Fat Body Of Larvae Research Articles

Particle Size Effect of Micro and Nano Aluminium Oxides on Antioxidant Defence System of Model Organism Galleria mellonella

Studies on heavy metal toxicity show that toxicity of nanoparticles compared to micro form have hypothesis regarding nanoparticles are more efficient on the oxidative stress. The aim of the study was to compare the toxic effects of nano and micro particles of Al2O3 and tissue differences on oxidative stress using model organism Galleria mellonella larvae. The study presented that Al2O3 NPs increased the antioxidant enzyme activities in the fat body of larvae, whereas Al2O3 MPs increased the enzyme activities in the midgut of larvae. In conclusion, heavy metal toxicity depends on the particle size, as well as tissue differences.

An Acyl Carrier Protein Gene Affects Fatty Acid Synthesis and Growth of Hermetia illucens

Acyl carrier protein (ACP) is an acyl carrier in fatty acid synthesis and is an important cofactor of fatty acid synthetase. Little is known about ACP in insects and how this protein may modulate the composition and storage of fatty acids. We used an RNAi-assisted strategy to study the potential function of ACP in Hermetia illucens (Diptera: Stratiomyidae). We identified a HiACP gene with a cDNA length of 501 bp and a classical conserved region of DSLD. This gene was highly expressed in the egg and late larval instars and was most abundant in the midgut and fat bodies of larvae. Injection of dsACP significantly inhibited the expression level of HiACP and further regulated the fatty acid synthesis in treated H. illucens larvae. The composition of saturated fatty acids was reduced, and the percentage of unsaturated fatty acids (UFAs) was increased. After interfering with HiACP, the cumulative mortality of H. illucens increased to 68.00% (p < 0.05). H. illucens growth was greatly influenced. The development duration increased to 5.5 days, the average final body weights of larvae and pupae were decreased by 44.85 mg and 14.59 mg, respectively, and the average body lengths of larvae and pupae were significantly shortened by 3.09 mm and 3.82 mm, respectively. The adult eclosion rate and the oviposition of adult females were also severely influenced. These results demonstrated that HiACP regulates fatty acid content and influences multiple biological processes of H. illucens.

Genome-wide identification of lncRNAs associated with viral infection in Spodoptera frugiperda.

The role of lncRNAs in immune defence has been demonstrated in many multicellular and unicellular organisms. However, investigation of the identification and characterization of long non-coding RNAs (lncRNAs) involved in the insect immune response is still limited. In this study, we used RNA sequencing (RNA-seq) to investigate the expression profiles of lncRNAs and mRNAs in the fall armyworm Spodoptera frugiperda in response to virus infection. To assess the tissue- and virus-specificity of lncRNAs, we analysed and compared their expression profiles in haemocytes and fat body of larvae infected with two entomopathogenic viruses with different lifestyles, i.e. the polydnavirus HdIV (Hyposoter didymator IchnoVirus) and the densovirus JcDV (Junonia coenia densovirus). We identified 1883 candidate lncRNAs, of which 529 showed differential expression following viral infection. Expression profiles differed considerably between samples, indicating that many differentially expressed (DE) lncRNAs showed virus- and tissue-specific expression patterns. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment and target prediction analyses indicated that DE-LncRNAs were mainly enriched in metabolic process, DNA replication and repair, immune response, metabolism of insect hormone and cell adhesion. In addition, we identified three DE-lncRNAs potentially acting as microRNA host genes, suggesting that they participate in gene regulation by producing miRNAs in response to virus infection. This study provides a catalogue of lncRNAs expressed in two important immune tissues and potential insight into their roles in the antiviral defence in S. frugiperda. The results may help future in-depth functional studies to better understand the biological function of lncRNAs in interaction between viruses and the fall armyworm.

