Pair Of Regions Research Articles

Genetic Structure of the Vulnerable Tricolored Bat (Perimyotis subflavus)

The tricolored bat (Perimyotis subflavus) has experienced extensive declines in regional abundance — near 30% as of 2013 — due to disease, habitat loss, and anthropogenic conflict. There is urgency to determine whether the species should be protected in the United States; however, critical species-specific information required to make this decision is lacking. Here, we address those critical knowledge gaps by (i) estimating genetic diversity, and (ii) assessing population structure. We utilized sequence data from a 562 base pair region of the mitochondrial genome and eight autosomal microsatellite loci from 14 sampling locations across the core of P. subflavus' range and found substantial diversity in both data types. Further, we found contrasting patterns of population structure between the data types. Weak evidence for population structure was detected using the mitochondrial data, with the most probable population break dividing eastern and western sampling sites, and evidence for isolation-by-distance across the sampled region. Conversely, we detected no evidence for structure or isolation-by-distance using microsatellite data, revealing a panmictic population. The findings reported here represent a baseline understanding of genetic diversity and structure for P. subflavus; additional analyses using samples collected post white-nose syndrome emergence are required to understand losses in genetic diversity due to recent population declines.

Why and how do Y chromosome stop recombining?

Why and how do Y chromosome stop recombining?

RNA sequence to structure analysis from comprehensive pairwise mutagenesis of multiple self-cleaving ribozymes.

Self-cleaving ribozymes are RNA molecules that catalyze the cleavage of their own phosphodiester backbones. These ribozymes are found in all domains of life and are also a tool for biotechnical and synthetic biology applications. Self-cleaving ribozymes are also an important model of sequence-to-function relationships for RNA because their small size simplifies synthesis of genetic variants and self-cleaving activity is an accessible readout of the functional consequence of the mutation. Here, we used a high-throughput experimental approach to determine the relative activity for every possible single and double mutant of five self-cleaving ribozymes. From this data, we comprehensively identified non-additive effects between pairs of mutations (epistasis) for all five ribozymes. We analyzed how changes in activity and trends in epistasis map to the ribozyme structures. The variety of structures studied provided opportunities to observe several examples of common structural elements, and the data was collected under identical experimental conditions to enable direct comparison. Heatmap-based visualization of the data revealed patterns indicating structural features of the ribozymes including paired regions, unpaired loops, non-canonical structures, and tertiary structural contacts. The data also revealed signatures of functionally critical nucleotides involved in catalysis. The results demonstrate that the data sets provide structural information similar to chemical or enzymatic probing experiments, but with additional quantitative functional information. The large-scale data sets can be used for models predicting structure and function and for efforts to engineer self-cleaving ribozymes.

Rapid coherent Raman hyperspectral imaging based on delay-spectral focusing dual-comb method and deep learning algorithm.

Rapid coherent Raman hyperspectral imaging shows great promise for applications in sensing, medical diagnostics, and dynamic metabolism monitoring. However, the spectral acquisition speed of current multiplex coherent anti-Stokes Raman scattering (CARS) microscopy is generally limited by the spectrometer integration time, and as the detection speed increases, the signal-to-noise ratio (SNR) of single spectrum will decrease, leading to a terrible imaging quality. In this Letter, we report a dual-comb coherent Raman hyperspectral microscopy imaging system developed by integrating two approaches, a rapid delay-spectral focusing method and deep learning. The spectral refresh rate is exploited by focusing the relative delay scanning in the effective Raman excitation region, enabling a spectral acquisition speed of 36 kHz, ≈4 frames/s, for a pixel resolution of 95 × 95 pixels and a spectral bandwidth no less than 200 cm-1. To improve the spectral SNR and imaging quality, the deep learning models are designed for spectral preprocessing and automatic unsupervised feature extraction. In addition, by changing the relative delay focusing region of the comb pairs, the detected spectral wavenumber region can be flexibly tuned to the high SNR region of the spectrum.

