Isolation and characterization of a new thermophilic and autotrophic methane producing bacterium:Methanobacterium thermoaggregans spec. nov.

Methanobacterium thermoaggregans is a new thermophilic autotrophic rod-shaped methane producing bacterium. The organism likes to form aggregates during growth and utilizes only H₂ and CO₂ as substrates. Growth optimum is at 65°C with a doubling time of 3.5 h. Optimal growth occurs at pH-values between 7 and 7.5. The addition of yeast extract to the mineral salt medium stimulates growth. The DNA base composition is 42 mol% G+C. The organism was isolated from mud taken from a cattle pasture. Because of its optimal growth temperature and its tendency to form aggregates the nameMethanobacterium thermoaggregans is suggested.Abbreviations G+C Guanine+cytosine     

Synthesis and phosphorylation of cytoskeleton components in foetal,regenerating and adult normal rat hepatocytes during culture

Summary Detergent insoluble material (DIM) was prepared by gentle treatment with detergent from foetal, regenerating and adult normal rat hepatocytes cultured for various times. It retained to some degree the morphology of the cells. After incubation of intact cells with ³⁵S-methionine, most of the labelled DIM proteins were found to be components of the cytoskeleton. They included several cytokeratins, vimentin and actin. The synthesis rate varied with the age of animals and culture conditions. The high synthetic rate of vimentin in foetal and regenerating hepatocytes could be associated with cell proliferation. No correlation was found between cytokeratin synthesis and hepatocyte growth. Most of the cytoskeleton proteins could be phosphorylated in intact cells and in DIM from cultured hepatocytes. However the degree of phosphorylation of these proteins was not related to their synthetic rate. The decreased phosphorylation level in cultured adult rat hepatocytes could be related to the rapid loss of specific functions.     

Floristic groups and plant communities of southeastern Santa Fe,Argentina

This paper is a survey of the vegetation of the southeastern departments in the Province of Santa Fe (Argentina). The vegetation was analyzed following Braun-Blanquet's approach modified by Mueller-Dombois & Ellenberg (1974). The most relevant species of the region were placed in 25 groups according to their requirements or general behaviour. Most of the communities are herbaceous, and apart from the woody and some other miscellaneous ones they were grouped into three ecologically and floristically defined sets. The first set, the Stipa grasslands and related communities, which are characterized by the more or less abundant presence of Stipa hyalina, Stipa neesiana and Stipa papposa, comprises five different communities. The second, the halophilous communities, comprises five communities, the two Spartina ssp. grasslands, the halophilous prairies of Distichlis spicata, the short sedge Scirpus americanus communities and the ‘pela-dales’. The third, the hygrophilous communities, comprises nine communities which are not so well defined as the ones in the other sets. Besides, two further communities have been included, the Paspalum quadrifarium and the Melica macra tall grasslands.     

Production and release of peptidoglycan and wall teichoic acid polymers in pneumococci treated with beta-lactam antibiotics

Autolysin-defective pneumococci treated with inhibitory concentrations of penicillin and other beta-lactam antibiotics continued to produce non-cross-linked peptidoglycan and cell wall teichoic acid polymers, the majority of which were released into the surrounding medium. The released cell wall polymers were those synthesized by the pneumococci after the addition of the antibiotics. The peptidoglycan and wall teichoic acid chains released were not linked to one another; they could be separated by affinity chromatography on an agarose-linked phosphorylcholine-specific myeloma protein column. Omission of choline, a nutritional requirement and component of the pneumococcal teichoic acid, from the medium inhibited both teichoic acid and peptidoglycan synthesis and release. These observations are discussed in terms of plausible mechanisms for the coordination between the biosynthesis of peptidoglycan and cell wall teichoic acids.     

Investigations on karyotype evolution in patients with chronic myeloid leukemia (CML)

In an attempt to relate karyotype evolution to clinical and hematological data serial chromosomal analyses were performed in 31 patients with chronic myeloid leukemia (CML), both in chronic and acute phases. Our results in Philadelphia chromosome (Ph1)-positive CML are in line with karyotype profiles described in the literature. In addition, we report on chromosomal findings in 4 cases of Ph1-negative disease, one presenting with an iso17q chromosome in the positive CML. The same chromosomal abnormality was observed in a small population of Ph1-negative cells present in one of two patients with mixed Ph1-positive/Ph1-negative CML. The first case of a female patient with the loss of a sex chromosome in Ph1-positive cells is reported. Two patients with unusually long and mild chronic phases despite the presence of trisomy 8 in their karyotypes are described. Our findings suggest that the order of appearance of additional chromosomal changes of CML is of prognostic significance for the progression and the clinical picture of the disease.     

Dietary docosahexaenoic acid is retroconverted in man to eicosapentaenoic acid, which can be quickly transformed to prostaglandin I3

In a 24 h kinetic study docosahexaenoic acid (DCHA, C22:6n-3) or eicosapentaenoic acid (EPA, C20:5n-3) were given in a single dose to healthy male volunteers. PGI₃-M, the main urinary metabolite of prostaglandin I₃ was below the detection limit in the control periods, but was excreted already in the first 4 h after ingestion of DCHA or EPA and decreased thereafter. Excretion of PGI₂-M did not change significantly. In a second dietary trial DCHA and EPA were given cross-over to 7 healthy male volunteers for 6 days. PGI₃-M was formed after DCHA and EPA in amounts of 35 and 20 % of PGI₂-M and showed a considerable interindividual variation. The structure of PGI₃-M was verified by independant biochemical synthesis. Our data indicate that dietary DCHA is retroconverted to EPA in man, which is quickly transformed - like dietary EPA itself - to prostaglandin I₃. DCHA may therefore serve as a precursor fatty acid for EPA and its cyclooxygenated and lipoxygenated products.     

Protein-chemical identification of the major cleavage sites of the Ca2+ proteinase on murine vimentin, the mesenchymal intermediate filament protein

Neutral thiol proteinases (calpains), activated by calcium are involved in the intracellular turnover of intermediate filaments but the precise position of the cleavage points has remained unknown. Here we identify by direct sequence analysis the major cleavage sites found when murine vimentin is digested by limited proteolysis in vitro with calpain purified from porcine kidney. Contrary to some previous suggestions, no absolute sequence specifity could be detected although 10 specific sites have been identified. This result is in line with the cDNA derived amino-acid sequence of a calpain, which pointed to a similarity of the catalytic site with the active sites in papain, cathepsin and actinidin. However, all major cleavage sites are located within regions of the vimentin molecule, which in current models of intermediate filament structure are thought to be non-helical: the amino-terminal headpiece, the carboxy-terminal tailpiece and the spacer separating the two major coiled-coil domains. The sequence information about the cleavage sites was extended to provide the amino-terminal 119 residues of murine vimentin.     

In vitro modification of Candida albicans invasiveness

Candida albicans produces germ-tubes (GT) when it is incubated in animal or human serum. This dimorphism is responsible for its invasive ability.The purpose of the present paper is (1) to evaluate the ability of rat peritoneal macrophages to inhibit GT production of ingested Candida albicans, obtained from immunized rats and then activated in vitro with Candida-induced lymphokines; (2) to determinate any possible alteration of phagocytic and candidacidal activities.The phagocytes were obtained from rats immunized with viable C. albicans. Some of them were exposed to Candida-induced lymphokines in order to activate the macrophages in vitro. The monolayers of activated, immune and normal macrophages were infected with a C. albicans suspension during 4 hr.Activated macrophages presented not only the highest phagocytic and candidacidal activities but a noticeable inhibition of GT formation and incremented candidacidal activity.