In Situ Electric-Field Control of THz Nonreciprocal Directional Dichroism in the Multiferroic Ba_{2}CoGe_{2}O_{7}.

Nonreciprocal directional dichroism, also called the optical-diode effect, is an appealing functional property inherent to the large class of noncentrosymmetric magnets. However, the in situ electric control of this phenomenon is challenging as it requires a set of conditions to be fulfilled: Special symmetries of the magnetic ground state, spin excitations with comparable magnetic- and electric-dipole activity, and switchable electric polarization. We demonstrate the isothermal electric switch between domains of Ba_{2}CoGe_{2}O_{7} possessing opposite magnetoelectric susceptibilities. Combining THz spectroscopy and multiboson spin-wave analysis, we show that unbalancing the population of antiferromagnetic domains generates the nonreciprocal light absorption of spin excitations.

Systemic injection of AAV9-GDNF provides modest functional improvements in the SOD1G93A ALS rat but has adverse side effects.

Injecting proteins into the central nervous system that stimulate neuronal growth can lead to beneficial effects in animal models of disease. In particular, glial cell line-derived neurotrophic factor (GDNF) has shown promise in animal and cell models of Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis (ALS). Here, systemic AAV9-GDNF was delivered via tail vein injections to young rats to determine whether this could be a safe and functional strategy to treat the SOD1G93A rat model of ALS and, therefore, translated to a therapy for ALS patients. We found that GDNF administration in this manner resulted in modest functional improvement, whereby grip strength was maintained for longer and the onset of forelimb paralysis was delayed compared to non-treated rats. This did not, however, translate into an extension in survival. In addition, ALS rats receiving GDNF exhibited slower weight gain, reduced activity levels and decreased working memory. Collectively, these results confirm that caution should be applied when applying growth factors such as GDNF systemically to multiple tissues.

C9orf72 is required for proper macrophage and microglial function in mice.

Expansions of a hexanucleotide repeat (GGGGCC) in the noncoding region of the C9orf72 gene are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Decreased expression of C9orf72 is seen in expansion carriers, suggesting that loss of function may play a role in disease. We found that two independent mouse lines lacking the C9orf72 ortholog (3110043O21Rik) in all tissues developed normally and aged without motor neuron disease. Instead, C9orf72 null mice developed progressive splenomegaly and lymphadenopathy with accumulation of engorged macrophage-like cells. C9orf72 expression was highest in myeloid cells, and the loss of C9orf72 led to lysosomal accumulation and altered immune responses in macrophages and microglia, with age-related neuroinflammation similar to C9orf72 ALS but not sporadic ALS human patient tissue. Thus, C9orf72 is required for the normal function of myeloid cells, and altered microglial function may contribute to neurodegeneration in C9orf72 expansion carriers.

Cortical modulation of pain.

The sensation commonly referred to as 'pain' has two components. The first is the sensory-discriminative component and provides information on location, modality and intensity of stimuli. The second is the affective-motivational component and refers to the emotional responses (fear, distress etc.) and the urge to respond evoked by the somatic sensation, and at the cortical level these two components appear to be located in different regions. The cortex probably influences pain by two different mechanisms. There is good evidence that the cortex can reduce pain by interrupting the transmission of noxious information from the spinal cord level by activating descending pain modulatory systems located in the brainstem. Less well established is the idea that modulation can also occur at the cortical level to change the affective-motivational aspects of nociception so that pain is perceived but looses its emotional and aversive component.

Futile caspase-8 activation during the apoptotic cell death induced by DNA damaging agents in human B-lymphoblasts.

Caspase-8 plays an essential role in apoptosis induced by Fas activation. Moreover, caspase-8 can be processed also in response to exposure to genotoxic agents. To decipher the role of caspase-8 in DNA damaging agent (DDA)-induced apoptosis as well as the pathway(s) leading to its activation in response to genotoxic stress, we investigated caspase-8 processing induced by ionizing radiation (IR) or mitomycin C (MMC) treatment in human B-lymphoblasts. Altogether, our observations establish that caspase-8 is actively processed in both receptor-mediated and DDA-induced cell death. However, while Fas-dependent apoptosis absolutely required caspase-8 activity, it is not necessary for completion of the apoptotic program induced by IR and MMC. Experiments performed to understand the molecular pathway(s) of the caspase-8 activation after DDA demonstrated that for both IR and MMC, the Fas/Fas-L interaction is dispensable. Data obtained from caspase inhibitors and from lymphoblasts carrying mutations in ATM and FANCC proteins, involved in DDA response, clearly showed that distinct mechanisms are responsible for caspase-8 activation by IR and MMC in B-lymphoblasts. IR-dependent processing of caspase-8 involves ATM, mitochondrial collapse, FANCC, and caspase-3 activation. Caspase-8 activation by MMC evokes the mitochondrial pathways involving FANCC but not ATM. Collectively, our data indicate that caspase-8 activation is essentially a bystander effect and not a major determinant of the behavior of DDA-exposed cells.

