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1.
Glass eels reacted chemotactically towards five non-protein constitutional amino acids, D-glutamine, D-asparagine, D-glutamic acid, D-alanine and β -alanine, dissolved in fresh water or salt water, with behavioural thresholds ranging from 10-9 M for the most effective (D- and β ;-alanine) to 10-7 M for the other three. With the exception of D-asparagine in fresh water and D-alanine at concentrations ≥10-7 M, these amino acids were strong attractants. The results are compared with previous findings on the respective L-isomers. The non-protein amino acids may influence behaviour in the search for food and the recognition of conspecifics.  相似文献   

2.
No significant differences were noted between responses of rainbow trout Oncorhynchus mykiss facial and glossopharyngeal nerves to 15 amino acids. Nine of these amino acids tested at 10−2 M were stimulatory, whereas only two tested at 10−3 M were effective gustatory stimuli. For both nerve systems, ≤10−3 M L-proline was the most stimulatory amino acid, with an estimated threshold of 10−7 M; however, L-α-amino-β-guanidino-propionic acid (estimated threshold of 3×10−3 M), was the most potent compound at 10−2 M. These results indicate that the same amino acids activate taste buds innervated by facial and glossopharyngeal nerves, respectively, and suggest that the same amino acids can be important in chemosensory feeding behaviour in the rainbow trout.  相似文献   

3.
The behaviour of juvenile Arctic charr, Salvelinus alpinus (L.) , to an abrupt concentration step of L-amino acids, L-alanine and ammonium chloride was studied by fluviarium technique. The emission rates of these substances were studied. Juvenile Arctic charr emit 8.0 × 10−4 mol total ammonia-N kg−1 h−1 and 3.3 × I0−5 mol amino acids kg−1 h−1. In behaviour tests the charr avoided 5.6x 10−6and 5.6 × 10−7 M ammonium chloride. The 17 L-amino acid mixture, ranked as observed in the analysis of emission, was avoided at 4.6 × 10−7 M, while 100 times dilution of this value gave neither avoidance nor attraction. The charr avoided L-alanine tested alone at the concentration of 4.6 × 10 −7 M. Anosmic charr showed neither avoidance nor attraction to the mixture of 17 amino acids tested at 4.6 × 10−7 M. The results indicate that ammonia as well as emitted amino acids are not responsible for the olfactory mediated attraction to conspecific odour shown earlier in Arctic charr. On the contrary, these substances may have a negative effect by reducing the strength of attraction.  相似文献   

4.
The detection of threshold concentrations and relative stimulatory effectiveness (RSE) for 19 amino acids were studied by olfactory bulbar electroencephalogram (EEG) in the algivorous rabbitfish. The threshold concentrations for 19 amino acids ranged from 10−10 to 10−5 M. l -Alanine was the most effective amino acid, and the threshold concentration was estimated to be from 10−10 to 10−9M. These results were compared with the olfactory response in herbivorous and carnivorous fishes previously reported. The comparison of RSE for rabbitfish with those for other fishes showed correlation coefficients ranging from r = 0.97 to r = 0.50, but high similarities did not correspond with difference in feeding habits for herbivores and carnivores. The role of amino acids in fish chemosensory behaviour and the olfactory response of the rabbitfish was compared with the gustatory response reported previously. It was found that l -serine was the most potent stimulant in both chemoreceptors, l -proline and l -glutaminic acid were the most potent gustatory stimulants, and l -alanine, l -glutamine, l -arginine and l -lysine were the most potent olfactory stimulants.  相似文献   

5.
Olfactory sensitivity of juvenile (0 year) Atlantic cod Gadus morhua to 20 L‐amino acids was studied by recording electroencephalograms (EEG) from the olfactory bulb. Leucine, methionine, asparagine, glutamine, alanine and threonine were highly stimulatory; proline, phenylalanine, aspartic acid and tryptophan were the least stimulatory. Threshold concentrations determined for four amino acids were 10−8 M for alanine, 10−7 M for arginine and leucine and 10−6 M for glutamic acid.  相似文献   

