Search

Achlya is a filamentous coenocytic fungus that grows only in the presence of Ca2+. The Ca2+ transport (uptake and binding) system of this organism was studied and shown to consist of two components: a low molecular weight Ca2+ binding glycopeptide present within the cell wall matrix and a Ca2+ uptake component associated with the cell membrane. Certain thiol group-reacting agents and cytokinin-active compounds enhanced Ca2+ binding and uptake, respectively. Ca2+ transport by intact cells showed pH dependence with optima at pH 6.5 and 8.5 and temperature dependence with maximal transport occurring at 40° (without activation) and 15° (with activation). Ca2+ transport proceeded by facilitated diffusion. The system is insensitive to metabolic inhibitors. Compounds with known cytokinin activity stimulated the release of Ca2+ bound to the cell wall glycopeptide, and these same compounds enhanced Ca2+ intake into osmotically shocked cells (lacking the glycopeptide). The half-saturation values for Ca2+ intake into cells and release from the glycopeptide are essentially identical.

Stevenson, M. M., G. D. Schnell, and R. Black (Department of Zoology and Stovall Museum of Science and History, and College of Education, Education Special Projects [Black], University of Oklahoma, Norman, Oklahoma 73069) 1974. Factor analysis of fish distribution patterns in western and central Oklahoma. Syst. Zool. 23:202-218.-The distribution patterns of western and central Oklahoma fishes were analyzed, utilizing factor analytical techniques, to determine generalized patterns and their correlation with certain environmental variables. Twenty-seven drainage units of the major Arkansas and Red river tributaries were scored for the presence or absence of each of 53 species and values for 13 environmental variables. Six factor groups were obtained through oblique rotation of principal axes that were factored from the correlation matrix of the variables. These six associations were judged biologically meaningful and provide insight into the limiting factors affecting the Oklahoma fish fauna. The relative effects of historical and environmental components on current distribution groupings are discussed and some predictions are made conceming future faunal changes. [Zoogeography; fish distribution; Oklahoma; factor analysis.] Traditionally, zoogeographic studies often have involved the classification of "regions" or grouping of species distribution patterns on the basis of a presupposed explanatory hypothesis. While the conclusions of such an analysis may be correct, it is difficult to effectively evaluate results since the reasoning presented often appears to contain a considerable degree of circularity. However, in Fisher (1968) and Smith and Fisher (1970), this a priori method of creating the ('most plausible grouping patterns" was abandoned. For example, Smith and Fisher (1970) objectively arranged distribution data on Kansas fish species (and environmental data) into a few generalized patterns using factor analysis, and only then were interpretations attempted of the common casual factors affecting each group. We have utilized a similar method to analyze and interpret information on fish distributions in western and central Oklahoma (e.g., west of the 970 meridian). Such an approach should give some insight into the limiting factors which, singularly or in 1 Present address: Tulane University, Systematic and Environmental Biology Laboratory, Environmental Science Center, Route 1, Box 46-B, Belle Chasse, Louisiana 70037. combination, have affected fish distributions in the past, and at least some degree of predictive ability concerning the possible effects of environmental modifications in the future. This rather delimited region was chosen mainly because of the general simplicity of stream type and the relatively complete collections available. We felt it more likely that patterns might be discernable and/or explainable in a relatively uncomplicated environment. The major systems are most often second and third order streams (in the sense of Horton, 1945), with wide flood plains, low relief, sandy bottoms, and a relatively high content of dissolved solids. However, the region also contains a few areas that are major exceptions to this generalization (e.g., the Wichita Mountains). With our analysis, certain generalized patterns of species distributions were discovered which in retrospect are suggested and often predictable on the basis of known ecological requirements of some of the included species. As a working hypothesis, we assumed that one or more of the tested environmental variables would be correlated with and help explain each of the discernable distributional patterns. The co

