cDNA probes of individual genes of human rotavirus distinguish viral subgroups and serotypes

The use of cDNA probes for detection of rotaviruses has been investigated using plasmids containing inserts specific for each of the eleven genes of human rotavirus strain Wa. In a dot-blot detection system in which radioactive DNA probes were hybridized to viral RNA extracted from cultivatable rotavirus strains, cDNAs of genes 7, 8, 10 and 11, were found to be the most reliable probes for detecting a range of rotavirus strains. Unexpectedly, rotaviruses could be distinguished with respect to subgroup and subtype specificities when cDNAs of genes 6 and 9, which encode the immunologically relevant proteins VP6 (group-specific antigen) and VP7 (type-specific antigen), were used as probe, even though the nucleic acid sequences of these genes are known to have a high degree of sequence homology.

Large scale synchronous mating and the study of macronuclear development in Euplotes crassus

After conjugation in hypotrichous ciliates, a new macronucleus is produced from a copy of the micronucleus. This transformation involves large-scale reorganization of DNA, with conversion of the chromosomal micronuclear genome into short, gene-sized DNA molecules in the macronucleus. To study directly the changes that occur during this process, we have developed techniques for synchronous mating of large populations of the hypotrichous ciliate Euplotes crassus. Electron microscope studies show that the micronuclear chromosomes are polytenized during the first 20 h of macronuclear development. The polytene chromosomes lack the band-interband organization observed in other hypotrichs and in the Diptera. Polytenization is followed by transectioning of the chromosomes. We isolated DNA at various times of macronuclear development and found that the average molecular weight of the DNA decreases at the time of chromosome transectioning. In addition, we have shown that a small size group of macronuclear DNA molecules (450-550 base pairs) is excised from the chromosomal DNA approximately 10 h later in macronuclear development.

Electron microscope autoradiography of DNA synthesis in the replication band of two hypotrichous ciliates

The synthesis of DNA in two hypotrichous ciliates, Styx sp. and an amicronucleated strain of Oxytricha sp., was studied by high voltage (1000 kV) electron microscopy. High voltage EM permits use of thick sections (0.25-0.40 micron), including serial sections; thick sections produce strong autoradiographic images with relatively short exposure times. The autoradiographs show that DNA synthesis occurs in a narrow part of the rear zone of a replication band in the macronucleus. Macronuclear DNA synthesis occupies a substantial part of the interdivision interval, and micronuclear DNA synthesis in Styx sp. takes place in early prophase at a time when macronuclear DNA synthesis is in its terminal phase.

Meningioma of the parapharyngeal space: a unique extension of intracranial tumor

A 45-year-old woman with a meningioma growing in the parapharyngeal space is reported. Her initial symptom was a stuffy feeling in the right ear and swelling of the right parapharynx. The parapharyngeal mass was biopsied, and a frozen section diagnosis suggested a paraganglioma. On electron microscopy, however, the tumor cells failed to show secretory granules, and represented a prominent interdigitation of the cytoplasm with occasional desmosomal attachments. Based on these features the tumor was diagnosed as a meningioma. Thereafter a mass lesion in the temporal lobe of the brain was detected by computerized tomography of the brain. The extracranial extension of the meningioma may occur in some occasions, but such cases in which the infiltrative portion in the parapharyngeal space was initially discovered have been rarely reported.

Changes in adenylate cyclase and phosphodiesterase activities during the growth cycle of adult rat hepatocytes in primary culture

Long-term primary adult rat hepatocyte cultures show growth-state-dependent changes in adenylate cyclase and cAMP phosphodiesterase activities. Cellular adenylate cyclase activity decreases to undetectable levels within 1 day postplating, reappears on Days 4-5, and becomes maximal on Day 9. Membrane adenylate cyclase and cellular cAMP formation are insensitive to glucagon during log phase (Days 4-8) but not during lag (Day 1) or stationary phase (Day 12). Cyclic AMP phosphodiesterase activities (soluble and particulate) fall approximately equal to 70% by Day 2 but recover as proliferation begins. By contrast, the particulate phosphodiesterase assayed at 100 microM cAMP, decreased during Days 0-2. These observations simulate changes seen during liver proliferative transitions in vivo and, therefore, further support the use of these cultures as a developmental model.

Purification of the photoaffinity-labeled glucagon receptor by gel electrophoretic methods

Rat liver plasma membrane glucagon receptor has been purified with a yield of 0.01% to an estimated homogeneity of 32-60%, using a 2-stage electrophoretic procedure. SDS-solubilized membrane proteins labeled by the photoaffinity-agent, Ne-4-azidophenylamidinoglucagon (APA-glucagon), were separated by polyacrylamide gel electrophoresis in SDS-containing buffers. Gel slices corresponding to the molecular weight of the receptor were excised, electrophoretically extracted and concentrated. The concentrate was subjected to isoelectric focusing on Sephadex to yield a purified product in which the photoaffinity-labeled receptor, with a molecular weight of 56K and a pI' of 5.9, is the sole major component.

Expression of differentiated function by hepatocytes in primary culture: variable effects of glucagon and insulin on gluconeogenesis during cell growth

Hormonal effects on gluconeogenesis from lactate were studied during the growth cycle of adult rat parenchyma liver cells using a primary monolayer culture system previously described [25]. Basal and glucagon-stimulated gluconeogenic ability were found to decline rapidly during log phase, insulin-stimulated growth. A progressive recovery of gluconeogenesis activity was observed after cell division subsided. Rates of lactate-gluconeogenesis were found also to decline in the absence of prior insulin exposure. This decline was not as rapid as the loss observed in cells cultured with insulin. However, in insulin-deficient cultures gluconeogenesis was completely abolished after 12 days and did not reelevate with further incubation unless cells were washed and exposed to glucagon. Decreasing growth rates of insulin-supplemented cultures by decreasing serum concentrations resulted in comparatively higher gluconeogenic activity. The results presented here are consistent with previous observations of hepatic parenchymal expression of 'differentiated function' during cellular growth phases in culture (i.e., differentiated functions are generally lost during rapid growth and regained as cells become quiescent). The present study, however, presents unexpected effects of insulin on the apparent growth-state dependent gluconeogenic recovery. Our data imply that although insulin has long been known to inhibit gluconeogenesis, its presence in culture may facilitate long-term basal maintenance of gluconeogenic enzyme activity. Insulin also functions as a growth factor whose initial mitogenic effect correlates with decreased gluconeogenic function. These changes show no simple or predictive correlation with cyclic nucleotide metabolism.

Distribution of alpha- and beta-adrenoceptors in human urinary bladder

1 The distribution of alpha- and beta-adrenoceptors in isolated preparations of human bladder neck and detrusor muscle has been studied.2 Adrenaline caused contraction of the bladder neck which was blocked by phenoxybenzamine but unaltered by propranolol.3 Isoprenaline caused relaxation of the bladder neck which was blocked by propranolol. High concentrations caused contraction which was enhanced by propranolol but blocked by phenoxybenzamine.4 Detrusor muscle was relaxed by isoprenaline and this effect was blocked by propranolol. Phenylephrine caused relaxation of detrusor which was unaffected by phenoxybenzamine; in some cases contraction was produced in the presence of propranolol.5 It is concluded that the bladder neck contains mainly alpha-receptors and the detrusor mainly beta-receptors but both regions posses both types of adrenoceptor.