Permission to pass: on the role of p53 as a gatekeeper for aneuploidy

Aneuploidy-the karyotype state in which the number of chromosomes deviates from a multiple of the haploid chromosome set-is common in cancer, where it is thought to facilitate tumor initiation and progression. However, it is poorly tolerated in healthy cells: during development and tissue homeostasis, aneuploid cells are efficiently cleared from the population. It is still largely unknown how cancer cells become, and adapt to being, aneuploid. P53, the gatekeeper of the genome, has been proposed to guard against aneuploidy. Aneuploidy in cancer genomes strongly correlates with mutations in TP53, and p53 is thought to prevent the propagation of aneuploid cells. Whether p53 also participates in preventing the mistakes in cell division that lead to aneuploidy is still under debate. In this review, we summarize the current understanding of the role of p53 in protecting cells from aneuploidy, and we explore the consequences of functional p53 loss for the propagation of aneuploidy in cancer.

All-Microwave Leakage Reduction Units for Quantum Error Correction with Superconducting Transmon Qubits

Minimizing leakage from computational states is a challenge when using many-level systems like superconducting quantum circuits as qubits. We realize and extend the quantum-hardware-efficient, all-microwave leakage reduction unit (LRU) for transmons in a circuit QED architecture proposed by Battistel et al. This LRU effectively reduces leakage in the second- and third-excited transmon states with up to 99% efficacy in 220 ns, with minimum impact on the qubit subspace. As a first application in the context of quantum error correction, we show how multiple simultaneous LRUs can reduce the error detection rate and suppress leakage buildup within 1% in data and ancilla qubits over 50 cycles of a weight-2 stabilizer measurement.

Nuclear chromosome locations dictate segregation error frequencies

Chromosome segregation errors during cell divisions generate aneuploidies and micronuclei, which can undergo extensive chromosomal rearrangements such as chromothripsis^1-5. Selective pressures then shape distinct aneuploidy and rearrangement patterns-for example, in cancer^6,7-but it is unknown whether initial biases in segregation errors and micronucleation exist for particular chromosomes. Using single-cell DNA sequencing⁸ after an error-prone mitosis in untransformed, diploid cell lines and organoids, we show that chromosomes have different segregation error frequencies that result in non-random aneuploidy landscapes. Isolation and sequencing of single micronuclei from these cells showed that mis-segregating chromosomes frequently also preferentially become entrapped in micronuclei. A similar bias was found in naturally occurring micronuclei of two cancer cell lines. We find that segregation error frequencies of individual chromosomes correlate with their location in the interphase nucleus, and show that this is highest for peripheral chromosomes behind spindle poles. Randomization of chromosome positions, Cas9-mediated live tracking and forced repositioning of individual chromosomes showed that a greater distance from the nuclear centre directly increases the propensity to mis-segregate. Accordingly, chromothripsis in cancer genomes⁹ and aneuploidies in early development¹⁰ occur more frequently for larger chromosomes, which are preferentially located near the nuclear periphery. Our findings reveal a direct link between nuclear chromosome positions, segregation error frequencies and micronucleus content, with implications for our understanding of tumour genome evolution and the origins of specific aneuploidies during development.

High-Fidelity Controlled-Z Gate with Maximal Intermediate Leakage Operating at the Speed Limit in a Superconducting Quantum Processor

Simple tuneup of fast two-qubit gates is essential for the scaling of quantum processors. We introduce the sudden variant (SNZ) of the net zero scheme realizing controlled-Z (CZ) gates by flux control of transmon frequency. SNZ CZ gates realized in a multitransmon processor operate at the speed limit of transverse coupling between computational and noncomputational states by maximizing intermediate leakage. Beyond speed, the key advantage of SNZ is tuneup simplicity, owing to the regular structure of conditional phase and leakage as a function of two control parameters. SNZ is compatible with scalable schemes for quantum error correction and adaptable to generalized conditional-phase gates useful in intermediate-scale applications.

