Lp(a) interactions.

In this report, we have summarized our recent studies on lipoprotein(a) (Lp(a)) and its interactions with apolipoprotein B-containing lipoproteins (ApoB-Lp). These findings implicate the kringle-4-like domains of Apo(a) in the binding of Lp(a) to other ApoB-Lp and point to proline as important in this interaction. Other studies have indicated that Lp(a) interacts with the subendothelial extracellular matrix (ECM) and that Lp(a) is inversely related to plasma triglycerides. Since Apo(a) also has an affinity for ApoB-Lp, enhanced binding of Apo(a) to the arterial wall could increase the accumulation of LDL in the matrix and thus promote the development of cardiovascular disease.     

Linkage of plasminogen (PLG) and apolipoprotein(a) (LPA) in baboons.

Four allelic forms of serum plasminogen (PLG) were detected in baboons (Papio hamadryas Linneaus 1758) by isoelectric focusing and were determined to be inherited as autosomal codominant traits. Linkage analysis of data from 179 progeny and their parents revealed that PLG is tightly linked (lod score = 30.20) to the gene encoding apolipoprotein(a) (LPA), as in humans. No recombinant individuals were identified. This is the first linkage detected between PLG and LPA in any species other than humans and is the first genetic linkage identified in a nonhuman primate species by family studies.     

Molecular phylogeny of siboglinid annelids (a.k.a. pogonophorans): a review

Siboglinid, or pogonophoran, annelids are tubicolous worms that rely on chemoautotrophic endosymbionts for nutrition. Three clades within the siboglinids are recognized: Frenulata, Vestimentifera, and Monilifera. As a group, these worms have received considerable attention from molecular phylogenetists. Most studies have focused either on the evolutionary origins of the group or on the relationships within vestimentiferans, which live at hydrocarbon seeps and hydrothermal vents. Here I review the literature to date on siboglinid molecular phylogeny and summarize the clade’s evolution. The vestimentiferans have been well studied, especially in the eastern Pacific. The seep taxon Lamellibrachia is basal in the clade with vent species being more derived. Recent studies of seeps are finding new species and suggest that habitat depth can be correlated with species boundaries. In contrast to the vestimentiferans, frenulate evolution has been poorly studied. Despite their greater apparent diversity, frenulate specimens have not been sampled so extensively, and thus little is known about their evolution. Sclerolinum, also referred to as Monilifera, is a recognized genus of siboglinids that forms the sister group to Vestimentifera. Like the frenulates, little is known about the history of this group. Our present understanding of siboglinid phylogeny has, in large part, been dictated by insufficient sampling effort.     

Lipoprotein(a) in women twins: heritability and relationship to apolipoprotein(a) phenotypes.

Lp(a) is a unique lipoprotein consisting of an LDL-like particle and a characteristic protein, apo(a). Increased levels of Lp(a) constitute a risk factor for coronary heart disease. Variation in the size of the apo(a) protein is a phenotype controlled by the apo(a) gene on chromosome 6 and is related to Lp(a) plasma levels. Based on 169 MZ and 125 DZ adult female twin pairs, this study's purpose was to estimate the proportion of the variation in Lp(a) levels that is due to genetic influences and to determine the extent to which the apo(a) locus explains this heritability. Lp(a) levels were significantly more similar in MZ twins than in DZ twins: mean co-twin differences were 3.9 +/- 5.7 mg/dl and 16.0 +/- 19.9 mg/dl (P less than .001), respectively. Intraclass correlations were .94 in MZ twins and .32 in DZ twins, resulting in a heritability estimate of .94 (P less than .001). Heritability was then calculated using only co-twins with the same apo(a) phenotype: the heritability estimate decreased to .45 but was still highly significant (P less than .001). Therefore, on the basis of heritability analysis of women twins, Lp(a) levels are almost entirely genetically controlled. Variation at the apo(a) locus contributes to this heritability, although other genetic factors could be involved.     

The activation of adenylate cyclase. II. The postulated presence of (A) adenylate cyclase in a phospho (inhibited) form (B) a dephospho (activated) form with a cyclic adenylate stimulated membrane protein kinase

Membrane adenylate cyclase (AC) from polymorphonuclear (PMN) leucocytes and platelet membranes are activated several fold by fluoride and prostaglandin E₁ (PGE₁) respectively. Incubation of such activated membranes in a phosphorylating system inhibits cyclase activity. The inhibition can now be relieved by further treatment with fluoride and PGE₁ respectively. These findings suggest that AC exists in an inhibited phospho- and activated dephospho-form. This is supported by the finding that membrane preparations from both sources contain a cyclic adenylate (cAMP) stimulated protein kinase and points to the existence of an adequate membrane phosphorylating system.     

Radioimmunoassay of human plasma Lp(a) lipoprotein.

A quantitative immunodiffusion assay demonstrated Lp(a) lipoprotein in 91% (911 of 1000) of subjects. In order to quantitate Lp(a) in all plasma, a sensitive and specific double antibody radioimmunoassay was developed. The between-assay coefficient of variation was 8%. Lp(a) levels by radioimmunoassay were highly correlated with those obtained by the less sensitive radial immunodiffusion method (r = 0.98, n = 51). All but one of the 89 Lp(a) "negative" subjects by immunodiffusion had detectable levels of Lp(a) by radioimmunoassay. The one subject without detectable Lp(a) had abetalipoproteinemia (without detectable apolipoprotein B by radioimmunoassay). Furthermore, Lp(a) was detected in all three non-human primates examined: patas monkey, baboon, and pig-tail monkey. Quantitation of Lp(a) levels in 90 male myocardial infarction (MI) survivors and their spouses showed that the distribution of Lp(a) levels of MI survivors was significantly higher above the 50th percentile cut-point (P < 0.02) and exceeded that of the spouses. Furthermore, the Lp(a) distribution at and above the 50th percentile for the MI survivors who had an MI at age <50 (n = 36) was shifted to values higher than those having an MI at age >50. Thus, high levels of Lp(a) may be associated with premature coronary disease. We conclude that Lp(a) is present in all individuals with apolipoprotein B and that apolipoprotein B appears necessary for the plasma transport of the Lp(a) lipoprotein. Consistent with this hypothesis, quantitative immunochemical precipitation of (125)I-Lp(a) indicated that essentially all individual molecules of six purified Lp(a) preparations contain both the Lp(a) antigen and apolipoprotein B.     

Diet of Physalaemus cf. cicada (Leptodactylidae) and Bufo granulosus (Bufonidae) in a semideciduous forest.

We determined the diet of the two most abundant anuran species which occur in the litter of a semideciduous forest (Len?óis, Bahia, Brazil), Physalaemus cf. cicada and Bufo granulosus in the dry and rainy seasons. Pitfall traps were used to collect anuran and invertebrate fauna, which showed the availability of prey in the environment. Physalaemus cf. cicada was present in both seasons and Bufo granulosus only in the rainy season. Both species fed mainly on Isoptera and Formicidae. However, there is a difference between the rainy and dry seasons concerning the diet of P. cf. cicada. During the rainy season P. cf. cicada consumed less Isoptera and more Formicidae than in the dry season. In the volumetric sense, Orthoptera was the most important alimentary category for P. cf. cicada and B. granulosus. The Jacobs electivity index indicated that Physalaemus cf. cicada and Bufo granulosus were specialists in Isoptera.