Assessment of black soldier fly (Hermetia illucens) larvae meal as a potential substitute for soybean meal on growth performance and flesh quality of grass carp Ctenopharyngodon idellus.

A 90-day feeding trial was conducted to assess the effects of black soldier fly larvae meal (BSFLM) as a replacement for soybean meal (SM) on growth performance and flesh quality of grass carp. A total of 420 grass carp (299.93 ± 0.85 g) were randomly divided into 7 groups (triplicate) and fed 7 diets with SM substitution of 0% (SM, control), 15% (BSFLM15), 30% (BSFLM30), 45% (BSFLM45), 60% (BSFLM60), 75% (BSFLM75) and 100% (BSFLM100) by BSFLM. The growth performance of grass carp in the BSFLM75 and BSFLM100 groups were significantly lower compared to other groups (P < 0.05). The mid-gut villus height was the lowest in the BSFLM100 group (P < 0.05). Muscle nutritional value was improved due to increased DHA (docosahexaenoic acid), EPA (eicosapentaenoic acid), total HUFA (highly unsaturated fatty acids) and glycine levels, and reached the optimum in the BSFLM100 group (P < 0.05). According to the results of principal component analysis and weight analysis of muscle texture and body color, all the BSFLM diets except BSFLM15 could improve muscle texture and body color and reached the optimum level in the BSFLM100 group. Muscle drip loss and hypoxanthine content were the lowest and muscle antioxidant capacity was the highest in the BSFLM75 group, and water- and salt-soluble protein contents reached the optimum level in the BSFLM60 group (P < 0.05). Dietary BSFLM significantly reduced muscle fiber area and diameter, and increased muscle fiber density and the proportion of small fiber (diameter <20 µm) (P < 0.05). Additionally, sarcomere lengths in the BSFLM75 and BSFLM100 groups were significantly higher than that in the SM group (P < 0.05). The mRNA relative expression levels of MyoD, Myf5, MyHC and FGF6b were remarkably up-regulated at an appropriate dietary BSFLM level (P < 0.05). In conclusion, BSFLM could replace up to 60% SM without an adverse effect on growth performance and improve the flesh quality of grass carp. The optimum levels of dietary BSFLM were 71.0 and 69.1 g/kg diet based on the final body weight and feed conversion ratio. The flesh quality was optimal when dietary SM was completely replaced with BSFLM (227 g/kg diet).

Co-attention enabled content-based image retrieval.

Content-based image retrieval (CBIR) aims to provide the most similar images to a given query. Feature extraction plays an essential role in retrieval performance within a CBIR pipeline. Current CBIR studies would either uniformly extract feature information from the input image and use it directly or employ some trainable spatial weighting module which is then used for similarity comparison between pairs of query and candidate matching images. These spatial weighting modules are normally query non-sensitive and only based on the knowledge learned during the training stage. They may focus towards incorrect regions, especially when the target image is not salient or is surrounded by distractors. This paper proposes an efficient query sensitive co-attention1 mechanism for large-scale CBIR tasks. In order to reduce the extra computation cost required by the query sensitivity to the co-attention mechanism, the proposed method employs clustering of the selected local features. Experimental results indicate that the co-attention maps can provide the best retrieval results on benchmark datasets under challenging situations, such as having completely different image acquisition conditions between the query and its match image.

Size-resolved gas-particle partitioning characteristics of typical semi-volatile organic compounds in urban atmosphere.

Understanding particle size distribution and size-resolved gas-particle partitioning of semi-volatile organic compounds (SVOCs) is important for characterizing their fate in atmosphere. However, the size-resolved gas-particle partitioning characteristics of SVOCs has not been adequately considered. To address this issue, the present study collected gaseous and size-fractioned particulate samples both in and outside of schools, offices, and residences in three districts of different urbanization levels in a megacity, Guangzhou, South China during two seasons. Typical SVOCs, including 15 polycyclic aromatic hydrocarbons (PAHs), six organophosphate esters and seven phthalic acid esters were measured. Emission sources, physicochemical properties, and environmental conditions at the sampling sites considerably impacted the spatiotemporal distribution patterns and particle size distribution of target SVOCs. Not all observed gas-particle partition coefficients (Kp) of target SVOCs were negatively correlated with subcooled liquid-vapor pressures (PL0), probably because certain factors, such as the non-exchangeable part of the particle-bound SVOCs, were not considered in traditional gas-particle partition theories. Particle size was an important factor affecting gas-particle partitioning. Adsorption was the dominant mechanism for PAHs with high molecular weight in different particle modes. A new model was established to predict size-resolved Kp of PAHs with high molecular weight based on PL0 and particle size.

Glycogen synthase kinase-3ß (GSK-3ß) of grass carp (Ctenopharyngodon idella): Synteny, structure, tissue distribution and expression in oleic acid (OA)-induced adipocytes and hepatocytes.

Glycogen synthase kinase-3ß (GSK-3ß) plays a crucial role in regulating lipid metabolism, endoplasmic reticulum (ER) stress and apoptosis in mammals, however, its gene structure and function is little known about in fish. Here, its two paralogs, grass carp (Ctenopharyngodon idella) GSK-3ß1 and GSK-3ß2 were isolated and characterized, encoding peptides of 421 and 457 amino acids, respectively. These two paralogs may have originated from the teleost-specific genome duplication (TSGD) event. Alignment of grass carp GSK-3ß deduced amino acid sequences with select teleost species showed that the protein is conserved. However, two paralogs of the GSK-3ß had great variation in gene structure: the GSK-3ß1 contained eleven exons while the GSK-3ß2 contained nine exons. The two paralogs were expressed in a wide range of tissues, GSK-3ß1 was most expressed in adipose tissue, GSK-3ß2 was most expressed in liver. In OA-induced adipocytes and hepatocytes, we found that GSK-3ß1 mRNA expression was significantly increased only in adipocytes, while the mRNA expression of GSK-3ß2 was dramatically increased both in adipocytes and hepatocytes. These results provide evidence that the GSK-3ß may participate in the process of lipid accumulation in OA-induced adipocytes and hepatocytes of grass carp.