甜瓜果肉硬度（Flesh firmness, FF）是农业生产者和消费者关注的一个复杂且重要的性状，但目前针对甜瓜果肉硬度性状的遗传机制尚不清楚。本研究以软果肉甜瓜“P5”和硬果肉甜瓜“P10”配置杂交组合，构建F₂分离群体，通过QTL-SLAF测序和分子标记连锁分析，共鉴定112,844个SLAF位点，使用5,919个SNP标记构建了总遗传距离为1356.49 cM的连锁图谱。结合两年田间表型分析显示，控制果实长度（Fruit Length, FL）和宽度（Fruit Diameter, FD）的QTLs位点位于同一区间，控制单果重（Single-Fruit Weight, SFW）性状的QTL位于两条不同的染色体上。对于果肉硬度检测到一个主要QTL位点ff2.1，位于甜瓜2号染色体0.17 Mb的候选区域。利用429个F₂单株，将ff2.1候选区间缩小到28.3 kb区域，包含3个候选基因。本研究不仅鉴定了一个控制甜瓜果肉硬度的QTLs位点，同时也为甜瓜基因功能基因的研究提供了理论基础。

杂交水稻为世界粮食的供应做出了重大贡献，而骨干亲本在杂交水稻品种选育中发挥着重要作用。为明确水稻骨干亲本蜀恢527（SH527，Oryza sativa）在育种过程中所利用的关键基因组区域，本研究对其进行了基于系谱的全基因组分析。利用高密度单核苷酸多态性（SNP）阵列对包括SH527、6个亲本品种及17个衍生恢复系在内的24个品种进行了扫描，分析了上游亲本对SH527基因组的独特贡献，确定了SH527及其衍生品种中保守的关键基因组区域。同时，利用多年的产量性状数据和SNP 芯片结果进行全基因组关联分析，发现了一些可能的已知或新的产量性状的关联位点。这项研究初步揭示了SH527育种的关键区域，将为后续育种提供参考。杂交水稻为世界粮食的供应做出了重大贡献，而骨干亲本在杂交水稻品种选育中发挥着重要作用。为明确水稻骨干亲本蜀恢527（SH527，Oryza sativa）在育种过程中所利用的关键基因组区域，本研究对其进行了基于系谱的全基因组分析。利用高密度单核苷酸多态性（SNP）阵列对包括SH527、6个亲本品种及17个衍生恢复系在内的24个品种进行了扫描，分析了上游亲本对SH527基因组的独特贡献，确定了SH527及其衍生品种中保守的关键基因组区域。同时，利用多年的产量性状数据和SNP 芯片结果进行全基因组关联分析，发现了一些可能的已知或新的产量性状的关联位点。这项研究初步揭示了SH527育种的关键区域，将为后续育种提供参考。

Received  12 December, 2017    Accepted  26 February, 2018

    Bovine mastitis caused by Staphylococcus aureus is difficult to treat because of increasing resistance against antibiotics, especially penicillin. β-Lactamase and biofilm are responsible for penicillin resistance of S. aureus. The aim of this study was to investigate the β-lactamase activity and biofilm formation capacity of 37 penicillin-resistant S. aureus strains (35 were blaZ positive and 2 were blaZ negative) from bovine mastitis in Gansu Province, China, as well as to measure the intercellular adhesion genes icaA and icaD of these strains. β-Lactamase Test Kit was used to determine the β-lactamase activity, biofilm formation was tested by semi-quantitative adherence assay method. Moreover, the presence of icaA and icaD were measured by PCR. A total of 32 penicillin-resistant S. aureus strains, including the two blaZ-negative strains, were identified as β-lactamase producers. All tested S. aureus isolates produced biofilm in the microtiter plate assay. Meanwhile, all these strains were PCR-positive for the ica locus, icaA and icaD. The study indicated high prevalence of β-lactamase activity, biofilm-forming capacity, and the ica genes among the penicillin-resistant S. aureus isolates, and implied that S. aureus resistant to penicillin was attributed to multiple mechanisms.

