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[
Methods Cell Biol,
1995]
Complementary DNA libraries are useful tools for uncovering genes of interest in C. elegans and finding specific homologies to genes in other organisms (Waterston et al., 1992; McCombie et al., 1992). When working with existing cDNA libraries, be sure to carefully choose which libraries would be most beneficial to the type of research being done. Some libraries may be specific for genes that are present in lower copy numbers, whereas others may be of a more general nature. It is important to fully understand the source and construction of the library you will be working with. Once an appropriate library has been chosen, work may begin to isolate a specific cDNA and sequence it completely or to survey many cDNAs by single-pass DNA sequencing. Whatever the project, it is important to develop a specific strategy for both the sequencing and the organization of the clones being characterized. The strategies and procedures we have outlined in this chapter have proven effective for rapid and comprehensive cDNA characterization.
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[
Oncogene,
2002]
As the primary microtubule-organizing center (MTOC) of the cell, the centrosome is a major structural determinant of the mitotic spindle. Like each chromosome, the centrosome must replicate once and only once per cell cycle in order to maintain the fidelity of nuclear division and the integrity of the genome. While the mechanisms that govern this process are not well understood and are sure to be complex, centrosome duplication can be described as involving three general steps. First, the centrosome splits to form two centrosomes, each with half the reproductive capacity of the original. Second, a replication step restores each new centrosome to full reproductive capacity. Third, the replicated centrosomes sever any remaining connections and move apart. In the past few years, several factors have been identified that regulate each of these steps. Among these factors is the ZYG-1 kinase of C. elegans, which functions during both mitotic and meiotic divisions (O?Connell et al., 2001).
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[
Dev Biol,
2022]
The microtubule cytoskeleton is critical for maintenance of long and long-lived neurons. The overlapping array of microtubules extends from the major site of synthesis in the cell body to the far reaches of axons and dendrites. New materials are transported from the cell body along these neuronal roads by motor proteins, and building blocks and information about the state of affairs in other parts of the cell are returned by motors moving in the opposite direction. As motor proteins walk only in one direction along microtubules, the combination of correct motor and correctly oriented microtubules is essential for moving cargoes in the right direction. In this review, we focus on how microtubule polarity is established and maintained in neurons. At first thought, it seems that figuring out how microtubules are organized in neurons should be simple. After all, microtubules are essentially sticks with a slow-growing minus end and faster-growing plus end, and arranging sticks within the constrained narrow tubes of axons and dendrites should be straightforward. It is therefore quite surprising how many mechanisms contribute to making sure they are arranged in the correct polarity. Some of these mechanisms operate to generate plus-end-out polarity of axons, and others control mixed or minus-end-out dendrites.
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[
Adv Protein Chem,
2001]
Biochemical characterization of the yeast prions has revealed many similarities with the mammalian amyloidogenic proteins. The ease of generating in vivo mutations in yeast and the developing in vitro models for [PSI+] and [URE3] circumvent many of the difficulties of studying the proteins linked to the mammalian amyloidoses. Future work especially aimed at understanding the molecular role of chaperone proteins in regulating conversion as well as the early steps in de novo formation of the prion state in yeast will likely provide invaluable lessons that may be more broadly applicable to related processes in higher eukaryotes. It is important to remember, however, that there are clear distinctions between disease states associated with amyloidogenesis and the epigenetic modulation of protein function by self-perpetuating conformational conversions. Amyloid formation is detrimental to mammals and is likely selected against, providing a possible explanation for the late onset of these disorders (Lansbury, 1999). In contrast, the known yeast prions are compatible with normal growth and, if beneficial to the organism, may be subject to evolutionary pressures that ultimately maximize transmission. In the prion proteins examined to date, distinct domains are responsible for normal function and for the conformational switches producing a prion conversion of that function. Recent work has demonstrated that the prion domains are both modular and transferable to other proteins on which they can confer a heritable epigenetic alteration of function (Edskes et al., 1999; Li and Lindquist, 2000; Patino et al., 1996; Santoso et al., 2000; Sondheimer and Lindquist, 2000). That is, prion domains need not coevolve with particular functional domains but might be moved from one protein to another during evolution. Such processes may be widely used in biology. Mechanistic studies of [PSI+] and [URE3] replication are sure to lay a foundation of knowledge for understanding a host of nonconventional genetic elements that currently remain elusive.