Structure of the human telomere in Na+ solution: an antiparallel (2+2) G-quadruplex scaffold reveals additional diversity

Single-stranded DNA overhangs at the ends of human telomeric repeats are capable of adopting four-stranded G-quadruplex structures, which could serve as potential anticancer targets. Out of the five reported intramolecular human telomeric G-quadruplex structures, four were formed in the presence of K⁺ ions and only one in the presence of Na⁺ ions, leading often to a perception that this structural polymorphism occurs exclusively in the presence of K⁺ but not Na⁺. Here we present the structure of a new antiparallel (2+2) G-quadruplex formed by a derivative of a 27-nt human telomeric sequence in Na⁺ solution, which comprises a novel core arrangement distinct from the known topologies. This structure complements the previously elucidated basket-type human telomeric G-quadruplex to serve as reference structures in Na⁺-containing environment. These structures, together with the coexistence of other conformations in Na⁺ solution as observed by nuclear magnetic resonance spectroscopy, establish the polymorphic nature of human telomeric repeats beyond the influence of K⁺ ions.     

Multiple Hits for the Association of Uterine Fibroids on Human Chromosome 1q43

Uterine leiomyomas (or fibroids) are the most common tumors in women of reproductive age. Early studies of two familial cancer syndromes, the multiple cutaneous and uterine leiomyomatosis (MCUL1), and the hereditary leiomyomatosis and renal cell cancer (HLRCC), implicated FH, a gene on chromosome 1q43 encoding the tricarboxylic acid cycle fumarate hydratase enzyme. The role of this metabolic housekeeping gene in tumorigenesis is still a matter of debate and pseudo-hypoxia has been suggested as a pathological mechanism. Inactivating FH mutations have rarely been observed in the nonsyndromic and common form of fibroids; however, loss of heterozygosity across FH appeared as a significant event in the pathogenesis of a subset of these tumors. To assess the role of FH and the linked genes in nonsyndromic uterine fibroids, we explored a two-megabase interval spanning FH in the NIEHS Uterine fibroid study, a cross-sectional study of fibroids in 1152 premenopausal women. Association mapping with a dense set of single nucleotide polymorphisms revealed several peaks of association (p = 10⁻²–8.10⁻⁵) with the risk and/or growth of fibroids. In particular, genes encoding factors suspected (cytosolic FH) or known (EXO1 - exonuclease 1) to be involved in DNA mismatch repair emerged as candidate susceptibility genes whereas those acting in the autophagy/apoptosis (MAP1LC3C - microtubule-associated protein) or signal transduction (RGS7 - Regulator of G-protein and PLD5– Phospoholipase D) appeared to affect tumor growth. Furthermore, body mass index, a suspected confounder altered significantly but unpredictably the association with the candidate genes in the African and European American populations, suggesting the presence of a major obesity gene in the studied region. With the high potential for occult tumors in common conditions such as fibroids, validation of our data in family-based studies is needed.     

Polypyrrole-hydrogel composites for the construction of clinically important biosensors.

The present study reports on the use of p(2-hydroxyethyl methacrylate) (pHEMA) in which polypyrrole and various oxidoreductase enzymes were physically entrapped to function as a viable matrix for the construction of clinically important amperometric biosensors. Glucose oxidase, cholesterol oxidase and galactose oxidase biosensors were constructed. Electrode-supported hydrogel films were prepared by UV polymerization of the HEMA component (containing the dissolved enzyme) followed immediately by electrochemical polymerization (+0.7V vs. Ag/AgCl) of the pyrrole component within the interstitial spaces of the pre-formed hydrogel network. The optimized glucose oxidase biosensor displayed a wide linear glucose response range (5.0 x 10(-5) to 2.0 x 10(-2) M), a detection limit (3S(y/x)/sensitivity) of 25 microM and a response time of 35-40 s. The analytical recovery of glucose in serum samples ranged from 98 to 102% with mean coefficients of variation of 4.4% (within-day analyses) and 5.1% (day-to-day analyses). All three sensors displayed good stabilities when stored desiccated in the absence of buffer (>9 months).     