6.
The olfactory sensitivity of a herbivore, the grass carp, Ctenopharyngodon idella , to ten amino acids was investigated using electrophysiological recording techniques. Underwater electroolfactogram recordings increased exponentially with logarithmic increases of stimulus concentration from threshold to 1 × 10−3 m. Calculated detection thresholds ranged from 1 × 10−7.15 m to 1 × 10−8.7 M and are similar to those previously reported for carnivorous fish species. The relative stimulatory efficacy (RSE) of the ten amino acids determined at 1 × 10−4 M revealed five groups of stimuli, with cysteine the most stimulatory and proline the least. Measures of amino acid RSE did not differ significantly from those of previously studied carnivores, except for arginine. Grass carp showed strong responses to this compound, whereas it has produced only limited responses in carnivores. Differences in the responsiveness of herbivores and carnivores were not observed, suggesting that feeding niche segregation is probably not facilitated by differential olfactory sensitivities to feeding stimuli.  相似文献   

7.
A new behavioural bioassay for determining the locomotor response by fish to chemical cues is described. The assay combines a behavioural trough, capable of delivering up to 10 discrete plumes of treated water, together with a digital method for quantifying the movements of single fish. Sample responses of two whitefish, Coregonus clupeaformis , one to an attractant (a food extract) and one to a repellant (quinine monohydrochloride), are provided. Their locomotor responses are analyzed in terms of such parameters as total distance travelled, average velocity, number of turns, average excursion distance, and the number of times specific boundaries are crossed. The assay's sensitivity is demonstrated through concentration-response curves by Arctic char, Salvelinus alpinus , to the bile acid, taurocholic acid, and the amino acids, L-serine and L-alanine. Behavioural response threshold concentrations for these three substances were estimated to be 10−15, 10−n, and 10−9 m, respectively.  相似文献   

8.
This study tested the hypotheses, using glass eels of longfin eels Anguilla dieffenbachii and shortfin eels Anguilla australis migrating into fresh waters, (1) that both species prefer water from their river of collection to well water, (2) that shortfin eels prefer lowland, pastoral stream water to mainstem river water, (3) that longfin eels are attracted to both waters but do not prefer one to the other, and (4) both prefer water scented with geosmin, a widely occurring metabolite of bacteria and algae, to well water. Glass eels of both species from a river on the west coast of South Island, New Zealand, and shortfin glass eels from an east coast river significantly preferred water from their river of capture to well water. Two to three times as many eels chose their own river water as chose well water. Longfin eels were rare in the east coast river. Shortfin glass eels from the two rivers chose lowland stream water to mainstem river water about two to one in three experiments with different pairs of waters to which they had no prior exposure. Longfin glass eels significantly chose mainstem river water over lowland water in one pair but showed no preference when presented with a different pair. Reactions to solutions of geosmin at concentrations of 10–5-10–7 mg 1–1 were inconclusive, with geosmin being preferred significantly, by shortfin eels, in only one experiment. The interspecific differences in discrimination of natural waters demonstrated in this study, with shortfin eels preferring lowland waters and longfin eels more indifferent to water types, are in broad agreement with both the distribution of adults and observations on their habitat preferences.  相似文献   

9.
The apple rootstock A2 can be readily propagated in vitro both in the juvenile and in the adult growth phase. Shoots were produced by meristem tip culture from the apple rootstock A2 in different growth phases. The influence of growth phases and different concentrations of PG and IBA was investigated as to rooting percentage, survival percentage, number of roots per rooted shoot, root length, shoot length and formation of callus. IBA at 15 μ M without PG gave a significantly lower rooting percentage than 5 and 10 μ M IBA. PG together with IBA stimulated rooting, the optimum concentrations of PG being, however, not the same for the different growth phases. For the adult growth phase, 10−4 M PG promoted rooting, whereas 10−3 M PG markedly inhibited rooting. In the juvenile growth phases, both 10−4 and 10−3 M PG stimulated rooting. PG at 10−4 M also increased the number of roots. The longest roots were obtained at 10−3 M PG and 5 μ M IBA. PG at 10−3 M reduced callus formation at all IBA concentrations used. Neither shoot length nor root length influenced the survival percentage.  相似文献   

