Both the C1 domain and a basic amino acid cluster at the C-terminus are important for the neurite and branch induction ability of DGKβ

We previously reported that diacylglycerol kinase β (DGKβ) induces neurites and branches, contributing to higher brain function including emotion and memories. However, the detailed molecular mechanism of DGKβ function remains unknown. Therefore, we constructed various mutants of DGKβ and compared their enzyme activity, intracellular localization, and ability to induce neurites and branching in SH-SY5Y cells.     

Identification and characterization of granule bound starch synthase I (GBSSI) gene of tartary buckwheat (Fagopyrum tataricum Gaertn.)

Tartary buckwheat (Fagopyrum tataricum Gaertn.) is increasingly considered as an important functional food material because of its rich nutraceutical compounds. Reserve starch is the major component of tartary buckwheat seed. However, the gene sequences and the molecular mechanism of tartary buckwheat starch synthesis are unknown so far. In this study, the complete genomic sequence and full-size cDNA coding tartary buckwheat granule-bound starch synthase I (FtGBSSI), which is responsible for amylose synthesis, were isolated and analyzed. The genomic sequence of the FtGBSSI contained 3947 nucleotides and was composed of 14 exons and 13 introns. The cDNA coding sequence of FtGBSSI shared 63.3%–75.1% identities with those of dicots and 56.6%–57.5% identities with monocots (Poaceae). In deduced amino acid sequence of FtGBSSI, eight motifs conserved among plant starch synthases were identified. A cleavage at the site IVC↓G of FtGBSSI protein produces the chloroplast transit sequence of 78 amino acids and the mature protein of 527 amino acids. The FtGBSSI mature protein showed an identity of 73.4%–77.8% with dicot plants, and 67.6%–70.4% with monocot plants (Poaceae). The mature protein was composed of 20 α-helixes and 16 β-strands, and folds into two main domains, N- and C-terminal domains. The critical residues which are involved in ADP and sugar binding were predicted. These results will be useful to modulate starch composition of buckwheat kernels with the aim to produce novel improved varieties in future breeding programs.     

Uncovering molecular events associated with the chemosuppressive effects of flaxseed: a microarray analysis of the laying hen model of ovarian cancer

Background

The laying hen model of spontaneous epithelial ovarian cancer (EOC) is unique in that it is the only model that enables observations of early events in disease progression and is therefore also uniquely suited for chemoprevention trials. Previous studies on the effect of dietary flaxseed in laying hens have revealed the potential for both amelioration and prevention of ovarian cancer. The objective of this study was to assess the effect of flaxseed on genes and pathways that are dysregulated in tumors. We have used a bioinformatics approach to identify these genes, followed by qPCR validation, immunohistochemical localization, and in situ hybridization to visualize expression in normal ovaries and tumors from animals fed a control diet or a diet containing 10% flaxseed.

Results

Bioinformatic analysis of ovarian tumors in hens led to the identification of a group of highly up-regulated genes that are involved in the embryonic process of branching morphogenesis. Expression of these genes coincides with expression of E-cadherin in the tumor epithelium. Levels of expression of these genes in tumors from flax-fed animals are reduced 40-60%. E-cadherin and miR200 are both up-regulated in tumors from control-fed hens, whereas their expression is decreased 60-75% in tumors from flax-fed hens. This does not appear to be due to an increase in ZEB1 as mRNA levels are increased five-fold in tumors, with no significant difference between control-fed and flax-fed hens.

Conclusions

We suggest that nutritional intervention with flaxseed targets the pathways regulating branching morphogenesis and thereby alters the progression of ovarian cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-709) contains supplementary material, which is available to authorized users.     

In Vitro Pancreas Organogenesis from Dispersed Mouse Embryonic Progenitors

The pancreas is an essential organ that regulates glucose homeostasis and secretes digestive enzymes. Research on pancreas embryogenesis has led to the development of protocols to produce pancreatic cells from stem cells ¹. The whole embryonic organ can be cultured at multiple stages of development ^2-4. These culture methods have been useful to test drugs and to image developmental processes. However the expansion of the organ is very limited and morphogenesis is not faithfully recapitulated since the organ flattens. We propose three-dimensional (3D) culture conditions that enable the efficient expansion of dissociated mouse embryonic pancreatic progenitors. By manipulating the composition of the culture medium it is possible to generate either hollow spheres, mainly composed of pancreatic progenitors expanding in their initial state, or, complex organoids which progress to more mature expanding progenitors and differentiate into endocrine, acinar and ductal cells and which spontaneously self-organize to resemble the embryonic pancreas. We show here that the in vitro process recapitulates many aspects of natural pancreas development. This culture system is suitable to investigate how cells cooperate to form an organ by reducing its initial complexity to few progenitors. It is a model that reproduces the 3D architecture of the pancreas and that is therefore useful to study morphogenesis, including polarization of epithelial structures and branching. It is also appropriate to assess the response to mechanical cues of the niche such as stiffness and the effects on cell´s tensegrity.     

