General trend of lipase to self-assemble giving bimolecular aggregates greatly modifies the enzyme functionality

Three microbial lipases (those from Candida rugosa, Humicola lanuginosa, and Mucor miehei) have been found to exhibit a tendency to form bimolecular aggregates in solution even at very low enzyme concentrations (44 microg/mL) in the absence of a detergent, as detected by gel filtration. The monomolecular form of the enzymes was found as unique only at low enzyme concentration and in the presence of detergents. However, in the case of the lipase B from Candida antarctica, no bimolecular form could be identified even at enzyme concentrations as high as 1.2 mg/mL in the absence of detergent. It has been stated that bimolecular and monomolecular structures display very different functional properties: (i) the enzyme specific activity decreased when the lipase concentration increased; (ii) the bimolecular form was much more stable than the monomeric one yielding a higher optimal T (increasing between 5 and 10 degrees C) and higher stability in inactivation experiments (the dimer half-life became several orders of magnitude higher than that of the monomer); (iii) the enantioselectivity depended on the enzyme concentration even after immobilization. For example, with use of the lipase from H. lanuginosa, the enantiomeric excess of the remaining ester in the hydrolysis of fully soluble ethyl ester of (R,S)-2-hydroxy-4-phenylbutanoic acid varied from 4 to 57 when the concentrated or diluted enzyme immobilized on PEI support, respectively, was used. It seems that the bimolecular structure of lipases might be formed by two open lipase molecules (interfacially activating each other) in very close contact and hence with a very altered active center.     

Distribution and feeding habitat characterization of whale sharks Rhincodon typus in a protected area in the north Caribbean Sea

The relationship between the distribution of the whale shark Rhincodon typus and hydrobiological variables in the Caribbean Sea during 2005–2009 was analysed. Monthly trips were made to the R. typus aggregation area during the months when this species is present in the region (May to September) to record sightings and hydrological data and to collect samples to determine nutrients, chlorophyll a (Chl a) and zooplankton biomass. A total of 2104 R. typus were counted and three zones of high abundance were identified: Cabo‐Catoche, Contoy (both within the Whale Shark Biosphere Reserve, WSBR) and the zone knows as Afuera. The zones of greatest R. typus density within the WSBR were characterized by high Chl a concentrations (median: 1·1 mg m^?3, interpercentile range: 0·5–1·8 mg m^?3) and high nutrient concentrations, such as ammonium (median: 2·5 µmol l^?1, interpercentile range: 0·5–6·4 µmol l^?1), due to the influence of local upwelling. A generalized additive model (GAM) was used to explore the relationship between R. typus distribution and the environmental variables inside WSBR. Zooplankton biomass was the most influential environmental variable, supporting the close relationship between R. typus distribution and biological productivity. Copepods were the dominant zooplankton group within the WSBR. In the Afuera zone, there were large R. typus aggregations (>80 individuals) associated with zooplankton dominated by fish eggs and significantly higher mean ± s.d. biomass (3356·1 ± 1960·8 mg m^?3) compared with that recorded inside the WSBR (103·5 ± 57·2 mg m^?3). The differences among zones generated changes in R. typus distribution patterns and provided opportunities to develop local management strategies for this species.     

Characterization of a Prefusion-Specific Antibody That Recognizes a Quaternary,Cleavage-Dependent Epitope on the RSV Fusion Glycoprotein

Prevention efforts for respiratory syncytial virus (RSV) have been advanced due to the recent isolation and characterization of antibodies that specifically recognize the prefusion conformation of the RSV fusion (F) glycoprotein. These potently neutralizing antibodies are in clinical development for passive prophylaxis and have also aided the design of vaccine antigens that display prefusion-specific epitopes. To date, prefusion-specific antibodies have been shown to target two antigenic sites on RSV F, but both of these sites are also present on monomeric forms of F. Here we present a structural and functional characterization of human antibody AM14, which potently neutralized laboratory strains and clinical isolates of RSV from both A and B subtypes. The crystal structure and location of escape mutations revealed that AM14 recognizes a quaternary epitope that spans two protomers and includes a region that undergoes extensive conformational changes in the pre- to postfusion F transition. Binding assays demonstrated that AM14 is unique in its specific recognition of trimeric furin-cleaved prefusion F, which is the mature form of F on infectious virions. These results demonstrate that the prefusion F trimer contains potent neutralizing epitopes not present on monomers and that AM14 should be particularly useful for characterizing the conformational state of RSV F-based vaccine antigens.     

