Feeding Cycle Research Articles

The influence of feeding on the daily rhythm of mRNA expression on melatonin bio-synthesizing enzyme genes and clock associated genes in the zebrafish (Danio rerio) gut

ABSTRACT The study aimed to investigate the presence of melatonin bio-synthesizing enzyme genes in the zebrafish gut and its daily mRNA expression profile along with core clock genes in different feeding regime under regular photoperiod. Zebrafish were randomly distributed in the laboratory condition into two feeding groups; one was regular feeding (NF), where food was supplied at light phase. Another was the altered feeding (AF), where food was provided at the dark phase for 30 days. Primarily, the presence of melatonin bio-synthesizing machinery has been demonstrated in the zebrafish gut through immunohistochemistry and End Point PCR. Subsequently, the transcript profile of the said genes was analyzed by qRT-PCR. The study reveals an opposite phage in the daily mRNA expression of tph1, aanat2, and asmt in AF, concerning the NF condition. In contrast, all core clock genes in the gut display a rhythmic expression without any change in the acrophase, irrespective of the feeding schedule, indicating melatonin production may be controlled through the feeding cycle. Still, clock genes need other influence to entrain. The change in the rhythmic expression of the bio-synthesizing enzyme genes of the chronobiotic molecule through feeding may lead to desynchronization in fish physiology.

Daily rhythms in the morphometric parameters of hepatocytes and intestine of the European sea bass (Dicentrarchus labrax): influence of feeding time and hepatic zonation.

The digestive system presents daily rhythms at both physiological and histological levels. Although cell morphology rhythms in mammals have been reported, they have scarcely been investigated in fish. The aim of the present research was to investigate the existence of daily rhythms in the morphology of cells in the liver and intestine of a teleost fish, the European sea bass (Dicentrarchus labrax), and how feeding time influences them. Regarding liver, we also focused on differences between the two metabolic zones: perivenous and periportal. For this purpose, fish were divided into two groups: fish fed once a day in the mid-light phase (ML) or the mid-dark phase (MD). After 1 month under each feeding regime, liver and intestine samples were collected every 4h during a 24-h cycle, and different parameters were studied by light microscopyand image analysis. Daily rhythms occurred in most of the parameters evaluated in the liver. The effect of feeding time depended on the metabolic zone: the rhythms in the periportal zone were synchronized mainly by the light/dark cycle regardless of feeding time, whereas in the perivenous zone, rhythms were influenced more by feeding time. In the intestine, a daily rhythm in villi height was found with acrophases coinciding with feeding time in each group. These findings show for the first time the existence of cellular morphological rhythms in fish liver and intestine, and highlight the interactions between light and feeding cycles in the different metabolic zones of the liver.

Intermittent feeding in intensive care – the theory and practice

Nutrition therapy becomes one of the fundamental conditions of asuccessful outcome in malnourished patients and in critically ill patients. The administration of enteral feeding in critically ill patients is mostly performed by continuous or cyclic feeding. On the contrary, the potential benefits of intermittent feeding include increased muscle protein synthesis. This review outlines the theory of apossible anabolic effect of intermittent feeding. The authors describe their experience with implementation of this method of administration in the intensive care unit including the follow-up of possible complications and adverse effects. Six patients with intermittent feeding were followed retrospectively during the study period. In addition to demographic data, potential complications related to intermittent enteral feeding (aspiration pneumonia, increased gastric residual volume, abdominal discomfort, osmotic diarrhoea) were evaluated. The average time of intermittent feeding was 8 days. The sum of intermittent feeding days was 63. No aspiration followed by pneumonia was detected during this period. The gastric residual volume did not increase, either. Abdominal discomfort and osmotic diarrhoea were not observed in any patient. Although continuous and cyclic enteral feeding in critically ill patients remains the standard and the most common practice, it is considered as anon-physiological method with possible negative consequences for the patient. On the other hand, intermittent feeding is theoretically associated with respecting of the circadian rhythm and with activation of autophagy. Intermittent feeding increases muscle protein synthesis and supports the release of fatty acids. As shown by our observational study, intermittent administration of enteral nutrition in intensive care can be implemented without any adverse effects; however, it is more time consuming for the nurses.

