Rapid discrimination of <Emphasis Type="Italic">Porphyra tenera</Emphasis> Kjellman var. <Emphasis Type="Italic">tamatsuensis</Emphasis> Miura by PCR-RFLP

To allow to discriminate rapidly the strains of Porphyra tenera var. tamatsuensis, cultivars of which grow more vigorously than strains of P. tenera var. tenera, strains of both varieties were examined by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis using mitochondrial DNA related to the ATP synthase F0 subunit 6 (ATP6) gene. The lengths of all sequences in this region of three strains of each variety were 670 bp and had just a single nucleotide substitution. Digestion with the restriction enzyme of TaaI yielded three visible bands which appeared in the three strains of P. tenera var. tamatsuensis, whereas two bands appeared in the three strains of P. tenera var. tenera. We therefore conclude that PCR-RFLP analysis is a valuable tool for discrimination of P. tenera var. tamatsuensis among the stock of P. tenera strains used for mariculture.     

The p15gag and p12gag regions are both necessary for the pathogenicity of the murine AIDS virus.

The defective murine AIDS (MAIDS) virus has unique sequences in its p15gag and p12gag regions. To clarify whether these sequences are responsible for the development of MAIDS, we constructed recombinant viruses by replacing various regions of the gag gene of the nonpathogenic replication-competent LP-BM5 ecotropic virus with those of the MAIDS virus. Recombinants containing both unique sequences of the MAIDS virus were replication defective and induced MAIDS. However, a recombinant containing either the p15gag or p12gag region of the MAIDS virus was also replication defective but nonpathogenic in mice. A recombinant virus containing only the p30gag region of the MAIDS virus was replication competent and nonpathogenic. These results indicate that the p15gag and p12gag regions of the MAIDS virus do not function like those of replication-competent viruses and that both of the unique sequences in the p15gag and p12gag regions are required to develop MAIDS.     

Redescriptions ofGerres baconensis (Evermann & Seale, 1907),G. equulus Temminck & Schlegel, 1844 andG. oyena (Forsskål, 1775), included in the “G. oyena complex”, with notes on other related species (Perciformes: Gerreidae)

The gerreid species,Gerres baconensis (Evermann &; Seale),G. equulus Temminck &; Schlegel andG. oyena (Forsskål), were re-assessed as valid following examination of their holotypes and other specimens, and included in the “G. oyena complex”.Gerres haconensis is currently known only from Bacon, Luzon Island, Philippines and the Ogasawara (=Bonin) Islands, Japan, andG. equulus only from southern Japan (except Ryukyu Islands) and southern Korea.Gerres oyena is widely distributed in the Indo-West Pacific (in Japan, only from the Ryukyu Islands).Gerres baconensis differs from bothG. equulus andG. oyena in having higher counts of both the pored lateral line scales (39–42 vs 35–41 in the latter two species) and the lower gill raker series (8 or 9 vs. usually 7). A U-shaped premaxillary groove, formed on the dorsum of the forehead by the long ascending processes of the premaxillae, is scaleless inG. equulus andG. oyena, whereas it is fully scaled just behind the level of the posterior nostrils inG. baconensis over ca. 160 mm in standard length (SL) (partially scaled in specimens of ca. 100 mm SL).Gerres equulus differs fromG. oyena in having the posterior margin of the maxilla not extending beyond a vertical through the anterior margin of the inner dermal eye opening, shorter second dorsal and anal fin spines (means 18.5% and 8.5% of SL, respectively vs. 21.2% and 10.3% of SL), lower body depth at first anal fin spine base (27.0% vs. 29.6% of SL) and dorsomedial U-shaped groove scaleles throughout life (vs. tiny squamation anteriorly in specimens over ca. 130 mm SL). OtherGerres species of uncertain status and/or related species are discussed.     

