Genes involved in the biosynthesis of PQQ fromAcinetobacter calcoaceticus

From a gene bank of theAcinetobacter calcoaceticus genome a plasmid was isolated that complements four different classes of PQQ^- mutants. Subclones of this plasmid revealed that the four corresponding PQQ genes are located on a fragment of 5 kilobases. The nucleotide sequence of this 5 kb fragment was determined and by means of Tn5 insertion mutants the reading frames of the PQQ genes could be identified. Three of the PQQ genes code for proteins of M_r 29700 (gene I), M_r 10800 (gene II) and M_r 43600 (gene III) respectively. In the DNA region where gene IV was mapped however the largest possible reading frame encodes for a polypeptide of only 24 amino acids. A possible role for this small polypeptide will be discussed. Finally we show that expression of the four PQQ genes inAcinetobacter lwoffi andEscherichia coli lead to the synthesis of the coenzyme in these organisms.     

Expression of CD44 Splice Variants During Lymphocyte Activation and Tumor Progression

Recently, splice variants of CD44 have been described that confer metastatic potential to non-metastasizing rat pancreatic carcinoma and sarcoma cell lines. Using antibodies against variant CD44 (CD44v) sequences, we have examined the expression of variant CD44 glycoproteins on human lymphoid cells and tissues and in colorectal neoplasia. Lymphohematopoietic cells express low levels of CD44v glycoproteins. During the process of lymphocyte activation in vitro and in vivo, expression of CD44v glycoproteins is transiently upregulated. The reaction pattern of various antibodies indicates that these CD44 variants contain the domain encoded by exon v6, which is part of the variant that confers metastatic capability. In human colorectal neoplasia we observed overexpression of CD44 splice variants in all invasive carcinomas. Already at early stages of colorectal tumor progression exon v5 epitopes were overexpressed. Tumor progression was strongly related to expression of CD44 isoforms containing exon v6 encoded domains. The findings establish CD44 variants as tumor progression markers in colorectal cancer.     

Experimental evaluation of realized niche models for predicting responses of plant species to a change in environmental conditions

Abstract. We estimated, using logistic regression techniques, the realized niches of the four dominant species in an experimental marsh complex located in the Delta Marsh, Manitoba, Canada. These models were then used to predict the probability of occurrence of these species in selected elevation ranges when water levels were raised in 1985 either 0, 30 or 60 cm above the long-term normal water level. These realized-niche models were calculated using elevation and species data collected in 1980. After having been eliminated by two years of deep flooding, the emergent vegetation in this complex had been re-established during a drawdown beginning in either 1983 or 1984. Our hypothesis was that from 1985 to 1989 the frequencies of occurrence of species in selected elevation ranges would converge to their probabilities predicted from the 1980 logistic models. This was not borne out by our results. Actual frequencies and predicted probabilities of occurrence of a species were similar at best less than 40% and then mostly in the control (0 cm) treatment. The realized-niche models were not adequate to predict the distribution of emergents after an increase in water level in the short term because the emergent species did not migrate upslope. Emergent species in the medium and high treatments either (1) died out - Scolochloa festucacea and Scirpus lacustris - after 3 yr because they could not survive permanent flooding, (2) stayed where they were - Phragmites australis - because they were unable to move upslope through clonal growth, or (3) became more widespread - Typha glauca only because of the expansion of small local populations already established in 1985 in areas dominated formerly by other species.     

Modeling the circular economy in environmentally extended input–output: A web application

Global environmental and resource problems ask for new ways of managing the production and consumption of resources. The implementation of new paradigms, such as the circular economy, requires decision‐makers at multiple levels to make complex decisions. For this, clear analyses and modeling of scenarios are of utmost importance. Meanwhile, as the sophistication of databases and models increases so does the need for user‐friendly tools to use them. The RaMa‐Scene web platform reduces these barriers by allowing users to visualize easily diverse impacts of implementing circular‐economy interventions. This online web platform makes use of the multi‐regional environmentally extended input–output database EXIOBASE version 3 in monetary units, which has been modified to show explicit transactions of raw materials from recycling activities.     

Engagement of SIRPα Inhibits Growth and Induces Programmed Cell Death in Acute Myeloid Leukemia Cells

Background

Recent studies show the importance of interactions between CD47 expressed on acute myeloid leukemia (AML) cells and the inhibitory immunoreceptor, signal regulatory protein-alpha (SIRPα) on macrophages. Although AML cells express SIRPα, its function has not been investigated in these cells. In this study we aimed to determine the role of the SIRPα in acute myeloid leukemia.

Design and Methods

We analyzed the expression of SIRPα, both on mRNA and protein level in AML patients and we further investigated whether the expression of SIRPα on two low SIRPα expressing AML cell lines could be upregulated upon differentiation of the cells. We determined the effect of chimeric SIRPα expression on tumor cell growth and programmed cell death by its triggering with an agonistic antibody in these cells. Moreover, we examined the efficacy of agonistic antibody in combination with established antileukemic drugs.

Results

By microarray analysis of an extensive cohort of primary AML samples, we demonstrated that SIRPα is differentially expressed in AML subgroups and its expression level is dependent on differentiation stage, with high levels in FAB M4/M5 AML and low levels in FAB M0–M3. Interestingly, AML patients with high SIRPα expression had a poor prognosis. Our results also showed that SIRPα is upregulated upon differentiation of NB4 and Kasumi cells. In addition, triggering of SIRPα with an agonistic antibody in the cells stably expressing chimeric SIRPα, led to inhibition of growth and induction of programmed cell death. Finally, the SIRPα-derived signaling synergized with the activity of established antileukemic drugs.

Conclusions

Our data indicate that triggering of SIRPα has antileukemic effect and may function as a potential therapeutic target in AML.     

Antibody-dependent cell lysis by NK cells is preserved after sarcoma-induced inhibition of NK cell cytotoxicity

Osteosarcoma and Ewing’s sarcoma tumor cells are susceptible to IL15-induced or antibody-mediated cytolytic activity of NK cells in short-term cytotoxicity assays. When encountering the tumor environment in vivo, NK cells may be in contact with tumor cells for a prolonged time period. We explored whether a prolonged interaction with sarcoma cells can modulate the activation and cytotoxic activity of NK cells. The 40 h coculture of NK cells with sarcoma cells reversibly interfered with the IL15-induced expression of NKG2D, DNAM-1 and NKp30 and inhibited the cytolytic activity of NK cells. The inhibitory effects on receptor expression required physical contact between NK cells and sarcoma cells and were independent of TGF-β. Five days pre-incubation of NK cells with IL15 prevented the down-regulation of NKG2D and cytolytic activity in subsequent cocultures with sarcoma cells. NK cell FcγRIIIa/CD16 receptor expression and antibody-mediated cytotoxicity were not affected after the coculture. Inhibition of NK cell cytotoxicity was directly linked to the down-regulation of the respective NK cell-activating receptors. Our data demonstrate that the inhibitory effects of sarcoma cells on the cytolytic activity of NK cells do not affect the antibody-dependent cytotoxicity and can be prevented by pre-activation of NK cells with IL15. Thus, the combination of cytokine-activated NK cells and monoclonal antibody therapy may be required to improve tumor targeting and NK cell functionality in the tumor environment.