Molecular species of oxidized phospholipids in brain differentiate between learning- and memory impaired and unimpaired aged rats

Amino Acids - Loss of cognitive function is a typical consequence of aging in humans and rodents. The extent of decline in spatial memory performance of rats, assessed by a hole-board test, reaches...     

Visualisation of Leishmania donovani fluorescent hybrids during early stage development in the sand fly vector

Background

The Leishmania protozoan parasites cause devastating human diseases. Leishmania have been considered to replicate clonally, without genetic exchange. However, an accumulation of evidence indicates that there are inter-specific and intra-specific hybrids among natural populations. The first and so far only experimental proof of genetic exchange was obtained in 2009 when double drug resistant Leishmania major hybrids were produced by co-infecting sand flies with two strains carrying different drug resistance markers. However, the location and timing of hybridisation events in sand flies has not been described.

Methodology/Principal Findings

Here we have co-infected Phlebotomus perniciosus and Lutzomyia longipalpis with transgenic promastigotes of Leishmania donovani strains carrying hygromycin or neomycin resistance genes and red or green fluorescent markers. Fed females were dissected at different times post bloodmeal (PBM) and examined by fluorescent microscopy or fluorescent activated cell sorting (FACS) followed by confocal microscopy. In mixed infections strains LEM3804 and Gebre-1 reached the cardia and stomodeal valves more rapidly than strains LEM4265 and LV9. Hybrids unequivocally expressing both red and green fluorescence were seen in single flies of both vectors tested, co-infected with LEM4265 and Gebre-1. The hybrids were present as short (procyclic) promastigotes 2 days PBM in the semi-digested blood in the endoperitrophic space. Recovery of a clearly co-expressing hybrid was also achieved by FACS. However, hybrids could not sustain growth in vitro.

Conclusions/Significance

For the first time, we observed L. donovani hybrids in the sand fly vector, 2 days PBM and described the morphological stages involved. Fluorescence microscopy in combination with FACS allows visualisation and recovery of the progeny of experimental crosses but on this occasion the hybrids were not viable in vitro. Nevertheless, genetic exchange in L. donovani has profound epidemiological significance, because it facilitates the emergence and spread of new phenotypic traits.     

Experimental transmission of Leishmania infantum by two major vectors: a comparison between a viscerotropic and a dermotropic strain

We quantified Leishmania infantum parasites transmitted by natural vectors for the first time. Both L. infantum strains studied, dermotropic CUK3 and viscerotropic IMT373, developed well in Phlebotomus perniciosus and Lutzomyia longipalpis. They produced heavy late-stage infection and colonized the stomodeal valve, which is a prerequisite for successful transmission. Infected sand fly females, and especially those that transmit parasites, feed significantly longer on the host (1.5-1.8 times) than non-transmitting females. Quantitative PCR revealed that P. perniciosus harboured more CUK3 strain parasites, while in L. longipalpis the intensity of infection was higher for the IMT373 strain. However, in both sand fly species the parasite load transmitted was higher for the strain with dermal tropism (CUK3). All but one sand fly female infected by the IMT373 strain transmitted less than 600 promastigotes; in contrast, 29% of L. longipalpis and 14% of P. perniciosus infected with the CUK3 strain transmitted more than 1000 parasites. The parasite number transmitted by individual sand flies ranged from 4 up to 4.19×10(4) promastigotes; thus, the maximal natural dose found was still about 250 times lower than the experimental challenge dose used in previous studies. This finding emphasizes the importance of determining the natural infective dose for the development of an accurate experimental model useful for the evaluation of new drugs and vaccines.     

Characterization of advanced glycation end products for biochemical studies: side chain modifications and fluorescence characteristics

Advanced glycation end products (AGEs) are known to be involved in the pathogenesis of several diseases and therefore effects of AGEs on cells are the objective of numerous investigations. Since AGEs used in biochemical studies are usually not chemically characterized, comparison of data is difficult if not impossible. To find a suitable characterization protocol, human serum albumin was reacted with different concentrations of glucose, methyl glyoxal, and glyoxylic acid. The obtained AGEs were characterized with respect to the extent of side chain modifications (lysine and arginine), the carboxymethyl lysine and carbonyl content, and the fibrillar state. Additionally, their fluorescence and absorbance characteristics were extensively studied. Although we found significant differences in the degree of modification and in AGE-specific fluorescence when using different modifiers, the results provide important information and allow comparing AGEs derived from different modifier concentrations. The results also suggest strong conformational changes within the modified proteins. In the present paper we propose a set of parameters that is sufficient to partially characterize AGEs used for biochemical studies.     

Circulating isoflavonoid levels in CD-1 mice: effect of oral versus subcutaneous delivery and frequency of administration

