RSS 1.0Biological Sciences
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Characterization of neutral sphingomyelinase activity and isoform expression in rodent skeletal muscle mitochondriaSkeletal muscle is composed of fiber types that differ in mitochondrial content, antioxidant capacity, and susceptibility to apoptosis. Ceramides have been linked to oxidative stress-mediated apoptotic intracellular signalling and the enzyme neutral sphingomyelinase (nSMase) is, in part, responsible for generating these ceramides through the hydrolysis of sphingomyelin. Despite the role of ceramides in mediating apoptosis, there is a gap in the literature regarding nSMase in skeletal muscle mitochondria. This study aimed to characterize total nSMase activity and individual isoform expression in isolated subsarcolemmal (SS) mitochondria from soleus, diaphragm, plantaris, and extensor digitorum longus (EDL). Total nSMase activity did not differ between muscle types. nSMase2 content was detectable in all muscles and higher in EDL, soleus, and plantaris compared to diaphragm whereas nSMase3 was undetectable in all muscles. Finally, total nSMase activity positively correlated to nSMase2 protein content in soleus but not the other muscles.These findings suggest that nSMase associated with SS mitochondria may play a role in intracellular signalling processes involving ceramides in skeletal muscle and nSMase2 may be the key isoform, specifically in slow twitch muscle like soleus. Further studies are needed to fully elucidate the specific contribution of nSMase, along with the role of the various isoforms and mitochondrial subpopulation in generating mitochondrial ceramides in skeletal muscle, and its potential effects on mediating apoptosis.
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Imaginer le futur de la mobilisation des connaissancesLa Commission canadienne pour l’UNESCO (CCUNESCO) et le Conseil de recherches en sciences humaines (CRSH) partagent un engagement profond envers le soutien à la production et l’accès à un savoir diversifié et inclusif au profit des générations actuelles et futures. Nous reconnaissons l’importance de lier la recherche aux problèmes mondiaux urgents. Nous avons l’occasion de travailler ensemble pour s’assurer que les résultats de la recherche aient un maximum d’impact, tout en tenant compte des divers systèmes de pensées. Assurer une mobilisation efficace des connaissances est incontournable pour répondre aux défis auxquels notre monde est confronté.
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Is Science a Human Right? Implementing the Principle of Participatory, Equitable, and Universally Accessible ScienceThe right of every human being to have access to scientific knowledge and participate in its development (also called “the right to science”) is enshrined in Article 27.1 of the Universal Declaration of Human Rights, adopted by the United Nations General Assembly on December 10, 1948. This article stipulates that: “Everyone has the right freely to participate in the cultural life of the community, to enjoy the arts and to share in scientific advancement and its benefits.” In 1966, the right to science was included in Article 15 of the International Covenant on Economic, Social and Cultural Rights, which called on the States Parties to “recognize the right of everyone to enjoy the benefits of scientific progress and its applications” and take the necessary steps for “the conservation, the development and the diffusion of science.”
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Pursuing Excellence in Research Reflections from UNESCO Research Chairs in CanadaAssessing or even just defining what excellence in research means can become a monumental task that can lead to frustration. The main reason is that research can take many forms depending on the discipline in which a scientist is working. In this reflection paper, we discuss the potential principles that could be applied when thinking about excellence in research in the context of academic advancement and resourcing. We acknowledge that there are many variants of the term and trying to add a strict framework may lead to discrimination against not only some disciplines but also cultures, as research has a social component that should not be forgotten.
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Vitellogenin expression corresponds with reproductive status and caste in a primitively eusocial bee, Lasioglossum laevissimumVitellogenin (vg) expression is consistently associated with variation in insect phenotypes, particularly egg-laying. Primitively eusocial species, such as eusocial sweat bees, have behaviourally totipotent castes, in which each female is capable of high levels of ovarian development. Few studies have investigated vg expression patterns in primitively eusocial insects, and only one study has focused on a primitively eusocial bee. Here we use a primitively eusocial sweat bee, Lasioglossum laevissimum, and Real Time quantitative PCR (RT-qPCR) to investigate the relationship between vg expression, castes, and variation in phenotypes associated with castes differences. These assays showed that females with high ovarian development had the highest levels of vg expression, and that vg expression levels reflected the reproductive status of females first and caste second. This is in contrast to vg expression patterns observed in advanced eusocial queens and workers, which differ in vg expression based on caste and have caste-specific vg expression patterns. Furthermore, future queens (gynes) do not have ovarian development and had similar vg expression levels to early spring foundresses, which do have ovarian development, supporting Vg’s function as a transporter of lipids and amino acids before diapause.