10.
Abstract It has been hypothesized that vegetation in certain ecosystems inhibits nitrification in soil by producing phenolic compounds that inhibit oxidation of ammonia by nitrifying microorganisms. This hypothesis is based largely on a report that very low concentrations (10−6 M–10−8 M) of several phenolic acids (notably ferulic acid) completely inhibited NO2 production in an aqueous suspension of soil treated with (NH4)2SO4 and a nutrient solution suitable for growth of Nitrosomonas and other autotrophic nitrifying microorganisms. To evaluate this hypothesis, we determined the effects of three ohenolic acids (ferulic acid, caffeic acid, and p -coumaric on nitrite production by representatives of three genera of terrestrial autotrophic nitrifying microorganisms ( Nitrosospira, Nitrosomonas , or Nitrosolubos ) grown on a defined medium containing NH4+. We found that nitrite production by the Nitrososspira was not inhibited by ferulic acid, caffeic acid, or p -coumaric acid at concentrations of 10−6 or 10−5 M and was only slightly inhibited when these acids were at a concentration of 10−4 M. We also found that ferulic acid did not markedly inhibit nitrite production by the three genera of nitrifying microorganisms studied, even when its concentration was as high as 10−3 M. These observations invalidate the hypothesis tested because the phenolic acids studied did not significantly retard ammonia oxidation by autotrophic microorganisms even when their concentration in cultures of these microorganisms greatly exceeded their concentrations in soils.  相似文献   

11.
Otolith Sr:Ca ratios were examined to evaluate the contribution of the stocked eel Anguilla anguilla elvers, which have been stocked in Lithuanian waters and mixed with naturally recruited eels for several decades, to the native eel population. Stocked eels were identified by the freshwater signature (Sr:Ca ratios <2·24 × 10−3) on the otolith after the glass eel stage. Naturally recruited eels, that had migrated through the North and Baltic Seas, were characterized by an extended seawater and brackish-water signature (Sr:Ca ratios >3·23 × 10−3) after the glass eel stage. Of 108 eels analysed, 21 eels had otolith Sr:Ca ratio profiles consistent with stocking while 87 showed patterns of natural recruitment. The ages of naturally recruited eels arriving in Lithuanian fresh waters varied from 1 to 10 years, with a mean ±  s.d . age of 5·2 ± 2·1 years. Eels from the inland Lake Baluošai were all freshwater residents of stocked origin. Stocked eels, however, accounted for only 20% of the eels from the Curonian Lagoon and 2% of eels sampled in Baltic coastal waters. This finding does not support the hypothesis that the eel fishery in the Curonian Lagoon depends mostly on stocking.  相似文献   

12.
In the present study, glass eels Anguilla anguilla in the Minho River estuary (41·5° N, 8·5° W) decreased in size (standard length, L S and mass, M ) from the beginning (autumn) to the end of the sampling season (summer). On the other hand elvers increased in L S and M from spring to summer and were significantly larger than glass eels in paired comparisons. Branchial Na+/K+-ATPase and vacuolar (V-type) proton ATPase ( in vitro activities), two important ion transporting pumps, did not show significant seasonal changes in either glass eels or elvers although in glass eels Na+/K+-ATPase (activity) expression was significantly higher than in elvers. In a single month comparison Na+/K+-ATPase branchial mRNA expression was also higher in glass eels as was the protein level expression of both Na+/K+-ATPase and NKCC (Na+:K+:2Cl co-transporter). Immunofluorescence microscopy indicated apical CFTR Cl channel labelling in Na+/K+-ATPase positive chloride cell in glass eels which was absent in elvers. Whole body sodium concentration and percentage water did not show significant seasonal differences in either glass eels or elvers although there were significant differences between these two groups during some months.  相似文献   

