Lithium Effects on Inositol Phospholipids and Inositol Phosphates: Evaluation of an In Vivo Model for Assessing Polyphosphoinositide Turnover in Brain

Administration of lithium chloride to rats injected intracerebrally with [3H]inositol led to time- and dose-dependent increases in levels of labeled inositol monophosphates in brain. Quantitative analysis of the inositol phosphates by ion chromatography revealed 37- and 20-fold increases in the mass of myo-inositol 1-phosphate and 4-phosphate, respectively, at 4 h intraperitoneal after injections of 6 mEq/kg of lithium chloride. Albeit to a much lesser extent, lithium administration also resulted in an increase in the level of myo-inositol, 1,4-bisphosphate in brain. The lithium-induced increase in content of labeled inositol monophosphates was marked by a concomitant decrease in content of labeled inositol, and after injections of high doses of lithium, e.g., 10 mEq/kg, this was followed by a general decrease in labeling of the inositol phospholipids. In general, animals injected with [3H]inositol but not lithium did not reveal obvious differences in labeling of inositol monophosphates on stimulation by mecamylamine or pilocarpine. However, when animals were injected with [3H]inositol and then lithium, there were large increases in the levels of labeled inositol monophosphates on administration of these compounds. Administration of atropine to the lithium-treated mice led to a partial reduction in the amount of labeled inositol monophosphates accumulated due to the administration of lithium alone. Furthermore, atropine was able to block the pilocarpine-induced increase in level of labeled inositol monophosphates. These results demonstrate the suitable use of the radiotracer technique together with lithium administration for assessing the effects of drugs and receptor agonists on the signaling system involving polyphosphoinositide turnover in brain.     

Homozygous tyrosinase gene mutation in an American black with tyrosinase-negative (type IA) oculocutaneous albinism

We have identified a tyrosinase gene mutation in an American black with classic, tyrosinase-negative oculocutaneous albinism. This mutation results in an amino acid substitution (Cys----Arg) at codon 89 of the tyrosinase polypeptide. The proband is homozygous for the substitution, suggesting that this mutation may be frequently associated with tyrosinase-negative oculocutaneous albinism in blacks.     

Social behavior of Matschie's tree kangaroos (Dendrolagus matschiei) and its implications for captive management

Social behavior was studied in four (one male and three females) adult, captivebred Matschie's tree kangaroos (Dendrolagus matschiei) over a 124 day span in a large, naturalistic exhibit at the Woodland Park Zoological Gardens, Seattle, WA. A relatively high rate of social interaction occurred (15.2 per hour), over half of which consisted of approaches and nose contacts. The male initiated 54.1% of all social behaviors. Females tended to respond aggressively toward the male (avoid, bite, cuff, or swipe). The male initiated more affiliative behaviors and the females initiated more agonistic behaviors toward both the male and other females. A clear-cut dominance hierarchy could not be determined; reversals (i.e., cases in which the “subordinate” supplanted the “dominant”) occurred 43% of the time overall. Non-aggressive contact behavior consisted primarily of olfactory examination (nose contact). Allogrooming was extremely rare. The high level of agonism and lack of consistent association among individuals suggests that this species may be solitary in the wild. Two joeys were found dead on the floor during the course of the study, and based on previous findings, infanticide or behavioral stress was suspected to be the cause. Successful reproduction did not occur until females were isolated by removing other conspecifics from the enclosure.     

