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EFFECTS OF UV-B RADIATION ON AQUATIC ECOSYSTEM


Sharma, J. G., Masuda, R. and Tanaka, M. 2005. Ultrastructural study of skin and eye of UV-B irradiated ayu Plecoglossus altivelius. Journal of Fish Biology 67: 17.

A scanning electron microscopic study of the skin and eye of UV-B radiated ayu Plecoglossus altivelius (age 30 days, meanS.E. total length: 16.250.11 mm) under laboratory condition showed marked changes when compared with the control fish without UV-B radiation. The exposure of the fish to the radiation resulted in the destruction of microridges in the epidermis and exposed neuromast cells of the skin. Domed protrusions were also more common in the skin of UV-B radiated fish than in the control fish. The appearance of mucus in both groups was different. In the control skin the mucus was spread over a wide area whereas in the treated fish the mucus was concentrated in a small area. The anastomozing structures of the microridges of the eyes were lost in UV-B radiated fish and the microridges themselves were fewer in number, fragmented, and aggregated. Mucus cells, prominently visible in the control fish, were distorted in the treated fish. Cell contours were irregular in UV-B radiated fish and cell to cell contacts had been lost in this group. 

Sharma, J. G. and Chakrabarti, R. 2006. Effects of UV-B radiation on the gills of Catla catla during early development. Toxicological & Environmental Chemistry 82: 367-371.

Scanning electron microscopic study of gills of Catla catla catla (17-day-old) exposed to UV-B radiation (145 W/cm2 at the water surface) for three different exposure times: 5, 10 and 15 min was conducted. Fish without UV-B exposure served as control. UV-B radiation damaged both gill filaments and lamellae. The intensity of damage was minimal in 5 min exposed fish, followed by 10 min exposed fish and maximal in 15 min. The gill epithelium was severely damaged in 15 min irradiated fish compared to control. Pavement cells (PVCs) were damaged and the numbers of microridges within PVCs decreased. The deep, boundary of PVC was not clear. In some area of gill epithelium, PVCs were destroyed and mitochondrion-rich cells (MRCs) were exposed. The 5 min exposure reduced the number of microridges in the pavement cells, but the boundary of PVCs was still visible. MRCs in the gill epithelium were not exposed in 5 min exposed fish. The damage to PVCs and subsequent exposure of MRCs in UV-B irradiated fish may hamper respiratory functions and disturb osmoregulation in catla.

Sharma, J. G., Masuda, R. And Tanaka, M. 2007. Orientation behaviour of Pagrus major larvae exposed to UV-B radiation in laboratory conditions. International Journal of Radiation Biology 83: 49-52.

Purpose: The increasing intensity of ultraviolet-B (UV-B) radiation is a potential threat to the aquatic environment. The recognition capacity of the aquatic animals may help them to avoid this harmful radiation. The response of individual species, especially during early development may help to understand the vulnerability of that species and its potentiality in natural fishery.

Materials and methods: The orientation behaviour of red sea bream Pagrus major larvae exposed to UV-B radiation (280 - 315 nm) was studied within the laboratory (1.41 W/m2) under following experimental conditions: (i) two fluorescent lamps fixed above the tank, (ii) one fluorescent lamp on the left side, one fluorescent lamp and one UV-B lamp on the right side, and (iii) one UV-B lamp and one fluorescent lamp on the left side, one fluorescent lamp on the right side of the tank. Results: In the first treatment, 7-and 20-day-old larvae were significantly (p < 0.0095) higher in number at the right side than left and middle regions of the tank. Some 33 - 60% of larvae were found in the middle region of the tank at the age of 30 - 32 days. In the second treatment, significantly (p < 0.0034) lower numbers of larvae (10 - 13.3%) were found in the middle region of the tank compared to the other sides between days 17 and 20, whereas 40 - 86.67% larvae were found in the middle region between days 25 and 36. In the third treatment, significantly (p < 0.015) higher numbers of larvae were found in the right side at the age of days 17 - 25 and in the middle region between days 32 and 36. Conclusions: This study showed that UV-B sensitivity of P. major developed during ontogenic development. Care should be taken at early stages.

Sharma, J. G., Mittal, P. and Chakrabarti, R. 2008. Development of survivorship model for UV-B irradiated Catla catla larvae. Aquatic Ecology 42: 17-23.

A survivorship model was developed for UV-B irradiated Catla catla (17 days) larvae with the help of Kaplan and Meier Product-Limit (PL) method. Larvae were exposed to UV-B radiation (145 W/ cm2) for three different exposure times: 5, 10 and 15 min on every other day. The mean survival time of fish was calculated for each treatment using uncensored and censored survival data during 74 days study period. The mean uncensored and censored survival data for the 5-min exposed fish were 7 and 43, respectively. In 10-min exposure period, the uncensored and censored survival data were 19 and 31, respectively. During maximum exposure of 15 min, the uncensored survival data was 20 and censored data was 30. The mean survival time of fish calculated using PL estimate in 5, 10 and 15 min exposure treatments were 69.61 0.50, 65.25 0.96 and 60.60 1.55 days, respectively. The mean survival time showed a decreasing trend with the increase of exposure period. The survival time was significantly (P < 0.001) higher in 5-min exposure treatment than others. This is clear from the present study that the exposure of UV-B radiation affects the survival rate of surface feeder catla larvae.

