Sex Determination Research Articles

Verification of a Greener Method of Sex Determination Through the Multi-Elemental Analysis of Hair Using Electrothermal Vaporization Coupled to Inductively Coupled Plasma Optical Emission Spectrometry

Verification of a Greener Method of Sex Determination Through the Multi-Elemental Analysis of Hair Using Electrothermal Vaporization Coupled to Inductively Coupled Plasma Optical Emission Spectrometry

Balancing selfing and outcrossing: the genetics and cell biology of nematodes with three sexual morphs.

Trioecy, a rare reproductive system where hermaphrodites, females, and males coexist, is found in certain algae, plants, and animals. Though it has evolved independently multiple times, its rarity suggests it may be an unstable or transitory evolutionary strategy. In the well-studied Caenorhabditis elegans, attempts to engineer a trioecious strain have reverted to the hermaphrodite/male system, reinforcing this view. However, these studies did not consider the sex-determination systems of naturally stable trioecious species. The discovery of free-living nematodes of the Auanema genus, which have naturally stable trioecy, provides an opportunity to study these systems. In Auanema, females produce only oocytes, while hermaphrodites produce both oocytes and sperm for self-fertilization. Crosses between males and females primarily produce daughters (XX hermaphrodites and females), while male-hermaphrodite crosses result in sons only. These skewed sex ratios are due to X-chromosome drive during spermatogenesis, where males produce only X-bearing sperm through asymmetric cell division. The stability of trioecy in Auanema is influenced by maternal control over sex determination and environmental cues. These factors offer insights into the genetic and environmental dynamics that maintain trioecy, potentially explaining its evolutionary stability in certain species.

Human identification via digital palatal scans: a machine learning validation pilot study.

This study aims to validate a machine learning algorithm previously developed in a training population on a different randomly chosen population (i.e., test set). The discrimination potential of the palatal intraoral scan-based geometric and superimposition methods was evaluated. A total of 23 participants (16 females and seven males) from different countries underwent palatal scans using the Emerald intraoral scanner. Geometric-based identification involved measuring the height, width, and depth of the palatal vault in each scan. These parameters were then input into Fisher's linear discriminant equations with coefficients determined previously on a training set. Sensitivity and specificity were calculated. For the superimposition method, scan repeatability was compared to between-subjects differences, calculating mean absolute differences (MAD) between aligned scans. Multiple linear regression analysis determined the effects of sex, longitude, and latitude of country of origin on concordance. The geometric-based method achieved 91.2% sensitivity and 97.1% specificity, consistent with the results from the training set, showing no significant difference. Latitude and longitude did not significantly affect geometric-based matches. In the superimposition method, the between-subjects MAD range (1.068-0.214mm) and the repeatability range (0.011-0.093mm) did not overlap. MAD was minimally affected by longitude and not influenced by latitude. The sex determination function recognized females over males with 69.0% sensitivity, similar to the training set. However, the specificity (62.5%) decreased. The assessment of geometric and superimposition discrimination has unequivocally demonstrated its robust reliability, remaining impervious to population. In contrast, the distinction between sexes carries only moderate reliability. The significant correlation observed among longitude, latitude, and palatal height suggests the feasibility of a comprehensive large-scale study to determine one's country of origin. Portable intraoral scanners can aid forensic investigations as adjunct identification methods by applying the proposed discriminant function to palatal geometry without population restrictions. The Clinicatrial.gov registration number is NCT05349942 (27/04/2022).

Comparative Transcriptome Analysis of Sexual Differentiation in Male and Female Gonads of Nao-Zhou Stock Large Yellow Croaker (Larimichthys crocea)

