Genetic analysis of latrophilin in the toxicity of combined latrotoxins for C. elegans

Black widow spider venom (BWSV) contains high molecular weight proteins called latrotoxins (LTX) that induce catastrophic neurotransmitter release from nerve terminals, and one toxin, α-latrotoxin, is known to bind with high affinity to three neural proteins in mammals, including latrophilin (lat-1) a member of the class B family of G-protein coupled receptors. We have established C.elegans as a model organism to study the function of the binding protein, lat-1 and its role in regulating neurotransmitter release by latrotoxins. However, a lat-1-knockout worm is required for determining the function of the lat-1 gene. The lat-1(ok1465) allele has a deletion of the lat-1 gene, and ~95-98% of lat-1(ok1465) homozygous worms arrest or die before adulthood, with only ~2-5 adult offspring per animal. Micro-injection of the B0457 cosmid, that contains the full sequence of the lat-1 gene, or the lat-1a cDNA rescued the lethality of the lat-1 worms, thereby showing that lat-1 gene is responsible for the developmental lethality in these worms. Expression of the marker, GFP, under the control of the lat-1 promoter showed that there was expression of GFP during epithelial morphogenesis, and strong expression in the gut from the three-fold stage through to larval stages. The concordance between the site of expression of lat-1::gfp, with the sites of embryonic defects (epithelial enclosure defects; defective attachement of gut) in lat-1(ok1465) animals, provides further evidence that lat-1 is essential for embryonic and larval development. Deletion mutants of lat-1a were constructed to examine the role of domains of this protein. Deletion of sequences after the 4xCys domain of lat-1a did not affect the ability to rescue lethality in the lat-1 worm, while deletion of the C-terminus to the seven transmembrane domain impaired the ability of lat-1a to rescue lat-1 worms, and further deletion of six of seven transmembrane domains (the TM1 construct) yielded a construct that was unable to rescue lat-1 worms. These data suggest an important role for intracellular sequences and seven transmembrane in lat-1a signalling. It was proposed that TM1 could decoy ligand, without causing intracellular signalling. In agreement, the TM1 construct caused a mild phenocopy of the lat-1(ok1465) mutant in wild-type worms, whereas full-length, or non-ligand binding variants of lat-1a caused no such effect. To investigate the putative ligand-binding domain of lat-1a, deletion of residues 62-147 (ΔGBL), 62-250 (ΔHRM) and 62-487 (ΔN) was investigated; while the ΔN construct was incapable of rescuing lat-1(ok1465) worms, deletion of ΔGBL had a minor effect on the ability of lat-1 to rescue the null worms, while ΔHRM had a more marked effect. These data are consistent with a model whereby residues 147-487 are required for ligand binding, and the seventransmembrane and intracellular domains transmit a signal to the inside of the cell. Combined latrotoxins was highly toxic to wild-type C.elegans (LD50 ~4ng/ml), whereas the lat-1 worms were highly (>105-fold) resistant to combined latrotoxins. Lat-1 worms that were transgenic for B0457cosmid, or lat-1a cDNA, were as sensitive to combined latrotoxins as wildtype worm. Truncation of the C-terminus of lat-1a to TM1 yielded worms that had 105-fold resistance to combined latrotoxins, compared to wild-type; thus the intracellular domain of lat-1 is required for mediating combined latrotoxins toxicity. The deletion of galatactose-binding lectin (ΔGBL) in N-terminus lat-1a was sensitive as wild-type, but deletion of hormone receptor motif (ΔHRM) in N-terminus lat-1a showed a reduced sensitivity to combined latrotoxins by ~105-fold. These data showed presence of lat-1 gene was responsible for the rescue of lat-1 worms or toxicity of combined latrotoxins in lat-1 worms, and the absence of lat-1 gene was responsible for the lethality of lat-1 worms and resistance to combined latrotoxins in lat-1 worms

Key dimensions of land users’ perceptions of land degradation and sustainable land management in Niger State, Nigeria