The CD-1 mouse is a commonly used animal model to understand the biological effects of early-life exposure to soy isoflavones in infants. Most studies using CD-1 mice have administered isoflavones by daily subcutaneous injection, while infants receive oral feeds every few hours. The study objectives were to compare the total serum levels of genistein (GEN), daidzein (DAI) and the DAI metabolites equol and O-desmethyl-angolensin (O-DMA), after subcutaneous injection and oral dosing and to determine if frequency of oral administration results in different circulating levels of isoflavones using the CD-1 mouse model. From postnatal days 1 to 5, pups randomly received corn oil or soy isoflavones (total daily dose, 0.010 mg DAI+0.025 mg GEN) by subcutaneous injection once a day, orally once a day or orally every 4 hours. On postnatal day 5, 1 h posttreatment, mice were killed and serum was collected. Mice treated with soy isoflavones had higher (P<.05) serum GEN (female: 1895–3391 ng/ml and male: 483–578 ng/ml) and DAI (female: 850–1580 ng/ml and male: 248–322 ng/ml) concentrations versus control (5–20 ng/ml) mice, regardless of route or frequency of administration, and were similar among dosing strategies. Total serum concentrations of GEN and DAI were higher (P<.05) among females (GEN: 2714 ± 393 ng/ml and DAI: 1205 ± 164 ng/ml) than males (GEN: 521 ± 439 ng/ml and DAI: 288 ± 184 ng/ml) across treatment groups. Serum equol and O-DMA concentrations were negligible (<3 ng/ml) across groups. In conclusion, different routes of delivery and frequency of administration resulted in similar total serum levels of GEN, DAI¸ equol or O-DMA.     

The C-terminal domain of Fcj1 is required for formation of crista junctions and interacts with the TOB/SAM complex in mitochondria

Crista junctions (CJs) are tubular invaginations of the inner membrane of mitochondria that connect the inner boundary with the cristae membrane. These architectural elements are critical for mitochondrial function. The yeast inner membrane protein Fcj1, called mitofilin in mammals, was reported to be preferentially located at CJs and crucial for their formation. Here we investigate the functional roles of individual domains of Fcj1. The most conserved part of Fcj1, the C-terminal domain, is essential for Fcj1 function. In its absence, formation of CJ is strongly impaired and irregular, and stacked cristae are present. This domain interacts with full-length Fcj1, suggesting a role in oligomer formation. It also interacts with Tob55 of the translocase of outer membrane β-barrel proteins (TOB)/sorting and assembly machinery (SAM) complex, which is required for the insertion of β-barrel proteins into the outer membrane. The association of the TOB/SAM complex with contact sites depends on the presence of Fcj1. The biogenesis of β-barrel proteins is not significantly affected in the absence of Fcj1. However, down-regulation of the TOB/SAM complex leads to altered cristae morphology and a moderate reduction in the number of CJs. We propose that the C-terminal domain of Fcj1 is critical for the interaction of Fcj1 with the TOB/SAM complex and thereby for stabilizing CJs in close proximity to the outer membrane. These results assign novel functions to both the C-terminal domain of Fcj1 and the TOB/SAM complex.     

SWAN: Subset-quantile Within Array Normalization for Illumina Infinium HumanMethylation450 BeadChips

DNA methylation is the most widely studied epigenetic mark and is known to be essential to normal development and frequently disrupted in disease. The Illumina HumanMethylation450 BeadChip assays the methylation status of CpGs at 485,577 sites across the genome. Here we present Subset-quantile Within Array Normalization (SWAN), a new method that substantially improves the results from this platform by reducing technical variation within and between arrays. SWAN is available in the minfi Bioconductor package.     

Liver X Receptor Genes Variants Modulate ALS Phenotype

Amyotrophic lateral sclerosis (ALS) is one of the most severe motor neuron (MN) disorders in adults. Phenotype of ALS patients is highly variable and may be influenced by modulators of energy metabolism. Recent works have implicated the liver X receptors α and β (LXRs), either in the propagation process of ALS or in the maintenance of MN survival. LXRs are nuclear receptors activated by oxysterols, modulating cholesterol levels, a suspected modulator of ALS severity. In a cohort of 438 ALS patients and 330 healthy controls, the influence of LXR genes on ALS risk and phenotype was studied using single nucleotide polymorphisms (SNPs). The two LXRα SNPs rs2279238 and rs7120118 were shown to be associated with age at onset in ALS patients. Consistently, homozygotes were twice more correlated than were heterozygotes to delayed onset. The onset was thus delayed by 3.9 years for rs2279238 C/T carriers and 7.8 years for T/T carriers. Similar results were obtained for rs7120118 (+2.1 years and +6.7 years for T/C and C/C genotypes, respectively). The LXRβ SNP rs2695121 was also shown to be associated with a 30% increase of ALS duration (p = 0.0055, FDR = 0.044). The tested genotypes were not associated with ALS risk. These findings add further evidence to the suspected implication of LXR genes in the disease process of ALS and might open new perspectives in ALS therapeutics.     

Effects of homocysteine and its related compounds on oxygen consumption of the rat heart tissue homogenate: the role of different gasotransmitters

Accumulating evidence indicates that microRNAs are implicated in tumor initiation and progression through negatively regulating oncogenes or tumor suppressor genes. In the present study, we report that the expression of miR-200a was significantly lower in renal cell carcinoma (RCC) specimens and RCC cell lines. Restoration of miR-200a suppressed cell growth, arrested cell cycle progression, and promoted cell apoptosis in RCC cell lines. We next used qRT-PCR array technology to identify Sirtuin 1 (SIRT1) as one of the downregulated proteins during miR-200a overexpression in 786-O cells. Following a further assay by luciferase reporter system, SIRT1 was validated as a direct target of miR-200a. Moreover, siRNA-mediated knockdown of SIRT1 could partially phenocopy the effects of miR-200a overexpression. In contrast, overexpression of truncated SIRT1 (without an endogenous 3′-UTR) could rescue the effect of miR-200a overexpression on 786-O cells, which suggested that SIRT1 3′-UTR is targeted by miR-200a specifically. These observations provide further evidence for a critical tumor-suppressive role of the miR-200a in RCC in addition to identifying a novel regulatory mechanism, which may contribute to SIRT1 upregulation in RCC.