The Hemagglutinin of Bat-Associated Influenza Viruses Is Activated by TMPRSS2 for pH-Dependent Entry into Bat but Not Human Cells

New World bats have recently been discovered to harbor influenza A virus (FLUAV)-related viruses, termed bat-associated influenza A-like viruses (batFLUAV). The internal proteins of batFLUAV are functional in mammalian cells. In contrast, no biological functionality could be demonstrated for the surface proteins, hemagglutinin (HA)-like (HAL) and neuraminidase (NA)-like (NAL), and these proteins need to be replaced by their human counterparts to allow spread of batFLUAV in human cells. Here, we employed rhabdoviral vectors to study the role of HAL and NAL in viral entry. Vectors pseudotyped with batFLUAV-HAL and -NAL were able to enter bat cells but not cells from other mammalian species. Host cell entry was mediated by HAL and was dependent on prior proteolytic activation of HAL and endosomal low pH. In contrast, sialic acids were dispensable for HAL-driven entry. Finally, the type II transmembrane serine protease TMPRSS2 was able to activate HAL for cell entry indicating that batFLUAV can utilize human proteases for HAL activation. Collectively, these results identify viral and cellular factors governing host cell entry driven by batFLUAV surface proteins. They suggest that the absence of a functional receptor precludes entry of batFLUAV into human cells while other prerequisites for entry, HAL activation and protonation, are met in target cells of human origin.     

Staff Nurses’ Perceptions and Experiences about Structural Empowerment: A Qualitative Phenomenological Study

The aim of the study reported in this article was to investigate staff nurses’ perceptions and experiences about structural empowerment and perceptions regarding the extent to which structural empowerment supports safe quality patient care. To address the complex needs of patients, staff nurse involvement in clinical and organizational decision-making processes within interdisciplinary care settings is crucial. A qualitative study was conducted using individual semi-structured interviews of 11 staff nurses assigned to medical or surgical units in a 600-bed university hospital in Belgium. During the study period, the hospital was going through an organizational transformation process to move from a classic hierarchical and departmental organizational structure to one that was flat and interdisciplinary. Staff nurses reported experiencing structural empowerment and they were willing to be involved in decision-making processes primarily about patient care within the context of their practice unit. However, participants were not always fully aware of the challenges and the effect of empowerment on their daily practice, the quality of care and patient safety. Ongoing hospital change initiatives supported staff nurses’ involvement in decision-making processes for certain matters but for some decisions, a classic hierarchical and departmental process still remained. Nurses perceived relatively high work demands and at times viewed empowerment as presenting additional. Staff nurses recognized the opportunities structural empowerment provided within their daily practice. Nurse managers and unit climate were seen as crucial for success while lack of time and perceived work demands were viewed as barriers to empowerment.     

Electrical fusion of protoplasts from sycamore mutants and hybrid selection on hypoxanthine-aminopterin-thymidine (HAT) medium

Summary An electrical fusion method has been used to form somatic hybrids between protoplasts of two mutant cell lines of sycamore tissue culture cells. Both mutants will not grow in a hypoxanthine-aminopterin-thymidine (HAT) medium. It was possible to select the fused hybrids from homospecific fusion products and nonfused protoplasts by the use of HAT medium. In this way the viability and regeneration of the fused cells during the first few weeks of culture could be evaluated. An electron microscopic examination of the fusion process showed that it occurred at a series of points along the surface of the plasmalemma. Cytoplasmic bridges between the two cells were formed separated by vesicles which later dispersed to give complete cytoplasmic continuity between the cells.     

