Microfilament bundles associated with tubular endoplasmic Reticulum in fusiform cells in the active cambial zone ofFraxinus excelsior L.

Protoplasma - In the active cambium ofFraxinus excelsior L. microfilament bundles and tubular endoplasmic reticulum appear always associated with each other in the parietal cytoplasm of fusiform...     

Accumulation of Polyhydroxyalkanoate from Styrene and Phenylacetic Acid by Pseudomonas putida CA-3

Pseudomonas putida CA-3 is capable of converting the aromatic hydrocarbon styrene, its metabolite phenylacetic acid, and glucose into polyhydroxyalkanoate (PHA) when a limiting concentration of nitrogen (as sodium ammonium phosphate) is supplied to the growth medium. PHA accumulation occurs to a low level when the nitrogen concentration drops below 26.8 mg/liter and increases rapidly once the nitrogen is no longer detectable in the growth medium. The depletion of nitrogen and the onset of PHA accumulation coincided with a decrease in the rate of substrate utilization and biochemical activity of whole cells grown on styrene, phenylacetic acid, and glucose. However, the efficiency of carbon conversion to PHA dramatically increased once the nitrogen concentration dropped below 26.8 mg/liter in the growth medium. When supplied with 67 mg of nitrogen/liter, the carbon-to-nitrogen (C:N) ratios that result in a maximum yield of PHA (grams of PHA per gram of carbon) for styrene, phenylacetic acid, and glucose are 28:1, 21:1, and 18:1, respectively. In cells grown on styrene and phenylacetic acid, decreasing the carbon-to-nitrogen ratio below 28:1 and 21:1, respectively, by increasing the nitrogen concentration and using a fixed carbon concentration leads to lower levels of PHA per cell and lower levels of PHA per batch of cells. Increasing the carbon-to-nitrogen ratio above 28:1 and 21:1 for cells grown on styrene and phenylacetic acid, respectively, by decreasing the nitrogen concentration and using a fixed carbon concentration increases the level of PHA per cell but results in a lower level of PHA per batch of cells. Increasing the carbon and nitrogen concentrations but maintaining the carbon-to-nitrogen ratio of 28:1 and 21:1 for cells grown on styrene and phenylacetic acid, respectively, results in an increase in the total PHA per batch of cells. The maximum yields for PHA from styrene, phenylacetic acid, and glucose are 0.11, 0.17, and 0.22 g of PHA per g of carbon, respectively.     

Unique Gene Expression and MR T2 Relaxometry Patterns Define Chronic Murine Dextran Sodium Sulphate Colitis as a Model for Connective Tissue Changes in Human Crohn’s Disease

Introduction

Chronically relapsing inflammation, tissue remodeling and fibrosis are hallmarks of inflammatory bowel diseases. The aim of this study was to investigate changes in connective tissue in a chronic murine model resulting from repeated cycles of dextran sodium sulphate (DSS) ingestion, to mimic the relapsing nature of the human disease.

Materials and Methods

C57BL/6 mice were exposed to DSS in drinking water for 1 week, followed by a recovery phase of 2 weeks. This cycle of exposure was repeated for up to 3 times (9 weeks in total). Colonic inflammation, fibrosis, extracellular matrix proteins and colonic gene expression were studied. In vivo MRI T ₂ relaxometry was studied as a potential non-invasive imaging tool to evaluate bowel wall inflammation and fibrosis.

Results

Repeated cycles of DSS resulted in a relapsing and remitting disease course, which induced a chronic segmental, transmural colitis after 2 and 3 cycles of DSS with clear induction of fibrosis and remodeling of the muscular layer. Tenascin expression mirrored its expression in Crohn’s colitis. Microarray data identified a gene expression profile different in chronic colitis from that in acute colitis. Additional recovery was associated with upregulation of unique genes, in particular keratins, pointing to activation of molecular pathways for healing and repair. In vivo MRI T₂ relaxometry of the colon showed a clear shift towards higher T₂ values in the acute stage and a gradual regression of T₂ values with increasing cycles of DSS.

Conclusions

Repeated cycles of DSS exposure induce fibrosis and connective tissue changes with typical features, as occurring in Crohn’s disease. Colonic gene expression analysis revealed unique expression profiles in chronic colitis compared to acute colitis and after additional recovery, pointing to potential new targets to intervene with the induction of fibrosis. In vivo T₂ relaxometry is a promising non-invasive assessment of inflammation and fibrosis.     

Outer membrane protein gene expression traced by immunogold labelling in Rhizobium Leguminosarum bv. viciae strain 248 in Vicia sativa ssp. nigra.

During differentiation from bacterium into nitrogen fixing bacteroid, the outer membrane protein RopA decreases in density. Comparison between size increase of the rhizobia and density decrease of a RopA protein epitope after immuno-gold labelling, indicates that although ropA gene expression stops at the onset of nitrogen fixation, the amount of RopA protein probably remains the same.     

