Growth of a floating aquatic weed,Salvinia under standard conditions

1. Growth of the floating aquatic weed, Salvinia, in sterile culture was exponential for at least 2 weeks under standardized conditions.
2. Increase in light intensity or in CO₂ resulted in increases in growth rate, but did not extend the exponential period of growth.
3. This aquatic plant, like many others, discriminates against calcium relative to strontium.
4. In culture Salvinia exhibited luxury consumption of N and P.
5. Because of high C/N ratios, Salvinia may not be a favorable source of animal food, but might be useful in nutrient removal schemes.
6. In sterile culture, S. molesta produced fewer leaves than S. minima, but maintained a significant increase in leaf area and dry weight. This may be correlated with the ability of the first species to rapidly spread over tropical waterways.

     

Uptake of radionuclides by some aquatic macrophytes of Ismailia Canal,Egypt

1. Uptake of the radionuclides Co-60, Cs-134, Sr-89 and P-32 by different aquatic plants present in Ismailia Canal was found to increase at increasing initial concentrations of the radionuclides in the water.
2. Maximum uptake was reached by most of the aquatic plants after different periods of contamination, ranging from 1 to 4 days.
3. Ceratophyllum was found to be the most favourable biological indicator for strontium radioisotopes in concentrations ranging from 0.5 to 10 µCi/1 and for contamination periods up to 16 days.
4. Elodea was found to serve as a biological indicator for either strontium or phosphorus radioisotopes for limited contamination periods of 2 to 16 days for Sr and to 2 days for P isotopes.
5. Potamogeton was also found to serve as a biological indicator for limited contamination periods for strontium, phosphorus and cesium radioisotopes: 0 to 2 days for Sr, 2 to 16 days for P. and 0 to 2 days for Cs isotopes.

     

A study on the rate of water transport of the clam katelysia opima in relation to environmental conditions

1. The neutral red technique was employed to study the rate of filtration in Katelysia opima.
2. The weight specific water filtration was found to be greater for younger clams compared to the older ones.
3. The rate of water filtration increased with decreasing salinity.
4. Water filtration was found to increase as temperature increased, reaching a maximum at 35°C. but then sharply decreasing at 39°C.
5. Light had no significant effect on the rate of filtration.
6. Suspended matter was found to affect the rate of water filtration.
7. The rate of filtration was low at high pH and high in low pH.
8. The rate of water filtration was found to be faster during high tide than during low tide.
9. The presence of the parasitic crab, Pennotheris sp., in the mantle cavity of clams had a marked effect on the particle filtration.
10. Accidental cut of the siphon tips had no effect on the rate of filtration.

     

Seasonal variations in biochemical constituents of the clam,Paphia laterisulca

1. The total protein, fat and glycogen contents were estimated from the edible clam, P. laterisulca. Seasonal variations in these constituents along with the water content were studied.
2. The gonad index in P. laterisulca was found to increase during the ripe condition and in winter (December–January) and decrease on spawning.
3. A relatively high water content was obtained during monsoon (June to September). This might be due to the loss of salts and gain of water in low salinities.
4. Protein content varied with the reproductive cycle of the clam. The level reached its peak in the mature stage and declined on spawning. Immature clams showed less protein content than gravid ones.
5. Lipid content started to increase as the gametogenesis commenced, reached its peak in fully mature condition (August) and sharply declined due to the shedding of gametes during spawning.
6. Glycogen content was high during the period of active gameto-genesis (May–June). A sharp decrease took place when the clams were fully ripe (July). The glycogen might have been utilized in the formation of active ripe gametes.
7. After starvation for twelve days, total protein and fat contents remained constant, while glycogen content decreased by 66.82%. The water content increased by 4.67%.
8. Seasonal variation in the organic constituents are discussed in relation to the reproductive cycle of the clam.

     

The reproductive cycle in a typical estuarine mollusc Nausitora hedleyi Schepman based on a study of the Gonad Index

1. Previous work on the methods employed for the determination of the breeding season of shipworms is briefly reviewed.
2. The method adopted for studying the reproductive cycle by using the “gonad index” is described.
3. The reproductive cycle of Nausitora hedleyi is described in detail based on a study of the gonad index of different sexes collected at monthly intervals from the estuarine environment of Cochin harbour.
4. The fact that breeding is restricted as marked by seasonal activity is shown from the size and activity of the gonad during the different months of the year.
5. The environment, and the hydrographic conditions prevailing in the habitat of N. hedleyi in the Cochin harbour are described.

