A dual-function SNF2 protein drives chromatid resolution and nascent transcripts removal in mitosis.

Mitotic chromatin is largely assumed incompatible with transcription due to changes in the transcription machinery and chromosome architecture. However, the mechanisms of mitotic transcriptional inactivation and their interplay with chromosome assembly remain largely unknown. By monitoring ongoing transcription in Drosophila early embryos, we reveal that eviction of nascent mRNAs from mitotic chromatin occurs after substantial chromosome compaction and is not promoted by condensin I. Instead, we show that the timely removal of transcripts from mitotic chromatin is driven by the SNF2 helicase-like protein Lodestar (Lds), identified here as a modulator of sister chromatid cohesion defects. In addition to the eviction of nascent transcripts, we uncover that Lds cooperates with Topoisomerase 2 to ensure efficient sister chromatid resolution and mitotic fidelity. We conclude that the removal of nascent transcripts upon mitotic entry is not a passive consequence of cell cycle progression and/or chromosome compaction but occurs via dedicated mechanisms with functional parallelisms to sister chromatid resolution.

Endoplasmic reticulum membranes are continuously required to maintain mitotic spindle size and forces.

Membrane organelle function, localization, and proper partitioning upon cell division depend on interactions with the cytoskeleton. Whether membrane organelles also impact the function of cytoskeletal elements remains less clear. Here, we show that acute disruption of the ER around spindle poles affects mitotic spindle size and function in Drosophila syncytial embryos. Acute ER disruption was achieved through the inhibition of ER membrane fusion by the dominant-negative cytoplasmic domain of atlastin. We reveal that when centrosome-proximal ER membranes are disrupted, specifically at metaphase, mitotic spindles become smaller, despite no significant changes in microtubule dynamics. These smaller spindles are still able to mediate sister chromatid separation, yet with decreased velocity. Furthermore, by inducing mitotic exit, we found that nuclear separation and distribution are affected by ER disruption. Our results suggest that ER integrity around spindle poles is crucial for the maintenance of mitotic spindle shape and pulling forces. In addition, ER integrity also ensures nuclear spacing during syncytial divisions.

The crown lengthening double guide and the digital Perio analysis.

OBJECTIVE: This article describes a surgical crown lengthening double guide, which was digitally obtained to improve diagnosis, treatment outcome, and follow-up. CLINICAL CONSIDERATIONS: The rehabilitation of anterior dental esthetics should involve interdisciplinary and facially driven planning for achieving pleasant long-term outcomes. Surgical crown lengthening is one of the most common periodontal surgery, which can be assisted by digital tools to improve surgical planning and follow-up. CONCLUSION: The double guide for surgical crown lengthening allows the proper management of hard and soft tissues for achieving a predefined goal based on biological requirements and facially driven planning. In addition, the digital quality control allows the follow-up compared with the pre-operative condition and planned treatment plan. CLINICAL SIGNIFICANCE: The use of digital tools allow the clinician to develop a facially driven planning with proper communication with the team and patient, leading to a shorter, more predictable, and less invasive surgical technique, reducing postoperative inflammation and increasing patient comfort.

Biallelic BUB1 mutations cause microcephaly, developmental delay, and variable effects on cohesion and chromosome segregation.

Budding uninhibited by benzimidazoles (BUB1) contributes to multiple mitotic processes. Here, we describe the first two patients with biallelic BUB1 germline mutations, who both display microcephaly, intellectual disability, and several patient-specific features. The identified mutations cause variable degrees of reduced total protein level and kinase activity, leading to distinct mitotic defects. Both patients' cells show prolonged mitosis duration, chromosome segregation errors, and an overall functional spindle assembly checkpoint. However, while BUB1 levels mostly affect BUBR1 kinetochore recruitment, impaired kinase activity prohibits centromeric recruitment of Aurora B, SGO1, and TOP2A, correlating with anaphase bridges, aneuploidy, and defective sister chromatid cohesion. We do not observe accelerated cohesion fatigue. We hypothesize that unresolved DNA catenanes increase cohesion strength, with concomitant increase in anaphase bridges. In conclusion, BUB1 mutations cause a neurodevelopmental disorder, with clinical and cellular phenotypes that partially resemble previously described syndromes, including autosomal recessive primary microcephaly, mosaic variegated aneuploidy, and cohesinopathies.

Characterization of a MOB1 Homolog in the Apicomplexan Parasite Toxoplasma gondii.

