Test for association between dieldrin resistance and 2La inversion polymorphism in Anopheles coluzzii from Lagos, Nigeria.

The assortment of paracentric chromosomal inversion 2La is associated with the maintenance of dieldrin resistance in laboratory colonies of the malaria vector Anopheles gambiae. This association has not been tested in field populations. The aim of this study was to test the association between inversion 2La and dieldrin resistance in a field population of An. coluzzii in Nigeria. Field collected immature stages of Anopheles were raised to adults and exposed to 4% dieldrin according to WHO criteria. Knockdown was recorded at 10 min intervals for 1 hour and final mortality was recorded 24 hours post exposure. Species and inversion 2La diagnostic PCR assays were conducted on the resistant and susceptible mosquitoes. The mosquitoes were highly resistant to 4% dieldrin (17.1% knock down and 25.7% final mortality; KDT50 and KDT95 calculated as 170 and 1, 514 minutes respectively). Frequencies of 2La in both the resistant and susceptible cohorts assorted within HardyWeinberg estimates (χ2=1.32, p=0.8 for dead/susceptible mosquitoes and χ2=2.54, p=0.5 for survivors or resistant mosquitoes). However, a higher number of heterozygous mosquitoes were observed in the resistant cohort compared to the susceptible, with significant variation in karyotype frequencies (χ2=11.08, DF=2, p<0.05) and a significantly higher frequency of the 2La inversion arrangement in the resistant cohort (Pearson's χ2 = 4.58, p = 0.03.). These data are the first to associate paracentric chromosome inversion 2La and dieldrin resistance in field population of An. coluzzii. Dieldrin resistance shows a weak but significant association with 2La whose assortment is affected by positive heterosis. Variation in the assortment of 2La inversion arrangements between resistant and susceptible cohorts of this An. coluzzii population suggests that dieldrin resistance is at least partially linked to inversion 2La which may explain the persistence of dieldrin resistance in this population despite a significant absence of selection for resistance to this insecticide.

Test for association between dieldrin resistance and 2La inversion polymorphism in Anopheles coluzzii from Lagos, Nigeria

@#The assortment of paracentric chromosomal inversion 2La is associated with the maintenance of dieldrin resistance in laboratory colonies of the malaria vector Anopheles gambiae. This association has not been tested in field populations. The aim of this study was to test the association between inversion 2La and dieldrin resistance in a field population of An. coluzzii in Nigeria. Field collected immature stages of Anopheles were raised to adults and exposed to 4% dieldrin according to WHO criteria. Knockdown was recorded at 10 min intervals for 1 hour and final mortality was recorded 24 hours post exposure. Species and inversion 2La diagnostic PCR assays were conducted on the resistant and susceptible mosquitoes. The mosquitoes were highly resistant to 4% dieldrin (17.1% knock down and 25.7% final mortality; KDT50 and KDT95 calculated as 170 and 1, 514 minutes respectively). Frequencies of 2La in both the resistant and susceptible cohorts assorted within Hardy- Weinberg estimates (χ2=1.32, p=0.8 for dead/susceptible mosquitoes and χ2=2.54, p=0.5 for survivors or resistant mosquitoes). However, a higher number of heterozygous mosquitoes were observed in the resistant cohort compared to the susceptible, with significant variation in karyotype frequencies (χ2=11.08, DF=2, p<0.05) and a significantly higher frequency of the 2La inversion arrangement in the resistant cohort (Pearson’s χ2 = 4.58, p = 0.03.). These data are the first to associate paracentric chromosome inversion 2La and dieldrin resistance in field population of An. coluzzii. Dieldrin resistance shows a weak but significant association with 2La whose assortment is affected by positive heterosis. Variation in the assortment of 2La inversion arrangements between resistant and susceptible cohorts of this An. coluzzii population suggests that dieldrin resistance is at least partially linked to inversion 2La which may explain the persistence of dieldrin resistance in this population despite a significant absence of selection for resistance to this insecticide.

Electrocardiographic and Blood Pressure Measurements in Captive African Lions (Panthera leo) Immobilized with Xylazine-Ketamine Combination.

