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1.
Sci Rep ; 13(1): 13437, 2023 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-37596310

RESUMO

Feline chronic gingivostomatitis (FCGS) is a relatively common and debilitating disease characterized by bilateral inflammation and ulceration of the caudal oral mucosa, alveolar and buccal mucosa, and varying degrees of periodontal disease. The etiopathogenesis of FCGS remains unresolved. In this study, we performed bulk RNA-seq molecular profiling of affected tissues derived from a cohort of client-owned cats with FCGS compared to tissues from unaffected animals, to identify candidate genes and pathways that can help guide future exploration of novel clinical solutions. We complemented transcriptomic findings with immunohistochemistry and in situ hybridization assays to better understand the biological significance of the results and performed RNA-seq validation of biologically relevant differentially expressed genes using qPCR assays to demonstrate technical reproducibility. Transcriptomic profiles of oral mucosal tissues in cats with FCGS are enriched with immune- and inflammation-related genes and pathways that appear to be largely influenced by IL6, and include NFKB, JAK/STAT, IL-17 and IFN type I and II signaling, offering new opportunities to develop novel clinical applications based on a more rational understanding of the disease.


Assuntos
Interferon Tipo I , Estomatite , Gatos , Animais , Transcriptoma , Interleucina-6 , Reprodutibilidade dos Testes , Perfilação da Expressão Gênica , Estomatite/genética , Estomatite/veterinária , Inflamação/genética
2.
Am J Ophthalmol Case Rep ; 26: 101417, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35243157

RESUMO

PURPOSE: Iris cysts may arise secondary to surgical or nonsurgical trauma, potentially leading to corneal decompensation via mechanical injury to the adjacent endothelium. However, no well-established protocol exists for the treatment for corneal edema arising therefrom. OBSERVATIONS: A 58-year-old white male presented with an iris mass of his left eye; it occupied 1/3rd the anterior chamber volume and directly contacted the corneal endothelium. The cornea was diffusely edematous, and best corrected visual acuity (BCVA) measured 20/70 (0.3). Corneal endothelial decompensation secondary to iris cyst was diagnosed. Treatment consisted of endophotocoagulation and vitrectomy probe removal of the cyst wall, with Descemet membrane endothelial keratoplasty (DMEK) also performed as a single, combined procedure. The patient subsequently experienced a resolution of his corneal edema and disappearance of his iris cyst, without recurrence of either condition. BCVA improved to 20/25 (0.8). CONCLUSIONS AND IMPORTANCE: Iris cyst may be a rare cause of corneal decompensation. Viable treatment may entail a single-stage procedure involving endophotocoagulation and vitrectomy probe application to the cyst wall combined with DMEK.

3.
J Cataract Refract Surg ; 47(11): e37-e39, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34675164

RESUMO

Corneal allogenic intrastromal ring segments (CAIRS) are semicircular pieces of donor corneal stroma, which may be surgically implanted to flatten keratoconic corneas. These segments can be trimmed to different thicknesses; whereas thicker segments confer greater flattening, their bulk renders them more technically challenging to insert. Consequently, thinner segments are often preferred, especially for starting surgeons. Here, we describe a technique for transiently thinning CAIRS to facilitate easy insertion, thereby permitting the use of thicker segments to achieve the maximal flattening effect.


Assuntos
Desidratação , Ceratocone , Substância Própria/cirurgia , Topografia da Córnea , Humanos , Ceratocone/cirurgia , Próteses e Implantes , Implantação de Prótese
4.
J Cataract Refract Surg ; 47(11): e31-e33, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33577275

RESUMO

Corneal allogenic ring segments are semicircular pieces of donor corneal stroma that may be surgically implanted to flatten keratoconic corneas. Conventionally, these donor segments are inserted into channels created using femtosecond laser dissection. However, access to femtosecond technology is not universal. In this study, an alternate, manual technique for channel creation, which is femtosecond laser independent, is described.