Monopolar spindle One Binder1 (MOB1) proteins are conserved components of the tumor-suppressing Hippo pathway, regulating cellular processes such as cytokinesis. Apicomplexan parasites present a life cycle that relies on the parasites' ability to differentiate between stages and regulate their proliferation; thus, Hippo signaling pathways could play an important role in the regulation of the apicomplexan life cycle. Here, we report the identification of one MOB1 protein in the apicomplexan Toxoplasma gondii. To characterize the function of MOB1, we generated gain-of-function transgenic lines with a ligand-controlled destabilization domain, and loss-of-function clonal lines obtained through CRISPR/Cas9 technology. Contrary to what has been characterized in other eukaryotes, MOB1 is not essential for cytokinesis in T. gondii. However, this picture is complex since we found MOB1 localized between the newly individualized daughter nuclei at the end of mitosis. Moreover, we detected a significant delay in the replication of overexpressing tachyzoites, contrasting with increased replication rates in knockout tachyzoites. Finally, using the proximity-biotinylation method, BioID, we identified novel members of the MOB1 interactome, a probable consequence of the observed lack of conservation of some key amino acid residues. Altogether, the results point to a complex evolutionary history of MOB1 roles in apicomplexans, sharing properties with other eukaryotes but also with divergent features, possibly associated with their complex life cycle.

Formação, lazer e currículo: os cursos de Educação Física do Tocantins / Training, leisure and curriculum: the phisical education courses of Tocantins

O estudo teve como objetivo analisar a inserção do lazer nos currículos de Educação Física das instituições de ensino superior (IES) públicas do estado do Tocantins. A proposta metodológica da pesquisa teve inspiração no Estudo de Casos Múltiplos. Fizeram parte da pesquisa três cursos de licenciatura em Educação Física públicos existentes no estado. Para a coleta de dados utilizamos a análise documental, aplicação de questionários e entrevistas. O estudo demonstrou como o lazer se organiza no ensino, na pesquisa e na extensão das IES pesquisadas, além de mapear os espaços e algumas peculiaridades de cada curso. Todos os cursos de Educação Física pesquisados apresentam disciplinas sobre o lazer em seus currículos e ofertam projetos de extensão na área de esporte e/ou lazer. No que tange as produções acadêmico-cientificas apenas dois cursos estudados apresentaram publicações. Entendemos que o lazer precisa estar cada vez mais presente na formação dos profissionais de Educação Física.

This study aimed to analyze the insertion of leisure in the Physical Education curricula of public higher education institutions (HEIs) in the state of Tocantins/Brazil. The Multiple Case Study inspired the methodological proposal of the research. For this study were part of the research three undergraduate courses in Public Physical Education existing in the state. For the collection of data we used the documentary analysis, application of questionnaires and interviews. The study demonstrates how leisure is organized in the teaching, research and extension of HEIs researched, in addition to mapping the spaces and some peculiarities of each course. All the Physical Education courses researched present leisure disciplines in their curricula and offer extension projects in the area of sports and / or leisure. As far as academicscientific productions are concerned, only two courses studied presented publications. We understand that leisure needs to be increasingly present in the training of Physical Education professionals.

'Waking up' to the symbolic: a psychoanalytic investigation into the effects of a music workshop for children with Pervasive Developmental Disorders (PDDs) / "acordar" para o simbólico: uma investigação psicanalítica sobre os efeitos de um ateliê musical para crianças com transtornos globais do desenvolvimento (tgd)

RESUMO: A pesquisa Os efeitos do ritmo como função de estruturação psíquica em crianças com TGD se propôs a acompanhar os efeitos de um ateliê musical sobre um grupo de crianças com Transtornos Globais do Desenvolvimento (TGD). Trabalhamos com a hipótese de que a atenção a propriedades musicais pode favorecer o desenvolvimento da linguagem e enlaçamento social nesses casos. A partir de recortes clínicos construídos à luz do método psicanalítico, o artigo discute de que maneira a música atrelada à psicanálise pode favorecer o surgimento do sujeito desejante.

Abstract: The research Rhythm effects as psychic structuring function in children with PDD aimed to follow the effects of a musical atelier on a group of children with Pervasive Developmental Disorders - PPD. We worked with the hypotheses that the attention to musical proprieties can favor language development and social binding in these cases. Starting from clinical clippings built through the psychoanalytic method, this article discusses in which way the music associated to psychoanalysis can favor the emergence of the desiring subject.

