Pub Date : 2016-04-13DOI: 10.26443/msurj.v11i1.162
V. Caron, Ariel Greiner, K. Ransier, Bryna Cameron-Steinke
Background: Over the past few decades, climate change and the intensification of coastal development significantly contributed to the degradation of coral reefs across the Caribbean Sea. Widespread increase in algal cover on coral reefs since the 1970s has made it difficult for the corals to recover. Thus, algae regulating factors, such as herbivorous grazers and groundwater nutrient concentrations, have important implications for the conservation of coral reefs. In this study we conducted a small-scale assessment of the relationship between the abundance of two families of herbivorous fishes, Scaridae and Acanthuridae, and algal cover on the coral reefs of West Coast Barbados was conducted, and we hypothesized that a direct negative correlation exists between them. Methods: Herbivorous fish abundance and percent algal cover were quantified for three different coral reefs, and the data was analyzed using linear regressions and analyses of variance. Results: We found that although there were no significant relationship between herbivorous fish abundance and algal cover, there was a significant difference between them across the three reefs studied. These results suggest the presence of other factors influencing algal cover. One such factor could potentially be ground- water input levels, which was found to differ at each of the three sites studied. Limitations: The limited timeframe of this study did not allow for extensive sampling. Conclusion: In order to effectively protect the coral reefs in Western Barbados, Further studies are needed to increase the understanding of the relationship between herbivory and algal cover in Western Barbados as well as to further investigate the role of groundwater seepage on algal growth.
{"title":"The Relationship between Large Herbivore Abundance and Algal Cover on Coral Reefs on West Coast Barbados","authors":"V. Caron, Ariel Greiner, K. Ransier, Bryna Cameron-Steinke","doi":"10.26443/msurj.v11i1.162","DOIUrl":"https://doi.org/10.26443/msurj.v11i1.162","url":null,"abstract":"Background: Over the past few decades, climate change and the intensification of coastal development significantly contributed to the degradation of coral reefs across the Caribbean Sea. Widespread increase in algal cover on coral reefs since the 1970s has made it difficult for the corals to recover. Thus, algae regulating factors, such as herbivorous grazers and groundwater nutrient concentrations, have important implications for the conservation of coral reefs. In this study we conducted a small-scale assessment of the relationship between the abundance of two families of herbivorous fishes, Scaridae and Acanthuridae, and algal cover on the coral reefs of West Coast Barbados was conducted, and we hypothesized that a direct negative correlation exists between them. \u0000Methods: Herbivorous fish abundance and percent algal cover were quantified for three different coral reefs, and the data was analyzed using linear regressions and analyses of variance. \u0000Results: We found that although there were no significant relationship between herbivorous fish abundance and algal cover, there was a significant difference between them across the three reefs studied. These results suggest the presence of other factors influencing algal cover. One such factor could potentially be ground- water input levels, which was found to differ at each of the three sites studied. \u0000Limitations: The limited timeframe of this study did not allow for extensive sampling. \u0000Conclusion: In order to effectively protect the coral reefs in Western Barbados, Further studies are needed to increase the understanding of the relationship between herbivory and algal cover in Western Barbados as well as to further investigate the role of groundwater seepage on algal growth.","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-13DOI: 10.26443/msurj.v11i1.163
Zhubo D. Zhang, M. Chacron
Background: Natural stimuli can range orders of magnitude, and their encoding by the brain remains a central issue in neuroscience. An efficient way of encoding a natural stimulus is by changing a neuron’s cod- ing rule in tandem with changes in the stimulus. This phenomenon is called sensory adaptation. However, sensory adaptation creates ambiguity in the neural code, as different stimuli can produce the same neural response. Methods: One way to resolve this ambiguity is to encode additional stimulus information through parallel channels. We performed in vivo extracellular recordings from pyramidal cells in two parallel maps, the lateral segment (LS) and the centro-medial segment (CMS), within the hindbrain of the weakly electric fish Aptero- notus leptorhynchus, in response to stimuli that resemble the presence of another conspecific. Results: We found that CMS pyramidal cells generally adapted less strongly than LS cells (p<0.05). Signal detection theory confirms that the lesser degree of adaptation leads to a stronger ability to disambiguate between two input stimuli (p<0.05). In addition, the time course of adaptation in LS strictly followed a power law while that of CMS followed a power law only for a certain set of stimuli. Limitations: The design of our study allowed for a stimulus that oscillated only between two distributions. Further studies into the hindbrain’s ability to disambiguate the adaptive code will require confusion analysis of a stimulus that changes between more distributions. For confusion studies, cells in different areas can be compared as long as they have receptive fields in similar areas. Conclusions: Through recording from two parallel segments of the electro-sensory system in the hindbrain, we observed that different segments adapted with different strengths to similar stimuli. Different amounts of adaptation allude to a balance between the need to preserve absolute stimulus information while simul- taneously encoding a stimulus efficiently through adaptation.
