Short allele of serotonin transporter gene promoter is a risk factor for obesity in adolescents

Obesity and hypertension are increasing medical problems in adolescents. Serotonin transporter (5-HTT) is involved in mood and eating disturbances. Encoded by the gene SLC6A4, the promoter shows functional insertion/deletion alleles: long (L) and short (S). Because individuals who are carriers for the short version are known to be at risk for higher levels of anxiety, we hypothesized that this variant may be associated with overweight. Data and blood samples were collected from 172 adolescents out of a cross-sectional, population-based study of 934 high school students. To replicate the findings, we also included 119 outpatients from the Nutrition and Diabetes Section of the Children's County Hospital. We found that the S allele was associated with overweight (BMI > 85th percentile), being a risk factor for overweight independently of sex, age, and hypertension [odds ratio (OR): 1.85; 95% confidence interval (CI): 1.13, 3.05; p < 0.02]. Additionally, in the outpatient study, compared with the homozygous LL subjects, S allele carriers showed a higher BMI z-score (1.47 +/- 1.09 vs. 0.51 +/- 1.4; p < 0.002) and were more frequent in overweight children. In conclusion, the S allele of the SLC6A4 promoter variant is associated with overweight being an independent genetic risk factor for obesity.     

Invasive and adherent bacterial pathogens co-Opt host clathrin for infection

Infection by the bacterium Listeria monocytogenes depends on host cell clathrin. To determine whether this requirement is widespread, we analyzed infection models using diverse bacteria. We demonstrated that bacteria that enter cells following binding to cellular receptors (termed "zippering" bacteria) invade in a clathrin-dependent manner. In contrast, bacteria that inject effector proteins into host cells in order to gain entry (termed "triggering" bacteria) invade in a clathrin-independent manner. Strikingly, enteropathogenic Escherichia coli (EPEC) required clathrin to form actin-rich pedestals in host cells beneath adhering bacteria, even though this pathogen remains extracellular. Furthermore, clathrin accumulation preceded the actin rearrangements necessary for Listeria entry. These data provide evidence for a clathrin-based entry pathway allowing internalization of large objects (bacteria and ligand-coated beads) and used by "zippering" bacteria as part of a general mechanism to invade host mammalian cells. We also revealed a nonendocytic role for clathrin required for extracellular EPEC infections.     

N-Glycan structure annotation of glycopeptides using a linearized glycan structure database (GlyDB)

While glycoproteins are abundant in nature, and changes in glycosylation occur in cancer and other diseases, glycoprotein characterization remains a challenge due to the structural complexity of the biopolymers. This paper presents a general strategy, termed GlyDB, for glycan structure annotation of N-linked glycopeptides from tandem mass spectra in the LC-MS analysis of proteolytic digests of glycoproteins. The GlyDB approach takes advantage of low-energy collision-induced dissociation of N-linked glycopeptides that preferentially cleaves the glycosidic bonds while the peptide backbone remains intact. A theoretical glycan structure database derived from biosynthetic rules for N-linked glycans was constructed employing a novel representation of branched glycan structures consisting of multiple linear sequences. The commonly used peptide identification program, Sequest, could then be utilized to assign experimental tandem mass spectra to individual glycoforms. Analysis of synthetic glycopeptides and well-characterized glycoproteins demonstrate that the GlyDB approach can be a useful tool for annotation of glycan structures and for selection of a limited number of potential glycan structure candidates for targeted validation.     

Tomographic molecular imaging and 3D quantification within adult mouse organs

A convenient technology to quantify three-dimensional (3D) morphological features would have widespread applications in biomedical research. Based on combined improvements in sample preparation, tomographic imaging and computational processing, we present a procedure for high-resolution 3D quantification of structures within intact adult mouse organs. Using the nonobese diabetic (NOD) mouse model, we demonstrate a correlation between total islet beta-cell volume and the onset of type-1 diabetes.     