Cellular and humoral immune responses of Senegalese sole, Solea senegalensis (Kaup), following challenge with two Photobacterium damselae subsp. piscicida strains from different geographical origins

The present study aimed to investigate leucocyte responses to inflammation as well as some innate immune parameters of Senegalese sole, Solea senegalensis, following challenge with two strains of Photobacterium damselae subsp. piscicida belonging to the European and Japanese clones described for this bacterium. Pathogenicity assays were performed to assess the virulence of each Photobacterium damselae subsp. piscicida strain for sole. Subsequently, fish were intraperitoneally injected with phosphate-buffered saline (control) or two concentrations (2 × 10² and 2 × 10⁶ CFU mL⁻¹) of each bacterial strain and sampled after 6 and 24 h. Results showed that the European isolate induces a higher degree of response than the Japanese strain. While blood neutrophilia and monocytosis correlated well with the increase in neutrophil and macrophage numbers in the peritoneal cavity, fish infected with the European isolate presented higher peritoneal cell numbers than fish challenged with the Japanese strain. In addition, alternative complement pathway activity and respiratory burst of head kidney leucocytes increased significantly in fish infected with the European isolate. The enhanced innate immune response displayed by Senegalese sole challenged with the European isolate is probably due to the higher degree of virulence presented by this Photobacterium damselae subsp. piscicida strain.

Effect of particle polydispersity on the irreversible adsorption of fine particles on patterned substrates

We performed extensive Monte Carlo simulations of the irreversible adsorption of polydispersed disks inside the cells of a patterned substrate. The model captures relevant features of the irreversible adsorption of spherical colloidal particles on patterned substrates. The pattern consists of (equal) square cells, where adsorption can take place, centered at the vertices of a square lattice. Two independent, dimensionless parameters are required to control the geometry of the pattern, namely, the cell size and cell-cell distance, measured in terms of the average particle diameter. However, to describe the phase diagram, two additional dimensionless parameters, i.e., the minimum and maximum particle radii, are also required. We find that the transition between any two adjacent regions of the phase diagram solely depends on the largest and smallest particle sizes, but not on the shape of the distribution function of the radii. We consider size dispersions up to 20% of the average radius using a physically motivated, truncated, Gaussian-size distribution, and focus on the regime where adsorbing particles do not interact with those previously adsorbed on neighboring cells to characterize the jammed state structure. The study generalizes previous exact relations on monodisperse particles to account for size dispersion. Due to the presence of the pattern, the coverage shows a nonmonotonic dependence on the cell size. The pattern also affects the radius of adsorbed particles, where one observes preferential adsorption of smaller radii, particularly at high polydispersity.

Cryptic species of Didymobothrium rudolphii (Cestoda: Spathebothriidea) from the sand sole, Solea lascaris, off the Portuguese coast, with an analysis of their molecules, morphology, ultrastructure and phylogeny

Didymobothrium rudolphii (Cestoda: Spathebothriidea) was collected seasonally from the sand sole, Solea lascaris, off the northern, central and southern areas of the Portuguese coast. Morphological and molecular analyses were conducted in order to examine the possible existence of cryptic species and to facilitate the circumscription of their morphological boundaries. Data were compared between D. rudolphii specimens from each of the 3 geographical areas and 4 seasons, and principal components analysis of 18 morphological characters was used to detect differences. Two distinct genotypes were present with sequence divergences of 1.9% and 2.1% in the large subunit (lsrDNA) and second internal transcribed spacer (ITS-2) of ribosomal DNA (rDNA), respectively. The less common 'central' genotype was present only off the central area from summer to winter, whereas the 'common' genotype was present throughout the year off the northern and southern areas, but only during spring in the central area. No sequence variation was found within each genotype. The presence of 2 distinct genetic entities was supported by morphological analyses, which showed the 'central' genotype specimens to be more slender and elongate, although morphometric ranges overlapped considerably for most characters. Molecular phylogenetic analysis of 4 of the 5 known genera of the Spathebothriidea showed Spathebothrium to be the earliest branching lineage and the 2 genotypes of Didymobothrium formed a sister group to Cyathocephalus. The concordance of genetic differences with variation in host diet according to season and locality could account for sympatric speciation occurring in the central region of the Portuguese coast.

Third‐trimester erythrocytapheresis in pregnant patients with sickle cell disease

OBJECTIVE

To evaluate the effects of prophylactic transfusion by means of erythrocytapheresis at the beginning of the third trimester of pregnancy in women with sickle cell disease (SCD).

