Complete Genome Sequence of Corynebacterium pseudotuberculosis Strain 1/06-A, Isolated from a Horse in North America

Corynebacterium pseudotuberculosis causes disease in several animal species, although distinct biovars exist that appear to be restricted to specific hosts. In order to facilitate a better understanding of the differences between biovars, we report here the complete genome sequence of the equine pathogen Corynebacterium pseudotuberculosis strain 1/06-A.     

Applications of real-time thermoregulatory models to occupational heat stress: validation with military and civilian field studies

A real-time thermoregulatory model using noninvasive measurements as inputs was developed for predicting physiological responses of individuals working long hours. The purpose of the model is to reduce heat-related injuries and illness by predicting the physiological effects of thermal stress on individuals while working. The model was originally validated mainly by using data from controlled laboratory studies. This study expands the validation of the model with field data from 26 test volunteers, including US Marines, Australian soldiers, and US wildland fire fighters (WLFF). These data encompass a range of environmental conditions (air temperature: 19-30° C; relative humidity: 25-63%) and clothing (i.e., battle dress uniform, chemical-biological protective garment, WLFF protective gear), while performing diverse activities (e.g., marksmanship, marching, extinguishing fires, and digging). The predicted core temperatures (Tc), calculated using environmental, anthropometric, clothing, and heart rate measures collected in the field as model inputs, were compared with subjects' Tc collected with ingested telemetry temperature pills. Root mean standard deviation (RMSD) values, used for goodness of fit comparisons, indicated that overall, the model predictions were in close agreement with the measured values (grand mean of RMSD: 0.15-0.38° C). Although the field data showed more individual variability in the physiological data relative to more controlled laboratory studies, this study showed that the performance of the model was adequate.     

Seasonal fluctuation in susceptibility to insecticides within natural populations of Drosophila melanogaster. II. Features of genetic variation in susceptibility to organophosphate insecticides within natural populations of D. melanogaster

To elucidate genetic variation in susceptibility to organophosphate insecticides within natural populations of Drosophila melanogaster, we conducted an analysis of variance for mortality data sets of isofemale lines (10-286 lines) used in the previous studies. Susceptibility of isofemale lines to the three organophosphate insecticides was continuously distributed within each natural population, ranging from susceptible to resistant. Analysis of variance showed highly significant variation among isofemale lines in susceptibility to each insecticide for each natural population. Significant genetic variances in susceptibility to the three chemicals were estimated for the Katsunuma population; 0.0529-0.2722 for malathion, 0.0492-0.1603 for prothiophos, and 0.0469-0.1696 for fenitrothion. Contrary to the consistent seasonal tendency towards an increase in mean susceptibility in the fall, reported in the previous study, genetic variances in susceptibility to the three organophosphates did not change significantly in 1997 but tended to increase by 2- to 5-times in 1998. We tested whether both the observed situations, maintenance and increase in genetic variance in organophosphate resistance, can be generated under circumstances in which the levels of resistance to the three organophosphates tended to decrease, by conducting a simulation analysis, based on the hypothesis that resistant genotypes have lower fitnesses than susceptible ones under the density-independent condition. The simulation analysis generally explained the pattern in the mean susceptibility and genetic variances in susceptibility to the three organophosphates, observed in the Katsunuma population of D. melanogaster. It was suggested that the differences in the frequencies of resistance genes in the summer population could affect the patterns in genetic variance in organophosphate resistance in the fall population.     

Loss-of-Function Mutations of Retromer Large Subunit Genes Suppress the Phenotype of an Arabidopsis zig Mutant That Lacks Qb-SNARE VTI11

Arabidopsis thaliana zigzag (zig) is a loss-of-function mutant of Qb-SNARE VTI11, which is involved in membrane trafficking between the trans-Golgi network and the vacuole. zig-1 exhibits abnormalities in shoot gravitropism and morphology. Here, we report that loss-of-function mutants of the retromer large subunit partially suppress the zig-1 phenotype. Moreover, we demonstrate that three paralogous VPS35 genes of Arabidopsis have partially overlapping but distinct genetic functions with respect to zig-1 suppression. Tissue-specific complementation experiments using an endodermis-specific SCR promoter show that expression of VPS35B or VPS35C cannot complement the function of VPS35A. The data suggest the existence of functionally specialized paralogous VPS35 genes that nevertheless share common functions.     

