Optimization of inclusion level of lipid in larval diet of Labeo rohita (Hamilton, 1822).

Formulation and preparation of larval feed according to the requirement of Indian major carp is a prerequisite for improving the survival (%) and growth during early developmental stages. A feeding trial of 50 days in a replicate of five was conducted to determine the optimal inclusion levels of fish oil (lipid) in the larval diet of Labeo rohita. Four isonitrogenous (50% CP) nanoparticulate diets with four lipid inclusion levels, L5 (5%), L7 (7%), L9 (9%), and L11 (11%) were prepared and fed to four groups of rohu (Labeo rohita) larvae. At the end of feeding trial, survival (%), growth performance, digestive enzyme activity, gut morphology, and expression of growth and feed intake genes were evaluated. All pairwise comparisons among groups indicated higher growth performance (weight gain, specific growth rate, and daily weight gain), survival (%), and IGF-1 gene expression of the L9 group followed by the L7 while the L11 showed poor performance even less than L5. All studied intestinal enzymes except amylase showed a similar trend. Amylase showed comparable results among L7, L9, and L5, while L11 showed the lowest value. The intestinal villi length also showed higher values in L9 followed by L7, and lowest in the L11 group. Feed intake regulating genes, leptin showed lipid inclusion level upregulation, while ghrelin showed the highest expression in the L9 group. Based on growth performance, gut morphology, intestinal enzyme activity, and gene expression analysis, 9% dietary lipid could be recommended to ensure the optimum growth and survival of L. rohita larvae.

Optimization of Selenium Inclusion Level in the Larval Diet of Labeo rohita.

The nutritional requirement of fish larvae remains a limiting factor in advanced aquaculture. Micronutrients are crucial for early development, but their dietary inclusion level in the larval feed of carps has not been standardized. The present study was executed to determine the optimum dietary inclusion level of organic and inorganic selenium in the larval feed of Rohu, Labeo rohita. A 35-day feeding trial in triplicate under semi-control conditions was conducted in 21 troughs divided into seven groups. Each trough (capacity 4.0 L) contained 200 larvae (average body weight 0.4 mg). The first group (control) was reared on nano-particulate basal diet (CP 50%), while three groups Se-Na(0.5), Se-Na(1), and Se-Na(1.5) were fed basal diet supplemented with graded levels (0.5-1.5 mg/kg diet) of inorganic form of Se, sodium selenite (Se-Na). The last three groups (Se-Met(0.5), Se-Met(1), and Se-Met(1.5)) were fed organic form of dietary Se, selenium methionine (Se-Met) at the same inclusion level as Se-Na. Results indicated the curvilinear relationship of dietary Se levels with body weight, activity of digestive enzymes (protease, amylase, lipases, and trypsin), and antioxidant enzymes (SOD, CAT, POD, and GSH-Px) activity, intestinal villi, width, and absorptive area. A positive correlation was observed with up to 0.5 and 1 mg/kg diet of Se-Na and Se-Met, respectively; however, above these levels, a negative impact was observed. The upregulation of growth hormone mediator (IGF-1) and downregulation of heat shock protein (HSP-70) also followed a similar trend in response to Se-Na and Se-Met inclusion. Based on the results, 1 mg/kg diet Se-Met could be considered the optimum level and is recommended for the early rearing of rohu larvae.

Effect of acclimated temperature on thermal tolerance, immune response and expression of HSP genes in Labeo rohita, Catla catla and their intergeneric hybrids.

The ability of a species and population to respond to a decrease or an increase in temperature depends on their adaptive potential. Here, the critical thermal tolerance (CTmax and CTmin) of four populations: Labeo rohita, Catla catla, and their reciprocal hybrids L. rohitaâ™€× C. catla♂ (RC) and C. catla♀ × L. rohita♂ (CR) being acclimatized at four acclimation temperatures (22, 26, 30 and 34 °C) were determined. All populations indicated substantial variations (P < 0.05) in CTmax and CTmin values. L. rohita displayed, comparatively the highest CTmax with largest total and intrinsic polygon zones as well as the upper and lower acquired thermal tolerance zones followed by RC and CR hybrids, while C. catla showed significantly the highest CTmin value and the smallest intrinsic and acquired thermal tolerance zones. Both hybrids illustrated low parent heterosis (≤11%). Additionally, the highest expression of Hsp70 and Hsp90 (heat shock proteins) genes, serum lysozyme level, respiratory burst activity and lowest lipid peroxidation level under lower and higher temperature shock further illustrated strong physiological mechanism of L. rohita in contrast to C. catla, to deal with acute temperature, while hybrids, especially F1 RC hybrid appeared as a good option to replace C. catla in relatively higher and lower temperature areas.

2D DNA lattice arrays assembled from DNA dumbbell tiles using poly(A-T)-rich stems.

Poly(A-T)-rich sequences have been applied as stems of DNA dumbbell tiles for construction of single crystalline 2D DNA lattice arrays in slightly acidic solutions. These arrays show much higher stability and better organised crystalline lattice structures than those assembled from DNA dumbbell tiles with randomly sequenced stems in slightly alkaline environments. DNA nanotechnology probably provides a useful platform to study the mechanical properties of DNA duplexes with specific sequences.

DNA dumbbell tiles with uneven widths for 2D arrays.

Small DNA tiles built from linear oligonucleotides for the construction of DNA nanostructures often have even widths in the lateral direction against the DNA helical axis. Herein we present an example of DNA dumbbell tiles with uneven widths between the central double helical stem and the two head loops after association with helper strands. A characteristic of DNA dumbbell tiles is that the stem length controls the stereostructure of the two head motifs. A stem at 11 bp twists two head motifs of a dumbbell tile into parallel conformations, wheareas a stem at 16 bp twists two head motifs into antiparallel conformations. We successfully constructed four DNA dumbbell tiles and assembled them into two-dimensional (2D) arrays of planar nanoribbons with zebra-like patterns and fine nanotubes as well.

DNA nanotubes assembled from tensegrity triangle tiles with circular DNA scaffolds.

Using small circular DNA molecules of different lengths as scaffolds, we successfully synthesised DNA nanotubes consisting of Mao's DNA tensegrity triangle tiles with four-arm junctions (Holliday junctions) at all vertices. Due to the intrinsic curvature of the triangle tile and the consecutive tile alignment, the 2D arrays are organised in the form of nanotubes. Two sized triangle tiles with equilateral side lengths of 1.5 and 2.5 full helical turns are connected by the sticky ended cohesion of a duplex with a length of 2.5 helical turns respectively, and their parallel lozenge tiling lattices were demonstrated by high resolution AFM images, where the former lozenge unit cell has a lattice constant of 13.6 nm, and the latter has a larger lattice constant of 17.0 nm. Modification of the triangle tile with infinitesimal disturbance on side lengths and insertion of one thymine single stranded loop at every vertex resulted in comparably similar nanotubes.