Japanese MAGSAT team

Construction of a model of the regional magnetic field and investigation of the local magnetic anomalies and their origin were approaches used in attempts to study the crustal structure near Japan and its Antarctic bases. Spatial properties of the regional magnetic field and comparison of the regional model with that derived from MAGSAT data are discussed. Possible causes of the magnetic anomalies, and results of aeromagnetic surveys incorporating gravity and seismic data are explored. Ionospheric and magnetospheric contributions to geomagnetic variations, field-aligned currents, magnetic geomagnetic pulsations, and hydromagnetic waves by analysis of MAGSAT data are also examined

Studying internal and external magnetic fields in Japan using MAGSAT data

Examination of the total intensity data of CHRONIT on a few paths over Japan and its neighboring sea shows MAGSAT is extremely useful for studying the local magnetic anomaly. In high latitudes, the signatures of field aligned currents are clearly recognized. These include (1) the persistent basic pattern of current flow; (2) the more intense currents in the summer hemisphere than in the winter hemisphere; (3) more fluctuations in current intensities in summer dawn hours; and (4) apparent dawn-dusk asymmetry in the field-aligned current intensity between the north and south polar regions

Crystal structure of the H256A mutant of rat testis fructose-6- phosphate,2-kinase/fructose-2,6-bisphosphatase: Fructose 6-phosphate in the active site leads to mechanisms for both mutant and wild type bisphosphatase activities

Fructose-6-phosphate,2-kinase/fructose-2,6-bisphosphatase (Fru-6-P,2- kinase/Fru-2,6-Pase) is a bifunctional enzyme, catalyzing the interconversion of β-D-fructose-6-phosphate (Fru-6-P) and fructose-2,6-bisphosphate (Fru- 2,6-P2) at distinct active sites. A mutant rat testis isozyme with an alanine replacement for the catalytic histidine (H256A) in the Fru-2,6-Pase domain retains 17% of the wild type activity (Mizuguchi, H., Cook, P. F., Tai, C-H., Hasemann, C. A., and Uyeda, K. (1998) J. Biol. Chem. 274, 2166- 2175). We have solved the crystal structure of H256A to a resolution of 2.4 Å by molecular replacement. Clear electron density for Fru-6-P is found at the Fru-2,6-Pase active site, revealing the important interactions in substrate/product binding. A superposition of the H256A structure with the RT2K-Wo structure reveals no significant reorganization of the active site resulting from the binding of Fru-6-P or the H256A mutation. Using this superposition, we have built a view of the Fru-2,6-P2-bound enzyme and identify the residues responsible for catalysis. This analysis yields distinct catalytic mechanisms for the wild type and mutant proteins. The wild type mechanism would lead to an inefficient transfer of a proton to the leaving group Fru-6-P, which is consistent with a view of this event being rate-limiting, explaining the extremely slow turnover (0.032 s-1) of the Fru-2,6-Pase in all Fru-6-P,2-kinase/Fru-2,6-Pase isozymes

