A Drosophila melanogaster hobo-white+ vector mediates low frequency gene transfer in D. virilis with full interspecific white+ complementation

Transformation of a Drosophila virilis white mutant host strain was attempted using a hobo vector containing the D. melanogaster mini-white⁺ cassette (H[w⁺, hawN]) and an unmodified or heat shock regulated hobo transposase helper. Two transformant lines were recovered with the unmodified helper (HFL1), one containing only the white⁺ marked vector, and a sibling line containing the vector as well as an HFL1 helper integration. An approximate total transformation frequency of 1% is deduced. A high frequency of wing and eye morphology mutants were also observed, suggesting that hobo may have mobilized a related element in D. virilis. The data reaffirms a relatively low transformation vector activity for the hobo transposon in D. virilis; however, nearly full interspecific expression of the white⁺ marker supports its possible function in other species as well.     

人精浆对不同丝裂原诱导淋转反应的影响

本文通过人精浆对PHA、ConA和PWM三种丝裂原诱导淋巴细胞转化反应的影响,间接了解HSP对T辅助、T抑制和B淋巴细胞功能的影响,结果发现不同浓度的精浆对三种丝裂原诱导的淋转反应均有明显抑制作用(P<0.05),且三种浓度HSP的抑制作用在无显著性差异(P>0.05);中浓度的精浆对PHA、ConA和PWM诱导转反应的抑制率分别为69.7、51.7和48.3％,说明精浆对机体的T辅助、T抑制性和B淋巴细胞功能均有明显的抑制作用。此外,还对精浆的免疫抑制作用机理和意义进行了讨论。     

Astrocytoma and Schwann cells in coculture

Glial fibrillary acidic protein (GFAP) is the principal intermediate filament protein found in mature astrocytes. Although the exact function of GFAP is poorly understood, it is presumed to stabilize the astrocyte’s cytoskeleton and help in maintaining cell shape. Previous studies from our laboratory have shown that when astrocytes were cocultured with primary Schwann cells (pSCs), astrocytes became hypertrophied and fibrous with intensely positive GFAP staining and segregated Schwann cells (SCs) into pockets. In order to understand the functional role of GFAP in this already established astrocyte-SC coculture model, we generated GFAP-negative cell lines from a GFAP-positive astrocytoma cell line and cocultured both the cell lines with pSCs. Our studies demonstrate that the GFAP-positive cell line put out processes toward the SCs, whereas the GFAP-negative cells did not form processes and the majority of the cells remained round. The most significant and interesting finding of this study, however, is the formation of elaborate processes by SCs when grown in coculture with the astrocytoma cells, unlike SCs cultured alone, which showed their typical bipolar spindle-shaped morphology. The extent of processes did not seem to be dependent on GFAP, since SCs cultured with both the cell lines formed similar processes. This coculture model may be useful in elucidating the factor(s) responsible for the formation of processes by SCs and can be further help in our understanding of the mechanism of morphological transformation of SCs.     

Presence of natural killer-cell clones with variable proliferative capacity in chronic active Epstein-Barr virus infection

Chronic active Epstein-Barr virus infection (CAEBV) is a syndrome that takes diverse clinical courses and is often associated with lymphoproliferative disorders of T/natural killer (NK)-cell lineage. We describe a patient with CAEBV associated with persistent pharyngeal ulcer, and with subsequent nasal T/NK-cell lymphoma in her neck lymph nodes and nasopharynx. Immunophenotyping of lymphoid cells showed that the lineage of Epstein-Barr virus (EBV)-positive cells in the patient was of NK-cell origin. By means of high-dose recombinant interleukin-2, we established an EBV-positive cell line of NK-cell lineage from her peripheral blood. Southern blot analysis for the number of terminal repeat sequences of EBV detected three NK-cell clones in the patient's lymph node. One of these clones was identical to the established cell line but was not observed in the pharyngeal ulcer, while the other two clones were present in the pharyngeal ulcer. These results suggest that the patient had expansion of the three NK-cell clones, one of which had proliferative capacity in vitro and was involved in the formation of the lymphoma. Moreover, the results suggest that the proliferative capacity of EBV-positive cells can be variable even in a single patient, and this variability may explain the clinical diversity in CAEBV.     