METHODS

A cohort of 14 pregnant women with SCD who received prophylactic erythrocytapheresis transfusions at the beginning of the third trimester was retrospectively compared with a cohort of 17 pregnant women who received simple prophylactic transfusions for no indication other than SCD severity.

RESULTS

Prophylactic erythrocytapheresis transfusions were associated with a lower risk of intrauterine growth restriction (OR, 0.11; 95% confidence interval, 0.01-1.00) and oligohydramnios (OR, 0.65; 95% confidence interval, 0.45-0.92) in pregnant women with SCD.

CONCLUSION

These results suggest that erythrocytapheresis transfusions are beneficial in women with SCD who are in the third trimester of pregnancy. Given the decrease in transfusion risks, this therapy deserves further evaluation in future trials.

Molecular identification of Anisakis species from Pleuronectiformes off the Portuguese coast

Anisakid nematodes belonging to the Anisakis simplex complex are highly prevalent in several fish species off the coast of Portugal and are an important zoonotic problem in the Iberian Peninsula. Two reproductively isolated sibling species of the Anisakis simplex complex were identified from Pleuronectiformes inhabiting the Portuguese coast using restriction fragment length polymorphism (RFLP). Recombinant genotypes corresponding to presumptive Anisakis simplex sensu stricto and Anisakis pegreffii hybrids were also detected by this technique, as well as the species Anisakis typica. Although 25 species of Pleuronectiformes were investigated, Anisakis spp. larvae were only found in seven: Arnoglossus imperialis, Arnoglossus laterna, Lepidorhombus boscii, Citharus linguatula, Platichthys flesus, Dicologlossa cuneata and Solea senegalensis. The occurrence of hybrids in relatively sedentary fishes such as the Pleuronectiformes suggests that the Portuguese coast may constitute an area of hybridization and, therefore, is of particular interest for the study of the process of hybridization and speciation for these anisakids.

First record of Progrillotia dasyatidis Beveridge Neifar and Euzet, 2004 (Cestoda: Trypanorhyncha) plerocerci from Teleost fishes off the Portuguese coast, with a description of the surface morphology

Plerocerci of Progrillotia dasyatidis Beveridge et al. (2004), family Progrillotiidae Palm (2004), are reported from several teleost fishes off the Portuguese coast, giving a first insight into the life cycle biology of these unique trypanorhynchs. The first description and assignment of the plerocercus to P. dasyatidis is based on morphological features, such as scolex and bothria morphology and tentacular hook arrangement, and is expanded to incorporate the surface morphology, examined by scanning electron microscopy, constituting the first ultrastructural study for a species within this family. Comparisons with other species of the genus Progrillotia are made, based on the scolex and bothria morphology and tentacular hook arrangement, in order to give an overview into the variability within this genus, whereas comparisons with adults from the same species evidence the variability within the same species. The systematic approaches of Campbell and Beveridge (1994) and Palm (1997, 2004) are discussed and emphasis is placed on the utility of microtriches and the characteristic life cycle within the genus as systematic characters.

Early total white blood cell recovery is a predictor of low number of apheresis and good CD34(+) cell yield

OBJECTIVE

We analysed peripheral blood progenitor cell (PBPC) mobilisation and collection in order to assess the main factors related to CD34(+) cell yields in patients affected by haematological malignancies.

PATIENTS AND METHODS

The features of CD34(+) cell mobilisation of patients with haematological malignancies that underwent autologous bone marrow transplantation were examined. Mobilisation chemotherapy consisted mainly of cyclophosphamide (CY) 4 or 7 g/m(2) followed by growth factors. Leukapheresis was started when the WBC counts reached 1.0x10(9)/l with the aim to collect at least 5x10(6) CD34(+) cells/kg body weight. The aphereses were performed on continuous-flow blood cell separators. The analysed variables were: age, diagnosis, CT mobilisation regimen, type of growth factor, number of previous CT lines, prior radiotherapy, days for WBC recovery and number of aphereses procedures to achieve the target of CD34(+) cells.

