Physiology and Nutrition of Lampropedia hyalina

A detailed study of the physiology and nutrition of Lampropedia hyalina revealed that it is an aerobic, cytochrome-containing chemoheterotroph which is limited in its energy sources to a few intermediates (and close derivatives) of the Krebs cycle. Reducing compounds at low levels are potent growth inhibitors. The microbe has no photosynthetic ability (despite its previous taxonomic position with the sulfur purple bacteria). The results of a general investigation of its physiology are reported. Added biotin and thiamine are needed for growth in defined media; pantothenate is strongly stimulatory. Alanine, arginine, and tyrosine, as well as NH(4)Cl, serve as sole nitrogen sources. A unique motion exhibited by cells of a rapidly growing culture is described. Aspects of its metabolism of poly-beta-hydroxybutyrate and limiting aspects of its physiology as related to its ecology are discussed.     

武汉东湖透明溞和隆线溞一亚种的种群变动和生产量

本文报道了1980—1982年东湖二种优势枝角类:透明溞(Daphnia hyalina)和隆线溞一亚种(Daphnia carinata ssp.)的种群变动和生产量的研究结果。分析了影响种群变动和生产量的生态因子。尽管这二种枝角类在一年中有一段共存时间,但高峰期从来是错开的。一般来说,透明溞的高峰期出现在春季或冬季;而隆线溞一亚种则出现在夏季或秋季源沓ㄋ蘑蛘纠此?1980—1982年透明溞的种群密度的年平均值为28.43(17.59—38.50)个/升;隆线溞一亚种为4.64(3.79—5.31)个/升。种群的瞬时出生率(b),;通常大于瞬时增长率(r);瞬时死亡率(d)与b的季节变动在大多数情况下是一致的。透明溞的年平均生物量为0.218(0.163—0.315)毫克干重/升,生产量为9.181(4.877—13.428)毫克干重/升·年,P/B系数为42.38(27.76—56.70)。隆线溞一亚种的年平均生物量为0.046(0.039—0.060)毫克干重/升,生产量为3.417(2.752—3.829)毫克干重/升·年,P/B系数为77.04(61.24—99.74)。       

A taxonomic reappraisal of the Daphnia hyalina complex (Crustacea: Cladocera): an experimental and ecological approach

The paper is a taxonomic study of the limnetic Daphnia populations of the English Lake District, the populations upon which the most popular taxonomic scheme is based (Johnson, 1952).
Johnson treats these populations as three varieties of the species D. hyalina, namely D. hyalina s. str., D.h. var. galeata and D.h. var. lacustris .
Careful examination of the populations of Esthwaite reveals that what has previously been regarded as a population of a single variety of D. hyalina. includes three distinct forms. Experimental work confirms that these are genetically distinct. One of these forms corresponds to D. hyalina var. galeata , whilst the other two are designated the "toothed" and "round-headed" forms.
The first part of the paper is concerned with the taxonomic status of var. galeata . Brooks (1957) and some later workers treat this as a separate species (D. galeata) on morphological grounds. This is fully supported by the present work. Differences between var. galeata and co-existing forms in incidence of sexual reproduction, in vertical distribution and in seasonal abundance and average brood-size provide further support for the separation of D. galeata.
The second part of the paper is concerned with D. hyalina s.str. which, on the basis of morphology, ecology and reproductive behaviour, is shown to be at least as distinct from other members of the complex as is D. galeata . It is argued that other forms should therefore to be removed from D. hyalina . The taxonomic status and affinities of the remaining "toothed" and "round-headed" forms are discussed.     

Isolation and in vitro assembly of the components of the outer S layer of Lampropedia hyalina.

