Evaluating the Effects of Metals on Microorganisms in Flooded Paddy Soils Using the SEM/AVS-Based Approach and Measurements of Exchangeable Metal Concentrations.

We examined possible adverse effects of heavy metals on microbial activity, biomass, and community composition using the simultaneously extracted metals (SEM)/acid-volatile sulfide (AVS)-based approach and measurements of exchangeable metal concentrations in three paddy soils (wastewater-contaminated soil, mine-contaminated soil, and noncontaminated soil) incubated for 60 days under flooded conditions. Incubation under flooding increased pH and decreased Eh in all samples. AVS increased when Eh decreased to approximately -200 mV for the mine-contaminated and noncontaminated soils, while the wastewater-contaminated soil originally had a high concentration of AVS despite its air-dried condition. Addition of rice straw or alkaline material containing calcium carbonate and gypsum increased AVS levels under flooded conditions. We observed no apparent relationship between soil enzyme activity (ß-D-glucosidase and acid phosphatase) and concentrations of SEM, [∑SEM - AVS], and exchangeable metals. Bacterial and fungal community composition, assessed using polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) analysis targeting rRNA genes, was largely influenced by site of collection and incubation time, but metal contamination did not influence community composition. We observed significant negative correlations between biomass C and [∑SEM - AVS] and between biomass C and ∑SEM, suggesting that [∑SEM - AVS] and ∑SEM might reflect the bioavailability of organic matter to microorganisms in these soils.

Complete genome sequence of Bacillus subtilis NA05 (=NBRC 116153), a phosphate-solubilizing bacterium isolated from crop field soil.

We report the complete genome sequence of the phosphate-solubilizing bacterium Bacillus subtilis NA05 (=NBRC 116153), consisting of a circular chromosome of ~3.8 M bp and two circular plasmids. The data presented here provide further insight into the genetic and functional potential of B. subtilis and the mechanism of phosphate solubilization.

Bacterial and fungal community composition and community-level physiological profiles in forest soils.

We characterized the potential functioning and composition of the bacterial and fungal communities in the O and A horizons of forest soils using community-level physiological profile (CLPP) based on BIOLOG analysis, and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of 16S and 18S rDNA fragments, respectively. In addition, relationships between the potential functioning and the community composition in each horizon, and between the O and A horizons, were assessed using Procrustes analysis. For the bacterial and fungal communities, the CLPP and DGGE profile were clearly separated between the O and A horizons in a principal coordinate analysis except for the fungal CLPP. No significant links for CLPP and DGGE profile between the O and A horizons were observed for either bacterial or fungal communities, suggesting that different factors had considerable influence on the microbial communities between the O and A horizons. Significant couplings between bacterial and fungal DGGE profiles (p <0.05 for O horizon; p <0.01 for A horizon), and between bacterial and fungal CLPPs (p = 0.001 for O horizon; p <0.01 for A horizon), were observed in the O and A horizons, implying that common factors strongly influenced the bacterial and fungal communities in each horizon. Although a significant correlation was observed between bacterial community composition and the potential functioning in the A horizon (p <0.01), such a correlation was not observed for the fungal community in the A horizon, and for the bacterial and fungal communities in the O horizon. This finding suggested that potential functioning, which would reflect only rapidly growing microorganisms, was not strongly associated with the composition of the entire microbial community. Further studies are needed to unravel the factors shaping the composition and functioning of microbial communities in forest soils.

Polymorphic trial in oxidative damage of arsenic exposed Vietnamese.

