The rabbit alpha-like globin gene cluster is polymorphic both in the sizes of BamHI fragments and in the numbers of duplicated sets of genes

The alpha-like globin gene cluster in rabbits contains embryonic zeta- globin genes, an adult alpha-globin gene, and theta-globin genes of undetermined function. The basic arrangement of genes, deduced from analysis of cloned DNA fragments, is 5'-zeta 0-zeta 1-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3'. However, the pattern of restriction fragments containing zeta- and theta-globin genes varies among individual rabbits. Analysis of BamHI fragments of genomic DNA from 24 New Zealand white rabbits revealed eight different patterns of fragments containing zeta-globin genes. The large BamHI fragments containing genes zeta 0 and zeta 1 are polymorphic in length, whereas a 1.9-kb fragment containing the zeta 2 gene and the 3.5-kb fragment containing the zeta 3 gene do not vary in size. In contrast to this constancy in the size of the restriction fragments, the copy number of the zeta 2 and zeta 3 genes does vary among different rabbits. No length polymorphism was detected in the BamHI fragments containing the theta-globin genes, but again the copy number varies for restriction fragments containing the theta 2 gene. The alpha 1- and theta 1-globin genes are located in a nonpolymorphic 7.2-kb BamHI fragment. The combined data from hybridization with both zeta and theta probes shows that the BamHI cleavage pattern does not vary within the region 5'-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3', but the pattern genomic blot-hybridization patterns for the progeny of parental rabbits with different zeta-globin gene patterns shows that the polymorphic patterns are inherited in a Mendelian fashion. Two different haplotypes have been mapped based on the genomic blot-hybridization data. The variation in the alpha-like globin gene cluster in the rabbit population results both from differences in the copy number of the duplication block containing the zeta-zeta-theta gene set and from the presence or absence of polymorphic BamHI sites.      

Assignment of orthologous relationships among mammalian alpha-globin genes by examining flanking regions reveals a rapid rate of evolution

In order to study the relationships among mammalian alpha-globin genes, we have determined the sequence of the 3' flanking region of the human alpha 1 globin gene and have made pairwise comparisons between sequenced alpha-globin genes. The flanking regions were examined in detail because sequence matches in these regions could be interpreted with the least complication from the gene duplications and conversions that have occurred frequently in mammalian alpha-like globin gene clusters. We found good matches between the flanking regions of human alpha 1 and rabbit alpha 1, human psi alpha 1 and goat I alpha, human alpha 2 and goat II alpha, and horse alpha 1 and goat II alpha. These matches were used to align the alpha-globin genes in gene clusters from different mammals. This alignment shows that genes at equivalent positions in the gene clusters of different mammals can be functional or nonfunctional, depending on whether they corrected against a functional alpha-globin gene in recent evolutionary history. The number of alpha-globin genes (including pseudogenes) appears to differ among species, although highly divergent pseudogenes may not have been detected in all species examined. Although matching sequences could be found in interspecies comparisons of the flanking regions of alpha- globin genes, these matches are not as extensive as those found in the flanking regions of mammalian beta-like globin genes. This observation suggests that the noncoding sequences in the mammalian alpha-globin gene clusters are evolving at a faster rate than those in the beta-like globin gene clusters. The proposed faster rate of evolution fits with the poor conservation of the genetic linkage map around alpha-globin gene clusters when compared to that of the beta-like globin gene clusters. Analysis of the 3' flanking regions of alpha-globin genes has revealed a conserved sequence approximately 100-150 bp 3' to the polyadenylation site; this sequence may be involved in the expression or regulation of alpha-globin genes.      

