Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Diversification”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed2007

Diversity and diversification of light chains in myeloma: the specter of amyloidogenesis by proxy.

BACKGROUND/AIMS: Primary amyloidosis and the cancer, multiple myeloma, are characterized by the overproduction of free antibody light chains. Approximately 10% of myeloma patients develop amyloidosis; primary amyloidosis may be thought of as the pathological analog of monoclonal gammopathy of undetermined significance. The kidney is a common site of accumulation of amyloid fibrils and is also the target of other light chain pathologies. Understanding the structural origin of these pathologies is complicated by the extreme primary structure heterogeneity of light chains. METHODS: Patterns of light chain germline gene usage in myeloma patients were compared to those found in other immune system disorders: lymphoma, leukemia, systemic lupus erythematosus and rheumatoid arthritis. RESULTS: Significant differences in apparent gene usage are found in the various diseases; several germline gene products have not been documented in myeloma patients to date. CONCLUSION: The plasma cell dyscrasias including myeloma, lymphoma, leukemia, and monoclonal gammopathy of undetermined significance are usually monoclonal diseases; however, the light chains produced are not homogeneous. Thus, the pathological risk for the patient may change during the course of the illness. Mutation rates in light chains observed during clonal diversification parallel mutations occurring in all genes in the malignant cells and could be a clinically useful biomarker.

Amino Acid Sequence↗
PubMed2004

Conservation, diversification and expansion of C2H2 zinc finger proteins in the Arabidopsis thaliana genome.

BACKGROUND: The classical C2H2 zinc finger domain is involved in a wide range of functions and can bind to DNA, RNA and proteins. The comparison of zinc finger proteins in several eukaryotes has shown that there is a lot of lineage specific diversification and expansion. Although the number of characterized plant proteins that carry the classical C2H2 zinc finger motifs is growing, a systematic classification and analysis of a plant genome zinc finger gene set is lacking. RESULTS: We found through in silico analysis 176 zinc finger proteins in Arabidopsis thaliana that hence constitute the most abundant family of putative transcriptional regulators in this plant. Only a minority of 33 A. thaliana zinc finger proteins are conserved in other eukaryotes. In contrast, the majority of these proteins (81%) are plant specific. They are derived from extensive duplication events and form expanded families. We assigned the proteins to different subgroups and families and focused specifically on the two largest and evolutionarily youngest families (A1 and C1) that are suggested to be primarily involved in transcriptional regulation. The newly defined family A1 (24 members) comprises proteins with tandemly arranged zinc finger domains. Family C1 (64 members), earlier described as the EPF-family in Petunia, comprises proteins with one isolated or two to five dispersed fingers and a mostly invariant QALGGH motif in the zinc finger helices. Based on the amino acid pattern in these helices we could describe five different signature sequences prevalent in C1 zinc finger domains. We also found a number of non-finger domains that are conserved in these families. CONCLUSIONS: Our analysis of the few evolutionarily conserved zinc finger proteins of A. thaliana suggests that most of them could be involved in ancient biological processes like RNA metabolism and chromatin-remodeling. In contrast, the majority of the unique A. thaliana zinc finger proteins are known or suggested to be involved in transcriptional regulation. They exhibit remarkable differences in the features of their zinc finger sequences and zinc finger arrangements compared to animal zinc finger proteins. The different zinc finger helix signatures we found in family C1 may have important implications for the sequence specific DNA recognition and allow inferences about the evolution of the members in this family.

Amino Acid Motifs↗
PubMed2006

Phylogenetic diversification of glycogen synthase kinase 3/SHAGGY-like kinase genes in plants.

