Pathogenesis of hemosiderosis in lemurs: Role of dietary iron,tannin, and ascorbic acid

Clinical disease associated with excess iron deposition (hemosiderosis) in the duodenum, liver, and spleen occurs in captive lemurs. In this report we review the occurrence of hemosiderosis and related disease in the Zoological Society of San Diego lemur collection; we then define and describe potential pathogenic factors with the goal of establishing rational husbandry methods to limit or prevent the disease. At the San Diego Zoo, all 49 lemurs necropsied since 1968 were hemosiderotic, the severity increasing with increasing age; liver and kidney disease were common. Our review of iron metabolism, current knowledge on the pathogenesis of hemosiderosis in humans, and the diets of captive and wild lemurs reveals several key dietary substances that may contribute to lemur hemosiderosis: iron, tannins, and ascorbic acid. In captivity, excess dietary iron (commercial monkey chow) and high levels of ascorbic acid (citrus fruits) lead to enhanced iron uptake and increased toxicity of stored iron due to free radical formation. In the wild, lemurs have an unusual preference for leaves, fruits, and bark high in tannin, a polyphenolic secondary plant compound that rapidly chelates iron, protein, and minerals in the gastrointestinal (GI) tract, preventing their absorption. These findings suggest that hemosiderosis in captive lemurs results from a diet high in iron, high in ascorbic acid, and lacking in tannin. Immediate correction of captive diets may limit hemosiderosis in lemurs in the future.     

Ortholinea alata n. sp. (Myxosporea: Ortholineidae) in the northern butterfly fish Chaetodon rainfordi

Ortholinea alata n. sp. is described from the northern butterfly fish, Chaetodon rainfordi collected at Heron Island, Great Barrier Reef, Australia. Spherical, disporous trophozoites (10-15 micrometers) and spores were observed in the lumina of kidney tubules and collecting ducts. Spores are broadly triangular with two short, broad processes that extend dorsoventrad from the posterior end of each of the two spore valves. Valves are bisected by a suture in the plane of the polar capsules. Spores are 12.6 micrometers (length) x 9.6 micrometers (width) x 9.9 micrometers (length), and at the anterior end contain two spherical, divergent polar capsules measuring 4.6 (4.1-5.1) micrometers. Sporogenesis is similar to that of renal Sphaerospora spp.; the intraluminal trophozoites of O. alata n. sp. correspond to pseudoplasmodia described for Sphaerospora spp. and no large, multinucleated plasmodia are formed. No significant histopathological changes were observed in the kidneys of infected fish.     

Multiple T and B cell epitopes in the S1 subunit ("A"-monomer) of the pertussis toxin molecule

The immunogenicity and reactogenicity of Bordetella pertussis vaccine are mediated in part by the S1 subunit of pertussis toxin (PT). To identify the immune epitopes in the S1 subunit of PT, synthetic peptides were prepared and tested for their capacity to induce antibodies in mice with different MHC genotypes. In BALB/c mice, peptides corresponding to sequences 1-17, 70-82 and 189-199 generate T cell proliferative responses, induce the production of antibodies capable of neutralization of the toxin in the Chinese hamster ovary-cell assay, and protect mice from a shock-like syndrome caused by alternate injections of BSA and PT. Protection and neutralization correlated with the ability of these peptides to elicit high anti-PT titers. Different B cell epitopes were detected in other inbred mouse strains. The antibody reactivity against synthetic peptides from two infants vaccinated with pertussis vaccine was tested. These infants had antibodies reactive to a variety of epitopes in the S1 subunit, including peptides 1-17, 70-82, 99-112, 135-145, and 189-199. Thus, it appears that there are multiple T and B cell epitopes in the S1 subunit of PT.     

