Fine root foraging strategies in Norway spruce forests across a European climate gradient

Fine root acclimation to different environmental conditions is crucial for growth and sustainability of forest trees. Relatively small changes in fine root standing biomass (FRB), morphology or mycorrhizal symbiosis may result in a large change in forest carbon, nutrient and water cycles. We elucidated the changes in fine root traits and associated ectomycorrhizal (EcM) fungi in 12 Norway spruce stands across a climatic and N deposition gradient from subarctic‐boreal to temperate regions in Europe (68°N–48°N). We analysed the standing FRB and the ectomycorrhizal root tip biomass (EcMB, g m^?2) simultaneously with measurements of the EcM root morphological traits (e.g. mean root length, root tissue density (RTD), N% in EcM roots) and frequency of dominating EcM fungi in different stands in relation to climate, soil and site characteristics. Latitude and N deposition explained the greatest proportion of variation in fine root traits. EcMB per stand basal area (BA) increased exponentially with latitude: by about 12.7 kg m^?2 with an increase of 10° latitude from southern Germany to Estonia and southern Finland and by about 44.7 kg m^?2 with next latitudinal 10° from southern to northern Finland. Boreal Norway spruce forests had 4.5 to 11 times more EcM root tips per stand BA, and the tips were 2.1 times longer, with 1.5 times higher RTD and about 1/3 lower N concentration. There was 19% higher proportion of root tips colonized by long‐distance exploration type forming EcM fungi in the southern forests indicating importance of EcM symbiont foraging strategy in fine root nutrient acquisition. In the boreal zone, we predict ca. 50% decrease in EcMB per stand BA with an increase of 2 °C annual mean temperature. Different fine root foraging strategies in boreal and temperate forests highlight the importance of complex studies on respective regulatory mechanisms in changing climate.     

Auditory sensitivity and ecological relevance: the functional audiogram as modelled by the bat detecting moth ear

Auditory sensitivity has often been measured by identifying neural threshold in real-time (online) which can introduce bias in the audiograms that are produced. We tested this by recording auditory nerve activity of the notodontid moth Nadata gibbosa elicited by bat-like ultrasound and analysing the response offline. We compared this audiogram with a published online audiogram showing that the bias introduced can result in a difference in the audiogram shape. In the second part of our study we compared offline audiograms using spike number as threshold with others that used spike period and stimulus/spike latency, variables that have been suggested as providing behaviourally functional criteria. These comparisons reveal that functional audiograms are more flatly tuned than simple spike audiograms. The shapes of behavioural audiograms are discussed in the context of the selection pressure that maintains their shape, bat predation. Finally, we make predictions on the distance from bats at which notodontid moths use negative phonotaxis or the acoustic startle response.     

No neural evidence for dynamic auditory tuning of the A1 receptor in the ear of the noctuid moth, <Emphasis Type="Italic">Noctua pronuba</Emphasis>

By examining the mechanical properties of the tympanum of the noctuid moth, Noctua pronuba, Windmill et al. (2006) suggested that this insect increases (up-tunes) the frequencies of its best hearing when exposed to high intensity sounds (HIS) resembling the echolocation calls of attacking bats. We tested whether this biophysical phenomenon was encoded in the neural responses of this moth’s most sensitive auditory receptor (A1 cell) before and after exposure to HIS. We measured: (1) the number of A1 action potentials (spikes) per stimulus pulse; (2) the proportion of A1 spike periods below that determined to elicit evasive flight maneuvers and, (3) the change in A1 cell firing (spike number, interspike interval, stimulus/spike latency) over a duration of time similar to that in which up-tuning lasts. We observed no significant spiking response changes in the predicted direction to any of the frequencies tested following exposure to HIS and we observed only two of the 24 predicted time-dependent changes to A1 firing. These results indicate that tympanal up-tuning does not result in a change to this moth’s auditory frequency sensitivity and we suggest either sensillar resonances or increases in thoracic muscle tension following exposure to HIS as alternative explanations.     

