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1.
A cultivation-based approach was employed to compare the culturable actinobacterial diversity associated with five marine sponge species (Craniella australiensis, Halichondria rugosa, Reniochalina sp., Sponge sp., and Stelletta tenuis). The phylogenetic affiliation of the actinobacterial isolates was assessed by 16S rDNA-RFLP analysis. A total of 181 actinobacterial strains were isolated using five different culture media (denoted as M1–M5). The type of medium exhibited significant effects on the number of actinobacteria recovered, with the highest number of isolates on M3 (63 isolates) and the lowest on M1 (12 isolates). The genera isolated were also different, with the recovery of three genera on M2 and M3, and only a single genus on M1. The number of actinobacteria isolated from the five sponge species was significantly different, with a count of 83, 36, 30, 17, and 15 isolates from S. tenuis, H. rugosa, Sponge sp., Reniochalina sp., and C. australiensis, respectively. M3 was the best isolation medium for recovery of actinobacteria from S. tenuis, H. rugosa, and Sponge sp., while no specific medium preference was observed for the recovery of actinobacteria from Reniochalina sp., and C. australiensis. The RFLP fingerprinting of 16S rDNA genes digested with HhaI revealed six different patterns, in which 16 representative 16S rDNAs were fully sequenced. Phylogenetic analysis indicated that 12 strains belong to the group Streptomyces, three strains belong to Pseudonocardia, and one strain belongs to Nocardia. Two strains C14 (from C. australiensis) and N13 (from Sponge sp.) have only 96.26% and 96.27% similarity to earlier published sequences, and are therefore potential candidates for new species. The highest diversity of three actinobacteria genera was obtained from Sponge sp., though the number of isolates was low. Two genera of actinobacteria, Streptomyces, and Pseudonocardia, were isolated from both S. tenuis and C. australiensis. Only the genus of Streptomyces was isolated from H. rugosa and Reniochalina sp. Sponge species have been demonstrated here to vary as sources of culturable actinobacterial diversity, and the methods for sampling such diversity presented may be useful for improved sampling of such diversity.  相似文献   

2.
1. The response of a species to environmental disturbance is largely mediated by its life history traits that have evolved within a particular habitat template. Altered flow seasonality, as a direct consequence of river regulation, is a major environmental disturbance and has been implicated in the redistribution of a range of riverine organisms. An understanding of the reasons for species‐specific responses, however, has proved elusive. 2. Here, we investigated the reproduction of three riverine shrimp species (Paratya australiensis, Caridina mccullochi and Macrobrachium australiense) that show contrasting patterns in distribution and abundance in regulated Australian rivers. 3. In all three species, breeding females were largest, and fecundity was greatest early in the breeding season (November–December). Fecundity and egg size subsequently declined, with lower investment (overall and per offspring) perhaps indicating that conditions for larvae were more favourable later in the breeding season (a time normally characterised by low flow, warm water and high productivity). 4. Interspecific differences in absolute values of reproductive traits were, however, striking. Paratya australiensis has typically ‘opportunistic’ traits (small body size, small eggs and high fecundity), whereas M. australiense has more ‘equilibrium’ traits (larger body size, larger eggs and moderate fecundity). Caridina mccullochi is intermediate, having neither high fecundity nor large size, and has limited swimming ability when young. This species is now absent from at least one heavily regulated river in south‐eastern Australia, and we hypothesise that its life history may explain this absence. 5. Studies involving aspects of life history, such as reproductive traits, are likely to improve our understanding of a range of organisms and assist in the management of disturbed or altered environments.  相似文献   

3.
The life table responses and population dynamics of four cladocerans(Ceriodaphnia lacustris, Daphnia parvula, Diaphonosoma leuchtenbergianumand Moina micrura) were measured during a flood of a large turbidreservoir (Lake Texoma, Oklahoma-Texas). Mean recruitment andlongevity of Ceriodaphnia and Daphnia in life table experimentswere reduced during the flood when abundant silt particles andpicoplankton (<2 µm) replaced algal particles in thewater column. Individual growth rates measured in the life tableexperiments were slower for Ceriodaphnia during the flood. Fieldcollections revealed that Ceriodaphnia and Daphnia populationsdeclined immediately after the arrival of turbid water, andremaining females carried fewer eggs. Populations of Moina andDiaphanosoma increased during the flood, and life table experimentsshowed that these species were able to grow well in silt-ladenwater.  相似文献   

