首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
4.
Protein digestibility was determined via two feeding trials in glass aquaria by the indicator (Chromium oxide) method using a mixture of shrimp powder with oil cake and wheat bran respectively (1: 1 W/W) as food. Analyses of feed were made to calculate the crude protein, carbohydrate, lipid and ash contents. Feces were analysed to determine their total nitrogen and chromium oxide. Protein digestibility was studied in relation to salinity of the medium size and weight of the fish body. The apparent digestibility of crude protein of a corresponding die has shown that 1st: Younger fish do possess a lower capability of protein digestion than fish having a medium weight and medium size; 2nd: Older fish with a high weight and large size exhibit no improvement in efficiency to digest the food protein, though their weight and size are significantly greater than those of middle weight and medium size fish; 3rd: The replacement of oil cake by wheat bran decreases the protein digestibility of shrimp powder mixture with them; 4th: A salinity (NaCl) of the aquatic medium at or above 3 g/l depletes the protein digestibility when fish of the same size were experimented with; but a salinity up to 2 g/l does not result in a significant decrease in the protein digestion rate.  相似文献   

5.
6.
The present paper deals with the toxic effects if any of the two concentrations of Arsenic(III)-oxide on the nucleic acids and protein metabolism in the liver of H. fossilis after exposure for 20 and 30 days. Causes for significant alterations have been discussed.  相似文献   

7.
The toxicity of the distillation wastes with low acidity, high turbidity and high organic load to the two fish species is tested by a laboratory test. The threshold value of toxicity is found at a 4 or 7 per cent dilution of wastewater. The statistical analysis of the survival rates has shown that the survival rates are significantly dependent on concentration and the time of exposure, for Puntius sophore also on temperature within the range of 20…34°C. Mystus vittatus proves to be the significantly more resistant species. The maximum permissible concentration of waste in the water ist calculated, too.  相似文献   

8.
9.
Fish, Cyprinus carpio and Channa punctatus in four sizes (6.0 ± 1.2; 12.5 ± 1.6; 20.6 ± 1.5 and 28.0 ± 1.8 cm in total length) were exposed to industrial effluents from the Sangam Dyeing Factory (Ludhiana), the Sterling Steel and ABC Paper Mills (Hoshiarpur) to evaluate the acute toxicity of these effluents at different fish sizes. Results reveal that the toxicity of industrial effluents decreased with the increased fish size from 6.0 ± 1.2 to 20.6 ± 1.5 cm in length. However, for specimens of the size of 28.0 ± 1.6 cm and more, the toxicity of the effluents increased with an increase in fish size. On the basis of the relative toxicity to fish, effluent from the Sterling Steel Mill was found to be highly toxic to fish and effluent from the Dyeing Factory least toxic except for the fish of 6.0 ± 1.2 cm at which dyeing factory effluent was most toxic and ABC paper mill effluent the least toxic.  相似文献   

10.
11.
The effect of a sublethal concentration of malathion (95% E. C.) on the nucleic acids (DNA, RNA) and protein content in the liver of fingerlings of Channa punctatus, a freshwater murrel was investigated. 10 days of exposure brought non-significant alteration (P < 0.05) neither in the nucleic acids nor in protein content. However, significant quantitative decline in the liver's RNA (P < 0.01) and protein (P < 0.001) but not in the DNA content was observed after 20 days of exposure. Possible causes for such decline have been discussed.  相似文献   

12.
The LC50 for exposure of 48 and 96 h is 34.64 and 18.5 mg/l Cd2+, respectively. During the exposure to 3.5 mg/l Cd2+ from the 13th day significant differences of length and mass occur with respect to the control. Over a total of 31 days of experiment the reduction of growth rates is 11% for the longitudinal growth and 16% for the increase in weight.  相似文献   

13.
Prolonged exposure to two pesticides Sevin and Thiodan for 30 days produced impairments in the brain of Channa striatus on the following ways:
  • – Separation and damage to meninges of cerebral hemispheres
  • – severe damage to all the five layers of the optic textum
  • – severe damage to torus longitudinalis
  • – partial damage to the molecular and grannular layers of the corpus cerebelli.
  • – no effect on diencephalon and myelencephalon.
  相似文献   

14.
15.
Fossil cyprinids from the upper part of the upper Eocene Youganwo Formation of Maoming, Guangdong, China were first studied in 1957 by Liu, who referred the only specimen to the genus Cyprinus as a new species, C. maomingensis. And this was suggested as one of the earliest records for fossil cyprinids. Unfortunately, this specimen is poorly preserved and reveals no more morphological information than its serrated last unbranched dorsal and anal fin rays. Recently, some new specimens were unearthed from the same locality, where C. maomingensis was discovered. In addition to the serrated dorsal and anal fin rays, these new materials also show that the pattern and shape of their pharyngeal teeth obviously differ from that of Cyprinus but resemble that of Procypris. However, its number of the branched dorsal fin rays and number of vertebrae are much less than that in Procypris. Morphologically, these specimens are closer to Procypris than to Cyprinus. This is the first report of fossil Procypris-like fish, and it implies that Procypris-like fish is an early member of the Tribe Cyprinini sensu stricto(sensu Yang et al., 2010) and the origin of this group can be traced back at least to the late Eocene.  相似文献   

