Sensitivity and adaptation in R7, an ultraviolet photoreceptor,in theDrosophila retina

Summary Receptor deficient mutants and chromatic adaptation were used to isolate the contribution of R7 to the electroretinogram (ERG) ofDrosophila. R7 was found to be a single-peaked ultraviolet (UV) receptor (Fig. 1). Photoconversion of the UV absorbing rhodopsin (R) to its stable 470–495 nm metarhodopsin (M) was shown to elicit a long-lived negative (depolarizing) afterpotential (Fig. 3) while inactivating R7. Photoreconversion ofM toR reactivates R7 (Fig. 2) and repolarizes the ERG (Fig. 3). The intensities of light needed to elicit afterpotentials by photointerconverting R7 photopigment were found to be about 2 log units greater than for R1-6 photopigment (Fig. 4). Vitamin A deprivation decreases R7 (as well as R8) sensitivity by about 2 log units (through decreased photopigment levels) without changing spectral sensitivity shape (Fig. 5). Vitamin A deprivation further eliminates the light-induced inactivation of R7 allowing experiments designed to characterize the in vivo spectral absorption of R7M. R7M was found to have UV and 495 nm maxima (Fig. 6). No polarization sensitivity was detected in the R7 ERG component. The adaptational properties of R7 are similar to the properties previously established for R1-6 but different from the properties of R8.Supported by NSF grants BMS-74-12817 and BNS 76-11921. I thank M. Chapin, R. Greenberg, K. Hu, A. Ivanyshyn, D. Lakin, G. Pransky, D. Sawyer, J. Walker and W. Zitzmann for technical assistance.     

Many variable region genes are utilized in the antibody response of BALB/c mice to the influenza virus A/PR/8/34 hemagglutinin

We have examined how many different H chain variable (VH) and kappa-chain variable (Vk) germ-line genes are used in the antibody response to the influenza virus A/PR/8/34 hemagglutinin (PR8 HA), and have assessed how the expression of individual VH and/or Vk genes contributes to the generation of specificity for the HA. A panel of 51 hybridoma antibodies that recognize two antigenic regions on the HA were compared for the sequence of their Ig H and L chain V regions. The hybridomas were obtained from 28 individual BALB/c mice that had been immunized with PR8 under a variety of primary and secondary response immunization protocols. The degree and pattern of sequence similarity suggests that 29 different VH genes drawn from seven different VH gene families, and 25 different Vk genes drawn from 12 different Vk gene families were used in this panel. Based on current estimates of the total numbers of VH and Vk genes in the mouse, this suggests that between 2.5 and 10% of the entire VH and Vk germ-line repertoires were used by these hybridomas. Despite this extensive diversity, some V genes were repetitively identified among these hybridomas, and were most often expressed in the context of specific VH/Vk combinations. Because antibodies that used identical VH/Vk combinations also usually displayed similar reactivity patterns with a panel of mutant viruses, this indicates that VH/Vk pairing can be important in establishing the specificity of antibodies for the HA.     

Perception of the auxin signal at the plasma membrane of tobacco mesophyll protoplasts

Auxin-induced variations of transmembrane potential difference have been shown to be a useful tool for analyzing hormone sensitivity in tobacco protoplasts. Using this technique, we demonstrated that protoplasts derived from wild-type, an auxin-resistant mutant and Agrobacterium-rhizogenes transformed plants differed widely in the sensitivity of their electrical response to naphthalene acetic acid. We have used different antibodies, raised to auxin binding proteins (ABP) from maize coleoptiles, or to the axr1 gene product (ABP1), to test whether changes in auxin sensitivity can be correlated with the presence of tobacco proteins immunologically related to this ABP. Titrations indicated that 0.4 nM anti-ABP IgG inhibited 50% of the auxin-specific response of wild-type protoplasts, whereas 0.04 nM or 4 nM anti-ABP IgG were necessary to inhibit the response of mutant and transformed protoplasts, respectively, to the same extent. On wild-type protoplasts, blocking part of the immunoreactive sites with anti-ABP antibodies resulted in a decrease in auxin sensitivity of the electrical response (0.4 nM anti-ABP IgG inducing a 10–fold decrease), whereas addition of maize ABP increased this auxin sensitivity (1 pM ABP1 raised the sensitivity more than 1000–fold). The results obtained suggest that the auxin sensitivity detected by our assay system correlates with the amount of tobacco proteins immunologically related to the axr¹ gene product from maize. A hypothesis accounting for the presence of these proteins at the external surface of tobacco protoplasts and for the effects of hetero-logous maize ABP on auxin sensitivity is proposed.     

Intercellular adhesion molecule-1 (ICAM-1)-dependent and ICAM-1-independent adhesive interactions between polymorphonuclear leukocytes and human airway epithelial cells infected with parainfluenza virus type 2.

