中国金色藻属四个新记录种的超微结构研究

金色藻属Chrysochromulina的种类是海洋浮游植物的重要组成成分。报道了该属在我国的4个新记录种,即盅鳞金色藻Chrysochromulina cymbium Leadbeater ＆ Manton、毛刺金色藻C hirta Manton、粗柱金色藻C,megacylindra Leadbeater和普氏金色藻C pringsheimii Parke ＆ Manton,并在电子显微镜下观察了细胞的超微结构。     

Comparison of growth characteristics of New Zealand isolates of the prymnesiophytes Chrysochromulina quadrikonta and C.camella with those of the ichthyotoxic species C.polylepis

Chrysochromulina quadrikonta (Prymnesiophyceae), a quadriflagellatespecies previously unrecorded in New Zealand, was isolated fromNelson Harbour, New Zealand, in autumn 1991. It bears unmineralizedplate and spine scales, which morphologically are most likethose of Chrysochromulina ericina. Chrysochromulina quadrikonta,Chrysochromulina camella (isolated from the Marlborough Sounds,New Zealand) and Chrysochromulina polylepis (an ichthyotoxicspecies originally isolated from Scandinavia) grew most rapidly(growth rates, or divisions per day, of 1.41, 1.49 and 1.43,respectively) when cultured in a seawater-based general-purposenutrient medium at a salinity of 24% and pH 7.9, with only C.camellastill growing at 42% Chrysochromulina quadrikonta and C.camellagrew optimally at 25°C. and C.polylepis between 15 and 20°C;only C.polylepis grew at 10°C. Chrysochromulina quadrikontagrew optimally with potassium nitrate and ammonium chlorideas nitrogen source, whereas C.camella and C.polylepis grew equallywell with urea as nitrogen source. Only C.quadrikonta and C.polylepishad a selenium requirement. Unlike C.polylepis, neither of theNew Zealand isolates was phagotrophic nor ichthyotoxic.     

Chrysochromulina brachycylindra sp. nov. (Prymnesiophyceae) from Finnish coastal waters

Chrysochromulina brachycylindra sp. nov. is described by means of transmission electron microscopy of shadowcast whole mounts prepared from wild material collected from Finnish coastal waters. The suhspherical cell carries plate-scales and cylinder-scales. The scales are large enough to render possible a light microscopical identification of this species from dry preparations. Based on scale morphology it is evident that C. brachycylindra is closely related to C. pachycylindra Manton, Oates & Course. In addition to the findings from the Baltic Sea the new species is also reported from the Andaman Sea, SW Thailand.     

THE FLAGELLAR APPARATUS OF CHRYSOCHROMULINA SP. (PRYMNESIOPHYCEAE)1

The flagellar apparatus of an undescribed species of Chrysochromulina Lackey that bears “eyelash” scales is reconstructed. The transitional region consists of two transitional plates each with an axosome, with no stellate pattern between them. Fine osmiophilic rings lie between the flagellar membrane and the outer doublets in the transitional region. The two jagella and the haptonema are inserted in a subapical depression that is lined ventrally by a spine-like projection formed by one of the parietal chloroplasts. The angles of insertion are similar to those of some other Chrysochromulina species in that both the haptonema and the right basal body lie at an extreme angle to the left basal body. The connectives of the apparatus consist of a striated distal band with a dorsal extension to the R1 and a ventral extension overlying the R2, a striated distal accessory band, an auxiliary connective from the right basal body to the adjacent ventral chloroplast, a well-developed intermediate band, two striated proximal bands, and a striated proximal accessory band. Of the microtubular roots in this Chrysochromulina species, three are associated with the left side of the cell (an R1 of 8+3; a small crystalline compound root, the R1C, associated with the R1; an R2 of three micro-tubules), and two are associated with the right basal body (an R3 of 2/2 microtubules with which the single-stranded R4 converges to form a 2/2+1 and then a 2/3 tiered arrangement). Comparisons are drawn with other species in the genus and related genera, particularly Prymne-sium.     

