Activated chemical defenses suppress herbivory on freshwater red algae

The rapid life cycles of freshwater algae are hypothesized to suppress selection for chemical defenses against herbivores, but this notion remains untested. Investigations of chemical defenses are rare for freshwater macrophytes and absent for freshwater red algae. We used crayfish to assess the palatability of five freshwater red algae relative to a palatable green alga and a chemically defended aquatic moss. We then assessed the roles of structural, nutritional, and chemical traits in reducing palatability. Both native and non-native crayfish preferred the green alga Cladophora glomerata to four of the five red algae. Batrachospermum helminthosum, Kumanoa holtonii, and Tuomeya americana employed activated chemical defenses that suppressed feeding by 30–60 % following damage to algal tissues. Paralemanea annulata was defended by its cartilaginous structure, while Boldia erythrosiphon was palatable. Activated defenses are thought to reduce ecological costs by expressing potent defenses only when actually needed; thus, activation might be favored in freshwater red algae whose short-lived gametophytes must grow and reproduce rapidly over a brief growing season. The frequency of activated chemical defenses found here (three of five species) is 3–20× higher than for surveys of marine algae or aquatic vascular plants. If typical for freshwater red algae, this suggests that (1) their chemical defenses may go undetected if chemical activation is not considered and (2) herbivory has been an important selective force in the evolution of freshwater Rhodophyta. Investigations of defenses in freshwater rhodophytes contribute to among-system comparisons and provide insights into the generality of plant–herbivore interactions and their evolution.     

Predictors of Remission in Depression to Individual and Combined Treatments (PReDICT): Study Protocol for a Randomized Controlled Trial

ABSTRACT: BACKGROUND: Limited controlled data exist to guide treatment choices for clinicians caring for patients with major depressive disorder (MDD). Although many putative predictors of treatment response have been reported, most were identified through retrospective analyses of existing datasets and very few have been replicated in a manner that can impact clinical practice. One major confound in previous studies examining predictors of treatment response is the patient's treatment history, which may affect both the predictor of interest and treatment outcomes. Moreover, prior treatment history provides an important source of selection bias, thereby limiting generalizability. Consequently, we initiated a randomized clinical trial designed to identify factors that moderate response to three treatments for MDD among patients never treated previously for the condition. METHODS: Treatment-naive adults aged 18-65 years with moderate-to-severe, non-psychotic MDD are randomized equally to one of three 12-week treatment arms: 1) cognitive behavior therapy (CBT, 16 sessions), 2) duloxetine (30-60 mg/d), or 3) escitalopram (10-20 mg/d). Prior to randomization, patients undergo multiple assessments, including resting state functional magnetic resonance imaging (fMRI), immune markers, DNA and gene expression products, and dexamethasone-corticotropin releasing hormone (Dex/CRH) testing. Prior to or shortly after randomization, patients also complete a comprehensive personality assessment. Repeat assessment of the biological measures (fMRI, immune markers, and gene expression products) occur at an early time-point in treatment, and upon completion of 12-week treatment, when a a second Dex/CRH test is also conducted, Patients remitting by the end of this acute treatment phase are then eligible to enter a 21-month follow-up phase, with quarterly visits to monitor for recurrence. Non-remitters are offered augmentation treatment for a second 12-week course of treatment, during which they receive a combination of CBT and antidepressant medication. Predictors of the primary outcome, remission, will be identified for overall and treatment-specific effects, and a statistical model incorporating multiple predictors will be developed to predict outcomes. DISCUSSION: The PReDICT study's evaluation of biological, psychological, and clinical factors that may differentially impact treatment outcomes represents a sizeable step toward developing personalized treatments for MDD. Identified predictors should help guide the selection of initial treatments, and identify those patients most vulnerable to recurrence, who thus warrant maintenance or combination treatments to achieve and maintain wellness.     

