Interactions between beta-neuregulin and neurotrophins in motor neuron apoptosis

Neuregulins play a major role in the formation and stabilization of neuromuscular junctions, and are produced by both motor neurons and muscle. Although the effects and mechanism of neuregulins on skeletal muscle (e.g. regulation of acetylcholine receptor expression) have been studied extensively, the effects of neuregulins on motor neurons remain unknown. We report that neuregulin-1beta (NRGbeta1) inhibited apoptosis of rat motor neurons for up to 7 days in culture by a phosphatidylinositol 3 kinase-dependent pathway and synergistically enhanced motor neuron survival promoted by glial-derived neurotrophic factor (GDNF). However, binding of neurotrophins, including brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), to the p75 neurotrophin receptor (p75NTR) abolished the neuregulin anti-apoptotic effect on motor neurons. Inhibitors of the c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase prevented motor neuron death caused by co-incubation of NRGbeta1 and BDNF or NGF, as well as by trophic factor deprivation. Motor neuron apoptosis resulting from both trophic factor deprivation and exposure to NRGbeta1 plus neurotrophins required the induction of neuronal nitric oxide synthase and peroxynitrite formation. Because motor neurons express both p75NTR and neuregulin erbB receptors during the period of embryonic programmed cell death, motor neuron survival may be the result of complex interactions between trophic and death factors, which may be the same molecules acting in different combinations.     

Dietary flaxseed's protective effects on body tissues of mice after oral exposure to xylene

Xylene is a common pollutant in the environment that enters the body of animals and humans in various ways, but most often through the respiratory tract and adversely affects their overall health. However, xylene effects after oral exposure have not been sufficiently studied. This study aimed to investigate the effects of xylene exposure on the mouse organism and to identify possible beneficial effects of flaxseed on such exposure. Eighty mice were divided into four groups: control group C (basal diet + no xylene exposure), group X (oral exposure by 400 mg/kg/day xylene), group F (10% flaxseed supplementation of basal diet), and group XF (10% dietary flaxseed + oral exposure by xylene). Experimental trial took 14 days. Clinical examination, spectroscopic analysis of tissue aminotransferases, total lactate dehydrogenase (TLDH), and acetylcholinesterase (AchE) activities, electrophoretic analysis of LDH isoenzymes, western blot and immunohistochemical analysis of apoptosis as well as routine histology of the kidneys and jejunum, and transmission electron microscopy of the liver were performed. Marked restlessness in group X and high weight losses in mice of all groups were recorded during the experiment. Xylene promoted apoptosis (caspase-3 expression) without causing marked structural changes in the liver and jejunum, although renal cortex structure was affected adversely. In the brain, liver, and kidney of mice, xylene increased levels of liver transaminases, LDH, and decreased AchE activities, reflecting cell membrane damage. Flaxseed feeding improved animal behaviour, leakage of enzymes and prevented selected tissue toxic damage induced by xylene by protecting cell membrane integrity and fluidity and by suppressing apoptosis. These results point at the protective effect of flaxseed consumption on mice.     

Dynamics of cohesin subunits in grasshopper meiotic divisions

The cohesin complex plays a key role for the maintenance of sister chromatid cohesion and faithful chromosome segregation in both mitosis and meiosis. This complex is formed by two structural maintenance of chromosomes protein family (SMC) subunits and two non-SMC subunits: an α-kleisin subunit SCC1/RAD21/REC8 and an SCC3-like protein. Several studies carried out in different species have revealed that the distribution of the cohesin subunits along the chromosomes during meiotic prophase I is not regular and that some subunits are distinctly incorporated at different cell stages. However, the accurate distribution of the different cohesin subunits in condensed meiotic chromosomes is still controversial. Here, we describe the dynamics of the cohesin subunits SMC1α, SMC3, RAD21 and SA1 during both meiotic divisions in grasshoppers. Although these subunits show a similar patched labelling at the interchromatid domain of metaphase I bivalents, SMCs and non-SMCs subunits do not always colocalise. Indeed, SA1 is the only cohesin subunit accumulated at the centromeric region of all metaphase I chromosomes. Additionally, non-SMC subunits do not appear at the interchromatid domain in either single X or B chromosomes. These data suggest the existence of several cohesin complexes during metaphase I. The cohesin subunits analysed are released from chromosomes at the beginning of anaphase I, with the exception of SA1 which can be detected at the centromeres until telophase II. These observations indicate that the cohesin components may be differentially loaded and released from meiotic chromosomes during the first and second meiotic divisions. The roles of these cohesin complexes for the maintenance of chromosome structure and their involvement in homologous segregation at first meiotic division are proposed and discussed.     

