Examination of actin and microtubule dependent APC localisations in living mammalian cells

Abstract (provisional) Background The trafficking of the adenomatous polyposis coli (APC) tumour suppressor protein in mammalian cells is a perennially controversial topic. Immunostaining evidence for an actin-associated APC localisation at intercellular junctions has been previously presented, though live imaging of mammalian junctional APC has not been documented. Results Using live imaging of transfected COS-7 cells we observed intercellular junction-associated pools of GFP-APC in addition to previously documented microtubule-associated GFP-APC and a variety of minor localisations. Although both microtubule and junction-associated populations could co-exist within individual cells, they differed in their subcellular location, dynamic behaviour and sensitivity to cytoskeletal poisons. GFP-APC deletion mutant analysis indicated that a protein truncated immediately after the APC armadillo repeat domain retained the ability to localise to adhesive membranes in transfected cells. Supporting this, we also observed junctional APC immunostaining in cultures of human colorectal cancer cell line that express truncated forms of APC. Conclusions Our data indicate that APC can be found in two spatially separate populations at the cell periphery and these populations can co-exist in the same cell. The first localisation is highly dynamic and associated with microtubules near free edges and in cell vertices, while the second is comparatively static and is closely associated with actin at sites of cell-cell contact. Our imaging confirms that human GFP-APC possesses many of the localisations and behaviours previously seen by live imaging of Xenopus GFP-APC. However, we report the novel finding that GFP-APC puncta can remain associated with the ends of shrinking microtubules. Deletion analysis indicated that the N-terminal region of the APC protein mediated its junctional localisation, consistent with our observation that truncated APC proteins in colon cancer cell lines are still capable of localising to the cell cortex. This may have implications for the development of colorectal cancer

Effects of chitin and salicylic acid on biological control activity of Pseudomonas spp. against damping off of pepper

Fluorescent pseudomonads (SE21 and RD41) and resistance inducers (chitin and salicylic acid) were examined for plant growth promotion and biological control of damping off of pepper caused by Rhizoctonia solani. The antagonists SE21 and RD41 isolated from the rhizosphere of pepper were found to be effective in inhibiting the mycelial growth of R. solani in a dual culture assay and increasing the seedling vigour in a roll towel assay. Both antagonists were further characterized for biocontrol and plant growth promoting features. The addition of inducers (chitin alone) increased the antagonist's population in the culture medium. In a further study, seed treatment with antagonists showed an increase in plant growth and controlled the damping off under in vivo conditions. Amendment with inducers alone showed a moderate degree of plant protection against R. solani. However, the reduction in disease was more pronounced when inducers were applied with antagonists. Amendment with chitin alone enhanced biocontrol efficiency of both SE21 and RD41. However, amendment with SA alone or in conjunction with chitin showed a moderate effect on biocontrol efficiency of the antagonists. These results show that the biocontrol efficiency of antagonists SE21 and RD41 may be stimulated by chitin resulting in a significant increase in their population density and antagonistic effect against R. solani.http://www.sciencedirect.com/science/article/B7XN9-4RWJW34-1/1/3803a2492b3f01bbfad363cd3b39108

Twin weight discordance and maternal weight gain in twin pregnancies

Objective: To evaluate the association between twin weight discordance and maternal weight change during the gestational period. Method: One hundred forty‐seven twin pregnancies (Group A: < 25%, Group B: ≥ 25% birth weight discordance) were analyzed using Student’s t‐test, χ2‐test, and two‐way ANOVA at three gestational intervals: before 18 weeks, 18 to 28 weeks, and 28 weeks to birth. Result: There was no statistically significant difference between the two groups involving maternal age, parity, duration of pregnancy, height, pregravid weight, and conception method. Group A showed a pattern of constantly increasing maternal weight without a significant change in the twin weight discordance throughout gestation. However, Group B showed a fluctuation in maternal BMI with remarkably elevated twin weight discordance at 28 weeks to birth. Conclusion: The results suggest that in twin pregnancies constant maternal weight gain throughout gestation is important for maintaining a twin weight discordance of less than 25%.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135432/1/ijgo176.pd

Phase-sensitive wavelength conversion based on cascaded quadratic processes in periodically poled lithium niobate waveguides

We propose and experimentally demonstrate a novel scheme of phase-sensitive wavelength conversion, based on a combination of cascaded second-order nonlinear effects in two cascaded periodically poled lithium niobate waveguides

Submodular Maximization Meets Streaming: Matchings, Matroids, and More

We study the problem of finding a maximum matching in a graph given by an input stream listing its edges in some arbitrary order, where the quantity to be maximized is given by a monotone submodular function on subsets of edges. This problem, which we call maximum submodular-function matching (MSM), is a natural generalization of maximum weight matching (MWM), which is in turn a generalization of maximum cardinality matching (MCM). We give two incomparable algorithms for this problem with space usage falling in the semi-streaming range---they store only $O(n)$ edges, using $O(n\log n)$ working memory---that achieve approximation ratios of $7.75$ in a single pass and $(3+\epsilon)$ in $O(\epsilon^{-3})$ passes respectively. The operations of these algorithms mimic those of Zelke's and McGregor's respective algorithms for MWM; the novelty lies in the analysis for the MSM setting. In fact we identify a general framework for MWM algorithms that allows this kind of adaptation to the broader setting of MSM. In the sequel, we give generalizations of these results where the maximization is over "independent sets" in a very general sense. This generalization captures hypermatchings in hypergraphs as well as independence in the intersection of multiple matroids.Comment: 18 page

SEGA mode locking

Korte pulsen licht worden al sinds lange tijd gebruikt voor een heel scala aan toepassingen, voornamelijk in de fotonica. Zo kun je bijvoorbeeld denken aan materiaalbewerking, datacommunicatie via glasvezel, wetenschappelijk onderzoek, microscopie, eigenlijk teveel om op te noemen. De techniek om korte lichtpulsen te maken, met behulp van een laser, heet “mode locking”. Er is echter een groot probleem bij de standaard methode voor mode locking. De combinatie van een hoge repetitie frequentie (lees: een hoog aantal pulsen per seconde) en een hoog gemiddeld lichtvermogen (in de orde grootte van enkele tientallen Watts) is onmogelijk. Maar omdat fysici er niet van houden als iets “onmogelijk” is, hebben wij een methode ontwikkeld die de combinatie hoge repetitie frequentie en hoog lichtvermogen wel degelijk mogelijk gaat maken. Deze methode noemen wij Separate Gain mode locking, of afgekort SEGA mode locking