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Variation among 532 genomes unveils the origin and evolutionary history of a global insect herbivoreThe diamondback moth, Plutella xylostella is a cosmopolitan pest that has evolved resistance to all classes of insecticide, and costs the world economy an estimated US $4-5 billion annually. We analyse patterns of variation among 532 P. xylostella genomes, representing a worldwide sample of 114 populations. We find evidence that suggests South America is the geographical area of origin of this species, challenging earlier hypotheses of an Old-World origin. Our analysis indicates that Plutella xylostella has experienced three major expansions across the world, mainly facilitated by European colonization and global trade. We identify genomic signatures of selection in genes related to metabolic and signaling pathways that could be evidence of environmental adaptation. This evolutionary history of P. xylostella provides insights into transoceanic movements that have enabled it to become a worldwide pest.
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Strengthening our connection to nature and building citizens of the EarthThe authors elaborate on the dangers of rampant consumerism and attempt to explain why most humans are disconnected from the realities of our depleting planet and are not taking action to instigate change to ensure a more sustainable future. They argue that education for sustainable development will play a key role in transforming citizens of this Earth to assume fully their roles as environmental stewards.
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Activity analysis of thermal imaging videos using a difference imaging approachInfrared thermal imaging is a passive imaging technique that captures the emitted radiation from an object to estimate surface temperature, often for inference of heat transfer. Infrared thermal imaging offers the potential to detect movement without the challenges of glare, shadows, or changes in lighting associated with visual digital imaging or active infrared imaging. In this paper, we employ a frame subtraction algorithm for extracting the pixel-by-pixel relative change in signal from a fixed focus video file, tailored for use with thermal imaging videos. By summing the absolute differences across an entire video, we are able to assign quantitative activity assessments to thermal imaging data for comparison with simultaneous recordings of metabolic rates. We tested the accuracy and limits of this approach by analyzing movement of a metronome and provide an example application of the approach to a study of Darwin's finches. In principle, this “Difference Imaging Thermography” (DIT) would allow for activity data to be standardized to energetic measurements and could be applied to any radiometric imaging system.
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Thermal Imaging and Physiological Analysis of Cold-Climate Caribou-Skin ClothingProtective clothing is essential for human existence in the Arctic, and caribou-skin clothing has played a pivotal role for millennia. Although people with northern experience often extol caribou-skin clothing, few scientific studies have investigated its properties. We used infrared thermal imaging in a pilot study to compare authentic caribou-skin clothing sewn by traditional Inuit seamstresses with two other types of cold-weather clothing: a standard-issue, Canadian army, winter uniform and an ensemble of modern retail clothing designed for extreme cold (a down anorak and snowmobile pants). To make the comparison, two subjects sequentially wore the three types of clothing—caribou skin, army uniform, and modern retail—in a still air, uniform thermal environment (where radiant temperatures of all environmental surfaces were equal to air temperature) at −21°C to −23°C (−6°F to −10°F). Thermal imaging quantifies the temperature of the outer surface of clothing, thereby providing key, functionally relevant information on the interface where clothing and environment meet. Under otherwise similar conditions, a low clothing surface temperature indicates superior clothing performance and a reduced rate of heat loss from the body to the environment. Caribou-skin clothing was similar to modern extreme-cold retail clothing: the whole-body composite surface temperature of our subjects wearing caribou-skin clothing was −22.1°C to −22.7°C, compared with −21.6°C in both subjects wearing the modern retail clothing. The army winter uniform (−18.9°C to −20.0°C) was inferior. These quantitative results were mirrored by the subjects’ subjective impressions. A particular advantage of thermal imaging is that it pinpoints locations in clothing where heat leaks occur. Although the two types of modern clothing exhibited heat leaks at zippered structures (even though fully closed), the caribou-skin clothing evaded such heat leaks by lacking such structures, because it is donned over the head. The integral hood characteristic of a caribou-skin parka was also superior in comparison to the detachable hood of the army uniform.
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Development of homeothermic endothermy is delayed in high-altitude native deer mice (Peromyscus maniculatus)Altricial mammals begin to independently thermoregulate during the firstfew weeks of postnatal development. In wild rodent populations, this isalso a time of high mortality (50–95%), making the physiological systemsthat mature during this period potential targets for selection. High altitude(HA) is a particularly challenging environment for small endotherms owingto unremitting low O2and ambient temperatures. While superior thermo-genic capacities have been demonstrated in adults of some HA species, itis unclear if selection has occurred to survive these unique challengesearly in development. We used deer mice (Peromyscus maniculatus) nativeto high and low altitude (LA), and a strictly LA species (Peromyscus leucopus),raised under common garden conditions, to determine if postnatal onset ofendothermy and maturation of brown adipose tissue (BAT) is affected byaltitude ancestry. We found that the onset of endothermy correspondswith the maturation and activation of BAT at an equivalent age in LAnatives, with 10-day-old pups able to thermoregulate in response to acutecold in both species. However, the onset of endothermy in HA pups wassubstantially delayed (by approx. 2 days), possibly driven by delayedsympathetic regulation of BAT. We suggest that this delay may be part ofan evolved cost-saving measure to allow pups to maintain growth ratesunder the O2-limited conditions at HA.
