Deacetylase inhibitors increase muscle cell size by promoting myoblast recruitment and fusion through induction of follistatin

Fusion of undifferentiated myoblasts into multinucleated myotubes is a prerequisite for developmental myogenesis and postnatal muscle growth. We report that deacetylase inhibitors favor the recruitment and fusion of myoblasts into preformed myotubes. Muscle-restricted expression of follistatin is induced by deacetylase inhibitors and mediates myoblast recruitment and fusion into myotubes through a pathway distinct from those utilized by either IGF-1 or IL-4. Blockade of follistatin expression by RNAi-mediated knockdown, functional inactivation with either neutralizing antibodies or the antagonist protein myostatin, render myoblasts refractory to HDAC inhibitors. Muscles from animals treated with the HDAC inhibitor trichostatin A display increased production of follistatin and enhanced expression of markers of regeneration following muscle injury. These data identify follistatin as a central mediator of the fusigenic effects exerted by deacetylase inhibitors on skeletal muscles and establish a rationale for their use to manipulate skeletal myogenesis and promote muscle regeneration.     

alpha-Tubulin and acetylated alpha-tubulin during ovarian follicle differentiation in the lizard Podarcis sicula Raf

During most of the previtellogenic oocyte growth, the follicular epithelium of the lizard Podarcis sicula shows a polymorphic structure, due to the presence of different follicle cells. These include small cells which divide and move from the periphery of the follicle to the oocyte surface, intermediate cells which represent an initial step in the process of cell enlargement, and large pyriform cells engaged in the transport of different materials to the oocyte through intercellular bridges. We have studied, by immunolocalization and immunoblotting, the localization of alpha-tubulin and its acetylated form in different follicle cells and in the oocyte during the main steps of ovarian follicle differentiation. Our results indicate that alpha-tubulin is present in all follicle cells at different stages of ovarian follicle differentiation, while its acetylated form is detectable exclusively in the small proliferating and migrating follicle cells. In pyriform cells, alpha-tubulin is localized around the nucleus, extends to the cell apex, and crosses the zona pellucida into the oocyte cortex. The presence of acetylated tubulin in the small follicle cells may be related to the proliferation and/or migration of these cells. The absence of acetylated tubulin form in the cytoplasm of intermediate and pyriform cells can be related to the colocalization of alpha-tubulin with the keratin cytoskeleton in these cells, as detected by confocal microscopy. We have also identified the colocalization of alpha-tubulin with keratin in the cortical region of the oocyte, in particular when the cortex is engaged in the uptake of the yolk proteins.     

Expression profiling of mammalian microRNAs uncovers a subset of brain-expressed microRNAs with possible roles in murine and human neuronal differentiation

Background  

The microRNAs (miRNAs) are an extensive class of small noncoding RNAs (18 to 25 nucleotides) with probable roles in the regulation of gene expression. In Caenorhabditis elegans, lin-4 and let-7 miRNAs control the timing of fate specification of neuronal and hypodermal cells during larval development. lin-4, let-7 and other miRNA genes are conserved in mammals, and their potential functions in mammalian development are under active study.     

The limits to genomic predictions: role of sigma(N) in environmental stress survival of Pseudomonas putida

Based on genomic data and on the phenotypes of an FlhF mutant of Pseudomonas putida, the alternative sigma factor sigma(N) (sigma(54)) has been proposed to play a key role in survival to various nutritional and environmental stresses in this bacterium. Quite in contrast, we show that unlike sigma(S) (sigma(38)) the loss of sigma(N) does not impair to any significant extent the ability of P. putida to survive long-term starvation. rpoN mutants (lacking sigma(N)) are indistinguishable from the wild-type with respect to solvent tolerance, resistance to heat shock or sensitivity to hydrogen peroxide. These data suggest that while sigma(N) is a key component of expression of alternative biodegradative pathways for unusual carbon sources (i.e. m-xylene or dimethylphenols), its loss does not compromise bacterial endurance to gross types of environmental stress. Moreover, these results point out the limitations, if not the deception, of genomic predictions when confronted with experimental data.     

Single-chain antibody fragments specific to the hepatitis B surface antigen, produced in recombinant tobacco cell cultures

An anti-hepatitis B surface antigen (HBsAg), single-chain Fv antibody fragment (scFv) with a 6-histidine N-terminal tag was produced in cultured transgenic tobacco cells. Western blot and antigen-specific chromatography showed high levels of biologically active scFv in the culture supernatant (1 mg l^–1) and in cells (5 mg kg^–1). A simple one-step scFv purification was developed using immobilized metal ion affinity chromatography.     

Reproduction, age, growth and mortality of axillary seabream, Pagellus acarne (Sparidae), from the Canarian archipelago

Axillary seabream Pagellus acarne (Risso 1826) caught off the Canary Islands from January 1991 to December 1994 were studied. The length range of the catches was between 11 and 31 cm, with a modal distribution between 17 and 21 cm. The overall ratio of males to females was 1:1.74. Males were observed up to a length of 24 cm. Hermaphrodites were recorded at lengths between 15 and 23 cm. The species was characterized by protandric hermaphroditism. The reproductive season extended from October to March, with a peak in spawning activity in December–January. The size at sexual maturity was 15.8 cm total length (2 years old) for males and 19.4 cm total length (3 years old) for females. The total length–total weight relationship for the entire population is described by the parameters a = 0.0068, and b = 3.2401. Otolith age readings showed that the population exploited consisted of 10 age groups (1–10 years), including a very high proportion of individuals between 1 and 4 years old. The von Bertalanffy growth parameters for all individuals were L_∞ = 32.98 cm, k = 0.22 years⁻¹, and t₀ = −0.87 years. Males grew comparatively slower than females. The instantaneous rates of mortality for all fish were Z = 0.96 years⁻¹, M = 0.30 years⁻¹, and F = 0.66 years⁻¹. The exploitation ratio and the length at first capture were, respectively, E = 0.69 and LC₅₀ = 16.1 cm. The stock is overexploited, therefore measures such as closed seasons or changes in fishing patterns would be desirable to safeguard the spawning stock and recruits.     

Evaluation of the effect of some biocides against organisms isolated from historic monuments

On the surfaces of monuments and buildings, organic and inorganic pollutants accumulate, as well as various microbial communities which contribute to stone decay. In order to control these organisms, we have tested some chemical products with biocide and water-repellent properties. Some of these products were tested in an agar diffusion test and on limestone slabs. Efficacy of the products and the microbial inhibition were studied with scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM) techniques. This revised version was published online in June 2006 with corrections to the Cover Date.