Microbial community profiles in intercellular fluid of rice

Plants harbor microorganisms that are thought to stimulate plant defense systems or promote plant growth. Individual species in these intercellular microbial communities are often not sufficiently abundant to be easily described, although some endophytic microorganisms amenable to culture have been characterized. To better understand the microbial population of plants, we collected intercellular fluid (IF) from leaf blades and sheaths of rice and subsequently isolated DNA from the IF. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S and 18S rDNA fragments amplified from IF DNA by PCR indicated that these band patterns were distinguishable from those of a leaf surface-wash fluid (SF). Analysis of a set of rDNA fragments amplified from IF DNA of rice with different genotypes, paddies or growth stages for the primary survey of overall microbial community in the IF suggested that this approach is suitable for analyzing microbial diversity in the IF from various plant samples. Actually, comparative analysis of amplified rDNA fragments of rice and other five plant species indicated that the microbial diversity in IF is likely to vary substantially among plant species. We can also use sequence analysis of 16S rDNA fragments amplified from rice IF DNA to identify species including unculturable bacteria and proteobacteria and Xanthomonas and 18S rDNA fragments to identify Tilletiaria anomala, Tilletia iowensis, Ustilago maydis and unculturable eukaryotes. Thus, IF DNA analysis seems to be a good tool to further study the microbial ecology of plants.     

Effect of the d‐glucose analog,d‐allose,on the growth of Arabidopsis roots

Although d ‐glucose increased the root growth of Arabidopsis seedlings, d ‐allose (a d ‐glucose epimer at the third carbon atom) inhibited the root growth at concentrations >0.1 mmol L^?1 and the inhibition increased with increasing d ‐allose concentrations. Allitol (a reduction product of d ‐allose) did not show any significant effect on the growth. The addition of d ‐glucose into the growth medium of Arabidopsis reversed the d ‐allose‐induced growth inhibition, which suggests that the inhibition is not caused by the toxicity of the accumulation of d ‐allose and/or its metabolites in the seedlings. d ‐Allose is phosphorylated by hexokinase, using ATP and phosphate, to allose‐6‐phosphate, with no known capacity for further metabolism. The addition of phosphate into the growth medium did not affect the d ‐allose‐induced growth inhibition and d ‐allose did not reduce the ATP level in the roots. These results suggest that the inhibition is not due to phosphate starvation and ATP depletion. d ‐Mannoheptulose, a specific competitive inhibitor of hexokinase, defeated the d ‐allose‐induced growth inhibition. Hexokinase is known to have a sugar‐sensing function and possibly triggers a signal cascade, resulting in the change of several gene expressions. Therefore, the phosphorylation of d ‐allose by hexokinase might trigger a signal cascade, resulting in the inhibition of Arabidopsis root growth. This is probably a useful model system for studies of the hexokinase‐mediated sugar‐sensing function and for developing new types of weed‐control agents.     

In vitro production of porcine embryos: current status,future perspectives and alternative applications

The pig is considered to be a suitable source of cells and organs for xenotransplants, as well as a transgenic animal to produce specific proteins, given the biological similarities it shares with human beings. However, the in vitro embryo production system in pigs is inefficient compared with those in other mammals, such as cattle or mice. Although numerous modifications have been applied to improve the efficiency of in vitro embryo production systems in pigs, not much progress has been made to overcome the problem of polyspermy, and low developmental ability due to insufficient cytoplasmic abilities of in vitro matured oocytes and improper culture conditions for the in vitro produced embryos. Recent achievements, such as the establishment of chemically defined medium and utilization of ‘zona hardening’ technique, have gained some success. However, further research for the reduction of polyspermy and detrimental effects of the culture systems in pigs is still needed.     

Expressions of protein oxidation markers, dityrosine and advanced oxidation protein products in Cisplatin-induced nephrotoxicity in rats

The purpose of this study was to evaluate whether dityrosine and advanced oxidation protein products (AOPP) reflect the severity of cisplatin-induced nephrotoxicity. Immunoexpression of dityrosine in kidneys and plasma AOPP concentration were examined up to day 4 post-cisplatin injection in rats. Cisplatin injection induced tubular injury on days 2-4 after injection and increased serum creatinine and BUN on days 3 and 4. On days 2-4, dityrosine was immunostained in the cytoplasm of damaged tubular cells, and their immunostaining intensity increased time-dependently. Plasma AOPP levels were significantly increased on days 3 and 4. These results suggest that expressions of dityrosine and AOPP were associated with the severity of renal injury and may be useful markers for the development of cisplatin-induced nephrotoxicity.     