The outermost component of the S layer of Lampropedia hyalina, the punctate layer, is assembled onto an inner perforate layer. The punctate layer is composed of long, tapered cylindrical units centered on p6 symmetry axes and connected by six fine linking arms, joining at the axis of threefold symmetry to create a hexagonal layer with a lattice constant of 25.6 +/- 0.5 nm (J. A. Chapman, R. G. E. Murray, and M. R. J. Salton, Proc. R. Soc. London Ser. B 158:498-513, 1963; R. G. E. Murray, Can. J. Microbiol. 9:593-600, 1963). Extraction of cell envelopes with 100 mM Tris buffer (pH 8) containing 2% deoxycholate resulted in the release of several proteins, but left the S layers intact. The punctate layer was then extracted with 3 M guanidine hydrochloride or 6 M urea, leaving the perforate layer intact. This treatment led to the release of three polypeptides with molecular weights of 60,000, 66,000, and 240,000 (60K, 66K, and 240K polypeptides). These three polypeptides reassembled on the perforate layer as a template to form the S-layer complex or self-assembled to form the punctate layer alone after dialysis of the extract against 50 mM HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) buffer (pH 7.5) containing 10 mM CaCl2. The self-assemblies were composed of a 240K polypeptide and a 60K polypeptide. The 240K and 60K polypeptides were separated by column chromatography and examined by electron microscopy. The 240K polypeptide appeared in negative stain as a long, flexible structure and assembled into loose arrays with sixfold symmetry with obvious Y-shaped linking elements, while fractions containing both the 60K and 240K polypeptides showed assemblies closely resembling the punctuate layer. Immunoelectron microscopy was used to confirm the presence of both the 60K and 240K polypeptides as components of the punctuate layer.     

Niche in Pasture-Fed Ruminants for the Large Rumen Bacteria Oscillospira, Lampropedia, and Quin's and Eadie's Ovals

The little-studied large bacteria Oscillospira, Lampropedia, and ovals attach rapidly in large numbers to the cuticular surface of clover and grass leaves in the rumen. The cuticle of green leaves may constitute a specific niche for these bacteria.     

Respiratory electron transport system (ETS) activity as an estimator of the thermal tolerance of two Daphnia hybrids

The influence of temperature on the activity of the respiratoryelectron transport system (ETS) was measured in one clone ofDaphnia hyalina x galeata and one of Daphnia cucullata x galeata,isolated from Lake Bled (Slovenia). The ETS activity of ovigerousfemales acclimated to 7, 20 and 25°C, was measured at 5,10, 15, 20, 25 and 30°C. Population growth experiments showedthat D. cucullata x galeata grew better at high rather thanlow temperatures. Daphnia hyalina x galeata, however, grew moresuccessfully at low temperatures than did D. cucullata x galeata.The highest Q₁₀ of ETS activity of D. cucullata x galeata atthe lowest temperature range of 5–15°C indicated theabsence of enzymes that could function sufficiently well atlow temperatures. The ETS activity of the warm-acclimated hybridD. hyalina x galeata reached a maximum at an incubation temperatureof 20°C, while D. cucullata x galeata had maximal ETS activityat 25°C. Thus D. cucullata x galeata has a more efficientenzyme system than D. hyalina x galeata at the higher temperature.The higher Arrhenius activation energy (E_a) for D. cucullatax galeata than for D. hyalina x galeata indicates that enzymesfrom D. cucullata x galeata are more temperature sensitive thanthose from D. hyalina x galeata. In conclusion, the ETS of D.cucullata x galeata is adapted to a higher temperature and tonarrower temperature fluctuations than that of D. hyalina xgaleata.     

Prehistoric inter-archipelago trading of Polynesian tree snails leaves a conservation legacy

Inter-archipelago exchange networks were an important aspect of prehistoric Polynesian societies. We report here a novel genetic characterization of a prehistoric exchange network involving an endemic Pacific island tree snail, Partula hyalina. It occurs in the Society (Tahiti only), Austral and Southern Cook Islands. Our genetic data, based on museum, captive and wild-caught samples, establish Tahiti as the source island. The source lineage is polymorphic in shell coloration and contains a second nominal species, the dark-shelled Partula clara, in addition to the white-shelled P. hyalina. Prehistoric inter-island introductions were non-random: they involved white-shelled snails only and were exclusively inter-archipelago in scope. Partulid shells were commonly used in regional Polynesian jewellery, and we propose that the white-shelled P. hyalina, originally restricted to Tahiti, had aesthetic value throughout these archipelagoes. Demand within the Society Islands could be best met by trading dead shells, but a low rate of inter-archipelago exchange may have prompted the establishment of multiple founder populations in the Australs and Southern Cooks. The alien carnivorous land snail Euglandina rosea has recently devastated populations of all 61 endemic species of Society Island partulid snails. Southern Cooks and Australs P. hyalina now represent the only unscathed wild populations remaining of this once spectacular land snail radiation.     

