Supplementation of microbial levan in the diet of Cyprinus carpio fry (Linnaeus, 1758) exposed to sublethal toxicity of fipronil: effect on growth and metabolic responses

A 60-day feeding trial was conducted to study the effect of dietary microbial levan on growth performance and metabolic responses of Cyprinus carpio fry exposed to sublethal dose (1/10th LC₅₀) of fipronil [(±)-5-amino-1-(2,6-dichloro-α,α,α-trifluoro-p-tolyl)-4-trifluoromethylsulfinylpyrazole-3-carbonitrile]. Two hundred and twenty five fry were randomly distributed in five treatments in triplicates. Four purified diets were prepared with graded levels of microbial levan. Five different treatment groups were levan control L₀P₀ (basal feed + 0 % levan without exposure to pesticide); pesticide control L₀P₁ (basal feed + 0 % levan with exposure to pesticide); L_0.25P₁ (basal feed + 0.25 % levan with exposure to pesticide); L_0.50P₁ (basal feed + 0.50 % levan with exposure to pesticide); and L_0.75P₁ (basal feed + 0.75 % levan with exposure to pesticide). Weight gain% and specific growth rate were significantly higher (p < 0.05) in levan fed groups compared to their non-levan fed counterpart. Highest (p < 0.05) content of ascorbic acid in muscle, liver and brain tissues was observed with higher level of dietary levan. Glucose-6-phosphate dehydrogenase activity decreased with the increasing level of dietary levan in the liver and muscle. Aspartate aminotransferase activity exhibited a second order polynomial relationship with the dietary levan, both in liver (Y = ?1.001x ² + 5.366x + 5.812, r ² = 0.887) and muscle (Y = ?0.566x ² + 2.833x + 6.506, r ² = 0.858) while alanine aminotransferase activity showed third order polynomial relationship both in liver (Y = 1.195x ³ ? 12.30x ² + 35.23x + 9.874, r ² = 0.879) and muscle (Y = 0.527x ³ ? 8.429x ² + 31.80x + 8.718, r ² = 0.990). Highest (p < 0.05) superoxide dismutase activity in gill was observed in the group fed with 0.75 % levan supplemented diet. Overall results indicated that dietary microbial levan at 0.75 % in C. carpio fry ameliorated the negative effects of fipronil and augmented the growth.     

Use of Rotenone as Piscicide: Toxicity Levels in a Few Common Freshwater Predatory and Weed Fishes

Toxicity of rotenone was studied in a few common freshwater predatory and weed fishes through wet laboratory experiments for its use as a piscicide during pond preparation. Cube root powder (CRP) (ENT-133 Rotenone) containing 9% rotenone was used as the toxicant source. Lethal concentration of CRP for these common predatory and weed fishes varied between 0.75–2.70 mg L^?1 (0.068–0.243 mg L^?1 of rotenone). Acute toxicity study revealed Puntius sophore to have more susceptibility to rotenone toxicity with 24 h LC₅₀ value of CRP at 0.50 mg L^?1 (0.045 mg L^?1 rotenone) compared to 1.17 mg L^?1 (0.105 mg L^?1 rotenone) in Anabas testudineus and 1.90 mg L^?1 in Channa punctatus (0.171 mg L^?1 rotenone); while Heteropneustes fossilis showed higher tolerance with 24 h LC₅₀ value at 2.42 mg L^?1 (0.218 mg L^?1 rotenone). Such result suggested rotenone toxicity to depend on the respiratory behavior of fish. The marginal reduction in 48 h LC₅₀ of CRP compared to its 24 h value and no fish mortality beyond 48-h in all tested species suggested faster degradation of the toxicant in water. Since application of the piscicide aims at eradication of all commonly available species of predatory and weed fishes in the culture pond, the study suggested a dose of 2.5 mg L^?1 of CRP (0.225 mg L^?1 rotenone) for pond application.     

