Constant Environmental Conditions Research Articles

The nitrogen deficiency influence on the growth and development of spring two-nuclear barley varieties grown under photoculture conditions

The purpose of the research is to study, the effect of N deficiency in irrigation solutions on the structural and functional characteristics of spring barley (Hordeum vulgare L.), the Oplot variety under controlled environmental conditions, in comparison with the structural and functional characteristics of Takmak barley, which has been the standard in all variety testing sites of the Krasnoyarsk Territory since 2022. The plants were grown under light culture conditions using hydroponics on expanded clay with constant environmental conditions at a photoperiod day/night of 17h / 7h, respectively. The basis for the preparation of irrigation solutions was Knop solution (control) and a solution in which, in order to reduce the concentration of N-NO3, the salt content was changed 2 times so as not to change the concentration of other macronutrients. A comparison of the rate of absorption of macronutrients by barley plants of the Oplot and Takmak varieties, depending on the composition of the irrigation solution, shows a higher demand of the barley of the Oplot variety for the presence of mineral nutrition elements in the irrigation solution in comparison with the barley of the Takmak variety. The deficiency of N in the irrigation solution led to a decrease in total tillering by about 2.5 times, but productive tillering in the barley of the Oplot variety decreased to a greater extent than in the barley of the Takmak variety. When growing on Knop solution the barley of the Oplot variety showed higher productivity than the barley of the Takmak variety. When grown on solutions with a deficiency of N, the grain yield of the barley of the Oplot variety decreased by 2.8 times, and in the barley of the Takmak variety, the differences between the control and experimental variants were unreliable. The barley of the Takmak variety showed higher resistance to N deficiency in the irrigation solution, thereby showing higher plasticity compared to the barley of the Oplot variety.

Suprachiasmatic nucleus VIPergic fibers show a circadian rhythm of expansion and retraction

In animals, overt circadian rhythms of physiology and behavior are centrally regulated by a circadian clock located in specific brain regions. In the fruit fly Drosophila and in mammals, these clocks rely on single-cell oscillators, but critical for their function as central circadian pacemakers are network properties that change dynamically throughout the circadian cycle as well as in response to environmental stimuli.1,2,3 In the fly, this plasticity involves circadian rhythms of expansion and retraction of clock neuron fibers.4,5,6,7,8,9,10,11,12,13,14 Whether these drastic structural changes are a universal property of central neuronal pacemakers is unknown. To address this question, we studied neurons of the mouse suprachiasmatic nucleus (SCN) that express vasoactive intestinal polypeptide (VIP), which are critical for the SCN to function as a central circadian pacemaker. By targeting the expression of the fluorescent protein tdTomato to these neurons and using tissue clearing techniques to visualize all SCN VIPergic neurons and their fibers, we show that, similar to clock neurons in the fly, VIPergic fibers undergo a daily rhythm of expansion and retraction, with maximal branching during the day. This rhythm is circadian, as it persists under constant environmental conditions and is present in both males and females. We propose that circadian structural remodeling of clock neurons represents a key feature of central circadian pacemakers that is likely critical to regulate network properties, the response to environmental stimuli, and the regulation of circadian outputs.

Mosquito population dynamics is shaped by the interaction among larval density, season, and land use.

Understanding how variation in key abiotic and biotic factors interact at spatial scales relevant for mosquito fitness and population dynamics is crucial for predicting current and future mosquito distributions and abundances, and the transmission potential for human pathogens. However, studies investigating the effects of environmental variation on mosquito traits have investigated environmental factors in isolation or in laboratory experiments that examine constant environmental conditions that often do not occur in the field. To address these limitations, we conducted a semi-field experiment in Athens, Georgia using the invasive Asian tiger mosquito ( Aedes albopictus ). We selected nine sites that spanned natural variation in impervious surface and vegetation cover to explore effects of the microclimate (temperature and humidity) on mosquitoes. On these sites, we manipulated conspecific larval density at each site. We repeated the experiment in the summer and fall. We then evaluated the effects of land cover, larval density, and time of season, as well as interactive effects, on the mean proportion of females emerging, juvenile development time, size upon emergence, and predicted per capita population growth (i.e., fitness). We found significant effects of larval density, land cover, and season on all response variables. Of most note, we saw strong interactive effects of season and intra-specific density on each response variable, including a non-intuitive decrease in development time with increasing intra-specific competition in the fall. Our study demonstrates that ignoring the interaction between variation in biotic and abiotic variables could reduce the accuracy and precision of models used to predict mosquito population and pathogen transmission dynamics, especially those inferring dynamics at finer-spatial scales across which transmission and control occur.

