Alterations in Digestive Enzymes of Three Freshwater Teleostean Fishes by Almix Herbicide: A Comparative Study

Three freshwater teleostean fishes viz., Anabas testudineus (Bloch), Heteropneustes fossilis (Bloch) and Oreochromis niloticus (Linnaeus) were exposed to almix (66.67 mg/l) herbicide for 30 days to investigate the activity of digestive enzymes (amylase, lipase and protease) in stomach, intestine and liver. Amylase activity showed significantly high (p < 0.05) in all the fishes compared to control value and highest activity was observed in liver of A. testudineus (721.99 %) and minimum in intestine of H. fossilis (195.37 %). Lipase activity was also significantly increased (p < 0.05) in all the tissues; but highest in intestine of O. niloticus (235.51 %) and minimum in intestine of A. testudineus (130.51 %). Protease activity also showed similar trends of enhancement; it was maximum in stomach of O. niloticus (362.69 %), whereas in liver of H. fossilis it was rather less (173.72 %). Increased activity of digestive enzymes resulting from tissue damage ultimately affected the fish health due to impairment of digestive physiology confirming the herbicidal contamination on fish species. The sensitivity to the almix herbicide was pronounced in the order of O. niloticus > A. testudineus > H. fossilis.     

Faster redox fluctuations can lead to higher iron reduction rates in humid forest soils

Iron (Fe) minerals play an important role in carbon (C) and nutrient dynamics in redox fluctuating soils. We explored how the frequency of redox oscillations influence Fe reduction rates and C content in Puerto Rican soils. We hypothesized that iron reduction rates would be faster during short oscillation periods than in longer oscillation periods. Surface soils from an upland valley in a humid tropical forest were exposed to systematic redox oscillations over 49 days. The oxidation events were triggered by the introduction of air (21% O₂), maintaining the time ratio under oxic or anoxic conditions at 1:6 (τ_ox/τ_anox). After pre-conditioning the soil to fluctuating redox conditions for 1 month, we imposed 280- and 70-h (or 11.67- and 2.5-day) redox oscillations, measuring Fe^II every few days. We found that by the end of the experiment, Fe reduction rates were higher in the short oscillation period (τ_ox = 10 h, τ_anox = 60 h) than in the long oscillation period (τ_ox = 40 h, τ_anox = 240 h). Carbon and nitrogen loss however was similar for both treatments. These results suggest the characteristics of redox fluctuations can alter rates of Fe reduction and potentially influence ecosystem processes that depend on iron behavior.     

Microbial Consortium-Induced Changes in Oxidative Stress Markers in Pea Plants Challenged with Sclerotinia sclerotiorum

The ability for rhizobacteria and fungus to act as bioprotectants via induced systemic resistance has been demonstrated, and considerable progress has been made in elucidating the mechanisms of plant–biocontrol agent–pathogen interactions. Pseudomonas aeruginosa PJHU15, Trichoderma harzianum TNHU27, and Bacillus subtilis BHHU100 from rhizospheric soils were used singly and in consortium and assessed on the basis of their ability to provide disease protection by relating changes in ascorbic acid and hydrogen peroxide (H₂O₂) production, lipid peroxidation, and antioxidant enzymes in pea under the challenge of Sclerotinia sclerotiorum. Increased production of H₂O₂ 24 h after pathogen challenge was observed and was 254.4 and 231.7–287.7 % higher in the triple consortium and singly treated plants, respectively, when compared to untreated challenged control plants. A similar increase in ascorbic acid content and ascorbate peroxidase activity was observed 24 and 48 h after pathogen challenge, respectively, whereas increased activities of catalase, guaiacol peroxidase, and glutathione peroxidase were observed 72 h after pathogen challenge. Similarly, lipid peroxidation reached a maximum at 72 h of pathogen challenge and was 61.2 and 11.2–32.1 % less in the triple consortium and singly treated plants, respectively, when compared to untreated challenged control plants. These findings suggest that the interaction of microorganisms in the rhizosphere enhanced protection from oxidative stress generated by pathogen attack through induction of antioxidant enzymes and improved reactive oxygen species management.     

