Ultrastructural alterations in Tetrahymena pyriformis induced by growth on saturated phospholipids at 40.1 °C

Structural changes in Tetrahymena pyriformis, strain WH-14, induced by growth on saturated phospholipids at 40.1 °C, were studied by electron microscopy. Alterations in the ultrastructural organization of the cell membrane and surface regions were common. These alterations were characterized in the displacement of kinetosomes, the spatial disorientation and disorganization of cortical ridges and grooves, and the spatial disorientation of longitudinal and transverse microtubular ribbons. Irregular surface protrusions and multiple invaginations of alveolar membranes were among the most common features encountered. Disorganization of longitudinal microtubular ribbons was also a frequent encounter. The integrity of the ultrastructure of cell surface membranes and of the internal organization and ultrastructure of the kinetosomes, however, appeared to be unaltered. Other alterations included those of a number of cytoplasmic organelles (e.g. mitochondria and endoplasmic reticulum), which showed characteristic changes in structural patterns.     

Sources of Vibrio mimicus Contamination of Turtle Eggs

Vibrio mimicus contamination of sand increased significantly during the arrival of the olive ridley sea turtles (Lepidochelys olivacea) at Ostional anidation beach, Costa Rica. Statistical analysis supports that eggs are contaminated with V. mimicus by contact with the sand nest. V. mimicus was isolated from eggs of all nests tested, and ctxA⁺ strains were found in 31% of the nests, all of which were near the estuary.     

The H3.3K27M oncohistone affects replication stress outcome and provokes genomic instability in pediatric glioma

While comprehensive molecular profiling of histone H3.3 mutant pediatric high-grade glioma has revealed extensive dysregulation of the chromatin landscape, the exact mechanisms driving tumor formation remain poorly understood. Since H3.3 mutant gliomas also exhibit high levels of copy number alterations, we set out to address if the H3.3K27M oncohistone leads to destabilization of the genome. Hereto, we established a cell culture model allowing inducible H3.3K27M expression and observed an increase in mitotic abnormalities. We also found enhanced interaction of DNA replication factors with H3.3K27M during mitosis, indicating replication defects. Further functional analyses revealed increased genomic instability upon replication stress, as represented by mitotic bulky and ultrafine DNA bridges. This co-occurred with suboptimal 53BP1 nuclear body formation after mitosis in vitro, and in human glioma. Finally, we observed a decrease in ultrafine DNA bridges following deletion of the K27M mutant H3F3A allele in primary high-grade glioma cells. Together, our data uncover a role for H3.3 in DNA replication under stress conditions that is altered by the K27M mutation, promoting genomic instability and potentially glioma development.     

Bacterial biodiversity from anthropogenic extreme environments: a hyper-alkaline and hyper-saline industrial residue contaminated by chromium and iron

Anthropogenic extreme environments are among the most interesting sites for the bioprospection of extremophiles since the selection pressures may favor the presence of microorganisms of great interest for taxonomical and astrobiological research as well as for bioremediation technologies and industrial applications. In this work, T-RFLP and 16S rRNA gene library analyses were carried out to describe the autochthonous bacterial populations from an industrial waste characterized as hyper-alkaline (pH between 9 and 14), hyper-saline (around 100 PSU) and highly contaminated with metals, mainly chromium (from 5 to 18 g kg^?1) and iron (from 2 to 108 g kg^?1). Due to matrix interference with DNA extraction, a protocol optimization step was required in order to carry out molecular analyses. The most abundant populations, as evaluated by both T-RFLP and 16S rRNA gene library analyses, were affiliated to Bacillus and Lysobacter genera. Lysobacter related sequences were present in the three samples: solid residue and lixiviate sediments from both dry and wet seasons. Sequences related to Thiobacillus were also found; although strains affiliated to this genus are known to have tolerance to metals, they have not previously been detected in alkaline environments. Together with Bacillus (already described as a metal reducer), such organisms could be of use in bioremediation technologies for reducing chromium, as well as for the prospection of enzymes of biotechnological interest.     

