Seasonal variability in mercury inputs into the Ria de Aveiro,Portugal

Water, suspended particulate matter (SPM) and sediments were collected from the Esteiro de Estarreja (Ria de Aveiro, Portugal), which receives considerable quantities of waste mercury from a chlor-alkali plant. Dissolved and particulate Hg concentrations in the effluent ranged between 4 –167 g I^–1 and 141–3144 g g^–1, respectively, at pH values of >10. The effluent plume undergoes significant chemical changes during advection downestuary. The evidence suggested that adsorption of dissolved Hg onto organic-rich SPM was an important process. A maximum sediment Hg concentration of 500 g g^–1 was found about 1.5 km from the discharge, as a result of the settling of Hg-rich SPM. Downestuary Hg concentrations in sediments decline to about 100 g g^–1 at the mouth of the Esteiro. The particle-water interactions are discussed in terms of the transport of dissolved and particulate Hg into the Ria de Aveiro.     

Ultrastructural analysis ofSpinacia oleracea sperm cells isolated from mature pollen grains

Summary In isolated condition, the sperm cells ofSpinacia oleracea are no longer arranged in pairs as in the pollen grain. The vegetative membrane, which surrounds a sperm cell pair in a mature pollen grain, is lost during the isolation procedure. The sperm cells become spherical in shape.The isolated sperm cell is surrounded by an intact plasma membrane. The heterochromatic or euchromatic sperm cell nucleus is located in the cell center. Mitochondria are round to oval and have distinct cristae. Often they are clustered in groups of 5 to 10 mitochondria. Dictyosomes are present in the cytoplasm and consist of 4 to 5 cisterns. Endoplasmatic reticulum is mostly situated at the sperm cell periphery, as single cisterns very near the plasma membrane.From diameters of sectioned sperm cells in electron micrographs, it is possible to calculate the average diameter of the whole sperm cell. This average diameter is 3.66 m with a variation of 3.0 m to 4.2 m, resulting in an average volume of 25.6 m³. The nuclear volume is 12.8 m³ (50.0% of the whole cell) and the mitochondrial volume is 0.7 m³ (2.5% of the whole cell). The frequency distribution of the isolated sperm cells diameters shows only one peak with a normal distribution, indicating that there is no dimorphism in volume.     

The distribution of dissolved DNA in an oligotrophic and a eutrophic river of Southwest Florida

The distribution of dissolved DNA concentrations and some microbial variables were compared in an oligo-mesotrophic river (the Crystal River) and a phosphate-rich eutrophic river (the Alafia River) in Southwest Florida over a 15 month period. Concentrations of phosphate and nitrate in the Alafia River averaged 135 and 18.2 times the respective phosphate and nitrate concentrations of the oligo-mesotrophic Crystal River. The seasonal average dissolved DNA concentration for the Alafia River exceeded that of the Crystal River by a factor of 1.8 (8.2 g 1^–1 compared to 4.6 g 1^–1, respectively). The greatest concentrations of dissolved DNA in the Alafia River were found in areas that contained the largest populations of phytoplankton and bacteria (a reservoir formed from an abandoned phosphate mining pit and two downstream stations near the mouth of the river). Differences in dissolved DNA concentrations between these environments and more pristine environments (i.e. all Crystal River Stations and upstream Alafia River stations) were of the same order of magnitude (1.8 to 2.2-fold) as the differences in bacterial abundance and activity, but considerably less than differences in phytoplankton abundance and activity between such environments. Seasonal variations in dissolved DNA concentrations in the Crystal River corresponded to seasonal variations in microbial populations, with minimal values in January and greater values in July. In the Alafia River, lowest concentrations for dissolved DNA occurred in July during the wet season, when seasonal flooding of area of leaf litter yielded high levels of dissolved organic carbon (DOC) which were low in dissolved DNA. These results suggest that: 1) in situ planktonic activity is a greater source of dissolved DNA than allochthonous or terrestrial sources of DOC; 2) factors that control the magnitude of heterotrophic bacterial populations are more likely to control dissolved DNA levels than factors regulating autotrophic population activity and abundance; 3) differences in dissolved DNA between eutrophic and oligo-mesotrophic environments are often much smaller than the differences in nutrient concentration between such environments.     

