An astigmatid defence volatile against a phytoseiid mite

Numerous semiochemicals have been isolated from several species of astigmatid mites with various identified or unidentified functions. Alarm pheromonal activity is widespread with neryl formate and neral, being the most common compounds eliciting alarm response in conspecifics. The cosmopolitan astigmatid mite Suidasia medanensis (= S. pontifica) Oudemans (Acari: Suidasidae) has been reported to use neral as an alarm pheromone, but neral can also act as an allomone towards predators of oribatid mites. Suidasia medanensis can be utilised as a factitious prey for mass‐rearing of the phytoseiid predatory mite Amblyseius (= Typhlodromips) swirskii (Athias‐Henriot) (Acari: Phytoseiidae), which is used for biological control of insect and mite pests in protected crops. This study investigated the potential defence properties of the S. medanensis volatiles against A. swirskii, comparing the repellency to pollen‐reared (naïve) vs. S. medanensis‐reared (experienced) predators using a synthetic blend of the isomers neral and geranial (1:1) as a model compound. In a repellency bioassay, the synthetic blend elicited a significant repellence to A. swirskii with no difference between naïve and experienced predators. During capture success studies, S. medanensis under repeated attack could release sufficient quantities of the defence volatile to deter 1–5 attacks from A. swirskii, whereas hexane‐treated S. medanensis artificially depleted of volatiles were significantly more vulnerable to an attack. This is the first report of an astigmatid defence volatile with repellent activity to a phytoseiid mite and the starting point to understanding semiochemical interactions in any current or novel factitious predator‐prey mass‐rearing system.     

Circulating RNAs as predictive markers for the progression of type 2 diabetes

Type 2 Diabetes Mellitus (T2DM) is the most prevalent form of diabetes in the USA, thus, the identification of biomarkers that could be used to predict the progression from prediabetes to T2DM would be greatly beneficial. Recently, circulating RNA including microRNAs (miRNAs) present in various body fluids have emerged as potential biomarkers for various health conditions, including T2DM. Whereas studies that examine the changes of miRNA spectra between healthy controls and T2DM individuals have been reported, the goal of this study is to conduct a baseline comparison of prediabetic individuals who either progress to T2DM, or remain prediabetic. Using an advanced small RNA sequencing library construction method that improves the detection of miRNA species, we identified 57 miRNAs that showed significant concentration differences between progressors (progress from prediabetes to T2DM) and non‐progressors. Among them, 26 have been previously reported to be associated with T2DM in either body fluids or tissue samples. Some of the miRNAs identified were also affected by obesity. Furthermore, we identified miRNA panels that are able to discriminate progressors from non‐progressors. These results suggest that upon further validation these miRNAs may be useful to predict the risk of conversion to T2DM from prediabetes.     

A curated gene list for expanding the horizons of pigmentation biology

Over the past century, studies of human pigmentary disorders along with mouse and zebrafish models have shed light on the many cellular functions associated with visible pigment phenotypes. This has led to numerous genes annotated with the ontology term “pigmentation” in independent human, mouse, and zebrafish databases. Comparisons among these datasets revealed that each is individually incomplete in documenting all genes involved in integument‐based pigmentation phenotypes. Additionally, each database contained inherent species‐specific biases in data annotation, and the term “pigmentation” did not solely reflect integument pigmentation phenotypes. This review presents a comprehensive, cross‐species list of 650 genes involved in pigmentation phenotypes that was compiled with extensive manual curation of genes annotated in OMIM, MGI, ZFIN, and GO. The resulting cross‐species list of genes both intrinsic and extrinsic to integument pigment cells provides a valuable tool that can be used to expand our knowledge of complex, pigmentation‐associated pathways.     

Turbidity Structures the Controls of Ecosystem Metabolism and Associated Metabolic Process Domains Along a 75-km Segment of a Semiarid Stream

Ecosystems - Stream ecosystem metabolism contributes to global carbon cycling, yet predicting metabolism across ecosystems remains elusive. Even within stream segments, spatial variation in...     

Visualizing excitation waves inside cardiac muscle using transillumination

Voltage-sensitive fluorescent dyes have become powerful tools for the visualization of excitation propagation in the heart. However, until recently they were used exclusively for surface recordings. Here we demonstrate the possibility of visualizing the electrical activity from inside cardiac muscle via fluorescence measurements in the transillumination mode (in which the light source and photodetector are on opposite sides of the preparation). This mode enables the detection of light escaping from layers deep within the tissue. Experiments were conducted in perfused (8 mm thick) slabs of sheep right ventricular wall stained with the voltage-sensitive dye di-4-ANEPPS. Although the amplitude and signal-to-noise ratio recorded in the transillumination mode were significantly smaller than those recorded in the epi-illumination mode, they were sufficient to reliably determine the activation sequence. Penetration depths (spatial decay constants) derived from measurements of light attenuation in cardiac muscle were 0.8 mm for excitation (520 +/- 30 nm) and 1.3 mm for emission wavelengths (640 +/- 50 nm). Estimates of emitted fluorescence based on these attenuation values in 8-mm-thick tissue suggest that 90% of the transillumination signal originates from a 4-mm-thick layer near the illuminated surface. A 69% fraction of the recorded signal originates from > or =1 mm below the surface. Transillumination recordings may be combined with endocardial and epicardial surface recordings to obtain information about three-dimensional propagation in the thickness of the myocardial wall. We show an example in which transillumination reveals an intramural reentry, undetectable in surface recordings.     