Stimulation of prostaglandin synthesis in cultured rat synovial cells by a factor derived from polymorphonuclear leukocytes

Stimulation of synovial cell prostaglandin production by a factor obtained from casein-induced peritoneal polymorphonuclear (PMN) cells has been investigated. Both the extract and short time cultured medium of rat peritoneal PMN cells stimulate prostaglandin (PG)E2 production as well as collagenase production in the culture of rat synovial cells. PGE2 production by the cells in the presence of the PMN factor is much faster (5 to 24 hr) than collagenase production (24 hr or later, Biomedical Res. 3, 506-516, 1982). This stimulating factor is confirmed to be derived from PMN cells, based on the purification of the cells from peritoneal exudate cells by the Ficoll-Urographin method. Elution profile of the factor on gel filtration has indicated that both PGE2 and collagenase productions by synovial cells are stimulated by the same effluent fractions corresponding to molecular weights of 15,000 - 20,000 daltons and 30,000 - 40,000 daltons. These results suggest that PMN cells are involved in PG production as well as collagenase production in the inflamed tissue by stimulating connective tissue cells such as synovial cells.     

Monoamine fluorescence in the median eminence of the Japanese quail,Coturnix coturnix japonica,following medial basal hypothalamic deafferentation

Summary Monoamine fluorescence was examined in the ventral hypothalamus of the Japanese quail, Coturnix coturnix japonica after medial basal hypothalamic deafferentation. In sham-operated control birds, numerous yellow-green fluorescent fibers were observed in the median eminence and the nucleus tuberis. In the area of the paraventricular organ, a number of fluorescent fibers and cell bodies were observed. In birds with deafferented hypothalami, fluorescence disappeared both in the median eminence and the nucleus tuberis. In the area of the paraventricular organ, which was within the area of deafferentation, fluorescence of neuronal perikarya did not change, but fluorescent fibers decreased markedly in number. Disappearance of monoamine fluorescence in the median eminence and the nucleus tuberis is discussed in relation to the tanycyte absorptive function and gonadal development.Supported by Grants from the Ministry of Education to Professors T. Bando and H. Kobayashi, and a Grant from the Ford Foundation to Prof. H. Kobayashi.     

Age-dependent changes in cell proliferation and cell death in the periodontal tissue and the submandibular gland in mice: a comparison with other tissues and organs

This study investigated the age-dependent changes in the number of BrdU- and TUNEL-positive cells in murine gingival tissue and submandibular gland, and compared the findings with those in other tissues and organs. The cell proliferative activity was decreased after 20 weeks of age in epithelial cells of the gingiva, tongue, buccal mucosa and skin. A decreased cell proliferative activity was also associated with aging in the liver and kidney parenchymal cells. Meanwhile, cell death showed peculiar changes in gingival subepithelial tissue, and mucous and serous acini of the submandibular gland. An increase of TUNEL-positive cells was demonstrated in gingival subepithelial tissue after 20-week-old of age. A significant increase of TUNEL-positive cells was also found in the mucous acinar cells in the 20-week-old mice and in the serous acini after 20 weeks. The fluctuation in the number of TUNEL-positive cells in the subepithelial tissue of the skin, and BrdU- and TUNEL-positive staining ratios in the liver was smaller than that in other tissue and organs throughout life. This study may provide useful information for better understanding the influence of aging on the functional alteration that occurs in the gingival tissue and submandibular gland of the elderly.     

Interferon-gamma: a key contributor to hyperoxia-induced lung injury in mice

Hyperoxia-induced lung injury complicates the care of many critically ill patients who receive supplemental oxygen therapy. Hyperoxic injury to lung tissues is mediated by reactive oxygen species, inflammatory cell activation, and release of cytotoxic cytokines. IFN-gamma is known to be induced in lungs exposed to high concentrations of oxygen; however, its contribution to hyperoxia-induced lung injury remains unclear. To determine whether IFN-gamma contributes to hyperoxia-induced lung injury, we first used anti-mouse IFN-gamma antibody to blockade IFN-gamma activity. Administration of anti-mouse IFN-gamma antibody inhibited hyperoxia-induced increases in pulmonary alveolar permeability and neutrophil migration into lung air spaces. To confirm that IFN-gamma contributes to hyperoxic lung injury, we then simultaneously exposed IFN-gamma-deficient (IFN-gamma-/-) mice and wild-type mice to hyperoxia. In the early phase of hyperoxia, permeability changes and neutrophil migration were significantly reduced in IFN-gamma-/- mice compared with wild-type mice, although the differences in permeability changes and neutrophil migration between IFN-gamma-/- mice and wild-type mice were not significant in the late phase of hyperoxia. The concentrations of IL-12 and IL-18, two cytokines that play a role in IFN-gamma induction, significantly increased in bronchoalveolar lavage fluid after exposure to hyperoxia in both IFN-gamma-/- mice and wild-type mice, suggesting that hyperoxia initiates upstream events that result in IFN-gamma production. Although there was no significant difference in overall survival, IFN-gamma-/- mice had a better early survival rate than did the wild-type mice. Therefore, these data strongly suggest that IFN-gamma is a key molecular contributor to hyperoxia-induced lung injury.     