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A Long-Term Study on Massasaugas (Sistrurus catenatus) Inhabiting a Partially Mined Peatland: A Standardized Method to Characterize Snake Overwintering HabitatTemperate snakes occupy overwintering sites for most of their annual life cycle. Microhabitat characteristics of the hibernaculum are largely undescribed, yet are paramount in ensuring snake overwintering survival. We hypothesized that snakes survive hibernation within a vertical subterranean space that we termed a “life zone” (LZ), that is aerobic and flood and frost free throughout winter. We studied an isolated, endangered population of Massasaugas (Sistrurus catenatus) inhabiting an anthropogenically altered peatland and monitored the subterranean habitat during a period of environmental stochasticity. Initial radio telemetry confirmed that snakes moved between altered and natural habitats during the active season and showed hibernation-site fidelity to either habitat. We used a grid of groundwater wells and frost tubes installed in each hibernation area to measure LZ characteristics over 11 consecutive winters. The LZ within the impacted area was periodically reduced to zero during a flood–freeze cycle, but the LZ in the natural area was maintained. Model selection analysis revealed that soil depth and flood status best predicted LZ size. Thermal buffering and groundwater dissolved oxygen increased with LZ size, and annual Massasauga encounters were significantly correlated with LZ size. This analysis suggests a population decline occurred when LZ size was reduced by flooding. Our data give support to the importance and maintenance of an LZ for successful snake hibernation. Our methods apply to subterranean hibernation habitats that are at risk of environmental stochasticity, causing flooding, freezing, or hypoxia.
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Molecular Characterization and the Function of Argonaute3 in RNAi Pathway of Plutella xylostellaArgonaute (Ago) protein family plays a key role in the RNA interference (RNAi) process in different insects including Lepidopteran. However, the role of Ago proteins in the RNAi pathway of Plutella xylostella is still unknown. We cloned an Argonaute3 gene in P. xylostella ( PxAgo3 ) with the complete coding sequence of 2832 bp. The encoded protein had 935 amino acids with an expected molecular weight of 108.9 kDa and an isoelectric point of 9.29. It contained a PAZ (PIWI/Argonaute/Zwile) domain and PIWI (P-element-induced whimpy testes) domain. PxAgo3 was classified into the Piwi subfamily of Ago proteins with a high similarity of 93.0% with Bombyx mori Ago3 (BmAgo3). The suppression of PxAgo3 by dsPxAgo3 was observed 3 h after treatment and was maintained until 24 h. Knockdown of PxAgo3 decreased the suppression level of PxActin by dsPxActin in P. xylostella cells, while overexpression of PxAgo3 increased the RNAi efficiency. Our results suggest that PxAgo3 play a key role in the double stranded RNA (dsRNA)-regulated RNAi pathway in P. xylostella .
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Use of biological control against arthropod pests in Canadian greenhouse crop productionGreenhouse horticultural production currently represents an important and growing sector of Canada's food and plant production systems. Since 2006, the value of greenhouse vegetable crops in Canada exceeds that of field grown crops, signaling an important shift in the way food is cultivated in the country. While many factors have contributed to this change, a major area of innovation includes the discoveries and advances made in the development of commercial greenhouse production systems as well as the integration of biological control strategies for sustainable pest management. With this focus, this review offers a brief overview of the Canadian greenhouse industry, including a descriptive list of commonly used biological control organisms, as well as the role Canadian research has played in the development of these agents. We also address the threats that Canadian greenhouse producers face by invasive pests and the complications these have created for the commercialization of novel biological control agents. This information may serve as a guide for the development of parallel technologies and tools in other parts of the world where greenhouse production is expanding.
