Lophotrochozoan species exhibit wide morphological diversity; however, the molecular basis underlying this diversity remains unclear. Here, we explored the evolution of Notch pathway genes across 37 ...metazoan species via phylogenetic and molecular evolutionary studies with emphasis on the lophotrochozoans. We displayed the components of Notch pathway in metazoans and found that Delta and Hes/Hey-related genes, as well as their functional domains, are duplicated in lophotrochozoans. Comparative transcriptomics analyses allow us to pinpoint sequence divergence of multigene families in the Notch signalling pathway. We identified the duplication mechanism of a mollusc-specific gene, Delta2, and found it displayed complementary expression throughout development. Furthermore, we found the functional diversification not only in expanded genes in the Notch pathway (Delta and Hes/Hey-related genes), but also in evolutionary conservative genes (Notch, Presenilin, and Su(H)). Together, this comprehensive study demonstrates conservation and divergence within the Notch pathway, reveals evolutionary relationships among metazoans, and provides evidence for the occurrence of developmental diversity in lophotrochozoans, as well as a basis for future gene function studies.
To study the effects of Bacillus lincheniformis feeding frequency on the survival and growth of Haliotis discus hannai abalone, we measured the expression levels of nonspecific immune genes and ...monitored the anti-Vibrio parahaemolyticus immune reaction. H. discus hannai (shell length: 32.75 ± 2.63 mm, body weight: 4.91 ± 0.34 g) was selected to perform a 70 d laboratory culture experiment including a 14 d V. parahaemolyticus artificial infection experiment. The control group (C) was fed normal commercial feed every day. The M1 experimental group was given experimental feed and basal feed on alternating days until the end of the experiment. The M2 experimental group was given experimental feed for 4 d and basal feed for 3 d, and this cycle was repeated every 7 d until the end of the experiment. The M3 experimental group was given experimental feed for 2 d and basal feed for 5 d, and this cycle was repeated every 7 d until the end of the experiment. The M4 group was continuously given experimental feed for the duration of the experiment. The concentration of added B. lincheniformis in each experimental group was 105 cfu/g (according to the quantity of viable bacteria). The specific growth rate (as measured by body weight) and the feed conversion efficiency of the abalone in M1 and M2 were significantly higher than those in M4 and C (P < 0.05). The cellulose and lipase activities of abalone in M1, M2 or M4 were significantly higher than those in M3 or C (P < 0.05). The acid phosphatase, superoxide dismutase, total haemocyte counts, O2− levels generated by respiratory bursts, and the expression levels of Mn-SOD, TPx, GSTs and GSTm in abalone in the M2 group were significantly higher than those in any other feeding frequency group (P < 0.05). At the end of the V. parahaemolyticus infection, the cumulative mortality of the abalone in M2 was significantly lower than that in any other group (P < 0.05). Consequently, given the growth advantages and the enhancement of immune function, the feeding plan in which B. lincheniformis was applied for 4 d per week, and basal feed was then applied for 3 d, did not lead to a high level of immune reaction, immune fatigue or waste of resources, but increased the growth rate of individuals and their resistance to V. parahaemolyticus infection.
•Effects of the feeding frequency of B. lincheniformis on the survival and growth of abalones were evaluated.•B. lincheniformis was added 4 days a week, then the basal food was applied for 3 days to enhance the growth of abalones•B. lincheniformis was added 4 days a week, then the basal food was applied for 3 days to improve the immunity in abalones•B. lincheniformis was added 4 days a week, then the basal food was applied for 3 days to enhance the disease resistance.
