Mitosis Research Papers - Academia.edu (original) (raw)

The purpose of the present investigation was to study the effect of delay in fixation on the mitotic activity in tumour tissue. A human osteogenic sarcoma, especially suitable for counting of mitoses, grown in athymic nude mice, was fixed... more

The purpose of the present investigation was to study the effect of delay in fixation on the mitotic activity in tumour tissue. A human osteogenic sarcoma, especially suitable for counting of mitoses, grown in athymic nude mice, was fixed with varying delay and the mitotic, prophase, metaphase and ana-telophase indices were determined. An almost exponential decline of the mitotic index was observed with a reduction to 49.4% and 15.0% after respectively 60 and 180 minutes. The proportional incidence of prophases, metaphases and ana-telophases changed so that a relative accummulation of advanced phases occured during the 180 minutes of observation. It is concluded that delay in fixation of a magnitude, which is not uncommon in routine surgical pathology, may allow the majority of mitoses to terminate, resulting in unreliable assessments of mitotic activity.

Tumor-treating fields (TTFields) is an antimitotic treatment modality that interferes with glioblastoma cell division and organelle assembly by delivering low-intensity alternating electric fields to the tumor. To investigate whether... more

Tumor-treating fields (TTFields) is an antimitotic treatment modality that interferes with glioblastoma cell division and organelle assembly by delivering low-intensity alternating electric fields to the tumor. To investigate whether TTFields improves progression-free and overall survival of patients with glioblastoma, a fatal disease that commonly recurs at the initial tumor site or in the central nervous system. In this randomized, open-label trial, 695 patients with glioblastoma whose tumor was resected or biopsied and had completed concomitant radiochemotherapy (median time from diagnosis to randomization, 3.8 months) were enrolled at 83 centers (July 2009-2014) and followed up through December 2016. A preliminary report from this trial was published in 2015; this report describes the final analysis. Patients were randomized 2:1 to TTFields plus maintenance temozolomide chemotherapy (n = 466) or temozolomide alone (n = 229). The TTFields, consisting of low-intensity, 200 kHz fre...

Summary Primary cilia, which emanate from the cell surface, exhibit assembly and disassembly dynamics along the progression of cell cycle. However, the mechanism that links ciliary dynamics and cell cycle regulation remains elusive. Here,... more

Summary Primary cilia, which emanate from the cell surface, exhibit assembly and disassembly dynamics along the progression of cell cycle. However, the mechanism that links ciliary dynamics and cell cycle regulation remains elusive. Here, we report that Polo-like kinase 1 (Plk1), one of the key cell cycle regulators, which regulate centrosome maturation, bipolar spindle assembly and cytokinesis, acts as a pivotal player that connects the ciliary dynamics and cell cycle regulation. We found that the kinase activity of ...

Many aspects of the mitotic cycle can take place independently in syncytial Drosophila embryos. Embryos from females homozygous for the mutation gnu undergo rounds of DNA synthesis without nuclear division to produce giant nuclei, and at... more

Many aspects of the mitotic cycle can take place independently in syncytial Drosophila embryos. Embryos from females homozygous for the mutation gnu undergo rounds of DNA synthesis without nuclear division to produce giant nuclei, and at the same time show many cycles of centrosome replication (Freeman et al. 1986). S phase can be inhibited in wild-type Drosophila embryos by injecting aphidicolin, in which case not only do centrosomes replicate, but chromosomes continue to condense and decondense, the nuclear envelope undergoes cycles of breakdown and reformation, and cycles of budding activity continue at the cortex of the embryo (Raff and Glover, 1988). If aphidicolin is injected when nuclei are in the interior of the embryo, centrosomes dissociate from the nuclei and can migrate to the cortex. Pole cells without nuclei then form around those centrosomes that reach the posterior pole (Raff and Glover, 1989); the centrosomes presumably must interact with polar granules, the materna...

Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic... more

Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic recombination. We report that mitotic recombination between homologous chromosomes occurred in human lymphoid cells exposed to densely ionizing radiation. We used cells derived from the same donor that express either normal TP53 (TK6 cells) or homozygous mutant TP53 (WTK1 cells) to assess the influence of TP53 on radiation-induced mutagenesis. Expression of mutant TP53 (Met 237 Ile) was associated with a small increase in mutation frequencies at the hemizygous HPRT (hypoxanthine phosphoribosyl transferase) locus, but the mutation spectra were unaffected at this locus. In contrast, WTK1 cells (mutant TP53) were 30-fold more susceptible than TK6 cells (wild-type TP53) to radiation-induced mutagenesis at the TK1 (thymidine kinase) locus. Gene dosage analysis c...