Weight prediction of pork cuts and tissue composition using spectral graph wavelet

The manual quality assessment of a pork half-carcass using cutting and dissection process is time-consuming, financially expensive, and requires expert butchers. Recently, no technology is available for the automatic quality assessment of pork carcasses to maximize their market value through studying pig feeding cycle, changes in genetic lines, and feeding methods. In this paper, a novel approach for the quality assessment of pork carcasses using 3D shape analysis is proposed. First, a pork half-carcass is precisely modeled by harnessing the power of the spectral graph wavelets, called SpectralWeight. Then, the SpectralWeight is exploited as a predictive model to weigh different cuts and tissue composition of pork. Our study on employing SpectralWeight for weight prediction of a variety of pork cuts including primal and commercial cuts as well as tissue composition of pork demonstrates high accuracy of prediction for most cuts. Although in this work the performance of SpectralWeight for the weight prediction of pork cuts is evaluated, our framework is fairly general and enables new ways to estimate the quality and economical value of carcasses of different animals.

Plasticity of Foraging Strategies Adopted by the Painted Ghost Crab, Ocypode gaudichaudii, in Response to in situ Food Resource Manipulation Experiments.

The feeding strategies of Ocypode gaudichaudii at two sandy beaches, Culebra Beach (CB) and Playa Venao (PV) in Panama, were studied via three experiments. Two separate manipulative in situ experiments were conducted to determine how the densities of food resources and the size of the supplemented food offered to the crabs can affect their diet and food handling behavior. The third experiment, a transplantation study, was also conducted to determine the plasticity of the feeding behavior of the displaced crabs. In the first experiment, freshly-emerged crabs showed different feeding modes when washed-sediment was seeded with different densities of diatoms and rove beetles, which suggests that they are optimal foragers. Crabs hoarded food in the second experiment when food augmentation was performed, in which small and large food pellets were placed around the burrows at the beginning and end of the crabs' feeding cycle. All freshly-emerged crabs from both sites foraged on the small pellets outside their burrows and did not cache food; when pellets were provided at the end of the feeding cycle, crabs from CB fed on some of the small pellets and returned to their burrows with the uneaten pellets left on the surface, whereas crabs at PV picked up all the small food pellets and transferred them into their burrows over several trips before plugging their burrow entrances. Only the crabs from PV carried the large food pellets supplemented at the start and end of the feeding cycle into their burrows. In contrast, the crabs at CB often left behind the partially-eaten pellets on the sand surface, probably due to the increased risk of predation associated with the prolonged handling time of the large food pellets. Excavation of the burrows of the crabs that hoarded food showed that all the pellets were deposited at the bend of the burrows, indicating that they were not consumed immediately. Crabs that fed in droves at PV stopped droving and foraged around their burrows after being transplanted to CB. This is the first documentation of food hoarding in a sandy beach macroinvertebrate at a resource-impoverished habitat. The plasticity of feeding strategies adopted by the painted ghost crab in response to different densities of food resources in the habitat could be an adaptation to the dynamic sandy beach environment.

Multiple blood feeding in mosquitoes shortens the Plasmodium falciparum incubation period and increases malaria transmission potential.