4.
Fatty acids (FAs) profiles and stable isotope signatures of the ghost shrimp, Trypaea australiensis and the soldier crab, Mictyris longicarpus were determined at an unvegetated sandbank of Southport (Gold Coast, Queensland, Australia), in November 2005 and February 2006. Additionally, the FAs composition of the faeces and feeding pellets of M. longicarpus and the surface sediment at the study site were also analysed. Trypaea australiensis was found to selectively feed principally on benthic diatoms, as revealed by the high contribution of the marker lipid (20:5 (n‐3)) to tissue total FAs and the δ13C and δ15N isotopic signatures of shrimp tissues. Although the diet of T. australiensis did not change between the two sampling periods, the shrimps appeared to reduce their feeding activity in summer, presumably in relation to a restricted metabolism, as revealed by a decrease in the contribution of the microalgal markers in their tissues. The FAs composition of the tissues of the soldier crab indicated that bacteria and diatoms constituted the base of its diet (contributions of branched 15:0 and 17:0, 18:1 (n‐7) and 20:5 (n‐3)). However, the isotopic signatures of the crabs suggested that meiofauna may represent an intermediate link between the crab and these micro‐organisms.  相似文献   

5.
Proteolytic activity was found in the culture fluids of numerous psychrophilic bacteria isolated from terrestrial or marine samples. Among these organisms, a marine psychrophilic bacterium, Pseudomonas sp. No. 548, showed the highest proteolytic activity. This organism required salts of sea water for both growth and protease formation. The optimum temperature for the growth of this organism was 20°C. The formation of protease was the greatest at 5°C and decreased with increasing temperature. The extracellular protease system was fractionated into at least two components having proteolytic activities by chromatography with DEAE-cellulose. Increasing culture temperature tended to increase the activity ratio of Fraction I to Fraction II. Some cultural conditions for protease formation were investigated.  相似文献   

6.
Summary A number of bacterial strains, representing a range of genera, were isolated in pure culture with ethene or propene as the sole source of carbon and energy. The organisms included Aerococcus, Alcaligenes, Micrococcus and Staphylococcus spp. and a variety of Gram-negative, Gram-positive and Gram-variable mesophilic rods/ coccobacilli not yet identified. This suggests that the ability to utilize gaseous olefins is more widespread in nature than previously recognised. All 18 organisms tested stereospecifically formed R-1,2-epoxypropane (enantiomeric excess, ee=90–96%), R-1,2-epoxybutane (ee=90–98%) and trans-(2R,3R)-epoxybutane (ee=64–88%) from the corresponding olefins. In addition to Micrococcus sp. M90C, the substrate specificities of six other organisms were studied. The pattern of reactivity for the group of four ethene (M26, M90C, M93A, M186)- and two propene (M142, M156)-utilizers differed from that found with peracids, whereas the chemical reactivity of the substrate appeared to affect enzymatic epoxidations in Staphylococcus sp. M97B. Offprint requests to: M. Mahmoudian  相似文献   

7.
Batch and continuous cultures ofAnkistrodesmus braunii were established in an inorganic medium with growth rate limited by P. In batch culture, inoculation of lake water bacterial isolates ofPseudomonas sp. andFlavobacterium sp. showed that thePseudomonas isolate was capable of more rapid growth on algal exudates of lytic products than was theFlavobacterium isolate. When inoculated singly into a continuous culture (D=0.267 day–1; P level, 2M), theFlavobacterium isolate initially caused a decrease in the population density of the alga, but then steady states for both organisms were obtained. ThePseudomonas isolate under the same conditions caused a rapid washout of the algal culture, and steady-state conditions were never obtained. When thePseudomonas isolate was added to the two-member, steady-state system ofA. braunii andFlavobacterium, the algal population again washed out of the vessel, followed by theFlavobacterium and then thePseudomonas isolate. A transient increase in the P concentration to 200M in the culture vessel caused the low algal population level to increase, followed by increases in the bacterial isolates when the algal population was high enough to supply the required organic carbon source. The system demonstrated that competition for P between the alga and the bacteria can occur, and the results were dependent on the algal and bacterial relative growth rates. The bacterial growth rates were limited initially by organic substrates produced by the alga, and the different bacterial isolates competed for these substrates.  相似文献   

