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PubMed1998

Generation and properties of a luminescent insect pathogen Xenorhabdus nematophilus (Enterobacteriaceae).

Studies on the interaction of the insect pathogenic bacterium, Xenorhabdus nematophilus (Enterobacteriaceae), with its nematode and insect hosts would be greatly assisted if a luminescent phenotype were generated that would allow the detection of viable bacteria in vivo without the necessity for disruption of the cellular interactions. The plasmid, pMGM221, containing the luminescence gene (luxCDABE) of Vibrio harveyi was introduced into different strains (DD136 and 19061) and phases (one and two) of X. nematophilus by triparental mating. For reproducible and efficient conjugation, it was necessary to use older cultures (96-160 h) in the stationary phase of X. nematophilus for mating with relatively small differences (<2-fold) in transconjugant yield for the different strains and phases of X. nematophilus. All transconjugants emitted high levels of light with optimum bioluminescence at 27 degrees C in Luria broth at pH 8.0 containing 20 g/L NaCl; pH, osmolarity, and temperature conditions were similar to those encountered by the bacteria in the hemolymph of the larvae of Galleria mellonella. Plasmids were detected in the transconjugants after 6 months of subculturing the bacteria without antibiotic selection. Aside from light emission, luminescent transconjugants had the same physiological properties as the nonluminescent parental strains, including identical rates of growth, production of exoenzymes, removal from and subsequent emergence into the insect's hemolymph, bacterial-induced hemocyte damage, suppression of prophenoloxidase activation, and the ability to kill G. mellonella larvae. Light-emitting larvae could readily be detected by eye in a dark room, and all bacteria reisolated from dead larvae were luminescent. These properties validate the use of luminescent X. nematophilus not only as a means of following bacterial host interactions, but also as a potential agent to follow the infection and death of the insect population.

Journal Article↗

PubMed2026

A horizontally acquired gene mediates insect cocoon pigmentation in the eri silkmoth, Samia ricini.

Holometabolous insects make cocoons during larval-pupal metamorphosis to protect the pupal phase. The materials used for cocoon construction vary widely. Lepidopteran insects typically secrete silk to form cocoons, which display diverse colors. The eri silkworm, Samia cynthia ricini, is an economically important domesticated species that mostly produces white cocoons, with some varieties producing red cocoons. The enzyme kynureninase (KYNU), acquired from bacteria by horizontal gene transfer, has previously been implicated in insect coloration, while the tryptophan metabolite 3-hydroxyanthranilic acid (3-HAA) has been identified as a red pigment. However, exactly how KYNU is involved in cocoon pigmentation remains unclear. Here, we report that a horizontally transferred bacterial gene encoding KYNU regulates red cocoon formation. Metabolomic analysis revealed a high accumulation of 3-HAA in red cocoons, confirming its role as the primary pigment and associating the coloration with tryptophan metabolism. Quantitative real-time polymerase chain reaction (qPCR) analysis indicated that SrKYNU is highly expressed in the silk glands and significantly downregulated in the red cocoon strain compared to the white cocoon strain. Genomic sequencing identified a 141 bp deletion in the upstream regulatory region of KYNU in the red cocoon strain compared to the white cocoon strain. Dual-luciferase assays confirmed that this deletion significantly reduced promoter activity. CRISPR/Cas9 knockout of SrKYNU in the white-cocoon strain resulted in mutants producing red cocoons with elevated 3-HAA content. These findings reveal that the horizontally transferred gene SrKYNU exhibits tissue-specific expression and regulates cocoon coloration in S. ricini, illustrating that horizontal gene transfer can play an important role in regulating an insect physiological process.

Animals↗

PubMed1989

Cytochrome P-450 monooxygenases in insects.

1. The insect monooxygenase system is involved in the oxidative metabolism of both endogenous and exogenous substrates. 2. Monooxygenases appear to be important in insect growth and development, in adaptation to multiple food plants in phytophagous insects and in pesticide resistance. 3. The genetics, purification and properties of cytochrome P-450 isozymes of the house fly (Musca domestica) are discussed in relation to their role in resistance to xenobiotics. 4. Induction of insect cytochrome P-450 isozymes is discussed in comparison to induction in mammals and with reference to polyphagy.