ECO-PHYSIOLOGY, BIO-OPTICS AND TOXICITY OF THE ICHTHYOTOXIC CHRYSOCHROMULINA LEADBEATERI (PRYMNESIOPHYCEAE)

A toxic phytoplankton bloom, dominated by the prymnesiophyte Chrysochromulina leadbeateri Estep, developed in the Ofotfjord–Tysfjord area (North Norway) in mid-May and ended in late June 1991 in Vestfjorden and the adjacent fjord areas. Chrysochromulina leadbeateri dominated at total cell densities of >2 × 10⁶ cells·L⁻¹; at lower total cell densities, C. leadbeateri was accompanied by other Chrysochromulina species, peridinin-containing dinoflagellates, and diatoms. Bio-optical characteristics and pigmentation in laboratory and field strains of C. leadbeateri allowed for the interpretation of the optical signatures within the bloom. The bio-optical data suggested healthy and actively growing cells during the bloom. About 600 metric tons of pen-raised Atlantic salmon were killed by the C. leadbeateri bloom. A laboratory study was conducted to assess the potential impact of finfish on C. leadbeateri growth. It was found that the polyamine putrescine enhanced cell biomass and hemolytic activity. Given this, a possible scenario for the development of this bloom and the level of toxicity is hypothesized: (1) The nutrient loading in the Ofotfjord area was enhanced during the winter of 1990–1991 due to the overwintering of 1.5 × 10⁶ metric tons of herring from a depth of 0–250 m. This may have sustained a large stock of the mixotrophic C. leadbeateri in early spring before light regime (irradiance, spectral irradiance, and day length) made net photosynthesis possible. (2) The release of polyamines during the decay of dead fish (e.g. putrescine, cadaverine, and histamine) may have acted as cofactors with ichthyotoxins making "hypertoxic complexes" with the polyamines enhancing growth in the mixotrophic C. leadbeateri.     

NEW AND RARE CHRYSOPHYTES FROM WYOMING AND COLORADO LAKES

Colorado and Wyoming lakes with high pH values generally ranging from 8 to 10 are dominated by phytoplankton belonging to the chrysophytes, diatoms and cryptomonads. Our studies on phytoplankton diversity in Dowdy, South Delaney Buttes and Cowdrey Lakes in Colorado and Diamond and Twin Buttes Lakes in Wyoming have yielded several isolates of rare or new chrysophytes. These isolates were examined with light microscopy, SEM, TEM, and novel information regarding their structure is presented. Proposed new species belong to the genera Saccochrysis, Prymnesium and Chrysochromulina. Chrysophytes that were examined for the first time include Monochrysis aphanaster , Uroglenopsis , and a mixotrophic species of Ochromonas , which ingests small diatoms. Probable new species are the following: Saccochrysis sp. nov. differs in chloroplast structure, cell shape and cell number/colony, and absence of a posterior vacuole; Prymnesium sp. nov. is the first freshwater form examined with EM and differs in scale morphology; and Chrysochromulina sp. nov. is similar to Chrysochromulina parva but lacks scales. The ultrastructure of M. aphanaster is unique and appears to be a member of the Chrysophyceae. It has two flagella, one of which is emergent, while the other is hidden within an invagination of the cytoplasm. Diacronema and Sarcinochrysis spp. from these lakes also were isolated and reinvestigated, and some unique cellular features will be discussed.     

Environmental forcing as a main determinant of bloom dynamics of the Chrysochromulina algae

In this paper, we demonstrate that the seasonal dynamics in the abiotic factors, without including seasonal changes in the biological relationships, can appropriately account for the seasonal dynamics of Chrysochromulina spp. This is through the analysis of data on the population dynamics of Chrysochromulina spp. off southern Norway that is evaluated in relation to environmental factors and season by the analyses of 12 year monthly time-series. Chrysochromulina spp. abundance, nutrient concentrations, hydrographical properties, as well as current and wind data were analysed on a monthly scale by means of autoregressive moving average models, principal component analyses (PCA), and linear and nonlinear regression models. Seasonal development of the Chrysochromulina assemblage was well predicted from regression models forced with two PCA components representing seasonal variation in nutrient and chlorophyll a levels and ratios, inflow of North Seawater to the Skagerrak and northeasterly wind along the Norwegian coast. Assuming these to be general results, we might hypothesis that marine algal communities are governed by seasonally varying abiotic factors to a large extent.     