RESULTS

There were 41 consecutive patients (26 M/15 F): 21 non-Hodgkin's lymphoma (NHL), 15 Hodgkin's disease (HD), two chronic myeloid leukaemia (CML) and three multiple myeloma (MM). Eleven patients could not collect the proposed threshold of CD34(+) cells. CY 4 mobilised patients recovered WBC counts in less days (P=0.03). By ANOVA, the days to WBC recovery had a linear function of the predictors "number of aphereses" and "type of mobilisation CT" (coefficients: 0.86 and 0.95, respectively). For the number of aphereses and WBC recovery after CT mobilisation, we obtained a correlation coefficient of 0.36 (P=0.02).

CONCLUSION

This study shows that it is feasible to mobilise and collect PBPC in patients previously treated with CT with or without RT. There was a linear correlation between the days for WBC recovery and the number of aphereses needed to collect the target number of CD34(+) cells. The study suggests that early WBC recovery, using mainly CY 4 mobilisation chemotherapy, is an important predictor of a low number of aphereses to achieve a good CD34(+) yield.

A randomised, prospective comparison of allogeneic bone marrow and peripheral blood progenitor cell transplantation in the treatment of haematological malignancies

We present the results of a prospective, randomised study comparing PBPC and BM focusing on engraftment, acute and chronic GVHD and survival. Forty patients with haematological malignancies received HLA-identical sibling BM (group A) or PBPC (group B). Evaluable patients were 19 (A) and 18 (B). Median age was 35 (17-56) in A and 29.5 (9-51) in B. Conditioning was mainly Bu-Cy2; GVHD prophylaxis was CSA-MTX. PBPC were harvested after 5 days of G-CSF 10 microg/kg/day. Median days for an ANC >0.5 x 10(9)/l was 18 (13-30) in A and 16 (11-25) in B (P = 0.10). Platelets >20 x 10(9)/l occurred at +17 (10-40) in A and +12 (9-36) in B (P = 0.01). The probability of > or =2 grade a-GVHD was 19% (A) and 27% (B) (P = 0.53). The probability of all grade c-GVHD was 70% with BM. In spite of the small number of patients in group B (PBPC), our data suggest the great majority of them will have c-GVHD (P = 0.08); extensive disease was present in 50 and 100%, respectively (P = 0.05). The estimates of overall survival for A and B at 1000 days are 51 and 47%, respectively (P = 0.67); DFS at 1000 days are 52 and 58%, respectively (P = 0.50). PBPC resulted in faster platelet engraftment. The incidence of acute and chronic GVHD was similar in both groups, but the severity of c-GVHD was higher with PBPC. No differences in survival and DFS have been observed to date.

Allogeneic transplantation with blood stem cells mobilized by rhG-CSF for hematological malignancies

Allogeneic blood stem cell (BSC) transplantation has been performed experimentally in some patients with success. Wider application of this therapeutic modality has been hampered ultimately by many factors, mainly the concern that infusion of large numbers of donor T cells could result in an increased incidence and severity of graft-versus-host disease (GVHD). We report the short-term results of 17 allogeneic BSC transplants in patients with hematologic malignancies. When compared to standard BMT results, BSC transplants showed the advantages of faster engraftment, shorter hospital stay and fewer antibiotic needs. The incidence and severity of GVHD, as well as the general BMT-associated morbidity, was comparable between the two groups. BSC collection by apheresis was well tolerated and associated with less morbidity for donors, probably reducing the cost of the treatment. The collection of BSC was a single apheresis procedure and yielded adequate numbers of stem cells to ensure engraftment. Although this was not a prospective randomized study, the data obtained are encouraging and warrant more prospective and controlled studies.

Interaction of chlorpromazine with phospholipid membranes. An EPR study of membrane surface potential effects

The interaction of chlorpromazine (CPZ) with artificial membranes (egg-yolk phosphatidylcholine liposomes) has been studied. Measurements of the surface electric potential, which is modified in the presence of the ionized form of the drug, were obtained by electron paramagnetic resonance spectroscopy (EPR) using a positively charged amphiphilic spin-probe. This probe partitions between the aqueous and lipidic phases depending on the surface potential and on the structural state of the membrane. The surface potential was measured as a function of drug concentration in the range where the spectral line-shapes are not affected by the incorporation of the drug. From these experimental results and through an appropriate formalism we obtain information on the binding of the drug to the lipid bilayer and on the ionization of the drug in the lipidic phase.