Hereditary hemorrhagic telangiectasia: ENG and ALK-1 mutations in Dutch patients

Hereditary hemorrhagic telangiectasia (HHT) or Rendu-Osler-Weber disease is an autosomal dominant disorder characterized by an aberrant vascular development. The resulting vascular lesions range from smaller mucocutaneous telangiectases to large visceral arteriovenous malformations, especially in the skin, lung, gastrointestinal tract and the brain. Mutations in the genes encoding endoglin (ENG, chromosome 9q34) and activin A receptor type-like kinase 1 (ALK-1, also named ACVRL1, chromosome 12q13) are associated with HHT1 and HHT2, respectively. We report here on the genetic and molecular heterogeneity found in the HHT population in the Netherlands. Probands of 104 apparently unrelated families were studied and we performed sequence analysis on both the ENG gene and ALK-1 gene. In most of the probands, we found a mutation in one of the two genes: 53% in the ENG gene and 40% in the ALK-1 gene. In 7% of the families no ENG or ALK1 mutation was found. The mutations detected were deletions, insertions, nonsense, missense and splice site mutations. The majority were novel mutations.     

Repercussions of the COVID-19 pandemic on athletes: a cross-sectional study

The COVID-19 pandemic has presented significant challenges and implications for the sports community. Thus, this study aimed to describe the prevalence of COVID-19 in Brazilian athletes and identify the epidemiological, clinical, athletic, life and health factors associated with the disease in these individuals. A cross-sectional study was performed involving 414 athletes from 22 different sports using an online questionnaire from August to November 2020. The association between the athletes’ characteristics and COVID-19 was evaluated using a logistic regression model. The prevalence of COVID-19 was 8.5%, although only 40% of athletes reported having been tested. Being under 27 years of age (3-fold), having children (~5-fold), having a teammate test positive for COVID-19 (2.5-fold), and smoking (14-fold) were associated with a possible higher risk of disease. Almost 20% of athletes self-reported musculoskeletal injuries during the period of the pandemic that was studied. Athletes with a university education (P = 0.02), a profession other than sports (P < 0.001), those from a low-income family (P = 0.01), and public health system users (P = 0.04) were significantly less frequently tested for COVID-19, whereas international competitors, athletes who received a wage, and athletes who had a teammate who tested positive for COVID-19 were 2-, 3-, and 15-fold more likely to be tested for COVID-19, respectively. Approximately 26% of the athletes who tested negative or were untested reported more than three characteristic COVID-19 symptoms, and 11% of athletes who tested positive for COVID-19 were asymptomatic. The identification of modifiable (have children, smoking, and teammates positively tested) and non-modifiable (age under 27 years) factors related to COVID-19 in athletes can contribute to implementing surveillance programmes to decrease the incidence of COVID-19 in athletes and its negative impacts in sports.     

Hybrid speciation through sorting of parental incompatibilities in Italian sparrows

Speciation by hybridization is emerging as a significant contributor to biological diversification. Yet, little is known about the relative contributions of (i) evolutionary novelty and (ii) sorting of pre‐existing parental incompatibilities to the build‐up of reproductive isolation under this mode of speciation. Few studies have addressed empirically whether hybrid animal taxa are intrinsically isolated from their parents, and no study has so far investigated by which of the two aforementioned routes intrinsic barriers evolve. Here, we show that sorting of pre‐existing parental incompatibilities contributes to intrinsic isolation of a hybrid animal taxon. Using a genomic cline framework, we demonstrate that the sex‐linked and mitonuclear incompatibilities isolating the homoploid hybrid Italian sparrow at its two geographically separated hybrid–parent boundaries represent a subset of those contributing to reproductive isolation between its parent species, house and Spanish sparrows. Should such a sorting mechanism prove to be pervasive, the circumstances promoting homoploid hybrid speciation may be broader than currently thought, and indeed, there may be many cryptic hybrid taxa separated from their parent species by sorted, inherited incompatibilities.     

