Phospholipid hydroperoxide glutathione peroxidase (GPx4) is an intracellular antioxidant enzyme that directly reduces peroxidized phospholipids. GPx4 is strongly expressed in the mitochondria of testis and spermatozoa. We previously found a significant decrease in the expression of GPx4 in spermatozoa from 30% of infertile human males diagnosed with oligoasthenozoospermia (Imai, H., Suzuki, K., Ishizaka, K., Ichinose, S., Oshima, H., Okayasu, I., Emoto, K., Umeda, M., and Nakagawa, Y. (2001) Biol. Reprod. 64, 674 -683). To clarify whether defective GPx4 in spermatocytes causes male infertility, we established spermatocyte-specific GPx4 knock-out mice using a CreloxP system. All the spermatocyte-specific GPx4 knock-out male mice were found to be infertile despite normal plug formation after mating and displayed a significant decrease in the number of spermatozoa. Isolated epididymal GPx4-null spermatozoa could not fertilize oocytes in vitro. These spermatozoa showed significant reductions of forward motility and the mitochondrial membrane potential. These impairments were accompanied by the structural abnormality, such as a hairpin-like flagella bend at the midpiece and swelling of mitochondria in the spermatozoa. These results demonstrate that the depletion of GPx4 in spermatocytes causes severe abnormalities in spermatozoa. This may be one of the causes of male infertility in mice and humans.A frequent cause of male infertility is defective sperm function, which is the main problem for close to a quarter of couples who attend infertility clinics (1-4). Considerable efforts are now focused on the identifying ultrastructural and/or molecular defects in the spermatozoa or seminal plasma to develop solutions to various types of male infertility.Phospholipid hydroperoxide glutathione peroxidase (GPx4) 2 is an intracellular selenoprotein that directly reduces peroxidized phospholipids produced in cell membranes (5). The GPx4 gene has a complex intron/exon structure (6, 7). Three different transcripts of GPx4 exist, differing in their 5Ј extension and coding for a cytosolic protein (non-mitochondrial GPx4), a mitochondrial protein (mitochondrial GPx4), and a nuclear protein (nucleolar GPx4), respectively (6, 7). After cleavage of the N-terminal mitochondrial import sequence of mitochondrial GPx4, the mature protein becomes identical to the 20-kDa non-mitochondrial GPx4 (8, 9). Nuclear GPx4 was recently identified as a sperm nucleus-specific 34-kDa selenoprotein (called snGPx, for sperm nucleus-specific glutathione peroxidase) (10). It is formed by use of an alternative promoter and start codon localized in the first intron of the GPx4 gene (7, 10, 11). We previously reported that 34-kDa GPx4 localized in nucleoli in several cell lines by using an N-terminal nucleolar import signal (11). We call hereafter nuclear GPx4 nucleolar GPx4, because non-mitochondrial 20-kDa GPx4 exists both in cytosol and in the nucleus (12). Expression of three types of GPx4 is induced significantly in testis during spermatogenesis, especiall...

In LSI production, various factors contribute to critical dimension (CD) errors. Factors that gradually affect CD over a several mm–cm area are referred to as global CD errors. In this paper, a method of correcting global CD errors (GCD correction) that appear in processes following an electron-beam mask-writing process is discussed. Examples of GCD errors are the loading effects in wafer and mask processes, and the flare in lithography processes. In this paper, we propose a new method of calculating the optimum dimension to correct GCD errors. The correction method is based on a pattern modulation method; i.e., modification of the sizes of figures in an LSI pattern depending on their position. A feature of our method is the use of two newly introduced factors, a “figure edge contribution” and a “corner adjustment term”, in addition to conventional pattern density. As an example, the correction accuracy of our method is evaluated for mask fabrication by numerical calculation. It is shown that our method can suppress the GCD correction error to less than 0.01 nm when the maximum GCD error depending on the pattern density is 20 nm. Our method will provide the CD accuracy required in the future. The relation between global CD correction and proximity effect correction is also discussed in the case that an electron-beam writing system is used to control figure sizes.

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The proliferation and differentiation of human mast cells (MCs) occur under the influence of the mitogenic agent known as stem cell factor (SCF). This study analyses the distribution of SCF and SCF receptor in human myometrial tissue to further the understanding of the role(s) of MCs in the uterus. Immunohistochemical staining revealed that the majority of uterine MCs are located in close proximity to myometrial smooth muscle cells, and also among fibroblast-like spindle shaped cells. RNA extracts from myometrial tissues were subjected to reverse transcription. The resulting cDNA population was amplified by polymerase chain reaction (PCR) using a pair of 20-mer primers that were specific for SCF cDNA. Electrophoresis of the PCR products showed that the myometrial tissues contained transcripts for SCF. In-situ reverse transcription-PCR also revealed the expression of the transcripts for SCF in myometrial smooth muscle cells. Furthermore, enzyme-linked immunosorbent assays confirmed that the cultured myometrial cells produced SCF. Since immunohistochemical staining indicated there are SCF receptors on the surface of myometrial MCs, the results suggest that MC proliferation and differentiation in the myometrium is regulated by SCF secretion from the uterine smooth muscle cells. The mature MCs might, in turn, secrete mediators that influence tissue remodelling during the human menstrual cycle.

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