Collapse of the endemic lizard Podarcis pityusensis on the island of Ibiza mediated by an invasive snake

The invasive snake Hemorrhois hippocrepis colonized the island of Ibiza (Balearic Islands) in 2003 as stowaways inside trunks of olive trees imported for gardening. It has quickly spread since 2010, posing a threat to the island’s only remaining endemic vertebrate, the Ibiza wall lizard Podarcis pityusensis. We map the yearly expansion rate of the snake and estimate via transect surveys how severely it affects the distribution and abundance of the endemic lizard. As well, we surveyed 9 of 30 small lizard populations on islets surrounding Ibiza that have been isolated since the Last Glacial Maximum. Snakes had invaded 49% of Ibiza’s land area by 2018, and censuses show a critical contrast in lizard abundance between areas with and without snakes; almost all censuses in areas without snakes show lizard presence whereas nearly all censuses in areas with H. hippocrepis lack lizard sightings. Moreover, at least one subspecies previously thriving on one of the offshore islets has become extinct, and there have been several snakes recorded swimming between Ibiza and the surrounding islets. Therefore, lizard populations have been dramatically reduced or have vanished within the range of the snake, and our results quantitatively support upgrading this species’ threat level for extinction. This study can inform to programs to manage invasive snake populations and to conservation actions to recover the endemic lizard.     

Discrimination among <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> H serotypes,serovars and strains based on 16S rRNA, <Emphasis Type="Italic">gyrB</Emphasis> and <Emphasis Type="Italic">aroE</Emphasis> gene sequence analyses

Our aim was to investigate the capability of each of three genes, 16S rRNA, gyrB and aroE, to discriminate, first, among Bacillus thuringiensis H serotypes; second, among B. thuringiensis serovars from the same H serotype; and third, among B. thuringiensis strains from the same serovar. The 16S rRNA, gyrB and aroE genes were amplified from 21 B. thuringiensis H serotypes and their nucleotide sequences determined. Additional strains from four B. cereus sensu lato species were included for comparison purposes. These sequences were pair-wise compared and phylogenetic relationships were revealed. Each of the three genes under study could discriminate among B. thuringiensis H serotypes. The gyrB and aroE genes showed a discriminatory power among B. thuringiensis H serotypes up to nine fold greater than that of the 16S rRNA gene. The gyrB gene was retained for subsequent analyses to discriminate B. thuringiensis serovars from the same H serotype and to discriminate strains from same serovar. A total of 42 B. thuringiensis strains, which encompassed 25 serovars from 12 H serotypes, were analyzed. The gyrB gene nucleotide sequences were different enough as to be sufficient to discriminate among B. thuringiensis serovars from the same H serotype and among B. thuringiensis strains from the same serovar. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

N-Acetylglucosamine-binding proteins on Plasmodium falciparum merozoite surface

Plasmodium falciparum merozoite surface is specifically labelledwith a neoglycoprotein bearing N-acetylgluco-samine (GlcNAc)residues in a sugar-dependent manner, as shown by affinity cytochemistryin fluorescence and electron microscopy. To ascertain the natureof the sugar receptor, merozoite proteins were blotted and testedby a two-step method using biotinylated GlcNAc—bovineserum albumin (BSA) and streptavidin—peroxidase conjugate.Three parasite proteins were specifically revealed and designatedas Pf 120, Pf 83 and Pf 45 GlcNAc-binding proteins. These proteinsbind to a gel substituted with GlcNAc and are specifically elutedwith 300 mM GlcNAc. Using a rabbit antiserum raised againstPf 83, the Pf 120 GlcNAc-binding protein, in addition to Pf83, was labelled by Western blotting. Comparative analyses withan antibody against the Pf 83 MSP derived from the P.falciparummerozoite surface protein (Pf MSP) indicated that the Pf 83GlcNAc-binding protein is not related to the fragment of thePf MSP antigen. Similarly, the Pf 83 GlcNAc-binding proteinis not related to the apical membrane antigen 1 (AMA 1) whichalso has the same molecular mass. Therefore the Pf 120, Pf 83and Pf 45 GlcNAc-binding proteins which are located on the merozoitesurface and recognize GlcNAc residues could be involved in thebinding of merozoites to the glycoconjugates of the surfaceof the red blood cells. GlcNAc lectin neoglycoprotein Plasmodium falciparum red blood cell     

Ingestive Pattern Changes in Blinded Rats

Eating and drinking patterns were examined in intact and blinded adult male Sprague-Dawley rats fed a choice among isocaloric casein, sucrose/dextrin, and vegetable shortening/soybean oil diets. Weekly mean intake of all nutrients was altered in blinded rats, with increased lipid intake and decreased water intake in rats blinded for 2 weeks, lower carbohydrate but higher protein and water intakes in rats blinded for 4 weeks, while 2 weeks later blinded rats maintained high intakes of protein and water. The amplitudes of the daily rhythms for each nutrient behaved similarly to the weekly intakes. Delayed daily time of peak intake for all nutrients over successive weeks after blindness were found, indicating that the timing of peak intake free-runs. 24 h profile indicated time of day variations of nutrient intake tending to be less marked over successive weeks of blindness. Free-running animals maintained the link between carbohydrate intake and hypothalamus serotonin.