The wild progenitor species (Oryza rufipogon) of Asian cultivated rice (O. sativa L.) is located in Dongxiang county, China which is considered its the northernmost range worldwide. Nine ex situ and three in situ populations of the Dongxiang wild rice (DXWR) and four groups of modern cultivars were genotyped using 21 SSR markers for study of population structure, conservation efficiency and genetic relationship. We demonstrated that the ex situ conservation of the DXWR failed to maintain the genetic identity and reduced genetic diversity. Therefore, in situ conservation is absolutely necessary to maintain the genetic identity, diversity and heterozygosity. Also, in situ conservation is urgently needed because natural populations in DXWR have decreased from nine to three at present due to farming activity and urban expansion. In DXWR, the three surviving in situ populations had greater expected heterozygosity than any cultivated rice, and were genetically closer to japonica than either the male-sterile maintainer or restorer lines, or indica. Japonica has the lowest genetic diversity of cultivated rice. As a result, DXWR is a rich gene pool and is especially valuable for genetic improvement of japonica rice because these O. rufipogon accessions are most closely related to the japonica as compared to O. rufipogon collected anywhere else in the world.
Large-scale mitochondrial DNA (mtDNA) D-loop sequences data from previous studies were investigated to obtain genetic information which contributes to a better understanding of the genetic diversity and history of modern sheep. In this study, we analyzed mtDNA D-loop sequences of 963 individuals from 16 Chinese indigenous breeds that distributed seven geographic regions. Phylogenetic analysis showed that all three previously defined haplogroups A, B, and C were found in all breeds among different regions except in Southwest China mountainous region, which had only the A and B haplogroups. The weak phylogeographic structure was observed among Chinese indigenous sheep breeds distribution regions and this could be attributable to long-term strong gene flow among regions induced by the human migration, commercial trade, and extensive transport of sheep. The estimation of demographic parameters from mismatch analyses showed that haplogroups A and B had at least one demographic expansion of indigenous sheep in China.
Semen quality and fertility of Bama miniature pig and the effect of season on these parameters were determined in this study. Results were as follows: the overall mean ejaculate volume, 55.71 ± 15.21 ml; sperm concentration, 0.66 ± 0.22 × 108/ml; sperm motility, 65.39% ± 16.45%; abnormal sperm percentage, 12.16% ± 7.70%; farrowing rate, 76.44%; litter size, 7.74 ± 2.46. It showed that the semen quality and fertility of Bama miniature pigs were lower than the normal level of the larger commercial and local breeds. In terms of the effect of season, we noted that the semen quality and fertility of Bama miniature pigs were not worst in summer. This may indicate that Bama miniature pig is a relative heat-tolerant breed in comparison to larger commercial and local breeds. These findings in this study could provide reference material for improve management and husbandry in practice and for using Bama miniature pigs as animal model especially in male fertility studies.
Abstract:In this study, the cryopreservation methods for Bama miniature pig semen were investigated and optimized. First, using an orthogonal experimental design, the semen freezing-thawing procedure for Bama miniature boars was optimized based on analysis of the effects of concentrations of LDL (LC, parameter A), trehalose (TC, parameter B) and glycerol (GC, parameter C), the equilibration time at 15°C (ET, parameter D), and the thawing method (TM, parameter E) on sperm motility. The results showed that the effects of the parameters could be arranged as A>C>B>D>E. The LDL concentration and final glycerol concentration had exceedingly significant effects on the motility of thawed spermatozoa (P<0.01), and the effects of the trehalose concentration, equilibration time at 15°C, and the thawing method were not significant (P>0.05). Scheme 2 (A 3 B 4 C 2 D 3 E 1 ) gave a motility of 52.26% after thawing. Then, using sperm motility, acrosome integrity, plasma membrane integrity, and DNA injury rate as indicators, four combinations, on the basis of scheme 2, were designed to analyze the protective effects of different combinations of LDL, glycerol, and trehalose; the results showed that combination of 9% LDL, 200 mM trehalose, and 2% glycerol (i.e., combination 4) demonstrated significantly better protective effects than the other combinations (P<0.05), further verifying that scheme 2 was the best for cryopreservation of Bama miniature boar semen. In this way, a method with favorable performance was established for cryopreservation of semen of Bama miniature boars.
For better understanding the genetic diversity and phylogeny of the cultivated Salvia miltiorrhiza populations, four intergenic spacer sequences, ETS, psbA-trnH, trnL-trnF, and ycf1-rps15 of the 40 populations collected from China were Polymerase Chain Reaction (PCR) amplified, analyzed both individually and in combination. Haplotype diversity analysis showed that the cultivated S. miltiorrhiza populations had a very rich genetic diversity and an excellent capacity to resist environmental pressure. The best-fit nucleotide substitution models for ETS, psbA-trnH, trnL-trnF, ycf1-rps15, and their combined sequences were HKY+I, T92, T92, T92+G, and T92+G, respectively; the nucleotide conversion frequency in the combined sequences was lower than the transversion, and the relatively high nucleotide substitution frequencies suggests its high genetic variability. Neutral tests showed that the spacer sequences of the populations conform with the neutral evolution model, and there has been no current expansion events occurred. Phylogeny analyses based on both the individual and the combined sequences showed that the 40 populations were clustered in two clades with a very similar topological structure. The discrimination rate of the combined sequence marker is significantly increased to 52.5% (21 populations) over the highest 35% (13 populations) by the single marker of ETS, though still inadequate but a big step forward. Further exploration of more DNA markers is needed. This study for the first time revealed the rich genetic diversity and phylogeny of the currently cultivated S. miltiorrhiza populations in China and provides novel alternative molecular markers for the genetic identification and resources evaluation of the cultivated S. miltiorrhiza populations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.