Development of the jamming avoidance response and its morphological correlates in the gymnotiform electric fish,Eigenmannia

The electric fish, Eigenmannia, will smoothly shift the frequency of its electric organ discharge away from an interfering electric signal. This shift in frequency is called the jamming avoidance response (JAR). In this article, we analyze the behavioral development of the JAR and the anatomical development of structures critical for the performance of the JAR. The JAR first appears when juvenile Eigenmannia are approximately 1 month old, at a total length of 13–18 mm. We have found that the establishment of much of the sensory periphery and of central connections precedes the onset of the JAR. We describe three aspects of the behavioral development of the JAR: (a) the onset and development of the behavior is closely correlated with size, not age; (b) the magnitude (in Hz) of the JAR increases with size until the juveniles display values within the adult range (10–20 Hz) at a total length of 25–30 mm; and (3) the JAR does not require prior experience or exposure to electrical signals. Raised in total electrical isolation from the egg stage, animals tested at a total length of 25 mm performed a correct JAR when first exposed to the stimulus. We examine the development of anatomical areas important for the performance of the JAR: the peripheral electrosensory system (mechano- and electroreceptors and peripheral nerves); and central electrosensory pathways and nuclei [the electrosensory lateral line lobe (ELL), the lateral lemniscus, the torus semicircularis, and the pacemaker nucleus]. The first recognizable structures in the developing electrosensory system are the peripheral neurites of the anterior lateral line nerve. The afferent nerves are established by day 2, which is prior to the formation of receptors in the epidermis. Thus, the neurites wait for their targets. This sequence of events suggests that receptor formation may be induced by innervation of primordial cells within the epidermis. Mechanoreceptors are first formed between day 3 and 4, while electroreceptors are first formed on day 7. Electroreceptor multiplication is observed for the first time at an age of 25 days and correlates with the onset of the JAR. The somata of the anterior lateral line nerve ganglion project afferents out to peripheral electroreceptors and also send axons centrally into the ELL. The first electroreceptive axons invade the ELL by day 6, and presumably a rough somatotopic organization and segmentation within the ELL may arise as early as day 7. Axonal projections from the ELL to the torus develop after day 18. Within the torus semicircularis, giant cells are necessary for the performance of the JAR. Giant cell numbers increase exponentially during development and the onset of the JAR coincides with a minimum of at least 150 giant cells and the attainment of a total length of at least 15 mm and at least 150 giant cells. Pacemaker and relay cells comprise the adult Eigenmannia pacemaker nucleus. The growth and differentiation of these cell types also correlates with the onset of the JAR in developing animals. We describe a gradual improvement of sensory abilities, as opposed to an explosive onset of the mature JAR. We further suggest that this may be a rule common in most developing behavioral systems. © 1992 John Wiley & Sons, Inc.     

Formation of Hassall's corpuscles in vitro by the thymic epithelial cell line IT-26 R 21 of the rat

Summary In the monolayer of an established epithelial cell line from the rat thymus, IT-26R21, characteristic cell aggregates quite similar to Hassall's corpuscles were formed. These aggregates were examined by light and electron microscopy, and immunohistochemically. Their interpretation as Hassall's corpuscles is based on the following observations: (1) The aggregates are formed in the monolayer of cells that greatly resemble medullary epithelial cells of the thymus. (2) They consist of flattened epithelial cells in a concentric pattern with one or more degenerating cells in the center. (3) Loss of microvilli suggests that these cells are keratinizing. (4) The aggregates show strongly positive reactions in immunofluorescent staining with antikeratin and antiprekeratin.When Hassall's corpuscles increase in size, cellular proliferation is somewhat suppressed. Both in vivo and in vitro, they may be interpreted as an expression of a changing growth pattern in confined spaces and thus seem to have little immunological function.     

Predominance of gonadotropin α-subunit resulting from preferential loss of hCGβ production in an established cell line

Summary The BeWo line of trophoblastic cells, maintained in continuous culture since 1966, was employed to investigate the phenomenon of gonadotropin α-subunit predominance that exists in several cell lines. The secretion of complete human chorionic gonadotropin (hCG) relative to α-subunit was compared in several different BeWo sublines, all of which were derived from BeWo stock roller tube colonies. In all of the BeWo sublines, secretion of hCG originally exceeded secretion of α-subunit. With time in culture, however, there was a marked decline in production of hCG/hCGβ, but not in α-subunit. Thus it appears that the production of hCGβ by BeWo choriocarcinoma cells is more labile than the production of the α-subunit.     

