| 1. |
- Björn, Lars Olof, et al.
(författare)
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Diatoms: Their strange evolution and remarkable properties
- 2009
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Ingår i: Acta Biologica Slovenica. - 1408-3671. ; 52:2, s. 33-40
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Forskningsöversikt (refereegranskat)abstract
- We review some new literature on diatoms, with emphasis on genomics, evolution, ecology and biomimetic nanotechnical applications. Diatoms account for a substantial part of the photosynthetic production on this planet, and their genome is a mosaic of contributions from different sources. They occupy very diverse ecological niches, and may have been the first organisms to carry out C4 photosynthesis. Their frustrules (silica enclosures) with their elaborate sculpturing make it possible to follow the occurence of different forms back in time, and the frustrules is also the main reason that they are interesting for biotechnology. Izvleček: Prispevek je pregled novih virov o kremenastih algah s povdarkom na genomiki, evoluciji, ekologiji ter biomimetični nanotehnološki aplikaciji. Kremenaste alge prispevajo velik delež k fotosintezni produkciji našega planeta. Njihov genom je mozaik elementov različnega izvora. Zasedajo različne ekološke niše, in verjetno so bile prvi organizmi s C4 način fotosinteze. Njihove frustule (silikatni ovoji) z izdelanimi raznolikimi vzorci omogočajo sledenje različnih oblik v zgodovini in prav frustule so tiste, zaradi katerih so kremenaste alge zanimive za biotehnologe.
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| 2. |
- Cronberg, Gertrud, et al.
(författare)
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New species of Uroglena and Ochromonas (Chromulinales, Chrysophyceae) from Estonia
- 2005
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Ingår i: Nova Hedwigia: Zeitschrift für Kryptogamenkunde. - 0029-5035. ; Suppl. 128, s. 43-63
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- During the spring of 2003 ninety-five water bodies in southeastern Estonia were surveyed for chrysophytes. The sampling was carried out as the ice broke up, when, within two weeks, the water temperature rose from 3 degrees C to 13 degrees C. Large lakes to small pools of different water chemistry were investigated. The plankton collected was studied alive within a few hours after sampling. Preparations for scanning electron microscopy (SEM) were made from fresh samples and later also from material preserved in Lugol's solution. About 95% of the water bodies contained chrysophytes. Species belonging to the genera Chrysosphaerella, Dinobryon, Mallonionas, Synura, Ochromonas, Paraphysomonas, Spiniferomonas, Uroglena and Uroglenopsis were recorded. The genus Uroglena was frequent and recorded in 30% of the localities studied. Mass development of different Uroglena species was found in several waterbodies. Many populations had developed stomatocysts (statospores, cysts) of different morphology, and, using LM, smooth stomatocysts and stomatocysts with long spines could be recognised. However, using SEM, it was shown that also the smooth stomatocysts had short spines. Four new species of Uroglena were found and are described here. Uroglena estonica and U. spinosa had long spines while U. kukkii and U. pikamae had very short spines. In addition, mass development of stomatocysts of an Ochromonas was recorded in two lakes. This species had similarities with Ochromonas stellaris, but differed in stomatocyst ornamentation, and is also described as a new species, O. magnifica.
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| 3. |
- Cronberg, Gertrud
(författare)
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The life cycle of Gonyostomum semen (Raphidophyceae)
- 2005
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Ingår i: Phycologia. - 0031-8884. ; 44:3, s. 285-293
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Tidskriftsartikel (refereegranskat)abstract
- Gonyostomum semen (Raphidophyceae) is today one of the most common flagellates in humic lakes ill Sweden and appears regularly in 30% of these lakes. The first mass development of this alga was recorded in 1948 in Lake Helgasjon, South Sweden. In this paper the life cycle of Gonyostomum is described for the first time. During the winter Gonyostomum survived as resting cysts on the surface of the bottom sediment. In spring (April to May) meiosis took place in the cysts, and on excystment two haploid gametes appeared. After a period of mobility, the gametes formed pairs. The gametes then fused, and a new diploid Gonyostomum cell developed. The vegetative stage of Gonyostomum, which was seen during the summer period (May-October), is thus the diploid phase. During this period normal, longitudinal cell division took place. Under unfavourable conditions, temporary cysts Could be formed. Cyst formation started from the centre of the cell, which swelled and became spherical. This was a thin-walled, temporary cyst, which was mobile and, like ordinary cells, had one flagellum protruding forward and one trailing behind. The temporary cysts could accumulate and settle in large clusters where the flagella were lost or had become invisible. When favourable conditions reappeared, the temporary cysts divided and formed two new gametes. In autumn, when the water temperature decreased to below about 10 degrees C, the temporary cysts went into dormancy and became resting cysts. The cyst wall thickened, and a brown body appeared within the cyst. Below 4-6 degrees C no vegetative cells were found.