The role of phytoplankton in pollutant transfer processes in rivers. Example of River Marne (France)

The impact of the spring phytoplanktonic blooms on the partition of nutrients and metals between the dissolved and particulate phases was studied over two years in the river Marne, upstream of its confluence with the river Seine. Particular attention was devoted to copper and manganese, determined in the dissolved phase (< 0.22 m), subdivided into the colloidal phase and the 'truly dissolved' phase (< 10 KDaltons) obtained by tangential ultrafiltration. During the algal growth peaks, a sharp reduction of nutrients was observed in the dissolved phase: in 1994, consumption of 70% of silica, 50% of ammonium and 40% of soluble phosphorus present before the phytoplanktonic bloom.The water concentration peaks of suspended matter (SM) and of particulate metals, phosphorus and carbon coincide with those of chlorophyll. The highly significant correlations between pH and chlorophyll (r = 0.92, P < 0.001), pH and SM (r = 0.97, P < 0.001) and chlorophyll and SM (r = 0.93, P < 0.001) confirmed the phytoplanktonic nature of SM and the determining role of pH in the partition of metals, its increase being responsible for the coprecipitation of metal. As a corollary to the increase in the particulate phase, a decrease of 55% was observed for copper and manganese in the 'truly dissolved' phase compared to the concentrations outside bloom periods.The importance of the colloidal fraction was also shown. During the strong algal growth periods, the proportion of 'colloidal metal' in the dissolved phase (< 0.22 m) reached 60% and the increase in the colloidal fraction was 4 times stronger for copper than for manganese. While manganese seemed to be more associated with macroparticles, copper was more associated with fine colloidal biological particles intrinsic to the phytoplankton.     

Influences of land use and stream size on particulate and dissolved materials in a small Amazonian stream network

We investigated the influences of forest or pasture land use and stream size on particulate and dissolved material concentrations in a network of second to third order streams in Rondônia, in the Brazilian Amazon. During the dry season, a second order stream originating in pasture had lower concentrations of dissolved oxygen and nitrate, higher concentrations of chlorophyll, total suspended solids, particulate organic carbon, particular organic nitrogen, ammonium, and phosphate than a second order stream originating in forest. Where the second order forest stream exited forest and entered pasture, concentrations of dissolved oxygen dropped from 6 mg/L to almost 0 mg/L and nitrate concentrations dropped from 12 M to 2 M over a reach of 2 km. These changes indicated a strong influence of land use. During the rainy season, differences among reaches of all particulate and dissolved materials were diminished. Concentrations of oxygen, chlorophyll, total suspended solids, particulate organic carbon and nitrogen, nitrate, ammonium, and phosphate in the third order pasture stream more closely resembled the second order forest stream than the second order pasture stream, suggesting that conditions in the channels of larger pasture streams more strongly control concentrations of these materials. If this pattern is widespread in stream networks of regions that consist of a mosaic of forest and pasture lands, it may have important consequences for understanding the effects of deforestation on larger rivers of the Amazon Basin. This would indicate that the effects of forest clearing on the concentrations of many suspended and dissolved materials will be most easily detected in very small streams but potentially difficult to detect in larger streams and rivers.     

Fine structure,origin, and distribution density of the autonomic nerve endings in the tarsal muscle in the eyelid of the mouse

Summary The fine structure, origin, and distribution density of the autonomic nerve endings in the tarsal muscle of the mouse were studied by histochemistry and electron microscopy. With histochemical methods, the fine nerve plexus in the normal muscle shows both catecholamine-positive varicose fibers and acetylcholinesterase-active varicose fibers. The former are distributed more densely than the latter. After superior cervical ganglionectomy, the catecholamine-positive fibers disappear, while after pterygopalatine ganglionectomy, the acetylcholinesterase-active fibers vanish. In electron micrographs, the varicosities appear as expansions containing many synaptic vesicles. The axonal expansions partly lack a Schwann sheath and directly face the pinocytotic vesicle-rich zones of the smooth muscle cells. A relatively wide space, 0.1 to 1.0 m in width, lies between nerve expansion and muscle cell. The expansions can be classified into two types: Type I having small granular synaptic vesicles, and Type II having agranular vesicles instead of small granular synaptic vesicles. Type I undergoes degeneration after superior cervical ganglionectomy, while Type II degenerates after pterygopalatine ganglionectomy. This indicates that Type I corresponds to the synaptic ending of the adrenergic fiber originating from the superior cervical ganglion, and Type II to the synaptic ending of the cholinergic nerve fiber derived from the pterygopalatine ganglion. Type I is more frequent (88/10⁴ m² area of muscle) than Type II (17/10⁴ m²).     

