Dietary folic Acid promotes survival of foxp3+ regulatory T cells in the colon

Dietary compounds as well as commensal microbiota contribute to the generation of a unique gut environment. In this study, we report that dietary folic acid (FA) is required for the maintenance of Foxp3(+) regulatory T cells (Tregs) in the colon. Deficiency of FA in the diet resulted in marked reduction of Foxp3(+) Tregs selectively in the colon. Blockade of folate receptor 4 and treatment with methotrexate, which inhibits folate metabolic pathways, decreased colonic Foxp3(+) Tregs. Compared with splenic Tregs, colonic Tregs were more activated to proliferate vigorously and were highly sensitive to apoptosis. In colonic Tregs derived from mice fed with a FA-deficient diet, expression of anti-apoptotic molecules Bcl-2 and Bcl-xL was severely decreased. A general reduction of peripheral Tregs was induced by a neutralizing Ab against IL-2, but a further decrease by additional FA deficiency was observed exclusively in the colon. Mice fed with an FA-deficient diet exhibited higher susceptibility to intestinal inflammation. These findings reveal the previously unappreciated role of dietary FA in promotion of survival of Foxp3(+) Tregs that are in a highly activated state in the colon.     

Potent antimycobacterial activity of mouse secretory leukocyte protease inhibitor

Secretory leukocyte protease inhibitor (SLPI) has multiple functions, including inhibition of protease activity, microbial growth, and inflammatory responses. In this study, we demonstrate that mouse SLPI is critically involved in innate host defense against pulmonary mycobacterial infection. During the early phase of respiratory infection with Mycobacterium bovis bacillus Calmette-Guérin, SLPI was produced by bronchial and alveolar epithelial cells, as well as alveolar macrophages, and secreted into the alveolar space. Recombinant mouse SLPI effectively inhibited in vitro growth of bacillus Calmette-Guérin and Mycobacterium tuberculosis through disruption of the mycobacterial cell wall structure. Each of the two whey acidic protein domains in SLPI was sufficient for inhibiting mycobacterial growth. Cationic residues within the whey acidic protein domains of SLPI were essential for disruption of mycobacterial cell walls. Mice lacking SLPI were highly susceptible to pulmonary infection with M. tuberculosis. Thus, mouse SLPI is an essential component of innate host defense against mycobacteria at the respiratory mucosal surface.     

Microsatellite diversity and crossover regions within homozygous and heterozygous SLA haplotypes of different pig breeds

Our aim was to investigate microsatellite (MS) diversity and find crossover regions at 42 polymorphic MS loci in the swine leukocyte antigen (SLA) genomic region of 72 pigs with different well-defined homozygous and heterozygous SLA haplotypes. We analyzed the genetic polymorphisms of 42 MS markers in 23 SLA homozygous-heterozygous, common pig breeds with 12 SLA serological haplotypes and 49 National Institutes of Health (NIH) and Clawn homozygous-heterozygous miniature pigs with nine SLA serological or genotyped haplotypes including four recombinant haplotypes. In comparing the same and different haplotypes, both haplospecific patterns and allelic variations were observed at the MS loci. Some of the shared haplotype blocks extended over 2 Mb suggesting the existence of strong linkage disequilibrium (LD) in the entire SLA region. Crossover regions were easily defined by the MS markers within the class I and/or III region in the NIH and Clawn recombinant haplotypes. The present haplotype comparison shows that our set of MS markers provides a fast and cost-efficient alternative, or complementary, method to the serological or sequence-based determination of the SLA alleles for the characterization of SLA haplotypes and/or the crossover regions between different haplotypes.     

Presence of aquaporin and V-ATPase on the contractile vacuole of Amoeba proteus.

BACKGROUND INFORMATION: The results of water permeability measurements suggest the presence of an AQP (aquaporin) in the membrane of the CV (contractile vacuole) in Amoeba proteus [Nishihara, Shimmen and Sonobe (2004) Cell Struct. Funct. 29, 85-90]. RESULTS: In the present study, we cloned an AQP gene from A. proteus [ApAQP (A. proteus AQP)] that encodes a 295-amino-acid protein. The protein has six putative TMs (transmembrane domains) and two NPA (Asn-Pro-Ala) motifs, which are conserved among various AQPs and are thought to be involved in the formation of water channels that span the lipid bilayer. Using Xenopus oocytes, we have demonstrated that the ApAQP protein product can function as a water channel. Immunofluorescence microscopy with anti-ApAQP antibody revealed that ApAQP is detected on the CV membrane and on the vesicles around the CV. The presence of V-ATPase (vacuolar H+-ATPase) on the vesicle membrane around the CV was also detected. CONCLUSIONS: Our data on ApAQP allow us to provide the first informed explanation of the high water permeability of the CV membrane in amoeba. Moreover, the results suggest that vesicles possessing V-ATPase are involved in generating an osmotic gradient. Based on our findings, we propose a new hypothesis for the mechanism of CV function.     