Amplified B lymphocyte CD40 signaling drives regulatory B10 cell expansion in mice

Background

Aberrant CD40 ligand (CD154) expression occurs on both T cells and B cells in human lupus patients, which is suggested to enhance B cell CD40 signaling and play a role in disease pathogenesis. Transgenic mice expressing CD154 by their B cells (CD154^TG) have an expanded spleen B cell pool and produce autoantibodies (autoAbs). CD22 deficient (CD22^−/−) mice also produce autoAbs, and importantly, their B cells are hyper-proliferative following CD40 stimulation ex vivo. Combining these 2 genetic alterations in CD154^TGCD22^−/− mice was thereby predicted to intensify CD40 signaling and autoimmune disease due to autoreactive B cell expansion and/or activation.

Methodology/Principal Findings

CD154^TGCD22^−/− mice were assessed for their humoral immune responses and for changes in their endogenous lymphocyte subsets. Remarkably, CD154^TGCD22^−/− mice were not autoimmune, but instead generated minimal IgG responses against both self and foreign antigens. This paucity in IgG isotype switching occurred despite an expanded spleen B cell pool, higher serum IgM levels, and augmented ex vivo B cell proliferation. Impaired IgG responses in CD154^TGCD22^−/− mice were explained by a 16-fold expansion of functional, mature IL-10-competent regulatory spleen B cells (B10 cells: 26.7×10⁶±6 in CD154^TGCD22^−/− mice; 1.7×10⁶±0.4 in wild type mice, p<0.01), and an 11-fold expansion of B10 cells combined with their ex vivo-matured progenitors (B10+B10pro cells: 66×10⁶±3 in CD154^TGCD22^−/− mice; 6.1×10⁶±2 in wild type mice, p<0.01) that represented 39% of all spleen B cells.

Conclusions/Significance

These results demonstrate for the first time that the IL-10-producing B10 B cell subset has the capacity to suppress IgG humoral immune responses against both foreign and self antigens. Thereby, therapeutic agents that drive regulatory B10 cell expansion in vivo may inhibit pathogenic IgG autoAb production in humans.     

Characterization of macronuclear DNA in five species of ciliates

Macronuclear DNA of four hypotrichous and one holotrichous ciliate species was characterized by biochemical techniques. The renaturation kinetics of the macronuclear DNAs of all five species were similar. Repetitive sequences occur only in an amount below 2%. Although the DNA content of the macronuclei of the species differs considerably, the kinetic complexity of the macronuclear DNA is rather uniform (around 3 × 10¹⁰ daltons, i.e., 4–11 x the E. coli genome). Only in the macronuclei of the hypotrichous species the DNA exists as gene-sized fragments.Dedicated to Professor W. Beermann on the occasion of his 60th birthday     

Domestication and crop evolution of wheat andbarley: Genes,genomics, and future directions

Wheat and barley are two of the founder crops of the agricultural revolution that took place 10,000 years ago in the Fertile Crescent and both crops remain among the world's most important crops. Domestication of these crops from their wild ancestors required the evolution of traits useful to humans, rather than survival in their natural environment. Of these traits, grain retention and threshability, yield improvement, changes to photoperiod sensitivity and nutritional value are most pronounced between wild and domesticated forms. Knowledge about the geographical origins of these crops and the genes responsible for domestication traits largely pre-dates the era of nextgeneration sequencing, although sequencing will lead to new insights. Molecular markers were initially used to calculate distance(relatedness), genetic diversity and to generate genetic maps which were useful in cloning major domestication genes. Both crops are characterized by large,complex genomes which were long thought to be beyond the scope of whole-genome sequencing. However, advances in sequencing technologies have improved the state of genomic resources for both wheat and barley. The availability of reference genomes for wheat and some of its progenitors,as well as for barley, sets the stage for answering unresolved questions in domestication genomics of wheat and barley.     