Assisted hatching of poor-quality bovine embryos increases pregnancy success rate after embryo transfer

Embryos of good, fair and poor quality were collected from superovulated cows and subjected to zona cutting (ZC) treatment using a needle under either an inverted microscope or a stereomicroscope. One (single transfer) or 2 (twin transfer) embryos with or without prior ZC treatment were transferred nonsurgically to recipients. Without the ZC treatment, lower embryonic quality resulted in lower pregnancy success rates. However, the ZC treatment increased the pregnancy success rate following transfer of poor-quality embryos, but not the pregnancy rate after transfer of good- or fair-quality embryos. No differences were observed between the pregnancy success rates after the transfer of embryos treated under the inverted microscope and those after transfer of embryos treated under the stereomicroscope, and this was the same after single and twin transfer. Moreover, ZC treatment of embryos prior to transfer did not result in an increased abortion rate, irrespective of the number of transferred embryos. In conclusion, ZC treatment improves pregnancy success rates following transfer of poor-quality embryos. Moreover, the results indicate that ZC treatment by using a stereomicroscope is practical for on-farm application.     

Effect of bovine lactoferrin feeding on lipopolysaccharide-induced metabolic and hormonal disturbances in preruminant calves

One of the biological functions of bovine lactoferrin (LF) is modulation of the host defense system, including cytokine production and immune response. The aim of the present study was to investigate the effect of oral administration of LF in calves on lipopolysaccharide (LPS)‐induced metabolic and hormonal changes in inflammatory response. Thirty Holstein calves at 4 day of age were given one of three oral doses of LF (0, 1, 3 g/day) for 10 days (?10 day to ?1 day). They were injected i.v. with LPS (50 ng/kg bodyweight) the day (day 0) after the end of LF treatment. Plasma samples were obtained on ?10, 0 day (immediately before LPS injection), and at 2, 6, 12, 24, 48, 72, and 96 h after LPS injection. Plasma tumor necrosis factor‐α concentrations at 2 h after LPS treatment were lower (P < 0.05) in LF 1 g/day‐fed claves compared with LF 0 g/day (control) calves. On day 0 there were no significant group differences in plasma LF concentration. Plasma concentration of haptoglobin in control calves was elevated by LPS injection. In LF groups, plasma haptoglobin concentrations slightly increased after LPS injection, but those levels at 6–24 h were lower (P < 0.05) than in the control group. The LF treatment inhibited (P < 0.05) the reduction of plasma ferrin concentration in calves following LPS challenge. The concentration of plasma aspartate aminotransferase in calves treated with LF was lower (P < 0.05) than in control calves at 24–96 h after LPS treatment. The concentration of plasma insulin‐like growth factor‐1 (IGF‐1) in all groups was decreased by LPS treatment, while in the LF groups the IGF‐1 level was higher (P < 0.05) than in the control group. Plasma adrenocorticotropic hormone and insulin concentrations in LF groups were lower (P < 0.05) than in control calves at 2 h after LPS injection. These data suggest that LF has a substantial anti‐inflammatory effect on the modulation of the host defense system in preruminant calves.     

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.     

Effect of the Fukushima Daiichi nuclear power plant accident on radiocesium distribution in tea fields in Saitama Prefecture: Intercultivar differences

We investigated radiocesium distribution in tea plants (Camellia sinensis L. var. sinensis) of Saitama Prefecture, located approximately 200–250 km away from Tokyo Electric Power Company’s Fukushima Daiichi nuclear power plant. In 2012, more than 2500 samples of tea plants were analyzed. We found differences in radiocesium concentration among tea plant cultivars, which appeared to be attributable mainly to the leaf morphology and depth of the leaf layer in tea plants. Furthermore, the radiocesium concentration in the first tea crop showed a strong correlation with that in spring skiffing.     

Characteristics of nutrient load in a stream flowing through a livestock farm during spring snowmelt

We investigated the stream water quality during the snowmelt period in a livestock farm, located in Shizunai, southern Hokkaido, Japan. The water quality was very different between the early stage of the snowmelt period (March 15–21) and the later stage (March 22–April 5) in 2001. The load of nutrients (NH₄ ⁺-N, T-P, K⁺) was large along with the increase of the flow rate and nutrient concentrations during the early stage of the snowmelt period. The molar ratios of Si / T-N and Si / T-P of the stream water, as an index of eutrophication, were also under the threshold values (2.7, 64.3, respectively) during the early stage of the snowmelt period. In addition, the relationship between the Si and nutrient concentrations (NH₄ ⁺-N, T-P, K⁺) showed a significantly negative correlation (R ² = 0.65), which indicated that the amount of nutrient load might be derived from surface runoff. Consequently both the quantity and quality of the stream water during snowmelt may exert an adverse effect on coastal waters, leading to eutrophication. Furthermore, since the main effluent source appeared to be surface runoff at the early stage of the snowmelt period, attention should be paid to land management before and during the snow covering period.