Exposure to atrazine altered postembryonic organs development, functions and growth performance of Clarias gariepinus catfish juveniles

Atrazine is a selective pre- and post-emergence herbicide for the control of weeds. Decades after being banned, atrazine remains the most abundant pesticide in water bodies. This study evaluated the toxic effects of atrazine on the post-embryonic development of African catfish (Clarias gariepinus). Catfish juveniles of 0.89 ± 0.06 cm and with an average weight of 0.01 ± 0.005 g were exposed to five different concentrations (0, 0.03, 0.3, 3.0 and 30 μgL-1) of atrazine in three replicates. The catfish juveniles mortality were significantly increased with increasing atrazine concentrations (p<0.05). Probit analysis showed 48 hours LC50 of atrazine at 0.68   μgL-1 with 100 % mortality at 30 μgL-1. Significant reduction (p<0.05) was observed in the specific growth rate (SGR) and the relative growth rate (RGR) with increasing concentration of Atrazine treatment. Histological assessment revealed disintegration of the nervous tissues, vacuolization of the epithelium of the anterior intestine, loss of gill cytoarchitecture and distortions of the intestine in all atrazine-treatment groups. Our results show that environmentally realistic concentrations (0.30 – 30.00 μgL-1) of atrazine in the aquatic environment may adversely affect the post-embryonic development and survival of African catfish

MAPT allele and haplotype frequencies in Nigerian Africans: Population distribution and association with Parkinson's disease risk and age at onset

INTRODUCTION: The association between MAPT and PD risk may be subject to ethnic variability even within populations of similar geographical origin. Data on MAPT haplotype frequencies, and its association with PD risk in black Africans are lacking. We aimed to determine the frequencies of MAPT haplotypes and their role as risk factors for PD and age at onset in Nigerians. METHODS: The haplotype and genotype frequencies of MAPT rs1052553 were analysed in 907 individuals with PD and 1022 age-matched healthy controls from the Nigeria Parkinson's Disease Research network cohort. Clinical data related to PD included age at study, age at onset (AAO), and disease duration. RESULTS: The frequency of the H1 haplotype was 98.7% in PD, and 99.1% in controls (p = 0.19). The H2 haplotype was present in - 1.3% of PD and 0.9% of controls (p = 0.24). The most frequent MAPT genotype was H1H1 (PD - 97.5%, controls - 98.2%). The H1 haplotype was not associated with PD risk after accounting for gender and AAO (Odds ratio for H1/H1 vs H1/H2 and H2/H2: 0.68 (95% CI:0.39-1.28); p = 0.23). CONCLUSIONS: Our findings support previous studies that report a low frequency of the MAPT H2 haplotype in black ancestry Africans but document its occurrence in Nigerians. The MAPT H1 haplotype was not associated with an increased risk or age at onset of PD in this cohort