Ionylideneacetic Acids and Abscisic Acid Biosynthesis by Cercospora rosicola

Several compounds having the basic α-ionylideneacetic acid structure were tested in Cercospora rosicola resuspensions. At 100 μm, all the compounds inhibited abscisic acid (ABA) biosynthesis. Time studies with unlabelled and deuterated (2Z,4E)- and (2E,4E)-α-ionylideneacetic acids showed rapid conversions into both (2Z,4E)- and (2E,4E)-4′-keto-α-ionylideneacetic acids as major products. Incorporation of the label into ABA was specific for the 2Z,4E-isomer. Minor products, identified by GC-MS, were (2Z,4E)- and (2E,4E)-4′-hydroxy-α-ionylideneacetic acids and (2Z,4E)-1′-hydroxy-α-ionylideneacetic acid. The conversion to (2Z,4E)-l′-hydroxy-α-ionylideneacetic acid has not been previously reported and was specific for the 2Z,4E-isomer. A time study for the conversion of methyl esters of [²H₃]-(2Z,4E)- and [²H₃]-(2E,4E)-4′-keto-α-ionylideneacetates showed a slow introduction of the l′-hydroxyl group and specificity for 2Z,4E-isomer. Conversion of the ethyl esters of (2Z,4E)- and (2E,4E)-l′-hydroxy-α-ionylideneacetates into the ethyl esters of both ABA and (2E,4E)-ABA demonstrated that ABA can be formed by oxidation of the 4′-position after the insertion of the 1′-hydroxy group. The ethyl 1′-hydroxy acids were also isomerized to the corresponding ethyl (2Z,4E)- and ethyl (2E,4E)-3′-hydroxy-β-ionylideneacetates. Ethyl (2Z,4E)-1′-hydroxy acid also gave small amounts of ethyl l′,4′-trans-diol of ABA. These results suggest that ABA may be formed through a (2Z,4E)-1′-hydroxy-α-ionylidene-type intermediate in addition to the previously proposed route through (2Z,4E)-4′-keto-α-ionylideneacetic acid.     

Palau’s taro fields and mangroves protect the coral reefs by trapping eroded fine sediment

Sedimentation is one of the biggest threats facing coral reefs, not only in Palau, but everywhere in the world where there are reefs within reach of river plumes. Due to Palau’s largest island of Babeldaob’s steep topography, high rainfall, and highly erodible volcanic soil, erosion has been exacerbated by recent increases in land-use. Studies have documented the negative impacts of the resulting sedimentation on coral reefs around Babeldaob. Similar studies have shown that mangroves can trap about 30 % of the fine eroded sediment from land. This paper documents the filtering effects of cultivated wetland, namely that of taro (Colocasia esculenta) fields, which are natural wetlands used to grow taro, a source of starch for the population. A 4-month long field study was conducted to quantify the sediment accumulation rate for three different types of taro fields and to determine their sediment trapping efficiency. The results showed that the taro fields have the capacity to trap up to 90 % of sediments. We suggest that the sediment trapping capacity of mangroves and taro fields mitigated the negative impacts of soil runoff on coral reefs around Babeldaob while the island was being inhabited by early Palauans for many generations.     

Racial affective economies,disalienation and ‘race made ordinary’

This paper speaks against tolerance as an instrument of institutionalized anti-racism within academia where collegiality is a minimal expectation in interpersonal interactions. Through auto-ethnographic readings, the discussion focuses on the racial affective economies produced in universities as tolerance ‘makes race ordinary’. Within this reading, ‘making race ordinary’ is shown to produce unliveable lives because of its racial affective economies animated by contemptuous tolerance, disgust and disattendability. These negative affects emerge within the epistemology of ignorance produced by the racial contract and have affective and career consequences for racialized others placed outside of organizational networks. The paper argues that to destabilize the white power in networks that decide on access, tenure and promotion and to enable liveable lives within universities, the transformative potential of the transracial intimacy of friendship must be engaged. This entails ‘race made ordinary’ through disalienation-estrangement from the ‘raced’ subject positionings of the racial contract.     

