Maize endosperm ADP-glucose pyrophosphorylase SHRUNKEN2 and BRITTLE2 subunit interactions

ADP-glucose pyrophosphorylase (AGP) represents a key regulatory step in polysaccharide synthesis in organisms ranging from bacteria to plants. Higher plant AGPs are complex in nature and are heterotetramers consisting of two similar but distinct subunits. How the subunits are assembled into enzymatically active polymers is not yet understood. Here, we address this issue by using naturally occurring null mutants of the Shrunken2 (Sh2) and Brittle2 (Bt2) loci of maize as well as the yeast two-hybrid expression system. In the absence of the maize endosperm large AGP subunit (SH2), the BT2 subunit remains as a monomer in the developing endosperm. In contrast, the SH2 protein, in the absence of BT2, is found in a complex of 100 kD. A direct interaction between SH2 and BT2 was proven when they were both expressed in yeast. Several motifs are essential for SH2:BT2 interaction because truncations removing the N or C terminus of either subunit eliminate SH2:BT2 interactions. Analysis of subunit interaction mutants (sim) also identified motifs essential for protein interactions.     

Pre- and Post-Natal Maternal Depressive Symptoms in Relation with Infant Frontal Function,Connectivity, and Behaviors

This study investigated the relationships between pre- and early post-natal maternal depression and their changes with frontal electroencephalogram (EEG) activity and functional connectivity in 6- and 18-month olds, as well as externalizing and internalizing behaviors in 24-month olds (n = 258). Neither prenatal nor postnatal maternal depressive symptoms independently predicted neither the frontal EEG activity nor functional connectivity in 6- and 18-month infants. However, increasing maternal depressive symptoms from the prenatal to postnatal period predicted greater right frontal activity and relative right frontal asymmetry amongst 6-month infants but these finding were not observed amongst 18-month infants after adjusted for post-conceptual age on the EEG visit day. Subsequently increasing maternal depressive symptoms from the prenatal to postnatal period predicted lower right frontal connectivity within 18-month infants but not among 6-month infants after controlling for post-conceptual age on the EEG visit day. These findings were observed in the full sample and the female sample but not in the male sample. Moreover, both prenatal and early postnatal maternal depressive symptoms independently predicted children’s externalizing and internalizing behaviors at 24 months of age. This suggests that the altered frontal functional connectivity in infants born to mothers whose depressive symptomatology increases in the early postnatal period compared to that during pregnancy may reflect a neural basis for the familial transmission of phenotypes associated with mood disorders, particularly in girls.     

Hepatitis B and C Co-Infection in HIV Patients from the TREAT Asia HIV Observational Database: Analysis of Risk Factors and Survival

Background

We assessed the effects of hepatitis B (HBV) or hepatitis C (HCV) co-infection on outcomes of antiretroviral therapy (ART) in HIV-infected patients enrolled in the TREAT Asia HIV Observational Database (TAHOD), a multi-center cohort of HIV-infected patients in the Asia-Pacific region.

Methods

Patients testing HBs antigen (Ag) or HCV antibody (Ab) positive within enrollment into TAHOD were considered HBV or HCV co-infected. Factors associated with HBV and/or HCV co-infection were assessed by logistic regression models. Factors associated with post-ART HIV immunological response (CD4 change after six months) and virological response (HIV RNA <400 copies/ml after 12 months) were also determined. Survival was assessed by the Kaplan-Meier method and log rank test.

Results

A total of 7,455 subjects were recruited by December 2012. Of patients tested, 591/5656 (10.4%) were HBsAg positive, 794/5215 (15.2%) were HCVAb positive, and 88/4966 (1.8%) were positive for both markers. In multivariate analysis, HCV co-infection, age, route of HIV infection, baseline CD4 count, baseline HIV RNA, and HIV-1 subtype were associated with immunological recovery. Age, route of HIV infection, baseline CD4 count, baseline HIV RNA, ART regimen, prior ART and HIV-1 subtype, but not HBV or HCV co-infection, affected HIV RNA suppression. Risk factors affecting mortality included HCV co-infection, age, CDC stage, baseline CD4 count, baseline HIV RNA and prior mono/dual ART. Shortest survival was seen in subjects who were both HBV- and HCV-positive.

Conclusion

In this Asian cohort of HIV-infected patients, HCV co-infection, but not HBV co-infection, was associated with lower CD4 cell recovery after ART and increased mortality.     

