Christian O. Chukwuka

Christian O. Chukwuka
University of Otago · Department of Zoology

PhD

About

25
Publications
18,906
Reads
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158
Citations
Additional affiliations
January 2015 - October 2016
Federal University Ndufu Alike Ikwo
Position
  • Lecturer
Education
November 2016 - December 2020
University of Otago
Field of study
  • Zoology
February 2011 - June 2013
University of Nigeria
Field of study
  • Zoology (Environmental Physiology)
August 2005 - September 2007
University of Nigeria
Field of study
  • Biology

Publications

Publications (25)
Article
Rocky retreats are limited and geologically constrained resources for rock-dwelling nocturnal lizards. Such lizards should seek retreats that offer thermoregulatory benefits without the risk of overheating during the day, and that protect from predation. For cold-adapted species where air temperature is frequently lower than optimum temperature for...
Preprint
Environmental temperature profoundly influences the body temperatures of reptiles, and hence the rates at which physiological processes occur. We review progress in understanding the thermal ecophysiology of New Zealand’s endemic, terrestrial reptiles (tuatara, geckos, and skinks), and in applying this knowledge to conservation. By understanding th...
Article
Previous study using the traditional method of screening snails for infection reported shedding of Schistosoma cercaria by Biomphalaria snails from a river in Nkalagu, southeastern Nigeria. This is contrary to published reports that Biomphalaria from this part of the country does not shed schistosome cercaria. Here, we employed the use of polymeras...
Article
Understanding the interaction between upper voluntary thermal limit (VTmax) and water loss may aid in predicting responses of ectotherms to increasing temperatures within microhabitats. However, the temperature (VTmax) at which climate heating will force cool-climate, nocturnal lizards to abandon daytime retreats remains poorly known. Here, we deve...
Thesis
Ectotherms, especially terrestrial squamates, rely on suitable microclimatic conditions to maintain critical physiological processes. Selection of appropriate microhabitat determines how well squamates will function in fluctuating thermal environments. Understanding the use of microhabitat by cool-climate lizards, including the long-lived gecko, Wo...
Article
Studies of thermal sensitivity in ectotherms require accurate measurements of body temperature using a reliable device, including in field situations. In this study, we tested the accuracy of a compact and inexpensive mini-infrared thermometer (mini-IRT, 22.3 g) at close distance (within 5 mm) for measuring skin surface temperature of small lizards...
Article
Comparisons of sympatric species inhabiting the same ecological habitat may elucidate adaptive processes. We studied the physiological patterns of two species of the genus Limicolaria (L. aurora and L. flammea) that thrive in a hot tropical habitat. We examined changes in water content, biochemical fuel reserves and haemolymph enzyme activities dur...
Article
Full-text available
Basis: The fruit extract of Dacryodes edulis, the African pear or plum, a tree indigenous to the humid tropics has been used for managing wounds, skin diseases,in sickle cell anaemia, dysentery and fever in some African nations. In South Eastern Nigeria, 'herbal doctors' include its marshed fruit in decoctions administered diabetic patients. Howeve...
Article
Full-text available
Objective: To investigate the physiological effects of paraquat in African freshwater catfish Clarias gariepinus. Methods: Two sublethal test concentrations of paraquat (1.37 and 2.75 mg/L) were chosen based on the 96 h LC50 value (27.46 mg/L). Some experimental fish were exposed to these concentrations and control group for 15 d. Peripheral blood...
Article
Full-text available
Mucuna sloanei is a legume used as a soup thickener by communities in some parts of Africa countries. The effect of aqueous seed extract of M. sloanei on the haematological profile of normal albino rats was investigated for 28 days using standard methods. The results show no overall dose dependent significant difference (p > 0.05) in the serum leve...
Article
Full-text available