Detecting Resistance to Organophosphates and Carbamates in the Cattle Tick Boophilus Microplus, with a Propoxur-based Biochemical Test

Rapid and sensitive detection of resistance to insecticides in arthropods is needed. In the cattle tick, Boophilus microplus, resistance to a variety of acaricides is widespread. The most commonly used assay for resistance, the larval packet test, takes at least two, but generally six weeks for a one-host tick like B. microplus to complete and may take up to three months to complete for three-host ticks. Here we describe a test for resistance to organophosphate acaricides that can be used on larvae and adult ticks which takes less than 24 hours. The test measures the difference in acetylcholinesterase (AChE) activity in homogenates of ticks in the presence and absence of propoxur, a carbamate acaricide. We found clear discrimination of organophosphate-susceptible and organophosphate-resistant adults with 100 M propoxur. AChE from susceptible ticks had almost no activity at this concentration of propoxur whereas AChE from resistant ticks had 67% of its potential activity. AChE from heterozygote ticks could also be distinguished from AChE from homozygous-susceptible and homozygous-resistant ticks. This is the first biochemical test for resistance to an acaricide. Rapid, sensitive tests like ours will allow resistance to organophosphates to be detected soon after it develops in the field, thus, the spread of resistance might be slowed and the useful life of acaricides extended.     

The cover of living and dead corals from airborne remote sensing

Trends in coral cover are widely used to indicate the health of coral reefs but are costly to obtain from field survey over large areas. In situ studies of reflected spectra at the coral surface show that living and recently dead colonies can be distinguished. Here, we investigate whether such spectral differences can be detected using an airborne remote sensing instrument. The Compact Airborne Spectrographic Imager (Itres Research Ltd, Canada) was flown in two configurations: 10 spectral bands with 1-m² pixels and 6 spectral bands with 0.25-m² pixels. First, we show that an instrument with 10 spectral bands possesses adequate spectral resolution to distinguish living Porites, living Pocillopora spp., partially dead Porites, recently dead Porites (total colony mortality within 6 months), old dead (>6 months) Porites, Halimeda spp., and coralline red algae when there is no water column to confuse spectra. All substrata were distinguished using fourth-order spectral derivatives around 538 nm and 562 nm. Then, at a shallow site (Tivaru) at Rangiroa Atoll, Tuamotu Archipelago (French Polynesia), we show that live and dead coral can be distinguished from the air to a depth of at least 4 m using first- and fourth-order spectral derivatives between 562–580 nm. However, partially dead and recently dead Porites colonies could not be distinguished from an airborne platform. Spectral differences among substrata are then exploited to predict the cover of reef substrata in ten 25-m² plots at nearby Motu Nuhi (max depth 8 m). The actual cover in these plots was determined in situ using quadrats with a 0.01-m² grid. Considerable disparity occurred between field and image-based measures of substrate cover within individual 25-m² quadrats. At this small scale, disparity, measured as the absolute difference in cover between field and remote-sensing methods, reached 25% in some substrata but was always less than 10% for living coral (99% of which consisted of Porites spp.). At the scale of the reef (all ten 25-m² quadrats), however, disparities in percent cover between imagery and field data were less than 10% for all substrata and extremely low for some classes (e.g. <3% for living Porites, recently dead Porites and Halimeda). The least accurately estimated substrata were sand and coralline red algae, which were overestimated by absolute values 7.9% and 6.6%, respectively. The precision of sampling was similar for field and remote-sensing methods: field methods required 19 plots to detect a 10% difference in coral cover among three reefs with a statistical power of 95%. Remote-sensing methods required 21 plots. However, it took 1 h to acquire imagery over 92,500 m² of reef, which represents 3,700 plots of 25 m² each, compared with 3 days to survey 10 such plots underwater. There were no significant differences in accuracy between 1-m² and 0.25-m² image resolutions, suggesting that the advantage of using smaller pixels is offset by reduced spectral information and an increase in noise (noise was observed to be 1.6–1.8 times greater in 0.25-m² pixels). We show that airborne remote sensing can be used to monitor coral and algal cover over large areas, providing that water is shallow and clear, and that brown fleshy macroalgae are scarce, that depth is known independently (e.g. from sonar survey).     

B-type natriuretic peptide limits infarct size in rat isolated hearts via KATP channel opening

B-type natriuretic peptide (BNP) has been reported to be released from the myocardium during ischemia. We hypothesized that BNP mediates cardioprotection during ischemia-reperfusion and examined whether exogenous BNP limits myocardial infarction and the potential role of ATP-sensitive potassium (K(ATP)) channel opening. Langendorff-perfused rat hearts underwent 35 min of left coronary artery occlusion and 120 min of reperfusion. The control infarct-to-risk ratio was 44.8 +/- 4.4% (means +/- SE). BNP perfused 10 min before ischemia limited infarct size in a concentration-dependent manner, with maximal protection observed at 10(-8) M (infarct-to-risk ratio: 20.1 +/- 5.2%, P < 0.01 vs. control), associated with a 2.5-fold elevation of myocardial cGMP above the control value. To examine the role of K(ATP) channel opening, glibenclamide (10(-6) M), 5-hydroxydecanoate (5-HD; 10(-4) M), or HMR-1098 (10(-5) M) was coperfused with BNP (10(-8) M). Protection afforded by BNP was abolished by glibenclamide or 5-HD but not by HMR-1098, suggesting the involvement of putative mitochondrial but not sarcolemmal K(ATP) channel opening. We conclude that natriuretic peptide/cGMP/K(ATP) channel signaling may constitute an important injury-limiting mechanism in myocardium.