Biology subjects

Jonker, M. J.

Publications and source records attributed to Jonker, M. J..

At least 19 recordsLinked to original sources

bioRxiv2026

Pervasive short hairpin folding in non-encapsidated RNA viruses

Genome-wide RNA secondary structure can influence viral replication, stability, translation, and interactions with host defenses, yet its distribution and significance across RNA viruses remain poorly understood. We developed the pervasive hairpin (peHaPi) metric to quantify densely distributed stem-loop structures and applied it to 817,234 GenBank virus sequences. This revealed a distinctive RNA architecture characterized by numerous short, highly uniform hairpins spanning most of the genome. The structure was strongly enriched in capsidless RNA viruses, encompassing nearly all ormycoviruses and a substantial fraction of narnaviruses, although it also occurred in several other RNA and DNA virus groups. Comparative analyses showed that increasing peHaPi scores appeared associated with more stable and constrained predicted RNA structures and altered codon base-pairing patterns, indicating selective constraints imposed by pervasive folding. Relationships between peHaPi and RdRp sequence similarity differed among virus groups, consistent with independent evolutionary origins of this structural phenotype. Analysis of virus-derived small RNAs provided no evidence that peHaPi(+) viruses elicit a reduced siRNA response, arguing against siRNA evasion as its primary function. Finally, combining peHaPi classification with DNA-read subtraction identified candidate RNA virus contigs lacking detectable protein homology or recognizable RdRp signatures across multiple independent datasets. These findings reveal pervasive short-hairpin organization as a novel feature of predominantly capsidless viruses and establish genome-wide RNA structure as a complementary signature for discovering highly divergent ormyco- and narnaviruses.

microbiology↗

bioRxiv2026

Modulation of rob expression accelerates development of antibiotic resistance in Yersinia enterocolitica

Multidrug-resistant bacteria pose a severe threat to global health. Mutations in transcriptional regulators accelerate the emergence of multidrug resistance and may have a crucial impact on pathogen evolvability under antibiotic exposure. Here, we investigate these dynamics in the bacterial pathogen Yersinia enterocolitica. In this organism, we identified a high-frequency de novo mutation in the promoter of an AraC/XylS-family transcriptional regulator, Rob. This mutation arose independently during resistance evolution against three of six antibiotic classes. Sequence and structure alignments indicate that Rob is a previously uncharacterized, lineage-specific regulator in Y. enterocolitica, featuring a conserved promoter architecture. This promoter mutation resulted in robust rob overexpression, leading to the activation of multiple downstream efflux- and membrane-associated pathways. This regulatory mutation emerges early and shapes the acquisition of tetracycline resistance, while also enhancing high-level enrofloxacin resistance in combination with canonical mutations in gyrA and parC. Despite being favored under antibiotic selection, rob overexpression is costly, resulting in counter-selection of the -57 G>A rob allele in the absence of antibiotics. Together, these findings identify Rob as a Yersinia-specific efflux regulator and demonstrate how regulatory mutations can transiently accelerate antibiotic resistance. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/707304v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@107aa88org.highwire.dtl.DTLVardef@4ccd66org.highwire.dtl.DTLVardef@411e2aorg.highwire.dtl.DTLVardef@1235fbc_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2025

Extreme GC3 Codon Bias in a Novel Brown Seaweed Virus Results in Pseudoambigrammatic Characteristics

