Neurofilament-like and glial fibrillary acidic protein-like immunoreactivities in rat and guinea-pig sympathetic ganglia in situ and after perturbation

Summary The presence of neurofilament (NF)-like and glial fibrillary acidic protein (GFAP)-like immunoreactivities was studied in sympathetic ganglia of adult rats and guinea pigs during normal conditions and after perturbation. In the superior cervical ganglion (SCG) of normal rats, many ganglion cells and nerve fibers show NF immunoreactivity. Some of these nerve fibers disappear after preganglionic decentralization of SCG; this indicates the presence of a mixture of preand postganglionic NF-positive nerves in the ganglion. Cuts in both preand postganglionic nerves result in a marked increase in GFAP immunoreactivity in SCG, whereas NF immunoreactivity increases in nerve cell bodies after preganglionic cuts. Only a few ganglion cells show NF immunoreactivity in the normal SCG of guinea pig. All intraganglionic NF-positive nerves are of preganglionic origin; decentralization abolishes NF immunoreactivity in these nerve fibers. The inferior mesenteric ganglion, the hypogastric nerves and colonic nerves in guinea pigs contain large numbers of strongly NF-immunoreactive nerve fibers.When the SCG of adult rat is grafted to the anterior eye chamber of adult rat recipients, both ganglionic cell bodies and nerve fibers, forming on the host iris from the grafted ganglion, are NF-positive. As only the perikarya of these neurons normally exhibit NF immunoreactivity, and the terminal iris arborizations are NF-negative, it appears that the grafting procedure causes NF immunoreactivity to become more widespread in growing SCG neurons.     

A morphometric and ultrastructural study of lithium-induced changes in the medullary collecting ducts of the rat kidney

Summary Rats were given a lithium-containing diet (40 mmol/kg) to Study the effect of lithium on the structure of collecting ducts from the inner stripe of the outer medulla. The results show that there is a significant increase in the volume density of collecting ducts already after one week on this diet. The volume density of both intercalated and principal cells increases, whereas the volume density of mitochondria in the cytoplasm increases in the intercalated cells only. The increased volume of both principal and intercalated cells seems to be part of a general hyperplasia and hyperactivity of the collecting duct, which may in some way be related to the effects of lithium on vasopressinmediated water transport. The specific changes in the intercalated cells may be a consequence of the effects of lithium on distal nephron potassium and hydrogen ion transport in the distal nephron.     

Testing the “methanochondrion concept”: are nucleotides transported across internal membranes in Methanobacterium thermoautotrophicum?

In order to test the Methanochondrion concept, uptake of adenine nucleotides in various membrane preparations of Methanobacterium thermoautotrophicum was studied. The uptake showed properties which are in general interpreted as indicative of a transport mechanism: (i) kinetics in the time range of minutes, (ii) temperature dependence, (iii) substrate specificity and (iv) failure to remove the substrate by extensive washing.However, nucleotide transport as an interpretation of this uptake can definitely be excluded. Not only an exchange mechanism of the mitochondrial type, but also a general exchange or an uniport mechanism was ruled out. In contrast, the nucleotide uptake was shown to be actually a tight and specific binding of ADP and ATP to binding sites at the interior side of the cell membrane. This was conclusively demonstrated in protoplasts obtained from M. thermoautotrophicum cells. In these protoplasts which do not contain internal membranes also nucleotide binding was observed, but only after disruption of the plasma membrane by osmotic lysis, which leads to the exposure of binding sites.     

Expression of antibody cDNA in murine myeloma cells: possible involvement of additional regulatory elements in transcription of immunoglobulin genes

Expression vectors for cDNA of the κ and λ1 chains of a monoclonal antibody directed against creatine kinase were introduced into murine myeloma cells. κ and γ1 cDNA were either under the control of the SV40 early promoter or of the cognate promoters and enhancers of the light- and heavy-chain genes. Secretion of immuno-reactive κ and γ1 chains into the culture medium was demonstrated with the SV40 promoter as well as with the cognate promoters. Expression of y 1 cDNA with the SV40 early promoter was about twice as high as with the heavy-chain promoter and enhancer. Expression of κ cDNA under the control of the S V40 early promoter was about 17 times higher than with the light-chain promoter and enhancer. These expression levels were compared to those of a genomic immunoglobulin (Ig) κ determinant, including introns. Such an entire κ gene led to expression of the light chain at levels double those with the κ cDNA construction using the SV40 promoter and about 35 times as high when using κ cDNA and the cognate promoter and enhancer. This result might indicate that, besides the cognate promoter and enhancer elements, other intragenic elements are involved in the regulation of Ig expression. However, the SV40 early promoter seems to be able to compensate for the absence of these postulated regulatory elements probably located in the introns.