The genes encoding the major 42S storage particle proteins are expressed in male and female germ cells of Xenopus laevis

As components of the 42S storage particles (thesaurisomes), thesaurin a and thesaurin b are involved in the long-term storage of tRNA and 5S RNA in previtellogenic oocytes of Xenopus laevis. Thesaurin a and thesaurin b are among the most abundant proteins in previtellogenic oocytes. We show here that the mRNAs encoding thesaurin a and thesaurin b are present not only in previtellogenic oocytes but also in pre-meiotic germ cells (oogonia). These mRNAs can also be detected in spermatogonia and early spermatocytes, and are translated into protein in testis, as they are in ovary. We conclude that male germ cells mimic female germ cells in several aspects of gene activity related to RNA accumulation and metabolism.

Particulate Magnetic Media Contamination: Large Defects

Participate magnetic media is widely used throughout the computer industry for data storage. Particle contamination is a major source for head crashes in magnetic disk drives. Bit size, track width and flying heights are decreasing because of the demands for greater storage density. As a result, the interfacial phenomena between the head and the disk are becoming critical. Particles generated during the operation of a magnetic disk drive or introduced through the defects in the filtering system, can cause a Head/Disk Interference (HDI) and/or result in a total system failure due to a head crash.Interaction between the head and the particle becomes responsible for HDI or head crashes. The HDI occur either from the head impacting and shattering the particle as shown in Figure 1 or the particle is dragged across the disk surface by the head as shown in Figure 2. The particle, marked by the arrow, in Figure 2 has been pushed into the substrate.