Out of Africa and back again: nested cladistic analysis of human Y chromosome variation

We surveyed nine diallelic polymorphic sites on the Y chromosomes of 1,544 individuals from Africa, Asia, Europe, Oceania, and the New World. Phylogenetic analyses of these nine sites resulted in a tree for 10 distinct Y haplotypes with a coalescence time of approximately 150,000 years. The 10 haplotypes were unevenly distributed among human populations: 5 were restricted to a particular continent, 2 were shared between Africa and Europe, 1 was present only in the Old World, and 2 were found in all geographic regions surveyed. The ancestral haplotype was limited to African populations. Random permutation procedures revealed statistically significant patterns of geographical structuring of this paternal genetic variation. The results of a nested cladistic analysis indicated that these geographical associations arose through a combination of processes, including restricted, recurrent gene flow (isolation by distance) and range expansions. We inferred that one of the oldest events in the nested cladistic analysis was a range expansion out of Africa which resulted in the complete replacement of Y chromosomes throughout the Old World, a finding consistent with many versions of the Out of Africa Replacement Model. A second and more recent range expansion brought Asian Y chromosomes back to Africa without replacing the indigenous African male gene pool. Thus, the previously observed high levels of Y chromosomal genetic diversity in Africa may be due in part to bidirectional population movements. Finally, a comparison of our results with those from nested cladistic analyses of human mtDNA and beta-globin data revealed different patterns of inferences for males and females concerning the relative roles of population history (range expansions) and population structure (recurrent gene flow), thereby adding a new sex-specific component to models of human evolution.      

Dasatinib Attenuates Pressure Overload Induced Cardiac Fibrosis in a Murine Transverse Aortic Constriction Model

Reactive cardiac fibrosis resulting from chronic pressure overload (PO) compromises ventricular function and contributes to congestive heart failure. We explored whether nonreceptor tyrosine kinases (NTKs) play a key role in fibrosis by activating cardiac fibroblasts (CFb), and could potentially serve as a target to reduce PO-induced cardiac fibrosis. Our studies were carried out in PO mouse myocardium induced by transverse aortic constriction (TAC). Administration of a tyrosine kinase inhibitor, dasatinib, via an intraperitoneally implanted mini-osmotic pump at 0.44 mg/kg/day reduced PO-induced accumulation of extracellular matrix (ECM) proteins and improved left ventricular geometry and function. Furthermore, dasatinib treatment inhibited NTK activation (primarily Pyk2 and Fak) and reduced the level of FSP1 positive cells in the PO myocardium. In vitro studies using cultured mouse CFb showed that dasatinib treatment at 50 nM reduced: (i) extracellular accumulation of both collagen and fibronectin, (ii) both basal and PDGF-stimulated activation of Pyk2, (iii) nuclear accumulation of Ki67, SKP2 and histone-H2B and (iv) PDGF-stimulated CFb proliferation and migration. However, dasatinib did not affect cardiomyocyte morphologies in either the ventricular tissue after in vivo administration or in isolated cells after in vitro treatment. Mass spectrometric quantification of dasatinib in cultured cells indicated that the uptake of dasatinib by CFb was greater that that taken up by cardiomyocytes. Dasatinib treatment primarily suppressed PDGF but not insulin-stimulated signaling (Erk versus Akt activation) in both CFb and cardiomyocytes. These data indicate that dasatinib treatment at lower doses than that used in chemotherapy has the capacity to reduce hypertrophy-associated fibrosis and improve ventricular function.     

Why Middle-Aged Listeners Have Trouble Hearing in Everyday Settings

Anecdotally, middle-aged listeners report difficulty conversing in social settings, even when they have normal audiometric thresholds [1-3]. Moreover, young adult listeners with "normal" hearing vary in their ability to selectively attend to speech amid similar streams of speech. Ignoring age, these individual differences correlate with physiological differences in temporal coding precision present in the auditory brainstem, suggesting that the fidelity of encoding of suprathreshold sound helps explain individual differences [4]. Here, we revisit the conundrum of whether early aging influences an individual's ability to communicate in everyday settings. Although absolute selective attention ability is not predicted by age, reverberant energy interferes more with selective attention as age increases. Breaking the brainstem response down into components corresponding to coding of?stimulus fine structure and envelope, we find that age alters which brainstem component predicts performance. Specifically, middle-aged listeners appear to rely heavily on temporal fine structure, which is more disrupted by reverberant energy than temporal envelope structure is. In contrast, the fidelity of envelope cues predicts performance in younger adults. These results hint that temporal envelope cues influence spatial hearing in reverberant settings more than is commonly appreciated and help explain why middle-aged listeners have particular difficulty communicating in daily life.     

