Distribution of the molossinus allele of Sry, the testis-determining gene, in wild mice

When the Y chromosome of the laboratory inbred mouse strain C57BL/6 (B6) is replaced by the Y of certain strains of Mus musculus domesticus, testis determination fails and all XY fetuses develop either as hermaphrodites or XY females (XY sex reversal). This suggests the presence of at least two alleles of Sry, the male-determining gene on the Y:M. m. domesticus and B6. The B6 Y chromosome is derived from the Japanese house mouse, M. m. molossinus and therefore carries a molossinus Sry allele. As a first step to determine how the molossinus Sry allele evolved, its distribution pattern was determined in wild mice. The cumulative data of 96 M. musculus samples obtained from 58 geographical locations in Europe, North Africa, and Asia show the molossinus Sry allele is restricted to Japan and the neighboring Asian mainland and confirm that Japanese M. m. molossinus mice were derived in part from a race of M. m. musculus from Korea or Manchuria. Sry polymorphisms, as illustrated by the molossinus Sry allele, can serve as molecular markers for studies on the evolution of wild M. musculus populations and can help determine the role sex determination plays in speciation.      

Immunologic properties of purified and complex preparations of group-B meningococcal polysaccharide

The complex preparations of group B meningococcal polysaccharide have been found to be capable of inducing primary immune response in mice, while purified group B polysaccharide has proved to be immunologically inert. As revealed in this investigation, the intravenous injection to mice of the optimum doses of the complex preparation of group B polysaccharide leads to the increased number of specific B-antibody-forming cells in their spleens and to a rise in B-antibody titers in their sera; besides, the time course of the process has been studied. Both preparations have been found capable of forming the immunological memory in mice if booster immunization is made with the complex preparation of group B polysaccharide. The immunological inertness of purified group B polysaccharide is attributed, supposedly, to the action of some specific suppressor mechanism. Considering the pronounced antigenic activity of the complex preparation of group B polysaccharide and the insignificant admixture of endotoxin in this preparation, the suitability of its future use as vaccine for the prophylaxis of meningitis caused by group B meningococcus is indicated and the tentative immunization schedules are discussed.     

Protective properties of recombinant IgA1 protease from meningococcus

The study of enzymatic and protective properties of recombinant IgA1 protease in active and mutant form has shown that the active form of IgA1 protease exhibited species- and type-specificity for mouse and human immunoglobulins. A mutant form, lacking enzymatic activity, had protective properties against meningococcal infection, induced by meningococcus serogroup A, B and C; it protected mice from lethal infection by live virulent cultures of heterologous serogroups of meningococcus. The results obtained in this study suggest that IgA1 protease may be considered as a perspective preparation at the stages of development of a polyvalent vaccine for protection of human against meningococcal infections of various etiology.     

Genome-wide analysis of lysine catabolism in bacteria reveals new connections with osmotic stress resistance

Lysine is catabolized via the saccharopine pathway in plants and mammals. In this pathway, lysine is converted to α-aminoadipic-δ-semialdehyde (AASA) by lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH); thereafter, AASA is converted to aminoadipic acid (AAA) by α-aminoadipic-δ-semialdehyde dehydrogenase (AASADH). Here, we investigate the occurrence, genomic organization and functional role of lysine catabolic pathways among prokaryotes. Surprisingly, only 27 species of the 1478 analyzed contain the lkr and sdh genes, whereas 323 species contain aasadh orthologs. A sdh-related gene, identified in 159 organisms, was frequently found contiguously to an aasadh gene. This gene, annotated as lysine dehydrogenase (lysdh), encodes LYSDH an enzyme that directly converts lysine to AASA. Pipecolate oxidase (PIPOX) and lysine-6-aminotransferase (LAT), that converts lysine to AASA, were also found associated with aasadh. Interestingly, many lysdh–aasadh–containing organisms live under hyperosmotic stress. To test the role of the lysine-to-AASA pathways in the bacterial stress response, we subjected Silicibacter pomeroyi to salt stress. All but lkr, sdh, lysdh and aasadh were upregulated under salt stress conditions. In addition, lysine-supplemented culture medium increased the growth rate of S. pomeroyi under high-salt conditions and induced high-level expression of the lysdh–aasadh operon. Finally, transformation of Escherichia coli with the S. pomeroyi lysdh–aasadh operon resulted in increased salt tolerance. The transformed E. coli accumulated high levels of the compatible solute pipecolate, which may account for the salt resistance. These findings suggest that the lysine-to-AASA pathways identified in this work may have a broad evolutionary importance in osmotic stress resistance.     

