scholarly journals Trypanosome outer kinetochore proteins suggest conservation of chromosome segregation machinery across eukaryotes

2016 ◽  
Vol 216 (2) ◽  
pp. 379-391 ◽  
Author(s):  
Simon D’Archivio ◽  
Bill Wickstead

Kinetochores are multiprotein complexes that couple eukaryotic chromosomes to the mitotic spindle to ensure proper segregation. The model for kinetochore assembly is conserved between humans and yeast, and homologues of several components are widely distributed in eukaryotes, but key components are absent in some lineages. The recent discovery in a lineage of protozoa called kinetoplastids of unconventional kinetochores with no apparent homology to model organisms suggests that more than one system for eukaryotic chromosome segregation may exist. In this study, we report a new family of proteins distantly related to outer kinetochore proteins Ndc80 and Nuf2. The family member in kinetoplastids, KKT-interacting protein 1 (KKIP1), associates with the kinetochore, and its depletion causes severe defects in karyokinesis, loss of individual chromosomes, and gross defects in spindle assembly or stability. Immunopurification of KKIP1 from stabilized kinetochores identifies six further components, which form part of a trypanosome outer kinetochore complex. These findings suggest that kinetochores in organisms such as kinetoplastids are built from a divergent, but not ancestrally distinct, set of components and that Ndc80/Nuf2-like proteins are universal in eukaryotic division.

2021 ◽  
Author(s):  
Stephen M Hinshaw ◽  
Yun Quan ◽  
Jiaxi Cai ◽  
Ann Zhou ◽  
Huilin Zhou

Kinetochores control eukaryotic chromosome segregation by connecting chromosomal centromeres to spindle microtubules. Duplication of centromeric DNA necessitates kinetochore disassembly and subsequent reassembly on the nascent sisters. To search for a regulatory mechanism that controls the earliest steps of kinetochore assembly, we studied Mif2/CENP-C, an essential basal component. We found that Polo-like kinase (Cdc5) and Dbf4-dependent kinase (DDK) phosphorylate the conserved PEST region of Mif2/CENP-C and that this phosphorylation directs inner kinetochore assembly. Mif2 phosphorylation promotes kinetochore assembly in a reconstituted biochemical system, and it strengthens Mif2 localization at centromeres in cells. Disrupting one or more phosphorylation sites in the Mif2-PEST region progressively impairs cellular fitness and sensitizes cells to microtubule poisons. The most severe Mif2-PEST mutations are lethal in cells lacking otherwise non-essential Ctf19 complex factors. These data suggest that multi-site phosphorylation of Mif2/CENP-C is a robust switch that controls inner kinetochore assembly, ensuring accurate chromosome segregation.


2019 ◽  
pp. 71-85
Author(s):  
Doris Rodriguez Leal ◽  
Betty Sánchez de Parada ◽  
Patricia Elena Dueñas Granados

Objetivo: Conocer y analizar la muerte materna, a partir de una aproximación a la realidad familiar, al indagar la experiencia vivida por los familiares de la mujer fallecida y valorar los cambios en los roles y la dinámica familiar. Materiales y Métodos: La investigación se realizó mediante metodología cualitativa, a través del estudio de casos; éstos fueron diez familias que tuvieron una muerte materna en los últimos cinco años, atendidas en hospitales y clínicas del departamento del Tolima-Colombia. Resultados: Ante una muerte materna, las familias y cada uno de sus miembros se tornan vulnerables. Cuando se cuenta con el apoyo de otros familiares, amigos o vecinos, el jefe de familia tiene un trabajo, o la familia pertenece a un grupo religioso o red de apoyo social, la situación se hace menos traumática. Las relaciones familiares en algunos casos se fortalecen, en otros empeoran, particularmente entre suegras y yernos. Con respecto a los cuidados maternales, normalmente las abuelas son las que continúan desempeñando el rol de cuidadoras o madres sustitutas. Conclusiones: Este tipo de muertes, pueden generar sentimientos contradictorios, por un lado se vive el dolor por la ausencia del familiar fallecido y por otro, la alegría de un nuevo miembro. La familia vive una situación de duelo ante la muerte de alguien que trae y cuida la vida, considerada como una muerte trágica, prematura y evitable, por lo que la espera de recibir a un nuevo miembro es sustituida por una pérdida. Palabras clave: Mortalidad materna, familia, relaciones familiares, Colombia.   Family experience of maternal death Abstract Objective: Understanding and analyzing maternal death, approaching to the family reality by examining the experience of the family members of the deceased, and evaluating the change of roles and family dynamic. Materials and Methods: The research was made through study cases, using qualitative methodology; these were ten families that experienced maternal death in the last 5 years, and were attended in clinics and hospitals in de department of Tolima-Colombia. Results: Facing maternal death, families and each of their members become vulnerable. Having support from other family members, friends or neighbors, having a job, or belonging to a religious group or social support network, makes the situation less traumatic. Family relations in some cases are strengthened or worsened, particularly between the mother-in-law and son-in-law.  Regarding maternal care, grandmothers normally take the role of caretakers or substitute mothers. Conclusions: These types of deaths cause contradictory feelings, on one hand there is the pain for the absence of a dead family member and on the other, the joy of a new one. The family goes through a situation of facing the death of someone who brings life and cares for it. It is considered a tragic, premature, and avoidable death, consequently the longing of receiving a new family member is substituted by a loss. Keywords: Maternal mortality, family, family relationships, Colombia.   Experiência dos parentes diante da morte materna Resumo Objetivo: Conhecer e analisar a morte materna, a partir de uma aproximação à realidade da família, ao indagar a experiencia vivida pelos parentes da mulher falecida e valorar as mudanças nos papéis e na dinâmica da família. Materiais e Métodos: A pesquisa se realizou utilizando a metodologia qualitativa, através do estudo de casos; estes foram dez famílias que tiveram uma morte materna nos últimos cinco anos, atendidas em hospitais e clínicas do estado de Tolima, na Colômbia. Resultados: Diante uma morte materna, as famílias e cada um de seus membros se tornam vulneráveis. Quando se conta com o apoio de outros parentes, amigos ou vizinhos, o chefe de família tem um trabalho, ou a família pertence a um grupo religioso ou rede de apoio social, a situação se faz menos traumática. Os relacionamentos da família em alguns casos se fortalecem, em outros pioram, particularmente entre sogras e genros. Com respeito aos cuidados maternais, normalmente as avós são as que continuam desempenhando o papel de cuidadoras ou mães substitutas. Conclusões: Este tipo de mortes, podem gerar sentimentos contraditórios, por um lado se vive a dor pela ausência do parente falecido e por outro, a alegria de um novo membro da família. A família vive uma situação de luto diante da morte de alguém que traz e cuida da vida, considerada como uma morte trágica, prematura e evitável, pelo que a espera de receber a um novo membro na família é substituída por uma perda. Palavras-chave: Mortalidade materna, família, relações familiares, Colômbia.