Polymorphism of the DQA1 promoter region (QAP) and DRB1, QAP,DQA1, DQB1 haplotypes in systemic lupus erythematosus

We have investigated the DNA polymorphism for the DQA1 promoter region (QAP) and HLA-class II DRB1, DQA1, and DQB1 genes in 178 central European patients with Systemic lupus erythematosus (SLE) using polymerase chain reaction and Dig-ddUTP labeled oligonucleotides. Increased frequencies of DRB1*02 and *03 are confirmed by DNA typing. In addition, the frequencies of DQA1*0501, *0102 and DQB1*0201, *0602 alleles are increased in the patients as compared to controls. The strongest association to SLE is found with DRB1*03 and DQB1*0201 alleles (p<10^–7, p corr. <10^–5 and p<10^–6, p corr. <10^–4, respectively). By investigating the DQA1 promoter region in the SLE patients we have detected nine different QAP variants. Increased frequencies of QAP1.2 and QAP4.1 are observed in patients as compared to controls (p <0.05, p corr. = n. s.). Analysis of linkage disquilibria demonstrates a very strong association between QAP variants and DQA1, DRB1 alleles. Certain QAP variants are completely associated with DQA1 and DRB1 alleles, whereas others can combine with different DQA1 and DRB1 alleles. All DRB1*02-positive patients and controls carry QAP1.2, and all DRB1*03-positive patients and controls carry QAP4.1. Conversely, the QAP1.2 variant appears only in DRB1*02 haplotypes, while the QAP4.1 variant can be observed in DRB1*03, *11, and *1303 haplotypes. Based on the strong linkage disequilibria between DRB1-DQA1-DQB1 genes and between DRB1-QAP-DQA1, we have deduced the four-point haplotypes for DRB1-QAP-DQA1-DQB1 in patients and controls. Two haplotypes DRB1*02-QAP1.2-DQA1*0102-DQB1*0602-and DRB1*03-QAP4.1-DQA1*0501-DQB1*0201 are significantly increased in patient as compared to controls (p<0.01, p corr. = n.s., RR = 1.8 and p <10^–7, p corr. <10^–5, RR = 3.1, respectively). The analysis of relative risks attributed to the various alleles of QAP, DQA1, and DQB1 as well as the investigation of the deduced DRB1-QAP-DQA1-DQB1 haplotypes leads to the conclusion that QAP4.1 and DQA1*0501 on the DR3 haplotypes are probably not involved in SLE susceptibility. There is no evidence for the involvement of DQ2 / dimers coded in transposition. Thus, susceptibility to SLE is on the DR3 haplotype most probably localized at DRB1 or telomeric of DRB1, while for the DR2 haplotype such orientation cannot be given. SLE study group members: M. Baur, A. Corvetta, H. Ehrfeld, J. Frey, J. R. Kalden, F. Krapf, B. Lang, G. G. Lange, K. Pirner, C. Rittner, E. Röther, P. Schneider, H. P. Seelig, S. Seuchter, W. Stangel, C. Specker, P. Späth, H. Deicher. Correspondence to: Z. Yao.     

Expression,purification, and inhibition of in vitro proteolysis of human AMPD2 (isoform L) recombinant enzymes

AMP deaminase (AMPD) is a multigene family in higher eukaryotes whose three members encode tetrameric isoforms that catalyze the deamination of AMP to IMP. AMPD polypeptides share conserved C-terminal catalytic domains of approximately 550 amino acids, whereas divergent N-terminal domains of approximately 200-330 amino acids may confer isoform-specific properties to each enzyme. However, AMPD polypeptides are subject to limited N-terminal proteolysis during purification and subsequent storage at 4 degrees C. This presents a technical challenge to studies aimed at determining the structural and functional significance of these divergent sequences. This study describes the recombinant overexpression of three naturally occurring human AMPD2 proteins, 1A/2, 1B/2, and 1B/3, that differ by N-terminal extensions of 47-128 amino acids, resulting from the use of multiple promoters and alternative splicing events. A survey of protease inhibitors reveals that E-64 and leupeptin are able to maintain the subunit structure of each AMPD2 protein when they are included in extraction and storage buffers. Gel filtration chromatography of these three purified AMPD2 enzymes comprised of intact subunits reveals that each migrates faster than expected, resulting in observed molecular masses significantly greater than those predicted for native tetrameric structures. However, chemical crosslinking analysis indicates four subunits per AMPD2 molecule, confirming that these enzymes have a native tetrameric structure. These combined results suggest that AMPD2 N-terminal extensions may exist as extended structures in solution.