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1.
New Phytol ; 229(6): 3281-3293, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33020949

RESUMEN

Ensuring faithful homologous recombination in allopolyploids is essential to maintain optimal fertility of the species. Variation in the ability to control aberrant pairing between homoeologous chromosomes in Brassica napus has been identified. The current study exploited the extremes of such variation to identify genetic factors that differentiate newly resynthesised B. napus, which is inherently unstable, and established B. napus, which has adapted to largely control homoeologous recombination. A segregating B. napus mapping population was analysed utilising both cytogenetic observations and high-throughput genotyping to quantify the levels of homoeologous recombination. Three quantitative trait loci (QTL) were identified that contributed to the control of homoeologous recombination in the important oilseed crop B. napus. One major QTL on BnaA9 contributed between 32 and 58% of the observed variation. This study is the first to assess homoeologous recombination and map associated QTLs resulting from deviations in normal pairing in allotetraploid B. napus. The identified QTL regions suggest candidate meiotic genes that could be manipulated in order to control this important trait and further allow the development of molecular markers to utilise this trait to exploit homoeologous recombination in a crop.


Asunto(s)
Brassica napus , Brassica napus/genética , Cromosomas de las Plantas/genética , Genoma de Planta , Poliploidía , Sitios de Carácter Cuantitativo/genética
2.
J Exp Bot ; 72(8): 3012-3027, 2021 04 02.
Artículo en Inglés | MEDLINE | ID: mdl-33502451

RESUMEN

Meiosis generates genetic variation through homologous recombination (HR) that is harnessed during breeding. HR occurs in the context of meiotic chromosome axes and the synaptonemal complex. To study the role of axis remodelling in crossover (CO) formation in a crop species, we characterized mutants of the axis-associated protein ASY1 and the axis-remodelling protein PCH2 in Brassica rapa. asy1 plants form meiotic chromosome axes that fail to synapse. CO formation is almost abolished, and residual chiasmata are proportionally enriched in terminal chromosome regions, particularly in the nucleolar organizing region (NOR)-carrying chromosome arm. pch2 plants show impaired ASY1 loading and remodelling, consequently achieving only partial synapsis, which leads to reduced CO formation and loss of the obligatory CO. PCH2-independent chiasmata are proportionally enriched towards distal chromosome regions. Similarly, in Arabidopsis pch2, COs are increased towards telomeric regions at the expense of (peri-) centromeric COs compared with the wild type. Taken together, in B. rapa, axis formation and remodelling are critical for meiotic fidelity including synapsis and CO formation, and in asy1 and pch2 CO distributions are altered. While asy1 plants are sterile, pch2 plants are semi-sterile and thus PCH2 could be an interesting target for breeding programmes.


Asunto(s)
Brassica rapa , Recombinación Homóloga , Meiosis , Brassica rapa/genética , Emparejamiento Cromosómico , Proteínas de Unión al ADN/genética , Meiosis/genética , Fitomejoramiento , Complejo Sinaptonémico/genética
3.
PLoS Genet ; 11(7): e1005372, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26182244

RESUMEN

Meiotic chromosomes are organized into linear looped chromatin arrays by a protein axis localized along the loop-bases. Programmed remodelling of the axis occurs during prophase I of meiosis. Structured illumination microscopy (SIM) has revealed dynamic changes in the chromosome axis in Arabidopsis thaliana and Brassica oleracea. We show that the axis associated protein ASY1 is depleted during zygotene concomitant with synaptonemal complex (SC) formation. Study of an Atpch2 mutant demonstrates this requires the conserved AAA+ ATPase, PCH2, which localizes to the sites of axis remodelling. Loss of PCH2 leads to a failure to deplete ASY1 from the axes and compromizes SC polymerisation. Immunolocalization of recombination proteins in Atpch2 indicates that recombination initiation and CO designation during early prophase I occur normally. Evidence suggests that CO interference is initially functional in the mutant but there is a defect in CO maturation following designation. This leads to a reduction in COs and a failure to form COs between some homologous chromosome pairs leading to univalent chromosomes at metaphase I. Genetic analysis reveals that CO distribution is also affected in some chromosome regions. Together these data indicate that the axis remodelling defect in Atpch2 disrupts normal patterned formation of COs.


