Fibulin-4 is essential for maintaining arterial wall integrity in conduit but not muscular arteries

Homozygous or compound heterozygous mutations in fibulin-4 (FBLN4) lead to autosomal recessive cutis laxa type 1B (ARCL1B), a multisystem disorder characterized by significant cardiovascular abnormalities, including abnormal elastin assembly, arterial tortuosity, and aortic aneurysms. We sought to determine the consequences of a human disease-causing mutation in FBLN4 (E57K) on the cardiovascular system and vascular elastic fibers in a mouse model of ARCL1B. Fbln4E57K/E57K mice were hypertensive and developed arterial elongation, tortuosity, and ascending aortic aneurysms. Smooth muscle cell organization within the arterial wall of large conducting vessels was abnormal, and elastic fibers were fragmented and had a moth-eaten appearance. In contrast, vessel wall structure and elastic fiber integrity were normal in resistance/muscular arteries (renal, mesenteric, and saphenous). Elastin cross-linking and total elastin content were unchanged in large or small arteries, whereas elastic fiber architecture was abnormal in large vessels. While the E57K mutation did not affect Fbln4 mRNA levels, FBLN4 protein was lower in the ascending aorta of mutant animals compared to wild-type arteries but equivalent in mesenteric arteries. We found a differential role of FBLN4 in elastic fiber assembly, where it functions mainly in large conduit arteries. These results suggest that elastin assembly has different requirements depending on vessel type. Normal levels of elastin cross-links in mutant tissue call into question FBLN4\u27s suggested role in mediating lysyl oxidase-elastin interactions. Future studies investigating tissuespecific elastic fiber assembly may lead to novel therapeutic interventions for ARCL1B and other disorders of elastic fiber assembly. 2017 © The Authors, some rights reserved

The endemic gastropod fauna of Lake Titicaca : correlation between molecular evolution and hydrographic history

Lake Titicaca, situated in the Altiplano high plateau, is the only ancient lake in South America. This 2- to 3-My-old (where My is million years) water body has had a complex history that included at least five major hydrological phases during the Pleistocene. It is generally assumed that these physical events helped shape the evolutionary history of the lake´s biota. Herein, we study an endemic species assemblage in Lake Titicaca, composed of members of the microgastropod genus Heleobia, to determine whether the lake has functioned as a reservoir of relic species or the site of local diversification, to evaluate congruence of the regional paleohydrology and the evolutionary history of this assemblage, and to assess whether the geographic distributions of endemic lineages are hierarchical. Our phylogenetic analyses indicate that the Titicaca/Altiplano Heleobia fauna (together with few extralimital taxa) forms a species flock. A molecular clock analysis suggests that the most recent common ancestor (MRCAs) of the Altiplano taxa evolved 0.53 (0.28–0.80) My ago and the MRCAs of the Altiplano taxa and their extralimital sister group 0.92 (0.46–1.52) My ago. The endemic species of Lake Titicaca are younger than the lake itself, implying primarily intralacustrine speciation. Moreover, the timing of evolutionary branching events and the ages of two precursors of Lake Titicaca, lakes Cabana and Ballivián, is congruent. Although Lake Titicaca appears to have been the principal site of speciation for the regional Heleobia fauna, the contemporary spatial patterns of endemism have been masked by immigration and/or emigration events of local riverine taxa, which we attribute to the unstable hydrographic history of the Altiplano. Thus, a hierarchical distribution of endemism is not evident, but instead there is a single genetic break between two regional clades. We also discuss our findings in relation to studies of other regional biota and suggest that salinity tolerance was the most likely limiting factor in the evolution of Altiplano species flocks

The Trypanosomatid Pr77-hallmark contains a downstream core promoter element essential for transcription activity of the Trypanosoma cruzi L1Tc retrotransposon

Diagram of: a) RT-PCR for analysis of the composition of the Luc mRNA 5′ end. The CTC7 primer was employed for the reverse transcription and cDNA synthesis of Luc mRNA in stable T. cruzi transfectants. PCR amplification was carried out with 5′R77 primer or the SLTc primers. b) Primer extension analysis to detect the transcription initiation site of Luc mRNAs in stable transfectants. The LUC28rev primer was used to extend the Luc mRNA using the AMV reverse transcriptase enzyme. (PDF 288 kb