基于16S rDNA和COⅠ基因序列探讨四种溞类的系统关系和分类地位

为了检验已记录的4个溞属种类（(隆线溞Daphnia carinata、透明溞D. hyalina、蚤状溞D. pulex和大型溞D. magna）的系统分类, 用试剂盒法分别提取4种溞类的基因组DNA。利用特异性引物, 通过PCR扩增了4种溞属种类的16S rDNA和COⅠ基因部分序列, 并与来自GenBank中每个种类相似度较高的同种序列进行分析。结果表明, 基于16S rDNA和COⅠ基因, 4个溞属种类的平均种间相似度分别为85.56%和80.67%, 碱基中A+T含量均明显高于G+C含量。基于COⅠ基因, 巢湖隆线溞与来自GenBank上的拟同形溞（(Daphnia similoides AB549199）)相似度为99%, 分歧度为0.4%0.9%。就16S rDNA和COⅠ基因而言, 巢湖透明溞更接近于盔形溞（Daphnia galeata）。基于16S rDNA和COⅠ基因构建的NJ树和贝叶斯树, 两者的主要分枝基本一致。结果暗示, 巢湖隆线溞与拟同形溞为一个种, 透明溞应属于盔形溞。由于缺乏核基因的研究, 有关巢湖溞属的分类地位还需进行更深入的探讨。       

Assessment of the importance of fish predation versus copepod predation on life history traits of Daphnia hyalina

Daphnia hyalina is a cladoceran present throughthe whole year except for late summer in Maranhão,a meso-eutrophic reservoir in central Portugal. Apartfrom the influence of food, both vertebrate andinvertebrate predation pressures seem to have aneffect on D. hyalina population dynamics.Enclosure experiments were designed to assess therelative importance of both types of predation. Afterthe summer crash, D. hyalina reached highernumbers in the fishless enclosures than in the lakedespite of high predation pressure upon juveniles byAcanthocyclops robustus. Fish predation upon thelargest individuals, especially large egg bearingfemales, was responsible for the lower fertility ofthe open water population when compared with theenclosure population. In the enclosures an increase intail spine length was observed. The longer tail spineprobably offered protection from copepod predation,allowing at least some of the juveniles to coexistwith their potential predator and reach the adultstage, less susceptible to copepod predation.     

武汉东湖透明溞和隆线溞一亚种体长-体重回归方程式

透明溞(Daphnia hyalina)和隆线溞一亚种(Daphnia carinata ssp.)是东湖优势枝角类。       

Mitochondrial DNA phylogeography and mating compatibility reveal marked genetic structuring and speciation in the NE Atlantic bryozoan Celleporella hyalina

The marine bryozoan Celleporella hyalina is a species complex composed of many highly divergent and mostly allopatric genetic lineages that are reproductively isolated but share a remarkably similar morphology. One such lineage commonly encrusts macroalgae throughout the NE Atlantic coast. To explore the processes leading to geographical diversification, reproductive isolation and speciation in this taxon, we (i) investigated NE Atlantic C. hyalina mitochondrial DNA phylogeography, and (ii) used breeding trials between geographical isolates to ascertain reproductive isolation. We find that haplotype diversity is geographically variable and there is a strong population structure, with significant isolation by distance. NE Atlantic C. hyalina is structured into two main parapatric lineages that appear to have had independent Pleistocene histories. Range expansions have resulted in two contact zones in Spain and W Ireland. Lineage 1 is found from Ireland to Spain and has low haplotype diversity, with closely related haplotypes, suggesting a recent population expansion into the Irish Sea, S Ireland, S England and Spain. Lineage 2 is found from Iceland to Spain and has high haplotype diversity. Complete reproductive isolation was found between some geographical isolates representing both lineages, whereas it was incomplete or asymmetric between others, suggesting these latter phylogeographical groups probably represent incipient species. The phylogeographical distribution of NE Atlantic C. hyalina does not fall easily into a pattern of southern refugia, and we discuss likely differences between terrestrial and marine system responses to Pleistocene glacial cycles.     