背景:自然刺激可以有数量级的变化，大脑对其进行编码仍然是神经科学的核心问题。对自然刺激进行编码的一种有效方法是随着刺激的变化而改变神经元的编码规则。这种现象被称为感觉适应。然而，感觉适应在神经编码中产生歧义，因为不同的刺激可以产生相同的神经反应。方法:一种解决这种模糊的方法是通过并行通道编码额外的刺激信息。我们对弱电鱼Aptero- notus leptorhynchus后脑内锥体细胞的两个平行图(外侧段(LS)和中央-内侧段(CMS))进行了体内细胞外记录，以响应类似于另一个同类存在的刺激。结果:CMS锥体细胞的适应能力普遍低于LS细胞(p<0.05)。信号检测理论证实，适应程度越低，消除两种输入刺激之间歧义的能力越强(p<0.05)。此外，LS的适应时间过程严格遵循幂律，而CMS的适应时间过程仅对某一组刺激遵循幂律。局限性:我们研究的设计允许刺激只在两个分布之间振荡。对后脑消除自适应代码歧义能力的进一步研究，将需要对在更多分布之间变化的刺激进行混淆分析。对于混淆的研究，只要不同区域的细胞在相似的区域有接受野，就可以进行比较。结论:通过对后脑电感觉系统两个平行节段的记录，我们观察到不同节段对相似刺激的适应强度不同。不同程度的适应暗示了在需要保留绝对刺激信息的同时，通过适应有效地编码刺激之间的平衡。
{"title":"Scale-Invariant Adaptation in Response to Second-Order Electro-Sensory Stimuli in Weakly Electric Fish","authors":"Zhubo D. Zhang, M. Chacron","doi":"10.26443/msurj.v11i1.163","DOIUrl":"https://doi.org/10.26443/msurj.v11i1.163","url":null,"abstract":"Background: Natural stimuli can range orders of magnitude, and their encoding by the brain remains a central issue in neuroscience. An efficient way of encoding a natural stimulus is by changing a neuron’s cod- ing rule in tandem with changes in the stimulus. This phenomenon is called sensory adaptation. However, sensory adaptation creates ambiguity in the neural code, as different stimuli can produce the same neural response. \u0000Methods: One way to resolve this ambiguity is to encode additional stimulus information through parallel channels. We performed in vivo extracellular recordings from pyramidal cells in two parallel maps, the lateral segment (LS) and the centro-medial segment (CMS), within the hindbrain of the weakly electric fish Aptero- notus leptorhynchus, in response to stimuli that resemble the presence of another conspecific. \u0000Results: We found that CMS pyramidal cells generally adapted less strongly than LS cells (p<0.05). Signal detection theory confirms that the lesser degree of adaptation leads to a stronger ability to disambiguate between two input stimuli (p<0.05). In addition, the time course of adaptation in LS strictly followed a power law while that of CMS followed a power law only for a certain set of stimuli. \u0000Limitations: The design of our study allowed for a stimulus that oscillated only between two distributions. Further studies into the hindbrain’s ability to disambiguate the adaptive code will require confusion analysis of a stimulus that changes between more distributions. For confusion studies, cells in different areas can be compared as long as they have receptive fields in similar areas. \u0000Conclusions: Through recording from two parallel segments of the electro-sensory system in the hindbrain, we observed that different segments adapted with different strengths to similar stimuli. Different amounts of adaptation allude to a balance between the need to preserve absolute stimulus information while simul- taneously encoding a stimulus efficiently through adaptation.","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-13DOI: 10.26443/msurj.v11i1.165
Moushumi Nath, Xinwen Zhu
Background: Visual perception constitutes the dominant method by which we process our environment, yet the neuronal substrates that underlie visual perception in the brain are not well understood. Noise correla- tion, defined as the correlation in non-stimulus evoked activity between neurons, has been shown to impact both encoding and decoding processes of visual stimuli. We wanted to determine whether changes in noise correlation can predict behavioural performance in a coherent motion-detection task. Methods: Two macaque monkeys (Macaca mulatta) were trained in a coherent motion-detection task, where they learned to fixate on a screen and anticipate the onset of a motion coherence stimulus. During this task, spike activity from pairs of neurons of the middle temporal area (area MT) were recorded and data was analyzed using MATLAB. Specifically, we examined noise correlation as a function of time and success rate in the task. Results: We found a decrease in the correlation in activity between neurons in area MT prior to the onset of the motion coherence stimulus. This decrease was accompanied by improved behavioural performance in the motion coherence-detection task. Limitations: The activity in pairs of neurons may not accurately represent overall activity in a population of neurons. In addition, control experiments to better assess the nature of the common input that leads to a reduction in noise correlation were not conducted. Conclusions: Despite these limitations, we have shown that a reduction in noise correlation prior to stimulus onset is accompanied by improved behavioural performance, suggesting that noise correlation may be a critical parameter that can aid in our understanding of how visual perception occurs in the brain.
