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Steady gravity-capillary periodic waves on the surface of a thin viscous liquid film supported by an air stream on an inclined wall are investigated. Based on lubrication approximation and thin air-foil theory, this problem is reduced to an integro-differential equation. The small-amplitude analysis is carried out to obtain two analytical solutions up to the second order. Numerical computation shows there exist two distinct primary bifurcation branches starting from infinitesimal waves, which approach solitary wave configuration in the long-wave limit when the values of physical parameters are above certain thresholds. New families of solutions manifest themselves either as secondary bifurcation occurring on primary branches or as isolated solution branches. The limiting configurations of the primary solution branches with the increase of two parameters are studied in two different cases, where one and two limiting configurations are obtained, respectively. For the latter case, the approximation of the configurations is given. [ABSTRACT FROM AUTHOR]

Two-dimensional capillary–gravity waves travelling under the effect of a vertical electric field are considered. The fluid is assumed to be a dielectric of infinite depth. It is bounded above by another fluid which is hydrodynamically passive and perfectly conducting. The problem is solved numerically by time-dependent conformal mapping methods. Fully nonlinear waves are presented, and their stability and dynamics are studied. [ABSTRACT FROM AUTHOR]

In this paper, fully nonlinear non-symmetric periodic gravity-capillary waves propagating at the surface of an inviscid and incompressible fluid are investigated. This problem was pioneered analytically by Zufiria (J. Fluid Mech., vol. 184, 1987c, pp. 183-206) and numerically by Shimizu & Shoji (Japan J. Ind. Appl. Maths, vol. 29 (2), 2012, pp. 331-353). We use a numerical method based on conformal mapping and series truncation to search for new solutions other than those shown in Zufiria (1987c) and Shimizu & Shoji (2012). It is found that, in the case of infinite-depth, non-symmetric waves with two to seven peaks within one wavelength exist and they all appear via symmetry-breaking bifurcations. Fully exploring these waves by changing the parameters yields the discovery of new types of non-symmetric solutions which form isolated branches without symmetry-breaking points. The existence of non-symmetric waves in water of finite depth is also confirmed, by using the value of the streamfunction at the bottom as the continuation parameter. [ABSTRACT FROM AUTHOR]

Hormones control developmental and physiological processes, often by regulating the expression of multiple genes simultaneously or sequentially. Crosstalk between hormones and epigenetics is pivotal to dynamically coordinate this process. Hormonal signals can guide the addition and removal of epigenetic marks, steering gene expression. Conversely, DNA methylation, histone modifications and non-coding RNAs can modulate regional chromatin structure and accessibility and regulate the expression of numerous (hormone-related) genes. Here, we provide a review of the interplay between the classical insect hormones, ecdysteroids and juvenile hormones, and epigenetics. We summarize the mode-of-action and roles of these hormones in post-embryonic development, and provide a general overview of epigenetic mechanisms. We then highlight recent advances on the interactions between these hormonal pathways and epigenetics, and their involvement in development. Furthermore, we give an overview of several 'omics techniques employed in the field. Finally, we discuss which questions remain unanswered and possible avenues for future research., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The digestive tract constitutes an important interface between an animal's internal and external environment. In insects, available gut transcriptome studies are mostly exploratory or look at changes upon infection or upon exposure to xenobiotics, mainly performed in species belonging to holometabolan orders, such as Diptera, Lepidoptera or Coleoptera. By contrast, studies focusing on gene expression changes after food uptake and during digestion are underrepresented. We have therefore compared the gene expression profiles in the midgut of the desert locust, Schistocerca gregaria , between three different time points after feeding, i.e., 24 h (no active digestion), 10 min (the initial stage of feeding), and 2 h (active food digestion). The observed gene expression profiles were consistent with the polyphagous herbivorous lifestyle of this hemimetabolan (orthopteran) species. Our study reveals the upregulation of 576 genes 2 h post-feeding. These are mostly predicted to be associated with digestive physiology, such as genes encoding putative digestive enzymes or nutrient transporters, as well as genes putatively involved in immunity or in xenobiotic metabolism. The 10 min time point represented an intermediate condition, suggesting that the S. gregaria midgut can react rapidly at the transcriptional level to the presence of food. Additionally, our study demonstrated the critical importance of two transcripts that exhibited a significant upregulation 2 h post-feeding: the vacuolar-type H(+)-ATPase and the sterol transporter Niemann-Pick 1b protein, which upon RNAi-induced knockdown resulted in a marked increase in mortality. Their vital role and accessibility via the midgut lumen may make the encoded proteins promising insecticidal target candidates, considering that the desert locust is infamous for its huge migrating swarms that can devastate the agricultural production in large areas of Northern Africa, the Middle East, and South Asia. In conclusion, the transcriptome datasets presented here will provide a useful and promising resource for studying the midgut physiology of S. gregaria , a socio-economically important pest species., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Van Lommel, Holtof, Tilleman, Cools, Vansteenkiste, Polgun, Verdonck, Van Nieuwerburgh and Vanden Broeck.)