Impact of yarn extension on packing density of ring spun yarn

The present paper deals with a detailed study on the effect of progressive yarn extension on diameter, overall packing fraction, radial packing fraction at different radial positions and partial packing fraction at different segments along the length of a fibre. An image processing based system to characterize and visualize the configuration of fibers in yarn in extended mode has been adopted. It has been observed that with the increase of yarn extension at different intervals, yarn diameter continuously decreases but at different yarn extension intervals, the percentage decrease value in the yarn diameter is different. But the packing density of yarn does not follow the exact trend of yarn diameter with the extension of yarn at different intervals. The yarn packing density initially increases at very high rate, then at very low rate and finally the packing density of yarn rather slightly decreases with the increase in yarn extension. The radial packing density of the yarn is not uniform across the cross-section of the yarn and it is not maximum near the yarn axis, rather it is maximum at some distance from the yarn axis. The location of maximum radial packing densities of yarn changes with the yarn extension. The partial packing density along the length of yarn is not uniform and the results are equally applicable for all level of yarn extension.     

PCR-based segregation of one hybrid variety of Labeo rohita and Catla catla from their wild-types

High consumer preference together with its polyculture potential has undoubtedly driven Rohu (Labeo rohita) and Catla (Catla catla) to top the list of the most preferred fishes among the Indian major carps. Commonly found in these fishes are hybrids that can be natural or man-made. Increasing emphasis on biodiversity issues has necessitated proper stock management of these through molecular genetics techniques. Also with few morphological differences that can be used to differentiate wild types and hybrids properly, the problem demands a straightforward molecular approach. Here, we report a simple PCR-based technique that can differentiate the hybrid variety from wild types easily using three different microsatellite markers. Three sets of primers were used to amplify three different microsatellite markers from the genomic DNA isolated from pectoral fins. When the PCR products using all three primer sets were analyzed, ‘hybrid–Rohu’ could be distinguished from wild types. Whereas the hybrid–Rohu DNA yielded specific PCR products with all three primer pairs, only two PCR products were obtained either from wild-type Catla DNA (by primer sets 1 and 2) or from wild-type Rohu DNA (by primer sets 1 and 3). This study clearly demonstrates that a simple PCR-based technique will help the fish breeders and hatcheries to identify and differentiate suspected hybrid–Rohu carp from the wild types within a few hours.     

Markers for selection of disease resistance in fish: a review

Aquaculture is the fastest growing food producing sector in the world. However, diseases result in a major loss in production. Among the several management techniques, selective breeding for resistant trait is one of the most reliable methods and provides long-term control over disease problems. Field survival or challenge survival records provide initial information of resistant stocks. However, selection programmes demand a proper marker which can identify the resistant stock easily with much accuracy. Several immunological indicators associated with resistance to a particular disease have been reported. These include positively correlated markers such as level of natural and specific antibody, respiratory burst activity of phagocytes and level of acute-phase ceruloplasmin protein and negatively correlated markers such as serum lysozyme, haemolytic and haemagglutination activities. However, for few fish species and pathogen-specific markers viz., myeloperoxidase activity, cortisol and glucose levels, macrophage aggregation and the level of plasma proteins, a confined conclusion of association has not been established. Besides immunological markers, molecular markers are in use because of their reliable screening methods. Genome can be scanned for molecular markers which provide the full linkage map of a species or stock. Association of these molecular markers with resistant traits gives rise to quantitative trait loci (QTL) for resistance to a particular pathogen. Screening of resistant stock can be carried out using these markers. Among the several marker systems, amplified fragment length polymorphism, microsatellites and single-nucleotide polymorphism play a major role in the process of selection for disease resistance. With the use of these marker techniques, we can avoid challenge testing where a huge number of animals were being killed. Multiple trait selection can also be possible with multiple QTL identification for resistance to two or more diseases simultaneously.     

Genetic variability and pathogenicity of Rhizoctonia solani associated with black scurf of potato in New Zealand

Isolates (a total of 129) of Rhizoctonia solani were collected from black scurf on potato tubers from different potato‐growing regions in New Zealand. Sequence analysis of the nuclear ribosomal DNA internal transcribed spacer (rDNA–ITS) regions from these isolates identified three anastomosis groups (AGs), AG‐3PT, AG‐2‐1 and AG‐5. Isolates classified as AG‐3PT were widely distributed, whereas AG‐2‐1 and AG‐5 were confined to distinct locations. Sequence heterogeneity was identified in the ITS regions of 100 AG‐3PT and AG‐2‐1 isolates. Variation in the sequence and length of the rDNA–IGS1 region was also observed for selected isolates of AG‐3PT and AG‐2‐1. Phylogenetic studies found all AG‐2‐1 isolates belong to AG‐2Nt, a subset of AG‐2‐1 previously associated with solanaceous crops in other countries. AG‐2‐1 isolates were consistently more aggressive than those of AG‐3PT. Delayed emergence, severe infection on stolons, formation of aerial tubers and considerable yield losses were associated with AG‐2‐1, but they caused negligible black scurf. In contrast, AG‐3PT caused black scurf on progeny tubers but variable effects on stem emergence and stolons. Furthermore, AG‐2‐1 isolates caused severe tuber malformation, but isolates of other AGs did not. This is the first report on the AG composition, genetic variability and pathogenicity of R. solani isolates associated with black scurf of New Zealand potatoes.     