{"title":"Reduction in Noise Correlation is Associated with Improved Behavioural Performance","authors":"Moushumi Nath, Xinwen Zhu","doi":"10.26443/msurj.v11i1.165","DOIUrl":"https://doi.org/10.26443/msurj.v11i1.165","url":null,"abstract":"Background: Visual perception constitutes the dominant method by which we process our environment, yet the neuronal substrates that underlie visual perception in the brain are not well understood. Noise correla- tion, defined as the correlation in non-stimulus evoked activity between neurons, has been shown to impact both encoding and decoding processes of visual stimuli. We wanted to determine whether changes in noise correlation can predict behavioural performance in a coherent motion-detection task. \u0000Methods: Two macaque monkeys (Macaca mulatta) were trained in a coherent motion-detection task, where they learned to fixate on a screen and anticipate the onset of a motion coherence stimulus. During this task, spike activity from pairs of neurons of the middle temporal area (area MT) were recorded and data was analyzed using MATLAB. Specifically, we examined noise correlation as a function of time and success rate in the task. \u0000Results: We found a decrease in the correlation in activity between neurons in area MT prior to the onset of the motion coherence stimulus. This decrease was accompanied by improved behavioural performance in the motion coherence-detection task. \u0000Limitations: The activity in pairs of neurons may not accurately represent overall activity in a population of neurons. In addition, control experiments to better assess the nature of the common input that leads to a reduction in noise correlation were not conducted. \u0000Conclusions: Despite these limitations, we have shown that a reduction in noise correlation prior to stimulus onset is accompanied by improved behavioural performance, suggesting that noise correlation may be a critical parameter that can aid in our understanding of how visual perception occurs in the brain.","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-13DOI: 10.26443/msurj.v11i1.167
L. Chen
Background: Through transcriptional and post-transcriptional regulation, eukaryotic cells can control gene expression to moderate vital cell processes and induce morphological changes. In developmental biology, translation initiation is emerging as a key player in gene expression regulation. Translation initiation begins when eukaryotic initiation factor 4E (eIF4E) binds the 5’ mRNA cap to recruit other initiation factors. Eight eIF4E isoforms are present in Drosophila melanogaster. The canonical eIF4E-1 is involved in the translation of all genes and is a common target for translational regulation mechanisms. The activity of testis-specific eIF4Es in Drosophila are largely unclear, but recent evidence on eIF4E-3 suggests that the other isoforms may also possess distinct, essential functions in spermatogenesis. Methods: Here we provide protein localization data and loss-of-function analysis to characterize eIF4E-4, eIF4E-5, and eIF4E-7. Results: Single KD showed few phenotypes, while eIF4E-4/eIF4E-5 double knockdown males had severe de- fects in spermatogenesis. In eIF4E-5/eIF4E-7 double knockdowns, mutations manifested in multiple stages of severity. Conclusions: The unique expression patterns and differential mutant phenotypes observed suggest that the testis-specific isoforms contain varying levels of functional redundancy. eIF4E-4 and eIF4E-5, which share close homology, appear to have overlapping roles in regulating germ cell division during early spermato- genesis. However, during spermatid individualization they seem to assume different functions. eIF4E-7 also appears to be involved in germ cell differentiation, but most likely in a separate mechanism due to the inability of other isoforms to compensate for its knockdown.
