Nanoemulsion formulation of florfenicol improves bioavailability in pigs

Nanotechnology applications in medicine have seen a tremendous growth in the past decade and are being employed to enhance the stability and bioavailability of lipophilic substances, such as florfenicol. This study aimed to examine the pharmacokinetic properties of the formulated oil‐in‐water florfenicol‐loaded nanoemulsion (FF‐NE). FF‐NE and florfenicol control (Nuflor^®) were administered to the pigs at a dose of 20 mg/kg. Nanoemulsion formulation of florfenicol was highly influenced in vivo plasma profile. The in vivo absorption study in pigs indicated that C_max (14.54 μg/mL) was significantly higher in FF‐NE, 3.42 times higher than the marketed formulation. In comparison with the control group, the relative bioavailability of formulated nanoemulsion was up to 134.5%. Assessment of bioequivalence using log‐transformed data showed that the 90% confidence intervals (90% CI) of C_max and AUC_0–∞ were 2.48–4.60 and 1.21–1.72, respectively.     

Two single nucleotide polymorphisms in the promoter of the ovine myostatin gene (MSTN) and their effect on growth and carcass muscle traits in New Zealand Romney sheep

Myostatin is a negative regulator of muscle growth and development in mammals, and variation in ovine myostatin gene (MSTN) has been demonstrated to be associated with variation in the muscularity of sheep. Polymerase chain reaction–single‐stranded conformational polymorphism (PCR–SSCP) was used to look for single nucleotide polymorphisms (SNPs) in a 304‐bp amplicon from the promoter region of ovine MSTN. Sequence analyses revealed two previously identified SNPs (c.?2449G/C and c. ?2379T/C) that resulted in three haplotypes (H₁ (c.[?2449G; ?2379C]), H₂ (c.[?2449C; ?2379C]) and H₃ (c.[?2449G; ?2379T]). The effect of these SNPs on growth and carcass traits was investigated in 357 NZ Romney lambs. General linear mixed‐effect models revealed that sheep with the genotype c.?2449GC had a higher loin meat yield (p = 0.032) and proportion loin yield (p = 0.028), than those with the genotype c.?2449GG. The genotype c.?2379CC was associated with an increase in three weight traits: birthweight (p = 0.003), tailing weight (p = 0.009) and weaning weight (p = 0.028), when compared with the genotype c.?2379TC, but it was not found to have an association with growth rate. This suggests that c.?2379T/C has an effect that originates at, or before birth. Haplotype H₃ was associated with a decrease in birthweight (p = 0.002), tailing weight (p = 0.003) and weaning weight (p = 0.011). Haplotype H₂ was associated with increased loin yield (p = 0.012) and proportion loin yield (p = 0.002). The SNPs may have value as genetic markers for improved Romney breeding.     

路灯照射对大豆生长发育和产量的影响

通过对淮北市五马路沿线2块夏大豆的田间调查分析表明:受路灯照射的影响,夏大豆株高增加,开花期、成熟期推迟,底荚部位上升,单株生产力下降.且距离越近,植株越高,开花、成熟越晚,底荚部位越高,单株生产力越低.     

Inhibition of porcine circovirus type 1 and type 2 production in PK-15 cells by small interfering RNAs targeting the Rep gene

Porcine circovirus type 1 (PCV1) and type 2 (PCV2) are two genotypes of porcine circovirus. Both of them are presumed to be widespread in the swine population. Currently, there is no specific treatment for their infections. RNA interference (RNAi) is a sequence-specific RNA degradation mechanism mediated by small interfering RNA (siRNA), which represents a possible therapeutic application for the treatment of viral infections. In this study, three siRNA expression plasmids (pS-RepA, pS-RepB and pS-RepC) were generated to target three different coding regions of the Rep protein (Rep) of PCV. These siRNAs were used to inhibit PCV production in a porcine kidney cell line, PK-15 cells. Our results revealed that Rep gene expression was inhibited by pS-RepA, pS-RepB and pS-RepC to different degrees. Moreover, our study also showed that the production of PCV1 and PCV2 was reduced by these siRNAs. pS-RepC, which targets the middle region of Rep gene, proved to be the most efficient siRNA for inhibition of Rep expression and viral production. Taken together, our data suggest that RNAi could be investigated as a potential treatment for PCV infection.     