Molecular Monitoring and Isolation of Previously Uncultured Bacterial Strains from the Sheep Rumen

To estimate the contribution of uncultured bacterial groups to fiber degradation, we attempted to retrieve both ecological and functional information on uncultured groups in the rumen. Among previously reported uncultured bacteria, fiber-associated groups U2 and U3, belonging to the low-GC Gram-positive bacterial group, were targeted. PCR primers and fluorescence in situ hybridization (FISH) probe targeting 16S rRNA genes or rRNA were designed and used to monitor the distribution of targets. The population size of group U2 in the rumen was as high as 1.87%, while that of group U3 was only 0.03%. Strong fluorescence signals were observed from group U2 cells attached to plant fibers in the rumen. These findings indicate the ecological significance of group U2 in the rumen. We succeeded in enriching group U2 using rumen-incubated rice straw as the inoculum followed by incubation in an appropriate medium with an agent inhibitory for Gram-negative bacteria. Consequently, we successfully isolated two strains, designated B76 and R-25, belonging to group U2. Both strains were Gram-positive short rods or cocci that were 0.5 to 0.8 μm in size. Strain B76 possessed xylanase and α-l-arabinofuranosidase activity. In particular, the xylanase activity of strain B76 was higher than that of xylanolytic Butyrivibrio fibrisolvens H17c grown on cellobiose. Strain R-25 showed an α-l-arabinofuranosidase activity higher than that of strain B76. These results suggest that strains B76 and R-25 contribute to hemicellulose degradation in the rumen.Ruminants can utilize plant fiber as an energy source with the aid of a symbiotic relationship with microbes in the rumen. The rumen is a complex microbial ecosystem comprised of bacteria (10¹⁰ to 10¹¹ per ml), protozoa (10⁴ to 10⁶ per ml), and fungi (10³ to 10⁶ per ml) (8, 23, 39). Of the rumen microbes, bacteria are considered to be primarily responsible for the biological degradation of plant fiber, due to their high fibrolytic activity and large biomass in the rumen. In order to determine the mechanism of plant fiber degradation in the rumen, numerous studies have been performed on both the physiological and ecological characteristics of rumen bacteria (16, 27, 36). In particular, various aspects of bacterial attachment to feed particles have been investigated (19, 21, 25), because attachment to plant fiber is a critical step in initiating fiber degradation (20).Recent advances in molecular techniques have allowed recognition of a predominance of uncultured bacteria in the rumen (6, 24, 33). The majority (77%) of fiber-associated community members are uncultured bacteria, although 17% of cloned bacterial 16S rRNA gene sequences were classified as known fibrolytic species, such as Fibrobacter succinogenes and Butyrivibrio fibrisolvens (12). These findings clearly indicate the possibility for involvement of uncultured bacteria in ruminal fiber degradation. Through the phylogenetic analysis of fiber-associated community members, the unidentified bacterial groups were detected and designated uncultured group 2 (U2) and uncultured group 3 (U3). However, their roles in plant fiber digestion have yet to be determined.The predominance of uncultured bacteria has also been pointed out in other environments (26). Recently, new strategies for cultivation have been introduced to resolve the problem of the bacteria being unculturable. Sait et al. (28) reported that culturing with a polymeric growth substrate and longer incubation time was effective for the isolation of previously uncultured bacteria from soil. Cultivation on low-nutrient medium, using increased incubation times, with simulated natural environments or using a membrane as a solid support for growth has apparently led to improvements in bacterial cultivation (7, 31). On the other hand, the majority of rumen bacteria have yet to be isolated (10) despite great efforts toward the isolation of rumen bacterial strains over the past 50 years. Considering the ecological significance of uncultured rumen bacteria, it is important to cultivate and characterize these bacteria to fully understand the ecology of fiber digestion.In the present study, molecular monitoring tools were developed to obtain ecological information on target uncultured bacterial groups in the rumen. Previously uncultured rumen bacteria were then isolated and characterized to retrieve functional information.