Luminescence Tracking and In Vivo Toxicity Evaluation of TiO2 and Europium Doped TiO2 Nanocrystals during Drosophila Development

Titanium dioxide (TiO2) nanoparticles (NPs) are widely used in industry and commercial products. Thus, their potential risks to the environment and human health must be evaluated. Doping NPs with certain ions makes it possible to mix properties or generate new ones. Thus, in order to track TiO2 NPs in biological assays, doping with europium (Eu3+) ions was performed, which luminesce in red. Here, we synthesized TiO2 and Eu3+-doped TiO2 nanocrystals (NCs) in anatase phase to verify the toxicity at different concentrations in Drosophila melanogaster and track the distribution of these NCs in vivo. We verified that the incorporation of europium improved the biocompatibility in relation to the pure samples. The presence of Eu3+-doped TiO2 NCs in the gut, brain, and fat body of larvae and intestinal cells of adult animals was detected. Eu3+-doped TiO2 NCs caused significant larval and pupal mortality rates, in addition to leading to the formation of reactive species, especially at high concentrations. Therefore, our data demonstrated it was possible to trace the Eu3+-doped TiO2 NCs, but TiO2 and Eu3+-doped TiO2 NCs in anatase phase were toxic to fruit flies at the tested concentrations, and should be used with caution to minimize health risks.

Antimicrobial peptides expressed in the fat body of Spodoptera frugiperda (Lepidoptera: Noctuidae) in response to the microbial challenge

Spodoptera frugiperda (Lepidoptera: Noctuidae) is the key pest in maize crops and has a major impact on world agriculture. Several studies on the biological control of this species have been carried out, and these demonstrate resistance to biological control and pesticides. However, the humoral immune system of S. frugiperda is not yet completely known in relation to the innate immune response to biological control agents. The aim of this study was to evaluate the expression of Gloverin, Sf-gallerimycin, and Attacin genes in the fat body of larvae at the 6th instar of development. Our work confirmed the expression of Sf-gallerimycin in response to the bacterial challenge, 24 h post-inoculation, and revealed the expression of Gloverin and Attacin for the first time for both bacterial challenge and entomopathogenic fungus Beauveria bassiana challenge. Gloverin and Attacin genes were upregulated under the conditions analyzed. In addition, we revealed the presence of two probable antimicrobial peptides in the hemolymph, induced 24 h post challenge with the microorganisms. The 4.7 kDa band b is probably a defensin-like peptide, and the 6.1 kDa band a is a peptide not yet reported in S. frugiperda.

Nutrition regulates the expression of storage proteins in Bombyx mori via insulin-like/FoxO signaling pathway

Insect serum proteins, also termed storage proteins (SPs), are hexamer proteins that form amino acid reservoirs important for the development of pupae and embryos in most insects. In this study, we investigated the SP genes expression and regulation pathways in silkworms (Bombyx mori). We observed that B. mori SPs (BmSPs) in the fat body of larvae were strongly decreased by starvation, suggesting they respond to nutrition deprivation. Further, we examined the relationship between BmSP expression and the insulin-like signaling pathway (ILS) to study the regulation of BmSPs expression. The results showed that insulin up-regulated the expression of BmSPs, but an inhibitor of the ILS pathway protein PI3K downregulated the expression of BmSPs in B. mori larvae. Similar results were observed in cultured fat body in vitro and BmE cells. We then over-expressed FoxO, an ILS transcriptional factor, in BmE cells and B. mori larvae to further verify the regulatory role of ILS on expression of BmSPs and found BmFoxO negatively regulates the expression of BmSPs in both BmE cells and larvae. Moreover, BmFoxO was dephosphorylated and translocated from the cytoplasm to the nucleus under starvation treatment. Finally, an element on −2627–2644 bp upstream of the transcription start site of BmSP1 was identified as the binding site of BmFoxO by electrophoretic mobility shift assay and verified by chromatin immunoprecipitation. In summary, our results indicate that nutrient uptake triggers the expression of BmSPs via the ILS/FoxO signaling pathway. This study provides a reference for further study on the expression and regulation of insect SP genes.