SummaryADP-induced platelet aggregation and the breakdown of ADP in platelet-poor plasma of normal and magnesium deficient calves and rats have been studied. There was no statistically significant difference in ADP-induced platelet aggregation between the treated and untreated groups of animals. There was a significant difference in the ADP breakdown in platelet poor plasma of magnesium deficient rats as compared to the untreated animals. The platelet count of the magnesium deficient calves and in the citrated platelet-rich plasma of the magnesium deficient rats was not different from the normal. The thrombin clotting and partial thromboplastin times were significantly shortened in the magnesium deficient calves, but the prothrombin time was not affected. These findings suggest that pathological alterations in the serum magnesium levels that are still compatible with life do not influence adenosine diphosphate-induced platelet aggregation but do affect the breakdown of adenosine diphosphate in the plasma of rats. Just as magnesium administration may produce an anticoagulant effect, so may magnesium depletion produce a procoagulant effect in the blood of animals rendered magnesium deficient by diet. The clinical implications of this are discussed.

A series of studies was made upon the coumarin content of various species, varieties and individual plants of sweet clover (Melilotus), determinations being made from different parts of the plant, at different stages of growth, and upon herbage dried by different methods. The conclusions drawn from the results of these studies may be summarized as follows:— (1) Coumarin content of the leaf and stem of sweet clover changes rapidly throughout the various stages of growth. (2) Wide variations in coumarin content exist between different species, between different varieties within a species and often between different individuals within a variety. (3) There is a marked relation between color of leaf and coumarin content. Plants possessing dark-colored foliage have invariably tested higher in coumarin content than those with foliage of lighter color. (4) The Alpha variety possesses a lower coumarin content than any other variety of M. albus tested. (5) The species, Melilotus dentatus, used in these tests, contained less than 0.01% of coumarin in the foliage and less than 0.05% in the mature seeds. For all practical purposes it may be regarded as coumarin-free. (6) Air drying or oven drying of sweet clover results in a heavy loss of coumarin from the leaves and marked changes in the coumarin content of the stems. (7) There is a definite correlation between the coumarin content of the leaf and of the mature seed in the materials used. (8) The coumarin content of the mature seed provides a reliable estimate of the coumarin content of the leaf of the plant. (9) Breeding results indicate the possibility of producing low coumarin varieties through inbreeding and selection.

The supply of electrons for the hydroxylation reactions associated with cholesterol side-chain cleavage has been studied in intact porcine luteal mitochondria. The work was based on an assay of the NADPH-dependent side-chain-cleavage reaction, the activity of the mitochondrial enzyme complex being expressed as the percentage of [4-14C]cholesterol converted to the products, [4-14C]pregnenolone and [4-14C]progesterone, in 1 h. The reaction could best be supported by intermediates of the tricarboxylic acid cycle, although NADPH, and to a lesser degree NADH, would also support some activity. Investigations of the ADP:O ratios of the substrates which could support cholesterol side-chain cleavage showed that they were lower than the ADP:O ratios found for the same substrates in liver mitochondria from the same animal; respiratory-control ratios were also lower in the ovarian preparation. In the adrenal cortex, another steroid-hydroxylating tissue, similar results obtained by other workers have been interpreted as indicating that the two oxidative chains, the first terminating in cytochrome oxidase and the second in cytochrome P450, are connected by an energy-dependent transhydrogenase. In the ovary this explanation may be true for succinate, but it does not satisfy the results obtained with substrates which reduce NAD(P)+. Although spectrophotometric assays showed that there was some energy-linked transhydrogenase, as well as non-energy-linked transhydrogenase activity in ovarian mitochondria, all the evidence obtained by investigating cholesterol side-chain cleavage supported by NADH and the NAD+-specific 2-oxoglutarate dehydrogenase indicated that in ovary hydrogen transfer from NADH to the cholesterol-hydroxylation site was not dependent on energy. In contrast, inhibitors of NADH oxidase markedly stimulated NADH-supported side-chain cleavage. Energy was required for the transfer of electrons from succinate to the site of cholesterol side-chain cleavage.

