Cycling of soil carbon in a Japanese red pine forest II. Changes occurring in the first year after a clear-felling

Cycling of soil carbon in the first year after a clear-felling was compared with that before the felling in a Japanese red pine forest in Hiroshima Prefecture, west Japan. The daily mean temperature at the soil surface in summer was increased after the felling in comparison to that before felling, and the water content of both the A₀ layer and the surface mineral soil was decreased due to the loss of the forest canopy. The rate of weight loss of the A₀ layer was reduced after felling. However, accumulation of the A₀ layer rapidly decreased because of the lack of litter supply to the forest floor. Low soil respiration after felling was mainly caused by the cessation of root respiration. Analysis of annual soil carbon cycling was then conducted using a compartment model. The relative decomposition rate of the A₀ layer decreased whereas that of humus and dead roots in mineral soil increased to some extent after felling. The accumulation of carbon in mineral soil, however, increased slightly due to the supply of humus from roots killed by the felling.     

Changes in the antibiotic production by co-culture of Rhizopus peka P8 and Bacillus subtilis IFO3335

The co-culture of Bacillus subtilis IFO 3335 with Rhizopus peka P8 or Rhizopus oligosporus P12 in liquid medium was found to increase production of antibiotic activity and to alter the spectrum of activity relative to the pure cultures. However, a mixed culture of Rhizopus arrhizus P7 and Rhizopus oryzae P17 did not produce antibiotic activity. The concentration, ratio, and time of addition of B. subtilis to the R. peka culture was found to influence antibiotic yields. Solid-state fermentations using mixed cultures of R. peka and B. subtilis were investigated. The growth of Escherichia coli IFO 3792 as a target bacterium was inhibited by the mixed culture. These results suggest the possibility of biopreservation of fermented foods by novel co-culture systems.     

Biochemical and ultrastructural evidence for the association of basic fibroblast growth factor with cardiac gap junctions

Basic fibroblast growth factor (bFGF) is a ubiquitous and multifunctional polypeptide that is believed to have a role in tissue repair and to act as a morphogen in embryonic development. Here, we have used immunohistochemical and biochemical methods with antibodies directed against the amino-terminal domain of bFGF, designated IS2, which recognize native and denatured bFGF, to demonstrate that in addition to its known intracellular and extracellular localization in heart, bFGF is also associated with cardiomyocyte gap junctions. In tissue sections, IS2 labeled regions of intercalated discs, producing an immunofluorescence pattern virtually indistinguishable from that obtained with antibodies against the heart gap junction protein connexin-43. By electron microscopy, gap junctions but not other regions of plasma membrane were heavily immunolabeled with this antibody. By solid phase immunoassay, bFGF was found to be more concentrated in a fraction enriched in cardiac gap junctions than in whole sarcolemmal preparations. Finally, an 18-kDa protein was recognized by several different antibodies specific for bFGF on Western blots of heart subcellular fractions enriched in gap junctions. We suggest that bFGF-like peptides are either an integral part of, or exist in close association with, cardiac gap junctions and thus may play a role in modulating gap junctional intercellular communication.     

A mobility shift detection method for DNA methylation analysis using phosphate affinity polyacrylamide gel electrophoresis

We describe a procedure for DNA methylation analysis using the bisulfite-mediated cytosine-to-uracil conversion of a target DNA followed by methylation-specific polymerase chain reaction (MSP) and phosphate affinity polyacrylamide gel electrophoresis (PAGE). The MSP was performed using a 1:1 mixture of 5′-phosphorylated methylation-specific and 5′-OH non-methylation-specific primers. The PAGE using an immobilized phosphate-binding tag molecule (i.e., a polyacrylamide-bound dizinc(II) complex, Zn²⁺-Phos-tag), which selectively captures the 5′-phosphorylated DNA fragment, enabled the mobility shift detection of the methylation-specific product as a slower migration band. Using this novel procedure, we demonstrated the detection of a methylated cytosine base in a pUC19 plasmid.     

Isolation of a novel sphingoglycolipid containing glucuronic acid and 2-hydroxy fatty acid from Flavobacterium devorans ATCC 10829

A new acidic sphingoglycolipid has been isolated from a Gram-negative, glucose-non-fermentative (obligatory aerobic) bacterium, Flavobacterium devorans ATCC 10829, by thin-layer chromatography on silica gel after mild alkaline hydrolysis of the cellular lipids. Chemical degradation studies, thin-layer chromatographic behavior, IR and mass-spectrometric analysis of the original and reduced glycolipid with LiA1H4 revealed that the lipid contained glucuronic acid, long-chain bases, and fatty acids in a molar ratio of approximately 1:1:1. The major long-chain bases were identified by gas chromatography-mass spectrometry as dihydrosphingosine (d-18 :0) and longer homologues, while the N-acyl group was exclusively 2-hydroxy myristic acid. The most probable structure of this glycolipid appeared to be a ceramide glucuronic acid (N-acyl dihydrosphingosine 1-glucuronic acid).     

SGIP1alpha is an endocytic protein that directly interacts with phospholipids and Eps15

SGIP1 has been shown to be an endophilin-interacting protein that regulates energy balance, but its function is not fully understood. Here, we identified its splicing variant of SGIP1 and named it SGIP1alpha. SGIP1alpha bound to phosphatidylserine and phosphoinositides and deformed the plasma membrane and liposomes into narrow tubules, suggesting the involvement in vesicle formation during endocytosis. SGIP1alpha furthermore bound to Eps15, an important adaptor protein of clathrin-mediated endocytic machinery. SGIP1alpha was colocalized with Eps15 and the AP-2 complex. Upon epidermal growth factor (EGF) stimulation, SGIP1alpha was colocalized with EGF at the plasma membrane, indicating the localization of SGIP1alpha at clathrin-coated pits/vesicles. SGIP1alpha overexpression reduced transferrin and EGF endocytosis. SGIP1alpha knockdown reduced transferrin endocytosis but not EGF endocytosis; this difference may be due to the presence of redundant pathways in EGF endocytosis. These results suggest that SGIP1alpha plays an essential role in clathrin-mediated endocytosis by interacting with phospholipids and Eps15.