Characterization of Erwinia sp. causing black rot of papaya (Carica papaya) first recorded in Okinawa Main Island,Japan

Since 2002, papaya black rot has been spreading over several islands of Okinawa Prefecture, Japan. To devise a prevention strategy for the disease, microbiological research on the pathogen was conducted. Twelve strains were isolated from papaya infected with black rot showing symptoms such as water-soaked lesions on stems and petioles, black spots on fruits, and rotted leaves turning yellow with necrotic spots. Through Koch's postulates, we confirmed that the isolated strains caused papaya black rot. Bacteriological assays showed that the strains have characteristics different from the type strains of Erwinia mallotivora, E. papayae, and E. psidii. Moreover, 16S rDNA sequence similarity searches showed that the isolated strains had less than 98.6% similarity with type strains. Additionally, phylogenetic analysis of 16S rDNA sequences suggested that the isolated strains were possibly a novel species belonging to the genus Erwinia, as the strains formed an independent cluster and had low sequence similarity with the type strains. Earlier studies indicated that papaya black rot is caused by E. cypripedii. Therefore, we propose to add the Erwinia sp. isolated in this study to the list of papaya black rot pathogens.     

Characterization of monoclonal antibodies against fowl adenovirus serotype 1 (FAV1) isolated from gizzard erosion

Six clones of monoclonal antibodies (Mabs) to fowl adenovirus (FAV) serotype 1 were produced. All Mabs reacted positively by enzyme-linked immunosorbent assay. Three Mabs recognized the putative 100-kD hexon protein and reacted to serotype 1 specifically by western blot analysis but did not react to other FAV serotypes (2, 3, 4, 5, 6, 7, and 8a). These Mabs will be useful for immunodiagnosis of FAV serotype 1 infection in chickens with gizzard erosion and in further research studies involving the genomes and proteins of FAV serotype 1.     

A 38-kDa protein from Babesia gibsoni and its antibody response in an experimentally infected dog

A cDNA encoding the Babesia bovis 12D3 antigen homologue was obtained by immunoscreening the expression library prepared from Babesia gibsoni merozoite mRNA. The complete nucleotide sequence of the gene was 1406 bp. Computer analysis suggested that the sequence contains an open reading frame of 1052 bp encoding an expected protein with a molecular weight of 36kDa. Based on homology analysis, this putative protein was designated as the B. gibsoni 12D3 antigen (Bg12D3). The Bg12D3 gene was expressed in the Escherichia coli BL21 strain, and the chronically infected dog serum reacted with the recombinant protein. The antiserum against the recombinant Bg12D3 protein can recognize a 38-kDa native protein, which is consistent with its expected size. Moreover, the purified recombinant proteins were used as the antigen to detect the antibody response in an experimentally infected dog by the enzyme-linked immunosorbent assay (ELISA). Our results indicated that the Bg12D3 protein was recognized by the host immune system and that it induced an antibody response in chronic B. gibsoni infection. These results allowed us to identify a new member of the 12D3 antigens and its characteristic immune response in canine B. gibsoni infection.     

Occurrence of the free and Peptide forms of pyroglutamic acid in plasma from the portal blood of rats that had ingested a wheat gluten hydrolysate containing pyroglutamyl peptides

In order to determine pyroglutamic acid levels in plasma, we developed a method based on precolumn derivatization of the carboxyl group of pyroglutamic acid with 2-nitrophenylhydrazine. Eight-week-old male SD strain rats were administered 200 mg of an acidic peptide fraction obtained from a commercial wheat gluten hydrolysate containing 0.63 mmol/g pyroglutamyl peptide. After administration, significant amounts of free pyroglutamic acid were observed in the ethanol-soluble fraction of the plasma from the portal vein. In addition, pyroglutamate aminopeptidase digestion of the ethanol-soluble fraction liberated significant amounts of pyroglutamic acid, which indicated the presence of the pyroglutamyl peptide. The presence of the pyroglutamyl peptide in the plasma was further confirmed by size exclusion chromatography. The levels of free and peptide forms of pyroglutamic acid increased significantly and reached a maximum (approximately 40 nmol/mL) at 15 and 30 min after administration, respectively.     

Development of a large-scale (50 L) apparatus for ampholyte-free isoelectric focusing (autofocusing) of peptides in enzymatic hydrolysates of food proteins

It has been demonstrated that peptides in enzymatic hydrolysates of proteins can be fractionated on the basis of the amphoteric nature of the sample peptides, by a laboratory-scale isoelectric focusing apparatus, without adding a chemically synthesized carrier ampholyte. This approach is referred to as autofocusing. In the present study, a large-scale (up to 50 L) autofocusing apparatus was developed and tested. A tank (125 cm x 25 cm x 20 cm) was divided into 12 compartments by 11 plates, each with a window covered in a thin agarose gel layer supported by a nylon screen (100 mesh). The compartments at both ends were filled with 0.1 N phosphoric acid (anode) and 0.1 N NaOH (cathode), respectively, functioning as electrode compartments. The remaining compartments were used for sample compartments. Autofocusing was carried out at constant voltage according to two different methods. In method 1, all sample compartments were filled with a 1% water solution of casein or milk whey protein hydrolysates. In method 2, two compartments located in the center of the tank were filled with 5% sample solution and the others were filled with deionized water. Compositional and sequence analyses of the autofocusing fractions revealed that peptides in the two hydrolysates can be fractionated within 24 h by the present apparatus. Better fractionation was obtained by method 2, whereas enrichment of some peptides occurred by using method 1.     

