OxLDL-induced macrophage cytotoxicity is mediated by lysosomal rupture and modified by intralysosomal redox-active iron

Oxidized low density lipoprotein (oxLDL) is believed to play a central role in atherogenesis. LDL is oxidized in the arterial intima by mechanisms that are still only partially understood. OxLDL is then taken up by macrophages through scavenger receptor-mediated endocytosis, which then leads to cellular damage, including apoptosis. The complex mechanisms by which oxLDL induces cell injury are mostly unknown. This study has demonstrated that oxLDL-induced damage of macrophages is associated with iron-mediated intralysosomal oxidative reactions, which cause partial lysosomal rupture and ensuing apoptosis. This series of events can be prevented by pre-exposing cells to the iron-chelator, desferrioxamine (DFO), whereas it is augmented by pretreating the cells with a low molecular weight iron complex. Since both DFO and the iron complex would be taken up by endocytosis, and thus directed to the lysosomal compartment, the results suggest that the normal contents of lysosomal low molecular weight iron may play an important role in oxLDL-induced cell damage, presumably by catalyzing intralysosomal fragmentation of lipid peroxides and the formation of toxic aldehydes and oxygen-centered radicals.     

Polyunsaturated hydrocarbons in the hemolymph: biosynthetic precursors of epoxy pheromones of geometrid and arctiid moths

Female moths of many species in Geometridae, Arctiidae and some other macrolepidopteran families produce epoxy pheromones, which are probably derived from polyunsaturated hydrocarbons. In order to understand a biosynthetic site, hemolymph from both sexes of two geometrid species, Ascotis selenaria cretacea and Hemerophila artilineata, and one arctiid species, Spilosoma imparilis, was shaken with n-hexane and the solvent extracts were analyzed by GC-MS. Each extract of the female hemolymph sex-specifically included polyunsaturated hydrocarbons corresponding to the pheromonal epoxy components in addition to many saturated hydrocarbons, but no epoxy compounds were detected in it. Based on this analysis, deuterated polyunsaturated hydrocarbons were injected into the abdomens of two geometrid females, and the labeled epoxy components were successfully yielded from the pheromone glands. This result indicated that the polyunsaturated hydrocarbons occurring in the female hemolymph were direct pheromone precursors, which might be produced outside the pheromone gland, probably in oenocytes associated with abdominal epidermal cells or in the fat body, and transported to the pheromone gland via the hemolymph for their epoxydation and emission into the atmosphere.     

cDNA approaches to isolation of the mouse mutant weaver gene

The mouse autosomal recessive mutant gene weaver (wv) results in abnormalities in cerebellum, substantia nigra and testis. Although a subtracted cDNA library prepared by removing P31 (wv/wv) sequences from a P1 (wv/+) library should contain mainly nonrepetitive neonatal sequences, unfortunately, repetitive sequences still appear during screening. Two clones, one repetitive, the other not, are used to illustrate the problems encountered in attempting to isolate the weaver gene from a subtracted cDNA library.Special issue dedicated to Dr. Sidney Ochs.     

Enhanced aerobic granulation and nitrogen removal by the addition of zeolite powder in a sequencing batch reactor

The aim of this study was to evaluate the impact of zeolite powders on feasibility of rapid aerobic granulation in the column-type sequencing batch reactors. After 90 days' operation, aerobic granular sludge was formed in both reactors by altering influent chemical oxygen demand/nitrogen (COD/N) ratios. R1 with zeolite powders had better removal capabilities of COD and total nitrogen than R2, which was without zeolite powders. Mixed liquor volatile suspended solid concentrations of the two reactors were 7.36 and 5.45 g/L, while sludge volume index (SVI₃₀) values were 34.9 and 47.9 mg/L, respectively. The mean diameters of aerobic granular sludge in the above two reactors were 2.5 and 1.5 mm, respectively. Both reactors achieved the largest simultaneous nitrification and denitrification (SND) efficiency at an influent COD/N ratio of 8; however, R1 exhibited more excellent SND efficiency than R2. The obtained results could provide a novel technique for rapid aerobic granulation and N removal simultaneously, especially when treating nitrogen-rich industrial wastewater.     