Asunto(s)
Adenosina Trifosfatasas/genética , Proteínas de Arabidopsis/genética , Ensamble y Desensamble de Cromatina/genética , Proteínas de Unión al ADN/genética , Complejo Sinaptonémico/genética , Adenosina Trifosfatasas/biosíntesis , Arabidopsis , Cromosomas de las Plantas , Intercambio Genético , Meiosis/genética
4.
Plant Cell ; 26(2): 729-40, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24563202

RESUMEN

In many cereal crops, meiotic crossovers predominantly occur toward the ends of chromosomes and 30 to 50% of genes rarely recombine. This limits the exploitation of genetic variation by plant breeding. Previous reports demonstrate that chiasma frequency can be manipulated in plants by depletion of the synaptonemal complex protein ZIPPER1 (ZYP1) but conflict as to the direction of change, with fewer chiasmata reported in Arabidopsis thaliana and more crossovers reported for rice (Oryza sativa). Here, we use RNA interference (RNAi) to reduce the amount of ZYP1 in barley (Hordeum vulgare) to only 2 to 17% of normal zygotene levels. In the ZYP1(RNAi) lines, fewer than half of the chromosome pairs formed bivalents at metaphase and many univalents were observed, leading to chromosome nondisjunction and semisterility. The number of chiasmata per cell was reduced from 14 in control plants to three to four in the ZYP1-depleted lines, although the localization of residual chiasmata was not affected. DNA double-strand break formation appeared normal, but the recombination pathway was defective at later stages. A meiotic time course revealed a 12-h delay in prophase I progression to the first labeled tetrads. Barley ZYP1 appears to function similarly to ZIP1/ZYP1 in yeast and Arabidopsis, with an opposite effect on crossover number to ZEP1 in rice, another member of the Poaceae.


Asunto(s)
Intercambio Genético , Hordeum/citología , Hordeum/genética , Meiosis/genética , Proteínas de Plantas/metabolismo , Complejo Sinaptonémico/metabolismo , Cromosomas de las Plantas/genética , Roturas del ADN de Doble Cadena , Regulación de la Expresión Génica de las Plantas , Técnicas de Silenciamiento del Gen , Profase Meiótica I , Datos de Secuencia Molecular , No Disyunción Genética , Filogenia , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Interferencia de ARN , ARN Mensajero/genética , ARN Mensajero/metabolismo , Factores de Tiempo
5.
Proc Natl Acad Sci U S A ; 111(6): 2182-7, 2014 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-24469829

RESUMEN

The Arabidopsis cyclin-dependent kinase G (CDKG) gene defines a clade of cyclin-dependent protein kinases related to CDK10 and CDK11, as well as to the enigmatic Ph1-related kinases that are implicated in controlling homeologous chromosome pairing in wheat. Here we demonstrate that the CDKG1/CYCLINL complex is essential for synapsis and recombination during male meiosis. A transfer-DNA insertional mutation in the cdkg1 gene leads to a temperature-sensitive failure of meiosis in late Zygotene/Pachytene that is associated with defective formation of the synaptonemal complex, reduced bivalent formation and crossing over, and aneuploid gametes. An aphenotypic insertion in the cyclin L gene, a cognate cyclin for CDKG, strongly enhances the phenotype of cdkg1-1 mutants, indicating that this cdk-cyclin complex is essential for male meiosis. Since CYCLINL, CDKG, and their mammalian homologs have been previously shown to affect mRNA processing, particularly alternative splicing, our observations also suggest a mechanism to explain the widespread phenomenon of thermal sensitivity in male meiosis.


