Homolog of FlhDC, a master regulator for flagellum synthesis: required for pathogenicity in Erwinia carotovora subsp. carotovora

 Erwinia carotovora subsp. carotovora (Ecc) is a causal agent of soft-rot diseases in a wide variety of plants. Here, we have isolated nonmotile mutants in Ecc by in vivo insertional mutagenesis using a transposon Tn5. The sequence disrupted by the Tn5 insertion in YMU1 and YMU5 mutants was highly homologous to that of flhC and flhD genes, respectively. They are involved in the initiation of the expression of flagellum-related genes in many gram-negative bacteria such as Escherichia coli and Salmonella. With electron microscopy, the flhC and the flhD homolog mutants were shown to be aflagellate. Furthermore, the virulence of these mutants was greatly reduced in Chinese cabbage and potato compared to that of the parental strain. These results suggest that flagellar formation is required for the pathogenicity of Ecc. Received: November 5, 2002 / Accepted: December 2, 2002 Acknowledgments This research was supported in part by Grant-in-Aid (12052210) and by a grant from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (13073).     

A canine case of skull base meningioma treated with hydroxyurea

An 11-year-old female miniature schnauzer was tentatively diagnosed with the skull base meningioma, based on several examinations. Because surgical treatment was difficult, and outpatient radiation therapy was not available in the local area, chemotherapy with hydroxyurea combined with dexamethasone was selected. The patient's clinical symptoms improved after one week of treatment, and the tumor size was obviously reduced on MRI performed 37 days after treatment began. The patient received hydroxyurea for 7 months, with symptoms remaining stable, and the tumor re-increased to almost the same size at 7 months as that at the initial examination. At that time, hydroxyurea was discontinued. The patient died from pulmonary edema 14 months after treatment began. Pathologically, the tumor was diagnosed as a meningioma.     

Effects of 3-methyl-4-nitrophenol in diesel exhaust particles on the regulation of reproductive function in immature female Japanese quail (Coturnix japonica)

In a previous study, we found that 3-methyl-4-nitrophenol (PNMC), a component of diesel exhaust particles and also a degradation product of the insecticide fenitrothion, exhibits reproductive toxicity in the adult male Japanese quail. The present study investigated the toxicity of PNMC in the female Japanese quail and its ability to influence reproduction in immature females. The quail (21-day-old) were injected intramuscularly (im) with PNMC at doses 0.1, 1 or 10 mg/kg body weight daily for 3 days. There was no significant difference in body growth between the PNMC-administered and control birds. However, the weights of the oviducts were significantly lower in the PNMC-treated birds at all doses. Furthermore, the plasma concentrations of luteinizing hormone (LH) and estradiol-17 beta were significantly decreased with 1 and 10 mg/kg of PNMC. These findings suggest that PNMC might influence the hypothalamo-pituitary-gonadal axis with decreasing in secretion of GnRH, LH and ovarian steroid hormones and subsequently disturb growth of the reproductive organs of immature female quail. This study indicates that PNMC induces reproductive toxicity at the central level and disrupts reproductive function in the immature female quail.     

The influence of barley malt protein modification on beer foam stability and their relationship to the barley dimeric alpha-amylase inhibitor-I (BDAI-I) as a possible foam-promoting protein

The foam stability of beer is one of the important key factors in evaluating the quality of beer. The purpose of this study was to investigate the relationship between the level of malt modification (degradation of protein, starch, and so on) and the beer foam stability. This was achieved by examining foam-promoting proteins using two-dimensional gel electrophoresis (2DE). We found that the foam stability of beer samples brewed from the barley malts of cultivars B and C decreased as the level of malt modification increased; however, the foam stability of cultivar A did not change. To identify the property providing the increased foam stability of cultivar A, we analyzed beer proteins using 2DE. We analyzed three fractions that could contain beer foam-promoting proteins, namely, beer whole proteins, salt-precipitated proteins, and the proteins concentrated from beer foam. As a result, we found that in cultivar A, some protein spots did not change in any of these three protein fractions even when the level of malt modification increased, although the corresponding protein spots in cultivars B and C decreased. We analyzed these protein spots by peptide mass finger printing using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. As a result, all of these spots were identified as barley dimeric alpha-amylase inhibitor-I (BDAI-I). These results suggest that BDAI-I is an important contributor to beer foam stability.     

Fine structure and differentiation of the alimentary canal in captive-bred Japanese eel Anguilla japonica preleptocephali

ABSTRACT:   The fine structure of the alimentary canal in preleptocephali produced by artificially matured Japanese eel was examined. At 1 day posthatch (dph), the alimentary canal was found only above the dorsal side of the yolk mass, and the epithelium was composed of a single layer of epithelial cells. By 5 dph, the alimentary canal was divided into three segments based on the structure of the epithelial cells: foregut, midgut and hindgut, corresponding to the future esophagus, intestine and rectum, respectively. After 7 dph, the epithelium in the foregut was surrounded by a circular muscle layer, suggesting a role in the transportation of food materials. The epithelial cells of the midgut exhibited well-developed membranous structures, which are deduced to be invaginations of the cytoplasmic membrane. Pinocytotic invaginations and vacuoles were observed in the epithelial cells of the hindgut; this observation suggests that this region is involved in the uptake of food. Significant changes in morphological features of the epithelial cells in each segment were observed until 7 dph; however, these were not evident between 7 dph and 13 dph. Consequently, the differentiation of the alimentary canal was completed by 7 dph, and preleptocephalus had developed the ability to absorb food by 7 dph.     

