The effect of pentobarbital on the antinociceptive action of morphine in morphine-tolerant and non-tolerant rats

The interaction of sodium pentobarbital with morphine sulfate in both morphine-tolerant and non-tolerant rats was investigated using the tail-compression test for analgesia. Male Sprague-Dawley rats (300–350 g) were given pentobarbital (4, 8, or 16 mg/kg) 5 min before morphine (2, 4, 6, or 8 mg/kg). Control animals received two saline injections, or pentobarbital plus saline, or saline plus morphine. All injections were subcutaneous. Prior to the first injection, a baseline nociceptive threshold was determined for each rat by applying a modified micrometer to its tail and increasing the pressure until a squeak was elicited. Test readings were taken every half-hour for 2 hr beginning 30 min after the second injection. For the chronic studies, animals were first made tolerant to morphine by the administration of the narcotic twice a day for 3 days, increasing the dose from 10 to 50 mg/kg/injection. Identical testing procedures were then followed with these rats except that the test dose of morphine given on day 4 was in the range 8–128 mg/kg. It was found that Na pentobarbital, in the subanesthetic doses used, had neither antinociceptive nor hyperalgesic properties. Furthermore, the barbiturate had no effect on the antinociceptive action of morphine in either morphine-tolerant or non-tolerant rats.     

Orientation of the protonmotive force in membrane vesicles of escherichia coli

Membrane vesicles of Escherichia coli can be produced by 2 different methods: lysis of intact cells by passage through a French pressure cell or by osmotic rupturing of spheroplasts. The membrane of vesicles produced by the former method is everted relative to the orientation of the inner membrane in vivo. Using NADH, D-lactate, reduced phenazine methosulfate, or ATP these vesicles produce protonmotive forces, acid and positive inside, as determined using flow dialysis to measured the distribution of the weak base methylamine and the lipophilic anion thiocyanate. The vesicles accumulate calcium using the same energy sources, most likely by a calcium/proton antiport. Calcium accumulation, therefore, is presumably indicative of a proton gradient, acid inside. The latter type of vesicle, on the other hand, exhibits D-lactate-dependent proline transport but does not accumulate calcium with D-lactate as an energy source. NADH oxidation or ATP hydrolysis, however, will drive the transport of calcium but not proline in these vesicles. Oxidation of NADH or hydrolysis of ATP simultaneous with oxidation of D-lactate does not result in either calcium or proline transport. These results suggest that the vesicles are a patchwork or mosiac, in which certain enzyme complexes have an orientation opposite to that found in vivo, resulting in the formation of electrochemical proton gradients with an orientation opposite to that found in the intact cell. Other complexes retain their original orientation, making it possible to set up simultaneous proton fluxes in both directions, causing an apparent uncoupling of energy-linked processes. That the vesicles are capable of generating protonmotive forces of the opposite polarity was demonstrated by measurements of the distribution of acetate and methylamine (to measure the ΔpH) and thiocyanate (to measure the Δψ).     

The functional importance of structural features of ergosterol in yeast.

As an approach to the study of the relationship between the structure of sterols and their capacity to function in the lipid leaflet of membranes, various sterols were examined for their ability to support the growth of anaerobic Saccharomyces cerevisiae. A marked dependence on precise structural features was observed in growth-response and morphology. Of the chemical groups which distinguish ergosterol, the main sterol of S. cerevisiae, the hydroxyl group at C-3 was obligatory, and the other groups were found to be of the following relative importance: 24beta-methyl-delta22-grouping greater than 24beta-methyl group greater than delta5,7-diene system = delta5-bond approximately or equal to no double bond. Methyl groups at C-4 and C-14 were inconsistent with activity. Consequently, the data strongly suggest that the normal biosynthetic processes removal of methyl groups from the nucleus and introduction of one in the side chain are of functional significance. A double bond between C-17 and C-20 joining the steroidal side chain to the nucleus had no deleterious effect on the growth process but only if C-22 was trans-oriented to C-13. In the cis-case no growth at all proceeded. This means the natural sterol probably acts functionally in the form of its preferred conformer in which C-22 is to the right ("right-handed") in the usual view. Since the placing of a substituent (OH or CH3) in the molecule at C-20 in such a way that it appears on the front side in the right-handed conformer completely destroyed activity, the sterol apparently presents its front face to protein or phospholipid when complexing occurs.     

Failure of sensory adaptation in bacterial mutants that are defective in a protein methylation reaction.

