Responsiveness of mesolimbic, mesocortical, septal and hippocampal cholecystokinin and substance P neuronal systems to stress, in the male rat

The effects of acute and subchronic stress upon discrete cholecystokinin (CCK) and Substance P (SP) neuronal systems have been studied. Adult male rats were exposed to foot-shock stress for periods of 2, 4, 10, 30 or 60 min, immediately following which they were decapitated; brains were rapidly removed and frozen, and subsequently microdissected and extracted. CCK and SP were determined by RIA. In the olfactory tubercule, stress had no effect upon CCK content, but induced a rapid depletion of SP. In the prefrontal cortex, increased CCK concentrations were found following 30 min of stress exposure. In the medial septum, foot-shock led to a rapid increase in CCK content, and to a similar but delayed change in SP levels. A rapid rise in CCK concentrations was also seen in the lateral septum, but no stress effect whatsoever upon SP occurred in this structure. In the dentate gyrus, CCK exhibited a biphasic responsiveness to stress, while SP levels were increased only at the later time intervals. These data demonstrate that discrete CCK and SP neuronal systems are responsive to stress, and thereby support a functional role for these peptides in the processing of neural and hormonal signals by the CNS.     

Carbonic anhydrase,carbondioxide levels and growth of Nitrosomonas

The ammonia oxidizing bacterium Nitrosomonas europaea was grown either (a) with added bicarbonate in the absence of added CO₂ (bubbled through the culture), (b) with added bicarbonate plus low added CO₂ (0.03% v/v), or (c) without added bicarbonate with high added CO₂ (1% v/v). Cell doubling times of 12 h were observed in 1% cultures; doubling times of 2 to 3-fold longer wre found with 0.03% CO₂ and/or bicarbonate grown cultures. The specific activity of carbonic anhydrase was 40–80% lower in cultures grown on 1% CO₂. These results are compared with those in heterotrophic and photosynthetic microorganisms.Scientific Contribution Number 1241 from the New Hampshire Agricultural Experiment Station     

Microbiochemical investiagation on diurnal rhythmic changes of the activities of the lactate dehydrogenase in the periportal and perivenous zones of the acinus of the rat liver

Summary Activities of the lactate dehydrogenase within the periportal zone and within the perivenous zone in the first layer of hepatocytes adjacent to terminal hepatic venules and the remainder of the perivenous parenchyma of the liver acinus were measured using a Lowry technique during a full 24-h cycle (08.00-08.00) in untreated adult male Wistar rats kept under 12 h of light and 12 h of darkness, scotophase 18.25-06.25. In all three regions studied a broad first maximum was recorded between 10.00 and 22.00 with the peak value at 16.00 and a high and narrow peak at 24.00. Zonal and intrazonal heterogeneity of the lactate dehydrogenase were retained during the full day and night cycle. The regions displayed individual dynamic changes in enzyme activity.Supported by the Deutsche Forschungsgemeinschaft (Hi 318/21)     

Oxidoreductases Involved in Cell Carbon Synthesis of Methanobacterium thermoautotrophicum