Animals↗

PubMed1998

Organization of the circadian system in insects.

The circadian systems of different insect groups are summarized and compared. Emphasis is placed on the anatomical identification and characterization of circadian pacemakers, as well as on their entrainment, coupling, and output pathways. Cockroaches, crickets, beetles, and flies possess bilaterally organized pacemakers in the optic lobes that appear to be located in the accessory medulla, a small neuropil between the medulla and the lobula. Neurons that are immunoreactive for the peptide pigment-dispersing hormone (PDH) arborize in the accessory medulla and appear to be important components of the optic lobe pacemakers. The neuronal architecture of the accessory medulla with associated PDH-immunoreactive neurons is best characterized in cockroaches, while the molecular machinery of rhythm generation is best understood in fruit flies. One essential component of the circadian clock is the period protein (PER), which colocalizes with PDH in about half of the fruit fly's presumptive pacemaker neurons. PER is also found in the presumptive pacemaker neurons of beetles and moths, but appears to have different functions in these insects. In moths, the pacemakers are situated in the central brain and are closely associated with neuroendocrine functions. In the other insects, neurons associated with neuroendocrine functions also appear to be closely coupled to the optic lobe pacemakers. Some crickets and flies seem to possess central brain pacemakers in addition to their optic lobe pacemakers. With respect to neuronal organization, the circadian systems of insects show striking similarities to the vertebrate circadian system.

Animals↗

PubMed2003

Expression, purification and serological analysis of hepatocellular carcinoma associated antigen HCA587 in insect cells.

AIM: In order to assess hepatocellular carcinoma associated antigen HCA587 as a potential target for immunotherapy, the Bac-to-Bac expression system was used to express recombinant protein HCA587 in insect cells. METHODS: The cDNA encoding HCA587 gene was cloned into donor vector pFasBacHtb and recombinant pFasBac Htb-587 was transformed into competent cells DH10Bac. Recombinant Bacmid-587 was transfected into Sf9 insect cells using CELLFECTIN, Recombinant HCA587 protein was produced in Sf9 insect cells after infection with recombinant baculovirus, and was purified using Ni-NTA resin. Sera from HCC patients were also screened using recombinant protein HCA587. RESULTS: The molecular weight of the recombinant protein HCA587 expressed in insect cells was approximately 43kd. Western blot results proved the recombinant protein HCA587 had the similar antigenicity with its native counterpart. Serological analysis told that the rate of seroreactivity to HCA587 was not high in HCC patients. CONCLUSION: The recombinant protein HCA587 was successfully expressed and purified using Bac-to-Bac expression system. It paved the way for generation of specific antibody and investigation of immunohistochemical analysis and immune responses of HCC in the future.

Animals↗

PubMed2000

Central complex in the brain of crayfish and its possible homology with that of insects.

A small, medial heterolateral neuropil in the brain of crustaceans has long been regarded as the central body of the crustacean brain. Its simplicity and the absence of clear layers within its neuropil have led to the question of its homology with the more complex central body that occupies an approximately equivalent position in the brain of insects. We have labelled neurons in the central body of the Australian freshwater crayfish Cherax destructor by the extracellular application of dextrans and by treating the brain with antibodies to anti-CCAP, anti-locustatachykinin, anti-perisulfakinin, anti-proctolin, anti-dip-allatostatin AI, anti-PEA-head-peptide, anti-serotonin, and anti-rabbit anti-substance P, all of which label neurons in the insect brain. The dextran and immunocytochemical labelling have revealed a neural complex associated with the crayfish central body that is very similar in overall anatomical architecture to the subset of neuropils that are incorporated in the central complex of the insects, and in particular to that of the locust. Similarities between the crayfish and locust central complexes extend to the number and position of the neuropils, the location of the cell body clusters of the neurons that belong to the central complex, the numbers of tracts that link some of the constituent neuropils together, and the form and immunoreactivity of many of the individual neuron classes. These similarities are taken as evidence to support a possible homology between the crustacean central complex and that of the insects.

