Rotifers Research Articles

EFFECTS OF METHAMIDOPHOS AND ACEPHATE ON EXPERIMENTAL POPULATION DYNAMICS OF ROTIFER <I>BRACHIONUS CALYCIFLORUS</I>

Effects of sublethal levels(0.01,0.1,1.0,10.0,100.0,1000.0 and 10000.0 μg/L) of organophosphorus insecticides including methamidophos(O,S-Dimethyl phosphoramidothioate,CAS No.10265-92-6) and acephate(O,S-Dimethyl acetylphosphoramidothioate,CAS No.30560-19-1) on population dynamics of rotifer Brachionus calyciflorus were studied by 3-day population growth test at 25±1℃,in dark,and with 3.0×106 cells/mL of S.obliquus as the rotifers' food.The results showed that both methamidophos and acephate influenced significantly the population growth rate,the ratio mictic females/amictic females and the mictic rate of the rotifers.Methamidophos influenced markedly the carrying-egg females/non-carrying-egg females of the rotifers,but acephate did not.Compared to the controls,100.0 μg/L methamidophos and 1.0—10000.0 μg/L acephate increased significantly the population growth rate,but the reverse was true for 1,000.0 and 10,000.0 μg/L methamidophos.1,000.0 μg/L methamidophos increased significantly the ratio carrying-egg females/non-carrying-egg females.0.1 μg/L methamidophos and 10.0—10000.0 μg/L acephate increased significantly the ratio mictic females/amictic females,and both 0.1 μg/L methamidophos and 10 μg/L acephate increased significantly the mictic rate.10.0—10000.0 μg/L acephate significantly increased the resting egg production.The above-stated results indicated that sublethal levels of methamidophos and acephate influenced significantly the population dynamics of B.calyciflorus.

First description of the serotonergic nervous system in a bdelloid rotifer: Macrotrachela quadricornifera Milne 1886 (Philodinidae)

Class Bdelloidea of phylum Rotifera comprises aquatic microinvertebrates that are known for both obligate parthenogenesis and for resisting desiccation through a dormant reversible state. In the frame of an investigation about the role of the nervous system in controlling life cycle, reproduction and dormancy, we describe the serotonergic system of a bdelloid, Macrotrachela quadricornifera, using serotonin immunohistochemistry and confocal laser scanning microscopy. Serotonin immunoreactivity is present in the cerebral ganglion, lateral nerve cords and peripheral neurites. The cerebral ganglion consists of perikarya that send neurites cephalically to the rostrum and corona. A pair of neurites exits the cerebral ganglion as lateral nerve cords, and proceeds caudally to the pedal ganglion where additional neurites enter the foot. Based on the location of serotonergic immunoreactivity, we hypothesize that the neurotransmitter is involved in both motor activity (e.g., ciliary beating, inchworm-like locomotion) and sensory activity. A comparison between the serotonergic nervous systems of M. quadricornifera and species of Monogononta reveals differences in the numbers and patterns of cerebral perikarya, peripheral perikarya, and periperhal neurites. These differences may have functional significance for understanding adaptations to specific environments and/or systematic significance for reconstructing the rotiferan ground pattern.

ROTIFERS AND HUBBELL'S UNIFIED NEUTRAL THEORY OF BIODIVERSITY AND BIOGEOGRAPHY

. This paper reviews several neutral models as possible mechanisms for simulating and explaining so-called “hollow curve distributions.” The models include simple random assignment, MacArthur's broken stick, Preston's lognor-mal (but as simulated by Sugihara), Fisher's logseries, and Hubbell's unified neutral theory of biodiversity and biogeog-raphy. Each model is fitted to data describing the distribution of genera over families in the phylum Rotifera.

Rotifer Gene Scavenging

Rotifer Gene Scavenging

Efeitos de fertilização na biomassa e qualidade nutricional do zooplâncton utilizado para alimentação de alevinos na estação de hidrobiologia e piscicultura de Furnas, MG

This investigation aimed to evaluate the effects of organic matter (pig manure) and nutrients on the structure of zooplankton in plankton tanks at Furnas hatchery station. Zooplankton is commonly used as food resource of Hoplias lacerdae fry. Total lipid levels, density and biomass of zooplankton were analyzed in two plankton tanks twice a week during 60 days. Water temperature, pH, dissolved oxygen and electric conductivity were also monitored daily. Chlorophyll-a, total phosphorus, ammonium and total kejdahl nitrogen (TKN) were measured on a weekly basis. In the first thirty days, nutrient fertilization was performed every five days. In the last thirty days, there was no external input of nutrient or organic material. The interruption of external nutrient load caused a clear and conspicuous modification in most physical and chemical variables as well as in the zooplankton. There was an abrupt and conspicuous reduction in the conductivity, ammonium , TKN, total phosphorus and chlorophyll. On the other hand, dissolved oxygen and pH increased. Biomass of total zooplankton also showed a brief peak following the interruption of external nutrient flux. During this period, the cladocera Moina and the rotifer Brachionus calyciflorus became the dominant zooplanktons. At the end of the study, the ciclopods became once more the dominant organisms, although there was a higher proportion of immature stages. Levels of total lipids of zooplankton remained at lower levels (6-10%) throughout the covered period, suggesting that zooplankton was eating food particles of lower nutritional quality. Nevertheless, the study demonstrates that nutrient input is essential for maintaining zooplankton at adequate levels. However, lower lipid levels also suggest that the quality, quantity and frequency of this nutrient input showed be thoroughly revised.