Herbivore-induced tomato plant volatiles lead to the reduction of insecticides susceptibility in Spodoptera litura

Herbivore-induced plant volatiles (HIPVs) have been associated with plant-plant-herbivorous-natural enemies communication and an enhanced response to the subsequent attack. Spodoptera litura is a serious cosmopolitan pest that has developed a high level of resistance to many insecticides. However, the underlying molecular and biochemical mechanism by which HIPV priming reduces S. litura larval sensitivity to insecticides remains largely unknown. This study was conducted to explore the potential of volatile from undamaged, or artificially damaged, or S. litura-damaged tomato plants on the susceptibility of S. litura to the insecticides beta-cypermethrin indoxacarb and chlorpyrifos. We found that larvae exposed to volatile from S. litura-damaged or artificially damaged tomato plants were significantly less susceptible to the three insecticides than those exposed to volatile from undamaged tomato plants. Elevated activities of detoxifying enzymes [cytochrome P450 monooxygenases (P450s), glutathione S-transferases (GSTs), and esterases (ESTs)], were expressed in S. litura larvae exposed to volatile from S. litura-damaged tomato plants than those exposed to volatile from undamaged tomato plants. Similarly, seven detoxification-related genes [GSTs (SlGSTe1, SlGSTo1, and SlGSTe3) and P450s (CYP6B48, CYP9A40, CYP321A7, and CYP321B1)] in the midgut and fat body of larvae were up-regulated under exposure to volatile from S. litura-damaged tomato plants. Increased volatile organic compounds emissions were detected in the headspace of tomato plants damaged by S. litura compared to the undamaged plants. Collectively, these findings suggest that HIPVs can considerably reduce caterpillar susceptibility to insecticides, possibly through induction-enhanced detoxification mechanisms, and provide valuable information for implementing an effective integrated pest management strategy.

Three cytochrome P450 CYP4 family genes regulated by the CncC signaling pathway mediate phytochemical susceptibility in the red flour beetle, Tribolium castaneum

AbstractBackgroundInsect cytochrome P450 monooxygenases (P450s) play a crucial role in phytochemical metabolism and tolerance. Three P450 genes (TcCYP4Q3, TcCYP4Q5, and TcCYP4Q7) are associated with the response of eugenol in Tribolium castaneum. However, the responding mechanisms of these P450 genes to eugenol remain unknown.ResultsHere, spatiotemporal expression profiling revealed that TcCYP4Q3 and TcCYP4Q5 were most highly expressed in late adult, while TcCYP4Q7 was predominantly expressed in late larva; and all of these three P450 genes were mainly expressed in the fat body of larvae. Furthermore, the expressions of these three P450 genes were significantly up‐regulated after exposure to eugenol, and depletion of them enhanced the susceptibility of beetles to eugenol. Interestingly, RNA interference (RNAi) against the CncC gene, a transcription factor of CncC signaling pathway associated with regulation of insect P450s in response to phytochemicals, reduced the transcripts of these three P450 genes following exposure to eugenol. Investigation of CncC signaling pathway showed that this pathway could be activated by eugenol.ConclusionAltogether, the results indicate that these three P450 genes are regulated by CncC signaling pathway to participate in the susceptibility of Tribolium castaneum to phytochemicals. These findings will aid implications for the development of novel therapeutics to control pest. © 2022 Society of Chemical Industry.

Bombyx mori can synthesize ascorbic acid through the l-gulose pathway to varying degrees depending on developmental stage.

