Deficiency in monocarboxylate transporter 1 (MCT1) in mice delays regeneration of peripheral nerves following sciatic nerve crush.

Peripheral nerve regeneration following injury occurs spontaneously, but many of the processes require metabolic energy. The mechanism of energy supply to axons has not previously been determined. In the central nervous system, monocarboxylate transporter 1 (MCT1), expressed in oligodendroglia, is critical for supplying lactate or other energy metabolites to axons. In the current study, MCT1 is shown to localize within the peripheral nervous system to perineurial cells, dorsal root ganglion neurons, and Schwann cells by MCT1 immunofluorescence in wild-type mice and tdTomato fluorescence in MCT1 BAC reporter mice. To investigate whether MCT1 is necessary for peripheral nerve regeneration, sciatic nerves of MCT1 heterozygous null mice are crushed and peripheral nerve regeneration was quantified electrophysiologically and anatomically. Compound muscle action potential (CMAP) recovery is delayed from a median of 21days in wild-type mice to greater than 38days in MCT1 heterozygote null mice. In fact, half of the MCT1 heterozygote null mice have no recovery of CMAP at 42days, while all of the wild-type mice recovered. In addition, muscle fibers remain 40% more atrophic and neuromuscular junctions 40% more denervated at 42days post-crush in the MCT1 heterozygote null mice than wild-type mice. The delay in nerve regeneration is not only in motor axons, as the number of regenerated axons in the sural sensory nerve of MCT1 heterozygote null mice at 4weeks and tibial mixed sensory and motor nerve at 3weeks is also significantly reduced compared to wild-type mice. This delay in regeneration may be partly due to failed Schwann cell function, as there is reduced early phagocytosis of myelin debris and remyelination of axon segments. These data for the first time demonstrate that MCT1 is critical for regeneration of both sensory and motor axons in mice following sciatic nerve crush

Shrike predation on the lizard Mesalina adramitana in Qatar; a review of reported reptile and amphibian prey

We report, for the first time, evidence of predation by a shrike (Lanius sp.) on the lizard Mesalina adramitana. This is the first record of predation by shrikes on lizards in Qatar. Whilst we did not directly observe the event, the presence of shrikes in the area and the method of impalement indicate shrikes as the predator. The lizard was found freshly impaled on a palm tree (Phoenix dactylifera), at 150 cm above ground. Bird species of the genus Lanius are well-known predators of lizards, and in arid environments reptiles are likely common prey for these birds. We provide a review of literature concerning predatory events by shrikes on reptiles and amphibians. We suggest inspection of shrubs for animals impaled by shrikes can improve biodiversity inventories, complementing other commonly used methods

MACROINVERTEBRATES AS BIOINDICATORS OF POINT SOURCE POLLUTION OF SAMBUL RIVER, KENYA

Water pollution is a major global concern which calls for regular evaluation of levels of contamination of water bodies. It has been suggested that water borne infections account for over 14,000 people daily in the world. Point source pollution can be defined as contaminants from a single identifiable source. The major environmental concern by the residents around Sambul River is pollution of waters of Sambul River by effluent from Moi University sewage treatment plant (STP). Sambul River is the main source of water for both domestic and agricultural use among residents of Sambul area. This study focused on analysis of efficacy of the (sewage treatment plant) using macro-invertebrates as bio-indicators of contamination of waters of Sambul River. Purposive sampling design was used to select three sampling points; downstream of Sambul River where bio-treated sewage has mixed with waters of Sambul River, at point of effluent discharge to the river and upstream (control) of Sambul River where the river water does not mix with STP effluent. Triplicate water samples were collected at each sampling point bi-weekly and transported to the Laboratory for analysis. Sampling was done from May to August 2015. The impact of bio-treated effluent on the abundance of aquatic macro invertebrates at Sambul River was evaluated using Shannon- Wiener diversity index. The findings revealed that treated effluent had no significant effect on the aquatic macro invertebrate abundance at the receiving river, as demonstrated by Shannon-Wiener diversity index (H) and ANOVA. H-values were; upstream (H=2.504), wetland (H=2.4096) and downstream (H=2.371). High H-value indicates less number of species diversity while a lower value of H indicates a higher diversity of macro-invertebrates. Higher biodiversity is an indicator that the effluent from the STP is treated to recommended standard as required by National Environmental Management Authority (NEMA). Phosphate values for the different sampled points ranged from 0.05 ± 0.01 to 5.50 ± 0.15 mg/L. Mean phosphate level for upstream (control) was significantly lower than that of outlet (F4, 115 = 1125.73; p < 0.0001) and inlet (F4, 115 = 1125.73; p < 0.0001), but showed no significant differences from that of downstream (F4, 115 = 1125.73; p = 0.9931) and wetland (F4, 115 = 1125.73; p = 1.0000).  The findings of this research are important to demonstrate to concerned parties, including the public and the government; NEMA that the effluent from Moi University STP is treated to expectation. This will return confidence to the public on consumption of water from Sambul River