Chemotactic bacteria, such as E. coli, detect changes in the chemical composition of the environment. Addition of an attractant or repellent leads to an immediate response, characterized by a change in the swimming behavior of the cells--a process known as sensory excitation. However, the response gradually disappears with time, despite the continued presence of the chemical--a process known as sensory adaptation. We report here the behavior of a class of nonchemotactic mutants (cheX) that can carry out sensory excitation but are defective in the process of sensory adaptation. These mutants are also defective in the ability to carry out a protein methylation reaction which has previously been implicated in the adaptation process (Goy, Springer and Adler, 1977). The results presented here establish a firm relationship between the methylation reaction and sensory adaptation.     

Group mating among Norway rats II. The social dynamics of copulation: Competition,cooperation, and mate choice

The social interactions within groups of Norway rats (Rattus norvegicus) had a strong impact on the individual pattern of copulation which, in turn, affects sperm precedence and the probability of implantation in this species. Males alternated uninterrupted ejaculatory series, augmenting each others' copulatory investment. Females took turns mating after receiving an intromission, collectively potentiating the males' copulatory behaviour; increasing the number of oestrous females increased the number of intromissions and ejaculations achieved by each male but did not affect the amount of copulation experienced by each female. These turn-taking patterns within each sex provided the opportunity to change partners and permitted the emergence of different sex-typical patterns of copulation. Furthermore, the dominant male contributed more intromissions and tended to give each female more ejaculations than the subordinates did. Dominant males were also more likely to inhibit the subordinates' sperm transport. Females competed among themselves for the opportunity to mate with a male as he approached ejaculation and were likely to protect more of the dominant male's sperm transport than the subordinate male's.     

Neuronal survival in intact ciliary ganglia in vivo and in vitro: Ciliary neuronotrophic factor as a target surrogate

Ciliary neuronotrophic factor (CNTF) requirements for neuronal survival in the intact ciliary ganglion (CG) have been investigated in organ culture. Exogenous CNTF was not essential for neuronal survival until embryonic Day 8. Three-day cultures from 5-day ganglia were similar with or without CNTF, showing numerous neurons and extensive neuritic development. In 3-day cultures from 8-day-old ganglia, however, no neurons survived without CNTF, and the ganglia contained only nonneuronal cells and cell debris. Similar ganglia cultured with CNTF contained many neurons, surrounded by nonneuronal cells, and abundant neuritic processes. Morphologic maturation of the neurons was less advanced in CNTF-supported ganglia than in their in vivo counterparts.     

湖北省潜水蜂一新种（膜翅目：潜水蜂科）

潜水蜂属Agriotypus Curtis全世界共报道8种,其中我国已知4种。本文新添一采自湖北省房县的新种:郑氏潜水蜂A.zhengi sp.nov。     

Different legumin protein domains act as vacuolar targeting signals.

Legumin subunits are synthesized as precursor polypeptides and are transported into protein storage vacuoles in field bean cotyledons. We expressed a legumin subunit in yeast and found that in these cells it is also transported into the vacuoles. To elucidate vacuolar targeting information, we constructed gene fusions of different legumin propolypeptide segments with either yeast invertase or chloramphenicol acetyltransferase as reporters for analysis in yeast or plant cells, respectively. In yeast, increasing the length of the amino-terminal segment increased the portion of invertase directed to the vacuole. Only the complete legumin alpha chain (281 amino acids) directed over 90% to the vacuole. A short carboxy-terminal legumin segment (76 amino acids) fused to the carboxy terminus of invertase also efficiently targeted this fusion product to yeast vacuoles. With amino-terminal legumin-chloramphenicol acetyltransferase fusions expressed in tobacco seeds, efficient vacuolar targeting was obtained only with the complete alpha chain. We conclude that legumin contains multiple targeting information, probably formed by higher structures of relatively long peptide sequences.     

Membrane-derived oligosaccharides (MDO's) promote closing of an E. coli porin channel.

The outer membrane of Escherichia coli is a diffusion barrier for macromolecules, but allows the passage of small hydrophilic solutes through non-specific channels, the porins. Some electrophysiological studies find reconstituted porins in a mostly open state, while those done with the patch-clamp technique performed on live cells suggest that the vast majority of the native channels are closed. We present here current measurements through porins from reconstituted outer membrane, which demonstrate that bacterial metabolites, the MDO's, which bathe the periplasmic side of the outer membrane, induce the channels to close. These findings illustrate that the degree of openness of porins can be regulated by compounds naturally found in bacteria.