Rps4 maps near the inactivation center on the mouse X chromosome

Cloning and characterization of 40S ribosomal protein S4 gene from Culex pipiens pallens

The 40S ribosomal protein S4 gene (RPS4) has been cloned from Culex pipiens pallens. An open reading frame (ORF) of 789 bp was found to encode a putative 262 amino acid protein. The deduced amino acid sequence shares 96% and 91% identity with RPS4 genes from Aedes and Anopheles respectively. Transcript expression of RPS4 was determined by real-time PCR in all life stages of deltamethrin-susceptible and -resistant strains. The results demonstrated that this gene is expressed at all developmental stages. Meanwhile, in pupae and adults, RPS4 is overexpressed in deltamethrin-resistant strain than in -susceptible strain. Our data for the first time suggests that increased expression of the RPS4 gene may play some role in the development of deltamethrin resistance in C. pipiens pallens.

Identification and genetic mapping of 151 dispersed members of 16 ribosomal protein multigene families in the mouse

More than 150 individual members of 16 ribosomal protein multigene families were identified as DNA restriction fragments and genetically mapped. The ribosomal protein gene-related sequences are widely dispersed throughout the mouse genome. Map positions were determined by analysis of 144 progeny mice from both an interspecific (C57BL/6J x SPRET/Ei)F1 x SPRET/Ei and an intersubspecific (C57BL/6J x CAST/Ei)F1 x C57BL/6J backcross. In addition, 30 members of the multigene families encoding PGK1 ODC, and TPI, including five new loci for ODC and one new locus for TPI, were characterized and mapped. Interspecific backcross linkage data for 29 nonecotropic murine leukemia retroviruses endogenous to C57BL/6J mice are also reported. Transmission ratio distortions and recombination frequencies are compared between the two backcrosses.

Primary structure and expression of a gene encoding the cytosolic ribosomal protein S4 from potato

The primary structure of a cDNA clone encoding the S4 protein from the small subunit of 80S ribosomes from potato was determined. Cytosolic ribosomal protein S4 is hydrophilic and has a prevalence for positively charged residues. In potato it is 264 amino acids long and contains a putative nuclear targeting signal close to the N-terminus. Having 65-69% identical amino acids cytosolic ribosomal protein S4 from mammals, fungi and plants belongs to the highly conserved proteins. The S4 gene is transcribed in all potato tissues analysed and has a relatively high expression level in comparison to nuclear genes encoding mitochondrial proteins.

Structure and function of ribosomal protein S4 genes on the human and mouse sex chromosomes

The human sex-linked genes RPS4X and RPS4Y encode distinct isoforms of ribosomal protein S4. Insufficient expression of S4 may play a role in the development of Turner syndrome, the complex human phenotype associated with monosomy X. In mice, the S4 protein is encoded by an X-linked gene, Rps4, and is identical to human S4X; there is no mouse Y homolog. We report here the organization of the human RPS4X and RPS4Y and mouse Rps4 genes. Each gene comprises seven exons; the positions of introns are conserved. The 5' flanking sequences of human RPS4X and mouse Rps4 are very similar, while RPS4Y diverges shortly upstream of the transcription start site. In chickens, S4 is encoded by a single gene that is not sex linked. The chicken protein differs from human S4X by four amino acid substitutions, all within a region encoded by a single exon. Three of the four substitutions are also present in human S4Y, suggesting that the chicken S4 gene may have arisen by recombination between S4X- and S4Y-like sequences. Using isoform-specific antisera, we determined that human S4X and S4Y are both present in translationally active ribosomes. S4Y is about 10 to 15% as abundant as S4X in ribosomes from normal male placental tissue and 46,XY cultured cells. In 49,XYYYY cells, S4Y is about half as abundant as S4X. In 49,XXXXY cells, S4Y is barely detectable. These results bear on the hypothesized role of S4 deficiency in Turner syndrome.

Structure and function of ribosomal protein S4 genes on the human and mouse sex chromosomes

The human sex-linked genes RPS4X and RPS4Y encode distinct isoforms of ribosomal protein S4. Insufficient expression of S4 may play a role in the development of Turner syndrome, the complex human phenotype associated with monosomy X. In mice, the S4 protein is encoded by an X-linked gene, Rps4, and is identical to human S4X; there is no mouse Y homolog. We report here the organization of the human RPS4X and RPS4Y and mouse Rps4 genes. Each gene comprises seven exons; the positions of introns are conserved. The 5' flanking sequences of human RPS4X and mouse Rps4 are very similar, while RPS4Y diverges shortly upstream of the transcription start site. In chickens, S4 is encoded by a single gene that is not sex linked. The chicken protein differs from human S4X by four amino acid substitutions, all within a region encoded by a single exon. Three of the four substitutions are also present in human S4Y, suggesting that the chicken S4 gene may have arisen by recombination between S4X- and S4Y-like sequences. Using isoform-specific antisera, we determined that human S4X and S4Y are both present in translationally active ribosomes. S4Y is about 10 to 15% as abundant as S4X in ribosomes from normal male placental tissue and 46,XY cultured cells. In 49,XYYYY cells, S4Y is about half as abundant as S4X. In 49,XXXXY cells, S4Y is barely detectable. These results bear on the hypothesized role of S4 deficiency in Turner syndrome.