The Nao-zhou stock large yellow croaker (Larimichthys crocea) is a unique economic seawater fish species in China and exhibits significant dimorphism in both male and female phenotypes. Cultivating all-female seedlings can significantly improve breeding efficiency. To accelerate the cultivation process of all female seedlings of this species, it is necessary to deeply understand the regulatory mechanisms of sexual differentiation and gonadal development. This study used Illumina high-throughput sequencing to sequence the transcriptome of the testes and ovaries of Nao-zhou stock large yellow croaker to identify genes and molecular functions related to sex determination. A total of 10,536 differentially expressed genes were identified between males and females, including 5682 upregulated and 4854 downregulated genes. Functional annotation screened out 70 important candidate genes related to sex, including 34 genes highly expressed in the testis (including dmrt1, foxm1, and amh) and 36 genes highly expressed in the ovary (including gdf9, hsd3b1, and sox19b). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis found that differentially expressed genes were significantly enriched in nine signaling pathways related to sex determination and gonadal development, including steroid hormone biosynthesis, MAPK signaling pathway, and the TGF-beta signaling pathway. By screening sex-related differentially expressed genes and mapping protein–protein interaction networks, hub genes such as dmrt1, amh, and cyp19a1a were found to be highly connected. The expression levels of 15 sex-related genes, including amh, dmrt1, dmrt2a, foxl1, and zp3b, were determined by qRT–PCR and RNA sequencing. This study screened for differentially expressed genes related to sex determination and differentiation of Nao-zhou stock large yellow croaker and revealed the signaling pathways involved in gonad development of male and female individuals. The results provide important data for future research on sex determination and differentiation mechanisms, thereby providing a scientific basis for the cultivation of all-female seedlings.

Abstract 4124005: Sex, ethnic and social determinants of health differences in high-potency P2Y12 inhibitors prescription among patients with acute coronary syndrome: An analysis of the American Heart Association Get With The Guidelines®–Coronary Artery Disease Registry

Background: Sex and racial differences in the outcomes of patients with acute coronary syndrome (ACS) persist and could be related to the differences in management including high-potency P2Y12 inhibitors. Aim: This study aims to examine the contribution of social determinants of health on the association between sex and racial differences in the prescription of high-potency P2Y12 inhibitor upon discharge. Methods: Patients with ACS undergoing percutaneous coronary intervention (PCI) from the American Heart Association Get With The Guidelines®–Coronary Artery Disease Registry between October 2019 to December 2022 were included. Multivariable hierarchical models were used to assess whether there are differences in high-potency P2Y12 inhibitors (i.e., ticagrelor or prasugrel) prescription at discharge adjusting for race/ethnicity, insurance, age, social vulnerability index (SVI), zip code designation, and medical history. Analyses were performed in women and men separately. Results: Among 135,153 patients with ACS who underwent PCI, 59.8% were discharged on a high-potency P2Y12 inhibitor. Compared with men, women were less likely prescribed high-potency P2Y12 inhibitor (66.9% vs 72%), and this pattern did not change during the study period (P=0.50) (Figure). There was a significant interaction between sex and race for high-potency P2Y12 inhibitor prescription (P< 0.05). Among women, the likelihood of high-potency P2Y12 inhibitors prescription was not significantly different across different race/ethnicities. However, in men, non-Hispanic Blacks and Hispanics had lower odds of high-potency P2Y12 inhibitors prescription compared with non-Hispanic Whites among men after adjusting for all covariates. Conclusions: In this large contemporary observational analysis of patients with AMI undergoing PCI, women were less likely prescribed a high-potency P2Y12 inhibitor upon discharge. Among women, the likelihood of high-potency P2Y12 inhibitors prescription was not significantly different across different race/ethnicities; however, in men, non-Hispanic Blacks and Hispanics had lower odds of high-potency P2Y12 inhibitors prescription. Further efforts should be directed to minimize these sex and racial disparities.

Social Determinants of Health and Disparities in Guideline-Directed Medical Therapy Optimization for Heart Failure.

Fewer than 20% of eligible patients with heart failure with reduced ejection fraction receive all 4 pillars of guideline-directed medical therapy. Understanding disparities by race, ethnicity, sex, and adverse social determinants of health is necessary to equitably optimize quadruple therapy. Utilizing the American Heart Association's Get With The Guidelines-Heart Failure registry, we examined associations between race and ethnicity, sex, and adverse social determinants of health (insurance type and documented social need [any barrier to accessing health care]) with quadruple therapy optimization (QTO) in patients with heart failure with reduced ejection fraction hospitalized between July 1, 2021, and September 30, 2023, with complete medication data at discharge. We calculated adjusted mean differences (AMDs) in the discharge QTO score (range, 0%-100%) reflecting the proportion of eligible use of renin-angiotensin system inhibitors, β-blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter-2 inhibitors and compared across demographic and adverse social determinants of health groups. Among 82 637 patients (median age, 66 years; 32.5% female; 57.0% non-Hispanic White; 76.4% prior heart failure with reduced ejection fraction), the overall mean QTO score was 56.2% (SD, 25.5). After adjustment, compared with non-Hispanic White individuals, Black (AMD, 2.56 percentage points [95% CI, 2.16-2.96]) and Hispanic individuals (AMD, 0.71 percentage points [95% CI, 0.11-1.31]) had higher QTO scores. Females had higher QTO scores than males (AMD, 1.94 percentage points [95% CI, 1.58-2.31]). Patients with no insurance (AMD, -4.90 percentage points [-5.62 to -4.17]), Medicaid (AMD, -0.45 percentage points [-0.89 to -0.01]), and Medicare (AMD, -1.64 percentage points [-2.10 to -1.18]) had lower QTO scores versus private insurance. Those with an identified social need (n=24 651) had lower QTO scores than those without (AMD, -3.40 percentage points [95% CI, -4.10 to -2.71]). Disparities in QTO were most evident for patients with no insurance, Medicaid, Medicare, or potentially an identified social need. Future efforts should focus on reducing gaps to improve equitable guideline-directed medical therapy use.