Tissue culture ofKarwinskia humboldtiana—a plant producing toxins with antitumoural effects

Isolated embryos ofKarwinskia humboldtiana were cultured in vitro. The growth of embryos and development to plantlets on woody plant medium supplemented with indole-3-acetic acid 6.10^-2 mol l^–1, gibberellic acid (GA₃) 3.10^-2 mol l^–1, and 6-benzylaminopurine (BA) 2 mol l^–1 was obtained. Multiplication of shoots and rooting of excised shoots has been achieved. Callus formation on modified Murashige-Skoog medium supplemented with 1-naphthaleneacetic acid 10 mol l^–1, GA₃ 14 mol l^–1, and kinetin 5 mol l^–1 on hypocotyls, or on root cultures on medium supplemented with 2.4-dichlorophenoxyacetic acid 10 mol l^–1 and BA 10 mol l^–1 was induced.Abbreviations BA 6-benzylaminopurine - 2,4-d 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - TEM transmission electron microscopy     

Overview of trace metal contamination in the Scheldt estuary and effect of regulatory measures

Seasonally, dissolved and particulate metal concentrations in the Scheldt estuary were assessed over a period of 4 years (1995–1998). High quality data were obtained following stringent analytical protocols for each step: sampling, sample treatment, sample storage and analysis. Of the 5 trace metals, Ni showed the most conservative behaviour, while Cd and Cu were clearly transferred from the particulate to the dissolved phase in the middle estuary. A substantial part of the particulate metals entering the estuarine system are lost through sedimentation. General seasonal patterns are the following: lower concentrations in spring and higher ones in winter (sometimes late fall/early winter) for dissolved metals, while in summer a pronounced rise of the longitudinal concentration profile is observed for the particulate metals. A comparison of the trace metal concentrations (dissolved and particulate) at the mouth of the estuary in 1995–1998 with those from 1981 to 1983, reveal reductions between 30 and 58%. Reductions based on direct emission measurements for almost the same period suggest reductions (dissolved + particulate) between 42 and 64%. Biomagnification (BMF) is the accumulation of a compound through the food-chain. It is in our case expressed as the ratio of the metal concentration in the organism (g g^–1, d.w.)/the metal concentration in total suspended matter (g g^–1, d.w.). Almost all BMF-values of Periwinkle, Nereis diversicolor and Macoma balthica (3 bottom organisms in the Scheldt estuary) are negative meaning that these organisms contain less heavy metals than the particulate suspended matter. For all organisms log BMFs for Pb, respectively Ni, are around –1.8, respectively –0.7. For Cd, Periwinkle shows slight enrichment (0.05) and for Cu even more (0.45), while negative values were observed for Nereis diversicolour and Macoma balthica. The latter organisms are more enriched in Zn (–0.09) than Periwinkle (–0.43).     

A method for long-term micropropagation of Phaseolus coccineus L.

A method for long-term plant regeneration of Phaseolus coccineus L, is described. Shoot-tips and cotyledonary nodes cultured on a Murashige and Skoog medium supplemented with N⁶-benzylaminopurine, 10 M, and -naphthaleneacetic acid, 1M, formed multiple bud-shoots. These shoots were transferred to medium containing BAP 1 M, NAA 0.1 M, and gibberellic acid 3 M to promote shoot growth and further shoot multiplication. Rooting was achieved in medium with 11 M indole-3-acetic acid. Rooted plants grew to maturity and were fertile. Cultures have maintained their ability to regenerate plants for more than two years. A sample of 30 regenerated plants (R₀) was tested for chromosome number, all of them being diploid; seven isozymatic systems were electrophpretically analyzed in 82 R₀ regenerated plants. No differences were observed in their electrophoretic patterns in comparison with those shown by seedlings. Histological studies revealed the origin of buds from calluses via organogenesis.Abbreviations BAP N⁶-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - MS Murashige and Skoog (1962) medium - NAA -naphthaleneacetic acid - ADH alcohol dehydrogenase - GOT glutamic-oxaloacetic transaminase - MDH malate dehydrogenase - 6PGD 6-phosphogluconate dehydrogenase - PGI Phosphoglucose isomerase - PGM phosphoglucose mutase - SK shikimate dehydrogenase     