The hepato-and nephro-protective potentials of Vernonia amygdalina ethanolic root extract was evaluated for 14 days using standard bioassay in 45 normal male albino rats. The rats were divided into four treatment groups I – IV and a control group V. Groups I – IV were given 100mg.kg-1 , 200mg.kg-1, 400mg.kg-1 and 600mg.kg-1 body weight, respectivel...
Article
Full-text available
The behavioural and serum liver enzyme responses of juvenile catfish (Clarias gariepinus) were evaluated for 72 hours. Thirty-six (36) healthy fishes with standard weight, 20 ± 1.52 g and standard length, 18.25 ± 0.50 cm were used for the experiment in non-renewable bioassay system. The test fish exhibited stressful behavioural changes such as erra...
Article
Full-text available
Two months preliminary survey of the prevalence of diarrhoea among children (aged 5 – 10 years) was carried out in Nsukka area of Enugu State, Nigeria. Questionnaires were used to obtain information on the demographic details of the parents and children, prevalence, management and control of diarrhoea among children of this age group. These were di...
Article
Full-text available
The survival of land snails in an adverse environmental condition depends on the integral physiological, morphological and behavioural adaptations. These adaptations are essential in understanding the species-specific habitat requirements and in predicting their environmental responses. In this study, the monthly and the periodic patterns of eco-ph...
Article
Full-text available
The effects of four weeks administration of the methanolic seed extract of Cola acuminata on the haematology and serum cortisol profiles of adult male albino rats were investigated. Dose dependent significant effects of the extract were recorded in the white blood cell count and mean corpuscular volume (p<0.05). While the effects on the red blood c...
Article
Full-text available
This research was done to assess the phytochemical composition and possible effects for 28 days oral administration of aqueous crude seed extracts of Mucuna sloanei on organ weights of normal albino rats at weekly intervals. Forty eight adult male albino rats weighing between 150 to 250 g were divided into three treatment groups and one control gro...
Data
Full-text available
The effect of supplementing soya bean meal with feather meal was investigated to determine diet acceptability and growth performance of Heteroclarias species. The fishes were divided into six treatment groups containing three fishes per replicate basin. The groups were control (0% FEM), 2.5% FEM, 5% FEM, 7.5% FEM, 10% FEM and 12.5% FEM. Acceptabili...
Article
Full-text available
Abstract The present study was aimed at evaluating the effects of different concentrations of the most commonly used fish antimicrobial drug, chloramphenicol (CAP), on the behavior and hematological parameters of Clarias gariepinus. Fish specimens were exposed to three (2.5, 5.0 and 10.0 mg L(-1)) sublethal concentrations of CAP and a control. Abno...
Article
Full-text available
The effect of aqueous extract of Hibiscus sabdariffa calyces on the haematological profile of normal male albino rats was investigated for 28 days using standard methods. The rats were divided into five groups comprising of the control group, I; which received equal volume of distilled water and four treatment groups, II, III, IV and V that were ad...
Article
Full-text available
The mesocarp of pawpaw fruits (Carica papaya) is a delicacy in the tropics. However, the seeds contain toxic substances such as carpine, papain, etc. The first phase of the present study determines the acute toxicity of C .papaya seed extract to Clarias gariepinus juveniles using static bioassay. Sixty juveniles with mean weight 3.86 ± 1.18g and me...
Article
Full-text available
The mesocarp of pawpaw fruits (Carica papaya) is a delicacy in the tropics. However, the seeds contain toxic substances such as carpine, papain, etc. The first phase of the present study determines the acute toxicity of C .papaya seed extract to Clarias gariepinus juveniles using static bioassay. Sixty juveniles with mean weight 3.86 } 1.18g and m...
Thesis
Monthly and periodic patterns of eco-physiological adaptations and morphometric variations of land snails in Nsukka area of Enugu State were studied for eight months from December 2011 to July 2012. Seven species of land snails were sampled using a combination of quadrat count and direct search method. The distribution and abundance of the snails s...