Cloning of the nitrate reductase gene of Stagonospora (Septoria) nodorum and its use as a selectable marker for targeted transformation

The nitrate reductase gene (NIA1) of the phytopathogenic fungus Stagonospora (Septoria) nodorum has been cloned from a cosmid library by homologous hybridisation with a PCR-generated probe. A 6.7-kb fragment carrying the NIA1 gene was subcloned and partially characterised by restriction mapping. Sequencing of the gene indicated a high degree of homology, both at the nucleotide and amino-acid levels, with nitrate reductase genes of other filamentous fungi. Furthermore, consensus regulatory signals thought to be involved in the control of nitrogen metabolism are present in the 5′ flanking region. The cloned NIA1 gene has been used to develop a gene-transfer system based on nitrate assimilation. Stable nia1 mutants of S. nodorum defective in nitrate reductase were isolated by virtue of their resistance to chlorate. These were transformed back to nitrate utilisation with the wild-type S. nodorum NIA1 gene. Southern analyses revealed that transformation occurred as a result of the integration of transforming DNA into the fungal genome; in all cases examined, integration was targeted to the homologous sequence. Received: 30 March / 9 June 1998     

Structure, Metabolism, and Functions of Peripheral Blood Lymphocytes during Long-Term Persistence of Epstein-Barr Virus

Study of surface architectonics, blast transformation potential, and cytochemical activity of peripheral blood lymphocytes from children infected with Epstein-Barr virus revealed imbalance between structural, metabolic, and functional state of lymphocytes. This imbalance persists in delayed period after infection and determines long-term viral persistence in the macroorganism.     

Deletion of the Cochliobolus heterostrophus mating-type (MAT ) locus promotes the function of MAT transgenes

Cochhobolus heterostrophus has alternate genes (MAT-1 andMAT-2) at its mating-type locus. Transformants of aMAT-1 or aMAT-2 strain carrying a transgene of opposite mating type can self and are dual maters; the transgene, however, promotes development of pseudothecia only, not ascospores. To determine if the resident gene interferes with the function of the transgene, transformation vectors were designed to delete different amounts (2.5 kb, 5.7 kb, and 6.3 kb) of DNA at theMAT locus. Deletions occurred at a higher frequency (about 90% of transformants) with linearized plasmid than with circular plasmid (about 15% of transformants), and all three vectors were equally efficient at gene replacement. BothMAT-1 andMAT-2 could be deleted with the same set of vectors. Re-transformation of deletion strains (regardless of deletion size) with a wild-type copy ofMAT restored full mating ability, indicating that the residentMAT gene interferes with function of theMAT transgene. Moreover, sexual development was normal whether theMAT transgene integrated at the homologous or at an ectopic site.     

Spatial object representation and its use in planning eye movements

The eye movements we make to look at objects require that the spatial information contained in the objects image on the retina be used to generate a motor command. This process is known as sensorimotor transformation and has been generally addressed using simple point targets. Here, we investigate the sensorimotor transformation involved in planning double saccade sequences directed at one or two objects. Using both visually guided saccades toward stationary objects and objects subjected to intrasaccadic displacements, and memory-guided saccades, we found that the coordinate transformations required to program the second saccade were different for saccades aimed at a new target object and saccades that scanned the same object. While saccades aimed at a new object were updated on the basis of the actual eye position, those that scanned the same object were performed with a fixed amplitude, irrespective of the actual eye position. Our findings demonstrate that different abstract representations of space are used in sensory-to-motor transformations, depending on what action is planned on the objects.     

Nkx2.5‐negative myocardium of the posterior heart field and its correlation with podoplanin expression in cells from the developing cardiac pacemaking and conduction system

Recent advances in the study of cardiac development have shown the relevance of addition of myocardium to the primary myocardial heart tube. In wild‐type mouse embryos (E9.5–15.5), we have studied the myocardium at the venous pole of the heart using immunohistochemistry and 3D reconstructions of expression patterns of MLC‐2a, Nkx2.5, and podoplanin, a novel coelomic and myocardial marker. Podoplanin‐positive coelomic epithelium was continuous with adjacent podoplanin‐ and MLC‐2a‐positive myocardium that formed a conspicuous band along the left cardinal vein extending through the base of the atrial septum to the posterior myocardium of the atrioventricular canal, the atrioventricular nodal region, and the His‐Purkinje system. Later on, podoplanin expression was also found in the myocardium surrounding the pulmonary vein. On the right side, podoplanin‐positive cells were seen along the right cardinal vein, which during development persisted in the sinoatrial node and part of the venous valves. In the MLC‐2a‐ and podoplanin‐positive myocardium, Nkx2.5 expression was absent in the sinoatrial node and the wall of the cardinal veins. There was a mosaic positivity in the wall of the common pulmonary vein and the atrioventricular conduction system as opposed to the overall Nkx2.5 expression seen in the chamber myocardium. We conclude that we have found podoplanin as a marker that links a novel Nkx2.5‐negative sinus venosus myocardial area, which we refer to as the posterior heart field, with the cardiac conduction system. Anat Rec, 290:115–122, 2007. © 2006 Wiley‐Liss, Inc.