Declining land productivity remains a challenge for agriculture-based livelihoods and for achieving food security. Yet identifying how land users perceive land degradation and their capacity to manage land in an environmentally sustainable manner can influence the measures initiated to address it. Using the case of Niger State, Nigeria, this study examines land users’ perceptions of land degradation and land management measures to address it in the Nigerian Guinea Savannah. We used the Moderate-resolution Imaging Spectroradiometer derived Normalized Difference Vegetation Index as a proxy for degradation status, selecting 30 communities based on the extent of degraded areas. We adapted the World Overview of Conservation Approaches and Technologies, Sustainable Land Management questionnaires to capture perceptions and administered 225 questionnaires to land users. Through key informant interviews, we collected narrative insights and data on perspectives and motivations of land users to understand land degradation situations and to interpret the questionnaire surveys. We analysed data through descriptive statistics, Principal Component Analysis and qualitative analysis. Our analysis identified four perceptions dimensions of land degradation characteristics, two perceptions dimensions of land degradation drivers, and six perceptions dimensions of sustainable land management. The results also confirmed that degradation in Niger State is both due to widespread unsustainable human activities within Niger state and those by migrant farmers and pastoralism from adjoining Sudan Sahelian states that push people further south, a leakage of ongoing land degradation and conflicts in other areas. To deal with local land degradation in Niger State, improved land tenure, alternative livelihood strategies, poverty eradication and awareness, nature-based sustainable land management practices such as tree-based initiatives, environmentally friendly agriculture such as Farmer Managed Natural Regeneration supported by the necessary political will and institutions are critical

Increasing signs of forest fragmentation in the Cross River National Park in Nigeria: Underlying drivers and need for sustainable responses

Protected areas are expectedly intact habitats for biodiversity and key for ecosystem conservation. However, where inadequately protected, human-induced forest fragmentation can degrade them and reduce their functioning. Therefore, monitoring forests in protected areas is essential to ascertain their protection. This paper assesses forest fragmentation in the Cross River National Park, a biodiversity hotspot in the tropical rainforest of Nigeria. Forest fragmentation was analyzed using the Driver-Pressure-State-Impact-Response framework. Fragmentation analysis of the State used class-level pattern metrics on Landsat and Sentinel images from the years 2000, 2015 and 2020. Forest fragmentation has reduced total forest area, decreased average size of forest patches, increased the number of forest patches and amount of edge. Only the isolation of forest patches has not yet reached a measurable intensity. However, spatio-temporal forest fragmentation over the years 2000, 2015 and 2020 indicates a rising trend, especially between 2015 and 2020. The Drivers, Pressures, Impacts and Responses were investigated through a systematic literature review. Many studies show that the main proximate Drivers of forest fragmentation are agricultural activities mainly by the local communities, demand for forest resources by the growing population, and by external actors through illegal logging and infrastructure building, which have increased. However, wider literature highlight issues of disproportionately blaming local resource users, and the need to examine the neglect of justice, rights and local values, and their implications for sustainable protected areas. Reported Impacts include hindered migration of the endangered Cross River gorilla and impaired ecosystem services like water cycling, carbon sequestration and disease regulation. Responses have generally excluded the local communities, have failed or are yet to become effective. There is thus a need to identify, together with the involved actors, why measures have failed and to implement more sustainable options to reduce fragmentation in the park while addressing local users’ needs

Potential benefits of genetic modification (GM) technology for food security and health improvement in West Africa: Assessing the perception of farmers in Ghana and Nigeria