Se⋯π Chalcogen Bonding in 1,2,4-Selenodiazolium Tetraphenylborate Complexes

The series of substituted 1,2,4-selenodiazolium tetraphenylborate complexes were synthesized via cyclization between 2-pyridylselenylchloride, followed by the anion metathesis, and fully characterized. The utilization of tetraphenylborate anion, a strong π-electron donor via its phenyl rings, promoted the formation of assemblies exhibiting selenium–π interactions. The chalcogen bonding (ChB) interactions involving the π-systems of the tetraphenylborate anion were studied using density functional theory (DFT) calculations, where “mutated” anions were used to estimate the strength of the Se···π chalcogen bonds. Moreover, molecular electrostatic potential (MEP) surfaces were used to investigate the electron-rich and poor regions of the ion pairs. The quantum theory of atoms-in-molecules (QTAIM) and the noncovalent interaction (NCI) plot methods based on the topology of the electron density were used and combined to characterize the ChBs. The investigation reported herein disclosed that the formation of symmetrical dimers can be broken by the introduction of a stronger π-acceptor and, consequently, forming stronger Se···π contacts with selenodiazolium cations.

Small Body, Large Chromosomes: Centric Fusions Shaped the Karyotype of the Amazonian Miniature Fish Nannostomus anduzei (Characiformes, Lebiasinidae).

Miniature refers to species with extraordinarily small adult body size when adult and can be found within all major metazoan groups. It is considered that miniature species have experienced severe alteration of numerous morphological traits during evolution. For a variety of reasons, including severe labor concerns during collecting, chromosomal acquisition, and taxonomic issues, miniature fishes are neglected and understudied. Since some available studies indicate possible relationship between diploid chromosome number (2n) and body size in fishes, we aimed to study one of the smallest Neotropical fish Nannostomus anduzei (Teleostei, Characiformes, Lebiasinidae), using both conventional (Giemsa staining, C-banding) and molecular cytogenetic methods (FISH mapping of rDNAs, microsatellites, and telomeric sequences). Our research revealed that N. anduzei possesses one of the lowest diploid chromosome numbers (2n = 22) among teleost fishes, and its karyotype is entirely composed of large metacentric chromosomes. All chromosomes, except for pair number 11, showed an 18S rDNA signal in the pericentromeric region. 5S rDNA signals were detected in the pericentromeric regions of chromosome pair number 1 and 6, displaying synteny to 18S rDNA signals. Interstitial telomeric sites (ITS) were identified in the centromeric region of pairs 6 and 8, indicating that centric fusions played a significant role in karyotype evolution of studied species. Our study provides further evidence supporting the trend of diploid chromosome number reduction along with miniaturization of adult body size in fishes.

A comparative cytogenetic study of Hypsibarbusmalcolmi and H.wetmorei (Cyprinidae, Poropuntiini).

Cyprininae are a highly diversified but demonstrably monophyletic lineage of cypriniform fishes. Here, the karyotype and chromosomal characteristics of Hypsibarbusmalcolmi (Smith, 1945) and H.wetmorei (Smith, 1931) were examined using conventional, nucleolus organizing regions (NORs) and molecular cytogenetic protocols. The diploid chromosome number (2n) of H.malcolmi was 50, the fundamental number (FN) was equal to 62, and the karyotype displayed 8m + 4sm + 38a with NORs located at the centromeric and telomeric positions of the short arms of chromosome pairs 1 and 2, respectively. 2n of H.wetmorei was 50, FN 78, karyotype 14m + 14sm + 22a with the NORs at the telomeric position of the short arm of chromosome pair 2. 2n and FN in males and females were identical. Fluorescence in situ hybridization using different microsatellite motifs as probes also showed substantial genomic divergence between both studied species. In H.wetmorei, (CAG)n and (CAC)n microsatellites accumulated in the telomeric regions of all chromosomes, while in H.malcolmi, they had scattered signals on all chromosomes. Besides, the (GAA)n microsatellites were distributed along all chromosomes of H.malcolmi, but there was a strong hybridization pattern in the centromeric region of a single pair in H.wetmorei. These cytogenomic difference across the genomes of these Hypsibarbus Rainboth, 1996 species are markers for specific evolutionary differentiation within these two species.

Chromosomal rearrangements and the first indication of an ♀X1 X1 X2 X2 /♂X1 X2 Y sex chromosome system in Rineloricaria fishes (Teleostei: Siluriformes).