DNA methyltransferases (Dnmts) comprise a family of proteins which involved in the establishment and maintenance of DNA methylation patterns.  In pig, the molecular characterization and tissue expression profile of Dnmt gene family are not clear.  To solve this problem, reverse transcriptase PCR and rapid amplification of cDNA ends were used to clone the sequences of the porcine Dnmt2 and Dnmt3b genes.  Furthermore, the mRNA expression profiles of Dnmt1, Dnmt2, Dnmt3a and Dnmt3b genes from 54 adult tissues and 2 entire fetuses of Rongchang pig were analyzed by quantitative real-time PCR (qRT-PCR).  As a result, the lengths of porcine Dnmt2 and Dnmt3b gene cDNAs were 1 227 and 2 559 bp with cytosine-C5 specific DNA methylase domain, respectively.  The four Dnmt genes were highly expressed in longissimus dorsi muscle (P<0.01).  Dnmt1 is highly expressed in heart (P<0.01) and Dnmt 2 shows its preference in liver and seminal vesicle tissue (P<0.01).  Dnmt3a and Dnmt3b are highly expressed in the two fetus stages (P<0.01).  All these results suggested that each gene has its specific expression profile, and deeper study is required to dig more details between the methylation level and Dnmt family mRNA expressions in different tissues.

    Programmed cell death (PCD) plays a critical role in the development of plant pigment glands, while H₂O₂, which is a kind of reactive oxygen species (ROS) produced by the aerobic metabolism of cells, acts as an important signal in this process. Here, we investigated the temporal and spatial dynamics of accumulated H₂O₂ in pigment glands of Gossypium hirsutum L. with 3,3-diaminobenzidine (DAB) staining, 2’,7’-dichlorodihydrofluorescein diacetate (DCFH₂)-DA fluorescent labeling and CeCl₃ cytochemical localization techniques. The results showed that the pigment glands of G. hirsutum could generate H₂O₂, and the amount and localization of H₂O₂ varied at different developmental stages. At the early developmental stage, a small amount of HH₂O₂ accumulated in the vacuole membrane of pigment gland cells. At the intermediate stage, a large number of H₂O₂ appeared in the vacuole membrane, while cell walls started to accumulate a small amount of H₂O₂. When pigment gland cell degraded, H₂O₂ mainly accumulated on the chloroplast envelope membrane of inner sheath cells. With the degradation of the sheath cells, H₂O₂ was detected in cell wall and the membrane of secretory vesicles which contains the preliminary contents of pigment gland. With the pigment glands completely maturation, H₂O₂ would disappeared. The accumulation sites of H₂O₂ are consistent with the process of PCD of individual gland cells, which started from the degradation of intracellular membrane and ended with the degradation of cell walls. Thus H₂O₂ probably plays an important role in the development of pigment glands. In addition, the development of pigment glands and the generation of H₂O₂ are not associated with the light, and no H₂O₂ was detected in the secretions of pigment glands.

    Staphylococcus aureus is the most common etiological pathogen of bovine mastitis. The resistant strains make the disease difficult to cure. The aim of this study was to characterize the genetic nature of the antimicrobial resistance in S. aureus cultured from bovine mastitis in Northwest China in 2014. A total of 44 S. aureus were isolated for antimicrobial resistance and resistance-related genes. Antimicrobial resistance was determined by disc diffusion and the corresponding resistance genes were detected by PCR. Phenotype indicated that S. aureus isolates were resistant to penicillin (84.09%), erythromycin (20.45%), tetracycline (15.91%), gentamicin (9.09%), tobramycin (6.82%), kanamycin (6.82%) and methicillin (2.27%). 9.09% of the S. aureus isolates were classified as multidrug resistant. In addition, genotypes showed that the isolates were resistant to rifampicin (100%, rpoB), penicillin (95.45%, blaZ), tetracycline (22.73%, tetK, tetM, alone or in combination), erythromycin (22.73%, ermB or ermC), gentamicin/tobramycin/kanamycin (2.27%, aacA-aphD), methicillin (2.27%, mecA) and vancomycin (2.27%, vanA). Resistance to tetracycline was attributed to the genes tetK and tetM (r=0.558, P<0.001). This study noted high-level geno- and phenotypic antimicrobial resistance in S. aureus isolates from bovine mastitis cases in Northwest China.

