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1.
Am J Community Psychol ; 73(1-2): 27-43, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37126214

RESUMO

This article explores the magnifying lenses of the COVID-19 syndemic to highlight how people racialized as migrants and refugees have been-and continue to be-disproportionally harmed. We use empirical evidence collected in our scholarly/activist work in Europe, Africa, South Asia, and the United States to examine migrant injustice as being produced by a combination of power structures and relations working to maintain colonial global orders and inequalities. This is what has been defined as "border imperialism." Our data, complemented by evidence from transnational solidarity groups, show that border imperialism has further intersected with the hygienic-sanitary logics of social control at play during the COVID-19 period. This intersection has resulted in increasingly coercive methods of restraining people on the move, as well as in increased-and new-forms of degradation of their lives, that is, an overall multiplication of border violences. At the same time, however, COVID-19 has provided a unique opportunity for grassroot solidarity initiatives and resistance led by people on the move to be amplified and extended. We conclude by emphasizing the need for community psychologists to take a more vigorous stance against oppressive border imperialist regimes and the related forms of violence they re/enact.


Assuntos
COVID-19 , Migrantes , Humanos , Sindemia , Violência , Justiça Social
2.
BMC Genomics ; 24(1): 728, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-38041052

RESUMO

BACKGROUND: Collective cell migration underlies many essential processes, including sculpting organs during embryogenesis, wound healing in the adult, and metastasis of cancer cells. At mid-oogenesis, Drosophila border cells undergo collective migration. Border cells round up into a small group at the pre-migration stage, detach from the epithelium and undergo a dynamic and highly regulated migration at the mid-migration stage, and stop at the oocyte, their final destination, at the post-migration stage. While specific genes that promote cell signaling, polarization of the cluster, formation of protrusions, and cell-cell adhesion are known to regulate border cell migration, there may be additional genes that promote these distinct active phases of border cell migration. Therefore, we sought to identify genes whose expression patterns changed during border cell migration. RESULTS: We performed RNA-sequencing on border cells isolated at pre-, mid-, and post-migration stages. We report that 1,729 transcripts, in nine co-expression gene clusters, are temporally and differentially expressed across the three migration stages. Gene ontology analyses and constructed protein-protein interaction networks identified genes expected to function in collective migration, such as regulators of the cytoskeleton, adhesion, and tissue morphogenesis, but also uncovered a notable enrichment of genes involved in immune signaling, ribosome biogenesis, and stress responses. Finally, we validated the in vivo expression and function of a subset of identified genes in border cells. CONCLUSIONS: Overall, our results identified differentially and temporally expressed genetic networks that may facilitate the efficient development and migration of border cells. The genes identified here represent a wealth of new candidates to investigate the molecular nature of dynamic collective cell migrations in developing tissues.


Assuntos
Proteínas de Drosophila , Drosophila , Animais , Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Redes Reguladoras de Genes , Oogênese/genética , Movimento Celular/genética , Perfilação da Expressão Gênica , Drosophila melanogaster/genética
3.
Subst Use Misuse ; 58(1): 119-128, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36474456

RESUMO

Background: The aim of this research was to examine the psychometrics of a short form version of the multidimensional Involvement in Alcoholics Anonymous scale (IAA-SF) by assessing the factor structure, internal consistency, and predictive validity. While there are several existing measures of involvement in Alcoholics Anonymous, many are either unidimensional or are limited in their ability to gather variation in the level of involvement in the different dimensions of 12-step programs. Objective: To achieve our aim, we used exploratory and principal axis factor analysis, correlation, and logistic regression with two unique and diverse samples. Longitudinal data were collected from a northern Illinois sample of 110 post-treatment adults, and cross-sectional data were from a random sample of 296 recovery home residents in the United States. Results: Results from the first sample suggested three exploratory factors (Principles Involvement, Social Involvement, and Spiritual Involvement) that were concordant with the proposed conceptualization and were then confirmed in the second sample. A 2nd order factor of global involvement was also found. All subscales demonstrated good to excellent internal consistency and were moderately associated with AA affiliation. Global and social involvement predicted greater odds of abstinence 2 years later, but principles and spiritual involvement did not. Conclusion: Overall results suggest the IAA- SF is a valid and reliable 12-item instrument for assessing involvement in the AA program, and the differential prediction suggests potential utility for a multidimensional approach to 12-step involvement.