     

Seasonal variation in the biochemical composition of Mytilus viridis at Ratnagiri on the West Coast of India

1. The seasonal variation in the water, protein, fat and glycogen contents of the mussel, Mytilus viridis has been studied for the year March, 1974 to March, 1975.
2. The water level increased during the monsoon season and decreased in summer.
3. The level of protein, fat and glycogen showed correlation with the reproductive cycle of the mussel.
4. The protein level was high when the mussels were mature and dropped during the breeding period.
5. During sex change from male to female in May the protein level remained high whereas during sex change from female to male in October and November it was low.
6. The fat level was high in mature mussels and declined on spawning.
7. The glycogen level was at its peak in immature mussels and low in mature.

     

Charakterisierung eines phagenähnlichen Partikels aus Zellen von Nitrobacter

1. Polyhedral particles were isolated from cells of Nitrobacter winogradskyi and of Nitrobacter strains K₁, K₄ and α₁. Their physical and biological properties are characterized.
2. The investigated strains contain polyhedral particles, 1000–1200 Å in size. With increasing age of the culture more particles are found in cells of Nitrobacter. Simultaneously the number of colony producing nitritoxidants decreases.
3. In strain α₁ the loss of the capability to form colonies is connected with partial lysis of the cell and release of particles.
4. A homogeneous fraction of particles was obtained by zone density gradient centrifugation in Tris-Mg-SH-buffer.
5. The polyhedral particles have a sedimentation coefficient of s _w,20 ⁰ =825S and a CsCl-buoyant density of ?²⁵ g/cm³.
6. Based on the determined properties the particles are classified as phage-like Nitrobacter particles Nb₁.

     

An ecological study of the Ponggol Estuary in Singapore

1. An ecological study of the Ponggol Estuary was conducted from July 1965 to June 1966 and the seasonal data on physical, chemical and biological characteristics were presented.
2. The Ponggol River represents a short, narrow and shallow estuary in Singapore. The river mouth is open throughout the year and water from eastern Johore Straits drains in twice a day at high tide. The upper reach, however, is left exposed at low tide.
3. The Ponggol River was classified as a vertically and laterally homogeneous estuary and was found to exhibit a mesohaline to polyhaline environment.
4. Significant hydrological gradients from the river mouth 10 the upper reach were noted in the river system. Salinity, dissolved oxygen and pH increased towards the mouth of the river and other parameters such as nutrients, dissolved organic matter and turbidity increased towards the source.
5. Although the river received organic pollutants at the upper reach the estuary was able to discharge them fairly rapidly through regular flushing by the tides. The transient rise of organic matter did not appear to impart any serious affect on the biota in the estuary.
6. Over 98% of the phytoplankton consisted of diatoms, most of which were brought into the estuary from eastern Johore Straits. Freshwater forms were relatively few.
7. Phytoplankton biomass was considerably higher than the adjoining waters. and was reduced at the upper reach due to high turbidity of the water.
8. 80% of the zooplankton was composed of dinoflagellates,Difflugia, copepods and bivalve larvae dominating at all sections of the estuary.
9. Percentage composition of the zooplankton showed that dinoflagellates and copepod nauplii predominated at high tide whileDifflugia and bivalve larvae were abundant at low tide.
10. Zooplankton standing crop, in general, was higher towards the source at high tide but the reverse was found at low tide, i.e. standing crop increased towards the river mouth. This was attributed to the process of concentration.
11. Species composition of zooplankton was found to be more or less similar to that of the eastern Johore Straits.
12. The nekton consisted predominantly of small and juvenile fish. Close correlation of fish and copepods was found to be statistically valid and it was concluded that the fish entered the estuary to feed rather than to spawn.
13. The squids formed an important catch of the beach seine unit and were caught throughout the year.
14. The fish population could be grouped into four categories: estuarine components, euryhaline components, marine components and migratory components.
15. Benthic invertebrates were abundant. Commercially important species consisted of prawns,Metapenaeus andPenaeus, and crabs,Neptunus pelagicus andScylla serrata.
16. The river bed was inhabited predominantly by molluscs and the distribution resembled that of the sheltered shore of muddy-sand type.

     

The role of microorganisms in mobilization and fixation of phosphorus in sediments

Cycling of phosphorus (P) at the sediment/water interface is generally considered to be an abiotic process. Sediment bacteria are assumed to play only an indirect role by accelerating the transfer of electron from electron donors to electron acceptors, thus providing the necessary conditions for redox-and pH-dependent, abiotic sorption/desorption or precipitation/dissolution reactions. Results summarized in this review suggest that

1. in eutrophic lakes, sediment bacteria contain as much P as settles with organic detritus during one year
2. in oligotrophic lakes, P incorporated in benthic bacterial biomass may exceed the yearly deposition of bioavailable P several times
3. storage and release of P by sediment bacteria are redox-dependent processes
4. an appreciable amount of P buried in the sediment is associated with the organic fraction
5. sediment bacteria not only regenerate PO₄, they also contribute to the production of refractory, organic P compounds, and
6. in oligotrophic lakes, a larger fraction of the P settled with organic detritus is converted to refractory organic compounds by benthic microorganisms than in eutrophic lakes.