8.
The role of dissolved oxygen as a principal electron acceptor for microbial metabolism was investigated within Fe(III)‐oxide microbial mats that form in acidic geothermal springs of Yellowstone National Park (USA). Specific goals of the study were to measure and model dissolved oxygen profiles within high‐temperature (65–75°C) acidic (pH = 2.7–3.8) Fe(III)‐oxide microbial mats, and correlate the abundance of aerobic, iron‐oxidizing Metallosphaera yellowstonensis organisms and mRNA gene expression levels to Fe(II)‐oxidizing habitats shown to consume oxygen. In situ oxygen microprofiles were obtained perpendicular to the direction of convective flow across the aqueous phase/Fe(III)‐oxide microbial mat interface using oxygen microsensors. Dissolved oxygen concentrations dropped from ~ 50–60 μM in the bulk‐fluid/mat surface to below detection (< 0.3 μM) at a depth of ~ 700 μm (~ 10% of the total mat depth). Net areal oxygen fluxes into the microbial mats were estimated to range from 1.4–1.6 × 10?4 μmol cm?2 s?1. Dimensionless parameters were used to model dissolved oxygen profiles and establish that mass transfer rates limit the oxygen consumption. A zone of higher dissolved oxygen at the mat surface promotes Fe(III)‐oxide biomineralization, which was supported using molecular analysis of Metallosphaera yellowstonensis 16S rRNA gene copy numbers and mRNA expression of haem Cu oxidases (FoxA) associated with Fe(II)‐oxidation.  相似文献   

9.
Sur quelques Mesocyclops (Crustacea,Copepoda)   总被引:3,自引:3,他引:0  
Resumé Après un rappel des critères morphologiques qu'il faut considérer en taxonomie des Copépodes du genre Mesocyclops, 14 espèces de ce genre sont décrites our redécrites, à savoir: M. granulatus nov.sp., M. thermocyclopoides, M. isabellae nov.sp., M. Kieferi, M. pehpeiensis, M. ogunnus, M. splendidus, M. brevisetosus, M. borneoensis nov.sp., M. tobae, M. pseudospinosus nov.sp., M. darwini nov.sp., M. notius, et M. australiensis, toutes formes des régions tropicales de l'Asie méridionale ou de l'Australasie.  相似文献   

10.
Ecotoxicology is the science responsible for the study of the adverse effects of chemicals on ecosystems considering biotic and abiotic components. Several invertebrate groups have long been used to evaluate the aquatic toxicity of chemical compounds. Among these organisms, the microcrustaceans are the most recommended in Brazilian and international protocols (e.g. Daphnia sp. and Ceriodaphnia sp.). Until the beginning of the 1990s, the use of mollusks with ecotoxicological purposes was non-existent, except for the species tested as target of molluscicides in public health studies. Since the second half of this same decade the tests with mollusks have begun to be disseminated in several countries, valuing endemic species and especially the scarcity of test species in benthic habitats. In the early 2000s, with the disclosure of the harmful effects of pollutants with endocrine disrupting properties, gastropods have begun to be used not to evaluate lethal effects, but rather to observe physiological effects such as reproduction and embryonic development. Since then, assays with these approaches, especially with freshwater snails Lymnaea stagnalis and Biomphalaria sp., have been considered to be innovative and highly sensitive, often more than those achieved with traditional groups of test organisms in ecotoxicology (such as microcrustaceans and fishes).  相似文献   

