Seasonal changes in the biochemical composition of the freshwater murrel,Ophicephalus punctatus Bloch

Summary Seasonal variations in various biochemical constituents in the tissues of Ophicephalus punctatus showed that. the fat content in the muscle was highest during November–January and lowest during June–October. Liver contained more fat than the muscle and its seasonal cycle was marked by two well defined peaks. Changes in the ovarian fat were also well defined seasonally. The moisture content in all the tissues varied inversely with the fat. Protein values in different tissues did not show as much fluctuations as fat. In muscle, protein remained high throughout the year except in January. In liver and gonads very low protein values were recorded during the winter months. Seasonal changes in the ash content were not very well marked in any of the three tissues.The seasonal variations in all the biochemical constituents seem related to the feeding intensity of the fish and the maturation of its gonads. Maximum and minimum values of fat fell in accordance with the high and low food intake. In the pre-spawning phase, more fat was stored in the muscle at first but subsequently the fat was mobilized in the liver and finally in the gonads. Peak ripeness was associated with an accumulation of greater protein and fat in the gonads (ovaries). During the spawning months the various constituents were depleted and the post-spawning phase of the fish was marked by minimal values of most of the biochemical constituents, excepting moisture and ash.     

Changes in the biochemical composition of two common cat-fishes (Wallagonia attu Bloch and Mystus seenghala Sykes) in relation to length

Summary Biochemical composition of W. attu and M. seenghala undergo marked changes in relation to length. Fat, protein and ash show an initial fall with length followed by a rise in very large fishes. Moisture showed a negative relationship with fat and protein. Changes in calcium and phosphorus were similar to that of ash. A decrease in calorific values of fat, protein and carbohydrate and in the total calorific values was found associated with length upto a certain size but this was not so in very large fishes. The cycles of different constituents were compared with those of other fishes studied earlier.     

Seasonal correlative changes between sex steroids and lipid levels in the freshwater female catfish, Heteropneustes fossilis (Bloch)

Circannual variation in plasma levels of testosterone (T), oestradiol-17β(E₂) and 17α-hydroxy-progesterone (17α-OHPg) were measured in female, Heteropneustes fossilis . T and E2 levels increased during the preparatory phase, reached their peak in the early prespawning phase and fell during the late prespawning phase to reach their lowest levels post-spawning. 17a-OHPg was detected from the late preparatory to the late spawning phase showing its peak during the early spawning phase. The levels of free fatty acids (FFA), monoglycerides (MG), diglycerides (DG), triglycerides (TG), phospholipids (PL), free cholesterol (CF)and esterified cholesterol (CE) were estimated in liver, plasma and ovaries. The preparatory phase showed hepatic lipogenic activity while during the prespawning phase TG lipolysis was increased by FFA. Ovarian CF was depleted by enhancing plasma E, levels during the prespawning phase. The gonadosomatic index reached its peak during spawning.     

Seasonal changes in flesh weight and biochemical composition of mussels (Mytilus edulis L.) in the Conwy Estuary,North Wales

Sublittoral Mytilus edulis L. from natural mussel beds of the Conwy Estuary fishery exhibited an annual cycle of dry flesh weight, biochemical composition, and caloric value during 1971–1974.Mean percentage values of the main components of dry flesh, with seasonal extremes in parentheses, were: protein 58.7 (46.4–73.1), carbohydrates 22.5 (4.1–36.7), lipids 7.0 (3.9–9.6), and ash 11.8 (8.8–17.2). The mean caloric values of dry flesh were 5.57 kcal/g ash-free and 4.92 kcal/g ashinclusive.Individual dry flesh weight was highest in summer and autumn, when protein and carbohydrate were maximal, and decreased through the winter to a post-spawning minimum in spring. Weight loss in winter resulted from rapid utilization of carbohydrate (glycogen) reserves and a depletion of both protein and lipid content. It is considered likely that mussels were then stressed by food shortage at the time when metabolic demands, due to gametogenesis, were highest.During the six main fishing months, October to March, the average weight of dry flesh fell by 30–50 % and caloric content by 35–45 %. The likelihood of similar losses in cultivated mussel stocks is indicated and the need for comparable information in fishery management is emphasized. The extent to which predators compensate for these seasonal changes in prey quality also requires examination.     