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Projects (2)
Project
The Otago/Southland gecko (Woodworthia “Otago/Southland”) is found only in Southern New Zealand, including at the tussock grasslands at Macraes. Macraes is a prominent site for its high lizard diversity (7 species of lizards), comprising six species of Oligosoma skinks existing sympatrically with the Otago/Southland geckos. The Macraes habitat consists of tussock grassland with numerous rock outcrops and tors. The rock outcrops are flanked by tussock grass vegetation at the base such as Chionochloa rubra and C. rigida; and hard tussock, Festuca novae-zelandiae etc. The Otago/Southland gecko has the conservation status “At Risk – Declining” . The species is thought to be declining due to habitat loss and predation. But, Tingley et al., suggested that future research on the New Zealand herpetofauna should consider both the intrinsic traits and extrinsic threats, for accurate prediction and prevention of further population declines. Existing threats include habitat disruption and predatory mammals. However, global climate change, including warmer temperatures, is of great concern for the future preservation of biodiversity in general . New Zealand is experiencing warmer temperatures, and climate experts predict that these trends will continue. To predict how increased warming and changes in other climatic variables will affect the Otago/Southland gecko, we need to understand the current pattern of retreat site use by these geckos, and how it is related to weather conditions. Long-term warming may result in lizards emigrating to a cooler environment, or changing their retreat-sites (as mobile animals behaviourally exploit thermal variations and control their body temperature (Tb) within narrow ranges). It is clear that very low or high Tb reduces the performance of organisms and can be lethal. Exposure to extreme high temperatures can result in loss of motor functioning, and affect critical physiological processes in ectotherms
Project
The adaptation of land snails in the tropics is dependent on the balance between the environmental stressors and magnitude of tolerance in maintaining their internal milieu. Death due to thermal heat and rate of change in body water as a result of decrease in tissue osmolality had resulted in desiccation of tropical land snails during aestivation. Although alterations in physiology that occur in aestivating and anoxic snails have received much attention during the last two decades in Mediterranean snails, the changes in physiology in tropical snails during aestivation and other questions regarding the mechanism promoting metabolic depression in the tropics remain unattended. Aestivation causes hypercapnia, increase in solute concentration, decrease in metabolic rate and oxygen consumptions, metabolic acidosis of the extracellular fluid due to decrease in bicarbonate level and decrease in pHe etc. (Michaelidis, 2002). The rate and extent of acidosis in extracellular fluids have been shown to vary among several species of terrestrial snails (Michaelidis, 2002). It is not known whether the differences in the rate and extent of acidosis modulate the metabolism correspondingly especially in tropical land snail species. Moreover, the extent of coupling between pHe and pHi in the tissues of tropical land snails during aestivation and anoxia is not known. It has been documented that changes in pH regulate metabolic depression in the tissues of aestivating land snails (Michaelidis, 2002). Parallel decline of pHi and pHe during artificial hypercapnia and acidosis have been reported in Otala lactea and Orohelix strigossa (Rees et al., 1991). Since energy metabolism during aestivation is based on anaerobic processes (without oxygen), land snails possess a high glycolytic potential for anaerobic energy production in an oxygen free environment. In a prolonged anoxia, pyruvate is converted to fatty acid biosynthesis resulting in an increased fatty acid levels (Michaelidis et al., 1999). D-lactate then is decarboxylated anaerobically to acetyl Co-A which is used for lipid metabolism in order to clear the excess fatty acid accumulation. Therefore, accumulation of D-lactate, succinate and other end products of anaerobic metabolism in the haemoplymph and tissue of land snails during dormancy alters the acid-base balance in the extracellular fluid. Nevertheless, the mechanism by which the acid-base status affects the tissues of land snails during anoxia and aestivation in the tropics is lacking. Several physiological processes are coupled to aid animal survival during aestivation. Some of these include, net fluctuation in body water content, decrease in metabolic rate, depletion of stored fuel and apnoeic breathing pattern (Chukwuka, 2012). These processes result in cellular oxidative stress, and imbalance in the acid-base status of the organism’s internal environment. Surviving harsh environmental conditions especially in the tropics might be as a result of cellular stress resistance by aestivators. Stressors elicit an intracellular redox imbalances associated with ROS over production which results in macromolecular oxidative damages (Solani and Haris, 2005). The upregulation of antioxidant enzymes may confer stress resistance in the hypometabolic state (Carey et al., 2003). Snails experience relatively rapid increase in metabolic rate and oxygen consumption which could lead to the increase in ROS production and thus oxidative stress (Storey, 2002). Measurement of intracellular antioxidant enzymes’ activities during aestivation and anoxia provides evidence for upregulation in several tissues (Hermes-Lima and Storey, 1995), which was suggested to provide protection against ischemia reperfusion associated with aestivation-arousal transitions. Moreso, it is obvious that the heat shock protein protects organisms from the detrimental effects of heat and other stressors. The mechanism of induction of this protein in tropical snail species remains unknown. Also, our knowledge of how these snail species differ in survival tolerance with various modifications in metabolism and adaptive process is limited. In the above limelight, it is therefore necessary to explore the physiological modifications associated with aestivation and anoxia in the tropical land snail species.