Lipid composition of water and surface sediments in Takapoto atoll lagoon (French Polynesia)

Dissolved, particulate and sedimentary lipid compounds were analyzed in samples collected in May 1988 at three sites in the lagoon of the closed atoll of Takapoto (Tuamotu archipelago, French Polynesia). The study provides background information dealing with water quality and the nature and concentration of lipids. Non-aromatic hydrocarbons and fatty acids were isolated from lipids and analyzed by gas chromatography/mass spectrometry. Non-aromatic hydrocarbon concentrations did not exceed 1000 ng l^-1 in water, and 2300 ng g^-1 in surface sediments and are among the lowest encountered in pristine marine environments. No noticeable petroleum pollution was evidenced in the lagoon. Nevertheless, traces of petroleum-derived compounds were detected at the central site for both surface and deep water. Total fatty acid concentrations varied in the range 6.3–14.4 g l^-1 for the particulate phase and in the range 0.5–3.2 g l^-1 for the dissolved phase. The molecular fingerprints of fatty acids and hydrocarbons evidenced a predominant algal, and to a lesser extent microbial, origin of the organic matter present in water and sediments. Mono- and polyunsaturated fatty acids, which are essential components for animal metabolism, were identified in noticeable amounts in suspended matter (1.8–4.6 g l^-1), and at highly variable levels in the dissolved phase (0.08–1.21 g l^-1).     

The occurrence and behaviour of phosphate fractions in Izmir Bay, Aegean Sea

The area around Izmir Bay (Turkey) is heavily urbanized and receives, therefore, high concentrations of phosphate originating from industrial and municipal inputs. During the surveys between April 1993 and July 1994, the total phosphate concentrations were highest in the Inner Bay (6.45 M and 5.59 M in the surface and bottom water, respectively) where very dense anthropogenic pollution occurs. The total phosphate value gradually decreased towards the Outer Bay where 0.70 M and 1.18 M were found in the surface and bottom water, respectively. The distribution of dissolved inorganic, dissolved organic and particulate phosphate along the bay reflected some peculiar spatial and temporal patterns. A high percentage of dissolved organic phosphate was observed in the Outer Bay while the particulate phosphate peaked in the Middle Bay where an upwelling mechanism was observed. In the bay, the biological production was strongly correlated with the variations in the dissolved inorganic, organic and particulate phosphate. The high phosphate concentration in particles caused the particulate phosphate formed in the Inner Bay to be transported to the outer parts of the bay because of the short water residence time. On the other hand, Principal Component Analysis showed that about 35% of the variation in all variables measured were related to the total phosphate, total dissolved phosphate, dissolved inorganic phosphate and particulate phosphate together with ammonium and reactive-Fe while about 14% of the variation was related to the dissolved organic phosphate and the number of phytoplankton cells, chl-a, pH and O₂.     

Is bacterioplankton production in the Ria de Aveiro influenced by salt marshes and bed sediment?

