Scanning electron microscope study of Sendai virus fusion between HeLa cells and chick erythrocytes.

Chick erythrocytes were fused with HeLa cells by Sendai virus and preparations examined by scanning electron microscopy at different times after fusion. Heterokaryons were usually formed by fusion of erythrocyte ghosts with HeLa cells. Occasionally whole erythrocytes were engulfed but there was no evidence that free nuclei fused. Initial inter-cell attachments were usually, and possibly always, made at the site of an attached virus particle. This study helps to correlate topographical findings with previous two-dimensional studies with the transmission electron microscope and may also provide a model system for the fusion of parasitised erythrocytes with eukaryotic cells.     

Induction of chicken interferon by avian infectious bronchitis virus.

The ability of nine strains of avian infectious bronchitis virus (IBV) to induce chicken interferon has been investigated using Semliki Forest virus for the tests. The Beaudette, H120 and Connecticut 46 strains induced interferon in the allantoic fluids of embryonated hens' eggs, the highest titre (1 : 30) being associated with Beaudette; but these as well as the Massachusetts M-41 and H52 strains failed to yield interferon in primary monolayer cultures of chick kidney cells as did all nine strains in organ cultures of chick embryo trachea. None of six strains of IBV investigated was susceptible to the inhibitory effects of chicken interferon.     

Fish oil-induced yellow fat disease in rats. II. Enzyme histochemistry of adipose tissue

Adipose tissue in various stages of fish oil-induced yellow fat disease in the rat had the same acid phosphatase and 5-nucleotidase activity pattern as similar stages of the disorder in mink and pig. A weak acid phosphatase and 5-nucleotidase activity was seen in interstitial lipofuscin-laden macrophages in "stage M" yellow fat disease without fat cell degeneration. Activity of these macrophagic enzymes increased when there was fat cell degeneration ("stage S" and "stage E" yellow fat disease). This different phosphatase activity in the same cell type may result from phagocytosis of substrates with variable digestibility. Macrophages directly surrounding affected fat cells in steatitis areas ("stage S" and "stage E") had strong acid phosphatase and 5-nucleotidase activity. As in the pig, increased 5-nucleotidase activity was found in affected fat cells, which probably indicates plasma membrane damage. Increased nonspecific esterase activity occurred around affected fat cells. Only a small part of this esterase activity originated from inflammatory cells. This indicates that an increase of esterase activity in degenerating adipose tissue may be an endogeneous process in this tissue.     

S-methylcysteine sulphoxide,the brassica anaemia factor (a valuable dietary factor for man?)