Vitamin C (VC) is an essential nutrient for many animals. However, whether insects, including Bombyx mori, can synthesize VC remains unclear. In this article, the optimized HPLC method was used to determine the content of l-ascorbic acid (AsA) in silkworm eggs, larvae and pupae, and the activity of l-gulono-1,4-lactone oxidase (GULO), a key enzyme in VC synthesis. The RNA interference method was used to determine the effect of the BmGulo-like gene on embryonic development and GULO activity in the pupal fat body. The AsA content increased significantly during E144 h-E168 h in the late embryonic stage and P48 h-P144 h in the middle-late pupal stage, in which exogenous VC was not ingested. Furthermore, the body AsA content in larvae fed VC-free feed also increased with larval stage. The GULO enzymatic activity was present in eggs and the fat bodies of larvae and pupae, even when the larvae were reared with fresh mulberry leaves. Moreover, the activity was higher in the later embryonic stages (E144 h-E168 h) and the early pupal stage (before P24 h). The GULO activity in the pupal fat body dramatically decreased when the screened BmGulo-like gene (BGIBMGA005735) was knocked down with small interfering RNA; in addition, the survival rate and hatching rate of eggs significantly decreased 21% and 44%, respectively, and embryonic development was delayed. Thus, Bombyx mori can synthesize AsA through the l-gulose pathway, albeit with low activity, and this synthesis ability varies with developmental stages.

Galleria mellonellalarvae fat body disruption (Lepidoptera: Pyralidae) caused by the venom ofHabrobracon brevicornis(Hymenoptera: Braconidae)

The ability of Habrobracon brevicornis venom to elevate the nutritional suitability of a host by affecting the host larvae fat body condition was studied. To understand whether H. brevicornis crude venom impacts the host biochemical profile, the concentrations of total lipids and main sugars in the host larvae lymph were analyzed. All measurements were carried out during the first 3 days after envenomation. A significant increase in the lipid level was fixed only on the second day after envenomation. A significant increase in the total trehalose count was detected during all 3 days, while a significant increase in glucose concentration was noted only on the first day. Well-observed disruptions were fixed in thin and semithin sections of the G. mellonella larval fat body starting from the second day after envenomation. Significant increases in both phospholipase A2 and C enzyme activity as well as acid proteases were detected in the wax moth fat body after envenomation during all experimental times. At the same time, imbalances in the antioxidant system, including changes in the activities of superoxide dismutase, peroxidases, catalase, and glutathione-S-transferase, were detected. The reliable increase in the expression of the gene encoding Hsp70 was fixed both for 24 and 48 h after envenomation, while a reliable increase in the expression of the gene encoding inhibitor of apoptosis protein was detected only 24 h after wax moth larvae envenomation. Considering the absence of DNA fragmentation, the imbalance in the "ROS/antioxidants" system, and the increased activity of phospholipases and acid proteases in the fat body cells from envenomated wax moth larvae, we can hypothesize that the fat body disruption occurs in a necrotic manner. The results of the work expand the knowledge about the biochemical aspects of interaction between ectoparasitoids and their hosts.

Tissue Tropisms and Transstadial Transmission of a Rickettsia Endosymbiont in the Highland Midge, Culicoides impunctatus (Diptera: Ceratopogonidae).

Rickettsia is a genus of intracellular bacteria which can manipulate host reproduction and alter sensitivity to natural enemy attack in a diverse range of arthropods. The maintenance of Rickettsia endosymbionts in insect populations can be achieved through both vertical and horizontal transmission routes. For example, the presence of the symbiont in the follicle cells and salivary glands of Bemisia whiteflies allows Belli group Rickettsia transmission via the germ line and plants, respectively. However, the transmission routes of other Rickettsia bacteria, such as those in the Torix group of the genus, remain underexplored. Through fluorescence in situ hybridization (FISH) and transmission electron microscopy (TEM) screening, this study describes the pattern of Torix Rickettsia tissue tropisms in the highland midge, Culicoides impunctatus (Diptera: Ceratopogonidae). Of note is the high intensity of infection of the ovarian suspensory ligament, suggestive of a novel germ line targeting strategy. Additionally, localization of the symbiont in tissues of several developmental stages suggests transstadial transmission is a major route for ensuring maintenance of Rickettsia within C. impunctatus populations. Aside from providing insights into transmission strategies, the presence of Rickettsia bacteria in the fat body of larvae indicates potential host fitness and vector capacity impacts to be investigated in the future.IMPORTANCE Microbial symbionts of disease vectors have garnered recent attention due to their ability to alter vectorial capacity. Their consideration as a means of arbovirus control depends on symbiont vertical transmission, which leads to spread of the bacteria through a population. Previous work has identified a Rickettsia symbiont present in several species of biting midges (Culicoides spp.), which transmit bluetongue and Schmallenberg arboviruses. However, symbiont transmission strategies and host effects remain underexplored. In this study, we describe the presence of Rickettsia in the ovarian suspensory ligament of Culicoides impunctatus Infection of this organ suggests the connective tissue surrounding developing eggs is important for ensuring vertical transmission of the symbiont in midges and possibly other insects. Additionally, our results indicate Rickettsia localization in the fat body of Culicoides impunctatus As the arboviruses spread by midges often replicate in the fat body, this location implies possible symbiont-virus interactions to be further investigated.