From this we conclude that benthic bacteria do more than just mineralize organic P compounds. Especially in oligotrophic lakes, they also may regulate the flux of P across the sediment/water interface and contribute to its terminal burial by the production of refractory organic P compounds.     

Adenine nucleotide pool variations in intact Nitrobacter winogradskyi cells

1. The ATP pool in Nitrobacter winogradskyi cells was determined by means of the luciferin-luciferase enzyme system and the ADP and AMP pools were measured after enzymatic conversion into ATP.
2. In the fist 10 min after addition of nitrite to endogenously respiring cells, which had stood for 5–16 days after completion of the nitrite oxidation, the ATP pool dropped about 60%.
3. During the log phase the ATP pool was approx. 20–40 pmoles/5 μg cell-N. During growth it increased exponentially by 3–4 times the amount until the nitrite had been used up. Subsequently the ATP pool decreased at first rapidly and then more slowly without sinking to 0 in the first 2 months after nitrification.
4. Nitrite oxidizing cells had an energy charge of 0.37 during the log-phase. After approx. 90% of the substrate had been used up the energy charge had reached 0.57.
5. If the CO₂ assimilation was inhibited in growing cultures by increased oxygen partial pressure, nitrite oxidation continued but the ATP pool increased.
6. The ATP pool and the activity of the endogenous respiration decreased by more than 50% during the first hours after the substrate had been used up.

     

Summer algal communities and primary productivity in fish ponds

The paper presents data on primary productivity and phytoplankton communities in new experimental ponds which received the following treatments; ammonium nitrate and triplesuperphosphate, triplesuperphosphate, cracked corn (10% crude protein) and Auburn No. 3 fish feed (36% crude protein). Comparative data on algal communities were also obtained from production ponds which received feeds or fertilizers. Basic ecological data on macro-algae are also presented.

1. All nutrient additions to experimental ponds resulted in higher levels of gross photosynthesis and greater concentrations of chlorophyll a than were found in the control treatments. Fertilization with both nitrogen and phosphorus gave the highest values. Chlorophyll a and gross photosynthesis were higher in ponds receiving high protein content feed (Auburn No. 3) than in ponds to which low protein content feed (corn) was applied.
2. Persistent blooms of blue-green algae occurred in ponds receiving nitrogen and phosphorus fertilization. Phosphorus only fertilization produced blooms of blue-greens, but these blooms did not persist as in the ponds to which nitrogen was also added. Control ponds were dominated by green algae. Blue-green algae were seldom abundant in feed treatments.
3. Production ponds had high level of gross photosynthesis and large concentrations of chlorophyll a.
4. Many of the production ponds which received feed applications developed heavy blooms of blue-green algae.
5. The major species of blue-green algae observed in the present study were Oscillatoria sp., Raphidiopsis curvata, Anacystis nidulans, A. aeruginosa, Spirulina sp., and Anabaena circinalis. Heterocyst bearing forms, which can presumably fix nitrogen, were seldom noted in ponds that received continuous additions of nitrogen from fish feeds.
6. Macro-algae are abundant in many fish ponds. Data illustrating the competition of macro-algae with phytoplankton are presented.

     

Growth of Nitrobacter in the presence of organic matter

1. Culture filtrates of heterotrophic bacteria were tested for their stimulatory effect on nitrification of three strains of Nitrobacter.
2. Yeast extract-peptone solution, in which Pseudomonas fluorescens had grown, after removal of the cells was added to autotrophically growing cultures of Nitrobacter agilis; it caused a stimulated nitrite oxidation and growth of Nitrobacter agilis.
3. The degree of stimulation depended on: a) the proportion of the culture filtrate to the autotrophic medium; b) the composition of the complex medium in which Pseudomonas fluorescens had been grown; c) the time the heterotrophic bacterium had been grown in the complex medium.
4. The stimulatory effect was highest with Nitrobacter agilis, less with Nitrobacter winogradskyi and negligible with Nitrobacter K ₄.
5. It was possible to adapt nitrifying cells of Nitrobacter agilis to higher concentrations of yeast extract and peptone. After the nitrite had been completely oxidized the cell-N still increased up to 30% before growth stopped.

