Deciphering the Mechanism of Glyphosate Resistance in Amaranthus palmeri by Cytogenomics

In agriculture, various chemicals are used to control the weeds. Out of which, glyphosate is an important herbicide invariably used in the cultivation of glyphosate-resistant crops to control weeds. Overuse of glyphosate results in the evolution of glyphosate-resistant weeds. Evolution of glyphosate resistance (GR) in <i>Amaranthus palmeri</i> (AP) is a serious concern in the USA. Investigation of the mechanism of GR in AP identified different resistance mechanisms of which <i>5-enolpyruvylshikimate-3-phosphate synthase</i> (<i>EPSPS</i>) gene amplification is predominant. Molecular analysis of GR AP identified the presence of a 5- to &#x3e;160-fold increase in copies of the <i>EPSPS</i> gene than in a glyphosate-susceptible (GS) population. This increased copy number of the <i>EPSPS</i> gene increased the genome size ranging from 3.5 to 11.8%, depending on the copy number compared to the genome size of GS AP. FISH analysis using a 399-kb <i>EPSPS</i> cassette derived from bacterial artificial chromosomes (BACs) as probes identified that amplified <i>EPSPS</i> copies in GR AP exist in extrachromosomal circular DNA (eccDNA) in addition to the native copy in the chromosome. The <i>EPSPS</i> gene-containing eccDNA having a size of ∼400 kb is termed <i>EPSPS</i>-eccDNA and showed somatic mosacism in size and copy number. <i>EPSPS</i>-eccDNA has a genetic mechanism to tether randomly to mitotic or meiotic chromosomes during cell division or gamete formation and is inherited to daughter cells or progeny generating copy number variation. These eccDNAs are stable genetic elements that can replicate and exist independently. The genomic characterization of the <i>EPSPS</i> locus, along with the flanking regions, identified the presence of a complex array of repeats and mobile genetic elements. The cytogenomics approach in understanding the biology of <i>EPSPS</i>-eccDNA sheds light on various characteristics of <i>EPSPS</i>-eccDNA that favor GR in AP.

Novel Centromeric and Subtelomeric Repetitive DNA Sequences for Karyotyping the Bambara Groundnut (Vigna subterranea L. Verdc.)

Bambara groundnut (<i>Vigna subterranea</i> L. Verdc.) is an un­derutilized minor legume crop with climate resilience and great potential use in world agriculture. This study aimed to cytogenetically characterize the genome and chromosome properties of Bambara groundnut. We cloned, sequenced, and mapped a 50-bp centromere-specific tandem repeat on all chromosomes. In addition, a 400-bp subtelomeric repeat was discovered and mapped on a single pair of chromosomes. A Bambara groundnut karyotype was constructed using these novel repeats along with ribosomal RNA genes (45S and 5S) and telomeric DNA sequences. This study provides the first analysis of the genome and chromosome properties of Bambara groundnut. We discuss our findings in relation to genetic improvement of Bambara groundnut and centromere evolution in legume species.

Cleft Lip Palate in a Patient with 5q14.3 Deletion Syndrome: A Possible Unreported Feature?

5q14.3 deletion syndrome (MIM#613443) is an uncommon but well-known syndrome characterized by intellectual disability, epilepsy, hypotonia, brain malformations, and facial dysmorphism. Most patients with this syndrome have lost one copy of the <i>MEF2C</i> gene (MIM*600662), whose haploinsufficiency is considered to be responsible for the distinctive phenotype. To date, nearly 40 cases have been reported; the deletion size and clinical spectrum are variable, and at least 6 cases without <i>MEF2C</i> involvement have been documented. We herein report the clinical and cytogenomic findings of an 11-year-old girl who has a 5q14.3q21.1 de novo deletion that does not involve <i>MEF2C</i> but shares the clinical features described in other reported patients. Moreover, she additionally presents with bilateral cleft-lip palate (CLP), which has not been previously reported as a feature of the syndrome. The most frequent syndromic forms of CLP were ruled out in our patient mainly by clinical examination, and Sanger sequencing was performed to discard the presence of a <i>TBX22</i> gene (MIM*300307) defect. Our report suggests CLP as a possible unreported feature and redefines the critical phenotypic regions of 5q14.3 deletion syndrome.