Disturbance of the Main Body Metabolites in Larvae and Pupae of Spodoptera littoralis (Lepidoptera: Noctuidae) by Certain Sesquiterpene Compounds

The Egyptian cotton leafworm Spodoptera littoralis (Boisduval) is a dangerous pest of many field crops and vegetables in the world. The present study was conducted to investigate the disturbing effects of the sesquiterpene compounds, Farnesol, Nerolidol, and Bisabolol, on the main body metabolites in larvae and pupae of this insect. The newly moulted last (6th) instar larvae were treated with LC50 values of these compounds (33.67, 42.24 and 59.31 ppm, respectively) and the determination of the main metabolites was achieved in haemolymph and fat bodies of larvae and the homogenate of pupae. The most important results could be summarized as follows. The present study recorded predominant reducing effects of these compounds on the protein content in larvae and pupae with an exceptional enhancing effect of some compounds at certain ages of last instar larvae. Also, the lipid content in haemolymph and fat bodies of larvae as well as in the pupae was remarkably reduced. In addition, all compounds exhibited predominant reducing effects on the carbohydrate content in haemolymph and fat bodies of larvae and in the pupae, with two exceptions of increasing carbohydrate content in larval haemolymph (at 24 hr post-treatment) and in larval fat bodies by Nerolidol (at 72 hr post-treatment).

The ghost of temperature past: interactive effects of previous and current thermal conditions on gene expression in Manduca sexta.

High temperatures can negatively impact the performance and survival of organisms, particularly ectotherms. While an organism's response to high temperature stress clearly depends on current thermal conditions, its response may also be affected by the temporal pattern and duration of past temperature exposures. We used RNA sequencing of Manduca sexta larvae fat body tissue to evaluate how diurnal temperature fluctuations during development affected gene expression both independently and in conjunction with subsequent heat stress. Additionally, we compared gene expression between two M. sexta populations, a lab colony and a genetically related field population that have been separated for >300 generations and differ in their thermal sensitivities. Lab-adapted larvae were predicted to show increased expression responses to both single and repeated thermal stress, whereas recurrent exposure could decrease later stress responses for field individuals. We found large differences in overall gene expression patterns between the two populations across all treatments, as well as population-specific transcriptomic responses to temperature; more differentially expressed genes were upregulated in the field compared with lab larvae. Developmental temperature fluctuations alone had minimal effects on long-term gene expression patterns, with the exception of a somewhat elevated stress response in the lab population. Fluctuating rearing conditions did alter gene expression during exposure to later heat stress, but this effect depended on both the population and the particular temperature conditions. This study contributes to increased knowledge of molecular mechanisms underlying physiological responses of organisms to temperature fluctuations, which is needed for the development of more accurate thermal performance models.

