Transporters of arsenite in rice and their role in arsenic accumulation in rice grain.

Arsenic poisoning affects millions of people worldwide. Human arsenic intake from rice consumption can be substantial because rice is particularly efficient in assimilating arsenic from paddy soils, although the mechanism has not been elucidated. Here we report that two different types of transporters mediate transport of arsenite, the predominant form of arsenic in paddy soil, from the external medium to the xylem. Transporters belonging to the NIP subfamily of aquaporins in rice are permeable to arsenite but not to arsenate. Mutation in OsNIP2;1 (Lsi1, a silicon influx transporter) significantly decreases arsenite uptake. Furthermore, in the rice mutants defective in the silicon efflux transporter Lsi2, arsenite transport to the xylem and accumulation in shoots and grain decreased greatly. Mutation in Lsi2 had a much greater impact on arsenic accumulation in shoots and grain in field-grown rice than Lsi1. Arsenite transport in rice roots therefore shares the same highly efficient pathway as silicon, which explains why rice is efficient in arsenic accumulation. Our results provide insight into the uptake mechanism of arsenite in rice and strategies for reducing arsenic accumulation in grain for enhanced food safety.

RNA-Seq Transcriptome Analysis of the Liver and Brain of the Black Carp (Mylopharyngodon piceus) During Fasting.

The black carp (Mylopharyngodon piceus) is an important carnivorous freshwater-cultured species. To understand the molecular basis underlying the response of black carp to fasting, we used RNA-Seq to analyze the liver and brain transcriptome of fasting fish. Annotation to the NCBI database identified 66,609 unigenes, of which 22,841 were classified into the Gene Ontology database and 15,925 were identified in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Comparative analysis of the expression profile between fasting and normal feeding fish revealed 13,737 differentially expressed genes (P < 0.05), of which 12,480 were found in liver tissue and 1257 were found in brain tissue. The KEGG pathway analysis showed significant differences in expression of genes involved in metabolic and immune pathways, such as the insulin signaling pathway, PI3K-Akt signaling pathway, cAMP signaling pathway, FoxO signaling pathway, AMPK signaling pathway, endocytosis, and apoptosis. Quantitative real-time PCR analysis confirmed that expression of the genes encoding the factors involved in those pathways differed between fasting and feeding fish. These results provide valuable information about the molecular response mechanism of black carp under fasting conditions.

The role of the rice aquaporin Lsi1 in arsenite efflux from roots.

*When supplied with arsenate (As(V)), plant roots extrude a substantial amount of arsenite (As(III)) to the external medium through as yet unidentified pathways. The rice (Oryza sativa) silicon transporter Lsi1 (OsNIP2;1, an aquaporin channel) is the major entry route of arsenite into rice roots. Whether Lsi1 also mediates arsenite efflux was investigated. *Expression of Lsi1 in Xenopus laevis oocytes enhanced arsenite efflux, indicating that Lsi1 facilitates arsenite transport bidirectionally. *Arsenite was the predominant arsenic species in arsenate-exposed rice plants. During 24-h exposure to 5 mum arsenate, rice roots extruded arsenite to the external medium rapidly, accounting for 60-90% of the arsenate uptake. A rice mutant defective in Lsi1 (lsi1) extruded significantly less arsenite than the wild-type rice and, as a result, accumulated more arsenite in the roots. By contrast, Lsi2 mutation had little effect on arsenite efflux to the external medium. *We conclude that Lsi1 plays a role in arsenite efflux in rice roots exposed to arsenate. However, this pathway accounts for only 15-20% of the total efflux, suggesting the existence of other efflux transporters.

Complete mitochondrial genome of gray black carp (Mylopharyngodon piceus).

The black carp (Mylopharyngodon piceus), native to eastern Asian, is a large, commercially valuable fish, and has been widely introduced to other countries. In this study, the mitochondrial gene sequence of gray black carp (M. piceus MT084757) in Foshan, Guangdong Province was first determined using the Sanger sequencing method. The mitochondrial DNA genome was 16,616 bp in length, including 13 protein-coding genes (PCGs), two rRNA genes, 22 transfer RNA genes, and a non-coding control region (D-loop). The overall nucleotide composition of the mitochondrial DNA is 32.04% A, 24.52% T, 15.68% C, 27.76% G, with 56.56% AT, respectively. Phylogenetic tree analysis suggests that the gray black carp (M. piceus MT 084757) is closely related to Elopichthys bambus and Squaliobarbus curriculus. The complete mitochondrial genome of the gray black carp (M. piceus MT 084757) would be useful for researching the causes of changes in body color.

delta-Opioid receptor stimulation enhances the growth of neonatal rat ventricular myocytes via the extracellular signal-regulated kinase pathway.

