Using multivariate statistical methods to assess the groundwater quality in an arsenic-contaminated area of Southwestern Taiwan.

Groundwater is a major water resource in Southwestern Taiwan; hence, long-term monitoring of water quality is essential. The study aims to assess the hydrochemical characteristics of water in the arsenic-contaminated aquifers of Choushui River alluvial fan and Chianan Plain, Taiwan using multivariate statistical methods, namely, factor analysis (FA), cluster analysis (CA), and discriminant analysis (DA). Factor analysis is applied to reveal the processes controlling the hydrochemistry of groundwater. Cluster analysis is applied to spatially categorize the collected water samples based on the water quality. Discriminant analysis is then applied to elucidate key parameters associated with the occurrence of elevated As concentration (>10 µg L(-1)) in groundwater. Major water types are characterized as Na-Ca-Cl and Na-Mg-Cl in the Choushui River alluvial fan and Chianan Plain, respectively. Inorganic species of arsenic (As), particularly As(III), prevail in these two groundwater catchments, and their levels are higher in the Chianan Plain than in the Choushui River alluvial fan. Through FA, three factors, namely, the degree of salination, As reduction, and iron (Fe) reduction, are determined and denoted irrespective of some differences between the factorial compositions. Spatial distribution patterns of factors As reduction and Fe reduction imply that the redox zonation is delineated by As- and Fe-dominance zones separately. The results of CA demonstrate that three main groups can be properly explained by the factors extracted via FA. Three- (Fe(2+), Fe(3+), and NH (4) (+) ) and four-parameters (Fe(2+), Fe(3+), NH (4) (+) , and Ca(2+)) derived from discriminant analysis for Choushui River alluvial fan and Chianan Plain are elucidated as key parameters affecting the distribution of As-contained groundwater. The analytical results indicate that the reductive dissolution of Fe minerals is prerequisite for the mobilization of As, whereas the shift of redox condition from Fe- to As-reducing leads to the accumulation of dissolved As in this area.

Evolutionary fate of rhizome-specific genes in a non-rhizomatous Sorghum genotype.

What is the fate of organ-specific genes after the organ is lost? For Sorghum propinquum and Sorghum halepense genes that were previously shown to have rhizome-enriched expression, we have conducted comparative analysis of both coding regions and regulatory sequences in Sorghum bicolor (non-rhizomatousness) and S. propinquum (rhizomatousness). Most genes with rhizome-enriched expression appear to have similar numbers of paralogous copies in both genotypes, with only three of 24 genes studied showing significant differences in copy numbers. We detected no greater propensity for mutation in S. bicolor than in S. propinquum of genes with rhizome-enriched expression in the latter. Several cis-acting regulatory elements, particularly an Myb-binding core (AACGG) that is involved in the regulation of the mitotic cyclin, were more abundant in promoters of S. propinquum than in non-rhizomatous S. bicolor or Oryza sativa (rice). We suggest that many genes with rhizome-enriched expression in S. propinquum may serve multiple functions, with partial loss of some of these functions in S. bicolor but ongoing purifying selection acting to preserve the remaining functions. Expressed genes in polyploid S. halepense rhizomes appeared to be more frequently derived from the S. propinquum than the S. bicolor progenitor, but there was some evidence of formation of novel alleles and 'recruitment' of S. bicolor genes to rhizome-enriched expression in S. halepense, suggesting that polyploidy may have offered new evolutionary potential to S. halepense.

Characterization of the altered anthranilate synthase in 5-methyltryptophan-resistant rice mutants.