11.
ABSTRACT Goussia girellae n. sp. is described from the opaleye fish, Girella nigricans. Merogonic stages were observed in the apices of intestinal epithelial cells, in the lamina propria, and in extra-intestinal sites including liver, gills, and spleen. Gamonts were observed in the intestinal epithelial cells. Only unsporulated oocysts were detected in the intestine, and sporulation occurred when feces containing oocysts were incubated for 48 h in seawater at 21°C. Oocysts are elongated (24.8 × 14.7 μm) with a wall about 200 nm thick and have no residuum, micropyle, or polar granule. Sporocysts are ellipsoid (8.5 × 4.5 μm), have a thin two-layered wall approximately 30 nm thick, and consist of two valves joined by a suture. Although moribund opaleye were also infected with Gyrodactylus sp., Cryptobia sp., Cardicola sp., and epitheliocystis organisms (chlamydia), all fish were heavily infected with G. girellae and morbidity was thus attributed to the coccidium.  相似文献   

12.
SYNOPSIS. Toxoplasma ranae sp. n. is described from the brain of a leopard frog, Rana pipiens, probably from Mexico. Its pseudocysts were 72(55-106) × 48(29-70) μm in fixed sections. They contained an average of ~ 4,000 slightly curved elongate zoites measuring 4–5 × 0.5 μm, with a central, spherical, vesicular nucleus.  相似文献   

13.
光催化与纯紫外工艺对船舶压载水微藻的处理效果比较   总被引:3,自引:0,他引:3  
分析光催化和纯紫外工艺对控制处理压载水中10~50μm藻类的影响,比较了压载水中10~50μm藻类的去除率、种类变化、绿藻和硅藻去除率以及硅藻种类数的变化,结果显示光催化工艺对10~50μm藻类的去除效果要好于纯紫外工艺。两种工艺对10~50μm藻类的即时去除率均可以达到96.0%以上,压载数日后排放则效果更佳。研究发现两种工艺对硅藻的处理效果不如绿藻。并且压载水盐度会影响压载水处理工艺的效果。  相似文献   

14.
Biogeochemical, isotope geochemical and microbiological investigation of Lake Svetloe (White Sea basin), a meromictic freshwater was carried out in April 2014, when ice thickness was ~0.5 m, and the ice‐covered water column contained oxygen to 23 m depth. Below, the anoxic water column contained ferrous iron (up to 240 μμM), manganese (60 μM), sulfide (up to 2 μM) and dissolved methane (960 μM). The highest abundance of microbial cells revealed by epifluorescence microscopy was found in the chemocline (redox zone) at 23–24.5 m. Oxygenic photosynthesis exhibited two peaks: the major one (0.43 μmol C L?1 day?1) below the ice and the minor one in the chemocline zone, where cyanobacteria related to Synechococcus rubescens were detected. The maximum of anoxygenic photosynthesis (0.69 μmol C L?1 day?1) at the oxic/anoxic interface, for which green sulfur bacteria Chlorobium phaeoclathratiforme were probably responsible, exceeded the value for oxygenic photosynthesis. Bacterial sulfate reduction peaked (1.5 μmol S L?1 day?1) below the chemocline zone. The rates of methane oxidation were as high as 1.8 μmol CH4 L?1 day?1 at the oxi/anoxic interface and much lower in the oxic zone. Small phycoerythrin‐containing Synechococcus‐related cyanobacteria were probably involved in accumulation of metal oxides in the redox zone.  相似文献   