Purified NAD-specified glutamic dehydrogenases from two fungi, Pythium debaryanum and Achlya sp. (1969), have been studied kinetically, and some of their physical properties elucidated. The enzymes are regulated by a multitude of allosteric effectors: NADP+, GTP, short chain acyl-CoA derivatives, P-enolpyruvate, and ATP as activators; citrate, AMP, and long chain CoA derivatives as inhibitors. The kinetic mechanism was determined for activated and non-activated enzymes. In both cases, an ordered binary-ternary mechanism prevailed. The order of substrate addition and product release is identical with the order found for all NADP-specific glutamic dehydrogenases although NADP+ is not a substrate of the enzyme. It is proposed that the enzyme may have evolved as a catalyst that was initially non-specific for both coenzymes and later became modified to accommodate NADP+ (or NADPH) as an allosteric activator. The enzymes are extremely heat labile. They denature rapidly above 37°. The activators and inhibitors fail to stabilize the proteins against heat denaturation. A novel effect of pH influence on the degree of activation and inhibition was observed. The enzymes are activated and inhibited best at the pH minima and least of all at the optimum pH. The relevance of these pH effects to the mitochondrial location of the enzymes is discussed.

In the organized attack on the rheumatic infection there is probably no more debated point than that of the efficacy of tonsillectomy. As portals of entry of the virus the tonsils are supposed to occupy first place, and hence it is only natural that one of the commonest procedures in the attempt not only to prevent the disease but also to hinder its progress, should consist intheirremoval. It must be admitted, however, that so far as the latter purpose is concerned the operation savours of locking the stable after the steed has been stolen. Statistics vary regarding the incidence of disease of the tonsils in examples of the rheumatic infection, but there is no doubt that in a goodly proportion of the patients abnormal tonsillar tissue is present and that a history of a previous tonsillitis is obtained. In a recent survey in London' the incidence of diseased tonsils in rheumatic children was said to be roughly 60 per cent. as against 50 per cent. in non-rheumatic children, whereas in a simultaneous enquiry carried out in Glasgow only 45 per cent. of the rheumatic and 40 per cent. of the non-rheumatic presented tonsillar abnormality. Disease of the tonsils is thus so widespread, not only among the non-rheumatic members of the class of society which provides the majority of our examples of rheumatism, but as we all know among the children of the better classes as well, in whom on the other hand, rheumatic fever is admittedly rare, that it is exceedingly difficult to assess the importance of this condition in the pathogenesis of the infection. Nevertheless it seems rational to remove a possible focus of infection and portal of entry, apart altogether from the effect of the operation on the general health, and it has been our custom to have the tonsils enucleated in all examples of the disease when there was any question of enlargement. The present communication is an analysis of our results in an attempt to appraise the value of this line of attack.

The chief determining factor in spontaneous self-fertilization in white sweet clover (Melilotus alba) appears to be the distribution of pollen within the unopened flowers. This in turn depends on (1) length of stamens, (2) length of style, (3) amount of pollen, and (4) size of cavity within the upper part of the keel. When the flower structure and quantity of pollen is such as to insure the deposition of pollen grains on the stigma before the blossom is likely to be disturbed by insects, the plant will be normally self-fertilized. In the yellow flowered species of sweet clover (Melilotus officinalis) spontaneous self-fertilization is effectively prevented, except in certain varieties, by a characteristic of the stigma which makes it unreceptive. Scarification of the stigmatic surface appears to be necessary before fertilization can take place. Variation occurs also, as in M. alba, in the length of stamens and style, size of keel cavity, and the amount of pollen.There is a high correlation in M. alba between the percentage of flowers which are naturally self-pollinated and the percentage of flowers which produce pods when the plants are caged to exclude insects. Selection of plants which are normally self-fertilized can be made by examining the early flowers, thus obviating the necessity of bagging or caging plants which do not possess this character.A strain of M. alba which is normally self-fertilized was found to produce almost twice as much seed as another strain which is normally cross-pollinated under comparable conditions in the field.

