Beitrag zur Flora von Bosnien und der Hercegovina

Ohne Zusammenfassung     

Management of the Wadden Sea

The Wadden Sea situated along the North Sea coasts of Denmark, the Federal Republic of Germany and The Netherlands represents one of the world's largest bar-built type of estuaries. The area is a typical sedimentation and mineralization basin, with a large influx of organic matter from the adjoining North Sea, consequently a delicate oxygen balance and a rich benthic macrofauna, poor in species, which serves as food for juveniles of some commercially important North Sea fishes and for large numbers of migrating and wintering waders and waterfowl. Past and present activities of the human society in the area include fisheries (mainly for shrimp and mussels, semi-culture), shipping, land reclamation, recreation, dredging for sand and shells, and waste discharge from industries and human communities. Until the present these activities, although sometimes conflicting, did not fundamentally affect the area and its biota (pollution excluded), but future claims, including the construction of large deep-sea harbours, drilling for natural gas and oil, large-scale land reclamation and increased industrialization etc., might gradually induce degradation. For instance, area reduction by continued land reclamation could lead to irreversible losses of specific biotopes (e. g. salt-marshes, mud-flats), which could affect the size of bird and fish populations in a much wider region. Increased pollution, which has already inflicted damage on bird and seal populations, could reduce the fauna and hence the value of the area as a natural sanctuary. In the event of a proposal for a new human activity in the area, the present standing practice in the countries concerned requires an evaluation of its safety and economic aspects and its environmental impact. However, the various plans are considered separately and there is a general need for integrated management of the area.     

MährischeThymus-Formen

Ohne Zusammenfassung     

Beitrag zur Flora der Beskiden und des Hochgesenkes

Ohne Zusammenfassung     

Regulation of acid hydrolysis of sucrose in acid lime juice sac cells

The sucrose content of acid lime [ Citrus aurantifolia (Christm.) Swing.] juice tissue was measured at time 0 and at various times following incubation at 15.5, 26.6 and 37.7°C. The decline in sucrose content in fruit stored at 15.5°C paralleled the expected values for a sucrose solution at pH 2.1. At higher temperatures, the in vivo sucrose content decreased at significantly lower rates than the expected values. In fruit stored at 26.6 and 37.7°C, the vacuolar pH increased 0.11 and 0.23 units, respectively. When sucrose hydrolysis was recalculated at the increased vacuolar pH of juice cells stored at 26.6 and 37.7°C, the calculated values were similar to the measured values obtained in vivo. It is concluded that within the limits of the experimental conditions, the rates of sucrose acid hydrolysis are regulated by changes in the vacuolar H⁺ concentration.     

Major histocompatibility complex class II-regulated immunity to murine leukemia virus protects against early T- but not late B-cell lymphomas

We studied the relative importance of class I and class II major histocompatibility complex (MHC) immunoregulation in the control of T- and B-cell lymphomas induced by murine leukemia virus. Previously, we have described a mink cell focus-inducing (MCF) murine leukemia virus, MCF 1233, which induces not only lymphoblastic T-cell lymphomas but also follicle center cell or lymphoblastic B-cell lymphomas. We now report that the outcome of neonatal infection with MCF 1233 in H-2-congenic C57BL/10 and C57BL/6 mice is decisively influenced by the H-2 I-A locus. A total of 64% of H-2 I-Ak, d mice [B10.BR, B10.D2, B10.A(2R), B10.A(4R), and B10.MBR] developed T-cell lymphomas after MCF 1233 infection (mean latency, 37 weeks). In contrast, H-2 I-Ab [B10, B10.A(5R), B6], H-2 I-Ab/k [(B10.A x B10)F1 and (B10 x B10.A)F1], and H-2 I-Abm12 (bm12) mice were resistant against T-cell lymphomagenesis, but 65% of these H-2 I-Ab, b/k, bm12 animals developed B-cell lymphomas (mean latency, 71 weeks). Animals of T-cell lymphoma-susceptible strains that escaped from T-cell lymphomagenesis developed B-cell lymphomas with similar frequency as animals of T-cell lymphoma-resistant strains, but with a shorter latency. H-2 class II-determined regulation of antiviral immunity was reflected in the presence of high titers of antiviral envelope antibodies in T-cell lymphoma-resistant B-cell lymphoma-susceptible H-2 I-Ab, b/k, bm12 mice, whereas in T-cell lymphoma-susceptible H-2 I-Ak,d mice no antiviral antibodies were found. At week 4 after neonatal MCF 1233 infection, a high percentage of thymocytes were virally infected in both T-cell lymphoma-susceptible and -resistant mice. However, T-cell lymphoma-resistant animals cleared the thymic infection between weeks 4 and 10 of age, coinciding with a sharp rise in serum levels of antiviral antibodies. We conclude that the pleiotropic effects of MCF 1233 infection in H-2-congenic mice result from MHC class II I-A-determined T-cell response differences.     

Geometrical differences between neck motoneurons located in the brainstem and spinal cord in the mallard Anas platyrhynchos L.; a Golgi study.

The dendrite geometry of neck motoneurons located in the upper cervical cord and lower brainstem of the mallard was studied in Golgi silver impregnated material. Measurements were obtained from camera lucida drawings and concerned the extent and orientation of dendritic trees. Dendrites were found to be oriented predominantly parallel to the sagittal plane, and projections were asymmetric in the dorso-ventral direction. Comparison between motoneurons located in the supraspinal nucleus of the brainstem and motoneurons in the ventral horn of the upper spinal cord showed that dendrites of motoneurons in the first cell group branch more often than those of neurons in the latter group. In addition, dendritic trees of ventral horn motoneurons preferentially project into the field dorsal to the cell body.