Traitement de polissage par marais épurateur du drainage minier acide

Affiche présentée dans le cadre du Colloque de l'ARC, «La culture de la recherche au collégial», dans le cadre du 82e Congrès de l'Acfas, Université Concordia, Montréal, le 14 mai 2014.Les résidus miniers représentent une source de danger potentiel pour l'environnement, en particulier lorsque ces déchets contiennent des minéraux sulfureux qui peuvent s'oxyder et générer du drainage minier acide (DMA). Ce dernier est caractérisé par un pH faible et des concentrations en sulfates et métaux dissous élevées. Les traitements biologiques constituent une solution moins coûteuse par rapport aux traitements chimiques, en plus de présenter plusieurs avantages dont des taux élevés d’enlèvement des métaux, une réduction du pH, de faibles coûts d’exploitation et une consommation minimale d’énergie. La capacité des marais filtrants à traiter un DMA chargé en fer à l’étape de polissage a été étudiée. Les systèmes consistaient en des marais artificiels à écoulement vertical et horizontal de 0,052 m3, remplis de deux différents substrats et plantés avec des quenouilles (Typha latifolia). Ils étaient alimentés pour traiter 1,5 mL/min d’un DMA ayant une concentration moyenne de 38,0 mg/L de fer, 2,6 mg/L de manganèse, 0,4 mg/L de nickel et 0,9 mg/L de zinc à un pH moyen de 4,2. Après traitement, le pH moyen à l’effluent était de 8,0 pour les marais verticaux et de 7,6 pour les horizontaux. Le taux d’enlèvement du fer et du zinc était respectivement de 95 et 96 % pour les marais à écoulement verticaux et de 87 et 94 % pour les horizontaux. Le traitement du nickel et du manganèse était négligeable

The SIDER2 elements, interspersed repeated sequences that populate the Leishmania genomes, constitute subfamilies showing chromosomal proximity relationship

<p>Abstract</p> <p>Background</p> <p>Protozoan parasites of the genus <it>Leishmania </it>are causative agents of a diverse spectrum of human diseases collectively known as leishmaniasis. These eukaryotic pathogens that diverged early from the main eukaryotic lineage possess a number of unusual genomic, molecular and biochemical features. The completion of the genome projects for three <it>Leishmania </it>species has generated invaluable information enabling a direct analysis of genome structure and organization.</p> <p>Results</p> <p>By using DNA macroarrays, made with <it>Leishmania infantum </it>genomic clones and hybridized with total DNA from the parasite, we identified a clone containing a repeated sequence. An analysis of the recently completed genome sequence of <it>L. infantum</it>, using this repeated sequence as bait, led to the identification of a new class of repeated elements that are interspersed along the different <it>L. infantum </it>chromosomes. These elements turned out to be homologues of SIDER2 sequences, which were recently identified in the <it>Leishmania major </it>genome; thus, we adopted this nomenclature for the <it>Leishmania </it>elements described herein. Since SIDER2 elements are very heterogeneous in sequence, their precise identification is rather laborious. We have characterized 54 LiSIDER2 elements in chromosome 32 and 27 ones in chromosome 20. The mean size for these elements is 550 bp and their sequence is G+C rich (mean value of 66.5%). On the basis of sequence similarity, these elements can be grouped in subfamilies that show a remarkable relationship of proximity, i.e. SIDER2s of a given subfamily locate close in a chromosomal region without intercalating elements. For comparative purposes, we have identified the SIDER2 elements existing in <it>L. major </it>and <it>Leishmania braziliensis </it>chromosomes 32. While SIDER2 elements are highly conserved both in number and location between <it>L. infantum </it>and <it>L. major</it>, no such conservation exists when comparing with SIDER2s in <it>L. braziliensis </it>chromosome 32.</p> <p>Conclusion</p> <p>SIDER2 elements constitute a relevant piece in the <it>Leishmania </it>genome organization. Sequence characteristics, genomic distribution and evolutionarily conservation of SIDER2s are suggestive of relevant functions for these elements in <it>Leishmania</it>. Apart from a proved involvement in post-trancriptional mechanisms of gene regulation, SIDER2 elements could be involved in DNA amplification processes and, perhaps, in chromosome segregation as centromeric sequences.</p

Environmental contaminants and breeding biology of great blue herons in the Columbia River Basin

Great blue heron (Ardea herodias) eggs and prey items were collected from six colonies on the Columbia and Willamette rivers and Puget Sound during 1994-95. Contaminant concentrations, reproductive success, and biomagnification factors (BMFs) were determined and effects of residue levels were measured by H4IIE rat hepatoma and ethoxyresorufin-O-dealkylase (EROD) bioassays. Fledging and reproductive rates were similar to those determined for other healthy heron populations. With the exception of one site, mean residue concentrations in heron eggs and prey were low. However, elevated concentrations of PCBs were detected in eggs and prey from Ross Island on the Willamette River. Among-site differences were not statistically significant different in H4IIE TCDD-equivalents (TCDD-EQs) or EROD activity, although the TCDD-EQ for Karlson Island was 9 to 20 times greater than that of any other site. Large differences existed between toxic equivalents calculated from egg residue concentrations and TCDDEQs, which indicated non-additive interactions among the compounds. TCDD-EQs and nest failure were positively correlated with TCDD concentration. Biomagnification factors varied greatly among sites for most compounds. Of the organochlorine pesticides, DDE and heptachlor epoxide were magnified the most. Penta- and hexachlorinated dioxins were biomagnified to a greater extent than TCDD. Our results support the use of great blue herons as an indicator of contamination in aquatic ecosystems. Their relatively low sensitivity to organochlorine contaminants and high trophic position allows contaminant accumulation and biomagnification without immediate adverse effects which are often seen in other, more sensitive species. Breeding behavior of great blue herons was also examined at the six colonies to Patterns of brooding, pair bonding, preening, and nest visits were significantly different (P < 0.05) between the reference and non-reference sites. The site with the highest concentrations of DDE and PCBs had significantly lower nest attendance and feeding rates relative to the reference site. Differences in nest attendance among colonies were inversely correlated with DDE concentrations (r = -0.79, P = 0.06). Among-site differences in the odds ratios for adults feeding chicks were positively correlated with DDE and PCB concentrations (r = 0.84, P = 0.04 and r = 0.79, P = 0.06 respectively), but these relationships may be an artifact of the low frequency of occurrance of feeding sessions and its dependence on nest attendance. Clutch size and hatch, fledge, and reproductive success were similar to those reported for healthy populations. Differences in activity budgets among sites do not appear to be affecting reproductive rates of herons at the different colonies

