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Abstract PROFOUND differences in structure and function separate the prokaryotic cyanobacteria blue-green algae from eukaryotic algae and plants, whereas oxygenic photosynthesis is considered to distinguish the cyanobacteria and eukaryotic plants from the other phototrophic bacteria.
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Article Google Scholar 5 Cohen, Y. Article Google Scholar Download references. Author information Author notes B. Archaea reproduce asexually by binary fission, fragmentation, or budding; unlike bacteria and eukaryotes, no known species forms spores.
Archaea were initially viewed as extremophiles living in harsh environments, such as hot springs and salt lakes, but they have since been found in a broad range of habitats, including soils, oceans, and marshlands. They are also part of the human microbiota, found in the colon, oral cavity, and skin. Archaea are particularly numerous in the oceans, and the archaea in plankton may be one of the most abundant groups of organisms on the planet.
No clear examples of archaeal pathogens or parasites are known, but they are often mutualists or commensals. One example is the methanogens that inhabit human and ruminant guts, where their vast numbers aid digestion. Methanogens are also used in biogas production and sewage treatment, and biotechnology exploits enzymes from extremophile archaea that can endure high temperatures and organic solvents. Members of the domain Eukarya are called eukaryotes. A eukaryote is any organism whose cells have a cell nucleus and other organelles enclosed within membranes can be unicellular or multicellular organisms.
The defining feature that sets eukaryotic cells apart from prokaryotic cells Bacteria and Archaea is that they have membrane-bound organelles, especially the nucleus, which contains the genetic material enclosed by the nuclear membrane.
Eukaryotic cells also contain other membrane-bound organelles such as mitochondria, endoplasmic reticulum and the Golgi apparatus. In addition, plants and algae contain chloroplasts. Unlike unicellular archaea and bacteria, eukaryotes may also be multicellular and include organisms consisting of many kinds of tissue and cell types.
Eukaryotes can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion. In mitosis, one cell divides to produce two genetically identical cells. In meiosis, DNA replication is followed by two rounds of cell division to produce four haploid daughter cells.
These act as sex cells gametes. Each gamete has just one set of chromosomes, each a unique mix of the corresponding pair of parental chromosomes resulting from genetic recombination during meiosis. Eukaryotes evolved approximately 1. Viruses are not part of the three-domain system. Spirillum is a genus of Gram-negative bacteria Figure Members of the genus Spirillum are large, elongate, spiral shaped, rigid cells.
Some have tufts of amphitrichous flagella at both poles. They are microaerophilic and usually found in stagnant freshwater rich in organic matter. Treponema is a genus of spiral-shaped Gram-negative bacteria Figure The major treponeme species of human pathogens is Treponema pallidum, whose subspecies are responsible for diseases such as syphilis, bejel, and yaws.
Clostridium botulinum is a Gram-positive, rod-shaped, anaerobic, spore-forming, motile bacterium with the ability to produce a neurotoxin known as botulinum toxin. We expect the daphnids to exhibit differential incorporation of the P and C if the animals could discriminate in the biochemical aspects of food. The higher assimilation efficiency of P than C from Oscillatoria by the daphnids could compensate for the P-deficient diet comprised of both Oscillatoria and detritus, in view of the homeostatic needs of daphnids [see Gulati and DeMott, ; DeMott et al.
As mentioned above, it is now well known that the clearance rates of large-bodied daphnids are more likely to be depressed by cyanobacterial filaments than those of the smaller ones Gliwicz and Siedlar, On the other hand, Dawidowicz, who fed Daphnia magna on Oscillatoria filaments from Lake Loosdrecht Dawidowicz, , observed that the daphnids caused both reduction in filament numbers and the filament length.
This implies that the feeding activity of the daphnids makes these filaments more accessible to other filter-feeding cladocerans; and that the detritus formation is likely to make these filaments more vulnerable to be used as a substrate by heterotrophic bacteria. We offered the daphnids the live filaments and detrital particles of comparable length.
The detrital filaments, however, are probably less consistently elongated in the suspension than are the live filaments. It is, however, assumed that the size comparability would preclude the inhibitory effect of length-related factors.
Despite the difficulties of preparing shorter, live filaments of reproducible length, the disparity between the uptake rates of detritus and live filaments was substantially reduced. All the food uptake rate parameters are significantly higher for Daphnia feeding on the shorter Oscillatoria filaments than on the longer filaments. Thus, in D. Lower ingestion and filtering clearance rates for D.
Also, DeBernardi et al. Shorter filaments also result in an increase in SCR than long filaments, notwithstanding the presence of P or C tracers in the food Figure 2a. Nevertheless, the assimilation efficiency of shorter filaments of O. If this was achieved by egesting relatively more C or by incorporating relatively more P in the gut to keep the body's C:P ratio constant about , has been the subject of our other study.
This is certainly quite likely in homeostatic consumers such as Daphnia Sterner and Hessen, Thus, the shorterfilaments do appear to improve food uptake but this does not change our conclusion that the detritus was ingested much better than live filaments. On the other hand, assimilation efficiency of Daphnia feeding on detritus and shorter Oscillatoria filaments did not differ, though we had expected a clearly lower assimilation efficiency for detritus because of the expected lower nutritive value of detritus compared with live filaments.
Lastly, our data confirm that the difference in nutritive value between live Oscillatoria and detritus did not play an important role in the latter's greater uptake. Because the daphnids are relatively insensitive to food quality in their food collection mechanisms, they are likely to feed more efficiently on finer detrital particles so that they are categorized as detritivores rather than as herbivores Kerfoot and Kirk, The quality of detritus can vary markedly with its origin, age and colonization by microbes DeMott, , and it is generally regarded as inferior to live algae as food for daphnids Lampert, b.