Although viruses are often studied in relation to disease, they can also offer valuable insights into RNA functionality. Due to their vast range of hosts and high mutation rates, viruses can quickly adapt to changing environments. It is therefore expected that viruses exploit all possible RNA functionalities to develop strategies for host infection and propagation. Our aim is to discover RNA viruses with survival strategies that reveal unknown RNA characteristics and functionalities. We have chosen seaweed as host organism because relatively little is known about RNA viruses in seaweed. Additionally, seaweeds are evolutionary distant from terrestrial plants and inhabit environments with entirely different conditions, increasing the likelihood of discovering new RNA viruses with unknown survival strategies. Here we report a new, unclassified negative-stranded single-strand RNA virus from seaweed Saccharina latissima that showed a unique genome characteristic. The novel virus, named SalaUV-NL1, contains a large segment of 7.065 nucleotides coding for a 2.296 amino acids protein and a small segment of 2.120 nucleotides coding for a 328 plus a potential 315+ amino acids protein. The large segment also appeared to have an additional large open reading frame (ORF) on the negative strand, suggesting it could be an ambigrammatic virus. However, the virus displayed an extreme GC3 codon bias (98%) in the (+)ORF, which differs from the typical avoidance of just the reverse-complement stop codons seen in ambigrammatic viruses. Consequently, the (-)ORF appears to occur accidental and is unlikely to encode a functional protein. Therefore, we have termed our virus to be pseudoambigrammatic. Several other viruses with the same pseudogrammatic high GC3 codon bias were identified in Genbank, most without a (-)ORF. The SalaUV-NL1 virus codon bias surpasses the high GC3 codon bias of the S. latissima host genes, however other species that host pseudoambigrammatic viruses do not display a high GC3 codon bias. Comparison of several variants of SalaUV-NL1 showed that the relative nucleotide change rate, particularly for silent changes from A/T to G/C, was extremely high (up to 81%). This novel virus demonstrates a new survival strategy of RNA viruses that is not yet understood.

genomics↗

bioRxiv2025

Driving factors for beta-lactam resistance gene amplification during de novo resistance evolution in E. coli

Long-term exposure of E. coli to non-lethal step-wise increasing concentrations of beta-lactam antibiotics induces high levels of resistance that can be accompanied by amplification of a chromosomal fragment around the ampC gene. We compared the amplification of the ampC fragment in the wildtype, an ampC knockout mutant, a mutant in which the ampC gene was replaced by a tetracycline resistance gene tet(B)and a strain in which the ampC has been translocated. When ampC was removed, no amplification occurred at the original ampC location, but DNA fragments were amplified around the genes coding for efflux pump AcrAB and the multiple antibiotic resistance operon MarRAB. When tet(B) replaced ampC, exposure to tetracycline induced amplification of comparable fragments, while exposure to amoxicillin induced duplication of a larger fragment elsewhere. When ampC was translocated, a fragment around it at the new location was amplified. The importance of the presence but not of the location within the chromosome of the resistance genes for the amplification process indicates that the mechanisms are neither gene nor location specific. Without the relatively efficient resistance gene ampC, duplication and amplification occur around acrAB and marRAB that code for amoxicillin and tetracycline resistance factors. These duplications and amplifications are prevented by ampC amplification.

microbiology↗

bioRxiv2024

Collateral sensitivity and cross resistance in six species of bacteria exposed to six classes of antibiotics

De novo resistance can be developed in bacteria because of exposure to sublethal concentrations of antibiotics. Once the strain has become resistant to an initial antibiotic, this can cause cross-resistance or collateral sensitivity to a second antimicrobial. Specific collateral sensitivity is rarely conserved across species because the mechanisms triggered in different microorganisms to resist antibiotics are often different. In this study, we explored which collateral sensitivity or cross resistance networks are present in six species of bacteria with induced de novo-resistance. These six species were induced to become resistant to amoxicillin/cefepime, enrofloxacin, kanamycin, tetracycline, erythromycin and chloramphenicol(1). After that, the collateral sensitivity and the cross-resistance networks were evaluated by measuring increase or decrease of MIC of thirteen antibiotics that are often used in the clinic. Collateral sensitivity for kanamycin occurred in five species of strains resistant to chloramphenicol and tetracycline and for {beta}-lactam in strains of five species resistant to kanamycin. Further genetic analysis clarified that fusA consistently mutated in five species of bacteria made de novo resistant against kanamycin, suggesting that fusA operates in parallel with the other mechanisms related to antimicrobial resistance Based on considerations of resistance, a treatment protocol starting with chloramphenicol/tetracycline, followed by kanamycin and ending with amoxicillin may eliminate bacteria that have developed resistance against the initial treatment.

microbiology↗

bioRxiv2024

Discovery of new and variant Potyviruses in Asparagales plants from a Dutch urban botanic garden