Animals↗

PubMedDate not supplied

Population dynamics of mosquito immatures and the succession in abundance of aquatic insects in rice fields in Madurai, South India.

Studies on the breeding pattern of mosquito immatures and the successional changes in the abundance of aquatic insects were conducted in rice fields near Madurai, south India. The population of late (III/IV) larval instars of culicines peaked on Day 28 and pupae (Culex tritaeniorhynchus, Cx. pseudovishnui and Cx. vishnui) peaked on Day 9 after transplantation, whereas the population of late (III/IV) larval instars of anophelines peaked on Day 19 and pupae of Anopheles subpictus and An. vagus on Days 7 and 9 respectively, after transplantation of paddy. A total of 14 families (consisting of 17 subfamilies) of aquatic insects belonging to six different orders, Coleoptera, Diptera, Ephemeroptera, Hemiptera, Anisoptera and Zygoptera were collected during the study period and the abundance of each group of insects is discussed in detail. The Shannon-Weaver Diversity Index, applied to study the diversity of different groups of aquatic insects, showed a clear pattern in diversity of surface predators, bottom predators and non-predators of mosquito immatures. The multiple linear regression model reveals that notonectid adults, coenagrionids, libellulids and veliids act as important predators of mosquito immatures in rice fields.

Animals↗

PubMed2002

[Fluoride accumulation and distribution in mulberry insects near fluoride pollution sources].

Fluoride accumulation and the relative fluoride loading of different body parts in wild mulberry silkworm (Bombyx mandarina M.), mulberry geometrid (Pathonandria atrineata B.), and mulberry silkworm (Bombyx mori L.) near fluoride pollution sources were studied. Comparison of the fluoride content of insect bodies and mulberry leaves showed that insects collected from polluted sites had increased fluoride accumulation. The digestive tract of the insect had much higher fluoride content than the other parts of the body and was considered to be the important organ of fluoride accumulation. There were also wide differences in fluoride accumulation between different insect species within the same polluted site. The highly significantly correlation between fluoride contents of wild mulberry silkworm, mulberry geometrid, and mulberry silkworm with that of the mulberry leaves on which they were collected was found.

Air Pollutants↗

PubMed2001

[Expression of baculovirus recombinant HPV16L1 and L2 capsid proteins in insect cells].

BACKGROUND: To express capsid proteins of HPV16 in insect cells system. METHODS: Recombinant baculovirus stocks were generated by cotransfection with baculovirus DNA and baculovirus recombinant transfer plasmids. The expression of aimed proteins in insect cells were confirmed by using SDS-PAGE and Western blot. RESULTS: Two stable strains of recombinant baculovirus expressing HPV16L1 protein alone and co-expressing HPV16L1 plus L2 proteins were obtained. The L1 and L2 ORFs of HPV16 produced proteins of 57000 and 97000, respectively. The yield of L1 protein was about 25%-30% of the total proteins of the insect cell. CONCLUSIONS: L1 and L2 proteins of HPV16 could be expressed with high efficiency in insect cells via recombinant baculoviruses.

Animals↗

PubMedDate not supplied

Survival at low temperatures in insects: what is the ecological significance of the supercooling point?

Many freezing-intolerant insects may die during long or even brief exposures to temperatures above their supercooling point (SCP). Consequently, the real ecological value of the SCP remains ambiguous, particularly for tropical species that never experienced cold exposures. The bimodal distribution of SCP is discussed in the light of sexual dimorphism. The importance of sex in insect cold hardiness has been regularly neglected and although we admit that in some species sex may be uneasy to determine, it should be taken into account in further studies. We suggest that supercooling ability may be, at least partially, a result of adaptations to other functions unrelated to cold, including the desiccation resistance. The potential causes of insect death at low temperatures during survival experiments have also been examined. Prolonged exposures at lethal low temperatures can produce deleterious effects (including death) even if the insect does not freeze; during long-term exposure to low temperatures the organisms may finally die from the exhaustion of energy reserves.