From Observation to Theory with Resurrected Rotifers

From Observation to Theory with Resurrected Rotifers

Food and feeding habits of the african electric fish ( Mormyrus rume) in Anambra River, Nigeria

The food and feeding habits of 400 specimens of the African electric fish -Mormyrus rume (Osteichthyes: Mormyridae) in Anambra river, Nigeria were studied from October, 2004 to March, 2006. Fish specimens were collected monthly at Otuocha and Ogurugu areas of Anambra River using hook and line, traps, gillnets and cast nets of various mesh sizes. Out of the nine (9) categories of food consumed, the most dominant group was the insecta, with the index of food significance (IFS) = 69.49; while the least was the rotifera, with IFS= 0.42. Variation in the stomach fullness condition showed that 17 (4.25%) of the stomachs studied were empty, 108 (27.0%) were full and 275 (68. 75 %) were partially filled. Stomachs were generally full during the rains when feeding intensity was high while empty stomachs and partially filled stomachs predominated in the dry season. Food richness and diet breadth were significantly higher in females than males and were also higher in wet than dry season (P < 0.05). Key words : Mormyrus rume,, food and feeding habit, Anambra River.

Rotifer fauna of Seli Stream (Elazığ-Turkey) and analysis with some biodiversity indexes.

Rotifer fauna of Seli Stream (Elazığ-Turkey) and analysis with some biodiversity indexes.

Identification of exocytotic membrane proteins in three rotifer species

We confirmed the presence and expression of exocytotic membrane proteins: Syntaxin-1, Syntaxin-4, SNAP-23, and SNAP-25 in the rotifers Brachionus calyciflorus, Lecane quadridentata, and Philodina roseola. These proteins were identified by immunohistochemistry and immunoblot analysis using antibodies against Syntaxin-1, Syntaxin-4, SNAP-23, and SNAP-25. The presence of these proteins were observed mainly in regions of the nervous, reproductive, and glandular systems of these rotifer species, which underlines the fundamental role of exocytotic docking and fusion membrane proteins in the vesicular release of secretory proteins. The immunoblot analysis confirmed the expression of Syntaxin-1, Syntaxin-4, and SNAP-23 in the three rotifer studied, but not of SNAP-25. This study contributes to rotifer biology by revealing the presence of conservative exocytotic machinery such as SNAREs proteins in the phylum Rotifera, including members of the Class Bdelloidea the highest taxa of metazoans where sexual reproduction does not exist.

Annotated checklist of the rotifers (Phylum Rotifera), with notes on nomenclature, taxonomy and distribution

Phylum Rotifera comprises about 2030 known species classified in three main groups, the marine Seisonida (3 species), the Monogononta (1570 species) and the unique, exclusively parthenogenetic Bdelloidea with 461 clonal species. Here I present an annotated checklist of the taxon, giving the global distribution of the valid species. This checklist contains over 3,000 available names at the genusand species-group level, including valid names and a non-comprehensive list of synonyms. A number of taxonomic and nomenclatural suggestions following from the review is presented. Suggestions include several new synonyms and two nomina nova: Dissotrocha kostei for Dissotrocha aculeata Koste, 1996 non Ehrenberg, 1838 (stat. nov., ex. Dissotrocha hertzogi aculeata) and Lepadella zigzag for Lepadella bractea Myers, 1934 non (Ehrenberg, 1838). This contribution also describes features of an on-line, global names database of the Rotifera, on which this checklist is based.

