Pentose phosphate pathway and nucleic acid metabolism in red and white muscles of fish

The activities of the pentose phosphate cycle enzymes, the content of nucleic acids and the activities of acid and alkaline RNAses in the heart and red and white muscles of cartilaginous and teleost fish were determined. It was found that the rates of the dehydrogenase and transferase reactions of the pentose phosphate pathway and the nucleic acid metabolism in the red muscles and heart are much higher than those in the white muscles of the species under study.     

Differences in incorporation of nucleic acid bases and nucleosides by various Mycoplasma and Acholeplasma species.

Eight species representative of the serological diversity of the Mycoplasmatales were tested for their ability to incorporate radiolabeled nucleic acid precursors into acid-insoluble material. Cultures in complex growth medium were centrifuged and resuspended in minimal essential medium (Eagle). For Acholeplasma laidlawii, labeling occurred mainly during the first 4 h of incubation, with substrate saturation at 20 micron. All organisms tested incorporated uracil, adenine, and guanine; none incorporated cytosine. Thymine was incorporated only by bovine group 7, Mycoplasma putrefaciens, and Mycoplasma pneumoniae (strain 3546), but deoxynucleosides enhanced thymine incorporation in A. laidlawii, Mycoplasma gallisepticum, M. pneumoniae (strain AP-164), and Mycoplasma hyorhinis. Nucleoside incorporation (adenosine, guanosine, uridine, cytidine, and thymidine) was not observed for the arginine-utilizing species, Mycoplasma hominis and Mycoplasma arginini, whereas all other organisms tested incorporated nucleosides. The incorporation pattern provides additional metabolic evidence to support the biochemical and antigenic diversity of these organisms. The recognition of differences in incorporation of nucleic acid precursors is important not only to the specific labeling of these organisms, but also to the study of metabolism and transport.     

Localization of neurotensin-immunoreactive cells in the small intestine of man and various mammals

Summary Antibodies against synthetic bovine neurotensin were raised in rabbits and used to demonstrate neurotensin-immunreactive cells by immunohistochemical methods. In the jejunum and ileum of all species investigated (man, dog, monkey, cat, rabbit, sheep, rat, mouse, hamster, chinese hamster, gerbil, pig and guinea pig) cells were present in the mucosa, which reacted specifically with antineurotensin serum using the indirect immunofluorescence and peroxidase-antiperoxidase methods. In the monkey Tupaia the distribution of neurotensin-immunoreactive cells was examined by investigating serial sections through the entire gastro-entero-pancreatic (GEP) endocrine system, again showing most neurotensin-immunoreactive cells in the jejunum and ileum. The functional role of the presence of neurotensin immunoreactivity in the gut is discussed.Supported by the German Research Foundation     

Pentose phosphate pathway and nucleic acid synthesis in human funicular tissue. In vitro studies]

Umbilical cord slices were incubated with either 1- or 6-14C-glucose, the radioactivities of which were measured in CO2 evolved. The ratio, 1 CO2/6 CO2 was low, being comprised between 1 and 2. Furthermore, this incubation of cord slices with tritiated uridine or thymidine resulted in very low incorporations, especially for the latter. Therefore, both the pentose phosphate pathway and the synthesis of nucleic acid have a low activity in the cord tissue: these might be signs of senescence in this otherwise fetal organ.     

Low and high nucleic acid content bacteria play discrepant roles in response to various carbon supply modes

Planktonic bacteria can be grouped into ‘high nucleic acid content (HNA) bacteria’ and ‘low nucleic acid content (LNA) bacteria.’ Nutrient input modes vary in environments, causing nutrient availability heterogeneity. We incubated them with equal amounts of total glucose added in a continuous/pulsed mode. The pulse-treated LNA bacteria exhibited twice the cell abundance and four times the viability of the continuous-treated LNA, while HNA did not show an adaptation to pulsed treatment. In structural equation modelling, LNA bacteria had higher path coefficients than HNA, between growth and carbon-saving metabolic pathways, intracellular ATP and the inorganic energy storage polymer, polyphosphate, indicating their low-cost growth, and flexible energy storage and utilisation. After incubation, the pulse-treated LNA bacteria contained more proteins and polysaccharides (0.00064, 0.0012 ng cell⁻¹) than the continuous-treated LNA (0.00014, 0.00014 ng cell⁻¹), conferring endurance and rapid response to pulses. Compared to LNA, HNA keystone taxa had stronger correlations with the primary glucose metabolism step, glycolysis, and occupied leading positions to explain the random forest model. They are essential to introduce glucose into the element cycling of the whole community under both treatments. Our work outlines a systematic bacterial response to carbon input.     

The nucleic acid content of some edible mushrooms

Summary An improved method for the determination of nucleic acid content in edible mushrooms is described. Details of tissue homogenization and extraction are also included. In regard to the limit suggested by the Protein Advisory Group of the United Nations System, the amount of nucleic acids found in Agaricus bisporus, Pleurotus cystidiosus, Pleurotus sajor-caju and Volvariella volvacea indicates that it is safe to consume mushrooms as daily vegetable. No significant changes have been found in the nucleic acid content of V. volvacea at different degrees of maturity. V. volvacea loses around 20% of its nucleic acids upon boiling for 10 min. Possible reasons for the discrepancy between the present finding and that given in an earlier report have been discussed.     

Localization of neurotensin-immunoreactive cells in the small intestine of man and various mammals.

Antibodies against synthetic bovine neurotensin were raised in rabbits and used to demonstrate neurotensin-immunreactive cells by immunohistochemical methods. In the jejunum and ileum of all species investigated (man, dog, monkey, cat, rabbit, sheep, rat, mouse, hamster, chinese hamster, gerbil, pig and guinea pig) cells were present in the mucosa, which reacted specifically with antineurotensin serum using the indirect immunofluorescence and peroxidase-antiperoxidase methods. In the monkey Tupaia the distribution of neurotensin-immunoreactive cells was examined by investigating serial sections through the entire gastro-entero-pancreatic (GEP) endocrine system, again showing most neurotensin-immunoreactive cells in the jejunum and ileum. The functional role of the presence of neurotensin immunoreactivity in the gut is discussed.     

Substance P-immunoreactive sensory nerves in the lower respiratory tract of various mammals including man

Summary The occurrence and origin of substance P (SP)-immunoreactive (IR) nerves in the lower respiratory tract was studied by means of immunohistochemistry in the guinea-pig, rat, cat and man. In addition, biopsies from human material were also analysed by radioimmunoassay. SP-IR nerves were seen in four principal locations: 1) under or within the lining epithelium, 2) around blood vessels, 3) within the bronchial smooth muscle layer, and 4) around local tracheobronchial ganglion cells. Ligation experiments combined with capsaicin pretreatments indicated that all SP-IR nerves in the respiratory tract are sensory. The trachea seems to be mainly supplied by the vagal nerves, while intrapulmonary bronchi and blood vessels receive SP-IR nerves of both vagal and non-vagal (spinal) origin. SP-IR nerves were also found in the human bronchi with principally similar location as in the guinea-pig. The levels of SP-IR in the trachea and peripheral bronchi of man were about 3–4 pmol/g, which is in the same range as the content of corresponding tissues from the guinea-pig.In conclusion, the present experimental findings of SP-IR nerves in the lower respiratory tract in both experimental animals and man support the functional evidence for the importance of SP in the vagal and non-vagal (spinal) control of bronchial smooth muscle tone and vascular permeability.