Ruminant animals fed mainly or exclusively on brassica crops may develop a severe Heinz body anaemia. Clinical signs of the disease include haemoglobinuria, jaundice, increase in pulse rate and fall in milk production; there may also be growth retardation. Nitrate and thiocyanates were excluded as primary haemolytic factors in kale which contains up to 2% in DM of S-methylcysteine sulphoxide (SMCO). In test goats, daily intakes of SMCO in the range 15 to 19 g/100 kg liveweight, whether given as kale or the pure synthetic compound, elicited comparable haemolytic responses. SMCO was thus implicated as the major primary toxin in brassica poisoning. Rumen organisms converted SMCO into dimethyl disulphide which mimicked the haemolytic action of kale and SMCO in goats and is thus considered to be the secondary haemolysin. The practical consequence of this disulphide mechanism is that, because there is no simple way of counteracting the systemic action of dimethyl disulphide, prophylactic measures are restricted to limiting the intake of SMCO or to inhibiting disulphide production. Manipulation of rumen flora by dietary means to exclude organisms with SMCO-lyase is seen as a possible way of minimising the problem which in the long term however calls for developing brassica varieties with low SMCO content. The SMCO content of leafy brassicas increases as the plants mature; within a single plant highest SMCO levels are found in young leaves and growing shoots. SMCO is a heritable character and its selection will probably not lead to marked changes in protein or carbohydrate contents. In steers acute haemolytic response with growth inhibition was obtained with daily SMCO intakes, given as cabbage, of 18 to 35 g/100 kg liveweight. At the lower daily intake of 10–15 g the response was sub-acute, but the low grade anaemia produced would probably be incompatible with maximum productivity. Daily intakes below 10 g/100 kg generally lead to mild disturbances only in blood picture; and it is speculated that, on balance, at this level the effects of SMCO may even be beneficial to the animal. The possible prophylactic action of the S-alkylcysteine sulphoxides in coronary heart disease in man is briefly discussed.Resume Les ruminants nourris principalement ou exclusivement de crucifères peuvent contracter une grave anémie à corpuscules endoglobulaires. Les signes cliniques de la maladie comprennent l'hémoglobinurie, la jaunisse, l'élévation du pouls et la baisse de la production de lait et éventuellement aussi un retard de la croissance. Le nitrate et les thiocyanates ont été exclus comme facteurs hémolytiques primaires du chou à feuilles, qui contient jus qu'à 2% en matières sèches du sulfoxyde de s-méthylcystéine (SMCO). Chez les chèvres utilisées comme sujets d'expériences, des doses quotidiennes de SMCO de l'ordre de 15 à 19 g par 100 kg de poids corporel, absorbée sous la forme de chou ou sous celle de composé synthétique pur ont donné des réactions hémolytiques comparables. On a donc conclu que le SMCO était la principale toxine primaire responsable de l'empoisonnement brassicaire. Les organismes du rumen ont transformé le SMCO en disulphide de diméthyle qui a reproduit l'action hémolytique du chou et du SMCO chez les chèvres, et qui est donc considéré comme l'hémolysine secondaire. Étant donné qu'il n'y a pas de moyens simples de contrecarrer l'action systémique du disulphide de diméthyle, les seules mesures prophylactiques sont la limitation de l'absorption de SMCO ou l'inhibition de la production de disulphide. L'action sur la flore du rumen par des moyens diététiques, à fin d'exclure les organismes à SMCO-lyase, semble un moyen possible d'atténuer le problème. Mais à long terme, il faudra développer des variétés de crucifères à faible teneur en SMCO. La teneur en SMCO des crucifères feuillus augmente au fur et à mesure de la maturation. Sur une même plante, les teneurs les plus élevées se rencontrent dans les jeunes feuilles et dans les pousses en croissance. Le SMCO est un caractère héréditaire et une sélection operée en fonction de lui n'entraînera probablement pas de modifications importantes des teneurs en protéines ou en hydrates de carbone. Une réaction hémolytique aiguë avec inhibition de la croissance a été provoquée chez les bouvillons au moyen de doses quotidiennes de SMCO de 18 à 35 g par 100 kg de poids corporel, administrées sous forme de chou. A la dose quotidienne plus faible de 10 à 15 g la réaction a été sub-aiguë mais l'anémie faible qui en résulte serait probablement incompatible avec une productivité optimale. Les doses quotidiennes inférieures à 10 g par 100 kg ne provoquent généralement que de légères perturbations de la formule hématologique. On estime qu'à ce taux les effets du SMCO peuvent même, dans l'ensemble, être bénéfiques à l'animal. L'action prophylactique possible des sulfoxydes de s-alkylcysteine dans les cas de maladies coronaires chez l'homme est examinée brièvement.

