides a basis for development of early diagnostic tests of placental function that can indicate overall pregnancy heath, fetal-maternal health, and long-term adult health.