Vacuolar/pre-vacuolar compartment Qa-SNAREs VAM3/SYP22 and PEP12/SYP21 have interchangeable functions in Arabidopsis

SNAREs (soluble N-ethylmaleimide sensitive factor attachment protein receptors) mediate specific membrane fusion between transport vesicles or organelles and target membranes. VAM3/SYP22 and PEP12/SYP21 are Qa-SNAREs that act in the vacuolar transport pathway of Arabidopsis thaliana, and are localized predominantly on the vacuolar membrane and the pre-vacuolar compartment (PVC), respectively. Previous studies have shown that loss-of-function mutants of VAM3/SYP22 or PEP12/SYP21 showed male gametophytic lethality, suggesting that VAM3/SYP22 and PEP12/SYP21 possess different, non-redundant functions. We have re-evaluated the effects of mutations in these genes using T-DNA insertion mutants in the Columbia accession. We found that a mutation in VAM3/SYP22 (vam3-1) caused pleiotropic abnormalities, including semi-dwarfism and wavy leaves. In contrast, a loss-of-function mutant of PEP12/SYP21 (pep12) showed no apparent abnormal phenotype. We also found that the double vam3-1 pep12 mutant had severely reduced fertilization competence, although male and female gametophytes (vam3-1(-) pep12(-) ) maintained the ability to fertilize. Moreover, promoter swapping analysis revealed that expression of a GFP-PEP12/SYP21 fusion under the control of the VAM3/SYP22 promoter suppressed all phenotypes of the vam3-1 mutant. These results indicate that the functions of VAM3/SYP22 and PEP12/SYP21 were redundant and interchangeable.     

Conspicuous Growth of Intravenously Inoculated Staphylococcus aureus in Subcutaneously Established Ehrlich Ascites Tumor Tissue of Mice

Intratumoral growth of Staphylococcus aureus was compared with the intrarenal growth, to examine the usefulness of the method as a marker of its pathogenicity. When 5 × 10⁷ CFU/mouse of three derivatives from S. aureus Cowan I with different intrarenal growth were intravenously injected into Ehrlich tumor-bearing mice, they lodged in the tumor tissue at approximately 10³ CFU/0.1 g by 30 min after infection, and grew in the range of 10⁶ CFU/0.1 g to 10⁸ CFU/0.1 g by day 4, regardless of their intrarenal growth capacity. In contrast, S. saprophyticus lodged in both tissues to the same degree as S. aureus, but did not grow at all. The time course of the staphylococcal growth was different between tumor tissue and kidney, suggesting differences in the local responses against S. aureus.     

Contributions of three-site mutations in acetylcholinesterase and cytochrome P450 to genetic variation in susceptibility to organophosphate insecticides within a natural population of Drosophila melanogaster

In this study, we attempted to elucidate the two resistance factors conferring resistance to organophosphates within the Katsunuma population of Drosophila melanogaster (Meigen), one of which has been mapped on the second chromosome and the other on the third chromosome. With regard to the second chromosome factor, we tested susceptibility to malathion of 54 recombinant inbred lines with recombination between ltd and vg. Analyses of variance (ANOVAs) showed highly significant variation in susceptibility to malathion between recombinant lines. In addition, susceptibility of the second-chromosome resistant line to malathion was increased with additional application of piperonyl butoxide, suggesting a member of the Cyp gene family located between ltd and vg. With regard to the third-chromosome factor, we conducted inhibition assays of acetylcholinesterase (AChE) with respect to fenitroxon and carbaryl, to evaluate the contribution of mutated AChE to organophosphate resistance within the Katsunuma population. I ₅₀ values of resistant lines, isolated from this population, were about 15 times higher for fenitroxon, and about two times higher for carbaryl, than those of susceptible lines, suggesting the contribution of mutated AChE to organophosphate resistance within the Katsunuma population. We further investigated the genetic variation in the acetylcholinesterase (Ace) gene within the newly collected Katsunuma population, by using the allele-specific polymerase chain reaction (PCR) approach, and revealed that within this population there were high frequencies of resistant-type mutations at three sites in the Ace gene, which play critical roles in altering sensitivity of AChE to organophosphate and carbamate insecticides.     

Micromanipulation of amyloplasts with optical tweezers in Arabidopsis stems

Intracellular sedimentation of highly dense, starch-filled amyloplasts toward the gravity vector is likely a key initial step for gravity sensing in plants. However, recent live-cell imaging technology revealed that most amyloplasts continuously exhibit dynamic, saltatory movements in the endodermal cells of Arabidopsis stems. These complicated movements led to questions about what type of amyloplast movement triggers gravity sensing. Here we show that a confocal microscope equipped with optical tweezers can be a powerful tool to trap and manipulate amyloplasts noninvasively, while simultaneously observing cellular responses such as vacuolar dynamics in living cells. A near-infrared (λ=1064 nm) laser that was focused into the endodermal cells at 1 mW of laser power attracted and captured amyloplasts at the laser focus. The optical force exerted on the amyloplasts was theoretically estimated to be up to 1 pN. Interestingly, endosomes and trans-Golgi network were trapped at 30 mW but not at 1 mW, which is probably due to lower refractive indices of these organelles than that of the amyloplasts. Because amyloplasts are in close proximity to vacuolar membranes in endodermal cells, their physical interaction could be visualized in real time. The vacuolar membranes drastically stretched and deformed in response to the manipulated movements of amyloplasts by optical tweezers. Our new method provides deep insights into the biophysical properties of plant organelles in vivo and opens a new avenue for studying gravity-sensing mechanisms in plants.