Immunostimulatory DNA sequences influence the course of adjuvant arthritis.

Bacterial DNA is enriched in unmethylated CpG motifs that have been shown to activate the innate immune system. These immunostimulatory DNA sequences (ISS) induce inflammation when injected directly into joints. However, the role of bacterial DNA in systemic arthritis is not known. The purpose of the present experiments was to determine whether ISS contributes to the development of adjuvant arthritis in Lewis rats after intradermal injection of heat-killed Mycobacterium tuberculosis (Mtb). The results showed that Mtb DNA was necessary for maximal joint inflammation in adjuvant arthritis but could be replaced by synthetic ISS oligodeoxynucleotides. The arthritis-promoting effect of the Mtb DNA or of the ISS oligodeoxynucleotides correlated with an increased Th1 response to Mtb Ags, as measured by the production of IFN-gamma and increased production of the osteoclast differentiation factor, receptor activator of NF-kappaB ligand (RANKL). The Mtb DNA did not enter the joints but dispersed to the bone marrow and spleen before the onset of systemic joint inflammation. Thus, adjuvant arthritis is a microbial DNA-dependent disease. In this model, we postulate that massive and prolonged activation of macrophages, dendritic cells, and osteoclast precursors in the bone marrow may prime the joints for the induction of inflammatory Th1 immune responses to Mtb Ags.     

Starvation and herbivore-induced plant volatiles affect the color preferences of parasitic wasps

Using light-emitting diode spotlights, we examined the responses of Cotesia vestalis, a parasitoid of diamondback moth (DBM), Plutella xylostella larvae, with different hunger level to different chromatic cues. Naïve satiated female wasps showed no significant preference for either green, yellow, orange, or red spotlighted areas over a control area with background fluorescent light. When starved for 2 h, female wasps preferred yellow and green light over the control area, but not orange or red light. We also tested the effects of DBM-larvae-induced cabbage-plant volatiles, which attract female wasps, on wasp responses to green versus yellow light. In control experiments with no plant volatiles, starved wasps showed no color preference. However, when synthetic volatiles were present, the wasps preferred green over yellow light. We concluded that both hunger level and herbivore-induced plant volatiles were important factors affecting the response of parasitic wasps to light of different color.     

Traumatin- and Dinortraumatin-containing Galactolipids in Arabidopsis: THEIR FORMATION IN TISSUE-DISRUPTED LEAVES AS COUNTERPARTS OF GREEN LEAF VOLATILES*

Green leaf volatiles (GLVs) consisting of six-carbon aldehydes, alcohols, and their esters, are biosynthesized through the action of fatty acid hydroperoxide lyase (HPL), which uses fatty acid hydroperoxides as substrates. GLVs form immediately after disruption of plant leaf tissues by herbivore attacks and mechanical wounding and play a role in defense against attackers that attempt to invade through the wounds. The fates and the physiological significance of the counterparts of the HPL reaction, the 12/10-carbon oxoacids that are formed from 18/16-carbon fatty acid 13-/11-hydroperoxides, respectively, are largely unknown. In this study, we detected monogalactosyl diacylglycerols (MGDGs) containing the 12/10-carbon HPL products in disrupted leaf tissues of Arabidopsis, cabbage, tobacco, tomato, and common bean. They were identified as an MGDG containing 12-oxo-9-hydroxy-(E)-10-dodecenoic acid and 10-oxo-7-hydroxy-(E)-8-decenoic acid and an MGDG containing two 12-oxo-9-hydroxy-(E)-10-dodecenoic acids as their acyl groups. Analyses of Arabidopsis mutants lacking HPL indicated that these MGDGs were formed enzymatically through an active HPL reaction. Thus, our results suggested that in disrupted leaf tissues, MGDG-hydroperoxides were cleaved by HPL to form volatile six-carbon aldehydes and non-volatile 12/10-carbon aldehyde-containing galactolipids. Based on these results, we propose a novel oxylipin pathway that does not require the lipase reaction to form GLVs.     

Vestibulo-ocular reflex and gravity in fish.

An otolith organ on ground behave as a detector of both gravity and linear acceleration, and play an important role in controlling posture and eye movement for tilt of the head or translational motion. On the other hand, a gravitational acceleration ingredient to an otolith organ disappears in microgravity environment. However, linear acceleration can be received by otolith organ and produce a sensation that is different from that on Earth. It is suggested that in microgravity signal from the otolith organ may cause abnormality of posture control and eye movement. We examined function of otolith organ in goldfish revealed from analysis of eye movement induced by linear acceleration. We analyzed vertical eye movements from video images frame by frame. In normal fish, leftward lateral acceleration induced downward eye rotation in the left eye and upward eye rotation in the right eye. Acceleration from caudal to rostra1 evoked downward eye rotation in both eyes. When the direction of acceleration was shifted 15 degrees left, the responses in the left eye disappeared. These results suggested that otolith organs in each side transmitted different signals.     