In an earlier investigation, homologous mutant lines resistant to growth inhibition by 5-methyltryptophan (5MT) were selected from a callus that had been irradiated with a 50-Gy gamma ray during embryo culture. In order to identify the 5MT-resistant mechanism, we have continued our investigations of these mutant lines and studied the anthranilate synthase activity of the M5) advanced lines by direct fluorometric detection of the anthranilate formed in both control plants and mutant lines grown on 500 microM 5MT. The anthranilate synthase activity of the mutant plants was 2.2- to 3-fold higher than that of the control. In a kinetic analysis with tryptophan, an anthranilate synthase of the mutant lines was insensitive to feedback inhibition. These lines showed an enhanced accumulation of storage proteins and amino acids. The increased rates of protein synthesis in the mutant lines, relative to that of the control seeds, were 17-28.5%. The amino acid contents were 2.4-fold (MRI-40-2) to 2.6-fold (MRI-110-6) higher in the MRI lines than in the control seeds, and 2.4-fold (MRII-12-5) to 3.5-fold (MRII-8-1) higher in the MRII lines than in the control seeds. Significant increases among the amino acids of the MR lines were observed for tryptophan, phenylalanine, and tyrosine, which had been biosynthesized through the shikimate pathway. The transcript levels of putative OASA2, which is one of the key-regulating enzyme subunits in the tryptophan biosynthesis pathway, were studied in the control and 5MT-resistant mutant lines subjected to inhibition by two tryptophan analogs (5MT and alphaMT) and to other abiotic stresses (ABA, NaCl, and cold). The putative OASA2 gene in the 5MT-resistant mutant lines was highly expressed in at a low 5MT concentration and at an early stage of the 5MT and alphaMT treatments. However, mRNA accumulation of the putative OASA2 gene in the mutant plants gradually decreased when the plants were subjected to abiotic stresses such as NaCl and cold. These results indicated that the 5MT resistance in the mutant lines is due to altered anthranilate synthase forms.

Development of AFLP-derived STS markers for the selection of 5-methyltryptophan-resistant rice mutants.

To increase the specific free amino acid content in the japonica rice (Oryza sativa L.) cultivar Donganbyeo, mutant cell lines resistant to growth inhibition by 5-methyltryptophan (5MT) were selected from embryo-cultured callus irradiated with 50 Gy gamma-rays. Four 5MT-resistant homozygous M4 lines, MRI-40, MRI-116, MRII-8, and MRII-12, were obtained. The mean content of nine free essential amino acids were 70.1, 72.5, 31.7, and 35.4% greater than the original variety in these four mutant lines, respectively. For AFLP analysis, 8 EcoRI (+2) and 8 MseI (+3) primers used in 45 primer combinations generated a total of 3,684 bands with a mean of 82 bands, of which 361 (9.8%) were clearly polymorphic with the control cultivar, the four 5MT-resistant mutants, and five sensitive lines. The lines were grouped into three clusters through cluster analysis using unweighted pair grouping method of averages. The 36 polymorphic PCR products present only in the four homozygous 5MT-resistant lines were cloned and sequenced, and 10 of these sequenced products were converted into sequence tagged site (STS) markers. These STS primer sets were designated OSMR1-OSMR10. Six STS primer sets (OSMR1, OSMR2, OSMR3, OSMR4, OSMR5, and OSMR6) generated a single monomorphic PCR product identical in size to the original AFLP fragments. The broad applicability of these STS markers for the screening of 5MT resistance was evaluated with seven putative 5MT-resistant M2 plants (PM-1 to PM-7). Four STS markers (OSMR1, OSMR2, OSMR4, and OSMR5) out of six STS primer sets were revealed as polymorphic products between the control cultivar and the seven M2 plants. These markers can be utilized for the fine selection of 5MT resistance in rice, and this PCR-screening technique is less time-consuming, less labor-intensive, and more accurate and reliable than selection based solely on phenotypic evaluation involving soaking in 5MT solutions.

Expressed sequence tags from a wheat-rye translocation line (2BS/2RL) infested by larvae of Hessian fly [Mayetiola destructor (Say)].

Of the 16 known biotypes of the Hessian fly [ Mayetiola destructor (Say)], biotype L is recognized as being the most virulent. We have previously reported the development of near-isogenic lines (NILs) (BC(3)F(3:4)) by backcross introgression (Coker797*4/Hamlet) that differed by the presence or absence of the H21 gene on 2RL chromatin. Florescence in situ hybridization analysis revealed introgressed 2RLs in NILs possessing the H21 gene, but no signal was detected in NILs lacking 2RL. As part of an approach to elucidate molecular interactions between plants and the Hessian fly, a cDNA library from NILs with H21 infested by larvae of biotype L of the Hessian fly was constructed for expressed sequence tag (EST) analysis. Of 1,056 sequenced reactions attempted, 919 ESTs produced some lengths of readable sequences. Based on their putative identification, 730 ESTs that showed significant similarity with amino acid sequences registered in the gene bank were divided into 13 functional categories. Defense- and stress-related genes represented about 16.1%, including protease inhibition, oxidative burst, lignin synthesis, and phenylpropanoid metabolism. EST clones obtained from the cDNA library may provide a clue to the molecular interactions between plant and larva of the Hessian fly larval infestation.