Changes in body surface temperature reveal the thermal challenge associated with catastrophic moult in captive gentoo penguins.

Once a year, penguins undergo a catastrophic moult, replacing their entire plumage during a fasting period on land or on sea-ice during which time individuals can lose 45% of their body mass. In penguins, new feather synthesis precedes the loss of old feathers, leading to an accumulation of two feather layers (double coat) before the old plumage is shed. We hypothesized that the combination of the high metabolism required for new feather synthesis and the potentially high thermal insulation linked to the double coat could lead to a thermal challenge requiring additional peripheral circulation to thermal windows to dissipate the extra heat. To test this hypothesis, we measured the surface temperature of different body regions of captive gentoo penguins (Pygoscelis papua) throughout the moult under constant environmental conditions. The surface temperature of the main body trunk decreased during the initial stages of the moult, suggesting greater thermal insulation. In contrast, the periorbital region, a potential proxy of core temperature in birds, increased during these same early moulting stages. The surface temperature of the bill, flipper and foot (thermal windows) tended to initially increase during the moult, highlighting the likely need for extra heat dissipation in moulting penguins. These results raise questions regarding the thermoregulatory capacities of penguins in the wild during the challenging period of moulting on land in the current context of global warming.

Biodiversity is enhanced by sequential resource utilization and environmental fluctuations via emergent temporal niches.

How natural communities maintain their remarkable biodiversity and which species survive in complex communities are central questions in ecology. Resource competition models successfully explain many phenomena but typically predict only as many species as resources can coexist. Here, we demonstrate that sequential resource utilization, or diauxie, with periodic growth cycles can support many more species than resources. We explore how communities modify their own environments by sequentially depleting resources to form sequences of temporal niches, or intermediately depleted environments. Biodiversity is enhanced when community-driven or environmental fluctuations modulate the resource depletion order and produce different temporal niches on each growth cycle. Community-driven fluctuations under constant environmental conditions are rare, but exploring them illuminates the temporal niche structure that emerges from sequential resource utilization. With environmental fluctuations, we find most communities have more stably coexisting species than resources with survivors accurately predicted by the same temporal niche structure and each following a distinct optimal strategy. Our results thus present a new niche-based approach to understanding highly diverse fluctuating communities.

Obesity to Type 2 Diabetes Mellitus: Importance of Longitudinal Characterization of the Progressive Phases as Identified in Rhesus Monkeys Maintained Under Constant Diet and Environmental Conditions

The complex physiological mechanisms that underlie the links between obesity and T2DM involve “adiposity-induced” alterations in beta cell function —not yet mechanistically understood. Clearly the changes in beta cell function are greatly increased during the progression of obesity, --not reduced!! AND multiorgan insulin resistance whose mechanisms are unknown (although likely reduced by weight loss). Rhesus monkeys have shown these and have provided an amazing look at the Phases that lead to T2DM. We have previously summarized, in a table of 49 variables, the many ways that the nonhuman primate rhesus monkey offers exciting opportunities for insight into these extraordinary conditions compared to the human with T2DM. The Importance of longitudinal characterization, with a number of measurements that are regularly and periodically carried out to assess longitudinally some of the pathophysiological processes that develop spontaneously and naturally in these monkeys as they progress from normal, lean, young animals to obese animals with or without various physiological disturbances undergo the aging process. Usually these disturbances develop at varying rates in different monkeys and include hypertension, hyperlipidemia, hyperinsulinemia, hyperglycemia, impaired glucose tolerance, insulin resistance, peripheral neuropathy, impaired renal clearance, and cardiovascular disease—in short, the entire syndrome that becomes manifest in aged and diabetic humans. The longitudinal studies depend specifically on regular assessment of each animal and determination of the rate at which that animal is or is not progressing in the development of pathophysiological disturbances. Identification of phases allows one to estimate where a given monkey is in regard to the progression to overt diabetes. Application to humans will greatly increase our predictive ability to understand the mechanisms underlying both obesity and T2DM. NIA NO1AG3 1012. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The contribution of biological sex to heat stress-mediated outcomes in growing pigs

