Impact of methylparathion and malathion on cholinergic and non-cholinergic enzyme systems of penaeid prawn, Metapenaeus monoceros

The nervous tissue AChE, BUChE and glutaminase activity levels were significantly inhibited, whereas glutamine synthetase activity, acetylcholine and glutamine contents were increased significantly following the sublethal exposure of prawn, Metapenaeus, monoceros to methylparathion and malathion. During OPI exposure ammoniagenesis was triggered by increased deamination of purines and oxidative deamination of glutamate. This results in the hyperammonemia. As a consequence of hyperammonemia, the OPI exposed prawn tissue have adopted the suitable mechanisms to detoxity the ammonia by enhancing the synthesis of urea and glutamine. From the study, it has been observed that 10 days of reclamation period is not enough but the prawn nervous tissue showed efficient mechanisms for the detoxification or biodegradation of OPI molecules, which will pave way for the successful survival prawns.     

Tissue glycolytic potentials of penaeid prawn, Metapenaeus monoceros during methylparathion, carbaryl and aldrin exposure.

Changes in midgut gland and muscle tissue glycolytic potentials of penaeid prawn, Metapenaeus monoceros following exposure to methylparathion, carbaryl and aldrin were studied. A decrease in total carbohydrates, glycogen and pyruvate and an increase in lactate levels were observed. An increase in phosphorylase 'a' and aldolase activity levels suggested increased formation of trioses during selected insecticide toxicity. The decrease in the lactate dehydrogenase activity levels and an increase in the lactate content indicative of reduced mobilization of pyruvate into the citric acid cycle. During selected insecticide exposure, the prawn tissues adopting some sort of regulatory pathways such as enhanced glycolysis and a shift of metabolic emphasis from aerobiosis to anaerobiosis. All the above mentioned changes were more pronounced in the midgut gland compared to muscle tissue. The per cent decrease or increase are more under aldrin exposure followed by carbaryl and methylparathion exposure. The selected insecticides in the present investigation, though belongs to different representative groups, but appears to be neurotoxic leading to disturbances in the carbohydrate catabolism.     

Recovery of carbaryl inhibited AChE in penaeid prawn, Metapenaeus monoceros

The acetylcholinesterase activity in selected tissues of prawn, Metapenaeus monoceros showed a significant inhibition during commercial (CgC) and technical (TgC) grade carbaryl exposure. The rate of inhibition of AChE in nervous and non-nervous tissues is more under CgC over TgC exposure, suggests the involvement of emulsifier system for easy penetration of CgC molecule, which is absent in TgC. A progressive recovery of AChE activity from TgC and CgC induced inhibition was in the tissues within 10 days after the transfer of prawns to toxicant free water i.e., recovery or reclamation period. From the study, it has been observed that the inhibition of AChE activity is still persists evenafter 10 days of reclamation period, gives the idea of carbaryl accumulation at the cellular level or the reclamation period is not sufficient for the restoration of normalcy of AChE activity.     

Toxic impact of phosphamidon on acid phosphatase of prawn, Metapenaeus monoceros (Fabricius)

Activity levels of acid phosphatase (ACPase) in midgut gland and muscle tissues of penaeid prawn, Metapenaeus monoceros were studied after exposure to selected sublethal concentrations of phosphamidon after acute and chronic exposure. Phosphamidon was found to elevate the activity levels of ACPase in the selected tissues. The rate of elevation of ACPase is dose-dependant and is more at higher concentrations. Acute and chronic exposure to phosphamidon creates disturbances in the normal functioning at the cellular level in the tissues of prawn, M. monoceros.     

Inhibition and recovery of selected target enzyme activities in tissues of penaeid prawn, Metapenaeus monoceros (Fabricius), exposed to different insecticides.

The target enzymes, acetylcholinesterase (for phosphamidon and carbaryl) and Mg2+ ATPase (for DDT and fenvalerate) have been assayed during exposure and reclamation of these insecticides in M. monoceros. Toxicity of these insecticides are in the order: fenvalerate greater than DDT greater than carbaryl greater than phosphamidon. Reclamation studies show that fenvalerate is rapidly degradable while DDT is slowly degradable. It is suggested that pyrethroid, organophosphate and carbamate insecticides may be preferred over organochlorine compounds in farm operations.     