The contribution of potential export of materials from bottom sedimentsand salt marshes into the water column of a shallow estuarine system of Ria deAveiro to the observed high bacterial productivity in the mid section of thisestuary was evaluated. Vertical profiles of physical, chemical and bacterialvariables were studied in the marine and brackish water zones, and oftransversal profiles in the brackish zone only. Although the concentrations ofseston (17–241 mg l^–1), particulate organiccarbon (3–15.5 mg l^–1) and chlorophyll(1.2–7.0 g l^–1) varied widely, thevertical and transversal profiles were without much variation. Total bacterialnumber (0.2–8.5 × 10⁹ cellsl^–1) and the number of particle-attached bacteria(0.02–2.50 × 10⁹ cellsl^–1)along vertical and transversal profiles did not differ much, but the rate ofbacterial production (0.05–14.2 g C l^–1h^–1) and dissolved organic carbon concentration(6.0–69.2 mg l^–1) were frequently highernear the salt marsh margin at the brackish water transect. The increase inproductivity could not be associated with runoff of particulate matter butcoincided with the inputs of dissolved organic carbon. The results of verticaland transversal profiles point to a minor role of particulate matter additionsfrom the salt marsh area or from bed sediments.     

Surface distribution of size-fractionated chlorophyll a and participate organic matter in the Strait of Magellan

The surface distribution of chlorophyll a (chl a) from size-fractionated phytoplankton and of particulate organic matter was studied along the Strait of Magellan during late austral summer (February 20th to March 2nd, 1991), in order to contribute an outline of the ecological characteristics of its pelagic compartment. Sampling of surface water was carried out at 2.5 mile intervals, yielding 152 sampling points for chl a and 104 for particulate organic carbon (POC). The Strait appeared as a system strongly controlled by land forcing. Its phytoplankton community was dominated by the picoplanktonic fraction along its entire length, with mean chl a concentrations of 0.74 and 1.17 g dm^–3 for pico- and total phytoplankton, respectively. The microphytoplankton never exceeded 0.02 g dm^–3. POC concentrations, with a maximum of 242.5 and a mean of 144.8 g dm^–3, were mainly of autotrophic origin, as indicated by a mean POC:chl a ratio of 138.4.     

Differential filtration studies of carbon flux from living algae to microheterotrophs,microplankton size distribution and respiration in Lake Kinneret

The flux of newly photosynthetically fixed, dissolved organic carbon (PDOC) from phototrophs to microheterotrophs in Lake Kinneret was examined by differential (3 and 0.4m) filtration after samples were incubated with¹⁴C-bicarbonate for 3 hours (in the light) and subsequently for 21 hours (in darkness). Only a small proportion (average about 10%) of the carbon fixed from¹⁴C-bicarbonate in the light was associated with particulate matter <3m. In 14 out of 16 experiments there was no significant decrease in the relative proportion of radioactivity associated with larger (>3m) organisms after the dark period, suggesting that the amount of PDOC taken up by unclumped, single bacteria (<3m) was not very great. Respiration rates, estimated by the decrease in¹⁴C particulate counts in the dark period, ranged from 3.4 to 21.2% of daylight net photosynthesis. In almost all cases, parallel experiments with additions of radioactive glucose or amino acids indicated that the majority of active heterotrophs passed through 3m filters. Apparent residence times for glucose and amino acids were 20 to 168 hours and 20 to 152 hours, respectively.     

An efficient <Emphasis Type="Italic">in vitro</Emphasis> method for mass propagation of <Emphasis Type="Italic">Tylophora indica</Emphasis>

A protocol of high frequency shoot organogenesis and plant establishment from stem derived callus has been developed for Tylophora indica (Burm. f.) Merrill. - an endangered medicinal plant. Callus was developed on Murashige and Skoog (MS) medium supplemented with 10 M 2,4,5-trichlorophenoxy acetic acid (2,4,5-T). Multiple shoot induction was achieved from the surface of the callus after transferring onto shoot induction medium. The highest rate (80 %) of shoot multiplication was achieved on MS medium containing 5.0 M kinetin. The developed shoots rooted best on half-strength MS medium supplemented with 0.5 M indole-3-butyric acid (IBA). The in vitro raised plantlets with well developed shoot and roots were acclimatized successfully and grown in greenhouse.     