Iodine nutrition and breast feeding

A survey of the databanks Medline and Web of science identified studies dealing with maternal and infant iodine nutrition during breast feeding. The iodine concentration of human milk varies widely due to maternal iodine intake. Mean breast milk iodine concentrations are reported as ranging from 5.4 to 2170 μg/L (median 62 μg/L) in worldwide studies. In the few studies that compared length of lactation, gestation length, and parity number, these factors did not significantly affect milk-iodine concentrations. In studies of maternal iodine deficiency, untreated goiter had no impact on breast milk iodine when compared with controls. Iodine in human milk responds quickly to dietary iodine intake, either supplemented or consumed in natural foods. Easily absorbable iodine from foods, supplemental sources, iodine-based medication or iodine-based antiseptic solutions used during parturition, is taken up by the maternal thyroid and mammary glands through the Na⁺/I⁻ symporter system. This transmembrane carrier protein transports iodine against a high concentration gradient. Hormonal iodine in breast milk occurs mainly as T-4, but depending on maternal iodine intake, high concentrations of the inorganic form (iodide) are found. In less developed countries, where natural-food-iodine intake is low, adequate maternal iodine nutritional status depends exclusively on enforcement of food iodination. In industrialized countries, maternal iodine intake has increased as a function of increasing consumption of dairy products. The human infant is sensitive to maternal iodine nutrition during fetal development and later during breast feeding. Environmental factors, not directly related to maternal iodine intake, such as intake of selenium and organochlorine pollutants, can affect thyroid hormone homeostasis in breast-fed infants. In spite of low iodine concentrations found in milk of mothers consuming low-iodine natural foods, long lasting or even life-lasting benefits to the breast-fed infant are demonstrable.     

Effects of Temperature and pH on Reduction of Bacteria in a Point-of-Use Drinking Water Treatment Product for Emergency Relief

The effects of temperature and pH on the water treatment performance of a point-of-use (POU) coagulant/disinfectant product were evaluated. Cold temperatures (∼5°C) reduced the bactericidal efficiency of the product with regard to Escherichia coli and total coliform log₁₀ reductions.     

Arrestin-dependent Angiotensin AT1 Receptor Signaling Regulates Akt and mTor-mediated Protein Synthesis

Control of protein synthesis is critical to both cell growth and proliferation. The mammalian target of rapamycin (mTOR) integrates upstream growth, proliferation, and survival signals, including those transmitted via ERK1/2 and Akt, to regulate the rate of protein translation. The angiotensin AT₁ receptor has been shown to activate both ERK1/2 and Akt in arrestin-based signalsomes. Here, we examine the role of arrestin-dependent regulation of ERK1/2 and Akt in the stimulation of mTOR-dependent protein translation by the AT₁ receptor using HEK293 and primary vascular smooth muscle cell models. Nascent protein synthesis stimulated by both the canonical AT₁ receptor agonist angiotensin II (AngII), and the arrestin pathway-selective agonist [Sar¹-Ile⁴-Ile⁸]AngII (SII), is blocked by shRNA silencing of βarrestin1/2 or pharmacological inhibition of Akt, ERK1/2, or mTORC1. In HEK293 cells, SII activates a discrete arrestin-bound pool of Akt and promotes Akt-dependent phosphorylation of mTOR and its downstream effector p70/p85 ribosomal S6 kinase (p70/85S6K). In parallel, SII-activated ERK1/2 helps promote mTOR and p70/85S6K phosphorylation, and is required for phosphorylation of the known ERK1/2 substrate p90 ribosomal S6 kinase (p90RSK). Thus, arrestins coordinate AT₁ receptor regulation of ERK1/2 and Akt activity and stimulate protein translation via both Akt-mTOR-p70/85S6K and ERK1/2-p90RSK pathways. These results suggest that in vivo, arrestin pathway-selective AT₁ receptor agonists may promote cell growth or hypertrophy through arrestin-mediated mechanisms despite their antagonism of G protein signaling.