Identification of (Na,K)ATPase inhibitor in brine shrimp,Artemia salina,as long-chain fatty acids

Summary An inhibitory activity to (Na,K)ATPase was found in cell extracts of the brine shrimp, Artemia salina, irrespective of its developmental stages. Organic solvent extraction together with gas chromatographic analysis reveals that the inhibitory activity is due to long-chain, non-esterified fatty acids and their derivatives. Unsaturated fatty acids, especially with cis-configuration, are more effective in inhibition than saturated ones.Abbreviations ATPase adenosine triphosphatase - EDTA ethylenediamine-tetraacetate - TLC thin-layer chromatography     

Incorporation of fatty acids by Streptococcus mutans

In a series of investigations into the cariogenicity of Streptococcus mutans, we studied the incorporation of exogenous fatty acids with reference to glucosyltransferase secretion and membrane fatty acid changes. When cells were grown with different fatty acids, both saturated and unsaturated fatty acids were readily incorporated into the membrane lipids and were biotransformed and elongated preferentially to the longer 16- and 18-carbon-chain fatty acids. This incorporation and chain-elongation led to significant changes in fatty acids composition. By adding fatty acids to the medium, it was possible to appropriately modify the degree of unsaturation and the relative ratio between specific fatty acids in the membrane lipids of S. mutans.     

Cutaneous vascular responses to heat simulated at a high altitude of 5,600 m

Six healthy young men were studied in a high-altitude chamber during a 60-min heat exposure at a simulated altitude of 5,600 m or 0.5 atmosphere absolute (ATA). The heat load was provided by increasing the chamber temperature to 38 degrees C at the rate of 1 degree C/min after a 60-min equilibrium period at thermoneutrality (28 degrees C). Our question was whether or not hypoxia causes differential changes in regional cutaneous circulation during heat exposure. Skin blood flow in the forearm (FBF) and the finger (FiBF), temperatures of the esophagus (Tes) and of the skin, and cardiac output (CO) were measured during the heat exposure at 0.5 ATA and at the sea level (1 ATA). During the equilibrium period, hypoxia increased the mean skin temperature and mean heat transfer coefficient, as well as FBF and forearm vascular conductance. The increased blood flow in the cutaneous circulation during the hypoxic exposure may reflect cutaneous vasodilation and vasoconstriction in other regions of the body, since there was no alteration in CO and total peripheral resistance. During heat exposure, Tes rose faster at high altitude than at sea level. However, at the end of the 60-min heat exposure, all thermal as well as circulatory parameters showed no difference between the two altitudes, except for the FiBF. An attenuated vasodilation in the fingers during heat exposure at high altitude suggests differential vascular controls and possible impairment of thermoregulation when additional stress, such as heat, is imposed. The data suggest that cutaneous blood flow during heat exposure is not uniform throughout the entire skin in a hypoxic environment.     

A new stichaeid fish of the genusAlectrias from Mutsu Bay,northern Japan

Alectrias mutsuensis sp. nov. is described on specimens collected from Mutsu Bay, Aomori Pref. This new species is rather deep dweller compared to other species of the genus, living on muddy bottoms, about 20 to 40 meters deep, and is diagnosed by the following characters: dermal crest on head reaching to occipital region; distance between end of dermal crest and dorsal fin origin less than eye diameter; end of anal fin separated from caudal fin; anterior dorsal spines before anal origin, slender and flexible; epaxial hypurals mostly fused into a single plate. A key to all nine species belonging to the subfamily Alectriinae is presented.     

Triterpenes from Periandra dulcis roots

Three oleanane triterpenes were isolated from the roots of Periandra dulcis,and identified as 3β-hydroxy-25-al-olean-18-en-30-oic acid (periandric acid I), 3β-hydroxy-25-al-olean-12-en-30-oic acid (periandric acid II) and 3-oxo-25-hydroxy-olean-12-en-30-oic acid. The former two compounds (periandric acids I and II) were identical with the aglycones obtained by hydrolysis of periandrin I and II, respectively and the latter one was a new triterpene.     

Circadian rhythms of testosterone-dependent behaviors,crowing and locomotor activity,in male Japanese quail

Summary An apparatus was devised to record crowing (mate calling by males) together with locomotor activity and recorded data was analyzed by several methods for rhythm analysis. Crowing and locomotor activity of Japanese quail held on long days were recorded during sexual development as estimated from circulating gonadotropins and testosterone. Both behaviors were testosterone-dependent but commencement of crowing preceded the increase in locomotor activity. When the two behaviors attained their maximum levels, crowing showed consistent daily rhythms in which two peaks were apparent, a major one at the onset of light and a broader one 8 hours later. Locomotor activity also showed a clear daily rhythm with a peak between the two peaks of crowing rhythm suggesting a fixed phase relationship between the two rhythms.Both rhythms free-ran under constant dim light with periods shorter than 24 h. They persisted in birds which had been castrated and then supplied with exogenous testosterone via implanted Silastic capsules. The durations of both rhythms were quite comparable to each other and they maintained a fixed phase relationship similar to that found under LD cycles.The results indicate that testosterone is essential for the induction of crowing and for the enhancement of locomotor activity but the formation of the rhythms in behavior was strictly dependent on a circadian oscillatory mechanism.Abbreviations LH luteinizing hormone - FHS follicle-stimulating hormone - LD light-dark - LDim light-dim light     