Salinity is one of the critical ecological factors which will impact the growth and development of marine shellfish. With the rapid expansion of aquaculture area for
Haliotis discus hannai
, the ...frequent summer rainstorms in South China, the influx of freshwater, or the strong volatility of seawater in coastal areas, inner bays have placed abalone into the dynamic environment where the salinity is changing drastically. This work examined the effects of sudden salinity changes on abalone’s survival, osmotic pressure regulation, energy metabolism, and related gene expression by simulating the salinity changes of water for breeding
H. discus hannai
caused by heavy storm. The salinity was gradually reduced from 30 to 20, then kept at 20 for 48 h, followed by gradual increase to 30, and was kept at 30 for 48 h. Samples were taken at 6, 12, 36, 60, 66, 72, 96, and 120 h after the start of the experiment, respectively. Results showed that the survival rate of abalone at 120 h was significantly lower than that at any other time except at 96 h (
P
< 0.05). With the decrease and increase of salinity, the hemolymph osmotic pressure and the concentration of Na
+
, K
+
, Ca
2+
, Cl
−
in the hemolymph also followed the same trend, while the concentration of hemocyanin, total soluble protein, taurine, and free amino acids showed an inverse trend. The activity of Na
+
/K
+
-ATPase also increased then declined with salinity changes. Except at 0, 6, and 12 h, the activity of Na
+
/K
+
-ATPase in the salinity-changing group was significantly higher than that in the control group (
P
< 0.05). In the salinity-changing group, the activity of pyruvate kinase, succinate dehydrogenase, and malate dehydrogenase reached a maximum at 72 h, but no significant difference was found at the end of the experiment compared to the control group (
P
> 0.05). The expression levels of catalase, thioredoxin peroxidase, sigma-glutathione-
s
-transferase, and Mu-glutathione-
s
-transferase significantly rose with the salinity changes, and were significantly higher than that in the control group up to the end of the experiment (
P
< 0.05). As sudden salinity changes may cause some abalone deaths, the enhanced activity of related enzymes and the increase of gene expression levels might be one of the effective methods for an organism to respond to salinity stress and regulate osmotic pressure.
The effects of a diet containing the probiotic Bacillus amyloliquefaciens on the survival and growth of Haliotis discus hannai were evaluated by measuring growth and hematological parameters and the ...expression levels of nonspecific immune genes. In addition, the abalone's response to Vibrio parahaemolyticus infection was assessed. H. discus hannai (shell length: 29.35 ± 1.81 mm, body weight: 4.28 ± 0.23 g) were exposed to an 8-week culture experiment in indoor aquariums and a 2-week V. parahaemolyticus artificial infection experiment. In each experiment, the control group (C) was fed daily with the basal feed; the experimental groups were fed daily with the experimental feed, prepared by spraying B. amyloliquefaciens onto the basal feed at final concentrations of 103 (group A1), 105 (A2), and 107 (A3) cfu/g. The survival rate, body weight specific growth rate, and food conversion efficiency in A2 and A3 were significantly higher than those in A1 and C (P < 0.05). The total number of blood lymphocytes, the O2− and NO levels produced from respiratory burst, the activities of acid phosphatase, superoxide dismutase, and catalase, and the expression levels of catalase and thiol peroxidase in A2 were not significantly different from those in A3, but these factors were significantly higher in A2 compared to A1 and C (P < 0.05). The total antioxidant capacity and expression levels of glutathione S-transferase in A1, A2 and A3 were significantly higher than those in C (P < 0.05). At day 9 after infection with V. parahaemolyticus, all abalone in C were dead; at the end of the experiment, the cumulative mortality of abalone in A2 was significantly lower than that in any other group (P < 0.05). Thus, the experimental feed containing 105 cfu/g B. amyloliquefaciens not only facilitated the food intake and growth of abalone, but also effectively enhanced their non-specific immunity and resistance to V. parahaemolyticus infection. In this regard, B. amyloliquefaciens may be a useful probiotic strain for abalone aquaculture.
•Three different concentrations of B. amyloliquefaciens were added to the abalone's basal feed.•Dietary supplementation with B. amyloliquefaciens for 8 weeks enhanced abalones growth.•Dietary B. amyloliquefaciens at 105 cfu/g significantly improved immunity in abalones.•B. amyloliquefaciens enhanced disease resistance to V. parahemolyticus in abalones.
