Drosophila rhino encodes a female-specific chromo-domain protein that affects chromosome structure and egg polarity.

Here we describe our analyses of Rhino, a novel member of the Heterochromatin Protein 1(HP1) subfamily of chromo box proteins. rhino (rhi) is expressed only in females and chiefly in the germline, thus providing a new tool to dissect the role of chromo-domain proteins in development. Mutations in rhi disrupt eggshell and embryonic patterning and arrest nurse cell nuclei during a stage-specific reorganization of their polyploid chromosomes, a mitotic-like state called the "five-blob" stage. These visible alterations in chromosome structure do not affect polarity by altering transcription of key patterning genes. Expression levels of gurken (grk), oskar (osk), bicoid (bcd), and decapentaplegic (dpp) transcripts are normal, with a slight delay in the appearance of bcd and dpp mRNAs. Mislocalization of grk and osk transcripts, however, suggests a defect in the microtubule reorganization that occurs during the middle stages of oogenesis and determines axial polarity. This defect likely results from aberrant Grk/Egfr signaling at earlier stages, since rhi mutations delay synthesis of Grk protein in germaria and early egg chambers. In addition, Grk protein accumulates in large, actin-caged vesicles near the endoplasmic reticulum of stages 6-10 egg chambers. We propose two hypotheses to explain these results. First, Rhi may play dual roles in oogenesis, independently regulating chromosome compaction in nurse cells at the end of the unique endoreplication cycle 5 and repressing transcription of genes that inhibit Grk synthesis. Thus, loss-of-function mutations arrest nurse cell chromosome reorganization at the five-blob stage and delay production or processing of Grk protein, leading to axial patterning defects. Second, Rhi may regulate chromosome compaction in both nurse cells and oocyte. Loss-of-function mutations block nurse cell nuclear transitions at the five-blob stage and activate checkpoint controls in the oocyte that arrest Grk synthesis and/or inhibit cytoskeletal functions. These functions may involve direct binding of Rhi to chromosomes or may involve indirect effects on pathways controlling these processes.

A common immunoregulatory locus controls susceptibility to actively induced experimental allergic encephalomyelitis and experimental allergic orchitis in BALB/c mice.

Previous studies have shown that differential susceptibility to actively induced experimental allergic encephalomyelitis (EAE) and experimental allergic orchitis (EAO) exists among various BALB/c substrains. Of eight substrains studied for EAE and 13 for EAO, BALB/cJ mice are phenotypically the most resistant to disease induction. Resistance to both diseases is controlled by single recessive mutations unlinked to any of the known alleles distinguishing BALB/cJ mice. In this study, segregation analysis employing a second generation backcross population shows that resistance to both EAE and EAO is due to a mutation in a common immunoregulatory gene. The role of immunoregulatory cells in controlling EAE resistance was examined using adoptive transfer protocols. BALB/cJ mice immunized with spinal cord homogenate plus adjuvants generate immunoregulatory spleen cells (SpC) that, when transferred to naive BALB/cByJ recipients, reduce the incidence and severity of EAE. Treatment of such cells with either cytotoxic monoclonal anti-Thy1.2 or anti-CD4 plus C' before transfer abrogates the ability of BALB/cJ SpC to inhibit disease. In contrast, neither SpC from adjuvant-immunized BALB/cJ nor spinal cord homogenate- plus adjuvant-primed BALB/cByJ donors influences the incidence or severity of disease observed in recipients. In addition, the role of environment in influencing susceptibility to EAE and EAO in BALB/c mice is documented. Taken together, these results support the existence of a common disease susceptibility locus in the pathways leading to two autoantigenically distinct CD4+ T cell-mediated, organ-specific, autoimmune diseases.

A novel negative imaging technique for accurate localization of stainable proteins on complex two-dimensional autoradiograms.

This paper describes a fast, simple, and accurate method for localization of protein antigens in complex two-dimensional (2-D) autoradiograms where the precise position and identity of the protein is required. The method involves the creation of negative images on an autoradiogram through arrangement of image-intensifying screens. By placing a chromogenically stained 2-D gel or blot between the intensifying screen and the film, photons emitted from the intensifying screen are obstructed by the stained spots, thus creating a negative image on the film. The technique can be used in autoradiograms of proteins labeled with either 32P or (125)I radioisotopes. The technique permits analysis of radiolabeled, gold-stained and immunoreacted proteins on a single film and offers versatility by combining analysis of total protein patterns with specific identification of radiolabeled and/or immunoreacted protein spots. The technique is especially useful when selecting a subset of specifically radiolabeled proteins from the total protein pattern in 2-D gels or membranes for microsequencing.