Gonadal morphogenesis and sex differentiation in cultured chub mackerel,Scomber japonicus

The timing of primordial germ‐cell (PGC) migration with regard to the gonadal anlagen, gonad formation and sex differentiation was examined histologically in the chub mackerel (Scomber japonicus) at 5–190 days post hatching (dph). At 5 dph, PGCs appeared on the peritoneal epithelium surface or in the mesentery, on the dorsal side of the abdominal cavity. By 10 dph, stromal cells around the PGCs proliferated. The gonadal primordium was formed by 15 dph. The gonadosomatic index was 0.01% at 30 dph and increased thereafter (0.32% in females and 0.04% in males at 160 dph). Ovarian differentiation occurred at 30–40 dph, indicated by ovarian cavity formation (elongation and fusion of the upper and lower ovarian edges). Meiosis was subsequently initiated. A few meiotic oocytes surrounded the cavity at 50 dph; most were in the perinucleolus stage at 60 dph and attained a diameter of 60–70 μm at 190 dph. Testicular differentiation occurred at 30 dph, indicated by the formation of the sperm duct primordium. Spermatogonia gradually proliferated, developing into spermatocytes at the chromatin–nucleolus stage (after 90 dph) and subsequently into spermatids and spermatozoa (160 dph). These data could aid the development of seeding and cell‐engineering technologies for scombrid fish.     

Development of an in vitro culture system for producing eel larvae from immature ovarian follicles in Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis>

To standardize conditions during the final maturation and ovulation of ovarian follicles from Japanese eel, we have developed a culture system for the production of fertilizable eggs from post-vitellogenic ovarian follicles in vitro. Post-vitellogenic ovarian follicles were incubated in culture medium supplemented with 17α,20β-dihydroxy-4-pregnen-3-one (DHP) with or without bovine serum albumin (BSA) to assess the effects of protein concentration. Eggs that ovulated during incubation were fertilized, and the remaining follicles were incubated in prostaglandin F_2α (PGF_2α) for a further 3 or 6 h before fertilization. Male eels were injected repeatedly with human chorionic gonadotropin. The quality of eggs obtained under the different culture conditions was evaluated after artificial fertilization in terms of hatching success. Hatching rates tended to decrease with increasing concentrations of BSA in the incubation medium in a dose-dependent manner. The addition of PGF_2α drastically increased the number of eggs that ovulated, but the rate of hatching was greatly decreased compared with eggs obtained earlier by DHP incubation alone. The larvae obtained from artificially fertilized eggs produced in vitro survived for 14 days without feeding. We conclude that in vitro culture systems thus have a great potential for the acquisition of good quality eggs under tightly controlled artificial conditions, culminating in the production of eel larvae.     

Studies on red light-induced resistance of broad bean to Botrytis cinerea: I. Possible production of suppressor and elicitor by germinating spores of pathogen

When detached broad bean leaves were preinoculated with virulent strain B304 of Botrytis cinerea 24 h before a challenge inoculation with strain B304, lesion formation by B304 was significantly inhibited in red light but not in the dark. In leaves that were preinoculated with avirulent strain 021 and then challenged by B304, however, lesion formation was not inhibited even under red light. Such differences in lesion formation after the challenge inoculation with an avirulent strain were also observed with lesions caused by Alternaria alternata, a nonpathogen of broad bean and by avirulent strain 021R in the presence of germination fluid from spores of strains B304 and 021R. These results suggest the possibility that virulent B. cinerea produced a suppressor involved in induced susceptibility and an elicitor involved in resistance induced by red light during spore germination.     

Allele frequencies of the extension locus encoding the melanocortin-1 receptor in Japanese and Korean cattle

In order to estimate the influence of the Extension (E) locus in cattle coat color, the melanocortin‐1 receptor (MC1R) gene in Japanese Black, Japanese Brown and Korean (Hanwoo) cattle were sequenced. The sequences of the coding region revealed three alleles (E^D, E⁺ and e), which were previously reported. Polymerase chain reaction‐restriction fragment length polymorphism was performed to investigate the gene frequencies of the three breeds. Japanese Black was almost composed of E^D and E⁺ individuals, E^D = 0.481 and E⁺ = 0.514, and no homozygous e/e, therefore that is consistent with the hypothesis that E^D and E⁺ induce black pigment synthesis. Allele frequencies between Japanese Brown and Hanwoo were obviously different; however, recessive red e allele frequency was 0.038 for Japanese Brown and 0.948 for Hanwoo, even though both breeds have quite similar coat colors (ranging from yellowish brown to dark brown including a red coat color). This result suggested that other genes are also associated with a coat color of red and brown in cattle.