RELATIONSHIPS BETWEEN FLOODING TOLERANCE,LIFE HISTORY,AND SHORT-TERM COMPETITIVE PERFORMANCE IN THREE SPECIES OF POLYGONUM

The objective of this study was to compare the growth and short-term (single season) competitive performance of three species of Polygonum known to differ in flooding tolerance and life history. Polygonum amphibium is a perennial with low sexual reproductive effort and a relatively high degree of flooding tolerance, P. lapathifolium is an annual species with a high sexual reproductive effort and a low tolerance to flooding, and P. hydropiperoides is intermediate to the other two in terms of sexual reproductive effort and flooding tolerance. In order to determine the relative growth and competitive abilities of these species, mixtures and monocultures of plants were grown in pots and maintained under three flooding regimes: 1) flooded, 2) partially drained, and 3) well drained. Both P. hydropiperoides and P. amphibium grew best under flooded and partially drained conditions with reduced growth in the drained treatment. Polygonum lapathifolium, in contrast, grew as well in the drained treatment as in the more flooded treatments. Results from competition experiments were consistent in showing the relative competitive abilities to be P. lapathifolium > P. hydropiperoides > P. amphibium regardless of flooding regime. Thus, short-term competitive performance was found to trade off with flood tolerance rather than with sexual reproductive effort.     

Juvenile hormone esterases of Lepidoptera

Summary The juvenile hormone esterase (JHE) titer was measured during the last larval instar of 11 species of Lepidoptera (Pieris rapae, Junonia coenia, Danaus plexippus, Hemileuca nevadensis, Pectinophora gossypiella, Spodoptera exigua, Orgyia vetusta, Ephestia elutella, Galleria mellonella, Manduca sexta andEstigmene acrea). All species had a peak of JHE at or near the time of wandering. The peak activity at this time ranged from 0.8 to 388 nmoles JH III cleaved/min·ml. All species exceptJ. coenia had a second peak of JHE during the late prepupal stage. The height of the second peak ranged from 0.4 to 98.4 nmoles/min·ml. However, there was no apparent correlation between size of the first and second JHE activity peaks for the lepidopteran species examined. There was an apparent relationship between the height of the first and second JHE peaks and reports on titer of JH just prior to these peaks. These data support, with some qualifications, the extension of developmental information obtained on several well studied species to a variety of Lepidoptera.Abbreviations JH juvenile hormone - JHE juvenile hormone esierase - PTTH prothoracotropic hormone - R _o -10-3108 1-(4-ethylphenoxy)-6,7-epoxy-3-ethyl-7-methylnonane     

Evolutionary significance of the renal excretion of transferrin half-molecule fragments

It is generally thought that the duplicated structure of serum transferrin in vertebrates arose by gene duplication and fusion from a small ancestral protein. We have found that the isolated domains of transferrin are rapidly lost from the bloodstream via the kidneys. Therefore we suggest that the ancestral transferrin was not a serum protein or, alternatively, that it was not as small as the half-molecule.     

Biotransformation of aflatoxin B1 and its conjugated metabolites by rat gastrointestinal microfloras.

Rat cecal microflora from high- and low-fiber-fed animals hydrolyzed aflatoxin conjugates to metabolites indistinguishable from aflatoxin B1 and aflatoxin P1, but aflatoxicol was not a transformation product.     

Sensitivity of cultured pancreatic carcinoma cells toAcinetobacter glutaminase-asparaginase

Summary Cultured human pancreatic carcinoma cells (MIA PaCa-2) have been shown previously to be very sensitive toE. coli l-asparaginase (EC II). The present studies have demonstrated that another enzyme,Acinetobacter glutaminase-asparaginase (AGA) is much more effective in inhibiting cell growth. At the concentration of 0.0025 U/ml of AGA activity the enzyme totally inhibited cell growth, whereas the EC II with the same concentration did not show any effect. The inhibition of cell growth correlated well with inhibition of protein and glycoprotein synthesis. The addition ofl-glutamine at the concentration of 1 mM completely reversed the inhibition of protein synthesis. Similarly, the addition ofl-glutamine at the concentration of 3 mM daily on 3 successive days after adding AGA resulted in significant reversal of growth inhibition. The results of this study indicate that the action of AGA on MIA PaCa-2 is, to a great extent, exerted through itsl-glutaminase activity. This work was supported in part by USPHS Grant CA 19182. Dr. Wu is recipient of Research Career Development Award Grant CA00686 and Dr. Yunis is a Howard Hughes Investigator.