Shoot Regeneration Is Not a Single Cell Event

Shoot regeneration is a key tool of modern plant biotechnology. While many researchers use this process empirically, very little is known about the early molecular genetic factors and signaling events that lead to shoot regeneration. Using tobacco as a model system, we found that the inductive events required for shoot regeneration occur in the first 4–5 days following incubation on regeneration medium. Leaf segments placed on regeneration medium did not produce shoots if removed from the medium before four days indicating this time frame is crucial for the induction of shoot regeneration. Leaf segments placed on regeneration medium for longer than five days maintain the capacity to produce shoots when removed from the regeneration medium. Analysis of gene expression during the early days of incubation on regeneration medium revealed many changes occurring with no single expression pattern evident among major gene families previously implicated in developmental processes. For example, expression of Knotted gene family members increased during the induction period, whereas transcription factors from the Wuschel gene family were unaltered during shoot induction. Expression levels of genes involved in cell cycle regulation increased steadily on regeneration medium while expression of NAC genes varied. No obvious possible candidate genes or developmental processes could be identified as a target for the early events (first few days) in the induction of shoot regeneration. On the other hand, observations during the early stages of regeneration pointed out that regeneration does not occur from a single cell but a group of cells. We observed that while cell division starts just as leaf segments are placed on regeneration medium, only a group of cells could become shoot primordia. Still, these primordia are not identifiable during the first days.

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Gene family evolution underlies cell type diversification in the hypothalamus of teleosts

10.1101/2020.12.13.414557 ◽

2020 ◽

Author(s):

Maxwell E.R. Shafer ◽

Ahilya N. Sawh ◽

Alex F. Schier

Keyword(s):

Gene Family ◽

Single Cell ◽

Gene Families ◽

Cell Types ◽

Gene Family Evolution ◽

Specific Cell ◽

Cell Type ◽

Vertebrate Brain ◽

Hypothalamic Cells ◽

Species Specific

Hundreds of cell types form the vertebrate brain, but it is largely unknown how similar these cellular repertoires are between or within species, or how cell type diversity evolves. To examine cell type diversity across and within species, we performed single-cell RNA sequencing of ~130,000 hypothalamic cells from zebrafish (Danio rerio) and surface- and cave-morphs of Mexican tetra (Astyanax mexicanus). We found that over 75% of cell types were shared between zebrafish and Mexican tetra, which last shared a common ancestor over 150 million years ago. Orthologous cell types displayed differential paralogue expression that was generated by sub-functionalization after genome duplication. Expression of terminal effector genes, such as neuropeptides, was more conserved than the expression of their associated transcriptional regulators. Species-specific cell types were enriched for the expression of species-specific genes, and characterized by the neo-functionalization of members of recently expanded or contracted gene families. Within species comparisons revealed differences in immune repertoires and transcriptional changes in neuropeptidergic cell types associated with genomic differences between surface- and cave-morphs. The single-cell atlases presented here are a powerful resource to explore hypothalamic cell types, and reveal how gene family evolution and the neo- and sub-functionalization of paralogs contribute to cellular diversity.

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Single-Cell Transcriptomics Reveal a Correlation between Genome Architecture and Gene Family Evolution in Ciliates

mBio ◽

10.1128/mbio.02524-19 ◽

2019 ◽

Vol 10 (6) ◽

Cited By ~ 6

Author(s):

Ying Yan ◽

Xyrus X. Maurer-Alcalá ◽

Rob Knight ◽

Sergei L. Kosakovsky Pond ◽

Laura A. Katz

Keyword(s):

