The Cell In Development And Heredity
About: This article is published in Transactions of the American Microscopical Society.The article was published on 1925-01-01 and is currently open access. It has received 1502 citations till now. The article focuses on the topics: Heredity.
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TL;DR: At the present time, with the immense increase in research activity in mammalian cytology, the terminology of the centromeric position has become burdened by much obscurity and confusion.
Abstract: N the inorphologic identification of chromosomes, the location of the I centromere is the most useful landmark, and one which is characterized by great constancy. It would seem that not much could be added to the definitions by E. B. WILSON (1928) of the locations on the chromosome of the centrornere or, in the terminology of that time, the spindle attachment: “Attachment of the chromosome to the spindle is commonly limited to a small area, and is of two general types, namely: (1) terminnl or telomitic and (2) non-ferminal or atelomitic, being in the former case at one end, and in the latter at some other point or points. Non-terminal attachment may be at the middle point (median) or at an intermediate point (submedian, sub-terminal). All gradations exist between these various cases;” (I.c., p. 130-131). In the acconipanying picture (l.c., Fig. 56, p. 132), here reprinted as Fig. l., the four locations of median, submedian, subterminal and terminal are represented, and, in addition, “lateral”, which corresponds to the modern term “diffuse centromere”. Nevertheless, at the present time, with the immense increase in research activity in mammalian cytology, the terminology of the centromeric position has become burdened by much obscurity and confusion. One cause of confusion is that different authors, and even the same author on different occasions, have used the terms median, submedian etc. with great amplitude, and it is often difficult to know in a specific case what each term signifies. Another cause of confusion is that a set of terms for chromosomes with specific centromeric positions, such as metacentric, acrocentric, telocentric, have come into wide usage without being clearly defined in relation to the positional terms median, submedian, subterminal and terminal. During the spring of 1963 the present writers exchanged epistolary
5,352 citations
TL;DR: The first crystallographic analysis of a non-γ-tubulin γTuRC component has resulted in a new appreciation of the relationships among all γ TuRC proteins, leading to a refined model of their organization and function.
Abstract: Microtubule nucleation is regulated by the γ-tubulin ring complex (γTuRC) and related γ-tubulin complexes, providing spatial and temporal control over the initiation of microtubule growth. Recent structural work has shed light on the mechanism of γTuRC-based microtubule nucleation, confirming the long-standing hypothesis that the γTuRC functions as a microtubule template. The first crystallographic analysis of a non-γ-tubulin γTuRC component (γ-tubulin complex protein 4 (GCP4)) has resulted in a new appreciation of the relationships among all γTuRC proteins, leading to a refined model of their organization and function. The structures have also suggested an unexpected mechanism for regulating γTuRC activity via conformational modulation of the complex component GCP3. New experiments on γTuRC localization extend these insights, suggesting a direct link between its attachment at specific cellular sites and its activation.
3,494 citations
TL;DR: This review describes progress toward understanding the mechanism of dynamic instability of pure tubulin and discusses the function and regulation of microtubule dynamic instability in living cells.
Abstract: The polymerization dynamics of microtubules are central to their biological functions. Polymerization dynamics allow microtubules to adopt spatial arrangements that can change rapidly in response to cellular needs and, in some cases, to perform mechanical work. Microtubules utilize the energy of GTP hydrolysis to fuel a unique polymerization mechanism termed dynamic instability. In this review, we first describe progress toward understanding the mechanism of dynamic instability of pure tubulin and then discuss the function and regulation of microtubule dynamic instability in living cells.
2,484 citations
TL;DR: During the course of the evolution of mitosis, photosynthetic plastids were symbiotically acquired by some of these protozoans to form the eukaryotic algae and the green plants.
1,409 citations
TL;DR: The purpose of this review is to describe the current understanding of how the four maternal signals establish positional information in the Drosophila embryo, and to discuss the molecular properties of each system.
1,315 citations