Haemoglobins of the shark, Heterodontus portusjacksoni II. Amino acid sequence of the alpha-chain

The amino acid sequence of the alpha-chain of the principal haemoglobin from the shark, H. portusjacksoni has been determined. The chain has 148 residues and is acetylated at the amino terminal. The soluble peptides obtained by tryptic and chymotryptic digestion of the protein or its cyanogen bromide fragments were isolated by gel filtration, paper ionophoresis and paper chromatography. The amino acid sequences were determined by the dansyl-Edman procedure. The insoluble "core" peptide from the tryptic digestion contained 34 residues and required cleavage by several prosteases before the sequence was established. Compared with human alpha-chain there are 88 amino acid differences including the additional seven residues which appear on the amino terminal of the shark chain. There is also one deletion and one insertion. The chain contains no tryptophan but has four cysteinyl residues which is the highest number of such residues recorded for a vertebrate globin. In the alpha1beta1 contact sites there are four changes in the oxyhaemoglobin form and six deoxy form. Nine of the 16, alpha1beta1 contact sites show variation while three of the haem contact sites have changed in comparison to the residues known to be involved in these interactions in horse haemoglobin alpha-chain. Use of the sequence data to estimate a time of divergence of the shark from the main vertebrate line yielded the value of 410 +/- 46 million years. The data, in general, support the palaeontological view that bony fishes arose before the elasmobranchs.     

The relationship of education to blood pressure: findings on 40,000 employed Chicagoans

The relationship of education to both actual blood pressure and the prevalence of high blood pressure, based on a systolic pressure of 160 mm Hg or greater or a diastolic pressure of 95 mm Hg or greater, was analyzed among 27,033 men and women, white and black, age 25-44 and 45-64, from the Chicago Heart Association Detection Project in Industry. The educational status of each individual was categorized as not a high school graduate, high school graduate, some college, or college graduate. A statistically significant inverse association between education and high blood pressure was present in all groups of whites. This association could not be "accounted for" by differences in age, relative weight, and heart rate among the educational strata. Controlling for these variables did, however, lessen the association. Among black males a significant inverse association between education level and blood pressure was found for the younger group. For the older black males there was a clear inverse association although with the small numbers it did not achieve statistical significance. For black females there was no clear association.     

Chemical Ecology of the host searching behavior in an Egg Parasitoid: are Common Chemical Cues exploited to locate hosts in Taxonomically Distant Plant Species?

Parasitoids are known to exploit volatile cues emitted by plants after herbivore attack to locate their hosts. Feeding and oviposition of a polyphagous herbivore can induce the emission of odor blends that differ among distant plant species, and parasitoids have evolved an incredible ability to discriminate them and locate their hosts relying on olfactive cues. We evaluated the host searching behavior of the egg parasitoid Cosmocomoidea annulicornis (Ogloblin) (Hymenoptera: Mymaridae) in response to odors emitted by two taxonomically distant host plants, citrus and Johnson grass, after infestation by the sharpshooter Tapajosa rubromarginata (Signoret) (Hemiptera: Cicadellidae), vector of Citrus Variegated Chlorosis. Olfactory response of female parasitoids toward plants with no herbivore damage and plants with feeding damage, oviposition damage, and parasitized eggs was tested in a Y-tube olfactometer. In addition, volatiles released by the two host plant species constitutively and under herbivore attack were characterized. Females of C. annulicornis were able to detect and significantly preferred plants with host eggs, irrespectively of plant species. However, wasps were unable to discriminate between plants with healthy eggs and those with eggs previously parasitized by conspecifics. Analysis of plant volatiles induced after sharpshooter attack showed only two common volatiles between the two plant species, indole and β-caryophyllene. Our results suggest that this parasitoid wasp uses common chemical cues released by many different plants after herbivory at long range and, once on the plant, other more specific chemical cues could trigger the final decision to oviposit.

