The GABAa receptor complex in the developing chick optic tectum: Ontogeny of [H]muscimol, [H]flunitrazepam and [S]TBPS binding sites

The developmental profiles of the neurotransmitter recognition site, labeled by [³H]muscimol, and of the two main modulatory sites, labeled by [³H]flunitrazepam and [³⁵S]t-butylbicyclophosphorothionate, respectively, within the GABA_A receptor complex, have been determined in chick tectal lobes between embryonic day 8 and postnatal day 20. The consonance among the rates of appearance and accumulation of the three receptor sites in tectal membranes suggests a coordinated expression and assembly of the protein subunits involved in the spatial configuration of the complex and its three binding sites, although the existence of isolated muscimol binding subunits during early embryogenesis cannot be excluded at the present time. Furthermore, the total number of binding sites of each kind, per pair of lobes, is compatible with a 1/1/I stoichiometry. The GABA_A receptor complex reaches a maximum of expression, relative to total membrane protein, immediately after hatching, suggesting that the tectal GABAergic system may be instrumental in damping the effects of sudden exposure to light of the chick visual system upon eye opening.     

A case of trisomy 12 mosaicism with pituitary malformation and polycystic ovary syndrome

We report the case of a patient (followed from birth to 15 years) presenting with trisomy 12 mosaicism, and focus on the endocrine phenotype associating a pituitary malformation and ovarian abnormalities. We describe the dysmorphic features and their evolution, the growth retardation and ovarian symptoms. Complete growth hormone deficiency was confirmed on auxological data, stimulation test and was related to pituitary stalk interruption, diagnosed by magnetic resonance imaging. Effect of growth hormone treatment was satisfactory resulting in a normal adult height. She also presented premature thelarche associated with right ovarian hypertrophy (4 to 5 fold the volume of the left ovary) which remained constant until 15 years of age. Diagnosis of trisomy 12 mosaicism was made on skin and ovarian karyotypes. The possible relation between these endocine findings and some genes located on chromosome 12 involved in pituitary and ovarian development is discussed.     

Immunity to Intracellular Salmonella Depends on Surface-associated Antigens

Invasive Salmonella infection is an important health problem that is worsening because of rising antimicrobial resistance and changing Salmonella serovar spectrum. Novel vaccines with broad serovar coverage are needed, but suitable protective antigens remain largely unknown. Here, we tested 37 broadly conserved Salmonella antigens in a mouse typhoid fever model, and identified antigen candidates that conferred partial protection against lethal disease. Antigen properties such as high in vivo abundance or immunodominance in convalescent individuals were not required for protectivity, but all promising antigen candidates were associated with the Salmonella surface. Surprisingly, this was not due to superior immunogenicity of surface antigens compared to internal antigens as had been suggested by previous studies and novel findings for CD4 T cell responses to model antigens. Confocal microscopy of infected tissues revealed that many live Salmonella resided alone in infected host macrophages with no damaged Salmonella releasing internal antigens in their vicinity. In the absence of accessible internal antigens, detection of these infected cells might require CD4 T cell recognition of Salmonella surface-associated antigens that could be processed and presented even from intact Salmonella. In conclusion, our findings might pave the way for development of an efficacious Salmonella vaccine with broad serovar coverage, and suggest a similar crucial role of surface antigens for immunity to both extracellular and intracellular pathogens.     

Distinct Distribution of Ectopically Expressed Histone Variants H2A.Bbd and MacroH2A in Open and Closed Chromatin Domains

Background

It becomes increasingly evident that nuclesomes are far from being identical to each other. This nucleosome diversity is due partially to the existence of histone variants encoded by separate genes. Among the known histone variants the less characterized are H2A.Bbd and different forms of macroH2A. This is especially true in the case of H2A.Bbd as there are still no commercially available antibodies specific to H2A.Bbd that can be used for chromatin immunoprecipitation (ChIP).

Methods

We have generated HeLa S3 cell lines stably expressing epitope-tagged versions of macroH2A1.1, H2A.Bbd or canonical H2A and analyzed genomic distribution of the tagged histones using ChIP-on-chip technique.

Results

The presence of histone H2A variants macroH2A1.1 and H2A.Bbd has been analyzed in the chromatin of several segments of human chromosomes 11, 16 and X that have been chosen for their different gene densities and chromatin status. Chromatin immunoprecipitation (ChIP) followed by hybridization with custom NimbleGene genomic microarrays demonstrated that in open chromatin domains containing tissue-specific along with housekeeping genes, the H2A.Bbd variant was preferentially associated with the body of a subset of transcribed genes. The macroH2A1.1 variant was virtually absent from some genes and underrepresented in others. In contrast, in closed chromatin domains which contain only tissue-specific genes inactive in HeLa S3 cells, both macroH2A1.1 and H2A.Bbd histone variants were present and often colocalized.

Conclusions

Genomic distribution of macro H2A and H2A.Bbd does not follow any simple rule and is drastically different in open and closed genomic domains.     

