Noisy-threshold control of cell death

Background  

Cellular responses to death-promoting stimuli typically proceed through a differentiated multistage process, involving a lag phase, extensive death, and potential adaptation. Deregulation of this chain of events is at the root of many diseases. Improper adaptation is particularly important because it allows cell sub-populations to survive even in the continuous presence of death conditions, which results, among others, in the eventual failure of many targeted anticancer therapies.     

Pigment-dispersing factor affects nocturnal activity rhythms, photic entrainment, and the free-running period of the circadian clock in the cricket gryllus bimaculatus

Pigment-dispersing factor (PDF) is a neuropeptide widely distributed in insect brains and plays important roles in the circadian system. In this study, we used RNA interference to study the role of the pigment-dispersing factor (pdf) gene in regulating circadian locomotor rhythms in the cricket, Gryllus bimaculatus. Injections of pdf double-stranded RNA (dspdf) effectively knocked down the pdf mRNA and PDF peptide levels. The treated crickets maintained the rhythm both under light-dark cycles (LD) and constant darkness (DD). However, they showed rhythms with reduced nocturnal activity with prominent peaks at lights-on and lights-off. Entrainability of dspdf-injected crickets was higher than control crickets as they required fewer cycles to resynchronize to the LD cycles shifted by 6 h. The free-running periods of the dspdf-injected crickets were shorter than those of control crickets in DD. These results suggest that PDF is not essential for the rhythm generation but involved in control of the nocturnality, photic entrainment, and fine tuning of the free-running period of the circadian clock.     

High sero-prevalence of caseous lymphadenitis identified in slaughterhouse samples as a consequence of deficiencies in sheep farm management in the state of Minas Gerais, Brazil

Background

Multiple congenital ocular anomalies (MCOA) syndrome is a hereditary congenital eye defect that was first described in Silver colored Rocky Mountain horses. The mutation causing this disease is located within a defined chromosomal interval, which also contains the gene and mutation that is associated with the Silver coat color (PMEL17, exon 11). Horses that are homozygous for the disease-causing allele have multiple defects (MCOA-phenotype), whilst the heterozygous horses predominantly have cysts of the iris, ciliary body or retina (Cyst-phenotype). It has been argued that these ocular defects are caused by a recent mutation that is restricted to horses that are related to the Rocky Mountain Horse breed. For that reason we have examined another horse breed, the Icelandic horse, which is historically quite divergent from Rocky Mountain horses.

Results

We examined 24 Icelandic horses and established that the MCOA syndrome is present in this breed. Four of these horses were categorised as having the MCOA-phenotype and were genotyped as being homozygous for the PMEL17 mutation. The most common clinical signs included megaloglobus, iris stromal hypoplasia, abnormal pectinate ligaments, iridociliary cysts occasionally extending into the peripheral retina and cataracts. The cysts and pectinate ligament abnormalities were observed in the temporal quadrant of the eyes. Fourteen horses were heterozygous for the PMEL17 mutation and were characterized as having the Cyst-phenotype with cysts and occasionally curvilinear streaks in the peripheral retina. Three additional horses were genotyped as PMEL17 heterozygotes, but in these horses we were unable to detect cysts or other forms of anomalies. One eye of a severely vision-impaired 18 month-old stallion, homozygous for the PMEL17 mutation was examined by light microscopy. Redundant duplication of non-pigmented ciliary body epithelium, sometimes forming cysts bulging into the posterior chamber and localized areas of atrophy in the peripheral retina were seen.

Conclusions

The MCOA syndrome is segregating with the PMEL17 mutation in the Icelandic Horse population. This needs to be taken into consideration in breeding decisions and highlights the fact that MCOA syndrome is present in a breed that are more ancient and not closely related to the Rocky Mountain Horse breed.     

