Nitrogenase activity,hydrogen evolution and biomass production in different Casuarina symbioses

Nitrogenase activity, hydrogen evolution, biomass production and nodulation were studied in threeCasuarina species,C. equisetifolia Forst.,C. glauca Sieber ex Spreng andC. obesa Miq., either inoculated with a crushed nodule inoculum prepared fromC. glauca nodules or inoculated with the pure cultureHFP CcI3. Nodulation was also studied inC. cristata Miq. inoculated with the above mentionedFrankia sources. C. equisetifolia, C. glauca andC. obesa were nodulated when inoculated with both of theFrankia inoculum, whileC. cristata was very poorly nodulated. Nitrogenase activity per plant and on a nodule dry weight basis was significantly highest inC. glauca inoculated withC. glauca inoculum after 150 days from planting. This difference decreased and at 217 days from planting there was no significant difference between the symbioses, except forC. obesa inoculated withC. glauca inoculum which showed the significantly lowest nitrogenase activity. After 150 days from planting relative efficiency of nitrogenase was lowest inC. equisetifolia inoculated withHFP CcI3 and inC. equisetifolia inoculated withC. glauca inoculum. Biomass production was similar inC. glauca inoculated withC. glauca inoculum, inC. equisetifolia inoculated withHFP CcI3 and inC. obesa inoculated withHFP CcI3 at the final harvest. The data presented here show that there is a strong interrelationship between host plant and endobiont. This interrelationship is of considerable importance when introducing Casuarina symbioses for production of fuel wood.     

Angiotensin III and IV activation of the brain AT1 receptor subtype in cardiovascular function

The present investigation determined that native angiotensins II and III (ANG II and III) were equipotent as pressor agents when ICV infused in alert rats, whereas native angiotensin IV (ANG IV) was less potent. An analogue of each of these angiotensins was prepared with a hydroxyethylamine (HEA) amide bond replacement at the N-terminus, yielding additional resistance to degradation. These three angiotensin analogues, HEA-ANG II, HEA-ANG III, and HEA-ANG IV, were equivalent with respect to maximum elevation in pressor responses when ICV infused; and each evidenced significantly extended durations of effect compared with their respective native angiotensin. Comparing analogues, HEA-ANG II had a significantly longer effect compared with HEA-ANG III, and HEA-ANG IV, whereas the latter were equivalent. Pretreatment with the AT₁ receptor subtype antagonist, Losartan (DuP753), blocked subsequent pressor responses to each of these analogues, suggesting that these responses were mediated by the AT₁ receptor subtype. Pretreatment with the specific AT₄ receptor subtype antagonist, Divalinal (HED 1291), failed to influence pressor responses induced by the subsequent infusion of these analogues. These results suggest an important role for Ang III, and perhaps ANG IV, in brain angiotensin pressor responses mediated by the AT₁ receptor subtype.     

EFFECT OF CYANIDE AND ELECTRICAL STIMULATION ON PHOSPHOINOSITIDE METABOLISM IN LOBSTER NERVES

The contents of phosphoinositides, ATP, glucose and lactate in leg and claw nerves of the lobster were determined. Nerves were also analysed after cyanide poisoning, after electrical stimulation, and 1 h after removing the leg from the lobster. Cyanide poisoning decreased the levels of ATP and glucose and increased the content of lactate but did not alter the levels of phosphoinositides. Nerves left in situ for 1 h after disconnection from the central nervous system exhibited a decrease in the content of tri-phosphoinositides (TPI) of 50 per cent, without changes in ATP, glucose or lactate. The TPI change was reversed after incubation for 1 h in oxygenated seawater. Nerves labelled in vivo with ³²P were removed and stimulated at 50 Hz for 5 min. The turnover of TPI phosphorus increased on stimulation in both normal and cyanide-poisoned nerves. In contrast, turnover of ATP increased after stimulation in normal nerves but not in cyanide-treated nerves. We sought to determine whether polyphosphoinositides play a greater role in resting metabolism of the nerve or in the conducting mechanisms. Our results make more likely the involvement of TPI in permeability changes of neural membranes during excitation.     