     

Modulation of gramicidin channel structure and function by the aliphatic "spacer" residues 10, 12, and 14 between the tryptophans

In the linear gramicidins, the four aromatic residues at positions 9, 11, 13, and 15 are well-known to be important for the structure and function of membrane-spanning gramicidin channels. To investigate whether the "spacer" residues between the tryptophans in gramicidin A (gA) are important for channel structure and function, D-Leu-10, -12. and -14 of gA were replaced by Ala, Val, or Ile. (For practical reasons, the Ile substitutions were introduced into the enantiomeric gramicidin A-, gA-.) Circular dichroism spectra of [D-Ala10,12,14]gA, [D-Val10,12,14]gA, or [Ile10,12,14]gA- incorporated into sodium dodecyl sulfate micelles or 1, 2-dimyristoyl-sn-glycero-3-phosphocholine vesicles differ from the spectrum of the native [D-Leu10,12,14]gA. All the analogue spectra display reduced ellipticity at both 218 and 235 nm, indicating the presence of double-stranded conformers with the Ala analogue spectra showing the largest departure from the native gA spectra. Size-exclusion chromatograms of the Val and Ile analogues show both monomer and dimer peaks, accompanied by peak broadening; the chromatograms for the Ala analogue show broad, overlapping peaks and suggest the presence of higher oligomers and/or (rapidly) interconverting conformations. All three analogues form membrane-spanning channels, with the channel-forming potency of the Ala analogue being much less than that of gA or the other analogues. In 1.0 M CsCl, the conductance of each analogue channel is approximately 25% less than that of [D-Leu10,12,14]gA channels. The lifetimes of the analogue channels also are less than of [D-Leu10,12, 14]gA channels, with the largest (8-fold) reduction being for [D-Ala10,12,14]gA channels. Hybrid channel experiments show that the beta6.3-helical backbone folding pattern is retained in the channel-forming subunits and that the substitutions primarily influence ion entry. Both the bulk and the stereochemistry of the aliphatic residues between the tryptophans of gA are important for channel structure and function.     

The dual function of the proliferating cell nuclear antigen (PCNA) in the response of human cells to UV damages

An auxiliary protein of DNA polymerases delta and epsilon, the proliferating cell nuclear antigen (PCNA), is necessary for efficient DNA replication in vivo and in vitro, and also for the repair synthesis in vitro, but its role in the excision repair of genome in vivo is not exactly established. In S-phase of unirradiated cells, PCNA is tightly bound to focal centers of DNA replication and is not removed by treatment with detergent Triton X-100, but is completely extracted from non-S-phase cells by the indicated detergent. It was shown earlier that after UV-irradiation PCNA could not be removed by the detergent even from non-S-phase cells. It was interpreted as the evidence of PCNA integration into the repair complex and of the participation of this protein in repair synthesis in vivo. In the present work the data were obtained indicating that the role of PCNA in cell response to UV-damage was not confined only to its possible involvement in repair synthesis. With the help of confocal microscopy it was established that in Triton X-100-extracted normal cells PCNA did not colocalize with the well known excision repair protein XPB/ERCC3, defective in cells from Xeroderma pigmentosum (complementation group B) patients. XPB-protein is induced by UV-irradiation in normal cells, and this induction is not observed in repair deficient cells. However, in such cells UV-light induces a detergent-resistant form of PCNA, and this form is obviously not connected with repair. It cannot be excluded that a rapid PCNA immobilization immediately after UV-irradiation of cells is needed for the facilitation of photochemical damage bypass during the subsequent replication of genome.     

Hypomethylation in cervical tissue: is there a correlation with folate status?

5-Aminolevulinic acid (ALA) is the first intermediate substrate in the heme synthetic pathway and is the substrate of aminolevulinic acid dehydratase (ALAD, porphobilinogen synthase). Because lead effectively inhibits ALAD activity, resulting in accumulation of ALA in urine and blood, urinary ALA (ALAU) has been used as a biomarker for lead exposure or early biologic effect of lead. Intraindividual variation in urinary excretion of ALA requires the use of 24-hour urine samples or adjustment of single urine samples by other normalizing variables, such as urinary creatinine concentration. Previous studies of ALAU concentration have used various adjustment methods; however, few have compared creatinine-adjusted ALAU concentration with ALA concentration in plasma (ALAP) from subjects with low (< 30 micrograms/dL) to moderate (< 60 micrograms/dL) levels of blood lead. To determine if creatinine-adjusted ALAU is associated with ALAP, we measured ALAU, ALAP, and urinary creatinine in 65 Korean lead workers with blood lead concentrations in the range of 14-60 micrograms/dL. ALAU, ALAU/creatinine, or ALAU/log creatinine all correlated with ALAP. However, ALAU/creatinine correlated more closely with ALAP based on Spearman's r (rs = 0.40, P, = 0.0009), supporting the use of ALA/creatinine in single urine samples as a surrogate for ALAP.