Effects of Foraging Experiences on Residence Time of the Predatory Mite <Emphasis Type="BoldItalic">Neoseiulus womersleyi</Emphasis> in a Prey Patch

We investigated the effects of foraging experiences on the residence time of Neoseiulus womersleyi in a currently inhabited prey (Tetranychus urticae) patch. Satiated predators that had experienced starvation stayed longer in a current patch than those that had not experienced starvation. Satiated predators that had experienced a prey-rich patch showed approximately the same residence time in the current patch irrespective of the number of prey therein. By contrast, satiated predators that had experienced a prey-poor patch stayed longer in a current patch of high prey density than in one of low prey density. N. womersleyi appears to determine residence time in the current patch based on foraging experiences together with the quantity of prey in the current patch.     

Induction and inhibition of the Th2 phenotype spread: implications for childhood asthma

The interactions between genetic and environmental factors play a major role in the development of childhood asthma. We hypothesized that a pre-existing Th2/asthmatic response can promote Th2 responses to newly encountered Ags (i.e., phenotype spread). To test this hypothesis, we developed a mouse model in which the requirements for the induction and inhibition of phenotype spread to a clinically relevant neo-allergen (i.e., ragweed) were investigated. Our results indicate that 1) phenotype spread to the neo-allergen can be induced only within the first 8 h after a bronchial challenge with the first Ag (OVA); 2) Th2 differentiation of naive CD4(+) T cells occurs in bronchial lymph nodes; 3) trafficking of naive CD4(+) T cells to local lymph nodes and IL-4 produced by OVA-activated Th2 cells play essential roles in the differentiation of naive CD4(+) T cells to Th2 cells; and 4) suppression of the production of chemokines involved in the homing of naive CD4(+) T and Th2 cells to bronchial lymph nodes by a TLR9 agonist inhibited phenotype spread and abrogated the consequent development of experimental asthma. These findings provide a mechanistic insight into Th2 phenotype spread and offer an animal model for testing relevant immunomodulatory interventions.     

Functional dissection of two Arabidopsis PsbO proteins: PsbO1 and PsbO2

PsbO protein is an extrinsic subunit of photosystem II (PSII) and has been proposed to play a central role in stabilization of the catalytic manganese cluster. Arabidopsis thaliana has two psbO genes that express two PsbO proteins; PsbO1 and PsbO2. We reported previously that a mutant plant that lacked PsbO1 (psbo1) showed considerable growth retardation despite the presence of PsbO2 [Murakami, R., Ifuku, K., Takabayashi, A., Shikanai, T., Endo, T., and Sato, F. (2002) FEBS Lett523, 138-142]. In the present study, we characterized the functional differences between PsbO1 and PsbO2. We found that PsbO1 is the major isoform in the wild-type, and the amount of PsbO2 in psbo1 was significantly less than the total amount of PsbO in the wild-type. The amount of PsbO as well as the efficiency of PSII in psbo1 increased as the plants grew; howeVER, it neVER reached the total PsbO level observed in the wild-type, suggesting that the poor activity of PSII in psbo1 was caused by a shortage of PsbO. In addition, an in vitro reconstitution experiment using recombinant PsbOs and urea-washed PSII particles showed that oxygen evolution was better recoVERed by PsbO1 than by PsbO2. Further analysis using chimeric and mutated PsbOs suggested that the amino acid changes Val186-->Ser, Leu246-->Ile, and Val204-->Ile could explain the functional difference between the two PsbOs. Therefore we concluded that both the lower expression level and the inferior functionality of PsbO2 are responsible for the phenotype observed in psbo1.     

Microsatellite genotyping for genetic quality testing using sperm cells in the mouse.

We attempted to determine the number of sperm cells required for genotyping of one microsatellite marker. The crude genomic DNA extracted from about 760 or more sperm cells gave sufficient quantity of PCR product using a 20 microl-scale PCR. We also studied the effects of non-ionic detergents on extraction of crude sperm genomic DNA. PCR products amplified with the crude sperm genomic DNA extracted using the lysis buffer supplemented with non-ionic detergents showed much clear bands. In conclusion, our results suggest that a small part of the frozen sperm, which is less than 1/10 of the original volume (10 microl), provides sufficient quantity of template DNA for genetic quality testing.