One-step leaping evolution from an autosomal pair to the heteromorphic sex chromosomes.

Sex chromosomes evolve from an autosomal pair after the acquisition of a sex-determining gene. The primary sex chromosomes are homomorphic in both sexes and often undergo heteromorphism in either sex (XY in males or ZW in females) in association with chromosome rearrangements such as inversion, which creates a non-recombining region, called a stratum. Then, multiple strata may form by sequential inversions and extend the non-recombining region, where gene divergence accelerates, and degeneration of the Y or W chromosome progressively occurs. Contrast to the conventional theory, we propose a shortcut in heteromorphic sex chromosome evolution, where an autosomal pair directly evolves into a heteromorphic sex chromosome pair. We illustrate this with two frog cases where Y chromosome or autosome, which is morphologically inverted, was introgressed from another species through interspecific hybridization, instantly forming a new heteromorphic sex chromosome pair. This event resulted in a distinct non-recombining region immediately after hybridization. The introduction of an inverted chromosome from a different species may be associated with benefits in morphology, breeding behavior, hybrid viability, sex determination, and recovery of the sex ratio of the hybrids. We discuss the molecular mechanisms driving preferential mutations in the introduced, inverted chromosome through interspecific hybridization.

Relationship Between Loss of Y Chromosome and Urologic Cancers: New Future Perspectives

Background: The Y chromosome (ChrY) is essential for male sex determination and spermatogenesis. However, recent studies have revealed its broader role in various physiological processes and disease susceptibility, including cancer. Methods: A comprehensive literature review was conducted using databases like MEDLINE, Scopus, Web of Science, and Google Scholar. The review included clinical and preclinical studies in animals and humans focusing on the role of LoY in urological tumors. Data on the frequency of LoY, its clinical implications, and underlying mechanisms were extracted and analyzed. Results: The evidence suggests that LoY is associated with an increased risk of urologic neoplasms, potentially serving as an early marker of genomic instability. Studies reveal that LoY in urologic cancers correlates with worse survival outcomes and may contribute to tumor progression. LoY may interfere with chromatin structure and epigenetic regulation, suggesting its role as a contributor to early tumorigenesis. Conclusions: LoY appears to be a structural aberration with unique biological and clinical relevance in urologic cancers, possibly serving as a biomarker for genomic instability. Further research is necessary to identify specific Y-linked genes affected by LoY, potentially informing targeted therapies and early diagnostic strategies for these cancers.

Rapid chromosome evolution and acquisition of thermosensitive stochastic sex determination in nematode androdioecious hermaphrodites

The factors contributing to evolution of androdioecy, the coexistence of hermaphrodites and males such as in Caenorhabditis elegans, remains poorly known. However, nematodes exhibit androdioecy in at last 13 genera with the predatory genus Pristionchus having seven independent transitions towards androdioecy. Nonetheless, associated genomic architecture and sex determination mechanisms are largely known from Caenorhabditis. Here, studying 47 Pristionchus species, we observed repeated chromosome evolution which abolished the ancestral XX/XO sex chromosome system. Two phylogenetically unrelated androdioecious Pristionchus species have no genomic differences between sexes and mating hermaphrodites with males resulted in hermaphroditic offspring only. We demonstrate that stochastic sex determination is influenced by temperature in P. mayeri and P. entomophagus, and CRISPR engineering indicated a conserved role of the transcription factor TRA-1 in P. mayeri. Chromosome-level genome assemblies and subsequent genomic analysis of related Pristionchus species revealed stochastic sex determination to be derived from XY sex chromosome systems through sex chromosome-autosome fusions. Thus, rapid karyotype evolution, sex chromosome evolution and evolvable sex determination mechanisms are general features of this genus, and represent a dynamic background against which androdioecy has evolved recurrently. Future studies might indicate that stochastic sex determination is more common than currently appreciated.