Heat stress (HS) negatively impacts a variety of production parameters in growing pigs; however, the impact of biological sex on the HS response is largely unknown. To address this, 48 crossbred barrows and gilts (36.8 ± 3.7 kg BW) were individually housed and assigned to one of three constant environmental conditions: (1) thermoneutral (TN) (20.8 ± 1.6 °C; 62.0 ± 4.7% relative humidity; n = 8/sex), (2) HS (39.4 ± 0.6 °C; 33.7 ± 6.3% relative humidity) for 1 d (HS1; n = 8/sex), or (3) or for 7 d (HS7; n = 8/sex). As expected, HS increased rectal temperature (Tr) following 1 d of HS (1.0 °C; P < 0.0001) and 7 d of HS (0.9 °C; P < 0.0001). By 7 d, heat-stressed gilts were cooler than barrows (0.4 °C; P = 0.016), despite identical heating conditions. There was a main effect of sex such that barrows had higher Tr than gilts (P = 0.031). Heat-stressed pigs on d 1 had marked reductions in feed intake and BW compared to TN (P < 0.0001). One day of HS resulted in negative gain to feed (G:F) in barrows and gilts and was reduced compared to TN (P < 0.0001). Notably, following 1 d of HS, the variability of G:F was greater in gilts than in barrows. Between 1 and 7 d of HS, G:F improved in barrows and gilts and were similar to TN pigs, even though HS barrows had higher Tr than gilts over this period. Heat stress for 1 and 7 d reduced empty gastrointestinal tract weight compared to TN (P < 0.0001). Interestingly, HS7 gilts had decreased gastrointestinal tract weight compared to HS1 gilts (2.43 vs 2.72 kg; P = 0.03), whereas it was similar between HS1 and HS7 barrows. Lastly, a greater proportion of gastrointestinal contents was in the stomach of HS1 pigs compared to TN and HS7 (P < 0.05), which is suggestive of decreased gastric emptying. Overall, HS barrows maintained an elevated Tr compared to HS gilts through the duration of the experiment but also maintained similar growth and production metrics compared to gilts, despite this higher temperature.

Establishment of the microscope incubation system and its application in evaluating tumor treatment effects through real-time live cellular imaging.

Introduction: Long-term imaging of live cells is commonly used for the study of dynamic cell behaviors. It is crucial to keep the cell viability during the investigation of physiological and biological processes by live cell imaging. Conventional incubators that providing stable temperature, carbon dioxide (CO2) concentration, and humidity are often incompatible with most imaging tools. Available commercial or custom-made stage-top incubators are bulky or unable to provide constant environmental conditions during long time culture. Methods: In this study, we reported the development of the microscope incubation system (MIS) that can be easily adapted to any inverted microscope stage. Incremental PID control algorithm was introduced to keep stable temperature and gas concentration of the system. Moreover, efficient translucent materials were applied for the top and bottom of the incubator which make it possible for images taken during culture. Results: The MIS could support cell viability comparable to standard incubators. When used in real time imaging, the MIS was able to trace single cell migration in scratch assay, T cell mediated tumor cells killing in co-culture assay, inflation-collapse and fusion of organoids in 3D culture. And the viability and drug responses of cells cultured in the MIS were able to be calculated by a label-free methods based on long term imaging. Discussion: We offer new insights into monitoring cell behaviors during long term culture by using the stage adapted MIS. This study illustrates that the newly developed MIS is a viable solution for long-term imaging during in vitro cell culture and demonstrates its potential in cell biology, cancer biology and drug discovery research where long-term real-time recording is required.

How accurate are automated sorption balances? An analysis of errors in wood moisture content from uncertainties in the conditioning environment

Automated sorption balances are increasingly used to determine sorption isotherms of hygroscopic materials like wood. The sorption isotherms are constructed based on a number of equilibrium states between a specimen and the surrounding conditioning environment. In recent years, the uncertainty of these equilibrium states has been thoroughly discussed related to the time at constant environmental conditions needed to reach an adequate mass stability. However, uncertainties related to the conditioning environment are rarely discussed. This study describes a framework for analyzing and quantifying the effect of these uncertainties on the error in determined equilibrium moisture content. Various effects of the conditioning environment are analyzed, and the most important effects relate to the relative humidity (RH) in the instruments, both in terms of fluctuations in RH and an offset from the target value. The moisture error for these effects was found within the range 0.001–0.01 g g−1.