Measurements have been made of the lowering of the conductance of hexadecyl trimethyl ammonium bromide and sodium dodecyl sulphate solutions on addition of hydrocarbons of various types. Explanations are advanced for these decreases and for the difference in behaviour observed between aromatic and non-aromatic hydrocarbons.

A second-born twin with intra-utenine gangrene of the right lower limb secondary to a dissecting intramural hematoma of the femoral artery is reported. Although trauma seems most likely, the exact mechanism of intramural hemorrhage with compression and obliteration of the lumen of the vessel remains unknown.

A novel form of allosteric control in which NAD-specific glutamic dehydrogenases obtained from taxonomically related fungi are activated by NADP+, NADPH, and P-enolpyruvate has been elucidated. Citrate and isocitrate are equally effective as inhibitors of the enzymes. The enzymes are allosterically inhibited by their substrates, α-ketoglutarate and ammonia, in a highly cooperative manner. NADP+, NADPH, and P-enolpyruvate antagonize substrate inhibition. These activators also function as multivalent modulators in releasing the enzyme from inhibition by citrate. Control of the enzyme activity is unidirectionally oriented such that it is the reductive amination that is effectively controlled. The purified glutamic dehydrogenases have a molecular weight of 225,000 daltons. They are susceptible to inactivation by hydrodynamic shear in sucrose density gradients at alkaline pH levels. Inactivation by sedimentation can be prevented by bound activators. Inactivation and dissociation of the enzyme are related phenomena. Synthesis of the glutamic dehydrogenases can be repressed by addition of glucose to the growth medium. Glutamate acts as an inducer. NADP-specific isocitric dehydrogenase present in these fungi responds in the opposite manner to the metabolism of glucose and glutamate.

The effective delayed-neutron fractions of 235U and 239Pu have been determined for two fast critical assemblies from measurements of the absolute fission rate and the apparent reactivity worths of ...

It is widely accepted that human thyrotropin causes lipolysis in fat cells isolated from a variety of sources. An investigation into the use of this lipolytic activity as a means of tracing thyrotropin through a fractionation procedure revealed that the biological and lipolytic activities of this hormone are separable and are probably, therefore, caused by two different entities. It is obvious that the measurement of lipolysis is an unsuitable assay for thyrotropin. It was shown that this lipotropic compound is antigenic and likely also to interfere with the accuracy of a radio-immunoassay for thyrotropin.

An analysis has been made of the bubble and crystal structure and of the isotopic composition of a hailstone from a severe storm which occurred near Cardiff on 1 July 1968. A trajectory for the stone has been deduced from the isotopic data which is consistent with its crystal and bubble structures. Updraught profiles have been calculated also and are in reasonable agreement with those inferred from the extended parcel theory.

The use of a mixture of 2 mg phenoperidine and 5 mg droperidol as an adjunct to topical anaesthesia for bronchography, with or without prior bronchoscopy, is reported in 100 adult patients. Given slowly over 2 to 10 minutes this produces good operating conditions in the majority of patients. However, if parenteral pethidine or diazepam are used as premedication, patients may be too drowsy to co-operate with changes in posture. In the absence of excessive sedation respiratory depression will respond to the simple expedient of asking the patient to breathe. It is recommended that atropine alone be given as premedication, perhaps with oral diazepam in apprehensive patients. Despite the good operating conditions most patients remembered the procedure and half of them found it to be unpleasant.

Cet article résume les essais de théorisation qui ont cherché à expliquer l'instabilité politique dans les nouvelles nations par des facteurs de pluralisme culturel et de modernisation. Il met ces explications à l'épreuve de données quantitatives portant sur trente pays d'Afrique, situés au sud du Sahara. Le problème théorique est posé à savoir si oui ou non un degré élevé de pluralisme culturel et de modernisation rend compte des différents types d'instabilité politique. On se demande aussi si l'interaction entre le pluralisme culturel et la modernisation rend compte de ces différences. L'analyse empirique comprend la classification des diverses unités culturelles dans les pays d'Afrique, la mesure des taux de changement dans de nombreux indices de modernisation, et la recension des cas de violence politique où des élites opposées et des groupes locaux ont été impliqués. A l'examen des résultats positifs et convergents qui sont atteints par voie d'une opérationnalisation diverse des trois concepts centraux, on arrive à la conclusion que la variation dans le pluralisme culturel est une source importante d'instabilité politique dans les pays d'Afrique, et que la modernisation de ces pays, contrairement à une opinion répandue, a des effets restrictifs sur la probabilité que l'instabilité politique se produise.

