The virus-vector relationship of the tomato leafcurl virus (TLCV) and its vector,Bemisia tabaci gennadius (Hemiptera: aleyrodidae)

Basic studies carried out in India showed that the incubation period of TLCV in plants varied from 8 days in August to 90 days in winter. The acquisition threshold for the whitefly,Bemisia tabaci Gen., was 31 min; it resulted in 3% transmission. An acquisition access of 24 h for a female whitefly on a TLCV source resulted in 30% transmission. A minimum feeding period of 32 min was required by a viruliferous whitefly to cause infection on tomato test plants; this gave 4% transmission. With inoculation access of 24 h on tomato test plants, the transmission rose to 24%. Starving the vector for 1 h pre-acquisition or 1 h pre-inoculation resulted in higher levels of transmission of TLCV: 36 and 40%, respectively, compared with 20% for non-starved whiteflies. Extending the fasting period beyond 1 h resulted in a reduced transmission level. The whiteflies could acquire the virus from the cotyledonary leaves of an infected tomato plant, with a resultant 28% transmission; but infection did not occur when the whiteflies had an inoculation access to such leaves. Higher transmission rates were obtained when the younger leaves on tomato plants were used for acquisition and inoculation. Transmission was 8 and 38% when five whiteflies per plant were allowed 24 h of acquisition access to 11- and 2-month-old virus sources, respectively. After an acquisition access of 24 h to a TLCV source, male and female whiteflies retained their infectivity for 5 and 53 days, respectively. Nymphs can acquire and transmit the virus. When ten whiteflies of each sex were given 24 h of acquisition and of inoculation access, the subsequent transmission rate of males and females was 56 and 86%, respectively. This virus is not transovarially transmitted. Whitefly colonies raised on brinjal were more efficient (70 and 84% transmission in two experiments) than those raised on chilli, cotton, cowpea, tobacco or tomato.     

A new pattern of morphofunctional relationship among cranial nerves: Evidence of anatomical and physiological connection between trigeminus and oculomotor nerves

It is shown that the cell bodies of the afferent fibres supplying the proprioceptivity to the extrinsic eye muscles are located within the semilunar ganglion. Furthermore, some Gasserian cells have central processes which enter the midbrain through the oculomotor nerve. Sensory ganglion cells, derived from the same strand of placodal cells forming the ophthalmic lobe, can be constantly detected within the oculomotor nerve of ox, monkey and man.

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Kurzfassung Unsere Forschungen haben ergeben, dass sich die Zellkörper der fibrae afferentes, die dem äusserlichen Augenmuskeln die propriozeptive Sensibilität geben, im Ganglion des Gasser befinden. Ausserdem haben einige Zellen des Gasserschenganglion zentrale Verzweigungen die durch den Nervus oculomotorius in den Hirnstamm führen. Sensitive Ganglionzellen, die von der gleichen Reihe plakodischer Zellen stammen, und den lobus oftalmicus Gasseri formen, sind regelmassig im nervus oculomotorius des Rindes, des Affen und des Menschen zu finden.

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Resume Nos recherches ont démontré que, chez le Mouton et le Porc, le ganglion de Gasser contient les corps cellulaires des fibres nerveuses desservant les fuseaux neuromusculaires des muscles extrinsèques de l'oeil. En outre, quelques cellules du ganglion de Gasser ont leurs prolongements centraux qui se portent au tronc cérébral en suivant à rebours les radicules du nerf oculomoteur. En fin, on a trouvé constamment des cellules ganglionnaires sensitives dans l'oculomoteur du Boeuf, du Singe et de l'Homme; ces cellules proviennent du même cordon de cellules placodiales qui forme le lobe ophthalmique du ganglion semilunaire.

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Riassunto Le nostre ricerche hanno dimostrato che i corpi cellulari delle fibre nervose afferenti, che danno la sensibilità propriocettica al muscolo oculare estrinseco, si trovano nel ganglione di Gasser. Inoltre, alcune cellule del ganglione di Gasser hanno diramazioni centrali che portano al tronco cerebrale attraverso il nervo oculomotore. Infine, si sono costantemente incontrati nel nervo oculomotore del bovino, della scimmia e dell'uomo, cellule sensitive che provengono dallo stessotronco di cellule placodali che formano il lobo oftalmico.