Molecular Evolution ◽

Gene Family ◽

Single Cell ◽

Genome Evolution ◽

Gene Families ◽

Gene Family Evolution ◽

Genome Architecture ◽

Eukaryotic Genes ◽

Ciliate Species ◽

Transcript Diversity

ABSTRACT Ciliates, a eukaryotic clade that is over 1 billion years old, are defined by division of genome function between transcriptionally inactive germline micronuclei and functional somatic macronuclei. To date, most analyses of gene family evolution have been limited to cultivable model lineages (e.g., Tetrahymena, Paramecium, Oxytricha, and Stylonychia). Here, we focus on the uncultivable Karyorelictea and its understudied sister class Heterotrichea, which represent two extremes in genome architecture. Somatic macronuclei within the Karyorelictea are described as nearly diploid, while the Heterotrichea have hyperpolyploid somatic genomes. Previous analyses indicate that genome architecture impacts ciliate gene family evolution as the most diverse and largest gene families are found in lineages with extensively processed somatic genomes (i.e., possessing thousands of gene-sized chromosomes). To further assess ciliate gene family evolution, we analyzed 43 single-cell transcriptomes from 33 ciliate species representing 10 classes. Focusing on conserved eukaryotic genes, we use estimates of transcript diversity as a proxy for the number of paralogs in gene families among four focal clades: Karyorelictea, Heterotrichea, extensive fragmenters (with gene-size somatic chromosomes), and non-extensive fragmenters (with more traditional somatic chromosomes), the latter two within the subphylum Intramacronucleata. Our results show that (i) the Karyorelictea have the lowest average transcript diversity, while Heterotrichea are highest among the four groups; (ii) proteins in Karyorelictea are under the highest functional constraints, and the patterns of selection in ciliates may reflect genome architecture; and (iii) stop codon reassignments vary among members of the Heterotrichea and Spirotrichea but are conserved in other classes. IMPORTANCE To further our understanding of genome evolution in eukaryotes, we assess the relationship between patterns of molecular evolution within gene families and variable genome structures found among ciliates. We combine single-cell transcriptomics with bioinformatic tools, focusing on understudied and uncultivable lineages selected from across the ciliate tree of life. Our analyses show that genome architecture correlates with patterns of protein evolution as lineages with more canonical somatic genomes, such as the class Karyorelictea, have more conserved patterns of molecular evolution compared to other classes. This study showcases the power of single-cell transcriptomics for investigating genome architecture and evolution in uncultivable microbial lineages and provides transcriptomic resources for further research on genome evolution.

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HLA Genotype of Patients with Severe Haemophilia A due to Intron 22 Inversion with and without Inhibitors of Factor VIII

Thrombosis and Haemostasis ◽

10.1055/s-0038-1655945 ◽

1997 ◽

Vol 77 (02) ◽

pp. 238-242 ◽

Cited By ~ 129

Author(s):

J Oldenburg ◽

J K Picard ◽

R Schwaab ◽

H H Brackmann ◽

E G D Tuddenham ◽

...

Keyword(s):

Factor Viii ◽

Major Gene ◽

Statistical Significance ◽

Strong Association ◽

Molecular Genetic ◽

Single Mutation ◽

Severe Haemophilia ◽

Extended Haplotype ◽

Intron 22 Inversion ◽

Hla Genotype

SummaryMolecular genetic studies have shown that development of antibodies to factor VIII (inhibitors) occurs most frequently in patients with severe haemophilia due to major gene lesions including inversions, stop codons and large deletions. Previous studies of HLA type were performed on inhibitor and non-inhibitor patients with diverse uncharacterised mutations which may have confounded detection of significant associations. We therefore selected a group of patients with a single mutation type, the prevalent intron 22 inversion, with or without inhibitors, to determine HLA genotype. Seventy-one such patients, 42 without and 29 with inhibitors (13 high, 9 low and 7 transient responders) were genotyped for MHC Class I HLA-A, -B, -C and Class II HLA-DQA, -DQB and -DRB loci. No strong correlation of any HLA-allele to inhibitor or non-inhibitor status was found. However, alleles of the haplotype HLA-A3, HLA-B7, HLA-C7, HLA-DQA0102, HLA-DQB0602, HLA-DR15 occurred more often in inhibitor patients. Since the alleles of this extended haplotype are common in the North European population only a very strong association would achieve statistical significance. Further studies of groups of patients similar to those studied here will be needed to confirm or exclude this association.

