Homologies between higher plant and algal 25S cytoplasmic ribosomal RNA

Using heat and urea treatment, the degradation products of denatured 25S cytoplasmic ribosomal RNA from jack bean (a higher plant) and $\text{Chlamydomonas reinhardi}$ (an alga) were compared. Several specific modes of 25S RNA breakdown are postulated. The results suggest that (1) both higher plant algal 25S RNA may contain homologous endonuclease susceptible regions as judged by the stoichiometry of degradation and (2) that similar secondary structural properties of 25S cytoplasmic RNA have been conserved by evolution in the plant kingdom.     

Disruption of membrane functions in Fusarium culmorum by an acetylenic allelochemical

The acetylenic allelochemical, phenylheptatriyne (PHT), from species of the Asteraceae disrupts membrane function in Fusarium culmorum by both phototoxic and non-phototoxic mechanisms. Treatment of mycelia or macroconidia with 10 ppm PHT leads to an aggregation of lipids visible in Sudan Black stained material. This characteristic stress response increases in conjunction with photosensitizing wavelengths of radiation (near UV). Mild treatment of PHT (10 ppm) and near UV (5 Wm²/50 min) inhibit ¹⁴C phenylalanine uptake and respiration and enhance K¹ leakage suggesting that the membrane is the primary site of action of PHT.     

A reproducible method for producing and quantifying the stages of fracture repair.

Male CD-1 mice, 4 to 6 months of age, were used to establish a reproducible model to study the stages of fracture repair. A custom-designed fracture apparatus was constructed, and trials with it demonstrated its capacity to reliably reproduce a closed fracture of the tibia. Dietary and sleep habits in the treated mice were the same as unfractured control mice. Four stages of fracture repair were documented and the duration of each stage was quantifiable and reproducible. The last stage of fracture repair was completed by 21 days postfracture. The reproducibility of the fracture, the reproducibility of the times and stages of fracture repair, the relatively short time to complete the fracture repair process, and the minimal discomfort which allowed the mice to maintain a normal daily routine, suggest that this is an ideal animal model for studying the fracture repair process.     

Evaluation of D1 and D2 Dopamine Receptor Segregation in the Developing Striatum Using BAC Transgenic Mice

The striatum is predominantly composed of medium spiny neurons (MSNs) that send their axons along two parallel pathways known as the direct and indirect pathways. MSNs from the direct pathway express high levels of D1 dopamine receptors, while MSNs from the indirect pathway express high levels of D2 dopamine receptors. There has been much debate over the extent of colocalization of these two major dopamine receptors in MSNs of adult animals. In addition, the ontogeny of the segregation process has never been investigated. In this paper, we crossed bacterial artificial chromosome drd1a-tdTomato and drd2-GFP reporter transgenic mice to characterize these models and estimate D1-D2 co-expression in the developing striatum as well as in striatal primary cultures. We show that segregation is already extensive at E18 and that the degree of co-expression further decreases at P0 and P14. Finally, we also demonstrate that cultured MSNs maintain their very high degree of D1-D2 reporter protein segregation, thus validating them as a relevant in vitro model.     

The effects of long-term endurance training on the immune and endocrine systems of elderly men: the role of cytokines and anabolic hormones

Background  

a decline in immune and endocrine function occurs with aging. The main purpose of this study was to investigate the impact of long-term endurance training on the immune and endocrine system of elderly men. The possible interaction between these systems was also analysed.     

Why do parasitized hosts look different? Resolving the “chicken-egg” dilemma

Phenotypic differences between infected and non-infected hosts are often assumed to be the consequence of parasite infection. However, pre-existing differences in hosts’ phenotypes may promote differential susceptibility to infection. The phenotypic variability observed within the host population may therefore be a cause rather than a consequence of infection. In this study, we aimed at disentangling the causes and the consequences of parasite infection by calculating the value of a phenotypic trait (i.e., the growth rate) of the hosts both before and after infection occurred. That procedure was applied to two natural systems of host–parasite interactions. In the first system, the infection level of an ectoparasite (Tracheliastes polycolpus) decreases the growth rate of its fish host (the rostrum dace, Leuciscus leuciscus). Reciprocally, this same phenotypic trait before infection modulated the future level of host sensitivity to the direct pathogenic effect of the parasite, namely the level of fin degradation. In the second model, causes and consequences linked the growth rate of the fish host (the rainbow smelt, Osmerus mordax) and the level of endoparasite infection (Proteocephalus tetrastomus). Indeed, the host’s growth rate before infection determined the number of parasites later in life, and the parasite biovolume then decreased the host’s growth rate of heavily infected hosts. We demonstrated that reciprocal effects between host phenotypes and parasite infection can occur simultaneously in the wild, and that the observed variation in the host phenotype population was not necessarily a consequence of parasite infection. Disentangling the causality of host–parasite interactions should contribute substantially to evaluating the role of parasites in ecological and evolutionary processes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.