EDIS ◽  
2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Linda B Bobroff ◽  
Nicole Owens Duffy
Keyword(s):  

Feeding your baby is one of the first things you do as a parent. It is also one of the ways that you develop a relationship with this new family member. When feeding goes well, everyone in the family is happier. This 3-page publication can help you develop a close feeding relationship with your baby. The skills you learn will also help you and your child avoid conflicts over food during the toddler and preschool years. Written by Linda B. Bobroff and Nicole Owens Duffy, and published by the UF/IFAS Department of Family, Youth and Community Sciences, revised March 2019.  http://edis.ifas.ufl.edu/he964


2005 ◽  
Vol 16 (12) ◽  
pp. 5649-5660 ◽  
Author(s):  
Kimberly A. Collins ◽  
Andrea R. Castillo ◽  
Sean Y. Tatsutani ◽  
Sue Biggins

Kinetochores mediate chromosome attachment to the mitotic spindle to ensure accurate chromosome segregation. Budding yeast is an excellent organism for kinetochore assembly studies because it has a simple defined centromere sequence responsible for the localization of >65 proteins. In addition, yeast is the only organism where a conditional centromere is available to allow studies of de novo kinetochore assembly. Using a conditional centromere, we found that yeast kinetochore assembly is not temporally restricted and can occur in both G1 phase and prometaphase. We performed the first investigation of kinetochore assembly in the absence of the centromeric histone H3 variant Cse4 and found that all proteins tested depend on Cse4 to localize. Consistent with this observation, Cse4-depleted cells had severe chromosome segregation defects. We therefore propose that yeast kinetochore assembly requires both centromeric DNA specificity and centromeric chromatin.


2005 ◽  
Vol 25 (10) ◽  
pp. 3967-3981 ◽  
Author(s):  
Vinciane Régnier ◽  
Paola Vagnarelli ◽  
Tatsuo Fukagawa ◽  
Tatiana Zerjal ◽  
Elizabeth Burns ◽  
...  

ABSTRACT CENP-A is an evolutionarily conserved, centromere-specific variant of histone H3 that is thought to play a central role in directing kinetochore assembly and in centromere function. Here, we have analyzed the consequences of disrupting the CENP-A gene in the chicken DT40 cell line. In CENP-A-depleted cells, kinetochore protein assembly is impaired, as indicated by mislocalization of the inner kinetochore proteins CENP-I, CENP-H, and CENP-C as well as the outer components Nuf2/Hec1, Mad2, and CENP-E. However, BubR1 and the inner centromere protein INCENP are efficiently recruited to kinetochores. Following CENP-A depletion, chromosomes are deficient in proper congression on the mitotic spindle and there is a transient delay in prometaphase. CENP-A-depleted cells further proceed through anaphase and cytokinesis with unequal chromosome segregation, suggesting that some kinetochore function remains following substantial depletion of CENP-A. We furthermore demonstrate that CENP-A-depleted cells exhibit a specific defect in maintaining kinetochore localization of the checkpoint protein BubR1 under conditions of checkpoint activation. Our data thus point to a specific role for CENP-A in assembly of kinetochores competent in the maintenance of mitotic checkpoint signaling.