Electrocardiographic and blood pressure measurements are extremely valuable diagnostic tools in the evaluationof the cardiovascular system of living animals. In this study, 6-lead electrocardiograms were recorded from five male captiveAfrican lions (Panthera leo). Also, blood pressure measurements were recorded and compared from three different sites;fore limb, hind limb and the tail, were recorded. Immobilization was done with a combination of Ketamine Hydrochloride(10mg/kg) and Xylazine (3mg/kg). Measurements were recorded as mean ± standard deviation. ECG readings were analysedusing descriptive statistics while blood pressure readings were compared using ANOVA at a 5% level of significance. Heartrate was 66±11.6 beats per minute. The heart rhythm was sinus in all the animals. Mean Electrical Axis (MEA) was between+810 and +930 degrees (Mean +89±5). Three animals had their MEA between +810 and +890 while two had MEA between+910 and +930. Fore limb measurements for Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DAP) and MeanArterial Pressure (MAP) were 177.6±6.8 mmHg, 157.2±5.9 mmHg and 168.6±5.2 mmHg respectively. Hind limbmeasurements for the SBP, DBP and MAP were 135.4±9.5 mmHg, 120.6±5.9 mmHg and 123.0±6.8 mmHg respectivelywhile the tail measurements for the SBP, DBP and MAP were 149.6±8.3 mmHg, 132.8±5.9 mmHg and 137.2±5.8 mmHgrespectively. There was weak correlation between forelimb vs hindlimb and forelimb vs tail comparisons of SBP, DBP andMAP. However, a strong positive correlation was found between hindlimb and tail comparisons of those parameters. Resultsfrom this study should serve as a guide in the cardiovascular monitoring of captive African Lions immobilized with axylazine-ketamine combination.

Industrial effluent induced chromosomal aberration in catfish from Ogun River, Lagos, Nigeria.

The aim of the study is to evaluate the cytotoxic effect of effluents at inducing chromosomal aberrations, using this as a biomarker tool in wild Clarias pachynema for assessing and monitoring pollution of the aquatic environment. A total of 60 live fish (30 each downstream and upstream) were obtained and subjected to chromosomal analysis. Chromosomal aberration in the fish samples from the downstream sector was recorded at a rate of 30%, while there were no aberrations in the samples collected upstream the effluent discharge point. Water sample analysis revealed a high concentration of Ammonia and Nitrates above permissible standards of Federal Environmental Protection Agency (FEPA) guidelines. Heavy metal analysis also revealed the presence of Cr (0.05), Cu (0.01), Pb (0.05), Zn (5.0) and Fe (0.3) above permissible standards from the downstream section of the river. This study shows clearly that the ever increasing discharge of effluents from the industry could increase chromosomal damage in the aquatic components.

Gastrointestinal Helminth Parasites of the fish Synodontis clarias (Siluriformes: Mochokidae) from Lekki lagoon, Lagos, Nigeria

A total of 362 specimens of the fish Synodontis clarias were randomly selected and subjected to parasitological examination for helminth parasites. They were collected over a period of one year from Lekki lagoon, Lagos, Nigeria. The prevalence of gastrointestinal infection was 38.7%. The helminth worms found include two cestodes, Proteocephalus spp., Wenyonia acuminata, and a nematode species, Raphidascaroides. Male specimens (196) presented a higher rate of infection (37.8%) than female specimens (166) which showed a rate of 23.5%. The overall worm burden was high (678) and it was independent of fish sex and fish size. Rev. Biol. Trop. 56 (4): 2021-2026. Epub 2008 December 12.

Se muestrearon aleatoriamente un total de 362 especímenes de Synodontis clarias, los cuales fueron sometidos a análisis parasitológicos. Los especimenes fueron recolectados durante un período de un año del lago Lekki, Nigeria. La existencia de infecciones gastrointestinales fue de un 38.7% del total de especímenes examinados, lo cual representó 114 especímenes infectados con parásitos helmintos. Los gusanos helmintos encontrados incluyen dos céstodos, especies de Proteocephalus, Wenyonia acuminata, y una especie de nemátodo, Raphidascaroides sp. Los especímenes machos (196) presentaron una tasa de infección mayor (37.8%) que la presentada por hembras (23.5%). La cantidad total de gusanos parásitos fue alta (678) y fue independiente del sexo y la talla del pez.

Gastrointestinal helminth parasites of the fish Synodontis clarias (Siluriformes: Mochokidae) from Lekki lagoon, Lagos, Nigeria.

A total of 362 specimens of the fish Synodontis clarias were randomly selected and subjected to parasitological examination for helminth parasites. They were collected over a period of one year from Lekki lagoon, Lagos, Nigeria. The prevalence of gastrointestinal infection was 38.7%. The helminth worms found include two cestodes, Proteocephalus spp., Wenyonia acuminata, and a nematode species, Raphidascaroides. Male specimens (196) presented a higher rate of infection (37.8%) than female specimens (166) which showed a rate of 23.5%. The overall worm burden was high (678) and it was independent of fish sex and fish size.