Lea Yogev

Bio: Lea Yogev is an academic researcher from Technion – Israel Institute of Technology. The author has contributed to research in topics: Semen analysis & Sperm motility. The author has an hindex of 1, co-authored 1 publications receiving 66 citations.

Mammalian sperm translate nuclear-encoded proteins by mitochondrial-type ribosomes

Abstract: It is widely accepted that spermatozoa are translationally silent. The present study demonstrates, for the first time, incorporation of labeled amino acids into polypeptides during sperm capacitation, which was completely inhibited by mitochondrial translation inhibitors but not by the cytoplasmic translation inhibitor. Unlike 80S cytoplasmic ribosomes, 55S mitochondrial ribosomes were present in polysomal fractions, indicating that these ribosomes are actively involved in protein translation in spermatozoa. Inhibition of protein translation significantly reduced sperm motility, capacitation and in vitro fertilization rate. Thus, contrary to the accepted dogma, nuclear genes are expressed as proteins in sperm during their residence in the female reproductive tract until fertilization.

Hybrid breakdown caused by substitution of the X chromosome between two mouse subspecies.

Abstract: Hybrid breakdown is a type of reproductive failure that appears after the F2 generation of crosses between different species or subspecies. It is caused by incompatibility between interacting genes. Genetic analysis of hybrid breakdown, particularly in higher animals, has been hampered by its complex nature (i.e., it involves more than two genes, and the phenotype is recessive). We studied hybrid breakdown using a new consomic strain, C57BL/6J-X(MSM), in which the X chromosome of C57BL/6J (derived mostly from Mus musculus domesticus) is substituted by the X chromosome of the MSM/Ms strain (M. m. molossinus). Males of this consomic strain are sterile, whereas F1 hybrids between C57BL/6J and MSM/Ms are completely fertile. The C57BL/6J-X(MSM) males showed reduced testis weight with variable defects in spermatogenesis and abnormal sperm head morphology. We conducted quantitative trait locus (QTL) analysis for these traits to map the X-linked genetic factors responsible for the sterility. This analysis successfully detected at least three distinct loci for the sperm head morphology and one for the testis weight. This study revealed that incompatibility of interactions of X-linked gene(s) with autosomal and/or Y-linked gene(s) causes the hybrid breakdown between the genetically distant C57BL/6J and MSM/Ms strains.

In Vivo and In Vitro Impairment of Human and Ram Sperm Nuclear Chromatin Integrity by Sexually Transmitted Ureaplasma urealyticum Infection

Abstract: The incidence of Ureaplasma urealyticum infection in the semen of infertile men is variable (7%–42%). Evidence has accumulated through routine semen analysis to suggest that this infection can cause embryo loss without necessarily affecting sperm quality. The aim of this study was to specifically investigate the effects of U. urealyticum infection on sperm chromatin stability and DNA integrity, which are known to be correlated to pregnancy outcome. Sperm cells isolated from human semen infected in vivo with U. urealyticum exhibited a low percentage of stable chromatin as determined by nuclear chromatin decondensation assay (42% ± 4.8%, n = 8) and a high percent of denatured DNA as determined by sperm chromatin structure assay (60.9% ± 9.1%, n = 7). After doxycyclin treatment, a significant improvement in both parameters was observed (73.7% ± 3.6%, P < 0.001 and 30.1% ± 3.5%, P < 0.008, respectively). Sperm cells infected in vitro exhibited higher rates of viability and motility than uninfected ce...