An SRY-related sequence on the marsupial X chromosome: implications for the evolution of the mammalian testis-determining gene

The SRY gene on the human, mouse, and marsupial Y chromosomes is the testis-determining gene that initiates male development in mammals. The SRY protein has a DNA-binding domain (high mobility group or HMG box) similar to those found in the high-mobility-group proteins. SRY is specific for the Y chromosome, but many autosomal genes have been identified that possess a similar HMG box region; those with the most closely SRY-related box regions form a gene family now referred to as SOX genes. We have identified a sequence on the marsupial X chromosome that shares homology with SRY. Sequence comparisons show near-identity with the mouse and human SOX3 gene (formerly called a3), the SOX gene which is the most closely related to SRY. We suggest here that the highly conserved X chromosome-linked SOX3 represents the ancestral SOX gene from which the sex-determining gene SRY was derived. In this model SOX3/SRY divergence and the acquisition of a testis-determining role by SRY might have preceded (and initiated) sex chromosome differentiation or, alternatively, might have been a consequence of X chromosome-Y chromosome differentiation initiated at the locus of an original sex-determining gene(s), later superseded by SRY.

Functional equivalence of human X- and Y-encoded isoforms of ribosomal protein S4 consistent with a role in Turner syndrome

Several genes are found on both the human X and Y chromosomes in regions that do not recombine during male meiosis. In each case, nucleotide sequence analysis suggests that these X-Y gene pairs encode similar but nonidentical proteins. Here we show that the human Y- and X-encoded ribosomal proteins, RPS4Y and RPS4X, are interchangeable and provide an essential function: either protein rescued a mutant hamster cell line that was otherwise incapable of growth at modestly elevated temperatures. These findings are consistent with the hypothesis that RPS4 deficiency has a role in Turner syndrome, a complex human phenotype associated with monosomy X.

An evaluation of the inactive mouse X chromosome in somatic cell hybrids

The expression of mouse Zfx, Rps4, Ube1x, and Xist was evaluated in hamster-mouse somatic cell hybrids containing either an active or an inactive mouse X chromosome using polymerase chain reaction of reverse transcribed RNA (RT-PCR). The results showed that Zfx, Rps4, and Ube1x are expressed exclusively from the active mouse X, while Xist is expressed exclusively from the inactive X. These findings confirm the pattern of X inactivation for these mouse genes reported previously based on expression in somatic tissues of F1 females from interspecific crosses. These results demonstrate the existence of differences between human and mouse X inactivation, as the corresponding human genes, ZFX, RPS4X, and UBE1 escape X inactivation.

Marsupial Y chromosome encodes a homologue of the mouse Y-linked candidate spermatogenesis gene Ube1y

The mammalian subclass Theria consists of infraclasses Metatheria (marsupials) and Eutheria ('placentals') which diverged from each other 120-150 million years before present (Myr BP). Both infraclasses have Y chromosome-dependent testis determination but direct molecular evidence linking the Metatherian and Eutherian Y chromosomes is lacking. Comparative analyses indicate that three mammalian genes have remained Y-linked for at least 80 Myr, since the divergence of the Eutherian orders from a common ancestor. These are Zfy, a gene encoding a transcription factor of the zinc-finger type; Sry, the putative primary testis-determining gene; and Ube1y (formerly Sby or A1s9Y-1), a candidate for the mouse spermatogenesis gene Spy, encoding a ubiquitin-activating enzyme E1 homologue. Although in marspials Zfy homologues are autosomal, a Y homologue of Sry has recently been isolated. We report here the identification of a functional marsupial Y-linked homologue of the murine Ube1y gene establishing that Metatherian and Eutherian Y chromosomes diverged from a common ancestor. This extreme conservation indicates that Ube1y plays a critical role in male development.

Construction of a mouse yeast artificial chromosome library in a recombination-deficient strain of yeast

We have constructed a new generation yeast artificial chromosome (YAC) library from female C57BL/10 mice in a recombination-deficient strain of Saccharomyces cerevisiae carrying a mutation in the RAD52 gene. The YAC library contains 41,568 clones with an average insert size of 240 kilobases, representing a greater than threefold coverage of the mouse genome. Currently, the library can be screened by polymerase chain reaction and we have isolated positive clones at a number of loci in the mouse genome. This rad52 library should enable a long-term assessment of the effect of one of the yeast recombination pathway genes on both, genome-wide YAC clone stability and the frequency of chimaeric clones.