mRNA stabilization by poly(A) binding protein is independent of poly(A) and requires translation

Translation and mRNA stability are enhanced by the presence of a poly(A) tail. In vivo, the tail interacts with a conserved polypeptide, poly(A) binding protein (Pab1p). To examine Pab1p function in vivo, we have tethered Pab1p to the 3′ UTR of reporter mRNAs by fusing it to MS2 coat protein and placing MS2 binding sites in the 3′ UTR of the reporter. This strategy allows us to uncouple Pab1p function from its RNA binding activity. We show that mRNAs that lack a poly(A) tail in vivo are stabilized by Pab1p, and that the portions of Pab1p required for stabilization are genetically distinct from those required for poly(A) binding. In addition, stabilization by Pab1p requires ongoing translation of the mRNA. We conclude that the primary, or sole, function of poly(A) with respect to mRNA stability is simply to bring Pab1p to the mRNA, and that mRNA stabilization is an intrinsic property of Pab1p. The approach we describe may be useful in identifying and assaying 3′ UTR regulatory proteins, as it uncouples analysis of function from RNA binding.     

Spatial summation in lateral geniculate nucleus and visual cortex

We have compared the spatial summation characteristics of cells in the primary visual cortex with those of cells in the dorsal lateral geniculate nucleus (LGN) that provide the input to the cortex. We explored the influence of varying the diameter of a patch of grating centred over the receptive field and quantitatively determined the optimal summation diameter and the degree of surround suppression for cells at both levels of the visual system using the same stimulus parameters. The mean optimal summation size for LGN cells (0.90 degrees) was much smaller than that of cortical cells (3.58 degrees). Virtually all LGN cells exhibited strong surround suppression with a mean value of 74%+/-1.61% SEM for the population as a whole. This potent surround suppression in the cells providing the input to the cortex suggests that cortical cells must integrate their much larger summation fields from the low firing rates associated with the suppression plateau of the LGN cell responses. Our data suggest that the strongest input to cortical cells will arise from geniculate cells representing areas of visual space located at the borders of a visual stimulus. We suggest that analysis of response properties by patterns centred over the receptive fields of cells may give a misleading impression of the process of the representation. Analysis of pattern terminations or salient borders over the receptive field may provide much more insight into the processing algorithms involved in stimulus representation.     

X-linked recessive chondrodysplasia punctata: spectrum of arylsulfatase E gene mutations and expanded clinical variability

Partial trisomy of the long arm of chromosome 10 is a well-defined but rare syndrome. Clinical features of this chromosomopathy are a distinctive dysmorphic appearance, developmental delay, growth retardation, and in some cases, abnormalities of the extremities and renal, cardiac and ocular anomalies. This report describes a neonate with symmetric growth retardation and multiple dysmorphic features, in whom chromosomal analysis revealed a partial trisomy of chromosome 10q with a monosomy of the 13q34 region. The phenotype shares many common features with previously published cases. In addition to the typical features, our case also shows renal hypoplasia with early renal insufficiency and some genital anomalies.     

Synergistic effect of interleukin-2 and a vaccine of irradiated melanoma cells transfected to secrete staphylococcal enterotoxin A

We have previously reported that immunization of mice with melanoma cells transfected to secrete the superantigen, Staphylococcal enterotoxin A (SEA), increased the production of antibodies to the B700 melanoma antigen, stimulated the production of endogenous interleukin 2 (IL-2), activated the expression of CD4, CD8 and CD25 T cell markers and enhanced NK cell activity. Now we show that immunization of mice with a vaccine of irradiated sea-transfected melanoma cells coupled with IL-2 therapy was even more effective in inhibiting the growth of primary melanoma tumors and the development of lung metastases than was the irradiated melanoma cell vaccine alone or IL-2 alone. The morphological and immunological effectiveness of the therapy was dose-dependent on IL-2.     

Gene therapy in soft tissue reconstruction

Gene therapy is defined as the introduction of a therapeutic gene into a cell, whose expression can lead to a cure of a disease or offer a transient advantage for tissue growth and regeneration. The delivery of genes can be undertaken for a number of purposes, usually it is attempted to enhance or add a function to a cell or a tissue or to delete or reduce another function. In this brief overview we describe various vehicles and techniques that have been developed to deliver therapeutic genes into cells, such as viral vectors and physical/chemical gene delivery methods including naked DNA and particle-mediated gene transfer, the microseeding technique and the application of lipids. Furthermore we review the potential utility of gene therapy from the perspective of a reconstructive surgeon. Several tissues will be discussed, particularly muscle, tendon, nerve, bone, skin and wounds.