Phylogenetic analysis of slippage-like sequence variation in the V4 rRNA expansion segment in tiger beetles (Cicindelidae)

Sequence variation in the middle part of the small-subunit rRNA was studied for representatives of the major groups in the family Cicindelidae (Coleoptera). All taxa exhibited a much expanded segment in variable region V4 compared to D. melanogaster. This expanded segment was not found in other groups of beetles, including three taxa in the closely related Carabidae. Secondary structure predictions indicate that the expanded segment folds into a single stem-loop structure in all taxa. Despite its structural conservation, the fragment differs strongly in primary sequence, even between closely related sister taxa. Several features of these sequences are consistent with slippage replication as the mechanism that has generated this sequence variation: the level of internal sequence repetition as measured by the relative simplicity factor (RSF), its variation in length between close relatives, and the strong nucleotide bias compared to the remainder of the gene. With few exceptions, there was also a correlation between sequence length and the level of sequence repetition, frequently interpreted as the result of slippage. Phylogenies inferred from the expansion segment were not consistent with existing hypotheses from other molecular data for the group. This indicates that DNA sequences in this region are not homologous throughout the entire Cicindelidae, but it leaves open the possibility that this expansion segment can be used for phylogeny reconstruction within subgroups. The implications of a phylogenetic approach to the understanding of slippage-like evolution are discussed.      

Immunogenic and Protective Properties of <Emphasis Type="Italic">Neisseria meningitidis</Emphasis> IgA1 Protease and of Its Truncated Fragments

Four recombinant proteins, MA²⁸–P¹⁰⁰⁴LEH₆, ME¹³⁵–H³²⁸LEH₆, MW³²⁹–H⁶²²LEH₆ and MH⁸³⁵–P¹⁰⁰⁴LEH₆, were prepared based on the genomic sequence of IgA1 protease from Neisseria meningitidis serogroup B strain H44/76. The immunogenic and protective properties of these proteins were studied in a mouse model. The predicted T- and B-epitopes located in the N-terminal part of amino acid sequence of this enzyme are very important for the formation of effective protection against meningococci of the three main epidemic serogroups A, B, and C. The small-sized recombinant protein having the sequence ME¹³⁵–H³²⁸LEH₆ (molecular weight 23367 Da) appears to be as protective against meningococci of the tested serogroups as the high molecular MA²⁸–P¹⁰⁰⁴LEH₆ (molecular weight 109019 Da), the latter being a large-sized analog of full-length IgA1 protease. These proteins can be promising candidates for a polyvalent meningococcal vaccine.     

Phosphorylation regulates the Star-PAP-PIPKIα interaction and directs specificity toward mRNA targets

Star-PAP is a nuclear non-canonical poly(A) polymerase (PAP) that shows specificity toward mRNA targets. Star-PAP activity is stimulated by lipid messenger phosphatidyl inositol 4,5 bisphoshate (PI4,5P₂) and is regulated by the associated Type I phosphatidylinositol-4-phosphate 5-kinase that synthesizes PI4,5P₂ as well as protein kinases. These associated kinases act as coactivators of Star-PAP that regulates its activity and specificity toward mRNAs, yet the mechanism of control of these interactions are not defined. We identified a phosphorylated residue (serine 6, S6) on Star-PAP in the zinc finger region, the domain required for PIPKIα interaction. We show that S6 is phosphorylated by CKIα within the nucleus which is required for Star-PAP nuclear retention and interaction with PIPKIα. Unlike the CKIα mediated phosphorylation at the catalytic domain, Star-PAP S6 phosphorylation is insensitive to oxidative stress suggesting a signal mediated regulation of CKIα activity. S6 phosphorylation together with coactivator PIPKIα controlled select subset of Star-PAP target messages by regulating Star-PAP-mRNA association. Our results establish a novel role for phosphorylation in determining Star-PAP target mRNA specificity and regulation of 3′-end processing.