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The FokI family of short interspersed repetitive elements (SINEs) has been found only in the genomes of charr fishes (genus Salvelinus). In an analysis of the insertion of FokI SINEs using PCR, we characterized six loci at which FokI SINEs have been inserted into the genomes of Salvelinus alpinus (Arctic charr) and/or S. malma (Dolly Varden). An analysis of one locus (Fok-223) suggested that a sister relationship exists between S. alpinus and S. malma and the SINE at this locus might have been inserted in a common ancestor of these two species, being fixed in all extant populations examined. By contrast, SINEs at two other loci (Fok-211 and Fok-206) were present specifically in the genome of S. alpinus, with polymorphism among populations of this species. Moreover, the presence or absence of the SINEs of the other three loci (Fok-214, Fok-217, and Fok-600) varied among populations of these two species. The most plausible interpretation of this result is that SINEs, which were ancestrally polymorphic in the genome of a common ancestor of these two species, are involved in an ongoing process of differential sorting and subsequent fixation in the various populations of each species.

The genomes of chum salmon and pink salmon contain a family of short interspersed repetitive elements (SINEs), designated the salmon SmaI family. It is restricted to these two species, a distribution that suggests that this SINE family might have been generated in their common ancestor. When insertions of the SmaI SINEs at 10 orthologous loci of these species were analyzed, however, it was found that there were no shared insertion sites between chum and pink salmon. Furthermore, at six loci where SmaI SINEs have been species-specifically inserted in chum salmon, insertions of SINEs were polymorphic among populations of chum salmon. By contrast, at four loci where SmaI SINEs had been species-specifically inserted in pink salmon, the SINEs were fixed among all populations of pink salmon. The interspecific and intraspecific variation of the SmaI SINEs cannot be explained by the assumption that the Sinai family was amplified in a common ancestor of these two species. To interpret these observations, we propose several possible models, including introgression and the horizontal transfer of SINEs from pink salmon to chum salmon during evolution.

Salmonid species contain numerous short interspersed repetitive elements (SINEs), known collectively as the HpaI family, in their genomes. Amplification and successive integration of individual SINEs into the genomes have occurred during the evolution of salmonids. We reported previously a strategy for determining the phylogenetic relationships among the Pacific salmonids in which these SINEs were used as temporal landmarks of evolution. Here, we provide evidence for extensive genomic rearrangements that involved retropositions and deletions in a common ancestor of all the Pacific salmon and trout. Our results provide genetic support for the recent phylogenetic reassignment of steelhead and related species from the genus Salmo to the genus Oncorhynchus. Several other informative loci identified by insertions of HpaI SINEs have been isolated, and previously proposed branching orders of the Oncorhynchus species have been confirmed. The authenticity of our phylogenetic tree is supported both by the isolation of more than two informative loci per branching point and by the congruence of all our data, which suggest that the period between successive speciations was sufficiently long for each SINE that had been amplified in the original species to become fixed in all individuals of that species.

Asthenozoospermia is commonly observed in infertile men. However, very few causative gene mutations have been identified because an efficient detection method has not been established. We previously identified a patient with asthenozoospermia carrying a heterozygous point deletion in GALNTL5 by detecting an abnormal reduction in the abundance of GALNTL5 and other marker proteins. To identify other mutations in GALNTL5, we screened sperm samples from 208 infertile men mainly diagnosed with asthenozoospermia using the same method, and conducted next-generation sequencing. Consequently, another case of GALNTL5 mutation was detected only in sperm at a low frequency but not in the somatic blood cells of a patient diagnosed with asthenozoospermia. In this patient, sperm motility improved and the mutation disappeared at 2 years after the first observation. In this man, carrying a heterozygotic deficiency of GALNTL5, the swim-up method was useful to concentrate the spermatozoa without mutation. Intracytoplasmic sperm injection of the selected motile spermatozoa into oocytes of the patient's partner resulted in successful conception, and a female child was safely delivered. These results suggest the feasibility of our approach for the screening and treatment of asthenozoospermia associated with GALNTL5 mutation. [ABSTRACT FROM AUTHOR]

XX gonads differentiate into ovaries, a morphologic event evident by embryonic day 13.5 (E13.5) in mice. To identify early markers of oogenesis, sex-specific urogenital ridge cDNA libraries were constructed from E12-13 embryos. After mass excision and isolation of plasmid DNA, approximately 4800 expressed sequence tags were determined and compared to existing databases. Few cDNAs were specifically expressed in the urogenital ridge, but one, designated GPBOX, encodes a 227-amino-acid homeobox protein that is first expressed at E10.5 in the embryo as well as in the extraembryonic tissues. The Gpbox gene is single copy in the mouse genome and is located on the X chromosome in close proximity to two other homeobox genes, Peru and Psx1. Within the embryo, its expression is limited to the gonad, and transcripts are not detected in adult tissues. Although comparable levels are initially present in both sexes, GPBOX transcripts accumulate faster in female germ cells and peak at E12.5 when they are present in fivefold greater abundance than in males. The persistence of GPBOX transcripts in female germ cells until E15.5 and their virtual disappearance in males by E13.5 suggest that Gpbox may play a role in mammalian oogenesis. [C] 2000 Academic Press Key Words: homeobox transcription factors; oogenesis; oocyte-specific gene expression; expressed sequence tags.

We have identified cis-regulatory sequences acting on Otx2 expression in epiblast (EP) and anterior neuroectoderm (AN) at about 90 kb 5′ upstream. The activity of the EP enhancer is found in the inner cell mass at E3.5 and the entire epiblast at E5.5. The AN enhancer activity is detected initially at E7.0 and ceases by E8.5; it is found later in the dorsomedial aspect of the telencephalon at E10.5. The EP enhancer includes multiple nrequired domains over 2.3 kb, and the AN enhancer is an essential component of the EP enhancer. Mutants lacking the AN enhancer have demonstrated that these cis-sequences indeed regulate Otx2 expression in EP and AN. At the same time, our analysis indicates that another EP and AN enhancer must exist outside of the -170 kb to +120 kb range. In Otx2ΔAN/- mutants, in which one Otx2 allele lacks the AN enhancer and the other allele is null, anteroposterior axis forms normally and anterior neuroectoderm is normally induced. Subsequently, however, forebrain and midbrain are lost, indicating that Otx2 expression under the AN enhancer functions to maintain anterior neuroectoderm once induced. Furthermore, Otx2 under the AN enhancer cooperates with Emx2 in diencephalon development. The AN enhancer region is conserved among mouse, human and Xenopus; moreover, the counterpart region in Xenopus exhibited an enhancer activity in mouse anterior neuroectoderm. [ABSTRACT FROM AUTHOR]