A branching process for the early spread of a transposable element in a diploid population

Transposable elements (TEs) face significant challenges upon transfer into a new host population, invariably beginning their invasion with only a single element. The fate of this element is a product of its internal properties, the population dynamics of the host species, and genetic drift. We present a continuous-time multi-type branching process to model the early stages of TE spread. The model incorporates seasonal population size changes and is applicable to diploid hosts for prevalences up to 10%. We reproduce standard results of TE population dynamics and show that population growth may have a greater influence on reducing TE loss probability than a transpositional burst. These results are applied to the planned use of a TE to drive an antimalarial gene into an Anopheles gambiae population. The model favors a transgenic release immediately following the dry season when the An. gambiae population begins to grow. Increasing the number of transgenic hosts released has the greatest influence on reducing the probability of TE loss. Following release, the rate at which the TE increases its proportion in the population is most sensitive to its replicative transposition rate. The model recommends a replicative transposition rate greater than 0.1 per TE per generation to satisfy public health goals.     

Determining the expected variability of immune responses using the cyton model

During an adaptive immune response, lymphocytes proliferate for 5–20 cell divisions, then stop and die over a period of weeks. The cyton model for regulation of lymphocyte proliferation and survival was introduced by Hawkins et al. (Proc. Natl. Acad. Sci. USA 104, 5032–5037, 2007) to provide a framework for understanding this response and its regulation. The model assumes stochastic values for division and survival times for each cell in a responding population. Experimental evidence indicates that the choice of times is drawn from a skewed distribution such as the lognormal, with the fate of individual cells being potentially highly variable. For this reason we calculate the higher moments of the model so that the expected variability can be determined. To do this we formulate a new analytic framework for the cyton model by introducing a generalization to the Bellman–Harris branching process. We use this framework to introduce two distinct approaches to predicting variability in the immune response to a mitogenic signal. The first method enables explicit calculations for certain distributions and qualitatively exhibits the full range of observed immune responses. The second approach does not facilitate analytic solutions, but allows simple numerical schemes for distributions for which there is little prospect of analytic formulae. We compare the predictions derived from the second method to experimentally observed lymphocyte population sizes from in vivo and in vitro experiments. The model predictions for both data sets are remarkably accurate. The important biological conclusion is that there is limited variation around the expected value of the population size irrespective of whether the response is mediated by small numbers of cells undergoing many divisions or for many cells pursuing a small number of divisions. Therefore, we conclude the immune response is robust and predictable despite the potential for great variability in the experience of each individual cell.      

Semaphorin3a inhibits ureteric bud branching morphogenesis

Class 3 semaphorins are guidance proteins involved in axon pathfinding, vascular patterning and lung branching morphogenesis in the developing mouse embryo. Semaphorin3a (Sema3a) is expressed in renal epithelia throughout kidney development, including podocytes and ureteric bud cells. However, the role of Sema3a in ureteric bud branching is unknown. Here we demonstrate that Sema3a plays a role in patterning the ureteric bud tree in both metanephric organ cultures and Sema3a mutant mice. In vitro ureteric bud injection with Sema3a antisense morpholino resulted in increased branching, whereas recombinant SEMA3A inhibited ureteric bud branching and decreased the number of developing glomeruli. Additional studies revealed that SEMA3A effects on ureteric bud branching involve downregulation of glial cell-line derived neurotrophic factor (GDNF) signaling, competition with vascular endothelial growth factor A (VEGF-A) and decreased activity of Akt survival pathways. Deletion of Sema3a in mice is associated with increased ureteric bud branching, confirming its inhibitory role in vivo. Collectively, these data suggest that Sema3a is an endogenous antagonist of ureteric bud branching and hence, plays a role in patterning the renal collecting system as a negative regulator.     

Branch direction in Carnegiea gigantea (Cactaceae): Regional patterns and the effect of nurse plants

Abstract. Branch direction in Carnegiea gigantea (saguaro) cacti affects PAR interception and CO₂ uptake, and may influence reception of photomorphogenic cues. Branch direction data were collected in 29 saguaro populations over Arizona to determine if the southerly bias observed in previous studies at two locales can be generalized to the American range of the saguaro, and to determine the effect of shading by nurse plants on branch direction. Locally observed S bias from previous studies can be extended and generalized to include the American saguaro range. Branches were statistically uniform across environmental variability regarding temperature and precipitation. The S bias was not found in saguaros shaded by large nurse plants, supporting the assertion that branch direction occurs, in part, to maximize receipt of insolation.