Seasonal variations in the immune system of the tench,Tinca tinca (Cyprinidae): proliferative response of lymphocytes induced by mitogens

The proliferation of tench lymphocytes induced by mitogens was studied during the four seasons of the year. Fish were maintained under natural conditions of photoperiod and temperature (mean ± SD: 12±2°C in winter, 22±3°C in spring, 30±3°C in summer and 21±3°C in autumn). Cultures were performed in vitro at 22°C in all seasons and the results were compared. Subsequently, in seasons with extreme water temperatures, cultures in vitro were performed at the same temperature as that of the water (12°C in winter and 30°C in summer) and the results were compared seasonally at the seasonal temperature, i.e. at 22°C in spring, 30°C in summer, 22°C in autumn and 12°C in winter. Phytohemagglutinin, concanavalin A, lipolisaccharide from E. coli and pokeweed mitogen were used as mitogens. Studies performed at 22°C as assay temperature in all seasons showed profound seasonal changes: while in spring, summer and autumn the mitogenic response of lymphocytes to phytohemagglutinin, concanavalin A, lipolisaccharide from E. coli and pokeweed mitogen was very low, during winter the results obtained were significantly higher. However, when the assays were performed at the corresponding seasonal temperature the differences were not as pronounced between the different seasons, and the mitogenic responses of lymphocytes were found to be the lowest during the winter and the highest during the summer with all mitogens used. This fact suggests that immunosuppression occurs in winter and an immunostimulation occurs in summer. However, the higher response found in winter when assaying at 22°C suggests that this property of lymphocytes needs an assay temperature higher than the in vivo temperature in order to observe accurate mitogenic responses.Abbreviations Con A concanavalin A - cpm counts per minute - LPS E. coli lipolisaccharide - MS222 tricainemethane sulphonate - PBS phosphate-buffered saline - PHA phytohemagglutinin - PWM pokeweed mitogen - SI stimulation index     

Difference in blood and water diffusion distance in gill lamellae of diploid and triploid tench Tinca tinca (L.)

Image analysis of sagittal sections of gill lamellae of diploid and triploid tench Tinca tinca revealed the blood and water diffusion distance in diploids (2·07 μm) to be significantly higher than that of their triploid siblings (1·46 μm; P < 0·01). Lamellae of diploids compared to triploids were found to be significantly shorter (105·84 v. 132·11 μm) and thicker (18·47 v. 14·21 μm; all at P < 0·05) than those of their triploid siblings but with similar mean sectional areas (1965·44 v. 1910·86 μm²).     

Autotriploid tench Tinca tinca (L.) larvae obtained by fertilization of eggs previously subjected to postovulatory ageing in vitro and in vivo

Eggs of diploid tench Tinca tinca were half-stripped out and stored for 0 (control batch), 1, 3 and 5 h at mean ± s . d . 17·0 ± 0·4 and 21·9 ± 0·5° C or for 0, 1, 2, 3, 4 and 5 h at 24·0 ± 0·0° C in vitro prior to fertilization. The eggs remaining in vivo in the fish kept at 17·0 ± 0·4 and 21·9 ± 0·5° C were collected and fertilized in the same time intervals. Fertilization rate and larval yield mostly decreased after 3–5 h storage of eggs both in vitro and in vivo and only the diploid larvae were found in all control batches. Triploid larval yields increased to a maximum 5·26% after 5 h in vitro storage at 24·0° C and 1·07 and 1·60% after 3 h in vitro storage at 21·9 and 17·0° C, respectively. Triploid larval yield during in vivo storage at 21·9° C reached a maximum 0·91% after 5 h. As the spontaneous autotriploid larvae arose solely from fertilized eggs previously subjected to postovulatory egg ageing by means of prolongated storage, the autotriploidy was probably caused by failure of extrusion of the second polar body.     