Effect of Kind and Dosage of Enrichment Materials on the Nutritional Quality of Rotifers Especially n3-HUFA

&lt;p&gt;This experiment was conducted to evaluate the quality of rotifer enriched with four kinds of enrichement materials from the stand point of essensial fatty acids. Rotifer was enriched at 24 - 25&lt;sup&gt;o&lt;/sup&gt;C for 18 hours at a density of 1000 ind/ml. Rotifers were treated by four kinds of enrichment materials such as oleic acid (R-OA), two different density of &lt;em&gt;Nannochloropsis oculata&lt;/em&gt;, (4x10&lt;sup&gt;7&lt;/sup&gt; and 16x10&lt;sup&gt;7&lt;/sup&gt; cell/ml; R-N18 and R-N42) two different levels of eicosapentaenoic acids (EPA) triglyceride type (EPA-TAG) (20 and 40 ml/ml; R-E20, R-E40) and two different level of EPA ethyl ester (EPA-EE) (R-EE25 and R-EE50%) respectively. Rotifers enriched with &lt;em&gt;Nannochloropsis&lt;/em&gt; &lt;em&gt;oculata&lt;/em&gt; and EPA-EE type have a similar profile of essensial fatty acid especially on n3-HUFA that dominated by EPA, while DHA was in a trace amount or not detected. In addition &lt;em&gt;Nannochloropsis&lt;/em&gt; &lt;em&gt;oculata&lt;/em&gt; as an enrichment material showed the highest population density of rotifers during enrichment periods. Rotifer enriched with EPA-TAG has a more complete of essential fatty acid profile compared to other enrichment materials due to their contained both of EPA and DHA. We conclude that rotifer enriched with EPA-TAG as enrichment material showed the best nutritional quality of rotifers from the stand point of essential fatty acid.&lt;/p&gt; &lt;p&gt;Key words : Rotifers, enrichment, eicosapentaenoic acid, docosaheksaenoic acid, n3-HUFA&lt;/p&gt; &lt;h2&gt; &lt;/h2&gt; &lt;h2&gt;ABSTRAK&lt;/h2&gt; &lt;p&gt;Penelitian ini dilakukan untuk mengetahui profil asam lemak rotifera yang diperkaya dengan berbagai macam jenis dan dosis pengkaya. Rotifera dengan kepadatan 1000 ind./ml diperkaya dengan bebagai bahan pengkaya seperti asam oleat (R-OA); &lt;em&gt;Nannochloropsis oculata &lt;/em&gt;dengan kepadatan 4x10&lt;sup&gt;7&lt;/sup&gt; dan 16x10&lt;sup&gt;7&lt;/sup&gt; sel/ml (R-N18 dan R-N42); eicosapentaenoic acid (EPA) tipe triglicerida (EPA-TAG) dengan dosis 20 dan 40 μl (R-E20 dan R-E40) dan EPA tipe ethyl esther (EPA-EE) dengan dosis 25 dan 50 μl per liter (R-EE25 and R-EE50%). Rotifera diperkaya selama 18 jam pada suhu 24-25&lt;sup&gt;o&lt;/sup&gt;C. Rotifera yang diperkaya dengan &lt;em&gt;Nannochloropsis oculata&lt;/em&gt; serta EPA-EE memiliki kesamaan profil asam lemak terutama pada incorporasi EPA, sedangkan DHA terkandung pada jumlah yang kecil atau tidak terdeteksi. Adapun rotifera yang diperkaya dengan EPA-TAG memiliki profil asam lemak yang lebih lengkap terutama ditinjau dari kandunga EPA dan docosahexaenoic acid (DHA) nya. Selanjutnya rotifera yang diperkaya dengan &lt;em&gt;Nannochloropsis&lt;/em&gt; &lt;em&gt;oculata&lt;/em&gt; memiliki populasi yang tertinggi dibanding perlakuan lainnya. Dari penelitian ini dapat disimpulkan bahwa pengkayaan dengan EPA-TAG memiliki kualitas rotifera yang terbaik ditinjau dari sisi kelengkapan kandungan asam lemaknya.&lt;/p&gt; &lt;p&gt;Kata kunci : Kualitas rotifera, pengkayaan, asam eikosapentaenoik, asam dokosaheksaenoik, n3-HUFA&lt;/p&gt;

Determination on base systematic and ecology of rotifer fauna (Rotifera) in Hoyran Region of Eğirdir Lake.

Determination on base systematic and ecology of rotifer fauna (Rotifera) in Hoyran Region of Eğirdir Lake.

On the rotifer fauna of Disko Island, Greenland, with notes on selected species from a stagnant freshwater lake

The rotifer fauna in Moraine Lake on Disko Island was investigated. 24 species were identified, of which 22 are new for Disko Island and three are new to Greenland. The new findings are presented in a species list that summarizes all records of rotifers from Disko Island, including several previously unpublished records. Furthermore, notes are given on the morphology of some selected species, including Eothinia elongata, Mikrocodides chlaena and Resticula nyssa.

