三种食用百合种质资源限制生长保存及遗传稳定性研究

以3种食用百合试管苗为试材,采用限制生长保存法,研究了不同浓度生长抑制剂对食用百合试管苗保存效果的影响,并对保存后的试管苗进行遗传稳定性检测,以期建立食用百合种质资源离体保存体系。结果表明:龙芽百合试管苗用10mg·L~(-1)防落素(PCPA)处理保存300d后,试管苗生长缓慢,存活率达96.00%;川百合试管苗用2.0mg·L~(-1)青鲜素(MH)处理保存150d后,试管苗的抑制生长效果明显,结鳞率和存活率高达100.00%;兰州百合试管苗用10mg·L~(-1)多效唑(PP333)处理保存300d后,试管苗抑制作用明显,结鳞率达100.00%,存活率达94.40%。比较限制生长保存后与未保存植株的可溶性蛋白和酯酶同工酶图谱,各处理和对照图谱带相似,初步证明了以上保存方法的可行性,较好的保持了遗传稳定性。     

不同低温春化天数和赤霉素处理对解除洋桔梗莲座化的影响

以2个洋桔梗品种"雪莱香槟"(‘Ceremony Orange’)和"露西塔I白底粉边"(‘Rosita I Pink Picotee’)为试材,研究了育苗期种子低温(10℃)春化处理天数(35、28、21、14、0d)及栽培期赤霉素处理对解除洋桔梗莲座化的影响,探寻了生产上解除洋桔梗莲座化技术。结果表明:2个品种低温春化处理28d均能提高种子发芽率。定植60d后,低温春化处理35d洋桔梗‘Ceremony Orange’抽薹率最高,达72.9%;低温春化处理28d‘Rosita I Pink Picotee’抽薹率最高,达89.6%。栽培期对未经种子低温春化处理的洋桔梗‘Ceremony Orange’莲座化苗进行赤霉素处理(处理浓度为0、50、100、150mg·L~(-1)),100mg·L~(-1)赤霉素处理对促进洋桔梗节间的伸长有明显作用,抽薹率达70.5%,可以有效打破莲座化。比较2种解除莲座化的处理效果,生产上解除洋桔梗莲座化方法可首选种子低温春化处理,该方法上花时间比栽培期赤霉素处理提早2个多月;栽培期赤霉素处理可以作为种子低温春化未打破莲座化的辅助措施。     

Validity of goniometric joint measurements in cats

OBJECTIVE: To compare and validate goniometric joint measurements obtained from nonsedated and sedated cats with measurements from radiographic evaluation. ANIMALS: 20 adult cats with no evidence of joint disease. PROCEDURES: Measurements of flexion and extension of the carpus, elbow, shoulder, tarsus, stifle, and hip joints and of carpal and tarsal joints during varus and valgus angulation were made by a single investigator before and after sedation of cats. Measurements were made by use of a goniometer with a masked dial. Joint angle measurements were compared between nonsedated and sedated cats and also with measurements from radiographs made while cats were sedated. Each series of measurements was repeated 4 times. To evaluate repeatability, Cronbach alpha values were calculated for repeated measure results of goniometric joint measurements of nonsedated and sedated cats. An intraclass correlation was calculated to determine reliability among the 3 measurement types (ie, measurements from nonsedated and sedated cats and on radiographic evaluation). RESULTS: Joint measurements did not differ significantly by measurement type, when comparing radiographic measurements with goniometric measurements in sedated and nonsedated cats. Cronbach alpha values were > 0.99 for goniometric joint measurements within individual nonsedated and sedated cats and also for comparison of mean measurements obtained from sedated cats versus nonsedated cats versus radiographs. An intraclass correlation of 0.999 revealed high reliability among measurement types. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that goniometric joint measurements in nonsedated and sedated cats are repeatable and valid.     

