Of volatiles and peptides: in search for MHC-dependent olfactory signals in social communication

Genes of the major histocompatibility complex (MHC), which play a critical role in immune recognition, are considered to influence social behaviors in mice, fish, humans, and other vertebrates via olfactory cues. As studied most extensively in mice, the polymorphism of MHC class I genes is considered to bring about a specific scent signature, which is decoded by the olfactory system resulting in an individual-specific reaction such as mating. On the assumption that this signature resides in volatiles, extensive attempts to identify these MHC-specific components in urine failed. Alternatively, it has been suggested that peptide ligands of MHC class I molecules are released into urine and can elicit an MHC-haplotype-specific behavioral response after uptake into the nose by sniffing. Analysis of the urinary peptide composition of mice shows that MHC-derived peptides are present, albeit in extremely low concentrations. In contrast, urine contains abundant peptides which differ between mouse strains due to genomic variations such as single-nucleotide variations or complex polymorphisms in multigene families as well as in their concentration. Thus, urinary peptides represent a real-time sampling of the expressed genome available for sensory evaluation. It is suggested that peptide variation caused by genomic differences contains sufficient information for individual recognition beyond or instead of an influence of the MHC in mice and other vertebrates.     

Of von Willebrand factor and platelets

Hemostasis and pathological thrombus formation are dynamic processes that require multiple adhesive receptor-ligand interactions, with blood platelets at the heart of such events. Many studies have contributed to shed light on the importance of von Willebrand factor (VWF) interaction with its platelet receptors, glycoprotein (GP) Ib-IX-V and αIIbβ3 integrin, in promoting primary platelet adhesion and aggregation following vessel injury. This review will recapitulate our current knowledge on the subject from the rheological aspect to the spatio-temporal development of thrombus formation. We will also discuss the signaling events generated by VWF/GPIb-IX-V interaction, leading to platelet activation. Additionally, we will review the growing body of evidence gathered from the recent development of pathological mouse models suggesting that VWF binding to GPIb-IX-V is a promising target in arterial and venous pathological thrombosis. Finally, the pathological aspects of VWF and its impact on platelets will be addressed.     

Rapid assessment of acid phosphatase activity in the mycorrhizosphere and in arbuscular mycorrhizal fungal hyphae

A pot experiment has been carried out under controlled conditions to study the possibility of applying the technique ofin vivo staining for acid phosphatase activity on the roots of mycorrhizal plants and arbuscular mycorrhizal hyphae. The pots had 5 compartments. The central root compartment was separated from the two adjacent hyphal compartments using nylon nets of 30 μm mesh, and the two hyphal compartments were separated from the two outermost compartments with 0.45 μm membranes. Red clover was grown in the root compartment and was either inoculated with the arbuscular mycorrhizal fungus (AMF)Glomus mosseae or unlnoculated. Sodium phytate was applied to all compartments. The results show that AMF can increase acid phosphatase activity of clover roots. The plant roots acquired deep red “mycorrhizal prints”. The external hyphae also had obvious “hyphal prints” on the test papers, indicating the ability of mycorrhizal hyphae to release acid phosphatase.     

Present effects of past wildfires on leaf litter breakdown in stream ecosystems

We investigated the present effects from a 10-year-old wildfire on leaf litter breakdown rates in 3 headwater streams in central Idaho. These systems experienced a massive debris flow one year after the fire. Based on soil instability and burn patterns, we identified 3 stream conditions: unburned, burned only, and burned/scoured. We placed leaf bags containing willow leaves ( Salix sp.) in each stream type and removed bags at various time intervals until all bags were collected 100 days after their introduction. Leaf material was dried and weighed, and decay rate coefficients were calculated. Macroinvertebrates colonizing the bags were enumerated and identified, and selected taxa were placed into trophic groups. We found that the unburned stream had the fastest leaf litter breakdown rate, the lowest level of incident light reaching the stream, and the largest amount of benthic organic matter. The burned/scoured stream was nearly opposite in all respects. Numbers of 2 detritivore invertebrate taxa, Serratella tibialis and Zapada oregonensis, were highest in the unburned stream but lowest in the burned/scoured stream. A third taxon, Baetis sp., showed the opposite relationship. Presence of predatory invertebrates did not affect detritivore abundance or leaf decay rate in the bags. Our research suggests that recovery response variables of some stream systems may not have returned to prefire levels even a decade after the initial wildfire. In this study, the recovery of our streams appears to be connected to the return of the riparian zone, though fire-induced debris flows may slow or alter final recovery of the stream system.     

The prevalence of Echinococcus granulosus and other taeniid cestodes in sheep dogs of central Utah

Fifty-one of 62 sheep dogs in central Utah were successfully purged for diagnosis of cestodes in 1981. Tapeworms were identified in the purged fecal samples of 33 (64.7 percent) animals. Minimum infection rates in the dogs which were purged were; 9.8 percent for Echinococcus granulosus , 29.4 percent for Taenia pisiformis , 27.5 percent for T. ovis krabbei , 27.5 percent for T. hydatigena , and 2.0 percent for T. serialis . The prevalence of E. granulosus decreased from 27 percent in 1971 to 9.8 percent in 1981.     

Pogonomyrmex ewyheei nest site density and size on a minimally impacted site in central Oregon

Little is known about the basic characteristics of the western harvester ant ( Pogonomyrmex owyheei ) in the absence of anthropogenic disturbances. We examined the role of P. owyheei as an agent of disturbance in an area of semiarid vegetation in central Oregon known as the Horse Ridge Research Natural Area (HRRNA) that has been largely free of livestock grazing and other significant anthropogenic influences for over 23 yr. We determined density and size characteristics of nest sites and estimate total area cleared by P. owyheei activities on HRRNA. From random sampling of twenty-five 0.04-ha plots we found a mean nest density/standard error of 1.6(± 0.16) nests/0.04 ha. Mean area cleared per nest site was 4.8 m 2 , which results in an estimated barren area of 46,080 m 2 on the 240-ha HRRNA. Comparing our findings to others on P. owyheei and P. occidentalis , we found nest density and mean cleared area to be in the middle range of reported observations under a variety of land-use influences. The literature suggests that moderate disturbance may increase nest site density, but little relationship exists between disturbance history and mean size of nest sites.     

What is ontic structural realism?

In recent years a doctrine known as ontic structural realism (OSR) has achieved a degree of notoriety, but many people remain confused as to what exactly the doctrine amounts. In this paper three main variants of OSR are defined and discussed: (i) OSR1, which is the view that relations are ontologically primitive but objects and properties are not; (ii) OSR2, which is the view that objects and relations are ontologically primitive but properties are not; (iii) OSR3, which is the view that properties and relations are ontologically primitive but objects are not. Proponents of OSR claim that it is a “naturalistic” metaphysics, arguing that metaphysical views that take objects and/or properties as ontologically primitive are undermined by contemporary physics. In this paper it is argued that OSR1 and OSR2 are themselves undermined by contemporary physics. On the other hand, it is also argued that considerations about the objects of quantum mechanics and general relativity do seem to suggest that we should abandon some of our “common-sense” metaphysical intuitions, and that OSR3 is one of the metaphysical views that is compatible with what these theories seem to tell us about fundamental ontology.