{"title":"Loss-of-Function Analysis Elucidates Essential Roles of eIF4E Isoforms in Drosophila Spermatogenesis","authors":"L. Chen","doi":"10.26443/msurj.v11i1.167","DOIUrl":"https://doi.org/10.26443/msurj.v11i1.167","url":null,"abstract":"Background: Through transcriptional and post-transcriptional regulation, eukaryotic cells can control gene expression to moderate vital cell processes and induce morphological changes. In developmental biology, translation initiation is emerging as a key player in gene expression regulation. Translation initiation begins when eukaryotic initiation factor 4E (eIF4E) binds the 5’ mRNA cap to recruit other initiation factors. Eight eIF4E isoforms are present in Drosophila melanogaster. The canonical eIF4E-1 is involved in the translation of all genes and is a common target for translational regulation mechanisms. The activity of testis-specific eIF4Es in Drosophila are largely unclear, but recent evidence on eIF4E-3 suggests that the other isoforms may also possess distinct, essential functions in spermatogenesis. \u0000Methods: Here we provide protein localization data and loss-of-function analysis to characterize eIF4E-4, eIF4E-5, and eIF4E-7. \u0000Results: Single KD showed few phenotypes, while eIF4E-4/eIF4E-5 double knockdown males had severe de- fects in spermatogenesis. In eIF4E-5/eIF4E-7 double knockdowns, mutations manifested in multiple stages of severity. \u0000Conclusions: The unique expression patterns and differential mutant phenotypes observed suggest that the testis-specific isoforms contain varying levels of functional redundancy. eIF4E-4 and eIF4E-5, which share close homology, appear to have overlapping roles in regulating germ cell division during early spermato- genesis. However, during spermatid individualization they seem to assume different functions. eIF4E-7 also appears to be involved in germ cell differentiation, but most likely in a separate mechanism due to the inability of other isoforms to compensate for its knockdown.","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-13DOI: 10.26443/msurj.v11i1.170
Howie Wu
Background: Protein phosphorylation and dephosphorylation is an integral component of many cellular signaling pathways and regulatory mechanisms. Phosphatases are enzymes that catalyze the removal of phosphate groups from proteins. The phosphatases of regenerating liver (PRLs) are a family of phosphatases which have been correlated with cancer development and metastasis. However, they appear to have weak phosphatase activity and little is known about their physiological substrates. This review discusses PRL from a structural and functional perspective, including recent findings on its interaction with another family of proteins, cyclin M (CNNM). Methods: Articles were obtained from the scientific literature using databases like PubMed and McGill University’s open access institutional repository. This paper specifically focuses on those articles that provided an overview of phosphatases, PRLs, CNNMs, and structural and functional studies of PRLs and CNNMs. In total, 40 articles were selected for the purpose of this review. Summary: Although PRLs retain many of the structural features of other protein tyrosine phosphatases (PTPs) including the phosphatase catalytic motif and regulation via oxidation, other structural features such as mutation of a conserved serine/threonine residue to alanine in the active site disfavor catalytic activity. Moreover, PRL interaction with CNNM appears to be responsible for its oncogenic potential, yet this inter- action does not appear to require PRL phosphatase activity. Thus, PRL may be best classified as a pseudo-phosphatase, which are phosphatase-like proteins that are structurally similar to phosphatases but have acquired a dominant function that does not require phosphatase activity.
背景:蛋白质磷酸化和去磷酸化是许多细胞信号通路和调控机制的组成部分。磷酸酶是催化从蛋白质中去除磷酸基团的酶。再生肝磷酸酶(PRLs)是一类与肿瘤发生和转移有关的磷酸酶。然而，它们似乎具有较弱的磷酸酶活性，并且对其生理底物知之甚少。本文从结构和功能的角度讨论了PRL，包括其与另一个蛋白家族细胞周期蛋白M (cyclin M, CNNM)相互作用的最新发现。方法:利用PubMed和麦吉尔大学开放获取机构资源库等数据库从科学文献中获取文章。本文特别关注那些概述了磷酸酶、prl、CNNMs以及prl和CNNMs的结构和功能研究的文章。本次综述共选取了40篇文章。摘要:尽管prl保留了其他蛋白酪氨酸磷酸酶(PTPs)的许多结构特征，包括磷酸酶催化基序和氧化调控，但其他结构特征，如活性位点上保守的丝氨酸/苏氨酸残基突变为丙氨酸，不利于其催化活性。此外，PRL与CNNM的相互作用似乎是其致癌潜力的原因，但这种相互作用似乎不需要PRL磷酸酶活性。因此，PRL可能被最好地归类为伪磷酸酶，这是一种类似磷酸酶的蛋白质，在结构上与磷酸酶相似，但具有不需要磷酸酶活性的主要功能。
{"title":"Dead but not gone: The case for PRL as a pseudophosphatase","authors":"Howie Wu","doi":"10.26443/msurj.v11i1.170","DOIUrl":"https://doi.org/10.26443/msurj.v11i1.170","url":null,"abstract":"Background: Protein phosphorylation and dephosphorylation is an integral component of many cellular signaling pathways and regulatory mechanisms. Phosphatases are enzymes that catalyze the removal of phosphate groups from proteins. The phosphatases of regenerating liver (PRLs) are a family of phosphatases which have been correlated with cancer development and metastasis. However, they appear to have weak phosphatase activity and little is known about their physiological substrates. This review discusses PRL from a structural and functional perspective, including recent findings on its interaction with another family of proteins, cyclin M (CNNM).\u0000Methods: Articles were obtained from the scientific literature using databases like PubMed and McGill University’s open access institutional repository. This paper specifically focuses on those articles that provided an overview of phosphatases, PRLs, CNNMs, and structural and functional studies of PRLs and CNNMs. In total, 40 articles were selected for the purpose of this review.\u0000Summary: Although PRLs retain many of the structural features of other protein tyrosine phosphatases (PTPs) including the phosphatase catalytic motif and regulation via oxidation, other structural features such as mutation of a conserved serine/threonine residue to alanine in the active site disfavor catalytic activity. Moreover, PRL interaction with CNNM appears to be responsible for its oncogenic potential, yet this inter- action does not appear to require PRL phosphatase activity. Thus, PRL may be best classified as a pseudo-phosphatase, which are phosphatase-like proteins that are structurally similar to phosphatases but have acquired a dominant function that does not require phosphatase activity.","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-13DOI: 10.26443/msurj.v11i1.166