Flavonoids in the leaves of twenty-eight polygonaceous plants

Flavonoids in the leaves of twenty-eight species belonging to the Polygonaceae were studied. Thirty-three kinds of flavonoids were isolated, and eighteen kinds were obtained as crystals. Quercetin glycosides were commonly found in the family. In the quercetin glycosides, 3-O-rhamnoside was most frequently found: 3-O-glucuronide is also distributed widely. Myricetin glycosides were rare. Methylated flavonols were found in some species of the sectionsEchinocaulon andPersicaria. Eleven kinds ofC-glycosylflavones were found in the present survey, andC-glycosylflavones were distributed in all species of the genusRheum and in almost all species of the section Tiniaria.Rumex Acetosella andPolygonum suffultum are exceptional, the former contains flavone glycoside and the latterC-glycosylflavones only, as main components.     

IMP dehydrogenase. II. Purification and properties of the enzyme from Yoshida sarcoma ascites tumor cells

The preceding paper showed that IMP dehydrogenase [IMP:NAD+ oxidoreductase, EC 1.2.1.14] tended to form a precipitable complex(es) through ionic and hydrophobic interactions. On the basis of these observations, a method was developed for purification of IMP dehydrogenase from Yoshida sarcoma ascites cells. On SDS-polyacrylamide gel electrophoresis, the purified preparation (1.19 U/mg protein) appeared homogeneous and its minimum molecular weight was estimated to be 68K daltons. Amino acid analyses indicated a subunit molecular weight of 68,042. Molecular sieve chromatography in the presence of 10% (NH4)2SO4 showed that the molecular weight of the native enzyme was 127K daltons. These values indicate that the native enzyme is composed of two identical subunits. However, the purified enzyme gave 4 protein bands on polyacrylamide gel electrophoresis under non-denaturing conditions, and appeared as a single fraction in the vicinity of the void volume on Ultrogel AcA 34 column chromatography at low salt concentration, indicating that its molecular weight exceeded 200K daltons. These findings indicate that the enzyme tends to aggregate owing to its own physicochemical characteristics. The Km values for IMP and NAD were calculated to be 12 and 25 microM, respectively, and the Ki values for XMP, GMP, and AMP to be 109, 130, and 854 microM, respectively. The purified enzyme showed full activity in the presence of K+, and K+ could be partially replaced by Na+. PCMB inactivated the enzyme, but the activity was completely restored by the addition of DTT. Cl-IMP also inactivated the enzyme and IMP prevented this inactivation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evidence that cyclic AMP may regulate Ca2+-mobilization and phospholipases in thrombin-stimulated human platelets

The regulation of human platelet responses by cyclic AMP (cAMP) has been investigated by measuring thrombin-stimulated serotonin release, Ca²⁺ uptake and phospholipase activity. Thrombin-induced 1,2-diacylglycerol (DG) formation as a result of phospholipase C activation was inhibited by pretreatment with dibutyryl cAMP (dbcAMP) in a dose-dependent manner. Subsequent failure to produce phosphatidic acid (PA), which is converted from 1,2-DG by phosphorylation and would serve as intracellular Ca²⁺ ionophore, appeared to parallel the decrease in Ca²⁺ uptake activity. Phospholipase A₂ activity, monitored by the production of [³H]lysophosphatidylcholine and [³H]lysophosphatidylethanolamine, was also suppressed by dbcAMP. These data indicate that the intracellular cAMP level may be closely associated with Ca²⁺ uptake and phospholipases activation. In addition, it is suggested that alteration of intracellular cAMP regulates phospholipase activation and consequently platelet responses, perhaps by controlling available Ca²⁺ content.     

Significance of 12S Toxin of Clostridium botulinum Type E

The pathogenesis of type E botulism is discussed as an aspect of the physicochemical and biological properties of 12S toxins (prototoxin and trypsin-activated 12S toxin) and the Ealpha and Ebeta components of each 12S toxin. A molecular weight of 350,000 was determined for each 12S toxin and 150,000 for Ealpha and Ebeta. Owing to the structure comprising the subunits Ealpha and Ebeta, 12S toxins are much more stable than Ealpha at low pH values and high temperatures. Such was also the case with type A 19S toxin and its alpha component. The Ealpha component alone accounts for the total toxicity of type E toxin. The toxic substance detected in the blood of the animals administered 12S toxins orally or parenterally was identified as Ealpha from the molecular size and the chromatographic pattern. Prototoxin escaping from detoxification in the stomach owing to the subunit structure may undergo dissociation in the intestine to release the Ealpha component. After absorption, the activated Ealpha appeared in the circulating blood without any further signs of dissociation or enzymatic digestion.