Short peptide constructs mimic agonist sites of AT1R and BK receptors

Extracellular peptide ligand binding sites, which bind the N-termini of angiotensin II (AngII) and bradykinin (BK) peptides, are located on the N-terminal and extracellular loop 3 regions of the AT₁R and BKRB₁ or BKRB₂ G-protein-coupled receptors (GPCRs). Here we synthesized peptides P15 and P13 corresponding to these receptor fragments and showed that only constructs in which these peptides were linked by S–S bond, and cyclized by closing the gap between them, could bind agonists. The formation of construct-agonist complexes was revealed by electron paramagnetic resonance spectra and fluorescence measurements of spin labeled biologically active analogs of AngII and BK (Toac¹-AngII and Toac⁰-BK), where Toac is the amino acid-type paramagnetic and fluorescence quencher 2, 2, 6, 6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid. The inactive derivatives Toac³-AngII and Toac³-BK were used as controls. The interactions characterized by a significant immobilization of Toac and quenching of fluorescence in complexes between agonists and cyclic constructs were specific for each system of peptide-receptor construct assayed since no crossed reactions or reaction with inactive peptides could be detected. Similarities among AT, BKR, and chemokine receptors were identified, thus resulting in a configuration for AT₁R and BKRB cyclic constructs based on the structure of the CXCR₄, an α-chemokine GPCR-type receptor.     

Diacylglycerol Acyltransferase-1 (DGAT1) Inhibition Perturbs Postprandial Gut Hormone Release

Diacylglycerol acyltransferase-1 (DGAT1) is a potential therapeutic target for treatment of obesity and related metabolic diseases. However, the degree of DGAT1 inhibition required for metabolic benefits is unclear. Here we show that partial DGAT1 deficiency in mice suppressed postprandial triglyceridemia, led to elevations in glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) only following meals with very high lipid content, and did not protect from diet-induced obesity. Maximal DGAT1 inhibition led to enhanced GLP-1 and PYY secretion following meals with physiologically relevant lipid content. Finally, combination of DGAT1 inhibition with dipeptidyl-peptidase-4 (DPP-4) inhibition led to further enhancements in active GLP-1 in mice and dogs. The current study suggests that targeting DGAT1 to enhance postprandial gut hormone secretion requires maximal inhibition, and suggests combination with DPP-4i as a potential strategy to develop DGAT1 inhibitors for treatment of metabolic diseases.     

Oral Colonization of Fungi

Opportunistic microbes are able to exist as commensals or pathogens depending on local environmental conditions. The bacterial microbiome at mucosal sites (gut, oral and vaginal) has been well characterized but there has been less focus on the fungal component of the microbiome, the “mycobiome”, especially of the oral mucosa. Genomic characterization studies have shown that Candida species are the most prevalent fungal species in the mycobiomes of the murine gut and human oral cavity, with C. albicans being the most abundant fungal species in the oral cavity. In this review, we outline recent advances in the characterization of the oral mycobiome, how different Candida species colonize, invade and infect the oral cavity, and how epithelial surfaces play a key role in antifungal activity and discriminate between commensal and pathogenic Candida.     

Feeding preferences of the weevils Sitona gressorius and Sitona griseus on different lupin genotypes and the role of alkaloids

The weevils Sitona gressorius and Sitona griseus are specialist herbivores on lupins in Europe. The adult weevils feed on the leaves, and the larvae on the root nodules of the plants. This causes severe damage to lupin crops. In the present study, the feeding preferences of lupin weevil adults on different lupin genotypes were examined with respect to a possible effect of lupin alkaloids on host selection. A total of 12 genotypes from the species Lupinus albus, L. angustifolius, L. luteus, and L. nanus were grown in a field experiment and the feeding damage on the leaves caused by naturally occurring lupin weevil adults was estimated. Additionally, a feeding choice test with S. gressorius adults was performed to examine feeding preferences under laboratory conditions. A gas chromatographic analysis provided information on the alkaloid content and profiles in the leaves of the tested lupin genotypes. In the field experiment, significant differences in the extent of the feeding damage within the 12 lupin genotypes were observed. The dual-choice feeding bioassay did not show discrimination of lupin species, but two L. angustifolius genotypes were significantly less affected than the standard L. luteus “Bornal”. The alkaloid analysis revealed large contrasts in alkaloid concentrations and profiles in the leaves of the tested genotypes. Correlation analysis with the results from the field and laboratory did not indicate a significant influence of the total foliar alkaloid content on the extent of weevil feeding.