Studies on the behaviour and substratum preference in juveniles of the marine prawn,Metapenaeus monoceros (Fabricius)

Circadian rhythmicity in the behaviour of the marine prawn, Metapenaeus monoceros (Fab) and its substratum preference has been observed under laboratory conditions. In the morning at 9. a.m. 80% prawns remain buried and in the afternoon at 3 p.m. 60% burrowing was observed. A contrasting situation was observed in the night i.e. 17% burrowing at 9 p.m. and 30% burrowing at 3 a.m. was registered. In the second set of experiments juveniles were subjected to four types of substrata viz. mud, black fine sand, white coarse sand and stones. It was noted that M. monoceros showed more affinity towards the mud and less preference to other substrata. The obtained results are discussed to provide clues for prawn fishing.This work was supported by I.C.A.R., New Delhi through a project on Reprod. Endocr. Edible prawns.     

Effects of eyestalk ablation on moulting and growth of penaeid prawn Metapenaeus dobsoni (de Man)

Penaeid prawns M. dobsoni of two different size ranges were ablated both unilaterally (UEA) and bilaterally (BEA) and subjected to individual study. The UEA prawns consumed almost the same amount of food as the control prawns in the size group, 35-40mm, but consumed about 57.8% more food than the control prawns in the larger size group, 48-53mm. Growth was estimated as length and weight changes and significant variation was observed. The moult rate and dry moult weight showed marked differences. Average intermoult period increases with second ablation. Dry weight of moult in every succeeding moult was found to decrease irrespective of the level of ablation. Unilateral eyestalk ablation resulted in increase in dry weight whereas bilateral eyestalk ablation reduced the dry weight of moult and this decrease in the rate increased after each subsequent moult. In the larger size group, values of protein efficiency ratio (PER) were almost same as that of the lower size group. The UEA prawns exhibited highest conversion efficiency. The production rate of UEA prawns was 84% more than that of the control whereas BEA prawns indicated negative production. The same trend followed for net growth efficiency also. The results suggest that unilateral eyestalk ablation can be resorted to accelerate growth and conversion efficiency. Eyestalk ablation has been frequently resorted in matured forms for inducing maturation of gonads. For the first time attempts have been made to compare between the effects of removing one eyestalk versus two and changes taking place in juvenile forms especially in their physiology related to growth.     

Methylparathion, carbaryl and aldrin impact on nitrogen metabolism of prawn, Penaeus indicus

Changes in hepatopancreas, muscle and gill tissue nitrogen metabolic profiles were studied in a penaeid prawn, Penaeus indicus, following its exposure to sublethal concentrations of methylparathion, carbaryl and aldrin. In all the insecticide exposed prawn tissues, Ammonia levels were significantly increased and a shift in the nitrogen metabolism towards the synthesis of urea and glutamine was observed. Inhibition of glutamate oxidation to ammonia and alpha-ketoglutarate by glutamate dehydrogenase suggests a mechanism whereby hyperammonemia is reduced by minimizing the addition of further ammonia to the already existing elevated ammonia pool. Increased alanine and aspartate aminotransferases demonstrates the onset of gluconeogenesis. Mechanisms to detoxify the ammonia by enhancing the synthesis of urea and glutamine at the cellular level was observed in the selected tissues pave way for the survivability of prawns in insecticide polluted environs.     

Some aspects of respiratory metabolism of a penaeid prawn,Penaeus japonicus (Bate) (Crustacea,Decapoda, Penaeidae)

Respiratory metabolism of a marine penaeid prawn, Penaeus japonicus (Bate) was studied in relation to body size, starvation, dissolved oxygen tension, salinity and temperature. Oxygen consumption was significantly (P < 0.03) elevated with decline in body size. The rate of oxygen consumption was decreased significantly (P < 0.05) with an increase in the day of starvation, but the values of the loth and 15th day did not differ significantly (P > 0.05) from each other, indicating adaptation to starved conditions. Respiratory rate was on the ascending scale with an elevation in the surrounding oxygen content. Oxygen consumption increased significantly (P < 0.05) in both hyper- and hypotonic media. Rate of oxygen consumption was significantly (P < 0.05) augmented with an increase in the ambient temperature upto 34°C but a drastic fall was found at both low (18°C) and high (36°C) extreme temperatures. Functional significance of these findings to the prawn, in combating the environmental eddies is discussed.This investigation was supported by I.C.A.R., New Delhi, through a project No. 21 (80)/73-ASR (I)This investigation was supported by I.C.A.R., New Delhi, through a project No. 21 (80)/73-ASR (I)     