Seasonal changes in the hypothalamo-hypophyseal-ovarian system in the catfish,Heteropneustes fossilis (Bloch)*

The annual reproductive cycle of the catfish, H. fossilis (Bloch) is divided into the preparatory period (February-April), the prespawning period (May-June), the spawning period (July-August) and the postspawning period (September-January). During the early postspawning period (September-November), the hypothalamo-hypophyseal-ovarian system shows a gradual regression. In January, the hypothalamic nuclei, the pars magnocellularis (PMC), the pars parvocellularis (PPC) of the nucleus preopticus (NPO), and the nucleus lateralis tuberis (NLT) show renewed activity, as shown by a significant increase in their nuclear diameters and an accumulation of neurosecretory material (NSM) in their cell bodies. The hypophysis and the ovary remain quiescent. During the preparatory period, all the hypothalamic neurons studied indicate decreased activity but simultaneously show an accumulation of NSM in their cell bodies. The number of granulated basophils in the proximal pars distalis (PPD) of the hypophysis remains low but ovarian weights increase, presumably due to the multiplication of oogonia. In the prespawning period, there is a marked accumulation of NSM in the cell bodies of the hypothalamic neurons and at the same time the number of granulated basophils in the PPD of the hypophysis dramatically increases with concomitant increase in vitellogenic activity in the ovary. During the spawning period, the hypothalamic neurons continue to store NSM in their cell bodies and simultaneously there is a tremendous increase in the number of granulated basophils in the PPD of the hypophysis and the ovary has a large proportion of yolky primary oocytes. Spawning is associated with a significant degranulation of the granulated basophils in the PPD of the hypophysis. The significance of the results is discussed in relation to the environmental and hormonal regulation of seasonal ovarian activity.     

Seasonal variations of calcium and phosphorus in the juveniles of freshwater murrel,Ophicephalus punctatus Bloch

Summary In young O. punctatus seasonal variations in calcium and phosphorus showed a direct correlation. Both of these minerals showed a bimodal cycle. High values occurred during pre- and post-monsoon months and low values during winter and monsoon months. These changes seem to be related to the feeding intensity and growth of the fish.     

Differential C-heterochromatin distribution in two species of freshwater fish, Anabas testudineus (Bloch.) and Puntius sarana (Hamilton.)

Anabas testudineus (2n = 46) had the more conserved pattern of its C-heterochromatin distributed mainly in the centromeric region, whereas Puntius sarana (2n = 50) exhibited a rather unorthodox pattern, many chromosomes showing interstitial, some telomeric and a few chromosomes showing centromeric C-band localization. Further, lateral asymmetry in distribution of heterochromatin was also noted in two pairs of chromosomes in P. sarana. The possible implications of the differential distribution noted in these two species has been discussed.     

Seasonal changes in the corpuscles of Stannius and the gonads of the catfish, Heteropneustes fossilis (Bloch).

The seasonal changes in the corpuscles of Stannius (CS) and the gonads of the catfish, Heteropneustes fossilis were studied. The annual sex cycle of the fish has been divided into 4 phases on the basis of the variations in the gonosomatic index and histocytological features displayed by the testes and ovaries. There is a rise in the percentage of aldehyde fuchsin (AF)-positive cells in the CS and an increase in the nuclear diameter, at the beginning of preparatory period (February). In the prespawning period (May--June) the AF-positive cells undergo degranulation. A slight regranulation and rise in the percentage of AF-positive cells occurs during early spawing period (July). During the postspawning phase (September--January) the corpuscles remain predominated by AF-negative cells and show histolytical changes; the nuclear indices are reduced. In view of the concomitant changes occurring in the CS and the gonads the possibility of some direct or indirect relationship between the two has been discussed, although it is difficult to ascertain whether the changes in the corpuscles are cause or consequence of the gonadal cycle.     

