Biochemical changes in tissues of goldfish acclimated to high and low temperatures. I. Protein synthesis

Hemato-biochemical alteration in the bronze featherback Notopterus notopterus (Pallas, 1769) as a biomonitoring tool to assess riverine pollution and ecology: a case study from the middle and lower stretch of river Ganga

Fishes are poikilothermic animals and are rapid responders to any sort of ecological alteration. The responses in the fish can be easily assessed from their hematological and biochemical responses. To study the variation in the hemato-biochemical parameters in retort to ecological alteration and ecological regime, a study was conducted at six different sampling stations of the middle and lower stretches of river Ganga. Various hematological and biochemical responses of fishes were also monitored in response to multiple ecological alterations. For the assessment of ecological alteration, various indices were calculated such as the water pollution index (WPI), National Sanitation Foundation-water quality index (NSF-WQI), and Nemerow's pollution index (NPI) has been calculated based on various water quality parameters such as dissolved oxygen (DO), pH, total dissolved solids (TDS), total alkalinity (TA), total hardness (TH), electrical conductivity (EC), biochemical oxygen demand (BOD), chlorinity (CL), total nitrogen (TN), and total phosphorus (TP). The hematological parameters such as WBC, RBC, platelet, hemoglobin, and hematocrit were monitored. The serum biochemical parameters such as SGPT, SGOT, ALP, amylase, bilirubin, glucose, triglyceride (TRIG), and cholesterol (CHOL) were investigated. The study revealed that NSF-WQI varied from 45.08 at Buxar to 110.63 at Rejinagar and showed a significantly positive correlation with SGPT, SGOT, ALP, TRIG, CHOL, and WBC, whereas a significantly negative correlation was observed between TRIG and RBC. WPI varied from 19 to 23 and showed a significant positive correlation with SGOT and a negative correlation was observed with total nitrogen. The PCA analysis illustrated the significance of both natural as well as anthropogenic factors on riverine ecology. Strong positive loading was observed with SGPT, SGOT, ALP, and platelet. The study signified the need for monitoring the hemato-biochemical responses of fishes in response to alterations in the ecological regime.

The 4E-BP growth pathway regulates the effect of ambient temperature on Drosophila metabolism and lifespan

Changes in body temperature can profoundly affect survival. The dramatic longevity-enhancing effect of cold has long been known in organisms ranging from invertebrates to mammals, yet the underlying mechanisms have only recently begun to be uncovered. In the nematode Caenorhabditis elegans, this process is regulated by a thermosensitive membrane TRP channel and the DAF-16/FOXO transcription factor, but in more complex organisms the underpinnings of cold-induced longevity remain largely mysterious. We report that, in Drosophila melanogaster, variation in ambient temperature triggers metabolic changes in protein translation, mitochondrial protein synthesis, and posttranslational regulation of the translation repressor, 4E-BP (eukaryotic translation initiation factor 4E-binding protein). We show that 4E-BP determines Drosophila lifespan in the context of temperature changes, revealing a genetic mechanism for cold-induced longevity in this model organism. Our results suggest that the 4E-BP pathway, chiefly thought of as a nutrient sensor, may represent a master metabolic switch responding to diverse environmental factors.

Cold acclimation strategy is highly variable among the sunfishes (Centrarchidae)

We tested the hypothesis that the physiological strategy for acclimating to low body temperature is similar among closely related fish. Largemouth bass (Micropterus salmoides), green sunfish (Lepomis cyanellus), bluegill sunfish (Lepomis macrochirus), black crappie (Pomonix nigromaculatus), and white crappie (Pomonix annularis), all members of the family Centrarchidae, were acclimated to 5 degrees and 25 degrees C. Morphometric variables (total mass, total length, organ masses) and enzyme activities (hexokinase; lactate dehydrogenase; and cytochrome oxidase in heart, liver, and muscle) were measured in 5 degrees C- and 25 degrees C-acclimated fish at 5 degrees and 25 degrees C assay temperatures. Each species displayed a distinct physiological response to cold acclimation that differed among tissues. These data suggest that the response to cold acclimation is highly variable within families. Our findings are consistent with other studies suggesting that acclimation responses are labile and may evolve independently even among closely related species.

