[
MicroPubl Biol,
2021]
Saul-Wilson Syndrome (SWS) is an ultra-rare, autosomal dominant skeletal dysplasia syndrome discovered in 1990; only 16 patients have been identified to date (Saul and Wilson 1990; Ferreira et al. 2018, OMIM#: 618150). The disease is characterized by short stature, various craniofacial abnormalities, shortened fingers and toes, and speech and physical developmental delay (Ferreira 2020). SWS is caused by a missense mutation in the COG4 gene, resulting in a G516R residue change. Other pathogenic mutations have been observed in this gene and all are clustered at the C-terminal end of the protein (R724W, R729W, R729A, E764A). These are associated with Congenital Disorder of Glycosylation type 2j (CDGIIj). This is a recessive disease characterized by mild psychomotor delay, mild dysmorphic features, epilepsy, and defective sialylation (Reynders et al. 2009). Besides the mild developmental delay, this disease seems to share virtually no phenotypic similarity with SWS.
[
J Biol Chem,
1996]
Previously, we reported antibacterial activity in the body fluid of the nematode Ascaris suum (Kato, Y. (1995) Zool. Sci. 12, 225-230). The antibacterial activity is due to a heat-stable and trypsin-sensitive molecule that was designated as ASABF (A. suum antibacterial factor). In the present study, the purification, determination of primary structure, and cDNA cloning of ASABF were carried out. The mature peptide of ASABF is a basic peptide consisting of 71 residues and containing four intramolecular disulfide bridges. The amino acid sequence of a precursor for ASABF, deduced from a cDNA clone, indicates that flanking peptides both at the N terminus and at the C terminus are eliminated by processing. ASABF exhibits potent antibacterial activity particularly against Gram-positive bacteria. ASABF has several features that resemble those of insect/arthropod defensins, whereas the statistical significance of the similarity is not observed on comparison of amino acid sequences. A search of data bases revealed ASABF homologues in Caenorhabditis elegans.
[
MicroPubl Biol,
2020]
OP50 is an Escherichia coli strain conventionally used as a bacterial food in the laboratory maintenance of Caenorhabditis elegans on agar plates. It has also been used to feed C. elegans in longitudinal cultures within microfluidic devices (MFDs) (Hulme et al., 2010; Li et al., 2015), where it has been subject to killing by ultraviolet irradiation or pasteurization performed to suppress clogging due to biofilm formation and aggregation (Li et al., 2015; Zhuo et al., 2017). However, the killed bacterial food can change C. elegans aging dynamics, likely due to influences on C. elegans physiology (Saul et al., 2009; Gruber et al.;, 2007; Garigan et al., 2002). Further development of longitudinal culturing systems for C. elegans in MFDs requires elucidation of the mechanisms that underlie food bacteria clogging and delineation of culture conditions in which living bacterial food can be incorporated without clogging. Bacteria switch from planktonic growth to aggregated growth under conditions of environmental stress, in the presence of toxins (e.g. antibiotics), and when there is a lack of nutrients (Trunk et al., 2018). Biofilms, such as dental plaque, are bacterial communities that are organized in a film-like form in which they are embedded in a self-produced polymeric matrix on biotic or abiotic surfaces; pellicles are floating biofilms that form at liquid-air interfaces. Meanwhile, autoaggregations are aggregated communities of bacteria suspended in solution, such as bacterial flocs formed in activated sludge. Biofilms and autoaggregations are formed by both shared and independent genetic and physico-chemical mechanisms (Trunk et al., 2018; Berne et al., 2018; Berne et al., 2015). In this study, we examined OP50 biofilm formation.Biofilm formation is mediated by flagellin proteins (e.g. FliC), which form flagella, and the adhesion protein FimH, which is located at the tips of type I pili (Berne et al., 2018, Jones et al., 1995; Pratt and Kolter, 1998; Friedlander et al., 2013). We compared the biofilm formation ability of OP50 with that of the biofilm-forming (Wood et al., 2006) wild-type BW251113 E. coli strain as well as that of two BW251113-derived knockouts produced with a kanamycin (Km) cassette characterized as biofilm formation defective mutants: JW4283: BW25113 fimH::Km (a fimH knockout) and JW1908: BW25113 fliC::Km (a fliC knockout) (Baba et al., 2006). Compared to the original BW251113 strain, BW251113 fliC::Km had a significantly reduced ability to form biofilm on glass and polystyrene (Fig. 1A and 1B, p < 0.05) and BW25113 fimH::Km had a significantly reduced ability to form biofilm on glass (Fig. 1A, p < 0.05; biofilm formation on polystyrene showed a near-significant reduction trend Fig. 1B, p = 0.0574). Compared with the original BW251113 strain, we found that OP50 had a significantly reduced biofilm formation ability on polystyrene (Fig. 1B, p < 0.05; biofilm formation on glass showed a near-significant reduction trend, Fig. 1A, p = 0.0507). The biofilm formation ability of OP50 was as low as that seen with the BW251113 biofilm formation defective mutants, and similar to that of OP50 fliC::Km and OP50 fimH::Km mutants (Fig. 1A and 1B), which were constructed by transferring fliC::Km and fimH::Km alleles to OP50 by P1 transduction (Fig. 1C and 1D). Therefore, we conclude that the original OP50 strain is itself a biofilm formation defective mutant.