Haematological indices are modulated in juvenile carp, Cyprinus carpio L., exposed to microcystins produced by cyanobacterial water bloom

This study evaluated the influence of toxic cyanobacterial water blooms on the blood indices of the common carp, Cyprinus carpio L. Experimental fish were exposed to a natural population of cyanobacterial water blooms (mainly Microcystis aeruginosa and M. ichthyoblabe), which contained microcystins [total concentration 133–284 μg g^?1 (DW), concentration in water 2.8–7.4 μg L^?1]. Haematological indices showed marked changes in fish exposed to the cyanobacterial population in comparison with the control group. Statistical evaluation of the influence of cyanobacterial water blooms on biochemical indices of the juvenile carp showed a distinct decrease in albumin, alanine aminotransferase, total bilirubin, calcium, cholesterol, glucose, phosphorus and iron when compared to controls. Values of red blood counts [haemoglobin, haematocrit (PCV), mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration] and lactate were significantly increased compared to controls. After exposure to cyanobacterial water bloom, the carp were kept in clean water to monitor the persistence of biochemical indices. The influence of cyanobacterial populations on calcium, cholesterol, glucose, lactate, phosphorus and PCV persisted up to 28 days after conclusion of the experiment. Duration of exposure, toxicity and density of cyanobacterial water blooms had an important impact on individual haematological indices.     

Comparative performance of Gamma Amino Butyric Acid (GABA) and 5-Hydroxytryptamine (5-HT) in the diet of larvae and post larvae of giant freshwater prawn, Macrobrachium rosenbergii: Effect of dose and route of administration on growth and survival

Three experiments were conducted to evaluate the effect of different dose and route of administration of 5-Hydroxytryptamine (5-HT) and Gamma Amino Butyric Acid (GABA) on growth, survival and pigmentation of giant freshwater prawn, Macrobrachium rosenbergii, larvae (experiment 1) and post larvae (experiment 2 and 3). In experiment 1 larva were stocked at 100 /L in seven different treatments with each of three replicates. The treatments were T1 (control), T2 (100 μg/ml of 5-HT bath exposure for 2 days), T3 (1 μM of GABA bath exposure for 2 days), T4 (0.5% 5-HT in feed), T5 (0.25% 5-HT in feed), T6 (0.5% GABA in feed) and T7 (0.25% GABA in feed). Highest growth, transformation rate, pigmentation and survival of larvae were recorded in T2 group in experiment 1. In experiment 2, post larvae were stocked at 70 per tank with 200 L of water for 45 days. This experiment consisted of 5 treatment groups with each of 3 replication viz. T1 (control), T2 (0.5% 5-HT in feed), T3 (0.25% 5-HT in feed), T4 (0.5% GABA in feed) and T5 (0.25% GABA in feed). At the end of this experiment growth was found to be higher in the control than the other treatment group showing inhibitory effect of 5-HT and GABA on growth of post larvae. To confirm the result, a third experiment was conducted for 30 days. Thirty numbers of post larvae having similar size were segregated from the previous experimental tanks (experiment 2) and stocked in the tanks of 100 L of water for experiment 3. All treatments were fed with control diet. There was similar growth pattern in all the treatments, which were higher (P < 0.05) than control, confirms the inhibitory effect of neurotransmitter in the diet of PL. Therefore, the overall results of the present study suggest that the bath treatment of neurotransmitter is superior to the dietary addition with regard to the growth, survival and pigmentation of M. rosenbergii larvae. 5-HT is more effective than the GABA for larvae of M. rosenbergii.     

Effect of methyl parathion and chlorpyrifos on certain biomarkers in various tissues of guppy fish, Poecilia reticulata

Tests of acute toxicity were performed on the most common species of aquarium fish, Poecilia reticulata. Guppies (P. reticulata) were exposed to progressive concentrations of methyl parathion (MP) and chlorpyrifos (CPF); a semi-static method according to guidelines of OECD was used. Tests of acute toxicity were conducted using 10 fish for each separate concentration and for the control group. The results were subjected to probit analysis to determine the 96 h LC₅₀ values. The 96 h LC₅₀ values of MP and CPF to P. reticulata were 8.48 ppm/L (5.98–10.89) and 0.176 ppm/L (0.313–0.224) respectively. In addition, behavioral changes at each concentration were observed for the individual fish. Fish were exposed for 96 h to different sublethal concentrations of MP and CPF (¼ LC₅₀, 1/8 LC₅₀ and 1/10 LC₅₀) and their oxidative stress-induction potential was estimated in brain, liver and gills of fish. MDA content is induced in all tissues but maximum rise was observed in gills (161% and 153% for MP and CPF respectively). With regard to antioxidant defense system (ADS), GSH level decreased in the brain, liver and gills of tissues of MP treated fishes (22%, 6% and 13% respectively) and showed increase in brain and gills CPF treated (23% and 21% respectively). CAT, GST, GR and SOD levels fluctuated in all treatment groups relative to the control. Brain AChE showed dose-dependent inhibition in fish exposed to the higher concentrations reached 45% and 66% for MP and CPF respectively. Collective findings demonstrated that pesticide exposure of fish induced an increase in MDA and fluctuated ADS along with inhibited AChE. These findings may be used as valuable biomarkers for evaluation of water pollution.     