Libro de Biología Teórico-práctico diseñado especialmente para postulantes a la UNMSM. Contiene teoría sistematizada y contextualizada que se apoya en dibujos, esquemas, tablas, cuadros, esquemas, mapas conceptuales y fotografías que... more

Libro de Biología Teórico-práctico diseñado especialmente para postulantes a la UNMSM. Contiene teoría sistematizada y contextualizada que se apoya en dibujos, esquemas, tablas, cuadros, esquemas, mapas conceptuales y fotografías que consolidarán tu aprendizaje.

Mitosis is the most potentially dangerous event in the life of a cell, during which the cell genetic identity is transmitted to daughters; errors at this stage may yield aneuploid cells that can initiate a genetically unstable clone.... more

Mitosis is the most potentially dangerous
event in the life of a cell, during which the cell genetic
identity is transmitted to daughters; errors at this stage
may yield aneuploid cells that can initiate a genetically
unstable clone. The small GTPase Ran is the central
element of a conserved signaling network that has a
prominent role in mitotic regulation. Pioneering
studies with amphibian oocytes indicated that Ran,
in the GTP-bound form, activates factors that regulate
spindle assembly and dynamics.An increasing body of
data indicate higher specificity and complexity in
mitotic control operated by Ran in somatic cells.
Newly identified target factors of Ran operate with
different specificity, and it is emerging that mitotic
progression requires the precise positioning of Ran
network components and effectors at specific sites of
the mitotic apparatus according to a highly regulated
schedule in space and time. In this review we
summarize our current understanding of Ran control
of mitosis and highlight the specificity of mechanisms
operating in mammalian somatic cells.

Informe de mitosis visto en células diferenciadas de Allium cepa, Pontificia Universidad Javeriana

Informe de laboratorio de Biología sobre la Reproducción Celular: Mitosis

One of the most prospective directions of study of C.G. Jung’s synchronicity phenomenon is reviewed considering the latest achievements of modern science. The attention is focused mainly on the quantum entanglement and related phenomena –... more

One of the most prospective directions of study of C.G. Jung’s synchronicity phenomenon
is reviewed considering the latest achievements of modern science. The attention is
focused mainly on the quantum entanglement and related phenomena – quantum
coherence and quantum superposition. It is shown that the quantum non-locality capable
of solving the Einstein-Podolsky-Rosen paradox represents one of the most adequate
physical mechanisms in terms of conformity with the Jung’s synchronicity hypothesis. An
attempt is made on psychophysiological substantiation of synchronicity within the context
of molecular biology. An original concept is proposed, stating that biological molecules
involved in cell division during mitosis and meiosis, particularly DNA may be considered
material carriers of consciousness. This assumption may be formulated on the basis of
phenomenology of Jung’s analytical psychology

El origen de las brujas. Ya queda menos para el día de brujas o Halloween, la noche más espeluznante del año, y seguro que una de nuestras favoritas. ¿Ya sabes que también se le conoce por el nombre de noche de brujas? Esas criaturas... more

El origen de las brujas. Ya queda menos para el día de brujas o Halloween, la noche más espeluznante del año, y seguro que una de nuestras favoritas. ¿Ya sabes que también se le conoce por el nombre de noche de brujas? Esas criaturas sobrecogedoras que han amenazado al hombre desde el principio de los tiempos. Hoy se verá en este informe algo más sobre su historia y la naturaleza de sus poderes. Los primeros indicios de brujería aparecen ya en las civilizaciones clásicas, casi siempre practicada por mujeres. Se reunían de noche, tenían el poder de transformarse en animales voladores e incluso eran capaces de provocar enfermedades o tempestades. Las brujas más famosas de la Grecia Clásica fueron Medea y Circe, cuyas habilidades residían sobre todo en su dominio de las pócimas mágicas. Se las solía asociar a ciertos lugares, considerados portales de paso al mundo infernal, como pantanos o cementerios. Algunas aprovechaban su conexión con los muertos para predecir el futuro, como Erictho durante la antigua Roma. O la bruja de Endor, a la que según la biblia recurrió el rey Saúl para hablar con el difunto profeta Samuel. Se reunían en los aquelarres o Sabbats, fiestas celebradas a medianoche, donde bebían y bailaban en honor al dios cornudo de la fecundidad y la naturaleza. Para ello escogían lugares alejados de las poblaciones, donde practicaban rituales mágicos que les otorgaban más poder. Las juntanzas también servían para convertir a los nuevos adeptos, niños y niñas que eran secuestrados de sus propias casas y consagrados a este dios. Comenzaban sirviendo como discípulos de otras hechiceras, hasta llegar a convertirse ellos mismos en brujos. Otros pequeños corrían peor suerte y acababan sirviendo de alimento en banquetes caníbales o como en ingredientes para elaborar pociones y ungüentos mágicos. Para llegar a estos aquelarres apartados, las brujas se desplazaban a gran velocidad, viajando en una ráfaga de viento, montadas en una bestia o en una escoba mágica. Algunas incluso tenían el poder de teletransportarse. manuelverdugo.com