     

Rationalization of properties of nitrate reductases in Rhodopseudomonas capsulata

1. The properties of nitrate reductase activities have been compared in several strains of Rhodopseudomonas capsulata grown phototrophically in the presence of nitrate as sole nitrogen source.
2. Strains AD2 and BK5 resemble the spontaneous mutant N22DNAR⁺ (described by McEwan et al. 1982 FEBS Lett. 150, 277\2-280) in that reduction of nitrate was inhibited by either illumination or oxygen but not by NH ₄ ⁺ , and that electron flow to nitrate under dark anaerobic conditions generated a cytoplasmic membrane potential (as judged by an electrochromic shift in the absorbance spectrum of endogenous carotenoid pigments). In contrast disappearance of nitrate from suspensions of strains N22 and St. Louis was dependent upon illumination and was inhibited by NH ₄ ⁺ . Membrane potentials were not generated by addition of nitrate in the dark to N22, St. Louis or strain Kbl.
3. Nitrate reductase was shown to be located in the periplasmic space of both strain AD2 and mutant N22DNAR⁺. The nitrate reductase activity in cells of AD2 and N22DNAR⁺ was relatively insensitive to azide, with 0.5mM azide required for 50% inhibition. The nitrate reductase of strain BK5 was more strongly associated with the cytoplasmic membrane and no conclusion could be reached about whether it was located on the periplasmic or cytoplasmic surface. In BK5 cells nitrate reductase activity was sensitive to low concentrations of azide (50% inhibition with 2 \gmM azide). It is proposed that functionally the nitrate reductase activity in strains AD2, BK5 and N22DNAR⁺ has identical roles. These roles are suggested to include:
4. The first step in the assimilation of nitrate.
5. Provision of an alternative electron acceptor to oxygen for generating a membrane potential.
6. A mechanism for disposing of excess reducing equivalents in the maintenance of balanced growth. This type of nitrate reductase, especially in AD2 and N22DNAR⁺, appears to resemble that described in a denitrifying strain of Rps. sphaeroides, but to differ markedly from its membrane-bound counterpart in other bacteria including the denitrifying Paracoccus denitrificans and Escherichia coli.
7. In other strains of Rps. capsulata including St. Louis, N22 and Kbl, only an assimilatory nitrate reductase, whose activity in intact cells is relatively sensitive to azide, is present in anaerobic, phototrophic cultures grown with nitrate as nitrogen source. As this reductase cannot be detected after breakage of cells, no conclusion can be made as to its location in the cell.

     

Effects of Environmental Perturbations on Short-Term Phytoplankton Production off Lawson's Bay,A Tropical Coastal Embayment

1. The phytoplankton cycle off Lawson's Bay, Waltair follows a bimodal pattern with a major peak during March–May; a minor peak during October–November months and with a low production during the summer months i.e., June–August.
2. During the summer months of 1957, 1958, 1960 and 1962 dumping of dredged spoil from the entrance channel of the harbour into the sea resulted in a natural enrichment of waters.
3. Following this enrichment, there was a qualitative and quantitative increase in the phytoplankters thus leading to the development of a bloom.
4. Only Thalassiosira subtilis and Chaetoceros curvisetus commonly bloomed during the four years.
5. The increase in gross production which varied from 3–13 fold and the high photosynthesis-respiration ratios 5.1 to 10.5 indicated that the bloom populations were in a healthy state.
6. The decrease of the populations to the initial levels suggests that some unknown factor, other than those investigated must have been operating.
7. Consequences of eutrophication of different origins on stimulation of phytoplankton production are briefly discussed.

     

Amino acid receptor sites in the facial taste system of the sea catfish Arius felis

1. The amino acid sensitivity and specificity of the facial taste system of the marine catfish, Arius felis, is characterized electrophysiologically.
2. The facial taste system of Arius felis responded to all 28 amino acids tested, but was highly sensitive to only a few. In general, acidic amino acids and neutral amino acids with short side chains were more effective than imino, basic and neutral amino acids with long side chains.
3. A reciprocal cross-adaptation protocol used to characterize the receptor sites identified at least some relatively independent receptor sites for L-arginine, L-histidine, L-proline, L-alanine, glycine, D-alanine and L-glutamate.
4. Of the 7 amino acids that were indicated to have relatively independent receptor sites, the median electrophysiological threshold for L-alanine, the most stimulatory, and L-proline, the least stimulatory compounds, were 10 nM and 10,000 nM, respectively. The integrated facial taste response did not saturate at test amino acid concentrations up to 10 mM.
5. The generalized depression in responsiveness to test stimuli observed during amino acid adaptation is proposed to be a result of the co-distribution of sensitivity at the level of single taste cells rather than high cross-reactivity of the respective amino acid receptor sites for the test stimuli.