High prevalence of methicillin resistant Staphylococcus aureus in pigs

Recently methicillin resistant Staphylococcus aureus (MRSA) was isolated from pigs and pig farmers in The Netherlands. In order to assess the dissemination of MRSA in the Dutch pig population, we screened 540 pigs in 9 slaughterhouses, where a representative portion of Dutch pigs (63%) was slaughtered in 2005. We found 209 (39%) of the pigs to carry MRSA in their nares. Forty-four of 54 groups of 10 consecutive pigs (81%), each group from a different farm, and all slaughterhouses were affected. All MRSA isolates belonged to 1 clonal group, showing Multi-Locus Sequence Type 398 and closely related spa types (mainly t011, t108 and t1254). Three types of the Staphylococcal Chromosome Cassette (SCCmec) were found: III (3%), IVa (39%) and V (57%). All 44 tested isolates (1 isolate per group) were resistant to tetracycline, reflecting the high and predominant use of tetracyclines in pig husbandry. Twenty-three percent of the isolates were resistant to both erythromycin and clindamycin and 36% to kanamycin, gentamicin and tobramycin but only a single isolate was resistant to co-trimoxazole and none to ciprofloxacin and several other antibiotics. The percentage of MRSA positive pigs was significantly different among slaughterhouses and among groups within slaughterhouses, indicating a high prevalence of MRSA in pigs delivered from the farms as well as cross contamination in the slaughterhouses.     

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.     

Seasonal and photoperiodic regulation of secretion of hormones associated with reproduction in Magang goose ganders

This study examined the reproductive endocrine profile under natural and artificial photoperiods in Magang goose ganders. Group 1 ganders (n=8) served as non-treated controls and were exposed to natural photoperiod throughout the experiment from 13th January to 17th December 2004. Group 2 ganders (n=8) were exposed to 18 h long daily photoperiod for 60 days from 13 January till 15 March 2004 and again to 16 h photoperiod for 75 days till 10th October 2004, and the 11h short photoperiod in the remainder periods of the experiment. In control ganders, plasma LH concentrations were high in normal breeding seasons (August-March) and decreased to low levels in non-breeding season from April to July. Testosterone concentrations changed similarly to that of LH throughout the seasons. Seasonal pattern of PRL concentrations was opposite to those of LH and testosterone, with low values in breeding season and high values in non-breeding season. In artificial photoperiod treated ganders, increasing photoperiod increased PRL and decreased LH and testosterone concentrations, while decreasing photoperiod reversed these changes. There were no seasonal or photoperiod caused changes in plasma T3 concentrations in both control ganders and artificial photoperiod treated ganders. These results demonstrated that in Magang goose ganders that long photoperiod stimulates PRL secretion and decreases LH secretion, which terminates reproductive season in spring and early summer, and short photoperiod stimulates LH secretion and inhibits PRL secretion rendering ganders enter into reproductive season.     

非亲和性稻瘟病菌对水稻的诱导抗性

为研究稻瘟病菌Magnaporthe oryzae不同菌株间的相互作用,选择与单抗性基因系水稻IRBL5-M （携带抗性基因Pi5）表现为亲和性的菌株HN52与非亲和性的菌株HN119为研究对象,将其单独或混合接种到单抗性基因系水稻IRBL5-M中,并通过荧光显微镜观察接种后水稻叶鞘的发病情况及病斑面积,测定接种后水稻内相关抗性基因OsWRKY45、OsNPR1、OsPR10、OsMAPK2的表达量以及活性氧的变化。结果显示,相较于单独接种亲和性菌株,混合接种后单抗性基因系水稻IRBL5-M病斑发病面积减少;混合接种中亲和性菌株HN52菌丝侵染能力降低,侵染菌丝细胞间扩展率显著降低73.13%;同时单抗性基因系水稻IRBL5-M中OsWRKY45、OsNPR1、OsPR10和OsMAPK2抗性基因表达量显著增加,水稻叶片中活性氧含量增加,表明在菌株混合侵染过程中,非亲和性菌株可通过激发水稻的抗性反应来降低亲和性菌株对水稻的侵染程度。     

Nutrient addition and disturbance effects on the community composition and assembly in a desert steppe北大核心CSCD