Nighttime Lighting Influences on the Plankton Feeding and Growth of Juvenile Pacific Bluefin Tuna, Thunnus orientalis.

During fingerling production of Pacific bluefin tuna (PBF) Thunnus orientalis, heavy mortality can occur immediately after juveniles are transferred from nursery tanks to sea cages; however, nighttime lighting can moderate this mortality. Additionally, various live prey aggregate due to nighttime lighting in practical sea cage culture of PBF. Here, we investigated whether the growth and viability of PBF juveniles could be improved through promoting feeding on live prey that aggregate under nighttime lighting. Two treatment groups were established using land-based tanks under constant environmental conditions, one in which the juveniles were fed live prey at night (night-feed in four replicate tanks) and the other in which juveniles were not fed during the night (control in four replicate tanks). Although the survival rate did not differ significantly between the two groups, growth was significantly improved in the night-feed group, in which 69-78% of the juveniles showed evidence of feeding during the night. Thus, nighttime lighting plays a vital role in the aggregation of various live prey. PBF juveniles consume these prey in sea cages, which promotes their growth. This may partially serve as a countermeasure against the heavy mortality observed in sea cages.

A new approach for modeling stand height development of German forests under climate change

IntroductionWe developed a new approach for site index curve models that combines longitudinal height development patterns derived from state-space data with the broad environmental conditions covered by space-for-time data.MethodsFor this, we gathered dendrometry from both inventories and research plots. Concerning environmental variables, we included soil mapping data as well as atmospheric data, i.e., precipitation, temperature, and nitrogen deposition. The atmospheric data was included as a weighted mean over the stand life of the sums for the dynamically determined vegetation period or as yearly sums in the case of nitrogen deposition, respectively. As a weight, the values of a height increment function were used. Then, we derived the basic shape of a height development curve from research plot data and transferred said shape to a site index curve model.ResultsThe model represents a substantial advancement of a previous version and was fitted as a generalized additive model (GAM). All effects were of relevant size and showed biologically feasible patterns.DiscussionThough the model is biased for young ages, we could predict site index curves that, under constant environmental conditions, closely follow yield table curves and thus accurately depict stand height development. Moreover, the model does not require initial dendrometry, which broadens its applicability. Thus, the model represents a useful tool for forest management and planning under climate change.

Critical calls: Circadian and seasonal periodicity in vocal activity in a breeding colony of Panamanian golden frogs (Atelopus zeteki).

The Panamanian golden frog (Atelopus zeteki) is a critically endangered species and currently is believed to survive and reproduce only in human care. Panamanian golden frog males are considerably vocal which may be an important component in their successful reproduction, though little is currently known about their calls. To better understand the behavior and vocal patterns of this species and to improve breeding efforts in the assurance colony, we employed individual sound recording of male advertisement calls and acoustic monitoring of a breeding colony to investigate variation in the vocal behavior of Panamanian golden frogs. The goal was to capture variability within and among frogs as well as patterns of periodicity over time. First, the advertisement calls from individual male Panamanian golden frogs were recorded, and acoustic parameters were analyzed for individual differences. Results suggest that male advertisement calls demonstrate individual- and population specificity. Second, data collected through a year-long acoustic monitoring of the breeding colony were investigated for circadian and circannual periodicity. Male vocal activity revealed a circadian periodicity entrained by the daily light schedule. Seasonal periodicity was also found with highest vocal activities between December and March. The finding of a seasonal periodicity is worth noting given that the population had been bred for 20 years under constant environmental conditions. Finally, results suggest that vocal activity was responsive to daily animal care activity. Vocal activity decreased substantially when personnel entered the room and engaged in animal husbandry activities. The findings illustrate the usefulness of acoustic monitoring to provide insight into animal behavior in a zoo setting in a key breeding colony of endangered animals, and calling pattern observations may be utilized to modify husbandry practices to improve Panamanian golden frog breeding success and general care.