Blood pressure and hypertension in an American colony (Puerto Rico) and on the USA mainland compared, 1886–1930

We compare blood pressure and hypertension between adult men on the USA mainland and in Puerto Rico born during 1886-1930 to test hypotheses about the link between cardiovascular health and large socioeconomic and political changes in society: (a) 8853 men surveyed in Puerto Rico in 1965 and (b) 1449 non-Hispanic White men surveyed on the mainland during 1971-1975. Systolic and diastolic blood pressure and hypertension were regressed separately on demographic and socioeconomic variables and cardiovascular risk factors. Mainland men not taking anti-hypertensive medication showed statistically significant improvements in systolic blood pressure and hypertension at the beginning of the century and men in Puerto Rico showed improvements in diastolic blood pressure but only during the last two quinquenniums. An average man born on the mainland during the last birth quinquennium (1926-1930) had 7.4-8.7 mmHg lower systolic blood pressure and was 61% less likely to have systolic hypertension than one born before 1901. On average Puerto Rican men born during 1921-1925 had approximately 1.7 mmHg lower diastolic blood pressure than men born before 1901. Analyses of secular trends in cardiovascular health complements analyses of secular trends in anthropometric indicators and together provide a fuller view of the changing health status of a population.     

Purification and partial characterization of 1-aminocyclopropane-1-carboxylate synthase from tomato pericarp

1-Aminocyclopropane-1-carboxylate synthase was purified 5000-fold from LiCl-induced tomato fruit slices by conventional and high-performance liquid chromatography. The final preparation was estimated to be between 25% and 50% pure. Two-dimensional gel electrophoresis indicates that 1-aminocyclopropane-1-carboxylate synthase activity is associated with a 45-kDa polypeptide, with a pI of 5.8 +/- 0.2. The enzyme is inactivated both by its substrate, S-adenosyl-L-methionine (AdoMet) and by one of its products, 1-aminocyclopropane-1-carboxylate. Due to the extremely low abundance of the protein it was necessary to scale up the extraction in order to obtain reasonable amounts for sequence analysis. Therefore, 200 kg tomatoes were extracted on semi-industrial scale and 1-aminocyclopropane-1-carboxylate synthase purified. This yielded approximately 150 micrograms enzyme.     

Two genes encode the major membrane-associated protein of methanol-induced peroxisomes from Candida boidinii

A massive proliferation of peroxisomes occurs in the yeast Candida boidinii when methanol is utilized as the sole carbon source; these peroxisomes contain the enzymes which catalyze the initial steps of methanol utilization. The most abundant peroxisomal membrane-associated protein has an apparent molecular mass of 20 kDa and is termed PMP20. We report the isolation of two genes that encode very similar forms of PMP20; this is the first report of genes that encode proteins associated with peroxisomal membranes. Southern analysis demonstrates that the two genes are on different loci, although there are several homologous regions of both 5'- and 3'-untranslated sequence. One of the areas of 5' homology is within the untranslated region of the mRNA. Within the coding region there are 35 base differences between the two genes that are reflected in only five amino acid differences. The mRNAs representing both genes of PMP20 are induced in cells grown in methanol-containing medium and are below detection in cells grown in glucose. S1 nuclease protection analysis indicates that there is a 2.5-fold difference in mRNA expression between the two genes when induced. The predicted sequences of both PMP20 genes show the absence of a cleaved amino-terminal leader sequence and the presence of only 1 cysteine residue. In agreement with previous biochemical data suggesting a peripheral association of this protein with the membrane (Goodman, J. M., Maher, J., Silver, P. A., Pacifico, A., and Sanders, D. (1986) J. Biol. Chem. 261, 3464-3468), there are no obvious membrane spanning regions predicted in the sequences. Both PMP20 gene products contain the carboxyl-terminal sequence AKL, similar to the putative SKL peroxisomal sorting sequence (Gould, S. J., Keller, G.-A., and Subramani, S. (1988) J. Cell Biol. 107, 897-905).     

Investigation of an F-18 oxytocin receptor selective ligand via PET imaging

The compound 1-(1-(2-(2-(2-fluoroethoxy)-4-(piperidin-4-yloxy)phenyl)acetyl)piperidin-4-yl)-3,4-dihydroquinolin-2(1H)-one (1) was synthesized and positively evaluated in vitro for high potency and selectivity with human oxytocin receptors. The positron emitting analogue, [F-18]1, was synthesized and investigated in vivo via PET imaging using rat and cynomolgus monkey models. PET imaging studies in female Sprague–Dawley rats suggested [F-18]1 reached the brain and accumulated in various regions of the brain, but washed out too rapidly for adequate quantification and localization. In vivo PET imaging studies in a male cynomolgus monkey suggested [F-18]1 had limited brain penetration while specific uptake of radioactivity significantly accumulated within the vasculature of the cerebral ventricles in areas representative of the choroid plexus.