Induced aneuploidy in neural stem cells triggers a delayed stress response and impairs adult life span in flies.

Studying aneuploidy during organism development has strong limitations because chronic mitotic perturbations used to generate aneuploidy usually result in lethality. We developed a genetic tool to induce aneuploidy in an acute and time-controlled manner during Drosophila development. This is achieved by reversible depletion of cohesin, a key molecule controlling mitotic fidelity. Larvae challenged with aneuploidy hatch into adults with severe motor defects shortening their life span. Neural stem cells, despite being aneuploid, display a delayed stress response and continue proliferating, resulting in the rapid appearance of chromosomal instability, a complex array of karyotypes, and cellular abnormalities. Notably, when other brain-cell lineages are forced to self-renew, aneuploidy-associated stress response is significantly delayed. Protecting only the developing brain from induced aneuploidy is sufficient to rescue motor defects and adult life span, suggesting that neural tissue is the most ill-equipped to deal with developmental aneuploidy.

A quantitative analysis of cohesin decay in mitotic fidelity.

Sister chromatid cohesion mediated by cohesin is essential for mitotic fidelity. It counteracts spindle forces to prevent premature chromatid individualization and random genome segregation. However, it is unclear what effects a partial decline of cohesin may have on chromosome organization. In this study, we provide a quantitative analysis of cohesin decay by inducing acute removal of defined amounts of cohesin from metaphase-arrested chromosomes. We demonstrate that sister chromatid cohesion is very resistant to cohesin loss as chromatid disjunction is only observed when chromosomes lose >80% of bound cohesin. Removal close to this threshold leads to chromosomes that are still cohered but display compromised chromosome alignment and unstable spindle attachments. Partial cohesin decay leads to increased duration of mitosis and susceptibility to errors in chromosome segregation. We propose that high cohesin density ensures centromeric chromatin rigidity necessary to maintain a force balance with the mitotic spindle. Partial cohesin loss may lead to chromosome segregation errors even when sister chromatid cohesion is fulfilled.

Three decades of reference evapotranspiration estimates for a tropical watershed in the eastern Amazon.

This study estimated the reference evapotranspiration rate (ETo) for the Itacaiúnas River Watershed (IRW), Eastern Amazonia, and measured the accuracy of eight empirical equations: Penman-Monteith (PM), Priestley-Taylor (PT), Hargreaves and Samani (HS), Camargo (CAM), Thornthwaite (TH), Hamon (HM), Kharrufa (KF) and Turc (TC) using monthly data from 1980 to 2013. In addition, it verifies the regional applicability to the IRW using a for the Marabá-PA station. The methods TC and PM (FAO56) presented the best results, which demonstrate that radiation and higher temperatures are the dominant drivers in the Evapotranspiration process, while relative humidity and wind speed have a much smaller impact. The temporal and spatial variability of ETo for IRW show has strong seasonality, increasing during the dry season and decreasing during the rainy season. The statistical analyses at 1% level of significance, indicates that there is no correlation of the residuals between the dry and rainy seasons, and test of the physical parameters such as mean temperature, solar radiation and relative air humidity explains the variations of ETo.

Da vibração ao encontro com o outro: psicanálise, música e autismo / From vibration to meeting with other: phychoanalysis, music and autism / De la vibración al encuentro con el otro: psicoanálisis, música y autismo

O estudo, partindo do princípio de que o ritmo permeia a estruturação psíquica, investigou os efeitos de um ateliê musical como formador de laço entre crianças autistas e seus semelhantes. O ateliê, com encontros semanais, era formado por crianças de dois a quatro anos. Foram interventores: psicólogas, psicanalistas, uma professora de música, uma fonoaudióloga e estudantes de psicologia da Universidade Ceuma. Os resultados foram descritos por meio de um estudo de caso, discutido sob o referencial da psicanálise. Conclui-se que a linguagem musical pode auxiliar no estabelecimento de vínculos, sendo esta linguagem não ameaçadora e intrusiva.

The study investigated the effects of a musical atelier as in instrument to create bond between autistic children with pairs. It was assumed that rhythm permeates psychic structuring. The atelier, which happened once a week, was composed by children aged two to four. The interventors were: one speech therapist, psychologists and students of the Psychology at Ceuma University. The results were described through a case study, done with a three year old child and discussed under the theoretical reference of psychoanalysis. It concluded that the musical language can help in the establishment of bond with autistic children, since this language is not threatening and intrusive.