Predictive Modeling and Computer Vision-Based Decision Support to Optimize Resource Use in Vertical Farms

This study evaluated several decision-support tools that can be used to create a control system capable of taking advantage of fluctuations in the price of resources and improving the energy use efficiency of growing crops in vertical farms. A mechanistic model was updated and calibrated for use in vertical farm environments. This model was also validated under changing environmental conditions with acceptable agreement with empirical observations for the scenarios considered in this study. It was also demonstrated that lettuce plants use carbon dioxide (CO2) more efficiently later in their development, producing around 22% more biomass during high CO2 conditions during the fourth-week post-transplant than in the first week. A feedback mechanism using top-projected canopy area (TPCA) was evaluated for its ability to correlate with and provide remote biomass estimations. It was shown that for a given set of constant environmental conditions, a scaling factor of 0.21 g cm−2 allowed the TPCA to serve as a rough proxy for biomass in the period prior to canopy closure. The TPCA also was able to show deviation from expected growth under changing CO2 concentrations, justifying its use as a feedback metric.

Toward a logistic model of dynamic mold growth on wood

This paper deals with mathematical modeling of mold growth on wood. The logistic growth equation is used to model mold growth phenomena in changing environmental conditions. Microscopic mold coverage fraction is used in the logistic equation to represent mold development on a material surface over time. The current state-of-the-art dynamic Finnish mold growth model is used as the reference model for development of the logistic mold growth model. The optimal values of mold growth coefficient are estimated by simulations of mold growth under constant environmental conditions and by finding the best agreement with the Finnish mold growth model using mathematical optimization methods. It is shown that the mold growth coefficient can be approximated as a function of relative humidity, temperature, wood species and the quality of the surface. The model parameters are then verified by a comparison with the Finnish mold growth model. In this case, cyclic step changes of constant relative humidity are used. Finally, the logistic mold growth model is compared with published experimental observations of mold growth. The discrepancy of mold growth models and experimental mold growth data, and possible improvements are discussed.

Is obstructive sleep apnea a circadian rhythm disorder?

Obstructive sleep apnea is the most common sleep-related breathing disorder worldwide and remains underdiagnosed. Its multiple associated comorbidities contribute to a decreased quality of life and work performance as well as an increased risk of death. Standard treatment seems to have limited effects on cardiovascular and metabolic aspects of the disease, emphasising the need for early diagnosis and additional therapeutic approaches. Recent evidence suggests that the dysregulation of circadian rhythms, processes with endogenous rhythmicity that are adjusted to the environment through various cues, is involved in the pathogenesis of comorbidities. In patients with obstructive sleep apnea, altered circadian gene expression patterns have been demonstrated. Obstructive respiratory events may promote circadian dysregulation through the effects of sleep disturbance and intermittent hypoxia, with subsequent inflammation and disruption of neural and hormonal homeostasis. In this review, current knowledge on obstructive sleep apnea, circadian rhythm regulation, and circadian rhythm sleep disorders is summarised. Studies that connect obstructive sleep apnea to circadian rhythm abnormalities are critically evaluated. Furthermore, pathogenetic mechanisms that may underlie this association, most notably hypoxia signalling, are presented. A bidirectional relationship between obstructive sleep apnea and circadian rhythm dysregulation is proposed. Approaching obstructive sleep apnea as a circadian rhythm disorder may prove beneficial for the development of new, personalised diagnostic, therapeutic and prognostic tools. However, further studies are needed before the clinical approach to obstructive sleep apnea includes targeting the circadian system.

Using Simulations to Evaluate the Utility of Geohistorical Reference Conditions for Assessing Ecological Quality

Incorporating paleontological data into the methods and formats familiar to conservation practitioners may facilitate greater use of paleontological data in conservation practice. Benthic indices (e.g., Multivariate-AZTI Marine Biotic Index; M-AMBI) utilize reference conditions for monitoring ecological conditions. However, reference conditions from monitoring records are limited in temporal scope and often represent degraded conditions, which can cause inaccurate assessments of ecological quality. Paleontological data, such as molluscan death assemblages, have potential to provide long-term, location-specific reference conditions, which are otherwise inaccessible to decision-makers. Here we use simulations of living communities under constant and changing environmental conditions to evaluate the capacity of death assemblage reference conditions to replicate M-AMBI values when used in place of reference conditions from the living communities. Reference conditions from all death assemblage scenarios successfully replicated correct remediation decisions in most simulation runs with environmental change and stability. Variations in M-AMBI values were due to overestimated species richness and Shannon entropy values in the death assemblages and effects of changes to these parameters varied across scenarios. Time averaging was largely beneficial, particularly when environmental change occurred, and short-term observations of the living communities produced incorrect remediation decisions. When the duration of time averaging is known, death assemblages can provide valuable longer-term perspectives with the potential to outperform temporally constrained baseline information from monitoring the living community.

