Intragenomic variation in the internal transcribed spacer regions between 16S–23S rRNA genes among the three copies of Sinorhizobium fredii strains

The soybean-nodulating Sinorhizobium fredii strain has been reported to possess three copies of rRNA gene operons. In the present study, we investigated the diversity of the 16S–23S rDNA internal transcribed spacer (ITS) regions of S. fredii strains. Based on the sequences of the ITS regions, we divided the sequences of the S.   fredii strains into two groups, type A and type B. A dot-matrix analysis indicated that the region flanked by tRNA-Ile and tRNA-Ala is longer in type A than in type B, whereas type B sequences possess longer regions upstream of tRNA-Ile and downstream of tRNA-Ala than those of the type A sequence. Restriction fragment length polymorphism of polymerase chain reaction product (PCR-RFLP) of the ITS region in the cloned plasmids as templates could reconstruct the PCR-RFLP pattern from the total DNA as a template. The results of Southern hybridization using the insert sequence between tRNA-Ile and tRNA-Ala in type A as a probe indicated differences in the copy numbers of the type A ITS regions among the strains tested. These results indicated that S. fredii strains possess the type A and type B sequences of the ITS regions at ratios of 3:0, 2:1, 1:2 or 0:3. These S. fredii strains may be useful biological materials for the study of intraspecific variations.     

Toxicity of Uranium to Microbial Communities in Anaerobic Biofilms

Microbial processes have shown promise for the remediation of uranium and nitrate in groundwater impacted by uranium mine tailings. This study investigated the inhibitory impact of uranium(VI) towards different microbial populations in anaerobic biofilms, including methanogenic, denitrifying, and uranium-reducing microorganisms, which are commonly found at uranium bioremediation sites. Results of batch activity bioassays indicated a very distinct level of toxicity depending on the targeted microbial community. U(VI) caused severe inhibition of acetoclastic methanogenesis as indicated by a 50?% inhibiting concentration (IC₅₀) of only 0.16?mM. Denitrifying populations were also impacted by uranium, but their sensitivity depended on the electron donor utilized. Sulfur-oxidizing denitrifiers were the least affected (IC₅₀ for denitrification activity?=?0.32?mM), followed by H₂- and acetate-utilizing denitrifiers (IC₅₀ of 0.20 and 0.15?mM, respectively). In contrast, exposure to U(VI) concentrations up to 1.0?mM did not inhibit the rate of U(VI) bioreduction with H₂ as electron donor in the presence or absence of nitrate. On the contrary, a considerable increase in the uranium-reducing activity of the denitrifying and methanogenic mixed cultures was observed with increasing uranium concentrations. The results suggest that microorganisms responsible for U(V) reduction could tolerate much higher uranium concentrations compared to the other microbial populations assayed.     

Central somatostatin-somatostatin receptor 2 signaling mediates lactational suppression of luteinizing hormone release via the inhibition of glutamatergic interneurons during late lactation in rats

Reproductive function is suppressed during lactation owing to the suckling-induced suppression of the kisspeptin gene (Kiss1) expression in the arcuate nucleus (ARC) and subsequent suppression of luteinizing hormone (LH) release. Our previous study revealed that somatostatin (SST) neurons mediate suckling-induced suppression of LH release via SST receptor 2 (SSTR2) in ovariectomized lactating rats during early lactation. This study examined whether central SST-SSTR2 signaling mediates the inhibition of ARC Kiss1 expression and LH release in lactating rats during late lactation and whether the inhibition of glutamatergic neurons, stimulators of LH release, is involved in the suppression of LH release mediated by central SST-SSTR2 signaling in lactating rats. A central injection of the SSTR2 antagonist CYN154806 (CYN) significantly increased ARC Kiss1 expression in lactating rats on day 16 of lactation. Dual in situ hybridization revealed that few ARC Kiss1-positive cells co-expressed Sstr2, and some of the ARC Slc17a6 (a glutamatergic neuronal marker)-positive cells co-expressed Sstr2. Furthermore, almost all ARC Kiss1-positive cells co-expressed Grin1, a subunit of N-methyl-D-aspartate (NMDA) receptors. The numbers of Slc17a6/Sstr2 double-labeled and Slc17a6 single-labeled cells were significantly lower in lactating dams than in non-lactating rats whose pups had been removed after parturition. A central injection of an NMDA antagonist reversed the CYN-induced increase in LH release in lactating rats. Overall, these results suggest that central SST-SSTR2 signaling, at least partly, mediates the suppression of ARC Kiss1 expression and LH release by inhibiting ARC glutamatergic interneurons in lactating rats.     

Use of viable-cell ELISA for detection of monoclonal antibodies recognizing tumor-associated antigens on bovine lymphosarcoma cells

An ELISA, using viable bovine lymphosarcoma cells, was developed to detect tumor-associated antigens (TAA) expressed on lymphosarcoma cells from cows with enzootic bovine leukosis (EBL). Monoclonal antibodies (MAB) against TAA were used. Using viable-cell ELISA, MAB reacted with tumor cells from 9 cows with EBL, but not with peripheral blood lymphocytes from 10 clinically normal cows. Titers of MAB against tumor cells from 1 cow with EBL were 2,048 (direct immunofluorescence assay), 8,192 (flow cytometry), 2,048 (fixed-cell ELISA), and 16,384 (viable-cell ELISA). Viable-cell ELISA was the most sensitive method for detection of TAA. Reactivities of 7 MAB to tumor cells from cows with EBL were compared between viable-cell ELISA and a complement-dependent antibody cytotoxicity test. Of 5 MAB with no cytotoxic activity against tumor cells, 3 were reactive against tumor cells from the same cow, as determined by viable-cell ELISA, with titers ranging from 128 to 2,048.     