Although viruses play an important role in human health and plant health, most viruses are still undetected. One of the reasons is that they may evolve in distinct natural habitats that are not yet extensively sampled for virus analysis. An example of such a habitat is urban botanic gardens. We analyzed 25 Asparagales plants with a mild to severe disease phenotype from a Dutch urban botanic garden for the presence of known an unknown virus types and virus variants by smallRNA-seq and RNA-seq. We found in all samples evidence for (past) Potyviridae presence, mostly Ornithogalum virus (OV) and Ornithogalum mosaic virus (OrMV), as well as a new Iris mild mosaic virus variant (IMMV) and a yet unknown species of Potyvirus. Also, presence of a new Betaflexivirus, a new Polerovirus and a new Phenuivirus were detected. Most analyzed plants harbored multiple viruses, 18 out of 25 plants showed evidence for three to seven viruses and 12 out of 13 viruses were present in four to 11 samples. In this study, we describe the characteristics of a newly discovered Potyvirus and identify several variants of known potyviruses. We place these findings in the context of known viruses. However, we were unable to link these potyviruses to any specific disease phenotype.

genomics↗

bioRxiv2024

A new Polerovirus species in plants from the Asparagaceae family defined by its RNA-silencing repressor protein P0

To contribute to the discovery of the global virome, we explored plants from an urban botanic garden in the Netherlands for new and variant plant viruses. Analyzing RNA from 25 plants from the Asparagaceae family with both RNA-seq, as well as smallRNA-seq revealed in six plants the presence of a variant Polerovirus from the Solemoviridae family that shows an overall RNA-sequence identity of 93% to the known Ornithogalum Virus 5 (OV-5). Amino acid sequence comparison of the complex set of proteins produced by the new virus revealed that all but Protein-0, showed high similarity (> 91%) with those of the OV-5 virus. The similarity between the new P0 protein and the OV-5 P0 protein, however, was for all variants less than 83%, well below the ICTV species protein-based demarcation criterium. Hence, we named the new virus Asparagaceae Polerovirus 1 (AspPolV-1).

genomics↗

bioRxiv2024

Discovery of a new Phenuivirus species in Lachenalia plants reveals possible co-evolution between 5' and 3' RNA sequence motifs

This study reports the discovery of a new Phenuivirus species, named Lachenalia Phenuivirus-1 (LacPhV-1), from Lachenalia plants in an urban botanic garden in Amsterdam. Using a combination of smallRNA-seq, RNA-seq, and advanced bioinformatics, we identified a segmented negative-strand RNA virus in the Phenuiviridae family. Our findings show significant divergence between this new virus and known Phenuiviruses, such as Tulip Streak Virus (TuSV) and Lactuca Big Vein associated Phlebovirus (LBVaPV), supporting its classification as a distinct species. Notably, the sequence differences found in the conserved 5 and 3 ends of these segments suggest potential co-evolution. Despite the observed genomic distances, there is significant conservation in the RdRp subdomain, underscoring evolutionary relationships among LacPhV-1, TuSV, and LBVaPV. Our findings expand the known global virome and highlight the importance of exploring plant viromes in diverse ecological settings to better understand virus evolution and diversity.

genomics↗

bioRxiv2024

A new Betaflexivirus species in Ferraria crispa plants

The global virome is still largely unknown. In this study we describe the discovery of a new Betaflexivirus species in Ferraria crispa plants. The plant samples were collected in an experiment of 25 Asparagales plants, obtained from an urban botanic garden in the Netherlands, and analyzed by smallRNA-seq as well as RNA-seq. The new Betaflexivirus only occurred in four Ferraria cripsa plants and was tentatively named Ferraria Betaflexivirus 1 (FerBfV-1). This Betaflexivirus showed an RNA genome structure characteristic for the genus Capillovirus, a single-stranded (+) RNA virus. The closest known Capilloviruses in GenBank showed a protein similarity less than 49%, which is well below the proposed demarcation value of species in this genus. Further comparison analysis of the Capillovirus genus revealed the possible presence of two groups.