CHRYSOCHROMULINA BREVITURRITA SP. NOV., A NEW FRESHWATER MEMBER OF THE PRYMNESIOPHYCEAE1

Chrysochromulina breviturrita sp. nov. is described as a new haptonema-bearing member of the freshwater Prymnesiophyceae. It is ca. three times larger than the only other known freshwater member of the genus (C. parva Lackey)and possesses a haptonema only ca. 0.2–0.3 as long as the haptonema of C. parva. Two equal flagella (1.5–2 as long as the haptonema), a large contractile vacuole, two parietal plasties, a single pyremid, nucleus, Chrysolaminarin-like droplets and a food vacuole are features readily observed with the light microscope. Dried and shadoweast whole mounts examined with the electron microscope reveal the cell surface covered with two types of small, delicate scales: outer spined scales with a clubshaped terminus and with the spine anchored to a circular to oval base-plate by 2–6 (7) branching arms; and, spineles oval plate scales with concentric lines and radiating ridges on one face and parallel ridges on the other. C. breviturrita has been found in nine lakes in Ontario (Canada). Pereliminary observations suggest that it is an important component of lake plankton and has probably not been delected in previous work, more because of its fragility than because of its scarcity. Living specimens are a prerequisite for initial identification, since cells frequently rupture and haptonemata are often lost when the organisms are killed with the commonly used fixatives.     

SOME PRYMNESIACEAE (HAPTOPHYTA,PRYMNESIOPHYCEAE) FROM THE MEDITERRANEAN SEA,WITH THE DESCRIPTION OF TWO NEW SPECIES: CHRYSOCHROMULINA LANCEOLATA SP. NOV. AND C. PSEUDOLANCEOLATA SP. NOV.1

Five species belonging to the family Prymnesiaceae (one Prymnesium and four Chrysochromulina) have been identified in cultures obtained from water collected in the Bay of Banyuls‐sur‐Mer (Mediterranean Sea, France) using LM, SEM, and TEM. Two are described as new species, Chrysochromulina lanceolata sp. nov. and C. pseudolanceolata sp. nov. Both species are large and lanceolate with an acute posterior and two anterior arms. They are easily detectable with LM but difficult to distinguish to species level with live cells, without experience. EM reveals two completely different scale patterns in the two species. Cells of C. lanceolata are 21–38 μm long, 7–12 μm wide, and 3–7 μm thick. They possess two subequal flagella (30–51 and 29–44 μm), and the haptonema is shorter than the flagella (23–37 μm). The cell body is covered by plate and spine scales. Cells of C. pseudolanceolata sp. nov. are slightly smaller (15–18 × 6–8 μm) with more rounded extremities, two subequal flagella (19–26 and 17–24 μm), and the haptonema is longer than the flagella (about 35 μm). Three types of plate scales are observed in this species. Other findings are C. alifera Parke et Manton and C. throndsenii Eikrem (a new record for the Mediterranean Sea). Prymnesium faveolatum Fresnel, a new toxic species recently described, is illustrated with both LM and SEM.     

Scale–bearing Chrysophyceae (Mallomonadaceae) from Central and Northern Canada

In this study, scale–bearing Chrysophyceae (Mallomonadaceae) have been examined by means of transmission and scanning electron microscopy. Lakes in four areas in central and northern Canada, viz. Experimental Lakes Area (ELA), in northwestern Ontario, Whiteshell Provincial Park and Southern Indian Lake in eastern and northern Manitoba, respectively, and Saqvaqjuac on the west coast of Hudson Bay in the Northwest Territories have been investigated. Forty–three species of the genera Mallomonas, Paraphysomonas, Spiniferomonas and Synura have been identified in addition to three species of the genus Chrysochromulina (Prymnesiophyceae). Ten species are new to Canada; five of these have not previously been recorded from North America. Paraphysomonas elegantissima sp. nov. is described. The composition of the Canadian chrysophycean flora is compared with the chrysophycean flora of North America as a whole.     

Multiple plastids collected by the dinoflagellate Dinophysis mitra through kleptoplastidy

Kleptoplastidy is the retention of plastids obtained from ingested algal prey, which may remain temporarily functional and be used for photosynthesis by the predator. We showed that the marine dinoflagellate Dinophysis mitra has great kleptoplastid diversity. We obtained 308 plastid rbcL sequences by gene cloning from 14 D. mitra cells and 102 operational taxonomic units (OTUs). Most sequences were new in the genetic database and positioned within Haptophyceae (227 sequences [73.7%], 80 OTUs [78.4%]), particularly within the genus Chrysochromulina. Others were closely related to Prasinophyceae (16 sequences [5.2%], 5 OTUs [4.9%]), Dictyochophyceae (14 sequences [4.5%], 5 OTUs [4.9%]), Pelagophyceae (14 sequences [4.5%], 1 OTU [1.0%]), Bolidophyceae (3 sequences [1.0%], 1 OTU [1.0%]), and Bacillariophyceae (1 sequence [0.3%], 1 OTU [1.0%]); however, 33 sequences (10.8%) as 9 OTUs (8.8%) were not closely clustered with any particular group. Only six sequences were identical to those of Chrysochromulina simplex, Chrysochromulina hirta, Chrysochromulina sp. TKB8936, Micromonas pusilla NEPCC29, Micromonas pusilla CCMP491, and an unidentified diatom. Thus, we detected >100 different plastid sequences from 14 D. mitra cells, strongly suggesting kleptoplastidy and the need for mixotrophic prey such as Laboea, Tontonia, and Strombidium-like ciliates, which retain numerous symbiotic plastids from different origins, for propagation and plastid sequestration.     