Cold-acclimation-induced protein hypertrophy in channel catfish and green sunfish

1. Following acclimation of channel catfish to a reduction in temperature from 25 degrees to 15 degrees C, there were approximately two-fold increases in liver mass, cell size, total protein, and total enzyme activity, relative to activity per milligram of protein and per gram wet weight of tissue, indicating tissue hypertrophy. There was no change in either total liver DNA content or protein concentration per gram weight. 2. Green sunfish, unlike catfish, showed virtually no change in liver mass following cold acclimation. However, sunfish showed a net increase in total liver protein content and an increase in protein concentration. The increase in protein content was balanced by a reciprocal and equivalent decrease in glycogen content. Consequently, liver mass was maintained. 3. During cold acclimation both catfish and sunfish showed an increase in ventricular heart mass and protein content, but no change in protein concentration. 4. The activities of several enzymes were measured in liver from 15 degrees C and 25 degrees C steady-state-acclimated catfish and at intervals following transfer from 15 degrees to 25 degrees C and from 25 degrees to 15 degrees C. Total tissue enzyme activity showed positive compensation which correlated with the change in liver mass and protein content. Specific activities based on protein and on wet weight showed dissimilar acclimatory patterns. Two enzymes - cytochrome oxidase and lactate dehydrogenase - showed inverse compensation in specific activity but positive compensation in total activity. Citrate synthase, glucose-6-phosphate-dehydrogenase and 6-phosphogluconate dehydrogenase showed positive compensation in both specific and total activities. 5. The increase in tissue protein content or 'protein hypertrophy' occurred with cell hypertrophy in cold-acclimated catfish, while protein hypertrophy occurred as an increased protein concentration without cell hypertrophy in sunfish. This phenomenon is considered adaptive in that it permits a compensatory increase in the total enzymatic capacity of a tissue. The two-fold increases in total enzyme activities, superimposed on either an increase or decrease in specific activity, suggest that two biochemical mechanisms may be operative during cold-induced liver hypertrophy, one effecting a specific step in protein translation at a point common to the synthesis of all proteins and a second targetted pretranslationally, i.e., transcriptional regulation.

Effect of acclimation temperature on the elongation step of protein synthesis in different organs of rainbow trout

Cytosolic extracts of liver, kidney, spleen, gill, red and white muscle from rainbow trout acclimated to 4 and 17 degrees C, respectively, have been investigated in vitro with respect to their enzymic activity in stimulating the growth of nascent peptide chains (labelled polyphenylalanine) at assay temperatures from 5 to 25 degrees C using polyuracil as messenger RNA. The elongation step of protein synthesis is characterized by a Q10 value of about 2.4 (range 10-25 degrees C) in all organs from both, 4 and 17 degrees C acclimated fish. Except for the red muscle, the organs of cold acclimated trout, however, exhibit significantly higher specific elongation rates (mol phenylalanine polymerized/(g wet weight X h)) at any experimental temperature than those of warm acclimated fish. This increase of the elongation rates varies between the organs and ranges from +29% (liver) to +60% in the gill. The specific acylation rate (mol phenylalanyl-tRNA formed/(g wet weight X h] surpasses the specific elongation rate by a factor of at least 8.5. Moreover, the specific acylation rate per mg protein is independent of acclimation temperature. It is concluded that the increased specific elongation rates in 4 degrees C acclimated trout are not due to altered pool sizes of the precursor phenylalanyl-tRNA, but reflect an effective enhancement of enzymic elongation factor activities. In accordance with data taken from literature, this finding suggests a compensatory enhancement of in vivo protein synthesis to occur in trout during cold acclimation.

Effects of temperature, food deprivation and salinity on growth, RNA/DNA ratio and certain enzyme activities in rainbow trout (Salmo gairdneri Richardson)

1. The connection between feeding regime (food deprivation and restricted diet) and thermal acclimation (1-2, 6, 11 and 16 degrees C) was studied in rainbow trout held in diluted seawater (20% S). 2. At 1 degree C, food deprivation effects on all parameters are slight, and on RNA and certain enzymes they are masked by thermal acclimation effects. 3. At a salinity of 20% rainbow trout on a restricted diet and held at 11 degrees C have the highest growth rate. 4. Owing to increasing RNA levels, the RNA/DNA quotient is significantly higher than normal in rainbow trout held at 1 degree C although the fishes do not grow at this temperature. 5. Temperature and feeding both affect the enzymes we studied (liver: G1DH, AspT, arginase, G6PDH, and 6PGDH; kidney: G1DH, AspT, arginase, and Na/K-ATPase; white muscle: AspT and A1T; gill: Na/K-ATPase) differently. Interactions between these two factors also occur in some cases.

