A single alpha-globin gene deletion in Australian aborigines

alpha- and beta-thalassaemias and other haemoglobinopathies have not so far been reported in Australian Aborigines. Using a DNA mapping technique, we tested groups of Aborigines for a deletion form of alpha-thalassaemia and found that there was a single alpha-globin gene deletion (-alpha/alpha alpha) in some populations. The alpha-globin gene deletion was detected in Aboriginal DNA samples collected from Kalumburu in the Kimberley region of Western Australia. It was found also in one sample from Mowanjum, near Derby in Western Australia, and in one from Mornington Island in the Gulf of Carpentaria. It was not observed in Aboriginal DNA samples from the central desert. Further analysis of the alpha-globin gene deletion revealed that it was of the 3.7 kilobase (Kb) (-alpha 3.7) type. However, the -alpha 3.7 deletion in the Aborigines is apparently different from that found in southern Papua New Guinea as it is linked to a different zeta-globin gene polymorphism. The presence of this silent alpha-thalassaemia in several populations of Aborigines may be explained in several ways. The most likely is through contact with Macassans or other voyagers from the Indonesian and Southeast Asian areas.

Platelet monoamine oxidase: specific activity and turnover number in schizophrenics and their families

Monoamine oxidase specific activities and molecular turnover numbers have been measured in families with at least two schizophrenic members. Neither measure of monoamine oxidase was different in schizophrenics compared with their first degree relatives. Molecular turnover number was remarkably similar in males and females and when the group was considered by age, diagnosis, drug status and family membership. Neither specific activity nor turnover number could be used in risk estimation for the development of schizophrenia in members of these families.

Extremely high frequencies of alpha-globin gene deletion in Madang and on Kar Kar Island, Papua New Guinea

Extremely high frequencies of the deletion form of alpha(+)-thalassemia (-alpha/), as studied by the DNA mapping technique, were found in the population of Madang, a coastal province in the north of Papua New Guinea (PNG) and in the population of Kar Kar, an island situated near Madang. Ninety-seven percent of the population tested from Madang and 89% of that from Kar Kar Island were either alpha(+)-thalassemia heterozygotes or homozygotes. By contrast, no examples of the deletion form were detected in the Eastern Highlands of PNG. The haplotype frequencies of alpha(+)-thalassemia (-alpha/) in Madang and Kar Kar Island were found to be 81.33% and 66.67%, respectively. A more detailed analysis of the gene deletion revealed that in both populations 96% were of the 4.2 kilobase (kb) type and 4% were of the 3.7-kb type. Thus, this group is the only example in which the 4.2-kb deletion is predominant over 3.7-kb defect. The presence in high frequencies of alpha(+)-thalassemia in the coastal area of Madang and on the neighboring island, where malaria has long been holoendemic or hyperendemic, and its virtual absence from the nonmalarious highlands of PNG suggest the role of malaria as the selective factor in maintaining alpha(+)-thalassemia. If this selective pressure is still operating, and since alpha(+)-thalassemia has no apparent homozygous disadvantage, the abnormal haplotype (-alpha/) will be in the process of fixation in this population.

Alpha zero- and beta zero-thalassemia in a Thai family: unusually mild homozygous beta zero-thalassemia without alpha-globin gene deletion

Alpha-globin genes were analyzed by the direct method of DNA mapping using alpha- and zeta-globin specific probes in a Thai family in which the proposita was an unusually mild beta zero-thalassemia homozygote. alpha zero-Thalassemia was found to be segregating in the family, inherited from the proposita's father by one of her younger sisters. However, alpha zero-thalassemia was not detected by this DNA mapping in the proposita. The mild homozygous beta zero-thalassemia in this family may result from interactions of a non-deletion alpha-thalassemia, a gene responsible for high proteolytic activity permitting more balanced globin-chain levels, or from an unusually active hemoglobin F production in the proposita.

Regulation of the production of granulocyte-macrophage colony-stimulating factor by macrophage-like tumour cell lines

Macrophage tumour cell lines (PU5-1.8, P388D1) produced detectable granulocyte macrophage colony-stimulating (CSF-2) activity measured using a factor-dependent cell line FDC-P1. The production of CSF-2 was enhanced by endotoxin and inhibited by serum, and correlated inversely with [3H]TdR incorporation. mRNA isolated from PU5-1.8 or P388D1 cells initiated CSF-2 production when injected into Xenopus laevis oocytes. The specific activity in this assay was unaltered in mRNA isolated from endotoxin-treated cells. The results suggest that endotoxin acts at a post-transcriptional level.

Urinary hormone levels: a population study of associations between steroid and catecholamine excretion rates

Urinary levels of steroid metabolites (17-hydroxycorticosteroids and 17-oxosteroids) were measured in 408 males at two times during the normal working day. Hormone levels are expressed both as rates of excretion and as creatinine ratios and are compared with the values for adrenaline and noradrenaline previously measured in the same samples. Strong associations are found between catecholamines and steroids. Generally the greatest correlation is with hormones of the same biochemical class, although the 17-hydroxycorticosteroid level is more strongly correlated with the adrenaline level than is the level of noradrenaline.