Polymorphisms at Locus 4p14 of Toll-Like Receptors TLR-1 and TLR-10 Confer Susceptibility to Gastric Carcinoma in Helicobacter pylori Infection

Helicobacter pylori (H. pylori) -induced gastric inflammation impacts the functions of leptin- and ghrelin-producing cells in the gastroduodenum. Inflammation resulting from H. pylori sensing via Toll-like receptors (TLRs) and the associated downstream signaling largely remain ambiguous. Here, we investigated the role of gut hormones, pro-inflammatory cytokines and single nucleotide polymorphisms (SNPs) associated with TLR 4p14 in H. pylori disease in 30 subjects with non-ulcer dyspepsia (NUD), 40 with peptic ulcer disease (PUD) and 15 with gastric cancer (GC) subjects positive and negative for H. pylori infection. The level of pro-inflammatory cytokines was directly proportional to the severity of gastritis, and disease status influenced the levels of gut hormones and pro-inflammatory cytokines. TLR-1 SNPs rs4833095 and TLR-10 SNPs rs10004195 and were directly associated with H. pylori disease, and were up-regulated in the presence of H. pylori in a genotype-independent manner. We concluded that TLR-1 rs4833095 and TLR10 rs10004195 confer susceptibility to development of gastroduodenal disease, especially GC in H.pylori disease.     

Genetic system in Pseudomonas alcaligenes NCIB 9867

Abstract Genetic transfer of both auxotrophic and catabolic markers was detected in filter matings of mutant strains of Pseudomonas alcaligenes NCIB 9867. Bidirectional transfer of auxotrophic markers was demonstrated in most of the crosses. Strains could either act as donors or recipients. Polarized transfer of auxotrophic markers was observed in some crosses. There was low co-inheritance of both 2,5X⁺ catabolic marker and auxotrophic markers. No evidence could be presented indicating the involvement of the indigenous 33-kb plasmid in the genetic transfer process. Partial sensitivity to DNase was observed in some of the crosses. Maximum frequency of recombinant formation obtained with mating cultures from stationary growth phase suggested an influence of physiological states on genetic transfer. As transfer did not appear to be due to classical transformation or to be plasmid-mediated, the likely mechanism could involve the release of DNA upon intimate cell-to-cell contact. The gene transfer system may be useful for linkage analysis of closely linked genes.     

Transgene expression from CpG-reduced lentiviral gene delivery vectors in vitro

Current viral gene delivery vectors for gene therapy are inefficient due to short-lived transgene expression attributed to the cytosine-phosphate-guanine (CpG) motifs in the transgene. Here we assessed the effects of CpG motif reduction in lentiviral (LV) gene delivery context on the level and duration of reporter gene expression in Chinese Hamster Ovary (CHO) cells, Human Immortalized Myelogenous Leukemia (K562) cells and hematopoietic stem cells (HSCs). The cells were transduced with LV carrying Zero-CpG green fluorescent protein (ZGFP) reporter gene, LV/CMV/ZGFP. The GFP expression was compared to its non CpG-depleted GFP reporter gene LV (LV/CMV/GFP) counterpart. The LV/CMV/ZGFP exhibited prolonged transgene expression in CHO cells and HSCs up to 10 days and 14 days, in the respective cells. This effect was not seen in the transduced K562 cells, which may be due to the DNA hypomethylation status of the cancer cell line. Transgene copy number analysis verified that the GFP expression was not from pseudo-transduction and the transgene remained in the genome of the cells throughout the period of the study. The modest positive effects from the LV/CMV/ZGFP suggest that the reduction of CpG in the LV construct was not substantial to generate higher and more prolonged transgene expression.     

Embryonic Stem Cells Do Not Stiffen on Rigid Substrates

It has been previously established that living cells, including mesenchymal stem cells, stiffen in response to elevation of substrate stiffness. This stiffening is largely attributed to the elevation of the tractions at the cell base that is associated with increases in cell spreading on more-rigid substrates. We show here, surprisingly, that mouse embryonic stem cells (ESCs) do not stiffen when substrate stiffness increases. As shown recently, these cells do not increase spreading on more-rigid substrates either. However, these ESCs do increase their basal tractions as substrate stiffness increases. We conclude that these ESCs exhibit mechanical behaviors distinct from those of mesenchymal stem cells and of terminally differentiated cells, and decouple its apical cell stiffness from its basal tractional stresses during the substrate rigidity response.     

An Extended Bidomain Framework Incorporating Multiple Cell Types

The muscular layers within the walls of the gastrointestinal tract contain two distinct cell types, the interstitial cells of Cajal and smooth muscle cells, which together produce rhythmic depolarizations known as slow waves. The bidomain model of tissue-level electrical activity consists of single intracellular and extracellular domains separated by an intervening membrane at all points in space and is therefore unable to adequately describe the presence of two distinct cell types in its conventional form. Here, an extension to the bidomain framework is presented whereby multiple interconnected cell types can be incorporated. Although the derivation is focused on the interactions of the interstitial cells of Cajal and smooth muscle cells, the conceptual framework can be more generally applied. Simulations demonstrating the feasibility of the proposed model are also presented.