Sharma, J .G., Rao, Y. V., Kumar, S. and Chakrabarti, R. 2010. Impact of UV-B radiation on the digestive enzymes and immune system of larvae of Indian major carp Catla catla. International Journal of Radiation Biology 86: 181-186.

Purpose: Ultraviolet radiation is a potent threat to the aquatic animals. Exposure to such stressor affects metabolic and immunological processes. The present investigation aims to study the effect of UV-B radiation on digestive enzymes and immunity of larvae of Catla catla.
Materials and methods: Larvae were exposed to ultraviolet-B (UV-B, 280–320 nm) radiation (145 μW/cm2) for three different exposure times of 5, 10 and 15 min on every other day. After 55 days, important digestive enzymes were assayed. For immunological study, lysozyme, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) levels were measured. Then the fish were kept for one month without radiation and lysozyme level was measured.
Results: Protein concentration varied directly with the duration of exposure and was highest among fish that had received the 15 min UV-B irradiation. Significantly higher amylase, protease, trypsin and chymotrypsin activities were found in 5 min exposed fish compared to others. Lysozyme level was significantly higher in control group compared to the UV-B treated fish. The lysozyme level decreased with the increasing duration of UV-B radiation. When fish were kept without UV-B radiation for one month, lysozyme level was brought to the normal level in all treatments, except 15 min exposed fish. The GOT and GPT levels were significantly higher in the 15 min exposed group than others.
Conclusions: The effects of UV-B radiation on the digestive physiology and immune system of catla have been clearly observed in the present study. The decreased enzyme activities in UV-B radiated fish results into improper digestion and poor growth.

Singh, K. M., Sharma, J. G. and Chakrabarti, R. 2013. Effect of UV-B radiation on the defense system of Labeo rohita (Cyprinidae) larvae and its modulation by seed of Achyranthes aspera. Acta Ichthyologica et Piscatoria (Scientific Society of Szczecin, in press)..

Background. Ultraviolet (UV-B) radiation affects the immune system of fish. Dietary supplementation of natural immunostimulant may enhance the immunity of fish. The present investigation evaluates the UV-B protective property of Achyranthes aspera seed in Labeo rohita larvae.
Materials and methods. Larvae (1.190.03 g) were fed with four type of diets containing 0.1, 0.5, 1.0% Achyranthes aspera seeds and control diet. After 51 days, larvae of each feeding scheme were divided into two groups. One group was exposed to UV-B radiation (80 W cm-2) and the other remained unexposed.
Results. Average weight was significantly (P < 0.05) higher in 0.5% seed supplemented diet fed fish compared to the others. UV-B radiation affected the growth of 0.1% seed supplemented and control diets fed fish, other two treatments remained unaffected. Total serum protein, albumin and globulin levels were significantly (P < 0.05) higher in exposed fish compared to the unexposed one. Among the exposed groups, serum glutamic oxaloacetic transminase and serum glutamate pyruvate transminase levels were minimum in 1.0% seed supplemented diet fed fish, whereas highest levels of myeloperoxidase, hemagglutination titre and white blood cells were found in 0.5% seed supplemented diet fed group.
Conclusion. Dietary supplementation of seed at 0.5% level enhanced the growth and immunity of UV-B exposed fish.

Singh, K. M., Sharma, J. G. and Chakrabarti, R. 2013. Impact of UV-B Radiation on the physiology of freshwater carp Labeo rohita larvae and evaluation of UV-B protective properties of seeds of Achyranthes aspera and vitamin C. Agricultural Research (Springer) 2: 166-171..

Effect of harmful UV-B radiation and their remedial measures have been studied in Labeo rohita (rohu) larvae. Larvae were fed with four different diets: D1 and D2 contained 0.1 and 0.5% Achyranthes aspera seeds, respectively; D3 contained 800 mg vitamin C/kg diet and D4, control diet. After 50 days, all groups were exposed to UV-B radiation (80 W/cm2). One batch of control diet fed fish was exposed to UV-B (D4Ex) and the other group remained unexposed (D4UEx). Survival rate of rohu was significantly (P < 0.05) higher in D2 compared to others. Among the exposed groups, highest average weight was recorded in D2 (103 4 mg). Total tissue protein concentration was higher in exposed groups compared to the unexposed one. GOT and GPT levels were minimum in unexposed control diet fed fish. Vitamin C provided protection against lipid peroxidation which was evident from the lowest level of thiobarbituric acid reactive substance in exposed fish (D3). Significantly (P < 0.05) higher nitric oxide synthase level in fish fed with Achyranthes aspera seeds (0.5%) supplemented diet confirmed the immunomodulatory property of the seeds. A combination of vitamin C and seed may be more UV-B protective for carp larvae.

