Daily expression of two circadian clock genes in compound eyes of Helicoverpa armigera: evidence for peripheral tissue circadian timing

Silencing the rhythm gene AgCLK-1 reduced feeding of Aphis gossypii

The cotton aphid Aphis gossypii Glover is an important cotton pest, and means of controlling this insect is a primary research focus. Although biological rhythm is an important mechanism that regulates numerous insect processes and activities, its role in cotton aphid has not been elucidated. In the present study, four highly-expressed circadian rhythm genes were selected from the cotton aphid genome database and their physicochemical properties and protein structures were analyzed. These genes were in the Takeout, Timeless, and Timeless interacting-related families, and the corresponding proteins contained highly-conserved Swis and TIMELESS domains. Gene expression analysis at multiple developmental stages revealed differing expression patterns between the four genes. AgCLK-1 had the highest relative expression of the four, especially during the nymph period. Silencing AgCLK-1 caused a significant refusal of the cotton aphids to feed at 1, 3, and 5 d of treatment. These results demonstrated that AgCLK-1 played a key role in regulating the feeding behavior of cotton aphid. This new functional understanding provides novel insights into cotton aphid biology and suggests new targeting strategies for agricultural pest control.

Circadian Rhythms of Locomotor Activity Mediated by Cryptochrome 2 and Period 1 Genes in the Termites Reticulitermes chinensis and Odontotermes formosanus

Locomotor activity rhythms are crucial for foraging, mating and predator avoidance in insects. Although the circadian rhythms of activity have been studied in several termite species, the molecular mechanisms of circadian rhythms in termites are still unclear. In this study, we found that two termite species, R. chinensis and O. formosanus, exhibited clear circadian rhythms of locomotor activity in constant darkness along with rhythmically expressed core clock genes, Cry2 and Per1. The knockdown of Cry2 or Per1 expression in the two termite species disrupted the circadian rhythms of locomotor activity and markedly reduced locomotor activity in constant darkness, which demonstrates that Cry2 and Per1 can mediate the circadian rhythms of locomotor activity in termites in constant darkness. We suggest that locomotor activity in subterranean termites is controlled by the circadian clock.

FoxO-promoted peroxiredoxin1 expression induced by Helicoverpa armigera single nucleopolyhedrovirus infection mediates host development and defensive responses

Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) has a long coevolutionary history with its host, exerting profound effects on larval development, physiology and immune responses, although the mechanisms mediating these effects remain unclear. We demonstrate that HearNPV infection constrains the growth and development of larvae by inducing high levels of reactive oxygen species (ROS), which increase the expression of forkhead box O transcription factor (FoxO). FoxO upregulates the expression of peroxiredoxin 1 (Prx1) which serves to regulate larval development and immune responses following HearNPV infection. Collectively, our results provide novel insights into the role of Prx1 in larval development and immunity subsequent to HearNPV infection. Further investigation of the oxidative stress induced by HearNPV in H. armigera and its interactions with host immunity could yield novel insights useful in agricultural pest control.

The Circadian Clock in Lepidoptera

With approximately 160,000 identified species of butterflies and moths, Lepidoptera are among the most species-rich and diverse insect orders. Lepidopteran insects have fundamental ecosystem functions as pollinators and valuable food sources for countless animals. Furthermore, Lepidoptera have a significant impact on the economy and global food security because many species in their larval stage are harmful pests of staple food crops. Moreover, domesticated species such as the silkworm Bombyx mori produce silk and silk byproducts that are utilized by the luxury textile, biomedical, and cosmetics sectors. Several Lepidoptera have been fundamental as model organisms for basic biological research, from formal genetics to evolutionary studies. Regarding chronobiology, in the 1970s, Truman's seminal transplantation experiments on different lepidopteran species were the first to show that the circadian clock resides in the brain. With the implementation of molecular genetics, subsequent studies identified key differences in core components of the molecular circadian clock of Lepidoptera compared to the dipteran Drosophila melanogaster, the dominant insect species in chronobiological research. More recently, studies on the butterfly Danaus plexippus have been fundamental in characterizing the interplay between the circadian clock and navigation during the seasonal migration of this species. Moreover, the advent of Next Generation Omic technologies has resulted in the production of many publicly available datasets regarding circadian clocks in pest and beneficial Lepidoptera. This review presents an updated overview of the molecular and anatomical organization of the circadian clock in Lepidoptera. We report different behavioral circadian rhythms currently identified, focusing on the importance of the circadian clock in controlling developmental, mating and migration phenotypes. We then describe the ecological importance of circadian clocks detailing the complex interplay between the feeding behavior of these organisms and plants. Finally, we discuss how the characterization of these features could be useful in both pest control, and in optimizing rearing of beneficial Lepidoptera.

Bioprospecting of endophytes in medicinal plants of Thar Desert: An attractive resource for biopharmaceuticals

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Endophytes act as chemical synthesizers of the secondary metabolites of the host plant.

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Endophytic microflora has been isolated from a wide array of plants.

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It can serve as a good alternative source for pharmaceutically important compounds.

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The arid ecosystem of Thar Desert is a rich repository of ethnomedicinal plants.

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Role of endophytes in the synthesis of bioactive molecules used to enhance production.

Endophytes live asymptomatically within the healthy tissues of plant parts of the host, has grabbed the attention of ecologists, chemists, and researchers to have a broad spectral of biotechnological potential. It has been proven that almost all plants harbor endophytes within themselves. Numerous studies indicated that endophytes act as chemical synthesizers of the secondary metabolites of their host plant. Various medicinal plants of the Thar Desert have been used by the local folks of the Rajasthan to treat several diseases ailments for time immemorial. On the basis of their prior knowledge of ethnopharmacological usage of medicinally important plants of Thar Desert, several researchers directed their studies in search of endophytic microflora of such medicinally important plants for the discovery of novel bioactive molecules of pharmaceutical importance, for instance, taxol producing endophytic fungus Phoma sp. isolated from Calotropis gigantea as well as Aspergillus fumigatus, an endophytic fungus reported from Moringa oleifera demonstrated an effective antibiofilm, antimicrobial and antiproliferative activity. This review sheds light on the endophytic microflora of the ethnomedicinal plants of the Thar Desert and their biopotential as a promising source of pharmaceutically important naturally derived compounds.