Effects of shift work on attention deficit,hyperactivity, and impulsivity,and their relationship with chronotype

There is growing evidence that shift-work schedules cause severe disturbances to circadian rhythms and the sleep–wakefulness cycle, and that these changes in turn lead to cognitive and behavioral problems. The objective of this study is to explore the relationships between biological rhythm differences (chronotype) and impulsive behaviors and attention-deficit hyperactivity symptoms in shift workers. Seventy-nine nurses working in the daytime and 127 nurses working on night shifts were evaluated with the Barratt Impulsiveness Scale, Adult Attention Deficit Hyperactivity Disorder Self-Report Scale (ASRS), and Morningness–Eveningness questionnaire for identifying circadian preference. It was found that shift workers had more attention deficit (p < .05) and impulsivity (p < .01) when compared with daytime workers. Morning-type workers reported lower hyperactivity and ASRS total scores than evening- and intermediate-type workers. The mean impulsivity score of evening-type workers was higher than both the other groups (p < .05). It has been shown that attention deficit, hyperactivity, and impulsivity levels that appear as a result of working shifts might change in accordance with the individual’s chronotype. It might, therefore, be desirable to evaluate an individual’s chronotype to establish suitability for working shifts.     

Gating the pore of potassium leak channels

A key feature of potassium channel function is the ability to switch between conducting and non-conducting states by undergoing conformational changes in response to cellular or extracellular signals. Such switching is facilitated by the mechanical coupling of gating domain movements to pore opening and closing. Two-pore domain potassium channels (K_2P) conduct leak or background potassium-selective currents that are mostly time- and voltage-independent. These channels play a significant role in setting the cell resting membrane potential and, therefore modulate cell responsiveness and excitability. Thus, K_2P channels are key players in numerous physiological processes and were recently shown to also be involved in human pathologies. It is well established that K_2P channel conductance, open probability and cell surface expression are significantly modulated by various physical and chemical stimuli. However, in understanding how such signals are translated into conformational changes that open or close the channels gate, there remain more open questions than answers. A growing line of evidence suggests that the outer pore area assumes a critical role in gating K_2P channels, in a manner reminiscent of C-type inactivation of voltage-gated potassium channels. In some K_2P channels, this gating mechanism is facilitated in response to external pH levels. Recently, it was suggested that K_2P channels also possess a lower activation gate that is positively coupled to the outer pore gate. The purpose of this review is to present an up-to-date summary of research describing the conformational changes and gating events that take place at the K_2P channel ion-conducting pathway during the channel regulation.     

Renoprotective Effects of Alpha Lipoic Acid on Iron Overload-Induced Kidney Injury in Rats by Suppressing NADPH Oxidase 4 and p38 MAPK Signaling

Biological Trace Element Research - We aimed to investigate the protective effect of alpha lipoic acid (ALA), a powerful antioxidant, against oxidative kidney damage induced by iron overload in...     

Comparing aflatoxin contamination in chilies from Punjab,Pakistan produced in summer and winter

A comparison was made of total aflatoxins (AFs) in 43 samples of chilies collected during winter and 42 in summer to determine the effect of season on contamination. The samples were analyzed by HPLC with fluorescence detection. The limits of detection and quantification for AFB₁ and AFG₁ were 0.05 μg/kg and 0.50 μg/kg, whilst for AFG₂ and AFB₂ they were 0.10 μg/kg and 0.60 μg/kg. In the winter samples, AFs were detected in 18 (72%) whole and 14 (60%) ground chilies, with concentration ranges 0.00-52.30 μg/kg and 0.00-74.60 μg/kg respectively. In the summer samples, 17 (64%) whole and 12 (76%) ground chilies were contaminated with AFs at concentrations 0.00-61.50 μg/kg and 0.00-95.90 μg/kg respectively. The percentage of samples greater than the European Union statutory limit for AFB₁ and total AF for whole chilies were 48 and 36%, compared with ground chili values of 50 and 45%, respectively, in the winter season. In the summer season, the samples greater than the European Union limit for AFB₁ and total AF in whole chilies were 52 and 38%, compared with values of 54 and 49% in ground chilies respectively. AF contamination was found to be higher in summer chili samples and hence winter chilies may provide a better quality product with respect to AF contamination. The ability to undertake this analysis in Pakistan will enhance greatly the ability to improve chili production in that country, as described herein.     