Assuntos
Alcoólicos Anônimos , Alcoolismo , Adulto , Humanos , Estados Unidos , Alcoolismo/diagnóstico , Estudos Transversais , Psicometria , Reprodutibilidade dos Testes
4.
Am J Community Psychol ; 68(3-4): 269-291, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-33960422

RESUMO

In 2018, in response to increasingly oppressive and widespread federal immigration enforcement actions in the United States (U.S.) and around the globe - including family separation, immigration raids, detention, deportation of people who have lived in the country for much of their lives - the Society for Community Research & Action produced a statement on the effects of deportation and forced separation on immigrants, their families, and communities (SCRA, 2018). The statement focused exclusively on the impacts of deportation and forced family separation, documenting the damage done by oppressive U.S. policies and practices. We felt it was imperative to document this harm, and yet were uncomfortable producing a narrow paper that focused solely on harm. There are multiple ways immigrants and their allies resist deportation and other forms of oppression. This resistance is done individually, collectively, and in settings that vary in size and scope, including community-based, faith-based, direct care, and educational settings, as well as entire municipalities and transnational organizing settings. Settings facilitate resistance in many ways, focusing on those who are oppressed, their oppressors, and systems of oppression. In this statement, we describe the unique and overlapping ways in which settings facilitate resistance. We situate this review of the scientific and practice literature in the frameworks of change through social settings, empowering settings, healing justice, and decolonization. We also document recommendations for continued resistance.


Assuntos
Emigrantes e Imigrantes , Transtornos Mentais , Emigração e Imigração , Humanos , Políticas , Sociedades Científicas , Estados Unidos
5.
Proc Natl Acad Sci U S A ; 114(31): E6361-E6370, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28716924

RESUMO

Porphyra umbilicalis (laver) belongs to an ancient group of red algae (Bangiophyceae), is harvested for human food, and thrives in the harsh conditions of the upper intertidal zone. Here we present the 87.7-Mbp haploid Porphyra genome (65.8% G + C content, 13,125 gene loci) and elucidate traits that inform our understanding of the biology of red algae as one of the few multicellular eukaryotic lineages. Novel features of the Porphyra genome shared by other red algae relate to the cytoskeleton, calcium signaling, the cell cycle, and stress-tolerance mechanisms including photoprotection. Cytoskeletal motor proteins in Porphyra are restricted to a small set of kinesins that appear to be the only universal cytoskeletal motors within the red algae. Dynein motors are absent, and most red algae, including Porphyra, lack myosin. This surprisingly minimal cytoskeleton offers a potential explanation for why red algal cells and multicellular structures are more limited in size than in most multicellular lineages. Additional discoveries further relating to the stress tolerance of bangiophytes include ancestral enzymes for sulfation of the hydrophilic galactan-rich cell wall, evidence for mannan synthesis that originated before the divergence of green and red algae, and a high capacity for nutrient uptake. Our analyses provide a comprehensive understanding of the red algae, which are both commercially important and have played a major role in the evolution of other algal groups through secondary endosymbioses.