A modern approach to rotiferan phylogeny: Combining morphological and molecular data

The phylogeny of selected members of the phylum Rotifera is examined based on analyses under parsimony direct optimization and Bayesian inference of phylogeny. Species of the higher metazoan lineages Acanthocephala, Micrognathozoa, Cycliophora, and potential outgroups are included to test rotiferan monophyly. The data include 74 morphological characters combined with DNA sequence data from four molecular loci, including the nuclear 18S rRNA, 28S rRNA, histone H3, and the mitochondrial cytochrome c oxidase subunit I. The combined molecular and total evidence analyses support the inclusion of Acanthocephala as a rotiferan ingroup, but do not support the inclusion of Micrognathozoa and Cycliophora. Within Rotifera, the monophyletic Monogononta is sister group to a clade consisting of Acanthocephala, Seisonidea, and Bdelloidea—for which we propose the name Hemirotifera. We also formally propose the inclusion of Acanthocephala within Rotifera, but maintaining the name Rotifera for the new expanded phylum. Within Monogononta, Gnesiotrocha and Ploima are also supported by the data. The relationships within Ploima remain unstable to parameter variation or to the method of phylogeny reconstruction and poorly supported, and the analyses showed that monophyly was questionable for the families Dicranophoridae, Notommatidae, and Brachionidae, and for the genus Proales. Otherwise, monophyly was generally supported for the represented ploimid families and genera.

Do Rotifer Jaws Grow After Hatching?

Do Rotifer Jaws Grow After Hatching?

Spliced Leader RNA–Mediated trans-Splicing in Phylum Rotifera

In kinetoplastids, Euglena, and four metazoan phyla, trans-splicing has been described as a mechanism for the generation of mature messenger RNAs (mRNAs): 5'-ends of precursor mRNAs are replaced by a short spliced leader (SL) exon from a small SL RNA. Although the full phylogenetic range is unknown, trans-splicing has not been found in vertebrates, insects, plants, or yeast. In animal groups where it does occur, i.e., nematodes, cnidarians, platyhelminths, and primitive chordates, SL RNAs do not show sequence relatedness across phyla. The apparently sporadic phylogenetic distribution and the lack of SL RNA homology have led to opposing hypotheses on its evolution, involving either an ancient origin followed by loss in multiple lineages or independent acquisition in several taxa. Here we present evidence for the occurrence of trans-splicing in bdelloid rotifers (Bdelloidea, Rotifera). A common 23-nt sequence, representing the SL exon-diagnostic of SL RNA-mediated trans-splicing-was found at the 5'-end of at least 50%-65% of mRNAs from Adineta ricciae and Philodina sp. The trans-splicing pattern in bdelloid rotifers can be unusually complex, as observed in transcripts from a heat shock protein gene, hsp82-1, where the SL exon was spliced to three alternative positions. Bdelloid rotifer SL RNAs were found to be 105 or 106 nt long and comprised the SL sequence, a conserved splice donor site and an intron containing a putative spliceosome-binding motif. Intriguingly, some similarity of rotifer SL RNA sequence and predicted secondary structure was seen to that of the predominant SL1 RNA of nematodes, although it is unlikely that this demonstrates homology. In addition, sequence corresponding to the rotifer SL exon was found at the 5'-end of a number of full-length complementary DNA (cDNA) clones in a rice (Oryza sativa) database. None of these cDNAs gave a close match with homologous plant genes, suggesting that a small but significant portion of the rice expressed sequence tag database represents sequences derived from rotifers. In summary, the description of SL-mediated trans-splicing in Rotifera extends its representation to at least five metazoan phyla, making it increasingly probable that this is a phylogenetically widespread and therefore ancient phenomenon.

マハタ仔魚のワムシサイズに対する摂餌選択性

マハタ仔魚のワムシサイズに対する摂餌選択性

The Frank J. Myers Rotifera Collection: an illustrated catalog

The Frank J. Myers Rotifera Collection: an illustrated catalog

Feed consumption ratios of gilthead seabream larvae during first feeding by using microcapsules feeds and rotifer, either together or separately.

Feed consumption ratios of gilthead seabream larvae during first feeding by using microcapsules feeds and rotifer, either together or separately.

Molecular Phylogeny of Lophotrochozoa Based on 18S rRNA Gens Sequences-with Comment on the Phylogenetic Position of Bryozoa

Lophotrochozoa relationships were examined based on 18S rDNA evidence. The complete 18S rRNA genes of eight species of cheilostome bryozoans commonly found in coastal waters of China were amplified through polymerase chain reaction (PCR) and sequenced. Combined with known sequences of other bryozoans and related lophotrochozoans available through GenBank, Hydra littoralis as an outgroup, the molecular phylogenetic trees of Lophotrochozoa were reconstructed using the neighbour joining (NJ) and maximum parsimony methods in PHYLIP software. The results show, Gnathostomulida, Gastrostricha, Rotifera, Acanthocephala and Platyhelminthes constitute the basal branches of the phylogentic trees;Bryozoa appears to be polyphyletic within a monophyletic clade including other lophotrochozoan phyla. We also briefly discuss the phylogenetic relationships among the lophotrochozoan phyla and evaluated the phylogenetic position of Bryozoa in the light of this molecular and morphological evidence.