Presence of aquaporin and V-ATPase on the contractile vacuole of Amoeba proteus

Background information. The results of water permeability measurements suggest the presence of an AQP (aquaporin) in the membrane of the CV (contractile vacuole) in Amoeba proteus [Nishihara, Shimmen and Sonobe ( 2004 ) Cell Struct. Funct. 29 , 85–90]. Results. In the present study, we cloned an AQP gene from A. proteus [ApAQP (A. proteus AQP)] that encodes a 295‐amino‐acid protein. The protein has six putative TMs (transmembrane domains) and two NPA (Asn‐Pro‐Ala) motifs, which are conserved among various AQPs and are thought to be involved in the formation of water channels that span the lipid bilayer. Using Xenopus oocytes, we have demonstrated that the ApAQP protein product can function as a water channel. Immunofluorescence microscopy with anti‐ApAQP antibody revealed that ApAQP is detected on the CV membrane and on the vesicles around the CV. The presence of V‐ATPase (vacuolar H⁺‐ATPase) on the vesicle membrane around the CV was also detected. Conclusions. Our data on ApAQP allow us to provide the first informed explanation of the high water permeability of the CV membrane in amoeba. Moreover, the results suggest that vesicles possessing V‐ATPase are involved in generating an osmotic gradient. Based on our findings, we propose a new hypothesis for the mechanism of CV function.     

A Theoretical Model of Jigsaw-Puzzle Pattern Formation by Plant Leaf Epidermal Cells

Plant leaf epidermal cells exhibit a jigsaw puzzle–like pattern that is generated by interdigitation of the cell wall during leaf development. The contribution of two ROP GTPases, ROP2 and ROP6, to the cytoskeletal dynamics that regulate epidermal cell wall interdigitation has already been examined; however, how interactions between these molecules result in pattern formation remains to be elucidated. Here, we propose a simple interface equation model that incorporates both the cell wall remodeling activity of ROP GTPases and the diffusible signaling molecules by which they are regulated. This model successfully reproduces pattern formation observed in vivo, and explains the counterintuitive experimental results of decreased cellulose production and increased thickness. Our model also reproduces the dynamics of three-way cell wall junctions. Therefore, this model provides a possible mechanism for cell wall interdigitation formation in vivo.     

Repetitive sequences: cause for variation in genome size and chromosome morphology in the genus Oryza

Large variation in genome size as determined by the nuclear DNA content and the mitotic chromosome size among diploid rice species is revealed using flow cytometry and image analyses. Both the total chromosomal length (r_0.939) and the total chromosomal area (r_0.927) correlated well with the nuclear DNA content. Among all the species examined, Oryza australiensis (E genome) and O. brachyantha (F genome), respectively, were the largest and smallest in genome size. O. sativa (A genome) involving all the cultivated species showed the intermediate genome size between them. The distribution patterns of genome-specific repetitive DNA sequences were physically determined using fluorescence in situ hybridization (FISH). O. brachyantha had limited sites of the repetitive DNA sequences specific to the F genome. O. australiensis showed overall amplification of genome-specific DNA sequences throughout the chromosomes. The amplification of the repetitive DNA sequences causes the variation in the chromosome morphology and thus the genome size among diploid species in the genus Oryza.     

Formation and stability of complex organic compounds in space environments.

Complex organic compounds have been found in extraterrestrial bodies such as meteorites and comets. We confirmed the formation of complex organic compounds that contained amino acid precursors from a mixture of carbon monoxide (or methanol), ammonia and water by radiation or UV. Molecular weights of the complex organics were several thousands. Stability of the complex precursors was studied. When free amino acids were irradiated with gamma rays or synchrotron radiation, they easily decomposed. The complex precursors were, however, much more stable than free amino acid against irradiation. We propose to examine the formation and alteration of amino acid precursors in space by using exposed facility of ISS.