To examine the effects of stocking density on growth, food intake, and expression levels of related genes of Haliotis discus hannai Ino in recirculating aquaculture systems, abalones (shell length: ...38.42±2.31mm, weight: 7.04±0.89g) were cultured at three different stocking densities (high 1500/m2, medium 1000/m2, and low 600/m2, 4 replicates each) for 90d. At the end of the experiment, the survival rate and specific growth rate of weight of abalones in the high-density group were 86.5% and 0.14mg d−1, respectively, which were significantly lower than those in the low- and medium-density groups (P<0.05). The food intake of abalones in the low-density group was significantly higher than that in the medium- and high-density groups (P<0.05). At days 60 and 90, the food conversion efficiency of abalones in the medium-density group had declined, but it still was significantly higher than that in the high-density group (P<0.05). At the end of the experiment, the moisture and lactic acid contents of abalones in the high-density group were significantly higher than those in the low-density group. The protein content in the medium-density group decreased over time and became significantly lower than that in the low-density group at day 90 (P<0.05). The activities of pepsin and cellulase were significantly higher in the low- and medium-density groups than in the high-density group (P<0.05). At days 60 and 90, the activity of α-amylase in the low-density group was significantly higher than that in the medium-density group (P<0.05). At the end of the experiment, the expression levels of the polysaccharide cleavage enzyme genes Hdaly and Hdamyl in the low-density group had increased and were significantly higher than those in the medium- and high-density groups (P<0.05). The expression level of Hdlam in the high-density group was significantly lower than that in the medium-density group (P<0.05), whereas the expression level of Hdcel in the medium-density group was significantly lower than that in the low-density group (P<0.05). At the end of the experiment, the expression levels of catalase and glutathione S-transferase in the high-density group were significantly higher than levels in the medium- and low-density groups (P<0.05). Overall, although food was readily available in this study, abalones had to first search for food and then spend time feeding and ingesting it. For some individuals, such as those in the corners of the tank or under a stack of other abalones, access to food was restricted. Moreover, extra energy expenditure was required to resist oxidative damage. These were the main reasons for the observed slowdown of abalone growth and the increased mortality rate observed in this study.
•The differences in growth and food intake of H. d. hannai cultured at different stocking densities were initially analyzed using molecular biological methods;•This experiment was carried out in a proprietary multi-layer and cubic RAS;•Although food was readily available in this study, abalones had to first search for food and then spend time feeding and ingesting it. For some individuals, such as those in the corners of the tank or under a stack of other abalones, access to food was restricted. Moreover, extra energy expenditure was required to resist oxidative damage. These were the main reasons for the observed slow down of abalone growth and the increased mortality rate observed in this study.
In order to examine the effects of stocking density on growth, food intake, energy budget, and expression levels of related genes of the abalone Haliotis discus hannai Ino, specimens (mean±standard ...error shell length: 36.25±1.97mm, weight: 6.88±0.71g) were cultured at four different stocking densities (600, 900, 1200, and 1500ind/m2). Four replicates were set for each density, and the experimental period was 60days. At the end of the experiment, the survival rate, shell length, and weight specific growth rate of abalones in the 600 and 900ind/m2 groups were significantly higher than in the 1200 and 1500ind/m2 groups (P<0.05). The food conversion rate of abalones in the 900ind/m2 group significantly increased compared with the other groups (P<0.05). The activity of hexokinase in the 1200 and 1500ind/m2 groups was significantly higher than that in 600 and 900ind/m2 groups (P<0.05). The activity of pyruvate kinase in the 1500ind/m2 group showed no significant difference compared with the 900 and 1200ind/m2 groups (P>0.05), but was significantly higher than that in the 600ind/m2 group (P<0.05). In the 1200 and 1500ind/m2 groups, lactic dehydrogenase activity at Day 60 increased significantly compared with Day 30 (P<0.05). In the 900ind/m2 group, the energy accumulated for the growth was significantly higher than that in the 1200, and 1500ind/m2 groups (P<0.05), but there was no significant difference compared with the 600ind/m2 group (P>0.05). As the stocking density increased, expression levels of Mn-superoxide dismutase, catalase, glutathione-s-transferase, thioredoxin peroxidase, and heat shock protein 70 in the 1500ind/m2 group at the end of the experiment were significantly higher than in the other groups (P<0.05). At Day 30, the expression level of heat shock protein 90 in the 1200ind/m2 group showed no significant difference compared with the 1500ind/m2 group (P>0.05), but it was significantly lower than that in the 1500ind/m2 group at the end of the experiment (P>0.05). In the 1200 and 1500ind/m2 groups, the food availability was lower, levels of anaerobic metabolism increased, and more energy was required to resist oxidative damage; therefore, no energy was accumulated for growth. When the stocking density was 900ind/m2, the survival rate of abalones was the highest with fast growth, the density factor didn't cause oxidative stress to the organism, and more food-derived energy were accumulated and used for the growth of abalones. Considering aquaculture production output and business profitability, it would be more appropriate to control the stocking density at 900ind/m2 for abalones with a shell length of 3–4cm.