Molecular characterization of a cDNA encoding putative calcium binding protein, HvCaBP1, induced during kernel development in barley (Hordeum vulgare L.).

Seed development is known to involve complex physiological and molecular events. In order to gain information on the molecular events that occur in the grains of barley during kernel development, we conducted suppression subtractive hybridization (SSH) using grains of barley cv. Karl at 14 days after fertilization (DAF) as the tester and grains at 5 DAF as the driver. We isolated an SSH clone that showed homology with a specific calcium binding protein in rice called EFA27. Screening the cDNA library, we identified two clones as a calcium binding protein. These clones, each carrying one calcium-binding EF-hand motif, were designated HvCaBP1 (Hordeum vulgare Calcium Binding Protein 1). HvCaBP1 possesses an N-terminal region with a conserved single Ca(2+)-binding EF-hand motif and one transmembrane helix. Northern hybridization showed that the highest expression occurred in grains and that expression increased in kernels at 8 DAF. As shown in situ hybridization, the HvCaBP1 gene was highly expressed in the embryo and tissues of the endosperm near the embryo and was detected in the vascular tissues of the glume in the kernel at 8 DAF. Accumulation of HvCaBP1 mRNAs subsequently increased in vegetative tissues for up to 48 h after abscisic acid (ABA) treatment. Transcripts of HvCaBP1 mRNAs may be regulated by endogenous ABA in the grains during kernel development.

Long-term effect of increased lead absorption on intelligence of children.

The authors examined the reversibility of cognitive impairment caused by a mild increase in lead absorption among children. The results of our initial study revealed that air and soil outside a lead-recycling plant in Taiwan were seriously contaminated by lead, which was associated with lowered intelligence quotients of 32 children who attended a nearby kindergarten (i.e., kindergarten A). Thirty-five children-who were comparable with respect to age, sex, birth order, sibling number, and parental education level-from another kindergarten (i.e., kindergarten B) located 5 km from the plant were enrolled as the reference group. Following the initial study, kindergarten A school children moved 2 km from the lead-recycling plant. Twenty-eight children in each group were followed successfully 2.5 y later. Blood lead, intelligence quotient, and intelligence quotient-related factors were reassessed. The results showed that the average blood lead level of the exposed pupils dropped 6.9 microg/dl (standard deviation [SD] = 3.9 microg/dl) (p < .001), and the average intelligence quotient increased 11.7 points (SD = 13.2) (p < .01), compared with the results of the initial study. The average blood lead level of the reference group decreased by 1.7 microg/dl (SD = .1.3) (p < .001), whereas the average intelligence quotient increased by 4.2 points (SD = 13.8) (p = .115). There was a significant difference in intelligence quotients between the two groups during the initial study, but the difference subsequently disappeared during the follow up. The authors concluded that intelligence quotient impairment, caused by a mild subclinical elevation of blood lead (i.e., likely no more than 30 microg/dl) for a period of 1-3 y in 3- to 5-y-olds, is at least partially reversible.

Occupational and environmental lead poisoning: case study of a battery recycling smelter in Taiwan.

The rapid industrialization in Taiwan has caused both prosperity and environmental pollution. The purpose of this study is to demonstrate a case of both occupational and environmental lead poisoning. A patient of lead poisoning initiated a survey of the battery recycling factory, which revealed that 31 of 64 workers suffered from lead poisoning. Children who attended a nearby kindergarten showed a significant increase of blood lead up to 15-25 micrograms/dl and a mild but significant decrease of IQ (intelligent quotient, by Binet-Simon scale) if compared with children of a nonexposed but socioeconomically comparable kindergarten. Outdoor workers of the nearby forging factory also showed a significant increase of blood lead if compared with indoor workers or workers of another nonexposed forging factory 20 Km away. Air sampling showed an average of more than 10 micrograms/m3 in the kindergarten. Soil sampling and analysis also revealed 400 folds increase of lead content, which decreased if the sample was taken deep down to 15-30 cm or 350 meters away from the battery recycling smelter. Moreover, after children were moved away from the pollution source, follow-up examination performed 2.5 years later showed a significant decrease of blood lead and partial recovery of IQ among them.