Silencing of miR-1246 Induces Cell Cycle Arrest and Apoptosis in Cisplatin-Resistant Ovarian Cancer Cells by Promoting ZNF23 Transcription

Ovarian cancer (OC) is the most frequent cause of death among patients with gynecologic malignancies. In recent years, the development of cisplatin (DDP) resistance has become an important reason for the poor prognosis of OC patients. Therefore, it is vital to explore the mechanism of DDP resistance in OC. In this study, microRNA-1246 (miR-1246) expression in OC and DDP-resistant OC cells was determined by RT-qPCR, and chemosensitivity to DDP was assessed by the CCK-8 assay. A dual-luciferase reporter assay was performed to confirm the interaction between miR-1246 and zinc finger 23 (<i>ZNF23</i>), while changes in <i>ZNF23</i> expression were monitored by RT-qPCR, immunofluorescence, and western blot assays. Moreover, cell proliferation, cycle phase, and apoptosis were determined by EdU staining, flow cytometry, TUNEL staining, and Hoechst staining. Our data showed that miR-1246 was highly expressed in DDP-resistant OVCAR-3 and TOV-112D cells. Functionally, overexpression of miR-1246 markedly enhanced DDP resistance and cell proliferation, and suppressed cell cycle arrest and apoptosis of OC cells. Inhibition of miR-1246 expression significantly attenuated DDP resistance and cell proliferation, and increased cell cycle arrest and apoptosis in DDP-resistant OC cells. Furthermore, <i>ZNF23</i> was identified as a target gene of miR-1246, and ZNF23 protein expression was notably downregulated in DDP-resistant OC cells. Moreover, overexpression of miR-1246 significantly downregulated the <i>ZNF23</i> levels in OVCAR-3 and TOV-112D cells, and inhibition of miR-1246 upregulated the <i>ZNF23</i> levels in the DDP-resistant OVCAR-3 and TOV-112D cells. In conclusion, miR-1246 might be a novel regulator of DDP-resistant OC that functions by regulating <i>ZNF23</i> expression in DDP-resistant cells, as well as cell proliferation, cell cycle progression, and apoptosis.

Chromosome Evolution in the Genus Partamona (Apidae: Meliponini), with Comments on B Chromosome Origin

The genus <i>Partamona</i> includes 33 species of stingless bees, of which 11 were studied cytogenetically. The main goal of this study was to propose a hypothesis about chromosomal evolution in <i>Partamona</i> by combining molecular and cytogenetic data. Cytogenetic analyses were performed on 3 <i>Partamona</i> species. In addition, the molecular phylogeny included mitochondrial sequences of 11 species. Although the diploid number was constant within the genus, 2n = 34, B chromosomes were reported in 7 species. Cytogenetic data showed karyotypic variations related to chromosome morphology and the amount and distribution of heterochromatin and repetitive DNA. The molecular phylogenetic reconstruction corroborated the monophyly of the genus and separated the 2 clades (A and B). This separation was also observed in the cytogenetic data, in which species within each clade shared most of the cytogenetic characteristics. Furthermore, our data suggested that the B chromosome in the genus <i>Partamona</i> likely originated from a common ancestor of the species that have it in clade B and, through interspecific hybridization, it appeared only in <i>Partamona rustica</i> from clade A. Based on the above, <i>Partamona</i> is an interesting genus for further investigations using molecular mapping of B chromosomes as well as for broadening phylogenetic data.

An Anomaly with Potential as a New Prognostic Marker in CLL with del(13q): Gain of 16p13.3

Deletion 13q [del(13q)] is a favorable prognostic marker if it is detected as a sole abnormality in chronic lymphocytic leukemia (CLL). However the clinical courses of cases with isolated del(13q) are quite heterogeneous. In our study, we investigated copy number variations (CNVs), loss of heterozygosity (LOH), and the size of del(13q) in 30 CLL patients with isolated del(13q). We used CGH+SNP microarrays in order to understand the cause of this clinical heterogeneity. We detected del(13q) in 28/30 CLL cases. The size of the deletion varied from 0.34 to 28.81 Mb, and there was no clinical effect of the deletion size. We found new prognostic markers, especially the gain of 16p13.3. These markers have statistically significant associations with short time to first treatment and advanced disease stage. Detecting both CNVs and LOH at the same time is an advantageous feature of aCGH+SNP. However, it is very challenging for the array analysis to detect mosaic anomalies. Therefore, it is very important to confirm the results by FISH. In our study, we detected approximately 9% mosaic del(13q) by microarray. In addition, the gain of 16p13.3 may affect the disease prognosis in CLL. However, additional studies with more patients are needed to confirm these results.