Many mosquito species, including the major malaria vector Anopheles gambiae, naturally undergo multiple reproductive cycles of blood feeding, egg development and egg laying in their lifespan. Such complex mosquito behavior is regularly overlooked when mosquitoes are experimentally infected with malaria parasites, limiting our ability to accurately describe potential effects on transmission. Here, we examine how Plasmodium falciparum development and transmission potential is impacted when infected mosquitoes feed an additional time. We measured P. falciparum oocyst size and performed sporozoite time course analyses to determine the parasite's extrinsic incubation period (EIP), i.e. the time required by parasites to reach infectious sporozoite stages, in An. gambiae females blood fed either once or twice. An additional blood feed at 3 days post infection drastically accelerates oocyst growth rates, causing earlier sporozoite accumulation in the salivary glands, thereby shortening the EIP (reduction of 2.3 ± 0.4 days). Moreover, parasite growth is further accelerated in transgenic mosquitoes with reduced reproductive capacity, which mimic genetic modifications currently proposed in population suppression gene drives. We incorporate our shortened EIP values into a measure of transmission potential, the basic reproduction number R0, and find the average R0 is higher (range: 10.1%-12.1% increase) across sub-Saharan Africa than when using traditional EIP measurements. These data suggest that malaria elimination may be substantially more challenging and that younger mosquitoes or those with reduced reproductive ability may provide a larger contribution to infection than currently believed. Our findings have profound implications for current and future mosquito control interventions.

The WISSH quasars project

Context. Sources at the brightest end of the quasi-stellar object (QSO) luminosity function, during the peak epoch in the history of star formation and black hole accretion (z ∼ 2−4, often referred to as “Cosmic noon”) are privileged sites to study the cycle of feeding & feedback processes in massive galaxies. Aims. We aim to perform the first systematic study of cold gas properties in the most luminous QSOs, by characterising their host-galaxies and environment. These targets exhibit indeed widespread evidence of outflows at nuclear and galactic scales. Methods. We analyse ALMA, NOEMA and JVLA observations of the far-infrared continuum, CO and [CII] emission lines in eight QSOs (bolometric luminosity LBol ≳ 3 × 1047 erg s−1) from the WISE-SDSS selected hyper-luminous (WISSH) QSOs sample at z ∼ 2.4−4.7. Results. We report a 100% emission line detection rate and a 80% detection rate in continuum emission, and we find CO emission to be consistent with the steepest CO ladders observed so far. Sub-millimetre data reveal presence of (one or more) bright companion galaxies around ∼80% of WISSH QSOs, at projected distances of ∼6−130 kpc. We observe a variety of sizes for the molecular gas reservoirs (∼1.7−10 kpc), mostly associated with rotating disks with disturbed kinematics. WISSH QSOs typically show lower CO luminosity and higher star formation efficiency than infrared matched, z ∼ 0−3 main-sequence galaxies, implying that, given the observed SFR ∼170−1100 M⊙ yr−1, molecular gas is converted into stars in ≲50 Myr. Most targets show extreme dynamical to black-hole mass ratios Mdyn/MBH ∼ 3−10, two orders of magnitude smaller than local relations. The molecular gas fraction in the host-galaxies of WISSH is lower by a factor of ∼10−100 than in star forming galaxies with similar M*. Conclusions. Our analysis reveals that hyper-luminous QSOs at Cosmic noon undergo an intense growth phase of both the central super-massive black hole and of the host-galaxy. These systems pinpoint the high-density sites where giant galaxies assemble, where we show that mergers play a major role in the build-up of the final host-galaxy mass. We suggest that the observed low molecular gas fraction and short depletion timescale are due to AGN feedback, whose presence is indicated by fast AGN-driven ionised outflows in all our targets.

Do methanotrophs drive phosphorus mineralization in soil ecosystem?

Experiments were carried out to elucidate linkage between methane consumption and mineralization of phosphorous (P) from different P sources. The treatments were (i)no CH4+ no P amendment (absolute control), (ii)with CH4+ no P amendment (control), (iii)with CH4+ inorganic P as Ca3(PO4)2, and (iv)with CH4+ organic P as sodium phytate. P sources were added at 25 µg P·(g soil)-1. Soils were incubated to undergo three repeated CH4 feeding cycles, referred to as feeding cycleI, feeding cycleII, and feeding cycleIII. CH4 consumption rate k (µg CH4 consumed·(g soil)-1·day-1) was 0.297± 0.028 in no P amendment control, 0.457± 0.016 in Ca3(PO4)2, and 0.627± 0.013 in sodium phytate. Rate k was stimulated by 2 to 6 times over CH4 feeding cycles and followed the trend of sodium phytate> Ca3(PO4)2> no P amendment control. CH4 consumption stimulated P solubilization from Ca3(PO4)2 by a factor of 2.86. Acid phosphatase (µg paranitrophenol released·(g soil)-1·h-1) was higher in sodium phytate than the no P amendment control. Abundance of 16SrRNA and pmoA genes increased with CH4 consumption rates. The results of the study suggested that CH4 consumption drives mineralization of unavailable inorganic and organic P sources in the soil ecosystem.