Influence of nitrogen on the behaviour of nickel in wheat

A glasshouse experiment was conducted to study the effect of Ni on the growth and nutrients concentration in wheat (Triticum aestivum Cv. WH 291) in the presence and absence of applied N as urea. Responses to N application were observed up to 120 g N g^–1 soil. No response to Ni was observed in the dry matter yield of wheat tops (leaves + stem) in the absence of applied N while in the presence of applied N, significant yield increases were obtained at 12.5g Ni g^–1 soil. Nickel was not toxic to wheat up to 50g Ni g^–1 soil in the presence of 120g N g^–1 soil. Nitrogen and Ni concentration in wheat tops and roots increased with increasing levels of applied N and Ni, respectively. Applied Ni had an antagonistic effect on N concentration. Similarly, N reduced the Ni concentration in the wheat tissues. Positive growth responses to Ni were associated with 22 and 15g Ni g^–1 in wheat tops, in the presence of applied N at 60 and 120g N g^–1 soil, while Ni toxicity was associated with 63, 92.5 and 112.5g Ni g^–1 in wheat tops, in the absence and presence of applied N at 60 and 120g N g^–1 soil, respectively.     

Factors affecting direct organogenesis from flower explants of Allium giganteum

A novel method is described for the propagation of Allium giganteum Regel using direct organogenesis resulting in multiple shoot structures formed on mature flower buds or ovaries. A two step induction and differentiation procedure, similar to that described earlier in onion, was tested. Flowers were inoculated on the induction medium for 6 days and extracted ovaries were placed on the differentiation medium. Optimal formation of multiple shoot structures was obtained using modified BDS medium containing 50 g l^–1 sucrose solidified by a mixture of agar/gellan-gum, with 8.88 M benzylaminopurine (BA) and 9.05 M 2,4 dichlorophenoxyacetic acid (2,4-D) in induction medium and 9.08 M tidiazuron (TDZ) in the differentiation medium. Five plant sources obtained from different European retailers of ornamental bulbs were tested separately. All tested genotypes produced multiple organogenic structures, although induction percentages clustered in two distinctive groups. Shoots formed tended to become dormant, and attempts to improve their growth and rooting included treatment with fluridone. Dormancy was partly broken when shoots were briefly dipped in 1 M fluridone. Genetic analysis of plant sources using random amplified polymorphic DNA method showed that 5 retailers actually distribute only two different clones, one of them more and the other less responsive to shoot organogensis.     

Growth and survival of tadpoles (Bufo americanus) fed amorphous detritus derived from natural waters

Growth and survival of tadpoles (Bufo americanus) were used to assess the food value of three types of amorphous detritus thought to be derived from dissolved organic matter (DOM) transported in river water or groundwater: 1. Flocculent organic aggregates suspended at the mouth of a humic stained river which drains into Lake Superior; 2. Precipitates formed directly from humic stained river water; 3. The < 35 m fraction of littoral lake sediment. Tadpoles were unable to grow when fed the amorphous detritus, but experienced lower mortality than unfed animals. Although the food quality of certain types of detritus derived from DOM may be inadequate to support the growth of aquatic fine particle feeders it may contribute to the nutrition of facultative detritivores.     

The spermatozoon of Oikopleura dioica Fol (Larvacea,Tunicata)

Summary The spermatozoon of Oikopleura dioica is about 30 m long, with a spherical head, about 1 m wide, a 3 m long and 1 m wide midpiece, and a 25 m long tail with a tapered end piece. The head contains a nucleus with the chromatin volume limited to about 0.1 m³. A small acrosome is found in an anterior inpocketing, and a flagellar basal body in a posterior inpocketing of the nucleus. The midpiece contains a single mitochondrion with the flagellar axoneme embedded in a groove along its medial surface. The flagellar axoneme has the typical 9 + 2 substructure, and the basal body the typical 9+0 substructure. A second centriole and special anchoring fibres are absent.     

Annual variation of dissolved free primary amines in estuarine water and sediment

Summary The concentration of dissolved free primary amines (DFPA), determined as fluorescamine positive material, was quantified during a one year period of a small estuary. In the water, the concentration of DFPA ranged from 1.8 M in winter, to 26.5 M in summer. In the sediment, from 16 to 56 M of DFPA occurred. The concentration varied with depth and season, and in summer months a maximum of DFPA was observed in the redox discontinuity layer. The DFPA peak in water and sediment coincided with maximum of the macrophytal biomass. About 80% of the fluorescamine positive material was identified as amino acids. Origin and distribution of primary amines in the estuarine environment are discussed.