A New Anaesthetic Protocol for Adult Zebrafish (Danio rerio): Propofol Combined with Lidocaine

Background

The increasing use of zebrafish model has not been accompanied by the evolution of proper anaesthesia for this species in research. The most used anaesthetic in fishes, MS222, may induce aversion, reduction of heart rate, and consequently high mortality, especially during long exposures. Therefore, we aim to explore new anaesthetic protocols to be used in zebrafish by studying the quality of anaesthesia and recovery induced by different concentrations of propofol alone and in combination with different concentrations of lidocaine.

Material and Methods

In experiment A, eighty-three AB zebrafish were randomly assigned to 7 different groups: control, 2.5 (2.5P), 5 (5P) or 7.5 μg/ml (7.5P) of propofol; and 2.5 μg/ml of propofol combined with 50, (P/50L), 100 (P/100L) or 150 μg/ml (P/150L) of lidocaine. Zebrafish were placed in an anaesthetic water bath and time to lose the equilibrium, reflex to touch, reflex to a tail pinch, and respiratory rate were measured. Time to gain equilibrium was also assessed in a clean tank. Five and 24 hours after anaesthesia recovery, zebrafish were evaluated concerning activity and reactivity. Afterwards, in a second phase of experiments (experiment B), the best protocol of the experiment A was compared with a new group of 8 fishes treated with 100 mg/L of MS222 (100M).

Results

In experiment A, only different concentrations of propofol/lidocaine combination induced full anaesthesia in all animals. Thus only these groups were compared with a standard dose of MS222 in experiment B. Propofol/lidocaine induced a quicker loss of equilibrium, and loss of response to light and painful stimuli compared with MS222. However zebrafish treated with MS222 recovered quickly than the ones treated with propofol/lidocaine.

Conclusion

In conclusion, propofol/lidocaine combination and MS222 have advantages in different situations. MS222 is ideal for minor procedures when a quick recovery is important, while propofol/lidocaine is best to induce a quick and complete anaesthesia.     

Effects of different arbuscular mycorrhizal fungal backgrounds and soils on olive plants growth and water relation properties under well‐watered and drought conditions

The adaptation capacity of olive trees to different environments is well recognized. However, the presence of microorganisms in the soil is also a key factor in the response of these trees to drought. The objective of the present study was to elucidate the effects of different arbuscular mycorrhizal (AM) fungi coming from diverse soils on olive plant growth and water relations. Olive plants were inoculated with native AM fungal populations from two contrasting environments, that is, semi‐arid – Freila (FL) and humid – Grazalema (GZ) regions, and subjected to drought stress. Results showed that plants grew better on GZ soil inoculated with GZ fungi, indicating a preference of AM fungi for their corresponding soil. Furthermore, under these conditions, the highest AM fungal diversity was found. However, the highest root hydraulic conductivity (Lp_r) value was achieved by plants inoculated with GZ fungi and growing in FL soil under drought conditions. So, this AM inoculum also functioned in soils from different origins. Nine novel aquaporin genes were also cloned from olive roots. Diverse correlation and association values were found among different aquaporin expressions and abundances and Lp_r, indicating how the interaction of different aquaporins may render diverse Lp_r values.     

Circadian rhythm in locomotor activity in the burrower crayfish Procambarus acanthophorus (Villalobos 1948)

Crayfish Procambarus acanthophorus is a burrower that spends long periods building deep tunnels to reach the water table during the dry season; thus, its survival entertains a close ecological relationship with the sediment. The aim of this work was to determine whether the properties of the circadian rhythm of locomotor activity could be modified by the sediment availability. Experiments were conducted in both aquaria filled with sediment or filled with water, under cycles of Bright and Dim Illumination (BI:DI, 12:12 h) or under continuous DI:DI. The rhythm of locomotor activity was entrained with the photoperiod in aquaria with sediment or water; however, statistical differences between conditions were obtained comparing the period and the level of activity under free-running. These data suggest that the substrate’s sensorial perception could be encoded as a significant ecological parameter that exerts influence in the physiological mechanisms that control the temporal order in P. acanthophorus.     

Performance of the eclipse monitor unit objective tool utilizing volumetric modulated arc therapy for rectal cancer

AimTo assess the performance of the monitor unit (MU) Objective tool in Eclipse treatment planning system (TPS) utilizing volumetric modulated arc therapy (VMAT) for rectal cancer.BackgroundEclipse VMAT planning module includes a tool to control the number of MUs delivered: the MU Objective tool. This tool could be utilized to reduce the total number of MUs in rectal cancer treatments.Materials and methods20 rectal cancer patients were retrospectively studied using VMAT and the MU Objective tool. The baseline plan for each patient was selected as the one with no usage of the MU Objective tool. The number of MUs of this plan was set to be the reference number of MUs (MU_ref). Five plans were re-optimized for each patient only varying the Max MU parameter. The selected values were 30%, 60%, 90%, 120% and 150% of MU_ref for each patient. Differences with respect to the baseline plan were evaluated regarding MU number and parameters for PTVs coverage evaluation, PTVs homogeneity and OARs doses assessment. A two-tailed, paired-samples t-test was used to quantify these differences.ResultsAverage relative differences in MU number obtained was 10% for Max MU values of 30% and 60% of MU_ref, respectively (p < 0.03). PTVs coverage and homogeneity were not compromised and discrepancies obtained with respect to baseline plans were not significant. Furthermore, maximum OARs doses deviations were also not significant.ConclusionsA 10% reduction in the MU number could be obtained without an alteration of PTV coverage and OARs doses for rectal cancer.     