Observations on the food of juvenile Atlantic salmon, Salmo salar L, reared in a Scottish hill loch

An analysis of the stomach contents of 0+ and 1 + Atlantic salmon parr, Salmo salar , introduced into a Scottish hill loch showed that benthos, plankton, and surface organisms were all taken. Molluscs comprised a relatively small proportion of the food material, probably because they are less active than other animal groups. The most abundant plankter was Daphnia hyalina. Cyclops spp. were scarce and no Diaptomus spp. were present in the stomachs despite their abundance in the loch plankton. Laboratory experiments indicated that copepods were difficult to capture and that D. hyalina was the organism most frequently selected, even when larger individuals of this species were removed from the environment. Differences between the results from the Scottish loch and similar work in Wales, Sweden and Canada are discussed.     

PHYSIOLOGICAL CHARACTERIZATION OF SIX LIPID-PRODUCING DIATOMS FROM THE SOUTHEASTERN UNITED STATES1

Six strains of diatoms from intertidal waters were isolated as part of the SERI Aquatic Species Program collection and screening effort: Amphiprora hyalina Greville, Cyclotella cryptica Reimann, Lewin & Guillard, Navicula acceptata Hustedt (two strains, NAVIC6 and NAVIC8), Navicula saprophila Lange-Bertalot & Bonik, and Nitzschia dissipata (Kütz.) Grunow. Among numerous algal strains isolated as part of this collection effort, these six strains showed rapid growth and elevated lipid content in preliminary screening experiments and were chosen for further physiological characterization. N. dissipata grew most rapidly at 25°C, whereas the other five strains grew best at 30–35°C. Salinity tolerance varied among strains, with maximal growth occurring at the following conductivities: 10–60 mS.cm^?1 (A. hyalina and N. acceptata NAVIC8), 10–35 mS.cm^?1 (C. cryptica), 20–45 mS.cm^?1 (N. acceptata NAVIC6), 10 mS.cm^?1 (N. saprophila), and 20–35 mS.cm^?1 (N. dissipata). The diatoms also differed in their utilization of nitrogen sources with A. hyalina growing optimally with either nitrate or urea; N. acceptata NAVIC6, with either nitrate or ammonium; C. cryptica, N. acceptata NAVIC8, and N. dissipata, with nitrate; and N. saprophila, with urea. Under optimal conditions, A. hyalina grew at 2.0 doublings. day^?1; C. cryptica grew at 3.0 doublings. day^?1. Each Navicula strain had a growth rate of 3.8 doublings. day^?1, and N. dissipata grew at 2.6 doublings.day^?1. All six strains had lipid contents in excess of 37% ashfree dry weight (AFDW) under nutrient-limited conditions, with N. saprophila having the highest lipid content at 48% AFDW.     

Some effects of enclosure on the zooplankton in a small lake

Observations on the effect of enclosure on zooplankton by introducing two experimental tubes, each holding some 18 000 m³ of water, into a small lake, showed that a limnetic community could be maintained within tubes of this capacity throughout a period of 22 months. Two species, the copepod Diaptomus gracilis and the cladoceran Daphnia hyalina were dominant both in the open lake and in each tube, but Diaptomus gracilis was relatively more abundant in the tubes than in the lake, whereas Daphnia hyalina, especially in spring and autumn, was more abundant in the lake than in the tubes. Several scarce species became relatively more abundant in the tubes than in the lake. These changes are more probably associated with reduced predation, especially by larvae of Chaoborus, than with artificially induced changes in the phytoplankton, changes only poorly correlated with changes in the zooplankton.     