     

The use of vitamin D metabolites and analogues for the prevention of milk fever in dairy cattle

During the past decade it has been discovered that vitamin D₃ (cholecalciferol) is converted into 25-hydroxycholecalciferol in the liver and that this compound in converted in the kidney into 1, 25-dihydroxycholecalciferol. These metabolites and particularly 1, 25-dihydroxycholecalciferol, rather than vitamin D itself, have powerful effects on calcium metabolism, stimulating the absorption of calcium from the gastrointestinal tract and the resorption of calcium from bone. A synthetic analogue of these metabolites, 1-hydroxycholecalciferol, is rapidly converted in the liver into 1, 25-dihycroxycholecalciferol. Thus the two metabolites and the synthetic analogue may be valuable for the prevention on treatment of milk fever.The three compounds, when administered in doses ranging from 0.5 to 32g/kg bodyweight increase the concentrations of calcium and phosphorus in the blood plasma of cattle more quickly than much larger doses of vitamin D₃. Their principal effect is to stimulate the absorption of calcium from the gastrointestinal tract. At the same time they decrease the plasma concentration of magnesium slightly. Trials of 25-hydroxycholecalciferol and 1-hydroxycholecalciferol in the prevention of milk fever have shown promising results.

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Kurzfassung Im vergangenen Jahrzehnt hat man festgestellt, dass das Vitamin D₃ (Cholecalciferol) in der Leber in 25-Hydroxycholecalciferol umgewandelt wird und die Nieren diese Verbindung wiederum in 1, 25-Dihydroxycholecalciferol umbilden. Mehr noch als Vitamin D selbst zeigen diese Metaboliten und hier insbesondere das 1, 25-Dihydroxychlecalciferol umfangreiche Auswirkungen auf den Kalziummetabolismus, indem sie die Kalziumabsorption aus dem Magen-Darmtrakt und die Kalziumresorption der Knochen anregen. Ein synthetischer Analogstoff zu diesen Metaboliten, das 1- Hydroxycholecalciferol, wird in der Leber rasch in 1, 25-Dihydroxycholecalciferol umgewandelt. Die beiden Metaboliten und der synthetische Analogwirkstoff könnten daher für die Milchfieberprophylaxe bzw-therapie von Nutzen sein.Werden die drei Verbindungen in Dosen von 0,5 bis 32g/kg Körpergewicht verabreicht, so erhöht sich die Kalzium-und Phosphorkonzentration im Blutplasma der Kühe schneller als bei bedeutend höheren Dosen von Vitamin D₃. Ihre Hauptwirkung liegt in der Anregung der Kalzium-absorption aus dem Magen-Darmtrakt. Gleichzeitig bauen sie jedoch auch in geringfügigem masse die Magnesiumkonzentration im Plasma ab. Versuche mit 25-Hydroxycholecalciferol und 1-Hydroxycholecalciferol haben bei der Milchfieberprophylaxe vielversprechende Ergebnisse gezeigt.

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Resume Au cours de la dernière décennie, on a découvert que la vitamine D₃ (cholécalciférol) se transformait en 25-hydroxycholécalciférol dans le foie et que ce composé se transformait en 1, 25-dihydroxy-cholécalciférol dans le rein. Ces métabolites, et en particulier le 1, 25-dihydroxycholécalciférol, ont, plus que la vitamine D elle-même, des effets puissants sur le métabolisme du calcium: ils stimulent l'absorption du calcium de l'appareil gastrointestinal et la résorption du calcium des os. Une substance homologue synthétique de cés metabolites, le 1-hydroxycholécalciférol, se transforme rapidement en 1, 25-dihydroxycholécalciférol dans le foie. Les deux métabolites et la substance homologue synthétique peuvent donc s'avérer précieux dans la prévention ou le traitement de la fièvre laiteuse.Administrés en doses allant de 0,5 à 32g/kg de poids corporel, ces trois composés augmentent les concentrations de calcium et de phosphore dans le plasma sanguin du bétail plus rapidement que des doses beaucoup plus fortes de vitamine D₃. Ils ont pour principal effet de stimuler l'absorption du calcium de l'appareil gastro-intestinal. Simultanément, ils réduisent légèrement la concentration de magnésium dans le plasma. Les essais d'utilisation du 25-hydroxycholécalciférol et du 1-hydroxycholécalciférol pour la prévention de la fièvre laiteuse ont donné des résultats prometteurs.

