Germination stimulatory activity of bacterial butenolide hormones from Streptomyces albus J1074 on seeds of the root parasitic weed Orobanche minor

Damage caused by Orobanchaceae root parasitic weeds is a substantial agricultural problem for global food security. Many studies have been conducted to establish practical methods of control, but efforts are still required for successful management. Seed germination of root parasitic weeds requires host-derived germination stimulants including strigolactones (SLs). Studies on SLs have revealed that a butenolide ring is the essential moiety for SL activity as a germination stimulant. Interestingly, recent studies have revealed that butenolide hormones regulate the biosynthesis of secondary metabolites and mediate communication in actinomycete bacteria. Because of the structural similarity between SLs and the bacterial butenolides, we evaluated the germination stimulatory activity of butenolides isolated from Streptomyces albus J1074 on root parasitic weeds. These butenolides were found to specifically induce seed germination of Orobanche minor. Our findings contribute to understanding the molecular mechanisms of germination stimulant perception and to the development of a method for their biological control.     

Isolation and partial characterization of endophytic diazotrophs associated with Japanese sugarcane cultivar

Endophytic bacteria were isolated from the juice of a 6 month-old sugarcane cv. NiF-8, which was collected from Miyako, Okinawa and planted in a field lysimeter in Tsukuba, Ibaraki, Japan. The most probable number of N₂-fixing endophytes was 4.5 × 10⁵ cells per gram of fresh weight sample and 21 isolates have a positive reaction for ARA in an N₂-free semi-solid medium with 10% crystallized sugarcane sugar and 0.5% sugarcane juice. Analyses of some of the biochemical properties of the N₂-fixing isolates indicated that 13 isolates were putative strains of Acetobacter diazotrophicus, 4 isolates showed similar characteristics to those of Herbaspirillum seropedicae, and 4 isolates consisted of Herbaspirillum rubribalbicans-like strains. This study confirmed the existence of N₂-fixing endophytic bacteria in the Japanese sugarcane cv. NiF-8.     

Heterologous expression of gassericin A,a bacteriocin produced by Lactobacillus gasseri LA39

Gassericin A, a bacteriocin produced by Lactobacillus gasseri LA39, has a cyclic structure linking N‐ and C‐terminal amino acids. Gassericin A was expressed in Escherichia coli JM109 as a biotinylated fusion protein on the basis of the DNA sequence of mature bacteriocin. A positive clone accumulated the bacteriocin, with no activity, as a soluble fusion protein in the cytoplasm. After release of an N‐terminal tag with factor Xa protease, gassericin A was converted into an active peptide having N‐ and C‐termini. The total amount of purified bacteriocins (expressed and native) was 480 µg/L and 370 µg/L, respectively. However, the specific activity of expressed gassericin A was 15 AU/mg lower than that of native bacteriocin (2600 AU/mg). Although the actual Mr (molecular weight) of the expressed bacteriocin should be 5666, the peptide showed the same mobility (Mr 3800) in sodium dodecylsulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) as native cyclic gassericin A, suggesting that the expressed peptide retains compact folding of the molecule similar to that of native gassericin A.     

Metallothionein expression and tumor growth in the transplantable pregnancy-independent mouse mammary tumor.

In various human tumors, a metal binding protein, metallothionein (MT) is reported to play an important role in carcinogenesis. In the present preliminary study, MT expression and tumor growth were investigated in transplantable pregnancy-independent mammary tumors (TPIMT) derived from pregnancy-independent mammary tumors (PIMT) in GR/A mice, in order to study the possible role of MT in mammary carcinogenesis. TPIMT as well as PIMT showed MT expression in tumor cells in all of the successive transplantations. A negative correlation was observed between MT expression in transplanted tumor tissues and their growth in the hosts (r=-0.53, p<0.05). The present study indicates that MT is a useful marker of tumor progression in TPIMT.     