BACKGROUND: The glycogen synthase kinase 3 (GSK3)/SHAGGY-like kinases (GSKs) are non-receptor serine/threonine protein kinases that are involved in a variety of biological processes. In contrast to the two members of the GSK3 family in mammals, plants appear to have a much larger set of divergent GSK genes. Plant GSKs are encoded by a multigene family; analysis of the Arabidopsis genome revealed the existence of 10 GSK genes that fall into four major groups. Here we characterized the structure of Arabidopsis and rice GSK genes and conducted the first broad phylogenetic analysis of the plant GSK gene family, covering a taxonomically diverse array of algal and land plant sequences. RESULTS: We found that the structure of GSK genes is generally conserved in Arabidopsis and rice, although we documented examples of exon expansion and intron loss. Our phylogenetic analyses of 139 sequences revealed four major clades of GSK genes that correspond to the four subgroups initially recognized in Arabidopsis. ESTs from basal angiosperms were represented in all four major clades; GSK homologs from the basal angiosperm Persea americana (avocado) appeared in all four clades. Gymnosperm sequences occurred in clades I, III, and IV, and a sequence of the red alga Porphyra was sister to all green plant sequences. CONCLUSION: Our results indicate that (1) the plant-specific GSK gene lineage was established early in the history of green plants, (2) plant GSKs began to diversify prior to the origin of extant seed plants, (3) three of the four major clades of GSKs present in Arabidopsis and rice were established early in the evolutionary history of extant seed plants, and (4) diversification into four major clades (as initially reported in Arabidopsis) occurred either just prior to the origin of the angiosperms or very early in angiosperm history.

Amino Acid Substitution↗
PubMed2003

Diversification of U.S. medical schools via affirmative action implementation.

BACKGROUND: The diversification of medical school student and faculty bodies via race-conscious affirmative action policy is a societal and legal option for the U.S. Supreme Court has recently ruled its use constitutional. This paper investigates the implications of affirmative action, particularly race-conscious compared to race-blind admissions policy; explains how alternative programs are generally impractical; and provides a brief review of the history and legality of affirmative action in the United States. DISCUSSION: Selection based solely on academic qualifications such as GPA and MCAT scores does not achieve racial and ethnic diversity in medical school, nor does it adequately predict success as practicing physicians. However, race-conscious preference yields greater practice in underserved and often minority populations, furthers our biomedical research progression, augments health care for minority patients, and fosters an exceptional medical school environment where students are better able to serve an increasingly multicultural society. SUMMARY: The implementation of race-conscious affirmative action results in diversity in medicine. Such diversity has shown increased medical practice in underserved areas, thereby providing better health care for the American people.

Biomedical Research↗
PubMed2026

Conserved protein folds underpin the diversification of secreted proteins in a fungal pathogen.

BACKGROUND: During host colonization, fungal plant pathogens secrete effector-like proteins that alter host cell physiology and target plant-associated microbes. However, rapid evolution and low sequence conservation hinder the study and characterization of these proteins. The fungus Zymoseptoria passerinii infects Hordeum spp. and includes lineages adapted to wild and domesticated barley. To date, the evolution of effector-like proteins in this species has not been addressed. RESULTS: We combined multiple structure-based and network analyses to unravel the secretome of Z. passerinii. We first compared AlphaFold2 and ESMFold predictions to establish the baseline for structural analyses. We identified 72 structural clusters in the secretome, revealing fold-level relationships across divergent sequences. We showed that effector-like proteins with predicted host immune-interfering functions evolved from a limited group of protein folds, whereas proteins with predicted antimicrobial properties were distributed across fold groups. Physicochemical comparisons indicate that putative antimicrobial effectors predominantly emerged through amino acid replacements on common effector-enriched scaffolds in Z. passerinii, reconfiguring surface charge and electrostatics. We analyzed intra- and interspecific variation in selected effector-enriched families by comparing Z. passerinii proteins and homologs across the genus Zymoseptoria. We describe constrained core folds, with local variation in loop and surface-exposed regions, consistent with fold stability while still enabling protein diversification. We further report that putative antimicrobial effector homologs are broadly distributed across the genus despite sequence divergence. CONCLUSIONS: The secretome of Z. passerinii is organized around common structural folds that support diverse biological roles, including host manipulation and host-associated microbial interactions. Conserved scaffolds combined with surface and physicochemical variation likely contribute to rapid adaptive evolution of effector-like proteins in Z. passerinii.

Fungal Proteins↗
PubMed2004

Evolutionary diversification of specification mechanisms within the O/P equivalence group of the leech genus Helobdella.

