Two Possibly Distinct Prostaglandin E1 Receptors in N1E-115 Clone: One Mediating Inositol Trisphosphate Formation, Cyclic GMP Formation, and Intracellular Calcium Mobilization and the Other Mediating Cyclic AMP Formation

Prostaglandin E1 (PGE1)-mediated transmembrane signal control systems were investigated in intact murine neuroblastoma cells (clone N1E-115). PGE1 increased intracellular levels of total inositol phosphates (IP), cyclic GMP, cyclic AMP, and calcium ([Ca2+]i). PGE1 transiently increased inositol 1,4,5-trisphosphate formation, peaking at 20 s. There was more than a 10-fold difference between the ED50 for PGE1 at cyclic AMP formation (70 nM) and its ED50 values at IP accumulation (1 microM), cyclic GMP formation (2 microM), and [Ca2+]i increase (5 microM). PGE1-mediated IP accumulation, cyclic GMP formation, and [Ca2+]i increase depended on both the concentration of PGE1 and extracellular calcium ions. PGE1 had more potent intrinsic activity in cyclic AMP formation, IP accumulation, and cyclic GMP formation than did PGE2, PGF2 alpha, or PGD2. A protein kinase C activator, 4 beta-phorbol 12 beta-myristate 13 alpha-acetate, had opposite effects on PGE1-mediated IP release and cyclic GMP formation (inhibitory) and cyclic AMP formation (stimulatory). These data suggest that there may be subtypes of the PGE1 receptor in this clone: a high-affinity receptor mediating cyclic AMP formation, and a low-affinity receptor mediating IP accumulation, cyclic GMP formation, and intracellular calcium mobilization.     

Experimental Approach Reveals the Role of alx1 in the Evolution of the Echinoderm Larval Skeleton

Over the course of evolution, the acquisition of novel structures has ultimately led to wide variation in morphology among extant multicellular organisms. Thus, the origins of genetic systems for new morphological structures are a subject of great interest in evolutionary biology. The larval skeleton is a novel structure acquired in some echinoderm lineages via the activation of the adult skeletogenic machinery. Previously, VEGF signaling was suggested to have played an important role in the acquisition of the larval skeleton. In the present study, we compared expression patterns of Alx genes among echinoderm classes to further explore the factors involved in the acquisition of a larval skeleton. We found that the alx1 gene, originally described as crucial for sea urchin skeletogenesis, may have also played an essential role in the evolution of the larval skeleton. Unlike those echinoderms that have a larval skeleton, we found that alx1 of starfish was barely expressed in early larvae that have no skeleton. When alx1 overexpression was induced via injection of alx1 mRNA into starfish eggs, the expression patterns of certain genes, including those possibly involved in skeletogenesis, were altered. This suggested that a portion of the skeletogenic program was induced solely by alx1. However, we observed no obvious external phenotype or skeleton. We concluded that alx1 was necessary but not sufficient for the acquisition of the larval skeleton, which, in fact, requires several genetic events. Based on these results, we discuss how the larval expression of alx1 contributed to the acquisition of the larval skeleton in the putative ancestral lineage of echinoderms.     

Significant increase in plasma 4β-hydroxycholesterol concentration in patients after kidney transplantation

Several previous studies have shown that renal failure decreases not only renal elimination but also metabolic clearance of drugs, particularly those metabolized by CYP3A. However, whether recovery of renal function results in recovery of hepatic CYP3A activity remains unknown. In this study, we evaluated the effect of renal function on CYP3A activity after kidney transplantation in patients with end-stage renal disease (ESRD) by measuring the change in CYP3A activity using plasma concentration of 4β-hydroxycholesterol as a biomarker. The study enrolled 13 patients with ESRD who underwent the first kidney allograft transplantation. Morning blood samples were collected before and 3, 7, 10, 14, 21, 30, 60, 90, 120, 150 and 180 days after kidney transplantation. Plasma concentration of 4β-hydroxycholesterol was measured using GC-MS. Compared with before kidney transplantation, creatinine clearance increased significantly from day 3 after kidney transplantation and stabilized thereafter. Plasma concentration of 4β-hydroxycholesterol was elevated significantly on days 90 and 180 after kidney transplantation. In conclusion, this study suggests the recovery of CYP3A activity with improvement in renal function after kidney transplantation in patients with ESRD.     