AsiaRiceYield4km: seasonal rice yield in Asia from 1995 to 2015

Abstract. Rice is the most important staple food in Asia. However, high-spatiotemporal-resolution rice yield datasets are limited over this large region. The lack of such products greatly hinders studies that are aimed at accurately assessing the impacts of climate change and simulating agricultural production. Based on annual rice maps in Asia, we incorporated multisource predictors into three machine learning (ML) models to generate a high-spatial-resolution (4 km) seasonal rice yield dataset (AsiaRiceYield4km) for the 1995–2015 period. Predictors were divided into four categories that considered the most comprehensive rice growth conditions, and the optimal ML model was determined based on an inverse probability weighting method. The results showed that AsiaRiceYield4km achieves good accuracy for seasonal rice yield estimation (single rice: R2=0.88, RMSE = 920 kg ha−1; double rice: R2=0.91, RMSE = 554 kg ha−1; and triple rice: R2=0.93, RMSE = 588 kg ha−1). Compared with single rice from the Spatial Production Allocation Model (SPAM), the R2 of AsiaRiceYield4km was improved by 0.20, and the RMSE was reduced by 618 kg ha−1 on average. In particular, constant environmental conditions, including longitude, latitude, elevation and soil properties, contributed the most (∼ 45 %) to rice yield estimation. For different rice growth periods, we found that the predictors of the reproductive period had greater impacts on rice yield prediction than those of the vegetative period and the whole growing period. AsiaRiceYield4km is a novel long-term gridded rice yield dataset that can fill the unavailability of high-spatial-resolution seasonal yield products across major rice production areas and promote more relevant studies on agricultural sustainability worldwide. AsiaRiceYield4km can be downloaded from the following open-access data repository: https://doi.org/10.5281/zenodo.6901968 (Wu et al., 2022).

Middle platform carbonate depositional systems and lithofacies patterns in the Lower Ordovician Ellenburger Group, Tobosa Basin in West Texas, U.S.A., and subsequent Sauk-Tippecanoe megasequence boundary meteoric karsting

A long, continuous core (1155 ft; 352 m) from the Ellenburger Group in Upton County, Texas allowed for a detailed reservoir description of depositional setting, lithofacies, pore networks, and impact of subsequent karst processes on the reservoir geology. This reservoir description furthers the understanding of the origin and characteristics of pore types relevant for waste-water disposal, carbon dioxide storage, and hydrocarbon reservoir quality in the Ellenburger Group. The Lower Ordovician Ellenburger Group in West Texas is a thick dolomite sequence that was deposited on a broad shelf over a 16 m.y. Time period in the Tobosa Basin. The shallow-water restricted depositional setting produced carbonate sediments that are dominantly composed of middle-shelf microbial thrombolite boundstones and inner-shelf laminated (stromatolitic) mudstones. Recognizable skeletal grains are rare. The lower two thirds of the cored section in the area of investigation in Upton County, Texas is dominated by microbial thrombolite complexes with associated stromatactis features. Interbeds of oolites and evaporites are associated with the complexes and may represent small-scale fluctuations in relative sea level. Up-section, lithofacies transition into a peritidal complex composed of stromatolites and laminated mudstones, some displaying evaporite nodules. The lithofacies stacking pattern is similar to the regional established stacking pattern where the most open-marine lithofacies are at the base of the stratigraphic section and the most restricted lithofacies are at the top of the stratigraphic section. This consistent stacking pattern suggests a stable structural setting for millions of years where constant environmental conditions existed. Following deposition and subsequent lithification and dolomitization of the Ellenburger Group, the section underwent intense meteoric karsting (epigenic) during Late Middle Ordovician Sauk-Tippecanoe megasequence long-term exposure. The meteoric karsting affected the upper 700 ft (215 m) of the Ellenburger Group. The pore network in the studied core is composed of vuggy (small cavities) pores in the thrombolite lithofacies and crackle and mosaic breccia fracture pores and chaotic breccias interbreccia pores in karst-affected intervals. These pore systems support hydrocarbon production, waste-water disposal, and carbon-dioxide storage.