Assuntos
Ceratocone , Terapia a Laser , Substância Própria/cirurgia , Topografia da Córnea , Humanos , Ceratocone/cirurgia , Próteses e Implantes , Implantação de Prótese , Acuidade Visual
6.
Cornea ; 39(10): 1303-1306, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32371843

RESUMO

PURPOSE: To describe the clinical outcome of a first patient undergoing Bowman layer (BL) transplantation with an onlay graft to reduce fluctuation in visual acuity and refractive error after previous radial keratotomy (RK) surgery. METHODS: In 2018, a 66-year-old woman presented with complaints of long-standing diurnal fluctuation in best-spectacle corrected visual acuity (BSCVA) after RK in 1983. After the removal of host epithelium, a BL graft was positioned onto the host cornea. BSCVA, Scheimpflug-based corneal tomography, and anterior segment optical coherence tomography were evaluated up to 12 months postoperatively. RESULTS: The surgery and postoperative course were uneventful. After surgery, the subjective complaints of visual fluctuation were reduced from 10 to 3 on a scale from 1 to 10. BSCVA (20/40; 0.5) did not change from preoperative to postoperative. Corneal tomography showed an overall central corneal steepening of 5.9 diopters. Biomicroscopy, Scheimpflug imaging, and anterior segment optical coherence tomography showed a completely epithelialized and well-integrated graft, with some minor epithelial remnants located in the preexisting keratotomy incisions. CONCLUSIONS: BL onlay grafting may have the potential to manage patients with subjective complaints of diurnal fluctuation in visual acuity after previous RK.


Assuntos
Lâmina Limitante Anterior/cirurgia , Ceratotomia Radial/efeitos adversos , Transtornos da Visão/cirurgia , Acuidade Visual/fisiologia , Idoso , Lâmina Limitante Anterior/diagnóstico por imagem , Topografia da Córnea , Feminino , Humanos , Transplante de Órgãos , Erros de Refração/etiologia , Erros de Refração/fisiopatologia , Doadores de Tecidos , Tomografia de Coerência Óptica , Transplante Homólogo , Transtornos da Visão/etiologia , Transtornos da Visão/fisiopatologia
7.
Curr Eye Res ; 45(9): 1031-1035, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32064948

RESUMO

PURPOSE/AIMS OF THE STUDY: To evaluate the clinical outcomes of Descemet membrane endothelial keratoplasty (DMEK) performed in the "oldest old" patients, i.e. ≥ 90 years. MATERIALS AND METHODS: Between the years of 2009 and 2019, 20 consecutive eyes of 17 patients aged ≥ 90 underwent DMEK for endothelial dysfunction. Best corrected visual acuity (BCVA), central corneal thickness (CCT), endothelial cell density (ECD), graft survival, and intra- and postoperative complications were assessed. RESULTS: Except in one case in which the DMEK surgery could not be completed, all operated eyes experienced an improvement in BCVA, although only 50% achieved ≥ 20/40 (0.5) by 1 year postoperatively. One year after surgery, median CCT had declined from 641(±161) µm to 480 (±34) µm, and median endothelial cell density was reduced by 53%, from 2574 (±286) to 1226 (±404) cells/mm2. Six of 19 eyes receiving DMEK grafts (32%) developed partial graft detachments requiring re-bubbling. One eye experienced a secondary graft failure at 6 months and underwent repeat endothelial keratoplasty. CONCLUSION: DMEK is technically feasible in the oldest old patients and may yield significant visual improvements, although an elevated risk of some postoperative complications including graft detachment with corresponding need for re-bubbling may be anticipated.


Assuntos
Doenças da Córnea/cirurgia , Ceratoplastia Endotelial com Remoção da Lâmina Limitante Posterior , Idoso de 80 Anos ou mais , Contagem de Células , Lâmina Limitante Posterior/cirurgia , Endotélio Corneano/patologia , Endotélio Corneano/cirurgia , Feminino , Seguimentos , Avaliação Geriátrica , Sobrevivência de Enxerto/fisiologia , Humanos , Masculino , Cuidados Pós-Operatórios , Complicações Pós-Operatórias , Resultado do Tratamento , Acuidade Visual/fisiologia
9.
Viruses ; 11(6)2019 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-31216693