Pokeweed mitogen inhibition of protein synthesis in cultured lymphoblastoid lines

Summary Pokeweed mitogen (PWM) and ricin are both lectins derived from plant seeds. They are glycoproteins and share the ability to agglutinate a variety of animal cells including erythrocytes. The effect of these two lectins on protein synthesis was studied in four longterm lymphoblastoid lines (8866 and GM1531, which are B cell lines; and CCRF/CEM and MOLT 4, which are T-cell lines). Ricin (50 μg/ml) completely inhibited protein synthesis by 2 hr in both B-cell and T-cell lines as measured by the uptake to [³H]leucine. The PWM appeared more specific and at a concentration of 500 μg/ml inhibited protein synthesis only in B-cell lines (8866 and GM 1531). This effect was maximal at 5 hr. To investigate the reason for the differential effect of PWM on T and B cells,¹²⁵I-labeled PWM was incubated with 8866, MOLT 4, and CCRF/CEM to see if a significant difference in binding to B cells and T cells could be demonstrated. It does not appear that the differential effect on T and B cells is due to a difference in the amount of PWM bound. On the other hand it is possible that the B cells may bind some toxic subcomponent of the PWM preparation that the T cells do not bind because of a difference in composition or arrangement of cell surface glycoproteins.     

Two relative efficiencies of polymorphic enzymes for characterizing cell lines,detecting contaminations,and monitoring transplants

Summary A new calculation of the relative efficiency of polymorphic enzyme markers, called the REB, was determined and compared with one of Fisher's determinations of the relative efficiency called REA here. The REA estimates the chance of failing, and 1-REA of succeeding, to show a phenotypic difference between two randomly selected persons or cultured cell lines (Case 1). In this study it was shown that the REA also estimates the chance of detecting a cell line mislabeling or similar mixup (Case 2) and a cell line cross-contamination leading to the complete replacement of an original line by contaminating line (Case 3). The new REB determines the probability of failing, and 1-REB of succeeding, to detect a contamination of an original line by another line leading to their coexistence, or at least a sufficiently long period of transitional coexistence before one overgrows the other. The REA and REB also apply to determining the efficiency of polymorphic markers in detecting donor and recipient cells in tissue transplants. This work was developed from the author's involvement in the human tumor cell-line characterization project at Sloan-Kettering Institute and he acknowledges this opportunity and the benefits of his association with Dr. J?rgen Fogh and colleagues in the Human Tumor Cell Laboratory.     

Characterization of WiDr: A human colon carcinoma cell line

Summary We describe the establishment and characterization of WiDr, a cell line derived from a human colon carcinoma. It produces carcinoembryonic antigen in culture, and has a doubling time of 15 hr with plating efficiency of 51%. The HLA antigenic profile and the allozyme genetic signature (composed of eight gene-enzyme systems) of WiDr cells are different from those of HeLa cells. Furthermore, WiDr cells possess three marker chromosomes, again distinct from the HeLa marker chromosomes. Finally, it is highly tumorigenic in four different xenogeneic animal models. Based on these studies, WiDr represents a useful model cell line for tumor cell biology investigations.     

Antimetabolic activities of 2-fluoro-L-histidine.

2-Fluoro-L-Histidine inhibits protein synthesis in various cell cultures, as measured by ³H-leucine incorporation. This histidine analog also inhibits the cytopathogenicity of a number of RNA and DNA viruses in primary and continuous cell cultures; it blocks the transformation of normal mouse (MO) cells by murine sarcoma virus, and partially suppresses the release of murine leukemia virus by a continuously infected mouse cell line (JLSV5). In human skin fibroblasts, it reduces the interferon-inducing capacity of poly(I)·poly(C). Inhibition of cell protein synthesis may be the common cause of the various effects. 4-Fluoro-L-histidine is essentially inert in all of the test systems examined.     

Sex and side differences and correlations between quantitative palmar characteristics in a sample Sardinian population

Differences between the sexes and between the sides and the correlations between four quantitative characteristics of palmar dermatoglyphics in a sample population of 809 individuals (418 males and 391 females) from the city of Cagliari, Sardinia, are tested. Males have a greater number of ridges than females, shown by a greater a-b ridge count and A-d ridge count, and a more transverse slope of the main lines, shown by a greater main line index and papillary number. The left palm shows a greater number of ridges than the right palm between the A line and the triradius d and between the triradii a and b, with a lower main line index and papillary number. The a-b ridge count has a negative correlation with the main line index and with the papillary number and a positive one with the A-d ridge count; these correlations are greater in the left palms, especially in the males.