Anthropic impacts on Sub-Saharan urban water resources through their pharmaceutical contamination (Yaoundé, Center Region, Cameroon)

Sub-Saharan urban centers have to tackle high population growth, lack of sanitation infrastructures and the need for good quality water resources. To characterize the impacts of anthropization on the water resources of the capital of Cameroon (Yaoundé), a multi-disciplinary approach was used in ten sub-watersheds (peri-urban and urban) of the Méfou watershed. Pharmaceutical residues were used as tracers of surface and groundwater contamination caused by the release of domestic wastewater from pit latrines and landfills. A water use survey was conducted in the vicinity of the sampling sites to better assess water use, treatment and management. Available land use and hydro-geomorphological data completed characterization of the sub-watersheds. The combined data showed that natural features (elevation, slope, and hydrography) and human activities (land use) favor rainfall-runoff events and hence surface water contamination. Pharmaceutical monitoring revealed contamination of both surface and groundwater especially in the urban sub-watersheds. Analgesics/anti-inflammatory drugs and anti-epileptic carbamazepine were the most frequently found compounds (in up to 91% of water samples) with concentrations of acetaminophen reaching 5660 ng/L. In urban sub-watersheds, 50% of the groundwater sites used for drinking water were contaminated by diclofenac (476-518 ng/L), carbamazepine (263-335 ng/L), ibuprofen (141-276 ng/L), sulfamethoxazole (<2-1285 ng/L) and acetaminophen (110-111 ng/L), emphasizing the need for a deeper understanding of the interactions between surface and groundwater. The use of groundwater as drinking water by 68% of the total population surveyed raises concerns about population exposure and potential health risks. This case study highlights the need for strategies to limit contamination of the water resource given the predicted future expansion of Sub-Saharan urban centers.

Timed artificial insemination in blocks: A new alternative to improve fertility in lactating beef cows

The aim of this study was to evaluate whether changing the interval from CIDR removal to timed artificial insemination (TAI) according to the diameter of the preovulatory follicle (POF) would improve pregnancy per AI in cows. In Study 1, a retrospective analysis of TAI experiments (n=96 cows) was performed to characterize the time of ovulation according to the diameter of the dominant follicle. It was observed that cows with a larger POF had ovulations earlier than cows with smaller POF, according to the equation: y=0.72x(2)-26.74x+264.54 (R(2)=0.63; P<0.001). In Study 2, lactating Nelore cows (n=412) were subjected to an EB-CIDR based TAI protocol. On the morning of Day 10 (time of TAI), cows were randomized into Control (n=209) and Block (n=203) groups; (1) Cows in the Control Group were TAI 48 h after CIDR removal (08:00 am on Day 10), and; (2) Cows in the block group were inseminated once at one of the following time points, according to the diameter of the POF on Day 10: B0 (POF≥15mm, TAI 0 h after convetional TAI), B1 (POF 13-14.9 mm, TAI 6h later), B2 (POF 10.1-12.9 mm, TAI 24h later) and B3 (POF≤10mm, TAI 30 h later). The cows of the Block Group had greater pregnancy rates per AI than the Control Group (129/203, 63.5% when compared with 102/209, 48.8%, respectively; P<0.01). In conclusion, results of the present study demonstrate that adjusting the timing of TAI according to the diameter of the POF can be an effective practice for improving fertility of cows in TAI protocols.

Respiratory system of Gluconacetobacter diazotrophicus PAL5 Evidence for a cyanide-sensitive cytochrome bb and cyanide-resistant cytochrome ba quinol oxidases

In highly aerobic environments, Gluconacetobacter diazotrophicus uses a respiratory protection mechanism to preserve nitrogenase activity from deleterious oxygen. Here, the respiratory system was examined in order to ascertain the nature of the respiratory components, mainly of the cyanide sensitive and resistant pathways. The membranes of G. diazotrophicus contain Q(10), Q(9) and PQQ in a 13:1:6.6 molar ratios. UV(360 nm) photoinactivation indicated that ubiquinone is the electron acceptor for the dehydrogenases of the outer and inner faces of the membrane. Strong inhibition by rotenone and capsaicin and resistance to flavone indicated that NADH-quinone oxidoreductase is a NDH-1 type enzyme. KCN-titration revealed the presence of at least two terminal oxidases that were highly sensitive and resistant to the inhibitor. Tetrachorohydroquinol was preferentially oxidized by the KCN-sensitive oxidase. Neither the quinoprotein alcohol dehydrogenase nor its associated cytochromes c were instrumental components of the cyanide resistant pathway. CO-difference spectrum and photodissociation of heme-CO compounds suggested the presence of cytochromes b-CO and a(1)-CO adducts. Air-oxidation of cytochrome b (432 nm) was arrested by concentrations of KCN lower than 25 microM while cytochrome a(1) (442 nm) was not affected. A KCN-sensitive (I(50)=5 microM) cytochrome bb and a KCN-resistant (I(50)=450 microM) cytochrome ba quinol oxidases were separated by ion exchange chromatography.