Arsenic causes DNA damage and changes the cellular capacity for DNA repair. Genes in the base excision repair (BER) pathway influence the generation and repair of oxidative lesions. Single nucleotide polymorphisms (SNPs) in human 8-oxoguanine DNA glycosylase (hOGG1) Ser326Cys; apurinic/apyrimidinic endonuclease (APE1) Asp148Glu; X-ray and repair and cross-complementing group 1 (XRCC1) Arg280His and Arg399Gln in the BER genes were analyzed, and the relationship between these 4 SNPs and the urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations of 100 Vietnamese population exposed to arsenic was investigated. Individuals with hOGG1 326Cys/Cys showed significantly higher urinary 8-OHdG concentrations than did those with 326 Ser/Cys and Ser/Ser. As for APE1 Asp148Glu, heterozygous subjects showed significantly higher urinary 8-OHdG concentrations than did those homozygous for Asp/Asp. Moreover, global ethnic comparison of the allelic frequencies of the 4SNPs was performed in 10 population and previous reported data. The mutant allele frequencies of hOGG1 Ser326Cys in the Asian populations were higher than those in the African and Caucasian populations. As for APE1 Asp148Glu, Caucasians showed higher mutant frequencies than those shown by African and Asian populations. Among Asian populations, the Bangladeshi population showed relatively higher mutant allele frequencies of the APE1 Asp148Glu polymorphism. This study is the first to demonstrate the existence of genetic heterogeneity in a worldwide distribution of SNPs (hOGG1 Ser326Cys, APE1 Asp148Glu, XRCC1 Arg280His, and XRCC1 Arg399Gln) in the BER genes.

Genetic variants associated with arsenic metabolism within human arsenic (+3 oxidation state) methyltransferase show wide variation across multiple populations.

Human arsenic (+3 oxidation state) methyltransferase (AS3MT) is known to catalyze the methylation of arsenite. The objective of this study was to investigate the diversity of the AS3MT gene in Mexican and German populations. The distribution of 18 single nucleotide polymorphisms (SNPs) in AS3MT was assessed on healthy individuals: 38 Mestizo, 69 Nahuas, 50 Huicholes, and 32 Germans. All 18 SNPs were polymorphic in the German and Mexican populations. Of the three Mexican populations, a minor allele frequency was the highest in the Mestizo, followed by the Nahuas and Huicholes. In the German and three Mexican groups, haplotype #1(TATAGAAGTCTTCATGAC) was the most predominant. Seven haplotypes were newly found in the German and three Mexican populations. The D' values between SNP pairs were high in the German and Nahua populations; they had a similar pattern. The pattern of the Mestizo was more similar to the African than to the other Mexican populations. Huicholes had a moderate pattern of the African and German/Nahua populations. The network had three clusters. One originated in the African population and another may have originated in an Asian (Chinese and/or Japanese) population. The third one may have originated among Caucasians. This study is the first to demonstrate the existence of genetic heterogeneity in the distribution of 18 SNPs in AS3MT of German and Mexican populations.

Silver speciation in liver of marine mammals by synchrotron X-ray absorption fine structure and X-ray fluorescence spectroscopies.

The chemical form of Ag in the livers of five species of marine mammals was examined using X-ray absorption fine structure (XAFS) and X-ray fluorescence (XRF) spectroscopies. The XAFS analysis suggested that Ag(2)Se was present in the livers of the Franciscana dolphin (Pontoporia blainvillei), Dall's porpoise (Phocoenoides dalli), and Baird's beaked whale (Berardius bairdii), whereas Ag(2)S was present in the livers of the striped dolphin (Stenella coeruleoalba) and pygmy killer whale (Feresa attenuata). XRF spectroscopy results revealed that the distribution patterns of Ag and Se in a thin section of the liver of the Franciscana dolphin were the same; this also implied that Ag was associated with Se in the liver. Thus, the interaction of Ag with Se or S may offer significant protection against the toxicity of Ag in marine mammals. The formation of either Ag(2)Se or Ag(2)S might depend on the Hg levels in the liver. Ag(2)Se was observed in liver samples with relatively high Ag/Hg ratio, whereas liver samples with low Ag/Hg ratio contained Ag(2)S.

Global analysis of genetic variation in human arsenic (+3 oxidation state) methyltransferase (AS3MT).