13.
Diazinon, an organophosphate pesticide, had a sublethal effect on the olfactory system of mature male Atlantic salmon parr. The olfactory responses of the parr to prostaglandin F2a (PGF2a) were studied after exposure of the epithelium to different concentrations of Diazinon in water. Electrophysiological recordings from the epithelium indicated that the responses to this prostaglandin were significantly reduced at nominal concentrations as low as 1.0μg l−1 and the threshold of detection was reduced 10-fold at 2.0 μg 1−1 . Mature male salmon parr exposed for a period of 120 h to Diazinon (nominal concentrations 0.3, 0.8, 1.7, 2.7, 5.6, 13, 28 and 45 μg 1 −1) also had significantly reduced levels of the reproductive steroids, 17,20β-dihydroxy-4-pregnen-3-one, testosterone and gonadotrophin II in the blood plasma after priming with ovulated female salmon urine. Both prostaglandin F2a and ovulated female urine are known to have important roles in synchronizing reproductive physiology and behaviour in salmonids as well as other fish species. The results are therefore discussed in relation to the possible sublethal effects of Diazinon on reproduction in the Atlantic salmon and possible effects on populations of salmonids.  相似文献   

14.
Resistance to cadmium by pretreated rainbow trout alevins   总被引:2,自引:0,他引:2  
A toxicity test with cadmium concentrations ranging from 0·1 to 100·0 mg Cd 1−1 was used to assess the effect of cadmium pretreatment on rainbow trout ( Salmo gairdneri Richardson) alevins. The median period of survival for fish pretreated at 0·01 mg Cd 1−1 was found to be increased at test concentrations up to 10mg Cd 1−1 compared with alevins pretreated with dilution water. However, at concentrations above 10mg Cd 1−1 pretreatment at 0·01 mg Cd 1−1 reduced the median period of survival.  相似文献   

15.
Age and total length ( L T) data from a 11 year monitoring of the Anguilla anguilla eel population of the Camargue lagoons (Rhône delta, southern France) were collected for glass, yellow and silver eels. Three distinct models were calibrated to describe the growth process of undifferentiated eels, females and males, respectively. Uncertainty of parameter estimates was evaluated by bootstrapping. Females were characterized by larger asymptotic body size ( L T) than males (580 ± 50 v . 388 ± 13 mm) and faster growth, whilst the Brody growth coefficient was larger for males than for females (means ±  s . d . 3·00 10−3 ± 1·68 10−3 v . 1·73 10−3 ± 0·50 10−3). Sexual differentiation was estimated to begin at 204 ± 38 mm mean ±  s . d ., i.e . at the end of the second year in the lagoons, well before the L T at which macroscopic differentiation became possible ( c . 300 mm). Males probably leave the lagoon or die (due to either natural or fishing mortality) within the first 3 years, whilst females can remain up to 5 years. Sexual differentiation and maturation have a major role in shaping the L T structure of the population. The L T and mass ( M ) data were fitted by allometric curves     . The calibration of distinct curves for data from different years indicated that the allometric coefficient a was subject to wider interannual fluctuations than the allometric exponent b . A negative correlation linked the average L T and the allometric exponent ( r  = −0·58, P  < 0·01).  相似文献   