The role of Thalassoma lunare as a predator of juvenile fish on a sub-tropical coral reef

The process of predation causes significant mortality in coral reef fishes immediately following settlement. However, much of what we know of predator identity is based on a small number of detailed studies. This study aims to identify the key predator of early juvenile coral reef fishes on Ningaloo Reef, North-Western Australia. Video cameras were used to observe patch reefs stocked with newly settled reef fish in the back-reef area between 12:00 and 20:30 h. The cameras were fitted with >610 nm light sources to allow observation in low light conditions. All strikes (attempted and successful) on newly settled fish were recorded, along with the time spent in the vicinity of experimental patch reefs with or without juvenile fish. A total of 69 strikes were observed over the 199 h of recorded video footage, with the majority of strikes occurring mid-afternoon between 13:00 and 15:30 h. Only one strike was observed during the twilight period, an hour either side of sunset (~18:45 h), and no strikes were observed after this period. The moonwrasse, Thalassoma lunare, was responsible for the majority of strikes (75.4 %), with the sandperch (Parapercis clatharatha—10.1 %), spanish flag (Lutjanus carponotatus—5.8 %) and ring wrasse (Hologymnosus annulatus—2.9 %) the next highest contributors. T. lunare also spent significantly more time in the vicinity of reefs stocked with newly settled fish, than those without, during daylight hours. The results of the study are in contrast to the common perception that predation on newly settled fish is focused largely around crepuscular periods and suggests that diurnally active species, in particular T. lunare, are important predators of juvenile fish on the Ningaloo back-reef. The study also implies that generalist species can fulfil key functional roles and that the nature of these roles is not always apparent.     

Respiration in air and water of three mangrove snails

The oxygen consumption of three species of Malaysian mangrove gastropods was measured in air and sea water at the temperatures commonly recorded in the mangrove. The experiments in air were carried out after the animals had regained fluid lost from the mantle due to handling. Fluid loss can have considerable effects on rate of oxygen consumption. Nerita arliculata (Gould) was found throughout the mangrove and experiences from 50 to 92% aerial exposure. It has a gill and a ratio of aerial to aquatic respiration rates of 2.7 at 28°C. 50% of the animals can survive underwater for 72 h at 28°C. The other two species, Cerithidea obtusa (Lamarck) and Cassidula aurisfelis (Brugière) experience over 95% aerial exposure, have their mantle cavities modified as lungs and have air : water respiration rate ratios of 5.5 and 6.0, respectively. 50% can survive from 48 to 36 h underwater at 28°C. Acclimated animals have Q₁₀'s of about 1.6 in air and 1.4 in water. The respiratory physiology of the snails is compared with that of rocky shore species.     

Detection of Multiple Cytochrome P450 in Hepatic Tissue of Heteropneustes fossilis (Bloch) Exposed to Cypermethrin

Cypermethrin (alpha-cyano-3-phenoxybenzyl ester of 2,2-dimethyl-3-(2,2-dichlorovinyl) cyclopropane carboxylic acid) is a synthetic pyrethroid. It is one of the most widely used pesticide in commercial agricultural applications because of its high effectiveness against target species. Beside its target toxicity it is also highly toxic to other non-target species like fish, bees and aquatic insects. The aim of this study was to detect the presence of cytochrome P450 (CYP 450) in the hepatic microsomes of Heteropneustes fossilis upon exposure to cypermethrin. The 96 h LC₅₀ value for each exposure route was calculated and two groups were treated, with one group receiving a single IP (intraperitoneal) injection for 96 h (0.030 mg/kg body weight) and the other group with 1/3 sub-lethal concentration (1.2 μg/l) of the LC₅₀ value in water for 15 days. Activities of the enzymes ethoxyresorufin-o-deethylase (EROD), N,N-dimethylaniline demethylase, aniline hydroxylase and erythromycin demethylase mediated respectively by the isozymes CYP1A, CYP2B, CYP2E1 and CYP3A4 were studied. The liver somatic index (LSI) was also calculated to determine the physiological status of the fish. Activities of CYP1A, CYP2B and CYP2E1 enzymes increased significantly while that of CYP3A4 enzyme inhibited as compared to control. Total CYP 450 content was also significantly induced in both the treated groups. The increase in activities of CYP P450 isozymes could be used as a biomarker to indicate the pollution of an aquatic environment by the pesticide.     