Developmental fates and cell lineage patterns are highly conserved in the teloblast lineages that give rise to the segmental ectoderm of clitellate annelids. But previous studies have shown that the pathways involved in specification of the ventrolateral O lineage and the dorsolateral P lineage differ to some degree in distantly related clitellate species such as the leeches Helobdella and Theromyzon, and the sludgeworm Tubifex. To examine this developmental variation at a lower taxonomic level, we have explored the specification pathways of the O and P lineages in the leech genus Helobdella. In leech, the O and P lineages arise from a developmental equivalence group of O/P teloblasts. In this study, we demonstrate that the cell-cell interactions involved in cell fate specification of the O/P equivalence group differ among three laboratory colonies of closely related species. In two populations, the Q lineage is necessary to specify the P fate in the dorsalmost O/P lineage, but in the third population the P fate can be specified by a redundant pathway involving the M lineage. We also observe interspecific variation in the role played by cell interactions within the O/P equivalence group, and in the apparent significance of extrinsic signals from the micromere cell lineages. Our data suggest that cell fate specification in the O/P equivalence group is a complex process that involves multiple cell-cell interactions, and that the developmental architecture of the O/P equivalence group has undergone evolutionary diversification in closely related species, despite maintaining a conserved morphology.

Animals↗
PubMed1994

Muscle pattern diversification in Drosophila is determined by the autonomous function of homeotic genes in the embryonic mesoderm.

Muscle diversification in the Drosophila embryo is manifest in a stereotyped array of myofibers that exhibit distinct segment-specific patterns. Here it is shown that the homeotic genes of the Bithorax complex control the identities of abdominal somatic muscles and their precursors by functioning directly in cells of the mesoderm. Whereas Ultrabithorax (Ubx) and abdominal-A (abd-A) have equivalent functions in promoting the formation of particular muscle precursors in the anterior abdominal segments, Abdominal-B (Abd-B) suppresses the development of these same myogenic cells in the posterior region of the abdomen. When expressed in the same mesodermal cells, however, either UBX or ABD-A can override the inhibitory influence of ABD-B, suggesting that these factors may compete in the regulation of common downstream genes. Furthermore, targeted ectopic expression of Ubx or abd-A indicates that these homeotic genes influence muscle cell fates by autonomous action in mesodermal cells. Muscle identity also appears to be sensitive to the level of UBX in myogenic precursors. Finally, these experiments reveal that homeotic cues specific to both the mesoderm and the ectoderm cooperate to specify the pattern of muscle attachment sites.

Animals↗
PubMed1995

Target-independent diversification and target-specific projection of chemically defined retinal ganglion cell subsets.

In diverse vertebrate species, defined subsets of retinal ganglion cells (RGCs, the neurons that project from retina to brain) are distinguishable on the basis of their dendritic morphology, physiological properties, neurotransmitter content and synaptic targets. Little is known about when this diversity arises, whether diversification requires target-derived signals, and how subtype-specific projection patterns are established. Here, we have used markers for two chemically defined RGC subsets in chick retina to address these issues. Antibodies to substance P (SP) and the nicotine acetylcholine receptor (AChR) beta 2 subunit label two small ( < 10%), mutually exclusive groups of RGCs in mature retina. SP and AChRs accumulate in distinct RGCs before retinotectal synapses have formed. Moreover, both populations of RGCs form in retinae that develop following tectal ablation or transplantation to the coelomic cavity. Thus, RGC subsets acquire distinct neurotransmitter phenotypes in the absence of extraretinal cues. In the mature optic tectum, SP- and AChR-positive RGC axonal arbors are confined to distinct retinorecipient (synaptic) laminae. In the developing tectum, SP- and AChR-positive axons are initially intermingled in a superficial fiber layer, but then enter and arborize in appropriate laminae soon after those laminae form. Importantly, SP-positive axons, which synapse in a superficial lamina, never extend into the deeper, AChR-positive lamina. Tectal interneurons rich in SP receptors are concentrated in the lamina to which SP-positive RGC axons project, and a set of cholinergic (choline acetyltransferase-positive) tectal projection neurons elaborate dendrites in the lamina to which AChR-positive RGC axons project. These populations of tectal neurons, which are likely targets of the RGC subsets, form in tecta that develop following enucleation. Thus, RGCs and their targets can diversify in each others absence. Accordingly, we propose that the lamina-selective connectivity we observe reflects the presence of complementary cues on RGC subsets and their laminar targets.

Animals↗
PubMed1997

ladybird, a new component of the cardiogenic pathway in Drosophila required for diversification of heart precursors.

