Seed Production and Maturation of the Western Prairie Fringed Orchid

A population of threatened western prairie fringed orchid (Platanthera praeclara) was selected in 2004 on the Sheyenne National Grassland in southeastern North Dakota to study seed production and maturation for future use in population viability modeling. We randomly collected 30 seed capsules from the population under a permit from the U.S. Fish and Wildlife Service to: 1) identify capsule parameters that might be correlated with seed number and viability, 2) estimate an appropriate sample size to obtain accurate seed production estimates, 3) quantify seed production and viability per seed capsule, and 4) document temporal patterns in seed embryo development. We found that the number of seeds per capsule was weakly correlated with capsule weight (R2 = 0.23, P = 0.04), while the proportion of viable seeds within a capsule was weakly correlated with capsule length (R2 = 0.20, P = 0.01) and capsule circumference (R2 = 0.17, P = 0.04). However, seed production and embryo viability varied extensively in our study to the extent that capsule measurements were not reliable indicators of fecundity or fertility. Our study provides guidance for the sample size required to make statistical inferences regarding seed production and seed viability in western prairie fringed orchid populations. Our data also suggest that orchid seeds undergo maturation up to the time of capsule dehiscence based on increases we observed from August to September in seed weights and proportion of large embryos. Our observations reinforce the importance of moratoriums on grazing and mowing in some areas of orchid habitat until after mid-September

LOW DOSE PPARγ AGONIST INHIBITION OF CYST GROWTH IN THE PCK RAT MODEL OF POLYCYSTIC KIDNEY DISEASE

poster abstractPolycystic kidney diseases (PKD) are genetic disorders characterized by fluid-filled cysts in kidney tubules and liver bile ducts that enlarge during the patient’s life commonly progressing to renal failure in midlife. Cyst enlarge-ment is due in part, to Cl- secretion via the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. Our previous studies demonstrat-ed that PPARγ agonists, insulin-sensitizing drugs used to treat diabetes, in-hibit Cl- secretion by renal collecting duct principal cells via decreased CFTR synthesis. The dose response curves for Cl- transport paralleled the EC50’s for receptor transactivation with a leftward shift, suggesting an increased sensitivity for inhibition of Cl- secretion. Our previous preclinical studies showed that high (20 mg/kg BW) dose pioglitazone, a PPARγ agonist, inhib-ited cyst growth in the PCK rat model, which is orthologous to a human form of PKD. PCK rats were fed a diet containing 3 doses of rosiglitazone (4, 0.4, and 0.04 mg/kg BW) for 24 weeks starting at weaning. 4.0 mg/kg BW rosig-litazone is analogous to 20 mg/kg BW pioglitazone used in the previous study. At the end of the study, urine, serum, kidney, liver, and heart were collected for analysis. There was a significant decrease in total kidney weight, kidney weight as a percent of body weight, and renal cyst volume in the lowest does (0.04 mg/kg BW). There was no significance difference in the other doses, and the liver and heart were not changed significantly. This showed both pioglitazone and rosiglitazone were effective in inhibiting cyst growth in the PCK rat indicating a class action of PPARγ agonists. Important-ly, the rodent data substantiated the previous tissue culture data showing that a very low dose of rosiglitazone is effective in treatment of PKD

The natural space environment: Effects on spacecraft

The effects of the natural space environments on spacecraft design, development, and operation are the topic of a series of NASA Reference Publications currently being developed by the Electromagnetics and Environments Branch, Systems Analysis and Integration Laboratory, Marshall Space Flight Center. This primer provides an overview of the natural space environments and their effect on spacecraft design, development, and operations, and also highlights some of the new developments in science and technology for each space environment. It is hoped that a better understanding of the space environment and its effect on spacecraft will enable program management to more effectively minimize program risks and costs, optimize design quality, and successfully achieve mission objectives

The normal increase in insulin after a meal may be required to prevent postprandial renal sodium and volume losses