15.
Crustose coralline algae occupied ~1%–2% (occasionally up to 7%) of the sea floor within their depth range of 15–50 m, and they were the dominant encrusting organisms and macroalgae beyond 20 m depth in Young Sound, NE Greenland. In the laboratory, oxygen microelectrodes were used to measure net photosynthesis (P) versus downwelling irradiance (Ed) and season for the two dominant corallines [Phymatolithon foecundum (Kjellman) Düwel et Wegeberg 1996 and Phymatolithon tenue (Rosenvinge) Düwel et Wegeberg 1996] representing> 90% of coralline cover. Differences in P‐Ed curves between the two species, the ice‐covered and open‐water seasons, or between specimens from 17 and 36 m depth were insignificant. The corallines were low light adapted, with compensation irradiances (Ec) averaging 0.7–1.8 μmol photons·m ? 2·s ? 1 and light adaptation (Ek) indices averaging 7–17 μmol photons·m ? 2·s ? 1. Slight photoinhibition was evident in most plants at irradiances up to 160 μmol photons·m ? 2·s ? 1. Photosynthetic capacity (Pm) was low, averaging 43–67 mmol O2·m ? 2 thallus·d ? 1 (~250–400 g C·m ? 2 thallus·yr ? 1). Dark respiration rates averaged ~5 mmol O2·m ? 2 thallus·d ? 1. In ice covered periods, Ed at 20 m depth averaged ~1 μmol photons·m ? 2·s ? 1, with daily maxima of 2–3 μmol photons·m ? 2·s ? 1. During the open water season, Ed at 20 m depth averaged ~7 μmol photons·m ? 2·s ? 1 with daily maxima of ~30 μmol photons·m ? 2·s ? 1. Significant net primary production of corallines was apparently limited to the 2–3 months with open water, and the small contribution of corallines to primary production seems due to low Pm values, low in situ irradiance, and their relatively low abundance in Young Sound.  相似文献   

16.
The inability of many organisms to degrade pollutants at low concentrations is a problem when selecting inocula for bioremediation of sites with these low concentrations. Thus, a study was conducted to determine the effect of low concentrations of p-nitrophenol (PNP) on growth of four PNP-degrading bacteria and their abilities to metabolize low concentrations of the compound in culture and samples from an oligotrophic lake. PNP did not increase the growth rates of Flavobacterium sp. M4, Pseudomonas sp. K, Flavobacterium sp. M1, and Pseudomonas sp. SP3 at concentrations of less than 2, 4, 10, and 100 ng/ml, respectively, when it was the sole added carbon source in culture, but it stimulated multiplication at higher concentrations. In liquid culture with the nitro compound as sole added carbon source, the four bacteria extensively mineralized PNP at 50 and 100 ng/ml, and three of the four degraded much of the substrate at 25 ng/ml. Pseudomonas sp. SP3 mineralized more than 20% but the two Flavobacterium strains converted less than 10% of the substrate to C02 at 10 ng/ml, and none of the three mineralized more than 5% at 1 and 5 ng PNP/ml. Under conditions where more than 99% of the radioactivity from 14C-PNP added at 1 ng/ml remained in solution, two of the isolates formed organic products. Pseudomonas sp. K had no activity at 1, 5, and 10 ng/ml. In contrast, when each of the bacteria was separately inoculated into samples of water from an oligotrophic lake and from a well in which PNP was not biodegraded, the bacteria were able to mineralize as little as 1 ng PNP/ml. The addition to a salts solution of 10 ng of glucose per ml resulted in mineralization of PNP at concentrations too low to be mineralized when the nitro compound was the sole source of added carbon. Bacteria may thus be able to mineralize substrates in natural waters at concentrations below those suggested by tests conducted in culture media, possibly because of the availability of other carbon sources for the bacteria.Offprint requests to: M. Alexander.  相似文献   

17.

The physical nature of fouling deterrence by the mussel Mytilus galloprovincialis was investigated using high-resolution biomimics of the bivalve surface. The homogeneous microtextured surface of M. galloprovincialis (1.94 ± 0.03 μm), the smooth surface of the bivalve Amusium balloti (0 μm), and moulds of these surfaces (biomimics) were compared with controls of smooth (0 μm) and sanded moulds, (55.4 ± 2.7 μm) and PVC strips (0 μm) in a 12-week field trial. The shell and mould of M. galloprovincialis were fouled by significantly fewer species and had significantly less total fouling cover than the shell and mould of A. balloti over a 12-week period. However, the major effects were between surfaces with and without microtopography. Surface microtopography, be it structured as in the case of M. galloprovincialis shell and mould, or random as in the case of the sanded mould, had a lower cover of fouling organisms than treatments without microtopography after 6 weeks. There was also no difference between the effect of the M. galloprovincialis mould and the sanded mould. The strong fouling deterrent effects of both these surfaces diminished rapidly after 6 to 8 weeks while that of M. galloprovincialis shell remained intact for the duration of the experiment suggesting factors in addition to surface microtopography contribute to fouling deterrence.  相似文献   