Growth of melon cultivated under saline stress and potassium doses

O Estado do Rio Grande do Norte, em destaque a região da Chapada do Apodi, se destaca na produção e exportação de melão no País, em regime de irrigação, devido à distribuição pluvial baixa e irregular. A Chapada do Apodi possui dois aqüíferos subterrâneos; a do lençol menos profundo de alta salinidade, porém com menor custo de bombeamento, ocorrendo o contrário com o de maior profundidade. Objetivou-se, ante o exposto, avaliar o efeito de duas águas de salinidades diferentes (0,52 e 2,41 dS m-1), combinadas com cinco doses de K2O (218, 273, 328, 383 e 438 kg ha-1) sobre o crescimento do meloeiro (Cucumis melo L.), cultivar Goldex, utilizando-se do delineamento de blocos ao acaso, com parcelas subdivididas; amostras de planta foram coletadas aos 21, 28, 35, 49 e 63 dias após a semeadura, determinando-se a fitomassa seca das plantas, estas separadas em ramos (caule + folhas), flores e frutos; avaliou-se, também, a taxa de crescimento absoluto e relativo e a produção de frutos. Em geral, o crescimento do melão foi favorecido com o uso de água mais salina; a taxa de crescimento absoluto foi máxima entre 35 e 49 dias após a semeadura. Obteve-se maior produção de fitomassa total com 438 kg ha-1 de K2O e uso de água mais salina, ao final do ciclo.The region of 'Chapada do Apodi', in the State of Rio Grande do Norte, stands out in Brazilian production and exportation of melon. This region possesses two aquiffers, one of lower exploration cost, though of high salinity, another of low salinity, with higher cost and limited use. This work was carried out with the objective to evaluate the effect of waters of different salinities combined with five doses of K in the dry matter accumulation and productivity of the melon (Cucumis melo L.) cultivar Goldex. The experimental design adopted was split plot in completely randomized blocks. The melon crop was irrigated with low (0.52 dS m-1) and high (2.41 dS m-1) salinity water combined with five doses of K2O (218, 273, 328, 383 and 438 kg ha-1). Plants were collected at 21, 28, 35, 49 and 63 days after sowing, and were separated in branches (shoot + leaves), flowers and fruits, and the total dry matter of the aerial parts obtained by summation. The absolute and relative growth rates and the production of fruits were also evaluated. The absolute growth rate of the plant was maximum between 35 and 49 days. The highest total biomass was obtained with 438 kg ha-1 K2O and use of high salinity water at the end of crop cycle.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Structure and properties of ilmenite from first principles

Published versio

Screening and analysis of genes expressed upon infection of broad bean with Clover yellow vein virus causing lethal necrosis

Clover yellow vein virus (ClYVV) causes lethal systemic necrosis in legumes, including broad bean (Vicia faba) and pea (Pisum sativum). To identify host genes involved in necrotic symptom expression after ClYVV infection, we screened cDNA fragments in which expression was changed in advance of necrotic symptom expression in broad bean (V. faba cv. Wase) using the differential display technique and secondarily with Northern blot analysis. Expression changes were confirmed in 20 genes, and the six that exhibited the most change were analyzed further. These six genes included a gene that encodes a putative nitrate-induced NOI protein (VfNOI), and another was homologous to an Arabidopsis gene that encodes a glycine- and proline-rich protein GPRP (VfGPRP). We recently reported that necrotic symptom development in ClYVV-infected pea is associated with expression of salicylic acid (SA)-dependent pathogenesis-related (PR) proteins and requires SA-dependent host responses. Interestingly, VfNOI and VfGPRP expression was correlated with that of the putative SA-dependent PR proteins in ClYVV-infected broad bean. However, broad bean infected with a recombinant ClYVV expressing the VfGPRP protein showed weaker symptoms and less viral multiplication than that infected with ClYVV expressing the GFP protein. These results imply that VfGPRP plays a role in defense against ClYVV rather than in necrotic symptom expression

Berberine Improves Glucose Metabolism in Diabetic Rats by Inhibition of Hepatic Gluconeogenesis

Berberine (BBR) is a compound originally identified in a Chinese herbal medicine Huanglian (Coptis chinensis French). It improves glucose metabolism in type 2 diabetic patients. The mechanisms involve in activation of adenosine monophosphate activated protein kinase (AMPK) and improvement of insulin sensitivity. However, it is not clear if BBR reduces blood glucose through other mechanism. In this study, we addressed this issue by examining liver response to BBR in diabetic rats, in which hyperglycemia was induced in Sprague-Dawley rats by high fat diet. We observed that BBR decreased fasting glucose significantly. Gluconeogenic genes, Phosphoenolpyruvate carboxykinase (PEPCK) and Glucose-6-phosphatase (G6Pase), were decreased in liver by BBR. Hepatic steatosis was also reduced by BBR and expression of fatty acid synthase (FAS) was inhibited in liver. Activities of transcription factors including Forkhead transcription factor O1 (FoxO1), sterol regulatory element-binding protein 1c (SREBP1) and carbohydrate responsive element-binding protein (ChREBP) were decreased. Insulin signaling pathway was not altered in the liver. In cultured hepatocytes, BBR inhibited oxygen consumption and reduced intracellular adenosine triphosphate (ATP) level. The data suggest that BBR improves fasting blood glucose by direct inhibition of gluconeogenesis in liver. This activity is not dependent on insulin action. The gluconeogenic inhibition is likely a result of mitochondria inhibition by BBR. The observation supports that BBR improves glucose metabolism through an insulin-independent pathway