EEG and behavioral effects of gamma-hydroxybutyrate in the rabbit

The effects of gamma-hydroxybutyrate (GHB) upon sleep wakefulness patterns and quantified nuchal muscle activity were examined in the rabbit in a dose-response paradigm (25–1,000 mg/kg). Relative to control (saline) values, there was no facilitation of sleep onset or epileptogenic activity at any of the dosages studied. However, at the higher GHB concentrations, slow wave sleep and tonic muscle activity were enhanced and a high amplitude, slow activity was superimposed on background EEG patterns. The highest concentration of GHB (1,000 mg/kg) was associated with depression of motor activity. An enhancement of paradoxical sleep observed at lower GHB levels in other species occured in attenuated form in the rabbit. The results indicate dose-related effects on both sleep and motor activation in the rabbit, but the absence of seizure activity for the concentrations of GHB studied.     

Anonymous nuclear DNA markers in the American oyster and their implications for the heterozygote deficiency phenomenon in marine bivalves

A puzzling population-genetic phenomenon widely reported in allozyme surveys of marine bivalves is the occurrence of heterozygote deficits relative to Hardy-Weinberg expectations. Possible explanations for this pattern are categorized with respect to whether the effects should be confined to protein-level assays or are genomically pervasive and expected to be registered in both protein- and DNA-level assays. Anonymous nuclear DNA markers from the American oyster were employed to reexamine the phenomenon. In assays based on the polymerase chain reaction (PCR), two DNA-level processes were encountered that can lead to artifactual genotypic scorings: (a) differential amplification of alleles at a target locus and (b) amplification from multiple paralogous loci. We describe symptoms of these complications and prescribe methods that should generally help to ameliorate them. When artifactual scorings at two anonymous DNA loci in the American oyster were corrected, Hardy-Weinberg deviations registered in preliminary population assays decreased to nonsignificant values. Implications of these findings for the heterozygote-deficit phenomenon in marine bivalves, and for the general development and use of PCR-based assays, are discussed.      

Characterization of a stable,anchorage-dependent clone obtained from a spontaneously transformed mouse cell line

Summary A variant nontransformed clone, I21, was selected from the spontaneously transformed mouse fibroblast line, IT22. Selection was done by plating IT22 in methylcellulose and picking single cells after 2 d. Cultures derived from these single cells were selected again and one clone, I21, derived from the second round of selection was characterized extensively. I21 and IT22 have the same plating efficiency (PE) on plastic, but in agarose they differ by 1000-fold. In comparison to IT22, I21 has a normal morphological appearance, a lower saturation density, a higher viability in stationary phase, an increased doubling time, an increased chromosome content, and is unable to form tumors in nude mice. I21 has remained remarkably stable in culture and has not reverted to the transformed phenotype for at least 300 generations in culture. Over 100 clones of I21, expanded to 10⁶ cells, failed to show an increased PE in agarose. Even expansion of the rare colonies of I21 that grow in agarose failed to produce clones similar to IT22. The research was supported by the Medical Research Council and the National Cancer Institute of Canada. R. Godbout was supported by a 1967 Science Scholarship and by an MRC Studentship. B. L. Gallie is a Research Associate of the Ontario Cancer Treatment and Research Foundation.     

Basolateral plasma membrane localization of ouabain-sensitive sodium transport sites in the secretory epithelium of the avian salt gland

