Relationships among New World species of Hibiscus section furcaria (Malvaceae)

Seventeen species ofHibiscus sectionFurcaria are native to the New World, of which 12 (one diploid, nine tetraploids, one octoploid and one decaploid) have been studied cytotaxonomically. New chromosome counts (2n=4x=72) are reported forH. cucurbitaceus, H. flagelliformis, H. kitaibelifolius, andH. laxiflorus. Seventeen types of tetraploid interspecific hybrids (seven new to this study) all showed complete meiotic chromosome homology (genome formulaGGPP) and normal floral development. That all hybrids were nevertheless almost completely sterile suggests a cytoplasmic component to the genetic differentiation of the species. The diversification of the tetraploid species in habits, habitats and geographical ranges is considerable, despite their similar genome constitutions. A key to 17 native and four introduced African species is presented.Hibiscus cerradoensis sp. nov. is described.     

Multiple Molecular Forms of Enkephalins in the Guinea Pig Hippocampus

Abstract: The combined techniques of HPLC and radioimmunoassay were used to identify and quantitate enkephalin-related peptides in the guinea pig hippocampus. Both met- and leu-enkephalin were identified, in approximately a 2:1 ratio, as well as a third enkephalin-like molecule that is neither met- nor leu-enkephalin. The third enkephalin elutes earlier than met- or leu-enkephalin from a reversed-phase column, has a molecular weight similar to the other enkephalins, and is as active as these enkephalins are in inhibiting binding of labeled opiates to rat brain membranes. All regions of the hippocampus (dentate gyrus, CA1–2, CA3–4, and subiculum) contain all three immunoreactive peptides. Immunocytochemical techniques, using antisera raised against met-enkephalin, show with one antiserum immunoreactivity in the granule cell-mossy fiber system, and with the other scattered immunoreactive cells mostly in the CA2 region. Enkephalins are not confined to the mossy fiber system, as previously suggested, but may be a component of another hippocampal innervation.     

Hypoxanthine: Guanine phosphoribosyltransferase mutants in Saccharomyces cerevisiae

Summary Yeast mutants lacking activity of the enzyme hypoxanthine: guanine phosphoribosyltransferase (H:GPRT) have been isolated by selecting for resistance to 8-azaguanine in a strain carrying the wild type allele, ade4 ⁺ of the gene coding for amidophosphoribosyltransferase (PRPPAT), the first enzyme of de novo purine synthesis. The mutants excrete purines and are cross-resistant to 8-azaadenine. They are recessive and represent a single complementation group, designated hpt1. Ade4-su, a prototrophic allele of ade4 with reduced activity of PRPPAT, is epistatic to hpt1, suppressing purine excretion and resistance to azaadenine but not resistance to azaguanine. The genotype ade2 hpt1 does not respond to hypoxanthine. Hpt1 complements and is not closely linked to the purine excreting mutants pur1 to pur5. Hpt1 and pur6, a regulatory mutant of PRPPAT, are also unlinked but do not complement, suggesting a protein-protein interaction between H:G-PRT and PRPPAT. Mycophenolic acid (MPA), an inhibitor of de novo guanine nucleotide synthesis, inhibits the growth of hpt1 and hpt1 ⁺. Xanthine allows both genotypes to grow in the presence of MPA whereas guanine only allows growth of hpt1 ⁺. Activity of A-PRT, X-PRT and H:G-PRT is present in hpt ⁺. Hpt1 lacks activity of H:G-PRT but has normal A-PRT and X-PRT.     

An aphasic syndrome in children

The paper presents case reports of nine children, all of whom had severe disturbances of language function of abrupt or gradual onset. Seizures occurred in seven of the children and all nine had EEG abnormalities.There was no apparent correlation between the seizures, the EEG changes and the aphasia. One patient had a brain biopsy performed at another hospital and the tissue was said to be normal. The cause of the abnormal language function is unknown. Five of the children failed to acquire normal speech subsequently. Three of the four children who made a complete recovery were treated with steroids.     

Location of phosphorylase kinase (Phk) in the mouse X chromosome

The phosphorylase kinase deficiency (Phk) locus has been located in the mouse X chromosome, the order of genes being centromere-Bn-Phk-Ta-jp. Since the Phk locus of the mouse may be identical to the locus responsible for the X-linked phosphorylase kinase deficiency trait of man, and there may be a high degree of gene-order homology in the X chromosome of all mammals, the location of Phk in the mouse reported here may aid in locating the phosphorylase kinase gene on the X chromosome of man.This research was supported by grants AM 13359 (to F.H.) and AM 14461 (to D.L.C.) from the National Institute of Arthritis and Metabolic Diseases, and by an allocation (to E.M.E.) from NIH General Research Support Grant RR-05545 from the Division of Research Resources to The Jackson Laboratory. F.H. is a recipient of a Research Career Development Award (AM 46 421) of the National Institute of Arthritis and Metabolic Diseases.     

Xylene Poisoning: A Report on One Fatal Case and Two Cases of Recovery after Prolonged Unconsciousness

Three cases of xylene poisoning occurred after prolonged inhalation of paint fumes. Analysis showed that xylene comprised more than 90% of the solvent in the paint, the total solvent comprising 34% of the paint by weight. One patient was dead on admission, while the other two recovered after at least 15 hours'' loss of consciousness. Both patients had transient liver cell damage, and one temporary impairment of renal function.     

Space biomagnetics

Astronauts who venture from their spacecraft onto the lunar surface and the surfaces of our neighboring planets will be exposed for a few hours in duration to magnetic-field intensities which are markedly less than that of the earth's field. The intensities of magnetic fields to which they will be exposed while inside their spacecraft can be stated only after completing a detailed survey of the contribution made to these fields by the functioning electronic components of spacecraft. Assessment of individuals regularly working in and exposed continuously for 10 days to magnetic fields less than 100 gammas in intensity indicate that extremely low-intensity magnetic fields encountered during a nominal Apollo moon mission should not affect astronaut health or performance. Careful physiological and psychological observations first on higher primates, then on man exposed to such fields for more prolonged periods of time must be carried out before this conclusion can be drawn for longer exposures.Recent technological advances in propulsion and radiation protection have made it possible that astronauts might also be exposed intermittently to high-intensity, relatively low-gradient magnetic fields during space missions. The duration of such exposures could range from less than an hour if an activated magnetohydrodynamic engine must be serviced, to several days if pure magnetic or plasma-radiation shielding is used for astronaut protection from solar flare radiation. From past experience with personnel who enter high-intensity magnetic fields for brief periods of time in their work, magnetic-field exposures while servicing magnetohydrodynamic engines should not be hazardous to astronauts. On the other hand, past exposures of man and sub-human systems to high-intensity magnetic fields do not indicate whether or not astronauts who are exposed for up to several days to currently estimated magnetic-field intensities associated with pure magnetic or plasma-radiation shielding could suffer impairment of their health or performance. This answer can be obtained only by carefully conducted experiments which closely simulate such exposures, and look closely for physiological, psychological and pathological changes, especially in exposed higher primates, before assessing the response of man to such exposures.Magnetic force is animate or imitates life; and in many things surpasses human life, while this is bound up in the organick body.Prepared under Contract NASr-115 at The Lovelace Foundation for Medical Education and Research, Albuquerque, N.M., U.S.A.