3D chromatin maps of a brown alga reveal U/V sex chromosome spatial organization.

Nuclear three dimensional (3D) folding of chromatin structure has been linked to gene expression regulation and correct developmental programs, but little is known about the 3D architecture of sex chromosomes within the nucleus, and how that impacts their role in sex determination. Here, we determine the sex-specific 3D organization of the model brown alga Ectocarpus chromosomes at 2 kb resolution, by mapping long-range chromosomal interactions using Hi-C coupled with Oxford Nanopore long reads. We report that Ectocarpus interphase chromatin exhibits a non-Rabl conformation, with strong contacts among telomeres and among centromeres, which feature centromere-specific LTR retrotransposons. The Ectocarpus chromosomes do not contain large local interactive domains that resemble TADs described in animals, but their 3D genome organization is largely shaped by post-translational modifications of histone proteins. We show that the sex determining region (SDR)within the U and V chromosomes are insulated and span the centromeres andwe link sex-specific chromatin dynamics and gene expression levels to the 3D chromatin structure of the U and V chromosomes. Finally, we uncover the unique conformation of a large genomic region on chromosome 6 harboring an endogenous viral element, providing insights regarding the impact of a latent giant dsDNA virus on the host genome's 3D chromosomal folding.

Identification of Genes and Long Non-Coding RNAs Putatively Related to Portunus trituberculatus Sex Determination and Differentiation Using Oxford Nanopore Technology Full-Length Transcriptome Sequencing.

The swimming crab (Portunus trituberculatus) is an economically important species in China, and its growth traits show obvious sexual dimorphism. Thus, it is important to study the mechanism of sex determination and differentiation in this species. Herein, we identified 2138 differentially expressed genes and 132 differentially expressed long non-coding RNAs (lncRNAs) using Oxford Nanopore Technology full-length transcriptome sequencing. We predicted 561 target genes of the differentially expressed lncRNAs according to their location and base pair complimentary principles. Furthermore, pathways related to sex determination, differentiation, and reproduction were enriched for lncRNAs according to gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses. This indicated that lncRNAs might play regulatory roles in these pathways. Our results could form the basis for future studies of sex determination and differentiation in P. trituberculatus.

Vitamin D status, physical activity and long-term mortality risk after myocardial infarction: a prospective analysis in the Alpha Omega Cohort.

In post-myocardial infarction (MI) patients, we examined independent and combined associations of vitamin D status and physical activity (PA) with long-term mortality, including effect modification by health determinants. We conducted a prospective analysis of 4,837 MI patients from the Alpha Omega Cohort. Baseline blood samples (2002-2006) were assessed for plasma 25-hydroxyvitamin D (25[OH]D) levels using LC-MS/MS. PA was assessed using a validated questionnaire. Patients were followed for mortality through December 2022. HRs for CVD and all-cause mortality were obtained across sex-specific tertiles of 25(OH)D and four categories of PA using Cox models, adjusted for sociodemographic and lifestyle factors. Potential effect modification by health determinants was examined through stratification. Patients were 69±5.6 years old, 78% was male, 21% had diabetes, and 10% used vitamin D-containing supplements. Over 14.4 years, 3,206 deaths occurred, including 1,244 from CVD. Median 25(OH)D was 21.1 ng/mL and 44% was vitamin D deficient (<20 ng/mL). Higher 25(OH)D levels were associated with lower CVD (HR:0.63, 95%CI:0.54,0.74) and all-cause mortality (HR:0.68, 95%CI:0.62,0.75). For PA levels (high vs. light), HRs were 0.72 (95%CI:0.61,0.85) for CVD mortality and 0.83 (95%CI:0.75,0.92) for all-cause mortality. Patients with low 25(OH)D and no PA had a threefold higher mortality risk than those with high 25(OH)D levels and high PA. The associations were not significantly modified by sex, comorbidities and other health determinants. Vitamin D status and PA were inversely and independently associated with long-term risk of CVD and all-cause mortality after MI, regardless of other health determinants.

Adult Sex-Ratio Bias Does Not Lead to Detectable Adaptive Offspring Sex Allocation Via Nest-Site Choice in a Turtle With Temperature-Dependent Sex Determination.