genomics↗

bioRxiv2024

De novo acquisition of antibiotic resistance in six species of bacteria

Bacteria can become resistant to antibiotics in two ways, by acquiring resistance genes through horizontal gene transfer and by de novo development of resistance upon exposure to non-lethal concentrations. The importance of the second process, de novo build-up, has not been investigated systematically over a range of species and may be underestimated as a result. To investigate the DNA mutation patterns accompanying the de novo antibiotic resistance acquisition process, six bacterial species encountered in the food chain were exposed to step-wise increasing sublethal concentrations of six antibiotics to develop high levels of resistance. Phenotypic and mutational landscapes were constructed based on whole genome sequencing (WGS) sequencing at two time points of the evolutionary trajectory. In this study, we found: 1) all of the six strains can develop high levels of resistance against most antibiotics. 2) increased resistance is accompanied by different mutations for each bacterium-antibiotic combination. 3) the number of mutations varies widely, with Y. enterocolitica having by far the most. 4) in the case of fluoroquinolone resistance, a mutational pattern of gyrA combined with parC is conserved in five of six species. 5) mutations in genes coding for efflux pumps are widely encountered in gram-negative species. The overall conclusion is that very similar phenotypic outcomes are instigated by very different genetic changes. IMPORTANCEThe significance of this study lies in the comparison of how six species of distinct genomic background under uniform conditions develop high levels of antibiotic resistance against six antibiotics. The mutational patterns in these six species of bacteria identify common target mutations and reveal how they acquire mutations from various pathways to survive and grow when exposed to sub-lethal levels of antibiotics. In addition to providing insights in microbial genetics, outcome of this study will assist policymakers when formulating practical strategies to prevent development of antimicrobial resistance in human and veterinary health care.

microbiology↗

bioRxiv2024

Progression of ampC amplification during de novo amoxicillin resistance development in E. coli

Beta-lactam antibiotics are the most applied antimicrobials in human and veterinarian health care. Hence, beta-lactam resistance is a major health problem. Gene amplification of AmpC beta-lactamase is a main contributor to de novo {beta}-lactam resistance in E. coli. However, the time course of amplification and the accompanying DNA mutations are unclear. Here, we study the progression of ampC amplification and ampC promoter mutations in the evolution of resistance by stepwise increasing amoxicillin concentration. AmpC promoter mutations occur by day two, while the amplification by a factor of approximately eight occurs after more than six days of amoxicillin exposure. The combination of amplification and promoter mutations increase ampC mRNA level by an average factor of 200 after 22 days. An IS1 insertion was identified in the amplification junction, suggesting the amplification is facilitated by mobile genetic elements transposition. In order to identify the essential genes for ampC amplification, the chromosomal mutations of strains with induced amoxicillin resistance were compared a similarly evolved resistant {Delta}ampC knockout. The evolved {Delta}ampC contained several resistance mutations that were absent in the WT, which accumulated more mutations in stress response genes. The amoxicillin evolved {Delta}ampC does not show amplification of the fragment around the original ampC position but exhibits a large duplication or triplication at another position, suggesting selection of genes to amplify is essential for resistance adaption. IMPORTANCEAmoxicillin is one of the most used antimicrobial against bacterial infections. DNA fragments containing ampC are amplified upon prolonged and stepwise increasing exposure to amoxicillin. These ampC amplification fragments have been identified in extended-spectrum beta-lactamases (ESBLs) plasmids, which are considered the main cause of beta- lactam resistance. Understanding the progression of ampC amplification enables amoxicillin resistance prevention. In this study, we show the time course of two important factors for ampC transcription enhancement, ampC amplification and ampC promoter mutations, during de novo amoxicillin resistance evolution. We propose that the transposon IS1 contributes to the amplification and that the sigma factor 70 regulates ampC overexpression.

microbiology↗

bioRxiv2024

Discovery of novel RNA viruses in commercially relevant seaweeds Alaria esculenta and Saccharina latissima

Seaweeds are increasingly recognized as sustainable food sources; however, their large-scale cultivation faces challenges similar to land crops, including susceptibility to pathogens. Plant viruses pose a significant threat to global food security, yet little is known about the diversity of viruses in seaweeds. This study investigates virus-associated small interfering RNA (siRNA) responses in commercially relevant seaweed species to understand RNA virus diversity, particularly in edible varieties. Through small RNA sequencing of 16 samples from Saccharina latissima and Alaria esculenta, we identified three new RNA viruses Aev-NL1, Slv-NL2 and Slv-NL3, and one new DNA virus (phaeovirus). The partial genome of the new DNA virus was discovered in the A. esculenta samples and shared 67% DNA sequence identity with the major coat protein of the large double-stranded DNA phaeovirus Feldmannia irregularis virus a. In four out of five A. esculenta samples, a new bisegmented ormycovirus-like RNA virus (Aev-NL1) was identified. A similar new virus, Slv-NL1, was found in previously published S. latissima RNA-seq data, sharing 87% sequence identity with Aev-NL1. Lastly, two novel RNA viruses, Slv-NL2 and Slv-NL3, were discovered in all eight S. latissima samples sharing limited similarity at the genome level but high sequence identity at protein level of both ORFs (>94%). Further investigation of the novel viruses presence across our limited set of samples revealed no conclusive associations with diseased seaweed phenotypes. The discovery of four new viruses in only a limited set of samples highlights the presence of previously unrecognized viral diversity in seaweed, thereby underscoring the importance of understanding viral diversity in seaweed as its virome is currently understudied.