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CRISPR/Cas9-Mediated Vitellogenin Receptor Knockout Leads to Functional Deficiency in the Reproductive Development of Plutella xylostellaThe vitellogenin receptor (VgR) belongs to the low-density lipoprotein receptor (LDLR) gene superfamily and plays an indispensable role in Vg transport, yolk deposition, and oocyte development. For this reason, it has become a promising target for pest control. The involvement of VgR in Vg transport and reproductive functions remains unclear in diamondback moths, Plutella xylostella (L.), a destructive pest of cruciferous crops. Here, we cloned and identified the complete cDNA sequence of P. xylostella VgR, which encoded 1805 amino acid residues and contained four conserved domains of LDLR superfamily. PxVgR was mainly expressed in female adults, more specifically in the ovary. PxVgR protein also showed the similar expression profile with the PxVgR transcript. CRISPR/Cas9-mediated PxVgR knockout created a homozygous mutant of P. xylostella with 5-bp-nucleotide deletion in the PxVgR. The expression deficiency of PxVgR protein was detected in the ovaries and eggs of mutant individuals. Vg protein was still detected in the eggs of the mutant individuals, but with a decreased expression level. However, PxVg transcripts were not significantly affected by the PxVgR knockout. Knockout of PxVgR resulted in shorter ovarioles of newly emerged females. No significant difference was detected between wild and mutant individuals in terms of the number of eggs laid in the first 3 days after mating. The loss of PxVgR gene resulted in smaller and whiter eggs and lower egg hatching rate. This study represents the first report on the functions of VgR in Vg transport, ovary development, oviposition, and embryonic development of P. xylostella using CRISPR/Cas9 technology. This study lays the foundation for understanding molecular mechanisms of P. xylostella reproduction, and for making use of VgR as a potential genetic-based molecular target for better control of the P. xylostella.
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Gut Microbiota Mediate Insecticide Resistance in the Diamondback Moth, Plutella xylostella (L.)The development of insecticide resistance in insect pests is a worldwide concern and elucidating the underlying mechanisms is critical for effective crop protection. Recent studies have indicated potential links between insect gut microbiota and insecticide resistance and these may apply to the diamondback moth, Plutella xylostella (L.), a globally and economically important pest of cruciferous crops. We isolated Enterococcus sp. (Firmicutes), Enterobacter sp. (Proteobacteria), and Serratia sp. (Proteobacteria) from the guts of P. xylostella and analyzed the effects on, and underlying mechanisms of insecticide resistance. Enterococcus sp. enhanced resistance to the widely used insecticide, chlorpyrifos, in P. xylostella, while in contrast, Serratia sp. decreased resistance and Enterobacter sp. and all strains of heat-killed bacteria had no effect. Importantly, the direct degradation of chlorpyrifos in vitro was consistent among the three strains of bacteria. We found that Enterococcus sp., vitamin C, and acetylsalicylic acid enhanced insecticide resistance in P. xylostella and had similar effects on expression of P. xylostella antimicrobial peptides. Expression of cecropin was down-regulated by the two compounds, while gloverin was up-regulated. Bacteria that were not associated with insecticide resistance induced contrasting gene expression profiles to Enterococcus sp. and the compounds. Our studies confirmed that gut bacteria play an important role in P. xylostella insecticide resistance, but the main mechanism is not direct detoxification of insecticides by gut bacteria. We also suggest that the influence of gut bacteria on insecticide resistance may depend on effects on the immune system. Our work advances understanding of the evolution of insecticide resistance in this key pest and highlights directions for research into insecticide resistance in other insect pest species.
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Identification of Halloween Genes and RNA Interference-Mediated Functional Characterization of a Halloween Gene shadow in Plutella xylostellaEcdysteroids play an essential role in controlling insect development and reproduction. Their pathway is regulated by a group of enzymes called Halloween gene proteins. The relationship between the Halloween genes and ecdysteroid synthesis has yet to be clearly understood in diamondback moth, Plutella xylostella (L.), a worldwide Lepidoptera pest attacking cruciferous crops and wild plants. In this study, complete sequences for six Halloween genes, neverland ( nvd ), shroud ( sro ), spook ( spo ), phantom ( phm ), disembodied ( dib ), shadow ( sad ), and shade ( shd ), were identified. Phylogenetic analysis revealed a strong conservation in insects, including Halloween genes of P. xylostella that was clustered with all other Lepidoptera species. Three Halloween genes, dib , sad , and shd were highly expressed in the adult stage, while nvd and spo were highly expressed in the egg and pupal stages, respectively. Five Halloween genes were highly expressed specifically in the prothorax, which is the major site of ecdysone production. However, shd was expressed predominantly in the fat body to convert ecdysone into 20-hydroxyecdysone. RNAi-based knockdown of sad , which is involved in the last step of ecdysone biosynthesis, significantly reduced the 20E titer and resulted in a longer developmental duration and lower pupation of fourth-instar larvae, as well as caused shorter ovarioles and fewer fully developed eggs of P. xylostella . Furthermore, after the knockdown of sad , the expression levels of Vg and VgR genes were significantly decreased by 77.1 and 53.0%. Meanwhile, the number of eggs laid after 3 days was significantly reduced in sad knockdown females. These results suggest that Halloween genes may play a critical role in the biosynthesis of ecdysteroids and be involved in the development and reproduction of P. xylostella . Our work provides a solid basis for understanding the functional importance of these genes, which will help to screening potential genes for pest management of P. xylostella.