Rineloricaria is the most diverse genus within the freshwater fish subfamily Loricariinae, and it is widely distributed in the Neotropical region. Despite limited cytogenetic data, records from southern and south-eastern Brazil suggest a high rate of chromosomal rearrangements in this genus, mirrored in remarkable inter- and intraspecific karyotype variability. In the present work, we investigated the karyotype features of Rineloricaria teffeana, an endemic representative from northern Brazil, using both conventional and molecular cytogenetic techniques. We revealed different diploid chromosome numbers (2n) between sexes (33♂/34♀), which suggests the presence of an ♀X1 X1 X2 X2 /♂X1 X2 Y multiple sex chromosome system. The male-limited Y chromosome was the largest and the only biarmed element in the karyotype, implying Y-autosome fusion as the most probable mechanism behind its origination. C-banding revealed low amounts of constitutive heterochromatin, mostly confined to the (peri)centromeric regions of most chromosomes (including the X2 and the Y) but also occupying the distal regions of a few chromosomal pairs. The chromosomal localization of the 18S ribosomal DNA (rDNA) clusters revealed a single site on chromosome pair 4, which was adjacent to the 5S rDNA cluster. Additional 5S rDNA loci were present on the autosome pair 8, X1 chromosome, and in the presumed fusion point on the Y chromosome. The probe for telomeric repeat motif (TTAGGG)n revealed signals of variable intensities at the ends of all chromosomes except for the Y chromosome, where no detectable signals were evidenced. Male-to-female comparative genomic hybridization revealed no sex-specific or sex-biased repetitive DNA accumulations, suggesting a presumably low level of neo-Y chromosome differentiation. We provide evidence that rDNA sites might have played a role in the formation of this putative multiple sex chromosome system and that chromosome fusions originate through different mechanisms among different Rineloricaria species.

Enhanced topological superconductivity in an asymmetrical planar Josephson junction

As a platform for holding Majorana zero models (MZMs), the two-dimensional planar topological Josephson junction that can be used as carriers for topological quantum computing faces some challenges. One is a combination of mirror and time-reversal symmetries may make the system hold multiple pairs of MZMs. The other is that a soft gap dominated by a large momentum occurs in a clean system. To solve these problems, asymmetric junction can be introduced. Breaking this symmetry changes the symmetry class from class BDI to class D, and only a single pair of MZMs can be left at the boundary of the system. We numerically study four cases that create an asymmetric system and find out different superconducting pairing potential, different coupling coefficients between two-dimensional electron gases (2DEGs) and two superconducting bulks, different widths of two superconducting bulks make the gap of the system decrease at the optimal value, but make the gap at the minimum value increases. And the zigzag-shape quasi-one-dimensional junction eliminates the large momentum parallel to the junction and enhances the gap at the large momentum. However, the zigzag-shape junction cannot increase the gap at the region of multiple pairs of MZMs in a symmetric system. We show that by combining zigzag-shape junction with different coupling coefficients, the system can maintain a large gap (≈0.2Δ) in a wide region of the parameter space.

Gene knockdown by structure defined single-stem loop small non-coding RNAs with programmable regulatory activities

Gene regulation by trans-acting small RNAs (sRNAs) has considerable advantages over other gene regulation strategies. However, synthetic sRNAs mainly take natural sRNAs (MicC or SgrS) as backbones and comprise three functional elements folding into two or more stem-loop structures: an mRNA base pairing region, an Hfq-binding structure, and a rho-independent terminator. Due to limited numbers of natural sRNAs and complicated backbone structures, synthetic sRNAs suffer from low activity programmability and poor structural modularity. Moreover, natural sRNA backbone sequences may increase the possibility of unwanted recombination. Here, we present a bottom-up approach for creating structure defined single-stem loop small non-coding RNAs (ssl-sRNAs), which contain a standardized scaffold of a 7 bp-stem-4 nt-loop-polyU-tail and a 24 nt basing pairing region covering the first eight codons. Particularly, ssl-sRNA requires no independent Hfq-binding structure, as the polyU tail fulfills the roles of binding Hfq. A thermodynamic-based scoring model and a web server sslRNAD (http://www.kangzlab.cn/) were developed for automated design of ssl-sRNAs with well-defined structures and programmable activities. ssl-sRNAs displayed weak polar effects when regulating polycistronic mRNAs. The ssl-sRNA designed by sslRNAD showed regulatory activities in both Escherichia coli and Bacillus subtilis. A streamlined workflow was developed for the construction of customized ssl-sRNA and ssl-sRNA libraries. As examples, the E. coli cell morphology was easily modified and new target genes of ergothioneine biosynthesis were quickly identified with ssl-sRNAs. ssl-sRNA and its designer sslRNAD enable researchers to rapidly design sRNAs for knocking down target genes.

