scholarly journals THE RELATIONSHIP BETWEEN SYNAPTINEMAL COMPLEXES, RECOMBINATION NODULES AND CROSSING OVER IN NEUROSPORA CRASSA BIVALENTS AND TRANSLOCATION QUADRIVALENTS

Genetics ◽  
1979 ◽  
Vol 91 (1) ◽  
pp. 1-17
Author(s):  
C B Gillies
Keyword(s):  
Neurospora Crassa ◽  
Linkage Map ◽  
Central Component ◽  
Crossing Over ◽  
Late Pachytene ◽  
Recombination Nodules ◽  
Crossover Event ◽  
Different Strains ◽  
The Relationship ◽  
Multiple Nodules

ABSTRACT Reconstruction of serially sectioned zygotene and pachytene nuclei has allowed the estimation of both the number and position of central component recombination nodules in the synaptinemal complexes of two chromosomally different strains of Neurospora crussa. In both strains the number of nodules is that expected if each nodule represents one crossover event (50 map units). The distribution of nodules within the arms of bivalents shows evidence of centromeric repulsion and telomeric localizatioa. Nodules appear quite early in the zygotene before pairing of chromosomes is complete. Evidence was found of size differences in nodules, and multiple nodules were occasionally seen. Chromosome lengths and nuclear sizes increased from early zygotene to late pachytene. The three quadrivalents present in the alcoy translocation heterozygotes were readily distinguishable in reconstructions, and their cytological dimensions were in agreement with predictions from linkage map distances.

Two kinds of "recombination nodules" in Neurospora crassa

Genome ◽  
1989 ◽  
Vol 32 (2) ◽  
pp. 309-317 ◽  
Author(s):  
Maja Bojko
Keyword(s):  
Neurospora Crassa ◽  
Synaptonemal Complex ◽  
Nucleolus Organizer ◽  
Crossing Over ◽  
Dramatic Reduction ◽  
Recombination Nodules ◽  
Exchange Event ◽  
The Mean ◽  
Different Origin ◽  
Positive Interference

Two morphological types of recombination nodules, termed early and late, are recognized in Neurospora crassa. Eighty nuclei at different substages were used to determine numbers of nodules per nucleus, distribution of nodules along the nucleolus-organizing chromosome, and distribution of nodules among the two largest chromosomes. Early nodules appear at the synaptonemal complex at early zygotene and increase in number during zygotene until a dramatic reduction occurs at zygotene – pachytene transition. Thereafter early nodules are steadily eliminated until they disappear by diplotene. Late nodules are also present during zygotene. Their number doubles at the zygotene – pachytene transition and stays at this level until diplotene. The total number of nodules is rather constant through zygotene and pachytene. Distribution of bivalents with 0, 1, 2, etc. nodules follows a Poisson distribution at zygotene, but not at pachytene, where variance is less than the mean, indicating positive interference. Nodules are distributed nonrandomly along the nucleolus-organizer bivalent. The pattern differs slightly in nuclei of different origin. Nuclei with unusual synaptonemal complexes sustain normal levels of recombination by having the same amount of nodules as normal nuclei. In abnormal nuclei nodules are preferentially associated with normal segments. It is proposed that early nodules do not participate in any form of recombination but have a role in finding an appropriate site for a crossing-over event. Morphological change to the late type indicates that the site has been reached and the exchange event can be mediated by the late nodule.Key words: recombination nodules, Neurospora crassa, synaptonemal complex.

scholarly journals The relationship of homologous synapsis and crossing over in a maize inversion.