El estudio investigó los efectos de un taller musical como formador de lazos entre los niños autistas y sus semejantes. Se supone que el ritmo impregna la estructura psíquica. Formaran parte del taller, con reuniones semanales, niños de dos a cuatro años. Los interventores fueron: psicólogos, psicoanalistas, un profesor de música, un terapeuta del habla y estudiantes de psicología de la Universidad Ceuma. Los resultados fueron presentados en un estudio de caso analizado desde la teoria psicoanálitica. Llegamos a la conclusión de que el lenguaje musical puede ayudar a formar una unión que no sea amenazadora y intrusiva.

Metaphase chromosome structure is dynamically maintained by condensin I-directed DNA (de)catenation.

Mitotic chromosome assembly remains a big mystery in biology. Condensin complexes are pivotal for chromosome architecture yet how they shape mitotic chromatin remains unknown. Using acute inactivation approaches and live-cell imaging in Drosophila embryos, we dissect the role of condensin I in the maintenance of mitotic chromosome structure with unprecedented temporal resolution. Removal of condensin I from pre-established chromosomes results in rapid disassembly of centromeric regions while most chromatin mass undergoes hyper-compaction. This is accompanied by drastic changes in the degree of sister chromatid intertwines. While wild-type metaphase chromosomes display residual levels of catenations, upon timely removal of condensin I, chromosomes present high levels of de novo Topoisomerase II (TopoII)-dependent re-entanglements, and complete failure in chromosome segregation. TopoII is thus capable of re-intertwining previously separated DNA molecules and condensin I continuously required to counteract this erroneous activity. We propose that maintenance of chromosome resolution is a highly dynamic bidirectional process.

Three decades of reference evapotranspiration estimates for a tropical watershed in the eastern Amazon

ABSTRACT This study estimated the reference evapotranspiration rate (ETo) for the Itacaiúnas River Watershed (IRW), Eastern Amazonia, and measured the accuracy of eight empirical equations: Penman-Monteith (PM), Priestley-Taylor (PT), Hargreaves and Samani (HS), Camargo (CAM), Thornthwaite (TH), Hamon (HM), Kharrufa (KF) and Turc (TC) using monthly data from 1980 to 2013. In addition, it verifies the regional applicability to the IRW using a for the Marabá-PA station. The methods TC and PM (FAO56) presented the best results, which demonstrate that radiation and higher temperatures are the dominant drivers in the Evapotranspiration process, while relative humidity and wind speed have a much smaller impact. The temporal and spatial variability of ETo for IRW show has strong seasonality, increasing during the dry season and decreasing during the rainy season. The statistical analyses at 1% level of significance, indicates that there is no correlation of the residuals between the dry and rainy seasons, and test of the physical parameters such as mean temperature, solar radiation and relative air humidity explains the variations of ETo.

Centromere-independent accumulation of cohesin at ectopic heterochromatin sites induces chromosome stretching during anaphase.

Pericentric heterochromatin, while often considered as "junk" DNA, plays important functions in chromosome biology. It contributes to sister chromatid cohesion, a process mediated by the cohesin complex that ensures proper genome segregation during nuclear division. Long stretches of heterochromatin are almost exclusively placed at centromere-proximal regions but it remains unclear if there is functional (or mechanistic) importance in linking the sites of sister chromatid cohesion to the chromosomal regions that mediate spindle attachment (the centromere). Using engineered chromosomes in Drosophila melanogaster, we demonstrate that cohesin enrichment is dictated by the presence of heterochromatin rather than centromere proximity. This preferential accumulation is caused by an enrichment of the cohesin-loading factor (Nipped-B/NIPBL/Scc2) at dense heterochromatic regions. As a result, chromosome translocations containing ectopic pericentric heterochromatin embedded in euchromatin display additional cohesin-dependent constrictions. These ectopic cohesion sites, placed away from the centromere, disjoin abnormally during anaphase and chromosomes exhibit a significant increase in length during anaphase (termed chromatin stretching). These results provide evidence that long stretches of heterochromatin distant from the centromere, as often found in many cancers, are sufficient to induce abnormal accumulation of cohesin at these sites and thereby compromise the fidelity of chromosome segregation.

The expression of tubulin cofactor A (TBCA) is regulated by a noncoding antisense Tbca RNA during testis maturation.

