The effects of adenine nucleotides and guanine nucleotides on urate synthesis de novo by isolated chick liver and kidney cells.

Isolated chick liver and kidney cells produce urate de novo from glycine, and this is partially inhibited by 1 mm-AMP and by 1 mm-GMP in liver cells but not in kidney cells. Azaserine fully inhibits this synthesis de novo, but attempts to isolate formylglycine amide ribonucleotide from azaserine-blocked cells were unsuccessful.     

Enzymic assays for amoonia and L-glutamine in tissue extracts

Fully enzymic assay methods are described for ammonia and l-glutamine in crude tissue extracts. Ammonia is estimated spectrophotometrically measuring the total amount of NADH oxidized in the presence of 2-oxoglutarate and GLDH, l-glutamine by measuring the increase in ammonia after treating extracts with glutaminase. The procedure reduces to zero the ammonia content of the assay reagents. The enzyme preparations used guarantee a high degree of specificity for both assays.     

The effects of soybean cultivar,rhizobium strain and nitrate on plant growth,nodule mass and acetylene reduction rate

Summary The effects of twelve strains ofBradyrhizobium japonicum and ten cultivars of soybean (Glycine max (L.) Merr.) on plant and nodule weights, and acetylene reduction rates (33 to 41 days) were measured in the presence and absence of 6mM nitrate. No interactions between strains and cultivars were observed. Strain by nitrate interactions were found for plant and nodule weights, and acetylene reduction rates per gram of nodule. Cultivar by nitrate interactions were found for nodule weights, acetylene reduction rates per plant and per gram of nodule. Blackhawk with all strains, and all cultivars with strains 110 and CB 1809, seemed to be able to grow as well in the absence of nitrate (utilizing nodule fixation) as in its presence. The problems of identifying strains and cultivars with especially good nitrogen fixing ability in the presence of nitrate are discussed.     

The patho-physiological basis for tests of viability in isolated perfused organs

The causes and prevention of inadequate isolated organ perfusion are discussed. The consequences of inadequate perfusion are outlined and presented as a rationale for the choice of appropriate tests of viability. The routine application of some tests is advocated and the criteria used in the assessment of the results of such test considered.     

Identified taste bud cell proliferation in the perihatching chick [published erratum appears in Chem Senses 1998 Aug;23(4):459]

Developing taste buds in the anterior mandibular floor of perihatching chicks were studied by high voltage electron microscopic autoradiography in order to identify proliferating gemmal cell types. Montaged profiles of 29 taste buds in five cases euthanized between embryonic day 21 and posthatching day 2 were analyzed after a single [3H]thymidine injection administered on embryonic day 16, 17 or 18. Results showed that dark cells comprised 55% of identified (n = 900 cells) and 62% of labeled (n = 568 cells) gemmal cells as compared with light, intermediate, basal or perigemmal bud cells. Dark cells had both a greater (P < 0.05) number of labeled cells and a greater amount of label (grains/nucleus) than the other four bud cell types, irrespective of injection day. The nuclear area (micron 2) of dark cells was not significantly larger (P > 0.05) than that of the other gemmal cell types and therefore cannot account for the greater amount for label in the dark cells. Interestingly, only dark cells showed a positive correlation (P < 0.003) between amount of label and nuclear area. Results suggest that, during the perihatching period of robust cell proliferation, dividing dark cells may give rise primarily, but not exclusively, to dark cell progeny.      

The ecological integrity of the Lower Olifants River,Limpopo province,South Africa: 2009–2015 – Part A: Olifants River main stem

The major rivers of the South African ‘Lowveld’ (low-latitude savanna) suffer numerous impacts from upstream economic activities. Whereas monitoring these rivers is required to detect biodiversity losses, record pollution events and devise mitigation strategies, current monitoring programmes are inadequate. In 2009, the South African Earth Observation Network initiated an intensive long-term research programme on the Lowveld reaches of the Olifants River. Physico-chemical parameters, aquatic macroinvertebrates and fish abundances were recorded at four Lowveld sites in the Olifants River. We review six years of this programme. The results suggest deterioration in the ecological condition of the Olifants River with no discernible improvement through protected areas. Trends could not be detected. The parameters measured, sampling methods and/or sampling frequency might be responsible for the limited trends observed, or alternatively the results simply reflect stable conditions despite on-going pollution. Real time monitoring and an expansion in the parameters monitored would add value to the monitoring programme.     

