SummaryA single polypeptide subunit, Caf1, polymerizes to form a dense, poorly defined structure (F1 capsule) on the surface of Yersinia pestis. The caf-encoded assembly components belong to the chaperone± usher protein family involved in the assembly of composite adhesive pili, but the Caf1M chaperone itself belongs to a distinct subfamily. One unique feature of this subfamily is the possession of a long, variable sequence between the F1 b-strand and the G1 subunit binding b-strand (FGL; F1 b-strand to G1 b-strand long). Deletion and insertion mutations confirmed that the FGL sequence was not essential for folding of the protein but was absolutely essential for function. Site-specific mutagenesis of individual residues identified Val-126, in particular, together with Val-128 as critical residues for the formation of a stable subunit±chaperone complex and the promotion of surface assembly. Differential effects on periplasmic polymerization of the subunit were also observed with different mutants. Together with the G1 strand, the FGL sequence has the potential to form an interactive surface of five alternating hydrophobic residues on Caf1M chaperone as well as in seven of the 10 other members of the FGL subfamily.

A vector-transformation system is described that permits replacement of a portion of the single rRNA operon of the archaeon Halobacterium halobium with a homologous fragment from a vector-borne gene. The vector construct contains three functional sections: (i) an entire H. halobium rRNA operon with two selective mutations in the 23S rRNA

Bovine leukemia virus (BLV) is an oncogenic retrovirus of the Deltaretrovirus genus, which causes persistent infection in its natural hostscattle, zebu, and water buffalo with diverse clinical manifestations through the defeat of B-cells. The BLV proviral genome, along with structural genes (gag, pro, pol, and env), includes nonstructural ones (R3, G4, tax, rex, AS, pre-miRs (for miRNAs). We have shown in our previous data the association of some pre-miRs-B' (for BLV miRNA) alleles with leukocyte (WBCwhite blood cell) number in BLV-infected cows. Multifunctional properties of Tax protein have led us to an assumption that tax gene/Tax protein could have too population variations related to WBC counts. Here we report about several tax alleles/Tax protein variants, which have a highly significant association with an increase or a decrease of WBC number in BLV-infected cows. We have provided evidence that Tax A, H variants (tax b, c, d, f, e alleles) are correlated with reduced WBC counts at the level of BLV-negative groups of animals and thus could be the feature of the aleukemic (AL) form of BLV infection. We suggest this finding could be used in BLV testing for the presence of Tax A, H in the proviral DNA consider such strains of BLV as AL ones, and because of this, minimize the clinical losses due to BLV infection in cattle.

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Highlights 18S rRNA phylogenetic analysis of four main classes of Tetrapod is base of PCR test. The result of the test is different PCR fragments for avian and mammalian DNA. 18S rDNA based PCR test determines avian and mammalian DNA. 18S rDNA based PCR test determines avian and mammalian meat in different products.

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Poultry eggs contain high-quality proteins, fat, vitamins, and minerals necessary for human nutrition as food and ingredients in the food industry. Egg whites have exceptional foaming, emulsifying, gelling, and heat setting properties, making them popular for use in baked goods. Intensive study of egg whites to date has now settled on a stable opinion that there are no cells, and no DNA, in them. However, this study demonstrates the possibility of DNA extraction from outer thin whites of chicken egg. Protein degradation of chicken egg white contents by trypsin has been used. The 18S ribosomal DNA based PCR test shows that the extracted from outer thin whites DNA contains nuclear DNA. Moreover, the Hoechst 33342 staining proves that outer thin whites contain nuclei. Therefore, this study demonstrates that chicken egg whites contain nuclear DNA and contain nuclei (i.e., and cells).