Although the regulation of vitellogenesis in insects has been mainly discussed in terms of ‘classical’ lipid hormones, juvenile hormone (JH), and 20-hydroxyecdysone (20E), recent data support the notion that this process must be adjusted in harmony with a nutritional input/reservoir and involvement of certain indoleamines and neuropeptides in regulation of such process. This study focuses on crosstalks among these axes, lipid hormones, monoamines, and neuropeptides in regulation of vitellogenesis in the American cockroach Periplaneta americana with novel aspects in the roles of arylalkylamine N-acetyltransferase (aaNAT), a key enzyme in indoleamine metabolism, and the enteroendocrine peptides; crustacean cardioactive peptide (CCAP) and short neuropeptide F (sNPF). Double-stranded RNA against aaNAT (dsRNAaaNAT) was injected into designated-aged females and the effects were monitored including the expressions of aaNAT itself, vitellogenin 1 and 2 (Vg1 and Vg2) and the vitellogenin receptor (VgR) mRNAs, oocyte maturation and changes in the hemolymph peptide concentrations. Effects of peptides application and 20E were also investigated. Injection of dsRNAaaNAT strongly suppressed oocyte maturation, transcription of Vg1, Vg2, VgR, and genes encoding JH acid- and farnesoate O-methyltransferases (JHAMT and FAMeT, respectively) acting in the JH biosynthetic pathway. However, it did not affect hemolymph concentrations of CCAP and sNPF. Injection of CCAP stimulated, while sNPF suppressed oocyte maturation and Vgs/VgR transcription, i.e., acting as allatomedins. Injection of CCAP promoted, while sNPF repressed ecdysteroid (20E) synthesis, particularly at the second step of Vg uptake. 20E also affected the JH biosynthetic pathway and Vg/VgR synthesis. The results revealed that on the course of vitellogenesis, JH- and 20E-mediated regulation occurs downstream to indoleamines- and peptides-mediated regulations. Intricate mutual interactions of these regulatory routes must orchestrate reproduction in this species at the highest potency.

Melatonin (MEL) orchestrates daily and seasonal rhythms (eg, locomotion, sleep/ wake cycles, and migration among other rhythms) in diverse organisms. We investigated the effects of pharmacological doses (0.03-1 mM) of exogenous MEL intake in the cockroach, Periplaneta americana, on locomotor activity. As per os MEL concentration increased, cockroach locomotor rhythm in light-dark (LD) cycles became more synchronized. The ratio of night activity to 24-h activity increased and the acrophase (peak) slightly advanced. MEL application also influenced total activity bouts in the free-running rhythm. Since MEL slightly influenced τ in the freerunning rhythms, it is not a central element of the circadian pacemaker but must influence mutual coupling of multi-oscillatory system components. Arylalkylamine N-acetyltransferase (aaNAT) regulates enzymatic production of MEL. aaNAT activities vary in circadian rhythms, and the immunoreactive aaNAT (aaNAT-ir) is colocalized with the key clock proteins cycle (CYC)-ir and pigment-dispersing factor (PDF)-ir These are elements of the central pacemaker and its output pathway as well as other circadian landmarks such as the anterior and posterior optic commissures (AOC and POC, respectively). It also partially shares immunohistochemical reactivity with PER-ir and DBT-ir neurons. We analyzed the role of Pamericana aaNAT1 (PaaaNAT1) (AB106562.1) by injecting dsRNA aaNAT1 . qPCR showed a decrease in accumulations of mRNAs encoding PaaaNAT1. The injections led to arrhythmicity in LD cycles and the arrhythmicity persisted in constant dark (DD). Continuous administration of MEL resynchronized the rhythm after arrhythmicity was induced by dsRNA aaNAT1 injection, suggesting that PaaaNAT is the key regulator of the circadian system in the cockroach via MEL production. PaaaNAT1 contains putative E−box regions which may explain its tight circadian control. The receptor that mediates MEL 2 of 19 | KAMRUZZAMAN et Al How to cite this article: Kamruzzaman ASM, Hiragaki S, Watari Y, et al. Clock-controlled arylalkylamine N-acetyltransferase (aaNAT) regulates circadian rhythms of locomotor activity in the American cockroach, Periplaneta americana, via melatonin/MT2-like receptor.

Vitellogenesis in many insect species is triggered by juvenile hormone (JH) where other factors such as neural or endocrinological ones also play a important roles. Newly emerged adult females of the American cockroach, Periplaneta americana were injected with indoleamines such as tryptamine (Tn), N-acetyltryptamine (NATn), serotonin (5-HT), N-acetylserotonin (NAS) and melatonin (ME) at 20, 30 and 40 µg in the abdomen. Tn and NATn stimulated Vg synthesis, while 5-HT, NAS and ME inhibited it. These amines may exert the effect on either directly on Vg synthesis in the fat body, Vg receptor, follicle cells, or JH synthesis. We first cloned the genes encoding juvenile hormone acid O-methyltransferase (JHAMT) and farnesoic acid O-methyl transferase (FAMeT) which are involved in JH biosynthesis. qRT-PCR analysis revealed that indoleamines affected the expression of JHAMT and FAMeT in the Br-CA complex. 5-HT, NAS and ME inhibited JHAMT and FAMeT transcription, while Tn and NATn stimulated their transcription. The oocyte length and yolk accumulation showed that, Tn, more likely NATn induced oocyte maturation. Here, the result suggests that intricate mutual interactions induced Vg synthesis in the fat body during oocyte maturation between neurotransmitters/modulator pathway and JH synthesis pathways.

Yellow mite, Polyphagotarsonemus latus [Banks] (Acari: Tarsonemidae) is one of the major pests of jute crops (Corchorus capsularis L.) in Bangladesh. In this study, indigenous varieties of jute were used for treatments, namely, CVL-1, CVE-3, BJC-7370 and BJC-83. The paired plot treatments (treated and untreated controls) were laid out under field conditions. The effects of yellow mite were studied at three stages of the jute plants: 60 days after sowing (DAS), 90 DAS and 120 DAS. A higher number of mite stages was observed up to 90 DAS and then declined up to 120 DAS in var. BJC-7370 among two other varieties, Deshi and Tossa. The percentage of infestation and damage indexes (scale 0-5) were measured to relate yellow mite injuries to the number of leaves, leaf area, fresh leaf weight, dry leaf weight, soluble solids, plant height, base diameter, fiber weight, stick weight, number of flowers per plant, number of pods, pod weight per plant, seeds per pod, seed weight and 1000 seeds' weight of plants infested at three different phenological stages. The highest fiber yield loss was found in the variety BJC-7370 (59.75%), followed by BJC-83 (55.56%), CVE-3 (54.30%) and CVL-1 (50.05). The highest stick yield losses were found in the following order: BJC-7370 (54.54%) > BJC-83 (51.17%) > CVL-1 (43.68%) > CVE-3 (37.80%) and BJC-7370 (30.33%) > CVL-1 (27.83%) > BJC-83 (24.16%) > CVE-3 (22.11%) for the highest seed yield under field conditions for Corchorus capsularis. High yellow mite population in untreated checks decreased plant growth and showed significant losses in yield production for the variety BJC-7370.

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