The embryonic heart precursors of Drosophila are arranged in a repeated pattern of segmental units. There is growing evidence that the development of individual elements of this pattern depends on both mesoderm intrinsic patterning information and inductive signals from the ectoderm. In this study, we demonstrate that two homeobox genes, ladybird early and ladybird late, are involved in the cardiogenic pathway in Drosophila. Their expression is specific to a subset of cardioblast and pericardial cell precursors and is critically dependent on mesodermal tinman function, epidermal Wingless signaling and the coordinate action of neurogenic genes. Negative regulation by hedgehog is required to restrict ladybird expression to two out of six cardioblasts in each hemisegment. Overexpression of ladybird causes a hyperplasia of heart precursors and alters the identity of even-skipped-positive pericardial cells. Loss of ladybird function leads to the opposite transformation, suggesting that ladybird participates in the determination of heart lineages and is required to specify the identities of subpopulations of heart cells. We find that both early Wingless signaling and ladybird-dependent late Wingless signaling are required for proper heart formation. Thus, we propose that ladybird plays a dual role in cardiogenesis: (i) during the early phase, it is involved in specification of a segmental subset of heart precursors as a component of the cardiogenic tinman-cascade and (ii) during the late phase, it is needed for maintaining wingless activity and thereby sustaining the heart pattern process. These events result in a diversification of heart cell identities within each segment.

Animals↗
PubMed1998

Signalling by the Drosophila epidermal growth factor receptor is required for the specification and diversification of embryonic muscle progenitors.

Muscle development initiates in the Drosophila embryo with the segregation of single progenitor cells, from which a complete set of myofibres arises. Each progenitor is assigned a unique fate, characterized by the expression of particular identity genes. We now demonstrate that the Drosophila epidermal growth factor receptor provides an inductive signal for the specification of a large subset of muscle progenitors. In the absence of the receptor or its ligand, SPITZ, specific progenitors fail to segregate. The resulting unspecified mesodermal cells undergo programmed cell death. In contrast, receptor hyperactivation generates supernumerary progenitors, as well as the duplication of at least one SPITZ-dependent myofibre. The development of individual muscles is differentially sensitive to variations in the level of signalling by the epidermal growth factor receptor. Such graded myogenic effects can be influenced by alterations in the functions of Star and rhomboid. In addition, muscle patterning is dependent on the generation of a spatially restricted, activating SPITZ signal, a process that may rely on the localized mesodermal expression of RHOMBOID. Thus, the epidermal growth factor receptor contributes both to muscle progenitor specification and to the diversification of muscle identities.

Animals↗
PubMed1998

ladybird determines cell fate decisions during diversification of Drosophila somatic muscles.

In the mesoderm of Drosophila embryos, a defined number of cells segregate as progenitors of individual body wall muscles. Progenitors and their progeny founder cells display lineage-specific expression of transcription factors but the mechanisms that regulate their unique identities are poorly understood. Here we show that the homeobox genes ladybird early and ladybird late are expressed in only one muscle progenitor and its progeny: the segmental border muscle founder cell and two precursors of adult muscles. The segregation of the ladybird-positive progenitor requires coordinate action of neurogenic genes and an interplay of inductive Hedgehog and Wingless signals from the overlying ectoderm. Unlike so far described progenitors but similar to the neuroblasts, the ladybird-positive progenitor undergoes morphologically asymmetric division. We demonstrate that the ectopic ladybird expression is sufficient to change the identity of a subset of progenitor/founder cells and to generate an altered pattern of muscle precursors. When ectopically expressed, ladybird transforms the identity of neighbouring, Krüppel-positive progenitors leading to the formation of giant segmental border muscles and supernumerary precursors of lateral adult muscles. In embryos lacking ladybird gene function, specification of two ladybird-expressing myoblast lineages is affected. The segmental border muscles do not form or have abnormal shapes and insertion sites while the number of lateral precursors of adult muscles is dramatically reduced. Altogether our results provide new insights into the genetic control of diversification of muscle precursors and indicate a further similarity between the myogenic and neurogenic pathways.

Animals↗
PubMed2000

Overlapping roles of two Hox genes and the exd ortholog ceh-20 in diversification of the C. elegans postembryonic mesoderm.

