New polymorphisms and markers in the HLA class I region: relevance to hereditary hemochromatosis (HFE)

Hereditary hemochromatosis (HFE) is an inherited disorder whose gene lies in the proximity of the histocompatability antigen (HLA) class I region, on 6p21.3. Despite efforts in refining the HFE region, a number of informative DNA markers, linked to the disease locus and amenable to use in an assay based on the polymerase chain reaction (PCR) is available. The gene content of this region is high, and the HFE gene has not so far been identified. We have used a strategy based on PCR protocols potentially able to detect both polymorphisms and expressed sequences. This approach has been applied to a 700-kb stretch (approximately) of DNA corresponding to the insert of a Centre d'Etude du Polymorphisme Humain yeast artificial chromosome (225 B1) of the possible candidate region. Five new polymorphisms have been detected among 20 specific fragments isolated. Four of them are tightly linked to the HFE locus. Because of the strong linkage disequilibrium with the disease demonstrated by these markers, they could represent starting points for the identification and characterization of the HFE gene. The remaining non-polymorphic fragments, being amplifiable and in most cases linked to NotI sites, may be useful starting points for the generation of a genomic contig of band 6p21.3 and for gene identification.     

Seahorses in focus: local ecological knowledge of seahorse-watching operators in a tropical estuary

Background

Seahorses are endangered teleost fishes under increasing human pressures worldwide. In Brazil, marine conservationists and policy-makers are thus often skeptical about the viability of sustainable human-seahorse interactions. This study focuses on local ecological knowledge on seahorses and the implications of their non-lethal touristic use by a coastal community in northeastern Brazil. Community-based seahorse-watching activities have been carried out in Maracaípe village since 1999, but remained uninvestigated until the present study. Our goal is to provide ethnoecological understanding on this non-extractive use to support seahorse conservation and management.

Methods

We interviewed 32 informants through semi-structured questionnaires to assess their socioeconomic profile, their knowledge on seahorse natural history traits, human uses, threats and abundance trends.

Results

Seahorse-watching has high socioeconomic relevance, being the primary income source for all respondents. Interviewees elicited a body of knowledge on seahorse biology largely consistent with up-to-date research literature. Most informants (65.5 %) perceived no change in seahorse abundance. Their empirical knowledge often surpassed scientific reports, i.e. through remarks on trophic ecology; reproductive aspects, such as, behavior and breeding season; spatial and temporal distribution, suggesting seahorse migration related to environmental parameters.

Conclusions

Seahorse-watching operators were aware of seahorse biological and ecological aspects. Despite the gaps remaining on biological data about certain seahorse traits, the respondents provided reliable information on all questions, adding ethnoecological remarks not yet assessed by conventional scientific surveys. We provide novel ethnobiological insight on non-extractive modes of human-seahorse interaction, eliciting environmental policies to integrate seahorse conservation with local ecological knowledge and innovative ideas for seahorse sustainable use. Our study resonates with calls for more active engagement with communities and their local ecologies if marine conservation and development are to be reconciled.

     

Calcium efflux from sarcoplasmic reticulum vesicles

Ca²⁺ efflux was studied in sarcoplasmic reticulum vesicles isolated from rabbit skeletal muscle. In experimental conditions in which the Ca²⁺ pump is reversed, the rate of Ca^2? efflux varies with the ADP, orthophosphate and Mg²⁺ concentrations of the assay medium and is inhibited by Na⁺.     