Gonadal responses of the male Syrian hamster to programmed infusions of melatonin are sensitive to signal duration and frequency but not to signal phase nor to lesions of the suprachiasmatic nuclei

This study investigated the roles of the melatonin signal and the circadian system in the induction of photoperiodic responses in the male Syrian hamster. Pinealectomized animals received programmed s.c. infusions of saline or melatonin. Saline infusions for 10 h or melatonin for 4 h during the night had no effect on the reproductive axis whereas nightly 10-h infusions of melatonin induced gonadal atrophy. Animals that received 10-h infusions of melatonin arranged such that consecutive daily signals were delivered alternately during the day and night also exhibited gonadal atrophy, whereas melatonin signals delivered every 48 h, exclusively during either the day or night, were without effect. These results demonstrate that the brain is able to read melatonin signals delivered at different phases of the circadian cycle and to use them in combination to generate an appropriate photoperiodic response. Melatonin signals lasting 10 h delivered to pinealectomized (PX) animals every 24 h induced gonadal regression. Melatonin delivered at periodicities of 20 h, 23 h, and 25 h also caused gonadal regression whereas infusions every 28 h were without effect, demonstrating that the systems responsive to melatonin are sensitive to signal frequency but do not need to receive the signal on a strictly circadian basis. These results are discussed in the context of the significance of the melatonin-free interval. PX animals that received sham or bilateral lesions of the suprachiasmatic nuclei (SCN) were infused nightly for 10 h with saline or melatonin. Melatonin infusions were equally effective at inducing gonadal atrophy and lowering serum testosterone levels in both sham- and SCN-lesioned animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunological detection of nitric oxide synthase(s) in human tissues using heterologous antibodies suggesting different isoforms.

Nitric oxide (NO) is generated from L-arginine by NO synthases. Localization of the brain enzyme has been carried out in the rat; however, despite data suggesting that NO is a major regulator of vascular and neural functions in man, there is no information about the localization of NO synthase in human tissues. Rabbit antisera to NO synthase purified from rat brain (antisera A and B) were raised, tested by Western blotting, affinity purification and enzyme immunoprecipitation assay, and used to investigate the distribution of the enzyme in a variety of human tissues by immunohistochemistry. Antisera to two synthetic peptides from cloned neural NO synthase were used to aid specificity testing. Anti-sera A and B reacted with a approximately 160-kDa protein in Western blots of human brain extracts, gave immunostaining of nerves, and precipitated enzyme activity from rat brain homogenates. Antiserum B to NO synthase also reacted with proteins of M(r) between 125 and 140 kDa in extracts of well-vascularised tissues, and immunostained vascular endothelium; the neural and vascular immunoreactivity persisted after affinity purification of antiserum B with the approximately 160 kDa protein. Endothelial staining with antiserum B was seen in respiratory tract, liver, skin and umbilicus; syncytial trophoblasts stained in the placenta. Neural staining with antiserum A and B was seen in the myenteric and submucous plexus, and in nerve fibres in smooth muscle of the gut and in many areas of the central nervous system, particularly cortex, hippocampus, hypothalamus, cerebellum, brain stem and spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of lactation on the fractional synthetic rate of protein in the liver and muscle of rats

Protein synthesis in muscle and liver were studied in rats in early and peak lactation. While the fractional synthetic rate of liver was greatly enhanced there were no significant changes in muscle. No evidence was obtained for a marked contribution of muscle protein for the demand of lactation.