BACKGROUND: Recently, long noncoding RNAs have emerged as pivotal molecules for the regulation of coding genes' expression. These molecules might result from antisense transcription of functional genes originating natural antisense transcripts (NATs) or from transcriptional active pseudogenes. TBCA interacts with ß-tubulin and is involved in the folding and dimerization of new tubulin heterodimers, the building blocks of microtubules. METHODOLOGY/PRINCIPAL FINDINGS: We found that the mouse genome contains two structurally distinct Tbca genes located in chromosomes 13 (Tbca13) and 16 (Tbca16). Interestingly, the two Tbca genes albeit ubiquitously expressed, present differential expression during mouse testis maturation. In fact, as testis maturation progresses Tbca13 mRNA levels increase progressively, while Tbca16 mRNA levels decrease. This suggests a regulatory mechanism between the two genes and prompted us to investigate the presence of the two proteins. However, using tandem mass spectrometry we were unable to identify the TBCA16 protein in testis extracts even in those corresponding to the maturation step with the highest levels of Tbca16 transcripts. These puzzling results led us to re-analyze the expression of Tbca16. We then detected that Tbca16 transcription produces sense and natural antisense transcripts. Strikingly, the specific depletion by RNAi of these transcripts leads to an increase of Tbca13 transcript levels in a mouse spermatocyte cell line. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that Tbca13 mRNA levels are post-transcriptionally regulated by the sense and natural antisense Tbca16 mRNA levels. We propose that this regulatory mechanism operates during spermatogenesis, a process that involves microtubule rearrangements, the assembly of specific microtubule structures and requires critical TBCA levels.

Mob1: defining cell polarity for proper cell division.

Mob1 is a component of both the mitotic exit network and Hippo pathway, being required for cytokinesis, control of cell proliferation and apoptosis. Cell division accuracy is crucial in maintaining cell ploidy and genomic stability and relies on the correct establishment of the cell division axis, which is under the control of the cell's environment and its intrinsic polarity. The ciliate Tetrahymena thermophila possesses a permanent anterior-posterior axis, left-right asymmetry and divides symmetrically. These unique features of Tetrahymena prompted us to investigate the role of Tetrahymena Mob1. Unexpectedly, we found that Mob1 accumulated in basal bodies at the posterior pole of the cell, and is the first molecular polarity marker so far described in Tetrahymena. In addition, Mob1 depletion caused the abnormal establishment of the cell division plane, providing clear evidence that Mob1 is important for its definition. Furthermore, cytokinesis was arrested and ciliogenesis delayed in Tetrahymena cells depleted of Mob1. This is the first evidence for an involvement of Mob1 in cilia biology. In conclusion, we show that Mob1 is an important cell polarity marker that is crucial for correct division plane placement, for cytokinesis completion and for normal cilia growth rates.

CCTalpha and CCTdelta chaperonin subunits are essential and required for cilia assembly and maintenance in Tetrahymena.

BACKGROUND: The eukaryotic cytosolic chaperonin CCT is a hetero-oligomeric complex formed by two rings connected back-to-back, each composed of eight distinct subunits (CCTalpha to CCTzeta). CCT complex mediates the folding, of a wide range of newly synthesised proteins including tubulin (alpha, beta and gamma) and actin, as quantitatively major substrates. METHODOLOGY/PRINCIPAL FINDINGS: We disrupted the genes encoding CCTalpha and CCTdelta subunits in the ciliate Tetrahymena. Cells lacking the zygotic expression of either CCTalpha or CCTdelta showed a loss of cell body microtubules, failed to assemble new cilia and died within 2 cell cycles. We also show that loss of CCT subunit activity leads to axoneme shortening and splaying of tips of axonemal microtubules. An epitope-tagged CCTalpha rescued the gene knockout phenotype and localized primarily to the tips of cilia. A mutation in CCTalpha, G346E, at a residue also present in the related protein implicated in the Bardet Biedel Syndrome, BBS6, also caused defects in cilia and impaired CCTalpha localization in cilia. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that the CCT subunits are essential and required for ciliary assembly and maintenance of axoneme structure, especially at the tips of cilia.

Revisiting the tubulin folding pathway: new roles in centrosomes and cilia.

Centrosomes and cilia are critical eukaryotic organelles which have been in the spotlight in recent years given their implication in a myriad of cellular and developmental processes. Despite their recognized importance and intense study, there are still many open questions about their biogenesis and function. In the present article, we review the existing data concerning members of the tubulin folding pathway and related proteins, which have been identified at centrosomes and cilia and were shown to have unexpected roles in these structures.