    The nuclear-encoded light-harvesting chlorophyll a/b-binding proteins (LHCPs) are specifically translocated from the stroma into the thylakoid membrane through the chloroplast signal recognition particle (cpSRP) pathway. The cpSRP is composed of a cpSRP43 protein and a cpSRP54 protein, and it forms a soluble transit complex with LHCP in the chloroplast stroma. Here, we identified the YGL9 gene that is predicted to encode the probable rice cpSRP43 protein from a rice yellow-green leaf mutant. A phylogenetic tree showed that an important conserved protein family, cpSRP43, is present in almost all green photosynthetic organisms such as higher plants and green algae. Sequence analysis showed that YGL9 comprises a chloroplast transit peptide, three chromodomains and four ankyrin repeats, and the chromodomains and ankyrin repeats are probably involved in protein-protein interactions. Subcellular localization showed that YGL9 is localized in the chloroplast. Expression pattern analysis indicated that YGL9 is mainly expressed in green leaf sheaths and leaves. Quantitative real-time PCR analysis showed that the expression levels of genes associated with pigment metabolism, chloroplast development and photosynthesis were distinctly affected in the ygl9 mutant. These results indicated that YGL9 is possibly involved in pigment metabolism, chloroplast development and photosynthesis in rice.

A synthetic cry2A* gene encoding Bacillus thuringiensis (Bt) δ-endotoxin that resistance to lepidopteran pest was transformed into japonica rice variety Jijing 88, which is the most widely cultivated variety in Jilin Province, Northeast China, by Agrobacterium-mediated transformation. A total of 106 independent transformants overexpressing cry2A* gene driven by ubiquitin (Ubi) promoter was produced. Three single-copy homozygous transgenic lines were finally selected based on the results of PCR analysis, segregation ratio of Basta resistance, and Southern hybridization analyses. RT-PCR and enzyme linked immune sorbent assay (ELISA) revealed that cry2A* transcripts and protein were highly expressed in these lines. The high level of Cry2A* protein expression resulted in high resistance to rice striped stem borer as evidenced by insect feeding bioassays. Our results demonstrate that cry2A* transgenic japonica rice confers resistance to the rice striped stem borer in the laboratory conditions.

In this study, nano-capsules of lansiumamide B (NCLB) was prepared by the microemulsion polymerization method to improve the nematicidal efficacy of lansiumamide B (LB). An optimal formulation was gained by orthogonal experiment design based on the encapsulation efficiency (En, %) value. The optimized NCLB were spherical and uniform under transmission electron microscopy (TEM). The mean particle size, zeta potential and En were (38.50±0.64) nm, (-70.5±0.76) mV and (95.13±1.16)%, respectively. The release profile indicated that the accumulated release of LB in NCLB reached up to 82% within 96 h. Effects of NCLB against Bursaphelenehus xylophilus and J2 of Meloidogyne incognita were reported in this paper. The nematicidal activity of NCLB has been remarkably increased, with LC50 values of 2.1407 mg L-1 and 19.3608 mg L-1, respectively, at 24 h after treatment. The disease progression and the average number of root knots of Ipomoea aquatica were 1.50 and 7.25, respectively, in the treatment of NCLB, at concentration of 200 mg L-1, significantly lower than the treatment of LB and ethoprophos. Compared to control, the treatments of NCLB, LB and ethoprophos leaded the disease progression to drop 68.42, 36.84 and 26.32%, respectively, and caused the average number of root knots to fall 83.94, 78.03 and 63.66%. These results suggested that NCLB, as a novel nematicides formulation, performed more efficient and longer effective maintenance against plant parasitic nematodes.