Molecular characterization of immune responses of Helicoverpa armigera to infection with the mermithid nematode Ovomermis sinensis

BackgroundMermithid nematodes, such as Ovomermis sinensis, display a broad host range including some lepidopteran pests. Infective juveniles penetrate their host through the cuticle, complete their growth within the hemocoel and eventually kill the host upon their emergence. Hence, mermithid nematodes are considered potential biological control agents of insect pests. Our previous data indicate that the infection rate of O. sinensis on cotton bollworm (Helicoverpa armigera) is low, which may be largely due to the strong immune system of the host. However, current knowledge on the interactions of mermithid nematodes with their hosts and the mechanisms employed by hosts to defend themselves against mermithid nematodes is limited.ResultsHere, we investigated the response of H. armigera to O. sinensis infection. Parasitism by O. sinensis caused a sharp decline in the survival rate of H. armigera. The hemocytic phagocytosis ability, antibacterial activity, and phenoloxidase (PO) activity in plasma of H. armigera increased at 1 d post parasitism (dpp) but decreased at 3 dpp. Further, we investigated gene expression in the fat body of parasitized and non-parasitized H. armigera larvae at 1, 3, and 5 dpp using a digital gene expression system. In total, 41, 60 and 68 immune-related differentially expressed genes were identified at 1, 3, and 5 dpp, respectively. These genes encoded pattern recognition receptors (PRRs), antimicrobial peptides (AMPs), serine proteases (SPs), SP inhibitors, mucins and other immune-related proteins. The expression of most PRRs, AMPs, SPs, and mucins was upregulated in the fat body of larvae at 1 dpp, downregulated at 3 dpp, and then again upregulated at 5 dpp by O. sinensis. The increased expression of SP inhibitors may contribute to the inhibited PO activity at 5 dpp.ConclusionsThis study demonstrates that parasitism by O. sinensis modulates the immune reaction of the host H. armigera by altering the expression of immune-related genes. Our data provide a basis for future investigation of the molecular mechanisms employed by the mermithid nematode O. sinensis to modulate the immunity of the host H. armigera. These data will also likely facilitate the improvement of success in parasitism of H. armigera by O. sinensis.

Knockdown of dorsal/relish increases larvae susceptibility to microbes in Spodoptera litura

Abstract The tobacco cutworm, Spodoptera litura has developed high levels of resistance to frequently-used insecticides, and failures of chemical control has frequently been reported in China. Moreover, the control efficiency of biological control agents was not satisfactory by farmers, and thus the development of novel or combined techniques for such pest control becomes an imperative requirement. In this study the potential application of innate immune-related genes in insect control was investigated. Sldorsal and Slrelish were identified from S. litura. Sldorsals were mainly expressed in epidermal and fatbody of larvae, and Slrelish highly expressed in fatbody and haemolymph of larvae. Their expression characteristic suggests potential roles in defense against fungi or bacteria. The expression of Sldorsal was up-regulated by the challenge of entomogenous fungi Isaria javanica and Beauveria bassiana, however, the expression of Slrelish could only be induced by Escherichia coli challenge. Injection of Sldorsal or Slrelish dsRNA down-regulated the expression level of the corresponding gene and broke specific signaling transduction pathway of innate immunity in S. litura. Knockdown of Sldorsal by RNAi significantly increased the mortality of S. litura larvae caused by I. javanica and B. bassiana, and Slrelish RNAi highly increased the mortality caused by E. coli. Sldorsal and Slrelish are essential genes for innate immunity, their knockdown by RNAi increases S. litura susceptibility to insect pathogens, therefore enhances the mortalities caused by I. javanica, B. bassiana and E. coli respectively.

