Effects of carbon to nitrogen ratio (C:N) on water quality and growth performance of Litopenaeus vannamei (Boone, 1931) in the biofloc system with a salinity of 5%

This study aimed to investigate the effects of carbon to nitrogen ratio (C:N) on the water quality and shrimp growth performance during the grow-out culture of Litopenaeus vannamei in the biofloc system under a low salinity condition. Three biofloc treatments with an C:N (contained in the inputted feed and carbon source with the assumption that 75% of the feed nitrogen is excreted) of 8:1 (CN8), 16:1 (CN16) and 24:1 (CN24), respectively, were designed to stocking shrimp juveniles (≈ 0.8 g) at a density of 270 individuals m-3, for a 63-days culture experiment at a salinity of about 5‰. Results showed that in CN8 treatment, the levels of pH (6.9±0.1), carbonate alkalinity (104.0±2.8mg L-1 CaCO3), biofloc volume (4.8±0.9mL L-1) and TSS (327.4±24.4mg L-1) were significantly lower than those in the other two treatments (≥7.6±0.3, ≥157.6±21.6mg L-1 CaCO3, ≥24.1±3.7mL L-1 and ≥508.1±32.3mg L-1, P<0.05); whereas the levels of TAN (7.1±0.9mg L-1), nitrite (14.0±3.6mg L-1) and nitrate (77.0±5.0mg L-1) were significantly higher than those in the other treatments (≤2.0±0.6mg L-1, ≤4.9±3.1mg L-1 and ≤14.7±5.9mg L-1, P<0.05). The zootechnical parameters of shrimp were not significantly different between three treatments (P>0.05), except that the survival rates in CN16 treatment (96.8±2.0%) and CN24 treatment (93.7±4.2%) were significantly higher than that of CN8 treatment (81.5±6.4%, P<0.05). The results indicated that an inputted C:N higher than 16:1 was suitable for the biofloc system with a low salinity of 5‰, with an optimal inferred C:N range of 18.5-21.0:1 for water quality and growth performance.

Transfer of Pollutants from Macrocystis pyrifera to Tetrapygus niger in a Highly Impacted Coastal Zone of Chile

PAHs and heavy metals are characteristic pollutants in urbanized coastal areas, especially those with industrial activity. Given this context and the ability of Macrocystis pyrifera to drift when detached and provide trophic subsidy in coastal systems, we analyzed the potential transfer of pollutants to the herbivore Tetrapygus niger, through diet, in an industrialized coastal zone in Central Chile (Caleta Horcón) and characterized the impacted zone using diverse polluted ecotoxicological indices. For this purpose, a culture experiment was conducted where M. pyrifera individuals from Algarrobo (control site) were cultivated in Caleta Horcón and then used as food for T. niger. The contents of both PAHs and heavy metal contents were subsequently determined in algal tissue and sea urchin gonads as well as in the seawater. The results show that algae cultivated in Caleta Horcón had higher concentrations of naphthalene (NAF) compared to those from a low industrial impact zone (Algarrobo) (2.5 and 1.8 mg kg−1, respectively). The concentrations of Cu, As, and Cd were higher in Caleta Horcón than in Algarrobo in both M. pyrifera and T. niger. For all metals, including Pb, higher concentrations were present in T. niger than in M. pyrifera (between 5 and 798 times higher). Additionally, as indicated by the toxicological indices MPI (0.00804) and PLI (10.89), Caleta Horcón is highly contaminated with metals compared to Algarrobo (0.0006 and 0.015, respectively). Finally, the bioconcentration factor (BCF) and trophic transfer factor (TTF) values were greater than one in most cases, with values in Caleta Horcón exceeding those in Algarrobo by one or two orders of magnitude. This study provides evidence that Caleta Horcón is a highly impacted zone (HIZ) compared to Algarrobo, in addition to evidence that the biomagnification of certain pollutants, including the possible responses to contaminants, are apparently not exclusively transferred to T. niger through diet.

Variations in Biochemical Constituents for Tolerance to Nematode and Fusarium wilt Complex in Select Banana Hybrids

Banana is one of the most important fruit crops cultivated worldwide and its cultivation is hampered by infestation by nematode and Fusarium wilt complex. A pot culture experiment was conducted to study the change in biochemical constituents due to the inoculation of nematodes followed by Fusarium pathogen in select banana hybrids. The results indicated that the increase in production of defense-related compounds and enzymes such as total phenols, lignin, PO, PPO and PAL in the root tissues of inoculated plants. Among the four select banana hybrids, NPH-02-01 recorded high total phenol content (586.92 µg-1) and H 531 recorded high lignin content (1.58 %). Similarly the hybrid NPH-02-01 registered the higher activity of PO (3.5 abs.min-1.g-1), PPO (0.23 abs.min-1.g-1) and PAL (14.83 abs.min-1.g-1) when compared to other hybrids. The percentage increase of all the constituents in the hybrid NPH-02-01 was found to be comparatively higher with uninoculated plants and check cultivars.

Production performance of stinging catfish (Heteropneustes fossilis, Bloch) in monoculture at two different locations

An on-farm mono culture experiment was conducted for a period of four months from May to September 2014 to compare the growth and production of stinging catfish, Heteropneustes fossilis, at two different environmental conditions. Two locations were one in Gazipur Sadar (AEZ 28)and the other in Narsingdi Sadar (AEZ 9).At each location, there were five ponds of almost similar size and water depth. The stocking density was 500 fry per decimal for each location. Pre-stocking and post-stocking management were similar in both locations. There were considerable variations in most of the water and soil qualities between two locations. After four months of rearing, significantlyhigher (p<0.05) mean harvesting weight of H. fossilis (48.10±7.12 g) was observed in Narsingdi, as compared to that of Gazipur (23.18± 6.24 g).