Morphology, phylogeny and biology of Gliocephalis hyalina, a biotrophic contact mycoparasite of Fusarium species

Gliocephalis hyalina, a rarely seen microfungus with a morphology similar to the hyphomycete genus Aspergillus but with slimy conidia was found in a mixed microbial culture from soybean roots. This species has been reported sporadically since 1899, each time in association with other fungi or bacteria. Gliocephalis hyalina has not been maintained in monoxenic culture and requires other fungi to grow. Light and scanning electron microcope studies indicate that it is a biotrophic contact parasite of Fusarium species. The fungus may penetrate the cells but has no apparent deleterious effect on the growth or plant pathogenicity of its host. Phylogenetic analyses of partial nuclear small subunit rDNA sequences place G. hyalina near the Laboulbeniales, an order of obligate insect parasitic microfungi, and the related mycelial genus Pyxidiophora. Gliocephalis hyalina is mycoparasitic along with many Pyxidiophora species. These discoveries suggest that some "unculturable" microorganisms or "cryptic DNA" recovered from environmental DNA samples might represent obligate biotrophs that could be cultured and studied with simple techniques.     

Interspecific hybridization betweenDaphnia hyalina,D. galeata,andD. cucullata and seasonal abundances of these species and their hybrids

The three cladoceran speciesDaphnia hyalina, D. galeata, andD. cucullata frequently coexist in the lakes of northern Germany. Although there are some problems in distinguishing them morphologically, they are easily determined by gelelectrophoresis: each species carries a different allele at the glutamate oxaloacetate transaminase (GOT) locus. Animals morphologically intermediate between two species are heterozygous for the alleles carried by the species they resemble. This pattern is in agreement with the findings at other loci, where also diagnostic alleles exist. These findings are most easily explained by interspecific hybridization between the three species. No evidence is found for backcrosses involving hybrids ofD. cucullata, whereas some backcrosses betweenD. hyalina, D. galeata, and their hybrids are found in some lakes. In four lakes the seasonal abundances of the three species and their hybrids are determined.     

Systematics of Catenulifera (anamorphic Hyaloscyphaceae) with an assessment of the phylogenetic position of Phialophora hyalina

Catenulifera, typified by C. rhodogena (=Scopulariopsis rhodogena), was established to accommodate the anamorphs of Hyphodiscus (Ascomycota, Helotiales) and to delimit these taxa from members of Phialophora section Catenulatae. Catenulifera rhodogena has been inferred as monophyletic, but its relationship to ascomycetes with poorly differentiated phialidic anamorphs remains enigmatic. To test the hypothesis that C. rhodogena is closely related to morphologically similar species of Phialophora and to further explore the systematics of Catenulifera, we analyzed nuclear rDNA and β-tubulin gene sequences of isolates identified as C. rhodogena, Hyphodiscus hymeniophilus, P. brachyconia, P. brevicollaris and P. hyalina. ITS-LSU and ITS-LSU-β-tubulin phylogenies positioned all isolates except P. hyalina in a single, well-supported clade that consisted of three subclades. Subclade 1 included fungicolous isolates of C. rhodogena and H. hymeniophilus that did not fluoresce when exposed to long-wave UV light. Subclade 2 contained fungicolous and lignicolous strains of C. rhodogena that produced fluorescent colonies and possessed a 366bp indel in the LSU rRNA gene. Neither lineage encompassed the ex-type strains of Cistella rubescens (=H. hymeniophilus) or S. rhodogena, but the former isolate was inferred as sister to Subclade 2. Subclade 3 included all isolates of P. brachyconia, a species recognized here as C. brachyconia comb. nov. A fourth isolate of P. brachyconia that was extralimital to Subclade 3 is described as C. luxurians sp. nov. The positions of C. brevicollaris comb. nov., a species based on P. brevicollaris, and C. luxurians were not resolved in the ITS-LSU phylogeny. P. hyalina is not closely related to Catenulifera.     