Mariya Stavnichuk, G. Sadvakassova, S. Komarova
Background: Numerous bone diseases are caused by abnormal activity of osteoclasts, cells responsible for physiological bone degradation. Understanding the mechanisms of osteoclast formation and activation is important for developing diagnostic tools and treatments for various bone diseases. Receptor activator of nuclear factor κB ligand (RANKL), a key osteoclastogenic cytokine, induces changes in intracellular Ca2+ con- centration ([Ca2+]i) that can be visualized and measured with a fluorescent Ca2+ binding dye. The objective of the study was to characterize the changes in [Ca2+]i induced by acute application of RANKL in osteoclast precursors. Methods: We performed calcium imaging in osteoclast precursors generated from RAW 264.7 cells loaded with Fura-2 fluorescent dye using an inverted microscope, Nikon TE2000-U. Data was collected with Volocity software and analysed in Excel and MATLAB. Results: In osteoclast precursors, RANKL induced oscillations in [Ca2+]i within 2 minutes of exposure. The main frequency of oscillations was approximately 37.7 mHz. However, no significant change in the mean level of intracellular Ca2+ was observed. Interestingly, when ATP was applied to RANKL-treated osteoclast precursors, it induced a long-lasting increase in [Ca2+]i compared to control cells. Limitations: The limitations of our study included the small number of replicates and the short duration of fluorescence recording under each condition. Conclusions: Short exposure of osteoclast precursors to RANKL not only induced oscillations in calcium con- centration, but also modulated cellular response to the subsequent application of ATP.
{"title":"Fluorescence Imaging of Receptor Activator of Nuclear Factor Kappa-B Ligand-Mediated Calcium Oscillations in Osteoclasts","authors":"Mariya Stavnichuk, G. Sadvakassova, S. Komarova","doi":"10.26443/msurj.v11i1.166","DOIUrl":"https://doi.org/10.26443/msurj.v11i1.166","url":null,"abstract":"Background: Numerous bone diseases are caused by abnormal activity of osteoclasts, cells responsible for physiological bone degradation. Understanding the mechanisms of osteoclast formation and activation is important for developing diagnostic tools and treatments for various bone diseases. Receptor activator of nuclear factor κB ligand (RANKL), a key osteoclastogenic cytokine, induces changes in intracellular Ca2+ con- centration ([Ca2+]i) that can be visualized and measured with a fluorescent Ca2+ binding dye. The objective of the study was to characterize the changes in [Ca2+]i induced by acute application of RANKL in osteoclast precursors. \u0000Methods: We performed calcium imaging in osteoclast precursors generated from RAW 264.7 cells loaded with Fura-2 fluorescent dye using an inverted microscope, Nikon TE2000-U. Data was collected with Volocity software and analysed in Excel and MATLAB. \u0000Results: In osteoclast precursors, RANKL induced oscillations in [Ca2+]i within 2 minutes of exposure. The main frequency of oscillations was approximately 37.7 mHz. However, no significant change in the mean level of intracellular Ca2+ was observed. Interestingly, when ATP was applied to RANKL-treated osteoclast precursors, it induced a long-lasting increase in [Ca2+]i compared to control cells. \u0000Limitations: The limitations of our study included the small number of replicates and the short duration of fluorescence recording under each condition. \u0000Conclusions: Short exposure of osteoclast precursors to RANKL not only induced oscillations in calcium con- centration, but also modulated cellular response to the subsequent application of ATP.","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-13DOI: 10.26443/msurj.v11i1.164
Jesse Mendoza, Francis N. Grafton, Amy Shan Wong, K. Cullen
Background: The α-9/10 nicotinic acetylcholine receptor is known to be the primary channel through which both vestibular and auditory efferents mediate the inhibition of their respective peripheral hair cells and afferents. With respect to the auditory system, the deletion of the α-9 subunit results in abnormalities in the development of properly functioning cochlear hair cells. Given the high degree of similarity between the au- ditory and the vestibular systems, we hypothesize that α-9 knockout mice should have impaired vestibular hair cell development and consequently compromised vestibular-mediated functions. Methods: In order to characterize vestibular function in α-9 knockout alert mice, we quantified the vestibu- lo-ocular reflex (VOR) through both gain and phase. Additionally, the optokinetic nystagmus (OKN) was sim- ilarly assessed as a control. VOR in light (VORl) was also quantified to further evaluate VOR and OKN efficacy. Furthermore, as information from the vestibular system mediates postural regulation and head stabilization, we assessed these properties through rotor rod and balance beam paradigms. Results: Surprisingly, the loss of the α-9 subunit in knockout mice did not result in any attenuation in VOR gain nor deviations in phase compared to wild type. OKN and VORl’s gain and phase values remain similarly unchanged, confirming preserved function within the vestibular nucleus. Descending vestibulospinal infor- mation seems to be unaltered as well, as no significant difference was observed in postural testing. Limitations: The α-9 knockout mice used specifically had exon 1 and exon 2 of the α-9 gene targeted, which could potentially limit generalizability. Also, frequencies greater than 3Hz were not tested. Conclusions: Our findings demonstrate that α-9 knockout mice still maintain normal vestibular function.
