A major difference between the divergence patterns within the lines-1 families in mice and voles

L1 retroposons are represented in mice by subfamilies of interspersed sequences of varied abundance. Previous analyses have indicated that subfamilies are generated by duplicative transposition of a small number of members of the L1 family, the progeny of which then become a major component of the murine L1 population, and are not due to any active processes generating homology within preexisting groups of elements in a particular species. In mice, more than a third of the L1 elements belong to a clade that became active approximately 5 Mya and whose elements are > or = 95% identical. We have collected sequence information from 13 L1 elements isolated from two species of voles (Rodentia: Microtinae: Microtus and Arvicola) and have found that divergence within the vole L1 population is quite different from that in mice, in that there is no abundant subfamily of homologous elements. Individual L1 elements from voles are very divergent from one another and belong to a clade that began a period of elevated duplicative transposition approximately 13 Mya. Sequence analyses of portions of these divergent L1 elements (approximately 250 bp each) gave no evidence for concerted evolution having acted on the vole L1 elements since the split of the two vole lineages approximately 3.5 Mya; that is, the observed interspecific divergence (6.7%-24.7%) is not larger than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses showed no clustering into Arvicola and Microtus clades.      

Multifactorial diversity sustains microbial community stability

Maintenance of a high degree of biodiversity in homogeneous environments is poorly understood. A complex cheese starter culture with a long history of use was characterized as a model system to study simple microbial communities. Eight distinct genetic lineages were identified, encompassing two species: Lactococcus lactis and Leuconostoc mesenteroides. The genetic lineages were found to be collections of strains with variable plasmid content and phage sensitivities. Kill-the-winner hypothesis explaining the suppression of the fittest strains by density-dependent phage predation was operational at the strain level. This prevents the eradication of entire genetic lineages from the community during propagation regimes (back-slopping), stabilizing the genetic heterogeneity in the starter culture against environmental uncertainty.     

Immunohistochemical localization of irisin in skin,eye, and thyroid and pineal glands of the crested porcupine (Hystrix cristata)

Irisin was first identified in muscle cells. We detected irisin immunoreactivity in various organs of the crested porcupine (Hystrix cristata). In the epidermis, irisin immunoreactivity was localized mainly in stratum basale, stratum spinosum and stratum granulosum layers; immunoreactivity was not observed in the stratum corneum. In the dermis, irisin was found in the external and internal root sheath, cortex and medulla of hair follicles, and in sebaceous glands. Irisin immunoreactivity was found in the neural retina and skeletal muscle fibers associated with the eye. The pineal and thyroid glands also exhibited irisin immunoreactivity.     

Bioavailability of hydroxycinnamates: a brief review of in vivo and in vitro studies

Hydroxycinnamates including p-coumaric acid, caffeic acid, ferulic acid, sinapic acid, and their esterified/etherified conjugates such as chlorogenic acids are abundant in cereals, coffee, fruit and vegetables. Studies have shown their potential in the prevention of chronic diseases such as cardiovascular disease and cancer. The impact of these dietary hydroxycinnamates on health depends on their bioavailability. In this article, in vivo and in vitro studies pertaining to bioavailability of hydroxycinnamates are reviewed and discussed. The chemical structures, existing forms, and/or doses of hydroxycinnamates may affect their metabolic fate. Limited studies suggest that the relative bioavailability of hydroxycinnamates may be in the following order: chlorogenic acid < rosmarinic acid < caffeic acid < ferulic acid < p-coumaric acid. Bound hydroxycinnamates generally have lower bioavailability than their monomer counterparts. Further pharmacokinetic and phamacodynamic studies are required to characterize the metabolism of hydroxycinnamates and their potential health impact in humans.     

Examining the interaction of apo E and neurotoxicity on a murine model of ALS-PDC

Epidemiological studies have shown a positive relationship between cycad flour consumption and the development of the neurodegenerative disorder, amyotrophic lateral sclerosis - parkinsonism - dementia complex (ALS-PDC). Apolipoprotein E (apo E) allele variations have been associated with genetic susceptibility in neurodegenerative diseases, including ALS-PDC. We have studied cycad toxicity in a mouse model of ALS-PDC with a particular interest in its impact on the central nervous system (CNS) in both apo E knock-out (KO) mice and their wild-type (WT) counterparts. Behavioral motor tests, motor neuron counts, and immunohistochemical staining in brain and spinal cord, as well as routine histological examinations on internal organs, were performed to evaluate cycad toxicity. Plasma cholesterol levels were also measured before and during the study. Cycad treatment was associated with higher levels of plasma cholesterol only in apo E KO mice; increased levels of plasma cholesterol did not result in increased athero genesis. Cycad-fed wild-type mice developed progressive behavioral deficits including ALS-PDC-like pathological outcomes, while cycad-fed apo E KO mice were not significantly affected. Cycad-fed wild-type mice had shorter gait length measurements along with higher active caspase-3 levels in the striatum, substantia nigra, primary motor cortex, and spinal cord as compared with corresponding controls. These changes were associated with decreased labeling for glutamate transporter 1B and tyrosine hydroxylase activity levels. No evidence of cycad toxicity was observed in internal organs of either wild-type or apo E KO mice. Our data demonstrate that apo E KO mice are less susceptible to cycad toxicity, suggesting a role for apo E as a possible genetic susceptibility factor for some forms of toxin-induced neurodegeneration.     

Effects of dietary flaxseed on vascular contractile function and atherosclerosis during prolonged hypercholesterolemia in rabbits

Dietary flaxseed has significant anti-atherogenic effects. However, the limits of this action and its effects on vascular contractile function are not known. We evaluated the effects of flaxseed supplementation on atherosclerosis and vascular function under prolonged hypercholesterolemic conditions in New Zealand White rabbits assigned to one of four groups for 6, 8, or 16 wk of feeding: regular diet (RG), 10% flaxseed-supplemented diet (FX), 0.5% cholesterol-supplemented diet (CH), and 0.5% cholesterol- and 10% flaxseed-supplemented diet (CF). Cholesterol feeding resulted in elevated plasma cholesterol levels and the development of atherosclerosis. The CF group had significantly less atherosclerotic lesions in the aorta and carotid arteries after 6 and 8 wk than the CH animals. However, the anti-atherogenic effect of flaxseed supplementation was completely attenuated by 16 wk. Maximal tension induced in aortic rings either by KCl or norepinephrine was not impaired by dietary cholesterol until 16 wk. This functional impairment was not prevented by including flaxseed in the high-cholesterol diet. Aortic rings from the cholesterol-fed rabbits exhibited an impaired relaxation response to acetylcholine at all time points examined. Including flaxseed in the high-cholesterol diet completely normalized the relaxation response at 6 and 8 wk and partially restored it at 16 wk. No significant changes in the relaxation response induced by sodium nitroprusside were observed in any of the groups. In summary, dietary flaxseed is a valuable strategy to limit cholesterol-induced atherogenesis as well as abnormalities in endothelial-dependent vasorelaxation. However, these beneficial effects were attenuated during prolonged hypercholesterolemic conditions.