Comparative molecular cytogenetics in five species of stingless bees (Hymenoptera, Apidae)

Repetitive DNA sequences constitute a large portion of the eukaryotic genome. Despite their importance, only a few Meliponini species, especially those from the Melipona Illiger, 1806 genus, had some microsatellite sequences and the rDNA genes physically mapped. Therefore, in order to expand our knowledge on this genomic component of neotropical bees, in the present study we investigated the distribution of microsatellite sequences, including the telomeric repeat (TTAGG)6 and rDNA clusters, in the chromosomes of five stingless species, Cephalotrigona capitata (Smith, 1854), Partamona auripennis Pedro & Camargo, 2003, P. cupira (Smith, 1863), P. helleri (Friese 1900), and Tetragona elongata (Lepeletier & Serville, 1828). The microsatellite probes (GA)15, (GAG)10, and (CAA)10, revealed hybridization signals in the euchromatic regions of most chromosome pairs. The (GAG)10 probe, however, also yielded a positive signal in the heterochromatic arm of one chromosome pair of T. elongata. The telomeric (TTAGG)6 sequence hybridized to the ends of chromosome pairs, while signals for the 18S rDNA probe varied among the species. Here was demonstrated the karyotypic diversity that exists among five species of stingless bees in terms of repetitive sequences. These cytogenetic marker provides new information about the chromatin composition and rDNA cluster locations for five Meliponini species (three genera) and highlights the contribution of repetitive sequences to the karyotypic evolution of this tribe.

An in vitro and computational validation of a novel loss-of-functional mutation in PAX9 associated with non-syndromic tooth agenesis.

Congenital tooth agenesis (CTA) is one of the most common craniofacial anomalies. Its frequency varies among different population depending upon the genetic heterogeneity. CTA could be of familial or sporadic and syndromic or non-syndromic. Five major genes are found to be associated with non-syndromic CTA, namely PAX9, MSX1, EDA1, AXIN2, and WNT10A. Very few studies have been carried out so far on CTA on this Indian population making this study unique and important. This study was initiated to identify potential pathogenic variant associated with congenital tooth agenesis in an India family with molar tooth agenesis. CTA was investigated and a novel c.336C > G variation was identified in the exon 3 of PAX9, leading to substitution of evolutionary conserved Cys with Trp at 112th amino acid position located at the functionally significant DNA-binding paired domain region. Functional analysis revealed that p.Cys112Trp mutation did not prevent the nuclear localization although mutant protein had higher cytoplasmic retention. EMSA using e5 probe revealed that mutant protein was unable to bind with the paired-domain-binding site. Subsequently, GST pull-down assay revealed lower binding activity of the mutant protein with its known interactor MSX1. These in vitro results were consistent with the computational results. The in vitro and computational observations altogether suggest that c.336C > G (p.Cys112Trp) variation leads to loss of function of PAX9 leading to CTA in this family.

Preoperative Brain Functional Connectivity Improve Predictive Accuracy of Outcomes After Revascularization in Moyamoya Disease.

In patients with moyamoya disease (MMD), focal impairments in cerebral hemodynamics are often inconsistent with patients' clinical prognoses. Evaluation of entire brain functional networks may enable predicting MMD outcomes after revascularization. To investigate whether preoperative brain functional connectivity could predict outcomes after revascularization in MMD. We included 34 patients with MMD who underwent preoperative MRI scanning and combined revascularization surgery. We used region of interest analyses to explore the differences in functional connectivity for 90 paired brain regions between patients who had favorable outcomes 1 year after surgery (no recurrent stroke, with improved preoperative symptoms, or modified Rankin Scale [mRS]) and those who had unimproved outcomes (recurrent stroke, persistent symptoms, or declined mRS). Variables, including age, body mass index, mRS at admission, Suzuki stage, posterior cerebral artery involvement, and functional connectivity with significant differences between the groups, were included in the discriminant function analysis to predict patient outcomes. Functional connectivity between posterior cingulate cortex and paracentral lobule within the right hemisphere, and interhemispheric connection between superior parietal gyrus and middle frontal gyrus, precuneus and middle cingulate cortex, cuneus and precuneus, differed significantly between the groups (P < .001, false discovery rate corrected) and had the greatest discriminant function in the prediction model. Although clinical characteristics of patients with MMD showed great accuracy in predicting outcomes (64.7%), adding information on functional connections improved accuracy to 91.2%. Preoperative functional connectivity derived from rs-fMRI may be an early hallmark for predicting patients' prognosis after revascularization surgery for MMD.