Mizelleus chauhani, n. sp., a branchial parasite of Wallago attu (Bloch)

The authors describe a new species of the genus Mizelleus Jain, 1957. Its characteristic features include the number of head organs, the presence of pharyngeal glands, the shape of the copulatory complex, the structure of the egg and the shape of the dorsal transverse bar, the ventral hamuli and the ventral transverse bar.     

Modulatory effect of copper on nonenzymatic antioxidants in freshwater fish Channa punctatus (Bloch.)

Effect of the low level of copper exposure on nonenzymatic antioxidants was studied in a freshwater fish Channa punctatus (Bloch.). Fish were exposed to cupric chloride at the concentration of 10 ppb for 4 wk (28 d) in a static culture condition. Copper significantly (p < 0.001) increased the serum ceruloplasmin level and total iron-binding capacity. A significant (p < 0.05) increase in reduced glutathione level was recorded in all of the tissues. With regard to nonprotein thiols, copper decreased their level in the liver, but increased it in the gill. The protein-bound thiols remained unaltered except for an increase in the liver. Metallothionein (MT) induction was observed in liver only. Copper exposure had no significant effect on the ascorbic acid level and induced no lipid peroxidation over control values. It is suggested that by modulating the ceruloplasmin level, copper indirectly protects the fish, as it facilitates conversion of pro-oxidant iron to nonoxidant iron. It also induces an array of antioxidants that may be beneficial to fish in the case of oxidative stress resulting from chemical pollutants.     

Anatomical and biochemical changes in the composition of developing seed coats of annatto (Bixa orellana L.)

Seeds of Bixa orellana (L.) have a sclerified palisade cell layer, which constitutes a natural barrier to water uptake. In fact, newly fully developed B. orellana seeds are highly impermeable to water and thereby dormant. The purpose of this work is to investigate, from a developmental point of view, the histochemical and physical changes in the cell walls of the seed coat that are associated with the water impermeability. Seed coat samples were analyzed by histochemical and polarization microscopy techniques, as well as by fractionation/HPAEC-PAD. For histochemical analysis the tissue samples were fixed, dehydrated, embedded in paraffin and the slides were dewaxed and tested with appropriate stains for different cell wall components. Throughout the development of B. orellana seeds, there was a gradual thickening of the seed coat at the palisade region. This thickening was due to the deposition of cellulose and hemicelluloses in the palisade layer cell walls, which resulted in a highly water impermeable seed coat. The carbohydrate composition of the cell walls changed dramatically at the late developmental stages due to the intense deposition of hemicelluloses. Hemicelluloses were mainly deposited in the outer region of the palisade layer cell walls and altered the birefringent pattern of the walls. Xylans were by far the most abundant hemicellulosic component of the cell walls. Deposition of cellulose and hemicelluloses, especially xylans, could be responsible for the impermeability to water observed in fully developed B. orellana seeds.     

Seasonal variation in the filament morphology of the freshwater diatom Melosiragranulata(Ehrenb.) Ralfs

SUMMARY 1, The seasonal changes in filament dimensions and the occurrence of separation valves in a population of Melosira granulata (Ehrenb.) Ralfs were investigated in a eutrophic lake in southern England. Experiments were carried out in culture to study the effects of various environmental factors on the diatom's morphology.
2. Major blooms of M. granulata occurred from September to October, coinciding with an increase in mean filament length brought about by the high growth rate of the diatom. This increase was controlled by a reduction in the frequency of separation valve production. A similar increase in filament length occurred in rapidly growing cultures.
3. The population was lost from the epilimnion when thermal stratification occurred. Immediately prior to this the population consisted of short filaments.
4. The mean filament length was greatest during occasional summer blooms and was again controlled by a reduction in the frequency of separation valve production. This appeared to be a response to the reduced nutrient concentration in the lake. This is supported by similar morphological changes in low nutrient cultures.
5. Increases in the filament length of the diatom were accompanied by increases in the diatom's sinking velocity. The length increase thus ensured its rapid return to the sediment, after summer growth periods, where the cells could be replenished with nutrients.