The ultrastructure of chemolithoautotrophic Gallionella ferruginea and Thiobacillus ferrooxidans as revealed by chemical fixation and freeze-etching

By using sodium thioglycolate to dissolve the high amount of excreted stalk material in axenic cultures of the chemolithoautotrophic iron bacterium Gallionella ferruginea, the ultrastructure of Gallionella cells from pure cell suspensions could be studied without any loss of viability or disturbance by dense ferric stalk fibers, and compared with Thiobacillus ferrooxidans, also grown chemolithoautotrophically with ferrous iron as energy source. Both organisms were chemically fixed or freeze-etched. Particular structural differences between these iron-bacteria could be ascertained. G. ferruginea possesses intracytoplasmic membranes and soluble d-ribulose-1,5-bisphosphate-carboxylase, whereas T. ferrooxidans contains carboxysomes but no intracytoplasmic membranes; Gallionella forms poly--hydroxybutyrate and glycogen as storage material; T. ferrooxidans produces only glycogen. Both organisms also differ from each other with respect to the freeze fracture behaviour of the cell envelope layers. Whereas the cells of T. ferrooxidans exhibit a characteristic double cleavage, exposing the plasmic fracture face and exoplasmic fracture face of the outer membrane and cytoplasmic membrane, the exceptionally thin multilayered cell envelope of G. ferruginea revealed a particularly intimate association between the layers, resulting in a visualisation of the supramolecular organisation of only the inner fracture face of the cytoplasmic membrane. The results are discussed predominantly in relation to the extremely distinct environments of both organisms.     

Longitudinal age changes in a fishermen population of West Bengal

The longitudinal anthropological age changes in a sample of coastal fishermen in West Bengal are discussed. The results show that some traits follow the trends observed in ageing of Western populations, for instance nasal length and breadth continue to increase throughout life in both sexes. Stature follows also the trend generally observed: a decrease occurs indeed from 35 years of age in both sexes, the decline is becoming higher with increasing age. The typical ecological conditions of our population influence the rate of change in other traits, such as weight and biacromial diameter. Weight is known to be influenced by the nutritional status and the way of life. It explains that in our study of males an early increase of weight and biacromial diameter is observed first and a decrease afterwards. In females, however, a decrease is observed already from 35 years of age. This kind of analysis was only possible with the help of longitudinal data and in a well defined population: only longitudinal data is free from the effect of secular changes and of selective death.     

Induction and modification of dinitrogenase reductase in the unicellular cyanobacterium Synechocystis BO 8402

Oxygen is an important regulatory factor of nitrogenase induced in a unicellular cyanobacterium, Synechocystis BO 8402, during nitrogen starvation. Synthesis of the enzyme is limited by the efficiency of the cells to remove oxygen by respiration, supported by hydrogenases and, in the light, by inhibition of photosynthesis. With a polyclonal antibody against dinitrogenase reductase (the Fe protein of nitrogenase) a single polypeptide is detected, indicative of an active dimeric enzyme in dense cell suspensions. Inhibition of nitrogenase by addition of oxygen is accompanied by the appearance of a second polypeptide of the Fe protein having a 1.5 kDa higher molecular weight. This disappears upon removal of oxygen from the gas phase while nitrogenase activity is restored. No protein synthesis is required indicating that a fraction of the existing polypeptides is reversibly modified in response to oxygen. After induction of nitrogenase activity in dilute culture suspensions, both forms of the Fe-protein are found in variable amounts possibly due to oxygen contamination during the experiment.Abbreviations CAM chloramphenicol - Chl chlorophyll a - CHO carbohydrates - DCMU 3,4-dichlorophenyl-1,1-dimethylurea (diuron) - kDa kilodalton - SDS sodium dodecylsulphate     

Molecular genetic analysis of 67 patients with duchenne/becker muscular dystrophy

Summary A total of 56 Duchenne muscular dystrophy (DMD) patients and 11 Becker muscular dystrophy (BMD) patients was analyzed by extended multiplex amplification of the DMD/BMD gene; deletions were found in 60% of these patients. The data obtained were used to test the frameshift hypothesis and to compare the distribution of familial versus isolated cases. A significant correlation was found between deletions and isolated cases. Additional experiments were performed in order to determine the deletion breakpoints more precisely. These data are a prerequisite for carrier analysis in the respective families by detection or exclusion of aberrant cDNA fragments derived from ectopic lymphocyte RNA. This diagnostic technique is illustrated by 5 examples.     

Retino-fugal projections in congenitally monophthalmic fish and anurans

Summary Intra-ocular deposition of horseradish peroxidase was used to visualize optic tract projections in normal and congenitally monophthalmic catfish and Xenopus. In neither species was evidence for an increased ipsilateral visual component found in congenitally one-eyed specimens. This indicates that competition between axons from both eyes is not an important mechanism for fiber distribution in the chiasm during ontogeny. Furthermore, it suggests that enhanced ipsilateral components, previously noted in unilaterally enucleated fish and anurans, are caused by debris of degenerated axons.     

Age changes of skull dimensions

At cranial level, external apposition during ageing has been postulated by some authors. In longitudinal studies, a gradual increase of cranial diameters has been shown by cephalometry (Kendrick et al. 1967) or by lateral radiography (Israel 1968, 1970). However, these results are contested at methodological level by other longitudinal studies (Tallgren 1974). It is the aim of this study to analyse, in a cross-sectional sample, the effects of senescence on several cephalic dimensions. A series of skulls of known age and sex has been selected for this purpose.     

Uranium mobilization from low-grade ore by cyanobacteria

Summary Three cyanobacterial isolates (two LPP-B forms and one Anabaena or Nostoc species) from different environments could mobilize uranium from low-grade ores. After 80 days, up to 18% uranium had been extracted from coal and 51% from carbonate rock by the filamentous cyanobacterium OL3, a LPP-B form. Low growth requirements with regard to light and temperature optima make this strain a possible candidate for leaching neutral and alkaline low-grade uranium ores.