An estimation of Canadian population exposure to cosmic rays from air travel

Based on air travel statistics in 1984, it was estimated that less than 4 % of the population dose from cosmic ray exposure would result from air travel. In the present study, cosmic ray doses were calculated for more than 3,000 flights departing from more than 200 Canadian airports using actual flight profiles. Based on currently available air travel statistics, the annual per capita effective dose from air transportation is estimated to be 32 μSv for Canadians, about 10 % of the average cosmic ray dose received at ground level (310 μSv per year).     

Physical activity and alpha-lipoic acid modulate inflammatory response through changes in thiol redox status

α-Lipoic acid (αLA), as an inductor of hydrogen peroxide (H₂O₂) and nitrogen oxide (NO) generation and modulator of thiol redox status, plays an important role in cell signalling pathways. The study was designed to observe the effect of αLA on inflammatory response through changes in H₂O₂ and NO levels as well as thiol redox status. Sixteen physically active males were randomly assigned to one of two groups: placebo or αLA (1,200 mg?d^?1 for 10 days prior to exercise). The exercise trial involved a 90-min run at 65 % VO₂max (0 % gradient) followed by 15-min eccentric phase at 65 % VO₂max (?10 % gradient). Blood samples were collected before the exercise trial and then again 20 min, 24, and 48 h after. αLA significantly elevated H₂O₂ but reduced NO generation before or after exercise. Thiol redox status (GSH_total-2GSSG/GSSG) increased by >50 % after αLA and exercise (ANOVA, P?<?0.05) and correlated with changes in cytokines interleukin-6 (IL-6) (r?=??0.478, P?<?0.05) and IL-10 (r?=??0.455, P?<?0.05). This was caused by strong effect of αLA on GSSG concentration. αLA elevated IL-6 and IL-10 levels at 20 min after exercise and decreased in interleukin-1β and tumor necrosis factor α before and after exercise. This enhanced the regeneration of injured muscles. Creatine kinase activity tended to lower values after αLA intake. The study suggests that the combination of intense exercise with α-lipoic acid intake might be useful to improve the skeletal muscle regeneration through changes in inflammatory response which are associated with H₂O₂ and NO generation as well as thiol redox status.     

Effects of negative air ions on oxygen uptake kinetics,recovery and performance in exercise: a randomized,double-blinded study

Limited research has suggested that acute exposure to negatively charged ions may enhance cardio-respiratory function, aerobic metabolism and recovery following exercise. To test the physiological effects of negatively charged air ions, 14 trained males (age: 32?±?7 years; \( \overset{\cdotp }{V}{\mathrm{O}}_{2 \max } \) : 57?±?7 mL min^?1 kg^?1) were exposed for 20 min to either a high-concentration of air ions (ION: 220?±?30?×?10³ ions cm^?3) or normal room conditions (PLA: 0.1?±?0.06?×?10³ ions cm^?3) in an ionization chamber in a double-blinded, randomized order, prior to performing: (1) a bout of severe-intensity cycling exercise for determining the time constant of the phase II \( \overset{\cdotp }{V}{\mathrm{O}}_2 \) response (τ) and the magnitude of the \( \overset{\cdotp }{V}{\mathrm{O}}_2 \) slow component (SC); and (2) a 30-s Wingate test that was preceded by three 30-s Wingate tests to measure plasma [adrenaline] (ADR), [nor-adrenaline] (N-ADR) and blood [lactate] (B_Lac) over 20 min during recovery in the ionization chamber. There was no difference between ION and PLA for the phase II \( \overset{\cdotp }{V}{\mathrm{O}}_2 \) τ (32?±?14 s vs. 32?±?14 s; P?=?0.7) or \( \overset{\cdotp }{V}{\mathrm{O}}_2 \) SC (404?±?214 mL vs 482?±?217 mL; P?=?0.17). No differences between ION and PLA were observed at any time-point for ADR, N-ADR and B_Lac as well as on peak and mean power output during the Wingate tests (all P?>?0.05). A high-concentration of negatively charged air ions had no effect on aerobic metabolism during severe-intensity exercise or on performance or the recovery of the adrenergic and metabolic responses after repeated-sprint exercise in trained athletes.     