genomics↗

bioRxiv2024

Genome sequences of three Konjac mosaic virus (KoMV) variants

This study explores the genomic diversity of three novel Konjac mosaic virus (KoMV) variants, originating from distinct Zantedeschia (calla lily) commercial cultivars. Virus-derived small RNA sequencing was performed and the complete KoMV variant genome sequences were determined by de novo assembly of short reads. All KoMV variants showed substantial nucleotide, as well as protein differences as compared to the KoMV RefSeq sequence.

genomics↗

bioRxiv2023

Reactive oxygen species accelerate de novo acquisition of antibiotic resistance in E. coli

Reactive oxygen species (ROS) produced as a secondary effect of bactericidal antibiotics are hypothesized to play a role in killing bacteria. However, the role of ROS in the development of de novo resistance as a result of sublethal levels of bactericidal antibiotics has barely been investigated. Here, we report that single-gene knockout strains with reduced ROS scavenging exhibited enhanced ROS accumulation and more rapid acquisition of resistance when exposed to sublethal levels of bactericidal antibiotics. Consistent with this observation, the ROS scavenger thiourea in the medium decelerated resistance development. Thiourea downregulated the transcriptional level of error-prone DNA polymerase and DNA glycosylase MutM, which counters the incorporation and accumulation of 8-hydroxy-2-deoxyguanosine (8-HOdG) in the genome. The level of 8-HOdG significantly increased following incubation with bactericidal antibiotics but decreased after treatment with the ROS scavenger thiourea. These observations suggest that in E. coli sublethal levels of ROS stimulate de novo development of resistance, providing a mechanistic basis for hormetic responses induced by antibiotics. ImportanceExposure to sublethal concentrations of antimicrobials is known to result in de novo resistance development against the specific compound. Particularly, the use of antibiotics as feed additives to enhance productivity may result in the development of drug resistance in environmental and veterinary microorganisms, which could subsequently transfer to human populations. Nevertheless, the mechanisms underlying de novo resistance development have not been extensively explored. In this study, we indicate the role of ROS in promoting the formation of resistance to bactericidal antibiotics and show the potential of ROS scavengers to reduce mutation rates and slow down resistance formation under long-term selection. Thus, the supplementary use of antioxidants during prolonged antibiotic administration potentially contributes to mitigating the emergence of antimicrobial resistance.

microbiology↗

bioRxiv2022

The conserved protein WhiA influences branched-chain fatty acid precursors in Bacillus subtilis

The conserved WhiA protein family is present in most Gram-positive bacteria and plays a role in cell division. WhiA contains a DNA-binding motive and has been identified as a transcription factor in actinomycetes. In Bacillus subtilis, the absence of WhiA influences cell division and chromosome segregation, however, it is still unclear how WhiA influences these processes, but the protein does not seem to function as transcription factor in this organism. To further investigate the function of WhiA in B. subtilis, we performed a yeast two-hybrid screen to find interaction partners, and a Hi-C experiment to reveal possible changes in chromosome conformation. The latter experiment indicated a reduction in short range chromosome interactions, but how this would affect either cell division or chromosome segregation is unclear. Based on adjacent genes, a role in carbon metabolism was put forward. To study this, we measured exometabolome fluxes during growth on different carbon sources. This revealed that in {Delta}whiA cells the pool of branched-chain fatty acid precursors is lower. However, the effect on the membrane fatty acid composition was minimal. Transcriptome data could not link the metabolome effects to gene regulatory differences. IMPORTANCEWhiA is a conserved DNA binding protein that influences cell division and chromosome segregation in the Gram-positive model bacterium B. subtilis. The molecular function of WhiA is still unclear, but a previous study has suggested that the protein does not function as a transcription factor. In this study, we used yeast two-hybrid screening, chromosome conformation capture analysis, metabolomics, transcriptomics and fatty acid analysis to obtain more information about the workings of this enigmatic protein.

