Preparation of soybean seed samples for FT-IR microspectroscopy

Typical preparation of seed samples for infrared (IR) microspectroscopy involves imbibition of the seed for varying time periods followed by cryosectioning. Imbibition, however, may initiate germination even at 4° C with associated changes in the chemistry of the sample. We have found that it is possible to section seeds that are sufficiently hard, such as soybeans, on a standard laboratory microtome without imbibition. The use of dry sectioning of unimbibed seeds is reported here, as well as a comparison of different mounting media and modes of analysis. Glycerol, Tissue-Tek, and ethanol were used as mounting media, and the quality of the resulting spectra was assessed. Ethanol was the preferred mountant, because it dried quickly with no residue and thus did not interfere with the spectrum of interest. Analysis in transmission mode using barium fluoride windows to hold the samples was compared with transmission-reflection analysis with sections mounted on special infrared-reflecting slides. The two modes of analysis performed well in different regions of the spectrum. The mode of analysis (transmission vs. transmission-reflection) should be based on the components of greatest interest in the sample.     

Potentiation of arachidonic acid release by phorbol myristate acetate in platelets is not due to inhibition of arachidonic acid uptake or incorporation into phospholipids

Activators of protein kinase C, such as tumor-promoting phorbol esters (e.g., phorbol myristate acetate), mezerein, (-)-indolactam V and 1-oleoyl 2-acetoyl glycerol, potentiate arachidonic acid release caused by elevation of intracellular Ca2+ with ionophores. This action of protein kinase C-activators required protein phosphorylation, and was attributed to enhanced hydrolysis of phospholipids by phospholipase A2 (Halenda, et al. (1989) Biochemistry 28, 7356-7363). Recently Fuse et al. ((1989) J. Biol. Chem 264, 3890-3895) reported that the apparent enhanced release of arachidonate was actually due to inhibition of the processes of re-uptake and re-esterification of released arachidonic acid. They attributed this to loss of arachidonyl-CoA synthetase and arachidonyl-CoA lysophosphatide acyltransferase activities, which were measured in membranes obtained from phorbol myristate acetate-treated platelets. In this paper, we show that phorbol myristate acetate, at concentrations that strongly potentiate arachidonic acid release, does not inhibit either arachidonic acid uptake into platelets or its incorporation into specific phospholipids. Furthermore, the fatty acid 8,11,14-eicosatrienoic acid, a competitive substrate for arachidonyl-CoA synthetase, totally blocks arachidonic acid uptake into platelets, but, unlike phorbol myristate acetate, does not potentiate arachidonic acid release by Ca2+ ionophores. We conclude that the action of phorbol myristate acetate is to promote the process of arachidonic acid release by phospholipase A2.     

Ethylene Biosynthesis and Accumulation under Drained and Submerged Conditions (A Comparative Study of Two Rumex Species)

A model is presented of the regulation of ethylene biosynthesis in relation to submergence and flooding resistance. It is based on time-course measurements of ethylene production, ethylene accumulation, and concentrations of free and conjugated 1-aminocyclo-propane-1-carboxylic acid (ACC) in submerged and drained flooding-resistant Rumex palustris Sm. and flooding-sensitive Rumex acetosella L. plants. From these data, in vivo reaction rates of the final steps in the ethylene biosynthetic pathway were calculated. According to our model, submergence stimulates ACC formation and inhibits conversion of ACC to ethylene in both Rumex species, and as a result, ACC accumulates. This may explain the stimulated ACC conjugation observed in submerged plants. Although submergence inhibited ethylene production, physical entrapment increased endogenous ethylene concentrations in both flooding-resistant R. palustris and flooding-sensitive R. acetosella plants. However, R. palustris plants controlled their internal ethylene levels in the long term by a negative regulation of ACC synthase induced by ethylene. In flooding-sensitive R. acetosella plants, absence of negative regulation increased internal ethylene levels to more than 20 [mu]L L-1 after 6 d of submergence. This may accelerate the process of senescence and contribute to their low level of flooding resistance.     