RNA(i) interference is a gene silencing mechanism triggered by double-stranded (ds)RNA, which promises to contribute to species-specific insect pest control strategies. The first step toward the application of RNAi as an insecticide is to enable efficient gene silencing upon dsRNA oral delivery. The desert locust, Schistocerca gregaria is a devastating agricultural pest. While this species is responsive to dsRNA delivered by intra-hemocoelic injection, it is refractory to orally delivered dsRNA. In this study, we evaluated the capacity of five cell-penetrating peptides (CPPs) to bind long dsRNA and protect it from the locust midgut environment. We then selected the CPP EB1 for further in vivo studies. EB1:dsRNA complexes failed to induce RNAi by feeding. Interestingly, we observed that intra-hemocoelic injection of small-interfering (si)RNAs does not result in a silencing response, but that this response can be obtained by injecting EB1:siRNA complexes. EB1 also protected siRNAs from midgut degradation activity. However, EB1:siRNA complexes failed as well in triggering RNAi when fed. Our findings highlight the complexity of the dsRNA/siRNA-triggered RNAi in this species and emphasize the multifactorial nature of the RNAi response in insects. Our study also stresses the importance of in vivo studies when it comes to dsRNA/siRNA delivery systems.

Insect cell expression systems are increasingly being used in the medical industry to develop vaccines against diseases such as COVID-19. However, viral infections are common in these systems, making it necessary to thoroughly characterize the viruses present. One such virus is Bombyx mori latent virus (BmLV), which is known to be specific to Bombyx mori and to have low pathogenicity. However, there has been little research on the tropism and virulence of BmLV. In this study, we examined the genomic diversity of BmLV and identified a variant that persistently infects Trichoplusia ni -derived High Five cells. We also assessed the pathogenicity of this variant and its effects on host responses using both in vivo and in vitro systems. Our results showed that this BmLV variant causes acute infections with strong cytopathic effects in both systems. Furthermore, we characterized the RNAi-based immune response in the T. ni cell line and in Helicoverpa armigera animals by assessing the regulation of RNAi-related genes and profiling the generated viral small RNAs. Overall, our findings shed light on the prevalence and infectious properties of BmLV. We also discuss the potential impact of virus genomic diversity on experimental outcomes, which can help interpret past and future research results.

Neuropeptides are important regulators of animal physiology and behavior. Hitherto the gold standard for the localization of neuropeptides have been immunohistochemical methods that require the synthesis of antibody panels, while another limiting factor has been the brain's opacity for subsequent in situ light or fluorescence microscopy. To address these limitations, we explored the integration of high-resolution mass spectrometry imaging (MSI) with microtomography for a multiplexed mapping of neuropeptides in two evolutionary distant ant species, Atta sexdens and Lasius niger . For analyzing the spatial distribution of chemically diverse peptide molecules across the brain in each species, the acquisition of serial mass spectrometry images was essential. As a result, we have comparatively mapped the three-dimensional (3D) distributions of eight conserved neuropeptides throughout the brain microanatomy. We demonstrate that integrating the 3D MSI data into high-resolution anatomy models can be critical for studying organs with high plasticity such as brains of social insects. Several peptides, like the tachykinin-related peptides (TK) 1 and 4, were widely distributed in many brain areas of both ant species, whereas others, for instance myosuppressin, were restricted to specific regions only. Also, we detected differences at the species level; many peptides were identified in the optic lobe of L. niger , but only one peptide (ITG-like) was found in this region in A. sexdens . Building upon MS imaging studies on neuropeptides in invertebrate model systems, our approach leverages correlative MSI and computed microtomography for investigating fundamental neurobiological processes by visualizing the unbiased 3D neurochemistry in its complex anatomic environment., (© The Author(s) 2023. Published by Oxford University Press on behalf of National Academy of Sciences.)