1. The aims of the present study were to determine whether delta-opioid receptor stimulation enhanced proliferation of and to investigate the role of the extracellular signal-regulated kinase (ERK) pathway in ventricular myocytes from neonatal rats. 2. At concentratins ranging from 10 nmol/L to 10 micromol/L, [D-Ala2,D-Leu5]enkephalin (DADLE) concentration-dependently promoted myocardial growth and DNA synthesis and altered the cytoskeleton. 3. At 1 micromol/L, DADLE also increased the expression and phosphorylation of ERK. 4. These effects of 1 micromol/L DADLE were abolished by 10 micromol/L naltrindole, a selective delta-opioid receptor antagonist, 10 nmol/L U0126, a selective ERK antagonist, 1 micromol/L staurosporine, an inhibitor of protein kinase (PK) C, and 100 micromol/L Rp-adenosine 3',5'-cyclic monophosphorothioate triethylammonium salt hydrate (Rp-cAMPS), an inhibitor of PKA. 5. In conclusion, delta-opioid receptor stimulation enhances the proliferation and development of the ventricular myocytes of neonatal rats. The ERK pathway and related signalling mechanisms, namely PKC and PKA, are involved.

[Genetic polymorphism of 15 STR loci in Tibetan population].

The polymorphism distributions of 15 STR loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, VWA, TPOX, D18S51, D5S818, and FGA) were investigated in a Tibetan population by multiplex PCR amplification using five fluorochromes (6FAM, VIC, NED, PET, LIZ). Gene frequency, discrimination power (DP), heterozygosity (H), polymorphism information content (PIC) and probability of paternity exclusion (EPP) were calculated, and all loci were tested for Hardy-Weinberg equilibrium. Results indicate that the gene frequency of these 15 STR loci is in Hardy-Weinberg equilibrium. The DP is at 0.7555-0.9602, H is at 0.5651-0.8530, PIC is at 0.5528-0.8456, and EPP is at 0.3811-0.8549. Cumulative DP of the 15 STR is 0.99999999, and cumulative EPP is 0.999999997. Therefore, these 15 STR loci can be used as genetic markers of Tibetan populations in anthropological studies, linkage analysis of genetic diseases, individual identification and paternity testing in forensic medicine.

Transport mechanisms for the uptake of organic compounds by rice (Oryza sativa) roots.

Uptake of six organic compounds, dinitrobenzene (DNB), dinitrotoluene (DNT), lindan (LIN), 1,2,3-triclorobenzene (TCB), phenanthrene (PHN) and pyrene (PYR) by freshly excised rice roots and dead rice roots (heated for 40min at 105 degrees C) were investigated. Results indicated that the uptake by the two types of roots did not increase proportionally with those in external solution. There appears to be some special chemical function of root cells other than simple absorption by the cells. The contribution of this special function can be roughly estimated by deducting the partition uptake into cells from the total uptake. Both time-dependent uptake data and concentration-dependent uptake curves demonstrate that, DNT and DNB transport is achieved presumably mainly via the symplastic pathway, while PHN and PYR transport mainly via the apoplastic pathway. For LIN and TCB, apoplastic transport pathway plays major roles in the first 2h of uptake, then symplastic transport pathway dominates uptake.

Effects of exposure time and co-existing organic compounds on uptake of atrazine from nutrient solution by rice seedlings (Oryza sativa L.).

Root uptake of atrazine (ATR) by rice seedlings (Oryza sativa L.) from nutrient solution was investigated with exposure periods of 48, 96, and 240h. A similar ATR uptake was carried out with two co-existing organic compounds (o-chlorophenol (CP) and 2,4-dichlorophenol (DCP)) with 48h exposure. In contact with the seedlings, the ATR level in nutrient solution decreased sharply during the early exposure and then reached relatively steady levels after 48h. It was observed that the ATR levels within whole seedlings approached the estimated equilibrium partition limits in about 48h, according to the partition-limited model utilizing the measured plant water and organic matter contents and the ATR partition coefficients with whole seedlings. However, when roots and shoots were consisted separately, the detected ATR levels in roots were lower than estimated equilibrium limit while the levels in shoots exceeded the equilibrium limit. The data with roots suggested the occurrence of rapid ATR degradation in roots. The results with shoots are intrinsically consistent with the suggested complex formation of ATR with free metal ions in shoots. The ATR levels in roots and shoots varied to a moderate extent when the seedlings were exposed to different levels of ATR-CP-DCP mixtures. The variation results presumably from the interference of coexisting CP and DCP and the phytotoxicity of the mixed chemicals.

