Abstract. The spindle pole body (SPB) is the equivalent of the centrosome in fission yeast. In vivo it nucleates microtubules (MTs) during mitosis, but, unlike animal centrosomes, does not act as a microtubule organizing center (MTOC) during interphase. We have studied the MT-nucleating activity of SPBs in vitro and have found that SPBs in permeabilized cells retain in vivo characteristics. SPBs in cells permeabilized during mitosis can nucleate MTs, and are recognized by two antibodies: anti-3,-tubulin and MPM-2 which recognizes phosphoepitopes. SPBs in cells permeabilized during interphase cannot nucleate MTs and are only recognized by anti-~-tubulin. Interphase SPBs which cannot nucleate can be converted to a nucleation competent state by incubation in cytostatic factor (CSF)-arrested Xenopus egg extracts. After incubation, they are recognized by MPM-2, and can nucleate MTs. The conversion does not occur in Xenopus interphase extract, but occurs in Xenopus interphase extract driven into mitosis by preincubation with exogenous cyclin B. The conversion is ATP dependent and inhibited by protein kinase inhibitors and alkaline phosphatase. Purified, active, cdc2 kinase/cyclin B complex in itself is not effective for activation of MT nucleation, although some interphase SPBs are now stained with MPM-2. These results suggest that the ability of SPBs in vitro to nucleate MTs after exposure to CSF-arrested extracts is activated through a downstream pathway which is regulated by cdc2 kinase.

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The effects of Tomato spotted wilt virus (TSWV) on yield and quality of tomato fruits were studied from May through November of 2004 at the Experimental Field of the Agricultural Faculty of Ondokuz Mayis University, in Samsun province, Turkey. TSWV caused 42.1% and 95.5% reduction in yield and marketable value of tomato, respectively. TSWV infection in tomato crop caused significant (P<0.05) reductions in weight, total number, width and length of the fruits in infected plants. Reductions in yieldcontributing parameters were 26.61% in weight,

To detect cucurbit viruses and determine their incidence, surveys were conducted in 45 fields in 18 villages in Samsun province, Turkey from July to October in 1999 and 2000. Watermelon mosaic virus (WMV), Zucchini yellow mosaic virus (ZYMV), and Cucumber mosaic virus (CMV) were detected in cucurbits after analyzing 165 samples by enzyme-linked immunosorbent assay. WMV, ZYMV, and CMV were detected in 53.9, 38.8, and 20.6% of samples tested, respectively. ZYMV and WMV infections were detected in all cucurbit species, but CMV was not detected in any samples of watermelon and pumpkin.

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Amasya is the greatest onion producing area in Turkey. Onion fields from Amasya region were surveyed for virus diseases in 2009-2011 and tested for the presence of the most important onion viruses such as Onion yellow dwarf virus (OYDV), Iris yellow spot virus (IYSV), Leek yellow stripe virus (LYSV), Shallot latent virus (SLV) and Garlic common latent virus (GCLV). The presence of virus diseases and their identification was ascertained through symptom observation in the fields, sap transmission to hosts, and DAS-ELISA. Based on the ELSA results, 57 out of 332 samples (17.16 %) were infected with viruses. The results showed that the highest infection was caused by OYDV (12.33 %) followed by LYSV (3.60 %). Only 1.19 % of the samples were infected with SLV, but none of the samples were found to be infected for GCLV and IYSV.

as moderately susceptible and 3 were susceptible to the CMV-BA isolate. These plants exhibited various symptoms and accumulated high levels of virus titer. However, the results showed that 17 lines had high resistance, 12 were found to be resistant and 10 were found to be moderately resistant to the CMV. The lines that showed high levels of resistance to the virus in this study could be used as sources of CMV resistance in cabbage breeding programs.