EVALUATION OF SUSTAINABLE USE OF UNDERGROUND WATER IN PERI-URBAN CENTERS’ OF ELDORET MUNICIPALITY IN KENYA

The Kenyan national water quality standard recommends that water should be safe for human consumption. If not protected, ground water can easily be contaminated with many pollutants including biological pathogenic microorganisms. Waterborne diseases can be effectively controlled through proper sanitary procedures that result in use of good quality water through proper sanitary procedures. The main purpose of the study was to compare levels of pollution of ground water between 3 peri-urban centers in Eldoret Municipality; Langas, Munyaka and Huruma, using levels of coliforms and solids in underground waters as an indicator of point source pollution as varied over the dry and wet seasons. Six test sampling points were randomly selected per peri-urban area and another two water wells located above 31 m from garbage dumpsites and pit latrines were purposely selected from the three zones and served as control samples. A total of 40 samples were collected in duplicates during the dry season (January and March 2015) and another 40 samples were collected in duplicates during the wet season (April and May 2015). Standard plate count method was used for total coliforms incubated at 35±2°C for 24 hours. The total solids were determined by evaporation technique in which the total solid material was collected and determined gravimetrically.  The mean total solids (TS), in each water well was within the permissible limits of 1.2 g/L. However, the means of the TS varied over the dry and wet seasons. Means, standards deviations, one way ANOVA and Pearson’s correlation analysis were used to analyze the relationship between variables in relation to seasons. Analysis of the collected data was done using JMP statistical software at 0.05 level of significance. Levels of coliforms in water wells were above the National Water Quality Standards of Nil/100 mL. Pearson`s correlation was used to test the relationship between the variables under study. The levels of Escherichia coli in well waters was positively influenced by the distance from the pit latrine and from the garbage dumpsites (r=-0.165, p=0.007) and (r=-0.246, p=0.024). There were no significant differences between the test and control samples, (ANOVA: F3, 39=0.2249; p<0.8487). During the dry season, total dissolved solids (TDS) levels of the test samples also showed no significant difference with the control sample (ANOVA: F3, 39=0.7601; p=0.5239).  This study concludes that topography is a key influence on proximity of water wells to pit latrines and garbage dumpsites in the study areas, thus affecting the number of coliforms in ground water. This study recommends the construction and use of standard communal water wells, review of the 30 m location distance of water wells and other water abstraction points from pollution sources and regular monitoring of ground water quality

Critical role for the lactate transporter, monocarboxylate transporter 1 (mct1), in the regeneration of peripheral nerves

Axons, and particularly regenerating axons, have high metabolic needs in order to maintain critical functions such as axon transport and membrane depolarization. Though some of the required energy likely comes form extracellular glucose and ATP generated in the soma, we and others hypothesize that some of the energy may be supplied by lactate. Unlike glucose that requires glycolytic enzymes to produce pyruvate, lactate can be converted directly to pyruvate by lactate dehydrogenase and transported into mitochondria for oxidative metabolism. In order to be transported into or out of cells, lactate requires specific monocarboxylate transporters (MCTs), the most abundant of which is MCT1. If MCT1 and lactate are critical for nerve function and regeneration, we hypothesize that MCT1 heterozygote null mice, which appear phenotypically normal despite having approximately 40% MCT1 as compared to wildtype littermate mice, would have reduced capacity for repair following nerve injury. To investigate this, adult MCT1 heterozygote null mice or wild-type mice underwent unilateral sciatic nerve crush in the proximal thigh. We found that regeneration of the sciatic nerve, as measured by recovery of compound muscle action potentials (CMAP) in the lateral plantar muscles following proximal sciatic nerve stimulation, was delayed from a median of 21 days in wildtype mice to 38.5 days in MCT1 heterozygote mice. In fact, half of the MCT1 heterozygote null mice had no recovery of CMAP by the endpoint of the study at 42 days, while all of the wild-type mice had recovered. In addition, the maximal amplitude of CMAP recovery in MCT1 heterozygote mull mice was reduced from a mean of 3 mV to 0.5 mV. As would be expected, the denervated gastrocnemius muscle of MCT1 heterozygote null mice remained atrophic at 42 days compared to wild-type mice. Our experiments show that lactate supplied through MCT1 is necessary for nerve regeneration. Experiments are underway to determine whether loss of MCT1 prevents nerve regrowth directly due to reduced energy supply to axons or indirectly by dysfunctional Schwann cells normally dependent on lactate supply through MCT1

Oligodendroglia metabolically support axons and contribute to neurodegeneration.

Oligodendroglia support axon survival and function through mechanisms independent of myelination, and their dysfunction leads to axon degeneration in several diseases. The cause of this degeneration has not been determined, but lack of energy metabolites such as glucose or lactate has been proposed. Lactate is transported exclusively by monocarboxylate transporters, and changes to these transporters alter lactate production and use. Here we show that the most abundant lactate transporter in the central nervous system, monocarboxylate transporter 1 (MCT1, also known as SLC16A1), is highly enriched within oligodendroglia and that disruption of this transporter produces axon damage and neuron loss in animal and cell culture models. In addition, this same transporter is reduced in patients with, and in mouse models of, amyotrophic lateral sclerosis, suggesting a role for oligodendroglial MCT1 in pathogenesis. The role of oligodendroglia in axon function and neuron survival has been elusive; this study defines a new fundamental mechanism by which oligodendroglia support neurons and axons