Purification and partial characterization of phytotoxic glycopeptides secreted by Colletotrichum gloeosporioides

Colletotrichum gloeosporioides secretes a phytotoxic compound that causes anthracnose in Hevea brasiliensis: as a first step we attempted to follow mycelium growth, pH and toxin production by this fungus. The compound was isolated and partially purified by ultrafiltration, acetone precipitation and affinity and gel-permeation chromatography. Material purified was largely carbohydrate with a small protein fraction. Galactose, mannose and rhamnose were the neutral sugars encountered, and serine and threonine the major amino acids found. We propose a molecular mass for this substance of 50333 Da.     

Quantification of water and biomass in small colony variant PAO1 biofilms by confocal Raman microspectroscopy

The Raman spectra, water content, and biomass density of wild-type (WT) Pseudomonas aeruginosa PAO1, small colony variant (SCV) PAO1, and Pseudoalteromonas sp. NCIMB 2021 biofilms were compared in order to determine their variation with strain and species. Living, fully submerged biofilms were analyzed in situ by confocal Raman microspectroscopy for up to 2 weeks. Water to biomass ratios (W/BRs), which are the ratios of the O–H stretching vibration of water at 3,450 cm⁻¹ to the C–H stretching band characteristic of biomass at 2,950 cm⁻¹, were used to estimate the biomass density and cell density by comparison with W/BRs of protein solutions and bacterial suspensions, respectively, on calibration curves. The hydration within SCV biofilm colonies was extremely heterogeneous whereas W/BRs were generally constant in young WT biofilm colonies. The mean biomass in biofilm colonies of WT or colony cores of SCV was typically equivalent to 16% to 27% protein (w/v), but was 10% or less for NCIMB 2021. The corresponding cell densities were 7.5 to >10 × 10¹⁰ cfu mL⁻¹ for SCV, while the maximum cell density for NCIMB biofilms was 2.8 × 10¹⁰ cfu mL⁻¹.     

Real time device for biosensing: design of a bacteriophage model using love acoustic waves

Love wave sensors (ST-cut quartz substrate with interdigital transducers, SiO(2) guiding layer and sensitive coating) have been receiving a great deal of attention for a few years. Indeed, the wave coupled in a guiding layer confers a high gravimetric sensitivity and the shear horizontal (SH) polarization allows to work in liquid media. In this paper, an analytical method is proposed to calculate the Love wave phase velocity and the gravimetric sensitivity for a complete multilayer structure. This allows us to optimize the Love wave devices design in order to improve their gravimetric sensitivity in liquid media. As a model for virus or bacteria detection in liquids (drinking or bathing water, food em leader ) we design a model using M13 bacteriophage. The first step is the anti-M13 (AM13) monoclonal antibody grafting, on the device surface (SiO(2)). The second step is an immunoreaction in between the M13 bacteriophage and the AM13 antibody. The Love wave device allows to detect in real time the graft of the AM13 sensitive coating, as well as the immobilization of the M13 bacteriophages. With a pH change, the M13 bacteriophages can be removed from the sensor surface, in order to be numerated as plaque forming unit (pfu). Results on the sensitivity of Love waves are compared with similar immunological works with bulk acoustic wave devices, and demonstrate the high potentialities of Love waves sensors.     

Differential effects of MYH9 and APOL1 risk variants on FRMD3 Association with Diabetic ESRD in African Americans

Single nucleotide polymorphisms (SNPs) in MYH9 and APOL1 on chromosome 22 (c22) are powerfully associated with non-diabetic end-stage renal disease (ESRD) in African Americans (AAs). Many AAs diagnosed with type 2 diabetic nephropathy (T2DN) have non-diabetic kidney disease, potentially masking detection of DN genes. Therefore, genome-wide association analyses were performed using the Affymetrix SNP Array 6.0 in 966 AA with T2DN and 1,032 non-diabetic, non-nephropathy (NDNN) controls, with and without adjustment for c22 nephropathy risk variants. No associations were seen between FRMD3 SNPs and T2DN before adjusting for c22 variants. However, logistic regression analysis revealed seven FRMD3 SNPs significantly interacting with MYH9—a finding replicated in 640 additional AA T2DN cases and 683 NDNN controls. Contrasting all 1,592 T2DN cases with all 1,671 NDNN controls, FRMD3 SNPs appeared to interact with the MYH9 E1 haplotype (e.g., rs942280 interaction p-value = 9.3E⁻⁷ additive; odds ratio [OR] 0.67). FRMD3 alleles were associated with increased risk of T2DN only in subjects lacking two MYH9 E1 risk haplotypes (rs942280 OR = 1.28), not in MYH9 E1 risk allele homozygotes (rs942280 OR = 0.80; homogeneity p-value = 4.3E⁻⁴). Effects were weaker stratifying on APOL1. FRMD3 SNPS were associated with T2DN, not type 2 diabetes per se, comparing AAs with T2DN to those with diabetes lacking nephropathy. T2DN-associated FRMD3 SNPs were detectable in AAs only after accounting for MYH9, with differential effects for APOL1. These analyses reveal a role for FRMD3 in AA T2DN susceptibility and accounting for c22 nephropathy risk variants can assist in detecting DN susceptibility genes.     

Phage morphology recapitulates phylogeny: the comparative genomics of a new group of myoviruses

Among dsDNA tailed bacteriophages (Caudovirales), members of the Myoviridae family have the most sophisticated virion design that includes a complex contractile tail structure. The Myoviridae generally have larger genomes than the other phage families. Relatively few "dwarf" myoviruses, those with a genome size of less than 50 kb such as those of the Mu group, have been analyzed in extenso. Here we report on the genome sequencing and morphological characterization of a new group of such phages that infect a diverse range of Proteobacteria, namely Aeromonas salmonicida phage 56, Vibrio cholerae phages 138 and CP-T1, Bdellovibrio phage φ1422, and Pectobacterium carotovorum phage ZF40. This group of dwarf myoviruses shares an identical virion morphology, characterized by usually short contractile tails, and have genome sizes of approximately 45 kb. Although their genome sequences are variable in their lysogeny, replication, and host adaption modules, presumably reflecting differing lifestyles and hosts, their structural and morphogenesis modules have been evolutionarily constrained by their virion morphology. Comparative genomic analysis reveals that these phages, along with related prophage genomes, form a new coherent group within the Myoviridae. The results presented in this communication support the hypothesis that the diversity of phages may be more structured than generally believed and that the innumerable phages in the biosphere all belong to discrete lineages or families.