Identification of an hepatitis delta virus-like ribozyme at the mRNA 5′-end of the L1Tc retrotransposon from Trypanosoma cruzi

L1Tc is a non-LTR LINE element from Trypanosoma cruzi that encodes its transposition machinery and bears an internal promoter. Herewith, we report the identification of an in vitro active hepatitis delta virus-like ribozyme located in the first 77 nt at the 5′-end of the L1Tc mRNA (L1TcRz). The data presented show that L1TcRz has a co-transcriptional function. Using gel-purified uncleaved RNA transcripts, the data presented indicate that the kinetics of the self-cleaving, in a magnesium-dependent reaction, fits to a two-phase decay curve. The cleavage point identified by primer extension takes place at +1 position of the element. The hydroxyl nature of the 5′-end of the 3′-fragment generated by the cleavage activity of L1TcRz was confirmed. Since we have previously described that the 77-nt long fragment located at the 5′-end of L1Tc has promoter activity, the existence of a ribozyme in L1Tc makes this element to be the first described non-LTR retroelement that has an internal promoter–ribozyme dual function. The L1Tc nucleotides located downstream of the ribozyme catalytic motif appear to inhibit its activity. This inhibition may be influenced by the existence of a specific L1Tc RNA conformation that is recognized by RNase P

Efficiency of monolaurin in mitigating ruminal methanogenesis and modifying C-isotope fractionation when incubating diets composed of either C3 or C4 plants in a rumen simulation technique (Rusitec) system

Mitigation of methanogenesis in ruminants has been an important goal for several decades. Free lauric acid, known to suppress ruminal methanogenesis, has a low palatability; therefore, in the present study the aim was to evaluate the mitigation efficacy of its esterified form (monolaurin). Further, 13C-isotope abundance (δ13C) and 13C-12C fractionation during methanogenesis and fermentation were determined to evaluate possible microbial C-isotope preferences. Using the rumen simulation technique, four basal diets, characterised either by the C3 plants grass (hay) and wheat (straw and grain), or the C4 plant (13C excess compared with C3 plants) maize (straw and grain), and a mixture of the latter two, were incubated with and without monolaurin (50g/kg dietary DM). Added to hay, monolaurin did not significantly affect methanogenesis. When added to the other diets (P<0·05 for the wheat-based diet) methane formation was lowered. Monolaurin decreased fibre disappearance (least effect with the hay diet), acetate:propionate ratio, and protozoal counts. Feed residues and SCFA showed the same δ13C as the diets. Methane was depleted in 13C while CO2 was enriched in 13C compared with the diets. Monolaurin addition resulted in 13C depletion of CO2 and enrichment in CH4 (the latter only in the hay diet). In conclusion, monolaurin proved to effectively decrease methanogenesis in the straw-grain diets although this effect might partly be explained by the concomitantly reduced fibre disappearance. The influence on 13C-isotope abundance and fractionation supports the hypothesis that ruminal microbes seem to differentiate to some extent between C-isotopes during methanogenesis and fermentatio

The crystalline structures of the odd alkanes pentane, heptane, nonane, undecane, tridecane and pentadecane monolayers adsorbed on graphite at submonolayer coverages and from the liquid

A combination of neutron and X-ray diffraction has been used to structurally characterise the crystalline monolayer structures of all the alkanes with odd number of carbon atoms in their alkyl chains from pentane to pentadecane adsorbed on graphite. The structures of all the molecules investigated at submonolayer coverages are isomorphous with centred rectangular unit cells containing two molecules per cell in a parallel arrangement. This is a completely different structure from the ‘herringbone’ arrangement of molecules found for the shorter ‘ even’ alkanes, such as hexane, octane and decane. The monolayers at sub-monolayer coverages are interpreted as uniaxial commensurate with the underlying graphite while those monolayers coexisting with the liquid, while structurally similar, are fully commensurate. The difference between the two structures is a uniaxial compression in the b-direction with the monolayers coexisting with the liquids significantly more dense than at submonolayer coverages. In the low coverage structures the ‘odd’ molecules have an all trans conformation with their extended axes parallel to the surface with the plane of the carbon skeleton also parallel to the graphite surface. At high coverages the carbon skeleton is no longer parallel to the graphite surface but significantly tilted. The longest alkanes, tridecane and pentadecane also show evidence of positional and/or rotational disorder at high coverages