Ultrastructure of hepatocytes in golden ide (Leuciscus idus melanotus L.; Cyprinidae: Teleostei) during thermal adaptation

The morphological alterations of hepatocytes of golden ide, Leuciscus idus melanotus, following adaptation to low and high temperatures (14 and 28 degrees C) were investigated by means of light and electron microscopy. The temperature-dependent behaviour of peroxisomes was visualized cytochemically with the alkaline diaminobenzidine medium; the morphological studies were supplemented by the biochemical determination of catalase activity. Cold adaptation of ide hepatocytes is manifested by proliferation and stacking of endoplasmic reticulum, an enhanced secretory activity of Golgi fields and a higher number of peroxisomes as compared with the warm-adapted animals. The latter organelles are characterized by a marked heterogeneity in size, shape and catalase activity, and by a more intimate association with mitochondria and endoplasmic reticulum. The occurrence of small peroxisomal profiles is restricted to lower temperature. Catalase activity can be shown both cytochemically and biochemically to increase during cold adaptation. Whereas the number of mitochondria seems to be unaffected by thermal adaptation, stacking of mitochondria as well as the formation of intramitochondrial membrane piles indicate cold-adaptive processes. A feature typical of warm-adaptation is the formation of membrane-glycogen complexes, which may represent the morphological expression of enhanced carbohydrate metabolism documented in a decreased storage of glycogen at 28 degrees C. At 28 degrees C lipid is the predominant storage product. These findings indicate that fish liver is well-suited to serve as a model for the analysis of the interaction of environmental temperature conditions and hepatic morphology.

Fish liver protein synthesis during cold acclimatization: seasonal changes of the ultrastructure of the carp hepatocyte

A cell-free system, active in protein synthesis, was constructed using ribosomes and supernatant factors isolated from the livers of winter-acclimatized carps. Upon seasonal adaptation, the hepatocytes of these fishes exhibited distinctive morphological features that were not sex dependent. The cytoarchitecture of the liver cell from summer carps is consistent with the cellular arrangements found when the rate of gene expression is high. During winter, several morphological features reveal that macromolecular synthetic activity may be clearly diminished.

Effects of ambient temperature on brain acetylcholinesterase activity and protein content in three Egyptian vertebrates

Exposure to cold caused an increase in AChE activity of the different brain regions of both Arvicanthis and Columbia and a decrease in the enzyme activity of Scincus midbrain. Heat exposure provoked variable changes in AChE activity of the various brain regions of the three experimental species. The changes in AChE activities may be one of the mechanisms by which birds and mammals tend to acclimatize themselves to various forms of stress. In reptiles, AChE activity varied with changes in ambient temperature and this is probably due to the adaptive significance of thermally directed changes in enzyme substrate affinity.

Quantitative protein synthetic rates in various tissues of a temperate fish in vivo by the method of phenylalanine swamping

1. A single high-dose injection of 14C- (or 3H-) phenylalanine was used for measurement of protein synthetic rates in tissues of toadfish, Opsanus tau, in vivo. 2. Average rates at 20 degrees C, as per cent of tissue protein synthesized per day, were as follows: liver, 14; head kidney, 15; gill, 7.7; spleen 5.0; heart, 2.3; testis, 1.4; epaxial and pectoral muscle, 0.20-0.23. Elevated rates in muscle (0.71%/day) were found in fed fish. 3. Temperature dependency (Q10) in the 10-20 degrees C range averaged 6-7 for tissues with high rates of protein turnover, and 3-4 in heart and muscle after two-weeks acclimation.

Changes in particulate-bound protease activity during cold acclimation in Tetrahymena pyriformis

The protease activity, as assayed at pH 8.0 with azocasein as substrate, of a ciliate protozoan Tetrahymena pyriformis NT-1, was found to alter by growing the cells at various constant temperatures or at shifted temperatures. The intracellular protease activity, when cells were grown at either constant 39 degrees C or 15 degrees C, was decreased throughout the growth phase with significant secretion into the medium. On the other hand, when the culture temperature was transferred from 39 degrees C to 15 degrees C, the protease activity in cells was greatly increased up to about 28-fold at 8 h after the shift. There was, however, no secretion into the medium during the cold acclimation after the shift, where no cell division occurred. The elevated protease activity was quickly decreased to the control level when the culture was warmed to 39 degrees C after 8-h chilling, and recovery of normal cell division was seen. The marked increase in the protease activity caused by the shift to 15 degrees C was completely blocked by the addition of either cycloheximide or actinomycin D. The thermally induced enhancement of protease activity was found to occur with no different preference between three protease fractions.