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| 4. |
- Cronberg, Gertrud, et al.
(författare)
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Undersokning av planktonsamhället i regionala referenssjöar i Skåne län,1969-2007.
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- SammanfattningI Skane har sex sjoar valts ut som regionala referenssjoar. Referenssjoar for i forsta handkalkade och forsurade sjoar ar Skaravattnet, Liasjon, Svanshalssjon, Faglasjon ochLarkesholmssjon, alla belagna i norra Skane. Referenssjo till i forsta hand naringsrikaslattsjoar ar Ellestadssjon som ar belagen i sodra Skane.Syftet med denna undersokning har varit att analysera artforekomst i insamlade prover ochsammanstalla resultaten for att sakra 25 ars vaxtplanktondata fran regionala referenssjoar iSkane.Samtliga fem referenssjoar i norra Skane var, eller utvecklades under den studerade periodentill, ”Gonyostomum-sjoar”.Liasjon dominerades samtliga undersokta ar (1982, 1993-2007) avGonyostemum semen,vaxtplanktonsamhallet var under hela perioden mycket artfattig och indikerade att vattnet varextremt surt.Skaravattnet dominerades hela undersokningsperioden(1982, 1993-2007) avGonyostemumsemenmen med inslag av pansarflagellater fram till millennieskiftet. Darefter okade badebiomassan av vaxtplankton och dominansen avGonyostemum semen.Tyvarr saknades prover fran 80-talet i Svanshalssjon. Fran 1993 och framat domineradeGonyostemum semenmen i Svanshalssjon utgjorde aven pansarflagellater en ganska stor delav biomassan under hela undersokningsperioden (1993-2007).Varken Faglasjon eller Larkesholmssjon var utpragladeGonyostemum sjoar 1982 istalletdominerades sjoarna vid detta undersokningstillfalle av pansarflagellater. Darefter har detskett en forandring i artsammansattningen i sjoarna. Fran 1993 och framat domineradesFaglasjon avGonyostemum semen och fran 2002 och framat dominerades LarkesholmssjonavGonyostemum semen.Skillnaden mellan Ellestadssjon och de ovriga sjoarna var pataglig. Ellestadssjon domineradesav blagrona alger och/eller kiselalger. De hogsta biomassorna, som uppmattes i denna studie,registrerades i Ellestadssjon. Denna sjo ar en naringsrik slattsjo i sodra Skane. Detvaxtplankton, som patraffades, ar typiska for de naringsrika sjoarna pa sydskanska slatten.En dominans avGonyostomum ar negativt for vattenkvaliteten, bade nar det galler rekreationoch dricksvattenproduktion. Slemmet franGonyostomum kan klibba igen galarna pa fisk ochkraftor och satta igen filtreringsorganen hos vattenloppor. Dessutom arGonyostomum-sjoarartfattigare an sjoar utan forekomst avGonyostomum. Detta kan man tydligt se i Skaravattnetoch Larkesholmssjon. NarGonyostomum okar i dessa sjoar, sa minskar antalet andravaxtplanktonarter.
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| 5. |
- Herrmann, Jan, et al.
(författare)
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Hornsjöns biologi 2004-2005
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det kan troligen sägas att en höjning av vattenståndet med ca 10 cm bör inte ha allvarligare konsekvenser för sjöns biologi. Möjligen kan erhållas viss positiv effekt; igenväxning kanske kan bromsas något, se avsnittet om Vegetation. Men det bör också framhållas att gäddans situation i sjön och dess vandringsmöjligheter och leksituation bör beaktas och utvecklas i samband med planerade åtgärder.Vissa av de biologiska parametrar som nu studerats i Hornsjön har förut gjorts studier av, nämligen vegetation (Wallsten 1979), plankton och bottenfauna (Berggren 1979), fåglar (Rodebrand 1979) samt fisk och plankton (Aspengren 1985, Troschke 1987). För dessa organismgrupper görs vissa jämförelser mellan 70-talet och 2004/2005, dvs oftast knappt 30 år. Vissa jämförelser har gjorts med nämnda publikationer. En mer omfattande analys avses göras i en planerad rapport om sjöns biologi. Där skall alla kända biologiska fakta sammanfattas och kommenteras.