Multiplex PCR for detection of Escherichia coli O157:H7 in foods

Escherichia coli O157:H7 is well known enterohemorrhagic pathogen responsible for infections among animals including a man. The main source of this bacterium is cattle, that is mostly asymptomatic and through that E. coli O157:H7 can simple transfer to food products. Therefore, there is a need for rapid, sensitive and specific detection method. The present work is focused on its detection by a heptaplex polymerase chain reaction, which targets genes from known virulent regions of E. coli O157:H7. According to obtained results this approach is able to reach the detection sensitivity of 4 colony-forming units (CFU) from a culture and 6 and 8 CFU from milk and meat samples, respectively, independently of tested sample volume.     

Lyme borreliosis—analysis of the trends in Slovakia, 1999–2008

Lyme borreliosis (LB) presents as one of the most frequent tick-borne diseases in Europe with more than 85,000 reported cases every year. The transport of this disease on humans is by tick species of the genus Ixodes. In our work, we aimed to perform a retrospective analysis of the incidence and seasonality of Lyme borreliosis during the period 1999–2008 in Slovakia. For our analysis, we used all the relevant data about the patients with Lyme borreliosis reported in the Epidemiological Informative System of Communicable Diseases in Slovakia during the decade of 1999–2008. During the observed period, there were 7,349 reported cases of LB in Slovakia. Whereas the incidence of early localized infection did not change during the observed period, there was a significant increase in the incidence of early disseminated infection and late persistent infection of LB. Seventy per cent of all patients was infected by tick bite. LB was more frequently reported in females than in males (56.1% vs. 43.9%; p < 0.05), and the most involved age group was the productive age (15–64 years). The incidence of disseminated infection and persistent infection was rising with increasing age. Regarding the seasonality of LB, we found the highest incidence during the summer months. Comparing the situation of LB in 1999 and 2008, significant increase in the number of reported cases was in April and June and from September to November (p < 0.05). Our epidemiological analysis confirmed that Lyme borreliosis requires increased attention due to its increasing incidence.     

The cohesin subunit RAD21L functions in meiotic synapsis and exhibits sexual dimorphism in fertility

The cohesin complex is a ring-shaped proteinaceous structure that entraps the two sister chromatids after replication until the onset of anaphase when the ring is opened by proteolytic cleavage of its α-kleisin subunit (RAD21 at mitosis and REC8 at meiosis) by separase. RAD21L is a recently identified α-kleisin that is present from fish to mammals and biochemically interacts with the cohesin subunits SMC1, SMC3 and STAG3. RAD21L localizes along the axial elements of the synaptonemal complex of mouse meiocytes. However, its existence as a bona fide cohesin and its functional role awaits in vivo validation. Here, we show that male mice lacking RAD21L are defective in full synapsis of homologous chromosomes at meiotic prophase I, which provokes an arrest at zygotene and leads to total azoospermia and consequently infertility. In contrast, RAD21L-deficient females are fertile but develop an age-dependent sterility. Thus, our results provide in vivo evidence that RAD21L is essential for male fertility and in females for the maintenance of fertility during natural aging.     

Identification of Selective Small Molecule Inhibitors of the Nucleotide-Binding Oligomerization Domain 1 (NOD1) Signaling Pathway

NOD1 is an intracellular pattern recognition receptor that recognizes diaminopimelic acid (DAP), a peptidoglycan component in gram negative bacteria. Upon ligand binding, NOD1 assembles with receptor-interacting protein (RIP)-2 kinase and initiates a signaling cascade leading to the production of pro-inflammatory cytokines. Increased NOD1 signaling has been associated with a variety of inflammatory disorders suggesting that small-molecule inhibitors of this signaling complex may have therapeutic utility. We utilized a cell-based screening approach with extensive selectivity profiling to search for small molecule inhibitors of the NOD1 signaling pathway. Via this process we identified three distinct chemical series, xanthines (SB711), quinazolininones (GSK223) and aminobenzothiazoles (GSK966) that selectively inhibited iE-DAP-stimulated IL-8 release via the NOD1 signaling pathway. All three of the newly identified compound series failed to block IL-8 secretion in cells following stimulation with ligands for TNF receptor, TLR2 or NOD2 and, in addition, none of the compound series directly inhibited RIP2 kinase activity. Our initial exploration of the structure-activity relationship and physicochemical properties of the three series directed our focus to the quinazolininone biarylsulfonamides (GSK223). Further investigation allowed for the identification of significantly more potent analogs with the largest boost in activity achieved by fluoro to chloro replacement on the central aryl ring. These results indicate that the NOD1 signaling pathway, similarly to activation of NOD2, is amenable to modulation by small molecules that do not target RIP2 kinase. These compounds should prove useful tools to investigate the importance of NOD1 activation in various inflammatory processes and have potential clinical utility in diseases driven by hyperactive NOD1 signaling.