Pre-parturition staphylococcal mastitis in primiparous replacement goats: persistence over lactation and sources of infection     

Iacome SC Jácome  Francisca GC Sousa  Candice MG De Leon  Denis A Spricigo  Mauro MS Saraiva  Patricia EN Givisiez  Wondwossen A Gebreyes  Rafael FC Vieira  Celso JB Oliveira 《Veterinary research》2014,45(1)

This investigation reported for the first time the occurrence of intramammary infections caused by Staphylococcus in primiparous replacement goats before parturition and the persistence of clinical Staphylococcus aureus infection during the lactation period. Subclinical infections, mainly caused by coagulase negative staphylococci (CoNS), did not persist during lactation. Genotyping analysis indicated that environment seems to play a moderate role as source of intramammary infections to goats before parturition, but causative agents of mastitis in lactating animals are not genotypically related to environmental staphylococci. The occurrence and persistence of intramammary infections in replacement goats demonstrate the need to consider those animals as potential sources of infections in dairy goat herds.  相似文献   

Comparison of Conventional Freezing and Vitrification with Dimethylformamide and Ethylene Glycol for Cryopreservation of Ovine Embryos     

FC Varago  VS Moutacas  BC Carvalho  RV Serapião  F Vieira  H Chiarini‐Garcia  FZ Brandão  LS Camargo  M Henry  MA Lagares 《Reproduction in domestic animals》2014,49(5):839-844

The aim of this work was to evaluate the efficiency of the cryoprotectants dimethylformamide and ethylene glycol for cryopreservation of ovine embryos using vitrification and conventional freezing. The recovered embryos were distributed randomly in three treatment groups: Gr. 1: conventional freezing (n = 44), Gr. 2: vitrification with ethylene glycol (n = 39) and Gr. 3: vitrification with dimethylformamide (n = 38). Quality of fresh embryos in control group as well as of frozen and vitrified embryos was examined by three methodologies: staining with propidium iodide and Hoechst 33258 and evaluation under fluorescent microscopy, evaluation of re‐expansion and hatching rates after culture, and determination of apoptotic index with TUNEL technique. It was established that re‐expansion rate in all treatment groups was similar. In the same time, hatching rates were higher in Gr. 1 (40.5%) and Gr. 2 (35.3%) in comparison with Gr. 3 (15.5%, p < 0.05). The number of dead cells in vitrified embryos of Gr. 2 and Gr. 3 was higher (42.6 ± 26.2 and 63.2 ± 34.65, respectively) in comparison with Gr. 1 (conventional freezing, 10.1 ± 8.5, p < 0.05). Embryos vitrified with dimethylformamide included the same quality of apoptotic cells that Gr. 1 (conventional freezing) and fresh embryos. In conclusion, the dimethylformamide and ethylene glycol used as cryoprotectant to vitrify ovine embryos, in the concentrations and exposition time tested in this work, were not as efficient as the conventional freezing for cryopreservation of ovine embryos Thus, the conventional freezing with ethylene glycol was the most efficient method to cryopreserve ovine embryos in comparison with vitrification.  相似文献   

Export performance of major cultured shrimp producers in the Japanese and US markets   总被引：1，自引：0，他引：1  

B H Ling  P S Leung  Y C Shang 《Aquaculture Research》1996,27(10):775-786

Increase in shrimp farming was stimulated by growth in world market for high-value shrimp products in the 1980s. The major cultured shrimp producers are located in Asia-Pacific and Latin American regions. The revealed comparative advantage (RCA) method is used to provide insights into the export performance of nine selected shrimp producers in the Japan and United States markets, separately. Shrimp is marketed in a wide variety of product forms, and prices vary according to various product attributes including species, size, taste, quality and origin. The results show that vertical product differentiation concerning different varieties of a good in terms of both quality and price plays an important role on the relative export competition of shrimp products among major shrimp-exporting countries. As a result of the geographical advantage, Asia-Pacific producers enjoy comparative advantage in the Japanese imported shrimp market. Joint ventures with the United States provide great benefits to Ecuador and Mexico in exporting fresh shrimp into the United States market.  相似文献   

Orientational ordering of polymers by atomic force microscope tip-surface interaction     

Leung OM  Goh MC 《Science (New York, N.Y.)》1992,255(5040):64-66

Results of studies on the interaction between the tip of an atomic force microscope and polystyrene molecules in a film spread on a surface are reported. The tip produces a persistent deformation on the film; some of the polymer molecules are eventually pulled up by the tip. Nanometer-size structures are induced, resulting in a pattern that is periodic and is oriented perpendicular to the scan direction.  相似文献   

Transmission dynamics of the etiological agent of SARS in Hong Kong: impact of public health interventions   总被引：2，自引：0，他引：2  

Riley S  Fraser C  Donnelly CA  Ghani AC  Abu-Raddad LJ  Hedley AJ  Leung GM  Ho LM  Lam TH  Thach TQ  Chau P  Chan KP  Lo SV  Leung PY  Tsang T  Ho W  Lee KH  Lau EM  Ferguson NM  Anderson RM 《Science (New York, N.Y.)》2003,300(5627):1961-1966

