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1. H-FABP (heart-type fatty acid-binding protein) is an important fatty acid-binding protein that participates in the metabolism and intracellular transportation of lipids. This study was designed ...

RFamide-related peptides (RFRP) are synthesized by the hypothalamus and have a regulatory role in gonad development. The goal of this study was to investigate the association between SNP of the RFRP gene and the reproductive traits and hormone levels of Zhenning yellow chickens. The mRNA expression levels were detected based on different tissues, ages, and genotypes. Eleven mutation sites were detected in the RFRP gene, 4 of which were significantly related to reproductive traits and hormone levels. Association analysis revealed that A276G was associated with egg production at 300 d of age (EP300) and amount of prehierarchical follicles (P

Design of the polymer networks with tunable mechanical properties and multishape memory effects (multi-SMEs) is highly desired in the engineering applications. Herein, we report on the stereocomplexed and homochiral polyurethane (PU) elastomers with tunable multi-SMEs by cross-linking the triblock prepolymers bearing the poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) enantiomeric segments. The homochiral PU is nearly amorphous, yet the stereocomplexed PU becomes highly crystalline due to the stereocomplexation of enantiomeric segments. Moreover, the two distinct thermal (glass, melting) transitions of PLLA (or PDLA) segments in PUs are integrated to realize the thermally induced triple- and quadruple-SMEs. Control over the enantiomeric segmental ratios allows the feasible manipulation of crystallizability, mechanical and thermal properties, and multi-SMEs of PUs.

Reproduction trait is one of the most important economic traits in poultry industry. This study was aimed to investigate the mRNA expression levels, single nucleotide polymorphisms (SNP) of POMC gene, and the association with reproduction traits in chickens. Five SNP (g.958 G > A, g.1374 G > C, g.1393 G > A, g.1817 C > T, and g.1918G > A) were detected in introns of POMC gene in 317 Zhenning yellow chickens. Association analysis revealed that g.958 G > A and g.1817 C > T showed significantly associations with fertilization rate, hatching rate of hatching eggs, and hatching rate of fertilized eggs in chickens. Simultaneously, g.1374 G > C and g.1918G > A were both associated with egg weight at 300 D of age (P < 0.05). The SNP of g.958 G > A, g.1393 G > A, and g.1817 C > T were all associated with E2 hormone levels (P < 0.05). The result of mRNA expression levels in different tissues showed that POMC mRNA expression level in the pituitary was higher than those in the other tissues and varied in different genotypes. In conclusion, the results in this study provided new evidences that polymorphisms of the POMC gene have potential effects on reproduction traits in chickens. The 5 SNP detected in this study could be potential markers for improving reproduction traits in chickens.

1. Fatty acid-binding proteins (FABP) are members of lipid-binding proteins, which participate in the metabolism and intracellular transportation of lipids. This study was designed to investigate t...

As an important indicator of sexual maturity of hens, age at first egg (AFE) is significantly associated with reproduction performance. In this study, 400 hens were divided into 6 groups based on AFE to analyze the difference of reproduction performance, reproduction hormone levels and the characterization of the hypothalamo–pituitary–gonadal axis in chickens. The results showed that the egg production of the hens in the late-maturing groups was significantly lower than that of the ones in other groups and the precocious hens had a lower egg production rate. The hens in late-maturing group had a lower fertility rate, LH levels and shorter duration of peak of egg production (PEP), the precocious hens had lower PRL levels. In addition, the characterization of the hypothalamo–pituitary–gonadal axis showed that the individuals with normal AFE had higher GNRH, GNRHR, ESR1, KITLG, and CYP11A1 expression levels than late-maturing and precocious individuals, which indicated that the chickens with normal AFE advantages on reproduction regulation system.

The widespread application of thermo-responsive hydrogels requires materials with robust mechanical properties and tunable responsiveness. Herein, we report robust thermo-responsive physical hydrogels with a tunable network structure and responsiveness by controlling the manner of crystallization of hydrophobic blocks. Biocompatible, stereocomplexable poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) were introduced into thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) to obtain the enantiomeric grafted copolymers PNIPAM-g-PLLA and PNIPAM-g-PDLA and their corresponding hydrogels. The hydrophobic PLLA/PDLA domains served as physical crosslinking junctions in the hydrogels. The crystalline structure of the hydrogels can be facilely tuned by varying the ratio of PLLA/PDLA enantiomeric blocks. Stereocomplex (SC) crystallization between PLLA and PDLA facilitates the formation of H-bonded hydrophobic domains with denser chain packing, which endows the racemic hydrogels with a stronger network structure, higher mechanical strength, and better solvent resistance compared to enantiopure examples. The hydrogels exhibit good thermo-sensitivity in water; the stronger racemic hydrogel network restricts volume shrinkage and water desorption at high temperatures, enabling the facile control of thermo-responsiveness. The crystallization-tuned thermo-responsiveness of racemic and enantiopure hydrogels also allows for the design of assembled bilayer hydrogels capable of thermally triggered reversible shape morphing.