Optimum conditions for the activation of the alternative complement pathway of a cyprinid fish (Tinca tinca L.). Seasonal variations in the titres

The present work describes the existence of a haemolytic activity in the serum of tench, Tinca tinca, against rabbit red blood cells (RRBC) which was identified as belonging to the alternative complement pathway from the following findings: haemolytic activity disappeared when the serum was heated to 45°C for 20 min; 10 mM EDTA, which chelates Ca²⁺ and Mg²⁺, induced a complete loss of haemolysis; Mg²⁺, but not Ca²⁺, was required for the activity, and the use of sheep red blood cells (SRBC), which have a high content of sialic acid, resulted in the serum activity falling to a very low degree of haemolysis. The ACH50 value (units ml^-1 serum) was defined as the reciprocal of the serum dilution necessary to lyse 50% of 4 × 10⁷ RRBC in a buffered medium of normal ionic strength (μ=0·15) containing 10 mM EGTA and optimum concentrations of Mg²⁺. The optimum conditions for the ACH50 assay were: pH 7·2-7-7; reaction temperature, 15°C; concentration of Mg²⁺, 5 mM; and reaction time, 90 min. Under these conditions, the values of ACH50 in spring, summer, autumn and winter for male tench were 69±13, 91±22, 90±36 and 137±41, and for female tench 100±11, 108±13, 82±12 and 145±17. The highest serum activity was found in the winter, suggesting the importance of this pathway during cold periods when the specific immune response is depressed in ectothermic vertebrates.     

Seasonal fluctuations of the mineral concentration of alder (Alnus glutinosa (L.) Gaertn.) from the field

Summary The seasonal fluctuation of N, P, K, Ca, Mg, Fe, Mn, Mo, and Co, in leaves, roots and nodules of 40–50 year oldAlnus glutinosa trees growing at four different locations along the banks of the Tormes river, in the province of Salamanca, was studied. Also, the evolution of the soil organic matter under the trees sampled was evaluated. The data obtained for the various nutrient elements in the three plant parts are statistically treated at the significance levels of 99–95 per cent, and some remarks as to the nutritional status of the European alder in respect to the nutrients and its contribution to soil nutrient-cycling are provided. A positive correlation was found between N–P, N–K, N–Mg, and N–Mo, in leaves, and between N–P, N–K, N–Fe, N–Mn, and N–Mo in root nodules. In roots only, no significance at any level was obtained between N and any of the elements analyzed.     

Survival and changes in growth of juvenile tench (Tinca tinca L.) fed defined diets commonly used to culture non-cyprinid species

The study is an attempt to evaluate the feasibility of intensive tench culture using non‐specific diets as a preliminary step to check the acclimatization of the species under intensive rearing systems. Five‐month‐old juvenile tench were reared in recirculating systems at mean water temperatures of 22°C for 75 days. Fish fed with four different commercial diets (trout starter, trout first feeding, sea‐bass and eel), showed significantly higher final weights than the fish fed either eel or sea‐bass diets. Initial weight for all treatments was 2.3 ± 0.53 g. Final weight for the commercial diet groups was 3.56 ± 0.4 g, compared with the remaining groups that reached 2.09 ± 0.47 g (P < 0.05). Significantly higher survival rates were observed in the eel and sea‐bass groups (84.7 and 51.5%, respectively) than in either of the trout diet groups (38%). Specific growth rates (1.26 vs –0.18) and condition factor (1.26 vs 0.93) were also higher than those fed with salmonid diets (P < 0.05). Results obtained in this study indicate that regardless of the species’ slow growth, when compared with other cyprinids, final growth rates and survival of tench fed exclusively on sea‐bass or eel diets can be considered satisfactory. It must be pointed out that these promising results were obtained at lower temperatures than previous studies of tench in culture systems. The use of belt feeders did not show improvement in growth compared with manually fed fish when trout diets were used.     

Seasonal changes in the utilization and turnover of assimilation products in 8-year-old Scots pine (Pinus sylvestris L.) trees