Genetics ◽  
1994 ◽  
Vol 137 (1) ◽  
pp. 281-288 ◽  
Author(s):  
M P Maguire ◽  
R W Riess
Keyword(s):  
Electron Micrographs ◽  
Crossing Over ◽  
Inverted Region ◽  
Recombination Nodule ◽  
Recombination Nodules ◽  
Reciprocal Recombination ◽  
Relationship Of ◽  
The Relationship

Abstract Frequency of homologous synapsis at pachytene for a relatively short heterozygous inversion was compared to the frequency of crossover occurrence within the inversion and to the frequency of the presence of a recombination nodule within the homologously synapsed inverted region. Crossover frequencies were estimated from bridge-fragment frequencies at anaphase I and anaphase II. Recombination nodules (RNs) were observed in electron micrographs. Results show very similar frequencies of homologous synapsis and the occurrence of reciprocal recombination within the inverted region, consistent with the interpretation that establishment of homologous synapsis in this case is related to at least commitment to the form of resolution of crossover intermediates which gives rise to reciprocal recombination, not conversion only, events. An RN was generally found at pachytene in homologously synapsed inverted regions.

scholarly journals Homenagem: Remembering the Life and Work of Abdias Nascimento

2021 ◽  
pp. 002193472110115
Author(s):  
Keisha-Khan Y. Perry ◽  
Anani Dzidzienyo
Keyword(s):  
Military Service ◽  
Black Studies ◽  
Central Component ◽  
Special Issue ◽  
Art And Politics ◽  
Black Politicians ◽  
Brown University ◽  
Black World ◽  
The Relationship

This essay provides a brief introduction to this special issue focused on the life and work of Black Brazilian scholar-activist Abdias Nascimento. The contributors include, Vera Lucia Benedito, Ollie Johnson, Zachary Morgan, Elisa Larkin Nascimento, and Cheryl Sterling who all participated in a 2015 conference at Africana Studies at Brown University. This group of scholars aptly illustrate that Nascimento had long contributed to the internationalization of Black Studies as a field in US academe and he was crucial in establishing Brazil as a central component of the Black World. The essays have much to teach us about Nascimento’s views on the relationship between art and politics, the role of military service in shaping his activism, the significance of black politicians in the reconceptualization of Brazilian democracy, and the importance of preserving archives and expanding our understanding of the Black radical tradition.

scholarly journals The Relationship between Affect Integration and Psychopathology in Patients with Personality Disorder: A Cross-Sectional Study

Medicina ◽  
2021 ◽  
Vol 57 (6) ◽  
pp. 627
Author(s):  
Christina Frederiksen ◽  
Ole André Solbakken ◽  
Rasmus Wentzer Licht ◽  
Carsten René Jørgensen ◽  
Maria Rodrigo-Domingo ◽  
...  
Keyword(s):  
Personality Disorder ◽  
Personality Disorders ◽  
Interpersonal Problems ◽  
Symptom Distress ◽  
Central Component ◽  
Psychotherapeutic Treatment ◽  
Cross Sectional ◽  
Personality Functioning ◽  
Emotional Dysfunction ◽  
The Relationship

Background and Objectives: Emotional dysfunction is considered a key component in personality disorders; however, only few studies have examined the relationship between the two. In this study, emotional dysfunction was operationalized through the Affect Integration Inventory, and the aim was to examine the relationships between the level of affect integration and the levels of symptom distress, interpersonal problems, and personality functioning in patients diagnosed with personality disorder according to the Diagnostic and Statistical Manual of Mental Disorders, fifth edition. Materials and Methods: Within a hospital-based psychiatric outpatient setting, 87 patients with personality disorder referred for treatment were identified for assessment with the Affect Integration Inventory and other measures (e.g., the Symptom Checklist-90, Revised, the Inventory of Interpersonal Problems 64 circumplex version, and the Severity Indices of Personality Problems). Results: The analyses revealed that problems with affect integration were strongly and statistically significantly correlated with high levels of symptom distress, interpersonal problems, and maladaptive personality functioning. Additionally, low scores on the Affect Integration Inventory regarding discrete affects were associated with distinct and differentiated patterns of interpersonal problems. Conclusion: Taken together, emotional dysfunction, as measured by the Affect Integration Inventory, appeared to be a central component of the pathological self-organization associated with personality disorder. These findings have several implications for the understanding and psychotherapeutic treatment of personality pathology. Furthermore, they highlight the importance of considering the integration of discrete affects and their specific contributions in the conceptualization and treatment of emotional dysfunction in patients with personality disorders.

