Alabi, O. O. | bioRxiv Science

bioRxiv2021

Multivariate Characterization of Morpho-biometric Traits of Indigenous Helmeted Guinea Fowl (Numida meleagris) in Nigeria

This study was embarked upon to characterise phenotypically helmeted guinea fowls in three agro-ecologies in Nigeria using multivariate approach. Eighteen biometric characters, four morphological indices and eleven qualitative (phaneroptic) traits were investigated in a total of 569 adult birds (158 males and 411 females). Descriptive statistics, non-parametric Kruskal-Wallis H test followed by the Mann-Whitney U test for post hoc, Multiple Correspondence Analysis (MCA), General Linear Model, Canonical Discriminant Analysis, Categorical Principal Component Analysis and Decision Trees were employed to discern the effects of agro-ecological zone and sex on the morphostructural parameters. Agro-ecology had significant effect (P<0.05; P <0.01) on all the colour traits. In general, the most frequently observed colour phenotype of guinea fowl had pearl plumage colour (54.0%), pale red skin colour (94.2%), black shank colour (68.7%), brown eye colour (49.7%), white earlobe colour (54.8%) and brown helmet colour (72.6%). The frequencies of helmet shape and wattle size were significantly influenced (P <0.01) by agro-ecology and sex. Overall, birds from the Southern Guinea Savanna zone had significantly higher values (P <0.05) for most biometric traits compared to their Sudano-Sahelian and Tropical Rainforest counterparts. They were also more compact (120.83{+/-}1.61 vs. 113.96{+/-}0.97 vs. 111.33{+/-}1.19) and had lesser condition index (8.542{+/-}0.17 vs. 9.92{+/-}0.10 vs. 9.61{+/-}0.13) than their counterparts in the two other zones. The interaction between agro-ecology and sex had significant effect (P <0.05) on some quantitative variables. The MCA and discriminant analysis revealed considerable intermingling of the phaneroptic, biometric traits and body indices especially between the Sudano-Sahelian and Tropical Rainforest birds. Inspite of the high level of genetic admixture, the guinea fowl populations could best be distinguished using wing length, body length and eye colour. However, further complementary work on genomics will guide future selection and breeding programmes geared towards improving the productivity, survival and environmental adaptation of indigenous helmeted guinea fowls in the tropics.

genetics↗

bioRxiv2019

Disruption of Nrxn1α within excitatory forebrain circuits drives value-based dysfunction

Goal-directed behaviors, complex action sequences that maximize reward, are essential for normal function and are significantly impaired across neuropsychiatric disorders. Despite extensive associations between genetic mutations and these brain disorders, the mechanisms by which candidate genes contribute to goal-directed dysfunction remains unclear, owing to challenges in (1) describing aspects of reward processing that drive goal-directed dysfunction, (2) localizing these deficits to specific brain circuits and (3) relating changes in physiology to behavioral alterations. Here we examined mice with mutations in Neurexin1, a presynaptically-localized adhesion molecule with widespread neuropsychiatric dis ease association, in value-based decision-making paradigms. We found that Neurexin1 knockout animals exhibited blunted choice bias towards outcomes associated with greater benefits. Mutant mice were similarly impaired in avoiding costlier, benefit-neutral actions. Analysis of trial-by-trial choice data via reinforcement learning models suggested these behavioral patterns were driven largely by deficits in the updating and representation of choice values. Employing conditional gene ablation and region-specific Cre-recombinase strains, we revealed that Neurexin1 disruption within forebrain excitatory projection neurons, but not thalamic population s, recapitulated most aspects of the whole-brain knockout phenotype. Finally, utilizing in vivo recordings of direct pathway spiny neuron population calcium activity, we demonstrated that selective knockout of Neurexin1 within forebrain excitatory neurons disrupts reward-associated neural signals within striatum, a major site of feedback-based learning. By relating deficits in value-based decision-making to region-specific Nrxn1 disruption and changes in reward-associated neural activity, we reveal potential neural substrates for the pathophysiology of neuropsychiatric disease-associated cognitive dysfunction.

neuroscience↗