16.
17.
The effects of DDT on the regeneration of cutaneous wounds has been studied in Mystus (mystus) vittatus. The fishes were locally collected, they were inflicted incised wounds surgically and kept in 0.01 and 0.15 ppm concentrations of DDT. The regenerating skin at different stages of development ranging from 15 min to 25 d after the injury was studied through microtomy sections. The following toxic effects were studied:
  • A small amount of DDT accumulated in the subcutis at the 25 days stage,
  • the regeneration of wounds under DDT stress has been slower, delayed or irregular,
  • the secretion of fibrinous exudate has been copious,
  • epithelization and fibroblastic activities have been slower,
  • the higher concentration of 0.15 ppm of DDT produced more toxic effects than the lower concentration of 0.01 ppm,
  • the earlier stages of wound healing up to 3 d have been more adversely affected than later stages.
  相似文献   

18.
Static bioassay acute toxicity tests of Zinc, Copper and Mercury were conducted to determine the median lethal concentrations (LC50s) of a freshwater teleost Channa marulius (HAM .) The 96 h LC50 and 95% confidence limits for Zn2+ were 25.61 (24.13 … 27.12) mg/l; 0.90 (0.80 … 1.038) mg/l; for Cu2+ and 0.314 (0.257 … 0.371) mg/l for Hg2+. However, these values decreased at 240 h of exposure and were: 21.09 (18.29 … 24.60) mg Zn2+/l; 0.66 (0.568 … 0.841) mg Cu2+/l; and 0.131 (0.103 … 0.158) mg Hg2+/l. The relative potency ratio of Zn/Hg, Zn/Cu and Cu/Hg suggests that fish were most sensitive to Hg, followed by Cu and Zn ions. The acute toxicities of mixtures of Zn2+?Cu2+; Zn2+?Hg2+, Cu2+?Hg2+ and Zn2+?Cu2+?Hg2+ up to 48 h of exposure were also investigated. The additive index and ranges for Zn2+?Cu2+ were ?0.241 (-0.577 … 0.054); 0.056 (-0.269 … 0.475) for Zn-Hg; 0.285 (-0.043 … 0.718) for Cu-Hg; and -0.542 (-1.215 … 0.005) for Zn-Cu-Hg. All the mixtures tested showed a greater than additive toxicity because index ranges overlapped zero.  相似文献   

19.
The effects of chronic exposures to sublethal concentration of two pesticides Carbaryl and Endosulfan on alkaline and acid phosphatase activities in the intestine of a fresh water teleost Channa striatus have been observed by exposing the fish for a period of two to thirty days to 10 ppm and 20 ppm of Carbaryl and 0.00075 and 0.001 ppm of Endosulfan. The inhibition of alkaline phosphatase activity has been dependent on the duration of exposure, concentration and the type of pesticide used. The acid phosphatase activity increased with the duration of exposure in higher concentration of Carbaryl and both the concentrations of Endosulfan. Endosulfan produced more pronounced effects than Carbaryl.  相似文献   

20.
An attempt has been made to study the toxicity of two commonly used pesticides aldrin (organochlorine) and ethyl-parathion (organophosphorus) to the fish Colisa fasciatus (Anabantidae) and Notopterus notopterus (Notopteridae). During bioassay studies, the behaviour of the fishes was recorded. The aldrin concentration used lies between 0.021 mg/1 and 0.042 mg/1 for C. fasciatus and 0.00056 mg/1 and 0.00135 mg/1 for N. notopterus. The ethyl-parathion concentration used lies between 1.8 mg/1 and 3.7 mg/1 for C. fasciatus and 0.49 mg/1 and 1.00 mg/1 for N. notopterus.
  • – The effect of lethal aqueous concentrations of pesticides on the Fishes prior to death are usually manifested by excitation, erratic swimming ability, difficulty in respiration, increasing in ventilation rate, jerky movements of body and fin fast, up- and downward movements, convulsions, loss of equilibrium, loss of the original colour of the body skin and the excess secretion of mucus by the gills and the body wall.
  • – the TLm values for 24, 48 and 96 hours of exposition are determined for both species of fish and both pesticides at the following variables:
  • ? three levels of temperature,
  • ? three levels of dissolved oxygen,
  • ? three levels of pH,
  • ? three fish sizes.
  • – statistical analysis of variance shows, that all variables have a significant effect on the TLm values of both pesticides for both fish species;
  • – Aldrin (chlorinated hydrocarbon) is more toxic than ethylparathion (organophosphate) at all variables;
  • Colisa fasciatus is the more resistant species than Notopterus notopterus.
  • – the relationship between the total number of the fishes N0, survival numbers N and time t can be expressed by a mathematical formula as:
  • – the harmless concentration to C. fasciatus ranged from 0.0049 mg/1 to 0.0161 for aldrin, 0.54 mg/1 to 0.99 mg/1 for ethyl-parathion and to N. notopterus from 0.00012 mg/1 to 0.00045 mg/1 for aldrin, 0.10 mg/1 to 0.21 mg/1 for ethyl-parathion;
  • – the aldrin should be diluted at least 4000 times and ethyl-parathion 320 times of its actual concentration.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号