A novel mechanism for human K2P2.1 channel gating. Facilitation of C-type gating by protonation of extracellular histidine residues

The mammalian K2P2.1 potassium channel (TREK-1, KCNK2) is highly expressed in excitable tissues, where it plays a key role in the cellular mechanisms of neuroprotection, anesthesia, pain perception, and depression. Here, we report that external acidification, within the physiological range, strongly inhibits the human K2P2.1 channel by inducing "C-type" closure. We have identified two histidine residues (i.e. His-87 and His-141), located in the first external loop of the channel, that govern the response of the channel to external pH. We demonstrate that these residues are within physical proximity to glutamate 84, homologous to Shaker Glu-418, KcsA Glu-51, and KCNK0 Glu-28 residues, all previously argued to stabilize the outer pore gate in the open conformation by forming hydrogen bonds with pore-adjacent residues. We thus propose a novel mechanism for pH sensing in which protonation of His-141 and His-87 generates a local positive charge that serves to draw Glu-84 away from its natural interactions, facilitating the collapse of the selectivity filter region. In accordance with this proposed mechanism, low pH modified K2P2.1 selectivity toward potassium. Moreover, the proton-mediated effect was inhibited by external potassium ions and was enhanced by a mutation (S164Y) known to accelerate C-type gating. Furthermore, proton-induced current inhibition was more pronounced at negative potentials. Thus, voltage-dependent C-type gating acceleration by protons represents a novel mechanism for K2P2.1 outward rectification.     

Aflatoxin contamination in different fractions of rice from Pakistan and estimation of dietary intakes

The purpose of this study was to determine the distribution of aflatoxins in rice milling fractions and to estimate dietary intakes. A total of 413 rice samples (paddy 58, parboiled 69, brown 84, white 93, and broken 109) were analyzed by HPLC with fluorescence detector. The results showed that 64?% paddy (16.35?±?1.67???g/kg), 38?% parboiled (14.20?±?2.04???g/kg), 33?% brown (9.85?±?1.25???g/kg), 42?% white (7.10?±?1.39???g/kg), and 50?% broken (8.5?±?1.71???g/kg) rice samples were contaminated with aflatoxins. It was found that paddy rice was most contaminated with aflatoxins while white rice was least contaminated. The percentage of samples exceeding EU maximum contents for total aflatoxins in rice (4???g/kg) varied from 14 to 36?% when compared to the analyzed rice fractions. The total estimated amount of aflatoxin intake for average rice consumers ranged from 19.1 to 26.6?ng/kg body weight/day, much higher than the reference value of 1?ng/kg body weight/day. This is the first report discovering that rice is a major contributor to the dietary intake of aflatoxins in Pakistan.     

A Novel Host-Proteome Signature for Distinguishing between Acute Bacterial and Viral Infections

Bacterial and viral infections are often clinically indistinguishable, leading to inappropriate patient management and antibiotic misuse. Bacterial-induced host proteins such as procalcitonin, C-reactive protein (CRP), and Interleukin-6, are routinely used to support diagnosis of infection. However, their performance is negatively affected by inter-patient variability, including time from symptom onset, clinical syndrome, and pathogens. Our aim was to identify novel viral-induced host proteins that can complement bacterial-induced proteins to increase diagnostic accuracy. Initially, we conducted a bioinformatic screen to identify putative circulating host immune response proteins. The resulting 600 candidates were then quantitatively screened for diagnostic potential using blood samples from 1002 prospectively recruited patients with suspected acute infectious disease and controls with no apparent infection. For each patient, three independent physicians assigned a diagnosis based on comprehensive clinical and laboratory investigation including PCR for 21 pathogens yielding 319 bacterial, 334 viral, 112 control and 98 indeterminate diagnoses; 139 patients were excluded based on predetermined criteria. The best performing host-protein was TNF-related apoptosis-inducing ligand (TRAIL) (area under the curve [AUC] of 0.89; 95% confidence interval [CI], 0.86 to 0.91), which was consistently up-regulated in viral infected patients. We further developed a multi-protein signature using logistic-regression on half of the patients and validated it on the remaining half. The signature with the highest precision included both viral- and bacterial-induced proteins: TRAIL, Interferon gamma-induced protein-10, and CRP (AUC of 0.94; 95% CI, 0.92 to 0.96). The signature was superior to any of the individual proteins (P<0.001), as well as routinely used clinical parameters and their combinations (P<0.001). It remained robust across different physiological systems, times from symptom onset, and pathogens (AUCs 0.87-1.0). The accurate differential diagnosis provided by this novel combination of viral- and bacterial-induced proteins has the potential to improve management of patients with acute infections and reduce antibiotic misuse.