Comparison of [125I]Iodolysergic Acid Diethylamide Binding in Human Frontal Cortex and Platelet Tissue

The human platelet contains a functional 5-hydroxytryptamine (5-HT) receptor that appears to resemble the 5-HT2 subtype. In this study, we have used the iodinated derivative [125I]iodolysergic acid diethylamide ([125I]iodoLSD) in an attempt to label 5-HT receptors in human platelet and frontal cortex membranes under identical assay conditions to compare the sites labelled in these two tissues. In human frontal cortex, [125I]iodoLSD labelled a single high-affinity site (KD = 0.35 +/- 0.02 nM). Displacement of specific [125I]iodoLSD binding indicated a typical 5-HT2 receptor inhibition profile, which demonstrated a significant linear correlation (r = 0.97, p less than 0.001, n = 17) with that observed using [3H]ketanserin. However, [125I]iodoLSD (Bmax = 136 +/- 7 fmol/mg of protein) labelled significantly fewer sites than [3H]ketanserin (Bmax = 258 +/- 19 fmol/mg of protein) (p less than 0.001, n = 6). In human platelet membranes, [125I]iodoLSD labelled a single site with affinity (KD = 0.37 +/- 0.03 nM) similar to that in frontal cortex. The inhibition profile in the platelet showed significant correlation with that in frontal cortex (r = 0.96, p less than 0.001, n = 16). We conclude that the site labelled by [125I]iodoLSD in human platelet membranes is biochemically similar to that in frontal cortex and most closely resembles the 5-HT2 receptor subtype, although the discrepancy in binding capacities of [125I]iodoLSD and [3H]ketanserin raises a question about the absolute nature of this receptor.     

Ineffectiveness of ethylene biosynthetic and action inhibitors in phenotypically reverting theEpinastic mutant of Tomato (Lycopersicon esculentum mill.)

Five-day-old, dark-grown seedlings of theEpinastic (Epi) tomato mutant (Lycopersicon esculentum Mill.) and its parent, cultivar VFN8, were used as a system for assessing the role of ethylene in theEpi phenotype. The distinguishing features ofEpi seedlings are an increase in hypocotyl diameter and reduced hypocotyl length. Treatment of VFN8 seedlings with 0.5 l/liter ethylene closely mimicked theEpi phenotype. The rate of ethylene production by 5-day-old, dark-grownEpi seedlings was double that of VFN8 seedlings. Nevertheless, treatment ofEpi seedlings with inhibitors of ethylene biosynthesis (aminoethoxyvinylglycine or Co²⁺) or ethylene action (silver thiosulfate or norbornadiene) failed to normalize theEpi phenotype.Epi seedlings grown in sealed jars containing ethylene and CO₂ adsorbants also expressed the characteristicEpi phenotype. The results indicate that the physiological lesion resulting from theEpi gene mutation is not simply an overproduction of ethylene.     

Localization of the membrane-associated CTP:phosphocholine cytidylyltransferase in Chinese hamster ovary cells with an altered membrane composition

The subcellular localization of the membrane-associated CTP:phosphocholine cytidylyltransferase was determined in Chinese hamster ovary cells in which the phospholipid composition had been altered by growth in the presence of N-methylethanolamine or treatment with phospholipase C. Cell homogenates were fractionated on Percoll density gradients, and marker enzyme activities were used to determine the location of the cellular membrane fractions. The peak of cytidylyltransferase activity occurred in the gradient at a density intermediate to that of the peaks of endoplasmic reticulum and plasma membrane markers. The profile of cytidylyltransferase activity most closely resembled that of the Golgi membrane marker; however, upon sucrose gradient centrifugation, the profile of the Golgi apparatus was very different from that of cytidylyltransferase. Differential centrifugation suggested a nuclear membrane association of the enzyme. Cytidylyltransferase was associated with a membrane fraction that sedimented when subjected to very low speed centrifugation (65 x g, 5 min). From Percoll gradient fractions, nuclei were identified by microscopy, and they migrated with cytidylyltransferase activity. The data are consistent with a localization of cytidylyltransferase in the nuclear membrane.     

Acclimation of barley to changes in light intensity: photosynthetic electron transport activity and components