Purification and Characterization of Cystathionine (gamma)-Lyase from Lactococcus lactis subsp. cremoris SK11: Possible Role in Flavor Compound Formation during Cheese Maturation

A cystathionine (gamma)-lyase (EC 4.4.1.1) ((gamma)-CTL) was purified to homogeneity from a crude cell extract of Lactococcus lactis subsp. cremoris SK11 by a procedure including anion-exchange chromatography, hydrophobic interaction chromatography, and gel filtration chromatography. The activity of SK11 (gamma)-CTL is pyridoxal-5(prm1)-phosphate dependent, and the enzyme catalyzes the (alpha),(gamma)-elimination reaction of L-cystathionine to produce L-cysteine, (alpha)-ketobutyrate, and ammonia. The native enzyme has a molecular mass of approximately 120 to 200 kDa and apparently consists of at least six identical subunits of 20 kDa. In this respect, the SK11 enzyme clearly differs from other bacterial cystathionine lyases, which are all tetrameric proteins with identical subunits of approximately 40 kDa. In addition, the specific activity of purified SK11 (gamma)-CTL toward L-cystathionine is relatively low compared with those reported for other bacterial cystathionine lyases. The SK11 enzyme shows a broad substrate specificity. In the case of L-methionine, the action of SK11 (gamma)-CTL results in the formation of methanethiol, a volatile sulfur compound known to be required in flavor development in cheddar cheese. The (alpha),(beta)-elimination reaction of L-cysteine is also efficiently catalyzed by the enzyme, resulting in the formation of hydrogen sulfide. Although the conditions are far from optimal, cystathionine (gamma)-lyase is still active under cheddar cheese-ripening conditions, namely, pH 5.0 to 5.4 and 5% (wt/vol) NaCl. The possible role of the enzyme in cheese flavor development is discussed.     

Blood Vessel Density in De Novo Formed Adipose Tissue Is Decreased Upon Overexpression of TIMP‐1

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play a role in the development of obesity by contributing to adipogenesis, angiogenesis, and extracellular matrix degradation. We have evaluated a potential functional role of TIMP‐1, which inhibits most MMPs, in in vivo adipogenesis. Therefore, human (h) TIMP‐1 was overexpressed by injection in the tail vein of NUDE mice of an adenoviral vector 3 days before injection of 3T3‐F442A preadipocytes in the back. After 4 weeks of high‐fat diet, the de novo formed fat was analyzed. Overexpression of hTIMP‐1 had no effect on de novo formed fat pad mass. However, the blood vessel density of the fat pads from mice overexpressing hTIMP‐1 was significantly lower than in controls (587 ± 11 mm^?2 vs. 806 ± 20 mm^?2, P < 0.0001) whereas the adipocytes were somewhat larger (1,477 ± 44 µm² vs. 1,285 ± 32 µm², P = 0.03). Thus, in vivo hTIMP‐1 overexpression did not significantly affect the extent of de novo adipose tissue formation, but was associated with significantly lower blood vessel density.     

Antigens up the nose: identification of putative biomarkers for nasal tolerance induction functional studies combined with proteomics

Intranasal autoantigen delivery is the most effective means of inducing mucosal tolerance and suppression of autoimmune disease. In an effort to identify markers of the "tolerant state", we employed proteomics technology at the level of the cervical lymph node. The analysis revealed that nasal antigen administration (without adiuvant) led to modulation of various proteins among which the most prominent were haptoglobin, nonintegrin 67 kDa laminin receptor, and MRP8. The immunoregulatory haptoglobin may qualify as (bio)marker for effective immunotherapy.     

IL-17 promotes bone erosion in murine collagen-induced arthritis through loss of the receptor activator of NF-kappa B ligand/osteoprotegerin balance

IL-17 is a T cell-derived proinflammatory cytokine in experimental arthritis and is a stimulator of osteoclastogenesis in vitro. In this study, we report the effects of IL-17 overexpression (AdIL-17) in the knee joint of type II collagen-immunized mice on bone erosion and synovial receptor activator of NF-kappa B ligand (RANKL)/receptor activator of NF-kappa B/osteoprotegerin (OPG) expression. Local IL-17 promoted osteoclastic bone destruction, which was accompanied with marked tartrate-resistant acid phosphatase activity at sites of bone erosion in cortical, subchondral, and trabecular bone. Accelerated expression of RANKL and its receptor, receptor activator of NF-kappa B, was found in the synovial infiltrate and at sites of focal bone erosion, using specific immunohistochemistry. Interestingly, AdIL-17 not only enhanced RANKL expression but also strongly up-regulated the RANKL/OPG ratio in the synovium. Comparison of arthritic mice from the AdIL-17 collagen-induced arthritis group with full-blown collagen-arthritic mice having similar clinical scores for joint inflammation revealed lower RANKL/OPG ratio and tartrate-resistant acid phosphatase activity in the latter group. Interestingly, systemic OPG treatment prevented joint damage induced by local AdIL-17 gene transfer in type II collagen-immunized mice. These findings suggest T cell IL-17 to be an important inducer of RANKL expression leading to loss of the RANKL/OPG balance, stimulating osteoclastogenesis and bone erosion in arthritis.