Sex-ratio theory predicts that parents can optimise their fitness by producing offspring of the rare sex, yet there is a dearth of empirical evidence for adaptive sex allocation in response to the adult sex ratio (ASR). This is concerning, as anthropogenic disruption of the sex ratios of reproductive individuals threatens to cause demographic collapse in animal populations. Species with environmental sex determination (ESD) are especially at risk but may possess the capacity to adaptively influence offspring sex via control over the developmental environment. For example, reptiles with temperature-dependent sex determination (TSD) could conceivably choose nest sites with thermal characteristics that produce offspring of the rare sex. To test this hypothesis, we seeded three secure outdoor ponds with different sex ratios (~M:F 3:1, 1:1, and 1:3) of adult painted turtles (Chrysemys picta), a reptile species with TSD. We then quantified nesting traits that could influence nest temperature and thus offspring sex ratio, including nesting date, nest depth, and nest canopy cover. We found no directional relationship between the ASR treatments and any measured nest traits and thus rejected our hypothesis. Interestingly, increased maternal body size was associated with reduced nest canopy cover, and this trend was more pronounced in the biased ASR treatments. If adaptive sex allocation occurs in this system, it instead may manifest via maternal epigenetic predisposition of offspring sex or in response to a phenomenon other than the ASR.

CRISPR-Mediated SRY Gene Mutation Increases the Expression of Female Lineage-Specific Gene in Pre-Implantation Buffalo Embryo.

In mammals, sex determination is governed by the SRY gene on the Y chromosome, redirecting gonadal development from forming ovaries to testes. Mutations or alterations in the SRY gene can significantly affect phenotypic changes and lineage-specific markers. This study aims to elucidate the role of the SRY gene in buffalo embryos using CRISPR-Cas9 technology. We designed a crRNA targeting the HMG domain of the SRY gene using the CRISPOR algorithm. Nucleofection of sgRNA-Cas9 RNPs into buffalo fibroblasts confirmed efficient cleavage at the targeted site. Using this validated guide, we investigated the role of the SRY gene in sexual determination by electroporating CRISPR-Cas9-RNPs into single-stage zygotes of buffalo. Genetic changes in the SRY gene were confirmed through sequencing, revealing mosaic blastocysts with multiple alleles and non-mosaic mutants. Mutations in SRY gene increased the expression of female lineage-specific gene Wnt4 whereas decreased the expression of male specific gene SOX9 in blastocysts, suggesting reprogramming towards female sex determination pathways. Our findings provide insights into buffalo sex differentiation mechanisms and potential applications in reproductive strategies for breeding programmes.

Sex-specific mRNA alternative splicing patterns and Dmrt1 isoforms contribute to sex determination and differentiation of oyster

Sex-specific mRNA alternative splicing patterns and Dmrt1 isoforms contribute to sex determination and differentiation of oyster

Re-Equilibrating Sex Ratios: Adjustment of Reaction Norms in Species With Temperature-Dependent Sex Determination.

Fisher's general principle for sex allocation holds that population sex ratios are typically balanced because parents producing the rare sex are benefited and the rare sex alternates over time. In species that have temperature-dependent sex determination (TSD), thermal reaction norms need to be adjusted at the population level to avoid extremely biased sex ratios and extinction. Extant species with TSD experienced drastic climatic changes in the geological past and must necessarily have mechanisms of adaptation. I propose here a conceptual framework to explain how TSD curves could be adjusted by means of natural selection, based on Fisher's equilibrium sex-ratio principle. Through a process that alternatively favors mothers that tend to produce the rare sex under new temperatures, sex ratios eventually return toward a theoretical equilibrium. Prerequisites for this model are variability among mothers in the tendency to produce a particular sex at a given temperature (i.e., variability in the thermal reaction norm), inheritance of this trend, and higher fitness of the rare sex. This straightforward mechanism could facilitate thermal adaptation in species with TSD over multiple generations.

Effects of single or combined exposure to tralopyril and ocean acidification on energy metabolism response and sex development in Pacific oysters (Crassostrea gigas)

The combined effects of the novel antifouling biocide tralopyril (TP) nitrile and ocean acidification (OA) on marine organisms are still not well understood, despite the increasing attention given to the toxic effects of emerging pollutants and OA on marine organisms in recent years. In this study, Crassostrea gigas (C. gigas) was exposed to TP, OA, and a combination of TP and OA for 21 days with a 14-day depuration. This study investigated the inter-tissue variability in energy metabolism responses and the impacts on gonadal development in C. gigas under both single and combined exposures to TP and OA. The results indicate that TP exposure and OA resulted in up-regulation of energy metabolism genes in the C. gigas, with tissues exhibiting enhanced aerobic metabolism. Furthermore, OA influences the sex determination of C. gigas, promoting the development of female individuals. Moreover, following depuration, C. gigas is able to restore normal energy metabolism and sexual development through the accumulation of suitable energy reserves. This study provides a valuable reference for the environmental and ecological risk assessment of TP, addressing the research gap in understanding the combined toxicity of TP and OA on aquatic organisms.