Multi-temporal orthophoto and digital surface model registration produced from UAV imagery over an agricultural field

Correcting the three-dimensional geometric error is essential to effectively use the multi-temporal unmanned aerial vehicle (UAV) orthophoto and digital surface model (DSM) acquired from the agricultural field. Although ground control points (GCPs) obtained through field surveys are usually used to calibrate geometrical errors establishing/maintaining GCPs and surveying them in the field are time-consuming and inefficient. Therefore, we propose a simple and efficient methodology to improve the geometric registration of multi-temporal orthophotos and DSMs without GCPs. In the proposed method, coarse to fine image registration is performed first, which corrects severe to slight errors by sequential feature and area-based matching methods. Subsequently, we extract height-invariant regions in multi-temporal DSM pairs, called elevation invariant feature (EIF), using the EIFs to register DSMs by estimating a linear regression model. Various experiments were conducted to analyze the absolute and relative accuracies using ten multi-temporal orthophotos and DSMs, and the robustness of the proposed method was evaluated using data obtained from another site. The experimental results demonstrate that the geometric quality of registered orthophotos and DSMs was significantly improved.

First Report on Classical and Molecular Cytogenetics of Doi Inthanon Bent-toed Gecko, Cyrtodactylus inthanon Kunya et al., 2015 (Squamata: Gekkonidae) in Thailand

This study analyzed the karyotype of Cyrtodactylus inthanon Kunya et al., 2015 from Doi Inthanon, Chiang Mai Province, northern Thailand. The metaphase and meiotic chromosome preparations were obtained by squash technique from bone marrow and testes, respectively. The chromosomes were stained by Giemsa staining, Ag-NOR banding and molecular cytogenetics with ?uorescence in situ hybridization (FISH) using microsatellites d(CA)15, d(GC)15, d(CAG)10 and d(GAA)10 as probes. The results showed the diploid chromosome number (2n) of 40. The chromosome types of metacentric, submetacentric, acrocentric and telocentric chromosomes were 12-4-2-22, respectively. The Ag-NORs banding technique provides the pair of nucleolar organizer regions (NORs) on the telomeric region of the long arm of acrocentric pair 12. There are no sex differences in karyotypes between males and females. We also found that during metaphase I on meiosis of C. inthanon, the homologous chromosomes appeared synapsis of 20 bivalents. The microsatellite d(CA)15 signals were located on the sub-centromeric region of the metacentric pair 10, whereas the d(GC)15, d(CAG)10 and d(GAA)10 repeats are highly accumulated throughout almost all entire chromosomes. The karyotype formula is as follows: C. inthanon (2n = 40), Lm2 + Lsm4 + Lt6 + Mm2 + Mt8 + Sm8 + Sa2 + St8.

Chromosomal description of three Dixonius (Squamata, Gekkonidae) from Thailand

Chromosomal characteristics and karyological analysis of three Dixonius, including D. hangseesom, D. siamensis and D. melanostictus, from Thailand were studied. Chromosome preparations were conducted by squash technique from bone marrow and testis. Conventional Giemsa’s staining and Ag-NOR banding techniques were applied to stain the chromosome. The results showed that the diploid chromosomes are 2n=40, for D. hangseesom and D. siamensis; and 2n=42, for D. melanostictus. The fundamental number (NF) is 42 in D. hangseesom and D. siamensis and 44 in D. melanostictus. The types of chromosomes were 2 metacentrics and 38 telocentrics for D. hangseesom and D. siamensis, while the karyotype of D. melanostictus comprised 2 acrocentrics and 40 telocentrics. In the D. hangseesom and D. siamensis, NORs are located to the near centromere on long arm of the telocentric chromosome pair 13. Although, the NORs of D. melanostictus are situated on the subtelomeric region of telocentric chromosome pair 8. There are no sex differences in karyotypes between males and females of these three geckos species. We found that during metaphase I and metaphase II on male meiosis of the D. hangseesom and D. siamensis, the homologous chromosomes showed synapsis of 20 bivalents and 20 haploid chromosomes (n=20). Moreover, metaphase I and metaphase II of the male D. melanostictus showed synapsis of 21 bivalents and 21 haploid chromosomes (n=21). Their karyotype formulas is as follows: D. hangseesom (2n=40): Lm2 + Lt2 + Mt4 + St32, D. siamensis (2n=40): Lm2 + Lt6 + Mt4 + St28, and D. melanostictus (2n=42): La2 + Lt12 + Mt4 + St24.

Characterization of Neutralizing Human Anti-Tetanus Monoclonal Antibodies Produced by Stable Cell Lines.