Diversity and fluctuation in ciliate protozoan population in the rumen of cattle

The purpose of this study was to investigate the diversity and fluctuation in the ciliate protozoan population in the rumen of cattle. DNA was extracted from the rumen of three ruminally cannulated, crossbred cattle and a polymerase chain reaction (PCR)‐derived clone library was constructed, using a specific primer set targeting 18S ribosomal RNA genes of ciliate protozoa. DNA fragments of seven selected clones were validated for standard DNA of the protozoa‐specific real‐time PCR assay. Furthermore, population fluctuation of ciliate protozoa and methanogens in the cattle rumen was determined by real‐time PCR. A total of 60 clones were sequenced, phylogenetically analyzed, and classified into 24 operational taxonomic units (OTUs) based on a 99% similarity criterion. More than 80% sequences were phylogenetically placed in the genus Entodinium. The rest of the sequences were placed in the genus Diploplastron (5%), Dasytricha (8.3%) and Isotricha (3.3%). The results suggest that Entodinium was the dominant group in the rumen of cattle used in this study. The ciliate protozoan population showed no significant change in numbers during the monitoring period and reached a peak at 3 h after feeding. Changes in the protozoa population were lower than those of the methanogens.     

Deviations of kerf by handsaws III: the bend of saw blade by unsymmetrical set

To clarify the inducing mechanism of kerf deviation caused by unsymmetrical set of the handsaw, we hypothesized that the moment on the bottom edge of the saw blade, which is generated by the unsymmetrical set on handsaw teeth, bends the saw blade and this deformation should be one factor of the kerf deviation. To verify this hypothesis, the bend of a saw blade was examined by experiment and by calculation. In the experiments, a model tooth was attached to an actual handsaw. In the calculations, a saw model with a rectangular prism as the model tooth was analyzed by the finite element method. Loads were applied on the model tooth or the rectangular prism. From both the experiments and the calculations, the following results were obtained: (1) the deformation of the handsaw was caused by the unsymmetrical set in the length direction and the height direction of the saw blade; (2) the deformation and the inclination of the blade was larger at the front part of the saw than at the butt part; and (3) comparing the saw handle fixing conditions, the kerf deviation in the sawing line was supposed to be larger in the free handle condition and that kerf deviation in the depth direction was larger in the fixed handle condition. Based on the above results, it is apparent that one of the kerf deviation mechanisms originated from unsymmetrical set on the saw teeth. Part of this report was presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, Japan, August 2004.     

Quantitative Contrast‐enhanced Ultrasonographic Assessment of Naturally Occurring Pancreatitis in Dogs

Background

Quantitative contrast‐enhanced ultrasonography (CEUS) can detect pancreatic perfusion changes in experimentally induced canine pancreatitis. However, its usefulness in detecting perfusion changes in naturally occurring pancreatitis is unclear.

Hypothesis/Objectives

To determine the feasibility of using CEUS to detect pancreatic and duodenal perfusion changes in naturally occurring canine pancreatitis.

Animals

Twenty‐three client‐owned dogs with pancreatitis, 12 healthy control dogs.

Methods

Dogs diagnosed with pancreatitis were prospectively included. CEUS of the pancreas and duodenum were performed. Time‐intensity curves were created from regions of interest in the pancreas and duodenum. Five perfusion parameters were obtained for statistical analyses: time to initial up‐slope, peak time (Tp), time to wash‐out (TTW), peak intensity (PI), and area under the curve (AUC).

Results

For the pancreas, Tp of the pancreatitis group was prolonged when compared to controls (62 ± 11 seconds versus 39 ± 13 seconds; P < .001). TTW also was prolonged but not significantly (268 ± 69 seconds versus 228 ± 47 seconds; P = .47). PI and AUC were increased when compared to controls (95 ± 15 versus 78 ± 13 MPV; P = .009 and 14,900 ± 3,400 versus 11,000 ± 2,800 MPV*s; P = .013, respectively). For the duodenum, PI and AUC were significantly increased in the pancreatitis group when compared to controls.

Conclusions and Clinical Importance

Contrast‐enhanced ultrasonography can detect pancreatic perfusion changes in naturally occurring canine pancreatitis characterized by delayed peak with prolonged hyperechoic enhancement of the pancreas on CEUS. Additionally, duodenal perfusion changes secondary to pancreatitis were observed.