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Kurzfassung Bei Wiederkäuern, die hauptsächlich oder ausschliesslich Brassica-Futter erhalten, kann es zu einer schweren Innenkörperanämie kommen. Klinische Anzeichen hierfür sind u.a. Bluthernen, Gelbsucht, erhöhte Pulsfrequenz und Rückgang der Milcherzeugung, ausserdem unter Umständen ein verlangsamtes Wachstum. Nitrat und Thiocyanat wurden als primäre hämolytische Faktoren im Brassica oleracea, das bis zu 2% S-Methylcystein sulfoxid (SMCO) in der Trockenmasse enthält, ausgeschlossen. Bei Test-Ziegen führten Tagesdosen von SMCO im Bereich von 15 bis 19 g/100 kg Lebendgewicht in Form von Brassica oleracea oder dem reinen, synthetisierten Bestandteil zu vergleichbaren hämolytischen Reaktionen. SMCO war also als wichtigstes Primärtoxin bei Brassica-Vergiftungen beteiligt. Die Pansenorganismen setzten SMCO in Dimethyldisulfid um, das die selbe hämolytische Wirkung wie Brassica oleracea und SMCO bei Ziegen hatte und so als sekundäres Hämolysin gilt. Die praktische Folge dieses Disulfidmechanismus ist, dass vorbeugende Massnahmen auf die Begrenzung der SMCO-Aufnahme oder die Verhinderung der Disulfidproduktion beschränkt sind, da es keine einfache Möglichkeit gibt, der systematischen Aktion von Dimethyldisulfid entgegenzuwirken. Eine Manipulation der Pansenflora durch entsprechende Ernährung zur Ausschaltung von Organismen mit SMCO-Lyase gilt als Möglichkeit zur Minimalisierung des Problems, das langfristig gesehen jedoch die Entwicklung von Brassica-Arten mit geringem SMCO-Gehalt erforderlich macht. Der SMCO-Gehalt von Blattkohl nimmt mit zunehmender Reife der Pflanze zu; innerhalb einer Pflanze findet sich der grösste SMCO-Gehalt in jungen Blättern und wachsenden Trieben. SMCO ist ein erbliches Merkmal, und seine Selektion wird vermutlich nicht zu grösseren Aenderungen im Protein-oder Kohlehydratgehalt führen. Bei Ochsen wurde eine akute hämolytische Reaktion mit Wachstumsverzögerung bei täglichem SMCO-Dosen von 18 bis 35 g/100 kg Lebendgewicht in Form von Kohl erzielt. Bei der geringeren Tagesdosis von 10–15 g war die Reaktion subakut, die entwickelte geringfügige Anämie wäre jedoch vermutlich mit maximaler Produktivität unvereinbar. Tagesdosen unter 10 g/100 kg führen im allgemeinen nur im Blutbild zu geringen Störungen; man vermutet, dass alles in allem SMCO bei dieser Dosierung sogar eine positive Auswirkung auf das Tier haben kann. Die mögliche prophylaktische Wirkung der S-Alkylcystein sulfoxide bei Erkrankungen der Herzkranzgefässe beim Menschen wird kurz erörtert.

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Riassunto I ruminanti la cui dieta è in gran parte o esclusivamente rappresentata da cavoli (Brassica spp.) possono essere colpiti da una grave forma di anemia (Heinz body anaemia). I sintomi clinici della malattia comprendono emoglobinuria, ittero, aumento della frequenza cardiaca e caduta della produzione lattea. A volte si può anche avere ritardo della crescita. I nitrati e i tiocianati sono stati esclusi come fattori emolitici primari nei cavoli che contengono fino al 2% in DM di S-metilcisteina sulfossido (SMCO). In experimenti condotti sulle capre, la somministrazione giornaliera di SMCO in dosi di 15–19 g/100 kg di peso vivo, sia sotto forma di vegetale che di prodotto sintetico puro, ha provocato fenomeni emolitici relativamente simili. L'SMCO è stato pertanto indicato come la principale tossina che ha un ruolo primario nell'intossicazione da cavoli. La flora ruminale converte infatti l'SMCO in dimetil bisolfuro, il quale svolge un'azione emolitica simile a quella osservata nelle capre dopo l'assunzione di cavoli e di SMCO; il dimetil bisolfuro, pertanto, e ritenuto costituire l'emolisina secondaria. Le conseguenze pratiche di tale produzione di dimetil bisolfuro è che, non esistendo un metodo semplice per contrastare l'azione sistemica del dimetil bisolfuro, le misure profilattiche non possono essere volte ad altro se non a limitare l'assunzione di SMCO o ad inibire la produzione di bisolfuro. Gli interventi sulla flora del rumine mediante una dieta capace di eliminare i microrganismi provvisti di SMCO-liasi vengono considerati come un possibile mezzo per minimizzare il problema, il quale, tuttavia, se visto a lungo termine, richiede la creazione di varietà di cavoli a basso contenuto di SMCO. Il contenuto di SMCO delle foglie dei cavoli aumenta col maturare della pianta: nella pianta singola i livelli piu alti di SMCO si riscontrano nelle foglie giovani e nei germogli. La presenza di questa sostanza costituisce un carattere ereditario ed un intervento selettivo in tal senso non dovrebbe condurre a significative alterazioni del contenuto in proteine e carboidrati della pianta. Nei vitelloni e stato possibile indurre una risposta emolitica di tipo acuto somministrando giornalmente, sotto forma di cavoli, 18–35 g di SMCO per 100 kg di peso vivo. Un' assunzione giornaliera minore, pari a 10–15 g, ha dato luogo ad una forma emolitica subacuta, ma e tuttavia da ritenere che la lieve anemia cosi indotta non sia compatibile con una produttività ottimale. Livelli giornalieri al di sotto dei 10 g/100 kg hanno causato soltanto lievi alterazioni a carico del quadro ematico, ed è stata avanzata l'ipotesi che, tutto sommato, gli effetti dell'SMCO possano, a questi livelli, essere addirittura di beneficio all'animale. Viene discussa brevemente la possibile azione preventiva degli S-alchilcisteina sulfossidi sulle malattie cardio-coronariche dell'uomo.

