Transgenic sorghum plants obtained after microprojectile bombardment of immature inflorescences

Summary Transgenic sorghum plants (Sorghum bicolor L. Moench, cv. SRN39) were obtained by microprojectile-mediated DNA delivery (Bio-Rad PDS 1000/He Biolistic Delivery System) to explants derived from immature inflorescences. Explants were precultured on medium supplemented with 2.5 mg/l (11.31 μM) 2,4-D, 0.5 mg/l (2.32 μM) kinetin, and 60 g/l sucrose for 1 to 2 wk prior to bombardment. Bialaphos selectron pressure was imposed 2 wk after bombardment and maintained throughout all the culture stages leading to plant regeneration. More than 2500 explants from 1.5 to 3.0 cm inflorescences were bombarded and subjected to bialaphos selection. Out of more than 190 regenerated plants, 5 were determined to be Ignite resistant. Southern analyses confirmed the likelihood that the 5 herbicide resistant plants derived from two independent transformation events. The phosphinothricin acetyltransferase gene (bar) was inherited by and functionally expressed in T₁ progeny. However, no β-glucuronidase (GUS) activity could be detected in T₁ plants that contained uidA restriction fragments. Histological analyses indicated that in the absence of bialaphos morphogenesis was primarily via embryogenesis while organogenesis was more predominant in callus maintained with herbicide selection.     

Transgenic tobacco plants expressing the putative movement protein of tomato spotted wilt tospovirus exhibit aberrations in growth and appearance

Within the Bunyaviridae virus family, members of the genus Tospovirus are unique in their ability to infect plants. A characteristic genetic difference between tospoviruses and the animal-infecting members of this virus family is the occurrence of an additional gene, denoted NSM, located on the genomic M RNA segment. This gene has previously been implicated in the cell-to-cell movement of this virus during systemic infection. Transgenic tobacco plants have been obtained expressing the NSM protein of tomato spotted wilt virus (TSWV), the type member of the tospoviruses, from a constitutive promoter. Detectable amounts of the NSM protein could be observed in plants from nine different lines. The protein was only detectable in fractions enriched for cell wall material. More detailed immunogold labelling studies revealed specific association of NSM protein with plasmodesmata. Plants accumulating the NSM protein to detectable levels developed aberrations in growth, resulting in a significant reduction of size and accelerated senescence. In addition, these plants are restricted in their capacity to produce flowers. The results presented provide additional evidence that the NSM protein, by modifying plasmodesmata, represents the cell-to-cell movement function of tospoviruses. Furthermore, the phenotype of the NSM transgenic plants suggests involvement of the NSM gene product in TSWV symptom expression     

The Dutch N-cascade in the European perspective

The Netherlands is "well known" for its nitrogen problems; it has one of the highest reactive nitrogen (Nr) emission densities in the world. It is a small country at the delta of several large European rivers. Ever since the industrial revolution, there has been a growing excess of nutrients and related emissions into the atmosphere (ammonia, nitrogen oxides and nitrous oxide)and into groundwater and surface water (nitrate), leading to a large range of cascading environmental impacts. Vehicular traffic, sewage and animal husbandry are the main sources of oxidized and reduced forms of Nr. This paper provides an overview of the origin and fate of nitrogen in the Netherlands, the various reported impacts of nitrogen, the Dutch and European policies to reduce nitrogen emissions and related impacts. In addition, ways are presented to go forward to potentially solve the problems in a European perspective. Solutions include the improvement of nitrogen efficiencies in different systems, technological options and education.     

Histological and immunohistochemical effects of Curcuma longa on activation of rat hepatic stellate cells after cadmium induced hepatotoxicity

The liver is a target for toxic chemicals such as cadmium (Cd). When the liver is damaged, hepatic stellate cells (HSC) are activated and transformed into myofibroblast-like cells, which are responsible for liver fibrosis. Curcuma longa has been reported to exert a hepato-protective effect under various pathological conditions. We investigated the effects of C. longa administration on HSC activation in response to Cd induced hepatotoxicity. Forty adult male albino rats were divided into: group 1 (control), group 2 (Cd treated), group 3 (C. longa treated) and group 4 (Cd and C. longa treated). After 6 weeks, liver specimens were prepared for light and electron microscopy examination of histological changes and immunohistochemical localization of alpha smooth muscle actin (αSMA) as a specific marker for activated HSC. Activated HSC with a positive αSMA immune reaction were not detected in groups 1 and 3. Large numbers of activated HSC with αSMA immune reactions were observed in group 2 in addition to Cd induced hepatotoxic changes including excess collagen deposition in thickened portal triads, interlobular septa with hepatic lobulation, inflammatory cell infiltration, a significant increase in Kupffer cells and degenerated hepatocytes. In group 4, we observed a significant decrease in HSC that expressed αSMA with amelioration of the hepatotoxic changes. C. longa administration decreased HSC activation and ameliorated hepatotoxic changes caused by Cd in adult rats.     

Inhibition of interferon secretion by vinblastine

The plant alkaloids vinblastine and colchicine are known to arrest cells in mitosis by virtue of their binding to spindle protein. These drugs are also capable of binding to microtubule protein and causing these structures to disaggregate into nonfunctional subunits (1, 2). Microtubular structures are thought to be involved in the secretory process of a number of proteins including insulin (7), collagen (4), and thyroid hormone (12). In this report we present our findings on the effects of these two drugs on the synthesis and secretion of interferon in a high producing human foreskin fibroblast strain (FS-4) (11).     

A simple method for following the fate of alanine-containing components in murein synthesis inEscherichia coli

The fate of the alanine-containing components in murein synthesis was followed by incorporation of¹⁴C-l-alanine inE. coli under conditions allowing cell-wall synthesis while preventing protein synthesis. The components were separated by chromatography and detected by autoradiography.Spots containing murein, cell-wall precursors, alanine andd-alanyl-d-alanine were identified. A further component was probably identical to pyruvic acid. Two unidentified spots were found in the region where lipid-intermediates in cell-wall synthesis are usually found. However, the absence of turnover of these two components was at variance with the proposed properties of the lipidintermediates. d-Alanyl-d-alanine and the component which is probably identical to pyruvic acid were excreted into the medium, whereas murein and cell-wall precursors were found in the cellular fraction.The influence of the concentration of alanine, and of the number of cells per ml, on the acid-precipitable activity were studied. The latter increased during, at least, the first two hours and represented mainly lysozyme-degradable material.Significant turnover of murein could be detected neither in the presence nor in the absence of protein synthesis.A time course of the activity of the radioactive components is provided. The influence of a number of antibiotics inhibiting cell-wall synthesis on the acid-precipitable activity and on the activity of the main intermediates in murein synthesis was studied.We thank Mrs. Arna van Schijndel-van Dam and Mr. A. A. G. Verweij for excellent assistance. We thank Dr. P. E. Reynolds (University of Cambridge) for teaching one of us (E J. J. L.) several techniques in the field of bacterial cell walls, and Dr. H. J. W. Wijsman for stimulating discussions.     

A multipurpose muscle ergometer

A fast (0.1 mm steps within 2 ms), strong (40 N continuously) and accurate (resolution 0.002 N and 1.0 micron) muscle ergometer was developed to test dynamic and static properties of mammalian muscle. Both for twitches and for tetani isometric, isokinetic and isotonic contractions can be measured accurately. Force-velocity data and time to peak-force data of four EDL muscles, as well as force-extension data of their serial tendinous structures are shown to demonstrate the machine.