Effects of temperature on sperm motility of burbot Lota lota: spontaneous activation and calcium dependency

Several factors regulating activation of spermatozoon motility in Eurasian burbot, Lota lota, including osmolality, calcium (Ca²⁺) ions, and temperature were investigated. Spermatozoon motility in Eurasian burbot, Lota lota was assessed at 4 and 30°C in seminal fluid, isotonic media (with and without Ca²⁺) and hypotonic media (with and without Ca²⁺). Spermatozoa were spontaneously activated in seminal fluid at 20°C and the maximum motility was recorded at 30°C, which is out of the spawning temperature range, indicating that no risk of activation occurs during routine semen handling in artificial insemination. Initiation of spermatozoon motility in L. lota is mediated by Ca²⁺ and sensitivity to Ca²⁺ is dependent on temperature.     

The potential of quantitative models to improve microalgae photosynthetic efficiency

The massive increase in carbon dioxide concentration in the atmosphere driven by human activities is causing huge negative consequences and new sustainable sources of energy, food and materials are highly needed. Algae are unicellular photosynthetic microorganisms that can provide a highly strategic contribution to this challenge as alternative source of biomass to complement crops cultivation. Algae industrial cultures are commonly limited by light availability, and biomass accumulation is strongly dependent on their photon‐to‐biomass conversion efficiency. Investigation of algae photosynthetic metabolism is thus strategic for the generation of more efficient strains with higher productivity. Algae are cultivated at industrial scale in conditions highly different from the natural niches they adapted to and strains development efforts must fully consider the seminal influence on productivity of regulatory mechanism of photosynthesis as well as of cultivation parameters like cells concentration, light distribution in the culture, mixing, nutrients and carbon dioxide availability. In this review we will focus in particular on how mathematical models can account for the complex influence of all environmental parameters and can be exploited for development of improved algae strains.     

A study of autologous anti-idiotypic antibody-forming cells in mice of different ages and genetic backgrounds.

Antibody response to phosphorylcholine, an immunodominant epitope of Streptococcus pneumoniae R36a (Pn), is characterized by a public idiotype, T15, that is expressed on a large proportion of antibody molecules produced by all mouse inbred strains. The ability of the immune system to produce an autologous antibody to T15 upon immunization with Pn vaccine was investigated using a modified ELISA plaque assay for detection of single antibody-forming cells (AFC). The limit of ELISA assay for detection of specific anti-T15 AFC is approximately 300 cells/spleen. However, our studies failed to detect any autologous anti-T15 AFC in the course of the primary antibody response to Pn vaccine in young/adult (2-4 months) BALB/c and C57BL/6 mice. Aged mice (20-22 months) also failed to develop any specific auto-anti-T15 AFC upon the primary Pn immunization, despite the fact that the anti-Pn response in these animals changes both quantitatively and qualitatively. In order to generate specific anti-T15 AFC, BALB/c mice had to be immunized repeatedly with Pn vaccine (four weekly injections) or immunized directly with T15 protein in CFA. Different results were obtained with D1.LP mice that are low responders to Pn and express lower levels of T15 Id as compared to BALB/c. Young D1.LP mice produced high numbers of auto-anti-T15 AFC of both IgM and IgG isotypes following a single immunization with Pn vaccine. The kinetics of auto-anti-T15 response in D1.LP mice was similar to that of the antigen-specific response. These results demonstrate that the ability of the immune network to produce autologous antibody to a shared Id depends on the genetic makeup of the host, and that this response may be regulated by the level of Id expression.     

Gene-targeted mice lacking the Trex1 (DNase III) 3'-->5' DNA exonuclease develop inflammatory myocarditis

TREX1, originally designated DNase III, was isolated as a major nuclear DNA-specific 3'-->5' exonuclease that is widely distributed in both proliferating and nonproliferating mammalian tissues. The cognate cDNA shows homology to the editing subunit of the Escherichia coli replicative DNA polymerase III holoenzyme and encodes an exonuclease which was able to serve a DNA-editing function in vitro, promoting rejoining of a 3' mismatched residue in a reconstituted DNA base excision repair system. Here we report the generation of gene-targeted Trex1(-/-) mice. The null mice are viable and do not show the increase in spontaneous mutation frequency or cancer incidence that would be predicted if Trex1 served an obligatory role of editing mismatched 3' termini generated during DNA repair or DNA replication in vivo. Unexpectedly, Trex1(-/-) mice exhibit a dramatically reduced survival and develop inflammatory myocarditis leading to progressive, often dilated, cardiomyopathy and circulatory failure.