Inducible Reporter Lines for Tissue-specific Monitoring of Drosophila Circadian Clock Transcriptional Activity

Organisms track time of day through the function of cell-autonomous molecular clocks. In addition to a central clock located in the brain, molecular clocks are present in most peripheral tissues. Circadian clocks are coordinated within and across tissues, but the manner through which this coordination is achieved is not well understood. We reasoned that the ability to track in vivo molecular clock activity in specific tissues of the fruit fly, Drosophila melanogaster, would facilitate an investigation into the relationship between different clock-containing tissues. Previous efforts to monitor clock gene expression in single flies in vivo have used regulatory elements of several different clock genes to dictate expression of a luciferase reporter enzyme, the activity of which can be monitored using a luminometer. Although these reporter lines have been instrumental in our understanding of the circadian system, they generally lack cell specificity, making it difficult to compare molecular clock oscillations between different tissues. Here, we report the generation of several novel lines of flies that allow for inducible expression of a luciferase reporter construct for clock gene transcriptional activity. We find that these lines faithfully report circadian transcription, as they exhibit rhythmic luciferase activity that is dependent on a functional molecular clock. Furthermore, we take advantage of our reporter lines' tissue specificity to demonstrate that peripheral molecular clocks are able to retain rhythmicity for multiple days under constant environmental conditions.

Coherent tracer correlations in deep-sea corals and implications for biomineralization mechanisms underlying vital effects

Deep-sea corals are a useful archive of thermocline, intermediate, and deep waters in past oceans. However, application of traditional oceanographic tracers to deep-sea corals remains a challenge due to our insufficient understanding of their “vital effects”. Deep-sea corals are ideal test organisms to study the mechanism underlying vital effects generally, due to the large tracer gradients in individual corals living under relatively constant environmental conditions. Lessons learned from these corals might apply to other scleractinia and to marine calcifiers more generally. Here we present stable isotope, minor and trace metal (Me/Ca ratios) data in a suite of modern Desmophyllum dianthus specimens, collected over multiple spatial scales in individual corals (bulk, micromill, SIMS, NanoSIMS), with multi-proxy analyses made on the same material whenever possible. Spatially coherent Me/Ca correlations are observed in the fibrous aragonite of individual corals, including positive correlations between Mg/Ca, Li/Ca and B/Ca, as well as negative correlations between Mg/Ca and Sr/Ca, consistent with previous studies. We also for the first time document strong correlations between the isotopic (δ18O and δ13C) and elemental compositions of the skeletons, most notably a negative correlation between δ18O and Mg/Ca. The centers of calcification (COCs) in the coral skeletons show distinct tracer correlations from the aragonite fibers that possibly reflect a more complicated formation mechanism. We interpret the spatially coherent tracer correlations in deep-sea corals with a numerical model of coral calcification previously developed for stable isotopes that considers the role of the enzyme carbonic anhydrase in the calcification processs. With the carbonate chemistry in the model constrained by the stable isotope data, we are able to explain the observed Me/Ca correlations as well as their range of variability, as a result of internal pH elevation in the extracellular calcifying fluid (ECF) of the corals with limited Ca-pumping through the calicoblastic membrane. In particular, the positive Mg/Ca–B/Ca correlation in the fibrous aragonite suggests a borate (B(OH)4–) substitution for carbonate ion (CO32–) incorporation mechanism in biogenic aragonite. We also suggest the growth rate dependence of the incorporation of minor and trace elements based conceptually on an ion-by-ion growth model may help explain the absolute Me/Ca values in biogenic aragonites. Finally, we generally find more limited tracer variability in corals from undersaturated seawater compared to their counterparts from supersaturated conditions, suggesting a limit to their internal pH elevation in response to this environmental stress. Understanding the biomineralization mechanisms underlying the vital effects is important for better use of these tracers for paleoceanographic applications, and may shed light on the response of marine calcification to future ocean acidification.