scholarly journals Gene Conversion Alone Accounts for More Than 90% of Recombination Events at the am Locus of Neurospora crassa

Genetics ◽  
1996 ◽  
Vol 143 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Frederick J Bowring ◽  
David E A Catcheside
Keyword(s):  
Molecular Markers ◽  
Neurospora Crassa ◽  
Gene Conversion ◽  
Holliday Junctions ◽  
Crossing Over ◽  
Gene Markers ◽  
General Significance ◽  
Flanking Sequences ◽  
Simple Conversion

Abstract We have used closely flanking molecular markers located ~4 kb distal and 6 kb proximal of the am locus to investigate the incidence of crossover events associated with the generation of prototrophic recombinants in a cross heteroallelic am1 am6. Ninety-three percent of prototrophs were generated by events that did not recombine the molecular markers, indicating that simple conversion accounts for the formation of most prototrophs and that associated crossovers are much less frequent (~0.07) than estimated previously using more distant flanking markers. This suggests that conversion and crossing over during meiosis may arise from distinct mechanisms or that if, as is widely supposed, conversion and crossing over result from alternate modes of resolution of Holliday junctions then, at least for the am locus of Neurospora, the mode of resolution is strongly biased in favor of retaining the parental association of flanking sequences. Because estimates of the association of conversion and crossing over based on more distant gene markers are similar for yeast and Neurospora (~0.35), our observation may have general significance.

scholarly journals Evidence for Negative Interference: Clustering of Crossovers Close to the am Locus in Neurospora crassa Among am Recombinants

Genetics ◽  
1999 ◽  
Vol 152 (3) ◽  
pp. 965-969
Author(s):  
Frederick J Bowring ◽  
David E A Catcheside
Keyword(s):  
Neurospora Crassa ◽  
Molecular Evidence ◽  
Crossing Over ◽  
Negative Interference

Abstract In response to a conflict between two mapping studies in the predicted orientation of the allele map with respect to the centromere, Fincham proposed that recombination events at the Neurospora am locus rarely have an associated crossover. Fincham considered that the elevated levels of crossing over between flanking markers in am recombinants resulted from negative interference, an increased probability of a nearby second event, and on this basis predicted a clustering of crossing over near am in these recombinants. In this article we reevaluate the data from three mapping studies of the am locus and report molecular evidence that shows crossovers to be clustered immediately proximal to am in am recombinants.

scholarly journals A genetic linkage map for the domesticated silkworm, Bombyx mori, based on restriction fragment length polymorphisms

1995 ◽  
Vol 66 (2) ◽  
pp. 109-126 ◽  
Author(s):  
Jinrui Shi ◽  
David G. Heckel ◽  
Marian R. Goldsmith
Keyword(s):  
Linkage Map ◽  
Bombyx Mori ◽  
Restriction Fragment ◽  
Fragment Length ◽  
Restriction Fragment Length Polymorphisms ◽  
Genetic Maps ◽  
Crossing Over ◽  
Linkage Groups ◽  
Length Polymorphisms ◽  
Restriction Fragment Length

SummaryWe present data for the initial construction of a molecular linkage map for the domesticated silkworm, Bombyx mori, based on 52 progeny from an F2 cross from a pair mating of inbred strains p50 and C108, using restriction fragment length polymorphisms (RFLPs). The map contains 15 characterized single copy sequences, 36 anonymous sequences derived from a follicular cDNA library, and 10 loci corresponding to a low copy number retrotransposon, mag. The 15 linkage groups and 8 ungrouped loci account for 23 of the 28 chromosomes and span a total recombination length of 413 cM; 10 linkage groups were correlated with established classic genetic maps. Scoring data from Southern blots were analysed using two Pascal programs written specifically to analyse linkage data in Lepidoptera, where females are the heterogametic sex and have achiasmatic meiosis (no crossing-over). These first examine evidence for linkage by calculating the maximum lod score under the hypothesis that the two loci are linked over the likelihood under the hypothesis that the two loci assort independently, and then determine multilocus linkage maps for groups of putatively syntenic loci by calculating the maximum likelihood estimate of the recombination fractions and the log likelihood using the EM algorithm for a specified order of loci along the chromosome. In addition, the possibility of spurious linkage was exhaustively tested by searching for genotypes forbidden by the absence of crossing-over in one sex.