背景:α-9/10烟碱乙酰胆碱受体被认为是前庭和听觉传出神经调节其周围毛细胞和传入神经抑制的主要通道。就听觉系统而言，α-9亚基的缺失导致功能正常的耳蜗毛细胞发育异常。鉴于听觉和前庭系统之间的高度相似性，我们假设α-9基因敲除小鼠可能会损害前庭毛细胞的发育，从而损害前庭介导的功能。方法:对α-9基因敲除警觉性小鼠的前庭功能，采用增益法和相法定量测定前庭-眼反射(VOR)。此外，视力性眼球震颤(OKN)作为对照进行了类似的评估。同时对VOR in light (VORl)进行量化，进一步评价VOR和OKN的疗效。此外，由于来自前庭系统的信息介导姿势调节和头部稳定，我们通过转子杆和平衡木范式评估了这些特性。结果:令人惊讶的是，与野生型相比，敲除小鼠α-9亚基的缺失并未导致VOR增益的衰减或相位偏差。OKN和VORl的增益和相位值相似地保持不变，证实了前庭核内保留的功能。降前庭脊髓信息似乎也没有改变，因为在姿势测试中没有观察到显著的差异。局限性:α-9基因敲除小鼠特异性靶向α-9基因的外显子1和外显子2，这可能会限制其普遍性。此外，没有测试大于3Hz的频率。结论:α-9基因敲除小鼠仍能维持正常的前庭功能。
{"title":"Preserved Vestibular Function in Mice with Loss of α-9 Subunit of the α-9/10 Nicotinic Acetylcholine Receptor (α-9/10 nAChR)","authors":"Jesse Mendoza, Francis N. Grafton, Amy Shan Wong, K. Cullen","doi":"10.26443/msurj.v11i1.164","DOIUrl":"https://doi.org/10.26443/msurj.v11i1.164","url":null,"abstract":"Background: The α-9/10 nicotinic acetylcholine receptor is known to be the primary channel through which both vestibular and auditory efferents mediate the inhibition of their respective peripheral hair cells and afferents. With respect to the auditory system, the deletion of the α-9 subunit results in abnormalities in the development of properly functioning cochlear hair cells. Given the high degree of similarity between the au- ditory and the vestibular systems, we hypothesize that α-9 knockout mice should have impaired vestibular hair cell development and consequently compromised vestibular-mediated functions. \u0000Methods: In order to characterize vestibular function in α-9 knockout alert mice, we quantified the vestibu- lo-ocular reflex (VOR) through both gain and phase. Additionally, the optokinetic nystagmus (OKN) was sim- ilarly assessed as a control. VOR in light (VORl) was also quantified to further evaluate VOR and OKN efficacy. Furthermore, as information from the vestibular system mediates postural regulation and head stabilization, we assessed these properties through rotor rod and balance beam paradigms. \u0000Results: Surprisingly, the loss of the α-9 subunit in knockout mice did not result in any attenuation in VOR gain nor deviations in phase compared to wild type. OKN and VORl’s gain and phase values remain similarly unchanged, confirming preserved function within the vestibular nucleus. Descending vestibulospinal infor- mation seems to be unaltered as well, as no significant difference was observed in postural testing. \u0000Limitations: The α-9 knockout mice used specifically had exon 1 and exon 2 of the α-9 gene targeted, which could potentially limit generalizability. Also, frequencies greater than 3Hz were not tested. \u0000Conclusions: Our findings demonstrate that α-9 knockout mice still maintain normal vestibular function.","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-04-13DOI: 10.26443/msurj.v11i1.169
Janna R. Shapiro
Background: The 2013-2015 Ebola outbreak caused severe human suffering and a global health crisis. Ebola Virus (EBOV) is a naturally zoonotic RNA virus that has several immune-evasion mechanisms and can cause serious disease and death in humans. The massive impact of the recent epidemic is unique in the 40-year history of this pathogen. Scientists and public health officials around the world are researching the factors that may have contributed to the scale and devastating nature of the 2013-2015 outbreak. Methods: Terms searched online through the McGill library and Medline Ovid included “Ebola”, “immune evasion”, “sequencing”, “Ebola glycoprotein” and “zoonotic transmission”. Only articles published since 2014 were selected. Summary: In this review article, we will provide discussion on the principal factors contributing to the un- usually destructive nature of the 2013-2015 Ebola outbreak. Interestingly, although several nonsynony- mous mutations have been observed in the recently circulating strains, they were not the principal cause of the unusually devastating nature of the outbreak. Instead, the high rate of transmission was likely caused by sociological factors, such as population dynamics and late detection of the outbreak. However, there is evidence to suggest that once the high rate of transmission in humans was established there was selective pressure on the virus to evade the human immune system. This selective pressure may have exacerbated an already deadly outbreak. Ongoing research efforts indicate that there is still much to be discovered about the virus and the control of outbreak management.
