Behavior of zoospores of Phytophthora megasperma var. sojae and P. drechsleri in soil

1972 ◽  
Vol 50 (11) ◽  
pp. 2125-2130 ◽  
Author(s):  
R. S. Mehrotra
Keyword(s):  
Fluorescence Microscope ◽  
Natural Soil ◽  
Moderate Degree ◽  
Percentage Germination ◽  
Phytophthora Megasperma ◽  
Potential Capacity ◽  
Perfusion Apparatus ◽  
Phytophthora Drechsleri ◽  
Germ Tubes ◽  
Modified Soil

Experiments done with the modified soil perfusion apparatus indicate the potential capacity of the zoospores and cysts of Phytophthora drechsleri and P. megasperma var. sojae as inoculum units in soil. The results indicate that although zoospores/cysts do not retain infectivity for months, those of P. drechsleri do not lose it very rapidly. Experiments done to find out the period of motility of zoospores have shown that some zoospores of P. drechsleri and P. megasperma var. sojae remained motile for up to 30 and 24 h respectively. Saprophytic behavior of the two species of Phytophthora has been studied with the help of a fluorescence microscope and using a fluorescent dye. Cysts of P. drechsleri and P. megasperma var. sojae germinate to a moderate degree in natural non-amended soil. Germination ranged from 30 to 50% in the case of P. drechsleri and 15 to 25% in P. megasperma var. sojae. Amending the soil with 0.4% glucose, 0.4% asparagine increased the percentage germination of cysts in natural soil. Germ tubes of a small percentage of cysts in the two species terminate in miniature sporangia-like structures.

FACTORS GOVERNING ZOOSPORE RESPONSES OF PHYTOPHTHORA MEGASPERMA VAR. SOJAE TO PLANT ROOTS

1967 ◽  
Vol 45 (11) ◽  
pp. 1983-1994 ◽  
Author(s):  
H. H. Ho ◽  
C. J. Hickman
Keyword(s):  
Root Exudate ◽  
Chemical Nature ◽  
Root Surface ◽  
Plant Roots ◽  
Root Tip ◽  
Phytophthora Megasperma ◽  
Negative Pole ◽  
New Feature ◽  
Germ Tubes ◽  
Cyst Germination

In the presence of plant roots, zoospores of Phytophthora megasperma var. sojae reacted in general as do other fungal zoospores: they were attracted to, and trapped in the immediate vicinity of the root surface, on which they encysted rapidly. Encysted zoospores formed a continuous sheath around the root, thickest just behind the root tip. Cyst germination was stimulated. Germ tubes were always initiated from the side of cysts closest to the root and grew towards it. In addition, a new feature was observed, suppression of repeated emergence of zoospores. Zoospore accumulation was nonspecific with respect to host and non-host, resistance, and susceptibility.Tests with exudates and extracts from roots of resistant and susceptible soybean varieties and a non-host, pea, confirmed the chemical nature of the stimulus inducing these responses. Zoospores observed in an electric field were not attracted towards either pole, but they were trapped and encysted rapidly around the negative pole. Cyst germination was not stimulated. Nevertheless, since encystment was more pronounced on root exudate agar mounted on the negative pole, electric charges on roots may also contribute to inducing early encystment of zoospores there.In an investigation of ions on zoospore responses, with ionic resins, all phases of zoospore response to roots, with the exception of attraction, occurred in the presence of hydrogen resin particles.

A SLIDE TECHNIQUE FOR THE STUDY OF FUNGI AND ACTINOMYCETES IN SOIL WITH SPECIAL REFERENCE TO HELMINTHOSPORIUM SATIVUM

1953 ◽  
Vol 31 (6) ◽  
pp. 718-724 ◽  
Author(s):  
S. H. F. Chinn
Keyword(s):  
Special Reference ◽  
Soybean Meal ◽  
Fusarium Culmorum ◽  
Natural Soil ◽  
Penicillium Notatum ◽  
Amended Soils ◽  
Helminthosporium Sativum ◽  
Stachybotrys Atra ◽  
Slide Technique ◽  
Germ Tubes