Periportal fibrosis in human Schistosoma mansoni infection is associated with low IL-10, low IFN-gamma, high TNF-alpha, or low RANTES, depending on age and gender

Schistosoma mansoni infection is highly endemic in parts of Uganda, and periportal fibrosis is common in communities along the shore of Lake Albert. In this study, we have identified cellular immune responses associated with fibrosis. A cohort of 199 individuals aged 6-50, resident in the village for at least 10 years or since birth, were examined for evidence of periportal fibrosis by ultrasound using the Niamey protocol. Whole-blood samples were assayed for levels of nine cellular immune molecules (IL-3, IL-4, IL-5, IL-10, IL-13, TNF-alpha, IFN-gamma, IL-1beta, and RANTES) in the absence of in vitro Ag stimulation, and after stimulation with egg and worm Ags. A lack of Ag specificity allowed the number of variables in the analysis to be reduced by factor analysis. The resulting factor scores were then entered into a risk analysis using a classification tree algorithm. Children, adult males, and adult females had different factors associated with fibrosis. Most cases of fibrosis in children (eight of nine) were associated with low (<47th percentile) IL-10 factor scores. Adult females at lowest risk had relatively high IFN-gamma factor scores (>83rd percentile), whereas those at highest risk had a combination of intermediate (32nd to 83rd percentile) IFN-gamma and relatively high (>60th percentile) TNF-alpha factor scores. Adult males at lowest risk of fibrosis had moderate TNF-alpha factor scores (55th to 82nd percentile), and a high risk was associated with either high TNF-alpha factor scores (>82nd percentile), or intermediate TNF-alpha combined with low RANTES factor scores (<58th percentile). These results demonstrate that periportal fibrosis is associated with cytokine production profiles that vary with both age and gender.     

Vegetationsgürtel in den Wiesenbeständen des Gatačko Polje

Summary Plant zones (belts) formed by single or few species, pressed together on restricted areas or bands on a carst field in the Hercegovina have been described.Sometimes, similar belts, to which W. Koch 1926 referred to as topographic units appear on shores or gentle slopes around ponds or lakes.In the carst field, however, they appear on meadows. These field are subject to an extremely fluctuating moisture regime due to the climatic conditions and the geographic position of this area. During the rainy season they are often transformed into lakes of some meters depth while in summer the drought entirely stops the growth of vegetation which turns to dry, yellow masses.As the surface of the fields is seldom ideally flat, very changeable moisture conditions exist there which cause striking changes in the composition of the vegetable cover; from far away slight elevations of only some centimeters reveal themselves by their different floristic composition. Therefore, for the appearance of belts with their regular successions, as developed in the carst field in question, a slightly undulating surface is necessary as well as a soil poor in organic matter because its high capacity of keeping moisture softens considerably the extreme environmental conditions of these fields.The mentioned clumps of few species may be observed in all carst fields of Bosnia and the Hercegovina but in no one they are so conspicously developed as in the Gatako Polje, especially on its north-western part, where all the conditions wanted for their appearance are evidentally present. This field can, therefore, be considered as the key to their understanding.On this area small hills can be seen surrounded by white rings of Narcissus on its moist basis, followed by a green belt of Bromus racemosus along their slopes while the hilltop is covered with yellow clumps of Crepis setosa. On this area the whole vegetation is likewise divided into striking belts composed of few species, which are always to be found again on sites with the same amount of moisture or depth of water level at the same time of the growing season.The single zones and their succession are cited in the german text; the entire series, however, are not always present depending upon the nature of the slopes. On steep ones there is so to say not enough place for them to develop and one or even several zones may be absent. The zone of Scirpus lacustris is bound to sloughs usually water-filled while the first zone with a water level completely receding during the droughts is formed by a pure stand of Carex Goodenoughii. During the chief growing season, in june, the depth of the water level exceeds there 50 cm; at its margin, when the water level has reached about 15 cm, Heleocharis palustris takes the dominance. Under somewhat drier conditions follows Leucoium aestivum, a geophyte, which is, therefore very resistant against summer droughts. In the next zone with a water level of about 3–5 cm the aspect is dominated by Ranunculus acer, accompanied by few hydrophil species, while in the coming zone dry land is finally reached. There occur Narcissus angustifolius with the codominant Colchicum autumnale on a soil which contains a considerable degree of moisture. Under similar conditions a zone is formed by Alectorolophus major which borders sometimes the small brooks, crossing the fields. The next zone is already developed on dry soil. It is composed by Bromus racemosus which also takes vast areas if similar conditions are present. In drought years Bromus alone forms almost pure stands of a very monotonous aspect, while in wet ones it is buried by the higher growing Poa silvicola which evidentally needs more moisture in early spring. On its margin forms Heleocharis palustris a narrow, characteristic line, while the next zone is developed on some-what higher elevations. Moenchia mantica forms there a dense cover which gives from far away the impression of areas covered by snow. The last zone is composed of species adapted to constantly dry sites.The single species, composing the mentioned zones, all belong to plant associations which form the meadows on the carst fields, but not even one represents a species, characteristic for the single communities.The zones were compared to similar ones in Finland, described by K. Teräsvuori 1927, who explains their existance with a severe competition which takes place on sites with greatly changing environmental factors and not with the autoecological claims of the single species.In a table the content of organic matter has been shown in the single zones that decreases regularly with the receding water level and in the same way changes the life forms of the plants. In wet zones they consist of hemicryptophytes, on sites with extremely changing moisture conditions geophytes are dominating while therophytes on dryplaces. On areas never subject to regular inundations, hemicryptophytes appear again but of a more xeric type.The cover value of the vegetation is also subject to the degree of moisture during the growing season. It amounts to 100% in the wet and moist zone and deceases to 60% in the dry ones while after the first precipitations in autumn in increases to 100% all over the field due to the germinating winter annuals — in the first place to Bromus racemosus. By this time the whole field has a strictly mesophytic aspect where all traces of whatever zones has vanished with the exception of Colchicum autumnale which is than in full blossom.     