[Progress in animal models for inherited cataract].

Cataract is a serious public health problem. It is usually inherited as an autosomal dominant trait, although autosomal recessive and X-linked inheritance are seen less commonly. With the development of molecular biology techniques, a large number of inherited cataract models are produced, which will reveal the pathogenesis of cataracts and provide a new view for the development and physiology of the lens. In addition, these models also facilitate our understanding of the manner of inheritance, the effect of the environment and nutrition on the lens and provide clues for the diagnosis and treatment of cataracts. Here we presented the relative genes of the animal models for inherited cataract, mutation forms and its progress.

Bioconcentration of atrazine and chlorophenols into roots and shoots of rice seedlings.

Accumulation of o-chlorophenol (CP), 2,4-dichlorophenol (DCP), and atrazine (ATR), as single and mixed contaminants, from hydroponic solutions into roots and shoots of rice seedlings was studied following 48-h exposure of the plant roots. As single contaminants at low levels, the observed bioconcentration factors (BCFs) of CP and DCP with roots approximated the equilibrium values according to the partition-limited model. The BCF of atrazine with roots was about half the partition limit for unknown reasons. The BCFs of CP and ATR with shoots also approximated the partition limits, while the BCF for more lipophilic DCP with shoots was about half the estimated limit, due to insufficient water transport into plants for DCP. As mixed contaminants at low levels, the BCFs with both roots and shoots were comparable with those for the single contaminants; at high levels, the BCFs generally decreased because of the enhanced mixed-contaminant phytotoxicity, as manifested by the greatly reduced plant transpiration rate.

[Relationship between MC4R gene polymorphyism and body weight trait in beagle dogs].

The relationship between MC4R gene polymorphism and body weight in beagle dogs was analyzed. Using gene-specific primers based on canine MC4R exonic sequences a gene fragment was PCR amplified, cloned and sequenced to identify potential polymorphisms. The relationship between a MC4R gene polymorphism detected by PCR-RFLP and canine body weight was analyzed. Three variants were found in beagle dog MC4R DNA sequence, of which two were deletions and one was a transversion which created a PshA I site that could be detected by PCR-RFLP. A statistically significant relationship between this polymorphism and body weight was found. MC4R gene could be a candidate modifier gene for canine body weight.

[Genetic polymorphism of 15 STR loci in a Lhasa Tibetan population].

The polymorphism distributions of 15 STR loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, VWA, TPOX, D18S51, D5S818 and FGA) were investigated in a Lhasa Tibetan population by multiplex PCR amplification using five fluorochromes (6FAM, VIC, NED, PET, LIZ). Gene frequency, discrimination power (DP), heterozygosity (H), polymorphism information content (PIC) and probability of paternity exclusion (EPP) were calculated, and all loci were tested for Hardy-Weinberg equilibrium. Results indicate that the gene frequency of these 15 STR loci is in Hardy-Weinberg equilibrium. The DP is at 0.7515 - 0.9599, H is at 0.5576 - 0.8538, PIC is at 0.5455 - 0.8458, and EPP is at 0.37550.8520. Cumulative DP of the 15 STR is 0.99999999, and cumulative EPP is 0.999999997. Therefore, these 15 STR loci can be used as genetic markers of in Lhasa Tibetan populations in anthropological studies, linkage analysis of genetic diseases, individual identification and paternity testing in forensic medicine.

Interaction between cadmium and atrazine during uptake by rice seedlings (Oryza sativa L.).

The uptake of atrazine by rice seedlings (Oryza sativa L.) through plant roots from nutrient solution was investigated in the presence and absence of Cd2+ over an exposure period of four weeks. It was found that both atrazine and Cd2+ were toxic to rice seedlings. Both shoot and root biomasses decreased when the seedlings were exposed to increasing atrazine or Cd2+ concentrations in nutrient solutions. In the absence of Cd2+, a linear relationship was observed between atrazine concentrations in roots/shoots and in external solution, and more atrazine is concentrated in roots than in shoots. When atrazine and Cd2+ concentrations in solution were maintained at mole ratio of 1:1, the accumulation of atrazine by seedlings was less and the seedling biomass was greater than found with other ratios, such as 1:2 or 2:1. Therefore, the formation of the complex between atrazine and Cd2+ reduced the individual toxicities. Analyses of data with the quasi-equilibrium partition model indicated that the atrazine concentrations in rice seedlings and external water were close to equilibrium. In the presence of Cd2+, however, the measured bioconcentration factor (BCF) of atrazine with roots and shoots were considerably greater. The latter findings resulted presumably from the atrazine-Cd2+ complex formation that led to a large apparent BCF.