Human arsenic (+3 oxidation state) methyltransferase (AS3MT) is known to catalyze the methylation of arsenite. The objective of this study was to investigate the diversity of the AS3MT gene at the global level. The distribution of 18 single nucleotide polymorphisms (SNPs) in AS3MT was performed in 827 individuals from 10 populations (Japanese, Korean, Chinese, Mongolian, Tibetans, Sri Lankan Tamils, Sri Lankan Sinhalese, Nepal Tamangs, Ovambo, and Ghanaian). In the African populations, the A allele in A6144T was not observed; the allele frequencies of C35587 were much lower than those in other populations; the allele frequencies of A37616 and C37950 were relatively higher than those in other populations. Among Asian populations, Mongolians showed a different genotype distribution pattern. A lower C3963 and T6144 frequencies were observed, and, in the C37616A and T37950C polymorphism, the Mongolian population showed higher A37616 and C37950 allele frequencies than other Asian populations, similarly to the African populations. A total of 66 haplotypes were observed in the Ovambo, 48, in the Ghanaian, 99, in the Japanese, 103, in the Korean, 103, in the South Chinese, 20, in the Sri Lankan Tamil, 12, in the Sri Lankan Sinhalese, 21, in the Nepal Tamang, 50, in the Tibetan, and 45, in the Mongolian populations. The D' values between the SNP pairs were extremely high in the Sri Lankan Sinhalese population. Relatively higher D' values were observed in Mongolian and Sri Lankan Tamil populations. Network analysis showed two clusters that may have different origins, African and Asians (Chinese and/or Japanese). The present study is the first to demonstrate the existence of genetic heterogeneity in a world wide distribution of 18 SNPs in AS3MT.

Genetic polymorphisms in glutathione S-transferase (GST) superfamily and arsenic metabolism in residents of the Red River Delta, Vietnam.

To elucidate the role of genetic factors in arsenic metabolism, we investigated associations of genetic polymorphisms in the members of glutathione S-transferase (GST) superfamily with the arsenic concentrations in hair and urine, and urinary arsenic profile in residents in the Red River Delta, Vietnam. Genotyping was conducted for GST omega1 (GSTO1) Ala140Asp, Glu155del, Glu208Lys, Thr217Asn, and Ala236Val, GST omega2 (GSTO2) Asn142Asp, GST pi1 (GSTP1) Ile105Val, GST mu1 (GSTM1) wild/null, and GST theta1 (GSTT1) wild/null. There were no mutation alleles for GSTO1 Glu208Lys, Thr217Asn, and Ala236Val in this population. GSTO1 Glu155del hetero type showed higher urinary concentration of As(V) than the wild homo type. Higher percentage of DMA(V) in urine of GSTM1 wild type was observed compared with that of the null type. Strong correlations between GSTP1 Ile105Val and arsenic exposure level and profile were observed in this study. Especially, heterozygote of GSTP1 Ile105Val had a higher metabolic capacity from inorganic arsenic to monomethyl arsenic, while the opposite trend was observed for ability of metabolism from As(V) to As(III). Furthermore, other factors including sex, age, body mass index, arsenic level in drinking water, and genotypes of As (+3 oxidation state) methyltransferase (AS3MT) were also significantly co-associated with arsenic level and profile in the Vietnamese. To our knowledge, this is the first study indicating the associations of genetic factors of GST superfamily with arsenic metabolism in a Vietnamese population.

Exposure, metabolism, and health effects of arsenic in residents from arsenic-contaminated groundwater areas of Vietnam and Cambodia: a review.