Assuntos
Citoesqueleto/genética , Evolução Molecular , Genoma de Planta/genética , Porphyra/citologia , Porphyra/genética , Actinas/genética , Sinalização do Cálcio/genética , Ciclo Celular/genética , Parede Celular/genética , Parede Celular/metabolismo , Cromatina/genética , Cinesinas/genética , Filogenia
6.
Mol Biol Evol ; 35(4): 855-870, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29294063

RESUMO

Multicellularity is the premier example of a major evolutionary transition in individuality and was a foundational event in the evolution of macroscopic biodiversity. The volvocine chlorophyte lineage is well suited for studying this process. Extant members span unicellular, simple colonial, and obligate multicellular taxa with germ-soma differentiation. Here, we report the nuclear genome sequence of one of the most morphologically simple organisms in this lineage-the 4-celled colonial Tetrabaena socialis and compare this to the three other complete volvocine nuclear genomes. Using conservative estimates of gene family expansions a minimal set of expanded gene families was identified that associate with the origin of multicellularity. These families are rich in genes related to developmental processes. A subset of these families is lineage specific, which suggests that at a genomic level the evolution of multicellularity also includes lineage-specific molecular developments. Multiple points of evidence associate modifications to the ubiquitin proteasomal pathway (UPP) with the beginning of coloniality. Genes undergoing positive or accelerating selection in the multicellular volvocines were found to be enriched in components of the UPP and gene families gained at the origin of multicellularity include components of the UPP. A defining feature of colonial/multicellular life cycles is the genetic control of cell number. The genomic data presented here, which includes diversification of cell cycle genes and modifications to the UPP, align the genetic components with the evolution of this trait.


Assuntos
Evolução Biológica , Clorófitas/genética , Genes cdc , Componentes Genômicos , Ciclinas/genética , Genes do Retinoblastoma , Família Multigênica , Complexo de Endopeptidases do Proteassoma/genética , Seleção Genética , Transcriptoma , Ubiquitina/genética
7.
New Phytol ; 217(3): 1346-1356, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29023752

RESUMO

Losses of floral pigmentation represent one of the most common evolutionary transitions in flower color, yet the genetic basis for these changes has been elucidated in only a handful of cases. Here we used crossing studies, bulk-segregant RNA sequencing, phylogenetic analyses and functional tests to identify the gene(s) responsible for the transition to white flowers in Iochroma loxense. Crosses between I. loxense and its blue-flowered sister species, I. cyaneum, suggested that a single locus controls the flower color difference and that the white allele causes a nearly complete loss of pigmentation. Examining sequence variation across phenotypic pools from the crosses, we found that alleles at a novel R3 MYB transcription factor were tightly associated with flower color variation. This gene, which we term MYBL1, falls into a class of MYB transcriptional repressors and, accordingly, higher expression of this gene is associated with downregulation of multiple anthocyanin pigment pathway genes. We confirmed the repressive function of MYBL1 through stable transformation of Nicotiana. The mechanism underlying the evolution of white flowers in I. loxense differs from that uncovered in previous studies, pointing to multiple mechanisms for achieving fixed transitions in flower color intensity.


Assuntos
Flores/fisiologia , Pigmentação , Proteínas de Plantas/metabolismo , Proteínas Repressoras/metabolismo , Solanaceae/fisiologia , Sequência de Aminoácidos , Antocianinas/metabolismo , Teorema de Bayes , Segregação de Cromossomos/genética , Cruzamentos Genéticos , Flores/genética , Regulação da Expressão Gênica de Plantas , Loci Gênicos , Modelos Biológicos , Fenótipo , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas Repressoras/química , Proteínas Repressoras/genética , Solanaceae/genética , Nicotiana/metabolismo
8.
Proc Natl Acad Sci U S A ; 112(10): E1152-61, 2015 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-25713358

RESUMO

Millions of people are infected each year by arboviruses (arthropod-borne viruses) such as chikungunya, dengue, and West Nile viruses, yet for reasons that are largely unknown, only a relatively small number of mosquito species are able to transmit arboviruses. Understanding the complex factors that determine vector competence could facilitate strategies for controlling arbovirus infections. Apoptosis is a potential antiviral defense response that has been shown to be important in other virus-host systems. However, apoptosis is rarely seen in arbovirus-infected mosquito cells, raising questions about its importance as an antiviral defense in mosquitoes. We tested the effect of stimulating apoptosis during arbovirus infection by infecting Aedes aegypti mosquitoes with a Sindbis virus (SINV) clone called MRE/Rpr, in which the MRE-16 strain of SINV was engineered to express the proapoptotic gene reaper from Drosophila. MRE/Rpr exhibited an impaired infection phenotype that included delayed midgut infection, delayed virus replication, and reduced virus accumulation in saliva. Nucleotide sequencing of the reaper insert in virus populations isolated from individual mosquitoes revealed evidence of rapid and strong selection against maintenance of Reaper expression in MRE/Rpr-infected mosquitoes. The impaired phenotype of MRE/Rpr, coupled with the observed negative selection against Reaper expression, indicates that apoptosis is a powerful defense against arbovirus infection in mosquitoes and suggests that arboviruses have evolved mechanisms to avoid stimulating apoptosis in mosquitoes that serve as vectors.