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Isolation and Characterization Of Rice R Genes: Evidence for Distinct Evolutionary Paths in Rice and Maize

Genetics ◽

10.1093/genetics/142.3.1021 ◽

1996 ◽

Vol 142 (3) ◽

pp. 1021-1031 ◽

Cited By ~ 3

Author(s):

Jianping Hu ◽

Beth Anderson ◽

Susan R Wessler

Keyword(s):

Gene Family ◽

Gene Families ◽

Chromosome 1 ◽

R Gene ◽

R Genes ◽

Helix Loop Helix ◽

Isolation And Characterization ◽

Undetermined Function ◽

Evolutionary Paths

Abstract R and B genes and their homologues encode basic helix-loop-helix (bHLH) transcriptional activators that regulate the anthocyanin biosynthetic pathway in flowering plants. In maize, R/B genes comprise a very small gene family whose organization reflects the unique evolutionary history and genome architecture of maize. To know whether the organization of the R gene family could provide information about the origins of the distantly related grass rice, we characterized members of the R gene family from rice Oryza sativa. Despite being a true diploid, O. sativa has at least two R genes. An active homologue (Ra) with extensive homology with other R genes is located at a position on chromosome 4 previously shown to be in synteny with regions of maize chromosomes 2 and 10 that contain the B and R loci, respectively. A second rice R gene (Rb) of undetermined function was identified on chromosome 1 and found to be present only in rice species with AA genomes. All non-AA species have but one R gene that is Ra-like. These data suggest that the common ancestor shared by maize and rice had a single R gene and that the small R gene families of grasses have arisen recently and independently.

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Expression of a gene duplication encoding conserved sperm tail proteins is translationally regulated in Drosophila melanogaster.

Molecular and Cellular Biology ◽

10.1128/mcb.13.3.1708 ◽

1993 ◽

Vol 13 (3) ◽

pp. 1708-1718 ◽

Cited By ~ 36

Author(s):

M Schäfer ◽

D Börsch ◽

A Hülster ◽

U Schäfer

Keyword(s):

Drosophila Melanogaster ◽

Gene Family ◽

Translational Control ◽

Germ Line ◽

Gene Families ◽

Homologous Gene ◽

Male Sterile ◽

Sperm Tail ◽

Repetitive Motif ◽

Carboxy Terminal

We have analyzed a locus of Drosophila melanogaster located at 98C on chromosome 3, which contains two tandemly arranged genes, named Mst98Ca and Mst98Cb. They are two additional members of the Mst(3)CGP gene family by three criteria. (i) Both genes are exclusively transcribed in the male germ line. (ii) Both transcripts encode a protein with a high proportion of the repetitive motif Cys-Gly-Pro. (iii) Their expression is translationally controlled; while transcripts can be detected in diploid stages of spermatogenesis, association with polysomes can be shown only in haploid stages of sperm development. The genes differ markedly from the other members of the gene family in structure; they do not contain introns, they are of much larger size, and they have the Cys-Gly-Pro motifs clustered at the carboxy-terminal end of the encoded proteins. An antibody generated against the Mst98Ca protein recognizes both Mst98C proteins in D. melanogaster. In a male-sterile mutation in which spermiogenesis is blocked before individualization of sperm, both of these proteins are no longer synthesized. This finding provides proof of late translation for the Mst98C proteins and thereby independent proof of translational control of expression. Northern (RNA) and Western immunoblot analyses indicate the presence of homologous gene families in many other Drosophila species. The Mst98C proteins share sequence homology with proteins of the outer dense fibers in mammalian spermatozoa and can be localized to the sperm tail by immunofluorescence with an anti-Mst98Ca antibody.

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Genome-wide search and structural and functional analyses for late embryogenesis-abundant (LEA) gene family in poplar

BMC Plant Biology ◽

10.1186/s12870-021-02872-3 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Zihan Cheng ◽

Xuemei Zhang ◽

Wenjing Yao ◽

Kai Zhao ◽

Lin Liu ◽

...

