Fat Storage-inducing Transmembrane Protein 2 Is Required for Normal Fat Storage in Adipose Tissue

Triglycerides within the cytosol of cells are stored in a phylogenetically conserved organelle called the lipid droplet (LD). LDs can be formed at the endoplasmic reticulum, but mechanisms that regulate the formation of LDs are incompletely understood. Adipose tissue has a high capacity to form lipid droplets and store triglycerides. Fat storage-inducing transmembrane protein 2 (FITM2/FIT2) is highly expressed in adipocytes, and data indicate that FIT2 has an important role in the formation of LDs in cells, but whether FIT2 has a physiological role in triglyceride storage in adipose tissue remains unproven. Here we show that adipose-specific deficiency of FIT2 (AF2KO) in mice results in progressive lipodystrophy of white adipose depots and metabolic dysfunction. In contrast, interscapular brown adipose tissue of AF2KO mice accumulated few but large LDs without changes in cellular triglyceride levels. High fat feeding of AF2KO mice or AF2KO mice on the genetically obese ob/ob background accelerated the onset of lipodystrophy. At the cellular level, primary adipocyte precursors of white and brown adipose tissue differentiated in vitro produced fewer but larger LDs without changes in total cellular triglyceride or triglyceride biosynthesis. These data support the conclusion that FIT2 plays an essential, physiological role in fat storage in vivo.     

Detached and attached Arabidopsis leaf assays reveal distinctive defense responses against hemibiotrophic Colletotrichum spp

The agriculturally important genus Colletotrichum is an emerging model pathogen for studying defense in Arabidopsis. During the process of screening for novel pathogenic Colletotrichum isolates on Arabidopsis, we found significant differences in defense responses between detached and attached leaf assays. A near-adapted isolate Colletotrichum linicola A1 could launch a typical infection only on detached, but not attached, Arabidopsis leaves. Remarkably, resistance gene-like locus RCH1-mediated resistance in intact plants also was compromised in detached leaves during the attacks with the virulent reference isolate C. higginsianum. The differences in symptom development between the detached leaf and intact plant assays were further confirmed on defense-defective mutants following inoculation with C. higginsianum, where the greatest inconsistency occurred on ethylene-insensitive mutants. In intact Arabidopsis plants, both the salicylic acid- and ethylene-dependent pathways were required for resistance to C. higginsianum and were associated with induced expression of pathogenesis-related genes PR1 and PDF1.2. In contrast, disease symptom development in detached leaves appeared to be uncoupled from these defense pathways and more closely associated with senescence: an observation substantiated by coordinated gene expression analysis and disease symptom development, and chemically and genetically mimicking senescence.     

Application of living immobilized cells to the acceleration of the continuous conversions of ethanol (wort) to acetic acid (vinegar)—Hydrous titanium(IV) oxide-immobilized Acetobacter species

Various strains of Acetobacter species have been immobilized on hydrous titanium(IV) oxide or hydrous titanium(IV) chelated cellulose and used in the continuous conversion of a dilute aqueous alcoholic solution (in the form of‘charging wort’) into acetic acid (in the form of vinegar) in tower fermenter-type reactors. A strain of Acetobacter species producing extracellular polysaccharide aggregated in the presence of hydrous titanium(IV) oxide thereby enabling higher medium flow rates and an increased acetic acid output to be achieved. A strain of Acetobacter species not producing polysaccharide showed no effect with hydrous titanium(IV) oxide but did produce more acetic acid when a titanium(IV)-cellulose chelate was added to the fermentation, although aggregation was not observed. Mechanisms, which appear to conform to established results, are proposed for the aggregation of both strains of bacteria. Apparently, these water-insoluble titanium compounds can interact with the bacterial cells, increasing their density and thus making them more resistant to ‘wash out’ by increasing the rate at which they sediment in the fermenter. This enables a greater cell mass per unit volume to be achieved which in turn leads to an increase in conversion rate in the reactor.     

Proliferating cell nuclear antigen (PCNA) as a proliferative marker during embryonic and adult zebrafish hematopoiesis

We investigated the expression of proliferative cell nuclear antigen (PCNA) in zebrafish to delineate the proliferative hematopoietic component during adult and embryonic hematopoiesis. Immunostaining for PCNA and enhanced green fluorescence protein (eGFP) was performed in wild-type and fli1-eGFP (endothelial marker) and gata1-eGFP (erythroid cell marker) transgenic fish. Expression of PCNA mRNA was examined in wild-type and chordin morphant embryos. In adult zebrafish kidney, the renal tubules are surrounded by endothelial cells and it is separated into hematopoietic and excretory compartments. PCNA was expressed in hematopoietic progenitor cells but not in mature neutrophils, eosinophils or erythroid cells. Some PCNA+ cells are scattered in the hematopoietic compartment of the kidney while others are closely associated with renal tubular cells. PCNA was also expressed in spermatogonial stem cells and intestine crypts, consistent with its role in cell proliferation and DNA synthesis. In embryos, PCNA is expressed in the brain, spinal cord and intermediate cell mass (ICM) at 24 h-post fertilization. In chordin morphants, PCNA is significantly upregulated in the expanded ICM. Therefore, PCNA can be used to mark cell proliferation in zebrafish hematopoietic tissues and to identify a population of progenitor cells whose significance would have to be further investigated.     

Strategies for recombinant expression of small, highly disulphide-bonded, cationic antimicrobial peptides

Expression of two recombinant hepcidin homologues from Atlantic salmon, Salmo salar, characterization of their antimicrobial activity, and partial structural determination of the peptides is described. Expression was attempted in baculovirus and bacterial expression systems and the various purification and refolding methods used to determine the optimal strategy for production of active, correctly refolded hepcidin are reviewed.