Intranukleäre Einschlusskörper in Neuronen alternder Ratten

Summary Intranuclear rodlet shaped structures similar to those recently observed in human multiple sclerosis biopsy material were found in cortical neurons of aging rats. The morphology of these structures is described and their possible significance discussed.     

Tetracalcium hydrogen triphosphate trihydrate,a constituent of dental calculus

Zusammenfassung Die überwiegenden Bestandteile des Zahnsteins sind Apatit, magnesiumhaltiger Whitlockit mit rund 7 Atomprozent Magnesium und (nur in der Mandibularregion) Brushit. Als untergeordneten Bestandteil haben wir in 48 von 124 untersuchten Zahnsteinproben auch Tetracalcium-hydrogen-triphosphat-trihydrat gefunden.      

In situ structure of the complete Treponema primitia flagellar motor

The bacterial flagellar motor is an amazing nanomachine: built from approximately 25 different proteins, it uses an electrochemical ion gradient to drive rotation at speeds of up to 300 Hz (refs 1, 2). The flagellar motor consists of a fixed, membrane-embedded, torque-generating stator and a typically bidirectional, spinning rotor that changes direction in response to chemotactic signals. Most structural analyses so far have targeted the purified rotor, and hence little is known about the stator and its interactions. Here we show, using electron cryotomography of whole cells, the in situ structure of the complete flagellar motor from the spirochaete Treponema primitia at 7 nm resolution. Twenty individual motor particles were computationally extracted from the reconstructions, aligned and then averaged. The stator assembly, revealed for the first time, possessed 16-fold symmetry and was connected directly to the rotor, C ring and a novel P-ring-like structure. The unusually large size of the motor suggested mechanisms for increasing torque and supported models wherein critical interactions occur atop the C ring, where our data suggest that both the carboxy-terminal and middle domains of FliG are found.     

Urbanization impacts on the trophic guild composition of bird communities

Urbanization transforms the landscape and generates loss of pristine habitats. We investigated the urbanization effect on bird communities in a growing South American city (Santa Fe, Argentina) and hypothesized that if habitat structure and human disturbance change along an urban gradient, the richness and abundance of trophic guilds should also vary accordingly. We placed 50 transects 100 m long × 50 m wide in five districts with different levels of urbanization, determined by habitat structure variables. We recorded the number and abundance of species and the amount of pedestrians and vehicles passing through each transect. We recorded 23% of all bird species known for the Santa Fe province and categorized them within 19 trophic guilds. The percentage of area covered by herbaceous vegetation, water bodies and trees and shrubs had a positive relationship with the richness and abundance of most of trophic guilds (hawking aerial, terrestrial, bark and foliage insectivores; terrestrial and generalized granivores; generalized, aquatic diving and foliage omnivores; hawking aerial, aquatic diving and striding carnivores; nectarivores; and aquatic filters). Pavement surface and human disturbance variables had a negative relationship with the richness, and high buildings and pavement surface had a positive relationship with the abundance of terrestrial omnivores and coursing aerial insectivores. Variation partitioning revealed that habitat structure and human disturbance were better predictors of the richness than the abundance of each trophic guild. Results showed that trophic guilds associated to vegetation strata were seen to increase their richness and abundance towards green areas, even if they presented generalist or specialist habits. Urban planners should conserve or manage the surrounded natural spaces when the growth of the city is directed to these areas and increase the availability of environmental features within the urban matrix.     

Three-year surveillance for cestode infections in sheep dogs in central Utah

During the summers of 1982, 1983, and 1984, 269 sheep dogs from an area endemic for hydatid disease were examined for cestodes ( Echinococcus granulosus and Taenia spp.). Each dog was given an oral purge of arecoline hydrobromide and then following purgation received a subcutaneous injection of praziquantel (Droncit ® ). During the three-year study period, 205 dogs were examined one time only, 48 dogs were examined two of the three years, and 16 dogs were examined each of the three years (= 349 separate examinations). In 1982, 45 of 91 dogs examined (49.5%) harbored at least one species of cestode. Those data for 1983 and 1984 were 55 positive of 141 examined (39.0%) and 34 positive of 117 examined (29.1%), respectively. The marked drop in dogs infected during the second and third year of the study suggests that many sheep ranchers were implementing some of the control measures recommended for prevention of E. granulosus infections. The numbers of separate purgations showing specific cestodes detected in all positive dogs (some dogs naturally with more than one species of cestode) were: E. granulosus, 16 (4.6%); T. hydatigena, 34 (9.7%); T. ovis krabbei, 46 (13.2%); T. pisiformis, 47 (13.5%); and T. serialis, 24 (6.9%).     

A linguistic model for the rational design of antimicrobial peptides

Antimicrobial peptides (AmPs) are small proteins that are used by the innate immune system to combat bacterial infection in multicellular eukaryotes. There is mounting evidence that these peptides are less susceptible to bacterial resistance than traditional antibiotics and could form the basis for a new class of therapeutic agents. Here we report the rational design of new AmPs that show limited homology to naturally occurring proteins but have strong bacteriostatic activity against several species of bacteria, including Staphylococcus aureus and Bacillus anthracis. These peptides were designed using a linguistic model of natural AmPs: we treated the amino-acid sequences of natural AmPs as a formal language and built a set of regular grammars to describe this language. We used this set of grammars to create new, unnatural AmP sequences. Our peptides conform to the formal syntax of natural antimicrobial peptides but populate a previously unexplored region of protein sequence space.     

Proteome survey reveals modularity of the yeast cell machinery

Protein complexes are key molecular entities that integrate multiple gene products to perform cellular functions. Here we report the first genome-wide screen for complexes in an organism, budding yeast, using affinity purification and mass spectrometry. Through systematic tagging of open reading frames (ORFs), the majority of complexes were purified several times, suggesting screen saturation. The richness of the data set enabled a de novo characterization of the composition and organization of the cellular machinery. The ensemble of cellular proteins partitions into 491 complexes, of which 257 are novel, that differentially combine with additional attachment proteins or protein modules to enable a diversification of potential functions. Support for this modular organization of the proteome comes from integration with available data on expression, localization, function, evolutionary conservation, protein structure and binary interactions. This study provides the largest collection of physically determined eukaryotic cellular machines so far and a platform for biological data integration and modelling.