•Differences in growth and food intake of H. discus hannai at different stocking densities were initially examined;•Characteristics of abalone energy metabolism at different stocking densities were investigated;•Decreased abalone growth rate and increased mortality in high-density conditions are primarily attributed to reduced food availability.
This study investigated the effects of different light cycles on growth, food intake, energy budget, and related gene expression of the abalone Haliotis discus hannai Ino. Abalones (mean±standard ...error shell length: 30.28±1.64mm, body weight: 4.51±0.49g) were exposed to the following light cycles: 0L:24D, 4L:20D, 8L:16D, 12L:12D, and 16L:8D for 60days, four repetitions were provided for each light cycle. At the end of the experiment, there was no significant difference in shell length or body weight growth rate between 0L:24D and 4L:20D (P>0.05), the values of which were significantly higher than in 16L:8D (P<0.05). In 0L:24D, abalone food intake was significantly higher compared with in the other groups (P<0.05), but the food conversion efficiency was significantly lower than in 4L:20D (P<0.05). At the end of the experiment, in 16L:8D, the activity of hexokinase was significantly higher than in any other group (P<0.05), but in 12L:12D and 16L:8D, it significantly increased compared with Day 30 (P<0.05). In 0L:24D, 4L:20D, and 8L:16D, cellulase and pyruvate kinase activity was significantly higher than in 12L:12D and 16L:8D (P<0.05). There was no significant difference in the energy acquired from food in 0L:24D and 4L:20D (P>0.05). However, the energy loss via feces and respiratory metabolism in 0L:24D was significantly higher than in 4L:20D (P<0.05); therefore, the energy accumulated for individual growth was significantly lower than in 4L:20D (P<0.05). Although the energy loss via feces, excretion, and respiratory metabolism was significantly lower in 16L:8D compared with 0L:24D, 4L:20D, and 8L:16D, the ratio of the energy loss via feces and respiratory metabolism to the energy acquired from food intake was significantly higher than in any other group (P<0.05); therefore, the net growth efficiency K2 was significantly lower (P<0.05). In 16L:8D, gene expression levels of manganese superoxide dismutase (Mn-SOD), catalase (CAT), TPx, heat shock protein (HSP) 26, HSP70, and HSP90 were significantly higher than in any other group (P<0.05). At the end of the experiment, Mn-SOD, CAT, and HSP70 expression in 16L:8D significantly increased compared with Day 30 (P<0.05). Therefore, considering aquaculture production and business costs, it would be appropriate to select the light cycle of 4L:20D for the culture of H. d. hannai.
•Differences in growth and food intake of H. d. hannai at different light cycles were initially examined using a bioenergetics and molecular biology method.•Food intake and energy metabolism in the abalone H. d. hannai exposed to different light cycles were investigated by observing changes in digestive and metabolic enzyme activity.•Under a light cycle of 4L:20D, more energy was acquired from food, but less energy was lost via feces and respiratory metabolism, and none of the extra energy budget was used to resist against oxidative damage. Consequently, greater energy accumulation could be used for individual growth.
