Integration of binocular optic flow in cervical neck motor neurons of the fly

Global visual motion elicits an optomotor response of the eye that stabilizes the visual input on the retina. Here, we analyzed the neck motor system of the blowfly to understand binocular integration of visual motion information underlying a head optomotor response. We identified and characterized two cervical nerve motor neurons (called CNMN6 and CNMN7) tuned precisely to an optic flow corresponding to pitch movements of the head. By means of double recordings and dye coupling, we determined that these neurons are connected ipsilaterally to two vertical system cells (VS2 and VS3), and contralaterally to one horizontal system cell (HSS). In addition, CNMN7 turned out to be connected to the ipsilateral CNMN6 and to its contralateral counterpart. To analyze a potential function of this circuit, we performed behavioral experiments and found that the optomotor pitch response of the fly head was only observable when both eyes were intact. Thus, this neural circuit performs two visuomotor transformations: first, by integrating binocular visual information it enhances the tuning to the optic flow resulting from pitch movements of the head, and second it could assure an even head declination by coordinating the activity of the CNMN7 neurons on both sides.     

Antigen-specificity of oligoclonal abnormal protein bands in multiple myeloma after allogeneic stem cell transplantation

Myeloma patients may develop oligoclonal immunoglobulins, so-called abnormal protein bands (APB), after stem cell transplantation. APB do not correspond to the patient's paraprotein and confer a good prognosis. We set out to investigate whether such APB represent a humoral anti-myeloma immune response by screening immunoglobulins of 15 myeloma patients after allogeneic stem cell transplantation and a control group of healthy donors for reactivity with myeloma protein extracts. While the immunoglobulins of healthy donors did not react with myeloma protein extracts, patient-derived immunoglobulins showed variable levels of interaction, depending on the presence of APB on immunofixation. Most commonly, we detected interactions with heat-shock proteins, followed by neutral alpha-glucosidase, alpha-enolase and vimentin, as well as proliferating cell nuclear antigen and MAGEA4. More than 80% of targets were upregulated in myeloma. Heat-shock protein 60 (HSP60) was subsequently evaluated as an exemplary antigen. We found that HSP60 was aberrantly displayed on the surface of primary myeloma cells. Indeed, patient-derived APB-containing immunoglobulins recognized surface HSP60 suggesting that this antigen becomes accessible to the immune system after aberrant membrane exposition. We conclude that immunoglobulin fractions with APB recognize recurrent myeloma antigens and that this humoral response may contribute to the more favorable prognosis in patients with APB.     

Structure, chromosomal localization, and expression of the gene for mouse ecto-mono(ADP-ribosyl)transferase ART5

Mono(ADP-ribosyl)transferases regulate the function of target proteins by attaching ADP-ribose to specific amino acid residues in their target proteins. The purpose of this study was to determine the structure, chromosomal localization, and expression profile of the gene for mouse ecto-ADP-ribosyltransferase ART5. Southern blot analyses indicate that Art5 is a single copy gene which maps to mouse chromosome 7 at offset 49.6 cM in close proximity to the Art1, Art2a and Art2b genes. Northern blot and RT-PCR analyses demonstrate prominent expression of Art5 in testis, and lower levels in cardiac and skeletal muscle. Sequence analyses reveal that the Art5 gene encompasses six exons spanning 8 kb of genomic DNA. The 5' end of the Art5 gene overlaps with that of the Art1 gene. A single long exon encodes the predicted ART5 catalytic domain. Separate exons encode the N-terminal leader peptide and a hydrophilic C-terminal extension. Sequencing of RT-PCR products and ESTs identified six splice variants. The deduced amino acid sequence of ART5 shows 87% sequence identity to its orthologue from the human, and 37 and 32% identity to its murine paralogues ART1 and ART2. Unlike ART1 and ART2, ART5 lacks a glycosylphosphatidylinositol-anchor signal sequence and is predicted to be a secretory enzyme. This prediction was confirmed by transfecting an Art5 cDNA expression construct into Sf9 insect cells. The secreted epitope-tagged ART5 protein resembled rat ART2 in exhibiting potent NAD-glycohydrolase activity. This study provides important experimental tools to further elucidate the function of ART5.     

Hierarchy of nonhomologous end-joining, single-strand annealing and gene conversion at site-directed DNA double-strand breaks

In mammalian cells, DNA double-strand breaks (DSBs) are repaired by three pathways, nonhomologous end-joining (NHEJ), gene conversion (GC) and single-strand annealing (SSA). These pathways are distinct with regard to repair efficiency and mutagenic potential and must be tightly controlled to preserve viability and genomic stability. Here, we employed chromosomal reporter constructs to characterize the hierarchy of NHEJ, GC and SSA at a single I-SceI-induced DSB in Chinese hamster ovary cells. We discovered that the use of GC and SSA was increased by 6- to 8-fold upon loss of Ku80 function, suggesting that NHEJ is dominant over the other two pathways. However, NHEJ efficiency was not altered if GC was impaired by Rad51 knockdown. Interestingly, when SSA was made available as an alternative mode for DSB repair, loss of Rad51 function led to an increase in SSA activity at the expense of NHEJ, implying that Rad51 may indirectly promote NHEJ by limiting SSA. We conclude that a repair hierarchy exists to limit the access of the most mutagenic mechanism, SSA, to the break site. Furthermore, the cellular choice of repair pathways is reversible and can be influenced at the level of effector proteins such as Ku80 or Rad51.     

A predictive model for respiratory syncytial virus (RSV) hospitalisation of premature infants born at 33–35 weeks of gestational age,based on data from the Spanish FLIP study

Background

The aim of this study, conducted in Europe, was to develop a validated risk factor based model to predict RSV-related hospitalisation in premature infants born 33–35 weeks'' gestational age (GA).

Methods

The predictive model was developed using risk factors captured in the Spanish FLIP dataset, a case-control study of 183 premature infants born between 33–35 weeks'' GA who were hospitalised with RSV, and 371 age-matched controls. The model was validated internally by 100-fold bootstrapping. Discriminant function analysis was used to analyse combinations of risk factors to predict RSV hospitalisation. Successive models were chosen that had the highest probability for discriminating between hospitalised and non-hospitalised infants. Receiver operating characteristic (ROC) curves were plotted.

Results

An initial 15 variable model was produced with a discriminant function of 72% and an area under the ROC curve of 0.795. A step-wise reduction exercise, alongside recalculations of some variables, produced a final model consisting of 7 variables: birth ± 10 weeks of start of season, birth weight, breast feeding for ≤ 2 months, siblings ≥ 2 years, family members with atopy, family members with wheeze, and gender. The discrimination of this model was 71% and the area under the ROC curve was 0.791. At the 0.75 sensitivity intercept, the false positive fraction was 0.33. The 100-fold bootstrapping resulted in a mean discriminant function of 72% (standard deviation: 2.18) and a median area under the ROC curve of 0.785 (range: 0.768–0.790), indicating a good internal validation. The calculated NNT for intervention to treat all at risk patients with a 75% level of protection was 11.7 (95% confidence interval: 9.5–13.6).

Conclusion

A robust model based on seven risk factors was developed, which is able to predict which premature infants born between 33–35 weeks'' GA are at highest risk of hospitalisation from RSV. The model could be used to optimise prophylaxis with palivizumab across Europe.