Hypolimnetic anoxia hampers top–down food-web manipulation in a eutrophic lake

SUMMARY 1. A biomanipulation experiment was carried out in a small (10 ha), but relatively deep (17 m) and highly eutrophic lake in northern Poland. The lake had been stocked in 1996, 1997 and 1998 with a variety of piscivorous fish (pike, catfish, trout and pikeperch), in order to reduce numbers of cyprinid planktivores.
2. Piscivore stocking was associated with a threefold decrease in the offshore fish density (night echosounding). Despite this reduction, the large planktonic cladoceran, Daphnia hyalina , remained scarce, whereas the density of small-sized zooplankton increased greatly.
3. The lack of demographic response in D. hyalina was probably due to the anoxia in the hypolimnetic refuge of this vertically migrating species. The anoxic hypolimnion, below 3–4 m depth, was inhabited day and night by numerous Chaoborus flavicans larvae.
4. Changes in zooplankton were associated with shifts in the taxonomic composition (from single-cell green algae to filamentous cyanobacteria), size structure (from nano- to net phytoplankton) and seasonal dynamics of phytoplankton, but not in the average biomass of planktonic algae. A clear-water phase, which was absent in the prestocking years, developed in spring, with Secchi depth reaching 2.5 m, a value which had never been recorded in the 20 years preceding the biomanipulation. In general, the lake's status was switched from hypertrophic to eutrophic.
5. Deteriorating food conditions, resulting from qualitative changes in the phytoplankton community, combined with predation pressure by the remaining fish and Chaoborus larvae were associated with the ultimate elimination of D. hyalina from the lake.     

Electron transport system (ETS) activity and respiration rate in five Daphnia species at different temperatures

Electron transport system activity (ETS) andrespiratory rate (R) were measured in five Daphnia species at different temperatures in thelaboratory. The animals were collected from differenthabitats: Daphnia hyalina Leydig from aneutrophic subalpine lake, D. pulicariaForbes from an oligotrophic high-mountainlake, D. pulex Leydig from a temporary lowlandpool, and D. obtusa Kurz from a temporaryhighland pool. D. magna Straus was obtained fromlaboratory cultures.ETS activities and respiratory rates were studied injuveniles and adult females without eggs. The rateswere measured at 5, 10, 15, and 20 °C. Foradult females Q₁₀ of ETS-activity ranged from 1.9for D. pulicaria to 2.2 for D. obtusa. Thevalues for juvenile individuals showed greatervariations, ranging from 1.6 for D. pulicaria to3.4 for D. hyalina. Q₁₀ values forrespiration were from 1.3 to 1.7 for adults, and from1.4 to 2.1 for juveniles. The accelerating effect oftemperature (µ) ranged from 18.5 to 93.4 kJ mol^-1.Average ETS/R ratios for single species for two lifestages ranged from 1.0 to 2.5.     

Lampropedia hyalina Schroeter,eine apochlorotische Merismopedia (Cyanophyceae)

Zusammenfassung Lampropedia hyalina, die bisher zu den Bakterien gestellt worden war, verriet sich durch die Art der Bewegung, wie sie nur für Cyanophyceen bekannt ist, als eine apochlorotische Merismopedia.Dadurch sind die farblosen Cyanophyceen um eine Lebensform bereichert worden, die besonders deutlich zeigt, daß der Pigmentverlust in dieser Klasse mehrfach und in mehreren Untergruppen erfolgt ist und zu einer Vielfalt von Organismen geführt hat, die Bakterien ähneln können, aber immer von ihnen zu unterscheiden sind.

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Summary Lampropedia hyalina Schroeter 1886 is a colourless microorganism forming small tablets that originate by division of the cells in two directions of the space. These then fragment into smaller tablets renewing the course of development without any other form of reproduction being known.This peculiar organism has hitherto been grouped among Bacteria until it was recently observed to exhibit the slow, irregular mode of locomotion only known in non-filamentous Cyanophyceae. Lampropedia has therefore to be regarded as an apochlorotic species of Merismopedia to which it is morphologically very similar.The colourless Cyanophyceae have thus been enriched by an organism which proves that the loss of photosynthetic pigments has in this class occurred repeatedly and in several taxonomic groups. A considerable number of forms of diverse appearances and with different kinds of reproduction have this way come into being. Although they may to the less experienced observer simulate Bacteria they can in every case be discerned.