Analyses of arbutin and chlorogenic acid, the major phenolic constituents in Oriental pear

The HPLC retention time, photodiode array UV spectrum analysis, and LC/MS results indicated that arbutin and chlorogenic acid are the main phenolic constituents in Oriental pear. The two compounds exist in different organs of the Yali pear, which is one of the major cultivars of Pyrus bretschnrideri. The contents of arbutin in the leaf bud, floral bud, flower, and young fruit were 11.9, 12.4, 8.29, and 9.92 mg/g fresh weight (FW), respectively. Chlorogenic acid amounts in the same organs were 2.26, 3.22, 5.32, and 3.72 mg/g FW, respectively. During development, the concentration of the two compounds in Yali pears was the greatest in young fruit (9.92 mg/g FW of arbutin and 3.72 mg/g FW of chlorogenic acid), and then declined swiftly with fruit growth to less than 0.400 and 0.226 mg/g FW, respectively, in mature fruit. Large differences existed in the distribution of the two compounds in parts of the mature fruit of 14 Oriental pear cultivars. The greatest concentration of arbutin was found in the peel (1.20 mg/g FW), which was 3-5 times greater than that found in the core and 10-45 times greater than the level in the pulp. The concentration of chlorogenic acid in the core was greater than that in the peel. The compounds in 17 cultivars of Oriental pear, including P. bretschnrideri, Pyrus pyrifolia, Pyrus ussuriensis, and Pyrus sinkiangensis, were compared with those in 5 cultivars of Occidental pear (Pyrus communis). The mean concentration of arbutin in the Oriental pear cultivars was 0.164 mg/g FW, greater than the 0.083 mg/g FW found in the Occidental pear cultivars. The greatest arbutin content was 0.400 mg/g FW, found in the Yali pear. However, the mean concentration of chlorogenic acid in the Oriental pear was 0.163 mg/g FW, less than that found in the Occidental pear (0.309 mg/g FW).     

Epidemiological survey of Theileria parasite infection of cattle in Northeast China by allele-specific PCR

An epidemiological survey on a Theileria parasite infection of cattle in Northeast China was carried out using allele-specific PCR and DNA sequence analysis of the major piroplasm surface protein (MPSP) gene. The results showed that 14 of 104 blood samples were positive for Theileria by PCR. Among the positive cases, co-infection with various combinations of C- and I-type parasites was detected in 12 samples; no B- and Thai-type parasites were detected by allele-specific PCR. Phylogenetic analysis based on the MPSP gene sequences revealed that Theileria parasites with the MPSP types 1, 2, and 4 were distributed in Northeast China.     

Wood friction characteristics during exposure to high pressure: influence of wood/metal tool surface finishing conditions

Friction that arises during processing for the deformation of wood under relatively high pressure levels (ca. >1 MPa) is an important factor to be taken into account when wood is processed. However, few studies on such friction have been published. The present study was undertaken to evaluate the influence of surface finishing conditions on the nominal friction coefficient (μ) of the wood and metal tool surfaces. Sticking friction was likely to arise on a relatively coarse metal surface, and the type of metal tool surface finishing was found to have large impact on the friction mechanism. The friction characteristics during exposure to high pressure seem to be affected not only by the interface contact characteristics, but also by the deformation characteristics of wood during compressive load or measurement. The value of μ on water-saturated wood was equal or higher than that on dry wood, which suggests that the contact characteristics between these two types of wood are significantly different. The water content in wood was shown to affect both the interface contact and deformation characteristics of wood. The value of μ was not significantly affected by the wood surface finishing conditions; however, changes in μ during sliding differed slightly, depending on the finishing conditions.     

Enthalpy relaxation behavior of dry wood detected by temperature-modulated differential scanning calorimetry

Enthalpy relaxation of dry wood has been investigated by temperature-modulated differential scanning calorimetry. The reversing and non-reversing heat flow changes revealed that enthalpy relaxation occurred in dry wood, which did not exhibit any clear glass transitions. This enthalpy relaxation behavior seemed to differ significantly from those of previously reported isolated lignins, which implies that the microstructure of dry wood possesses a rigid amorphous state derived from interactions among wood components. The observed enthalpy relaxation is considered to be related to other components besides lignin, and the time-dependent physical properties due to unstable states or physical aging of wood originate not only from lignin but also from other components, such as cellulose and hemicellulose and the interactions between them.