Influence of oxytocin on human memory processes: Validation by a control study

An earlier report (1) of an adverse effect of high doses of oxytocin on human memory included results of studies on women receiving oxytocin as part of the treatment to induce 2nd trimester therapeutic abortion. These women served as their own controls. We have now been able to study a group of women who have been treated in all ways like the original group, with the exception that they did not receive oxytocin. The results from this external control corroborate the finding that oxytocin affected memory.     

Immobilisation stress-induced anorexia is not due to gastric ulceration

The relationship between the anorexia following immobilisation and the associated gastric pathology in male and female rats was investigated. Male rats were injected with saline or the histamine-H2. antagonist, ranitidine, which inhibits gastric acid secretion but does not readily enter the brain. Thirty minutes later, the animals were immobilised for 2 hours. Ranitidine pretreatment reduced the number of gastric lesions but had no effect on the degree of stress-induced anorexia. The number of gastric lesions did not correlate significantly with the degree of anorexia or weight loss. Previous studies have reported that female rats (unlike males) exhibit anorexia after repeated daily immobilisations and have greater gastric pathology following stress. Therefore, in a second experiment, female rats were pretreated with saline or ranitidine and immobilised for 2 hours/day for 4 days. The drug did not decrease the number of lesions observed after this treatment. However, as in the first experiment, the number of lesions did not correlate significantly with anorexia or weight loss. It is therefore unlikely that immobilisation stress-induced anorexia in either male or female rats is merely a consequence of gastric ulceration.     

Amino Acid Analysis Demonstrates that Increased Plasma Free Tryptophan Causes the Increase of Brain Tryptophan During Exercise in the Rat

Rats were trained to run on a horizontal treadmill for 2 h at 20 m/min. This activity considerably increased plasma free tryptophan (TRP) (+70%) but did not alter plasma total TRP levels and had little or no effect on plasma concentrations of the other large neutral amino acids (LNAAs) that compete with TRP for entry into the brain. Brain TRP levels increased by 80%. The only other brain LNAA to be affected by exercise was threonine, which rose moderately. The results indicate that increased plasma free TRP was specifically responsible for the increase of brain TRP after 2 h of exercise. Brain lysine was also increased whereas glycine, alanine, and gamma-aminobutyric acid were decreased. The differences between the present findings and those previously obtained following 2 h immobilization stress are discussed.     

Isolation and characterization of a large,neurite-associated glycoconjugate from neuroblastoma cells

A high molecular weight glycoconjugate has been isolated from neurite-producing neuronal tumor cells in culture and has been designated as I(0) based on its elution characteristics in gel filtration chromatography. This molecule cannot be found in a variety of nonneuronal cells. I(0) is found in the substratum-attached material or cell fraction of neurite-producing neuroblastoma cells, depending upon culture conditions. It is found in the substratum-bound fraction of B104 rat neuroblastoma cells during serum starvation and in the EGTA-detached cell fraction of B104 cells grown in chemically defined N2 medium. It occurs only in the cell fraction of the human neuroblastoma line Platt. Examination of behavioral variants of the B104 rat line further strengthens the association of I(0) with neurite production; the constitutive neurite-producing E(R)B9 variant contains I(0) while the non-neurite-producing E(R)A11 variant does not. I(0) is large, eluting in the void volume of sepharose-CL2B columns. Radioiodination of intact cells with lactoperoxidase shows I(0) to be a cell surface component. Metabolic radiolabeling studies show that it contains a high proportion of polysaccharide to protein, does not contain mannose, and is unsulfated. Alkaline borohydride reduction release two size classes of large polysaccharide chain. The alkaline reduction results, along with the mannose incorporation studies, show the presence of O-glycosidic linkages and few, if any, N-linkages. Resistance to nitrous acid deamination, insensitivity to glycosaminoglycan lyases, and the absence of sulfation, indicate that I(0) does not contain the glycosaminoglycans hyaluronic acid, chondroitin-, dermatan-, or heparin- sulfates. Affinity column chromatography reveals high binding affinity of I(0) to polyornithine and no binding to gelatin (collagen) or the glycosaminoglycans hyaluronate and heparin. These studies describe a unique high molecular weight glycoconjugate on the surface of neurite-producing neuroblastoma cell lines from two species.     

Relative apparent synapomorphy analysis (RASA). I: The statistical measurement of phylogenetic signal

We have developed a new approach to the measurement of phylogenetic signal in character state matrices called relative apparent synapomorphy analysis (RASA). RASA provides a deterministic, statistical measure of natural cladistic hierarchy (phylogenetic signal) in character state matrices. The method works by determining whether a measure of the rate of increase of cladistic similarity among pairs of taxa as a function of phenetic similarity is greater than a null equiprobable rate of increase. Our investigation of the utility and limitations of RASA using simulated and bacteriophage T7 data sets indicates that the method has numerous advantages over existing measures of signal. A first advantage is computational efficiency. A second advantage is that RASA employs known methods of statistical inference, providing measurable sensitivity and power. The performance of RASA is examined under various conditions of branching evolution as the number of characters, character states per character, and mutations per branch length are varied. RASA appears to provide an unbiased and reliable measure of phylogenetic signal, and the general approach promises to be useful in the development of new techniques that should increase the rigor and reliability of phylogenetic estimates.      