Asunto(s)
Proteínas de Arabidopsis/fisiología , Arabidopsis/fisiología , Emparejamiento Cromosómico/fisiología , Calor , Polen , Proteínas Quinasas/metabolismo , Arabidopsis/enzimología , Arabidopsis/genética , Cromosomas de las Plantas , Reacción en Cadena de la Polimerasa
6.
PLoS Genet ; 10(10): e1004674, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25330379

RESUMEN

Meiotic crossovers (COs) shape genetic diversity by mixing homologous chromosomes at each generation. CO distribution is a highly regulated process. CO assurance forces the occurrence of at least one obligatory CO per chromosome pair, CO homeostasis smoothes out the number of COs when faced with variation in precursor number and CO interference keeps multiple COs away from each other along a chromosome. In several organisms, it has been shown that cytoskeleton forces are transduced to the meiotic nucleus via KASH- and SUN-domain proteins, to promote chromosome synapsis and recombination. Here we show that the Arabidopsis kinesin AtPSS1 plays a major role in chromosome synapsis and regulation of CO distribution. In Atpss1 meiotic cells, chromosome axes and DNA double strand breaks (DSBs) appear to form normally but only a variable portion of the genome synapses and is competent for CO formation. Some chromosomes fail to form the obligatory CO, while there is an increased CO density in competent regions. However, the total number of COs per cell is unaffected. We further show that the kinesin motor domain of AtPSS1 is required for its meiotic function, and that AtPSS1 interacts directly with WIP1 and WIP2, two KASH-domain proteins. Finally, meiocytes missing AtPSS1 and/or SUN proteins show similar meiotic defects suggesting that AtPSS1 and SUNs act in the same pathway. This suggests that forces produced by the AtPSS1 kinesin and transduced by WIPs/SUNs, are required to authorize complete synapsis and regulate maturation of recombination intermediates into COs. We suggest that a form of homeostasis applies, which maintains the total number of COs per cell even if only a part of the genome is competent for CO formation.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Emparejamiento Cromosómico , Cinesinas/metabolismo , Meiosis , Proteínas de Arabidopsis/genética , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Endonucleasas/genética , Endonucleasas/metabolismo , Cinesinas/genética , Microtúbulos/metabolismo , Mutación
7.
Plant J ; 81(2): 329-46, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25412930

RESUMEN

The movement of chromosomes during meiosis involves location of their telomeres at the inner surface of the nuclear envelope. Sad1/UNC-84 (SUN) domain proteins are inner nuclear envelope proteins that are part of complexes linking cytoskeletal elements with the nucleoskeleton, connecting telomeres to the force-generating mechanism in the cytoplasm. These proteins play a conserved role in chromosome dynamics in eukaryotes. Homologues of SUN domain proteins have been identified in several plant species. In Arabidopsis thaliana, two proteins that interact with each other, named AtSUN1 and AtSUN2, have been identified. Immunolocalization using antibodies against AtSUN1 and AtSUN2 proteins revealed that they were associated with the nuclear envelope during meiotic prophase I. Analysis of the double mutant Atsun1-1 Atsun2-2 has revealed severe meiotic defects, namely a delay in the progression of meiosis, absence of full synapsis, the presence of unresolved interlock-like structures, and a reduction in the mean cell chiasma frequency. We propose that in Arabidopsis thaliana, overlapping functions of SUN1 and SUN2 ensure normal meiotic recombination and synapsis.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citología , Arabidopsis/metabolismo , Emparejamiento Cromosómico/fisiología , Meiosis/fisiología , Arabidopsis/fisiología , Proteínas de Arabidopsis/genética , Emparejamiento Cromosómico/genética , Meiosis/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo
8.
New Phytol ; 212(3): 693-707, 2016 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-27392293