RESUMO

Following reovirus infection, cells activate stress responses that repress canonical translation as a mechanism to limit progeny virion production. Work by others suggests that these stress responses, which are part of the integrated stress response (ISR), may benefit rather than repress reovirus replication. Here, we report that compared to untreated cells, treating cells with sodium arsenite (SA) to activate the ISR prior to infection enhanced viral protein expression, percent infectivity, and viral titer. SA-mediated enhancement was not strain-specific, but was cell-type specific. While SA pre-treatment of cells offered the greatest enhancement, treatment within the first 4 h of infection increased the percent of cells infected. SA activates the heme-regulated eIF2α (HRI) kinase, which phosphorylates eukaryotic translation initiation factor 2 alpha (eIF2α) to induce stress granule (SG) formation. Heat shock (HS), another activator of HRI, also induced eIF2α phosphorylation and SGs in cells. However, HS had no effect on percent infectivity or viral yield but did enhance viral protein expression. These data suggest that SA pre-treatment perturbs the cell in a way that is beneficial for reovirus and that this enhancement is independent of SG induction. Understanding how to manipulate the cellular stress responses during infection to enhance replication could help to maximize the oncolytic potential of reovirus.


Assuntos
Arsenitos/toxicidade , Inibidores Enzimáticos/toxicidade , Orthoreovirus de Mamíferos/crescimento & desenvolvimento , Compostos de Sódio/toxicidade , Estresse Fisiológico/efeitos dos fármacos , Replicação Viral , Linhagem Celular , Humanos , Carga Viral
10.
Am J Ophthalmol Case Rep ; 14: 26-27, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30815619

RESUMO

PURPOSE: To describe a case of corneal ulceration associated with Nivolumab use. OBSERVATIONS: An 80-year-old woman treated with Nivolumab for metastatic melanoma developed an intractable corneal ulcer in her left eye, refractory to all therapies - including surgery to cover the ulcer with a conjunctival flap - until topical prednisolone acetate was tried, which was curative. CONCLUSIONS AND IMPORTANCE: Nivolumab use may be associated with a form of steroid-responsive corneal ulceration.

11.
Cell Host Microbe ; 24(5): 618-619, 2018 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-30439337

RESUMO

In this issue of Cell Host & Microbe, Bouziat et al. (2018) and Van Winkle et al. (2018) find that the capsid gene of murine norovirus (MNV) functions as a trigger of host inflammation. These studies specifically describe how MNV-induced inflammation promotes loss of oral tolerance and persistent viral infection, respectively.


Assuntos
Norovirus , Animais , Capsídeo , Proteínas do Capsídeo , Macrófagos , Camundongos , Células Mieloides
12.
Genes (Basel) ; 9(10)2018 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-30262745

RESUMO

Supernumerary chromosomal segments (SCSs) represent additional chromosomal material that, unlike B chromosomes, is attached to the standard chromosome complement. The Prospero autumnale complex (Hyacinthaceae) is polymorphic for euchromatic large terminal SCSs located on the short arm of chromosome 1 in diploid cytotypes AA and B7B7, and tetraploid AAB7B7 and B6B6B7B7, in addition to on the short arm of chromosome 4 in polyploid B7B7B7B7 and B7B7B7B7B7B7 cytotypes. The genomic composition and evolutionary relationships among these SCSs have been assessed using fluorescence in situ hybridisation (FISH) with 5S and 35S ribosomal DNAs (rDNAs), satellite DNA PaB6, and a vertebrate-type telomeric repeat TTAGGG. Neither of the rDNA repeats were detected in SCSs, but most contained PaB6 and telomeric repeats, although these never spanned whole SCSs. Genomic in situ hybridisation (GISH) using A, B6, and B7 diploid genomic parental DNAs as probes revealed the consistently higher genomic affinity of SCSs in diploid hybrid B6B7 and allopolyploids AAB7B7 and B6B6B7B7 to genomic DNA of the B7 diploid cytotype. GISH results suggest a possible early origin of SCSs, especially that on chromosome 1, as by-products of the extensive genome restructuring within a putative ancestral P. autumnale B7 genome, predating the complex diversification at the diploid level and perhaps linked to B-chromosome evolution.