Characterization of glycoprotein antifreeze biosynthesis in isolated hepatocytes from Pagothenia borchgrevinki

Incorporation of 14C-leucine and 3H-alanine into TCA-precipitable protein. TCA-soluble protein, and antifreeze glycoproteins (AFGP) was measured in isolated hepatocytes from Pagothenia borchgrevinki Boulenger following acclimation to -1.5 degrees C and +4 degrees C. the rate of 3H-alanine incorporation into AFGP followed Michaelis-Menten kinetics with a Vmax of 4.8 nM X mg protein-1 X h-1 at -1.5 degrees C and 7.5 nM X mg protein-1 X h-1 at +4 degrees C. Km values were 27.9 microM and 41.7 microM at -1.5 degrees C and +4 degrees C, respectively. Incorporation of 14C-leucine into TCA-precipitable protein also showed Michaelis-Menten kinetics with a Vmax of 20 nM X mg protein-1 X hr-1 at 1.5 degrees C and 32.3 nM X mg protein-1 X hr-1 at +4 degrees C. Km values were 83.3 microM at -1.5 degrees C and 125 microM at +4 degrees C. AFGP synthesis was monitored over a 120-h period by radioimmunoassay in cultures of hepatocytes from cold acclimated fish (-1.5 degrees C) incubated at both -1.5 degrees C and +4 degrees C. The estimated Q10 for AFGP from these data is 3.23. Polyacrylamide gel electrophoresis of antifreeze glycoproteins produced by isolated hepatocytes showed that all four antifreeze fractions normally present in the serum of P. borchgrevinki are also synthesized by isolated hepatocytes. The two major conclusions from these experiments were that 1) P. brochgrevinki, unlike many northern fishes, does not show thermal acclimation, and 2) environmental factors responsible for modification of peptide antifreeze synthesis in northern fishes do not elicit changes in AFGP synthesis in P. borchgrevinki.

Behavior of RNA and protein synthesis during the acclimatization of the carp. Studies with isolated hepatocytes

1. Carp hepatocytes were isolated by dissociating the liver tissue with collagenase. The procedure yields viable cells with highly preserved ultrastructural and metabolic features. The isolated cells were able to self-aggregated and form tissue. 2. RNA and protein synthesis activity was significantly higher in the carp hepatocytes from summer acclimatized fish compared to the activity present in the cold adapted animals. 3. RNA synthesis assayed in carp hepatocytes suspensions obtained from summer and winter acclimatized fish exhibited a behaviour consistent with an inverse compensation to the cold acclimatization state, being apparently repressed, whereas protein synthesis did not show a compensatory activity.

Turnover of cytochrome C in skeletal muscle of green sunfish (Lepomis cyanellus, R.) during thermal acclimation

The concentration of cytochrome c in the skeletal muscle of the green sunfish (Lepomis cyanellus) increases with decreasing temperature of acclimation: 1.51 +/- 0.09, 1.17 +/- 0.03, and 0.98 +/- 0.07 nanomoles per gram wet weight from muscle of animals acclimated to 5 degrees, 15 degrees, and 25 degrees C, respectively. The roles of synthesis and degradation of cytochrome c during thermal acclimation were investigated by measurement of loss of specific radioactivity from cytochrome c and from total mitochondrial heme protein, and by analysis of the rate of change in concentration of cytochrome c. The radioisotope used was 14C-delta-aminolevulinic acid, a non-reutilizable heme precursor. At 25 degrees C, the half-life of cytochrome c was 7.1 days based on radioactivity measurements and 5.6 days based on change in concentration. Statistical analysis showed no significant difference in half-lives obtained by the two methods. The half-life of total mitochondrial heme protein was determined to be 5.7 days on the basis of radioactivity data, under the same conditions. No significant difference was found between the rate of turnover of the heme protein pool from mitochondria and either measurement for cytochrome c at 25 degrees C. At an acclimation temperature of 5 degrees C, the half-life of cytochrome c from skeletal muscle was 13.7 days based upon changes in concentration. At low acclimation temperature, radioactive label was retained in acid-soluble form by fish for many days, precluding measurement of half-life by this technique. Transfer of fish from 25 degrees to 5 degrees C resulted in a rapid decrease of approximately 40% in rates in synthesis of skeletal muscle cytochrome c, and a concomitant decrease in the degradation rate constant for this molecule of approximately 60%. The disproportionality in temperature-sensitivities of these two processes leads to an approximately 50% net increase in the concentration of cytochrome c during acclimation. In transfer from 5 degrees to 25 degrees C, the converse, rapid readjustments in synthetic and degradative parameters occur, resulting in the observed decrease in cytochrome c content.