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排序方式: 共有324条查询结果,搜索用时 62 毫秒
1.
The Enigma of the Dinoflagellate Chromosome 总被引:3,自引:0,他引:3
PETER J. RIZZO 《The Journal of eukaryotic microbiology》1991,38(3):246-252
2.
第四纪沟鞭藻类在海南岛砂质白云岩中的发现 总被引:3,自引:3,他引:0
该文所研究的样品采自海南省儋县排浦乡,为一套珊瑚岸礁海蚀坪潮间带的更新世砂质白云岩。作者对其中两块样品进行了分析研究,并获得沟鞭藻类囊孢4属10种,其中包括1新种2未定种。文中除了对这些属种进行了较为详细的描述以外,还讨论了它们所反映的古环境,认为含有这些化石的砂质白云岩是暖温带浅海环境下的产物。 相似文献
3.
Barbara Hickel 《Hydrobiologia》1988,161(1):49-54
A new species of freshwater dinoflagellates, Ceratium rhomvoides nov. sp., is described from the Plußsee, northern West Germany, where it occurs regularly. C. rhomvoides nov. sp. is distinguished from closely related taxa by various aspects of the morphology of the vegetative cell and the cyst and by its sexual reproduction and seasonal distribution. 相似文献
4.
Barbara Hickel 《Hydrobiologia》1988,161(1):41-48
The life cycle of Ceratium furcoides (Levander) Langhans which features sexual reproduction is described for the first time in situ from the lake Plußsee (northern West Germany). Anisogamic copulation occurs during the bloom period in July–August by incorporation of the male gamete by the female gamete, resulting in an overwintering planozygote. The planozygote develops into a benthic hypnozygote which germinates in spring to establish a planomeiocyte. The morphology and structure of the stages of the life cycle are described using light and scanning electron microscopy. 相似文献
5.
Phagotrophic phytoflagellates in microbial food webs 总被引:7,自引:2,他引:5
Karen Glaus Porter 《Hydrobiologia》1988,159(1):89-97
Phagotrophy by pigmented flagellates is known from the literature but has recently been rediscovered in the context of microbial
food webs. Particle ingestion rates were found to be equivalent for pigmented and nonpigmented microflagellates in both field
and laboratory studies. Ingestion rates of the chrysophytes Ochromonas danica, O. minuta, and Poterioochromonas malhamensis, the dinoflagellate Peridinium inconspicuum, and the cryptophytes Cryptomonas ovata and C. erosa were compared with those of two nonpigmented Monas species using 0.57 μm polystyrene beads as a food source. Ingestion rates were 0.31 to 3.17 beads/cell/h and filtration rates
were 10−7 to 10−8 ml/cell/h with no detectable difference between pigmented and nonpigmented forms. Ingestion rates in unpigmented Monas species showed a linear increase with increasing particle concentration from 1.9 × 106 to 1.6 × 107 beads/ml.
Light and DOC levels in the range of those encountered by phytoflagellates in the field also influenced laboratory measurements
of bead ingestion by Poterioochromonas malhamensis. Ingestion rates decreased and photosynthesis increased over the natural PAR light range from 0 to 1800 microeinsteins/s/m2. At 40 microeinsteins/s/m2 maximum ingestion rates and high rates of photosynthesis occurred simultaneously. Ingestion rates decreased above 4 mgC/l
supplied as glucose. DOC levels commonly occurring in Lake Oglethorpe range from 3.5 to 10.0 mgC/l. These studies suggest
that mixotrophy, the trophic utilization of particulate food and dissolved organic matter as well as photosynthetically fixed
organic matter, is a balanced process that can be regulated by environmental conditions.
In field studies during a chrysophyte bloom, phytoflagellate grazing exceeded heterotrophic microflagellate grazing and constituted
up to 55% of the bactivory of all microflagellates, ciliates, rotifers, and crustaceans combined. Neither bacterial abundance,
light nor temperature were good predicters of grazing rates for the phagotrophic phytoflagellate association as a whole during
this unstratified period. Phagotrophs are often most abundant at the metalimnetic plate during stratification. 相似文献
6.
7.