Despite the effects of insulinopenia in type 1 diabetes and evidence that insulin stimulates multiple renal sodium transporters, it is not known whether normal variation in plasma insulin regulates sodium homeostasis physiologically. This study tested whether the normal postprandial increase in plasma insulin significantly attenuates renal sodium and volume losses. Rats were instrumented with chronic artery and vein catheters, housed in metabolic cages, and connected to hydraulic swivels. Measurements of urine volume and sodium excretion (UNaV) over 24 h and the 4-h postprandial period were made in control (C) rats and insulin-clamped (IC) rats in which the postprandial increase in insulin was prevented. Twenty-four-hour urine volume (36 ± 3 vs. 15 ± 2 ml/day) and UNaV (3.0 ± 0.2 vs. 2.5 ± 0.2 mmol/day) were greater in the IC compared with C rats, respectively. Four hours after rats were given a gel meal, blood glucose and urine volume were greater in IC rats, but UNaV decreased. To simulate a meal while controlling blood glucose, C and IC rats received a glucose bolus that yielded peak increases in blood glucose that were not different between groups. Urine volume (9.7 ± 0.7 vs. 6.0 ± 0.8 ml/4 h) and UNaV (0.50 ± 0.08 vs. 0.20 ± 0.06 mmol/4 h) were greater in the IC vs. C rats, respectively, over the 4-h test. These data demonstrate that the normal increase in circulating insulin in response to hyperglycemia may be required to prevent excessive renal sodium and volume losses and suggest that insulin may be a physiological regulator of sodium balance

Development and characterization of a stable adhesive bond between a poly(dimethylsiloxane) catheter material and a bacterial biofilm resistant acrylate polymer coating

Catheter associated urinary tract infections (CA-UTIs) are the most common health related infections world wide, contributing significantly to patient morbidity and mortality and increased health care costs. To reduce the incidence of these infections, new materials that resist bacterial biofilm formation are needed. A composite catheter material, consisting of bulk PDMS coated with a novel bacterial biofilm resistant polyacrylate (EGDPEA–co-DEGMA) has been proposed. The coated material shows excellent bacterial resistance when compared to commercial catheter materials but delamination of the coatings under mechanical stress presents a challenge. In this work, the use of oxygen plasma treatment to improve the wettability and reactivity of the PDMS catheter material and improve adhesion with the EGDPEA–co-DEGMA coating has been investigated. Argon Cluster 3D-imaging Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) has been used to probe the buried adhesive interface between the EGDPEA–co-DEGMA coating and the treated PDMS. ToF-SIMS analysis was performed in both dry and frozen-hydrated states and results were compared to mechanical tests. From the ToF-SIMS data we have been able to observe the presence of PDMS, silicates, salt particles, cracks and water at the adhesive interface. In the dry catheters, low molecular weight PDMS oligomers at the interface were associated with poor adhesion. When hydrated, the hydrophilic silicates attracted water to the interface and led to easy delamination of the coating. The best adhesion results, under hydrated conditions, were obtained using a combination of 5 min O2 plasma treatment and silane primers. Cryo-ToF-SIMS analysis of the hydrated catheter material showed that the bond between the primed PDMS catheter and the EGDPEA–co-DEGMA coating was stable in the presence of water. The resulting catheter material was resisted Escherichia coli and Proteus mirabilis biofilm colonization by up to 95 % compared with uncoated PDMS after 10 days of continuous bacterial exposure and had the mechanical properties necessary for use as a urinary catheter

Independent large scale duplications in multiple M. tuberculosis lineages overlapping the same genomic region

Mycobacterium tuberculosis, the causative agent of most human tuberculosis, infects one third of the world's population and kills an estimated 1.7 million people a year. With the world-wide emergence of drug resistance, and the finding of more functional genetic diversity than previously expected, there is a renewed interest in understanding the forces driving genome evolution of this important pathogen. Genetic diversity in M. tuberculosis is dominated by single nucleotide polymorphisms and small scale gene deletion, with little or no evidence for large scale genome rearrangements seen in other bacteria. Recently, a single report described a large scale genome duplication that was suggested to be specific to the Beijing lineage. We report here multiple independent large-scale duplications of the same genomic region of M. tuberculosis detected through whole-genome sequencing. The duplications occur in strains belonging to both M. tuberculosis lineage 2 and 4, and are thus not limited to Beijing strains. The duplications occur in both drug-resistant and drug susceptible strains. The duplicated regions also have substantially different boundaries in different strains, indicating different originating duplication events. We further identify a smaller segmental duplication of a different genomic region of a lab strain of H37Rv. The presence of multiple independent duplications of the same genomic region suggests either instability in this region, a selective advantage conferred by the duplication, or both. The identified duplications suggest that large-scale gene duplication may be more common in M. tuberculosis than previously considere