Watermelon mosaic virus 1 and 2 in Queensland cucurbit crops

1978 ◽  
Vol 29 (6) ◽  
pp. 1235 ◽  
Author(s):  
RS Greber

Watermelon mosaic virus type 1 (WMV-1) has not previously been reported from Australia and has become prevalent in Queensland only since 1970. Watermelon mosaic virus type 2 (WMV-2) continues to reach a high incidence in marrow (Cucurbita pepo) and pumpkin (Cucurbita maxima and Cucurbita moschata) crops, WMV-2 is rarely isolated from watermelons (Citrullus vulgaris) in which epidemics of WMV-1 now cause serious reductions in yield. The Queensland Blue cultivar of C. maxima, the most important cucurbit crop, produces severely distorted fruit following infection by WMV-1, although it is little affected by WMV-2. Physical properties of these WMV isolates and electron microscopic examination of the virus particles and associated cellular inclusions showed them to be similar to those reported elsewhere, but there were some distinctive host reactions for the WMV-2 isolates. No resistance to either WMV-1 or WMV-2 was found in commercially available C. pepo, C. maxima or C. vulgaris. The resistance of Cucumis metuliferus to Australian WMV-1 isolates was confirmed, and a source of resistance to both WMV-1 and WMV-2 was found in Lagenaria siceravia. Methods of separation of WMV-1 and WMV-2 from mixed isolates and methods for the identification of each on differential hosts and by serology were shown to be effective.

1971 ◽  
Vol 134 (4) ◽  
pp. 886-906 ◽  
Author(s):  
John Swanson ◽  
Stephen J. Kraus ◽  
Emil C. Gotschlich

The four colony types of several different strains of gonococci were isolated by selective transfers on agar. These colony variants differed in the degree of autoagglutination which occurred when they were grown in fluid medium. It was found that this clumping behavior was related to the colonial type, with type 2 isolates exhibiting the greatest autoagglutination followed by types 3, 1, and 4. Electron microscopic examination of thin sections indicated that the clumping in fluid medium was mediated by peculiar zones of adherence of the outer membranes of gonococci. These resembled the gap junctions seen in animal cell systems but differed in that the gonococcal membranes involved in the zone of adherence did not bear typical surface modifications. Electron microscopic study of negatively stained specimens of gonococci revealed that pili with a diameter of approximately 85 A and a length up to 4 µ were present on the surfaces of all type 1 and type 2 gonococci examined, and were not seen on any type 3 or 4 gonococci. The consistent presence of pili on type 1 and type 2 gonococci which are virulent colony forms and the lack of pili on avirulent colony types 3 and 4 suggests a relationship between the gonococcal pili and pathogenetic potential of the organisms.


Plant Disease ◽  
1999 ◽  
Vol 83 (5) ◽  
pp. 486-486 ◽  
Author(s):  
V. A. Yuki ◽  
J. A. M. Rezende ◽  
E. W. Kitajima ◽  
P. A. V. Barroso ◽  
H. Kuniyuki ◽  
...  

Cayaponia tibiricae Cogn. (CT) is a wild Cucurbitaceae species found in secondary forests in the State of São Paulo, Brazil. The species has indefinite growth and bears oblong dark green fruits, 15 to 20 mm long (1,2). CT plants showing yellow mosaic symptoms were found in Atibaia County. Extracts from symptomatic plants were rub inoculated to zucchini squash (Cucurbita pepo L.) and Chenopodium amaranticolor Coste & Reyn. Zucchini squash plants developed severe yellow mosaic with intense leaf malformation, while C. amaranticolor showed necrotic local lesions. Extracts from naturally infected CT, zucchini squash, and C. amaranticolor were tested by plate trapped antigen-enzyme-linked immunosorbent assay (PTA-ELISA) with antisera against papaya ringspot virus type W (PRSV-W), zucchini yellow mosaic virus (ZYMV), zucchini lethal chlorosis virus (ZLCV), watermelon mosaic virus 2 (WMV-2), and cucumber mosaic virus (CMV). All samples were positive in PTA-ELISA only with ZYMV antiserum. Also, in Western blot (immunoblot) assay, ZYMV antiserum labeled a protein of approximately 36 kDa. Electron microscopic examination of ultrathin sections from infected CT tissue revealed the presence of pinwheel inclusions typical of potyvirus (type 1) infection in the cytoplasm of the cell. CT seedlings were susceptible to mechanical inoculation with the ZYMV isolated from this species. This is the first report of CT as a natural host for ZYMV in Brazil. References: (1) A. Cogniaux. Flora Brasiliensis 6:1, 1878. (2) M. Pio Corrêa. 1926. Diccionário das plantas úteis do Brasil e das exóticas cultivadas. Vol 1. Ministério da Agricultura, Rio de Janeiro, Brazil.


Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1155-1155 ◽  
Author(s):  
J. A. M. Rezende

Stuffing cucumber (Cyclanthera pedata var. edulis Schrad.) is native to the Americas, where it often occurs as an escape. The species is monoecious, with small flowers and large and deeply palmately lobed leaves. Fruits are puffy, partially hollow, and measure 5 × 15 cm long. The plant has soft spines, a tapered neck, and black seeds. The species has long been cultivated in Asia, where fruits are eaten raw as a substitute for cucumber or cooked (1). One plant showing intense mosaic, without leaf malformation, was found near a squash crop (Cucurbita moschata) in Anhembi County, State of São Paulo. Electron microscopic examination of a negatively stained sap preparation from leaves of this plant showed that it contained numerous flexuous rod-shaped particles, approximately 700 × 760 nm long, similar to those of potyviruses. Extracts from symptomatic leaves were rub-inoculated to zucchini squash (Cucurbita pepo), Carica papaya, Chenopodium amaranticolor, C. quinoa, Gomphrena globosa, and Phaseolus vulgaris cv. Black Turtle 2. Only zucchini squash was infected and developed severe mosaic with intense leaf malformation. Extracts from field infected stuffing cucumber and experimentally inoculated zucchini squash were tested by plate-trapped antigen enzyme linked immunosorbent assay (PTA-ELISA) with antisera against the following potyviruses: Papaya ringspot virus-type W (PRSV-W), Zucchini yellow mosaic virus (ZYMV), and Watermelon mosaic virus-2 (WMV-2). Samples were also tested with antisera against a tospovirus (Zucchini lethal chlorosis virus) and a cucumovirus (Cucumber mosaic virus). Both samples were positive in PTA-ELISA only with PRSV-W antiserum. This is the first report of C. pedata var. edulis as a natural host for PRSV-W in Brazil. References: (1) R. W. Robinson and D. S. Decker-Walters. 1997. Cucurbits. CAB International, UK.


Author(s):  
P. Frayssinet ◽  
J. Hanker ◽  
D. Hardy ◽  
B. Giammara

Prostheses implanted in hard tissues cannot be processed for electron microscopic examination or microanalysis in the same way as those in other tissues. For these reasons, we have developed methods allowing light and electron microscopic studies as well as microanalysis of the interface between bone and a metal biomaterial coated by plasma-sprayed hydroxylapatite(HA) ceramic.An HA-coated titanium hip prosthesis (Corail, Landos, France), which had been implanted for two years, was removed after death (unrelated to the orthopaedic problem). After fixation it was dehydrated in solutions of increasing ethanol concentration prior to embedment in polymethylmethacrylate(PMMA). Transverse femur sections were obtained with a diamond saw and the sections then carefully ground to a thickness of 200 microns. Plastic-embedded sections were stained for calcium with a silver methenamine modification of the von Kossa method for calcium staining and coated by carbon. They have been examined by back-scatter SEM on an ISI-SS60 operated at 25 KV. EDAX has been done on cellular inclusions and extracellular bone matrix.


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