Some Observation on the Alga Fragilaria crotonensis Kitton and its Parasitism by Two Chytridiaceous Fungi

It has been shown by experimentation that two morphologicallydistinct clones of Fragilaria crotonensis Kitton, isolated fromthe plankton of Windermere at approximately the same time, wereaffected quite differently by the chytrid Rhizophydium fragilariaeCanter. In one case the diatom filaments became heavily parasitizedand could be used for the maintenance of the fungus. In theother case infection was negligible. Additional clones, representative of these two morphologicalforms, from other bodies of water in the Windermere drainagebasin were tested. The same pattern of infection or relativenon-infection again ensued in direct accordance with the particulartype of filament used. Some preliminary experiments undertaken with a second, as yetlittle known chytrid parasite of F. crotonensis are reported.In this instance the fungus appeared to find its natural hoston cells belonging to the morphological form which failed tosupport the continued increase of R. fragilariae. The parasitism of morphological variants of F. crotonensis bythese fungi in the wild from Britain and else where is discussed. Fragilaria crotonensis Kitton, Rhizophydium fragilariae Canter, chytrid, diatom, parasitism, culture     

A Study of Two Morphological Variants of the Diatom Fragilaria crotonensis Kitton using Electron Microscopy

Two forms of Fragilaria crotonensis Kitton, one with flaredends to the cells, the other with ends that taper to a narrowrod-like tip, were previously distinguished by light microscopyand by their contrasting relationships with the parasitic chytridsRhizophydium fragilariae Canter and one referred to as species3. Examples of the above diatom types, taken from a number ofgeographically widely separated lakes, have been examined byelectron microscopy. Additional morphological differences aredescribed. The ocellus in flared-type cells consists of 4–5rows of pores while in rod-type cells fewer (2–3) rowsof pores are present. Valve thickenings on the mantle at theapex of rod-type cells are rarely visible whereas in flared-typecells they are usually very prominent. A rimoportula was presentin both cell types. In flared cells its external aperture liesimmediately behind the apex usually in line with the striaeand the internal aperture is often orientated with its longaxis oblique to that of the diatom cell. The rimoportula inrod-type cells opens at the centre of the valve face and theinternal aperture is orientated at 90° to the apical axisof the valve. Comparison made with type material suggests thatthe rod-form should be recognized as F. crotonensis var. crotonensisand the flared-form as var. prolongata Grunow ex van Heurck. Fragilaria crotonensis, diatom, systematics, chytrid infection, rimoportula     

The influence of summer/winter conditions of temperature and irradiance on diel oscillations in photosynthesis by Fragilaria crotonensis

SUMMARY. 1. The common pennate diatom (Bacillaryiophyta) Fragilaria crotonensis Kitton showed strong periodicity in its photosynthesis -irradiance (P—I) relationship under summer conditions of high irradiance and temperature which damped progressively throughout the growth phase. Under winter conditions of low irradiance and temperature, weak periodicity was observed.
2. The amplitude of diel oscillations in photosynthesis as a function of irradiance under winter conditions showed only slight variation throughout the growth phase. Under summer conditions, however, amplitudes for both α and P_max were highest in the early exponential phase, declining progressively during growth.
3. These results indicate that the occurrence of periodicity is dependent, in part, on the growth phase of the cells and, in part, on environmental parameters of irradiance and temperature variations under simulated summer and winter conditions.     

The effect of mercury on the growth rate of Fragilaria crotonensis kitton and Asterionella formosa Hass.

The effects of two mercury salts Hg(NO₃)₂ and HgCl₂ on the growth rate ofFragilaria crotonensis Kitton andAsterionella formosa Hass. were investigated.Fragilaria crotonensis showed total inhibition at 0.1 ppm and a 4 day increase in lag phase along with a 2–4 fold reduction in growth rate at 0.05 ppm.Asterionella formosa showed a gradual increase in lag phase and reduction in growth rate with increasing concentrations of mercury up to 0.25 ppm with total inhibition at 0.5 ppm. Mercury salts in cultures of both species with soil extract additives were significantly less toxic than in totally defined systems. Cultures ofA. formosa deviated from the typical 8–16 celled stellate colony at sublethal concentrations to form large cylindrical stacks composed of 25 to 30 colonies.This study was supported in part by funds provided by the Navajo and Kaiparowits project participants.This study was supported in part by funds provided by the Navajo and Kaiparowits project participants.     