Protein Kinase LTRPK1 Influences Cold Adaptation and Microtubule Stability in Rice

Rice LTRPK1, which encodes a member of the casein kinase I family, has been reported to be involved in root development, hormone response, and metabolic processes. Here we further show that LTRPK1 participates in stress resistance by regulating cytoskeleton rearrangement and formation of cold tolerance and adaptation. Semiquantitative RT-PCR analysis revealed enhanced expression of LTRPK1 in plants subject to low-temperature stress at 4 °C, suggesting a role in low-temperature-related cell responses and signal transduction pathways. Further analysis of LTRPK1-deficient transgenic plants showed that under low-temperature treatment, the growth rate of transgenic plant primary roots, which is commonly used as an indicator for cold stress response abilities, was less inhibited than that of control plants. Moreover, damage to the plasma membrane of root cells in LTRPK1-deficient plants was greater than that of controls as measured by relative electrical conductivity (REC). The malondialdehyde (MDA) content of LTRPK1-deficient plants also increased over that of the control, indicating increased plasma membrane permeability. Further immunofluorescence localization observations indicated that microtubules of transgenic plants subject to low temperature disassembled more rapidly, whereas the control plant microtubules in most cells of the root elongation zone kept their normal habitus, which suggested that LTRPK1-deficient plants had reduced capacity to resist low-temperature stress through regulation of microtubule assembly. These results demonstrate involvement of LTRPK1 in low-temperature stress and provide new insight for rice breeding and germplasm innovation to improve crop cold tolerance.     

Chemical synthesis of S-ribosyl-L-homocysteine and activity assay as a LuxS substrate

Bacterial quorum sensing is mediated by autoinducers, small signaling molecules generated by bacteria. It has been proposed that the LuxS enzyme converts S-ribosyl-L-homocysteine to 4,5-dihydroxy-2,3-pentanedione, the precursor of autoinducer 2 (AI-2). We report here a chemical synthesis of S-ribosyl-L-homocysteine and its analogue using Mitsunobu coupling. Chemically synthesized ribosylhomocysteine has been confirmed as a substrate for LuxS in both an enzyme assay and a whole cell quorum sensing assay. The chemical entities of products from the LuxS reaction were also established. Several ribosylhomocysteine analogues have been tested as LuxS inhibitors.     

Comparison and Effects of Acute Lamotrigine Treatment on Extracellular Excitatory Amino Acids in the Hippocampus of PTZ-Kindled Epileptic and PTZ-Induced Status Epilepticus Rats

In this communication, the effect of acute treatment with lamotrigine (LTG) was investigated on release of main excitatory amino acids (EAA) such as glutamate (Glu) and aspartate (Asp) in the hippocampus of pentylenetetrazol (PTZ)-induced and PTZ-kindled freely moving rats using micro dialysis. The results show that, levels of Glu and Asp significantly increased in the rat hippocampus during the seizure/interical periods for PTZ-status epilepticus (SE) and PTZ-kindled epileptic (EP) rats. The levels of Glu and Asp increased more in EP rat hippocampus than in SE rat hippocampus. After administration of 20 mg/kg LTG, the levels of Glu and Asp significantly decreased in the SE and EP rat hippocampus. The results indicate that: (a) excitability of the PTZ-kindled epileptogenic model is higher than that of the status epilepticus model; (b) the modulation of LTG on the EAA neurotransmitters certainly plays an important role in antiepileptic efficacy, especially in PTZ-kindled epileptic model where the release of EAA was influenced more markedly by acute application of 20 mg/kg LTG.     

Genetic Variants in Meiotic Program Initiation Pathway Genes Are Associated with Spermatogenic Impairment in a Han Chinese Population

Background

The meiotic program initiation pathway genes (CYP26B1, NANOS1 and STRA8) have been proposed to play key roles in spermatogenesis.

Objective

To elucidate the exact role of the genetic variants of the meiosis initiation genes in spermatogenesis, we genotyped the potential functional genetic variants of CYP26B1, NANOS1 and STRA8 genes, and evaluated their effects on spermatogenesis in our study population.

Design, Setting, and Participants

In this study, all subjects were volunteers from the affiliated hospitals of Nanjing Medical University between March 2004 and July 2009 (NJMU Infertile Study). Total 719 idiopathic infertile cases were recruited and divided into three groups according to WHO semen parameters: 201 azoospermia patients (no sperm in the ejaculate even after centrifugation), 155 oligozoospermia patients (sperm counts <20×10⁶/ml) and 363 infertility/normozoospermia subjects (sperm counts >20×10⁶/ml). The control group consisted of 383 subjects with normal semen parameters, all of which had fathered at least one child without assisted reproductive technologies.

Measurements

Eight single nucleotide polymorphisms (SNPs) in CYP26B1, NANOS1 and STRA8 genes were determined by TaqMan allelic discrimination assay in 719 idiopathic infertile men and 383 healthy controls.

Results and Limitations

The genetic variant rs10269148 of STRA8 gene showed higher risk of spermatogenic impairment in the groups of abnormospermia (including azoospermia subgroup and oligozoospermia subgroup) and azoospermia than the controls with odds ratios and 95% confidence intervals of 2.52 (1.29–4.94) and 2.92 (1.41–6.06), respectively (P = 0.006, 0.002 respective). Notably, larger sample size studies and in vivo or in vitro functional studies are needed to substantiate the biological roles of these variants.

Conclusions

Our results provided epidemiological evidence supporting the involvement of genetic polymorphisms of the meiotic program initiation genes in modifying the risk of azoospermia and oligozoospermia in a Han-Chinese population.