In this review, we summarize the current knowledge on exposure, metabolism, and health effects of arsenic (As) in residents from As-contaminated groundwater areas of Vietnam and Cambodia based on our findings from 2000 and other studies. The health effects of As in humans include severe gastrointestinal disorders, hepatic and renal failure, cardiovascular disturbances, skin pigmentation, hyperkeratosis, and cancers in the lung, bladder, liver, kidney, and skin. Arsenic contamination in groundwater is widely present at Vietnam and Cambodia and the highest As levels are frequently found in groundwater from Cambodia. Sand filter system can reduce As concentration in raw groundwater. The results of hair and urine analyses indicate that residents from these As-contaminated areas are exposed to As. In general, sex, age, body mass index, and As exposure level are significantly associated with As metabolism. Genetic polymorphisms in arsenic (+III) methyltransferase and glutathione-S-transferase isoforms may be influenced As metabolism and accumulation in a Vietnamese population. It is suggested oxidative DNA damage is caused by exposure to As in groundwater from residents in Cambodia. An epidemiologic study on an association of As exposure with human health effects is required in these areas.

Ethnic differences in five intronic polymorphisms associated with arsenic metabolism within human arsenic (+3 oxidation state) methyltransferase (AS3MT) gene.

Human arsenic (+3 oxidation state) methyltransferase (AS3MT) is known to catalyze the methylation of arsenite, and intronic single-nucleotide polymorphisms (SNPs: G7395A, G12390C, T14215C, T35587C, and G35991A) in the AS3MT gene were shown to be related to inter-individual variation in the arsenic metabolism. In the present study, the genotyping for these SNPs was developed using the polymerase chain reaction and restriction fragment length polymorphism technique. Applying this method, the genotype distribution among the Ovambo, Turkish, Mongolian, Korean, and Japanese populations was investigated, and our results were compared with those from other studies. G7395, G12390, T35587, and A35991 were predominant among the five populations in our study. However, a previous study in Argentina, C12390 and G35991 showed the highest allele frequency among the eight populations studied in other studies. The dominant allele of T14215C differed among populations: the T14215 allele was predominant in Argentina, the allele frequency of C14215 was higher than that of T14215 among Turks, Mongolians, Europeans, and American ancestry. In Korea and Japan, similar allele frequencies were observed in T14215 and C14215. Higher allele frequencies were observed in haplotype G7395/G12390/C14215/T35587 with frequencies of 0.40 (Turks), 0.28 (Mongolians), and 0.23 (Koreans). On the other hand, the allele frequency for G7395/G14215/T35587/A35991 was the highest among the Ovambos (0.32), and the frequency for G7395/G12390/C35587/G35991 was the highest among the Japanese (0.27). It is noteworthy that the Japanese haplotype differs from that of the Koreans and Mongolians, which indicates the importance of investigating other intronic polymorphisms in AS3MT, especially in Asians.

Genetic polymorphisms in AS3MT and arsenic metabolism in residents of the Red River Delta, Vietnam.

To elucidate the role of genetic factors in arsenic (As) metabolism, we studied associations of single nucleotide polymorphisms (SNPs) in As (+3 oxidation state) methyltransferase (AS3MT) with the As concentrations in hair and urine, and urinary As profile in residents in the Red River Delta, Vietnam. Concentrations of total As in groundwater were 0.7-502 mug/l. Total As levels in groundwater drastically decreased by using sand filter, indicating that the filter could be effective to remove As from raw groundwater. Concentrations of inorganic As (IAs) in urine and total As in hair of males were higher than those of females. A significant positive correlation between monomethylarsonic acid (MMA)/IAs and age in females indicates that older females have higher methylation capacity from IAs to MMA. Body mass index negatively correlated with urinary As concentrations in males. Homozygote for SNPs 4602AA, 35991GG, and 37853GG, which showed strong linkage disequilibrium (LD), had higher percentage (%) of dimethylarsinic acid (DMA) in urine. SNPs 4740 and 12590 had strong LD and associated with urinary %DMA. Although SNPs 6144, 12390, 14215, and 35587 comprised LD cluster, homozygotes in SNPs 12390GG and 35587CC had lower DMA/MMA in urine, suggesting low methylation capacity from MMA to DMA in homo types for these SNPs. SNPs 5913 and 8973 correlated with %MMA and %DMA, respectively. Heterozygote for SNP 14458TC had higher MMA/IAs in urine than TT homozygote, indicating that the heterozygote may have stronger methylation ability of IAs. To our knowledge, this is the first study on the association of genetic factors with As metabolism in Vietnamese.