Influence of lead on atrazine uptake by rice (Oryza sativa L.) seedlings from nutrient solution.

BACKGROUND: Atrazine is a widely used herbicide, and its persistence in soil and water causes environmental concerns. In the past, plant uptake processes are mainly investigated for single contaminants. However, in many cases, contaminants co-exist in environmental matrix, such as soil, and plant uptake of one contaminant may be influenced by its co-existing ones. METHODS: The uptake of atrazine by rice seedlings (Oryza sativa L.) from nutrient solution through the roots was investigated in a solution culture, over an exposure period of 4 weeks. Atrazine accumulation in plant tissues was determined by gas chromatography, and lead was determined using atomic absorption spectrometry. RESULTS AND DISCUSSION: With different ratios of atrazine and Pb2+ concentrations in solution, the observed atrazine concentrations in shoots and roots varied significantly. In atrazine-Pb2+ mixture systems, the added Pb2+ either increased or decreased the concentrations or BCFs of atrazine in seedlings (relative to those without Pb2+), depending on the atrazine-Pb2+ ratio in nutrient solution. The enhanced atrazine uptake results presumably from atrazine-Pb2+ complex formation. The reduced atrazine uptake, which occurred mainly at high atrazine concentrations, is attributed to atrazine toxicity that inhibited seedling growth and transpiration. CONCLUSION: The formation of atrazine-Pb2+ complex both in the solution and within plant tissues may affect the accumulation of both contaminants by rice plants.

[Mapping quantitative trait loci for fat deposition in carcass in pigs].

One of the major determining factors in the price of market hogs today is backfat depth. Therefore, identification of regions of the genome affecting this trait is necessary. Gene-mapping technologies have provided scientists the necessary reagents to conduct genomewide searches for genes affecting any phenotype determined in part by the genetic makeup of the animal. Over the past few years, several experimental crosses have been used to detect quantitative triat loci (QTL) for fatness and meat quality traits in pigs. In an intercross between Large White and Meishan pigs, 81 F2 progenies in 1998 were slaughtered and phenotyped for fat deposite traits. F2 animals, their parents, and their grandparents were typed for molecular markers covering chromosomes (SSC) 1,2,3,4,6 and 7, since previous studies had revealed QTL affecting fatness traits on these chromosomes. Linear model and least square analyses were used for mapping these traits. Furthermore, a QTL accounting for imprinting effects was used. A total of 14 QTL at chromosome-wide level were detected on SSC1, 3-4, 6 and 7 for 12 fatness traits. There were evidences for imprinting effects on SSC7 for four traits at 60 cM and nearby. There were QTL for average backfat thickness (BFT) on SSC1, 4 and 7. Among them, BFT QTL on SSC1 and 7 may be the common locus for Sus scrofa. QTL for internal fat percentage was on SSC7 and QTL for average sidefat on SSC6.

[The construction of the genetic map and QTL locating analysis on chromosome 2 in swine].

The study constructed the genetic linkage map of porcine chromosome 2 and further analysis of quantitative trait loci was conducted. The results of the study demonstrated that all 7 microsatellite loci we chose were with relatively high polymorphism, and its polymorphic information content was from 0.40182 to 0.58477. The genetic map we constructed for resource family was 152.9 cM in length, with the order of all loci highly consistent with the USDA map. All marker intervals were longer than USDA map with the interval between marker Sw2516 and Sw1201 as an exception. Furthermore, we conducted QTLs locating analysis by combining the genetic map with the phenotypic data. QTLs affecting lively estimated traits such as lean meat percentage, were located at 60-65 cM on chromosome 2, while QTLs for the height and marbling of Longissmus dorsi muscle were located at 20 cM and 55 cM, respectively Among them, QTL for estimated lean meat percentage was significant at chromosome-wise level (P < 0.01) and was responsible for 21.55% of the phenotypic variance. QTLs for the height and marbling of Longissmus dorsi muscle were responsible for 10.12% and 10.97% of the phenotypic variance, respectively. The additive and dominance effect of lively estimated traits were in the inverse tendency, while the QTL for the height of Longissmus dorsi muscle had its additive and dominance effect in the same tendency and was with advantageous allele in Large White. The QTLs we detected had relatively large effect on phenotype and built a basis for molecular marker assisted selection and breeding.

[Mapping quantitative trait loci for meat quality trait in a Large White x Meishan cross].