Animals↗

PubMed2001

Effects of insecticide treatments on insect density and diversity in vegetable open fields.

Vegetable open field areas increased for 15 years in Wallonia, mainly in Hesbaye. To be in accordance with quality standards, especially in terms of agro-chimical residues (R.M.L.), biological pest control was developed and allowed to reduce the insecticide use, leading to have safer fresh products. Among cultivated species in Wallonia, leguminous crops represent more than 85% of the vegetable production. To assess the impact of insecticide treatment on both pests (mainly aphids) and beneficial insects (predators and parasitoïds), broad bean (Vicia faba L.) fields were investigated during all the production duration. Twelve fields between Waremme and Hannut were visited weakly from May to July. In each field, control untreated and treated plots were investigated. Insects were caught using yellow traps and determined until the family level. Approximately 90.000 insects belonging to 59 major families (99% of captures) and 64 minor families were identified. These results showed that biodiversity in terms of family numbers was significantly higher in unsprayed plots. In addition, biodiversity and biomass (insect density) increased gradually during the season. Evaluation of pest and beneficial diversity and density was discussed in relation to aphicid (lambda-cyhalothrin, pirimicarb) treatments and the development of I.P.M. program in vegetable crops.

Animals↗

PubMed1999

[Cloning and expression of bluetongue virus VP3 protein in insect cells].

OBJECTIVE: To elucidate the biological activities of VP3 protein of bluetongue virus (BTV) expressed in insect cells and to assemble, in future, the BTV core-like particles. METHODS: First, full length of BTV13 L3 cDNA was constructed from 2 sequenced clones. The silver staining of the splicing region proved that the construction was correct. Then, a recombinant baculovirus expression vector pFB1BL3 was constructed to express the L3 gene in insect cells. RESULTS: BTV13 VP3 could be highly expressed in Sf-9 cells, the production could occupy up to 10%-15% of the total cell protein. Core-like particles could be observed after co-expression of the VP3 and VP7 in insect cells. CONCLUSION: VP3 of BTV expressed in insect cells possesses biological activity and can be used to assemble BTV core-like particles.

Animals↗

PubMed2002

Host plant resistance to insects: an eco-friendly approach for pest management and environment conservation.

Host plant resistance (HPR) to insects is an effective, economical, and environment friendly method of pest control. The most attractive feature of HPR is that farmers virtually do not need any skill in application techniques, and there is no cash investment by the resource poor farmers. Considerable progress has been made in identification and development of crop cultivars with resistance to the major pests in different crops. There is a need to transfer resistance genes into high-yielding cultivars with adaptation to different agro-ecosystems. Resistance to insects should form one of the criteria to release varieties and hybrids for cultivation by the farmers. Genes from the wild relatives of crops, and novel genes, such as those from Bacillus thuringiensis can also be deployed in different crops to make HPR an effective weapon to minimize the losses due to insect pests. HPR will not only cause a major reduction in pesticide use and slowdown the rate of development of resistance to insecticides in insect populations, but also lead to increased activity of beneficial organisms and reduction in pesticide residues in food and food products.

Adaptation, Physiological↗

PubMedDate not supplied

[Dynamics of 134 + 137Cs accumulation in insects inhabiting the 30-kilometer zone of Chernobyl Nuclear Power Station].

Accumulation of the specific activity of 134 + 137Cs in insects was investigated in the most typical biogeocenoses within the 30-km zone of the Chernobyl NPP. The studied biogeocenoses had different rates of the exposure doses. It was shown that the specific activity of 134 + 137Cs in the insects inhabiting forest biotops was of the same order that in the crown, whereas in the insects inhabiting open biotops the specific activity was higher than in plants. Two periods of the increased 134 + 137Cs content in insects were found: May and September. Along with seasonal activity variations, a tendency to decreasing and stabilization of 134 + 137Cs content was observed during the period of the study.