RESUMEN

Although meiosis is evolutionarily conserved, many of the underlying mechanisms show species-specific differences. These are poorly understood in large genome plant species such as barley (Hordeum vulgare) where meiotic recombination is very heavily skewed to the ends of chromosomes. The characterization of mutant lines can help elucidate how recombination is controlled. We used a combination of genetic segregation analysis, cytogenetics, immunocytology and 3D imaging to genetically map and characterize the barley meiotic mutant DESYNAPTIC 10 (des10). We identified a spontaneous exonic deletion in the orthologue of MutL-Homolog 3 (HvMlh3) as the causal lesion. Compared with wild-type, des10 mutants exhibit reduced recombination and fewer chiasmata, resulting in the loss of obligate crossovers and leading to chromosome mis-segregation. Using 3D structured illumination microscopy (3D-SIM), we observed that normal synapsis progression was also disrupted in des10, a phenotype that was not evident with standard confocal microscopy and that has not been reported with Mlh3 knockout mutants in Arabidopsis. Our data provide new insights on the interplay between synapsis and recombination in barley and highlight the need for detailed studies of meiosis in nonmodel species. This study also confirms the importance of early stages of prophase I for the control of recombination in large genome cereals.


Asunto(s)
Emparejamiento Cromosómico/genética , Intercambio Genético , Hordeum/genética , Mutación/genética , Proteínas de Plantas/genética , Secuencia de Bases , Mapeo Cromosómico , Segregación Cromosómica/genética , Cromosomas de las Plantas/genética , Cruzamientos Genéticos , Reparación de la Incompatibilidad de ADN/genética , Genes de Plantas , Recombinación Homóloga/genética , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo
9.
Plant J ; 77(5): 782-94, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24506176

RESUMEN

In meiosis, chromosome cohesion is maintained by the cohesin complex, which is released in a two-step manner. At meiosis I, the meiosis-specific cohesin subunit Rec8 is cleaved by the protease Separase along chromosome arms, allowing homologous chromosome segregation. Next, in meiosis II, cleavage of the remaining centromere cohesin results in separation of the sister chromatids. In eukaryotes, protection of centromeric cohesion in meiosis I is mediated by SHUGOSHINs (SGOs). The Arabidopsis genome contains two SGO homologs. Here we demonstrate that Atsgo1 mutants show a premature loss of cohesion of sister chromatid centromeres at anaphase I and that AtSGO2 partially rescues this loss of cohesion. In addition to SGOs, we characterize PATRONUS which is specifically required for the maintenance of cohesion of sister chromatid centromeres in meiosis II. In contrast to the Atsgo1 Atsgo2 double mutant, patronus T-DNA insertion mutants only display loss of sister chromatid cohesion after meiosis I, and additionally show disorganized spindles, resulting in defects in chromosome segregation in meiosis. This leads to reduced fertility and aneuploid offspring. Furthermore, we detect aneuploidy in sporophytic tissue, indicating a role for PATRONUS in chromosome segregation in somatic cells. Thus, ploidy stability is preserved in Arabidopsis by PATRONUS during both meiosis and mitosis.


Asunto(s)
Proteínas de Arabidopsis/fisiología , Arabidopsis/fisiología , Proteínas de Ciclo Celular/fisiología , Centrómero/fisiología , Meiosis , Proteínas de Arabidopsis/metabolismo , Proteínas de Ciclo Celular/metabolismo , Segregación Cromosómica , Mitosis , Huso Acromático/fisiología
10.
Plant Cell ; 24(10): 4096-109, 2012 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-23104831

RESUMEN

Meiosis involves reciprocal exchange of genetic information between homologous chromosomes to generate new allelic combinations. In cereals, the distribution of genetic crossovers, cytologically visible as chiasmata, is skewed toward the distal regions of the chromosomes. However, many genes are known to lie within interstitial/proximal regions of low recombination, creating a limitation for breeders. We investigated the factors underlying the pattern of chiasma formation in barley (Hordeum vulgare) and show that chiasma distribution reflects polarization in the spatiotemporal initiation of recombination, chromosome pairing, and synapsis. Consequently, meiotic progression in distal chromosomal regions occurs in coordination with the chromatin cycles that are a conserved feature of the meiotic program. Recombination initiation in interstitial and proximal regions occurs later than distal events, is not coordinated with the cycles, and rarely progresses to form chiasmata. Early recombination initiation is spatially associated with early replicating, euchromatic DNA, which is predominately found in distal regions. We demonstrate that a modest temperature shift is sufficient to alter meiotic progression in relation to the chromosome cycles. The polarization of the meiotic processes is reduced and is accompanied by a shift in chiasma distribution with an increase in interstitial and proximal chiasmata, suggesting a potential route to modify recombination in cereals.


