BackgroundThe most critical step in the pearl formation during aquaculture is issued to the proliferation and differentiation of outer epithelial cells of mantle graft into pearl sac. This pearl sac secretes various matrix proteins to produce pearls by a complex physiological process which has not been well-understood yet. Here, we aimed to unravel the genes involved in the development of pearl sac and pearl, and the sequential expression patterns of different shell matrix proteins secreted from the pearl sac during pearl formation by pearl oyster Pinctada fucata using high-throughput transcriptome profiling.ResultsPrincipal component analysis (PCA) showed clearly different gene expression profiles between earlier (before 1 week) and later stages (1 week to 3 months) of grafting. Immune-related genes were highly expressed between 0 h – 24 h (donor dependent) and 48 h – 1 w (host dependent), and in the course of wound healing process pearl sac was developed by two weeks of graft transplantation. Moreover, for the first time, we identified some stem cell marker genes including ABCG2, SOX2, MEF2A, HES1, MET, NRP1, ESR1, STAT6, PAX2, FZD1 and PROM1 that were expressed differentially during the formation of pearl sac. The expression profiling of 192 biomineralization-related genes demonstrated that most of the shell matrix proteins (SMPs) involved in prismatic layer formation were first up-regulated and then gradually down-regulated indicating their involvement in the development of pearl sac and the onset of pearl mineralization. Most of the nacreous layer forming SMPs were up-regulated at 2 weeks after the maturation of pearl sac. Nacrein, MSI7 and shematrin involved in both layer formation were highly expressed during 0 h – 24 h, down-regulated up to 1 week and then up-regulated again after accomplishment of pearl sac formation.ConclusionsUsing an RNA-seq approach we unraveled the expression pattern of the key genes involved in the development of pearl sac and pearl as a result of host immune response after grafting. These findings provide valuable information in understanding the molecular mechanism of pearl formation and immune response in P. fucata.Electronic supplementary materialThe online version of this article (10.1186/s12864-019-5579-3) contains supplementary material, which is available to authorized users.
Asaduzzaman et al. Morphogenetic Divergence of Hilsa shad shad. The interaction of all of these forces and their relative strength in heterogeneous environments, however, made it rather challenging to determine the most probable selective pressure, which has shaped the Hilsa shad morphogenetic divergence across their diverse migratory habitats.
The present study was carried out to evaluate the dietary effects of host‐associated lactic acid bacteria on growth performance, metabolic enzyme activities, and immune response of Macrobrachium rosenbergii juveniles. To formulate the test diets, a control (Con) diet was supplemented with a commercial probiotic and three host‐derived bacteria Enterococcus faecalis (EC), Lactococcus lactis I (LC‐I), and L. lactis II (LC‐II), which were previously isolated from the gastrointestinal tract of adult individuals of M. rosenbergii. Juvenile M. rosenbergii (0.65 ± 0.008 g) were randomly stocked at 20 individuals/100 L of fiberglass tanks with three replications for each test diet. After 50 days, juveniles fed the diets LC‐I and LC‐II showed significantly higher (p < .05) weight gain, specific growth rate, and the lowest feed conversion ratio. The analyses of glutamic oxaloacetate transaminase and glutamic pyruvate transaminase in muscle and hepatopancreas revealed significantly (p < .05) reduced values in LC‐I fed juveniles. The total hemocyte count and phenoloxidase activity were significantly increased (p < .05) in LC‐I and LC‐II fed juveniles. The relative mRNA expression patterns of immune‐related α2‐M, LGBP, ProPO, Cu, Zn‐SOD, TG, PE, AKP, and ACP genes were significantly (p < .05) upregulated in juveniles fed with LC‐I followed by the diet LC‐II. Finally, the study suggests that the growth performance and immune response of M. rosenbergii can be improved through supplementation of host‐associated L. lactis bacteria for its higher production.
Tubificid worms are aquatic invertebrates, belonging to the class Oligochaeta and family Tubificidae, used as an important live food for fishes. The study was conducted to culture Tubificid worms under running water in order to develop a suitable culture media and an optimum duration of media inoculation for culturing Tubificid worms. The worms were cultured under two experiments in cemented culvert system (160×25×10 cm3) for 90 days. In the first experiment the worms were cultured in three different media designated as treatment-I, treatment-II and treatment-III. The highest yield (503.39±22.98 mg cm-2) was found at 70th day of culture duration in the culture media containing a mixture of 35% mustard oil cake, 20% wheat bran, 25% cow-dung and 20% fine sand (treatment-III). Only 1.99 kg media ingredients valued BDT 29.85 were needed to yield 1 kg worms. In the second experiment, the worms were cultured at three different intervals of media inoculation i.e., 6, 10 and 15 days interval designated as treatment-I, treatment-II and treatment-III respectively using the media found best in the first experiment. Inoculation of media at 10 days interval showed significantly (P<0.01) higher production (488.94±5.60 mg cm-2).DOI: http://dx.doi.org/10.3329/jbau.v10i2.14925 J. Bangladesh Agril. Univ. 10(2): 325-330, 2012
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