Diversity of glutathione s-transferase omega 1 (a140d) and 2 (n142d) gene polymorphisms in worldwide populations.

1. Glutathione S-transferase class omega (GSTO) 1 and 2 are members of the glutathione-S-transferase family, which uses glutathione in the process of the biotransformation of drugs, xenobiotics and oxidative stress. Associations with the age-at-onset of Alzheimer's and Parkinson's diseases have been shown in the genetic polymorphism of GSTO1 and GSTO2. 2. In the present study, the frequencies of GSTO1*A140D and GSTO2*N142D in Ovambos (n = 163), Turks (n = 194), Mongolians (n = 243) and Japanese (n = 102) were investigated and compared with findings from other studies. Detection of these single nucleotide polymorphisms was performed by polymerase chain reaction-restriction fragment length polymorphism analysis. 3. The allele frequencies of these polymorphisms in Ovambos, Turks, Mongolians and Japanese were 0.040, 0.085, 0.128 and 0.108, respectively, for GSTO1*A140D and 0.583, 0.219, 0.173 and 0.216, respectively, for GSTO2*N142D. Ovambos showed the lowest allele frequency of GSTO1*A140D. Conversely, Africans, including Ovambos, showed higher allele frequencies of GSTO2*N142D than Caucasians and Asians. 4. The existence of a certain genetic heterogeneity in the worldwide distribution of these two polymorphisms is revealed in the present study.

Prokaryotic Community Structure of Long-Term Fertilization Field Andisols in Central Japan.

Long-term fertilization experiments are a useful way to elucidate the impacts of fertilization on soil ecosystems. Here, we report the prokaryotic community structure in experimental field soil after 80 years of successive fertilization. Our 16S rRNA gene sequencing detected 20,996 amplicon sequence variants, including major phyla such as Proteobacteria, Acidobacteria, and Actinobacteria.

Arsenic in marine mammals, seabirds, and sea turtles.

Although there have been numerous studies on arsenic in low-trophic-level marine organisms, few studies exist on arsenic in marine mammals, seabirds, and sea turtles. Studies on arsenic species and their concentrations in these animals are needed to evaluate their possible health effects and to deepen our understanding of how arsenic behaves and cycles in marine ecosystems. Most arsenic in the livers of marine mammals, seabirds, and sea turtles is AB, but this form is absent or occurs at surprisingly low levels in the dugong. Although arsenic levels were low in marine mammals, some seabirds, and some sea turtles, the black-footed albatross and hawksbill and loggerhead turtles showed high concentrations, comparable to those in marine organisms at low trophic levels. Hence, these animals may have a specific mechanism for accumulating arsenic. Osmoregulation in these animals may play a role in the high accumulation of AB. Highly toxic inorganic arsenic is found in some seabirds and sea turtles, and some evidence suggests it may act as an endocrine disruptor, requiring new and more detailed studies for confirmation. Furthermore, DMA(V) and arsenosugars, which are commonly found in marine animals and marine algae, respectively, might pose risks to highly exposed animals because of their tendency to form reactive oxygen species. In marine mammals, arsenic is thought to be mainly stored in blubber as lipid-soluble arsenicals. Because marine mammals occupy the top levels of their food chain, work to characterize the lipid-soluble arsenicals and how they cycle in marine ecosystems is needed. These lipid-soluble arsenicals have DMA precursors, the exact structures of which remain to be determined. Because many more arsenicals are assumed to be present in the marine environment, further advances in analytical capabilities can and will provide useful future information on the transformation and cycling of arsenic in the marine environment.

Asian specific low mutation frequencies of the M287T polymorphism in the human arsenic (+3 oxidation state) methyltransferase (AS3MT) gene.