Members of the Hox family of homeoproteins and their cofactors play a central role in pattern formation of all germ layers. During postembryonic development of C. elegans, non-gonadal mesoderm arises from a single mesoblast cell M. Starting in the first larval stage, M divides to produce 14 striated muscles, 16 non-striated muscles, and two non-muscle cells (coelomocytes). We investigated the role of the C. elegans Hox cluster and of the exd ortholog ceh-20 in patterning of the postembryonic mesoderm. By examining the M lineage and its differentiation products in different Hox mutant combinations, we found an essential but overlapping role for two of the Hox cluster genes, lin-39 and mab-5, in diversification of the postembryonic mesoderm. This role of the two Hox gene products required the CEH-20 cofactor. One target of these two Hox genes is the C. elegans twist ortholog hlh-8. Using both in vitro and in vivo assays, we demonstrated that twist is a direct target of Hox activation. We present evidence from mutant phenotypes that twist is not the only target for Hox genes in the M lineage: in particular we show that lin-39 mab-5 double mutants exhibit a more severe M lineage defect than the hlh-8 null mutant.

Animals↗
PubMed2006

Diversification of gut morphology in caterpillars is associated with defensive behavior.

The relationship between insect gut structure and foraging strategy has been studied for several hundred years; however, we know little about how, or even if, other common insect behaviors are linked to gut morphology. For example, many insects defend themselves by regurgitation, a behavior which is expected to be closely connected to gut structure. Caterpillars belong to an insect taxon, the Lepidoptera, with a particularly well-studied digestive tract and a known predilection for defensive regurgitation. I have explored whether defensive regurgitation is associated with specific gut structure by examining the relationship between defensive behavior and gut morphology in the larvae of 36 butterfly and moth species. My analysis shows that predilection to defensively regurgitate is closely associated with fore- and midgut morphology. Species that primarily regurgitate in defense have enlarged foreguts and shortened midguts, whereas the opposite relationship is seen among those that do not readily regurgitate. These results reveal that: (i) defensive regurgitation is not the primary defense of all caterpillars, and (ii) gut morphology can be associated with other factors than the chemical and mechanical properties of ingested foods. These findings challenge long held beliefs concerning the ubiquity of defensive regurgitation in caterpillars and the causes of diversification of gut morphology, and further reinforce the gut's standing as a complex and sophisticated organ.

Animals↗
PubMed2002

A U.S. perspective on AHSCs: a future of increased diversification.

Academic Health Sciences Centres (AHSCs) have long been viewed much as the historic battleship - possessing great force, power and bulk, but increasingly vulnerable to forays of lighter and more agile competitors. This commentary reviews the efforts of leaders of AHSCs in the United States to reposition their institutions at the centre of integrated delivery systems, partly as a result of greatly increased reliance on clinical revenue to support the historic teaching mission. While Lozon and Fox point to increased involvement of AHSCs in broad regional systems of care financed through a coordinated strategy, integrated systems in the United States may be fragmenting as marketplace-driven financial schemes actually discourage integrated care. From the perspective of organizational theory, the future seems to imply a diversification of organizational forms for the AHSCs in the United States, with a corresponding strategy of lessening reliance on clinical revenues through enhancement of research funding.

Academic Medical Centers↗
PubMed2004

Genetic and functional diversification of small RNA pathways in plants.

Multicellular eukaryotes produce small RNA molecules (approximately 21-24 nucleotides) of two general types, microRNA (miRNA) and short interfering RNA (siRNA). They collectively function as sequence-specific guides to silence or regulate genes, transposons, and viruses and to modify chromatin and genome structure. Formation or activity of small RNAs requires factors belonging to gene families that encode DICER (or DICER-LIKE [DCL]) and ARGONAUTE proteins and, in the case of some siRNAs, RNA-dependent RNA polymerase (RDR) proteins. Unlike many animals, plants encode multiple DCL and RDR proteins. Using a series of insertion mutants of Arabidopsis thaliana, unique functions for three DCL proteins in miRNA (DCL1), endogenous siRNA (DCL3), and viral siRNA (DCL2) biogenesis were identified. One RDR protein (RDR2) was required for all endogenous siRNAs analyzed. The loss of endogenous siRNA in dcl3 and rdr2 mutants was associated with loss of heterochromatic marks and increased transcript accumulation at some loci. Defects in siRNA-generation activity in response to turnip crinkle virus in dcl2 mutant plants correlated with increased virus susceptibility. We conclude that proliferation and diversification of DCL and RDR genes during evolution of plants contributed to specialization of small RNA-directed pathways for development, chromatin structure, and defense.