Evaluation of Acute Toxicity Levels and Ethological Responses Under Tetrachlorocatechol Exposure in Common Carp,Cyprinus carpio (Linnaeus)

Tetrachlorocatechol (TCC) is one of the most toxic chlorinated catechol produced by the chlorobleaching of pulp and frequently found in the kraft pulp mill effluents. Toxicity of TCC to common carp, Cyprinus carpio and their ethological changes were evaluated in the present study. The 24, 48, 72 and 96 h LC₅₀ values of TCC to C. carpio were 4.73, 3.95, 3.20 and 2.43 mg/l respectively. The mortality rate of C. carpio showed significant relationship (p < 0.05) at different exposure times (24, 48, 72 and 96 h) in different treatments of TCC (2, 3, 4, 5 and 7 mg/l). On the other hand, a significant correlation (p < 0.01) was observed between the mortality rate of fish with all the concentrations of TCC. Mean opercular movement in the fish increased significantly with the increasing dose and time of exposure to TCC indicating acute respiratory distress. The jerky movement, somersaulting, circular movement and mucus secretion of fish increased gradually with the increasing concentrations and exposure times of TCC for adapting a compensatory mechanism to derive energy in order to avoid stress due to toxicity.     

Oxidative stress in digestive gland and gill of the brown mussel (Perna perna) exposed to air and re-submersed

Mussels Perna perna were exposed to air for 24 h showing a clear increase in the levels of lipid peroxidation and oxidative DNA damage, measured as 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo). The levels of lipid peroxidation increased both in the digestive gland and gills, while oxidative DNA damage increased only in the gills. After the 24 h of air exposure, mussels were re-submersed for a period of 3 h, leading values to return to a pre-aerial exposure levels. Control animals were kept immersed during the whole period. Several antioxidant and complementary enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH), glutathione S-transferase (GST) and the levels of total glutathione (Total GSH) were assayed in a second set of experiments where one group of mussels were exposed to air for 18 h and other to 1 h re-submersion after 18 h aerial exposure. Only a 52% increase in the glutathione S-transferase activity was observed in the digestive gland, which remained elevated to about 40% after 1 h re-submersion, showing that defense systems can be modulated even during oxygen deprivation in P. perna. The DNA and lipid oxidative damage observed after aerial exposure indicates that mussels face an oxidative challenge, and are able to counteract such an “insult” as values of lipid peroxidation and DNA damage returned to control values after 3 h re-submersion.     

Effects of in situ experimental air warming on the soil respiration in a coastal salt marsh reclaimed for agriculture

Background and Aims

The reclamation of natural salt marshes for agricultural use is expected to profoundly influence the effects of predicted global warming on the carbon balance of coastal areas globally. This study was undertaken to understand the potential for soil respiration changes in a disturbed coastal ecosystem under future atmospheric warming

Methods

An in situ simulated warming experiment was conducted in a reclaimed salt marsh on Chongming Island in the Yangtze Estuary, China. Open-top chambers (OTCs) were applied to simulate air-warming conditions.