Pathway for ATP synthesis by sarcoplasmic reticulum ATPase

Millisecond mixing and quenching experiments were performed in order to study the rate of phosphorylation by P_i of the Ca²⁺-dependent ATPase of sarcoplasmic reticulum vesicles. A rapid phosphoenzyme formation was observed when the vesicles were preincubated in the absence of Ca²⁺ prior to the addition of P_i and Mg²⁺ to the medium, the half-time being in the range of 6 to 10 ms. A lag phase and a 5- to 10-fold slower rate of phosphoenzyme formation were observed when the enzyme was preincubated with Ca²⁺ prior to the addition to the reaction mixture of P_i, Mg²⁺, and an excess of ethylene glycol bis(β-aminoethyl ether)N,N′-tetraacetic acid. The rate of phosphoenzyme hydrolysis was measured either by the addition of Ca²⁺ or, in the absence of Ca²⁺, by tracing the hydrolysis of radioactive phosphoenzyme upon the addition of nonradioactive P_i. In the presence of Ca²⁺, the rate of phosphoenzyme hydrolysis was found to be one order of magnitude slower than the rate of hydrolysis measured in the absence of Ca²⁺. Different rates of phosphoenzyme formation and cleavage were found depending on whether sarcoplasmic reticulum vesicles or purified Ca²⁺-dependent ATPase were used. A transient phosphorylation by P_i was observed when the enzyme was preincubated in the absence of Ca²⁺ and then added to a medium containing P_i, Mg²⁺, and excess of Ca²⁺. The enzyme was phosphorylated during the initial 100 ms, the phosphoenzyme formed being slowly hydrolyzed in the subsequent incubation intervals. In these conditions ATP synthesis was observed if ADP was added to the mixture 100 ms after starting the reaction. No transient phosphorylation by P_i was observed when the enzyme was preincubated with Ca²⁺. Synthesis of a small but significant amount of ATP was observed when the enzyme was preincubated in the absence of Ca²⁺ and then added to a medium containing P_i, ADP, Mg²⁺, and 20 mm CaCl₂. This was not observed when the enzyme was preincubated in the presence of Ca²⁺.     

Neonatal myosin heavy chains are not expressed in Ni-induced rat rhabdomyosarcoma

Myosin heavy chain (MHC) composition of chemically-induced rhabdomyosarcoma (RMS) was analyzed by gel electrophoresis and Western blotting using a panel of monoclonal antimyosin antibodies specific for embryonic-, neonatal-, slow- and adult fast-type MHC isoforms. Myosin extracted from tumours and electrophoresed on 6%-sodium dodecyl sulfate (SDS)glycerol gels was found to migrate as three distinct MHC components. These polypeptides were present in different relative amounts in the five RMS studied. Western blotting experiments revealed that variable proportions of embryonic-, slow- and adult fast-, but not neonatal-type, MHC isoforms are consistently expressed in RMS. Indirect and double immunofluorescence procedures applied to cryosections of tumoral tissue showed that: (a) RMS cells were unreactive with antineonatal-type-MHC antibody, (b) the majority of neoplastic, desmin-positive, cells contained embryonic- as well as adult fast-type MHCs and (c) a minority of cells were labelled by anti-slow MHC antibody. The results of this study indicate that there is no obligatory sequence of MHC isoform expression in the molecular transition (emb----neo----adult) which occurs during rat skeletal myogenesis.     

Water diffusion under osmotic gradients in frog gastric mucosa

The asymmetry of the osmotic response of the frog gastric mucosa has been further analyzed by studying the effect of external tonicity changes on the water diffusion fluxes. Hyperosmotic solution at the serosal surface does not affect the water diffusion fluxes. Hyperosmotic solution at the mucosal surface, with isosmotic solution at the serosal surface, significantly reduces (P<0.001) the serosal-to-mucosal and the mucosal-to-serosal water diffusion. An increment in the restriction offered by the mucosa to water diffusion by effect of hypertonicity at the mucosal surface is proposed.     

Correlation between Corpus Callosum Sub-Segmental Area and Cognitive Processes in School-Age Children

We assessed the relationship between structural characteristics (area) and microstructure (apparent diffusion coefficient; ADC) of the corpus callosum (CC) in 57 healthy children aged 7.0 to 9.1 years, with diverse cognitive and academic abilities as well as executive functions evaluated with a neuropsychological battery for children. The CC was manually delineated and sub-segmented into six regions, and their ADC and area were measured. There were no significant differences between genders in the callosal region area or in ADC. The CC area and ADC, mainly of anterior regions, correlated with different cognitive abilities for each gender. Our results suggest that the relationship between cognitive abilities and CC characteristics is different between girls and boys and between the anterior and posterior regions of the CC. Furthermore, these findings strenghten the idea that regardless of the different interhemispheric connectivity schemes per gender, the results of cognitive tasks are very similar for girls and boys throughout childhood.     

Non-electrolyte diffusion across the frog gastric mucosa under osmotic gradients

Serosal-to-mucosal and mucosal-to-serosal diffusion of ¹⁴C-labelled inulin, sucrose, erythritol and propionamide was compared with ³HHO diffusion in mucosae incubated with isosmotic solutions at both surfaces, as well as isosmotic solution at serosal surface and hyperosmotic solution at the mucosal surface. The use of a hyperosmotic solution at the mucosal surface significantly increases unidirectional diffusion fluxes of inulin and of sucrose. To a nonsignificant extent, it affects the fluxes of erythritol and propionamide and significantly reduces the ³HHO diffusion. A size increment of the diffusion path utilized by the larger molecules is proposed.