Identification and characterization of the catalase gene involved in resistance to thermal stress in Heortia vitessoides using RNA interference

To elucidate the role of catalase (CAT) in Heortia vitessoides Moore, which is one of the most destructive defoliating pests in Aquilaria sinensis (Loureiro) Sprenger forests, a CAT gene (HvCAT) was identified in the transcriptome of adult H. vitessoides. Sequence analyses indicated that HvCAT encodes a protein containing 507 amino acids, including a proximal active site sequence (FXRERIPERVVHAKGXGA), heme-ligand sequence (RLFSYNDTX), heme-binding residues (H73, S112, N146, F151, F159, R352, and Y356), and NADPH-binding residues (P149, H192, Y196, G199, R201, N211, H233, K235, I300, W301, P302, H303, Q442, and L445). A phylogenetic analysis indicated that CAT from lepidopteran species could be assigned to one well-supported cluster. Regarding its stage- and tissue-specific expression profiles, HvCAT was expressed at high levels in fifth-instar larvae, fat body of larvae, and abdomen of adults. Furthermore, when fifth-instar larvae were exposed to thermal stress at 35, 37, and 39 °C, hydrogen peroxide and malondialdehyde content significantly increased. HvCAT mRNA was upregulated when the larvae were exposed to temperatures of 31, 33, 35, 37, and 39 °C. The enzymatic activity of HvCAT was significantly elevated following thermal stress (35 and 37 °C). After the knockdown of HvCAT by double-stranded RNA interference, the expression of thioredoxin peroxidase (Tpx) increased, whereas that of copper zinc superoxide dismutase (Cu/ZnSOD) decreased. Additionally, knocking down HvCAT transcripts in fifth-instar larvae resulted in accelerated death following thermal stress at 35 °C. In summary, the results suggest that HvCAT plays a major role in the thermotolerance of H. vitessoides.

Disturbing Effects of Three Insect Growth Regulators on General Body Metabolism of the Olive Leaf Moth, Palpita unionalis (Hübner) (Lepidoptera: Pyralidae)

The olive leaf moth Palpita unionalis (Lepidoptera: Pyralidae) is an economic pest of the commercial olive groves in Egypt and different Mediterranean countries. The present study was conducted aiming to assess the disturbing effects of three novel IGRs, viz. Novaluron, Methoxyfenozide and Pyriproxyfen (LC50 values: 0.97, 0.176 and 0.00009 ppm, respectively) on the main metabolites (proteins, carbohydrates and lipids) in haemolymph and fat bodies of larvae (24 h-, 48 h- and 72 h-post-treatment) as well as in the developed pupae (3-day, 6-day and 9-day old pupae). Both Novaluron and Pyriproxyfen prevalently enhanced the treated larvae to gain increasing protein content in haemolymph, but Methoxyfenozide enhanced only the 48 h-old larvae. In the fat bodies, all IGRs predominantly prohibited the treated larvae to attain normal protein content. All of the tested IGRs profoundly prevented the developed pupae to attain normal protein level, regardless of the age. The carbohydrate content in haemolymph of larvae was dramatically declined, regardless the age. In larval fat bodies, all of the tested IGRs exerted suppressing actions on the carbohydrate content. In the developed pupae, carbohydrate content had been decreased, regardless of the tested IGR or the pupal age. The total lipid content in the haemolymph of treated larvae was elaborately declined, regardless the larval age. In fat bodies, all IGRs induced the larvae to gain more lipids. In the developed pupae, the lipid content was pronouncedly increased by Novaluron and Methoxyfenozide but dramatically reduced by Pyriproxyfen.

GLUTATHIONE S-TRANSFERASE Genes IN THE RICE LEAFFOLDER, Cnaphalocrocis medinalis (LEPIDOPTERA: PYRALIDAE): IDENTIFICATION AND EXPRESSION PROFILES.

In insects, glutathione S-transferases (GSTs) play critical roles in the detoxification of various insecticides, resulting in insecticide resistance. The rice leaffolder, Cnaphalocrocis medinalis, is an economically important pest of rice in Asia. GST genes have not been largely identified in this insect species. In the present study, by searching the transcriptome dataset, 25 candidate GST genes were identified in C. medinalis for the first time. Of these, 23 predicted GST proteins fell into five cytosolic classes (delta, epsilon, omega, sigma, and zeta), and two were assigned to the "unclassified" subgroup. Real-time quantitative PCR analysis showed that these GST genes were differentially expressed in various tissues, including the midgut, Malpighian tubules, and fat body of larvae, and the antenna, abdomen, and leg of adults, indicating diversified functions for these genes. Transcription levels of CmGSTd2, CmGSTe6, and CmGSTe7 increased significantly in larvae following exposure to chlorpyrifos, suggesting that these GST genes could be involved in the detoxification of this insecticide. The results of our study pave the way to a better understanding of the detoxification system of C. medinalis.