Keyword(s):

Gene Family ◽

Higher Plants ◽

Abiotic Stress Tolerance ◽

Gene Families ◽

Regulatory Elements ◽

Late Embryogenesis Abundant ◽

Genome Wide ◽

Lea Gene ◽

Late Embryogenesis ◽

Genome Wide Search

Abstract Background The Late Embryogenesis-Abundant (LEA) gene families, which play significant roles in regulation of tolerance to abiotic stresses, widely exist in higher plants. Poplar is a tree species that has important ecological and economic values. But systematic studies on the gene family have not been reported yet in poplar. Results On the basis of genome-wide search, we identified 88 LEA genes from Populus trichocarpa and renamed them as PtrLEA. The PtrLEA genes have fewer introns, and their promoters contain more cis-regulatory elements related to abiotic stress tolerance. Our results from comparative genomics indicated that the PtrLEA genes are conserved and homologous to related genes in other species, such as Eucalyptus robusta, Solanum lycopersicum and Arabidopsis. Using RNA-Seq data collected from poplar under two conditions (with and without salt treatment), we detected 24, 22 and 19 differentially expressed genes (DEGs) in roots, stems and leaves, respectively. Then we performed spatiotemporal expression analysis of the four up-regulated DEGs shared by the tissues, constructed gene co-expression-based networks, and investigated gene function annotations. Conclusion Lines of evidence indicated that the PtrLEA genes play significant roles in poplar growth and development, as well as in responses to salt stress.

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The power-law distribution of gene family size is driven by the pseudogenisation rate's heterogeneity between gene families

Gene ◽

10.1016/j.gene.2008.02.014 ◽

2008 ◽

Vol 414 (1-2) ◽

pp. 85-94 ◽

Cited By ~ 13

Author(s):

Timothy Hughes ◽

David A. Liberles

Keyword(s):

Gene Family ◽

Family Size ◽

Power Law ◽

Gene Families ◽

Power Law Distribution

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A Molecular-Genetic Study of the Arabidopsis Toc75 Gene Family

PLANT PHYSIOLOGY ◽

10.1104/pp.105.063289 ◽

2005 ◽

Vol 138 (2) ◽

pp. 715-733 ◽

Cited By ~ 77

Author(s):

Amy Baldwin ◽

Anthony Wardle ◽

Ramesh Patel ◽

Penny Dudley ◽

Soon Ki Park ◽

...

Keyword(s):

Gene Family ◽

Genetic Study ◽

Molecular Genetic ◽

Molecular Genetic Study

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Gene family innovation, conservation and loss on the animal stem lineage

eLife ◽

10.7554/elife.34226 ◽

2018 ◽

Vol 7 ◽

Cited By ~ 58

Author(s):

Daniel J Richter ◽

Parinaz Fozouni ◽

Michael B Eisen ◽

Nicole King

Keyword(s):

Gene Family ◽

Gene Families ◽

Gene Content ◽

Gene Repertoire ◽

Toll Like Receptor ◽

Stem Lineage ◽

Gains And Losses ◽

Core Features

Choanoflagellates, the closest living relatives of animals, can provide unique insights into the changes in gene content that preceded the origin of animals. However, only two choanoflagellate genomes are currently available, providing poor coverage of their diversity. We sequenced transcriptomes of 19 additional choanoflagellate species to produce a comprehensive reconstruction of the gains and losses that shaped the ancestral animal gene repertoire. We identified ~1944 gene families that originated on the animal stem lineage, of which only 39 are conserved across all animals in our study. In addition, ~372 gene families previously thought to be animal-specific, including Notch, Delta, and homologs of the animal Toll-like receptor genes, instead evolved prior to the animal-choanoflagellate divergence. Our findings contribute to an increasingly detailed portrait of the gene families that defined the biology of the Urmetazoan and that may underpin core features of extant animals.

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