Role of eyestalk hormone in the carbohydrate metabolism of a marine penaeid prawn,Parapenaeopsis hardwickii (MIERS) (Crustacea,Decapoda, Penaeidae)

Data furnished here concern with the role of eyestalk hormone in the regulation of carbohydrate metabolism in Parapenaeopsis hardwickii. Bilateral eyestalk ablation has brought about a significant (P < 0.01) fall and rise in the glycogen content in the midgut gland and abdominal muscle respectively. Although eyestalk ablation resulted in a significant (P < 0.01) depletion of fat in midgut gland, n0 significant (P > 0.05) change was observed in the abdominal muscle. Eyestalk extract administration in eyestalk-less prawns has significantly (P < 0.05) restored the glycogen and fat metabolites in the midgut gland. There was an obvious change in the glycogen content of the midgut gland and abdominal muscle of normal prawns when injected with eyestalk extracts from prawns in different molting stages. Eyestalk extract from intermolt prawns caused a significant (P < 0.05) decrease and increase in the glycogen quantity in the midgut gland and abdominal muscle respectively. Eyestalk extract from premolt and postmolt prawns has, although not significantly (P > 0.05), decreased and increased the utilization of glycogen respectively in the midgut gland. The physiological significance of these findings are discussed briefly.Paper forms part IV of the series

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High and low molecular weight proteolytic activities in prawn (Metapenaeus brevicornis) muscle

Muscle extract of prawn (Metapenaeus brevicornis) expressed high azocoll lytic activity compared to extracts of many other prawn varieties; the activity was also inhibited to a small extent by dithiothreitol. Ammonium sulphate precipitation, subsequent extraction at pH 5.6 and chromatography revealed the occurrence of two types of azocoll lytic activities: one, high molecular weight (630 kDa) and the other low molecular weight (< 30 kDa) enzyme. The former was stimulated by dithiothreitol whereas the latter was inhibited. SDS PAGE of high molecular weight preparation did not show homogeneity but the profile was similar to that of the low molecular weight fraction. Gel filtration of high molecular weight enzyme following incubation at high pH revealed the formation of low molecular weight fractions having activity towards azocoll. Chymotrypsin-like activity associated with high molecular weight enzyme was also susceptible to dissociation by high pH. Azocoll lytic activity of both enzymes was strongly inhibited by 1,10-phenanthroline.     

The impact of fasting on adipose tissue metabolism

Fasting and starvation were common occurrences during human evolution and accordingly have been an important environmental factor shaping human energy metabolism. Humans can tolerate fasting reasonably well through adaptative and well-orchestrated time-dependent changes in energy metabolism. Key features of the adaptive response to fasting are the breakdown of liver glycogen and muscle protein to produce glucose for the brain, as well as the gradual depletion of the fat stores, resulting in the release of glycerol and fatty acids into the bloodstream and the production of ketone bodies in the liver. In this paper, an overview is presented of our current understanding of the effects of fasting on adipose tissue metabolism. Fasting leads to reduced uptake of circulating triacylglycerols by adipocytes through inhibition of the activity of the rate-limiting enzyme lipoprotein lipase. In addition, fasting stimulates the degradation of stored triacylglycerols by activating the key enzyme adipose triglyceride lipase. The mechanisms underlying these events are discussed, with a special interest in insights gained from studies on humans. Furthermore, an overview is presented of the effects of fasting on other metabolic pathways in the adipose tissue, including fatty acid synthesis, glucose uptake, glyceroneogenesis, autophagy, and the endocrine function of adipose tissue.     