Kinetics of glucose stimulatory effect on silica deposition and growth of natural populations of Fragilaria crotonensis

Diatoms are known to exploit organic substrates for growth; however, convincing evidence that they can utilize dissolved organic carbon under natural conditions is not available. In 2008–2009, we performed in situ experiments examining the effect of glucose addition on silica deposition kinetics and growth rates of Fragilaria crotonensis in the eutrophic ?ímov Reservoir (Czech Republic). Silica deposition kinetics was measured at 4‐h intervals over a 24‐h incubation with PDMPO [2‐(4‐pyridyl)‐5{[4‐dimethylaminoethyl‐aminocarbamyl)‐methoxy] phenyl}oxazole] fluorescence probe. A significant stimulatory effect of glucose supplemented at the concentration of 10^?4 M on Fragilaria silification was observed at 20 and 24 h. Fragilaria growth rates almost doubled upon glucose enrichment compared with the untreated control at 24 h. In addition, we conducted a dose‐response experiment testing the glucose additions from 10^?8 to 10^?3 M in a 24‐h incubation. Glucose stimulated both Fragilaria silification and growth at concentrations >10^–7 M, which might occasionally occur in a reservoir as a result of accidental contamination of water by organic pollution.     

Parasitism of Xiphinema rivesi and X. americanum by Zoosporic Fungi

Living Xiphinema americanum (Xa) and X. rivesi (Xr) extracted from soil samples and stored for 1-5 days at 4 or 20 C contained aseptate fungal hyphae. The fungi directly penetrated the nematode''s cuticle from spores encysted near the head. Penetration through the stoma, vulva, or anus was rare. Catenaria anguillulae (Cat), Lagenidium caudatura (Lag), Aphanomyces sp. (Aph), and Leptolegnia sp. (Lep) were isolated into pure culture from infected nematodes. The pathogenicity of these zoosporic fungi was determined by incubating mixed freshly extracted Xa and Xr in 2% soil extract (pH = 6.7, conductivity = 48 μmhos, 20 ± 2 C) containing zoospores obtained from single-spore isolates. After 4 days, Cat, Lag, Aph, and Lep had infected 78, 18, 13, and 22%, respectively, of the nematodes. Both Xa and Xr were infected by every fungus; however, the relative susceptibility of Xa and Xr to these fungi was not determined. All noninoculated control nematodes remained uninfected and alive. In a second experiment, parasitism of Xa and Xr by Aph and Lep was increased when nematodes were incubated in 2% soil extract for 4 days before exposure to zoospores. In a third experiment, parasitism of Xa and Xr by Cat was greater in diluted saturation soil extract (conductivity = 100-400 μmhos) than in undiluted saturation extract (conductivity = 780 μmhos). Cat produced small zoospores (4-μm-d), bulbous infection hyphae, and assimilative hyphae of varying diameters in nematodes, whereas Lag, Aph, and Lep produced large zoospores (8-μm-d) and tubular, uniform infection and assimilative hyphae in nematodes.     

产银杏内酯内生真菌的筛选及培养条件研究

通过对内生真菌的发酵提取物进行TLC和HPLC-UV分析,进行菌株筛选;对该菌株在不同培养基上的生长情况、产孢量、银杏内酯类物质产量的测定,确定最佳培养基;并用HPLC-ELSD测定了不同时间段的发酵液中银杏内酯类物质含量。结果,筛选出一株产量较高的烟曲霉原变种(Aspergillus fumigatusvar.fumigatus)FG052;对其培养条件的研究表明,PDA培养基、查氏培养基分别为其最佳传代和发酵培养基,菌丝最大生物量在发酵168 h,产银杏内酯类物质高峰在发酵144 h,此时总内酯产量可达0.13 mg/mL,pH值为4.86。本实验筛选的菌株稳定性较好,筛选的培养基价格低廉,碳氮比明确,且总内酯的产量高,可作为规模生产银杏内酯类物质的培养基。     

丛枝菌根真菌离体培养研究概况(综述)

本文综述丛枝菌根真菌在离体条件下的生长发育、生长促进物质及生理生化代谢等方面的研究概况。     

Fungal Parasitism of Heterodera glycines Eggs as Influenced by Egg Age and Pre-colonization of Cysts by Other Fungi

The objective of this study was to determine the effect of egg age and pre-colonization of cysts by a saprophytic or parasitic fungus on parasitism of Heterodera glycines eggs by other parasitic fungi. In agar and in soil tests, fungi generally parasitized more eggs in early developmental stages than eggs containing a juvenile. The effect of pre-colonization of cysts by a fungus on parasitism of eggs by other fungi depended on the fungi involved. In most cases, pre-colonization of cysts by an unidentified, saprophytic fungal isolate (A-1-24) did not affect parasitism of eggs in the cysts subsequently treated with other fungi. However, pre-colonization of cysts by A-1-24 reduced fungal parasitism of eggs in cysts subsequently treated with Cylindrocarpon destructans isolate 3. In agar tests, pre-colonization of cysts by Chaetomium cochliodes, a saprophytic or weakly parasitic fungus, reduced parasitism of eggs in cysts subsequently treated with Verticillium chlamydosporium Florida isolate, Fusarium oxysporum, Fusarium solani, ARF18, and another sterile fungus. However, in soil tests, pre-colonization of cysts by C. cochliodes had no effect on parasitism of eggs by subsequent fungal parasites. In another test, parasitism of eggs by V. chlamydosporium in cysts was not affected by pre-colonizing fungi C. destructans, F. oxysporum, and F. solani but was reduced by Mortierella sp., Pyrenochaeta terrestris, and C. cochliodes. Parasitism of eggs in cysts by ARF18 was reduced by pre-colonizing fungi C. destructans, F. oxysporum, F. solani, P. terrestris, and C. cochliodes but not Mortierella sp.     