Effects Of Seed Priming On Root- Shoot Behaviour And Stress Tolerance Of Pea (Pisum Sativum L.)

A pot culture experiment was carried out under controlled conditions for the detailed study of morphophysiological and advanced stress response adaptive mechanisms along with yield performance of pea varieties under the influence of seed priming substances. The performances of selected seed priming substances in different pea varieties were tested with water stress. Growth and physiological parameters documented at the stress period. From the experiment, it can be inferred that seed priming substances like KH2PO4 (1.5 and 3%), H2O2 (10 mM) and PEG (5%) were significantly outperformed in inducing higher growth with positive physiological changes. Bangladesh J. Bot. 50(2): 199-208, 2021 (June)

Nitrogen Attenuated Zinc-Mediated Promotion of Rice Tillering Under Low Temperature via Regulating Auxin and Cytokinin Balance

Background and aims Zinc (Zn) can improve rice resistance to abiotic stress and participate in IAA synthesis. The absorption of Zn is closely related to nitrogen (N) nutrition. However, little is known about the mechanisms by which Zn regulates rice low-temperature resistance and tillering recovery after low-temperature under different N levels. Methods Water culture experiment was conducted with two temperatures (22°C and 12°C), two N levels (1.43 mM and 2.86 mM NH4NO3), and three Zn levels (0.08 µM, 0.15 µM and 0.30 µM ZnSO4·7H2O). Results Low-temperature decreased rice tillering, which was further exacerbated at high N levels. Increasing Zn application could improve rice low-temperature resistance under normal N levels, enhance nutrient absorption, improve tiller bud cytokinin (CTK) concentration and CTK/IAA ratio, finally accelerate tillering recovery one week before normal Zn treatment. High N attenuated the contribution of Zn under low temperature, but moderate Zn was beneficial to tillering recovery by regulating the balance of tiller bud IAA and CTK concentration, and IAA transport. Conclusions Increasing Zn application improved rice tolerance to low-temperature stress and promoted tillering recovery, which was aggravated under high N levels. However, appropriate Zn application under high N level was conducive to breaking tiller dormancy and promoting tillering growth spurts when recovering to a normal temperature, which was related to the hormone balance and nutrient absorption synergistic regulation by N and Zn.

Bioaccumulation and phytotoxicity of ZnO nanoparticles in soil-grown Brassica chinensis and potential risks

A pot-culture experiment was carried out to explore the phytotoxicity and accumulation of ZnO nanoparticles (ZnO NPs) in pakchoi (Brassica chinensis), as well as its potential risk. Zn was mainly accumulated in the shoots of pakchoi and showed the order of cell wall fraction > soluble fraction > organelles fraction. Endosomes were observed in roots cell by transmission electron microscope (TEM) and it is proving that endocytosis is a possible way for NPs to enter the cells. The results showed that higher concentration of ZnO NPs treatments resulted in an increase in the content of photosynthetic pigments and malondialdehyde (MDA), Catalase (CAT) and ascorbate peroxidase (APX) activity, while the activity of superoxide dismutase (SOD) and guaiacol peroxidase (G-POD) decreased significantly compared with the control. These changes suggest that the mechanism of ZnO NPs phytotoxicity may induce strongly oxidative stress and damage biomembrane. Generally, ZnO NPs had a similar impact on the growth and absorption of Zn in pakchoi with Zn2+. Simultaneously, the treatment of ZnO NPs affected the nutritional quality and food safety of pakchoi at high concentration.

Butyric Acid Added Apically to Intestinal Caco-2 Cells Elevates Hepatic ApoA-I Transcription and Rescues Lower ApoA-I Expression in Inflamed HepG2 Cells Co-Cultured in the Basolateral Compartment

Apolipoprotein A-I (ApoA-I) concentrations are decreased during inflammation, which may reduce high-density lipoprotein (HDL) functionality. Thus, rescuing ApoA-I concentrations during inflammation might help to prevent atherosclerosis. Recent studies have shown that butyric acid (C4) has anti-inflammatory effects and rescues ApoA-I production. However, whether intestinal short chain fatty acids (SCFAs) are able to influence hepatic processes is unknown. Therefore, we investigated C4 anti-inflammatory effects on ApoA-I transcription in the intestine-liver co-culture model. C4 dose-response experiments in the presence or absence of cytokines were performed in a co-culture system including Caco-2 cells, HepG2 cells, or both. Changes in ApoA-I transcription in Caco-2 cells and HepG2 cells were analyzed using qPCR. C4 increased ApoA-I expression in HepG2 cells that cultured alone. When both cells were cultured together, C4 decreased ApoA-I expression in Caco-2 cells and increased ApoA-I expression in HepG2 cells. However, adding C4 to apical Caco-2 cells resulted in a smaller effect in HepG2 cells compared with adding C4 directly to the hepatocytes. Moreover, C4 rescued ApoA-I expression in inflamed HepG2 cells. These findings suggests that intestinal SCFAs can affect hepatic processes. However, the smaller effect in the co-culture experiment indicates cross-talk between intestine and liver.