Reactor for Waste Gasification with Highly Superheated Steam

Using highly superheated steam (HSS) with a temperature of above 2000 K for oxygen-free gasification/detoxification of industrial, municipal, and toxic waste, the organic component of waste can be completely converted to syngas or power gas. It was proposed for the first time to produce such HSS by cyclic detonation of stoichiometric ternary mixtures fuel–oxygen–steam at a near-atmospheric initial pressure and to feed it into a cooled flow-type spherical reactor as supersonic countercurrent two-phase jets together with finely divided waste particles. Three-dimensional gas-dynamic calculations showed that the cyclic feed of supersonic jets into the reactor gives rise to intense vortex zones of high-temperature HSS. Waste particles repeatedly enter into these vortex zones and are gasified or heat-treated, and the shock waves accompanying the feed of the supersonic jets prevent particle agglomeration. In the quasi-stationary operation process, a small overpressure is maintained in the reactor (to prevent the suction of atmospheric air), and the median mean residence time of the particles is sufficient for their complete gasification.

Non-lethal effects of the predator Meganyctiphanes norvegica and influence of seasonal photoperiod and food availability on the diel feeding behaviour of the copepod Centropages typicus.

Predators can induce changes in the diel activity patterns of marine copepods. Besides vertical migration, diel feeding rhythms have been suggested as an antipredator phenotypic response. We conducted experiments to assess the non-lethal direct effects of the predator Meganyctiphanes norvegica (northern krill) on the diel feeding patterns of the calanoid copepod Centropages typicus. We also analysed the influence of seasonal photoperiod and prey availability on the intensity of copepod feeding rhythms. We did not detect any large effect of krill presence on the diel feeding behaviour of copepods, either in day-night differences or total daily ingestions. Seasonal photoperiod and prey availability, however, significantly affected the magnitude of copepod feeding cycles, with larger diel differences in shorter days and at lower prey concentrations. Therefore, the role of non-lethal direct effects of predators on the diel feeding activity of marine copepods remain debatable and might not be as relevant as in freshwater zooplankton.

Unified approach to developing analytical models of different grinding processes based on basic cutting process model

The appearance of modern CNC grinding machines allowed concentrating multipass and multistage processing of different workpiece surfaces by means of using different grinding types and different tool types. Meanwhile, the processing of different surfaces is carried out with different allowances and accuracy requirements and performed according to the specified stepwise cycles of the feeds control. As a result, there is a difficult task of quick and reliable calculation of the optimal feed cycles and other cutting modes for different types of processing of different surfaces with various grinding conditions. The solution to this problem is developing of mathematical models that link processing accuracy with cutting modes and other technological conditions of the processing. The development of such models should begin with the creation of a complex of the cutting forces` models for each grinding type. This article describes a method for deriving generalized analytical model of the cutting force for the different grinding types which is based on the functional interrelation between the intensity of the metal removal performed by the wheel and elementary volumes of metal deformable in the shear zone. The complex of the cutting forces models for different grinding types, obtained by means of using this technique, establishes functional interrelation of the cutting force with cutting modes, strength properties of the treated material, kinematics of the grinding process, geometry of the cutting zone, characteristics and geometric parameters of the grinding wheel, etc. It should also be noted that the developed models cover the majority of production conditions and they are wide-range in terms of the main technological parameters (dimensions of the treated surfaces, allowances, tolerance grades, etc.).