Assuntos
Aedes/virologia , Apoptose/fisiologia , Insetos Vetores/virologia , Seleção Genética , Sindbis virus/fisiologia , Aedes/genética , Animais , Insetos Vetores/genética , Saliva/virologia , Replicação Viral
9.
J Mol Evol ; 83(1-2): 26-37, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27364496

RESUMO

MYB transcription factors play an important role in regulating key plant developmental processes involving defense, cell shape, pigmentation, and root formation. Within this gene family, sequences containing an R2R3 MYB domain are the most abundant type and exhibit a wide diversity of functions. In this study, we identify 559 R2R3 MYB genes using whole genome data from four species of Solanaceae and reconstruct their evolutionary relationships. We compare the Solanaceae R2R3 MYBs to the well-characterized Arabidopsis thaliana sequences to estimate functional diversity and to identify gains and losses of MYB clades in the Solanaceae. We identify numerous R2R3 MYBs that do not appear closely related to Arabidopsis MYBs, and thus may represent clades of genes that have been lost along the Arabidopsis lineage or gained after the divergence of Rosid and Asterid lineages. Despite differences in the distribution of R2R3 MYBs across functional subgroups and species, the overall size of the R2R3 subfamily has changed relatively little over the roughly 50 million-year history of Solanaceae. We added our information regarding R2R3 MYBs in Solanaceae to other data and performed a meta-analysis to trace the evolution of subfamily size across land plants. The results reveal many shifts in the number of R2R3 genes, including a 54 % increase along the angiosperm stem lineage. The variation in R2R3 subfamily size across land plants is weakly positively correlated with genome size and strongly positively correlated with total number of genes. The retention of such a large number of R2R3 copies over long evolutionary time periods suggests that they have acquired new functions and been maintained by selection. Discovering the nature of this functional diversity will require integrating forward and reverse genetic approaches on an -omics scale.


Assuntos
Solanum lycopersicum/genética , Fatores de Transcrição/genética , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Sequência Conservada , Evolução Molecular , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Família Multigênica , Filogenia , Proteínas de Plantas/genética , Fatores de Transcrição/metabolismo
10.
PLoS Genet ; 9(8): e1003724, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24009520

RESUMO

Heteromorphic sex-determining regions or mating-type loci can contain large regions of non-recombining sequence where selection operates under different constraints than in freely recombining autosomal regions. Detailed studies of these non-recombining regions can provide insights into how genes are gained and lost, and how genetic isolation is maintained between mating haplotypes or sex chromosomes. The Chlamydomonas reinhardtii mating-type locus (MT) is a complex polygenic region characterized by sequence rearrangements and suppressed recombination between its two haplotypes, MT+ and MT-. We used new sequence information to redefine the genetic contents of MT and found repeated translocations from autosomes as well as sexually controlled expression patterns for several newly identified genes. We examined sequence diversity of MT genes from wild isolates of C. reinhardtii to investigate the impacts of recombination suppression. Our population data revealed two previously unreported types of genetic exchange in Chlamydomonas MT--gene conversion in the rearranged domains, and crossover exchanges in flanking domains--both of which contribute to maintenance of genetic homogeneity between haplotypes. To investigate the cause of blocked recombination in MT we assessed recombination rates in crosses where the parents were homozygous at MT. While normal recombination was restored in MT+ ×MT+ crosses, it was still suppressed in MT- ×MT- crosses. These data revealed an underlying asymmetry in the two MT haplotypes and suggest that sequence rearrangements are insufficient to fully account for recombination suppression. Together our findings reveal new evolutionary dynamics for mating loci and have implications for the evolution of heteromorphic sex chromosomes and other non-recombining genomic regions.


