In arthropods, it is known that ecdysteroids regulate molting, limb regeneration, and reproduction through activation of the ecdysone receptor (EcR). However, the ecdysteroid signaling pathway for promotion of ovarian development in crustaceans is still unclear. In this study, three cDNA isoforms of EcR were cloned from the mud crab Scylla paramamosain. qRT-PCR revealed that the SpEcR mRNA was abundant in the eyestalk, ovary and epidermis. During ovarian development, the SpEcR transcripts increased from stage I (undeveloped stage) and reached a peak at stage IV (late vitellogenic stage) before dropping to a lower level at stage V (mature stage). Meanwhile, levels of 20-hydroxyecdysone (20E) in the hemolymph, detected by HPLC-MS, displayed a similar pattern of increase with ovarian development. Results from in situ hybridization indicated that SpEcR mRNA was present in the follicular cells during vitellogenesis. Results from in vivo experiments revealed that 20E at 0.2 mg/g body weight significantly stimulated the expression of SpEcR and vitellogenin (SpVg) in female crabs during the early vitellogenic stage but not during the previtellogenic stage. This was confirmed by results from in vitro experiments which indicated that SpEcR and SpVg expression levels were significantly upregulated in early vitellogenic ovarian explants incubated with 5.0 mM 20E at 3 and 6 h but not in previtellogenic ovarian explants. Finally, results from in vitro gene silencing experiments indicated that the expression of SpEcR and SpVg in the ovary was significantly inhibited by SpEcR dsRNA. All these results together indicated that in S. paramamosain, 20E, and SpEcR, located in the follicular cells, play important roles in the promotion of ovarian development via regulating the expression of SpVg.

Among many improved convolutional neural network (CNN) architectures in the optical image classification, only a few were applied in synthetic aperture radar (SAR) automatic target recognition (ATR). One main reason is that direct transfer of these advanced architectures for the optical images to the SAR images easily yields overfitting due to its limited data set and less features relative to the optical images. Thus, based on the characteristics of the SAR image, we proposed a novel deep convolutional neural network architecture named umbrella. Its framework consists of two alternate CNN-layer blocks. One block is a fusion of six 3-layer paths, which is used to extract diverse level features from different convolution layers. The other block is composed of convolution layers and pooling layers are mainly utilized to reduce dimensions and extract hierarchical feature information. The combination of the two blocks could extract rich features from different spatial scale and simultaneously alleviate overfitting. The performance of the umbrella model was validated by the Moving and Stationary Target Acquisition and Recognition (MSTAR) benchmark data set. This architecture could achieve higher than 99% accuracy for the classification of 10-class targets and higher than 96% accuracy for the classification of 8 variants of the T72 tank, even in the case of diverse positions located by targets. The accuracy of our umbrella is superior to the current networks applied in the classification of MSTAR. The result shows that the umbrella architecture possesses a very robust generalization capability and will be potential for SAR-ART.

Arginine kinase (AK) is a phosphor‐transferase which plays a critical role in energy metabolism in invertebrates. Using reverse transcription‐polymerase chain reaction (RT‐PCR) and rapid amplification of cDNA ends (RACE) PCR, this study successfully cloned a 1469 bp full‐length complementary DNA (cDNA) of AK from the mud crab, Scylla paramamosain (designated as SpAK). The open‐reading frame (ORF) of SpAK was 1071 bp, encoding 357 amino acids. The predicted protein showed a high level of identity to known AK from other invertebrates and creatine kinase (CK) from vertebrates that belongs to a conserved family of ATP: guanidine phosphotransferases. The SpAK gene contains two exons and one intron. The quantitative real‐time PCR analysis revealed a broad expression of SpAK in various tissues. After challenge with the bacterium Vibrio alginolyticus, the peak value of AK expression in hepatopancreas increased 17‐fold (at 3 h), and 15‐fold (at 72 h) in hemolymph, as compared to the control. The present research suggests that AK might be involved in immune response of the mud crab, S. paramamosain.

Chymotrypsin is one of the serine proteases families that have various biological functions. A chymotrypsin gene was isolated from hepatopancreas of the mud crab, Scylla paramamosain (designated SpCHY) in this study. The full-length cDNA of SpCHY contained 942 nucleotides with a polyadenylation sequence and encoded a peptide of 270 amino acids with a signal peptide of 17 amino acids. The SpCHY gene contains seven exons, six introns, a TATA box and several transcription factor binding sites that were found in 5’-promoter region which is 1221 bp in length. Real-time quantitative PCR analysis indicated that the expression level of SpCHY mRNA in hepatopancreas was significantly higher than that in other tissues. Immunocytochemistry and in situ hybridization exhibited the CHY-like reactivity presented in resorptive cells of the hepatopancreas. After bacterial challenge with Vibrio alginolyticus, the expression level of SpCHY mRNA was extremely up-regulated at 3 h in hepatopancreas. Our results suggest that SpCHY might play an important role in the mud crab’s immune response.

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