Histocompatibility Gene Organization and Mixed Lymphocyte Reaction

TRANSFORMATION of allogenic lymphocytes in mixed cultures depends chiefly on an incompatibility between the lymphocyte donors at the major histocompatibility locus in man (HL-A), mouse (H-2) and rat (H-l)¹. Although the mouse H-2 locus can be divided into several regions each of which controls one or more antigenic specificities² and two or more subloci control HL-A antigens in man³, it is not known whether all parts of the major histocompatibility locus are equally important in eliciting transformation in mixed lymphocyte cultures. We now show that capacity to elicit lymphocyte transformation is different for different parts of the mouse H-2 locus.     

A simplified high-throughput method for pyrethroid knock-down resistance (kdr) detection in Anopheles gambiae

Background

A single base pair mutation in the sodium channel confers knock-down resistance to pyrethroids in many insect species. Its occurrence in Anopheles mosquitoes may have important implications for malaria vector control especially considering the current trend for large scale pyrethroid-treated bednet programmes. Screening Anopheles gambiae populations for the kdr mutation has become one of the mainstays of programmes that monitor the development of insecticide resistance. The screening is commonly performed using a multiplex Polymerase Chain Reaction (PCR) which, since it is reliant on a single nucleotide polymorphism, can be unreliable. Here we present a reliable and potentially high throughput method for screening An. gambiae for the kdr mutation.

Methods

A Hot Ligation Oligonucleotide Assay (HOLA) was developed to detect both the East and West African kdr alleles in the homozygous and heterozygous states, and was optimized for use in low-tech developing world laboratories. Results from the HOLA were compared to results from the multiplex PCR for field and laboratory mosquito specimens to provide verification of the robustness and sensitivity of the technique.

Results and Discussion

The HOLA assay, developed for detection of the kdr mutation, gives a bright blue colouration for a positive result whilst negative reactions remain colourless. The results are apparent within a few minutes of adding the final substrate and can be scored by eye. Heterozygotes are scored when a sample gives a positive reaction to the susceptible probe and the kdr probe. The technique uses only basic laboratory equipment and skills and can be carried out by anyone familiar with the Enzyme-linked immunosorbent assay (ELISA) technique. A comparison to the multiplex PCR method showed that the HOLA assay was more reliable, and scoring of the plates was less ambiguous.

Conclusion

The method is capable of detecting both the East and West African kdr alleles in the homozygous and heterozygous states from fresh or dried material using several DNA extraction methods. It is more reliable than the traditional PCR method and may be more sensitive for the detection of heterozygotes. It is inexpensive, simple and relatively safe making it suitable for use in resource-poor countries.     

Life at the border: Adaptation of proteins to anisotropic membrane environment

This review discusses main features of transmembrane (TM) proteins which distinguish them from water‐soluble proteins and allow their adaptation to the anisotropic membrane environment. We overview the structural limitations on membrane protein architecture, spatial arrangement of proteins in membranes and their intrinsic hydrophobic thickness, co‐translational and post‐translational folding and insertion into lipid bilayers, topogenesis, high propensity to form oligomers, and large‐scale conformational transitions during membrane insertion and transport function. Special attention is paid to the polarity of TM protein surfaces described by profiles of dipolarity/polarizability and hydrogen‐bonding capacity parameters that match polarity of the lipid environment. Analysis of distributions of Trp resides on surfaces of TM proteins from different biological membranes indicates that interfacial membrane regions with preferential accumulation of Trp indole rings correspond to the outer part of the lipid acyl chain region—between double bonds and carbonyl groups of lipids. These “midpolar” regions are not always symmetric in proteins from natural membranes. We also examined the hydrophobic effect that drives insertion of proteins into lipid bilayer and different free energy contributions to TM protein stability, including attractive van der Waals forces and hydrogen bonds, side‐chain conformational entropy, the hydrophobic mismatch, membrane deformations, and specific protein–lipid binding.     

Sar1 GTPase Activity Is Regulated by Membrane Curvature

The majority of biosynthetic secretory proteins initiate their journey through the endomembrane system from specific subdomains of the endoplasmic reticulum. At these locations, coated transport carriers are generated, with the Sar1 GTPase playing a critical role in membrane bending, recruitment of coat components, and nascent vesicle formation. How these events are appropriately coordinated remains poorly understood. Here, we demonstrate that Sar1 acts as the curvature-sensing component of the COPII coat complex and highlight the ability of Sar1 to bind more avidly to membranes of high curvature. Additionally, using an atomic force microscopy-based approach, we further show that the intrinsic GTPase activity of Sar1 is necessary for remodeling lipid bilayers. Consistent with this idea, Sar1-mediated membrane remodeling is dramatically accelerated in the presence of its guanine nucleotide-activating protein (GAP), Sec23-Sec24, and blocked upon addition of guanosine-5′-[(β,γ)-imido]triphosphate, a poorly hydrolysable analog of GTP. Our results also indicate that Sar1 GTPase activity is stimulated by membranes that exhibit elevated curvature, potentially enabling Sar1 membrane scission activity to be spatially restricted to highly bent membranes that are characteristic of a bud neck. Taken together, our data support a stepwise model in which the amino-terminal amphipathic helix of GTP-bound Sar1 stably penetrates the endoplasmic reticulum membrane, promoting local membrane deformation. As membrane bending increases, Sar1 membrane binding is elevated, ultimately culminating in GTP hydrolysis, which may destabilize the bilayer sufficiently to facilitate membrane fission.     