Determination of cisplatin and cis-diammineaquachloroplatinum(II) ion by liquid chromatography using post-column derivatization with diethyldithiocarbamate

A post-column derivatization method has been developed for the determination of cisplatin and its monohydrated form. Cisplatin was isolated on a strong anion-exchange column, while a strong cation-exchange column was used for the monohydrated complex. Diethyldithiocarbamate was used as reagent and the influence of temperature, pH and methanol content on the yield of derivative was investigated. The reaction was quantitative using a packed-bed reactor with a surrounding temperature of 115°C and a mobile phase consisting of 0.125 M succinic acid—sodium hydroxide buffer pH 5.2 and methanol (2:3, v/v). The resulting complex, Pt(DDTC)₂, was monitored photometrically at 344 nm. The precision of the determination was 11.5% (C.V.) at an injected amount of 20 ng (n = 12) for monoaqua and 8.0% (C.V.) at 9 ng (n = 10) for cisplatin. The method was used to evaluate the plasma concentration of cisplatin and its monohydrated form in a patient.     

Use of nuclear morphometry characteristics to distinguish between normal and abnormal cervical glandular histologies.

This is a methodological study exploring the use of quantitative histopathology applied to the cervix to discriminate between normal and cancerous (consisting of adenocarcinoma and adenocarcinoma in situ) tissue samples. The goal is classifying tissue samples, which are populations of cells, from measurements on the cells. Our method uses one particular feature, the IODs-Index, to create a tissue level feature. The specific goal of this study is to find a threshold for the IODs-Index that is used to create the tissue level feature. The main statistical tool is Receiver Operating Characteristic (ROC) curve analysis. When applied to the data, our method achieved promising results with good estimated sensitivity and specificity for our data set. The optimal threshold for the IODs-Index was found to be 2.12.     

Validity of the nearest-neighbor approximation in the evaluation of the electrophoretic manifestations of DNA curvature

The validity of a theoretical nearest-neighbor model based on conformational energy calculations, for translating the deterministic fluctuations of DNA base sequences in superstructural elements, is tested on the electrophoretic data of 450 multimeric, duplex oligonucleotides with different sequence, periodicity, and complexity, corresponding to all the experimental data so far published. An accurate semiempirical linear relation between the gel electrophoretic retardation and the dispersion of the theoretical curvature was found which allows a prediction of electrophoretic anomalies of DNA tracts, e.g., the cyclic permutation gel assays, with great confidence. Such a pattern of agreement allows the interpretation of the gel electrophoresis retardation as due to an increase of activation energy required in straightening the DNA axis.     

Biological soil crusts in ecological restoration: emerging research and perspectives

Drylands encompass over 40% of terrestrial ecosystems and face significant anthropogenic degradation causing a loss of ecosystem integrity, services, and deterioration of social‐ecological systems. To combat this degradation, some dryland restoration efforts have focused on the use of biological soil crusts (biocrusts): complex communities of cyanobacteria, algae, lichens, bryophytes, and other organisms living in association with the top millimeters of soil. Biocrusts are common in many ecosystems and especially drylands. They perform a suite of ecosystem functions: stabilizing soil surfaces to prevent erosion, contributing carbon through photosynthesis, fixing nitrogen, and mediating the hydrological cycle in drylands. Biocrusts have emerged as a potential tool in restoration; developing methods to implement effective biocrust restoration has the potential to return many ecosystem functions and services. Although culture‐based approaches have allowed researchers to learn about the biology, physiology, and cultivation of biocrusts, transferring this knowledge to field implementation has been more challenging. A large amount of research has amassed to improve our understanding of biocrust restoration, leaving us at an opportune time to learn from one another and to join approaches for maximum efficacy. The articles in this special issue improve the state of our current knowledge in biocrust restoration, highlighting efforts to effectively restore biocrusts through a variety of different ecosystems, across scales and utilizing a variety of lab and field methods. This collective work provides a useful resource for the scientific community as well as land managers.