Methylation Status of the miR-141-3p Promoter Regulates miR-141-3p Expression, Inflammasome Formation, and the Invasiveness of HTR-8/SVneo Cells

MicroRNA-141 (miR-141-3p) is upregulated in preeclampsia. This study investigated the effect of methylation of the miR-141-3p promoter on cell viability, invasion capability, and inflammasomes in vitro. The expression of miR-141-3p and methylation status of the miR-141-3p promoter were examined by RT-qPCR and pyrosequencing in villus tissues of women with spontaneous delivery (VTsd), villus tissues of women with preeclampsia (VTpe), and also in HTR-8/SVneo cells treated with a miR-141-3p inhibitor and 20 μmol/L 5-aza-2′-deoxycytidine (5-Aza), a DNA methyltransferase inhibitor. Cell viability and invasion were evaluated by CCK-8 and transwell assays. In addition, the levels of CXCL12, CXCR4, CXCR2, MMPs, NLRP3, and ASC expression were assessed by western blotting, and IL-1β and IL-18 concentrations were assayed by ELISA. miR-141-3p expression was upregulated, and the levels of miR-141-3p promoter methylation and CXCL12, CXCR4, and CXCR2 expression were decreased in VTpe relative to VTsd. In HTR-8/SVneo cells, hypomethylation caused by 5-Aza treatment increased miR-141-3p expression, while DNA methyltransferase 3 (DNMT3) transfection decreased miR-141-3p expression. miRNA-141-3p induced NLRP3, IL-1β, and IL-18 production, decreased CXCR4, MMP, and MMP2 production, and suppressed cell growth and invasion. Furthermore, we observed that NLRP3 plays an important mediatory role in the effects of miR-141-3p described above. Decreased methylation of the miR-141-3p promoter increases miR-141-3p expression, which in turn increases NLRP3 expression, resulting in higher IL-1β and IL-18 levels and lower levels of MMP2/9 and CXCR4. We conclude that modification of the miR-141-3p promoter might be a curial mediator in preeclampsia.

Novel SNX13 Frameshift Variant in an Individual with Developmental Delay

Recently, an increasing number of genes have been associated with global developmental delay (GDD) and intellectual disability (ID). The sorting nexin (SNX) protein family plays multiple roles in protein trafficking and intracellular signaling. SNXs have been reported to be associated with several disorders, including Alzheimer disease and Down syndrome. Despite the growing evidence of an association of SNXs with neurodegeneration, SNX13 deficiency has not been associated with GDD or ID. In this study, we present the case of a 4-year-old boy with brain dysplasia and GDD, including language delay, cognitive delay, and dyskinesia. Exome sequencing revealed a 1-bp homozygous deletion in <i>SNX13</i> (NM_015132.5: exon8: c.742_743del; p.Tyr248Leufs*20), which caused a frameshift and predicted early termination. Sanger sequencing confirmed that the variant was inherited from his parents respectively. Our findings associate <i>SNX13</i> variation with GDD for the first time and provide a new GDD candidate gene.

One Hundred Years of Gene Balance: How Stoichiometric Issues Affect Gene Expression, Genome Evolution, and Quantitative Traits

A century ago experiments with the flowering plant <i>Datura stramonium</i> and the fruit fly <i>Drosophila melanogaster</i> revealed that adding an extra chromosome to a karyotype was much more detrimental than adding a whole set of chromosomes. This phenomenon was referred to as gene balance and has been recapitulated across eukaryotic species. Here, we retrace some developments in this field. Molecular studies suggest that the basis of balance involves stoichiometric relationships of multi-component interactions. This concept has implication for the mechanisms controlling gene expression, genome evolution, sex chromosome evolution/dosage compensation, speciation mechanisms, and the underlying genetics of quantitative traits.

Molecular Cytogenetic Classification of Down Syndrome and Screening of Somatic Aneuploidy in Mothers

Down Syndrome (DS) caused by trisomy 21 results in various congenital and developmental complications in children. It is crucial to cytogenetically diagnose the DS cases early for their proper health management and to reduce the risk of further DS childbirths in mothers. In this study, we performed a cytogenetic analysis of 436 suspected DS cases using karyotyping and fluorescent in situ hybridization. We detected free trisomies (95.3%), robertsonian translocations (2.4%), isochromosomes (0.6%), and mosaics (1.2%). We observed a slightly higher incidence of DS childbirth in younger mothers compared to mothers with advanced age. We compared the somatic aneuploidy in peripheral blood of mothers having DS children (MDS) and control mothers (CM) to identify biomarkers for predicting the risk for DS childbirths. No significant difference was observed. After induced demethylation in peripheral blood cells, we did not observe a significant difference in the frequency of aneuploidy between MDS and CM. In conclusion, free trisomy 21 is the most common type of chromosomal abnormality in DS. A small number of DS cases have translocations and mosaicism of chromosome 21. Additionally, somatic aneuploidy in the peripheral blood from the mother is not an effective marker to predict DS childbirths.