The transmembrane glycoprotein (gp41) of human immunodeficiency virus type 1 (HIV-1) has been implicated in the cytopathology observed during HIV infection. The first amino acids located at the amino terminus are involved in membrane fusion and syncytium formation, while sequences located at the carboxy terminus have been predicted to interact with membranes and modify membrane permeability. The HIV-1 gp41 gene has been cloned and expressed in Escherichia coli cells by using pET vectors to analyze changes in membrane permeability produced by this protein. This system is well suited for expressing toxic genes in an inducible manner and for analyzing the function of proteins that modify membrane permeability. gp41 enhances the permeability of the bacterial membrane to hygromycin B despite the low level of expression of this protein. To localize the regions of gp41 responsible for these effects, a number of fragments spanning different portions of gp41 were inducibly expressed in E. coli. Two regions of gp41 were shown to increase membrane permeability: one located at the carboxy terminus, where two highly amphipathic helices have been predicted, and another one corresponding to the membrane-spanning domain. Expression of the central region of gp41 comprising this domain was highly lytic for E. coli cells and increased membrane permeability to a number of compounds. These findings are discussed in the light of HIV-induced cytopathology and gp41 structure.

No abstract

Education and training in musculoskeletal ultrasound (MSUS) comprises attendance at theoretical and practical courses and independent study. Web-based learning as a novel teaching method has previously been described. The present study summarizes normal and pathological findings in a web-based approach using widely accepted guidelines. In a prospective study over a period of 3 years normal and pathological images of the musculoskeletal system have been documented and catalogued. Overall 1240 ultrasound images and 183 ultrasound videos were collected. A total of 14.4% were normal and 85.6% were pathological MSUS findings; 61% concerned the upper extremity, while 39% were images and videos of the lower limbs. The most captured conditions included synovitis (33.3%), pathologies of the tendons e.g., tenosynovitis or tendinosis (19.6%) and normal findings (14.4%). The most represented diseases were rheumatoid arthritis (20%), calcium deposition disease (8.2%), gout (7.1%) and osteoarthritis (6.9%). The images and videos were edited and integrated in a web-based tool.

Cyanobacteria are photosynthetic prokaryotes of high ecological and biotechnological relevance that have been cultivated in laboratories around the world for more than 70 years. Prolonged laboratory culturing has led to multiple microevolutionary events and the appearance of a large number of domesticated substrains among model cyanobacteria. Despite its widespread occurrence, strain domestication is still largely ignored. In this work we describeSynechococcus elongatusPCC 7942-KU, a novel domesticated substrain of the model cyanobacteriumSynechococcus elongatusPCC 7942, which presents a fast-sedimenting phenotype. Under higher ionic strengths the sedimentation rate increases leading to complete sedimentation in just 12 h. Through whole genome sequencing and gene deletion, we demonstrate that the Group 3 alternative sigma factor F (SigF) plays a key role in cell sedimentation. In addition, sedimentation analysis of an unpiliated mutant and differences in surface hydrophobicity suggest that mutations in SigF lead to significant changes of cell surface structures and, consequentially, to the appearance of a fast-sedimenting phenotype. This work sheds light on the determinants of the planktonic to benthic transitions and provides genetic targets to generate fast-sedimenting strains that could unlock cost-effective cyanobacterial harvesting at scale.

Cyanobacteria are photosynthetic prokaryotes of high ecological and biotechnological relevance that have been cultivated in laboratories around the world for more than 70 years. Prolonged laboratory culturing has led to multiple microevolutionary events and the appearance of a large number of ‘domesticated’ substrains among model cyanobacteria. Despite its widespread occurrence, strain domestication is still largely ignored. In this work we describe Synechococcus elongatus PCC 7942‐KU, a novel domesticated substrain of the model cyanobacterium S. elongatus PCC 7942, which presents a fast‐sedimenting phenotype. Under higher ionic strengths the sedimentation rate increased leading to complete sedimentation in just 12 h. Through whole genome sequencing and gene deletion, we demonstrated that the Group 3 alternative sigma factor F plays a key role in cell sedimentation. Further analysis showed that significant changes in cell surface structures and a three‐fold increase in released polysaccharides lead to the appearance of a fast‐sedimenting phenotype. This work sheds light on the determinants of the planktonic to benthic transitions and provides genetic targets to generate fast‐sedimenting strains that could unlock cost‐effective cyanobacterial harvesting at scale.