Results

Based on the 2-year study, we found the following: (1) Averaged across the entire study period, the OTCs significantly increased the mean air temperature by 1.53?±?0.17 °C. (2) The air warming resulted in no significant stimulation of the mean soil respiration averaged across the entire study period. Warming had no significant effect on soil respiration in the growing season, but it markedly reduced soil respiration by 16 % in the non-growing season. (3) Air warming had no significant effect on the mean soil temperature or volumetric moisture at a 5 cm depth, but it increased the mean soil porewater salinity by 119 % averaged across the entire study period. (4) Air warming had no significant effect on total organic carbon, total nitrogen or the molar C/molar N ratio of the soil in the uppermost 10 cm layer during the 2 years of soil respiration measurement. The warming treatment also had no significant effect on aboveground biomass or fine root (<2 mm) density during the second year of soil respiration measurement. (5) Soil temperature accounted for 81.0 % and 79.0 % of the temporal variations of soil respiration in the control (CON) and elevated temperature (ET) plots, respectively. No significant correlation between soil volumetric moisture and soil respiration was observed in either CON or ET. Soil porewater salinity was positively correlated with soil respiration in CON, but such a positive correlation was not found in ET. No change of the temperature sensitivity of soil respiration (Q ₁₀ value) was observed.

Conclusions

Based on above results, we speculate that soil porewater salinity was the key factor controlling the effects of air warming on soil respiration in the reclaimed salt marsh. Our results suggest that an air warming of approximately 1.5 °C over the next few decades may not lead to a higher soil respiration in reclaimed salt marshes.     

Voltage dependence of the Ca<Superscript>2+</Superscript> transient in endocardial and epicardial myocytes from the left ventricle of Goto–Kakizaki type 2 diabetic rats

There is much evidence that a combination of ibuprofen (IBU) and Aspirin (ASA) can antagonize the irreversible inhibition of platelet function. This study was designed to investigate the degree of gastric damage, bleeding time (BT) and fluctuations in the serum levels of prostaglandin E₂ (PGE₂) and thromboxane A₂ (TXA₂) after oral administration of ASA (200 mg/kg) and IBU (50 mg/kg) either alone or in combination in rats in vivo. The stomach was assessed for any damage either after 6 h, 18 h or 6 days and carboxymethylcellulose (1% CMC) served as a vehicle and control. ELISA was used to measure TXA₂ and PGE₂ in serum. Bleeding time was assessed using tail blood. The results show that ASA and IBU either alone or in combination can cause gastric ulceration in 25–100% of the rats at 6 and 18 h. In contrast, gastric ulceration was seen in 50% of rats with a combination of ASA given before IBU only after 6 days of oral administration. BT was unaffected either by ASA or IBU when administered alone except after 18 h for IBU. In contrast, BT was significantly reduced when IBU was administered before ASA after 18 h and 6 days (P < 0.001). Serum PGE₂ levels decreased significantly after ASA administered either alone or in combination with IBU for 6 h, 18 h and 6 days (P < 0.05). Serum TXA₂ levels were significantly reduced after 6 h, 18 h and 6 days following ASA and IBU administration except for IBU alone which caused a significant increase in serum TXA₂ 6 days after its administration (P < 0.01). It can be concluded that ASA and IBU administered either alone or in combination can cause gastric ulcers in the rat stomach after 6 h and 18 h, but less severe after 6 days. IBU either alone or in combination with ASA reduced BT only after 18 h and 6 days of administration. Together, the results show that gastric ulceration correlated well with the inhibition of serum PGE₂ and TXA₂ levels.     

Impacts of varying durations of passive oxygen exposure on freshwater denitrifier community structure and function