Molecular evolution of voltage-sensitive ion channel genes: on the origins of electrical excitability

We have analyzed nucleic acid and amino acid sequence alignments of a variety of voltage-sensitive ion channels, using several methods for phylogenetic tree reconstruction. Ancient duplications within this family gave rise to three distantly related groups, one consisting of the Na+ and Ca++ channels, another the K+ channels, and a third including the cyclic nucleotide-binding channels. A series of gene duplications produced at least seven mammalian homologues of the Drosophila Shaker K+ channel; clones of only three of these genes are available from all three mammalian species examined (mouse, rat, and human), pointing to specific genes that have yet to be recovered in one or another of these species. The Shaw-related K+ channels and the Na+ channel family have also undergone considerable expansion in mammals, relative to flies. These expansions presumably reflect the needs of the high degree of physiological and neuronal complexity of mammals. Analysis of the separate domains of the four-domain channels (Ca++ and Na+) supports their having evolved by two sequential gene duplications and implies the historical existence of a functional two-domain channel.      

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Pokeweed mitogen inhibition of protein synthesis in cultured lymphoblastoid lines

Summary Pokeweed mitogen (PWM) and ricin are both lectins derived from plant seeds. They are glycoproteins and share the ability to agglutinate a variety of animal cells including erythrocytes. The effect of these two lectins on protein synthesis was studied in four longterm lymphoblastoid lines (8866 and GM1531, which are B cell lines; and CCRF/CEM and MOLT 4, which are T-cell lines). Ricin (50 μg/ml) completely inhibited protein synthesis by 2 hr in both B-cell and T-cell lines as measured by the uptake to [³H]leucine. The PWM appeared more specific and at a concentration of 500 μg/ml inhibited protein synthesis only in B-cell lines (8866 and GM 1531). This effect was maximal at 5 hr. To investigate the reason for the differential effect of PWM on T and B cells,¹²⁵I-labeled PWM was incubated with 8866, MOLT 4, and CCRF/CEM to see if a significant difference in binding to B cells and T cells could be demonstrated. It does not appear that the differential effect on T and B cells is due to a difference in the amount of PWM bound. On the other hand it is possible that the B cells may bind some toxic subcomponent of the PWM preparation that the T cells do not bind because of a difference in composition or arrangement of cell surface glycoproteins.     

Oviposition and development in predaceous mites fed with artificial and natural diets (Acari: Phytoseiidae)

Oviposition rate and developmental capacity was determined for Amblyseius hibisci (Chant), A. limonicus Garman and McGregor, A. largoensis (Muma), Metaseiulus pomoides Schuster & Pritchard, M. occidentalis (Nesbitt), Typhloseiopsis arboreus (Chant), Typhodromus pyri Scheuten, Phytoseiulus persimilis Athias-Henriot, and Iphiseius degenerans (Berlese) on both artificial and natural diets. Oviposition and development occurred in seven of nine species when fed artificial diet and in all species when fed natural diets (phytophagous mites or pollen). The combined mean oviposition rate (21-d tests) for all species which oviposited on artificial diet was ca. one third the rate achieved by these species when tested on natural diets. Eggs and immature stages derived from oviposition tests with artificial diet showed no abnormalities and developmental times (egg to egg) were similar to those observed on natural diets. Predator cultures maintained on artificial diet showed gradual declines in viability within 2–3 months and only A. hibisci survived longer than 6 months. Adult predators of species which failed to oviposit when fed artificial diet survived longer than adults tested in the absence of food and water. Immature stages of these species failed to develop on artificial diet.

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Ponte et developpement d'acariens predateurs alimentes a partir d'un regime artificiel et d'un regime naturel (Acari: Phytoseiidae)

Résumé Le nombre d'ufs pondus par 7 espèces de Phytoseiidae nourries sur milieu artificiel a varié de 0,1 à 1,2 uf/femelle/jour. Pour l'ensemble des espèces, le nombre moyen d'ufs pondus a été de 0,5 uf/femelle/jour pour une période de ponte moyenne de 18,5 jours.Deux espèces, Phytoseiulus persimilis et Metaseiulus occidentalis nourries sur milieu artificiel, n'ont pas pondu; leurs longévités moyennes ont été respectivement de 11,3 et de 10,3 jours.Avec un régime naturel (acariens phytophages ou pollen), le nombre d'ufs pondus, pour 9 espèces de Phytoseiidae a varié de 0,8 à 3,2 ufs/femelle/jour. Pour l'ensemble des espèces, le nombre moyen d'ufs pondus a été de 1,7 uf/femelle/jour pour une durée moyenne de la période de ponte de 19,0 jours.La viabilité des ufs provenant des expériences de ponte avec régime artificiel était elevée chez toutes les espèces prédatrices et les durées du développement sur milieu artificiel étaient semblables à celles observées avec régime naturel. La viabilité des élevages de prédateurs maintenus sur milieu artificiel a diminué progressivement et la plupart des élevages avaient disparu en moins de 6 mois. Les tentatives d'élevage de P. persimilis et M. occidentalis sur milieu artificiel ont été négatives bien que les prédateurs adultes femelles aient eu une plus grande longévité sur milieu artificiel qu'en absence de nourriture et d'eau.