Chloride as a macronutrient increases water‐use efficiency by anatomically driven reduced stomatal conductance and increased mesophyll diffusion to CO2

Chloride (Cl^?) has been recently described as a beneficial macronutrient, playing specific roles in promoting plant growth and water‐use efficiency (WUE). However, it is still unclear how Cl^? could be beneficial, especially in comparison with nitrate (NO₃^?), an essential source of nitrogen that shares with Cl^? similar physical and osmotic properties, as well as common transport mechanisms. In tobacco plants, macronutrient levels of Cl^? specifically reduce stomatal conductance (g_s) without a concomitant reduction in the net photosynthesis rate (A_N). As stomata‐mediated water loss through transpiration is inherent in the need of C₃ plants to capture CO₂, simultaneous increase in photosynthesis and WUE is of great relevance to achieve a sustainable increase in C₃ crop productivity. Our results showed that Cl^?‐mediated stimulation of larger leaf cells leads to a reduction in stomatal density, which in turn reduces g_s and water consumption. Conversely, Cl^? improves mesophyll diffusion conductance to CO₂ (g_m) and photosynthetic performance due to a higher surface area of chloroplasts exposed to the intercellular airspace of mesophyll cells, possibly as a consequence of the stimulation of chloroplast biogenesis. A key finding of this study is the simultaneous improvement of A_N and WUE due to macronutrient Cl^? nutrition. This work identifies relevant and specific functions in which Cl^? participates as a beneficial macronutrient for higher plants, uncovering a sustainable approach to improve crop yield.     

Use of classical bird census transects as spatial replicates for hierarchical modeling of an avian community

New monitoring programs are often designed with some form of temporal replication to deal with imperfect detection by means of occupancy models. However, classical bird census data from earlier times often lack temporal replication, precluding detection‐corrected inferences about occupancy. Historical data have a key role in many ecological studies intended to document range shifts, and so need to be made comparable with present‐day data by accounting for detection probability. We analyze a classical bird census conducted in the region of Murcia (SE Spain) in 1991 and 1992 and propose a solution to estimating detection probability for such historical data when used in a community occupancy model: the spatial replication of subplots nested within larger plots allows estimation of detection probability. In our study, the basic sample units were 1‐km transects, which were considered spatial replicates in two aggregation schemes. We fit two Bayesian multispecies occupancy models, one for each aggregation scheme, and evaluated the linear and quadratic effect of forest cover and temperature, and a linear effect of precipitation on species occupancy probabilities. Using spatial rather than temporal replicates allowed us to obtain individual species occupancy probabilities and species richness accounting for imperfect detection. Species‐specific occupancy and community size decreased with increasing annual mean temperature. Both aggregation schemes yielded estimates of occupancy and detectability that were highly correlated for each species, so in the design of future surveys ecological reasons and cost‐effective sampling designs should be considered to select the most suitable aggregation scheme. In conclusion, the use of spatial replication may often allow historical survey data to be applied formally hierarchical occupancy models and be compared with modern‐day data of the species community to analyze global change process.     

Variable actin dynamics requirement for the exit of different cargo from the trans-Golgi network

Efficient post-Golgi trafficking depends on microtubules, but actin filaments and actin-associated proteins are also postulated. Here we examined, by inverse fluorescence recovery after photobleaching, the role of actin dynamics in the exit from the TGN of fluorescent-tagged apical or basolateral and raft or non-raft-associated cargoes. Either the actin-stabilizing jasplakinolide or the actin-depolymerising latrunculin B variably but significantly inhibited post-Golgi traffic of non-raft associated apical p75NTR and basolateral VSV-G cargoes. The TGN-exit of the apical-destined VSV-G mutant was impaired only by latrunculin B. Strikingly, the raft-associated GPI-anchor protein was not affected by either actin toxin. Results indicate that actin dynamics participates in the TGN egress of both apical- and basolateral-targeted proteins but is not needed for apical raft-associated cargo.     

The virtues and limitations of exploring the eco‐evolutionary dynamics of sexually selected traits

Most studies on eco‐evolutionary feedbacks concern the influence of abiotic factors, or predator–prey and host–parasite interactions, while studies involving sexual interactions are lagging behind. This is at odds with the potential of these interactions to engage in such processes. Indeed, there is now ample evidence that sexual selection is affected by ecological change and that sexually selected traits can evolve rapidly, which may modify the ecological context of populations, and thus the selection pressures they will be exposed to. Here we review evidence for such eco‐evolutionary processes. We discuss examples of eco‐evolutionary change in an attempt to understand the challenges related with identifying and characterizing such processes. In particular, we focus on the challenges associated with accurately identifying the components of the feedback as well as their causal relation. Finally, we evaluate scenarios where understanding eco‐evolutionary feedbacks of sexual selection may help us appreciate the effects of sexual selection in shaping evolutionary processes.     

Root exudation of carbohydrates and cations from barley in response to drought and elevated CO2

Plant and Soil - Citrate secretion is a kind of typical strategy for plant against aluminum (Al) toxicity. However, the signaling process in Al-activated citrate secretion needs to be clarified....