Platelet monoamine oxidase: specific activity and turnover number in headache

Monoamine oxidase turnover numbers (molecules of substrate converted to product per minute per active site) have been calculated for the human platelet enzyme using [3H]pargyline. Headache patients with high and low monoamine oxidase specific activities relative to controls were found to have turnover numbers very close to those for controls. This finding suggests that their specific activities vary because of differences in the concentration of active monoamine oxidase molecules, rather than differences in the ability of those enzyme molecules to catalyse the deamination reaction.

Functions of the white and topaz loci of Lucilia cuprina in the production of the eye pigment xanthommatin

The white and topaz eye color mutants of L. cuprina are defective in the production of the brown screening pigment xanthommatin. Both white and topaz mutants were found to be unable to accumulate xanthommatin precursors in the larval malpighian tubules, correlating with their reduced early pupal level of this metabolite. In addition, white mutants showed reduced rates of accumulation of kynurenine and 3-hydroxykynurenine in the adult eyes. Another mutant strain, grape, was also defective in its ability to accumulate these xanthommatin precursors in the eyes, although accumulation was normal in the larval tubules. In contrast, the topaz mutants were found to be normal in eye accumulation, although tubule accumulation was markedly abnormal. These properties of the white and topaz mutants of L. cuprina are compared with those of the white and scarlet mutants of D. melanogaster, and it seems likely that in the two species these genes are involved with the uptake or storage of xanthommatin precursors in specific tissues.

Ultrastructure of pigment granules in the eyes of adults of the ommochrome-deficient mutant yellow of the Australian sheep blowfly Lucilia cuprina

Compound eyes from adult flies of the ommochrome deficient mutant yellow of the Australian sheep blowfly, Lucilia cuprina, are processed for transmission electron microscopy using conventional methods. The ultrastructure of the pigment granules in the primary and secondary pigment cells is compared with that in corresponding cells of the wild-type strain and of yellow adults raised from larvae fed a diet supplemented with 3-hydroxykynurenine (3-HK). The pigment granules in both cell types of yellow are shown to be of the "empty" type in contrast to those in the wild-type strain. The pigment granules in eyes of yellow adults raised from larvae fed 3-HK are effectively normalized. The results are discussed in terms of previous electron microscope studies on other dipteran eye-colour mutants.

Xanthommatin biosynthesis in wild-type and mutant strains of the Australian sheep blowfly Lucilia cuprina

The synthesis of eye pigments has been studied in the seven eye color mutants of the Australian sheep blowfly, Lucilia cuprina. Six appears to be affected primarily in the synthesis of xanthommatin. In wild type, the onset of xanthommatin biosynthesis occurs midway through metamorphosis. Developmental patterns of accumulation of the xanthommatin precursors tryptophan, kynurenine, and 3-hydroxykynurenine have also been established for wild type. By determining the levels of these precursors in late pupae of the mutants, it has been shown that the mutant yellowish accumulates excess tryptophan and the mutant yellow accumulates excess kynurenine. The implications of these results--that yellowish lacks tryptophan oxygenase, thus failing to convert tryptophan to kynurenine, and that yellow lacks kynurenine hydroxylase (blockade in the conversion of kynurenine to 3-hydroxykynurenine)--have been confirmed. This has involved in vitro assays of tryphophan oxygenase and precursor feeding experiments. The precursor accumulation patterns are less clear for the other mutants.

Developmental patterns of 3-hydroxykynurenine accumulation in white and various other eye color mutants of Drosophila melanogaster

Several points of biochemical similarity between white and scarlet mutants suggest that both are defective in the transport of xanthommatin precursors. In both, accumulation of 3-hydroxykynurenine is negligible during larval life and occurs at only a slow rate during adult development. Larvae of both mutants also excrete 3H-3-hydroxykynurenine and 3H-kynurenine rapidly, which probably accounts for the normal levels of kynurenine during larval life. 3-Hydroxykynurenine levels are abnormal in all white mutants which were studied, although in two alleles which are strongly pigmented (w(sat) and w(col)) accumulation is enhanced rather than diminished. In w(a), larval accumulation is normal but accumulation during adult development is greatly diminished, suggesting that this mutation has a tissue-specific effect. Similar levels were found in zeste females. Of the 11 other eye color mutants tested, abnormal levels of 3-hydroxykynurenine were found in eight. In four of these (claret, light, lightoid, and pink), larval accumulation is negligible, suggesting that these have defects in the kynurenine transport system like scarlet and white. In three others, however (brown, karmoisin, and rosy), accumulation during larval life is enhanced. In cardinal accumulation is normal during larval life but is excessive during adult development. This evidence supports the suggestion that the cd mutation blocks the final step of xanthommatin synthesis.