Barley seedlings (Hordeum vulgare L. Boone) were grown at 20°C with 16 h/8 h light/dark cycle of either high (H) intensity (500 mole m^-2 s^-1) or low (L) intensity (55 mole m^-2 s^-1) white light. Plants were transferred from high to low (H L) and low to high (L H) light intensity at various times from 4 to 8 d after leaf emergence from the soil. Primary leaves were harvested at the beginning of the photoperiod. Thylakoid membranes were isolated from 3 cm apical segments and assayed for photosynthetic electron transport, Photosystem II (PS II) atrazine-binding sites (Q_B), cytochrome f(Cytf) and the P-700 reaction center of Photosystem I (PS I). Whole chain, PS I and PS II electron transport activities were higher in H than in L controls. Q_B and Cytf were elevated in H plants compared with L plants. The acclimation of H L plants to low light occurred slowly over a period of 7 days and resulted in decreased whole chain and PS II electron transport with variable effects on PS I activity. The decrease in electron transport of H L plants was associated with a decrease in both Q_B and Cytf. In L H plants, acclimation to high light occurred slowly over a period of 7 days with increased whole chain, PS I and PS II activities. The increase in L H electron transport was associated with increased levels of Q_B and Cytf. In contrast to the light intensity effects on Q_B levels, the P-700 content was similar in both control and transferred plants. Therefore, PS II/PS I ratios were dependent on light environment.Abbreviations Asc ascorbate - BQ 2,5-dimethyl-p-benzoquinone - DBMIB 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone - DCIP 2,6-dichlorophenolindophenol - H control plants grown under high light intensity - H L plants transferred from high to low light intensity - L low control plants grown under low light intensity - L H plants transferred from low to high light intensity - MV methyl viologen - P-700 photoreaction center of Photosystem I - Q_B atrazine binding site - TMPD N,N,N,N-tetramethyl-p-phenylenediamine Cooperative investigations of the United States Department of Agriculture, Agricultural Research Service, and the North Carolina Agricultural Research Service, Raleigh, NC. Paper No. 11990 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7643, USA.     

Respiration and germination rates of tomato seeds at suboptimal temperatures and reduced water potentials

Suboptimal temperature (T) affects germination rates (reciprocalof time to radicle emergence) on a thermal time basis; thatis, the T in excess of a base or minimum temperature multipliedby the time to a given per cent germination [t_g) is a constant.Respiration rates are also sensitive to T, and proportionalrelationships are often found between respiration rates andgermination rates. Reduced water potential () delays seed germinationon a hydrotime basis (i.e. the in excess of a base water potentialmultiplied by t_g is a constant). It was tested whether respirationrates prior to radicle emergence vary in proportion to T and as expected from the thermal and hydrotime models. Respirationrates (C0₂ evolution) of cold-tolerant, rapidly germinating(PI 341988) and cold-sensitive, more slowly germinating (T5)tomato [Lycopersicon esculentum Mill.) seeds were evaluatedover a range of T and conditions. For both genotypes, respirationrates until the beginning of radicle emergence were relatedto T on a thermal time basis and increased approximately linearlywith above -2.0 MPa, consistent with the hydrotime model. Respirationrates were uniquely related to germination rates, regardlessof whether germination timing was affected by T, , or genotype.However, germination timing was unaffected when respirationrates were manipulated by varying 0₂ partial pressure. Thus,while both germination and respiration rates vary with T and consistent with thermal and hydrotime models of biologicaltime, respiration rates per se were not the limiting factorin germination timing of tomato seeds. Key words: Lycopersicon esculentum Mill., tomato, germination, respiration, temperature, water potential     

Family-friendly HIV and AIDS care the goal at Vancouver's Oak Tree Clinic.

A clinic at Vancouver''s old Shaughnessy Hospital offers specialized care for women and children infected with HIV. Drs. David Burdge and Jack Forbes, the codirectors, believe the "one-stop-shopping" for services offered by physicians, social workers, nurses, dietitians and pharmacists helps improve quality of life for families living with the consequences of HIV and AIDS. BC has the highest cumulative incidence of AIDS in the country, and demand for the clinic''s services has far exceeded expectations.     

IRE-Bubble PCR: A Rapid Method for Efficient and Representative Amplification of Human Genomic DNA Sequences from Complex Sources

A significant issue in the analysis of any genomic DNA segment is the generation of a unique set of short single-copy sequences that are representative of that region. In this report we describe a novel technique, IRE-bubble PCR, which was designed to amplify the human DNA content of somatic cell hybrids, YACs, cosmids, and λ phage and result in greater complexity and representation than standard inter-IRE, PCR. Here we demonstrate that IRE-bubble PCR is species specific and that it results in the generation of a product that is at least 10-fold more complex and representative than that produced by standard inter-IRE PCR. In addition, we have addressed the factors that contribute to the representation of the IRE-bubble PCR product and show how they may be used to further increase the complexity of this reaction. Finally, we have illustrated how the complexity and distribution of products generated by IRE-bubble PCR can be exploited and applied to FISH mapping and "chromosome painting" as well as to the generation of STSs targeted to specific chromosomal or subchromosomal regions.