13.
Front Plant Sci ; 9: 433, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29755483

RESUMO

Polyploidy is a major driving force in angiosperm evolution, but our understanding of establishment and early diversification processes following allo- vs. auto-polyploidy is limited. An excellent system to address such questions is the monocot plant Prospero autumnale, as it comprises several genomically and chromosomally distinct diploid cytotypes and their auto- and allotetraploid derivatives. To infer origins and evolutionary trajectories of the tetraploids, we use genome size data, in situ hybridization with parental genomic DNAs and specific probes (satDNA, rDNAs), as well as molecular-phylogenetic analyses. Thus, we demonstrate that an astounding range of allotetraploid lineages has been formed recurrently by chromosomal re-patterning, interactions of chromosomally variable parental genomes and nested cycles of extensive hybridization, whereas autotetraploids have originated at least twice and are cytologically stable. During the recurrent formation and establishment across wide geographic areas hybridization in some populations could have inhibited lineage diversification and nascent speciation of such a hybrid swarm. However, cytotypes that became fixed in populations enhanced the potential for species diversification, possibly exploiting the extended allelic base, and fixed heterozygosity that polyploidy confers. The time required for polyploid cytotype fixation may in part reflect the lag phase reported for polyploids between their formation and species diversification.

15.
PLoS One ; 11(11): e0167177, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27870903

RESUMO

Glechoma L. (Lamiaceae) is distributed in eastern Asia and Europe. Understanding chromosome evolution in Glechoma has been strongly hampered by its small chromosomes, constant karyotype and polyploidy. Here phylogenetic patterns and chromosomal variation in Glechoma species are considered, using genome sizes, chromosome mapping of 5S and 35S rDNAs by fluorescence in situ hybridisation (FISH), and phylogenetic analyses of internal transcribed spacers (nrITS) of 35S rDNA and 5S rDNA NTS sequences. Species and populations of Glechoma are tetraploid (2n = 36) with base chromosome number of x = 9. Four chromosomes carry pericentric 5S rDNA sites in their short arms in all the species. Two to four of these chromosomes also carry 35S rDNA in subterminal regions of the same arms. Two to four other chromosomes have 35S rDNA sites, all located subterminally within short arms; one individual possessed additional weak pericentric 35S rDNA signals on three other chromosomes. Five types of rDNA locus distribution have been defined on the basis of 35S rDNA variation, but none is species-specific, and most species have more than one type. Glechoma hederacea has four types. Genome size in Glechoma ranges from 0.80 to 0.94 pg (1C), with low levels of intrapopulational variation in all species. Phylogenetic analyses of ITS and NTS sequences distinguish three main clades coinciding with geographical distribution: European (G. hederacea-G. hirsuta), Chinese and Korean (G. longituba), and Japanese (G. grandis). The paper presents the first comparative cytogenetic analyses of Glechoma species including karyotype structure, rDNA location and number, and genome size interpreted in a phylogenetic context. The observed variation suggests that the genus is still in genomic flux. Genome size, but not rDNA loci number and distribution, provides a character for species delimitation which allows better inferences of interspecific relationships to be made, in the absence of well-defined morphological differentiation.


Assuntos
DNA de Plantas/genética , DNA Ribossômico/genética , Evolução Molecular , Loci Gênicos , Lamiaceae/genética , Poliploidia
16.
New Phytol ; 210(2): 669-79, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26643365

RESUMO

Supernumerary B chromosomes (Bs) are genomic parasitic components, originating from the A complement via chromosomal rearrangements, which follow their own evolutionary trajectories. They often contain repetitive DNAs, some shared with regular chromosomes and some newly evolved. Genomic composition, origin and evolution of Bs have been analysed in the chromosomally variable Prospero autumnale complex. Two rDNAs and a satellite DNA (PaB6) from regular chromosomes were mapped to Bs of 26 plants from three diploid cytotypes, their hybrids and polyploid derivatives. In homoploid diploid hybrids, genomic in situ hybridization (GISH) allowed B painting with the parental DNAs. Bs were structurally variable and highly enriched in 5S rDNA and satDNA PaB6, and rarely in 35S rDNA. Eleven combinations of rDNA and PaB6 localization were observed. The quantities of PaB6 in Bs and regular chromosomes were not correlated, suggesting amplification mechanisms other than recombination. PaB6 and 5S rDNA amounts increased with increasing ploidy level. GISH revealed two independent origins of Bs. The structural variation, repeat content, repeat-type fluctuations and differing genomic affinities of Bs in different cytotypes suggest that they represent young proto-B chromosomes. Bs in P. autumnale probably form recurrently as by-products of the extensive genome restructuring within this chromosomally variable species complex.


