Search Results

1 - 4 of 4 items

  • Author: A. Tripathi x
Clear All Modify Search
Monogenoidea on exotic Indian freshwater fishes. 2. Range expansion of Thaparocleidus caecus and T. siamensis (Dactylogyridae) by introduction of striped catfish Pangasianodon hypophthalmus (Pangasiidae)

Abstract

Thaparocleidus caecus and Thaparocleidus siamensis are parasitic monogeneans found on the gills of striped catfish Pangasianodon hypophthalmus (Pangasiidae), a native species of Southeast Asia. We report T. caecus and T. siamensis, for the first time in India, from the gills of aquarium-kept P. hypophthalmus (prevalence 40 % and 80 % respectively). We also report T. siamensis from the gills of pond-cultured P. hypophthalmus (prevalence 100 %); no specimen of T. caecus was observed on pondcultured P. hypophthalmus (prevalence 0 %). Morphometric data of the studied parasites did not differ significantly from previous descriptions of the two species recovered in other geographic locations. Similarly, no consequential variation was found when 28S rDNA of T. siamensis from the present study was compared with that of T. siamensis from Malaysia available on GenBank. The present investigation adds to growing cases of freshwater monogeneans that have been concomitantly introduced worldwide as a result of aquarium and aquaculture trade.

Open access
Impact Of Heavy Metals On Morphological And Biochemical Parameters Of Shorea Robusta Plant

Abstract

Pant P.P., Tripathi A.K.: Impact of heavy metals on morphological and biochemical parameters of Shorea robusta plant. Ekológia (Bratislava), Vol. 33, No. 2, p. 116-126, 2014.

A study was conducted to determine the impact of heavy metals (cadmium [Cd], arsenic [As] and lead [Pb]) on the morphological, and biochemical parameters of Shorea robusta and to investigate the uptake capacity of this plant for individual heavy metal. The study showed that all three heavy metals had significant adverse impact on most of the plant parameters of S. robusta, at all the given concentrations of 1, 5 and 10 mg/l. Maximum reduction in morphological parameters is observed in leaf area (92.67%) followed by shoot length (54%) and, root length (28.78%). Maximum reduction in biochemical parameters is observed in amino acid (75.13%) followed by chlorophyll (68.33%) and, crude protein (35.68%), whereas polyphenol and ascorbic acid showed maximum enhancement of 77.1 and 139.8%, respectively. The accumulation of heavy metals was found to be higher in the root than shoot of S. robusta with maximum accumulation being 0.053 mg/g in root for Cd, 0.17 mg/g of As in leaf and, 0.201mg/g of Pb in soil. Concentration- dependent changes were observed in most of the morphological and biochemical parameters, which may thus serve to determine suitable bio-indicators of heavy metal pollution.

Open access
Prevalence and intensity of Cornudiscoides agarwali (Monogenoidea) on the gills of Day’s mystus (Mystus bleekeri) in relation to some ecological and biological factors from Arunachal Pradesh, India

Summary

This work investigated the relationship of host size, seasons, and water quality parameters with the prevalence and intensity of Cornudiscoides agarwali on Mystus bleekeri collected from the Dikrong River in Arunachal Pradesh, India from February 2016 to January 2017. A total of 2760 specimens of C. agarwali were recovered from 114 individuals of M. bleekeri. The levels of mean intensity, but not the prevalence, of infection of C. agarwali were positively correlated with fish host size, peaking in the largest size class (45.20 ± 5.69 parasites/fish). The prevalence values had a statistically significant seasonal trend, reaching highest (100 %) during the pre-monsoon season, followed by 91.8% during the post-monsoon period and 87.5 % during the monsoon season. The levels of mean intensity of infection were also dependent on the seasons, reaching significantly higher levels during the pre-monsoon season (42.75 ± 4.18 parasites/fish). All water quality parameters measured were within the safety value recommended for freshwater aquaculture. Cornudiscoides agarwali maintained its prevalence above 87.5 % throughout the annual cycle, which means it was able to reproduce year-round in a non-polluted river. This could be an indication of monogenoidean community and population dynamics thriving best under optimum water quality parameters. Also, this article draws the attention of parasitologists and ichthyologists to a taxonomic problem of the misidentification of Mystus spp., and therefore, possibly of their parasitic monogenoids.

Open access
Effect of substrate temperature on the electrical and optical properties of electron beam evaporated indium antimonide thin films

Abstract

Thin films of non-stoichiometric indium antimonide (In0.66Sb0.34) have been deposited by electron beam evaporation technique on glass substrates at different substrate temperatures, (300–473 K). The films have polycrystalline nature with zinc blende structure. The decrease in electrical resistivity with increasing temperature shows semiconducting behavior. Hall measurements indicate that the films are of n-type. Optical transmission spectra of as deposited thin films have been measured at different substrate temperatures. All the electrical parameters i.e. electron mobility (µ), carrier concentration (n), resistivity (ρ), activation energy and band gap (E g) have been found to be temperature dependent. Suitable explanations are given in the paper.

Open access