Performance of polymer-coated urea in transplanted rice: effect of mixing ratio and water input on nitrogen use efficiency

Polymer-coated urea (PCU) is an important alternative to uncoated urea for improving nitrogen (N) use efficiency (NUE). Only a few studies discuss their utility for lowland rice systems. A 2-year field study was conducted to examine if nitrogen loading is reduced in lowland rice ecosystem by using mixture of PCU and uncoated urea without sacrificing yield. Five treatments involving two mixtures of PCU with 50 and 70% coated urea each at 70 and 50% of recommended dose (80 kg N ha⁻¹) and one with uncoated urea at 100% recommended dose were laid out in a completely randomized design. Selected plant growth parameters and plant available N contents (NH₄–N plus NO₃–N) in soil solution and ponded water were measured over a period of 65 days after transplanting. Results showed no significant difference for vegetative and yield parameters among different treatments suggesting that treatments receiving lower doses of nitrogen exhibited higher NUE. Analysis of partial factor of productivity (PFP) for N suggested that the total N dose may be reduced by 50% using mixtures of coated and uncoated urea. Similarly, statistically similar PFP values for treatments receiving the same amount of total N for both years and for both total N dose suggested that the proportion of coated urea may also be reduced to as low as 50% without sacrificing yield. Correlation analysis on nitrogen contents in ponded water and soil solutions and the analysis of water productivity and PFP showed that soil water regime could also significantly influence the nitrogen status in soil even when PCU are applied. In turn, both the water regime and N contents in soil ultimately influences grain yield. Although the constant release of N from coated fertilizer ensures adequate N supply for plant uptake, it may not completely avoid N deficit condition especially during heavy rainfall. Analysis of the developed production function suggested that 55–65% polymer coating and about 100 cm total water input may be ideal for achieving maximum yield. The production function was developed for PCU treatments using data observed in treatments receiving 70% recommended N dose. The range of water input in these treatments was 86.5–174.0 cm.     

Plasma Concentrations of 13, 14‐Dihydro‐15‐keto‐Prostaglandin F2α, Progesterone and Cortisol During Periparturient Period in Yaks (Poephagus grunniens L.)

An attempt was made to determine plasma concentrations of, 13, 14‐dihydro‐15‐keto‐prostaglandin F_2α (PGFM), cortisol and progesterone during periparturient period in yak. Plasma PGFM level showed an increasing trend beginning day 5 prior to parturition (0.48 ± 0.14 ng/ml) and increased steeply thereafter to reach a peak level (17.16 ± 1.31 ng/ml) on the day of parturition. The levels, then, declined sharply on day 1 postpartum to reach 1.20 ± 0.40 ng/ml and thereafter declined gradually over the days to reach 0.28 ± 0.09 ng/ml on day 20 postpartum and this level was maintained with fluctuation within narrow limits thereafter till conclusion of the blood sampling on day 90 post‐calving. The plasma progesterone concentration on days 7 and 6 before parturition was high (2.10 ± 0.10 and 2.12 ± 0.10 ng/ml, respectively). The level then decreased gradually and abrupt fall was observed 1–2 days before parturition and became basal on day of parturition (0.24 ± 0.04 ng/ml). This basal level was maintained till the end of the blood sampling on day 90 postpartum. Plasma cortisol level showed an increasing trend beginning day 2 prior to parturition (2.36 ± 0.65 ng/ml) and increased steeply thereafter to reach a peak level (26.65 ± 5.28 ng/ml) on the day of parturition. The levels, then, declined gradually over the days and touched 2.36 ± 0.25 ng/ml on day 3 postpartum and this level was maintained with fluctuation within narrow limits thereafter till day 7 post‐calving.