Isolation and phylogenetic analysis of novel viruses infecting the phytoplankton Phaeocystis globosa (Prymnesiophyceae)

Viruses infecting the harmful bloom-causing alga Phaeocystis globosa (Prymnesiophyceae) were readily isolated from Dutch coastal waters (southern North Sea) in 2000 and 2001. Our data show a large increase in the abundance of putative P. globosa viruses during blooms of P. globosa, suggesting that viruses are an important source of mortality for this alga. In order to examine genetic relatedness among viruses infecting P. globosa and other phytoplankton, DNA polymerase gene (pol) fragments were amplified and the inferred amino acid sequences were phylogenetically analyzed. The results demonstrated that viruses infecting P. globosa formed a closely related monophyletic group within the family Phycodnaviridae, with at least 96.9% similarity to each other. The sequences grouped most closely with others from viruses that infect the prymnesiophyte algae Chrysochromulina brevifilum and Chrysochromulina strobilus. Whether the P. globosa viruses belong to the genus Prymnesiovirus or form a separate group needs further study. Our data suggest that, like their phytoplankton hosts, the Chrysochromulina and Phaeocystis viruses share a common ancestor and that these prymnesioviruses and their algal host have coevolved.     

Temporary cyst formation in phytoplankton: a response to allelopathic competitors?

Competition among phytoplankton for limiting resources may involve direct or indirect interactions. A direct interaction of competitors is the release of chemicals that inhibit other species, a process known as allelopathy. Here, we investigated the allelopathic effect of three toxic microalgae species (Alexandrium tamarense, Karenia mikimotoi and Chrysochromulina polylepis) on a natural population of the dinoflagellate Scrippsiella trochoidea. Our major findings were that in addition to causing death of S. trochoidea cells, the allelopathic species also induced the formation of temporary cysts in S. trochoidea. Because cysts were not lysed, encystment may act as a defence mechanism for S. trochoidea to resist allelochemicals, especially when the allelopathic effect is moderate. By forming temporary cysts, S. trochoidea may be able to overcome the effect of allelochemicals, and thereby have an adaptive advantage over other organisms unable to do so.     

中国新记录──小金色藻在武汉东湖的季节消长

一种未曾在中国报道过的小金色藻(Chrysochromulina parva Lackey)在武汉东湖发现,此种在冬季出现,春末消失,高的种群密度(8357.6cells/ml及8737.0cells/ml)分别在1991年2月及1992年1月在水温为6─8℃时形成,持续时间近1个月,小金色藻的生物量在东湖营养状况不同的三个采集站是不同的,但季节消长的趋势基本上一致。此种喜生长在富营养的水体中。       

Lakewide odours in Ontario and New Hampshire caused by Chrysochromulina breviturrita Nich. (Prymnesiophyceae)

At densities of 500–9 000 cells/ml, the planktonic alga Chrysochromulina breviturrita Nich. produced obnoxious lake-wide odours in five lakes between 1978 and 1980. In one case, CuSO₄ was used to kill the organism and control the odour, but in the other four lakes, the species persisted for 4–6 weeks before populations declined and odours disappeared. This is the first recorded instance of odour production by any member of the Prymnesiophyceae.     

A simple and highly efficient fixation method for Chrysochromulina polylepis (Prymnesiophytes) for analytical flow cytometry

BACKGROUND: To study the fragile Prymnesiophyte species Chrysochromulina polylepis by flow cytometry (FC), we needed an effective fixation method. This method must guarantee a high yield of fixed cells to achieve acceptable measurement times by FC and to allow quick processing of many samples. Moreover, we wanted a method that allows for storage of fixed samples when FC analysis cannot be done immediately. METHODS: Different aldehydes and methanol were tested at different final concentrations. Gravity sedimentation and centrifugation were applied to achieve higher cell concentrations. Storage of fixed samples was tested under different conditions. RESULTS: 0.25% glutaraldehyde (GA) fixation yielded a recovery rate of about 90%. The signals obtained by FC analysis were excellent. It is possible to centrifuge GA-fixed cells and to store them for several weeks. CONCLUSIONS: GA is the fixative of choice for FC analysis of C. polylepis (and possibly other small delicate species) because it yielded highly significant recovery rates and high-quality FC signals. Cells can be centrifuged to increase the cell concentration, thereby achieving short measurement times with FC. The possibility of long-term storage of fixed cells presents an additional advantage if FC analysis cannot be done immediately.     