Asunto(s)
Cromosomas de las Plantas/metabolismo , Intercambio Genético , Hordeum/citología , Meiosis/fisiología , Emparejamiento Cromosómico , Cromosomas de las Plantas/ultraestructura , Replicación del ADN , Hordeum/genética , Hordeum/fisiología , Datos de Secuencia Molecular , Complejo Sinaptonémico , Temperatura
11.
PLoS Genet ; 8(2): e1002507, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22319460

RESUMEN

In this study we have analysed AtASY3, a coiled-coil domain protein that is required for normal meiosis in Arabidopsis. Analysis of an Atasy3-1 mutant reveals that loss of the protein compromises chromosome axis formation and results in reduced numbers of meiotic crossovers (COs). Although the frequency of DNA double-strand breaks (DSBs) appears moderately reduced in Atasy3-1, the main recombination defect is a reduction in the formation of COs. Immunolocalization studies in wild-type meiocytes indicate that the HORMA protein AtASY1, which is related to Hop1 in budding yeast, forms hyper-abundant domains along the chromosomes that are spatially associated with DSBs and early recombination pathway proteins. Loss of AtASY3 disrupts the axial organization of AtASY1. Furthermore we show that the AtASY3 and AtASY1 homologs BoASY3 and BoASY1, from the closely related species Brassica oleracea, are co-immunoprecipitated from meiocyte extracts and that AtASY3 interacts with AtASY1 via residues in its predicted coiled-coil domain. Together our results suggest that AtASY3 is a functional homolog of Red1. Since studies in budding yeast indicate that Red1 and Hop1 play a key role in establishing a bias to favor inter-homolog recombination (IHR), we propose that AtASY3 and AtASY1 may have a similar role in Arabidopsis. Loss of AtASY3 also disrupts synaptonemal complex (SC) formation. In Atasy3-1 the transverse filament protein AtZYP1 forms small patches rather than a continuous SC. The few AtMLH1 foci that remain in Atasy3-1 are found in association with the AtZYP1 patches. This is sufficient to prevent the ectopic recombination observed in the absence of AtZYP1, thus emphasizing that in addition to its structural role the protein is important for CO formation.


Asunto(s)
Arabidopsis/genética , Emparejamiento Cromosómico , Intercambio Genético , Proteínas de Unión al ADN/genética , Meiosis/genética , Complejo Sinaptonémico/genética , Arabidopsis/citología , Proteínas de Arabidopsis/genética , Brassica/genética , Cromosomas de las Plantas/genética , Roturas del ADN de Doble Cadena , Mutación , Recombinación Genética , Proteínas de Saccharomyces cerevisiae/genética
12.
Health SA ; 28: 2163, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36873781

RESUMEN

Background: Antenatal care is essential for all expectant mothers and assists in reducing maternal mortality rates thus addressing the Sustainable Development Goal 3. Obstetric ultrasound complements antenatal care and is used in pregnancy to identify and monitor high-risk pregnancies. However, disparities exist and in low- and middle-income countries, ultrasound services are not readily available. This contributes to maternal and neonatal morbidity and mortality within these populations. Short ultrasound training programmes for midwives can be beneficial in alleviating some of the challenges experienced. Aim: The aim of this scoping review was to identify global ultrasound education programmes for midwives. Method: Articles containing suitable keywords were retrieved from databases suitable to nursing, education and ultrasound. Themes were developed based on the articles included in the review. Results: A total of 238 articles were identified, and after the duplicates and irrelevant studies were removed, 22 articles were included. Articles were analysed and discussed under the identified themes and categories. Conclusion: It is essential that sufficient training is provided to medical professionals performing obstetric ultrasound so that adequate and safe care is offered to expectant mothers. With the introduction of ultrasound in low-resource settings, the knowledge of safety and competencies required to operate the equipment necessitate adequate training. Developed programmes have been found to meet the demands of the ever-changing workforce and allow for midwives to perform focused obstetric ultrasound examinations. Contribution: This scoping review highlighted ultrasound training programmes for midwives and provided guidance on the development of future midwifery ultrasound training programmes.