The distribution of Na+ pump sites (Na+-K+-ATPase) in the secretory epithelium of the avian salt gland was demonstrated by freeze-dry autoradiographic analysis of [(3)H] ouabain binding sites. Kinetic studies indicated that near saturation of tissue binding sites occurred when slices of salt glands from salt-stressed ducks were exposed to 2.2 μM ouabain (containing 5 μCi/ml [(3)H]ouabain) for 90 min. Washing with label-free Ringer's solution for 90 min extracted only 10% of the inhibitor, an amount which corresponded to ouabain present in the tissue spaces labeled by [(14)C]insulin. Increasing the KCl concentration of the incubation medium reduced the rate of ouabain binding but not the maximal amount bound. In contrast to the low level of ouabain binding to salt glands of ducks maintained on a freshwater regimen, exposure to a salt water diet led to a more than threefold increase in binding within 9-11 days. This increase paralleled the similar increment in Na+-K+-ATPase activity described previously. [(3)H]ouabain binding sites were localized autoradiographically to the folded basolateral plasma membrane of the principal secretory cells. The luminal surfaces of these cells were unlabeled. Mitotically active peripheral cells were also unlabeled. The cell-specific pattern of [(3)H]ouabain binding to principal secretory cells and the membrane-specific localization of binding sites to the nonluminal surfaces of these cells were identical to the distribution of Na+-K+-ATPase as reflected by the cytochemical localization of ouabain-sensitive and K+-dependent nitrophenyl phosphatase activity. The relationship between the nonluminal localization of Na+-K+-ATPase and the possible role of the enzyme n NaCl secretion is considered in the light of physiological data on electrolyte transport in salt glands and other secretory epithelia.     

The early life history of two sympatric New Zealand octopuses: eggs and paralarvae of Octopus huttoni and Pinnoctopus cordiformis

This study combined morphological and morphometric information on egg clutches, egg capsules and paralarvae of two sympatric coastal octopuses from New Zealand waters, Octopus huttoni and Pinnoctopus cordiformis, to provide species-specific traits to identify their early life stages obtained from field surveys. Eggs of O. huttoni (2.5 mm length; 1 mm width) were entwined with one another forming strings that ranged from 11 to 25.8 mm in length. Eggs of P. cordiformis (6.4 mm length; 1.5 mm width) were significantly bigger than those of O. huttoni and were grouped in small clusters of about seven eggs. Paralarvae O. huttoni and P. cordiformis differed in hatching size (1.4 mm versus 3.1 mm mantle length), number of suckers per arm (four versus eight), number of lamellae per outer demibranch (five versus ten) and arrangements of chromatophores in the body surface (29 to 59 versus 91 to 179), respectively. The morphological traits described in hatchlings from the laboratory allowed comparisons with field-collected paralarvae, suggesting that such characters were reliable species-specific patterns to enable a consistent differentiation between the early life stages of these two sympatric species, even in the absence of the brooding female.     

Molecular Mechanism by Which a Potent Hepatitis C Virus NS3-NS4A Protease Inhibitor Overcomes Emergence of Resistance

Although optimizing the resistance profile of an inhibitor can be challenging, it is potentially important for improving the long term effectiveness of antiviral therapy. This work describes our rational approach toward the identification of a macrocyclic acylsulfonamide that is a potent inhibitor of the NS3-NS4A proteases of all hepatitis C virus genotypes and of a panel of genotype 1-resistant variants. The enhanced potency of this compound versus variants D168V and R155K facilitated x-ray determination of the inhibitor-variant complexes. In turn, these structural studies revealed a complex molecular basis of resistance and rationalized how such compounds are able to circumvent these mechanisms.     

Daily Changes of Plasma Corticosterone by an 8-h Daytime Feeding Occur Without Body Weight Loss or Severe Food Restriction in the Rat

Different studies have reported that daytime feeding entrains the circadian rhythm of corticosterone secretion in rats. However, it remained unclear whether calorie restriction or daytime feeding access have an effect. The aim of our study is to evaluate the effect of an 8-h daytime feeding access on the circadian rhythm of plasma corticosterone. Eleven adult male Wistar rats were assigned to two different conditions of access to food: ad lib feeding for one week and daytime feeding for the following two weeks. On the 7th, 14th and 21st day, blood samples were collected every 4 h from 08:00 to 04:00. Food intake and body weight were recorded daily. During daytime feeding, rats ingested 88% of the amount of food ingested over 24 h in the ad lib feeding period. However, body weight increased significantly from the first day to the end of experiment. Peak plasma corticosterone was 12 h shifted during daytime feeding period compared to the ad lib condition. This study showed that an 8-h daytime feeding entrained the circadian rhythm of plasma corticosterone without body weight loss or severe food restriction.