Neuroendocrine control of reproduction in the male penaeid prawn,Parapenaeopsis hardwickii (Miers) (Crustacea,Decapoda, Penaeidae)

Effects of bilateral eyestalks ablation and injections of eyestalks, (Es) brain (Br) and thoracic ganglia (ThG) extract separately on the androgenic gland and testis development of Es-ablated (Experiment 1) and normal (Experiment 2) P. hardwickii, were investigated. The androgenic gland activity increased significantly in prawns having Es-ablated (Group II), and eyestalkless (Groups VI & VII) and normal (Groups D & E) prawns received Br and ThG extracts, separately, as compared to their respective controls (Groups I & A). Injection of unboiled Es extract in eyestalkless (Group V) and normal (Group C) prawns arrested the androgenic gland activity. Simultaneously, there was a significant (p<0.05) increase in the diameter of testicular follicles, testis weight, testis index and number of mature spermatocytes per follicle in the prawns of groups II, VI & VII of experiment 1 and of groups D & E of experiment 2 when compared to their respective controls. Injection of Es extract into the eyestalkless (Group V) and normal (Group C) prawns ceased testicular development. A significant (<0.05) decrease in testicular protein and midgut gland glycogen and lipid was found in groups II, VI & VII of experiment 1 and in groups D & E of experiment 2, but the glycogen and lipid content of the testis increased. These results indicate that the hormones released from the neuroendocrine centres regulate androgenic gland activity and spermatogenesis.     

Diagnosis of defects in oxidative muscle metabolism by non-invasive tissue oximetry

The dynamics of oxygen delivery and utilization are examined in a variety of mitochondrial disorders during rest, exercise and post exercise. We used a non-invasive optical technique to measure the oxygen consumption in the exercising limb in normal subjects and 5 patients with cytochrome c oxidase deficiency. We also examined 6 patients with MELAS and MERRF syndrome. We measured near-infrared spectra of hemoglobin in the gastrocnemius muscle during treadmill exercise. Normal subjects demonstrated a sustained deoxygenation during exercise, indicating an efficient utilization of delivered oxygen. Patients with cytochrome c oxidase deficiency demonstrated consistent oxygenation during exercise indicating an under utilization of delivered oxygen. Patients with MELAS and MERRF syndrome showed similar under utilization of oxygen during exercise. Non-invasive tissue oximetry during exercise demonstrates specific abnormalities in a variety of mitochondrial disorders, indicating abnormal oxygen utilization, and will be a useful addition to the clinical investigation of such disorders. (Mol Cell Biochem 174: 7–10, 1997)     

Studies of human achondroplasia: oxidative metabolism in tissue culture cells

Mitochondria prepared from the first growth of cells (fibroblasts) from skin biopsies from homozygous (but not heterozygous) achondroplastic human subjects were unable to carry out oxidative phosphorylation. However, successive crops of cells gained the ability to phosphorylate with normal P:O ratios with pyruvate-malate and succinate as substrates. Concentrations of cytochromes a + a3 were markedly and significantly lower in homogenates of homozygous achondroplastic tissue culture cells than in homogenates of normal cells. Levels of cytochromes a + a3 in the heterozygous achondroplastic cells were intermediate between the levels in normal cells and the homozygous achondroplastic cells. Activities of the mitochondrial oxidative systems (NADH, succinic and cytochrome oxidases) were not significantly lower in the achondroplastic cell preparations than in normal cell preparations under standard assay conditions (saturation levels of oxygen).     

Defensive and secondary metabolism in plant tissue cultures,with special reference to nicotinamide,glutathione and oxidative stress

The purpose of the presentation is to interconnect and illuminate certain parts of metabolism regarding stress signalling and defensive functions, including secondary metabolism in intact plants and plant tissue cultures. Increased cell/tissue levels of reactive oxygen species like H₂O₂, O₂ ^- and ·OH and the metabolism of glutathione, are linked to defensive/secondary metabolism and tissue differentiation. Special attention is paid to nicotinamide. A hypothetical role of nicotinamide and its metabolites as stress signals is also put forward especially in connection with hypomethylation of DNA. A role of DNA hypomethylation, as a link between various types of stressors and the induction of plant devensive metabolism, is discussed. We suggest that nicotinamide or nicotinamide based substances may be of value within biotechnology for the production of valuable substances as well as for plant protection.Abbreviations BSO buthionine sulfoximine - CHS chalcone synthase - GSH reduced glutathione - GSSG oxidized glutathione - INA isonicotinic acid - NIC nicotinamide - PADPRP poly(ADP-ribose)polymerase - PAL phenylalanine ammonia-lyase - SA salicylic acid - SAM S-adenosylmethionine - SSB single strand breakage