We present an analysis of the first 10 weeks of the severe acute respiratory syndrome (SARS) epidemic in Hong Kong. The epidemic to date has been characterized by two large clusters-initiated by two separate "super-spread" events (SSEs)-and by ongoing community transmission. By fitting a stochastic model to data on 1512 cases, including these clusters, we show that the etiological agent of SARS is moderately transmissible. Excluding SSEs, we estimate that 2.7 secondary infections were generated per case on average at the start of the epidemic, with a substantial contribution from hospital transmission. Transmission rates fell during the epidemic, primarily as a result of reductions in population contact rates and improved hospital infection control, but also because of more rapid hospital attendance by symptomatic individuals. As a result, the epidemic is now in decline, although continued vigilance is necessary for this to be maintained. Restrictions on longer range population movement are shown to be a potentially useful additional control measure in some contexts. We estimate that most currently infected persons are now hospitalized, which highlights the importance of control of nosocomial transmission.  相似文献   

Toward direct measurement of atmospheric nucleation     

Kulmala M  Riipinen I  Sipilä M  Manninen HE  Petäjä T  Junninen H  Maso MD  Mordas G  Mirme A  Vana M  Hirsikko A  Laakso L  Harrison RM  Hanson I  Leung C  Lehtinen KE  Kerminen VM 《Science (New York, N.Y.)》2007,318(5847):89-92

Atmospheric aerosol formation is known to occur almost all over the world, and the importance of these particles to climate and air quality has been recognized. Although almost all of the processes driving aerosol formation take place below a particle diameter of 3 nanometers, observations cover only larger particles. We introduce an instrumental setup to measure atmospheric concentrations of both neutral and charged nanometer-sized clusters. By applying the instruments in the field, we come to three important conclusions: (i) A pool of numerous neutral clusters in the sub-3 nanometer size range is continuously present; (ii) the processes initiating atmospheric aerosol formation start from particle sizes of approximately 1.5 nanometers; and (iii) neutral nucleation dominates over the ion-induced mechanism, at least in boreal forest conditions.  相似文献   

Genomics and agriculture. Collaborations in rice     

Fischer KS  Barton J  Khush GS  Leung H  Cantrell R 《Science (New York, N.Y.)》2000,290(5490):279-280

Advances in rice genomics will contribute to gene discovery and rice productivity, but many of the products with high potential for alleviating poverty and improving human nutrition may not be those that attract private investment. Although most genetic resources and biological expertise for functional genomics are in the public, many proprietary technologies are owned by the private sector. A public resource platform is needed for the application of genomic technology to accelerate gene discovery. We present a model and general principles in collaboration that can serve the poor and encourage innovation by both the public and private sectors.  相似文献   

Achieving stability of lipopolysaccharide-induced NF-kappaB activation     

Covert MW  Leung TH  Gaston JE  Baltimore D 《Science (New York, N.Y.)》2005,309(5742):1854-1857

  相似文献   

Mycotoxins in pet food: a review on worldwide prevalence and preventative strategies     

Leung MC  Díaz-Llano G  Smith TK 《Journal of agricultural and food chemistry》2006,54(26):9623-9635

Mycotoxins contaminate cereal grains worldwide, and their presence in pet food has been a potential health threat to companion animals. Aflatoxins, ochratoxin A, and Fusarium mycotoxins have been found in both raw ingredients and final products of pet food around the globe. Aflatoxin, a hepatotoxin and carcinogen, has caused several food poisoning outbreaks in dogs, and aflatoxin content is regulated in pet food in many countries. Ochratoxin A and Fusarium mycotoxins including trichothecenes, zearalenone, and fumonisins may have chronic effects on the health of companion animals. Grain processing, sampling error, analytical methods, conjugated mycotoxins, storage conditions, and synergistic interactions are common challenges faced by the pet food industry. Food-processing techniques such as sieving, washing, pearling, ozonation, and acid-based mold inhibition reduce the mycotoxin content of cereal grains. Dietary supplementation with large neutral amino acids, antioxidants, and omega-3 polysaturated fatty acids as well as inclusion of mycotoxin-sequestering agents and detoxifying microbes may ameliorate the harmful effects of mycotoxins in contaminated pet food.  相似文献   

稻瘟病菌致病突变株的分离   总被引：4，自引：1，他引：3  

何月秋  唐文华 《云南农业大学学报(自然科学版)》2000,15(3):197-199

 利用4个分属宗亲群4,7,17 和44的菌株连续接种在C039的单基因近等基因系和基因累加系上, 以获得突变抗病基因新菌株。经13轮接种循环, 共分离到9个新菌株。其中8个针对C101LAC(Pi－1) 突变 , 另1个针对C101PKT (Pi－4a)和F128 (Pi－ta²) 的双位点突变。4个原始菌株, P06－6, 9248－6, 9239－4和101－7－2的突变频率分别为: 0, 2.82×10^－5, 2.05×10^－5 和9.09×10^－5。菌株针对不同抗病基因的突变频率不同,由Av－1变到Av－1^＋和由Avir－4a(t)突变到Av－4a^＋的频率分别为7.51×10^－5和6.14×10^－5。没有针对Pi－2突变体出现。  相似文献