Mechanism of Na+/H+ antiporting

Na+/H+ antiporters are central to cellular salt and pH homeostasis. The structure of Escherichia coli NhaA was recently determined, but its mechanisms of transport and pH regulation remain elusive. We performed molecular dynamics simulations of NhaA that, with existing experimental data, enabled us to propose an atomically detailed model of antiporter function. Three conserved aspartates are key to our proposed mechanism: Asp164 (D164) is the Na+-binding site, D163 controls the alternating accessibility of this binding site to the cytoplasm or periplasm, and D133 is crucial for pH regulation. Consistent with experimental stoichiometry, two protons are required to transport a single Na+ ion: D163 protonates to reveal the Na+-binding site to the periplasm, and subsequent protonation of D164 releases Na+. Additional mutagenesis experiments further validated the model.     

Practices of cattle keepers of southwest Nigeria in relation to bovine trypanosomosis

Tropical Animal Health and Production - Significant increases in human and livestock populations coupled with agricultural practices have changed the socioeconomic perspectives of livestock...     

Anthelminthic activity of acetone extract and fractions of Vernonia amygdalina against Haemonchus contortus eggs and larvae

The current control of parasitic nematodes in small ruminants relies on the use of chemical anthelminthics, but the development of resistance and the problem of drug residues require research into alternatives. Acetone extract and solvent–solvent fractions of Vernonia amygdalina Del. (Compositae) were evaluated in vitro for potential anti-parasitic effects against the eggs and larvae of Haemonchus contortus. Significant effects were obtained with the extract and fractions but differences were observed depending on the parasitic stage. The acetone extract and fractions inhibited egg hatching and inhibited larval development and killed larvae of H. contortus in a concentration-dependent manner. Best-fit 50% lethal concentration (LC₅₀) values were 957.0, 76.0, 524.0, 309.0 and 224.0 μg/ml for the acetone extract, and the butanol, hexane, chloroform and 35% water in methanol fractions, respectively, when tested against nematode eggs. Best-fit LC₅₀ values for the larval viability test were 508.2, 485.5, 569.3, 348.9 and 196.6 μg/ml for the acetone extract, and the butanol, hexane, chloroform and 35% water in methanol fractions, respectively. The butanol fraction was most active against nematode eggs while the 35% water in methanol fraction was the most active on nematode larvae, although differences in activity between fractions were not significant (p > 0.05). Overall, these in vitro results suggest that V. amygdalina, traditionally used by small farmers in Western Africa, does possess anti-parasitic properties.     

Direct effects of Moringa oleifera Lam (Moringaceae) acetone leaf extract on broiler chickens naturally infected with Eimeria species

Avian coccidiosis is one of the most important diseases of poultry and it is responsible for a large number of all broiler mortalities worldwide. The control of this disease relies mainly on the use of anticoccidial drugs. However, herbal preparations could be an alternative for the treatment against coccidiosis in chickens. The direct effects of Moringa oleifera acetone extracts on broiler chickens naturally infected with mixed Eimeria species was investigated to determine the relative efficacy of the extracts against coccidiosis in birds. The investigations were carried out in seven groups (ten chickens per group). The birds were given various doses (1.0, 2.0, 3.0, 4.0 and 5.0 g/kg body weight) of acetone extract of leaves of M. toltrazuril® (positive control) and untreated (negative control). The extract was evaluated for anticoccidial activity by means of inhibition of oocyst output in faeces, faecal score, weight gain and mortality. Haematological indices were evaluated by standard methods. The group treated with 1.0 g/ kg body weight Moringa oleifera extract produced the least inhibitory effect on oocyst shed in the faeces (96.4 %), while the groups treated with 2.0 g/kg, 3.0 g/kg, 4.0 g/kg and 5.0 g/kg body weight of the extract produced 97.4, 98.7, 99.1 and 99.8 %, respectively. Body weight gains of infected chickens treated with the extract significantly improved (p?<?0.05), and faecal scores were milder. Packed cell volume, haemoglobin concentration and red blood count of the treated birds were significantly (p?<?0.05) higher than those of the infected untreated group. Moringa oleifera leaves could find application in the treatment of avian coccidiosis in veterinary practice.     

Implication of Tillage and Soil Mineralogy on the Setting and Sieving Efficiency of FTLHV–0200 Filtra Electromagnetic Sieve Shaker

Soil sieving is an essential laboratory procedure in every soil investigation. Soil tillage and mineralogy are critical factors to soil mechanical properties. The implication of tillage and mineralogy on the settings and sieving efficiency of FTLHV–0200 filtra electromagnetic sieve shaker was studied in soils of 13 ecotopes in Eastern Cape Province. The sieve shaker had T = time, I = interval, and P = power settings. The tillage systems were conventional tillage (CT) and no tillage (NT), while the soil mineralogy was mainly quartz and kaolinite. After sieving, 72% of the aggregates were retained on the 2 mm sieve for soils under CT and 69% were retained on the 2 mm sieve for soils under NT. Soils under NT required sieving for at least 5 min to be broken into particle sizes, while soils under CT required at least 35 min. The setting T4I4P4 (time = 35 min, sieving interval = 9 s, and power level = 9) significantly (p ≤ 5%) affected the percentage of aggregates passing through the stack for all the soils irrespective of mineralogy. Quartz-dominated soils required a sieving time of 15 min to disintegrate, while kaolinite-dominated soils required a sieving time of more than 35 min. Sieving efficiency for aggregate analysis was achieved at T4I4P4 setting for soils under CT and at T2I4P3 (time = 5 min, interval = 9 s, power level = 6) setting for soils under NT. While sieving efficiency was achieved at T3I4P3 (time = 15 min, interval = 9 s, power level = 6) setting for quartz-dominated soils and at T4I4P3 (time = 35 min, interval = 9 s, power level = 6) setting for kaolinite-dominated soils.     

Suspected resistance of Trypanosoma species to diminazene aceturate on a cattle farm in Nigeria

Tropical Animal Health and Production - African animal trypanosomiasis is a major cause of mortality and economic losses for the livestock industry in Nigeria. Chemotherapy has been the most...     

Comparative insecticidal activity of cypermethrin and cypermethrin-mix applications against stomoxyine vectors

Tropical Animal Health and Production - Stomoxyines are mechanical vectors of several pathogens of livestock with severe consequences such as low productivity from constant irritation and...