The effects of short-term nutrient additions (NPKμ, 10 g·m- 2) and disturbances on the species diversity, functional traits, soil properties, and community assembly mechanisms of the herbaceous community in the Urat desert steppe were examined. A mixed linear model, principal component analysis, and null model methods were utilized and both disturbance and interaction treatments were found to significantly reduce species richness and β diversity. Short-term nutrient additions significantly reduced soil pH but increased soil electrical conductivity. Six functional traits of the dominant species (i.e. Stipa glareosa, Peganum harmala, Salsola collina, Corispermum mongolicum) and six community-weighted mean significant changes under the disturbance and nutrient addition treatments were identified. The disturbance and nutrient additions promoted the transformation of the dominant species in the community from conservative strategies to acquisitive strategies. The results of the two null models revealed that community assembly under the control tended to be a stochastic process, while the disturbance and interaction treatments tended to be deterministic processes, and that of the nutrient addition treatments tended to be weaker deterministic processes. Plant communities in the desert steppe responded and adapted to the nutrient additions and disturbances through changes in the dominant species and their crucial functional traits. © 2023 Chinese Academy of Sciences. All rights reserved.     

Effects of Bacillus amylolyticus on Rumen Dry Matter Digestibility,Fermentation Parameters and Metabolites of Dairy Cows北大核心CSCD

This experiment was conducted to study the effects of Bacillus amylolyticus on rumen dry matter digestibility, fermentation parameters and metabolites of dairy cows. Experiment 1: six dairy cows with permanent fistula and had the similar parity (2 to 3 fetuses), body weight [(662 ±57) kg], lactation days [(160 ± 22) d] and milk yield [(36.1 ±3.8) kg / d], were randomly divided into 3 groups with 2 cows per group. Using 3 ×3 Latin square design, each group was extra fed 0 (control group), 5 ×109 and 5 ×1010 CFU / d Bacillus amylolyticus, the trial period was 3 periods, 13 days for each period, including 10 days for the pre-trial period and 3 days for the trial period. At the beginning of the trial period, the rumen dry matter digestibility of cows was measured by nylon bag method. Experiment 2: thirty dairy cows with similar parity [(2.5 ±0.3) fetuses], initial body weight [(559.2 ± 7. 4) kg], milk yield [(35. 2 ± 1. 5) kg / d] and lactation days [(99 ± 22) d] were randomly divided into three groups with 10 cows in each group. Cows in the 3 groups were extra fed with 0 (control group), 5 ×109 and 5 ×1010 CFU / d Bacillus amylolyticus, respectively. The pre-trial period was 10 days and the trial period was 42 days. The rumen fluid was collected on the last day of the trial period, and the rumen fermentation parameters and metabolites were determined. The results showed as follows: compared with the control group, 1) supplementary feeding of 5 × 1010 CFU / d Bacillus amylolyticus could significantly improve the rumen dry matter digestibility of dairy cows at 12, 24, 36, 48 and 72 h (P <0.05), supplementary feeding of 5 ×109 CFU / d Bacillus amylolyticus could significantly improve the rumen dry matter digestibility of dairy cows at 36 and 48 h (P <0.05); 2) supplementary feeding of 5 ×109 CFU / d Bacillus amylolyticus could significantly increase the contents of isobutyric acid, butyric acid, isovaleric acid, valeric acid, total volatile fatty acid and microbial protein in the rumen of dairy cows (P < 0. 05), supplementary feeding of 5 × 1010 CFU / d Bacillus amylolyticus could significantly increase the contents of isobutyric acid and isovaleric acid in the rumen of dairy cows and significantly reduce the rumen acetic acid / propionic acid (P < 0. 05), supplementary feeding of 5 ×109 and 5 ×1010 Bacillus amylolyticus had no effects on rumen pH and ammonia nitrogen content (P >0.05); 3) eleven metabolic pathways related to differential metabolites were detected, and ascorbic acid and alginate metabolism were significantly enriched (P < 0. 05) . In conclusion, Bacillus amylolyticus can increase the rumen dry matter digestibility, and improve the rumen fermentation function of dairy cows by affecting the content of rumen metabolites. By comprehensive analysis, supplementary feeding of 5 × 109 CFU / d Bacillus amylolyticus can achieve better effect. © 2023 Authors. All rights reserved.