Biochemical and Ultrastructural Changes in Tetrahymena pyriformis During Starvation*

SYNOPSIS. Certain of the ultrastructural and biochemical changes occurring during the first 25 hr of starvation in Tetrahymena pyriformis were studied. Ultrastructurally, numerous profiles of degenerating mitochondria were seen in the early stages of starvation. The presence of oxidizable substrate such as glucose and acetate did not prevent this degeneration. Numerous large nucleoli were formed, many of which seemed to be passing into the cytoplasm as forming autophagic vacuoles. There was a transient increase in Oil Red O-positive bodies, presumably lipid (triglycerides). The extent and duration of this increase were pronounced in the presence of acetate. The lipid droplets appeared to arise within the cisternae of the endoplasmic reticulum. Lipid reserves were apparently utilized prior to carbohydrates, as the disappearance of lipid droplets preceded glycogen utilization, both in the presence of acetate and in the absence of exogenous substrate. A considerable loss of cellular protein also occurred. In cells from inorganic medium supplemented with glucose, glycogen occupied much of the cell, leaving only islands of cell organelles. Acid phosphatase was localized, ultrastructurally, mainly in autophagic vacuoles which contained mitochondria and other cell organelles, and in association with small, double-membraned structures which seemed to be sequestering small areas of cytoplasm. Such sequestered areas also appeared within larger autophagic vacuoles. Residual bodies containing concentric whorls of myelin-like membranes surrounding a more solid core accumulated during starvation. Acid phosphatase activity decreased in amount but not in specific activity. The specific activity of cathespin doubled or tripled, but there was little change in total enzyme.     

Effects of Protease Inhibitors on Protein Breakdown and Enzyme Induction in Starving <Emphasis Type="Italic">Escherichia coli</Emphasis>

PROTEIN degradation is relatively slow in growing bacteria but much faster when there is no source of carbon or nitrogen^1–3. These changes in degradative rates seem to be important for the adaptation of the cell to non-growing conditions and may be controlled by mechanisms similar to those regulating synthesis of ribosomal RNA⁴. Identification of selective inhibitors of protein breakdown could greatly facilitate study of the mechanisms of this process and its physiological significance.     

Diversity of mitochondrial large subunit rDNA haplotypes of Glomus intraradices in two agricultural field experiments and two semi‐natural grasslands

Glomus intraradices, an arbuscular mycorrhizal fungus (AMF), is frequently found in a surprisingly wide range of ecosystems all over the world. It is used as model organism for AMF and its genome is being sequenced. Despite the ecological importance of AMF, little has been known about their population structure, because no adequate molecular markers have been available. In the present study we analyse for the first time the intraspecific genetic structure of an AMF directly from colonized roots in the field. A recently developed PCR‐RFLP approach for the mitochondrial rRNA large subunit gene (mtLSU) of these obligate symbionts was used and complemented by sequencing and primers specific for a particularly frequent mtLSU haplotype. We analysed root samples from two agricultural field experiments in Switzerland and two semi‐natural grasslands in France and Switzerland. RFLP type composition of G. intraradices (phylogroup GLOM A‐1) differed strongly between agricultural and semi‐natural sites and the G. intraradices populations of the two agricultural sites were significantly differentiated. RFLP type richness was higher in the agricultural sites compared with the grasslands. Detailed sequence analyses which resolved multiple sequence haplotypes within some RFLP types even revealed that there was no overlap of haplotypes among any of the study sites except between the two grasslands. Our results demonstrate a surprisingly high differentiation among semi‐natural and agricultural field sites for G. intraradices. These findings will have major implications on our views of processes of adaptation and specialization in these plant/fungus associations.     

Stimulation of Ribulose Bisphosphate Carboxylase Activity by Inorganic Orthophosphate without an Increase in Bound Activating CO2: Co-operativity between the Subunits of the Enzyme

Parry, M. A. J., Schmidt, C. N. G., Cornelius, M. J., Keys,A. J., Millard, B. N. and Gutteridge, S. 1985. Stimulation ofribulose bisphosphate carboxylase activity by inorganic orthophosphatewithout an increase in bound activating CO²: co-operativitybetween the subunits of the enzyme.—J. exp. Bot. 36: 1396–1404 Ribulose bisphosphate carboxylase/oxygenase (E.C. 4.1.1.39 [EC] )from wheat (Triticum aestivum L.), already activated by reactionwith CO² and Mg²⁺, was increased in activity on addition ofinorganic orthophosphate. This further activation took placewithout a significant increase in the amount of bound activatingCO² and the effect was relatively greater with smaller amountsof bound CO². With less than 2·0 mol of CO² bound permol holoenzyme, phosphate increased activity about five-foldwhilst with 7·0 mol of bound activating CO² per mol holoenzyme,phosphate increased activity by a factor of only 1 ·8.This decrease in the effect of orthophosphate with increasein bound activating CO² suggests negative co-operativity betweenactivated sites. The stimulation of activity by inorganic orthophosphatemust be a process distinct from activation by CO²; it was observedwith both the slow and the rapidly activating forms of ribulosebisphosphate carboxylase/oxygenase from wheat. Key words: Ribulose bisphosphate carboxylase, activation, inorganic orthophosphate CO², co-operativity     