Assuntos
Chlamydomonas reinhardtii/genética , Loci Gênicos/genética , Recombinação Genética , Reprodução/genética , Cromossomos Sexuais/genética , Translocação Genética/genética , Evolução Biológica , Chlamydomonas reinhardtii/crescimento & desenvolvimento , Conversão Gênica , Haplótipos
11.
Eukaryot Cell ; 13(5): 648-56, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24632243

RESUMO

Male and female, generally defined based on differences in gamete size and motility, likely have multiple independent origins, appearing to have evolved from isogamous organisms in various eukaryotic lineages. Recent studies of the gamete fusogen GCS1/HAP2 indicate that this protein is deeply conserved across eukaryotes, and its exclusive and/or functional expression generally resides in males or in male homologues. However, little is known regarding the conserved or primitive molecular traits of males and females within eukaryotes. Here, using morphologically indistinguishable isogametes of the colonial volvocine Gonium pectorale, we demonstrated that GCS1 is differently regulated between the sexes. G. pectorale GCS1 molecules in one sex (homologous to male) are transported from the gamete cytoplasm to the protruded fusion site, whereas those of the other sex (females) are quickly degraded within the cytoplasm upon gamete activation. This molecular trait difference might be conserved across various eukaryotic lineages and may represent male and female prototypes originating from a common eukaryotic ancestor.


Assuntos
Clorófitas/genética , Regulação da Expressão Gênica , Fusão Gênica , Células Germinativas Vegetais/metabolismo , Processamento de Proteína Pós-Traducional , Proteínas/genética , Sequência de Aminoácidos , Clorófitas/citologia , Clorófitas/metabolismo , Eucariotos/química , Eucariotos/classificação , Eucariotos/genética , Evolução Molecular , Dados de Sequência Molecular , Filogenia , Proteínas/metabolismo , Alinhamento de Sequência , Especificidade da Espécie
12.
J Drug Issues ; 45(1): 53-68, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25641984

RESUMO

This study examined the role played by aftercare following (mainly) inpatient community-based treatment in the outcomes of criminal ex-offenders with substance use disorders. Two hundred and seventy individuals who had been released from the criminal justice system were randomly assigned to either a Therapeutic Community (TC), recovery homes called Oxford Houses (OHs), or usual care settings (UA). The OHs and TCs are residential settings that emphasized socialization and abstinence from drugs and alcohol, but OHs do not include the formal therapeutic change interventions common to TCs, nor did they include any on-site access to drug abuse or health care professionals. UA involved what occurred naturally after completing treatment, which included staying with friends or family members, their own house or apartment, homeless shelters, or other settings. Longer lengths of stay in either the TCs or OHs were associated with increased employment, and reduced alcohol and drug use. Those assigned to the OH condition received more money from employment, worked more days, achieved higher continuous alcohol sobriety rates, and had more favorable cost-benefit ratios.

13.
J Offender Rehabil ; 54(3): 161-174, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25960625

RESUMO

The relationships between motivation, treatment readiness, and abstinence self-efficacy were examined among a sample of ex-offenders exiting inpatient treatment for substance use disorders. Hierarchical linear regression was conducted to examine changes in participants' motivation levels in relation to abstinence self-efficacy beyond what would be expected from treatment readiness and substance use. Abstinence self-efficacy predicted significant decreases in motivation whereas treatment readiness and substance use predicted significant increases. However, there was not a significant relationship between abstinence self-efficacy and treatment readiness. Findings suggest that motivation for change among persons with substance use disorders is related to their self-efficacy for ongoing abstinence.

