Simulating the hydrology of small coastal ecosystems in conditions of limited data

Hydrology / Simulation / Ecosystems / Lagoons / Estuaries / Irrigation effects / Sri Lanka / South Africa / Karagan Lagoon / Bundala Lagoon

Re-engineering a neuroprotective, clinical drug as a procognitive agent with high in vivo potency and with GABAA potentiating activity for use in dementia

Background Synaptic dysfunction is a key event in pathogenesis of neurodegenerative diseases such as Alzheimer’s disease (AD) where synapse loss pathologically correlates with cognitive decline and dementia. Although evidence suggests that aberrant protein production and aggregation are the causative factors in familial subsets of such diseases, drugs singularly targeting these hallmark proteins, such as amyloid-β, have failed in late stage clinical trials. Therefore, to provide a successful disease-modifying compound and address synaptic dysfunction and memory loss in AD and mixed pathology dementia, we repurposed a clinically proven drug, CMZ, with neuroprotective and anti-inflammatory properties via addition of nitric oxide (NO) and cGMP signaling property. Results The novel compound, NMZ, was shown to retain the GABAA potentiating actions of CMZ in vitro and sedative activity in vivo. Importantly, NMZ restored LTP in hippocampal slices from AD transgenic mice, whereas CMZ was without effect. NMZ reversed amnestic blockade of acetylcholine receptors by scopolamine as well as NMDA receptor blockade by a benzodiazepine and a NO synthase inhibitor in the step-through passive avoidance (STPA) test of learning and working memory. A PK/PD relationship was developed based on STPA analysis coupled with pharmacokinetic measures of drug levels in the brain: at 1 nM concentration in brain and plasma, NMZ was able to restore memory consolidation in mice. Conclusion Our findings show that NMZ embodies a promising pharmacological approach targeting synaptic dysfunction and opens new avenues for neuroprotective intervention strategies in mixed pathology AD, neurodegeneration, and dementia

Towards 25 Billionths of a Liter

Although fruit fly (Drosophila melanogaster) is an extensively used animal model in biology, attaining organism-level samples from this tiny insect for chemical characterization has been a challenge. Previously I developed a sampling method that enabled chemical analyses of individual fruit-fly larval blood known as hemolymph (Piyankarage et al. Anal. Chem. 2008). Illustrated here is an even challenging adult fruit-fly hemolymph sampling technique. The magnified image in the centre shows an adult male fruit fly and the tip of the sampling probe (50-µm inner diameter) that enabled collection of 25 billionths of a liter (nano liter/nL) of fly-hemolymph. The image on top left comparatively illustrates the size of adult flies, larva, and sampling probe tips by gluing them on a dime (note the letters E and DI of the ONE DIME coin). On the bottom left is the sampling probe tip with Tygon tubing, which connects the tip to a vacuum pump to pull hemolymph. An image of diluted fluorescent-tagged fly-hemolymph sample is shown on bottom right while a resultant electropherogram (a chart) from the sample analyses is shown as the border. All the images were captured through a microscope due to the small size of the objects

Nanoliter sampling and analysis of Drosophila melanogaster hemolymph.

Nanoliter sampling and analysis of Drosophila melanogaster hemolymph

Estimation of nitrogen and phosporus fluxes to Embilikala and Malala Lagoons in Southern Sri Lanka

In Ratnasiri, J. (Ed.). Assessment of material fluxes to the coastal zone in South Asia and their impacts: Proceedings of the APN/START/LOICZ South Asia Regional Workshop, Negombo, Sri Lanka, 8-11 December 2002. Colombo, Sri Lanka: Sri Lanka National Committee of IGB

Hemolymph amino acid analysis of individual Drosophila larvae

International audienceOne of the most widely used transgenic animal models in biology is Drosophila melanogaster, the fruit fly. Chemical information from this exceedingly small organism is usually accomplished by studying populations to attain sample volumes suitable for standard analysis methods. This paper describes a direct sampling technique capable of obtaining 50-300 nL of hemolymph from individual Drosophila larvae. Hemolymph sampling performed under mineral oil and in air at 30 s intervals up to 120 s after piercing larvae revealed that the effect of evaporation on amino acid concentrations is insignificant when the sample was collected within 60 s. Qualitative and quantitative amino acid analyses of obtained hemolymph were carried out in two optimized buffer conditions by capillary electrophoresis with laser-induced fluorescence detection after derivatizing with fluorescamine. Thirteen amino acids were identified from individual hemolymph samples of both wild-type (WT) control and the genderblind (gb) mutant larvae. The levels of glutamine, glutamate, and taurine in the gb hemolymph were significantly lower at 35%, 38%, and 57% of WT levels, respectively. The developed technique that samples only the hemolymph fluid is efficient and enables accurate organism-level chemical information while minimizing errors associated with possible sample contaminations, estimations, and effects of evaporation compared to the traditional hemolymph-sampling techniques

Nanoliter Hemolymph Sampling and Analysis of Individual Adult <i>Drosophila melanogaster</i>

The fruit fly (<i>Drosophila melanogaster</i>) is an extensively used and powerful, genetic model organism. However, chemical studies using individual flies have been limited by the animal’s small size. Introduced here is a method to sample nanoliter hemolymph volumes from individual adult fruit-flies for chemical analysis. The technique results in an ability to distinguish hemolymph chemical variations with developmental stage, fly sex, and sampling conditions. Also presented is the means for two-point monitoring of hemolymph composition for individual flies