Summary The present study aimed at a physiological understanding of the seasonal changes of the carbohydrate patterns and levels in the various tissues of 8-year-old Scots pine (Pinus sylvestris L.) trees growing under ambient climatic conditions in the botanical garden at Bayreuth. The photosynthates of selected twig sections were labelled by ¹⁴CO₂ fixation and after chase periods of 1 h up to 8 months, the distribution of radiocarbon in the whole trees was determined and the labelling of identified carbohydrates was compared with the levels of these compounds in the individual tissues. Bud break and sprouting in spring is exclusively supplied by the recent photosynthates of the previous year's needles. During summer assimilates of the old needles were utilized for secondary growth of the axial system while growth of the recent-year's shoots was supported by their own photosynthesis. In autumn, soluble carbohydrates were produced instead of starch, a major part of which in addition to recent photosynthates was utilized for root growth during the cold season. Another part of the autumnal storage material was incorporated into the cell walls of the latest xylem and phloem elements still in winter. A pronounced starch-oligosaccharide interconversion upon frost hardening, and its reversal in spring as has been described for deciduous trees, could not be observed. This was due to maintenance of photosynthetic capability even in the cold season and the replacement of consumed storage material especially in late winter and early spring by new photosynthates.     

Urinary bladder, ionic composition of seminal fluid and urine with characterization of sperm motility in tench (Tinca tinca L.)

A small urinary bladder attached to the seminal duct in caudal part of the abdominal cavity was registered for the first time in dissected males of tench. The urinary bladder wall was of whitish color and the bladder contained 0.5–2 ml of urine. When collected in the experiment, the tench sperm was white‐colored. Spermatozoa density is highly variable due to contamination by urine, and the latter additionally activates spontaneous motility of the spermatozoa. Seminal fluid contains ions such as Na⁺ (18.4 ± 1.3 mm ), K⁺ (1.9 ± 0.6 mm ), Ca²⁺ (0.6 ± 0.2 mm ) and Mg²⁺ (0.5 ± 0.1 mm ), leading to osmolality of 230 ± 82 mOsmol kg^?1 depending on the dilution by urine. Urea was detected in urine samples uncontaminated by sperm with an osmolality of 85 ± 58 mOsmol kg^?1. Urine also contained high concentrations of ions such as Na⁺ (30.9 ± 8.9 mm ), K⁺ (4.3 ± 2.9 mm ), Ca²⁺ (0.9 ± 0.5 mm ) and Mg²⁺ (0.6 ± 0.2 mm ). The spontaneous sperm activation by urine was up to 100%, but could be prevented by collection in an immobilizing solution. Motility was observed for 90–100% spermatozoa just after their transfer to distilled water or in a swimming medium (SM, 30–45 mm KCl) with a velocity of 120–140 μm s^?1. A flagellar beat frequency of 60–70 Hz and forward motility lasted up to 80 s in distilled water, and up to 180 s in SM at room temperature.     

Diet composition and prey preference of tench, Tinca tinca (L.), common bream, Abramis brama (L.), perch, Perca fluviatilis L. and roach, Rutilus rutilus (L.), in two contrasting gravel pit lakes: potential trophic overlap with wildfowl

The abundance of benthic macroinvertebrate taxa and the relative abundance of zooplankton taxa were compared with the diet of bream, tench. perch and roach from two gravel pit lakes during May-July 1986 and 1987. Significant food preferences were demonstrated between species and between lakes. Chironomid pupae dominated the macroinvertebrate diet of perch, roach, ate predominantly either Spirogyra sp. (St Peters Lake) or Daphniu hyalina (Main Lake).
The Main Lake, bream fed largely upon chironomid larvae and the bivalve Sphuerium but in St Peters Lake they positively selected a variety of less abundant benthic invertebrate taxa. Bream switched from benthos to zooplankton in the Main Lake in 1986. Tench ate large numbers of Aselhs and showed positive selection of various macroinvertebrate prey in St Peters but ate D. hjulim in Main Lake. Tropic overlap for chironomids and other macroinvertebrate prey was demonstrated between perch, bream and tench, and potentially with wildfowl which used the gravel pits for breeding and wintering.     

Seasonal variation in the monoterpenes in needles of Picea abies (L.) Karst.

Summary This investigation was conducted to obtain information about the fluctuations in composition and amount of needle monoterpenes during the development of spruce needles. Studies conducted with two Norway spruce clones clearly revealed the existence of fluctuations. In juvenile needles, the amounts of the oxygenated terpenes increase constantly with age during the first 2 months of needle growth. The hydrocarbon terpenes dominate within the first weeks, some of them even showing a very distinct first maximum within the first 3 weeks after bud burst. All terpenes, including the oxygenated ones, have a maximum in June/July, which favours the hypothesis of a substitution of the hydrocarbons later on. There are significant changes even in mature needles of Norway spruce. The terpene level of 1-year-old needles of the clonal trees increased from spring to early summer and then dropped again towards winter. In addition, fluctuations in mature needles were shown for a set of ten wild trees. Needles of the same age class, which emerged in 1986, were sampled 4 times from 1986 to 1988. The needle terpene concentrations of the 1 -year-old needles were considerably lower in spring at the time of bud burst than in autumn. The terpene level of older needles thus seems to be influenced by biosynthetic and catabolic activities.     