Groundwater pollution by arsenic is a serious worldwide problem, especially in Asian countries. Inter-individual variation in arsenic metabolism has been reported and recent studies demonstrate that 287T allele in human arsenic (+3 oxidation state) methyltransferase (AS3MT) increase the percentage of monomethylated arsenic in urine. The objectives of the present study was to evaluate the ethnic difference in M287T (T/C) polymorphism in AS3MT among Japanese (n=1074), Koreans (n=435), Chinese (n=154), Mongolians (n=246), Uygurs (n=56), Tibetans (n=180), Tamangs (n=53), Tamils (n=58), Sinhalese (n=54), Turks (n=243), Ovambos (n=185), Ghanaians (n=121), Xhosas (n=101), and other four populations from previous studies. Of 17 populations, Xhosas had the highest 287T frequency (0.233). Other African and Caucasian populations had similar287T frequencies above 0.100 with the exception of the Ghanaians (0.071). On the other hand, the Asian populations had relatively lower 287T allele frequencies ranging from 0.000 to 0.041 than the Africans and Caucasians. Our findings indicate that genetic susceptibility to arsenic toxicity in Asian is different from Africans and Caucasians.

Cytochrome P450 2J2*7 polymorphisms in Japanese, Mongolians and Ovambos.

Human cytochrome P450 2J2 (CYP2J2) is abundant in cardiovascular tissue and active in the metabolism of arachidonic acid to eicosanoids that have potent vasodilatory properties. Variability of the CYP2J2 gene is highly constrained except for its proximal promoter: there is a relatively common and functionally relevant single nucleotide polymorphism, indicated by -50G > T polymorphism (CYP2J2*7). Although genetic variation is known among ethnic groups, data for allele frequency are limited to a few Caucasian, Asian, and one African populations. In the present study, genotype distribution of CYP2J2*7 polymorphisms was investigated using polymerase chain reaction and restriction fragment length polymorphism assay in Japanese (n = 338), Mongolian (n = 118), and Ovambo (n = 186) populations and the findings compared with other populations. The mutant (CYP2J2*7) frequencies in the Japanese, Mongolians, and Ovambos were 0.0621, 0.0339, and 0.0672, respectively. Except for the Taiwanese, a general uniformity in the polymorphism in the Asian populations was observed. The mutation frequency of Ovambos was relatively lower than that of the African-American population. This study is the first to investigate the distribution of the CYP2J2*7 gene polymorphisms in Japanese, Mongolians, and Ovambos. These data will be informative and facilitate genetic association studies, in Asian and African populations for CYP2J2-related diseases such as cardiovascular disorders.

Two N-linked glycosylation sites (Asn18 and Asn106) are both required for full enzymatic activity, thermal stability, and resistance to proteolysis in mammalian deoxyribonuclease I.

Deoxyribonuclease I (DNase I) is known to be a glycoprotein, and two potential N-linked glycosylation sites (N18 and N106) are known for mammalian enzymes. In the present study, N18 and N106 were mutated in order to investigate the biological role of N-linked glycosylation in three mammalian (human, bovine, and equine) DNases I. The enzyme activities of N18Q and N106Q were lower than that of the wild type, and that of the double mutant (N18Q/N106Q) was lower than those of the single mutants, in accord with the sugar moiety contents in the three mammals. In addition, all mutant enzymes were unstable to heat, suggesting that both sites are required for heat stability. Moreover, in human and equine enzymes, the N18Q and N106Q mutant enzymes were less resistant to trypsin, while N18Q/N106Q was the most sensitive to trypsin. As for bovine DNase I, the trypsin resistance of N18Q and N106Q was similar to that of the wild type, but that of N18Q/N106Q decreased in a time-dependent manner. On the other hand, N-linked glycosylation was not related to pH sensitivity. The results of the present study suggest that N18 and N106 are both necessary for (i) full enzymatic activity, (ii) heat-stability, and (iii) trypsin resistance.