A slide technique suitable for studying the behavior of fungi and actinomycetes both qualitatively and quantitatively in soil is described. Besides Helminthosporium sativum, eight other fungi and one actinomycete were used to demonstrate the applicability of the method which was used for both natural and soybean meal amended soils. In the natural soil spores of Penicillium notatum, Stachybotrys atra, and the actinomycete only germinated. However, lysis or disintegration of the germ tubes of the two fungi was observed on the fourth day. Growth of the actinomycete was continuous to at least the seventh day. In the amended soil only one fungus failed to germinate. Of those that germinated, only Fusarium culmorum and the actinomycete were capable of continued growth and sporulation. Lysis or disintegration of the germ tubes of the others was noticed on the fourth day.

Effects of osmotic potential on germination of microsclerotia and growth of colonies of Verticillium dahliae

1976 ◽  
Vol 54 (11) ◽  
pp. 1214-1220 ◽  
Author(s):  
Huynh Congly ◽  
Robert Hall
Keyword(s):  
Verticillium Dahliae ◽  
Osmotic Potential ◽  
Aqueous Media ◽  
Germination Percentage ◽  
Maximum Activity ◽  
Percentage Germination ◽  
Sucrose Solutions ◽  
Agar Media ◽  
The Mean ◽  
Germ Tubes

The influence of available water, expressed as osmotic potential (ψs), on germination of microsclerotia (MS) and expansion of colonies of Verticillium dahliae was studied in osmotically adjusted aqueous and agar media. In distilled water (ψs = 0 bar) at 25 °C, 64–70% of MS germinated within 36 h and the mean number of germ tubes per germinated MS (germination vigour) was 4.7. In aqueous solutions of KCl or NaCl percentage germination and germination vigour were increasingly inhibited as ψs was lowered, reaching 50% inhibition at −11 to −14 bar and 100% inhibition at < −98 bar. In aqueous sucrose solutions germination percentage and vigour were significantly higher (P = 0.05) than in salt solutions; maximum activity occurred at −4 bar, 50% inhibition occurred at −40 bar, and 100% inhibition occurred at < −114 bar. On corn meal dextrose agar (CMDA) amended with KCl, percentage germination at 25 °C was maximal at −9 bar, was reduced 50% at −40 bar, and was 0 at −90 bar. For a given ψs, germination percentages at 25 and 30 °C were significantly greater than at 20 and 15 °C. No germination occurred at 4 or 35 °C. Where ψs was adjusted with KCl, agar media were less inhibitory to germination than aqueous media between 0 and −50 bar. On CMDA media amended with KCl, colony expansion was progressively faster as ψs was lowered from −1.1 to −13 bar, then progressively slower as ψs was lowered further. Rates of colony expansion at 20 and 25 °C were significantly greater than at 4, 15 and 30 °C. At 25 °C growth was reduced 50% at −49 bar and was completely suppressed at −119 bar.

ASEXUAL REPRODUCTION AND BEHAVIOR OF ZOOSPORES OF PHYTOPHTHORA MEGASPERMA VAR. SOJAE

1967 ◽  
Vol 45 (11) ◽  
pp. 1963-1981 ◽  
Author(s):  
H. H. Ho ◽  
C. J. Hickman
Keyword(s):  
Germ Tube ◽  
Solid Surfaces ◽  
Extreme Temperatures ◽  
Phytophthora Megasperma ◽  
Frequent Contact ◽  
Ph Values ◽  
Pure Cultures ◽  
And Behavior ◽  
Germ Tubes ◽  
Cyst Germination

A method was devised to produce abundant zoospores in distilled water suspension from pure cultures of Phytophthora megasperma var. sojae. Sporangia were predominantly non-papillate, but occasionally inconspicuously or conspicuously papillate, germinating with the formation of a delicate, evanescent vesicle. Proliferation of sporangia was observed.Flagella action of freely swimming zoospores was investigated photographically. Both flagella were proved to undulate. Zoospores remained motile longest at 15 °C. Motility was markedly reduced at extreme temperatures (5 and 36 °C), at extreme pH values (below 5.2 or above 9.25), or by mechanical disturbance, dilution, and frequent contact with solid surfaces. The fate of flagella during encystment was followed. Encysted zoospores germinated by germ tubes, or by secondary zoospores, or in rare cases, the germ tube was terminated by a miniature sporangium. Repeated emergence of zoospores was favored at 15 °C whereas total cyst germination and germ tube production was best at 25 °C and in the presence of nutrients.