Widespread male sterility and trioecy in androdioecious Mercurialis annua: Its distribution, genetic basis, and estimates of morph-specific fitness components.

Angiosperms range in sexual system from hermaphroditism through gynodioecy and androdioecy to dioecy. Trioecy, where females and males coexist with hermaphrodites, is rare. Recently, trioecy was documented in hexaploid populations of the wind-pollinated herb Mercurialis annua in Spain. We surveyed the frequency of males, hermaphrodites, and females in M. annua across its distribution in the Iberian Peninsula, tracked sex-ratio variation in several populations over consecutive generations, and assessed evidence for pollen limitation. In a common garden, we estimated male, female, and hermaphroditic fitness. We used controlled crosses to infer the genetic basis of male sterility. Finally, we compared predictions of a deterministic model with the distribution of observed sex ratios in the field based on our fitness estimates and the inferred genetics of sex determination. Trioecy is widespread in Spanish and Portuguese populations of M. annua. Males are determined by a dominant (Y-linked) allele, and female expression results from the interaction between cytoplasmic male sterility and multiple nuclear male sterility restorers partially linked to the male determiner. Male pollen production is approximately 12 times that of hermaphrodites, while female seed production is less than 1.12 times the observed hermaphroditic levels. The distribution of sex ratios in natural populations conforms with predictions of our deterministic simulations. Our study documents and accounts for a clear case of trioecy in which sex is determined by both maternally and biparentally inherited genes.

Morphometric Assessment of the Piriform Aperture and Its Clinical and Forensic Applications

Abstract Background: The piriform aperture (PA) is a midface structure that forms the anterior skeletal boundary of the nose. It is highly variant due to its physiological adaptations to the climate. Its variations are useful in forensic identification and reconstructive surgeries of the face. This study aimed at determining the PA’s dimensions and their accuracy in sex determination. Materials and Methods: The PA’s dimensions were retrospectively examined using 336 (199 males and 137 females) adult cranial computed tomography images in the database of the radiology unit of a university teaching hospital in Delta State, Nigeria, following institutional authorization. The aperture’s index was calculated as a ratio of height to width. The data were analyzed using Statistical Package for the Social Sciences Version 23. The sexual dimorphism in the parameters was assessed using an independent t-test. Association among the continuous variables was analyzed by Pearson’s correlation test. P = 0.05 was considered statistically significant. The percentage accuracy for correct sex prediction was assessed using the discriminant function analysis. Results: A significant relationship between dimensions with sex was observed (P &lt; 0.05). The width of the aperture was the best sex-discriminating parameter (70.2%). The overall accuracy for sex discrimination using the aperture’s dimensions was 75.0%. Conclusion: This study provides the standard ranges for the PA’s width and height, valuable for surgical planning. These dimensions were sexually dimorphic and demonstrated an acceptable overall accuracy of correct sex allocation (75%). Consequently, this aperture may be utilized as a supplementary tool in conjunction with other methods for sex determination within studied population.

Identification of genes associated with sex expression and sex determination in hemp (Cannabis sativa L.).

Dioecy in flowering plants has evolved independently many different times, and thus the genetic mechanisms underlying sex determination are diverse. In hemp (Cannabis sativa), sex is controlled by a pair of sex chromosomes (XX for females and XY for males). In an attempt to understand the molecular mechanism responsible for sex expression in hemp plants, we carried out RNA-Seq of male and female plants at different developmental stages. Using a pipeline involving differential gene expression analysis and weighted gene co-expression network analysis, we identified genes important for male and female flower development. We also demonstrate that sex-biased expression is already established at very early vegetative stages, before the onset of reproductive development, and several genes encoding transcription factors of the REM, bZIP and MADS family as candidate sex determination genes in hemp. Our findings demonstrate that the gene regulatory networks governing male and female development in hemp diverge already at a very early stage, leading to profound morphological differences in male and female hemp plants.