However, the observations that detritus derived from dying and decaying cyanobacteria can be effectively ingested and assimilated can have important consequences for the growth and reproduction of daphnids in the field. Interestingly, in an other study from our laboratory it has been demonstrated that the detritus derived from O. In other words, these decaying filaments overgrown by bacteria were found to become a better food source for filter-feeding cladocerans. Also laboratory studies demonstrate increased reproduction of cladocerans concomitant with the decline of cyanobac-teria, e.
These studies are also supported by field observations on cladoceran reproduction during the collapse of cyanobacterial blooms [see reviews Sommer et al. Such studies complement our findings that detritus derived from Oscillatoria is both ingested and assimilated better by the daphnids.
Both the present study and the published literature on the edibility of filamentous cyanobacteria for Daphnia show that despite the interference with the food collection and ingestion processes, cyanobacteria can be an important food source for daphnids in lakes. That the cyanobacterial detritus and shorter cyanobacterial filaments can be relatively better ingested, are important findings of this study. The cyanobacteria may form an important link in the food chain in lakes in which they are very abundant, especially considering that detritus formation considerably improves the edibility as well as nutritional value of cyanobacteria for daphnids.
It is quite likely that in lakes dominated by filamentous cyanobacteria, it is not the interference or edibility of these organisms alone, but more importantly, the low nutritive value of the cyanobacteria and increase in predation by fish, or both, that would help us explain better the virtual absence of daphnids, particularly of the larger-bodied Daphnia spp. Summary of grazing experiments with Daphnia galeata, using food mixtures of Oscillatoria limnetica and detritus in different concentrations and parameters measured.
Effect of sonification 50 s on the filament lengths of Oscillatoria limnetica. Specific clearance rates of Daphnia galeata on sonified S and non-sonified NS filaments labelled with two tracers: 14 C black bars ; 32 P hatched bars. A comparison of assimilation efficiencies of Daphnia galeata on short filaments sonified of Oscillatoria limnetica using two radioisotopes a. Feeding of Daphnia galeata on mixtures of sonified detritus and long non-sonified Oscillatoria limnetica in three experiments a ; see also Table 1 for details of the experiments 1, 2 and 3.
Feeding replicates Exp. The concentrations of the two food types in the mixture are shown. As in a but with the relative food concentrations of the two food types in the mixture changed and total food concentration decreased b.
See also in Table 1 under experiments 4 and 5. The manuscript benefited greatly from the constructive criticism and suggestions of especially Bill DeMott and Michael Arts and the reviewers' comments. Also, two colleagues at the Centre of Limnology Nieuwersluis , Koos Vijverberg and Wolf Mooij, read an earlier version of the typescript. Klass Siewertsen helped in preparing the illustrations and Irma Buenk in some of the grazing experiments.
Publication No. Bern L. Plankton Res. Bronkhorst, M. Buenk, I. Burns, C. New Zealand J. Chesson, J. Ecology , 64 , — Dawidowicz, P. Hydrobiologia , , — DeBernardi R. DeMott, W. In Sommer, U. Springer-Verlag, Berlin, pp. In Hughes, R. Blackwell Scientific, Oxford,pp. Epp, G. Fallon, R. Gliwicz, Z. Gliwiciz, Z. Ecology , — Gons, H. Hydrobiologia , , 51 — Gulati, R. Hydrobiologia , 95 , — Hydrobiologia , , 69 — Freshwater Biol , 38 , — Hanazato, T. Haney, J. Hartmann, H. Hoogveld, H.
Holm, N. Kerfoot, W. Kirk, K. Photosynth Res. Blue light enhance the pigment synthesis in cyanobacterium Anabaena ambigua rao nostacales , J Agrl Bio Sci.
Figure 2 - Total measured protein content of Oscillatoria agardhii subjected to different culture conditions. Each bar is an average of three replicates. The molecular weights of these polypeptides were ranging from The major polypeptide bands were around Similar to the control, samples of all the treatment were subjected to gel analysis.
Similar polypeptide profiles were found in all the lanes of control and different culture condition samples irrespective of varietal differences Table 1. Chan et al. The proteomic study shows both the constancy of protein profiles and variability of the relative abundance of some peptides under different culture conditions in the O.
The light dark photoperiod may be more beneficial than other regimes, as cell number is sustained longer in exponential phase Seyfabadi et al. However, two novel bands of Thumbnail Table 2 - Expression of unique peptides in Oscillatoria agardhii in different culture conditions. Another novel band of A novel protein of The Three polypeptides such as The gene expression for these peptides was inhibited in the constant light probably due to photoinhibition Jensen and Knutsen Jensen S and Knusten G.
Table 2. The latter is caused by the photo-oxidation reaction inside the cell due to excess light that cannot be absorbed by the photosynthetic apparatus Richmond The photoperiod and temperature could increase or decrease the level of protein expression.
Under the optimum condition, many proteins over-expressed and under the adverse condition some peptides expression was inhibited. The density of bands show the quantity of particular peptide as suggested, which indicated that this peptide was expressed in large amount and light band showed low level expression. The expression of A novel Due to high metabolic activity in the both hour light dark condition most proteins The other two peptides Expression of some other peptides depended on the photoperiod and the intensity of light e.
Two novel proteins These results tended to agree with Rajendran et al. These studies were conducted with a view to determine the deleterious and differential effects of temperature and photoperiod on the growth and protein profiling of O.
The proteomic study of the differential protein profiles under different environmental conditions revealed that O. Hence some novel proteins could be expressed and expression of some existing peptide could be repressed. In continuous light, algal growth might be reduced due to photoinhibition and photo-oxidation. Abrir menu Brasil. Brazilian Archives of Biology and Technology.
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