We assessed the perception of farmers towards potential adoption of genetic modification (GM) technology for improving health, food security and agricultural productivity using a semi-structured interview. A total sample of 54 small-scale farmers participated in 6 focus group meetings (FGMs) and 23 in-depth interviews at six locations in Ghana and Nigeria (West Africa). Our results reveal that most farmers have a very poor understanding of GM technology which they often misunderstood as traditional plant breeding biotechnology. While most respondents focused on the potential benefits of GM technology including high-yielding varieties, better nutritional value and shorter growing cycle crop traits, only a few respondents were concerned about the potential health and environmental risks of GM technology. Root and tuber crops such as cassava, yam and sweet potato were mostly discussed for health improvement and food security through GM technology. This study emphasizes the need to recognize challenges such as lack of awareness, inadequate training, low level of education and poor extension services among others in introducing new technology including GM technology to resource poor farmers in African countries like Ghana and Nigeria. We conclude that failure to address these challenges will impede the adoption of GM technology. Therefore, Ghanaian and Nigerian government(s) must put in place policy measures to address these problems.Keywords: Food security, health improvement, genetic modification (GM) technology, Ghana, Nigeria, West Africa farmersAfrican Journal of Biotechnology, Vol. 13(2), pp. 245-256, 8 January, 201

Identification and Functional Clustering of Genes Regulating Muscle Protein Degradation from amongst the Known C. elegans Muscle Mutants

Loss of muscle mass via protein degradation is an important clinical problem but we know little of how muscle protein degradation is regulated genetically. To gain insight our labs developed C. elegans into a model for understanding the regulation of muscle protein degradation. Past studies uncovered novel functional roles for genes affecting muscle and/or involved in signalling in other cells or tissues. Here we examine most of the genes previously identified as the sites of mutations affecting muscle for novel roles in regulating degradation. We evaluate genomic (RNAi knockdown) approaches and combine them with our established genetic (mutant) and pharmacologic (drugs) approaches to examine these 159 genes. We find that RNAi usually recapitulates both organismal and sub-cellular mutant phenotypes but RNAi, unlike mutants, can frequently be used acutely to study gene function solely in differentiated muscle. In the majority of cases where RNAi does not produce organismal level phenotypes, sub-cellular defects can be detected; disrupted proteostasis is most commonly observed. We identify 48 genes in which mutation or RNAi knockdown causes excessive protein degradation; myofibrillar and/or mitochondrial morphologies are also disrupted in 19 of these 48 cases. These 48 genes appear to act via at least three sub-networks to control bulk degradation of protein in muscle cytosol. Attachment to the extracellular matrix regulates degradation via unidentified proteases and affects myofibrillar and mitochondrial morphology. Growth factor imbalance and calcium overload promote lysosome based degradation whereas calcium deficit promotes proteasome based degradation, in both cases myofibrillar and mitochondrial morphologies are largely unaffected. Our results provide a framework for effectively using RNAi to identify and functionally cluster novel regulators of degradation. This clustering allows prioritization of candidate genes/pathways for future mechanistic studies

Response to issues on GM agriculture in Africa: Are transgenic crops safe?

The controversies surrounding transgenic crops, often called Genetically Modified Organisms (GMOs), call for a need to raise the level of public awareness of Genetic Modification (GM) technology in Africa. This should be accomplished by educating the public about the potential benefits and risks that may be associated with this new technology. In the last 15 years, GM crop producing countries have benefited from adoption of this new technology in the form of improved crop productivity, food security, and quality of life. The increased income to resource-poor farmers is a key benefit at the individual level especially as most countries using this technology are in the developing world, including three African countries (South Africa, Burkina Faso and Egypt). Despite clear benefits to countries and farmers who grow GMOs, many people are concerned about suspected potential risks associated with GMOs. This sparks debate as to whether GM technology should be adopted or not. Given the concerns regarding the safety of GMO products, thorough scientific investigation of safe application of GMOs is required. The objective of this paper is to respond to the issues of GM agriculture in Africa and some of the issues surrounding the adoption of GM crops between developed and developing countries. In this article, I analyse relevant papers relating to the adoption of GM technology particularly in developing countries including the few African countries that have adopted GM crops. The issues discussed span a wide range including: safety; potential benefits and risks; disputes between the United States of America (USA) and the European Union (EU) over adoption of GM crops with a focus on Africa continent. This article is concluded by summarising the issues raised and how GM technology can be adopted for agricultural development in Africa

