Rice phenolics efflux transporter 2 (PEZ2) plays an important role in solubilizing apoplasmic iron

Iron (Fe) is an essential micronutrient for plants; however, despite its abundance in soils it is not readily available in neutral to alkaline soils. Plants secrete phenolics, such as protocatechuic acid (PCA) and caffeic acid (CA), to absorb and utilize precipitated apoplasmic Fe from root surfaces. However, the synthesis and secretion of phenolics have not been well characterized in plants. We have identified and characterized a rice (Oryza sativa L.) mutant with reduced amounts of PCA and CA in xylem sap and root exudates; hence we named it phenolics efflux zero 2 (pez2). PEZ2 localized to the plasma membrane in onion (Allium cepa L.) epidermal cells and transported PCA when expressed in Xenopus laevis oocytes. PEZ2 expression was observed in whole root near root tips. Similarly, strong expression was observed in leaves. In line with reduced amounts of PCA and CA in xylem sap, the xylem Fe concentration was also low in pez2 plants. These results suggest that PEZ2 is involved in solubilization of apoplasmic Fe in rice.     

Influence of soil-drying under field conditions on exchangeable manganese,cobalt, and copper contents

Abstract

The changes in the exchangeable Mn (Ex-Mn), exchangeable Co (Ex-Co), and exchangeable Cu (Ex-Cu) contents by air-drying of soils were reported in our previous paper. The drying effect, however, was not analyzed in the field. The objective of this study was to investigate the influence of soil-drying under field conditions on Ex-Mn, Ex-Co, and Ex-Cu levels. Two paddy soils (Tsukuba and Yawara) were collected at four different soil depths (0?1, 1?5, 5?10, and 10?20 cm) under three different soil moisture conditions i.e., after harvest, after successive sunny days and after rainy days. After sunny days, Ex-Mn and Ex-Co contents in the surface soil layer markedly increased and drastically decreased after rainfall, while they remained almost unchanged in the lower soil layers. Ex-Cu contents slightly increased in the surface soil layer after sunny days. A similar tendency was observed in soil column experiments. The contents of Ex-Mn, Ex-Co, and Ex-Cu increased 12, 12, and 2 times in the upper layer of soil columns that had been sampled from the Yawara field and stored in a dark room for 8 d. The increase of the Ex-Mn and Ex-Co contents in the upper layer could not be explained by the capillary rise of soil water from the lower layers of the columns. In a soil-drying experiment under laboratory conditions, Ex-Mn and Ex-Co contents began to increase when the water content of the Yawara soil was lower than 0.09?0.13 kg kg^?1. The water content of the surface soil of the Yawara field after sunny days was 0.08 kg kg^?1. Ex-Cu content did not change apprecially with the water content. It is concluded that the increase of the Ex-Mn and Ex-Co levels in field surface soils after sunny days can be ascribed to soil-drying. Some of the excess Ex-Mn and Ex-Co is expected to leach down into lower layers due to rain, which may contribute to plant uptake of Mn and Co.     

Detection of Tobamoviruses from Soils by Non-precoated Indirect ELISA

A method for detecting tobamoviruses from field soils was developed using non-precoated indirect enzyme-linked immunosorbent assay (Id-ELISA). Absorbance values in Id-ELISA were relatively low after directly applying Pepper mild mottle virus (PMMoV)-infested soil extract. However, heat treating the soil extract before application greatly enhanced the absorbance values. The heat treatment was essential for the Id-ELISA detection of tobamoviruses from infested soil, although the efficiency of virus recovery varied depending on the properties of soil. The number of local lesions in the infectivity assay was consistent with the absorbance values in Id-ELISA. Moreover, the absorbance values in Id-ELISA were correlated with the incidence of soil transmission of PMMoV. Thus, Id-ELISA combined with heat treatment is a practical technique for the diagnosis of infestation with Tobamovirus in field soils, Gray Lowland soil and Sand-dune Regosol. Received 4 October 1999/ Accepted in revised form 9 December 1999     

Comparison of rDNA-ITS Sequences between Potato and Tobacco Strains in <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG-3

Genetic diversity among 51 isolates of Rhizoctonia solani AG-3, representing potato and tobacco populations, was inferred from the sequences of the internal transcribed spacer (ITS) and 5.8S ribosomal RNA (rRNA) gene. The 5.8S rDNA sequence was completely conserved not only in AG-3, but across all the AG isolates examined, whereas the rDNA-ITS sequence was found to be variable among the isolates. The nucleotide sequence similarity in the ITS 1 region was high (96-100%) for isolates within each of the two populations, but was 91-92% for isolates from different populations. The AG-3 isolates had 56 to 91% sequence similarities in the ITS 1 region with R. solani isolates of the other AGs. Phylogenetic analysis based on the ITS-5.8S rDNA sequence data indicated that the different populations in AG-3 are distantly related to each other. Genetic divergence between the two populations was also supported by the results of DNA-DNA hybridization studies. This study suggests that AG-3 consists of two genetically isolated groups corresponding to separate subgroups: AG-3 PT (potato type) and AG-3 TB (tobacco type). Specific primer sets for the detection of the two AG-3 subgroups were developed from the aligned rDNA-ITS sequences. Received 22 April 1999/ Accepted in revised form 2 July 1999     

