Voltage-dependent slowing of K channel closing kinetics by Rb+

We have studied the effect of Rb+ on K channel closing kinetics in toadfish pancreatic islet cells. These channels are voltage dependent, activating at voltages positive to -10 mV. The channels also inactivate upon prolonged depolarizations, and the inactivation time course is best fit by the sum of two exponentials. Instantaneous current-voltage relationships show that external Rb+ enters the channel as easily as K+, but carries less current. In the voltage range from -140 to -50 mV, the closing time course of the channels can be fit with a single exponential. When Rb+ is present in the external solution the channels close more slowly. The magnitude of this Rb+ effect is voltage dependent, decreasing at more negative voltages. Similarly, when the internal solution contains Rb+ instead of K+ the closing time constants are increased. The effect of internal Rb+ is also voltage dependent; at voltages positive to -80 mV the closing time constant in internal Rb+ is slower than in K+, whereas at more negative voltages the difference is negligible. With internal Rb+, the relationship between the closing time constant and voltage is best fit with two exponential components, suggesting the presence of two distinct voltage-dependent processes. The results are discussed in terms of a model of the K channel with two internal binding sites, and we conclude that Rb+ produces its effects on channel gating by binding to a site in the pore.     

Impact of Sylvatic Plague Vaccine on Non-target Small Rodents in Grassland Ecosystems

Oral vaccination is an emerging management strategy to reduce the prevalence of high impact infectious diseases within wild animal populations. Plague is a flea-borne zoonosis of rodents that often decimates prairie dog (Cynomys spp.) colonies in the western USA. Recently, an oral sylvatic plague vaccine (SPV) was developed to protect prairie dogs from plague and aid recovery of the endangered black-footed ferret (Mustela nigripes). Although oral vaccination programs are targeted toward specific species, field distribution of vaccine-laden baits can result in vaccine uptake by non-target animals and unintended indirect effects. We assessed the impact of SPV on non-target rodents at paired vaccine and placebo-treated prairie dog colonies in four US states from 2013 to 2015. Bait consumption by non-target rodents was high (70.8%, n?=?3113), but anti-plague antibody development on vaccine plots was low (23.7%, n?=?266). In addition, no significant differences were noted in combined deer mice (Peromyscus maniculatus) and western harvest mouse (Reithrodontomys megalotis) abundance or community evenness and richness of non-target rodents between vaccine-treated and placebo plots. In our 3-year field study, we could not detect a significant positive or negative effect of SPV application on non-target rodents.     

Response to color by male and female Frankliniella occidentalis during swarming and non-swarming behavior

Responses of male and female Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) to colors of various hues and brightness levels were compared between swarming and non-swarming behavior periods. Relative rankings of color preference were similar between males and females and between swarming and non-swarming behavior periods. Numbers of thrips were higher on blues, violets, white and somewhat less on some yellows, while lower numbers were found on greens, reds, some yellows and highly UV reflective white. The effect of UV reflection on thrips response to color depended upon the amount of UV reflectance. Highly UV reflective white (78% reflectance at 365 nm) captured very few thrips compared with low UV white (14% reflectance at 365 nm), but colors with less than 35% UV reflectance had no negative effect on numbers of thrips captured compared with their lower UV counterparts. Correlations of average preference rank of colors across all tests with relative rank of brightness of the colors (based on the area under the reflectance curve in different spectral ranges) indicated highly significant correlations of preference with the brightness in the blue-violet range (R=0.69 for females; R=0.86 for males, P<0.0021), but no significant correlation with brightness in the visible, green-yellow, or UV range. This contrasts with previous physiological research which indicates that spectral response efficiency of this species peaks in the UV and at 540 nm (green-yellow range). Several possible physiological, behavioral and color brightness explanations for this discrepancy are discussed.Significantly higher numbers of male thrips were trapped during swarming (4.5–6.3×) compared with non-swarming behavior periods. Significantly higher numbers of males were trapped than females during swarming behavior periods, but more females were trapped than males during non-swarming behavior periods. Sex ratios during non-swarming periods approximated sex ratios found in populations in plants. Based on the density change relative to sex ratio change between behavior periods, there was an indication of a greater change in male behavior than in female behavior. Since males and females responded similarly to color during both behavior periods and attractive colors were similar to flower colors, this suggests that male thrips use resource-based areas for aggregation sites.     

Evaluating concentration estimation errors in ELISA microarray experiments

Background  

Enzyme-linked immunosorbent assay (ELISA) is a standard immunoassay to estimate a protein's concentration in a sample. Deploying ELISA in a microarray format permits simultaneous estimation of the concentrations of numerous proteins in a small sample. These estimates, however, are uncertain due to processing error and biological variability. Evaluating estimation error is critical to interpreting biological significance and improving the ELISA microarray process. Estimation error evaluation must be automated to realize a reliable high-throughput ELISA microarray system.     

The National QAAMS Program – A Practical Example of PoCT Working in the Community

The Quality Assurance for Aboriginal and Torres Strait Islander Medical Services (QAAMS) Program is the largest and longest-standing national point-of-care testing (PoCT) program in Australia. With a focus on PoCT for diabetes management, it now operates in 115 Indigenous medical services and has been funded continuously by the Australian Government for 11 years. A recent independent evaluation of the QAAMS Program concluded that the program continues to meet best practice standards for Indigenous healthcare, diabetes management and PoCT.     

A model of blood flow in the mesenteric arterial system

Background  

There are some early clinical indicators of cardiac ischemia, most notably a change in a person's electrocardiogram. Less well understood, but potentially just as dangerous, is ischemia that develops in the gastrointestinal system. Such ischemia is difficult to diagnose without angiography (an invasive and time-consuming procedure) mainly due to the highly unspecific nature of the disease.