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| 6. |
- Ikavalko, J, et al.
(författare)
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CHRYS 2004 - Preface
- 2005
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Ingår i: Nova Hedwigia: Zeitschrift für Kryptogamenkunde. - 0029-5035. ; 128
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Mhlanga, L, et al.
(författare)
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Observations on limnological conditions associated with a fish kill of Oreochromis niloticus in Lake Chivero following collapse of an algal bloom
- 2006
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Ingår i: African Journal of Ecology. - : Wiley. - 1365-2028 .- 0141-6707. ; 44:2, s. 199-208
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Tidskriftsartikel (refereegranskat)abstract
- Possible causes of deaths of Oreochromis niloticus in Lake Chivero were examined in relation to changes in limnological conditions monitored over a 25-month period. The fish deaths coincided with the collapse of an algal bloom that had developed and builtup in the lake for 8 months. Chlorophyll a and dissolved oxygen increased to average concentrations of 42.4 mu g l(-1) and 10.9 mg l(-1) respectively prior to the collapse of the bloom. Dissolved oxygen decreased when the bloom started to die off and coincided with the fish deaths when the average surface dissolved oxygen concentration in the lake was 3.9 mg l(-1) and was at a depth of 5 m < 2 mg l(-1). Mortality probably resulted from depressed oxygen levels caused by the high oxygen demand from the massive algal die-off and released algal toxins. This is the first time that die-off of algae has been linked to fish-kills in Lake Chivero as occurs in other hypereutrophic systems.
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| 8. |
- Mussagy, Aidate, et al.
(författare)
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An experimental study of toxin production in Arthrospira fusiformis (Cyanophyceae) isolated from African waters
- 2006
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Ingår i: Toxicon. - : Elsevier BV. - 0041-0101. ; 48:8, s. 1027-1034
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Tidskriftsartikel (refereegranskat)abstract
- Arthrospira is one genus of cyanoprokaryota for which information on toxin production exists for only a few strains. The purpose of this study was to investigate whether strains of Arthrospira fusiformis produce intracellular toxic compounds such as microcystins and anatoxin-a. The study was based on three strains of Arthrospira, two strains isolated from wastewater ponds in Mozambique and one from Lake Nakuru, Kenya. These strains were cultivated experimentally in different light intensities and salinities. Microcystins were analysed by ELISA and HPLC and anatoxin-a by HPLC. Toxicity analysis of the three strains, following the growth cycle, detected neither microcystins nor anatoxin-a. The results indicated that the strains selected were not toxigenic under the experimental conditions applied. Thus, the strains of A. fusiformis tested in the present study could be considered candidates for use in different applications such as in food supplements and in aquaculture.
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| 9. |
- Nguyen, Lien Thi Thu, et al.
(författare)
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Planktic cyanobacteria from freshwater localities in ThuaThien-Hue province, Vietnam. II. Algal biomass and microcystin production
- 2007
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Ingår i: Nova Hedwigia: Zeitschrift für Kryptogamenkunde. - : Schweizerbart. - 0029-5035. ; 85:1-2, s. 35-49
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Tidskriftsartikel (refereegranskat)abstract
- A survey of cyanobacteria was carried out from February to August of 2004 along the Huong River and Hoamy Reservoir which supply part of the City of Hue, Vietnam with drinking water: also at some localities in the vicinity of the City of Hue. Quantitative analyses and screening for microcystin by ELISA and HPLC were done both in natural samples and in cultured cyanobacteria. The total biomass of cyanobacteria ranged from 0 to 3039 mg L-1 [wet weight (ww)] with Arthrospira massartii, Jaaginema sp., Merismopedia spp., Microcystis spp., Oscillatoria perornata, and Planktothrix zahidii as the dominating species. In the water samples, microcystins detected by ELISA varied between 0 and 76.2 mu g L-1. Concentrations above 1 mu g L-1, which is considered the safety limit for drinking water by WHO, were not found in the drinking water resources. Cultured strains of Microcystis aeruginosa, M. panniformis, M. botrys and Pseudanabaena cf. moniliformis were shown by ELISA to produce microcystins. The major microcystins produced were microcystin-LR and -RR, as detected by HPLC.
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