Sgk3 links growth factor signaling to maintenance of progenitor cells in the hair follicle

Tyrosine kinase growth factor receptor signaling influences proliferation, survival, and apoptosis. Hair follicles undergo cycles of proliferation and apoptotic regression, offering an excellent paradigm to study how this transition is governed. Several factors are known to affect the hair cycle, but it remains a mystery whether Akt kinases that are downstream of growth factor signaling impact this equilibrium. We now show that an Akt relative, Sgk (serum and glucocorticoid responsive kinase) 3, plays a critical role in this process. Hair follicles of mice lacking Sgk3 fail to mature normally. Proliferation is reduced, apoptosis is increased, and follicles prematurely regress. Maintenance of the pool of transiently amplifying matrix cells is impaired. Intriguingly, loss of Sgk3 resembles the gain of function of epidermal growth factor signaling. Using cultured primary keratinocytes, we find that Sgk3 functions by negatively regulating phosphatidylinositol 3 kinase signaling. Our results reveal a novel and important function for Sgk3 in controlling life and death in the hair follicle.     

A comparative study of blood culture conventional method vs. a modified lysis/centrifugation technique for the diagnosis of fungemias

The purpose of this work was to compare the efficacy of blood culture conventional method vs. a modified lysis/centrifugation technique. Out of 450 blood specimens received in one year, 100 where chosen for this comparative study: 60 from patients with AIDS, 15 from leukemic patients, ten from febrile neutropenic patients, five from patients with respiratory infections, five from diabetics and five from septicemic patients. The specimens were processed, simultaneously, according to the above mentioned methodologies with daily inspections searching for fungal growth in order to obtain the final identification of the causative agent. The number (40) of isolates recovered was the same using both methods, which included; 18 Candida albicans (45%), ten Candida spp. (25%), ten Histoplasma capsulatum (25%), and two Cryptococcus neoformans (5%). When the fungal growth time was compared by both methods, growth was more rapid when using the modified lysis/centrifugation technique than when using the conventional method. Statistical analysis revealed a significant difference (p<0.05) between them. The modified lysis/centrifugation technique showed to be more efficacious than the conventional one, and therefore the implementation of this methodology is highly recommended for the isolation of fungi from blood.     

Oct4 is required for primordial germ cell survival

Previous studies have shown that Oct4 has an essential role in maintaining pluripotency of cells of the inner cell mass (ICM) and embryonic stem cells. However, Oct4 null homozygous embryos die around the time of implantation, thus precluding further analysis of gene function during development. We have used the conditional Cre/loxP gene targeting strategy to assess Oct4 function in primordial germ cells (PGCs). Loss of Oct4 function leads to apoptosis of PGCs rather than to differentiation into a trophectodermal lineage, as has been described for Oct4-deficient ICM cells. These new results suggest a previously unknown function of Oct4 in maintaining viability of mammalian germline.