Tetanus toxin (TeNT) is produced by C. tetani, a spore-forming bacillus broadly spread in the environment. Although an inexpensive and safe vaccine is available, tetanus persists because of a lack of booster shots and variable responses to vaccines due to immunocompromised status or age-decreased immune surveillance. Tetanus is most prevalent in low- and medium-income countries, where it remains a health problem. Neutralizing monoclonal antibodies (mAbs) can prevent the severity of illness and death caused by C. tetani infection. We identified a panel of mAbs that bind to TeNT, some of which were investigated in a preclinical assay, showing that a trio of mAbs that bind to different sites of TeNT can neutralize the toxin and prevent symptoms and death in mice. We also identified two mAbs that can impair the binding of TeNT to the GT1b ganglioside receptor in neurons. In this work, to generate a series of cell lines, we constructed vectors containing sequences encoding heavy and light constant regions that can receive the paired variable regions resulting from PCRs of human B cells. In this way, we generated stable cell lines for five mAbs and compared and characterized the antibody produced in large quantities, enabling the characterization experiments. We present the results regarding the cell growth and viability in a fed-batch culture, titer measurement, and specific productivity estimation. The affinity of purified mAbs was analyzed by kinetics and under steady-state conditions, as three mAbs could not dissociate from TeNT within 36,000 s. The binding of mAbs to TeNT was confirmed by ELISA and inhibition of toxin binding to GT1b. The use of the mAbs mixture confirmed the individual mAb contribution to inhibition. We also analyzed the binding of mAbs to FcγR by surface plasmon resonance (SPR) and the glycan composition. Molecular docking analyses showed the binding site of an anti-tetanus mAb.

Tissue-specific transcriptomic analysis uncovers potential roles of natural antisense transcripts in Arabidopsis heat stress response.

Natural antisense transcripts (NATs) are an important class of non-coding ribonucleic acids (RNAs) that have been shown to regulate gene expression. Using strand-specific RNA sequencing, 36,317 NAT pairs were identified, and 5,536 were specifically expressed under heat stress. We found distinct expression patterns between vegetative and reproductive tissues for both coding genes and genes encoding NATs. Genes for heat-responsive NATs are associated with relatively high levels of H3K4me3 and low levels of H3K27me2/3. On the other hand, small RNAs are significantly enriched in sequence overlapping regions of NAT pairs, and a large number of heat-responsive NATs pairs serve as potential precursors of nat-siRNAs. Collectively, our results suggest epigenetic modifications and small RNAs play important roles in the regulation of NAT expression, and highlight the potential significance of heat-inducible NATs.

Rate-energy region of MIMO systems with sustainable intelligent reflecting surface

We consider MIMO systems with self-sustainable intelligent reflecting surface (IRS), where IRS can harvest energy from received power. We characterize the achievable region of rate-energy pairs and propose an alternating optimization algorithm to try to achieve its boundary points. We apply the coordinate descent method to find the optimal reflecting coefficients and provide the closed-form expression to each subproblem. Numerical results show that the proposed algorithm archives higher rate than the other algorithms for given required harvested energy.

ZW sex-chromosome evolution and contagious parthenogenesis in Artemia brine shrimp.

Eurasian brine shrimp (genus Artemia) have closely related sexual and asexual lineages of parthenogenetic females, which produce rare males at low frequencies. Although they are known to have ZW chromosomes, these are not well characterized, and it is unclear whether they are shared across the clade. Furthermore, the underlying genetic architecture of the transmission of asexuality, which can occur when rare males mate with closely related sexual females, is not well understood. We produced a chromosome-level assembly for the sexual Eurasian species Artemia sinica and characterized in detail the pair of sex chromosomes of this species. We combined this new assembly with short-read genomic data for the sexual species Artemia sp. Kazakhstan and several asexual lineages of Artemia parthenogenetica, allowing us to perform an in-depth characterization of sex-chromosome evolution across the genus. We identified a small differentiated region of the ZW pair that is shared by all sexual and asexual lineages, supporting the shared ancestry of the sex chromosomes. We also inferred that recombination suppression has spread to larger sections of the chromosome independently in the American and Eurasian lineages. Finally, we took advantage of a rare male, which we backcrossed to sexual females, to explore the genetic basis of asexuality. Our results suggest that parthenogenesis is likely partly controlled by a locus on the Z chromosome, highlighting the interplay between sex determination and asexuality.