Partial replacement of sodium in meat and fish products by using magnesium salts. A review

Sodium intake exceeds the nutritional recommendations in most industrialized countries becoming one concern for public health. This elimination or reduction is not simple due to its role in final food sensory, quality and safety. The aim of this work is to review the possibilities of magnesium ion, due to its healthy properties, to become a partial substitute of sodium in the production of fish and meat products, and a particular case for Spanish dry-cured ham and loin. Magnesium diffusion into different muscle based foods such as ham or loin, and its effect in the most important characteristics of the final product (microbiology, physico-chemical and sensory properties) has been analyzed. Results show that magnesium has more difficulty to penetrate inside the muscle and slightly modifies the water-holding capacity of proteins, their solubility and the enzymatic activity. Salty taste, bitterness and off-flavor are the most affected characteristics. However, these effects could be compensated by using longer post-salting periods and by employing masking agents. It is possible to reduce the sodium content in fish and meat products using magnesium as one of the ingredients, allowing to obtain new products with similar physicochemical characteristics and safety conditions.     

Novel insights into the pathogenesis of the Graffi murine leukemia retrovirus

The Graffi murine leukemia virus (MuLV) was isolated in 1954 by Arnold Graffi, who characterized it as a myeloid leukemia-inducing retrovirus. He and his team, however, soon observed the intriguing phenomenon of hematological diversification, which corresponded to a decrease of myeloid leukemias and an increase of other types of leukemias. Recently, we derived two different molecular clones corresponding to ecotropic nondefective genomes that were named GV-1.2 and GV-1.4. The induced leukemias were classified as myeloid based on morphological analysis of blood smears. In this study, we further characterized the two variants of the Graffi murine retrovirus, GV-1.2 and GV-1.4, in three different strains of mice. We show that the Graffi MuLV is a multipotent retrovirus capable of inducing both lymphoid (T- and B-cell) and nonlymphoid (myeloid, erythroid, megakaryocytic) leukemia. Many of these are very complex with concomitant expression of different hematopoietic lineages. Interestingly, a high percentage of megakaryocytic leukemias, a type of leukemia rarely observed with MuLVs, arise in the FVB/n strain of mice. The genetic backgrounds of the different strains of mice influence greatly the results. Furthermore, the enhancer region, different for GV-1.2 and GV-1.4, plays a pivotal role in the disease specificity: GV-1.2 induces more lymphoid leukemias, and GV-1.4 induces more nonlymphoid ones.     

Targeting internal ribosome entry site (IRES)-mediated translation to block hepatitis C and other RNA viruses

A number of RNA-containing viruses such as hepatitis C (HCV) and poliovirus (PV) that infect human beings and cause serious diseases use a common mechanism for synthesis of viral proteins, termed internal ribosome entry site (IRES)-mediated translation. This mode of translation initiation involves entry of 40S ribosome internally to the 5' untranslated region (UTR) of viral RNA. Cap-dependent translation of cellular mRNAs, on the other hand, requires recognition of mRNA 5' cap by the translation machinery. In this review, we discuss two inhibitors that specifically inhibit viral IRES-mediated translation without interfering with cellular cap-dependent translation. We present evidence, which suggest that one of these inhibitors, a small RNA (called IRNA) originally isolated from the yeast Saccharomyces cerevisiae, inhibits viral IRES-mediated translation by sequestering both noncanonical transacting factors and canonical initiation factors required for IRES-mediated translation. The other inhibitor, a small peptide from the lupus autoantigen La (called LAP), appears to block binding of cellular transacting factors to viral IRES elements. These results suggest that it might be possible to target viral IRES-mediated translation for future development of therapeutic agents effective against a number of RNA viruses including HCV that exclusively use cap-independent translation for synthesis of viral proteins.     

Range,population structure and morphological characterization of the small range endemic bush-cricket <Emphasis Type="Italic">Lluciapomaresius panteli</Emphasis> (Orthoptera: Tettigoniidae: Bradyporinae)

The bush-cricket genus Lluciapomaresius Barat, 2012 is endemic to the Iberian Peninsula. It includes at least seven species, most of which are narrow endemics restricted to single or few mountain ranges across the Peninsula. All of them are currently included under different categories in the IUCN red list. One of the species listed as data deficient is Pantel’s Saddle Bush-cricket L. panteli (Navàs 1899), an iconic species of the Montsant Natural Park. Up to now, it was thought to be restricted to few square kilometres in the Montsant range, in southern Catalonia (north-east Iberian Peninsula). The species was at some point suspected extinct, but it was rediscovered in 2000. More recently, a new species, L. nisae Olmo-Vidal 2017, was described based on specimens found in neighbouring Llaberia range, about 20 km south from Montsant. In this study, we present new data based on a systematic sampling of Lluciapomaresius across known and nearby locations in Montsant, Llaberia and surrounding ranges. The records and collected specimens allow us to provide a better delimitation of the actual distribution range and to conduct a detailed morphological study to shed light on the degree of differentiation of populations in different parts of the range, further supported by DNA sequence data of mitochondrial and nuclear genes. Our results show that L. nisae is a synonym of L. panteli as judged by the small genetic and morphological variability, better interpreted as the result of local differentiation of populations following post-glacial isolation. We further confirm the extremely small ranges and isolation of the Lluciapomaresius populations and propose to move the species towards the EN (endangered) category in the IUCN Red List. Additional research on the still unknown aspects of its biology and ecology is needed to implement reasoned and effective conservation measures that ensure its survival.