Cryopreservation of economically valuable marine micro-algae in the classes Bacillariophyceae, Chlorophyceae, Cyanophyceae, Dinophyceae, Haptophyceae, Prasinophyceae, and Rhodophyceae

The ability to routinely cryopreserve micro-algal species reduces costs associated with maintaining large culture collections and reduces the risks of losing particular strains or species through contamination and genetic drift. Cryopreservation is also a useful adjunct in aquaculture hatcheries for strains of micro-algae where the nutritional status may change as a result of continuous sub-culture. In this study, cryopreservation of isolates from seven micro-algal classes was investigated. Successful candidates included the marine dinoflagellates Amphidinium carterae, Amphidinium trulla, and Gymnodinium simplex, and the haptophytes Chrysochromulina simplex, Prymnesium parvum, Prymnesium parvum f. patelliferum, Isochrysis galbana, and Pavlova lutheri. Also successfully cryopreserved were the planktonic diatoms Chaetoceros calcitrans, Chaetoceros muelleri, Chaetoceros sp., and the benthic Nitzschia ovalis, the chlorophyte Chlamydomonas coccoides, the rhodophyte Porphyridium purpureum, the prasinophytes Tetraselmis chuii, and Tetraselmis suecica, and the cyanophytes Raphidiopsis sp., and Aphanizomenon flos-aquae. All species were successfully cryopreserved using 15% Me2SO.     

Phytoplankton responses to experimental enhancement of grazing pressure and nutrient recycling in a small Andean lake

1. Three series of field experiments with different zooplankton species composition and biomass were performed in a small lake in the south Andes. We attempted to measure the responses of phytoplankton species resulting from grazing mortality and stimulation of growth by nutrient recycling.
2. Nanoflagellates contributed substantially to total phytoplankton cell abundance. Chrysochromulina parva represented 93.4%, 92.2% and 95.9% of total phytoplankton density in December, January and February, respectively. This fraction was reduced in all treatments with increasing zooplankton biomass.
3. A negative relationship was obtained between C. parva cell numbers and increase in dissolved P. On the other hand, a significant positive relationship between the abundance of the diatom Aulacoseira granulata and P concentration was observed. These results indicate that the ungrazed diatom was able to capitalise on the increase in nutrient availability.
4. As a net result of the increase or decrease of algal species we observed a change in the nano:net phytoplankton relationship. The outcome of three‐day incubations with increased zooplankton biomass was an increasing importance of net phytoplankton.
5. The results indicate the importance of the indirect effects of zooplankton (through nutrient recycling) in the increase in diatoms, and the role of grazing as a growth‐limiting factor for the flagellate C. parva .     

中国拟缺齿藓属Haplodontium Hampe(真藓科)的分类学研究

报道了中国新记录属--拟缺齿藓属（Haplodontium Hampe）分类学的研究进展。目前本属在中国分布有3种,其中包括1新种：臧氏拟缺齿藓（Haplodontium zangii X.R.Wang&J.C.Zhao）,2个新组合：喜马拉雅拟缺齿藓[H.himalayanum（Mitt.）X.R.Wang&J.C.Zhao]和中华拟缺齿藓[H.sinensis（Dix.）X.R.Wang&J.C.Zhao]。笔者对中国拟缺齿藓属3种植物的形态学特征绘制了墨线图,在光学显微镜和电子显微镜下拍摄显微形态照片,并对每种的主要识别特征、生境和地理分布以及与相似种的形态学比较进行了讨论。     

A transglucosylase that forms soluble glucosides found in membranes of a haptophycean alga

A particulate enzyme preparation isolated from Chrysochromulina chiton catalysed the transfer of [U-¹⁴C]-glucose from UDP [U-¹⁴C]-Glc to a water-soluble small molecular weight material. Chemical and enzymic analysis of this material showed that it was a phenolic compound to which are attached two β(1–3) glucosides. Properties of the UDP glucose: glucosyltransferase involved in the synthesis of this material have been studied. The UDP glucose glucosyl-transferase was found to be associated with the rough endoplasmic reticulum. A possible function of this phenolic compound in the orientation of membranes for the synthesis of scales in C. chiton has been discussed.