Elevated temperature pressure swing adsorption using LaNi4.3Al0.7 for efficient hydrogen separation

The application of LaNi5 based alloys as adsorbent for hydrogen separation and purification has been proposed for a long time. However, the actual utilization is limited by the poor CO tolerance of the alloys at atmospheric temperature. In this study, an elevated temperature vacuum pressure swing adsorption (ET-VPSA) method for H2 separation using hydrogen storage material LaNi4.3Al0.7 is proposed and demonstrated to be energy efficient. Elevating the working temperature results in improved CO tolerance of LaNi4.3Al0.7, making it possible for the alloy to be used in more situations. An ET-VPSA model was built to explore the correlations between product H2 purity, recovery rate, feed gas composition, cycle duration and counter-current blow down (CD) pressure. The results show that H2 recovery rate of ET-VPSA reaches 95% while it is usually 85% or lower for regular pressure swing adsorption (PSA). The energy efficiency of these two separation methods is evaluated by methanol reforming-proton exchange membrane fuel cell system models which contain PSA or ET-VPSA as H2 purification unit. A larger net power generation amount indicates less energy loss during H2 purification process. Although the vacuum pump will lead to extra energy consumption, benefiting from higher H2 recovery rate, the net efficiency of the system with ET-VPSA is 0.475, still higher than that with PSA (0.448).

Automatic pig selection system based on body size using a camera: rotating mechanics for pig selection

Since the delivery of different pig sizes at a same time leads to loss profits, the management of pigs to be grown up uniformly is an important task in pig farms. Therefore, automatic sorting system of pigs by size has been introduced. In our proposed system, camera is used to measure the size of pigs. Camera detects the image of a pig and pig’s size is estimated using computer vision technique. The estimated size is used to select the adequate foods for the pig. The novel mechanism that leads the pig to the adequate direction for the feeding is introduced. The proposed mechanism works robustly in the poor environment of a pig farm. It works satisfactorily without disturbing the feeding cycles of pigs in the farms. The system reduces the labor cost and enables the efficient feeding cycles on considering the size of a pig. The weight is also estimated from the size. Experimental result shows the performance of the weight estimation.

Laser machining of die steel (En-31): an experimental investigation to study the effect of process parameters

ABSTRACT Laser beam machining (LBM) is a non-contact type advance machining process and can be applied to almost all metallic and non-metallic range of materials. The effect of process parameters such as feed, laser power, gas pressure, frequency, and duty cycle has been investigated on EN-31 die steel of 6 mm and 10 mm thickness to determine the surface roughness, heat-affected zone (HAZ) and taper effect of the hole. Second-order mathematical models with a regression coefficient greater than 90 degree have been achieved for all the responses using Response Surface Methodology (RSM) and validated with the experimental results. Better cut quality has been obtained using an optimised model and also validated its results with a mathematical model. Feed and laser power were observed significant process parameters for governing the taper angle. The bottom edge has been observed with significant HAZ compared to the upper edge. Feed, Power, and gas pressure were the significant parameters to control the HAZ and surface roughness. Dross and striation patterns were observed at the hole cut section. Indentation of HAZ, surface damage and micro-cracks near the cut edges have been recognised using Scanning Electron Microscope (SEM).

An assessment of Horlock’s approximate analysis of feed and district heating cycles for steam and CHP plant

In 1987 Professor Horlock published an approximate analysis of feed heating and district heating steam plant based on then current steam plant. This note examines the validity of this approximate analysis for a range of different boiler and condenser conditions in the light of an increased interest in district heating. It is shown that the analysis of Horlock is best suited for boiler pressure around 40 to 50 bar and temperatures from 300 °C to 500 °C.