Studies in the Physiology of Parasitism: XXXIV. Further Experiments on the Killing of Plant Cells by Fungal and Bacterial Extracts

When cucumber and turnip tissues were subjected to enzyme preparationsof Botrytis cinerea and Bacterium aroideae in the presence ofplasmolysing concentrations of various crystalloids, killingof cells was retarded out of all proportion to the slight retardingeffect on maceration. When the tissue cells were recovered fromplasmolysis they regained their sensitiveness to the toxic action.Toxicity of mercuric chloride and oxalic acid was also muchreduced when cells were plasmolysed. Fractional precipitation with various proportions of acetoneand over a wide range of pH gave preparations which varied in.activity from one treatment to another, but their maceratingand toxic actions varied together. After partial maceration, plant tissues were much more sensitiveto the toxic action of mercuric chloride or oxalic acid. Thisis interpreted as meaning that, before maceration is complete,the toxic principle has been able to reach the protoplasticsurface and to exert a deleterious effect upon it. The evidence presented gives further support to the view thatthe enzyme system of the two pathogenic organisms which maceratesthe host cell walls also brings about death of the protoplasts.     

一种便于丝状真菌显微观察的培养方法

在真菌培养过程中,对其个体形态与群体（菌落）形态进行实时观察与鉴定是很必要的。本文利用半培养基培养法结合显微操作技术,对丝状真菌个体与群体进行形态学观察。结果表明,该方法无需染色与制片,不破坏菌丝正常生长状态,可实时进行形态学检测,对多个菌种在自然生长状态下的菌丝与菌落特征进行观察,操作简单、方便、快捷,从而降低了成本及工作量。     

海南革菌初步研究(英文)

初步研究了中国海南省的革菌,共发现37种革菌,其中绝大部分种类为海南首次报道。锗边刺革孔菌(Hymenochaete ochromarginata)为中国一新记录种,并对该种进行了描述。台湾丝齿菌(Hyphodontia taiwaniana)为大陆首次发现。名录中列出了每个种的标本信息。     

A Comparative Study of Caffeine Degradation by Four Different Fungi

The objective of the present study is to investigate the caffeine-degrading abilities of different fungi and to apply this knowledge to environmental remediation and industrial decaffeination process. Chrysosporium keratinophilum, Gliocladium roseum, Fusarium solani, and Aspergillus restrictus were isolated from the coffee pulp obtained from a coffee estate. Pure cultures of fungi were isolated on standard conventional potato dextrose broth (PDB) medium and authenticated. Pure cultures were subjected to a caffeine tolerance study at different concentrations of caffeine (1–8 g/L) in potato dextrose agar (PDA) and minimal media. On PDA, Fusarium solani could tolerate caffeine concentration up to 8 g/L, whereas Chrysosporium keratinophilum, Gliocladium roseum, and Aspergillus restrictus could tolerate up to 6 g/L. On minimal agar medium containing different concentrations of caffeine (1–8 g/L), Fusarium solani tolerated up to 8 g/L and the other fungi up to 2 g/L. A time-bound caffeine degradation study was undertaken at 1 g/L concentration of caffeine and glucose in nitrogen-containing and nitrogen-free liquid minimal media by subjecting the four fungi to shake flask culture at 120 rpm and 30°C. Degradation of caffeine up to 7 days at 24-h intervals was analyzed by high-performance liquid chromatography (HPLC). Gliocladium roseum followed by Aspergillus restrictus showed maximum degradation of caffeine at 0.47 and 0.3 mg/ml, respectively, by 96 h in nitrogen-containing minimal medium, whereas Fusarium solani showed maximum degradation of caffeine by 48 h (0.35 mg/ml) and Chrysosporium keratinophilum by 72 h (0.29 g/ml). In nitrogen-free minimal medium, Chrysosporium keratinophilum showed maximum degradation of caffeine at 72 h (0.45 mg/ml), followed by Gliocladium roseum, Fusarium solani (0.3 mg/ml), and Aspergillus restrictus (0.25 mg/ml) at 96 h. Overall, Chrysosporium keratinophilum showed a comparatively higher rate of caffeine degradation in minimal medium with or without a nitrogen source as compared with the other three fungi, indicating that nitrogen affects caffeine metabolism.     