Developmental stages and localization of peroxidatic activity in the leucocytes of three teleost species (Cyprinus carpio L.; Tinca tinca L.; Salmo gairdneri Richardson)

Summary The ultrastructural localization of peroxidase (PO) in the leucocytes of three teleosts (Cyprinus carpio L., Tinca tinca L., Salmo gairdneri R.) has been investigated using the 3,3-diaminobenzidine method. In the heterophilic granulocytes the granules show a species specific structure and are PO-positive at pH 7.6. They can be traced back to small granules arising near the Golgi apparatus (GA) in the promyelocyte. They coalesce to form larger granules and gradually change into the mature type. Myelocytes contain small unreactive granules, and these represent a second granule population. Eosinophils contain one PO-positive granule type (at pH 9), and these granules show a varying density during cell maturation.Basophils are present only in the Cyprinid species, and contain unreactive granules originating from precursors displaying a weakly positive reaction at pH 7.6. The active secretory organelles (RER, GA) are PO-negative, except for a weakly positive reaction in the flocculent matrix of the inner G-cisternae.In promonocytes and monocytes the granules are unreactive, but in the macrophages PO-positive staining occurs in a few small to medium sized granules, and in large vacuoles. At least some of these latter are apparently derived from phagolysosomes containing digested erythrocytes. Thrombocytes and lymphocytes are unreactive.The successive development of PO-positive and negative granule populations in the heterophils, and the PO-reactivity of eosinophils and basophils, show some similarities to the corresponding cells in higher vertebrates, but an analogous PO-positive (azurophil) granule type in monocytes seems to be absent.     

Seasonal changes in the oxygen storage capacity and aerobic dive limits of the muskrat (Ondatra zibethicus)

Summary The oxygen storage capacity and partitioning of body oxygen reserves were compared in summer-and winter-acclimatized muskrats (Ondatra zibethicus). Blood volume, blood oxygen capacity, and skeletal muscle myoglobin content were higher in December than in July (P<0.02). Total lung capacity increased only slightly in winter (P>0.05). The oxygen storage capacity of a diving muskrat was calculated at 25.2 ml O₂ STPD · kg^-1 in July, compared to 35.7 ml O₂ STPD · kg^-1 in December. Blood comprised the major storage compartment in both seasons, accounting for 57% and 65% of the total oxygen stores in summer and winter, respectively. Based on available oxygen stores and previous estimates of the cost of diving, the aerobic dive limit (ADL) increased from 40.9 s in July to 57.9 s in December. Concurrent behavioral studies suggested that most voluntary diving by muskrats is aerobic. However, the proportion of dives exceeding the calculated ADL of these animals was shown to vary with the context of the dive. Only 3.5% of all dives initiated by muskrats floating in the water exceeded their estimated ADL. Provision of a dry resting site and access to a submerged food source increased this proportion to 18–61%, depending on the underwater distance that foraging muskrats were required to swim. Serial dives exceeding the estimated ADL were not accompanied by extended postdive recovery periods.Abbreviations ADL acrobic dive limit - Hb hemoglobin - Hct hematocrit - Mb myoglobin - PaO₂ arterial O₂ tension - STPD standard temperature and pressure, dry     

Seasonal and annual variations of phosphorus,calcium, potassium and manganese contents in different cross-sections of Picea abies (L.) Karst. needles and Quercus rubra L leaves exposed to elevated CO2

Norway spruce and red oak trees were planted directly into the soil and enclosed in open-top chambers. For 2 years the trees were exposed to both ambient and elevated CO₂ concentrations (700 mol mol^-1) and during this time variations in nutrient concentrations were studied. CO₂-treated plants had decreases in global leaf concentrations of nitrogen, potassium, calcium and manganese for both species. When different areas of the foliage were analysed however, the response showed much variability between the respective sites and between species. Furthermore the nutrient concentrations changed differently as the plant material aged and this change showed inter-treatment differences. These results show how it may be important to analyse plant material of different ages and at different cell sites when studying nutrient levels.     