Does rock type account for variation in mussel attachment strength? A test with <Emphasis Type="Italic">Brachidontes rodriguezii</Emphasis> in the southwestern Atlantic

Mussel attachment strength varies in space and time, frequently in association with variations in wave exposure. Yet, it remains uninvestigated whether different rock types can contribute to variation in mussel attachment. Here we compared the attachment strength of the mussel Brachidontes rodriguezii between soft and hard intertidal rock substrates that are typical of coastal Buenos Aires Province, Argentina: Pampean loess cemented by calcium carbonate and orthoquartzite, respectively. Overall comparisons of mussel attachment across natural platforms of either rock type (10 loess sites and 4 orthoquartzite sites) indicated stronger mussel attachment to orthoquartzite. However, mussel attachment strength did not differ when compared across natural loess platforms and introduced orthoquartzite blocks (i.e., groins and revetments) occurring within the same site. Mussels attaching to loess showed more byssal threads than those attaching to orthoquartzite at the same site. These findings suggest, first, that rock type does not influence mussel attachment strength in our study system, secondly, that overall differences in mussel attachment strength with rock type across natural platforms in our study range are due to confounding influences of co-varying factors (e.g., wave exposure) and, finally, that mussels can increase byssus production to counteract potential substrate failure when attaching to soft, friable rock. The latter likely explains the ability of mussels to maintain relatively stable cover across rocks of contrasting hardness.     

Morphological events during in vitro fertilization of prepubertal goat oocytes matured in vitro

Experiments were carried out to study morphological changes temporally associated with in vitro fertilization (IVF) of prepubertal goat oocytes and to elucidate some of the abnormalities occurring during this process. The effects of different intervals of insemination on subsequent embryonic development were also studied. Prepubertal goat oocytes collected at slaughter were matured in TCM199 supplemented with estrous goat serum (20%), FSH (10 microg/ml), LH (10 microg/ml) and estradiol-17 beta (1 microg/ml) for 27 h at 38.5 degrees C. Matured oocytes were inseminated with freshly ejaculated spermatozoa following capacitation as described by Younis et al. (37) but with 100 microg/ml heparin. Representative oocytes were fixed every 2 to 4 h from 2 to 28 h after insemination for a study of sperm penetration, sperm head decondensation, meiotic activation, female chromosome decondensation, and male and female pronuclear formation. At the same intervals after insemination, some of the ova were co-cultured on granulosa cell monolayers for up to 9 d. Sperm penetration into the ooplasm was first observed at 4 h post insemination; decondensation of male and female chromatin and formation of male and female pronuclei occurred at 6 to 8 and 10 to 16 h after insemination, respectively. Highest proportions of oocytes were penetrated after exposure to spermatozoa for 8 h. There were no significant differences in ovum penetration after longer insemination intervals. Cleavage was first observed 24 h after insemination. Three types of abnormalities were observed. These were polyspermy, polygyny and asynchrony in the development of the female and male pronuclei, apparently due to a delay in the decondensation of the male pronucleus. Significantly higher proportions of oocytes cleaved (31.2 to 45.5%) after 20, 24 or 28 h insemination intervals than following shorter intervals of exposure to spermatozoa. However, the sperm exposure interval did not significantly affect subsequent embryonic development to the blastocyst stage. Embryos resulting from oocytes exposed to sperm cells for at least 12 h developed further than the 8-cell stage.     

Effect of sperm capacitation and fertilization media on IVF and early embryo development of prepubertal goat oocytes

Experiments were carried out to develop an improved IVF system for prepubertal goat oocytes matured in vitro. Cumulus oocyte complexes (COC) were obtained by slicing ovaries from slaughtered prepubertal goats. Oocytes were matured in TCM199 supplemented with 20% estrous goat serum (EGS) + 10 micrograms/mL FSH + 10 micrograms/mL LH + 1 microgram/mL estradiol 17 beta for 27 h at 38.5 degrees C in 5% CO2 in air. In Experiments 1 and 2, freshly ejaculated spermatozoa were capacitated in 1 of 3 media: TALP/H, modified Defined Medium (mDM) and mH-M199 with 50 micrograms/mL heparin for 45 min. Matured oocytes were fertilized in TALP, mDM or mH-M199 in Experiment 1 and in TALP in Experiment 2. In Experiment 3, three media were used for sperm capacitation and fertilization: Treatment A (control group): spermatozoa were capacitated in mDM with 50 micrograms/mL heparin for 45 min and fertilized in TALP medium with 1 microgram/mL hypotaurine; Treatment B: spermatozoa were capacitated in mDM with 50 micrograms/mL heparin + 388 micrograms/mL caffeine for 30 min and fertilized in TALP medium without hypotaurine; Treatment C: spermatozoa were capacitated in mDM with 50 micrograms/mL heparin for 45 min and fertilized in TALP medium with PHE (20 microM penicillamine, 10 microM hypotaurine and 2 microM epinephrine). At 24 h post insemination, the ova were transferred to a granulosa cell monolayer, and early embryo development was evaluated until Day 8. In experiment 2, the results show, that mDM plus heparin for sperm capacitation and TALP medium with hypotaurine for oocyte fertilization provided the highest proportion of penetrated oocytes, both total number (79.6%) and normal fertilization (55.1%), whereas the use of caffeine (44.6 and 31.2%, total and normal fertilization rate, respectively) and PHE (31.8 and 20.6%, total and normal fertilization rate, respectively) as motility enhancers did not improve the results obtained in the control group (48.7% and 37.2%, total and normal fertilization rate, respectively). These were no differences for the results of morulae and blastocysts.     

Induction of a neutralizing immune response to human respiratory syncytial virus with anti-idiotypic antibodies.