Guanylates (GTP, GDP, and GMP), short chain acyl-CoA derivatives; ATP, and ADP, were found to be allosteric activators of NAD-specific glutamic dehydrogenases isolated from a unique group of fungi, the Oomycetes. Long chain acyl-CoA derivatives and AMP were very strong inhibitors of the enzyme. Pythium glutamic dehydrogenase, in particular, was shown to be sensitive to control by energy charge. A total of five activators have now been discovered. These are NADP+, P-enolpyruvate, short chain acyl-CoA derivatives, GTP, and ATP. These activators functioned cumulatively to antagonize the effects of the inhibitors, citrate, AMP, and long chain acyl-CoA derivatives. The activators acted as unidirectional stimulants of the biosynthetic reaction, while some of them inhibited the catabolic reaction unidirectionally. These glutamic dehydrogenases are genetically controlled. They are subjected to marked catabolic repression and inducible by glutamate. The substrates (ammonia and α-ketoglutarate) of the biosynthetic reaction are allosteric inhibitors. The activators modulated the enzyme against allosteric inhibition by its substrates. This multivalent control has been explained as a mechanism by which the enzyme effects its biosynthetic and cataboilc roles in amphibolic reactions of the citric acid cycle. A remarkable correlation has been made between lysine biosynthesis and allosteric control mechanisms among members of the Phycomycetes. The distribution of the two pathways of lysine biosynthesis among these simple fungi parallels the only two different forms of allosteric controls of NAD-specific glutamic dehydrogenases elucidated for all major orders of the Phycomycetes studied to date.

Seven factors have been described which seem to influence the tendency of sweet clover plants to produce seed by spontaneous self-fertilization. These are: length of stamens; stage of flower development when pollen is liberated from the pollen sacs; distribution of free pollen within the flower; size of cavity in the upper part of the keel; amount of pollen; condition of the pollen; and receptivity of the stigma.Spontaneous self-fertilization is the normal condition in certain plants of white blossom sweet clover, i.e., M. alba. This was not found to occur in any variety of yellow blossom sweet clover with the exception of "Redfield Yellow". True breeding lines of M. alba have been isolated consisting of naturally self-fertilized plants and other lines also which will not produce seed unless the flowers are manipulated. M. alba consists of a mixture of normally self-fertilized plants and plants that are random pollinated. This is especially true of certain varieties such as "Arctic". In some plants of M. alba an abundance of germinating pollen grains were found adhering to the stigmas before the flowers opened, thus precluding the possibility of natural crossing. Practically 100% of the flowers on such a plant produced selfed seed. The character of spontaneous self-fertilization exhibited clear cut segregation in a selfed line of M. alba. The importance of this character in relation to breeding improved varieties and pure seed production is emphasized.The efficiency of the "suction" method of emasculating sweet clover flowers depends on the peculiarities of the latter. This method is quite reliable with many plants but very unsatisfactory with others, depending upon the particular type of flower structure and behavior.

The results of an analysis of the chemical composition of precipitation and air over the British Isles and Eire are presented. Tables are given showing the median concentrations of S, Cl, Na, K, Ca and nitrogen in ammonia and nitrate, and maps are presented to indicate the variations in sources for different chemicals. The errors in the sampling technique are discussed.

study of the scope and content of consumer education in high-school courses in home economics. For this purpose recent courses of study issued by eight states (Alabama, Arizona, Indiana, Missouri, Montana, Ohio, Texas, and West Virginia) and four textbooks were analyzed. The courses of study were chosen from different areas of the United States, and the number was determined by the law of diminishing