Exacerbation of experimental autoimmune encephalomyelitis in prion protein (PrPc)-null mice: evidence for a critical role of the central nervous system

<p>Abstract</p> <p>Background</p> <p>The cellular prion protein (PrPc) is a host-encoded glycoprotein whose transconformation into PrP scrapie (PrPSc) initiates prion diseases. The role of PrPc in health is still obscure, but many candidate functions have been attributed to the protein, both in the immune and the nervous systems. Recent data show that experimental autoimmune encephalomyelitis (EAE) is worsened in mice lacking PrPc. Disease exacerbation has been attributed to T cells that would differentiate into more aggressive effectors when deprived of PrPc. However, alternative interpretations such as reduced resistance of neurons to autoimmune insult and exacerbated gliosis leading to neuronal deficits were not considered.</p> <p>Method</p> <p>To better discriminate the contribution of immune cells versus neural cells, reciprocal bone marrow chimeras with differential expression of PrPc in the lymphoid or in the central nervous system (CNS) were generated. Mice were subsequently challenged with MOG_35-55peptide and clinical disease as well as histopathology were compared in both groups. Furthermore, to test directly the T cell hypothesis, we compared the encephalitogenicity of adoptively transferred PrPc-deficient versus PrPc-sufficient, anti-MOG T cells.</p> <p>Results</p> <p>First, EAE exacerbation in PrPc-deficient mice was confirmed. Irradiation exacerbated EAE in all the chimeras and controls, but disease was more severe in mice with a PrPc-deleted CNS and a normal immune system than in the reciprocal construction. Moreover, there was no indication that anti-MOG responses were different in PrPc-sufficient and PrPc-deficient mice. Paradoxically, PrPc-deficient anti-MOG 2D2 T cells were less pathogenic than PrPc-expressing 2D2 T cells.</p> <p>Conclusions</p> <p>In view of the present data, it can be concluded that the origin of EAE exacerbation in PrPc-ablated mice resides in the absence of the prion protein in the CNS. Furthermore, the absence of PrPc on both neural and immune cells does not synergize for disease worsening. These conclusions highlight the critical role of PrPc in maintaining the integrity of the CNS in situations of stress, especially during a neuroinflammatory insult.</p

Protease-Resistant Prions Selectively Decrease Shadoo Protein

The central event in prion diseases is the conformational conversion of the cellular prion protein (PrPC) into PrPSc, a partially protease-resistant and infectious conformer. However, the mechanism by which PrPSc causes neuronal dysfunction remains poorly understood. Levels of Shadoo (Sho), a protein that resembles the flexibly disordered N-terminal domain of PrPC, were found to be reduced in the brains of mice infected with the RML strain of prions [1], implying that Sho levels may reflect the presence of PrPSc in the brain. To test this hypothesis, we examined levels of Sho during prion infection using a variety of experimental systems. Sho protein levels were decreased in the brains of mice, hamsters, voles, and sheep infected with different natural and experimental prion strains. Furthermore, Sho levels were decreased in the brains of prion-infected, transgenic mice overexpressing Sho and in infected neuroblastoma cells. Time-course experiments revealed that Sho levels were inversely proportional to levels of protease-resistant PrPSc. Membrane anchoring and the N-terminal domain of PrP both influenced the inverse relationship between Sho and PrPSc. Although increased Sho levels had no discernible effect on prion replication in mice, we conclude that Sho is the first non-PrP marker specific for prion disease. Additional studies using this paradigm may provide insight into the cellular pathways and systems subverted by PrPSc during prion disease

Protocol for augmented shoot organogenesis in selected variety of soybean [<i>Glycine</i><i style="mso-bidi-font-style: normal"> max</i> L. (Merr.)]

729-734<span style="mso-bidi-font-size:9.0pt;letter-spacing: -.1pt" lang="EN-GB">Development of a reproducible, versatile and efficient in vitro plant regeneration system is highly warranted for Indian soybean varieties for their mass multiplication in view of their commercial significance. Accordingly a protocol for direct shoot organogenesis in soybean variety JS 335 has been developed. Using cotyledonary node explants significant organogenic responses, mean shoot number and shoot length were observed when these were incubated on MS medium supplemented with 0.89 µM Benzyladenine (BA) and 5 <span style="mso-bidi-font-size:9.0pt;mso-fareast-font-family: TimesNewRoman;letter-spacing:-.1pt" lang="EN-GB">μ<span style="mso-bidi-font-size: 9.0pt;letter-spacing:-.1pt" lang="EN-GB">g/L triacontanol (TRIA) where in 9.3 ± 0.5 shoots were obtained. TRIA at 5 <span style="mso-bidi-font-size: 9.0pt;mso-fareast-font-family:TimesNewRoman;letter-spacing:-.1pt" lang="EN-GB">μg /L able to produce 6.8 ± 0.5 shoot buds in presence of 0.98 µ<i style="mso-bidi-font-style: normal">M IBA and 0.89 µM BA. Highest mean shoot buds (14.0 ± 0.5 and 9.0 ± 0.5) and mean shoot length (4.6 ± 0.3 and 10.0 ± 0.7) were obtained when cotyledonary node and shoot tip explants were cultured on MS medium containing 0.14 µM gibberellic acid (GA3), 0.89 µM BA and 5<span style="mso-bidi-font-size:9.0pt;mso-fareast-font-family: TimesNewRoman;letter-spacing:-.1pt" lang="EN-GB"> μ<span style="mso-bidi-font-size: 9.0pt;letter-spacing:-.1pt" lang="EN-GB">g/L TRIA. Moreover, TRIA supported highest mean root number (6.3±0.5) and root length (21.5 ± 0.57 cm). Field survival of in vitro derived plants of TRIA treatment was 70% and the overall growth and seed yield was also significantly better than control plants. This protocol may be used for improving the in vitro regeneration of soybean variety JS 335 for transformation studies. </span

Irigenin – an isoflavone: a brief study on structural and optical properties

Irigenin, an isoflavone (mol. formula = C18H16O8), was isolated from the plant Iris hookeriana using dichloromethane as solvent. The compound was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible spectroscopy measurements. Structural analysis of XRD data confirmed the orthorhombic structure for the compound. The microstructure of the compound is an aggregate of microcrystals with an irregular morphology. From the UV-visible spectroscopy, the present compound shows indirect allowed transition with an optical band gap (Eg) of around 3.25 eV. The present optical properties of the compound can be utilized in flexible organic electronics applications