Stereocomplexation of complementary chiral blocks has been a feasible way to prepare thermoresponsive physical gels (or thermogels). Understanding the thermoresponsive phase behavior of stereocomplexable amphiphilic copolymers in water is essential to prepare thermogels with tunable physical properties. Herein, we use an enantiomeric mixture of the poly(D-lactic acid) (PDLA)/poly(ethylene glycol) (PEG) diblock copolymer and the poly(L-lactic acid) (PLLA)/PEG triblock copolymer as a stereocomplexable system and report a novel thermogel that exhibits unique gel–sol–gel multiple transitions upon heating. The thermally-induced phase transition of the PEG–PDLA/PLLA–PEG–PLLA thermogel was governed by the copolymer composition and the stereocomplexation of PLLA/PDLA segments. The molecular motion of PEG segments enhances during the gel–sol transition but slows down in the subsequent sol–gel transition. The gel–sol and sol–gel transitions that occurred at low and high temperatures are driven by the increased mobility of PEG segments and micelles and the promoted PLLA/PDLA stereocomplexation, respectively. PEG–PDLA/PLLA–PEG–PLLA gels can be used to capsulate and release a hydrophobic drug; the drug release rate increases as the content of hydrophilic blocks increases.

Physical hydrogels crosslinked by non-covalent interactions have attained increasing attention due to their good mechanical properties and processability. However, the use of feasible and controllable non-covalent interactions is highly essential for preparing such hydrogels. In this article, we report on stereocomplexed physical hydrogels prepared by simple casting and swelling of amphiphilic graft copolymers bearing a poly(acrylic acid) (PAA) backbone and poly(l-lactic acid) (PLLA) or poly(d-lactic acid) (PDLA) stereocomplexable side chains. The microstructure, swelling behavior, and mechanical and shape memory properties of the obtained hydrogels can be tuned by varying the copolymer composition and stereocomplex (SC) crystallization of PLLA/PDLA enantiomeric chains. The long PLLA or PDLA chains segregate to form hydrophobic, crystallized domains in water, serving as physical crosslinking junctions for hydrogels. SC crystallization between PLLA and PDLA further enhances the number density of physical crosslinkers of enantiomerically mixed hydrogels. The SC content increases as the PLLA/PDLA ratio approaches 1/1 in enantiomerically mixed hydrogels. The average distance between crosslinking junctions declines for the hydrogels with a high PLLA (or PDLA) mass fraction (MPLA) and SC content, due to the increased number density of physical crosslinkers. Accordingly, the tensile strength and the Young's modulus increase but the swelling ratio and the elongation-at-break of the hydrogels decrease with an increase in MPLA and SC content. The hydrogels exhibit shape memory behavior; the shape fixing ability is enhanced by the SC crystallization of PLLA/PDLA side chains in the hydrogels.

Myostatin (MSTN) is a negative regulator of skeletal muscle growth and plays an important role in muscle development. In this research, we constructed a tissue expression profile of the pigeon MSTN gene in eight tissues and a spatio-temporal expression profile in the pectoral muscle using qRT-PCR method. And the pectoralis muscle fiber traits during pigeon post-hatching stages at 1, 7, 14, 21, and 28 D were analyzed through the paraffin sections. Then the correlations between the muscle fiber diameter, cross-sectional area, density, and the expression of MSTN in the pectoral muscle were analyzed. Results showed that MSTN mRNA was mainly expressed in breast muscle, heart, spleen, and kidney and it was almost unexpressed in the liver and lungs. Moreover, the MSTN mRNA expression level in breast muscle was significantly higher than that in other tissues (P < 0.05), and showed an interesting trend that it decreased in the first week and then increased with age. Meanwhile, decrease of myostatin transcripts was accompanied by the down-regulation of Myf5 and the up-regulation of MyoG during the first week post-hatching. In addition, the paraffin sections analysis results revealed that the diameter and cross-sectional area of pectoralis muscle fiber significantly increased with age (P < 0.05), and a significant positive correlation was shown between the MSTN gene expression level and muscle fiber diameter (P < 0.05). These fundamental researches might contribute to further understanding of the roles MSTN played in the post-hatching muscle fiber development in pigeon.

Stimuli-responsive shape-transforming hydrogels have shown great potential toward various engineering applications including soft robotics and microfluidics. Despite significant progress in designing hydrogels with ever more sophisticated shape-morphing behaviors, an ultimate goal yet to be fulfilled is programmable reversible shape transformation. It is reported here that transient structural anisotropy can be programmed into copolymer hydrogels of N-isopropylacrylamide and stearyl acrylate. Structural anisotropy arises from the deformed hydrophobic domains of the stearyl groups after thermomechanical programming, which serves as a template for the reversible globule-to-coil transition of the poly(N-isopropylacrylamide) chains. The structural anisotropy is transient and can be erased upon cooling. This allows repeated programming for reversible shape transformation, an unknown feature for the current hydrogels. The programmable reversible transformation is expected to greatly extend the technical scope for hydrogel-based devices.

Constructing dual or multiple noncovalent crosslinks is highly effective to improve the mechanical and stimuli-responsive properties of supramolecular physical hydrogels, due to the synergistic effects of different noncovalent bonds. Herein, a series of tough physical hydrogels are prepared by solution casting and subsequently swelling the films of poly(ureidopyrimidone methacrylate-co-stearyl acrylate-co-acrylic acid). The hydrophobic interactions between crystallizable alkyl chains and the quadruple hydrogen bonds between ureidopyrimidone (UPy) motifs serve as the dual crosslinks of hydrogels. Synergistic effects between the hydrophobic interactions and hydrogen bonds render the hydrogels excellent mechanical properties, with tensile breaking stress up to 4.6 MPa and breaking strain up to 680%. The UPy motifs promote the crystallization of alkyl chains and the hydrophobic alkyl chains also stabilize UPy-UPy hydrogen bonding. The resultant hydrogels are responsive to multiple external stimuli, such as temperature, pH, and ion; therefore, they show the thermal-induced dual and metal ion-induced triple shape memory behaviors.