Managing climate change risks in Africa - A global perspective

n/

Genetic analysis of latrophilin in the toxicity of combined latrotoxins for C. elegans

Black widow spider venom (BWSV) contains high molecular weight proteins called latrotoxins (LTX) that induce catastrophic neurotransmitter release from nerve terminals, and one toxin, α-latrotoxin, is known to bind with high affinity to three neural proteins in mammals, including latrophilin (lat-1) a member of the class B family of G-protein coupled receptors. We have established C.elegans as a model organism to study the function of the binding protein, lat-1 and its role in regulating neurotransmitter release by latrotoxins. However, a lat-1-knockout worm is required for determining the function of the lat-1 gene. The lat-1(ok1465) allele has a deletion of the lat-1 gene, and ~95-98% of lat-1(ok1465) homozygous worms arrest or die before adulthood, with only ~2-5 adult offspring per animal. Micro-injection of the B0457 cosmid, that contains the full sequence of the lat-1 gene, or the lat-1a cDNA rescued the lethality of the lat-1 worms, thereby showing that lat-1 gene is responsible for the developmental lethality in these worms. Expression of the marker, GFP, under the control of the lat-1 promoter showed that there was expression of GFP during epithelial morphogenesis, and strong expression in the gut from the three-fold stage through to larval stages. The concordance between the site of expression of lat-1::gfp, with the sites of embryonic defects (epithelial enclosure defects; defective attachement of gut) in lat-1(ok1465) animals, provides further evidence that lat-1 is essential for embryonic and larval development. Deletion mutants of lat-1a were constructed to examine the role of domains of this protein. Deletion of sequences after the 4xCys domain of lat-1a did not affect the ability to rescue lethality in the lat-1 worm, while deletion of the C-terminus to the seven transmembrane domain impaired the ability of lat-1a to rescue lat-1 worms, and further deletion of six of seven transmembrane domains (the TM1 construct) yielded a construct that was unable to rescue lat-1 worms. These data suggest an important role for intracellular sequences and seven transmembrane in lat-1a signalling. It was proposed that TM1 could decoy ligand, without causing intracellular signalling. In agreement, the TM1 construct caused a mild phenocopy of the lat-1(ok1465) mutant in wild-type worms, whereas full-length, or non-ligand binding variants of lat-1a caused no such effect. To investigate the putative ligand-binding domain of lat-1a, deletion of residues 62-147 (ΔGBL), 62-250 (ΔHRM) and 62-487 (ΔN) was investigated; while the ΔN construct was incapable of rescuing lat-1(ok1465) worms, deletion of ΔGBL had a minor effect on the ability of lat-1 to rescue the null worms, while ΔHRM had a more marked effect. These data are consistent with a model whereby residues 147-487 are required for ligand binding, and the seventransmembrane and intracellular domains transmit a signal to the inside of the cell. Combined latrotoxins was highly toxic to wild-type C.elegans (LD50 ~4ng/ml), whereas the lat-1 worms were highly (>105-fold) resistant to combined latrotoxins. Lat-1 worms that were transgenic for B0457cosmid, or lat-1a cDNA, were as sensitive to combined latrotoxins as wildtype worm. Truncation of the C-terminus of lat-1a to TM1 yielded worms that had 105-fold resistance to combined latrotoxins, compared to wild-type; thus the intracellular domain of lat-1 is required for mediating combined latrotoxins toxicity. The deletion of galatactose-binding lectin (ΔGBL) in N-terminus lat-1a was sensitive as wild-type, but deletion of hormone receptor motif (ΔHRM) in N-terminus lat-1a showed a reduced sensitivity to combined latrotoxins by ~105-fold. These data showed presence of lat-1 gene was responsible for the rescue of lat-1 worms or toxicity of combined latrotoxins in lat-1 worms, and the absence of lat-1 gene was responsible for the lethality of lat-1 worms and resistance to combined latrotoxins in lat-1 worms.EThOS - Electronic Theses Online ServiceGBUnited Kingdo