Effects of frequency and feeding time on growth, food utilization, somatic indexes and survival of juvenile white snook Centropomus viridis

The Pacific white snook, Centropomus viridis, is considered a species with high farming potential in Mexico due to its high economic value and overall demand in the national market. Growth in farmed fish is largely determined by the dietary regimen, which includes feeding frequency, rate, time, and cycle. The aim of the present study was to determine the feeding frequency and appropriate feeding time for farmed C. viridis juveniles in order to optimize growth and survival. Juveniles weighing 0.36 ± 0.01 g were used to evaluate 1 and up to 5 ad-libitum feeding frequencies per day, with 3 to 24-h intervals, for 6 weeks. Gained weight (GW), growth rate (GR), specific growth rate (SGR), food conversion ratio (FCR), feeding efficiency rate (FER), coefficient of variation (CV), hepatosomatic index (HI), peritoneal fat index (PFI), and survival (S) were determined for juveniles. Regardless of the feeding hours, no significant differences were found in the GR and SGR values between juveniles fed 3 times a day and those fed 5 times a day. FCR was significantly higher and FER significantly lower in treatments with juveniles fed only once a day compared with the rest of the treatments. No significant differences were found in CV, HI, and S between treatments. PFI was significantly different only between juveniles fed once and 5 times a day. Considering the results obtained in this study, we suggest feeding C. viridis juveniles 3 times a day at 6-h intervals between doses. These results will contribute to the development of biotechnology for farming this species.

Effects of Ramadan fasting on blood pressure in hypertensive patients

During Ramadan, repeated cycles of fasting and feeding might contribute to changes in blood pressure and heart rate among hypertensive patients. Studies on the effects of fasting on the blood pressure of hypertensive patients are scarce, and have provided inconclusive results. The aim of this study was to examine the effect of fasting on ambulatory blood pressure and heart rate in treated hypertensive subjects. The study prospectively recruited 40 hypertensive patients between April and June 2019, and followed up at the cardiology department of Habib Thameur Hospital of Tunis. A 24 hour pressure monitoring was carried out during three periods: prior to Ramadan, during Ramadan, and one month after. SPSS version 20 was used to perform the statistical analysis. The paired Student's t -test was used to compare data within the 3 periods. We studied 40 hypertensive subjects (65% women, 35% men), mean age was 57 ± 11years. Patients in the study group were using ACE inhibitors (15%), AT2 receptor blockers (17.5%), calcium channel blockers(17.5%), b-blockers(2.5%) and a combination treatment (47.5%). Average 24 h ambulatory blood pressure in the whole group was 129 ± 15/75 ± 8 mmHg before Ramadan, 127 ± 17/74 ± 8 mmHg during Ramadan and 126 ± 13/74 ± 7 in the following month ( P > 0.05). Daytime and night time mean values of systolic and diastolic blood pressure were not different between the three periods. This study showed a significant improvement in the heart rate during the second period in comparison with the first one ( P = 0.03). In this study, there were no significant changes in systolic and diastolic blood pressures during the 3 periods. There was a significant improvement in the heart rate during the ten last days of Ramadan, in comparison with the pre-Ramadan period. This suggest that fasting during the month of Ramadan, using the same medication might be non-threatening for patients with hypertension.

Dynamics of the behaviour of a vertical wetland (French system) operating in warm-climate conditions, evaluated by means of variables continuously measured in situ

The sewage treatment system in this study was operated with only the first stage of a French system of vertical wetlands, composed of two units in parallel and running with an extended feeding cycle (7 days). This research sought to evaluate and relate continuous variables measured in situ (dissolved oxygen (DO), pH and redox potential) throughout the feeding cycle, with measurements at distinct heights along the filter vertical profile. Additionally, the influence of the surface organic sludge deposit was investigated. A close link between the hydraulic behaviour and the effluent quality was verified, with both being related to the batch volume and the instantaneous hydraulic loading rate. The drop in DO as the feed days progressed could be related to the loss of hydraulic conductivity. A thicker sludge layer decreased the aeration capacity of the filter. The effluent was observed to be aerated when percolating through the medium. DO and pH data suggested that nitrification varied along the filter depth, the batch duration and the feed cycle. The monitored parameters may be indicative of the behaviour of other parameters.