Subcellular distribution of trace elements in kidney of a mother-fetus pair of Dall's porpoises (Phocoenoides dalli).

Total and subcellular renal Zn, Cu, Se, Mn, V, Hg, Cd and Ag were determined by a mother-fetus pair of Dall's porpoises (Phocoenoides dalli). All element concentrations in the maternal individual were higher than those in the fetal individual. Most of total renal elements studied were present in the cytosol of both animals. In maternal cytosol, Mn, Hg and Ag were present in high molecular weight substances (HMW); Se was in low molecular weight substances (LMW); Zn, Cu, and Cd were in metallothionein (MT), mostly; and the distribution of V in percentage among the three renal cytosolic fractions was similar. In fetal cytosol, Zn, Mn, Hg, V, Cd, and Ag were present in HMW, Cu was present in MT, mostly. In contrast, Se was observed mostly in both LMW and HMW. MT isoforms were characterized. Three obvious peaks in retention time were found in either the maternal or fetal MT. The highest elemental ion intensities were in the 7.8min peak for the mother, and in the 4.3min peak for the fetus, respectively, implying that different MT isoforms may be closely associated with elemental accumulation between maternal and fetal renal cytosols.

Interelement relationships and age-related variation of trace element concentrations in liver of striped dolphins (Stenella coeruleoalba) from Japanese coastal waters.

Concentrations of 19 trace elements (V, Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, Hg, and Pb) were determined in the liver of the striped dolphins (Stenella coeruleoalba) collected around Japan during 1977-1982 to examine the sex difference, age dependence, and interrelationships among trace elements. Tissue distribution of trace elements was also investigated in one adult and one fetus specimens. Generally, concentrations of Se, Sr, Ag, Cd, Cs, Ba, Hg, and Pb were higher in the tissues of adult than those of fetus, whereas the opposite trend was observed for Cr and Tl. There were no significant sex differences in the trace element levels in the liver. Significant positive correlations between age (0-26.5 years) and hepatic concentrations were found for Ag, Se, Hg, V, Fe, Pb, and Sr, suggesting their age-dependent accumulation in the liver. In contrast, hepatic concentrations of Mn and Zn decreased with age. Significant positive relationships were observed between Se, and Hg, Ag, V, Fe, and Sr in the liver.

Phosphorus-mineralizing Communities Reflect Nutrient-Rich Characteristics in Japanese Arable Andisols.

Elucidating the soil phosphorus cycle driven by soil microbes is a vital question in soil microbial ecology. The Japanese arable Andisols, occupying half of the Japanese cropland, are known for their high phosphorus sorption capacity. However, limited information is currently available on microbially driven phosphorus mineralization in arable Andisols. We herein report that the phosphorus-mineralizing community in the Japanese arable Andisols showed characteristic distribution and composition patterns, from those in other types of soils. We performed a chemical analysis and microbial community analysis of 43 arable Andisols along the Japanese archipelago. Soil phosphomonoesterase activities measured at pH 11 were approximately 70% of those at pH 6.5, which indicates that alkaline phosphatase contributes to phosphorus cycling, although most soil samples were acidic. Functional gene predictions based on 16S rRNA gene sequencing indicated that the alkaline phosphatase gene phoD was more abundant than other alkaline phosphatase genes and, thus, plays major roles. Hence, amplicon sequencing targeting phoD was performed and the results obtained showed that alphaproteobacterial phoD was dominant. This is in contrast to previously reported phoD compositions in other soils and may be attributed to the nutrient conditions in arable Andisols, which favor copiotrophic Alphaproteobacteria. Furthermore, the composition of phoD correlated with soil pH and bioavailable phosphorus concentrations rather than carbon or nitrogen concentrations. These results were partly different from previous findings, varying in the soil types and geographic ranges of sampling sites. Collectively, the present results indicate that the phosphorus-mineralizing community in the Japanese arable Andisols is regulated differently from those in other soil types.