Formation of microsclerotia and chlamydospores from conidia of Alternaria brassicae

1977 ◽  
Vol 55 (10) ◽  
pp. 1276-1281 ◽  
Author(s):  
A. Tsuneda ◽  
W. P. Skoropad
Keyword(s):  
Rose Bengal ◽  
Room Temperature ◽  
Agar Medium ◽  
Cold Temperature ◽  
Natural Soil ◽  
Malt Extract ◽  
Alternaria Brassicae ◽  
Direct Production ◽  
Extract Solution ◽  
Germ Tubes

Conidia of Alternaria brassicae are transformed into microsclerotia on some naturally infected, partially decayed rapeseed leaves stored at 3 °C in the dark. On V-8 juice agar medium, formation of microsclerotia occurs after 2-week-old cultures are exposed to 3 °C for at least 6–10 days. When rose bengal is added to the medium, growth is restricted and the transformation of conidia into microsclerotia is also initiated during gradual desiccation. Mature microsclerotia are darkly pigmented, many-celled, unevenly spheroidal, and about 60–150 μm in diameter. Microsclerotia are resistant to desiccation and freezing. On a 1% malt extract solution, germination of frozen–thawed microsclerotia results almost exclusively in the direct production of conidiophores and conidia, and germination of untreated microsclerotia results primarily in the production of germ tubes that extended into hyphae.Chlamydospores also form within conidium cells after cold temperature (3 °C) treatment or during gradual desiccation in cultures. Conidia placed on natural soil at room temperature become empty or form endocellular chlamydospores.

Carbon and nitrogen requirements for macroconidial germination of Fusarium solani: dependence on conidial density

1970 ◽  
Vol 16 (8) ◽  
pp. 733-740 ◽  
Author(s):  
G. J. Griffin
Keyword(s):  
Fusarium Solani ◽  
Germ Tube ◽  
Tube Length ◽  
Inorganic Salts ◽  
Percentage Germination ◽  
Medium Ph ◽  
Carbon And Nitrogen ◽  
Germ Tube Length ◽  
Germ Tubes

Washed, PGA-grown macroconidia of F. solani did not require exogenous carbon or nitrogen for rapid (within 7 h), complete germination in a phosphate-buffered inorganic salts medium (pH 5.7) when the density of conidia was 3 × 103/ml or 3 × 102/ml. Rapid germination of macroconidia was fully dependent on exogenous carbon at 3 × 105 conidia/ml. Full dependence on both exogenous carbon and nitrogen was observed near 1 × 106 conidia/ml. Incomplete and slow germination of macroconidia was observed over 978 h at 6.4 × 105 and 3.2 × 105 conidia/ml in the absence of exogenous carbon and nitrogen.When glucose and NH4Cl were supplied at 4.0 μg C plus 0.26 μg N/ml or 40 μg C plus 2.6 μg N/ml, percentage germination of macroconidia, number of germ tubes/macroconidium, and mean germ tube length increased as the density of conidia decreased between 6.4 × 105 and 6.4 × 104 conidia/ml. Percentage germination increased as conidial density decreased between 3.1 × 106 and 3.1 × 104 conidia/ml when glucose and NH4Cl were supplied at each density at constant low amounts/conidium. Chlamydo–spore morphogenesis on germ tubes closely followed macroconidial germination in media initially containing low or no glucose and NH4Cl. The possible relation of these findings to macroconidial germination and chlamydospore morphogenesis in soil is discussed.