     

Arbovirus isolations from mosquitoes in South Slovakia.

In the years 1973 and 1975 mosquitoes and some other Diptera (Tabanidae, Simuliidae, Hippoboscidae) were tested for virus. 13,924 mosquitoes, 75 horseflies and 60 blackflies were processed in 1973. Five strains of Tahyna virus were isolated from mosquito species Aedes vexans. 3,378 mosquitoes and 12 sheep keds were tested for virus in 1975. Twelve strains of Calovo virus were isolated from Anopheles maculipennis and one strain of Tahyna virus was obtained from Aedes vexans mosquitoes.     

Nerine latent virus: some properties and serological detectability in Nerine bowdenii

Nerine latent virus (NeLV), first found inNerine bowdenii, may occur also in the otherNerine species investigated so far:N. sarniensis, N. flexuosa Alba, andN. Mansellii. Chenopodium amaranticolor, C. quinoa, andGomphrena globosa sometimes reacted with local lesions after mechanical inoculation with NeLV.Nicotiana clevelandii andHippeastrum were symptomless hosts. In this respect NeLV resembled the incompletely describedHippeastrum latent virus (HLV).Serologically NeLV was closely related to HLV and to carnation latent virus (CaLV), but differed from the latter in host plant reaction. A more distant relationship was observed with some other carlaviruses, wheareas NeLV also reacted with an antiserum to potato virus X.Depending on the lot, NeLV could be detected rather reliably with the micro-precipitin test inN. bowdenii Van Roon, but less well in 63. Better results were obtained with the microplate method of enzyme-linked immunosorbent assay (ELISA).The average particle length was 664 nm, the sedimentation coefficient 155 S and the buoyant density 1.298 g/cm³.NeLV can be considered as a member of the carlavirus group. On basis of priority HLV may be considered as NeLV.     

Effect of tricyclazole on growth and secondary metabolism in Pyricularia oryzae

Tricyclazole [5-methyl-1,2,4-triazolo (3,4-b)-benzothiazole] controls rice blast disease caused by Pyricularia oryzae at concentrations (5–10 μg/ml) which do not inhibit growth of the pathogen in vitro. However, concentrations of 1 μg/ml or less inhibit melanin formation in the fungus. Production of pyriculol by the pathogen is usually enhanced by 10 μg/ml of tricyclazole, whereas production of 3,4-dihydro-4,8-dihydroxy-1(2H)-naphthalenone is strongly inhibited or markedly reduced and delayed. Evidence suggests that tricyclazole blocks aspects of polyketide metabolism in P. oryzae which may have a role in pathogenicity.     

Inhibition of chitin synthesis by two 1-(2,6-disubstituted benzoyl)-3-phenylurea insecticides. II

The knowledge of the biochemical mode of action of 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea (diflubenzuron) is presented, explaining the insecticidal effect. Like its structural analog, 1-(2,6-dichlorobenzyl)-3-(3,4-dichlorophenyl)urea (Du 19111), it inhibits chitin synthesis in the cuticle of larvae. Virtually complete inhibition was demonstrable 15 min after the application of diflubenzuron. Neither diflubenzuron nor Du 19111 has any effect upon chitinase activity either in vivo or in vitro. The insecticidal effect upon the cuticle, therefore, must be explained as an inhibition of chitin synthesis and not as an activation of chitin degradation. In contrast to the action of Du 19111, no accumulation of N-acetylglucosamine occurs upon treatment of larvae with diflubenzuron. Similarities and differences in the mode of action of both compounds are discussed, together with other effects reported in the literature.     

A leaf spot disease of Nymphaea alba in the Netherlands

A destructive leaf spot disease was found onNymphaea alba in the lakes near Kortenhoef, Netherlands. After comparison of fresh material and herbarium specimens the causal agent is namedColletotrichum nymphaeae (Pass.) van der Aa, comb. nov. Synonymy, morphology and cultural characters of the fungus are described and discussed. Some remarks on the relationship with several host plants are given and the provisional conclusion is that the species is a widespread parasite, but that the destructive attack in the Kortenhoef region is probably caused by a combination of various factors.