2020 ◽  
Vol 64 (2) ◽  
pp. 251-261
Author(s):  
Jessica E. Fellmeth ◽  
Kim S. McKim

Abstract While many of the proteins involved in the mitotic centromere and kinetochore are conserved in meiosis, they often gain a novel function due to the unique needs of homolog segregation during meiosis I (MI). CENP-C is a critical component of the centromere for kinetochore assembly in mitosis. Recent work, however, has highlighted the unique features of meiotic CENP-C. Centromere establishment and stability require CENP-C loading at the centromere for CENP-A function. Pre-meiotic loading of proteins necessary for homolog recombination as well as cohesion also rely on CENP-C, as do the main scaffolding components of the kinetochore. Much of this work relies on new technologies that enable in vivo analysis of meiosis like never before. Here, we strive to highlight the unique role of this highly conserved centromere protein that loads on to centromeres prior to M-phase onset, but continues to perform critical functions through chromosome segregation. CENP-C is not merely a structural link between the centromere and the kinetochore, but also a functional one joining the processes of early prophase homolog synapsis to late metaphase kinetochore assembly and signaling.


Think India ◽  
2013 ◽  
Vol 16 (3) ◽  
pp. 10-19
Author(s):  
Ang Bao

The objective of this paper is to find the relationship between family firms’ CSR engagement and their non-family member employees’ organisational identification. Drawing upon the existing literature on social identity theory, corporate social responsibility and family firms, the author proposes that family firms engage actively in CSR programs in a balanced manner to increase non-family member employees’ organisational identification. The findings of the research suggest that by developing and implementing balanced CSR programs, and actively getting engaged in CSR activities, family firms may help their non-family member employees better identify themselves with the firms. The article points out that due to unbalanced CSR resource allocation, family firms face the problem of inefficient CSR program implementation, and are suggested to switch alternatively to an improved scheme. Family firms may be advised to take corresponding steps to select right employees, communicate better with non-family member employees, use resources better and handle firms’ succession problems efficiently. The paper extends employees’ identification and CSR research into the family firm research domain and points out some drawbacks in family firms’ CSR resource allocation while formerly were seldom noticed.


2011 ◽  
Vol 20 (1) ◽  
pp. 161-173
Author(s):  
A.P. Kassatkina

Resuming published and own data, a revision of classification of Chaetognatha is presented. The family Sagittidae Claus & Grobben, 1905 is given a rank of subclass, Sagittiones, characterised, in particular, by the presence of two pairs of sac-like gelatinous structures or two pairs of fins. Besides the order Aphragmophora Tokioka, 1965, it contains the new order Biphragmosagittiformes ord. nov., which is a unique group of Chaetognatha with an unusual combination of morphological characters: the transverse muscles present in both the trunk and the tail sections of the body; the seminal vesicles simple, without internal complex compartments; the presence of two pairs of lateral fins. The only family assigned to the new order, Biphragmosagittidae fam. nov., contains two genera. Diagnoses of the two new genera, Biphragmosagitta gen. nov. (type species B. tarasovi sp. nov. and B. angusticephala sp. nov.) and Biphragmofastigata gen. nov. (type species B. fastigata sp. nov.), detailed descriptions and pictures of the three new species are presented.


2021 ◽  
pp. 003022282110244
Author(s):  
Júlia Camargo Contessa ◽  
Carolina Stopinski Padoan ◽  
Jéssica Leandra Gonçalves da Silva ◽  
Pedro V. S. Magalhães

The suicide of a loved one can be a traumatic experience. The objective of this study was to investigate trauma-related experiences of suicide survivors. This is a qualitative study with people who had recently lost a family member or a close one to suicide, conducted at least two months after the event. Forty-one participants agreed to take part in the study and were interviewed. The interviewees' perception was that suicide brought harm, symptoms, and suffering. Traumatic experiences can begin immediately after the event, with many reporting symptoms lasting many months and persistent impact, both personal and to the family. Postvention models after suicide should incorporate such findings, and investigate trauma consistently.


Cancers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2670
Author(s):  
Moira O’Connor ◽  
Greta Smith ◽  
Ashleigh Pantaleo ◽  
Darren Haywood ◽  
Rhys Weaver ◽  
...  

Sarcomas are a group of rare and aggressive cancers, which develop in bones and connective tissue throughout the body. Sarcomas account for only 1–2% of all cancers worldwide; however, mortality rates for sarcoma are high with approximately two in four sarcoma patients dying following a diagnosis. Delays in diagnosis, poor management of symptoms, patients’ high symptom loads and high carer burden are all associated with carer distress, which may lead to complications after bereavement. The experience of having a family member referred for palliative care is also distressing for carers, with the realisation that their family member is dying. This study aimed to explore the experiences of bereaved family carers of people diagnosed with sarcoma. A qualitative descriptive design using a social constructionist framework was adopted. Interviews were conducted with sixteen participants, and thematic analysis was used to identify patterns in the data. Four overarching themes emerged: beginning the journey; moving through treatment; transitioning to palliative care; and experiencing bereavement. The narratives were coherent and potent, and people reflected on their journeys. Interventions and supports for bereaved carers could include opportunities for counselling to support reflections, supports for developing a narrative such as writing therapy, and preparation for the death of the family member.


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