Search

Chest circumference (CC), abdominal circumference (AC), and waist circumference (WC) are regarded as important indicators for improving economic traits because they can reflect the growth and physiological status in pigs. However, the genetic architecture of CC, AC, and WC is still elusive. Here, we performed single-trait and multi-trait genome-wide association studies (GWASs) for CC, AC, and WC in 2,206 American origin Duroc (AOD) and 2,082 Canadian origin Duroc (COD) pigs. As a result, one novel quantitative trait locus (QTL) on Sus scrofa chromosome (SSC) one was associated with CC and AC in COD pigs, which spans 6.92 Mb (from 170.06 to 176.98 Mb). Moreover, multi-trait GWAS identified 21 significant SNPs associated with the three conformation traits, indicating the multi-trait GWAS is a powerful statistical approach that uncovers pleiotropic locus. Finally, the three candidate genes (ITGA11, TLE3, and GALC) were selected that may play a role in the conformation traits. Further bioinformatics analysis indicated that the candidate genes for the three conformation traits mainly participated in sphingolipid metabolism and lysosome pathways. For all we know, this study was the first GWAS for WC in pigs. In general, our findings further reveal the genetic architecture of CC, AC, and WC, which may offer a useful reference for improving the conformation traits in pigs.

In ultra-wideband (UWB) positioning systems, positioning accuracy can be improved by determining the conditions of line-of-sight (LOS) and non-line-of-sight (NLOS) propagation and taking appropriate measures. The machine learning-based LOS/NLOS identification methods have been widely used due to its advantages of eliminating the need for prior knowledge. Unfortunately, traditional identification methods, such as LS-SVM, DT, and KTT, decrease significantly in other scenarios. Fortunately, Capsule Networks (CapsNet) showed its advantages of high accuracy and robustness in image classification as one of the latest machine learning achievements. Recently, some researchers noticed CapsNet and extended its application to LOS/NLOS identification. However, the generation ability and robustness of the capsule network needs to be further studied. In this paper, we verify the generalization ability and robustness of CapsNet based on the IEEE 802.15.4a channel model and experimental data. Experimental results show that the generation ability and robustness of the CapsNet-based method is better than the benchmark methods.

Non-line-of-sight (NLOS) propagation is one of the key challenges in radio positioning. Significant attentions have been drawn to the identification and mitigation of the NLOS in recent years. This paper focuses on the identification of NLOS signals based on the feature attached to the signals themselves. We propose a novel NLOS identification technique employing K-Means Clustering (KMC) and kernel KMC methods, which are two of the most popular techniques in the field of data mining. Our work is based on the fact that the features used, i.e., the kurtosis, the mean excess delay spread, and the root-mean-square delay spread are well modeled by log-normal random variables. Numerical simulations are performed to demonstrate the validity of the methodology.

For a wireless location network using ultra-wideband signals, the positioning accuracy of the network is affected by the transmission power of the anchors when the power resources are limited. The square position error bound is introduced as the standard of the positioning accuracy of the network, and a functional model of the square position error bound of the network and the transmission power of the anchors is established. Based on this model, a power optimization allocation algorithm based on cooperative game was proposed to achieve the goal of improving positioning accuracy. Simulation results show that the algorithm reduces the square position error bound of the network, which effectively improves the positioning accuracy.

The somatic cell nuclear transfer (SCNT) technique could be used to produce genetically superior or genetically engineered cloned pigs that have wide application in agriculture and bioscience research. However, the efficiency of porcine SCNT currently is very low. Embryo transfer (ET) is a key step for the success of SCNT. In this study, the effects of several ET-related factors, including cloned embryo culture time, recipient's ovulation status, co-transferred helper embryos and ET position, on the success rate of pig cloning were investigated. The results indicated that transfer of cloned embryos cultured for a longer time (22–24h vs. 4–6h) into pre-ovulatory sows decreased recipient's pregnancy rate and farrowing rate, and use of pre-ovulatory and post-ovulatory sows as recipients for SCNT embryos cultured for 22–24h resulted in a similar porcine SCNT efficiency. Use of insemination-produced in vivo fertilized, parthenogenetically activated and in vitro fertilized embryos as helper embryos to establish and/or maintain pregnancy of SCNT embryos recipients could not improve the success rate of porcine SCNT. Transfer of cloned embryos into double oviducts of surrogates significantly increased pregnancy rate as well as farrowing rate of recipients, and the developmental rate of transferred cloned embryos, as compared to unilateral oviduct transfer. This study provided useful information for optimization of the embryo handling and transfer protocol, which will help to improve the ability to generate cloned pigs.

Currently, cloning efficiency in pigs is very low. Donor cell type and number of cloned embryos transferred to an individual surrogate are two major factors that affect the successful rate of somatic cell nuclear transfer (SCNT) in pigs. This study aimed to compare the influence of different donor fibroblast cell types and different transferred embryo numbers on recipients' pregnancy rate and delivery rate, the average number of total clones born, clones born alive and clones born healthy per litter, and the birth rate of healthy clones (=total number of healthy cloned piglets born /total number of transferred cloned embryos). Three types of donor fibroblasts were tested in large-scale production of cloned pigs, including fetal fibroblasts (FFBs) from four genetically similar Western swine breeds of Pietrain (P), Duroc (D), Landrace (L), and Yorkshire (Y), which are referred to as P,D,LY-FFBs, adult fibroblasts (AFBs) from the same four breeds, which are designated P,D,L,Y-AFBs, and AFBs from a Chinese pig breed of Laiwu (LW), which is referred to as LW-AFBs. Within each donor fibroblast cell type group, five transferred cloned embryo number groups were tested. In each embryo number group, 150-199, 200-249, 250-299, 300-349, or 350-450 cloned embryos were transferred to each individual recipient sow. For the entire experiment, 92,005 cloned embryos were generated from nearly 115,000 matured oocytes and transferred to 328 recipients; in total, 488 cloned piglets were produced. The results showed that the mean clones born healthy per litter resulted from transfer of embryos cloned from LW-AFBs (2.53 ± 0.34) was similar with that associated with P,D,L,Y-FFBs (2.72 ± 0.29), but was significantly higher than that resulted from P,D,L,Y-AFBs (1.47 ± 0.18). Use of LW-AFBs as donor cells for SCNT resulted in a significantly higher pregnancy rate (72.00% vs. 59.30% and 48.11%) and delivery rate (60.00% vs. 45.93% and 35.85%) for cloned embryo recipients, and a significantly higher birth rate of healthy clones (0.5009% vs. 0.3362% and 0.2433%) than that resulting from P,D,L,Y-AFBs and P,D,L,Y-FFBs. This suggests that using LW-AFBs as donor cells results in a higher cloning efficiency in pigs, compared with the other two donor fibroblast cell types. The birth rate of healthy clones was significantly improved when the number of transferred cloned embryos was increased from 150-199 to 200-450 per recipient. However, increase of the number of transferred embryos from 200-249 to 250-450 per surrogate did not change the birth rate of healthy clones. This suggests that transfer of excessive (250-450) cloned embryos to an individual surrogate is not necessary for increasing the cloning efficiency in pigs, and the relatively optimal number of reconstructed embryos transferred to individual recipient is 200-249. Furthermore, our results indicated that the numbers of total born clones, clones born alive, and clones born healthy per litter have a significantly high positive correlation with each other. The present study provides useful information for improving SCNT efficiency in pigs.