Several investigators suggest a relationship between neurotransmitters, serotonin (also called 5-hydroxytryptamine, 5-HT), and dopamine (DA) in the regulation of growth and reproductive development of vertebrate species, rather than the invertebrate species. In this study, we evaluated the role of 5-HT and DA in reproductive development of an invertebrate species, the freshwater crab Barytelphusa guerini. We tested the effects of 5-HT both alone and combined, and also the effects of an opioid antagonist naloxone, on reproductive development of B. guerini in terms of testicular and ovarian developmental parameters. Injection of either 5-HT or naloxone alone significantly increased the ovarian index and the oocyte diameter in female crabs, and the testicular index and testicular follicular diameter in male crabs. In contrast, injection of DA inhibited all the reproductive measures in both sexes. Co-injection of 5-HT with DA exhibited no significant effects on the reproductive development in both sexes compared to the control treatments. These results suggest that 5-HT, DA, and exogenous naloxone may be involved in the regulation of gonad stimulating hormone (GSH) and/or gonad inhibiting hormone (GIH). These results also provide evidence that naloxone may regulate endogenous neurotransmitters and its downstream hormones, GSH and GIH.

The frequent cases of dengue incidences are leading cause of illness and death in urban areas and Aedes albopictus (Skuse) is a primary vector for Dengue transmission in India. Synthesis of leaf mediated silver nanoparticles especially with Pongamia pinnata is a potential substitute for the existing organophosphorus insecticides like Tenophos, malathion and fenthion etc., for mosquito control programme. The nanoparticles were characterized by UV-visible absorption spectrum, X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) and Transmission Electron Microscopy (TEM). Analysis of TEM showed that the synthesized silver nanoparticles are in spherical shape with average size of 20 nm. Further the XRD analysis confirms the nano-crystalline phase of silver with face centred cubic (FCC) crystal structure. GC-MS analysis elucidated the presence of two active ingredients, such as 9-Octadecenoic acid (Z) and n-hexadecanoic acid, which are the prominent substances considered as larvicide. Larvae were exposed to varying concentrations of plant extracts and synthesized silver nanoparticles for 24 hours. From the results, it is found that plant extracts showed moderate larvicidal effects but, the synthesized silver nanoparticles had found to be toxic to larvae at LC50 (0.25 ppm) and LC 90 (1 ppm).

The tentative elucidation of the 3D-structure of vitellogenesis inhibiting hormone (VIH) peptides is conversely underprivileged by difficulties in gaining enough peptide or protein, diffracting crystals, and numerous extra technical aspects. As a result, no structural information is available for VIH peptide sequences registered in the Genbank. In this situation, it is not surprising that predictive methods have achieved great interest. Here, in this study the molt-inhibiting hormone (MIH) of the kuruma prawn (Marsupenaeus japonicus) is used, to predict the structure of four VIHrelated peptides in the crustacean species. The high similarity of the 3D-structures and the calculated physiochemical characteristics of these peptides suggest a common fold for the entire family.

The crustaceans produce several related peptides that belong to the crustacean hyperglycemic hormone (CHH) family. While these peptides have similar amino acid sequences, they have diverse biological functions that must arise, in part, from differences in the 3D shape of these peptides. However, it is generally accepted that peptides with a high degree of sequence similarity also have a similar 3-D structure. We used the solution structure of one peptide in the crustacean hyperglycemic hormone family, the molt-inhibiting hormone of the kuruma prawn (Marsupenaeus japonicus), to predict the shape of the five known peptides related to CHH in the Pacific white shrimp, Litopenaeus vannamei. The high similarity of the 3-D structures of these peptides suggests a common fold for the entire family. Nevertheless, minor differences in the shape of these peptides were observed, which may be the basis for their different biological properties.

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