13.
Chromosoma ; 120(3): 287-96, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21327830

RESUMEN

Dioecious Silene latifolia evolved heteromorphic sex chromosomes within the last ten million years, making it a species of choice for studies of the early stages of sex chromosome evolution in plants. About a dozen genes have been isolated from its sex chromosomes and basic genetic and deletion maps exist for the X and Y chromosomes. However, discrepancies between Y chromosome maps led to the proposal that individual Y chromosomes may differ in gene order. Here, we use an alternative approach, with fluorescence in situ hybridization (FISH), to locate individual genes on S. latifolia sex chromosomes. We demonstrate that gene order on the Y chromosome differs between plants from two populations. We suggest that dynamic gene order may be a general property of Y chromosomes in species with XY systems, in view of recent work demonstrating that the gene order on the Y chromosomes of humans and chimpanzees are dramatically different.


Asunto(s)
Evolución Molecular , Orden Génico , Cromosomas Sexuales/genética , Silene/genética , Hibridación Fluorescente in Situ
14.
New Phytol ; 190(3): 523-44, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21366595

RESUMEN

Meiosis is a central feature of sexual reproduction. Studies in plants have made and continue to make an important contribution to fundamental research aimed at the understanding of this complex process. Moreover, homologous recombination during meiosis provides the basis for plant breeders to create new varieties of crops. The increasing global demand for food, combined with the challenges from climate change, will require sustained efforts in crop improvement. An understanding of the factors that control meiotic recombination has the potential to make an important contribution to this challenge by providing the breeder with the means to make fuller use of the genetic variability that is available within crop species. Cytogenetic studies in plants have provided considerable insights into chromosome organization and behaviour during meiosis. More recently, studies, predominantly in Arabidopsis thaliana, are providing important insights into the genes and proteins that are required for crossover formation during plant meiosis. As a result, substantial progress in the understanding of the molecular mechanisms that underpin meiosis in plants has begun to emerge. This article summarizes current progress in the understanding of meiotic recombination and its control in Arabidopsis. We also assess the relationship between meiotic recombination in Arabidopsis and other eukaryotes, highlighting areas of close similarity and apparent differences.


Asunto(s)
Arabidopsis/citología , Arabidopsis/genética , Meiosis/genética , Recombinación Genética , Proteínas de Arabidopsis/metabolismo , Emparejamiento Cromosómico/genética , Roturas del ADN de Doble Cadena
15.
Plant J ; 58(5): 791-802, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19187040

RESUMEN

DNA damage in Arabidopsis thaliana seedlings results in upregulation of hundreds of genes. One of the earliest and highest levels of induction is displayed by a previously uncharacterized gene that we have termed X-ray induced 1 (XRI1). Analysis of plants carrying a null xri1 allele revealed two distinct requirements for this gene in plant fertility. XRI1 was important for the post-meiotic stages of pollen development, leading to inviability of xri(-) pollen and abnormal segregation of the mutant allele in heterozygous xri1(+/-) plants. In addition, XRI1 was essential for male and female meiosis, as indicated by the complete sterility of homozygous xri1 mutants due to extensive chromosome fragmentation visible in meiocytes. Abolition of programmed DNA double-strand breaks in a spo11-1 mutant background failed to rescue the DNA fragmentation of xri1 mutants, suggesting that XRI1 functions at an earlier stage than SPO11-1 does. Yeast two-hybrid studies identified an interaction between XRI1 and a novel component of the Arabidopsis MND1/AHP2 complex, indicating possible requirements for XRI1 in meiotic DNA repair.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Gametogénesis/genética , Meiosis/genética , Alelos , Secuencia de Aminoácidos , Arabidopsis/metabolismo , Arabidopsis/efectos de la radiación , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/efectos de la radiación , Clonación Molecular , Roturas del ADN de Doble Cadena , Fragmentación del ADN , Reparación del ADN , ADN de Plantas/genética , Flores/crecimiento & desarrollo , Meiosis/efectos de la radiación , Datos de Secuencia Molecular , Alineación de Secuencia , Rayos X
16.
Genetics ; 181(2): 811-7, 2009 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-19064703