The effects of various nutritional supplements on the growth,migration and differentiation ofxenopus laevis neural crest cells in vitro

Summary This study investigates the nutritional requirements ofXenopus laevis neural crest cells and melanophores developing in vitro. A comparison is made between the growth and differentiation of cells in serum-containing medium and a chemically defined, serum-free medium that we have designed. Our chemically defined medium is more efficient than serum-supplemented medium in promoting proliferation of these cells. Several supplements are required to enhance culture development. These include insulin, α-melanocyte stimulating hormone, somatotropin, luteotrophic hormone, linoleic acid, uridine, and putrescine. In addition, collagen and fibronectin provide the most conductive environment tested for cell migration and adhesion. This work was supported by establishment and major equipment grants from the Alberta Heritage Foundation for Medical Research to N. C. M. Nadine C. Milos is a Heritage Medical Research Scholar of the Alberta Heritage Foundation for Medical Research.     

Mass-spectrometric evidence for the double-carboxylation pathway of malate synthesis by Crassulacean acid metabolism plants in light

Phyllodia of the Crassulacean acid metabolism (CAM) plant Kalanchoë tubiflora were allowed to fix ¹³CO₂ in light and darkness during phase IV of the diurnal CAM cycle, and during prolongation of the regular light period. After ¹³CO₂ fixation in darkness, only singly labelled [¹³C]malate molecules were found. Fixation of ¹³CO₂ under illumination, however, produced singly labelled malate as well as malate molecules which carried label in two, three or four carbon atoms. When the irradiance during ¹³CO₂ fixation was increased, the proportion of singly labelled malate decreased in favour of plurally labelled malate. The irradiance, however, did not change either the ratio of labelled to unlabelled malate molecules found in the tissue after the ¹³CO₂ application, or the magnitude of malate accumulation during the treatment with label. The ability of the tissue to store malate and the labelling pattern changed throughout the duration of the prolonged light period. The results indicate that malate synthesis by CAM plants in light can proceed via a pathway containing two carboxylation steps, namely ribulose-1,5-bisphosphate-carboxylase/oxygenase (EC 4.1.1.39) and phosphoenolpyruvate carboxylase (EC 4.1.1.31) which operate in series and share common intermediates. It can be concluded that, in light, phosphoenolpyruvate carboxylase can also synthesize malate independently of the proceeding carboxylation step by ribulose-1,5-bisphosphate carboxylase/oxygenase.Abbreviations CAM Crassulacean acid metabolism - PEP phosphoenolpyruvate - PEPCase phosphoenolpyruvate carboxylase (EC 4.1.1.31) - RuBPCase ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) - TMS trimethylsilyl     

Expression of a chimeric CaMV 35S Bacillus thuringiensis insecticidal protein gene in transgenic tobacco

Insecticidal transgenic tobacco plants containing a truncated Bacillus thuringiensis cryIA(b) crystal protein (ICP) gene expressed from the CaMV 35S promoter were analyzed for ICP gene expression under field and greenhouse conditions over the course of a growing season. We present new information on temporal and tissue-specific expression of a CaMV 35S/cryIA(b) gene. Levels of cryIA(b) protein and mRNA were compared in both homozygous and hemizygous lines throughout plant development. Levels of ICP mRNA and protein increased during plant development with a pronounced rise in expression at the time of flowering. Homozygous ICP lines produced higher levels of ICP than the corresponding hemizygous lines. ELISA analysis of different tissues in the tobacco plant showed ICP gene expression in most tissues with a predominance of ICP in older tissue. All transgenic ICP tobacco lines which were studied in the field and greenhouse contained 400 ng to 1 g ICP per gram fresh weight in leaves from the mid-section of the plant at flowering. The amounts of ICP produced by field lines were directly comparable to levels observed in greenhouse-grown plants.     

Biochemical studies carried out on different groups ofCandida parapsilosis andCandida rhagii strains by comparing some cellular and mitochondrial activities

A comparative biochemical study was performed on some strains ofCandida rhagii and on strains belonging to different subgroups ofCandida parapsilosis. Measurements of alcohol dehydrogenase activity, resistance to drugs and occurrence of an alternative pathway enabled us to confirm the classification between several subgroups within theC. parapsilosis species.