     

Abundanzdynamik und reproduktionsphasen limnophiler tricladen (Turbellaria) Aus stehenden kleingewässern

Dynamics of abundance and reproductive cycles of limnophileous triclads (Turbellaria) from little ponds.

1. Studying 18 little ponds in Lower Southern-Saxonia (West-Germany), in 14 ponds seven triclad-species were found.
2. Phagocata vitta occurs from October to July in 1–2 generations. In the area the species reproduces by fissipary. Maximum abundances and rates of reproduction are reached in December and January. In the ponds, where P. vitta and Dugesia polychroa live together, there is no competition between the two species.
3. After dry periods Dendrocoelum hercynicum emigrates from interstitial habitats as facultative inhabitant of surface-waters.
4. In low abundances Dendrocoelum lacteum lives in one pond only. The breeding period (production of cocoons) lasts from January to March. Low densities of this species are probable caused by interspecific food-competition with Polycelis nigra.
5. Likewise, Dugesia tigrina inhabits only one pond. The species is competitive to P. nigra at temperatures of about 20°C. High abundances in the months July to October fall together with high fissipareous-rates.
6. Dugesia polychroa occurs in low densities over the year or dependent on dry-periods. Cocoons are produced between March and May, in low numbers till autumn.
7. In the stagnant pond Bursfelde Polycelis nigra is the absolute dominant triclad-species with densities of up to 800 individuals/0,I m³. The maximum-abundances are caused by two intense reproductive periods in spring and autumn, together with optimum temperatures and food conditions.

     

Diurnal variation in Sagar Lake,Sagar (India) I studies in the deep water area

1. A diurnal study of inland fresh water lake has been made with respect to physical and chemical properties and the plankton.
2. Chlorides have followed the total carbonates while dissolved oxygen and pH have shown no relation.
3. Microcystis has followed no definite pattern of diurnal movement.
4. All crustaceans, some of the rotifers andTrachelomonas perform considerable diurnal movement in the course of a twenty four hour period.

     

Aerobic and anaerobic growth of Paracoccus denitrificans on methanol

1. The dye-linked methanol dehydrogenase from Paracoccus denitrificans grown aerobically on methanol has been purified and its properties compared with similar enzymes from other bacteria. It was shown to be specific and to have high affinity for primary alcohols and formaldehyde as substrate, ammonia was the best activator and the enzyme could be linked to reduction of phenazine methosulphate.
2. Paracoccus denitrificans could be grown anaerobically on methanol, using nitrate or nitrite as electron acceptor. The methanol dehydrogenase synthesized under these conditions could not be differentiated from the aerobically-synthesized enzyme.
3. Activities of methanol dehydrogenase, formaldehyde dehydrogenase, formate dehydrogenase, nitrate reductase and nitrite reductase were measured under aerobic and anaerobic growth conditions.
4. Difference spectra of reduced and oxidized cytochromes in membrane and supernatant fractions of methanol-grown P. denitrificans were measured.
5. From the results of the spectral and enzymatic analyses it has been suggested that anaerobic growth on methanol/nitrate is made possible by reduction of nitrate to nitrite using electrons derived from the pyridine nucleotide-linked dehydrogenations of formaldehyde and formate, the nitrite so produced then functioning as electron acceptor for methanol dehydrogenase via cytochrome c and nitrite reductase.

     

Uptake of guanine by synchronizedChlorella fusca

1. The transport of guanine in autospores of light-dark synchronizedChlorella fusca was studied using radioactive guanine in the concentration range of 4 nM to 50 μM.
2. The transport system was constitutive, it had high specificity for the permeant, and theQ ₁₀ value was in the range of 1.5 to 2.2. At concentrations lower than 0.2 μM the half saturating constant, S_0.5 was 1 μM both for cells kept in dark and cells kept in light. At higher concentrations the S_0.5 of darkened cells was about 0.23 μM, while that of illuminated cells was unchanged. Only above 0.2 μM guanine did illumination of the cells or addition of glucose increase the transport rate.
3. Guanine which had accumulated did not leak out at temperatures below 45°C or by treatment with 10 μM dinitrophenol, which completely inhibited transport. Furthermore, the accumulated guanine did not exchange with exogenous guanine.
4. The guanine accumulated, more than 10⁵-fold over the external concentration, showing that the transport, was active.
5. The initial transport rate per cell revealed annual fluctuations.