Objectives: This survey aims to assess the scope of transfusion e-learning courses in blood establishments and transfusion services internationally., Background: E-learning/online education is increasingly used in the education of medical professionals. There is limited published data on the use of e-learning for transfusion medicine., Material and Methods: An International survey was designed and distributed to all members of the International Society of Blood Transfusion to assess utilisation of e-learning in their institutions. Descriptive statistics were used to summarise the results., Results: A total of 177 respondents participated, 68 of which had e-learning modules in their institutions. Approximately two-thirds of the courses were developed in-house (66%), and 63% are available to learners from outside the host institutions. In one-third of institutions, these courses were established during the COVID-19 pandemic, while 15% had used e-learning courses for more than 10 years. The courses target different audiences and topics ranging from blood donation to hemovigilance. The most common audiences were physicians (71%), laboratory scientists/technologists (69%) and transfusion practitioners (63%). Formal assessment of learning outcomes is used in 70% of the programs., Conclusions: The survey demonstrates the widespread use of e-learning courses in transfusion education, with a substantial proportion being developed during the COVID-19 pandemic., (© 2022 British Blood Transfusion Society.)

Adaptive plasticity requires an integrated suite of functional responses to environmental variation, which can include social communication across life stages. Desert locusts ( Schistocerca gregaria ) exhibit an extreme example of phenotypic plasticity called phase polyphenism, in which a suite of behavioral and morphological traits differ according to local population density. Male and female juveniles developing at low population densities exhibit green- or sand-colored background-matching camouflage, while at high densities they show contrasting yellow and black aposematic patterning that deters predators. The predominant background colors of these phenotypes (green/sand/yellow) all depend on expression of the carotenoid-binding "Yellow Protein" ( YP ). Gregarious (high-density) adults of both sexes are initially pinkish, before a YP -mediated yellowing reoccurs upon sexual maturation. Yellow color is especially prominent in gregarious males, but the reason for this difference has been unknown since phase polyphenism was first described in 1921. Here, we use RNA interference to show that gregarious male yellowing acts as an intrasexual warning signal, which forms a multimodal signal with the antiaphrodisiac pheromone phenylacetonitrile (PAN) to prevent mistaken sexual harassment from other males during scramble mating in a swarm. Socially mediated reexpression of YP thus adaptively repurposes a juvenile signal that deters predators into an adult signal that deters undesirable mates. These findings reveal a previously underappreciated sexual dimension to locust phase polyphenism, and promote locusts as a model for investigating the relative contributions of natural versus sexual selection in the evolution of phenotypic plasticity.

Ecdysteroids are widely investigated for their role during the molting cascade in insects; however, they are also involved in the development of the female reproductive system. Ecdysteroids are synthesized from cholesterol, which is further converted via a series of enzymatic steps into the main molting hormone, 20-hydoxyecdysone. Most of these biosynthetic conversion steps involve the activity of cytochrome P450 (CYP) hydroxylases, which are encoded by the Halloween genes. Three of these genes, spook ( spo ), phantom ( phm ) and shade ( shd ), were previously characterized in the desert locust, Schistocerca gregaria . Based on recent sequencing data, we have now identified the sequences of disembodied ( dib ) and shadow ( sad ), for which we also analyzed spatiotemporal expression profiles using qRT-PCR. Furthermore, we investigated the possible role(s) of five different Halloween genes in the oogenesis process by means of RNA interference mediated knockdown experiments. Our results showed that depleting the expression of SchgrSpo , SchgrSad and SchgrShd had a significant impact on oocyte development, oviposition and hatching of the eggs. Moreover, the shape of the growing oocytes, as well as the deposited eggs, was very drastically altered by the experimental treatments. Consequently, it can be proposed that these three enzymes play an important role in oogenesis.