14.
J Offender Rehabil ; 54(5): 338-349, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26279611

RESUMO

Research has shown employment to be a central mediator to sustained recovery and community reentry for substance abusers; however, heroin users have lower employment rates and report lower mean incomes than other drug users. The authors of the present study assessed income generating behaviors of substance users recruited from substance abuse treatment facilities (N=247). Heroin users had higher mean incomes from illegal sources. Further, logistic regression analysis found heroin use to increase the likelihood of engagement in illegal income generating behaviors. As these results increase the likelihood of involvement in the criminal justice system, the implications for heroin specific treatment and rehabilitation are discussed.

15.
Mol Biol Evol ; 30(4): 793-7, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23300255

RESUMO

It has been argued that for certain lineages, noncoding DNA expansion is a consequence of the increased random genetic drift associated with long-term escalations in organism size. But a lack of data has prevented the investigation of this hypothesis in most plastid-bearing protists. Here, using newly sequenced mitochondrial and plastid genomes, we explore the relationship between organelle DNA noncoding content and organism size within volvocine green algae. By looking at unicellular, colonial, and differentiated multicellular algae, we show that organelle DNA complexity scales positively with species size and cell number across the volvocine lineage. Moreover, silent-site genetic diversity data suggest that the volvocine species with the largest cell numbers and most bloated organelle genomes have the smallest effective population sizes. Together, these findings support the view that nonadaptive processes, like random genetic drift, promote the expansion of noncoding regions in organelle genomes.


Assuntos
Chlamydomonas reinhardtii/genética , Genoma Mitocondrial , Genomas de Plastídeos , Mitocôndrias/genética , Plastídeos/genética , Chlamydomonas reinhardtii/citologia , Evolução Molecular , Deriva Genética , Variação Genética , Genoma de Planta , Modelos Genéticos , Volvocida/citologia , Volvocida/genética
16.
BMC Plant Biol ; 14: 244, 2014 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-25252698

RESUMO

BACKGROUND: Cell walls are essential for most bacteria, archaea, fungi, algae and land plants to provide shape, structural integrity and protection from numerous biotic and abiotic environmental factors. In the case of eukaryotic algae, relatively little is known of the composition, structure or mechanisms of assembly of cell walls in individual species or between species and how these differences enable algae to inhabit a great diversity of environments. In this paper we describe the use of camelid antibody fragments (VHHs) and a streamlined ELISA assay as powerful new tools for obtaining mono-specific reagents for detecting individual algal cell wall components and for isolating algae that share a particular cell surface component. RESULTS: To develop new microalgal bioprospecting tools to aid in the search of environmental samples for algae that share similar cell wall and cell surface components, we have produced single-chain camelid antibodies raised against cell surface components of the single-cell alga, Chlamydomonas reinhardtii. We have cloned the variable-region domains (VHHs) from the camelid heavy-chain-only antibodies and overproduced tagged versions of these monoclonal-like antibodies in E. coli. Using these VHHs, we have developed an accurate, facile, low cost ELISA that uses live cells as a source of antigens in their native conformation and that requires less than 90 minutes to perform. This ELISA technique was demonstrated to be as accurate as standard ELISAs that employ proteins from cell lysates and that generally require >24 hours to complete. Among the cloned VHHs, VHH B11, exhibited the highest affinity (EC50 < 1 nM) for the C. reinhardtii cell surface. The live-cell ELISA procedure was employed to detect algae sharing cell surface components with C. reinhardtii in water samples from natural environments. In addition, mCherry-tagged VHH B11 was used along with fluorescence activated cell sorting (FACS) to select individual axenic isolates of presumed wild relatives of C. reinhardtii and other Chlorphyceae from the same environmental samples. CONCLUSIONS: Camelid antibody VHH domains provide a highly specific tool for detection of individual cell wall components of algae and for allowing the selection of algae that share a particular cell surface molecule from diverse ecosystems.


