Bradyrhizobium elkanii Induces Outer Cortical Root Swelling in Soybean

When soybean roots were inoculated with Bradyrhizobium elkaniiUSDA76, USDA94 or USDA31, a localized swelling of the root outercortical cells was observed within 10 days after inoculation.This phenotype was designated outer cortical swelling (OCS).OCS was not observed in roots inoculated with B.japonicum USDA110or USDA122. Therefore, the OCS response appears to be specificfor B. elkanii. To determine the involvement of the nodulationgenes in OCS formation, we constructed a nod^- mutant, strainUSDA94     

Discrete subcellular localization of membrane-bound ATPase activity in marine angiosperms and marine algae

The subcellular distribution of membrane-bound ATPases was compared among terrestrial plants, seagrasses and marine algae by cytochemical techniques. High ATPase activity was detected in the copiously invaginated plasma membrane that was characteristic of transfer cells but not in the tonoplast of epidermal cells in mature leaves of seagrasses. Magnesium- or Ca²⁺-dependent ATPase activity was induced together with the characteristics of transfer cells during the development of leaf tissues able to resist seawater. Northern hybridization revealed the effective induction of the synthesis of mRNA for plasma-membrane H⁺-ATPase during the development of leaves. Such high ATPase activity was not detected in the smooth plasma membranes of marine macro-algae but was found in the membranes of some cytoplasmic vesicles or microvacuoles, providing evidence of the excretion of salts by exocytosis. It appears, therefore, that two essentially different methods for excreting excess salts have developed separately in these two classes of marine plants. The evolution of mechanisms of salt tolerance in the plant kingdom is discussed in terms of the differential subcellular distribution of ATPase activity.Abbreviation PCR polymerase chain reaction The authors are grateful to Dr. P. Park of Teikyo University, School of Medicine, and Dr. K. Kasamo, National Institute for Food Sciences, Tsukuba, for their helpful advice. This work was supported by the Japanese Salt Science Research Foundation (No. 9228).     

A Circular Plasmid from the YeastTorulaspora delbrueckii

A new member of the 2-μm family of plasmids, named pTD1, was found in the yeastTorulaspora delbrueckii,a widespread yeast associated with food. Nucleotide sequences revealed the presence of a pair of inverted repeats and three open reading frames, one of which is a homologue of the FLP recombinase gene of 2-μm plasmid. An ARS region was identified, by replication inSaccharomyces cerevisiaeandT. delbrueckii,near one of the inverted repeats. By the use of pTD1 derivatives and auxotrophic mutant hosts, an efficient host–vector system was established forT. delbrueckii.So far, the 2-μm family of plasmids is restricted to four closely related genera (Q6 group):Saccharomyces, Zygosaccharomyces, Kluyveromyces,andTorulaspora.After a survey of 2500 strains belonging to about 500 species (80 genera) of yeast, no circular plasmids were found in other genera.     

Identifying Patients with Bacteremia in Community-Hospital Emergency Rooms: A Retrospective Cohort Study

Objectives

(1) To develop a clinical prediction rule to identify patients with bacteremia, using only information that is readily available in the emergency room (ER) of community hospitals, and (2) to test the validity of that rule with a separate, independent set of data.

Design

Multicenter retrospective cohort study.

Setting

To derive the clinical prediction rule we used data from 3 community hospitals in Japan (derivation). We tested the rule using data from one other community hospital (validation), which was not among the three “derivation” hospitals.

Participants

Adults (age ≥ 16 years old) who had undergone blood-culture testing while in the ER between April 2011 and March 2012. For the derivation data, n = 1515 (randomly sampled from 7026 patients), and for the validation data n = 467 (from 823 patients).

Analysis

We analyzed 28 candidate predictors of bacteremia, including demographic data, signs and symptoms, comorbid conditions, and basic laboratory data. Chi-square tests and multiple logistic regression were used to derive an integer risk score (the “ID-BactER” score). Sensitivity, specificity, likelihood ratios, and the area under the receiver operating characteristic curve (i.e., the AUC) were computed.

Results

There were 241 cases of bacteremia in the derivation data. Eleven candidate predictors were used in the ID-BactER score: age, chills, vomiting, mental status, temperature, systolic blood pressure, abdominal sign, white blood-cell count, platelets, blood urea nitrogen, and C-reactive protein. The AUCs was 0.80 (derivation) and 0.74 (validation). For ID-BactER scores ≥ 2, the sensitivities for derivation and validation data were 98% and 97%, and specificities were 20% and 14%, respectively.

Conclusions

The ID-BactER score can be computed from information that is readily available in the ERs of community hospitals. Future studies should focus on developing a score with a higher specificity while maintaining the desired sensitivity.     

Nuclear Involvement in Localization of the Initiation Site of Surface Contraction Waves in Xenopus Eggs

The initiation site of surface contraction waves (SCWs) was examined in fertilized, parthenogenetically activated and enucleated Xenopus eggs after either rotation through 90° off the vertical axis or injection of colchicine. In enucleated eggs, SCWs always started from a top site of the egg under all conditions examined. In fertilized or activated eggs, SCWs started, depending on the experimental conditions, from either the sperm entry point, the animal pole region located sideward or the top site of the egg. Histological examinations of fertilized and activated eggs revealed that the nucleus was in most cases positioned close to the initiation site of SCWs under various experimental conditions. It is suggested from these results that the egg cytoplasm has an intrinsic capability of causing the surface to generate SCWs, and that the nucleus is generally involved in localizing the initiation site of SCWs in fertilized or activated Xenopus eggs. A possible mechanism for localizing the initiation site of SCWs in Xenopus eggs is proposed.     

Enzymatic production of L-tryptophan from DL-serine and indole by a coupled reaction of tryptophan synthase and amino acid racemase

Enzymatic production of L-tryptophan from DL-serine and indole by a coupled reaction of tryptophan synthase and amino acid racemase was studied. The tryptophan synthase (EC 4.2.1.20) of Escherichia coli catalyzed beta-substitution reaction of L-serine into L-tryptophan and the amino acid racemase (EC 5.1.1.10) of Pseudomonas putida catalyzed the racemization of D-serine simultaneously in one reactor. Under optimal conditions established for L-tryptophan production, a large-scale production of L-tryptophan was carried out in a 200-liter reactor using intact cells of E. coli and P. putida. After 24 h of incubation with intermittent indole feeding, 110 g liter-1 of L-tryptophan was formed in molar yields of 91 and 100% for added DL-serine and indole, respectively. Continuous production of L-tryptophan was also carried out using immobilized cells of E. coli and P. putida. The maximum concentration of L-tryptophan formed was 5.2 g liter-1 (99% molar yield for indole), and the concentration decreased to 4.2 g liter-1 after continuous operation for 20 days.