Arabidopsis↗
PubMed2006

The leukocyte receptor complex in chicken is characterized by massive expansion and diversification of immunoglobulin-like Loci.

The innate and adaptive immune systems of vertebrates possess complementary, but intertwined functions within immune responses. Receptors of the mammalian innate immune system play an essential role in the detection of infected or transformed cells and are vital for the initiation and regulation of a full adaptive immune response. The genes for several of these receptors are clustered within the leukocyte receptor complex (LRC). The purpose of this study was to carry out a detailed analysis of the chicken (Gallus gallus domesticus) LRC. Bacterial artificial chromosomes containing genes related to mammalian leukocyte immunoglobulin-like receptors were identified in a chicken genomic library and shown to map to a single microchromosome. Sequencing revealed 103 chicken immunoglobulin-like receptor (CHIR) loci (22 inhibitory, 25 activating, 15 bifunctional, and 41 pseudogenes). A very complex splicing pattern was found using transcript analyses and seven hypervariable regions were detected in the external CHIR domains. Phylogenetic and genomic analysis showed that CHIR genes evolved mainly by block duplications from an ancestral inhibitory receptor locus, with transformation into activating receptors occurring more than once. Evolutionary selection pressure has led not only to an exceptional expansion of the CHIR cluster but also to a dramatic diversification of CHIR loci and haplotypes. This indicates that CHIRs have the potential to complement the adaptive immune system in fighting pathogens.

Alternative Splicing↗
PubMed2006

Type III effector diversification via both pathoadaptation and horizontal transfer in response to a coevolutionary arms race.

The concept of the coevolutionary arms race holds a central position in our understanding of pathogen-host interactions. Here we identify the molecular mechanisms and follow the stepwise progression of an arms race in a natural system. We show how the evolution and function of the HopZ family of type III secreted effector proteins carried by the plant pathogen Pseudomonas syringae are influenced by a coevolutionary arms race between pathogen and host. We surveyed 96 isolates of P. syringae and identified three homologs (HopZ1, HopZ2, and HopZ3) distributed among approximately 45% of the strains. All alleles were sequenced and their expression was confirmed. Evolutionary analyses determined that the diverse HopZ1 homologs are ancestral to P. syringae, and have diverged via pathoadaptive mutational changes into three functional and two degenerate forms, while HopZ2 and HopZ3 have been brought into P. syringae via horizontal transfer from other ecologically similar bacteria. A PAML selection analysis revealed that the C terminus of HopZ1 is under strong positive selection. Despite the extensive genetic variation observed in this family, all three homologs have cysteine-protease activity, although their substrate specificity may vary. The introduction of the ancestral hopZ1 allele into strains harboring alternate alleles results in a resistance protein-mediated defense response in their respective hosts, which is not observed with the endogenous allele. These data indicate that the P. syringae HopZ family has undergone allelic diversification via both pathoadaptive mutational changes and horizontal transfer in response to selection imposed by the host defense system. This genetic diversity permits the pathogen to avoid host defenses while still maintaining a virulence-associated protease, thereby allowing it to thrive on its current host, while simultaneously impacting its host range.

Adaptation, Biological↗
PubMed2005

Natural variation in Vif: differential impact on APOBEC3G/3F and a potential role in HIV-1 diversification.

The HIV-1 Vif protein counteracts the antiviral activity exhibited by the host cytidine deaminases APOBEC3G and APOBEC3F. Here, we show that defective vif alleles can readily be found in HIV-1 isolates and infected patients. Single residue changes in the Vif protein sequence are sufficient to cause the loss of Vif-induced APOBEC3 neutralization. Interestingly, not all the detected defects lead to a complete inactivation of Vif function since some mutants retained selective neutralizing activity against APOBEC3F but not APOBEC3G or vice versa. Concordantly, independently hypermutated proviruses with distinguishable patterns of G-to-A substitution attributable to cytidine deamination induced by APOBEC3G, APOBEC3F, or both enzymes were present in individuals carrying proviruses with completely or partly defective Vif variants. Natural variation in Vif function may result in selective and partial neutralization of cytidine deaminases and thereby promote viral sequence diversification within HIV-1 infected individuals.

Journal Article↗