Worldwide, the bivalve aquaculture industry has realized or recognized the potential gains from selective breeding programs using phenotypic and pedigree data. Yesso scallop
Patinopecten yessoensis
...are among the most important commercial shellfish in China. A family-based breeding program to investigate the genetic variations for growth and survival-related traits at suspended and bottom environments of sea-based culture systems was reported in this study. We proposed and conducted a novel phenotyping technique to longitudinally evaluate the shell heights in the yesso scallop. At harvest after rearing for 20 months, the individual shell heights at 6, 10, 16, and 20 months were simultaneously obtained by the growth rings in the outer shells of the animals. Meanwhile, the body weight (BW) of the survived individuals at harvest was also recorded. Variance components and genetic parameters for growth and survival-related traits were estimated using an animal and threshold model, respectively. In the suspended environment, the heritability estimates for BW and shell heights at specific ages ranged from moderate to high (0.328–0.853). The estimated correlations between shell heights at contiguous ages were consistently high, ranging from 0.890 to 0.958 but decreased with increasing intervals between ages (0.496–0.828). The estimated correlations between shell heights at contiguous ages and BW at harvest were similar, ranging from 0.535 to 0.983. The heritability estimates for individual survival at harvest were at a low level of 0.128 by the probit-threshold model. While at the bottom environment, estimates of heritability for growth and survival-related traits were similar but slightly lower than those at the suspended environment. Furthermore, the genetic correlation for BW between the two environments was very small, which probably indicates genotype-by-environment interaction effects for growth in the yesso scallop. The study can provide prior information, which might develop a new idea for selection in this species. The results are discussed concerning selection work with yesso scallop, and solutions for accurate estimation of genetic parameters and increasing genetic gain are also outlined.
This study investigated the effects of different flow velocities in a circulating aquaculture system on growth, food intake, and related gene expression of the abalone Haliotis discus hannai Ino. ...Abalones (shell length: 41.39±2.85mm, body weight: 8.19±0.66g) were cultured at three flow velocities; high-velocity (400L/h), medium-velocity (300L/h), and low-velocity (200L/h) during the course of the experiment. Four repeats of each flow velocity were conducted over an experimental cycle of 90days. Results showed that the survival and specific growth rate of abalones in the 200L/h group were significantly lower than in any other group at the end of the experiment, while total ammonia nitrogen and NO2‑N concentration in the water was significantly higher than that in any other group (P<0.05). Food intake, food conversion efficiency, protein content, pepsin, and α-amylase activity of abalones in the 300L/h group were significantly higher than in the 200 and 400L/h groups (P<0.05), but there was no significant difference identified between 200 and 400L/h groups (P>0.05). Although no significant difference was identified between 300 and 400L/h groups with respect to cellulase activity or the expression levels of Hdaly, both were significantly higher than in the 200L/h group (P<0.05). In the 400L/h group, hexokinase and pyruvate kinase activity, and lactic acid content were significantly higher compared with in the 300L/h group (P<0.05). The ash and fat contents of abalones in the 200L/h group were significantly lower than in any other group, but moisture content was significantly higher (P<0.05). At Day 90, the expression levels of Hdamyl, Hdlam, and Hdcel in the 300L/h group were significantly higher than in any other group (P<0.05), and compared with Day 45, the expression levels of were Hdamyl significantly increased (P<0.05). Although no significant difference was identified between 200 and 400L/h groups with respect to the expression levels of Mn-SOD and CAT, both were significantly higher than those in the 300L/h group (P<0.05). Therefore, control of flow velocity at 300L/h will not only stimulate the food intake and growth of abalones, but also reduce energy consumption to resist against water flow impact and avoid oxidative damage due to water quality deterioration. This will be beneficial for abalone health and will improve aquaculture production.
•Differences in growth of H. d. hannai at different flow velocities were initially examined using molecular biology method.•This experiment was carried out in a proprietary multi-layer and cubic RAS.•At low flow velocity, TAN and NO2-N concentrations increased, resulting in abnormal abalone metabolism.•At high flow velocity, abalones generated more energy to resist the impact of water currents through glycolysis.
The interplay between divergence and phenotypic plasticity is critical to our understanding of a species' adaptive potential under rapid climate changes. We investigated divergence and plasticity in ...natural populations of the Pacific oyster Crassostrea gigas with a congeneric oyster Crassostrea angulata from southern China used as an outgroup. Genome re-sequencing of 371 oysters revealed unexpected genetic divergence in a small area that coincided with phenotypic divergence in growth, physiology, heat tolerance and gene expression across environmental gradients. These findings suggest that selection and local adaptation are pervasive and, together with limited gene flow, influence population structure. Genes showing sequence differentiation between populations also diverged in transcriptional response to heat stress. Plasticity in gene expression is positively correlated with evolved divergence, indicating that plasticity is adaptive and favoured by organisms under dynamic environments. Divergence in heat tolerance-partly through acetylation-mediated energy depression-implies differentiation in adaptive potential. Trade-offs between growth and survival may play an important role in local adaptation of oysters and other marine invertebrates.
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