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Impacts of Smooth Pigweed (Amaranthus hybridus) on Cover Crops in Southern OntarioAmaranthushybridus is anoxious weed in Ontario, with demonstrated allelopathic properties that can lead to decreased agricultural production. We tested the germination and growth of five cover crop species exposed to A. hybridus extracts, and to dried or fresh materials in soil. A germination index was calculated, and the dry weight of plant organs were measured to quantify responses to treatments. All species had reduced germination (≤29%) in 100% extract. Trifolium pratense had significant root weight reductions in extract (52%) and dried (72%) treatments, whereas shoot weight only decreased (48%) in dried treatment. Medicagosativa shoot weight decreased (52%) in 20g fresh treatment, while root weight decreased (62%) in dried treatment. Shoot weight of Raphanus sativus increased (32%) at mid-extract concentrations, while root weight increased (33%) only with dried treatment; however, both its shoot and root weight decreased (>40%) in fresh treatment. Only the shoot weight of Loliummultiflorum increased (41% in 75% extract and 55% in dried treatment). Both Cichorium intybus shoot and root weights decreased (~50%) in fresh treatment. Crop responses to A. hybridus are complex, and material and species-dependant. Further testing in the field may provide a more comprehensive understanding of how to improve the management of A. hybridus.
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Investigating queen influence on worker behaviour using comparisons of queenless and queenright workers (Supplimentary Material)Female eusocial sweat bees are capable of behaving as queens or workers. Relatively few females become queens, and those that do can directly manipulate the reproductive behaviour of other females in the nest. We collected Lasioglossum (Dialictus) laevissimum workers from nests with and without queens (queenright and queenless nests, respectively) to investigate the influence queens exert on worker behaviour via direct manipulation. Overall, very few L. laevissimum workers (17%) had developed ovaries in Ontario, but queenright and queenless workers were equally likely to have developed ovaries and worn mandibles. However, queenless workers were more likely to be mated than queenright workers. These results suggest first, that queens inhibit egg-laying in most, but not all workers, and second, that queen behaviour during the first few days of workers’ adult lives exerts a lasting influence on worker behaviour. We also compared social traits of L. laevissimum and other Dialictus species using principal components analysis. A strong correlation between worker reproduction and male availability suggests that queen manipulation of the worker brood sex ratio has evolved as an indirect mechanism for queens to discourage worker reproduction. This item is the data set used to produce this study.
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Evaporative cooling and vasodilation mediate thermoregulation in naked mole-rats during normoxia but not hypoxiaNaked mole-rats are among the most hypoxia-tolerant mammals but have a poor thermoregulatory capacity due to their lack of insulating fur and fat, and small body size. In acute hypoxia, naked mole-rat body temperature (Tb) decreases to ambient temperature (Ta) but the mechanisms that underlie this thermoregulatory response are unknown. We hypothesized 1) that naked mole-rat blood vessels vasodilate during hypoxia to shunt heat toward the body surface and/or 2) that they augment heat loss through evaporative cooling. Using open-flow re- spirometry (indirect calorimetry) we explored metabolic and thermoregulatory strategies of naked mole-rats exposed to hypoxia (7% O2 for 1 h) at two relative humidities (RH; 50 or 100% water saturation), and in two Ta's (25 and 30 °C), alone, and following treatment with the vasoconstrictor angiotensin II (ANGII). We found that Tb and metabolic rate decreased in hypoxia across all treatment groups but that neither RH nor ANGII effected either variable in hypoxia. Conversely, both Tb and metabolic rate were reduced in 100% RH or by ANGII treatment in normoxia at 25 °C, and therefore the absolute change in both variables with the onset of hypoxia was reduced when vasodilation or evaporative cooling were prevented. We conclude that naked mole-rats employ evaporative cooling and vasodilation to thermoregulate in normoxia and in 25 °C but that neither mechanism is involved in thermoregulatory changes during acute hypoxia. These findings suggest that NMRs may employ passive strategies such as reducing thermogenesis to reduce Tb in hypoxia, which would support metabolic rate suppression.
