Anti-XK monoclonal antibody Made to order

In a wireless communication network, the channel assignment problem addresses the correct assignment of a frequency to each transmitter in the network. To avoid interference between two nearby transmitters, the assigned frequencies must satisfy certain conditions related to the distance between transmitters. We can use only a limited number of channels; hence, we have to minimize the range of frequencies used. The distance labelling of a graph is a mathematical model of the channel assignment problem derived from the work of Hale [Frequency assignment: Theory and application, Proc. IEEE 68 (1980), pp. 1497-1514]. Lam et al. [L(j, k)-labelings for the products of complete graphs, J. Comb. Optim. 14 (2007), pp. 219-227] addressed distance two labelling for the direct product K(n)xK(m) of complete graphs K-n and K-m. In this paper, we solve the distance three labelling problem for K(n)xK(2).

Background: The major carbohydrate components of lignocellulosic biomass are cellulose and hemicelluloses. Saccharomyces cerevisiae cannot efficiently utilize xylose derived upon the hydrolysis of hemicelluloses. Although engineering the yeast with xylose metabolic pathway has been intensively studied, challenges are still ahead for developing robust strains for lignocellulosic bioethanol production. Objective: The main objective of this study was to reveal the role of the MIG1 mutant isolated from the self-flocculating S. cerevisiae SPSC01 in xylose utilization, glucose repression and ethanol fermentation by S. cerevisiae. Methods: The MIG1 mutant was amplified from S. cerevisiae SPSC01 by PCR and MIG1-overexpression-cassette was transformed into S. cerevisiae S288c and xylose-metabolizing strain YB-2625-T through homologous recombination. Yeast growth was measured by colony assay on plates with or without xylose supplementation. Then xylose utilization and ethanol production were further evaluated through flask fermentation when mixed sugars of glucose and xylose at 3:1 and 2:1, respectively, were supplied. Fermentation products were detected by HPLC, and activities of xylose reductase (XR), xylitol dehydrogenase (XDH) and xylulokinase (XK) were also measured. The transcription of genes regulated by the expression of the MIG1 mutant was analyzed by RTqPCR. Evolutionary relationship of various MIG1s was developed by gene sequencing and sequence alignment. Results: No difference was observed for S288c growing with xylose when it was engineered with the overexpression or deletion of its native MIG1, but its growth was enhanced when overexpressing the MIG1 mutant from SPSC01. The submerged culture of YB-2625-T MIG1-SPSC engineered with xylose-metabolic pathway and the MIG1 mutant indicated that xylitol accumulation was decreased, and consequently, more biomass was accumulated. Furthermore, improved activities of the key enzymes such as XR, XDH and XK were detected in YB-2625-T MIG1-SPSC. Evolutionary analysis of MIG1s amplified from S. cerevisiae strains commonly used for ethanol production revealed a close relationship of SPSC01 and YB-2625. Conclusion: Our results demonstrated the effect of the overexpression of the MIG1 mutant from SPSC01 on xylose utilization of S. cerevisiae. This study could be an alternative strategy for engineering S. cerevisiae with improved xylose utilization.