Insect antiviral immunity primarily relies on RNAi mechanisms. While a key role of small interfering (si)RNAs and AGO proteins has been well established in this regard, the situation for PIWI proteins and PIWI-interacting (pi)RNAs is not as clear. In the present study, we investigate whether PIWI proteins and viral piRNAs are involved in the immunity against single-stranded RNA viruses in lepidopteran cells, where two PIWIs are identified (Siwi and Ago3). Via loss- and gain-of-function studies in Bombyx mori BmN4 cells and in Trichoplusia ni High Five cells, we demonstrated an antiviral role of Siwi and Ago3. However, small RNA analysis suggests that viral piRNAs can be absent in these lepidopteran cells. Together with the current literature, our results support a functional diversification of PIWI proteins in insects.

Since the discovery of the first microRNA (miRNA) in the nematode Caenorhabditis elegans , numerous novel miRNAs have been identified which can regulate presumably every biological process in a wide range of metazoan species. In accordance, several insect miRNAs have been identified and functionally characterized. While regulatory RNA pathways are traditionally described at an intracellular level, studies reporting on the presence and potential role of extracellular (small) sRNAs have been emerging in the last decade, mainly in mammalian systems. Interestingly, evidence in several species indicates the functional transfer of extracellular RNAs between donor and recipient cells, illustrating RNA-based intercellular communication. In insects, however, reports on extracellular small RNAs are emerging but the number of detailed studies is still very limited. Here, we demonstrate the presence of stable sRNAs in the hemolymph of the migratory locust, Locusta migratoria . Moreover, the levels of several extracellular miRNAs (ex-miRNAs) present in locust hemolymph differed significantly between young and old fifth nymphal instars. In addition, we performed a 'proof of principle' experiment which suggested that extracellularly delivered miRNA molecules are capable of affecting the locusts' development., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Author(s).)

RNA interference (RNAi) is a highly conserved pathway for the post-transcriptional regulation of gene expression. It has become a crucial tool in life science research, with promising potential for pest-management applications. To induce an RNAi response, long double-stranded RNA (dsRNA) sequences specific to the target gene must be delivered to the cells. This dsRNA substrate is then processed to small RNA (sRNA) fragments that direct the silencing response. A major obstacle to applying this technique is the need to produce sufficiently large amounts of dsRNA in a very cost-effective manner. To overcome this issue, much attention has been given to the development and optimization of biological production systems. One such system is the E. coli HT115 strain transformed with the L4440 vector. While its effectiveness at inducing knockdowns in animals through feeding of the bacteria has been demonstrated, there is only limited knowledge on the applicability of bacteria-derived dsRNA for in vitro experiments. In this paper, we describe and compare methods for the economical (43.2 €/mg) and large-scale (mg range) production of high-quality dsRNA from the HT115 bacterial system. We transformed the bacteria with constructs targeting the Helicoverpa -specific gene Dicer2 and, as a non-endogenous control, the Green Fluorescent Protein gene ( GFP ). First, we compared the total RNA extraction yields of four cell-lysis treatments: heating, lysozyme digestion, sonication, and a control protocol. Second, we assessed the quality and purity of these extracted dsRNAs. Third, we compared methods for the further purification of dsRNAs from crude RNA extracts. Finally, we demonstrated the efficiency of the produced dsRNAs at inducing knockdowns in a lepidopteran cell line. The insights and results from this paper will empower researchers to conduct otherwise prohibitively expensive knockdown studies, and greatly reduce the production times of routinely or large-scale utilized dsRNA substrates., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Verdonckt and Vanden Broeck.)

