In vitro template-change PCR to create single crossover libraries: a case study with B. thuringiensis Cry2A toxins

During evolution the creation of single crossover chimeras between duplicated paralogous genes is a known process for increasing diversity. Comparing the properties of homologously recombined chimeras with one or two crossovers is also an efficient strategy for analyzing relationships between sequence variation and function. However, no well-developed in vitro method has been established to create single-crossover libraries. Here we present an in vitro template-change polymerase change reaction that has been developed to enable the production of such libraries. We applied the method to two closely related toxin genes from B. thuringiensis and created chimeras with differing properties that can help us understand how these toxins are able to differentiate between insect species

Development of High-Loading Trastuzumab PLGA Nanoparticles: A Powerful Tool Against HER2 Positive Breast Cancer Cells

Tania Mariastella Caputo,1,* Giovannina Barisciano,2,* Chiara Mulè,1 Angela Maria Cusano,3 Anna Aliberti,1 Livio Muccillo,2 Vittorio Colantuoni,2 Lina Sabatino,2 Andrea Cusano1,3 1Optoelectronics Group, Department of Engineering, University of Sannio, Benevento, Italy; 2Department of Sciences and Technologies, University of Sannio, Benevento, Italy; 3CeRICTscrl Regional Center Information Communication Technology, Benevento, Italy*These authors contributed equally to this workCorrespondence: Anna Aliberti; Lina Sabatino, Email [email protected]; [email protected]: Trastuzumab, a therapeutic monoclonal antibody directed against HER2, is routinely used to treat HER2-positive breast cancer with a good response rate. However, concerns have arisen in the clinical practice due to adverse side effects. One way to overcome these limitations is to encapsulate trastuzumab in nanoparticles to improve cytotoxic activity, increase intracellular drug concentrations, escape the immune system and avoid systemic degradation of the drug in vivo.Methods: A double emulsion method was used to encapsulate trastuzumab into poly(lactic-co-glycolic) nanoparticles, effective for their biocompatibility and biodegradability. These nanocarriers, hereafter referred to as TZPs, were characterised in terms of size, homogeneity, zeta potential and tested for their stability and drug release kinetics. Finally, the TZPs cytotoxicity was assessed in vitro on the HER2 positive SKBR3 breast cancer cell line and compared to free trastuzumab.Results: The TZPs were stable, homogeneous in size, with a reduced zeta potential. They showed higher encapsulation efficiency and drug loading, a prolonged trastuzumab release kinetics that retained its physicochemical properties and functionality. TZPs showed a stronger cytotoxicity and increased apoptosis than similar doses of free trastuzumab in the cell line analysed. Confocal microscopy and flow cytometry assessed TZPs and trastuzumab cellular uptake while Western blot evaluated downstream signalling, overall HER2 content and shedding.Conclusion: TZPs exert more robust effects than free trastuzumab via a dual mode of action: TZPs are taken up by cells through an endocytosis mechanism and release the drug intracellularly for longer time. Additionally, the TZPs that remain in the extracellular space release trastuzumab which binds to the cognate receptor and impairs downstream signalling. This is the sole modality used by free trastuzumab. Remarkably, half dose of TZPs is as efficacious as the highest dose of free drug supporting their possible use for drug delivery in vivo. Keywords: PLGA nanoparticles, double-emulsion method, trastuzumab, breast cancer, signaling transductio

Pseudomonas fluorescens BBc6R8 type III secretion mutants no longer promote ectomycorrhizal symbiosis.

The Mycorrhiza Helper Bacterium (MHB) Pseudomonas fluorescens BBc6R8 promotes the ectomycorrhizal symbiosis between Douglas fir roots and Laccaria bicolor. In this study, we identified a non-flagellar type III secretion system (T3SS) in the draft genome of BBc6R8 similar to that described in the biocontrol strain P. fluorescens SBW25. We examined whether this T3SS plays a role in the BBc6R8 mycorrhizal helper effect by creating a deletion in the rscRST genes encoding the central channel of the injectisome. The in vitro effect of BBc6R8 T3SS mutants on the radial growth rate of L. bicolor was unchanged compared with the parental strain. In contrast, T3SS mutants were unable to promote mycorrhization, suggesting that type III secretion plays an important role in the mycorrhizal helper effect of P. fluorescens BBc6R8 independent of the promotion of hyphal growth that BBc6R8 exhibits in vitro

Pseudoxanthoma elasticum: point mutations in the ABCC6 gene and a large deletion including also ABCC1 and MYH11.

Pseudoxanthoma elasticum (PXE) is a mendelian disorder characterized by calcification of elastic fibers in skin, arteries, and retina. It results in dermal lesions, arterial insufficiency and retinal hemorrhages, leading to macular degeneration. PXE is transmitted either as an autosomal dominant or recessive trait and several sporadic cases have been observed. Mutations in the ABCC6 gene have been identified very recently in patients. Here, we report on a large Italian family affected by pseudoxanthoma elasticum for which linkage analysis had pointed to a region encompassing markers D16S3069-D16S405-D16S3103; hemizygosity of marker D16S405 allowed us to detect a submicroscopic deletion of at least 900 kb involving ABCC6, ABCC1, and MYH11. Mutation analysis on the other allele of the family, as well as on two additional sporadic cases, revealed nonsense (Y227X, R518X, R1164X) and frame-shift (c.960delC) mutations in ABCC6 (MRP6) further confirming the role of this multi-drug resistance gene in the etiology of pseudoxanthoma elasticum. Furthermore, clinical re-examination of members of the family harboring the deletion led to the detection of additional features, potentially caused by the deletion of the MYH11 gene. In the course of the analysis five nonpathogenic variants were found in ABCC6: 1233T>C, 1245G>A, 1838 T>G (V614A), 1890C>G, and 3506+83C>A. Hum Mutat 18:85, 200

New insights on Pseudoalteromonas haloplanktis TAC125 genome organization and benchmarks of genome assembly applications using next and third generation sequencing technologies

Pseudoalteromonas haloplanktis TAC125 is among the most commonly studied bacteria adapted to cold environments. Aside from its ecological relevance, P. haloplanktis has a potential use for biotechnological applications. Due to its importance, we decided to take advantage of next generation sequencing (Illumina) and third generation sequencing (PacBio and Oxford Nanopore) technologies to resequence its genome. The availability of a reference genome, obtained using whole genome shotgun sequencing, allowed us to study and compare the results obtained by the different technologies and draw useful conclusions for future de novo genome assembly projects. We found that assembly polishing using Illumina reads is needed to achieve a consensus accuracy over 99.9% when using Oxford Nanopore sequencing, but not in PacBio sequencing. However, the dependency of consensus accuracy on coverage is lower in Oxford Nanopore than in PacBio, suggesting that a cost-effective solution might be the use of low coverage Oxford Nanopore sequencing together with Illumina reads. Despite the differences in consensus accuracy, all sequencing technologies revealed the presence of a large plasmid, pMEGA, which was undiscovered until now. Among the most interesting features of pMEGA is the presence of a putative error-prone polymerase regulated through the SOS response. Aside from the characterization of the newly discovered plasmid, we confirmed the sequence of the small plasmid pMtBL and uncovered the presence of a potential partitioning system. Crucially, this study shows that the combination of next and third generation sequencing technologies give us an unprecedented opportunity to characterize our bacterial model organisms at a very detailed level