scholarly journals Science and math teachers as Instructional Designers: Linking ID to the ethic of caring

2008 ◽  
Vol 34 (1) ◽  
Author(s):  
Ellen Rose ◽  
Kate Tingley
Keyword(s):  
Instructional Design ◽  
Central Component ◽  
Instructional Decisions ◽  
Design Activity ◽  
Instructional Designers ◽  
Design Models ◽  
Math Teachers ◽  
Ethic Of Caring ◽  
Exploratory Inquiry ◽  
The Relationship

In this exploratory inquiry into the nature of the relationship between systematic instructional design models and teachers’ planning practices and needs, the researchers conducted open-ended interviews with six teachers of science and math in order to discover how they conceptualized and practiced instructional design. The most important finding to emerge from this research was that, from the teachers’ perspective, caring must be a central component of any instructional design activity. Regardless of gender and grades taught, the teachers indicated that they need to be able to make instructional decisions based upon their caring relationships with individual learners. Les enseignant de sciences et mathématiques comme concepteurs pédagogiques: relier l’identité et l'éthique de la sollicitude Résumé : Dans cette enquête exploratoire de la nature de la relation entre les modèles systématiques de conception pédagogique et les besoins ainsi que la pratique de planification des enseignants, les chercheures ont effectué des entrevues ouvertes avec six enseignants de sciences et mathématiques afin de découvrir leurs représentations et leurs pratiques de la conception pédagogique. Le résultat le plus important émergent de cette enquête a été que selon la perspective des enseignants, la sollicitude se doit d’être une des composantes centrales de n’importe quelle activité de conception pédagogique. Indépendamment du genre et du niveau d’enseignement, les enseignants ont indiqué qu’ils doivent être en mesure de pouvoir faire des décisions pédagogiques en fonction de leurs relations empathiques avec les apprenant individuels.

The relationship between genetic and cytogenetic maps of pea. I. Standard and translocation karyotypes

Genome ◽  
1997 ◽  
Vol 40 (5) ◽  
pp. 744-754 ◽  
Author(s):  
K. J. Hall ◽  
J. S. Parker ◽  
T. H. N. Ellis
Keyword(s):  
Linkage Map ◽  
Synaptonemal Complex ◽  
Chromosome Rearrangement ◽  
Translocation Line ◽  
Mitotic Chromosomes ◽  
Cytogenetic Map ◽  
Cytogenetical Study ◽  
Meiotic Analysis ◽  
Translocation Karyotypes ◽  
The Relationship

A detailed cytogenetical study of inbred lines of pea and their F1 hybrids has been undertaken to study the relationship between the cytogenetic map and the molecular linkage map. The mitotic karyotypes of a standard pea line, JI15, a translocation line, JI61, and line JI281, a line used in the production of a mapping population, are given. A chromosome rearrangement detected by cytogenetic analysis of mitotic chromosomes has been further defined by synaptonemal complex (SC) analysis and the study of metaphase I chromosome behaviour. This meiotic analysis has allowed a comparison of SC physical lengths, observed chiasma frequencies, and recombination frequencies, as estimated from the genetic map, as a means of comparing physical and genetic distances.Key words: Pisum, linkage map, cytogenetics, chromosome rearrangement, synaptonemal complex.

Sign in / Sign up

Export Citation Format

Share Document