Locusts have been known as pests of agricultural crops for thousands of years. Recently (2018-2021) the world has faced the largest swarms of desert locusts, Schistocerca gregaria, in decades and food security in large parts of Africa and Asia was under extreme pressure. There is an urgent need for the development of highly specific bio-rational pesticides to combat these pests. However, to do so, fundamental research is needed to better understand the molecular mechanisms behind key physiological processes underpinning swarm formation, such as development and reproduction. The scope of this study is to investigate the possible role(s) of the ecdysteroid receptor in the reproductive physiology of male S. gregaria. Ecdysteroids and juvenile hormones are two important classes of insect hormones and are key regulators of post-embryonic development. Ecdysteroids are best known for their role in moulting and exert their function via a heterodimer consisting of the nuclear receptors ecdysone receptor (EcR) and retinoid-X receptor (RXR). To gain insight into the role of SgEcR and/or SgRXR in the male reproductive physiology of S. gregaria we performed RNAi-induced knockdown experiments. A knockdown of SgEcR, but not SgRXR, resulted in an increased relative weight of the male accessory glands (MAG). Furthermore, the knockdown of these genes, either in combination or separately, caused a significant delay in the onset of mating behavior. Nevertheless, the MAG appeared to mature normally and the fertility of mated males was not affected. The high transcript levels of SgEcR in the fat body, especially towards the end of sexual maturation in both males and females, represent a remarkable finding since as of yet the exact role of SgEcR in this tissue in S. gregaria is unknown. Finally, our data suggest that in some cases SgEcR and SgRXR might act independently of each other. This is supported by the fact that the spatiotemporal expression profiles of SgEcR and SgRXR do not always coincide and that knockdown of SgEcR, but not SgRXR, significantly affected the relative weight of the MAG., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background and Objectives: Belgian health authorities launched a national platform in 2011 to improve the quality of transfusion practices and blood use in Belgian hospitals. No data were available about the quality of hospital transfusion practice at the national level., Materials and Methods: Three consecutive national surveys (2012, 2014 and 2016) were performed in all 111 Belgian hospitals to assess the degree of implementation of standards in four process domains related to red blood cell (RBC) transfusion: general quality aspects, ordering of RBC, electronic traceability and reporting of adverse events. The surveys were part of a methodology based on informing, feedback and benchmarking. Responses to questions were analysed semi-quantitatively, and hospitals could score 10 points on each of the domains., Results: The proportion of hospitals scoring below 5 per domain decreased from 16%, 70%, 14% and 11% (2012) to 2%, 17%, 1% and 1% (2016), respectively. Similarly, scores above 7.5 increased from 25%, 1%, 23% and 36% (2012) to 64%, 30%, 68% and 81% (2016), respectively. In 2016, overall quality of transfusion practices, including the four pre-specified domains, improved continuously with an average total score (max = 40) increasing from 24.2 to 30.5 (p = 0.0005). In addition, there was a decrease in the number of distributed and transfused RBC per 1000 population between 2011 and 2019 from 47.0 to 36.5 and 43.5 to 36.1, respectively., Conclusion: These data show that the applied methodology was a powerful tool to improve quality of transfusion practices and to optimize utilization of RBC at the national level., (© 2021 International Society of Blood Transfusion.)

We compiled a comprehensive list of 67 precursor genes encoding neuropeptides and neuropeptide-like peptides using the Schistocerca gregaria genome and several transcriptome datasets. 11 of these 67 precursor genes have alternative transcripts, bringing the total number of S. gregaria precursors identified in this study to 81. Based on this precursor information, we used different mass spectrometry approaches to identify the putative mature, bioactive peptides processed in the nervous system of S. gregaria. The thereby generated dataset for S. gregaria confirms significant conservation of the entire neuropeptidergic gene set typical of insects and also contains precursors typical of Polyneoptera only. This is in striking contrast to the substantial losses of peptidergic systems in some holometabolous species. The neuropeptidome of S. gregaria, apart from species-specific sequences within the known range of variation, is quite similar to that of Locusta migratoria and even to that of less closely related Polyneoptera. With the S. gregaria peptidomics data presented here, we have thus generated a very useful source of information that could also be relevant for the study of other polyneopteran species., (Copyright © 2021 Elsevier Ltd. All rights reserved.)