Seasonal changes in sea-water tolerance of Arctic charr (Salvelinus alpinus)

Summary Groups of Arctic charr,Salvelinus alpinus, which had been acclimated to water with a salinity of 7 g·l^–1 and natural temperature and photoperiod, were exposed to water with different salinities and temperatures in June, September and February. At a salinity of 15 g·l^–1, plasma osmolality, plasma Na⁺, Cl^–, Mg²⁺ concentrations and the activity of gill Na-K-ATPase were stable, irrespective of temperature and season. In June, the charr were able to regulate blood plasma ionic levels within narrow limits when exposed to a salinity of 34 g·l^–1 (sea water) and a temperature of 8°C. The hypo-osmoregulatory capacity was less, but sufficient if the temperature was only 1°C during the seawater exposure. At the start of the experiment, the gill Na-K-ATPase activity was significantly higher in June than corresponding enzyme activities in September and February. Furthermore, an increase in gill Na-K-ATPase activity during the seawater exposure (8°C) was seen in June. Irrespective of ambient temperature and salinity, no fish died during the June experiments. In September and February, exposure to sea water produced marked increases in plasma osmolality and plasma ion concentrations. There were no changes in gill Na-K-ATPase activity. Consequently, the fish became dehydrated and were moribund after a short period of seawater exposure. Highest mortality was recorded when charr were exposed to winter sea conditions (34 g·l^–1 and 1°C) in February. The results indicate that an increase in daylength induce a hypo-osmoregulatory capacity in the Arctic charr during summer. In fall and winter, however, reduced daylength are accompanied by poor hypo-osmoregulatory capacity. This leads to high mortality as a result of increased electrolyte levels and dehydration.     

Seasonal changes in production and nutrient content ofCynodon dactylon (L.) Pers. subjected to water deficits

Seasonal changes in water relations, production and mineral composition were studied in a sward ofCynodon dactylon (L). Pers. subjected to water deficits during a dry summer, and at recovery in autumn. The experiment was carried out under Mediterranean field conditions. Water deficits during summer reduced total dry matter production by 60%, but in autumn there were no differences between treatments. Compared to well-watered sward, the sward grown under drought showed an increase in potassium, calcium and nitrogen of 55, 10 and 10% respectively. These differences decreased with the arrival of autumn rains. Leaf osmotic potential (Ψ_Π) fell during the dry summer to −2.8 MPa in well-watered plants and to −4.2 MPa in stressed plants. In autumn there were no differences between treatments. Nevertheless, relative water content (RWC) only decreased to 0.86 in droughted plants. In summer potassium contributed to the osmotic adjustment. In contrast, under water deficits a decrease of 71% in sodium and, to a lesser but significant extent decreases in phosphorus, magnesium and chlorine was observed. Nitrogen, phosphorus and sulphur showed low concentrations during summer and increased in autumn.     

The saccus vasculosus of Anguilla anguilla (L.) from larva to adult

Summary The ultrastructure of coronet cells of the saccus vasculosus has been studied in specimens of Anguilla anguilla (L.) at different stages of its life cycle. At all the stages observed coronet cells are composed of a basal and an apical part, the latter bearing globules with primary vesicles. In the larva (a marine form) and in the fully metamorphosed small eel at the time of entry into freshwater the narrow lumen and the vesicles within the apical globules are filled with electron-dense material. In forms in which adaptation to freshwater has occurred, the saccus lumen appears expanded, the apical globules are better developed, and the electron-dense material has disappeared. It is suggested that the two situations observed represent different functional states of the organ, in relation to different conditions of environmental salinity.The authors gratefully acknowledge the contribution of Dr. G. Andreoli, of the University of Parma, who provided the Atlantic larvae for this study.     