Evaluation of immunogenicity and protective efficacy of Actinobacillus pleuropneumoniae HB04C(-) mutant lacking a drug resistance marker in the pigs

Previously, we reported the construction and characterization of a genetically defined Actinobacillus pleuropneumoniae (A. pleuropneumoniae) apxIIC gene mutant, HB04C(-), which conferred protection to mice against infection with A. pleuropneumoniae. In this study, we further evaluated HB04C(-) for safety and its ability to elicit protective immunity in pigs. It was demonstrated that a dose of 2 x 10(8) CFU HB04C(-) was safe to the pigs via intranasal or intramuscular injection. Immunization with a dose of 2 x 10(8) HB04C(-) by both intranasal and intramuscular routine could yield equal protective efficacy and elicited significant protection against experiment challenge with homologous or heterologous serotypes of a virulent A. pleuropneumonia. Taken together, HB04C(-) might serve as a promising vaccine candidate against infection with A. pleuropneumoniae.     

Stepwise in-straw dilution and direct transfer using open pulled straws (OPS) in the mouse: a potential model for field manipulation of vitrified embryos

In the present study, mouse blastocysts were employed to investigate the feasibility and efficiency of stepwise in-straw dilution and direct transfer using the open pulled straw (OPS) method. In experiment I, the effects of various vitrification solutions (VS) on embryo survival were examined. After thawing, the expanded blastocyst rates (97.59 and 95.05%) and hatching rates (80.48 and 78.95%) achieved in the EDFS30 [15% ethylene glycol (EG), 15% dimethyl sulfoxide (DMSO), Ficoll, and sucrose] and EFS40 [40% EG, Ficoll, and sucrose] groups were no different from those (96.15% and 83.33%) of the control group. However, the rates in the EFS30 [30% EG, Ficoll, and sucrose] (87.80 and 55.43%) and EDFS40 [20% EG, 20% DMSO, Ficoll, and sucrose] (95.69 and 70.97%) groups were significantly lower than those (96.15 and 83.33%) of the control group (P<0.05). In the experiment II, the effects of the volume of VS in the OPS on the survival of embryos after in-straw thawing were investigated. When the length of the VS in the column was less than 1 cm, the in vitro viability of embryos thawed by stepwise in-straw dilution was no different among the experimental and control groups. The embryos could be successfully thawed by immersing the OPS in 0.5 M sucrose for 3 min and then 0.25 M sucrose for 2 min. In experiment III, the effect of immersion time of the OPS in diluent (PBS) on the viability of vitrified embryos was investigated. After in-straw thawing, OPSs were immersed immediately in 1 ml PBS for 0 to 30 min. When the immersion time of the OPSs in PBS was less than 12 min, in vitro development of the in-straw thawed embryos was no different from that of the controls. In experiment IV, in-straw thawed blastocysts were directly transferred to pseudopregnant mice to examine their in vivo developmental viability. The pregnancy (91.67%) and birth rates (42.42%) of embryos in-straw thawed and directly transferred were no different from those of the unvitrified controls (90.90 and 40%) and embryos thawed by the conventional method (84.61 and 46.94%). These results demonstrate that mouse embryos vitrified with OPS could be successfully thawed by stepwise in-straw dilution and transferred directly to a recipient and that this method might be a model for field manipulation of vitrified embryos in farm animals.     