THERAPEUTIC STRATEGIES FOR THE INHIBITION OF INDUCIBLE NITRIC OXIDE SYNTHASE—POTENTIAL FOR A NOVEL CLASS OF ANTI-INFLAMMATORY AGENTS

In recent years, NO, a gas previously considered a potentially toxic chemical, has become established as a diffusible universal messenger mediating cell—cell communication throughout the body. In mammals, NO is a recognized mediator of blood vessel relaxation that helps to maintain blood pressure. In the central nervous system NO acts as a non-conventional neurotransmitter and participates in the establishment of long-term plasticity required for memory formation. In addition, NO is responsible for some parts of the host response to sepsis and inflammation and contributes to certain disease states. A number of strategies have emerged with regard to a pharmacological control of pathological NO overproductions. This review will discuss these novel therapeutic approaches that may provide new means for clinical medicine.     

Hormone sensitivity and plant adaptations to flooding

Plant hormones play a key role as mediators between environmental signals and adaptive plant responses. Auxin, ethylene and gibberellins are involved in the initiation of adaptive plant responses such as the development of adventitious roots and stimulated shoot elongation upon flooded conditions. These adaptive plastic responses in plants are frequently linked to changes in the concentrations of the hormones involved, but only rarely to shifts in sensitivity. Examples from ecophysiological research performed with species from the genusRumex demonstrate the importance of the hormone sensitivity concept in plant adaptations to flooding: (a)Rumex species can be grouped into three response categories according to the ethylene sensitivity of the youngest petioles: positive, negative and indifferent; (b) Sub-ambient oxygen concentrations sensitize petioles of wetlandRumex species to ethylene; (c) Enhanced ethylene levels sensitize petioles of wetlandRumex species to gibberellin; (d) Auxin is the primary plant hormone responsible for the initiation of adventitious roots in wetlandRumex species. However, a factor related to waterlogging, possibly ethylene, is required to sensitize the root-shoot junction to endogenous auxin.     

Demographics and parasites of African buffalo (Syncerus caffer Sparrman, 1779) in Ruaha National Park,Tanzania

The number of African buffaloes (Syncerus caffer Sparrman, 1779) inhabiting Ruaha National Park, Tanzania, is thought to be declining, but little data exist to determine whether the population is actually in decline. As an initial phase of collecting population data, we conducted demographic surveys, faecal egg counts and gastrointestinal parasite identification in Ruaha's buffalo herds in September 2011 and 2013. Most herds encountered in the two surveys appeared to be in good health, but with fewer calves in 2013 compared with 2011. The herd‐level body condition score was positively associated with the number of calves per 100 cows after adjusting for year, and the lower number of offspring in 2013 could possibly be associated with a below average rainfall in the 2012–2013 rainy season. Mean herd‐level egg counts ranged from 83 to 140 and from 28 to 113 eggs per g faeces in 2011 and 2013, respectively. Haemonchus, Nematodirus, Cooperia and Oesophagostomum spp., as well as coccidian oocysts, were detected in the population. Monitoring herd demographics and baseline health parameters over time will provide insight into population performance, increase the understanding of population stressors and contribute to buffalo conservation within Ruaha National Park and other protected areas of Africa.     

Effects of L-cysteine on lead acetate induced neurotoxicity in albino mice

Lead is a toxic heavy metal that adversely affects nervous tissues; it often occurs as an environmental pollutant. We investigated histological changes in the cerebral cortex, hippocampus and cerebellum of adult albino mice following exposure to lead acetate. We also studied the possible ameliorative effect of the chelating agent, L-cysteine, on lead-induced neurotoxicity. We divided albino mice into six groups: 1) vehicle-only control, 2) L-cysteine control, 3 and 4) treated for 7 days with 20 and 40 mg/kg lead acetate, respectively, and 5 and 6) treated for 7 days with 20 and 40 mg/kg lead acetate, respectively, followed by 50 mg/kg L-cysteine for 7 days. Lead acetate administration caused disorganization of cell layers, neuronal loss and degeneration, and neuropil vacuolization. Brain sections from lead-intoxicated mice treated with L-cysteine showed fewer pathological changes; the neuropil showed less vacuolization and the neurons appeared less damaged. L-cysteine at the dose we used only marginally alleviated lead-induced toxicity.