Lung toxicity of a vapor-grown carbon fiber in comparison with a multi-walled carbon nanotube in F344 rats

Carbon fibers have excellent physicochemical and electrical properties. Vapor-grown carbon fibers are a type of carbon fibers that have a multi-walled carbon tube structure with a high aspect ratio. The representative vapor-grown carbon fiber, VGCF^TM-H, is extremely strong and stable and has superior thermal and electrical conductivity. Because some high-aspect-ratio multi-walled carbon nanotubes (MWCNTs) have been reported to have toxic and carcinogenic effects in the lungs of rodents, we performed a 13-week lung toxicity study using VGCF^TM-H in comparison with one of MWCNTs, MWNT-7, in rats. Male and female F344 rats were intratracheally administered VGCF^TM-H at doses of 0.2, 0.4, and 0.8 mg/kg bw or MWNT-7 at doses of 0.4 and 0.8 mg/kg bw once a week for 8 weeks and then up to week 13 without treatment. The lung burden was equivalent in the VGCF^TM-H and MWNT-7 groups; however, the lung weight had increased and the inflammatory and biochemical parameters in the broncho-alveolar lavage fluid and histopathological parameters, including inflammatory cell infiltration, alveolar type II cells proliferation, alveolar fibrosis, pleural fibrosis, lung mesothelium proliferation, and diaphragm fibrosis, were milder in the VGCF^TM-H group than in the MWNT-7 group. In addition, the proliferating cell nuclear antigen (PCNA)-positive index in the visceral and pleural mesothelium was significantly higher in the MWNT-7 group than in the controls, but not in the VGCF^TM-H group. Thus, the results of this study indicate that the lung and pleural toxicities of VGCF^TM-H were less than those of MWNT-7.     

Functional supramolecular polymers

Supramolecular polymers can be random and entangled coils with the mechanical properties of plastics and elastomers, but with great capacity for processability, recycling, and self-healing due to their reversible monomer-to-polymer transitions. At the other extreme, supramolecular polymers can be formed by self-assembly among designed subunits to yield shape-persistent and highly ordered filaments. The use of strong and directional interactions among molecular subunits can achieve not only rich dynamic behavior but also high degrees of internal order that are not known in ordinary polymers. They can resemble, for example, the ordered and dynamic one-dimensional supramolecular assemblies of the cell cytoskeleton and possess useful biological and electronic functions.     

Conserved molecular components for pollen tube reception and fungal invasion

During sexual reproduction in flowering plants such as Arabidopsis, a tip-growing pollen tube (PT) is guided to the synergid cells of the female gametophyte, where it bursts and releases the two sperm. Here we show that PT reception and powdery mildew (PM) infection, which involves communication between a tip-growing hypha and a plant epidermal cell, share molecular components. NORTIA (NTA), a member of the MLO family originally discovered in the context of PM resistance, and FERONIA (FER), a receptor-like kinase, both control PT reception in synergids. Homozygous fer mutants also display PM resistance, revealing a new function for FER and suggesting that conserved components, such as FER and distinct MLO proteins, are involved in both PT reception and PM infection.     

Foraging Behavior of Alberes Cattle in a Mediterranean Forest Ecosystem

The dietary composition of the semiferal cattle population in the Alberes Natural Park in northeastern Spain was determined four times per year, from June 2002 to February 2004, by microhistological analysis of a total of 120 fecal samples. Woody species, mainly the Quercus and Erica genera, formed the bulk of the diet, reaching 89% of it in winter. However, in spring and summer, the proportion of woody and herbaceous species varied between samples, depending on the habitat where they were collected. The forest samples contained 67% woody species in summer, whereas grassland samples only contained 44%. The results showed that the Alberes cattle population grazed actively in Mediterranean forests and consumed a high proportion of the most combustible species, such as the Erica genus (39% of the epidermal fragments in winter samples). Even when grassland habitat was utilized, in spring and summer, one-third of the diet was from woody species. Some bovines, such as the Alberes cattle breed, can therefore survive year-round in a forest habitat with little forage supplementation, and the consumption of a predominantly woody diet would be expected to reduce forest fire hazards.     

Multigenerational cortical inheritance of the Rax2 protein in orienting polarity and division in yeast

Diploid yeast cells repeatedly polarize and bud from their poles, probably because of highly stable marks of unknown composition. Here, Rax2, a membrane protein, was shown to behave as such a mark. The Rax2 protein itself was inherited immutably at the cell cortex for multiple generations, and Rax2 was shown to have a half-life exceeding several generations. The persistent inheritance of cortical protein markers would provide a means to couple a cell's history to the future development of a precise morphogenetic form.