鱼类生殖细胞移植的研究进展及应用前景

生殖细胞移植是指将供体的生殖细胞移植到同种或异种受体体内,供体生殖细胞嵌合到受体性腺,经过增殖、分化并最终发育为功能性配子的过程。作为辅助生殖技术,它不仅为珍稀濒危动物的繁育和保护提供了新途径,同时也为生殖干细胞的功能研究提供了有效手段。鱼类生殖细胞移植研究首先在模式鱼类斑马鱼中开展,经过十多年的发展,取得了一系列突破性的进展:主要包括先后建立了以胚胎、仔鱼和成鱼为受体的生殖细胞移植体系,精原和卵原干细胞的发现拓宽了供体生殖细胞的选择,受体的选择与制备方法的完善。该技术在缩短鱼类性成熟周期、性控育种、珍稀濒危鱼类保护等方面具有巨大的应用前景,已成功在多种淡水和海水鱼类中开展了研究和应用。本文结合作者的研究实践和经验,系统地梳理和总结了鱼类生殖细胞移植的研究进展,指出了该技术实践应用的关键问题,并探讨了其应用前景。     

Response to mitogens of chicken splenocytes determined by three methods of measurement

The aim of the present study was to examine whether the 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyl tetrazolium bromide (MTT) colorimetric assay can be applied to measurement of mitogen‐induced chicken splenocyte activation. Activation was also measured by a ³H‐thymidine uptake assay and a viable cell count assay. Optimal concentrations of mitogens and incubation periods required for maximal responses to mitogens differed between the MTT assay and the viable cell count and thymidine uptake assays. This probably reflects differences in the activities measured by the MTT assay which detects mitochondrial enzyme activity, and the thymidine uptake and viable cell count assays which detect cellular proliferation activity. The validity of the MTT assay was supported by the observation that the mitogen‐induced increase in succinate dehydrogenase activity paralleled the level of mitogen‐induced MTT formazan production. Mitogen concentrations inducing maximal formazan formation in chicken splenocytes were higher than those for chicken peripheral blood lymphocytes reported previously. Results of the present study indicate that mitogen‐induced chicken splenocyte activation could be measured by the MTT colorimetric assay, although mitogen concentrations and incubation periods required for maximal splenocyte activation differed between the MTT assay and the other two assays used in this study.     

Differential expression of myostatin and its receptor in the porcine anterior pituitary gland

Myostatin (MSTN), known as growth and differentiation factor 8 (GDF-8), is a member of the transforming growth factor β (TGF-β) superfamily that negatively regulates skeletal muscle mass. Myostatin binds with high affinity to the receptor serine threonine kinase activin receptor type IIB (ActRIIB). Activins that also belong to the TGF-β superfamily, stimulate follicle-stimulating hormone production in gonadotrophs and suppress growth hormone and adrenocorticotropic hormone production in somatotrophs and corticotrophs, respectively. The aim of the present paper was therefore to clarify the endocrine action of MSTN in adenohypophysis. The present study details the expression and cellular localization of MSTN and ActRIIB in porcine anterior pituitary gland. The mRNA of MSTN and ActRIIB was consistently expressed in RT-PCR. Immunohistochemistry of MSTN and specific hormones showed that MSTN localized in thyrotrophs and gonadotrophs, in which most of the MSTN immunoreactive cells were identified as thyrotrophs. The immunostaining of ActRIIB was restricted to corticotrophs. These results indicate that MSTN was mainly produced in thyrotrophs and its receptor, ActRIIB, was restrictively contained in corticotrophs. Interestingly, thyrotrophs immunoreactive for MSTN were frequently close to corticotrophs immunoreactive for ActRIIB. The present study suggests that MSTN from thyrotrophs may regulate corticotroph function as a paracrine mediator among the porcine anterior pituitary cells.     

Disease Resistance of Tissue-cultured Seedlings of Rhododendron after Treatment with Streptomyces sp. R-5

An endophytic actinomycete, Streptomyces sp. R-5, which had been isolated from a field-grown rhododendron plant, was used to protect rhododendron seedlings in tissue culture from Pestalotia disease caused by Pestalotiopsis sydowiana. R-5 had intense antagonistic activity against P. sydowiana without adversely affecting the seedlings in glass flasks. A suspension of R-5 was spread on the surface of the multiplication medium in glass flasks in which seedlings were growing. Ten days later, the 4th upper leaf of seedlings was inoculated with P. sydowiana and incubated for 14 days. In controls untreated with R-5, substrate mycelia of P. sydowiana grew on all leaves and stems above and below the 4th leaf within 2–3 days of inoculation. Such growth resulted in the wilting death of 54% of seedlings by 14 days. In contrast, only the inoculated leaves turned brown in ca. 90% of seedlings growing on medium treated with R-5. None of these seedlings died. Thus, treatment of the medium surface with R-5 efficiently protects the seedlings from infection by P. sydowiana. Scanning electron microscopy revealed that substrate mycelia of R-5 grew on and beneath the cuticle of leaves of the treated seedlings. Fluorescent microscopy showed that R-5 was also inside the leaves. Received 8 June 2001/ Accepted in revised form 4 July 2001     

Development of a genotyping tool for a functionally relevant CYP2C19 allele (Phe100Asn,Ala103Val and Ile112Leu) in cynomolgus macaques

In cynomolgus macaques, which are widely used in drug metabolism studies, CYP2C19 (formerly known as CYP2C75) is abundantly expressed in liver, metabolizes human CYP2C substrates and is thus an important drug-metabolizing enzyme. One of the cynomolgus CYP2C19 alleles (p.Phe100Asn, p.Ala103Val and p.Ile112Leu) results in substantially reduced metabolic activity and thus is an important allele in drug metabolism studies. For this allele, a genotyping tool was developed using allele-specific TaqMan probe. Genotyping 40 Cambodian cynomolgus macaques using this tool found 1 homozygote, 17 heterozygotes and 22 wild type animals, and the result was confirmed by direct-sequencing. Interestingly, this allele frequency was similar to that of Chinese cynomolgus macaques. The genotyping tool established is useful for drug metabolism studies using cynomolgus macaques.