N. Radhakrishnan, N., Rullah, K., Chakrabarti, R. and Gnanamani, A. 2013. Inhibition of UVB induced oxidative stress in Catla catla & glutamate pyruvate transaminase (GPT) activities by embelin using molecular docking tool. Journal of Chemical and Pharmaceutical Research 5: 1094-1099.

The present study aimed to evaluate the inhibitory effect of embelin against UVB induced oxidative stress using in vivo (Catla catla) fish model. Larve [Catla catla (1.20.01 mg)] were fed with three types of diets control diet (Group I & Group II with and without UVB exposure) and diet containing 0.1 & 0.5% embelin (Group III & IV) respectively. After 40 days of feeding, embelin fed fishes (Group III & IV) were exposed to UVB radiation (145 W/cm2) for six days for 10 minutes. Survival rate of fishes after UVB exposure was recorded. Tissue samples were collected from the whole body and used for biochemical and enzyme analyses. In additional to these, we also docked embelin, 5-O-methyl embelin and vilangin with glutamate pyruvate transaminase (GPT) chain-A using Discovery Studio Version 3.1. Results revealed that statistically significant difference in the survival rate was observed between the control verses embelin fed fishes. Similarly, significant reduction in Glutamate oxaloacetate transaminase (GOT) and Glutamate pyruvate transaminase (GPT) enzymes were observed in the embelin fed fish groups. With reference to docking studies, vilangin fails to dock, whereas embelin and 5-O-methyl embelin showed interaction energy of -38.0 & -38.3 kcal/mol respectively. Thus, the present study suggested that embelin protects Catla catla (fish) against UVB induced oxidative stress, which could also substantiate our earlier in vitro study.

Sharma, J. G., Singh, M. K. and Chakrabarti, R. 2015.Physiological responses of Catla catla larvae fed with Achyranthes aspera seed enriched diet and exposed to UV-B radiation. Indian Journal of Biochemistry & Biophysics 52: 155-160 (CSIR).

Effect of harmful UV-B radiation and their remedial measures have been studied in Labeo rohita (rohu) larvae. Larvae were fed with four different diets: D1 and D2 contained 0.1 and 0.5% Achyranthes aspera seeds, respectively; D3 contained 800 mg vitamin C/kg diet, and D4 contained control diet. After 50 days, all groups were exposed to UV-B radiation (80 W/cm2). One batch of control diet-fed fish was exposed to UV-B (D4Ex), and the other group remained unexposed (D4UEx). Survival rate of rohu was significantly (P<0.05) higher in D2 when compared to others. Among the exposed groups, highest average weight was recorded in D2 (103 4 mg). Total tissue protein concentration was higher in exposed groups compared to the unexposed one. Glutamic oxaloacetic transaminase (GOT) and glutamate pyruvate transminase (GPT) levels were minimum in unexposed control diet-fed fish. Vitamin C provided protection against lipid peroxidation which was evident from the lowest level of thiobarbituric acid reactive substance in exposed fish (D3). Significantly (P<0.05) higher nitric oxide synthase level in fish fed with Achyranthes aspera seeds (0.5%) supplemented diet showed the immunomodulatory property of the seeds. A combination of vitamin C and seed may be more UV-B protective for carp larvae.

Singh, K. M., Sharma, J. G. and Chakrabarti, R. 2015. Simulation study of natural UV-B radiation on Catla catla and its impact on physiology, oxidative stress, Hsp70 and DNA fragmentation. Photochemistry and Photobiology (Elsevier B.V.) 149: 156-163.

UV-B radiation is a potential stressor to the aquacultural species. Catla catla, catla larvae (1.08 0.065 g) were exposed to different doses of UV-B radiation, 0 (control), 504, 1008, 1512 and 2016 mJ/cm2 at a mean radiant energy of 80 W/cm2 for 21 days. The dose of UV-B radiation was selected on the basis of the field study conducted in Lake Naini, Delhi, India (Latitude: 28_4102600N and Longitude: 7712003700E). Significantly (P < 0.05) lower survival, average weight and specific growth rate were found in UV-B irradiated larvae compared to the control one. Food conversion ratio was 1.5-4-fold higher in UV-B treated larvae compared to the control one. The carbonyl protein (CP), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) levels were significantly (P < 0.05) higher in UV-B irradiated larvae compared to the control group. Among the treated larvae, CP and SOD were significantly (P < 0.05) higher in larvae exposed at 1512 mJ/cm2 UV-B. A correlation was found between the CP and SOD (R2 = 0.834). Highest TBARS level was found in 2016 mJ/cm2 UV-B exposed catla. Nitric oxide synthase level was significantly (P < 0.05) lower in UV-B exposed larvae compared to the control one. A 3-fold increased Hsp 70 level was recorded in UV-B irradiated catla compared to the control larvae. Comet assay analysis indicated that UV-B irradiation enhanced DNA fragmentation. Tail extent moment and the olive tail moment were significantly (P < 0.05) higher in 2016 mJ/cm2 UV-B exposed catla compared to others. The tail length was significantly (P < 0.05) higher in 1512 and 2016 mJ/cm2 UV-B exposed larvae compared to the other doses. The present study suggests that the catla is a useful species for the biomonitoring of stress in the aquatic environment.



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