Effect of decapitation, phosfon D and cycocel on the flowering of Impatiens balsamina exposed to varying numbers of short days

Impatiens balsamina L., a qualitative short day plant, requiresmore short days for the development of floral buds into flowersthan for their initiation. Phosfon D and cycocel reduce thenumber of short days required for flowering, increase the numberof floral buds and flowers and delay their reversion to vegetativegrowth when transferred to noninductive conditions. The effectof decapitation of the main shoot subsequent to the emergenceof floral buds resembles that of retardants indicating thatthe effect of the latter in flower promotion in this plant maybe by virtue of their effect on cessation of apical dominanceas a consequence of which reserve food materials may be channeledto axillary floral buds enabling them to develop into flowers. (Received January 9, 1969; )     

Initiation of DNA Synthesis in HeLa Cell-free System

THE molecular mechanism for initiating DNA replication can be studied using a subcellular system. Rao and Johnson¹ found that HeLa cells in the pre-DNA-synthetic (G-1) period of the cell cycle initiate DNA synthesis after fusion with cells that are in the DNA synthetic (S) period. A previous subcellular system of DNA replication from HeLa cells^2–4 consisted of intact nuclei, supplemented with the four deoxy-nucleoside triphosphates, salt, ATP and a cytosol factor. The nuclei in this system appeared to be permeable to proteins and DNA synthesis was very similar to that within intact cells. We report here the initiation of DNA synthesis in nuclei isolated from HeLa cells. Our results suggest that, with the synchronization method used, a small percentage of dormant G-1 nuclei can be stimulated by S-phase cytoplasm; this would be the case if the cells were receptive to stimulation for only 30–60 min during the cell cycle. illustration

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Role of fine needle aspiration cytology in diagnosis of pleomorphic adenomas

Role of fine needle aspiration cytology in diagnosis of pleomorphic adenomas This retrospective study was carried out to review the cases diagnosed as pleomorphic adenoma in major or minor salivary glands and determine the difficulties encountered on typing this tumour on fine needle aspiration cytology (FNAC). Over a 19‐year period (1982–2000) 488 pleomorphic adenomas were diagnosed on FNAC from different sites (parotid – 372 cases, submandibular – 95 cases; oral cavity – 21 cases). Histology was available in 232 cases. Twenty‐nine cases where a histological diagnosis of pleomorphic adenoma was made but the cytological diagnosis was variable were also reviewed. In 216 of the 232 cases a good cytohistological correlation was available. On review only 4 of the 16 cases initially diagnosed as pleomorphic adenoma on FNAC where the histology revealed a different tumour were categorized as pleomorphic adenoma, while 3 each were classified as adenoid cystic carcinoma and benign tumour ?type, and 2 each were diagnosed to be muco‐epidermoid carcinoma, monomorphic adenoma and acinic cell carcinoma. On review of the FNAC smears from 29 cases where a histological diagnosis of pleomorphic adenoma was available while the cytological diagnosis was variable, only 11 (38%) were categorized as pleomorphic adenoma. In the majority of the remaining cases the cytological diagnosis did not alter markedly, 7 of 10 cases where the tumour could not be typed on cytology initially could not be typed even on review. In conclusion, FNAC is an ideal, fairly accurate preoperative procedure for the diagnosis of pleomorphic adenomas. Certain diagnostic problems occur in differentiating pleomorphic adenomas from adenoid cystic carcinoma, monomorphic adenoma and mucoepidermoid carcinoma. Carcinoma ex‐pleomorphic adenoma is difficult to identify on FNAC and in our series all 4 such cases on histology were considered benign on cytology.     

Tarsal contact chemoreceptor response to glucosinolates and cardenolides mediating oviposition in Pieris rape

Abstract. Water-soluble extracts of a host crucifer (Brassica oleracea L.) and non-host crucifer (Erysimum cheiranthoides L.) and isolated pure cardenolides and glucosinolates were tested on Pieris rapae L. (Lepidoptera: Pieridae) butterflies in oviposition assays and by electrophysiological recordings from the contact-chemoreceptor sensilla of the prothoracic tarsi. Ten different glucosinolates stimulated oviposition to varying degree when put on non-host plant leaves. The most active compounds were glucobrassiein and gluconasturtiin (methylindole and phenylethyl aglycone), whereas glucocapparin, sinalbin. glucotropaeolin, sinigrin and glucoalyssinin had intermediate activity. Glucocheirolin, glucoerucin and glucoiberin (sulphur-containing aglycone) were significantly less active. Of eight cardenolides applied to host-plant leaves (100 μg each), four glycosides deterred oviposition strongly (erysimoside, erychroside, cymarin and K-strophanthin-β). Erycordin, helveticoside, digitoxin and strophanthidin had little or no deterrent activity. Sensilla located laterally on the prothoracic tarsi of female butterflies contained one receptor cell sensitive to sucrose. None of the tested extracts or pure compounds stimulated any cell in these sensilla. In contrast, the cells in the medial sensilla showed little or no sensitivity to sucrose. One cell was found to be sensitive to cardenolide glycosides. The threshold for one of the most active compounds, erychroside, was about 0.1 μg/ml (1.5 times 10^-7 M). Two receptor cells, characterized by spikes of differing amplitude, were sensitive to glucosinolates. One of these, with larger amplitude spikes, seemed to be the same as the cell sensitive to cardenolides. The threshold for the most active glucosinolates, glucobrassicin and gluconasturtiin was estimated to be below 0.1 mg/ml (2 times 10^-4 M). The neural activity of both classes of compounds, cardenolides and glucosinolates, was significantly correlated with their behavioural activity as deterrents or stimulants.