Culture and Motion Analysis of Diatom Bacillaria paradoxa on a Microfluidic Platform

We proved the feasibility of using a microfluidic chip to culture diatom Bacillaria paradoxa, and analyzed the gliding characteristics of its self-organized colony in detail. The optimal cultivation parameters of B. paradoxa for the designed chip made with polydimethylsiloxane are as follows: the preferable cells injecting rate for keeping the cells alive is 0.2 mL/h, the initial cell density for fast reproduction is 5.5 × 10⁴ cells/mL, and the optimal replacement period of culture medium is 4 days. B. paradoxa tends to form a colony during their growth, and the colony can glide with a steady period of 29 ± 3 s along its axial direction in a constant stream, the amplitude of the colony will not decay (e.g., 24 μm of two-cell colony at 1.1 mm/s flow rate), and the colony rapidly adjusts its direction of gliding to the direction of water flow. The successful culture of diatoms on a microfluidic platform may be used for biosensing chips and the creation of gasoline-producing diatom solar panels.     

几株非模式白腐菌降解能力的研究

利用愈创木酚选择培养基,从11种白腐菌株中定性筛选出3株白腐菌,分别是毡毛栓孔菌Trametes velutina Dai10149、鍺栓孔菌T.ochracea Cui 6888、绒毛栓孔菌T.pubescens Cui 7571。重量法绘制它们的生长曲线,同时测定其蛋白质含量及胞外酶活。通过比较发现,绒毛栓孔菌T.pubescens Cui 7571的生长速度快,且具有较强及稳定的酶活分泌能力;对针叶植物、阔叶植物及单子叶草本的木质纤维素均表现出较好的降解效果。     

A Study of Nitrate Reduction in Mould Fungi

1. The activity of the nitrate-reducing (nitratase) system infungal mycelium was measured by incubation of the mycelium (eitherintact or ground) with nitrate in the presence of sodium fluoridewhich blocks nitrite reduction and causes nitrite accumulation. 2. The nitrate-reducing system in the fungi examined shows rapidchanges in activity in response to some environmental factors.Nitratase activity of mycelium in glucose-nitrate medium fallsto a low value within 1 hour after addition of ammonia and remainsat this value until all added ammonia has been assimilated.The fall in activity appears to depend on the assimilation ofammonia by the mycelium, since it did not occur in conditionswhen assimilation was prevented. 3. Nitrate-reducing activity declines rapidly in the absenceof assimilable carbohydrate, and recovers equally rapidly whencarbohydrate is restored. Recovery is accelerated by nitratebut almost completely prevented by ammonia. 4. Evidence is given that these variations in nitrate reductionare primarily changes in the nitrate reductase link in the enzymesystem. Nutritional behaviour of the fungi investigated is closelycorrelated with the observed changes in activity of their nitratereductase. 5. Nitrate reductase may be formed by these fungi when grownin complete absence of nitrate.     

Parasitism by unionicola spp larvae on chironomids

Mite larvae belonging to the genus Unionicola hatch from eggs laid in freshwater mussels. Larvae of the same genus are found attached to the legs and abdomens of adult Chironomids. Larvae from these two very different habitats are described and it is demonstrated that two of those found on Chironomids are identical with two obtained from mussels. It is thus confirmed that some mites of the genus Unionicola which lay their eggs in mussels also have larvae which parasitise Chironomids.

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Zusammenfassung Wassermilbenlarven von der Gattung Unionicola entwickeln sich in Eiern, die in Süsswassermuscheln abgelegt werden. Larven von der gleichen Gattung sind and den Beinen und Hinterleibern von erwachsenen Chironomiden zu finden. Larven von diesen beiden sehr verschiedenen Fundorten werden beschrieben, und es wird gezeigt, dass zwei von den an Chironomiden gefundenen mit zwei von den in Muscheln ausgebrüteten Arten identisch sind. Es wird somit beweisen, dass einige Milben von der Gattung Unionicola, die ihre Eier in Muschlen ablegen, auch Larven haben, die Chironomide parasitieren.

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Resumé Les larves des Hydrachnes du genre Unionicola sortent des oeufs qui sont pondus dans les moules d'eau douce. On trouve les larves du même genre attachées aux jambes et aux abdomens des Chironomes adultes. Les larves issues de ces deux habitats tres différents sont décrites et on démontre que deux de celles qui ont été trouvées sur les Chironomes sont identiques aux deux venant des moules. On a ainsi confirmé que certains Hydrachnes du genre Unionicola qui pondent des oeufs dans les moules ont aussi des larves qui vivent au parasites chez les Chironomes.