RESUMEN

Transposable elements often accumulate in nonrecombining regions, such as Y chromosomes. Contrary to this trend, a new Silene retrotransposon described here, has spread recently all over the genome of plant Silene latifolia, except its Y chromosome. This coincided with the latest steps of sex chromosome evolution in this species.


Asunto(s)
Genoma de Planta , Retroelementos/genética , Silene/genética , Evolución Biológica , Cromosomas de las Plantas/genética , Hibridación Fluorescente in Situ , Filogenia , Factores de Tiempo
17.
BMC Public Health ; 10: 744, 2010 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-21122148

RESUMEN

BACKGROUND: Universal screening for postnatal depression is currently being promoted in Australia to assist detection and treatment of affected women, yet debate continues internationally about the effectiveness of screening. One rural shire in Victoria has been screening all women for postnatal depression at maternal and child health checks for many years. This paper explores the views of women affected by this intervention. METHODS: A postal survey was sent to an entire one year cohort of women resident in the shire and eligible for this program [n = 230]. Women were asked whether they recalled having been screened for postnatal depression and what their experience had been, including any referrals made as a result of screening. Women interested in providing additional information were invited to give a phone number for further contact. Twenty women were interviewed in-depth about their experiences. The interview sample was selected to include both depressed and non-depressed women living in town and on rural properties, who represented the range of circumstances of women living in the shire. RESULTS: The return rate for the postal survey was 62% [n = 147/230]. Eighty-seven women indicated that they were interested in further contact, 80 of whom were able to be reached by telephone and 20 were interviewed in-depth. Women had diverse views and experiences of screening. The EPDS proved to be a barrier for some women, and a facilitator for others, in accessing support and referrals. The mediating factor appeared to be a trusting relationship with the nurse able to communicate her concern for the woman and offer support and referrals if required. CONCLUSIONS: Detection of maternal depression requires more than administration of a screening tool at a single time point. While this approach did work for some women, for others it actually made appropriate care and support more difficult. Rather, trained and empathic healthcare providers working in a coordinated primary care service should provide multiple and flexible opportunities for women to disclose and discuss their emotional health issues.


Asunto(s)
Depresión Posparto/diagnóstico , Tamizaje Masivo , Aceptación de la Atención de Salud , Población Rural , Adulto , Femenino , Encuestas de Atención de la Salud , Humanos , Entrevistas como Asunto , Victoria , Adulto Joven
18.
PLoS Genet ; 3(10): 1894-906, 2007 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-17937504

RESUMEN

During meiosis, homologous chromosomes recognize each other, align, and exchange genetic information. This process requires the action of RecA-related proteins Rad51 and Dmc1 to catalyze DNA strand exchanges. The Mnd1-Hop2 complex has been shown to assist in Dmc1-dependent processes. Furthermore, higher eukaryotes possess additional RecA-related proteins, like XRCC3, which are involved in meiotic recombination. However, little is known about the functional interplay between these proteins during meiosis. We investigated the functional relationship between AtMND1, AtDMC1, AtRAD51, and AtXRCC3 during meiosis in Arabidopsis thaliana. We demonstrate the localization of AtMND1 to meiotic chromosomes, even in the absence of recombination, and show that AtMND1 loading depends exclusively on AHP2, the Arabidopsis Hop2 homolog. We provide evidence of genetic interaction between AtMND1, AtDMC1, AtRAD51, and AtXRCC3. In vitro assays suggest that this functional link is due to direct interaction of the AtMND1-AHP2 complex with AtRAD51 and AtDMC1. We show that AtDMC1 foci accumulate in the Atmnd1 mutant, but are reduced in number in Atrad51 and Atxrcc3 mutants. This study provides the first insights into the functional differences of AtRAD51 and AtXRCC3 during meiosis, demonstrating that AtXRCC3 is dispensable for AtDMC1 focus formation in an Atmnd1 mutant background, whereas AtRAD51 is not. These results clarify the functional interactions between key players in the strand exchange processes during meiotic recombination. Furthermore, they highlight a direct interaction between MND1 and RAD51 and show a functional divergence between RAD51 and XRCC3.


Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Meiosis , Fosfotransferasas/genética , Rec A Recombinasas/genética , Cromatina/metabolismo , Dimerización , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Vectores Genéticos , Modelos Genéticos , Datos de Secuencia Molecular , Mutación , Recombinación Genética , Análisis de Secuencia de ADN
19.
Methods Mol Biol ; 2061: 69-78, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31583654

RESUMEN

The genome in situ hybridization (GISH) technique has become important for deciphering the organization of the constituent genomes in the allopolyploid plants that comprise many of the crop species. This technique comprises using the nuclear DNA from the constituent genomes as probes that have been labeled separately with different nucleotides that can be identified by using secondary antibodies. The Brassica family includes a range of mustard species with diverse phytochemical and morphological profile, hence making it an important plant family in agriculture. Meiosis is a specialized cellular division which brings the homologous chromosomes together and creates recombinants via pairing and synapsis during its early phase. Transfer of the genetic material within homoelog pairs creates novelty in subsequent generations which hold promise for improving the agriculture sector. This chapter is concerned with developing a GISH technique that discriminates between the constituent genomes in the allopolyploid B. juncea, in order to study meiosis.


Asunto(s)
Genoma de Planta , Hibridación Genética , Hibridación in Situ/métodos , Planta de la Mostaza/clasificación , Planta de la Mostaza/genética , Cromosomas de las Plantas , Meiosis , Mitosis , Poliploidía
20.
BMJ Open ; 10(6): e035580, 2020 06 17.
Artículo en Inglés | MEDLINE | ID: mdl-32554723

RESUMEN

OBJECTIVES: The implementation of advanced practice nursing (APN) programmes in sub-Saharan Africa (SSA) has been difficult due to lack of SSA-specific curriculum frameworks or benchmarks to guide institutions in developing and implementing APN programmes. A few APN programmes in SSA were benchmarked on western philosophy and materials, making local ownership and sustainability challenging. This paper presents an SSA-specific concept-based APN (Child Health Nurse Practitioner, CHNP) curriculum framework developed to guide institutions in developing relevant and responsive APN curricula in order to qualify CHNP and contribute to a decreased incidence of preventable deaths of children in the SSA region. DESIGN: A sequential multimethod study design consisting of a scoping review, Delphi study, development of a framework by a curriculum team, and evaluation of the curriculum framework by faculty from 15 universities in SSA. SETTING: This study included universities from East, West, Central and Southern Africa. PARTICIPANTS: The study included international multidisciplinary health professionals and curriculum development experts from 15 universities in 10 SSA countries. RESULTS: A concept-based Advanced CHNP curriculum framework was developed. The faculty who evaluated the curriculum framework for applicability within their institutions and the SSA context unanimously stated that the framework is detailed, evidenced-based and could be adapted for other APN specialty areas. CONCLUSION: The Child Health Nurse Practitioner curriculum framework is comprehensive, context-specific and has the potential to respond to the special child healthcare needs of SSA. It is adaptable for other APN specialty programmes in SSA. Nursing leaders should lobby for funding and advocate for the introduction of the CHNP programme as a collaborative process between government, clinical services, communities and educational institutions.


Asunto(s)
Enfermería de Práctica Avanzada/educación , Curriculum , Educación de Postgrado en Enfermería/organización & administración , África del Sur del Sahara , Técnica Delphi , Humanos
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