Non-Esterified Fatty Acids Generate Distinct Low-Molecular Weight Amyloid-β (Aβ42) Oligomers along Pathway Different from Fibril Formation

Amyloid-beta (A beta) peptide aggregation is known to play a central role in the etiology of Alzheimer\u27s disease (AD). Among various aggregates, low-molecular weight soluble oligomers of A beta are increasingly believed to be the primary neurotoxic agents responsible for memory impairment. Anionic interfaces are known to influence the A beta aggregation process significantly. Here, we report the effects of interfaces formed by medium-chain (C9-C12), saturated non-esterified fatty acids (NEFAs) on A beta 42 aggregation. NEFAs uniquely affected A beta 42 aggregation rates that depended on both the ratio of A beta:NEFA as well the critical micelle concentration (CMC) of the NEFAs. More importantly, irrespective of the kind of NEFA used, we observed that two distinct oligomers, 12-18 mers and 4-5 mers were formed via different pathway of aggregation under specific experimental conditions: (i) 12-18 mers were generated near the CMC in which NEFAs augment the rate of A beta 42 aggregation towards fibril formation, and, (ii) 4-5 mers were formed above the CMC, where NEFAs inhibit fibril formation. The data indicated that both 12-18 mers and 4-5 mers are formed along an alternate pathway called \u27off-pathway\u27 that did not result in fibril formation and yet have subtle structural and morphological differences that distinguish their bulk molecular behavior. These observations, (i) reflect the possible mechanism of A beta aggregation in physiological lipid-rich environments, and (ii) reiterate the fact that all oligomeric forms of A beta need not be obligatory intermediates of the fibril formation pathway

Evaluation of the available animal models for Bartonella infections

The diseases caused by the Bartonella genus of bacteria are clinically diverse, and can be challenging to cure. The study of bartonellosis has been hampered by the lack of a suitable animal model. Preclinical studies for novel therapeutics and a competent host for vector transmission studies are needed to fill critical knowledge gaps. The studies included here are a representation of in vivo Bartonella research and the corresponding challenges. This review examines the current state of available animal models by assessing the success of various model species and strains in Bartonella infection. With a focus on the strengths and weaknesses of current animal models, the importance of these models for improvement of human health and veterinary care is emphasized

Temporal expression of housekeeping genes.

<p>Raw Ct values for the mRNA of seven <i>A</i>. <i>americanum</i> housekeeping genes from tick salivary glands (A) and midgut (B) throughout a blood meal (unfed–168 h). Each gene was amplified from each sample and the point at which the amplification curve crosses the threshold is considered the Ct.</p

Analysis of microbial load in female salivary glands.

<p>The salivary glands of ticks treated with both Rep-Family RNAi and Aam-41580 RNAi were assessed for their total bacterial loads on day 8 of feeding. MP depletion in the salivary glands caused a significant reduction in the total microbial load in ticks in which both the MP family and single genes were knocked down. Bacterial loads after both types of knockdown were 5–12-fold lower than those of the Lac-Z-RNAi-treated and no-treatment control salivary glands. *P < 0.05.</p

Temporal gene expression of a miscellaneous pool of protein families.

<p>Aam-5252 was not expressed, according to qRT–PCR.</p

Temporal expression of seven tick-specific genes with unknown functions.

<p>AamerSigp-22563 was not expressed, according to qRT–PCR.</p

Larval hatching of tick eggs after ds-Reprolysin multiple gene knockdown.

<p>Depletion of MP transcripts negatively affected the hatching of larvae, whereas no changes in the control samples were observed.</p

Engorgement weights of female ticks.

<p>Tick engorgement weights (mg) from both Rep-MP RNAi and Aa-41580 RNAi ticks fed on sheep. Am-41580 RNAi knockdown caused a significant reduction in tick weights (P < 0.05) compared with the (No Treatment) control; weights were measured on day 10. The size of the ds-Lac-Z (irrelevant RNA)-treated sample was significantly reduced during feeding and was not included in the analysis. RNAi knockdown of the reprolysin family significantly reduced tick weight (P < 0.05) compared with both controls.</p

Multiple sequence alignment of reprolysin MP nucleotide sequences identified for multiple-gene RNAi.

<p>Knockdown was observed in four MPs. Nucleotides with more than 60% homology are highlighted in blue. Red underlining shows the locations of the primers. Actual primer sequences are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147966#pone.0147966.s003" target="_blank">S3 Table</a>.</p

Temporal expression of lipocalin genes.

<p>AamerSigP-18604 was not expressed at any time point, according to qRT–PCR.</p