To search for the chromosome regions for quantitative trait loci (QTL) affecting meat quality in pigs, a three-generation resource family was developed in China using three Large White grand sires and seven Meishan grand dams. A total of 147 F2 progenies derived from two populations in 1998 (n = 81) and 2000 (n = 66) were phenotyped for meat quality. All animals were typed for 48 microsatellite markers covering six chromosomes: 1, 2, 3, 4, 6 and 7. Linear model and least square analyses were used for interval mapping meat quality in jointed population and single population, permutation for empirical threshold. The strongest linkage at chromosome-wide level (P < 0.01) and genome-wide level (P < 0.05) on chromosome 4 affecting intramuscular fat (IMF) QTL from the population in 2000 was detected with explained phenotypic variance of 5.24%, and Meishan's QTL increased the intramuscular fat content. There was a suggestive QTL for IMF near the threshold of chromosome-wide in the same region in jointly population. The QTL for pH value in m. Semispinalis Capitis and m. Biceps Femoris were located on chromosomes 1 and 3, respectively. One and three QTL affecting WHC reached the thresholds of chromosome-wide level in the populations of 1998 and 2000, respectively. In the population of 1998, QTL for moisture content at chromosome-wide level was on SSC6 and in jointed populations were on SSC2, 6 and 7. There were imprinting effects in moisture content QTL, and Meishan and Large White pigs all had favorable effects influencing moisture on different chromosomes.

[Construction of linkage map of chromosomes 1 and 3 in large white x Meishan reference family].

A three-generation family of pigs has been constructed by using three Large White boars and seven sows of Meishan pigs as parents. In this family, five F1 males and twenty-three F1 females were intercrossed to generate 147 F2 offspring. According to the pig linkage map of USDA-MARC, eight and nine microsatellite markers selected on chromosomes 1 and 3 were chosen to span the entire chromosomes. The members of this family were genotyped. The characterization of these microsatellites was shown that they were polymorphic and could be used to construct linkage map and detect quantitative trait loci (QTLs). Linkage analyses were performed using the CRI-MAP software package. The lengths of the sex-averaged linkage map were 182.3 cM and 180.2 cM on chromosomes 1 and 3, respectively. There were some differences between the linkage maps in this study and of USDA-MARC. The linkage map of chromosome 1 in female was found to be shorter than in male, and the contrary was on chromosome 3.

[Detection of quantitative trait loci for growth in large white x Meishan intercross].

The development of molecular biology techniques and the application of these techniques to farm animals have progressed rapidly and have opened new vistas for investigators wishing to identify genes that control quantitative traits. Now that a comprehensive map has been developed for the porcine genome, genomic scans to detect quantitative trait loci (QTL) can begin. In order to locate the genetic regions in the swine genome that are responsible for economically important traits, a resource population was developed by intercross with three Large White and seven Meishan pigs. In subsequent generations, 66 F2 offsprings in 2000 were recorded for four growth traits including birth weight (BWT), body weight at 60 day (WT60), average daily gain from birth to 60 day (ADG1) and average daily gain from 60 day to the end of test (ADG2), and genotyped for 48 microsatellite markers spanning six chromosomes. Association analyses were performed using interval mapping by regression under an outbred line-cross model on chromosomes 1, 2, 3, 4, 6 and 7. The F threshold values were determined by permutation. A total of 12 QTL were detected at suggestive level for the four traits evaluated in this study. Of the 12 suggestive QTL, 3 and 1 QTL were significant at the chromosome-wise and genome-wise levels. There was a QTL for ADG2 at genome-wide level on chromosome 4 explained additive variance 2.19%. A chromosome-wide QTL affecting ADG1 and WT60 were detected on chromosomes 2 and 1 explained additive variance 0.01% and 26.01%, respectively.

[Construction of forward and reverse subtracted cDNA libraries between muscle tissue of Meishan and Landrace pigs].

Using suppression subtractive hybridization (SSH) technique, forward and reverse subtracted cDNA libraries were constructed between Longissimus muscles from Meishan and Landrace pigs. A housekeeping gene, G3PDH, was used to estimate the efficiency of subtractive cDNA. In two cDNA libraries, G3PDH was subtracted very efficiently at appropriate 2(10) and 2(5) folds, respectively, indicating that some differentially expressed genes were also enriched at the same folds and the two subtractive cDNA libraries were very successful. A total of 709 and 673 positive clones were isolated from forward and reverse subtracted cDNA libraries, respectively. Analysis of PCR showed that most of all plasmids in the clones contained 150-750 bp inserts. The construction of subtractive cDNA libraries between muscle tissue from different pig breeds laid solid foundations for isolating and identifying the genes determining muscle growth and meat quality, which will be important to understand the mechanism of muscle growth, determination of meat quality and practice of molecular breeding.