18.
1. Visually foraging fish typically exclude large zooplankton from clear‐water lakes and reservoirs. Do fish have the same effect in turbid waters, or does turbidity provide a refuge from visual predation? 2. To test the hypothesis that fish exclude large zooplankton species from turbid sites, I searched for populations of medium or large Daphnia species in turbid, fish‐containing reservoirs of south‐central Oklahoma and north‐central Texas, U.S.A., and surveyed the literature for accounts of Daphnia species in turbid habitats worldwide. 3. Only small Daphnia species and the exuberantly spined Daphnia lumholtzi were detected in the turbid reservoirs. The Daphnia species in the reservoirs are smaller than other Daphnia species that occur in the area but were not detected. An extensive survey of the literature suggests that large Daphnia may be found in the lakes of extreme turbidity [Secchi disk depth (SD) < 0.2 m] but that only small and spiny Daphnia are likely to occur in more typical turbid locations (1.0 m > SD > 0.2 m) unless some additional factor reduces the influence of fish predation in such sites. 4. The field samples from Texas and Oklahoma together with the literature review suggest that the effect of visually foraging planktivorous fish on the size structure of turbid‐water zooplankton communities may often be as strong or even stronger than the effect of fish on clear‐water zooplankton communities.  相似文献   

19.
During the spring of 1984, the ciliate Balantidium prionurium n. sp. was collected from the intestinal lumen of the herbivorous surgeonfish, Prionurus punctatus, from the Gulf of California. The symbionts were found in five fish from two well separated collection sites. Morphostatic specimens average 51 μm x 42 μm, and thus fall within the size range of several other fish balantidia. But the presence of Balantidium in a saltwater fish has not been reported, and such a host difference alone supports at least provisional recognition of this organism as a new species.  相似文献   

20.
ABSTRACT Thirteen eastern moles, Scalopus aquaticus, collected in West Texas were examined for coccidian oocysts; 11 (85%) were infected and eight (73%) of these had multiple infections representing two or more species. One cyclosporan, three eimerians, and two isosporans were studied and all are described as new species. Sporulated oocysts of Cyclospora megacephali n. sp. were subspheroidal, 18.5 × 15.7 (14–21 × 12–18) μm; they had sporocysts pointed at one end with Stieda bodies nearly as wide as the sporocysts themselves, and were 15.0 × 7.2 (11–17 × 6–9) μm; C. megacephali was found in four (31%) hosts. Sporulated oocysts of Eimeria scalopi n. sp. were spheroidal to subspheroidal, 13.6 × 12.6 (11–17 × 11–15) μm with sporocysts lemon-shaped, 8.7 × 5.5 (7–10 × 4–7) μm; it was found in six (46%) hosts. Sporulated oocysts of Eimeria aquatici n. sp. were asymmetrically ellipsoidal, 17.0 × 10.6 (14–20 × 9–14) μm, with sporocysts elongately ovoidal, 9.0 × 5.2 (8–11 × 4–6) μm; it was found in two (15%) hosts. Sporulated oocysts of Eimeria motleiensis n. sp. were subspheroidal, 17.0 × 15.3 (15–20 × 13–18) μm with sporocysts ovoidal, 10.7 × 6.8 (10–13 × 6–8) μm; it was found in seven (54%) hosts. Sporulated oocysts of Isospora motleiensis n. sp. were spheroidal to subspheroidal, 13.6 × 12.0 (10–17 × 8–15) μm with sporocysts broadly ovoidal, 9.5 × 6.7 (7–11 × 4–8) μm; it was found in nine (69%) hosts. Sporulated oocysts of Isospora aquatici n. sp. were subspheroidal, 20.9 × 18.4 (15–24 × 13–21) μm with sporocysts ellipsoidal, 11.8 × 9.0 (9–14 × 7–11) μm; it was found in two (15%) hosts.  相似文献   

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