Acute respiratory virus infections are often associated with an early influx of neutrophils (PMN) into the airways. Maximal cytoxic injury by PMN depends on tight cell-cell adhesion. Infection of some cell types by respiratory and other viruses has been shown to increase PMN adhesion to these cells by undefined mechanisms. We studied adhesion by human PMN to monolayers of primary (1 degree) human tracheal epithelial cells (TEC) or an immortalized cell line derived from human TEC, 9HTEo-, that had been infected with parainfluenza virus type 2 (PiV2). PMN adhesion to uninfected 1 degree TEC was very low (< 5%), but PMN adhesion to PiV2-infected 1 degree TEC was greatly increased (89 +/- 7%). PMN adhesion to 9HTEo- cells was 47 +/- 6%, but increased, 87 +/- 8%, for PiV2-infected 9HTEo- cells. Surface intercellular adhesion molecule-1 (ICAM-1) expression on 1 degree TEC, as determined by immunofluorescence flow cytometry, was relatively low (23 fluorescence units) but doubled by 24 h after PiV2 infection and tripled by 48 h. The 9HTEo- cells constitutively expressed higher levels of surface ICAM-1 (120 units) which did not increase with PiV2 infection. Treatment of non-PiV2-infected 9HTEo- cells with mAb (R6.5) to ICAM-1 reduced PMN adhesion to these cells from 47 +/- 8 to 23 +/- 5%. Identical mAb treatment of either 1 degree TEC or 9HTEo- cells infected with PiV2 had no significant effect on PMN adhesion. Treatment of the PMN with mAb against CD11a, CD11b, or CD18 markedly reduced PMN adhesion to PiV2-infected 1 degree TEC and 9HTEo- cells. We conclude that PiV2 infection of human TEC causes a marked increase in their adhesive interactions with PMN by inducing increased surface expression of both ICAM-1 and one or more, as yet uncharacterized, non-ICAM-1 adhesion molecules that function as counter-receptors for CD11/CD18 on PMN. These mechanisms of adhesion may play a role in epithelial damage during acute respiratory virus infections.     

Quantitation of model digestive mixtures by 13C NMR.

13C nuclear magnetic resonance (NMR) spectra were obtained at 50.3 and 100.5 MHz for methanolic and aqueous mixtures of sodium taurocholate, 1-monocapryloyl-rac-glycerol, and caprylic acid. Distortionless Enhancement by Polarization Transfer (DEPT) was used to improve spectral sensitivity and resolution, and to generate calibration curves for quantitative determinations of each lipid in methanol. Alternatively, the heights for nonoverlapping peaks in a 13C NMR spectrum acquired with inverse-gated decoupling provide reliable quantitative estimates for each component of the mixture, particularly when the data are obtained in methanol. These experiments also demonstrate the feasibility of detailed NMR structural investigations in model systems for glyceride digestion.     

Characterization of murine cell lines from Diethylstilbestrol-Induced uterine endometrial Adenocarcinomas

Neonatal treatment with estrogens is associated with development of uterine adenocarcinomas in CD-1 mice. Treatment with the synthetic estrogen diethylstilbestrol (DES) on Days 1 to 5 after birth results in 90% incidence of these hormonedependent lesions in 18-mo.-old mice. Three cell lines were established from these DES-associated tumors. Each of these cell lines exhibited morphologic and ultrastructural characteristics of transformed epithelial cells, including an increased nuclear:ytoplasmic ratio, enlarged and irregular nuclei with multiple nucleoli and areas of chromatin condensation, positive staining for cytokeratin, desmosomes, and microvilli. After subcutaneous injection into nude mice, all three cell lines formed solid tumors within 4 wk. Although the primary uterine tumors and tumor transplants in nude mice had been shown to be estrogen-dependent and estrogen-receptor positive, neither the monolayer growth nor the tumorigenicity of any of the three cell lines in this study was enhanced by or dependent on estrogen. Estrogen receptor levels were low in early and intermediate passage cells. Allele-specific oligonucleotide hybridization analysis of PCR-amplified cell line DNA revealed no point mutations in the 12th, 13th, or 61st codons of the K-ras or H-ras protooncogenes. Southern analysis revealed no changes in genomic organization of the putative tumor suppressor gene DCC, but demonstrated a three-to four-fold amplification of the c-myc gene in one cell line. Expression of c-myc RNA was concomitantly increased in the same cell line. These three transformed cell lines represent the end point in the process of hormone-associated tumorigenesis and as such should prove useful in investigating the molecular changes and the mechanisms involved in hormonal carcinogenesis.     

Schizophrenia, eye movements, and biocultural heterogeneity

Smooth-pursuit eye-tracking dysfunction is a putative genetic trait marker for schizophrenia. In this study 88 Japanese schizophrenics from Kyushu and Okinawa were examined for the marker using precise high-resolution instrumentation: 76% of the schizophrenics from Kyushu and 89% of those from Okinawa had pursuit dysfunction. The presence of the culture-neutral smooth-pursuit marker for schizophrenia in Japan demonstrates that the etic concept "schizophrenia" is cross-culturally valid. Furthermore, the ubiquity of the marker in biologically and culturally diverse populations may indicate a limit on the extent of meaningful heterogeneity likely to be discovered within the condition.