microbiology↗

bioRxiv2022

Cellular Factors Involved in Transcriptome Dynamics in Early Zebrafish Embryogenesis

At gastrulation in the zebrafish embryogenesis, the embryonic genome is switched on to produce transcripts that are used for the maintenance and development of the embryo. In a previous study from late blastula to mid gastrula on the transcriptomes of 179 individual embryos, we capture the transcriptome dynamics via ten gene-expression types. Here we study the factors that regulate these transcriptome dynamics by in extensive silico analyses and two small-RNA sequencing experiments. We analyzed mechanisms that would make it possible for the embryo to achieve the tight regulation of gene expression that was observed, not only during development, but also when individual embryos were compared. We found that many of the gene-expression regulatory factors that are available to the embryo are operational in the different gene-expression types and act concurrently with not one mechanism prevailing in this developmental phase. We also saw that at least one of the regulatory mechanisms, the expression of members of the miRNA-430 family again is very tightly regulated, both during development as well as when miRNA expression from individual embryos is compared.

developmental biology↗

bioRxiv2021

The protein modifier SUMO is critical for Arabidopsis shoot meristem maintenance at warmer ambient temperatures

Short heat waves (>37{degrees}C) are extremely damaging to non-acclimated plants and their capacity to recover from heat stress is key for their survival. To acclimate, the HEAT SHOCK TRANSCRIPTION FACTOR A1 (HSFA1) subfamily activates a transcriptional response that resolves incurred damages. In contrast, little is known how plants acclimate to sustained non-detrimental warm periods at 27-28{degrees}C. Plants respond to this condition with a thermomorphogenesis response. In addition, HSFA1 is critical for plant survival during these warm periods. We find that SUMO, a protein modification whose conjugate levels rise sharply during acute heat stress in eukaryotes, is critical too for plant longevity during warm periods, in particular for normal shoot meristem development. The known SUMO ligases were not essential to endure these warm periods, alone or in combination. Thermo-lethality was also not seen when plants lacked certain SUMO proteases or when SUMO chain formation was blocked. The SUMO-dependent thermo-resilience was as well independent of the autoimmune phenotype of the SUMO mutants. As acquired thermotolerance was normal in the sumo1/2 knockdown mutant, our data thus reveal a role for SUMO in heat acclimation that differs from HSFA1 and SIZ1. We conclude that SUMO is critical for shoot meristem integrity during warm periods. HighlightThe protein modifier SUMO governs shoot meristem maintenance in Arabidopsis allowing sustained rosette development when plants endure a sustained warm non-detrimental period of 28 degrees Celsius.

plant biology↗

bioRxiv2019

Maternal- and Somatic-type snoRNA Expression and Processing in Zebrafish Development

Small nucleolar RNAs (snoRNAs) are non-coding RNAs that play an important role in the complex maturation process of ribosomal RNAs (rRNAs). SnoRNAs are categorized in classes, with each class member having several variants present in a genome. Similar to our finding of specific rRNA expression types in zebrafish embryogenesis, we discovered preferential maternal- and somatic-expression for snoRNAs. Most snoRNAs and their variants have higher expression levels in somatic tissues than in eggs, yet we identified three snoRNAs; U3, U8 and snoZ30 of which specific variants show maternal- or somatic-type expression. For U3 and U8 we also found small-derived snoRNAs that lack their 5 rRNA recognition part and are essentially Domain II hairpin structures (U-DII). These U-DII snoRNAs from variants showed similar preferential expression, in which maternal-type variants are prominently expressed in eggs and subsequently replaced by a somatic-type variants during embryogenesis. This differential expression is related to the organization in tandem repeats (maternal type) or solitary (somatic-type) genes of the involved U snoRNA loci. The collective data showed convincingly that the preferential expression of snoRNAs is achieved by transcription regulation, as well as through RNA processing. Finally, we observed small-RNAs derived from internal transcribed spacers (ITSs) of a U3 snoRNA loci that via complementarity binding, may be involved in the biosynthesis of U3-DII snoRNAs. Altogether, the here described maternal- and somatic-type snoRNAs are the latest addition to the developing story about the dual ribosome system in zebrafish development.

developmental biology↗