黑龙江绥滨地区晚侏罗世东荣组的沟鞭藻类 总被引:12,自引:0,他引:12
本文对黑龙江绥滨86-11孔的沟鞭藻类进行了初步研究,共描述化石10属16种(包括2新种,6未定种);其中不少是在我国首次描述的。这些化石分成两个组合,其优势分子分别为Gonyaulacysta jurassica和Amphorula delicata。根据组合内各分子的时代分布,两化石组合的时代分别为Late Oxfordian—Early Kimmeridgian和Portlandian期,并对其产出层位东荣组的时代作了讨论,认为属于晚侏罗世。 相似文献
8.
Till Roenneberg 《Physiologia plantarum》1996,96(4):733-737
Circadian oscillations are a fundamental biological property from bacteria to humans. The molecular mechanisms which produce a ca 24-h rhythmicity are still unknown but it has become clear that they are part of the biochemical machinery of the single cell. The cellular circadian system can be favorably studied in single-cell organisms such as the dinoflagellate Gonyaulax polyedra . The complexity of this circadian model system, which consists of at least two circadian oscillators, receives light via two input systems with different spectral sensitivities, and has several feed–back loops between the central oscillator(s) and the environment, is described here. 相似文献
9.
Maria A. Faust 《Journal of phycology》1993,29(1):100-107
Three new benthic dinoflagellate species, Prorocentrum belizeanum, Prorocentrum elegans, and Prorocentrum caribbaeum, from mangrove floating detritus are described from scanning electron micrographs. Species were identified based on shape, size, surface micromorphology, ornamentation of thecal plates, and architecture of the periflagellar area and intercalary band. Cells of P. belizeanum are round to slightly oval with a cell size of 55–60 μm long and 50–55 μm wide. Areolae are round and numerous (853–1024 per valve) and range from 0.66 to 0.83 μm in size. The periflagellar area of P. belizeanum is a broad V-shaped depression; it accommodates a flagellar and an auxiliary pore and a flared, curved apical collar. The intercalary band of P. belizeanum is horizontally striated. Prorocentrum elegans is a small species 15–20 μm long and 10–14 μm wide, with an ovate cell shape. The thecal surface is smooth. Two sizes of valve pores were recognized: large, round pores (20–22 per valve) arranged in a distinct pattern and smaller pores situated in an array along the intercalary band. The periflagellar area is V-shaped; it accommodates an uneven sized flagellar pore, an auxiliary pore, and an angled protuberant flagellar plate. The intercalary band is transversely striated. It is a bloom-forming species. Prorocentrum caribbaeum cells are heart-shaped with a rounded anterior end and a pointed posterior end. Cells range from 40 to 45 μm long and 30 to 35 μm wide. Thecal surface has two different-sized pores: large, round pores (145–203 per valve) arranged perpendicularly from the posterior margins, and small, round pores unevenly distributed on the thecal surface. The periflagellar area is ornate. It is V-shaped with a curved apical collar located next to the auxiliary pore; a smaller protuberant apical plate is adjacent to the flagellar pore. The intercalary band is transversely striated and sinuous. Cells are active swimmers. 相似文献
10.
The composition of paralytic shellfish toxins in the marine dinoflagellate Alexandrium ostenfeldii (Paulsen) Balech et Tangen grown in unialgal culture was determined by high-performance liquid chromatography. The toxin profile revealed that the low-potency sulfamate toxin B2 was dominant (90 molar % of total toxins), but small amounts of the weakly toxic 21-N-sulfocarbamoyl derivatives C1+2 and trace amounts of the carbamate toxins GTX2 and GTX3 were also present. The mammalian toxicity was confirmed by a modification of the conventional AOAC mouse bioassay (0.6–1.4 pg STXeq· cell-1). The acute toxicity to a potential predator, the tintinnid ciliate Favella ehrenbergi (Clap, et Lach.) Jörg., was also investigated. The ciliate was able to graze on A. ostenfeldii when the cell concentration of the dinoflagellate was low (<2000 cells · mL-1). At higher concentrations the ciliate was affected by exudates (presumably PSP toxins) that induced backward swimming followed by swelling and lysis of the cell. Fluorescence microscopy of calcofluor-stained cells was employed as an easy and rapid method to identify this and other thecate dinoflagellates. 相似文献