Sec22 Regulates Endoplasmic Reticulum Morphology but Not Autophagy and Is Required for Eye Development in Drosophila

The endoplasmic reticulum (ER) is a highly dynamic organelle that plays a critical role in many cellular processes. Abnormal ER morphology is associated with some human diseases, although little is known regarding how ER morphology is regulated. Using a forward genetic screen to identify genes that regulated ER morphology in Drosophila, we identified a mutant of Sec22, the orthologs of which in yeast, plants, and humans are required for ER to Golgi trafficking. However, the physiological function of Sec22 has not been previously investigated in animal development. A loss of Sec22 resulted in ER proliferation and expansion, enlargement of late endosomes, and abnormal Golgi morphology in mutant larvae fat body cells. However, starvation-induced autophagy was not affected by a loss of Sec22. Mosaic analysis of the eye revealed that Sec22 was required for photoreceptor morphogenesis. In Sec22 mutant photoreceptor cells, the ER was highly expanded and gradually lost normal morphology with aging. The rhabdomeres in mutants were small and sometimes fused with each other. The morphology of Sec22 mutant eyes resembled the eye morphology of flies with overexpressed eyc (eyes closed). eyc encodes for a Drosophila p47 protein that is required for membrane fusion. A loss of Syntaxin5 (Syx5), encoding for a t-SNARE on Golgi, also phenocopied the Sec22 mutant. Sec22 formed complexes with Syx5 and Eyc. Thus, we propose that appropriate trafficking between the ER and Golgi is required for maintaining ER morphology and for Drosophila eye morphogenesis.

Superoxide dismutases, SOD1 and SOD2, play a distinct role in the fat body during pupation in silkworm Bombyx mori.

One way that aerobic biological systems counteract the generation of reactive oxygen species (ROS) is with superoxide dismutase proteins SOD1 and SOD2 that metabolize superoxide radicals to molecular oxygen and hydrogen peroxide or scavenge oxygen radicals produced by the extensive oxidation-reduction and electron-transport reactions that occur in mitochondria. We characterized SOD1 and SOD2 of Bombyx mori isolated from the fat body of larvae. Immunological analysis demonstrated the presence of BmSOD1 and BmSOD2 in the silk gland, midgut, fat body, Malpighian tubules, testis and ovary from larvae to adults. We found that BmSOD2 had a unique expression pattern in the fat body through the fifth instar larval developmental stage. The anti-oxidative functions of BmSOD1 and BmSOD2 were assessed by exposing larvae to insecticide rotenone or vasodilator isosorbide dinitrate, which is an ROS generator in BmN4 cells; however, exposure to these compounds had no effect on the expression levels of either BmSOD protein. Next, we investigated the physiological role of BmSOD1 and BmSOD2 under environmental oxidative stress, applied through whole-body UV irradiation and assayed using quantitative RT-PCR, immunoblotting and microarray analysis. The mRNA expression level of both BmSOD1 and BmSOD2 was markedly increased but protein expression level was increased only slightly. To examine the differences in mRNA and protein level due to UV irradiation intensity, we performed microarray analysis. Gene set enrichment analysis revealed that genes in the insulin signaling pathway and PPAR signaling pathway were significantly up-regulated after 6 and 12 hours of UV irradiation. Taken together, the activities of BmSOD1 and BmSOD2 may be related to the response to UV irradiation stress in B. mori. These results suggest that BmSOD1 and BmSOD2 modulate environmental oxidative stress in the cell and have a specific role in fat body of B. mori during pupation.