Inactivation of template-directed misfolding of infectious prion protein by ozone

Misfolded prions (PrP(Sc)) are well known for their resistance to conventional decontamination processes. The potential risk of contamination of the water environment, as a result of disposal of specified risk materials (SRM), has raised public concerns. Ozone is commonly utilized in the water industry for inactivation of microbial contaminants and was tested in this study for its ability to inactivate prions (263K hamster scrapie = PrP(Sc)). Treatment variables included initial ozone dose (7.6 to 25.7 mg/liter), contact time (5 s and 5 min), temperature (4°C and 20°C), and pH (pH 4.4, 6.0, and 8.0). Exposure of dilute suspensions of the infected 263K hamster brain homogenates (IBH) (0.01%) to ozone resulted in the in vitro destruction of the templating properties of PrP(Sc), as measured by the protein misfolding cyclic amplification (PMCA) assay. The highest levels of prion inactivation (≥4 log(10)) were observed with ozone doses of 13.0 mg/liter, at pH 4.4 and 20°C, resulting in a CT (the product of residual ozone concentration and contact time) value as low as 0.59 mg · liter(-1) min. A comparison of ozone CT requirements among various pathogens suggests that prions are more susceptible to ozone degradation than some model bacteria and protozoa and that ozone treatment may be an effective solution for inactivating prions in water and wastewater.     

Enhancement of ethanol production by simultaneous saccharification and fermentation (SSF) of rice straw using ethoxylated span 20

In this work, four nonionic surfactants based on sorbitan monolaurate (Span 20) were synthesized by introducing ethylene oxide gas (n?=?20, 40, 60, 80 ethylene oxide units) into Span 20 to give four new surfactants with different hydrophilic-lipophilic balance (HLB), namely, E(20), E(40), E(60), and E(80). The structures of the prepared nonionic surfactants were elucidated using Fourier-transform infrared (FT-IR) and (1)H-nuclear magnetic resonance (NMR) spectroscopy. The surface-tension measurements were recorded. The effects of the prepared nonionic surfactants on the simultaneous saccharification and fermentation (SSF) of microwave/alkali-pretreated rice straw to produce ethanol were investigated. From the obtained data, it was found that the addition of the nonionic surfactants at 2.5?g/L had a positive effect on SSF. The maximum ethanol yield (76 and 55%) was obtained after 72?hr for rice straw using Kluyveromyces marxianus and Saccharomyces cerevisiae, respectively. Also, it was found that the ethanol yield increases with increasing HLB of the prepared nonionic surfactants by increasing ethylene oxide units. The adsorption of nonionic surfactants on lignocelluloses is proposed to be due to hydrophobic and hydrogen bonding interactions between nonionic surfactants and the lignin part in the lignocelulose. It can be concluded that additions of surface-active compounds, such as nonionic surfactants, increase enzymatic conversion of rice straw for bioethanol purposes.     

The effect of monosodium glutamate on the cerebellar cortex of male albino rats and the protective role of vitamin C (histological and immunohistochemical study)

Monosodium glutamate (MSG) is a natural constituent of many foods and was reported to have neurotoxic effects. The aim of this study was to investigate the possible toxic effect of MSG on histological and glial fibrillary acidic protein (GFAP) immunohistochemical features of cerebellar cortex of albino rats and to evaluate the possible protective role of vitamin C against this effect. Thirty rats were divided into 3 equal groups. Group I, control; Group II, treated with 3 g/kg/day of MSG and Group III, received 100 mg/kg/day of vitamin C simultaneously with MSG. After 14 days, cerebellar tissues were obtained and processed to prepare sections stained with H&E, toluidine blue. The GFAP was detected immunohistochemically. Histological examination of group II showed degenerative changes as pyknotic Purkinje and granule cells with areas of degeneration surrounded by inflammatory cells in granular layer. However, group III showed more preserved histological structure of cerebellar cortex. Statistical analysis of area percent of the GFAP immunoreaction among studied groups showed significant increase in group III when compared with group I and group II. However, a non significant increase was detected in group II when compared with group I. In conclusion, MSG has neurotoxic effect leading to degenerative changes in neurons and astrocytes in cerebellar cortex of albino rats and vitamin C supplementation could protect from these changes. Getting more attention to the constituents of food products is recommended and vitamin C could be advised to protect people from food oxidants additives.     

Alternating Magnetic Field Induced Membrane Permeability in Erythromycin Magneto-Liposomes A Potential Solution to Antibiotic Resistance

Biophysics - Antibiotic resistance is a serious problem facing the world; it is increasing every year due to over or misuse of antibiotics that led to developing new mechanisms of drug resistance...