Bacterial Cytochrome P450 System Catabolizing the Fusarium Toxin Deoxynivalenol

Deoxynivalenol (DON) is a natural toxin of fungi that cause Fusarium head blight disease of wheat and other small-grain cereals. DON accumulates in infected grains and promotes the spread of the infection on wheat, posing serious problems to grain production. The elucidation of DON-catabolic genes and enzymes in DON-degrading microbes will provide new approaches to decrease DON contamination. Here, we report a cytochrome P450 system capable of catabolizing DON in Sphingomonas sp. strain KSM1, a DON-utilizing bacterium newly isolated from lake water. The P450 gene ddnA was cloned through an activity-based screening of a KSM1 genomic library. The genes of its redox partner candidates (flavin adenine dinucleotide [FAD]-dependent ferredoxin reductase and mitochondrial-type [2Fe-2S] ferredoxin) were not found adjacent to ddnA; the redox partner candidates were further cloned separately based on conserved motifs. The DON-catabolic activity was reconstituted in vitro in an electron transfer chain comprising the three enzymes and NADH, with a catalytic efficiency (k_cat/K_m) of 6.4 mM⁻¹ s⁻¹. The reaction product was identified as 16-hydroxy-deoxynivalenol. A bioassay using wheat seedlings revealed that the hydroxylation dramatically reduced the toxicity of DON to wheat. The enzyme system showed similar catalytic efficiencies toward nivalenol and 3-acetyl deoxynivalenol, toxins that frequently cooccur with DON. These findings identify an enzyme system that catabolizes DON, leading to reduced phytotoxicity to wheat.     

Structural Requirements for Mutagenic Activities of N-Heterocyclic Bases in the Salmonella Test System

The mutagenic activities of quinoline, isoquinoline, phenanthridine, benzo(f)quinoline, benzo(h)quinoline and their α-amino derivatives were compared in relation to the effect of structural changes using the Salmonella typhimurium test system. All mutagenic compounds tested require the liver microsomal fraction for their mutagenic activity. Phenanthridine, two benzoquinolines and quinoline were mutagenic. α-Amination of two benzoquinolines and quinoline resulted to increase their mutagenic activity intensively. Addition of a benzene ring to the benzene moiety of 2-aminoquinoline, so that two carbon atoms are shared, affected distinctly the increase in the mutagenic activity. The co-existence of benzoquinoline series with 2-aminobenzo(f)quinoline showed the clear synergistic action.     

How are plant and fungal communities linked to each other in belowground ecosystems? A massively parallel pyrosequencing analysis of the association specificity of root-associated fungi and their host plants

In natural forests, hundreds of fungal species colonize plant roots. The preference or specificity for partners in these symbiotic relationships is a key to understanding how the community structures of root‐associated fungi and their host plants influence each other. In an oak‐dominated forest in Japan, we investigated the root‐associated fungal community based on a pyrosequencing analysis of the roots of 33 plant species. Of the 387 fungal taxa observed, 153 (39.5%) were identified on at least two plant species. Although many mycorrhizal and root‐endophytic fungi are shared between the plant species, the five most common plant species in the community had specificity in their association with fungal taxa. Likewise, fungi displayed remarkable variation in their association specificity for plants even within the same phylogenetic or ecological groups. For example, some fungi in the ectomycorrhizal family Russulaceae were detected almost exclusively on specific oak (Quercus) species, whereas other Russulaceae fungi were found even on “non‐ectomycorrhizal” plants (e.g., Lyonia and Ilex). Putatively endophytic ascomycetes in the orders Helotiales and Chaetothyriales also displayed variation in their association specificity and many of them were shared among plant species as major symbionts. These results suggest that the entire structure of belowground plant–fungal associations is described neither by the random sharing of hosts/symbionts nor by complete compartmentalization by mycorrhizal type. Rather, the colonization of multiple types of mycorrhizal fungi on the same plant species and the prevalence of diverse root‐endophytic fungi may be important features of belowground linkage between plant and fungal communities.     

CTENO64 Is Required for Coordinated Paddling of Ciliary Comb Plate in Ctenophores

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Empirical Bayes inference of pairwise F(ST) and its distribution in the genome

Populations often have very complex hierarchical structure. Therefore, it is crucial in genetic monitoring and conservation biology to have a reliable estimate of the pattern of population subdivision. F(ST)'s for pairs of sampled localities or subpopulations are crucial statistics for the exploratory analysis of population structures, such as cluster analysis and multidimensional scaling. However, the estimation of F(ST) is not precise enough to reliably estimate the population structure and the extent of heterogeneity. This article proposes an empirical Bayes procedure to estimate locus-specific pairwise F(ST)'s. The posterior mean of the pairwise F(ST) can be interpreted as a shrinkage estimator, which reduces the variance of conventional estimators largely at the expense of a small bias. The global F(ST) of a population generally varies among loci in the genome. Our maximum-likelihood estimates of global F(ST)'s can be used as sufficient statistics to estimate the distribution of F(ST) in the genome. We demonstrate the efficacy and robustness of our model by simulation and by an analysis of the microsatellite allele frequencies of the Pacific herring. The heterogeneity of the global F(ST) in the genome is discussed on the basis of the estimated distribution of the global F(ST) for the herring and examples of human single nucleotide polymorphisms (SNPs).