16.
The possibility to induce nitrate reductase (NR; EC 1.6.6.2) in needles of Scots pine ( Pinus sylvestris L.) seedlings was studied. The NR activity was measured by an in vivo assay. Although increased NR activities were found in the roots after application of NO3, no such increase could be detected in the needles. Detached seedlings placed in NO3 solution showed increasing NR activities with increasing NO3 concentrations. Exposure of seedlings to NOx (70–80 ppb NO2 and 8–12ppb NO) resulted in an increase of the NR activity from 10–20 nmol NO2 (g fresh weight)−1 h−1 to about 400 nmol NO2 (g fresh weight)−1 h−1. This level was reached after 2–4 days of exposure, thereafter the NR activity decreased to about 200 nmol NO2 (g fresh weight)−1 h−1. Analyses of free amino acids showed low concentrations of arginine and glutamine in NOx-fumigated seedlings compared to corresponding controls.  相似文献   

17.
The survival of Atlantic salmon smolts on exposure to constant concentrations of ammonia has been measured under laboratory conditions. At concentrations of dissolved oxygen close to the air-saturation value, the 24-h LC50 of un-ionised ammonia is 0.15 mg NH31−1 in fresh water (hardness 264 mg 1−1 as CaCO3) and 0.3 mg NH31−1 in 30% sea water; at concentrations of dissolved oxygen of 3.5 mg 1−1 in fresh water and 3.1 mg 1−1 in 30% sea water, the 24-h LC50 is 0.09 mg NH3 1−1 and 0.12 mg NH3 1−1 respectively; for fish acclimated for 1 day to a concentration of ammonia close to the 24-h median for un-acclimated fish, the median is increased between 38 and 79%, depending on test conditions.  相似文献   

18.
Abstract: [3H]Strychnine specifically binds to membrane fractions isolated from rat retinae. The binding is saturable, with an apparent dissociation constant, K D, of 14.3 × 10−9 M and 205 fmol bound/mg protein. Specific binding is time-dependent and proportional to protein concentration. Glycine and taurine are equally potent inhibitors of [3H]strychnine binding ( K i= 4 × 10−5 M); no other amino acids endogenously present in the retina inhibited [3H]strychnine binding.  相似文献   

19.
Abstract: Protein synthesis was measured using a cell-free system obtained from subcortical rat brain tissue. The concentrations of Mg2+ and K+ and the amount of tissue, during both the preparation and the final assay, were critical to the incorporation of amino acids as expressed per milligram protein. Even under optimal conditions mainly elongation of growing peptide chains was measured. Behaviorally active fragments of ACTH modulated the activity of the system in a biphasic manner; i.e., at a low concentration (10−8 M) of ACTH a stimulation of between 10 and 70% was found; a high concentration (10−4 M) was inhibitory (50 to 70%). Structure-activity studies revealed that the stimulatory effect was confined to the N-terminus of the peptide (1–24), whereas the C-terminal sequence was responsible for the inhibition. The stimulation by ACTH1–24 was dependent on Ca2+ and Mg2+. Cyclic AMP (10−5 M) stimulated the amino acid incorporation too. When a similar cell-free extract was prepared from brain tissue of hypophysectomized rats, the lower in vivo protein synthesis in these animals was preserved in the present cell-free system. The data are discussed in terms of a possible direct intracellular effect of ACTH on brain protein synthesis.  相似文献   

20.
Protoplast fusion induced by polyethylene glycol and Ca2+, was performed between auxotrophic mutants of pectinolytic fungi Aspergillus sp. CH-Y-1043 (A13) ade and Aspergillus flavipes ATCC-16795 (F7) lys . Prototrophic colonies were developed on minimal medium with a fusion frequency of 1·0×10−2. The reversion frequency of the mutation in spores and protoplasts was low and ranged from 2·0 to 4·0×10−7. Four prototrophic hybrids (HH, HE, HF and HJ) exhibited enhanced production of endo-pectinase and pectin-lyase. The highest production was observed in HJ ; maximum activities were 150 and 160% respectively, whereas the exo-pectinase production was similar to the wild-type strain Aspergillus sp. CH-Y-1043. Hybrid HJ showed the greatest growth ; nevertheless, specific endo-pectinase and pectin-lyase activities were higher in all hybrids than those produced by the wild-type strains.  相似文献   

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