Susceptibility of cyprinid cultured cells to cyprinid herpesvirus 3.

Cyprinid herpesvirus 3 is a highly contagious and lethal virus that affects ornamental koi and common carp worldwide. However, it is not yet known whether other cyprinids are infected and/or harbor the virus. Here, we report that cultured cells derived from common carp, koi, silver carp and goldfish allow CyHV-3 propagation, while cyprinid cells derived from fathead minnow and non-cyprinid cells derived from the channel catfish ovary are resistant to CyHV-3 infection. Interestingly, the epithelioma papulosum Cyprini cells derived from Cyprinus carpio are restrictive to the virus. These results indicate that CyHV-3 is not restricted to common carp and koi, but other cyprinids are also vulnerable to the virus.

Detection of phytoplasma by polymerase chain reaction of insect feeding medium and its use in determining vectoring ability.

A polymerase chain reaction (PCR)-based method was developed for the detection of phytoplasma in insect feeding medium (sucrose). A correlation was established between the transmissibility of Flavescence dorée phytoplasma in the experimental leafhopper vector Euscelidius variegatus and its detection by PCR in the insect feeding medium. However, phytoplasma were detected in the insects' bodies 3 weeks before they began to transmit. Hence, PCR assays of the sucrose medium reflected phytoplasma vectoring ability probably by detecting it in the insect saliva, whereas detection of phytoplasma in the insect's body did not identify it as a vector. The assay was applied to two field-collected leafhoppers suspected of being phytoplasma vectors in Israel (Orosius albicinctus and Anaceratagallia laevis). The presence of phytoplasma in the body of specimens of the latter species was assayed by PCR in 1999. Phytoplasmas were detected in insects' bodies throughout the year, with no specific seasonal pattern. In the saliva, however, no phytoplasma could be detected in the autumn. This seasonal pattern supported the validity of the feeding-medium tests and their correlation to the insect's ability to transmit phytoplasma. Transmission assays indicated, to our knowledge for the first time, that O. albicinctus and A. laevis are vectors of phytoplasma in Israel. A simple PCR-based assay is thus provided, circumventing the need for tedious biological assays and enabling epidemiological studies of phytoplasma transmissibility on a large scale.

Relationship between neonatal excitability and respiratory habituation.

The Brazelton Neonatal Behavioral Assessment Scale was administered and analyzed in the cases of 25 full-term infants in order to assess the relationship between a behavioral measure of excitability and respiratory habituation. Sound and light stimuli were sequentially delivered, and prestimulus and poststimulus respiratory amplitude mean and standard deviation were analyzed. The stimulus with the least interperiod difference was considered as habituation. The correlation between arousal behavioral items and respiratory habituation ranged between 0.16 and 0.44. The two significant correlations were between peak of excitement and respiratory habituation to light (0.44) and between rapidity of buildup and respiratory habituation to sound (0.38). These results may indicate an interrelation in neonates between temperamental excitability attributes and respiratory regulation.

Rotation of sickle cells in homogeneous magnetic fields.

Deoxygenated sickle cells (HbS) have been shown to orient in homogeneous magnetic fields because of magnetic anisotropy of the hemes. The time of rotation is proportional to 1/H2 and is in agreement with theory. Structural information concerning the orientation of HbS molecules in the fibers is obtained from these experiments and is shown to agree substantially with existing models.

Theory of fluorescence polarization in magnetically oriented photosynthetic systems.

Many cells and cell fragments are known to assume specific alignments with respect to an applied magnetic field. One indicator of this alignment is a difference between the intensities of fluorescence observed in polarizations parallel and perpendicular to the magnetic filed. We calculate these two intensities using a model that assumes axially symmetric membranes and that covers a wide variety of shapes from flat disk to right cylinder. The fluorescence is assumed to originate at chromophores randomly exicted but nonrandomly oriented in the membranes. The membrane alignment is assumed to be due to the net torque on a nonrandom distribution of diamagnetically anisotropic molecules. The predicted results are consistent with most magnetoorientation data from green cells, but we are able to show that Chlorella data are not consistent with the hypothesis that the membranes have, and maintain, a cuplike configuration.