Trichomonas gallinae in wintering Common Wood Pigeons Columba palumbus in Spain

We studied the prevalence and potential subclinical effects of infestation by Trichomonas gallinae in 91 hunter-harvested Common Wood Pigeons Columba palumbus from northern ( n  = 30) and southern ( n  = 61) Spain during the winter period. All animals were measured, sexed, aged, necropsied and their organs were weighed. Infestation with T. gallinae was diagnosed using three different methods: direct inspection for the presence of lesions, direct microscopic observation and culture. Of the sampled birds, 34.2% were positive for the presence of T. gallinae . Prevalence was significantly higher in adult Wood Pigeons than in the juvenile group, and prevalence was significantly lower in birds sampled from the north. No significant differences in prevalence were found between males and females. Culture was significantly more sensitive than the other methods of diagnosis. Parasitized birds were in poorer body condition, as revealed by their lower body mass and fat reserves. No significant variation could be detected in heart or spleen weight between parasitized and healthy birds. However, juvenile Wood Pigeons in which T. gallinae was detected had a significantly larger bursa of Fabricius. Variations in the prevalence of T. gallinae in Wood Pigeons could be related to migration as well as increased exposure through shared feed and water where these are artificially provided. We also discuss the potential effect of T. gallinae on body condition and the eventual risk for endangered predators through increased exposure to infected prey.     

A Fossilized Microcenosis In Triassic Amber

ABSTRACT Detailed data on bacterial and protistan microfossils are presented from a 0.003 mm³ piece of Triassic amber (Schlierseerit, Upper Triassic period, 220-230 million years old). This microcenosis, which actually existed as such within a very small, probably semiaquatic habitat, included the remains of about two bacteria species, four fungi ( Palaeodikaryomyces baueri, Pithomyces -like conidia, capillitium-like hyphae, yeast cells) two euglenoids, two chlamydomonas ( Chlamydomonas sp., Chloromonas sp.), two coccal green microalgae ( Chlorella sp., Choricystis -like cells), one zooflagellate, three testate amoebae ( Centropyxis aculeata var. oblonga-like, Cyclopyxis eurystoma -like, Hyalosphenia baueri n. sp.), seven ciliates ( Pseudoplaryophrya nana -like, Mykophagophrys terricola -like, Cyrtolophosis mucicola -like, Paracondylostoma sp., Bryometopus triquetrus -like. Tetrahymena rostrata -like, Paramecium triassicum n. sp.) the microfossils correspond to or diverge from extant species only slightly.     

Comparative anatomy of the heart of mammals

Hearts from 20 mammalian orders were examined according to a fixed protocol to determine if the gross differences of shape and internal anatomy could be explained. Three generalizations can be made: firstly differences are most closely related to taxonomic position, secondly some features, such as the prominence of the conus of the right ventricle in animals that leap, dig or sprint regularly as part of their defence mechanism and a long, narrow left ventricle in endurance performers may be more closely related to activity than ancestry, and lastly some characteristics may be pleiotropic effects of thoracic morphogenesis.     

Influence of Donor Age on Establishing Well-Differentiated Clonal Cultures from Embryonic Chicken Retinal Pigmented Epithelium

Retinal pigmented epithelia (RPE) isolated from chicken embryos of various developmental stages were dissociated into single cells, and their ability to re-express defferentiated characteristics in clonal culture was investigated. The lighty pigmented, columnar cells isolated from stage 25 to 29 embryos dissociated more easily than the heavily pigmeted, cuboidal cells from embryos of stages 30 to 34. The yield of RPE cells per embryo increased with donor age, paralleling the growth of the epithelium in vivo . However, the potential these cells to attach, to proliferate, and to form typical, welldifferentiated RPE colonies declined with donor age. Cells from stage 25 embryos developed exclusively into large, typical epithelial colonies which expressed all stages of differentiation from flat, unpigmented cells at the margin to cuboidal, pigmented cells in the centre. At the other end of the spectrum, cells from stage 34 embryos frequently formed small, atypical colonies of unpigmented cells, in addition to typical but relatively small colonies. The plating efficiency (calculated on the basis of pigmented colonies formed within 3 weeks) dropped from more than 2% at stage 25 to 0.01% at stage 34.     

Resistance and Sensitivity of Chloroplast Ribosomes to Streptomycin in Mutants of Chlamydomonas reinhardi

• 1 In a mendelian (sr₃) and an uniparental (sr₃₅) streptomycin resistant mutant of Chlamydomonas reinhardi the influence of streptomycin on protein synthesis on the chloroplast and cytoplasmic ribosomes was investigated in vitro. Hetero-, mixo- and phototrophic agar cultures and heterotrophic liquid cultures were used.
• 2 Protein synthesis on the cytoplasmic ribosomes, measured by the activity of glyceraldehyde-3-phosphate: NADP dehydrogenase (EC 1.2.1.9), was not inhibited, but rather stimulated by streptomycin.
• 3 Protein synthesis on the chloroplast ribosomes of sr₃, measured by the activity of ribulose-1,5-diphosphate carboxylase (EC 4.1.1.39), was greatly inhibited by streptomycin, especially in hetero- and mixotrophic cultures. In sr₃₅ the chloroplast ribosomes were resistant to streptomycin.
• 4 Heterotrophically grown cultures of sr₃ and of a streptomycin-sensitive strain are yellow in the presence of streptomycin and form no or only reduced thylakoids on solid media. But 70-S organelle-ribosomes are present in a normal amount.
• 5 The relationship between chloroplast protein synthesis and thylakoid formation is discussed.