Fertilizer use has dramatically increased the availability of nitrate (NO₃ ^?) in aquatic systems. Microbe-mediated denitrification is one of the predominant means of NO₃ ^? removal from freshwaters, yet oxygenation (O₂)-induced disruptions—e.g., extreme precipitation events—can occur, resulting in a disproportional increase in nitrous oxide (N₂O) production and efflux as facultative anaerobic bacterial populations use of O₂ as a terminal electron acceptor increases. We examined the effects of 12- and 24-h passive O₂ exposure on previously anaerobic bacterial communities focusing on denitrification enzyme activity (DEA), N₂O production, and bacterial community 16S rRNA and nitrous oxide reductase gene (nosZ) profiles after 12, 24, and 48 h of anaerobic recovery. Treatments experiencing 24-h O₂ exposure had significantly higher DEA 12 h into anaerobic recovery than treatments undergoing 12-h O₂ exposure. Initial N₂O emissions were significantly lower in the 24-h O₂ exposure treatments although by 24 h a dramatic spike (tenfold relative to the 12-h O₂ exposure treatments) in N₂O concentrations was observed. However, within 6 h (30-h anaerobic recovery) these differences were gone. Community nosZ profiles experiencing 24-h O₂ exposure exhibited reduced diversity after 24-h recovery, which corresponded with an increase in N₂O emissions. However, after 48 h of anaerobic recovery, nosZ diversity had recovered. These observations highlight the effects of short-term aerobic disruption on denitrification, as well as the effects on the denitrifier community profile. Together, these data suggest that recovery to ambient N cycling is exacerbated by disturbance length due to increased lag time and subsequent loss of denitrifier community diversity.     

Elevated carbon dioxide has the potential to impact alarm cue responses in some freshwater fishes

Freshwater fish behaviors have the potential to be impacted by acidification due to increases in dissolved carbon dioxide (CO₂). Recent work in the marine environment suggests that increased CO₂ levels due to climate change can negatively affect fishes homing to natal environments, while also hindering their ability to detect predators and perform aerobically. The potential for elevated CO₂ to have similar negative impacts on freshwater communities remains understudied. The objective of our study was to quantify the effects of elevated CO₂ on the behaviors of fathead minnows (Pimephales promelas) and silver carp (Hypophthalmichthys molitrix) following exposure to conspecific skin extracts (alarm cues). In fathead minnows, their response to conspecific skin extracts was significantly impaired following exposure to elevated CO₂ levels for at least 96 h, while silver carp behaviors were unaltered. However, fathead minnow behaviors did return to pre-CO₂ exposure in high-CO₂-exposed fish following 14 days of holding at ambient CO₂ levels. Overall, this study suggests there may be potential impacts to freshwater fishes alarm cue behaviors following CO₂ exposure, but these responses may be species-specific and will likely be abated should the CO₂ stressor be removed.     

Exposure to moderate air pollution during late pregnancy and cord blood cytokine secretion in healthy neonates

Background/Objectives

Ambient air pollution can alter cytokine concentrations as shown in vitro and following short-term exposure to high air pollution levels in vivo. Exposure to pollution during late pregnancy has been shown to affect fetal lymphocytic immunophenotypes. However, effects of prenatal exposure to moderate levels of air pollutants on cytokine regulation in cord blood of healthy infants are unknown.

Methods

In a birth cohort of 265 healthy term-born neonates, we assessed maternal exposure to particles with an aerodynamic diameter of 10 µm or less (PM₁₀), as well as to indoor air pollution during the last trimester, specifically the last 21, 14, 7, 3 and 1 days of pregnancy. As a proxy for traffic-related air pollution, we determined the distance of mothers'' homes to major roads. We measured cytokine and chemokine levels (MCP-1, IL-6, IL-10, IL-1ß, TNF-α and GM-CSF) in cord blood serum using LUMINEX technology. Their association with pollution levels was assessed using regression analysis, adjusted for possible confounders.

Results

Mean (95%-CI) PM₁₀ exposure for the last 7 days of pregnancy was 18.3 (10.3–38.4 µg/m³). PM₁₀ exposure during the last 3 days of pregnancy was significantly associated with reduced IL-10 and during the last 3 months of pregnancy with increased IL-1ß levels in cord blood after adjustment for relevant confounders. Maternal smoking was associated with reduced IL-6 levels. For the other cytokines no association was found.

Conclusions

Our results suggest that even naturally occurring prenatal exposure to moderate amounts of indoor and outdoor air pollution may lead to changes in cord blood cytokine levels in a population based cohort.