Scanning x-ray fluorescence microscopy and principal component analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1752-1753
Author(s):  
Brian Cross
Keyword(s):  
Principal Component Analysis ◽  
Fluorescence Microscopy ◽  
Spatial Resolution ◽  
High Speed ◽  
Image Acquisition ◽  
Principal Component ◽  
Fluorescence Microscope ◽  
Acquisition Rate ◽  
X Ray ◽  
Speed Up

A relatively new entry, in the field of microscopy, is the Scanning X-Ray Fluorescence Microscope (SXRFM). Using this type of instrument (e.g. Kevex Omicron X-ray Microprobe), one can obtain multiple elemental x-ray images, from the analysis of materials which show heterogeneity. The SXRFM obtains images by collimating an x-ray beam (e.g. 100 μm diameter), and then scanning the sample with a high-speed x-y stage. To speed up the image acquisition, data is acquired "on-the-fly" by slew-scanning the stage along the x-axis, like a TV or SEM scan. To reduce the overhead from "fly-back," the images can be acquired by bi-directional scanning of the x-axis. This results in very little overhead with the re-positioning of the sample stage. The image acquisition rate is dominated by the x-ray acquisition rate. Therefore, the total x-ray image acquisition rate, using the SXRFM, is very comparable to an SEM. Although the x-ray spatial resolution of the SXRFM is worse than an SEM (say 100 vs. 2 μm), there are several other advantages.

The role of immunohistochemistry in the diagnosis of cervical intraepithelial neoplasia of different severity

2016 ◽  
pp. 138-140
Author(s):  
S.I. Zhuk ◽  
◽  
O.A. Taran ◽  
A.N. Koshmienskaya ◽  
T.V. Lobastova ◽  
...  
Keyword(s):  
Protein Expression ◽  
Cervical Intraepithelial Neoplasia ◽  
Precancerous Lesions ◽  
Molecular Genetic ◽  
Intraepithelial Neoplasia ◽  
Reproductive Age ◽  
Moderate Degree ◽  
Ki 67 ◽  
The Third ◽  
Diagnosis And Prognosis

The objective: the finding of protein expression of apoptosis regulator BCL-2, Smooth Muscule Actin and the antigen Ki-67 in cervical intraepithelial neoplasia of different severity to optimize the diagnosis and prognosis of the disease. Patients and methods. The study involved 42 women of reproductive age with cervical intraepithelial the neoplasia of the cervix varying degrees applied to the doctor of cervical pathology Zhitomir regional oncologic dispensary. All women (n=42) were divided into groups. The first group included 15 patients (35.7%) with cervical intraepithelial neoplasia with mild. The second group included 13 women (31%) with cervical intraepithelial neoplasia a moderate degree. The third group was represented by patients with cervical intraepithelial neoplasia with severe – 14 respondents (33.3 per cent). Results. Marker BCL-2 in patients of the first group was positive in 7 patients (46.7%), Smooth Muscule Actin was positive in 9 patients (60%) and Ki-67 was diagnosed in 8 of the surveyed women (53.3%). In the second group of BCL-2 was positive in 8 patients (61.5%), Clone 124, Smooth Muscule Actin, Clone 1A4 was positive in 9 patients (69.2%), and Ki-67 was diagnosed in 12 of the surveyed women (92.3%). Marker BCL-2 in patients of the third group was positive in 12 patients (85.7%), Smooth Muscule Actin was positive in 10 patients (71.4%) and Ki-67 was diagnosed in 13 of the surveyed women (92.9% ). Conclusion. Carcinogenesis is associated with molecular genetic damage to the cervix. Some of the products of this process can be used as prognostic and diagnostic markers of tumor progression. Determination of protein expression of apoptosis regulator BCL-2, Smooth Muscule Actin and the antigen Ki-67 in cervical intraepithelial neoplasia makes it possible to accurately verify the diagnosis and to predict the course of pathological changes in the flat epithelium of the cervix. Key words: cervical intraepithelial neoplasia, cervical cancer, morphological diagnostics of precancerous lesions, BCL-2, Smooth Muscule Actin, Ki-67.

Assessing the mortgage potential capacity of regions: A methodology and indicators

2020 ◽  
Vol 18 (2) ◽  
pp. 381-396
Author(s):  
T.S. Korosteleva ◽  
◽  
V.E. Tselin ◽  
Keyword(s):  
Potential Capacity
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