{"title":"Understanding the 2013-2015 Ebola Outbreak","authors":"Janna R. Shapiro","doi":"10.26443/msurj.v11i1.169","DOIUrl":"https://doi.org/10.26443/msurj.v11i1.169","url":null,"abstract":"Background: The 2013-2015 Ebola outbreak caused severe human suffering and a global health crisis. Ebola Virus (EBOV) is a naturally zoonotic RNA virus that has several immune-evasion mechanisms and can cause serious disease and death in humans. The massive impact of the recent epidemic is unique in the 40-year history of this pathogen. Scientists and public health officials around the world are researching the factors that may have contributed to the scale and devastating nature of the 2013-2015 outbreak. \u0000Methods: Terms searched online through the McGill library and Medline Ovid included “Ebola”, “immune evasion”, “sequencing”, “Ebola glycoprotein” and “zoonotic transmission”. Only articles published since 2014 were selected. \u0000Summary: In this review article, we will provide discussion on the principal factors contributing to the un- usually destructive nature of the 2013-2015 Ebola outbreak. Interestingly, although several nonsynony- mous mutations have been observed in the recently circulating strains, they were not the principal cause of the unusually devastating nature of the outbreak. Instead, the high rate of transmission was likely caused by sociological factors, such as population dynamics and late detection of the outbreak. However, there is evidence to suggest that once the high rate of transmission in humans was established there was selective pressure on the virus to evade the human immune system. This selective pressure may have exacerbated an already deadly outbreak. Ongoing research efforts indicate that there is still much to be discovered about the virus and the control of outbreak management.","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-03-31DOI: 10.26443/msurj.v10i1.119
Zhihong Zhang, E. Pérez, A. Chinn, J. Davies
Background: American beech trees (Fagus gandifolia) exist in many areas in northeastern North America. Beech bark disease (BBD) is caused by a scale insect and bark-killing fungus (Cryptococcus fagisuga and Nectria spp.). We aim to study the correlation between diversity and the presence of BBD, and predict that tree diversity in Gault’s Nature Reserve in Mont St-Hilaire (MSH), Québec decreases the presence of BBD and that F. grandifolia density would increase the presence of this disease. Methods: We randomly chose 15 sites for sampling of individual tree species. F. grandifolia trees were identified as “healthy” or “infected”. Simple regressions, ANOVA, two and three-way interaction, linear mix effect model, and paired t-test were performed using R and Excel. Results: Our results show no significant correlation of infected individuals and total number of either A. saccharum or A. pensylvanica, unless analyzed with a linear mixed effect model (p=0.0256). However, there was a strong, positive correlation between the number of infected trees and the density of F. grandifolia (R2=0.6712), and this relationship was stronger in disturbed areas compared to undisturbed areas in the reserve (t=2.0492, p=0.047, tcritical=2.0211). Conclusion: We found beech tree density and habitat disturbance, but not community diversity, to have a significant positive effect on Beech Bark Disease infection rates.