Cell-free extracts of Methanobacterium thermoautotrophicum were found to contain high activities of the following oxidoreductases (at 60°C): pyruvate dehydrogenase (coenzyme A acetylating), 275 nmol/min per mg of protein; α-ketoglutarate dehydrogenase (coenzyme A acylating), 100 nmol/min per mg; fumarate reductase, 360 nmol/min per mg; malate dehydrogenase, 240 nmol/min per mg; and glyceraldehyde-3-phosphate dehydrogenase, 100 nmol/min per mg. The kinetic properties (apparent V_max and K_M values), pH optimum, temperature dependence of the rate, and specificity for electron acceptors/donors of the different oxidoreductases were examined. Pyruvate dehydrogenase and α-ketoglutarate dehydrogenase were shown to be two separate enzymes specific for factor 420 rather than for nicotinamide adenine dinucleotide (NAD), NADP, or ferredoxin as the electron acceptor. Both activities catalyzed the reduction of methyl viologen with the respective α-ketoacid and a coenzyme A-dependent exchange between the carboxyl group of the α-ketoacid and CO₂. The data indicate that the two enzymes are similar to pyruvate synthase and α-ketoglutarate synthase, respectively. Fumarate reductase was found in the soluble cell fraction. This enzyme activity coupled with reduced benzyl viologen as the electron donor, but reduced factor 420, NADH, or NADPH was not effective. The cells did not contain menaquinone, thus excluding this compound as the physiological electron donor for fumarate reduction. NAD was the preferred coenzyme for malate dehydrogenase, whereas NADP was preferred for glyceraldehyde-3-phosphate dehydrogenase. The organism also possessed a factor 420-dependent hydrogenase and a factor 420-linked NADP reductase. The involvement of the described oxidoreductases in cell carbon synthesis is discussed.     

Nucleoside triphosphate pools in minicells of Escherichia coli.

The nucleoside triphosphate pools of Escherichia coli minicells are different from those in parental cells. The growth phase in which minicells accumulate significantly affects the pool sizes.     

Activities evoked in different strain structures by stimulation of the contralateral tectum in the chick]

In the chick, as soon as hatching, the responses recorded in various areas in the "accessorius hyperstriatum" (Wulst) seem to be very localized in relation with the stimulated region of the contralateral tectum. Very similar results are obtained within the other striate structures. These observations suggest in first part, that the tectal efferents project very diffusely to various striate structures and, in other part, that it exists in these a rather precise tectotopy and a columnar organisation. These results appear very constant during the first month of the hatching.     

Parallel measurements of bound calcium and force in glycerinated rabbit psoas muscle fibers

A simple double-isotope procedure has been developed for making simultaneous measurements of bound Ca²⁺ and relative force in glycerinated rabbit psoas bundles containing two fibers. With this preparation it is possible to study Ca²⁺-troponin interactions coincident with MgATP-induced force development. Over the free [Ca²⁺] range 6 · 10^?8–1.2 · 10^?5 M the bound Ca²⁺ varied from 0.25 to 1.65 μmol/g protein. The free [Ca²⁺] at half-maximal Ca²⁺ saturation was 2 · 10^?7 M while that a half-maximal force was 5 · 10^?7 M. Half-maximal Ca²⁺ saturation was associated with 20% maximal force. The force-[Ca²⁺] saturation curve showed a steep rise in slope at greater than half saturation. The observed relationship was consistent with a model in which multiple occupancy of troponin Ca²⁺-binding sites is essential for initiation of cross-bridge cycling.     

Stimulation of myometrial and decidual prostaglandin production by amniotic fluid from term,but not midtrimester pregnancies

The effect of amniotic fluid obtained from second trimester (16–20 wks) and term pregnancies (38–41 wks) on the production of PGE and F by human amnion, decidua and myometrium at term was determined using tissue slices incubated in vitro. Midpregnancy amniotic fluid neither inhibited nor stimulated the prostanoid production by any of the tissues. In contrast, term amniotic fluid obtained before as well as after the onset of labor markedly increased the production of both PGE and PGF in decidua and myometrium from levels in Krebs solution. The prostanoid production (PGE + PGF) in amnoin was not significantly increased but the proportion of PGF was raised during incubations in term amniotic fluid. In decidua and myometrium the increase in PGE and PGF production in term amniotic fluid was approximately 200 and 400 percent respectively, from control values in Krebs solution. We propose that the stimulatory activity in term amniotic fluid in responsible for the accelerated synthesis of prostaglandins after of membranes, which is reflected in raised PGF metabolite levels in maternal circulation. It may also be the reason for the rise in amniotic fluid prostaglandin levels around the 35th week of gestation, and perhaps for the onset of labor.