Tumours of Begonia and some other ornamentals,induced by Corynebacterium fascians

In 1975 many tumours were observed in plants ofBegonia Schwabenland grown in Aalsmeer. Submersion of the roots ofNicotiana megalosiphon seedlings in a homogenate of tumorous tissue, induced tumours after two weeks. Short periods of submergence yielded results similar to those obtained after longer periods. Tumour homogenates lost their infectivity after ten min at 50°C. Aphids transmitted the infectious agent.Treatment with propylene oxide did not inhibit infectivity completely. Filtration through a 450 nm filter removed the infectious agent.Tobacco tumor virus or a viroid could not be isolated. Cultures ofCorynebacterium fascians, isolated from tumours ofN. megalosiphon were highly infectious and induced tumours in healthyN. megalosiphon andBegonia. Tumorous tissue homogenates ofPelargonium zonale, Dahlia sp.,Gladiolus sp., andLilium sp. also caused tumours inN. megalosiphon, from whichC. fascians was isolated. It was not possible to produce tumours inN. megalosiphon with homogenates from roses with symptoms of bud proliferation.Samenvatting In 1975 werden vele tumoren waargenomen inBegonia Schwabenland op Aalsmeerse bedrijven (Fig. 1). De infectiositeit van tumorweefsel kon goed en snel worden vastgesteld door de wortels van zaailingen vanNicotiana megalosiphon in een homogenaat van tumorweefsel te dompelen. Tumoren ontstonden na twee weken, de eindbeoordeling geschiedde na een maand (Fig. 2). Ook verschillende andereNicotiana spp.,Melilotus officinalis (Fig. 3) enPisum odoratum (Fig. 4) werden aangetast.Bij de infectiositeitstoets gaven zeer korte dompeltijden even goede resultaten als langere (Tabel 1). Infectieus sap verloor zijn infectievermogen na 10 min verhitting bij 50°C. Bladluizen brachten de smetstof over. Propyleenoxide verminderde de infectiositeit wel, doch onderdrukte deze niet totaal. Bij filtratie door een 450 nm filter bleef het infectieuse agens op het filter achter. Het tumor-inducerende agens was ook aanwezig in die delen van planten met tumoren welke gezond leken en het ging voor een gering deel over met zaad (Tabel 2).Uit tumoren konden wij geen tabakstumorvirus of een viroïde isoleren. Culturen vanCorynebacterium fascians, geïsoleerd uit tumoren vanN. megalosiphon bleken zeer infectieus en veroorzaakten tumoren inN. megalosiphon enBegonia. Homogenaten van tumorweefsel vanPelargonium zonale, dahlia (Fig. 5), gladiool (Fig. 6) enLilium Mid Century Hybrid Enchantment (Fig. 7) veroorzaakten ook tumoren opN. megalosiphon, waaruitC. fascians werd geïsoleerd. Met sap van kroeskopzieke rozen konden wijN. megalosiphon niet besmetten.     

苹毒蛾核多角体病毒观察初报

苹毒蛾病毒是典型的核型多角体病毒结构,对苹毒蛾幼虫有较强的致死能力,对于开展苹毒蛾的生物防治有一定意义;在病毒分类上根据形态鉴别,可能属于杆状病毒属(Baculovirus)亚组(A)的一个种。     

Crystalline ribulose 1,5-bisphosphate carboxylase-oxygenase from spinach

Spinach fraction I protein (ribulose 1,5-bisphosphate carboxylase-oxy genase, E.C. 4.1.1.39) was crystallized on both an analytical and a preparative scale by vapor diffusion with polyethylene glycol (molecular weight, 6000) used as the precipitant. The identity of the crystalline material with fraction I protein was shown by gel electrophoresis in the presence of sodium dodecyl sulfate and immunological properties. The carboxylase and oxygenase activities copurify during crystallization, and the crystalline enzyme lacks copper and iron.     

Nitrogen-fixing anabaena: physiological adaptations instrumental in maintaining surface blooms

Both laboratory and in situ studies indicate that the nitrogen-fixing blue-green nuisance algae Anabaena spp. have developed adaptive means of dominating surface lake waters. During the dramatic diurnal shifts in surface light intensity and oxygen saturation accompanying blooms, Anabaena can overcome oxygen toxicity by sequential optimization of carbon dioxide and nitrogen fixation and by pigment alteration. These mechanisms allow optimal utilization of the radiant energy while minimizing competition for photoreductant between two main energy-demanding processes.     

Superheavy elements: a crossroads

The failure to synthesize superheavy elements by using complete fusion reactions is most likely understandable in terms of the low survival probabilities of the superheavy precursors formed in these reactions or (in some cases) the failure to achieve complete fusion. Further attempts to synthesize these elements by using complete fusion or deep inelastic transfer reactions, or both, are discussed in light of these results.     

Photosynthetic Marine Mollusks: In vivo 14C Incorporation into Metabolites of the Sacoglossan Placobranchus ocellatus

In seawater enriched with carbon-14-labeled sodium hydrogen carbonate the sacoglossan Placobranchus ocellatus when exposed to light incorporates carbon-14 at a rate 50-fold of that for animals kept in the dark. 9,10-Deoxytridachione, a secondary metabolite of the mollusk, undergoes a photorearrangement to photodeoxytridachione in vivo.