{"title":"Tree Diversity has Limited Effects on Beech Bark Disease Incidence in American Beech Population of Mont St-Hilaire","authors":"Zhihong Zhang, E. Pérez, A. Chinn, J. Davies","doi":"10.26443/msurj.v10i1.119","DOIUrl":"https://doi.org/10.26443/msurj.v10i1.119","url":null,"abstract":"\u0000 \u0000 \u0000 \u0000Background: American beech trees (Fagus gandifolia) exist in many areas in northeastern North America. Beech bark disease (BBD) is caused by a scale insect and bark-killing fungus (Cryptococcus fagisuga and Nectria spp.). We aim to study the correlation between diversity and the presence of BBD, and predict that tree diversity in Gault’s Nature Reserve in Mont St-Hilaire (MSH), Québec decreases the presence of BBD and that F. grandifolia density would increase the presence of this disease. \u0000Methods: We randomly chose 15 sites for sampling of individual tree species. F. grandifolia trees were identified as “healthy” or “infected”. Simple regressions, ANOVA, two and three-way interaction, linear mix effect model, and paired t-test were performed using R and Excel. \u0000Results: Our results show no significant correlation of infected individuals and total number of either A. saccharum or A. pensylvanica, unless analyzed with a linear mixed effect model (p=0.0256). However, there was a strong, positive correlation between the number of infected trees and the density of F. grandifolia (R2=0.6712), and this relationship was stronger in disturbed areas compared to undisturbed areas in the reserve (t=2.0492, p=0.047, tcritical=2.0211). \u0000Conclusion: We found beech tree density and habitat disturbance, but not community diversity, to have a significant positive effect on Beech Bark Disease infection rates. \u0000 \u0000 \u0000 \u0000","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-03-31DOI: 10.26443/msurj.v10i1.121
M. Festa
Background: Depending on their path of differentiation, immune cells can have opposing roles in tumour progression. As a result, during growth, tumours undergo selective pressure to produce immunosuppressive factors that contribute to tumour growth, angiogenesis, and metastasis. This review discusses the contribution of different macrophages and T cells to tumour progression, as well as their role in current cancer immunotherapies. Methods: We searched for articles online through McGill Library with search terms including the names of different immune cells along with “polarity”, “tumour progression”, or “cancer immunotherapy”. Cancer therapies “CTLA-4 blockade”, “Ipilimumab”, “adoptive cell transfer”, and “PD1 inhibition” were also used as search terms. Summary: Depending on the cell types involved, crosstalk between different immune cells in the tumour stroma can contribute to either the development or the inhibition of tumour growth. Certain therapies such as adoptive cytotoxic T lymphocyte (CTLs) transfer and CTLA-4 & PD1 inhibition work by enhancing CTL tumoricidal responses, and have produced durable responses in a small but significant group of patients. Other therapies work by skewing the phenotype of tumour associated macrophages from pro-tumorigenic to anti-tumorigenic. However, disrupting the balance between immune cell functions risks triggering inflammatory disorders such as autoimmunity. Therefore, future directions in cancer immunotherapy include targeting potential responders and restricting therapeutic mechanisms to the tumour microenvironment.
{"title":"Immune Response Regulation has Therapeutic Potential in the Treatment of Cancer","authors":"M. Festa","doi":"10.26443/msurj.v10i1.121","DOIUrl":"https://doi.org/10.26443/msurj.v10i1.121","url":null,"abstract":"\u0000 \u0000 \u0000 \u0000Background: Depending on their path of differentiation, immune cells can have opposing roles in tumour progression. As a result, during growth, tumours undergo selective pressure to produce immunosuppressive factors that contribute to tumour growth, angiogenesis, and metastasis. This review discusses the contribution of different macrophages and T cells to tumour progression, as well as their role in current cancer immunotherapies. \u0000Methods: We searched for articles online through McGill Library with search terms including the names of different immune cells along with “polarity”, “tumour progression”, or “cancer immunotherapy”. Cancer therapies “CTLA-4 blockade”, “Ipilimumab”, “adoptive cell transfer”, and “PD1 inhibition” were also used as search terms. \u0000Summary: Depending on the cell types involved, crosstalk between different immune cells in the tumour stroma can contribute to either the development or the inhibition of tumour growth. Certain therapies such as adoptive cytotoxic T lymphocyte (CTLs) transfer and CTLA-4 & PD1 inhibition work by enhancing CTL tumoricidal responses, and have produced durable responses in a small but significant group of patients. Other therapies work by skewing the phenotype of tumour associated macrophages from pro-tumorigenic to anti-tumorigenic. However, disrupting the balance between immune cell functions risks triggering inflammatory disorders such as autoimmunity. Therefore, future directions in cancer immunotherapy include targeting potential responders and restricting therapeutic mechanisms to the tumour microenvironment. \u0000 \u0000 \u0000 \u0000","PeriodicalId":91927,"journal":{"name":"McGill Science undergraduate research journal : MSURJ","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69323300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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