POLQ suppresses genome instability and alterations in DNA repeat tract lengths.

DNA polymerase theta (POLQ) is a principal component of the alternative non-homologous end-joining (ANHEJ) DNA repair pathway that ligates DNA double-strand breaks. Utilizing independent models of POLQ insufficiency during telomere-driven crisis, we found that  cells are resistant to crisis-induced growth deceleration despite sustaining inter-chromosomal telomere fusion frequencies equivalent to wild-type (WT) cells. We recorded longer telomeres in than WT cells pre- and post-crisis, notwithstanding elevated total telomere erosion and fusion rates.

Dysgu: efficient structural variant calling using short or long reads.

Structural variation (SV) plays a fundamental role in genome evolution and can underlie inherited or acquired diseases such as cancer. Long-read sequencing technologies have led to improvements in the characterization of structural variants (SVs), although paired-end sequencing offers better scalability. Here, we present dysgu, which calls SVs or indels using paired-end or long reads.

High-throughput STELA provides a rapid test for the diagnosis of telomere biology disorders.

Telomere biology disorders are complex clinical conditions that arise due to mutations in genes required for telomere maintenance. Telomere length has been utilised as part of the diagnostic work-up of patients with these diseases; here, we have tested the utility of high-throughput STELA (HT-STELA) for this purpose. HT-STELA was applied to a cohort of unaffected individuals (n = 171) and a retrospective cohort of mutation carriers (n = 172).

Tracking telomere fusions through crisis reveals conflict between DNA transcription and the DNA damage response.

Identifying attributes that distinguish pre-malignant from senescent cells provides opportunities for targeted disease eradication and revival of anti-tumour immunity. We modelled a telomere-driven crisis in four human fibroblast lines, sampling at multiple time points to delineate genomic rearrangements and transcriptome developments that characterize the transition from dynamic proliferation into replicative crisis. Progression through crisis was associated with abundant intra-chromosomal telomere fusions with increasing asymmetry and reduced microhomology usage, suggesting shifts in DNA repair capacity.

Catastrophic Endgames: Emerging Mechanisms of Telomere-Driven Genomic Instability.

When cells progress to malignancy, they must overcome a final telomere-mediated proliferative lifespan barrier called replicative crisis. Crisis is characterized by extensive telomere fusion that drives widespread genomic instability, mitotic arrest, hyperactivation of autophagy, and cell death. Recently, it has become apparent that that the resolution of dicentric chromosomes, which arise from telomere fusions during crisis, can initiate a sequence of events that leads to chromothripsis, a form of extreme genomic catastrophe.

Chromothripsis during telomere crisis is independent of NHEJ, and consistent with a replicative origin.

Telomere erosion, dysfunction, and fusion can lead to a state of cellular crisis characterized by large-scale genome instability. We investigated the impact of a telomere-driven crisis on the structural integrity of the genome by undertaking whole-genome sequence analyses of clonal populations of cells that had escaped crisis. Quantification of large-scale structural variants revealed patterns of rearrangement consistent with chromothripsis but formed in the absence of functional nonhomologous end-joining pathways.

DNA Ligase 1 is an essential mediator of sister chromatid telomere fusions in G2 cell cycle phase.

Fusion of critically short or damaged telomeres is associated with the genomic rearrangements that support malignant transformation. We have demonstrated the fundamental contribution of DNA ligase 4-dependent classical non-homologous end-joining to long-range inter-chromosomal telomere fusions. In contrast, localized genomic recombinations initiated by sister chromatid fusion are predominantly mediated by alternative non-homologous end-joining activity that may employ either DNA ligase 3 or DNA ligase 1.

Telomere Length Dynamics and the Evolution of Cancer Genome Architecture.

Telomeres are progressively eroded during repeated rounds of cell division due to the end replication problem but also undergo additional more substantial stochastic shortening events. In most cases, shortened telomeres induce a cell-cycle arrest or trigger apoptosis, although for those cells that bypass such signals during tumour progression, a critical length threshold is reached at which telomere dysfunction may ensue. Dysfunction of the telomere nucleoprotein complex can expose free chromosome ends to the DNA double-strand break (DSB) repair machinery, leading to telomere fusion with both telomeric and non-telomeric loci.

Distal phenylalanine modification for enhancing cellular delivery of fluorophores, proteins and quantum dots by cell penetrating peptides.

For cell penetrating peptides (CPPs) to fulfil their promise as effective delivery vectors we need a better understanding of their mechanisms of cell binding and uptake. This is especially the case when they are linked to different types of cargo. Here we describe new studies based on our previous findings suggesting that, for peptide-CPP chimeras, distal hydrophobic residues upstream of the CPP sequence can have profound effects on the way they interact with cells.

Endocytosis, intracellular traffic and fate of cell penetrating peptide based conjugates and nanoparticles.

The insides of cells can be viewed as a treasure trove of targets for therapeutic intervention of diseases or as deposits for contrasting agents. Increasingly the molecules that need to be delivered to the inside of cells for these purposes are macromolecular and membrane impermeable. Cell penetrating peptides (CPPs) have proven abilities to deliver a range of macromolecular cargo into cells thus raising their profile as potential delivery vectors for wide-ranging applications.

The predatory strike of free ranging praying mantises, Sphodromantis lineola (Burmeister). II: Strikes in the horizontal plane.

The predatory behavior of free ranging praying mantises, Sphodromantis lineola (Burmeister), in response to prey at various positions in the horizontal plane was examined using high speed (200 frames per second) videography. We found that the movements of the meso- and metathoracic legs over the course of the strike were analogous in many respects to those made by the cockroach Periplaneta americana during escape turns. When mantises struck at prey directly ahead of them, they were propelled forward by extensions of the metathoracic femur-tibia, and the meso- and metathoracic coxa-femur joints (changes in the latter were determined indirectly via changes in the femur-pterothorax angles).

The predatory strike of free ranging praying mantises, Sphodromantis lineola (Burmeister). I: Strikes in the mid-sagittal plane.

The predatory behavior of free ranging praying mantises, Sphodromantis lineola (Burmeister), in response to prey at various positions in the midsagittal plane, was examined using high speed (200 frames per second) videography. Predatory strikes fell neatly into two categories based on the elevation of the prey from the surface on which the mantises stood: high strikes and low strikes. When the prey was 35 degrees or more above the surface (measured from the mesothoracic tarsus), mantises assumed a posture that elevated and pointed the body upwards (high strikes).