Sauropod Trackway Reflecting an Unusual Walking Pattern from the Early Cretaceous of Shandong Province,China

The trackway of a quadrupedal dinosaur from the Early Cretaceous (Albian) Qingquan tracksite (Tancheng, Shandong Province) is redescribed, and the trackmaker is identified as a sauropod. The trackway makes a slight turn towards the northwest and is characterized by an extremely narrow gauge pattern and an unusual configuration, i.e., a conspicuous difference between the position of the left and right manus tracks with respect to the position of the preceding pes track. Left manus tracks are located on the inside of the trackway, very close (and sometimes even in connection) to the opposite right pes tracks. So far, the Qingquan trackway is possibly the only extremely narrow-gauge sauropod trackway known from China. However, it is not clear to what extent this extremely narrow gauge pattern is related to the turning or a special behavior, or even linked to an injury (“limping trackway”). We tentatively attribute the Qingquan trackway to cf. Parabrontopodus, even though it has a rather low heteropody that is significantly lower than in Parabrontopodus and not typical for narrow-gauge sauropod trackways, but occurs in the wide-gauge ichnotaxon Brontopodus. Because of this discrepancy, the Qingquan trackway cannot readily be attributed to a more basal sauropod, which is generally considered the producer of narrow-gauge trackways. Therefore, the identification of a distinct sauropod group is not possible presently. The only skeletal remains of sauropods from the Lower Cretaceous of Shandong Province belong to the large titanosauriform, Euhelopus zdanskyi.     

Thermal biology mediates responses of amphibians and reptiles to habitat modification

Human activities often replace native forests with warmer, modified habitats that represent novel thermal environments for biodiversity. Reducing biodiversity loss hinges upon identifying which species are most sensitive to the environmental conditions that result from habitat modification. Drawing on case studies and a meta‐analysis, we examined whether observed and modelled thermal traits, including heat tolerances, variation in body temperatures, and evaporative water loss, explained variation in sensitivity of ectotherms to habitat modification. Low heat tolerances of lizards and amphibians and high evaporative water loss of amphibians were associated with increased sensitivity to habitat modification, often explaining more variation than non‐thermal traits. Heat tolerances alone explained 24–66% (mean = 38%) of the variation in species responses, and these trends were largely consistent across geographic locations and spatial scales. As habitat modification alters local microclimates, the thermal biology of species will likely play a key role in the reassembly of terrestrial communities.     

PERCEPTION OF PORK PATTIES WITH SHIITAKE (LENTINUS EDODE P.) MUSHROOM POWDER AND SODIUM TRIPOLYPHOSPHATE AS MEASURED BY KOREAN AND UNITED STATES CONSUMERS

This study explored consumer liking and perception of pork patties with an added functional health ingredient: shiitake (Lentinus edodes P.) mushroom powder. In addition, patties with and without sodium tripolyphosphate were tested. Both native Korean and U.S. consumers evaluated the products. Pork patties made with both phosphate and mushroom powder were found to be acceptable by Korean consumers, but increases in mushroom powder in patties with phosphate decreased acceptability for U.S. consumers. However, addition of mushroom powder to patties without phosphate increased acceptability for U.S. consumers, perhaps because it tended to increase texture acceptance and juiciness. Thus, addition of mushroom powder as a functional ingredient in pork patties, while possible, would require different formula modifications to appeal to consumers of differing nationalities.     

The Long-Run Socio-Economic Consequences of a Large Disaster: The 1995 Earthquake in Kobe

We quantify the ‘permanent’ socio-economic impacts of the Great Hanshin-Awaji (Kobe) earthquake in 1995 by employing a large-scale panel dataset of 1,719 cities, towns, and wards from Japan over three decades. In order to estimate the counterfactual—i.e., the Kobe economy without the earthquake—we use the synthetic control method. Three important empirical patterns emerge: First, the population size and especially the average income level in Kobe have been lower than the counterfactual level without the earthquake for over fifteen years, indicating a permanent negative effect of the earthquake. Such a negative impact can be found especially in the central areas which are closer to the epicenter. Second, the surrounding areas experienced some positive permanent impacts in spite of short-run negative effects of the earthquake. Much of this is associated with movement of people to East Kobe, and consequent movement of jobs to the metropolitan center of Osaka, that is located immediately to the East of Kobe. Third, the furthest areas in the vicinity of Kobe seem to have been insulated from the large direct and indirect impacts of the earthquake.