Assuntos
Asparagaceae/genética , Evolução Biológica , Cromossomos de Plantas/genética , Genoma de Planta , Polimorfismo Genético , DNA Ribossômico/genética , DNA Satélite/genética , Diploide , Hibridização in Situ Fluorescente , Meiose/genética , Poliploidia , Sequências de Repetição em Tandem/genética
17.
J Virol ; 85(4): 1507-16, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21106751

RESUMO

The reovirus outer capsid protein µ1 is responsible for cell membrane penetration during virus entry and contains determinants necessary for virus-induced apoptosis. Residues 582 to 611 of µ1 are necessary and sufficient for reovirus-induced apoptosis, and residues 594 and 595 independently regulate the efficiency of viral entry and reovirus-induced cell apoptosis, respectively. Two of three α-helices within this region, helix 1 (residues 582 to 611) and helix 3 (residues 644 to 675), play a role in reovirus-induced apoptosis. Here, we chemically synthesized peptides representing helix 1 (H1), H1:K594D, H1:I595K, and helix 3 (H3) and examined their biological properties. We found that H1, but not H3, was able to cause concentration- and size-dependent leakage of molecules from small unilamellar liposomes. We further found that direct application of H1, but not H1:K594D, H1:I595K, or H3, to cells resulted in cytotoxicity. Application of the H1 peptide to L929 cells caused rapid elevations in intracellular calcium concentration that were independent of phospholipase C activation. Cytotoxicity of H1 was not restricted to eukaryotic cells, as the H1 peptide also had bactericidal activity. Based on these findings, we propose that the proapoptotic function of the H1 region of µ1 is dependent on its capacity to destabilize cellular membranes and cause release of molecules from intracellular organelles that ultimately induces cell necrosis or apoptosis, depending on the dose.


Assuntos
Apoptose/efeitos dos fármacos , Proteínas do Capsídeo/química , Membrana Celular/efeitos dos fármacos , Orthoreovirus de Mamíferos/patogenicidade , Peptídeos/química , Sequência de Aminoácidos , Animais , Células CHO , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/metabolismo , Membrana Celular/virologia , Permeabilidade da Membrana Celular , Dicroísmo Circular , Cricetinae , Cricetulus , Eritrócitos/fisiologia , Hemólise , Células L , Lipossomos/metabolismo , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , Orthoreovirus de Mamíferos/genética , Orthoreovirus de Mamíferos/fisiologia , Peptídeos/síntese química , Peptídeos/genética , Peptídeos/farmacologia
18.
Mol Vis ; 15: 250-8, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19190733

RESUMO

PURPOSE: Inflammation plays an important role in dry eye syndrome. In this study, inflammatory cytokine expression on the ocular surface in the Botulium toxin B (BTX-B) induced mouse dry eye model was investigated. METHODS: CBA/J mice received an injection of saline or 20 milliunits (mU) of BTX-B into the lacrimal gland. Tear production and corneal fluorescein staining were evaluated in all groups before injection and at 3 time points after. The pro-inflammatory cytokines macrophage inhibitory factor (MIF), interleukin-1beta (IL-1 beta), tumor necrosis factor-alpha (TNF- alpha) and interleukin-6 (IL-6) in conjunctival and corneal epithelium were evaluated by real time quantitative PCR and immunohistochemistry. RESULTS: BTX-B injected mice showed significantly decreased aqueous tear production and increased corneal fluorescein staining at the 1 week and 2 week time points compared with normal control and saline-injected mice. The BTX-B injected mice mRNA expression levels of TNF-alpha and IL-1beta from conjunctival and corneal epithelial cells increased significantly at two early time points comparing with that of normal and saline injected mice, but IL-1beta returned to normal levels at the 4 week time point. Saline injected mice showed no difference in mRNA expression of TNF-alpha, IL-1beta, MIF, and IL-6 on the ocular surface tissue at all time points. Immunohistochemistry confirmed these findings. CONCLUSIONS: BTX-B induced mouse model showed decreased aqueous tear production, increased corneal fluorescein staining, and TNF-alpha and IL-1beta increased expression on the ocular surface within one month. The patterns seen appeared to mimic those in humans with non-Sjögren's syndrome keratoconjunctivitis sicca (NS-KCS).