Echinometra sea urchins on Caribbean coral reefs: Diel and lunar cycles of movement and feeding, densities, and morphology

Two species of Echinometra are found on tropical western Atlantic reefs. E. viridis and E. lucunter. Both are grazers and bioeroders, and on some disturbed reefs E. viridis has become the dominant herbivore, particularly since the disease-caused decline of the much larger echinoid Diadema antillarum. Thus, it is critical to understand factors affecting herbivory by Echinometra, including foraging behaviors and distances, diel and lunar cycles of foraging, and densities of Echinometra, particularly E. viridis, across habitats and locations.Twenty-four hour tracking studies undertaken in the San Blas Islands of Panama, conducted at different times in the lunar cycle, revealed that on new moons both species of Echinometra primarily moved and fed at night, but the pattern reversed on full moons. These data suggest that vulnerability to predators and/or aggression by damselfishes during the night on full moons may be a significant selective force affecting diel foraging behavior. Daily distances moved (minimum estimate) averaged 19 cm for E. viridis and 11 cm for E. lucunter. The average foraging range for E. viridis was estimated to be 0.3–5% the size of that of D. antillarum, while per capita daily algal consumption by E. viridis is 20% that of D. antillarum.These results suggest more intense, localized grazing by E. viridis compared to D. antillarum.A review of published densities of E. viridis show that 50% of studied sites (location/habitat combination) have densities less than 5 m−2, a level unlikely to produce a strong herbivory effect. Densities greater than 15 m−2 were found at 25% of sites, including the San Blas Islands, Panama patch reefs in this study, which averaged 26 m−2. Where high densities are combined with low predator numbers due to fishing, E. viridis can have strong direct effects on algal assemblages, with potential indirect effects on corals and other benthic invertebrates. However, available published data indicate E. viridis has strong regional variation in abundance, as yet unexplained, that limits its potential Caribbean-wide role as a reef herbivore.Morphological traits of E. viridis that are likely related to vulnerability to predation varied across habitats. A newly-described melanic color morph comprised 4–16% of the population, with significant variation in frequency across habitat types. Body sizes (test diameter) also varied among habitats, with larger individuals much more common in habitats with fewer shelter sites. Similarly, in habitats offering less protection from predators, spine lengths were longer relative to test diameter. Morphological traits that reduce predator detection or vulnerability to predation, as well as the refuges afforded by habitat, will ultimately affect both the number of E. viridis on a particular reef and their ability to forage in the presence of predators.

Inhibition of norfloxacin on anaerobic digestion: Focusing on the recoverability and shifted microbial communities

Antibacterial properties of norfloxacin (NOR) could cause adverse impact on engineered biological process. In this study, the objective was to investigate the inhibitory effects of NOR on anaerobic digestion focusing on the recoverability and microbial community changes. The effects of different concentrations of NOR on anaerobic digestion were studied with three continuous feed cycles. Results showed that NOR seriously inhibited the methane production with an 50% inhibitory concentration (IC50) of 0.41 mM. In addition, with extending of exposure time, inhibitory effect increasingly strengthened and the IC50 values decreased to 0.16 mM and 0.07 mM in the second and third feeding cycle, respectively. However, when the inhibitor in supernatant was removed, the performance recovered and the relative methane yield increased by 9 times from 25.38 mL/g VS to 257.05 mL/g VS. The transformation of NOR showed that the degradation of NOR in the anaerobic digestion was difficult and the recovery was due to the removal of NOR. The microbial analysis revealed that the inhibition of NOR on bacteria of Candidatus_Cloacimonas, Petrimonas, Ercella, Sphaerochaeta and hydrogenotrophic methanogens of Methanoculleus and Methanobacterium was recoverable when NOR was removed. However, it was irreversible for acetoclastic methanogen of Methanosaeta. These findings provided comprehensive understanding on the characteristics of NOR inhibition and also provided feasible strategy to recover the NOR inhibited anaerobic digestion.