Anti-idiotypic (anti-Id) antibodies were raised in rabbits against monoclonal antibodies that recognized either F glycoprotein 47F or G glycoprotein 63G, 62G, or 74G of the human respiratory syncytial virus Long strain. Anti-Id sera inhibited the virus binding of the immunizing monoclonal antibodies and in some cases the binding of other antibodies reacting with overlapping epitopes. The anti-Id sera also inhibited virus neutralization mediated by the original monoclonal antibodies. Affinity purified anti-Id antibodies were subsequently used to raise a homologous anti-anti-Id response in rabbits. One of the rabbits, inoculated with anti-Id 63G, generated antibodies that reacted with the G protein of respiratory syncytial virus and neutralized the virus to high titers. The antiviral antibodies induced by anti-Id 63G were broadly cross-reactive with strains of the A and B subtypes. However, the specificities of monoclonal antibody 63G and anti-anti-Id 63G were not exactly the same, as indicated by their reaction with escape mutants to antibody 63G. These results demonstrate for the first time the induction of an anti-respiratory syncytial virus response by anti-Id antibodies.     

Involving Families with Osteogenesis Imperfecta in Health Service Research: Joint Development of the OI/ECE Questionnaire

Background

Despite the growing interest in understanding the psycho-social impact of rare genetic diseases, few studies examine this concept and even fewer seek to obtain feedback from families who have lived the experience. The aim of this project was to involve families of children living with osteogenesis imperfecta (OI) in the development of a tool to assess the impact of OI on the lives of patients and their families.

Methods

This project used an integrated knowledge translation approach in which knowledge users (clinicians and people living with OI and their families) were consulted throughout the four steps of development, that is: content mapping, item generation, tool appraisal and pre-testing of the questionnaires. The International Classification of Functioning and Health was used as a framework for content mapping. Based on a scoping review we selected two validated tools to use as a basis for developing the questionnaire. The final parent self-report version measured six domains: experience of diagnosis; use of health services; use of social and psychological support services; expectations about tertiary specialized centers; and socio-demographic information.

Results

A total of 27 out of 40 families receiving care at the Shriners Hospital for Children-Canada and invited to participate in the pre-test returned the completed questionnaires. In more than two-thirds of families (69%; n = 18) OI was suspected either at or within the first 3 months after birth. Up to 46% of families consulted between 3 and 5 doctors (46%; n = 12) prior to final diagnosis. The use of services by families varied from 0 to 16 consultations, 0 to 9 exploratory examinations and 1 to 10 types of allied health services. In the 12 months prior to the study, fewer than a quarter of children had been admitted, for treatment, for hospital stays of longer than 8 hours or to an emergency department (24% and 9% respectively). Only 29% of parents received psychological support.

Conclusion

This joint development process generated a tool, with good psychometric properties, that provides unique insight into the experiences of patients and families with OI, the psycho-social impact of the illness, and their service needs and expectations.     

The D2 dopamine receptor gene variant C957T affects human fear conditioning and aversive priming

Polymorphisms of DRD2 and A NKK1 have been associated with psychiatric syndromes where there is believed to be an underlying learning process deficit such as addiction, post-traumatic stress disorder and psychopathy. We investigated the effects of the DRD2 C957T and ANKK1 Taq IA single nucleotide polymorphism (SNP), which have been associated with psychopathic traits in alcoholic patients, on fear conditioning and aversive priming in healthy volunteers. We found that the DRD2 C957T SNP, but not the ANKK1 Taq IA SNP, was associated with both differential conditioning of the skin conductance response and the aversive priming effect. There were no differences between the genotype groups with respect to the extinction of the skin-conductance conditioned response. These results suggest that the C957T SNP could be related to learning differences associated with the risk of developing psychiatric disorders in individuals that are carriers of the C homozygous genotype. Our genetic data raise the possibility that the dopaminergic system functional variations determined by this SNP could affect fear learning.     

Transcriptome of Extracellular Vesicles Released by Hepatocytes

The discovery that the cells communicate through emission of vesicles has opened new opportunities for better understanding of physiological and pathological mechanisms. This discovery also provides a novel source for non-invasive disease biomarker research. Our group has previously reported that hepatocytes release extracellular vesicles with protein content reflecting the cell-type of origin. Here, we show that the extracellular vesicles released by hepatocytes also carry RNA. We report the messenger RNA composition of extracellular vesicles released in two non-tumoral hepatic models: primary culture of rat hepatocytes and a progenitor cell line obtained from a mouse foetal liver. We describe different subpopulations of extracellular vesicles with different densities and protein and RNA content. We also show that the RNA cargo of extracellular vesicles released by primary hepatocytes can be transferred to rat liver stellate-like cells and promote their activation. Finally, we provide in vitro and in vivo evidence that liver-damaging drugs galactosamine, acetaminophen, and diclofenac modify the RNA content of these vesicles. To summarize, we show that the extracellular vesicles secreted by hepatocytes contain various RNAs. These vesicles, likely to be involved in the activation of stellate cells, might become a new source for non-invasive identification of the liver toxicity markers.