The effects of tench (Tinca tinca (L.)) and sticklebacks (Gasterosteus aculeatus L.) on planktonic and benthic communities in mesocosms in a shallow lake

The effects of introducing a zooplanktivorous fish, three-spined stickleback, (Gasterosteus aculeatus) and a benthivorous fish, tench (Tinca tinca) separately and in combination to replicated experimental enclosures with two density levels of white water lily (Nymphaea alba) were studied in Little Mere, UK. Numbers of Daphnia hyalina were high and only slightly diminished at reduced lily densities, probably due to stickleback predation, but there was no consequential effect on phytoplanktonic chlorophyll a concentrations. Tench reduced the numbers of gastropods but not of other macroinvertebrates, and in turn increased the biomass of periphyton growing on artificial substrata within the enclosures. The higher lily density reduced oxygen concentrations and pH values and increased total phosphorus and soluble reactive phosphorus concentrations but otherwise had little effect on water chemistry. There was little interactive effect of the fish species. The results are integrated with those of six other such enclosure experiments carried out in Little Mere since 1992.     

Seasonal variations in polyhydroxysteroids and related glycosides from digestive tissues of the starfish Patiria (=Asterina) pectinifera

Seasonal variations in the concentrations of individual polyhydroxysteroids and related low molecular weight glycosides in pyloric caeca and stomach of the starfish Patiria (=Asterina) pectinifera collected at one location near Vladivostok have been studied. HPLC analysis on the fractions containing these substances showed a fairly constant composition of steroids in digestive tissues of P. pectinifera in spite of small seasonal variations in the relative concentrations of individual compounds.     

Enhancement of superoxide dismutase activity in the leaves of white clover (Trifolium repens L.) in response to polyethylene glycol-induced water stress

Effects of polyethylene glycol (PEG)-induced water stress on the activities of total leaf superoxide dismutase (SOD) and chloroplast SOD (including thylakoid-bound SOD and stroma SOD) are described in white clover (Trifolium repens L.) grown in solution culture from rooted cuttings. Both leaf SOD and chloroplast SOD activities were markedly enhanced with increasing concentration of PEG stress, generating osmotic potentials around the roots 0, −0.5, −1.0, −1.5 MPa. The effects increased with time up to 72 h. Chloroplast Fe-containing SOD represented about 30% of the total leaf SOD activity in the control plants and a significant increase in chloroplast SOD activity was found during the stress period. This accounted for about 35.5–71.1% of the total leaf SOD activity. The proportion of chloroplast SOD in total leaf SOD not only increased with the decreasing of osmotic potential, but also increased with incubation time. Furthermore, the increase in thylakoid-bound SOD activity was much higher than that of stroma SOD in chloroplast of plants under water stress. The enhanced chloroplastic SOD activity, especially thylakoid-bound SOD activity, demonstrated in Trifolium repens suggests that Fe-SOD located in chloroplasts play a more important role than cytosolic Cu/Zn-containing SODs in scavenging O₂ ⁻.     

Reproductive capacity of bacteroids in nodules of Trifolium repens L. and Glycine max (L.) Merr.

Reproductive growth of intracellular bacteria from isolated protoplasts in nodules of clover and soybean was directly investigated using a microchamber with visual and video recording. Differentiated bacteriods from clover nodules uniformly failed to reproduce. Such growth as occurred came from undifferentiated rhizobia from within the protoplast or extracellularly in the nodule. Plating investigation gave results in agreement with this conclusion. Osmoprotective media failed to secure the reproduction of differentiated clover bacteroids. Reproductive growth of bacteroids from protoplasts and crushed nodules of soybean was regularly observed in the microchamber and determined as proportionate colony-forming ability (CFA) on laboratory media. The CFA markedly increased with age of nodule and with the addition of nodule or root extract. The promoting effect of such extracts was reduced after heating for 60 min at 100°C, and lost completely after 20 min at 121°C. High osmolarity in the suspending and culture media was detrimental to bacteroid recovery.Abbreviations BMM Bergersen's modified medium - B^+m BMM with additional mannitol - CDB Chlamydomonas dilution buffer - PDB protoplast dilution buffer - PDB PDB without mannitol or sorbitol - RMM Rhizobium minimal medium - R^+m RMM with mannitol instead of sucrose - YMA, YMB yeast mannitol agar and broth, respectively. For details, see Materials and methods