Micronutrients (Fe,Mn, Zn and Cu) balance under long-term application of fertilizer and manure in a tropical rice-rice system

Purpose

The balance of micronutrients in soils is important in nutrient use efficiency, environmental protection and the sustainability of agro-ecological systems. The deficiency or excess of micronutrients in the plough layer may decrease crop yield and/or quality. Therefore, it is essential to maintain appropriate levels of micronutrients in soil, not only for satisfying plant needs in order to sustain agricultural production but also for preventing any potential build-up of certain nutrients.

Materials and methods

A long-term fertilizer experiment started in 1969 at Central Rice Research Institute, Cuttack, Odisha, India. Using this experiment, a study was conducted to analyze the balance of micronutrients and their interrelationship. The experiment was composed of ten nutrient management treatments viz. control; nitrogen (N); N + phosphorus (NP); N + potassium (NK); nitrogen, phosphorus and potassium (NPK); farmyard manure (FYM); N + FYM; NP + FYM; NK + FYM; and NPK + FYM with three replications. Micronutrients in soil (total and available), added fertilizers and organic manures and in rice plant were analyzed. Besides, atmospheric deposition of the micronutrients to the experimental site was also calculated. A micronutrient balance sheet was prepared by the difference between output and input of total micronutrients.

Results and discussion

Application of FYM alone or in combination with chemical fertilizer increased the diethylenetriamine pentaacetate (DTPA)-extractable Fe, Mn and Zn over the control treatment. The treatment with NPK + FYM had the highest soil DTPA-extractable Fe, Mn, Zn and Cu after 41 years of cropping and fertilization. Application of chemical fertilizers without P decreased the DTPA-extractable Zn over the control while the inclusion of P in the fertilizer treatments maintained it on a par with the control. The application of P fertilizer and FYM either alone or in combination significantly increased the contents of total Fe, Mn, Zn and Cu in soil mainly due to their micronutrient content and atmospheric depositions. A negative balance of Zn was observed in the N, NP, NK and NPK treatments, while a positive balance observed in the remaining treatments. The balance of Mn was negative in all the treatments, due to higher uptake by the rice crop than its addition.

Conclusions

Long-term application of chemical fertilizers together with FYM maintained the availability of micronutrients in soil and, thus, their uptake by rice crop.

     

Yeast extract, brewer’s yeast and spirulina in diets for Labeo rohita fingerlings affect haemato-immunological responses and survival following Aeromonas hydrophila challenge

A feeding trial was conducted for 60 days to study the immunomodulatory role of three different immunostimulants yeast extract (YE), brewer’s yeast (BY) and spirulina (SP) in Labeo rohita fingerlings. Four hundred and fifty fingerlings (avg. wt 3.35 ± 0.15 g) were randomly distributed in ten treatments and fed with either of ten iso-nitrogenous and iso-caloric semi-purified diets, prepared with three incremental levels (1%, 2% and 4%) of different immunostimulants except the control. Growth parameters did not vary significantly (p > 0.05) among the experimental groups. Haematology and serum parameters was performed before Aeromonas hydrophila challenge whereas respiratory burst activity was analysed following challenge. The respiratory burst activity, total leucocyte count, serum total protein and globulin was significantly higher (p < 0.05) in YE 1% supplemented group. The survival (%) after challenging with A. hydrophila was also highest in the YE fed groups. The results indicate that among the different sources and levels of immunostimulants, YE at lower inclusion level is more effective in promoting the immune status of L. rohita fingerlings.     

Canine periodontal disease control using a clindamycin hydrochloride gel

Stabilizing or reducing periodontal pocket depth can have a positive influence on the retention of teeth in dogs. A topical 2% clindamycin hydrochloride gel (CHgel) was evaluated for the treatment of periodontal disease in dogs. The CHgel formulation provides for the sustained erosion of the matrix, but also flows into the periodontal pocket as a viscous liquid, and then rapidly forms a gel that has mucoadhesive properties and also may function as a physical barrier to the introduction of bacteria. A professional teeth cleaning procedure including scaling and root planing was done in dogs with one group receiving CHgel following treatment. Periodontal health was determined before and after the procedure including measurement of periodontal pocket depth, gingival index, gingival bleeding sites, and number of suppurating sites. There was a statistically significant decrease in periodontal pocket depth (19%), gingival index (16%), and the number of bleeding sites (64%) at 90-days in dogs receiving CHgel. Additionally, the number of suppurating sites was lower (93%) at 90-days for the group receiving CHgel. The addition of CHgel effectively controlled the bacterial burden (e.g, Fusobacterium nucleatum) at both day 14 and 90. Gingival cells in culture were shown to rapidly incorporate clindamycin and attain saturation in approximately 20-minutes. In summary, a professional teeth cleaning procedure including root planning and the addition of CHgel improves the gingival index and reduces periodontal pocket depth.     