Survival, ranging, habitat choice and diet of the Northern Goshawk Accipiter gentilis during winter in Northern Finland

The winter ecology of the Northern Goshawk Accipiter gentilis was studied in northern Finland in 1991-95. The data consist of 26 radiomarked hawks, of which 331 day and 299 night positions were located. Average range size was 9894 ha for males (minimum convex polygon, n = 4) and 6282 ha for females ( n = 11). Ranges calculated by the 75% harmonic mean contour gave range areas of 3283 ha for males ( n = 3) and 2753 ha for females ( n = 11). Harmonic mean centres concentrated near human settlements, implying better food availability there compared with woodland areas. Some Goshawks preyed upon animals living in the city dump in late winter. Goshawks preferred deciduous and mature conifer forests and avoided open areas such as fields and bogs. They also avoided very heterogeneous sites. The winter diet consisted mostly of Mountain Hares Lepus timidus (30.9%), Red Squirrels Sciurus vulgaris (23.6%), Brown Rats Rattus norvegicus (12.7%) and forest grouse Tetraonidae (27.1%), of which Black Grouse Tetrao tetrix was the most important (14.5%). By weight, hares constituted 70% of the biomass consumed.     

The Distribution of Tetrahymena pyriformis1

SYNOPSIS. This paper is a brief account of both amicronucleate and sexually active strains of Tetrahymena pyriformis and their distribution with some comments on their possible evolution.     

The trace fossil Nummipera eocenica from the Tatra Mountains,Poland: morphology and palaeoenvironmental implications

Jach, R., Machaniec, E. & Uchman, A. 2011: The trace fossil Nummipera eocenica from the Tatra Mountains, Poland: morphology and palaeoenvironmental implications. Lethaia, Vol. 45, pp. 342–355. The tubular trace fossil Nummipera eocenica Hölder 1989 occurs in a single stratigraphical horizon in Eocene nummulitic limestones of the Tatra Mountains, Poland. The wall of N. eocenica is built of Discocyclina and Nummulities (larger foraminifera) tests, very rarely of the Ditrupa (Polychaeta) tube fragments, bivalve shell fragments, echinoid spines and coralline algae. Morphotype are distinguished on the basis of wall composition and structure. Morphotype A is dominated by fusiform Discocyclina tests, which were preferentially selected by the trace makers for construction of a well‐constructed and resistant wall. Morphotype B contains more robust tests of Nummulites, while morphotype C is dominated by saddle‐shaped tests of Discocyclina. Nummipera eocenica was produced during a period of seafloor stabilization caused by a deepening. The succession of the morphotypes B, A reflects diminishing energy and increasing water depth. Probably morphotype C represents even lower energy environment than morphotype A. The trace fossil is interpreted as a domichnion, which wall was constructed for protection. The trace maker can be considered between polychaetes and crustaceans; however, comparisons to the closest recent analogues, the polychaete Diopatra cuprea or alpheid shrimps, are not satisfactory. □Bartonian, burrow, Carpathians, large foraminifera, trace fossils.     

Did Polyommatus icarus (Lepidoptera: Lycaenidae) have distinct glacial refugia in southern Europe? Evidence from population genetics

Pleistocene climatic oscillations strongly influenced the genetic composition of many species which are often divided into several genetic lineages. In this context, we studied the allozymes of a common and widely distributed butterfly, the common blue Polyommatus icarus, over a large part of Europe. The species had a rather high genetic diversity within populations with a strikingly high mean number of alleles per locus (2.98). In contrast, differentiation between populations was very low ( F _ST: 0.0187). Only a marginal trend of decline in genetic diversity from the south to the north was observed. Isolation-by-distance existed on a European scale ( r =  0.826), but not at a regional level. Regional differentiation between populations in western Germany was extremely low ( F _ST: 0.0041). It is probable that P. icarus was widely distributed in the Mediterranean region during the last ice age and expanded into central Europe in the postglacial period without major genetic erosion. Moderate present and past gene flow in an intact metapopulation structure may have occurred on local, regional and perhaps even continental scales.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 529–538.     

The Effect of Puromycin and Cycloheximide on the Infection of Algae-Free Paramecium bursaria by Symbiotic Chlorellae1

It has been suggested that the infection of algae-free Paramecium bursaria by symbiotic algae involves an induction in the ciliate. Such a process suggests a need for the synthesis of specific proteins. Therefore, an attempt was made to determine the role of protein synthesis during the initial phases of host-symbiont interaction by examining the capacity of the ciliate to form a stable association with algae when the ciliate is exposed to puromycin (PURO) or cycloheximide (CYC) during the first 1–3 h of algal insestion. Cycloheximide (100 μg/ml) blocked algal but not ciliate growth and protein synthesis while PURO (250 μg/ml) appeared to inhibit these processes in both Puromycin significantly inhibited the infection when presented to the ciliate during the first hour of algal exposure and had little effect when added after that period. Inhibition of ciliate, as compared to the alga, protein synthesis appears to be significant in relationship to those processes leading to infection, as CYC when presented during the first hour of algae-ciliate exposure has no inhibitory effects. Experiments on algal sugar secretion and ciliate ingestion of algae indicated that neither process was significantly affected by these inhibitors. These results point to a need for host protein synthesis during the initial phase of ingestion of algae which appears to be important to establishment of the symbiotic association.