ATM protein is required for radiation-induced apoptosis and acts before mitochondrial collapse.

PURPOSE: To define the role of the ataxia telangiectasia (A-T) mutated gene (ATM) in activation and progress of apoptosis. MATERIAL AND METHODS: Three normal and three A-T EBV-transformed cell lines were studied. Following irradiation (IR), Fas activation or ceramide exposure, viability and apoptosis were measured by trypan blue dye exclusion assay and as sub-G1 cell fraction by flow cytometric analysis of propidium iodide stained cultures, respectively. Activation of caspase-3 was evaluated by immunoblot and by an in vitro activity assay on cytosolic cell extracts. To assess changes in mitochondrial potential and reactive oxygen species, cells were stained by 3,3'-dihexyloxacarbocynine iodide or hydroethidine, respectively, and scored by flow cytometry. RESULTS: The observations establish that A-T cells are equipped with a proficient apoptotic machinery, as demonstrated by their ability to undergo mitochondrial collapse and caspase-3 activation after Fas activation or ceramide treatment. Both treatments have a similar cytotoxic effect on normal and A-T cells. In contrast, in spite of the stronger cytotoxicity induced by IR exposure, irradiated A-T cells are unable to undergo mitochondrial collapse and caspase-3 activation. CONCLUSIONS: The data indicate that ATM is necessary in the initiation of molecular pathway(s) leading to IR-induced apoptosis, and suggest that increased radiosensitivity of A-T cells is more likely a direct consequence of necrotic cell death.

Loss of the Fanconi anemia group C protein activity results in an inability to activate caspase-3 after ionizing radiation.

Fanconi anemia (FA) is a human genetic disease featuring cancer predisposition, genetic instability and DNA damage hypersensitivity. Although abnormalities in DNA repair and cell cycle checkpoint have been proposed as the underlying defect in this syndrome, these hypotheses did not provide full explanations of the complex phenotype. Although not exclusive of such possibilities, alterations in the control of apoptosis might account for the pleiotropic phenotype of this syndrome. We and others have previously reported a deregulation of the apoptotic response to mitomycin C, suggesting that the products of the Fanconi anemia group C protein (FANCC) contribute to the regulation of apoptosis. To explore the functional importance of the apoptotic alterations in FA we analyzed biochemical steps of the execution phase of apoptosis stimulated by another DNA damaging agent, the gamma-ray using FA cell lines derived from complementation group C (FA-C) independent patients. It is shown that the poly(ADP-ribose) polymerase, a target of caspase-3, is not cleaved in FA-C after ionizing radiation (IR). Moreover, caspase-3 is not processed in its active form and, its activity is not increased by IR in FA-C cells compared to normal cells. Altogether, these results demonstrate that loss of the FANCC activity results in a deficiency of the IR-induced apoptosis which is due to an inability to activate caspase-3. Our work suggests that apoptosis signaling induced by mitomycin C and IR is subject to common regulation involving the FANCC protein.

Integration of chicken cytogenetic and genetic maps: 18 new polymorphic markers isolated from BAC and PAC clones.

As an approach to integrate the chicken genetic and cytogenetic maps, bacterial artificial chromosome (BAC) and P1-derived artificial chromosome (PAC) clones were localized by fluorescence in situ hybridization (FISH) on chromosomes and by genetic mapping on the East Lansing and Compton reference families. Some of the clones used in this study were previously selected for the presence of potentially polymorphic (CA)n repeats and a microsatellite marker was developed when possible for genetic mapping. For other clones, a single strand conformational polymorphism (SSCP) was developed and used for this purpose. Between the two approaches, 18 markers linking the cytogenetic and genetic maps, seven on macrochromosomes and 11 on microchromosomes, were generated. Our results enabled the assignment and orientation of a linkage group to chromosome 3, together with the assignment of linkage groups to eight different microchromosomes, a fraction of the genome lacking mapping data and for which the degree of coverage by the genetic map was not well estimated previously.