Identification and distribution of fungal pathogens associated with seedling blight of rice in the southern United States

Surveys were conducted in the five southern rice-producing states of Arkansas, Louisiana, Mississippi, Missouri and Texas in the United States during the 2018 and 2019 cropping seasons to determine the distribution and pathogenicity of fungal pathogens associated with seedling blight in rice. A total of 349 pathogenic fungal isolates were collected and identified as belonging to four genera: Rhizoctonia solani, Fusarium spp., Sclerotium rolfsii and Marasmius graminum based on morphological characteristics, molecular analysis and Koch's postulates. R. solani (252 out of 349 pathogenic isolates) was the most prevalent fungus isolated from diseased samples. Of the 252 pathogenic R. solani isolates, 245 were further classified as anastomosis group 11 (AG-11) and 7 as AG-4. Isolates of R. solani AG-4 and M. graminum were the most aggressive, with the highest stand loss (63% to 100%) and median disease rating (DR; 5.0), followed by isolates of R. solani AG-11 (stand loss = 4% to 100% and DR = 0.6 to 5.0), Fusarium spp. (stand loss = 26% to 48% and DR = 2.0 to 5.0) and S. rolfsii (stand loss = 33% to 48% and DR = 2.0 to 3.0) in causing seedling blight in rice. R. solani (62% to 83% of total pathogenic isolates) and Fusarium spp. (10% to 24% of total pathogenic isolates) were predominant in all the five states surveyed. S. rolfsii and M. graminum were present only in Louisiana and Texas. The results of this first systematic survey of rice seedling diseases in the southern United States will help develop effective fungicide seed treatment strategies for control of stand loss caused by seedling blight, one of the major factors limiting rice production.     

Application and mechanisms of metal-based nanoparticles in the control of bacterial and fungal crop diseases

Nanotechnology is a young branch of the discipline generated by nanomaterials. Its development has greatly contributed to technological progress and product innovation in the field of agriculture. The antimicrobial properties of nanoparticles (NPs) can be used to develop nanopesticides for plant protection. Plant diseases caused by bacterial and fungal infestations are the main types of crop diseases. Once infected, they will seriously threaten crop growth, reduce yield and quality, and affect food safety, posing a health risk to humans. We reviewed the application of metal-based nanoparticles in inhibiting plant pathogenic bacteria and fungi, and discuss the antibacterial mechanisms of metal-based nanoparticles from two aspects: the direct interaction between nanoparticles and pathogens, and the indirect effects of inducing plant resilience to disease. © 2022 Society of Chemical Industry.     

动物防疫领域政府购买公共服务相关术语混合使用情况辨析

自1994年深圳市罗湖区在环境卫生领域率先引入政府购买公共服务以来,我国政府购买公共服务经历局部性试点与探索、试点推进、制度化推广、全面推开与创新等4个阶段。2005年以来,我国对动物防疫领域政府购买公共服务进行了探索,但有关术语及其涵义一直未界定,更未形成共识,导致术语混用较为严重。术语混用体现了人们认知不同,看法不一,给动物防疫领域政府购买公共服务理论研究和实践探索造成了混乱。鉴于此,本文尝试梳理术语混用的背景、混用情况并予以辨析,以探讨动物防疫领域政府购买公共服务相关术语的正确使用。     

胺鲜酯(DA-6)浸种对盐胁迫下白三叶种子萌发及抗盐性的影响

以白三叶(Trifolium repens L.‘Haifa’)为研究对象,研究了0.8 mmol·L^-1胺鲜酯(DA-6)浸种处理对白三叶种子在盐胁迫条件下萌发的影响,并对DA-6诱导的耐盐机理进行初步研究,为白三叶的栽培管理提供参考。结果表明,DA-6浸种显著提高了盐胁迫下种子的发芽势、发芽率、活力指数、发芽指数、茎长和鲜干重(P<0.05)。盐胁迫显著诱导了游离脯氨酸和可溶性糖的积累,降低了细胞渗透势(P<0.05)。此外,盐胁迫导致了萌发种子中活性氧(超氧阴离子和过氧化氢)和膜脂过氧化产物丙二醛含量显著增加,电导率显著升高(P<0.05)。DA-6浸种前处理显著提高了胁迫下抗氧化酶(SOD、POD和APX)的活性,增幅分别为33.0%、31.9%和49.1%,这有效地缓解了由盐胁迫引起的氧化损伤,有利于幼苗稳定细胞膜(P<0.05)。本研究表明DA-6浸种处理通过增强抗氧化防御并降低细胞氧化伤害,从而提高盐胁迫下白三叶种子的萌发特性和胁迫耐受性。