No abstract

No abstract

No abstract

Advances in molecular biotechnology have introduced new generations of molecular markers for use in the genetic improvement of farm animals. Consequently, more accurate genetic information can be obtained to better understand existing animal genetic resources. This review gives a brief summary on the development of genetic markers including both the classical genetic markers and more advanced DNA-based molecular markers. This review will help us better understand the characteristics of different genetic markers and the genetic diversity of animal genetic resources.

Smart 3D printed structural components with self-monitoring ability show potential applications in some extreme environments, such as deep-water and space. Fused deposition modeling (FDM) provides a feasible solution; however, it is still a big challenge to print structural components with high bending and stretching mechanical properties because of the weak interlayer bonding and the pores. Here, a low-cost and facile fabrication strategy of smart components combining FDM with laser-scribing technology is reported. A thin laser-induced graphene (LIG) layer (∼50 μm) can serve as the active materials of sensors, which can be obtained on the printed polyetheretherketone (PEEK) components. Accordingly, the PEEK−LIG smart components (PEEK−LIG SCs) can self-monitor the working process and the deformations (bidirectional bending and stretching) in real time with high sensitivity. For instance, the gauge factors of PEEK−LIG SCs for bending outward and stretching are up to 155.36 and 212.35 (2−5% strain), respectively. Besides, the PEEK−LIG SCs possess good reliability (>1000 cycles), fast response time (60 ms), and recovery time (247 ms). We further show the excellent performance of the PEEK−LIG smart gear in monitoring the rotation and the abrasion, indicating the wide potential applications of this strategy.

No abstract

Fused deposition modeling possesses great advantages in fabricating high performance composites with controllable structural designs. As such, it has attracted attention from medical, automatic, and aerospace fields. In this paper, the influence of short carbon fibers (SCFs) and the orthogonal building orientation on the flexural properties of printed polyether ether ketone (PEEK) composites are systematically studied. The results show that the addition of SCFs raises the uniform nucleation process of PEEK during 3D printing, decreases the layer-to-layer bonding strength, and greatly changes the fracture mode. The flexural strength of vertically printed PEEK and its CF-reinforced composites show strengths that are as high as molded composites. X-ray micro-computed tomography reveals the microstructure of the printed composites and the transformation of pores during bending tests, which provides evidence for the good mechanical properties of the vertically printed composites. The effect of multi-scale factors on the mechanical properties of the composites, such as crystallization in different positions, layer-by-layer bonding, and porosity, provide a successful interpretation of their fracture modes. This work provides a promising and cost-effective method to fabricate 3D printed composites with tailored, orientation-dependent properties.

The Positive Transcription Elongation Factor b (P-TEFb) phosphorylates Ser2 residues of the C-terminal domain (CTD) of the largest subunit (RPB1) of RNA polymerase II and is essential for the transition from transcription initiation to elongation in vivo. Surprisingly, P-TEFb exhibits Ser5 phosphorylation activity in vitro. The mechanism garnering Ser2 specificity to P-TEFb remains elusive and hinders understanding of the transition from transcription initiation to elongation. Through in vitro reconstruction of CTD phosphorylation, mass spectrometry analysis, and chromatin immunoprecipitation sequencing (ChIP-seq) analysis, we uncover a mechanism by which Tyr1 phosphorylation directs the kinase activity of P-TEFb and alters its specificity from Ser5 to Ser2. The loss of Tyr1 phosphorylation causes an accumulation of RNA polymerase II in the promoter region as detected by ChIP-seq. We demonstrate the ability of Tyr1 phosphorylation to generate a heterogeneous CTD modification landscape that expands the CTD’s coding potential. These findings provide direct experimental evidence for a combinatorial CTD phosphorylation code wherein previously installed modifications direct the identity and abundance of subsequent coding events by influencing the behavior of downstream enzymes.