Effects of the bitter additives naringin and sucrose octa-acetate on sweet persistence and sweet quality of neohesperidin dihydrochalcone

The maximal perceived sweet intensity (Ip_max) and the sweetpersistence constant (T) of neohesperidin dihydrochalcone (NHD),were significantly reduced in a mixture containing naringin(NAR), a bitter flavone analog of NHD Sucrose octa-acetate (SOA),another bitter stimulus, reduced the Ip_max of NHD in mixtures,but no appreciable decrease in T values was found. Linear regressionanalyses performed on the IP_max data of either NHD + NAR orNHD + SOA (logIp_max versus log concentration) produced slopevalues lower than those of NHD alone. Moreover, taste similarityexperiments revealed that the mixture of NHD + NAR was locatedfurther than NHD from the sugar area in the multi-dimensionalscaling (MDS) map. It is concluded that the reduction in Tvaluesof NHD by NAR was apparently related to the reduced Ip_max levelsand that such a mixture produces a sweet quality inferior tothat of NHD.     

Relationship between suicide and myocardial infarction with regard to changing physical environmental conditions

In recent years, the possible association of changes in mortality from cardiovascular disease and myocardial infarction (MI) and deaths related to violence and the suicide rate has been repeatedly discussed. This study examined the relationship between cosmic physical changes (solar, geomagnetic and other space activity parameters) and changes in the total number of in-hospital and MI-related deaths and deaths from suicide to determine if a relationship exists between the distribution of total and MI-related deaths with suicide over time; some differences in the serotonergic mechanisms involved in the pathogenesis of MI and suicide were also taken into account. All suicides (n=2359) registered in the State of Israel from 1981 to 1989 (108 months) were analysed and compared with the total number of deaths (n=15601) and deaths from MI (n=1573) in a large university hospital over 180 months (1974–1989). The following were the main features of the Results. (1) Monthly suicide rate was correlated with space proton flux (r=0.42,P=0.0001) and with geomagnetic activity (r=–0.22,P=0.03). (2) Total hospital and MI-related deaths were correlated with solar activity parameters (r=0.35,P<0.001) and radiowave propagation (r=0.52-0.44,P<0.001), an with proton flux (r=–0.3 to –0.26,P<0.01). (3) Monthly suicide distribution over 108 months was correlated with MI (r=–0.33,P=0.0005) and total hospital mortality (r=–0.22,P=0.024). (4) Gender differences were prominent. We conclude that the monthly distributions of suicides and deaths from MI are adversely related to many environmental physical parameters and negatively correlated with each other.     

The comparative biologies of two hymenopterous parasites of the chaff scale,Parlatoria pergandii

Résumé La biologie des aphelinidesAphytis hispanicus (Mercet) etProspaltella inquirenda Silvestri, respectivement ecto et endoparasite deParlatoria pergandii Comstock, a été étudiée comparativement en laboratoire.A. hispanicus accomplit son cycle en 34 jours environ à 20 °C et en 16 jours à 28 °C; il produit en moyenne 23,8 descendants, tandis que pourP. inquirenda ces durées sont de 62 et 26 jours et le nombre moyen de descendants 20,6. Le comportement pendant l'oviposition et les interactions diverses entre l'h?te et le parasite ont été notés. Le nectar d'agrumes a prolongé la vie des deux parasites autant que le miel.A. hispanicus a généralement une vie plus prolongée queP. inquirenda. Le premier parasite a mieux survécu dans des conditions de forte humidité relative (61%, 80%), maisP. inquirenda s'est trouvé favorisé dans des conditions de faible humidité relative, ainsi qu'après une exposition à des températures extrêmes. En conclusion,A. hispanicus a un taux plus rapide de croissance, tandis queP. inquirenda est mieux adapté aux conditions naturelles.

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This research has been finaneed in part by Grant No. FG-Is-227 made by the United States Department of Agriculture under P.L. 480.     

Processing of snake venom -amino acid oxidase during intracellular transport

The isoelectrofocusing patterns of -amino acid oxidase (LAO) from venom gland homogenates and of the secreted venom of Vipera palaestinae have been compared. The LAO isozyme profile of actively synthesizing gland spans over a wider range of pIs (4.8–6.0) and includes more variants as compared with the profile of the secreted venom. A basic shift of the isoelectrofocusing pattern of LAO obtained by treatment of the gland homogenate or the venom with neuraminidase indicates that sialic acid residues are responsible for the changes in the electronegativity of the isozymes. Analyses of subcellular fractions show that the microsomal fraction of the venom gland homogenate exhibits the highest multiplicity of molecular forms of LAO, whereas the fraction including the secretory granules has an isozyme profile similar to the venom. Double labelling experiments show that the newly synthesized LAO include isozymes which span over a wide range of pIs, whereas later on labelling of the more acidic isozymes is prominent. The results obtained may suggest that the sialic acid residues which are attached to LAO during its transport serve as “markers” for secretion.     

Effect of capsid confinement on the chromatin organization of the SV40 minichromosome

Using small-angle X-ray scattering, we determined the three-dimensional packing architecture of the minichromosome confined within the SV40 virus. In solution, the minichromosome, composed of closed circular dsDNA complexed in nucleosomes, was shown to be structurally similar to cellular chromatin. In contrast, we find a unique organization of the nanometrically encapsidated chromatin, whereby minichromosomal density is somewhat higher at the center of the capsid and decreases towards the walls. This organization is in excellent agreement with a coarse-grained computer model, accounting for tethered nucleosomal interactions under viral capsid confinement. With analogy to confined liquid crystals, but contrary to the solenoid structure of cellular chromatin, our simulations indicate that the nucleosomes within the capsid lack orientational order. Nucleosomes in the layer adjacent to the capsid wall, however, align with the boundary, thereby inducing a ‘molten droplet’ state of the chromatin. These findings indicate that nucleosomal interactions suffice to predict the genome organization in polyomavirus capsids and underscore the adaptable nature of the eukaryotic chromatin architecture to nanoscale confinement.