Microbial Biomass and Activity in a Laterite Soil Amended with Municipal Solid Waste Compost

The dynamics of soil quality indicators, such as microbial biomass-C, soil respiration, and urease and acid phosphatase activities, in a laterite soil (Typic Haplustalf ) amended with different doses of Calcutta municipal solid waste compost (MSWC) were studied over 120 days of incubation at 30 °C under 60 % soil water holding capacity. The parameters were found to increase with the increase in doses of MSWC. Soil microbial biomass-C (MBC) and soil respiration activity reached peak values at 30 days of incubation and then gradually decreased up to 120 days of incubation. Urease and acid phosphatase activities showed peak values at 60 and 90 days of incubation, respectively. The increase in soil enzyme activities with the fall in MBC suggested that the release of enzymes was associated with lysis of microbial cells at the end of their life cycle. There was no indication of any detrimental effect on soil quality indicators of application of MSWC to soil.     

Is insecticide-induced release of insect neurohormones a secondary effect of hyperactivity of the central nervous system?

Organochlorine and organophosphorus insecticides, in the concentration range of 1–10 μM, induce the release of hyperlipemic (adipokinetic) hormone from the isolated corpora cardiaca of the locust Locusta migratoria. Treatment of locusts with these insecticides in vivo also provokes the release of hyperlipemic hormone. The insecticide-induced release of hormone in vivo was found to precede the onset of poisoning symptoms. The insecticides tested in this study modulate the electrical activity of the isolated corpora cardiaca at doses lower than those required to have similar effects on the central nervous system. The results indicate that the insecticide-induced release of hormone may be mediated by the action of insecticides directly on neurosecretory cells.     

Studies on the role of microorganisms in the metabolism of dieldrin in the epicuticular wax layer of blowflies Calliphora erythrocephala

Microorganisms which inhabit the surface of blowflies, Calliphora erythorcephala, were identified as Bacillus spp., Micrococcus spp., Proteus spp., Streptococcus spp., and yeasts. These microorganisms were able to metabolize [¹⁴C]dieldrin incorporated into their culture media. Micrococcus spp. converted up to 29% of the applied dose of dieldrin to its more polar metabolites while the lowest ability to breakdown dieldrin was associated with Streptococcus spp. which metabolized nearly 0.8% of the applied dose. The addition of sesamex into microbial cultures partly inhibited the breakdown of dieldrin. Cuticular microflora of blowflies were controlled by the topical application of a mixture of gentamicin and amphotericin B. Pretreatment of blowflies with these antibiotics blocked dieldrin metabolism, to a certain degree, in the epicuticular wax layer. The formation of some of the metabolites, which were uniquely confined to the external lipid layer of blowflies, was found to be due to the activity of certain microorganisms. Therefore, microorganisms living on the surface of blowflies were found to play a role in the metabolism of topically applied [¹⁴C]dieldrin. There was a loss in the recovery of the dose of dieldrin applied to blowflies with the lapse of time. This was principally due to its volatilization from treated insects. The volatilization of [¹⁴C]dieldrin from different surfaces was also studied. The loss of the applied dose of dieldrin from various surfaces was in the order of glass > aluminum > fiberglass > DEAE-cellulose paper > silica gel G.     

Effect of mixed cation solutions on hydraulic soil properties

Hydraulic conductivity (K) and soil water diffusivity (D) characterizing water flow under saturated and unsaturated conditions, respectively, were determined for a sandy loam and a clay loam soil, using water with different combinations of total electrolyte concentrations, C (i.e., 20, 40, 80, 125 and 250 meq 1^?1) and sodium adsorption ratios, SAR (i.e., 0, 20, 30, 40, 80 and ∞ mmole $\text{l}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$). Both K and D were found to increase with C and decrease with SAR. In low sodium adsorption ratio ranges (i.e., up to 20) the requirement of electrolyte concentration to maintain relative hydraulic conductivity = 0.5 was relatively more for sandy loam than for clay loam soil. However, the trend for electrolyte concentration requirements for the two soils was reversed at high sodium adsorption ratios (i.e. > 20). A spline function was used to draw the best fitting line through the data points of horizontal absorption experiments.