Assuntos
Córnea/metabolismo , Citocinas/metabolismo , Síndromes do Olho Seco/metabolismo , Animais , Toxinas Botulínicas , Túnica Conjuntiva/efeitos dos fármacos , Túnica Conjuntiva/metabolismo , Túnica Conjuntiva/patologia , Córnea/efeitos dos fármacos , Córnea/patologia , Citocinas/genética , Modelos Animais de Doenças , Síndromes do Olho Seco/induzido quimicamente , Feminino , Fluoresceína/metabolismo , Imunofluorescência , Expressão Gênica/efeitos dos fármacos , Aparelho Lacrimal/metabolismo , Camundongos , Camundongos Endogâmicos CBA , Lágrimas/efeitos dos fármacos , Lágrimas/metabolismo
19.
J Virol Methods ; 157(1): 105-10, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19103225

RESUMO

Mucosal epithelial cells are the primary targets for many common viral pathogens of cats. Viral infection of epithelia can damage or disrupt the epithelial barrier that protects underlying tissues. In vitro cell culture systems are an effective means to study how viruses infect and disrupt epithelial barriers, however no true continuous or immortalized feline epithelial cell culture lines are available. A continuous cell culture of feline mammary epithelial cells (FMEC UCD-04-2) that forms tight junctions with high transepithelial electrical resistance (>2000Omegacm(-1)) 3-4 days after reaching confluence was characterized. In addition, it was shown that FMECs are susceptible to infection with feline calicivirus (FCV), feline herpesvirus (FHV-1), feline coronavirus (FeCoV), and feline panleukopenia virus (FPV). These cells will be useful for studies of feline viral disease and for in vitro studies of feline epithelia.


Assuntos
Calicivirus Felino/crescimento & desenvolvimento , Linhagem Celular , Coronavirus Felino/crescimento & desenvolvimento , Células Epiteliais/virologia , Vírus da Panleucopenia Felina/crescimento & desenvolvimento , Varicellovirus/crescimento & desenvolvimento , Animais , Gatos , Técnicas de Cultura de Células , Virologia/métodos
20.
Ann Bot ; 101(7): 909-18, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18285356

RESUMO

BACKGROUND AND AIMS: Changes in chromosome structure and number play an important role in plant evolution. A system well-suited to studying different modes of chromosome evolution is the genus Hypochaeris (Asteraceae) with its centre of species' diversity in South America. All South American species uniformly have a chromosome base number of x = 4 combined with variation in rDNA number and distribution, and a high frequency of polyploidy. The aim of this paper is to assess directions and mechanisms of karyotype evolution in South American species by interpreting both newly obtained and previous data concerning rDNA localization in a phylogenetic context. METHODS: Eleven Hypochaeris species from 18 populations were studied using fluorescence in situ hybridization (FISH) with 35S and 5S rDNA probes. A phylogenetic framework was established from neighbour-net analysis of amplified fragment length polymorphism (AFLP) fingerprint data. KEY RESULTS: A single 5S rDNA locus is invariably found on the short arm of chromosome 2. Using 35S rDNA loci, based on number (one or two) and localization (interstitial on the long arm of chromosome 2, but sometimes lacking, and terminal or interstitial on the short arm of chromosome 3, only very rarely lacking), seven karyotype groups can be distinguished; five of these include polyploids. Karyotype groups with more than one species do not form monophyletic groups. CONCLUSIONS: Early evolution of Hypochaeris in South America was characterized by considerable karyotype differentiation resulting from independent derivations from an ancestral karyotype. There was marked diversification with respect to the position and evolution of the 35S rDNA locus on chromosome 3, probably involving inversions and/or transpositions, and on chromosome 2 (rarely 3) concerning inactivation and loss. Among these different karyotype assemblages, the apargioides group and its derivatives constitute by far the majority of species.


Assuntos
Asteraceae/genética , DNA Ribossômico/genética , Diploide , Evolução Molecular , Poliploidia , Asteraceae/classificação , Cromossomos de Plantas/genética , DNA de Plantas/genética , Variação Genética , Hibridização in Situ Fluorescente , Cariotipagem , Filogenia , América do Sul
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