Animals↗

PubMed2002

[Study on the micro-identification of insect material medicine].

OBJECTIVE: To seek microstructure characters and method of insect material medicines. METHOD: Insect material medicines and Chinese patent medicines containing these medicines were observed and compared with OLYMPUS. RESULT: The texture of integumentary cells, the shape and size of hair socket and bristle were important characters for species identification. CONCLUSION: This method can effectively identify 8 insect medicines, which provides some data and foundation for Chinese patent medicines' identification containing insects medicines and making quality standard for new drugs.

Animals↗

PubMed1992

Over-expression and characterization of recombinant beta subunit of the human chorionic gonadotropin hormone synthesized in insect cells infected with a genetically engineered baculovirus.

A recombinant baculovirus, vAc beta hCG, having a replacement of the viral polyhedrin gene with the cDNA encoding the beta subunit of hCG was used to express beta hCG, an extensively glycosylated hormone, in insect cells. Virus-infected cells, 72 hr pi, secreted approximately 8.02 micrograms beta hCG/2 x 10(6) cells/ml. The recombinant beta hCG purified from insect cells exhibited increased mobility on SDS-PAGE as compared to authentic urinary beta hCG, a reflection on differences in glycosylation between insect and mammalian systems. The insect derived beta hCG, however, was identical to the native hormonal peptide in terms of immunoreactivity and bioactivity on association with alpha-subunit, as evident by its binding to rat testicular receptors and induction of steroidogenesis in a mouse Leydig cell bioassay system. The implications of using the baculovirus system to study the importance of carbohydrates for biological activity are also discussed.

Animals↗

PubMed2003

Suppression of adult neurogenesis impairs olfactory learning and memory in an adult insect.

Although adult neurogenesis has now been demonstrated in many different species, the functional role of newborn neurons still remains unclear. In the house cricket, a cluster of neuroblasts, located in the main associative center of the insect brain, keeps producing new interneurons throughout the animal's life. Here we address the functional significance of adult neurogenesis by specific suppression of neuroblast proliferation using gamma irradiation of the insect's head and by examining the impact on the insect's learning ability. Forty gray irradiation performed on the first day of adult life massively suppressed neuroblasts and their progeny without inducing any noticeable side effect. We developed a new operant conditioning paradigm especially designed for crickets: the "escape paradigm." Using olfactory cues, visual cues, or both, crickets had to choose between two holes, one allowing them to escape and the other leading to a trap. Crickets lacking adult neurogenesis exhibited delayed learning when olfactory cues alone were used. Furthermore, retention 24 hr after conditioning was strongly impaired in irradiated crickets. By contrast, when visual cues instead of olfactory ones were provided, performance of irradiated insects was only slightly affected; when both olfactory and visual cues were present, their performance was not different from that of controls. From these results, it can be postulated that newborn neurons participate in the processing of olfactory information required for complex operant conditioning.

Animals↗

PubMed2003

Laboratory evaluation of heavy metals stress on certain biochemical parameters of the aquatic insect, Sphaerodema urinator Duf. (Hemiptera: Belostomatidae).

The present work discussed the effect of lead and copper on certain biochemical parameters of the aquatic insect, Sphaerodema urinator, Duf. (Hemiptera: Belostomatidae). The insect samples were collected from fish farms of some volunteers. LC25 and LC50 were determined. The insects were exposed to three concentration levels (10, 20 and 30 mM) of lead nitrate and copper sulphate. The biochemical studies were carried out on the whole body homoginate. The results showed great reductions of the main metabolites (carbohydrates, lipid and protein). A decline in the alkaline phosphatase activity was detected, while an increase in the activity of acid phosphatase was found. Also the treated insects showed lower activities of GOT and GPT. In general, all estimated parameters were less than those of control.

Alkaline Phosphatase↗