Assuntos
Antígenos de Plantas/imunologia , Chlamydomonas reinhardtii/imunologia , Microalgas/isolamento & purificação , Animais , Especificidade de Anticorpos , Antígenos de Superfície/imunologia , Bioprospecção , Camelídeos Americanos , Parede Celular/imunologia , Chlamydomonas reinhardtii/genética , Meio Ambiente , Ensaio de Imunoadsorção Enzimática , Escherichia coli/genética , Escherichia coli/metabolismo , Citometria de Fluxo , Genes Reporter , Microalgas/classificação , Filogenia , Proteínas Recombinantes de Fusão , Anticorpos de Domínio Único/imunologia
17.
Plant Cell ; 22(10): 3331-47, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20978220

RESUMO

We examined the cell cycle dynamics of the retinoblastoma (RB) protein complex in the unicellular alga Chlamydomonas reinhardtii that has single homologs for each subunit-RB, E2F, and DP. We found that Chlamydomonas RB (encoded by MAT3) is a cell cycle-regulated phosphoprotein, that E2F1-DP1 can bind to a consensus E2F site, and that all three proteins interact in vivo to form a complex that can be quantitatively immunopurified. Yeast two-hybrid assays revealed the formation of a ternary complex between MAT3, DP1, and E2F1 that requires a C-terminal motif in E2F1 analogous to the RB binding domain of plant and animal E2Fs. We examined the abundance of MAT3/RB and E2F1-DP1 in highly synchronous cultures and found that they are synthesized and remain stably associated throughout the cell cycle with no detectable fraction of free E2F1-DP1. Consistent with their stable association, MAT3/RB and DP1 are constitutively nuclear, and MAT3/RB does not require DP1-E2F1 for nuclear localization. In the nucleus, MAT3/RB remains bound to chromatin throughout the cell cycle, and its chromatin binding is mediated through E2F1-DP1. Together, our data show that E2F-DP complexes can regulate the cell cycle without dissociation of their RB-related subunit and that other changes may be sufficient to convert RB-E2F-DP from a cell cycle repressor to an activator.


Assuntos
Ciclo Celular , Chlamydomonas/citologia , Cromatina/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Protozoários/metabolismo , Proteína do Retinoblastoma/metabolismo , Chlamydomonas/genética , Chlamydomonas/metabolismo , Fatores de Transcrição E2F/genética , Fatores de Transcrição E2F/metabolismo , Regulação da Expressão Gênica de Plantas , Dados de Sequência Molecular , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Fosforilação , Proteínas de Protozoários/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteína do Retinoblastoma/genética , Fator de Transcrição DP1/genética , Fator de Transcrição DP1/metabolismo , Técnicas do Sistema de Duplo-Híbrido
19.
Curr Biol ; 33(23): R1231-R1234, 2023 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-38052172

RESUMO

A new study uses Chlamydomonas reinhardtii to understand how cell size homeostasis emerges from stochastic individual cell behaviors within a population. The authors find that a simple power law model was a poor predictor of cell size regulation; rather, it is better explained by a modified threshold model.


Assuntos
Chlamydomonas reinhardtii , Chlamydomonas reinhardtii/fisiologia , Tamanho Celular , Homeostase
20.
Sci Rep ; 13(1): 5268, 2023 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-37002250

RESUMO

Multicellular evolution is a major transition associated with momentous diversification of multiple lineages and increased developmental complexity. The volvocine algae comprise a valuable system for the study of this transition, as they span from unicellular to undifferentiated and differentiated multicellular morphologies despite their genomes being similar, suggesting multicellular evolution requires few genetic changes to undergo dramatic shifts in developmental complexity. Here, the evolutionary dynamics of six volvocine genomes were examined, where a gradual loss of genes was observed in parallel to the co-option of a few key genes. Protein complexes in the six species exhibited novel interactions, suggesting that gene loss could play a role in evolutionary novelty. This finding was supported by gene network modeling, where gene loss outpaces gene gain in generating novel stable network states. These results suggest gene loss, in addition to gene gain and co-option, may be important for the evolution developmental complexity.


Assuntos
Evolução Biológica , Filogenia
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