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Riassunto Nel corso dell'ultimo decennio si è scoperto che la vitamina D₃ (colecalciferolo) viene trasformata nel fegato in 25-idrossicolecalciferolo, il quale, a sua volta, si trasforma nel rene in 1, 25-diidrossicolecalciferolo. Detti metaboliti, ed in specie l'1, 25-diidrossicolecalciferolo., più che la stessa vitamina D, hanno potenti effetti sul metabolismo del calcio, poichè ne stimolano l'assorbimento da parte dell' apparato digerente e l'anabolizzazione da parte delle ossa. Un composto sintetico analogo di questi metobiliti, l'1, idrossicolecalciferolo, viene rapidamente trasformato nel fegato in 1, 25-diidrossicolecalciferolo. Perciò i due metaboliti e il composto sintetico analogo possono essere utili per la profilassi e la cura della febbre da latte.I tre composti, se somministrati in dosi da 0.5 a 32g/kg peso corporeo, aumentano la concentrazione del calcio e del fosforo nel plasma sanguigno del bestiame più rapidamente di dosi molto maggiori di vitamina D₃. Il loro effetto principale è quello di stimolare l'assorbimento del calcio da parte dell'apparato digerente. Contemporaneamente, essi riducono leggermente la concentrazione di magnesio nel plasma. Esperimenti con il 25-idrossicolecalciferolo nella profilassi della febbre da latte hanno dato risultati promettenti.

     

A light and scanning-electron microscopic study of infection of tomato plants by virulent and avirulent races of Cladosporium fulvum

Infection of tomato plants byCladosporium fulvum Cooke was studied using light and scanning-electron microscopy. Races 1.2.3 and 4 ofCladosporium fulvum were used, whereas tomato cultivars, carrying the Cf2 gene (susceptible to race 1.2.3 and immune to race 4) and the Cf4 gene (immune to race 1.2.3 and susceptible to race 4) served as differentials. No differences were observed in growth between compatible and incompatible combinations during germination, subsequent formation of runner hyphae and stomatal penetration. Runner hyphae did not show directional growth towards stomata. Penetration usually occurred on the third or fourth day after inoculation. In compatible combinations the fungus grew intercellularly, often in close contact with spongy mesophyll cells. Under optimal conditions it did not cause visible damage to plant cells during early stages of infection. Under suboptimal conditions in winter, the host cells often reacted with callose deposition, but growth of the fungus did not appear to be inhibited. Ten to twelve days after inoculation conidiophores emerged through the stomata and produced conidia. In incompatible combinations fungal growth was arrested one to two days after penetration and confined to stomata and surrounding cells. Very soon the host cells, in contact with the fungus, deposited extensive amounts of callose. Later these cells turned brown and collapsed. At the surface of the host cells, contacted by fungal hyphae, abundant extracellular material could be observed by scanning-electron microscopy. Removing the epidermis of leaves before inoculation delayed the resistant response. On stripped leaves the rate of fungal growth was equal for both interactions up to ten days after inoculation, but the incompatible combination lacked sporulation.     

Observation on the remarkable stability of transmissible mink encephalopathy virus.

Transmissible mink encephalopathy (TME) virus retained biological activity after prolonged storage in formalin (about three and a half years) and in paraffin tissue blocks used for histologic preparations (about six and a half years). Thus, TME tissues in formalin and in paraffin blocks should be handled as contaminated materials.     

Tiering in suspension-feeding communities on soft substrata throughout the phanerozoic

Tiering of benthic marine suspension-feeding communities on soft substrata has varied throughout the Phanerozoic. Epifaunal tiering was most developed during the middle and late Paleozoic and the Triassic to Jurassic, with large-scale reductions in tiering occurring during the Permian-Triassic extinctions and after the Jurassic. Infaunal tiering reached its highest level of organization after the Paleozoic.