Growth and interaction of Mycoplasma bovirhinis and Mycoplasma dispar in vitro

Two mycoplasmas were grown in pure and mixed cultures in glucose calf-serum broth with initial pH 7.8. Sensitivity to pH was also tested. The main data for Mycoplasma bovirhinis and Mycoplasma dispar, respectively, in pure cultures were as follows: lag phase, days: <1, 1–2; log phase: 1–2, 1–4; relatively stationary phase: 0–1, 2–4; decline phase (to the extent roughly logarithmic): 2–6, 5–10; maximal titers: 5 × 10⁷ to 10⁹, 5 × 10⁶ to 10⁸ color changing units per 0.2 ml; highest pH, approximately, at which decline started: 7.7 and 7.0; definitely toxic initial pH: 5.6, 6.8; relative production of acidity; less, more. Decline either shortly ended in loss of viability or, correlated with higher pH levels, led to a prolonged maintenance in lower numbers. The decline of M. bovirhinis was postulated to be essentially caused by an autotoxic product/products other than H⁺.

In mixed cultures an antagonistic effect due to the faster growing M. bovirhinis against M. dispar was recorded. The effect varied according to the initial numbers of organisms and their ratio. Two mechanisms seemed to be active: 1. decrease of pH somewhat below neutrality led to the death of the sensitive M. dispar; 2. M. dispar, when present in relatively high initial numbers, was inhibited by M. bovirhinis during the latter's logarithmic growth at pH-levels above 7.0, the inhibition ending shortly afterwards. A rapidly inactivated product/products of M. bovirhinis metabolism, inhibitory to M. dispar was posited. The results offer an improved insight into diagnostic practices for M. dispar.     

Prevalence of Ehrlichia canis infection in thrombocytopenic dogs from Rio de Janeiro, Brazil

BACKGROUND: Infection with Ehrlichia canis causes a highly variable, multisystemic disease in dogs. Nevertheless, many clinicians in Rio de Janeiro, Brazil, use the presence of only thrombocytopenia to make a presumptive diagnosis of E canis infection. OBJECTIVE: The objective of this study was to determine the prevalence of E canis in thrombocytopenic dogs from Rio de Janeiro, Brazil, using polymerase chain reaction (PCR). METHODS: Following DNA extraction of whole blood samples from 226 dogs, PCR assays were done using primers for rickettsial DNA (including Ehrlichia spp, Anaplasma platys and A phagocytophilum) and using E canis-specific primers (16S rRNA gene). Dogs were grouped as thrombocytopenic and nonthrombocytopenic based on platelet counts. The null hypothesis that there was no difference in the prevalence of E canis in these groups was rejected at P<.05. RESULTS: Thirty-six (32.1%) of the thrombocytopenic dogs and 4 (3.5%) of the nonthrombocytopenic dogs were positive for rickettsial gene sequences (P<.0001). Further, 30 (26.8%) of thrombocytopenic dogs and 4 (3.5%) nonthrombocytopenic dogs were positive for E canis-specific gene sequences (P<.0001). CONCLUSIONS: Although the prevalence of E canis infection was higher in thrombocytopenic dogs, less than one third of these dogs had demonstrable E canis infection. Thus, thrombocytopenia is not specific for the detection of E canis infection and should not be used solely to establish a diagnosis of canine ehrlichiosis, even in a geographic area with relatively high disease prevalence.     

Fatal septicaemia caused by Aeromonas hydrophila in a patient with cirrhosis

In this case report from Italy we describe a fatal infection caused by A. hydrophila in a 39 yr old cirrhotic patient. This pathogen was isolated as a pure single culture from the patient's blood sample. The patient died on the second day of hospitalization from overwhelming sepsis. The A. hydrophila isolate was tested for different potential virulence properties, such as invasiveness, adherence, exotoxins production, presence of fimbriae and for the patterns of resistance to a variety of antimicrobial agents. Although, the Aeromonas species are infrequently reported as a cause of human infections, the present case study confirms the capability of these pathogens to induce serious human infections.     

温度对豹纹鳃棘鲈幼鱼呼吸代谢的影响

研究了温度为15、20、25、30、35℃时豹纹鳃棘鲈幼鱼的代谢情况,并分析了幼鱼利用蛋白质、脂肪和糖类作为能源物质的供能情况。试验结果表明,在15~30℃范围内,各试验组耗氧率、排氨率和二氧化碳排出率均随温度的升高而升高,且差异显著(P0.05);在15~30℃范围内,各试验组呼吸熵、氨熵、代谢率和排泄率均随温度的升高而升高,35℃时均下降。根据氧氮比的分析结果可知,豹纹鳃棘鲈幼鱼主要利用脂肪和蛋白质供能,且随着温度的升高,脂肪和碳水化合物供能的比例逐渐增大。Q10的变化规律反映出豹纹鳃棘鲈幼鱼的适温范围为15~30℃,且温度显著影响豹纹鳃棘鲈幼鱼的代谢率。     

植物细胞的分化与脱分化

细胞分化与脱分化是现代生物学的基本问题之一。综述了植物细胞分化、脱分化过程中的形态结构变化及其调控。结果表明：从形态结构水平很难找出标志细胞分化与脱分化的特征规律。激素被证明对细胞分化与脱分化的调控起作用。生长素与细胞分裂素的作用受到普遍的关注。参18。     

Towards a dengue vaccine: progress to date and remaining challenges

The increased incidence and extended geographical reach of Dengue virus over the past two decades have made the development of an effective vaccine an international urgency. Various strategies are being pursued, including live, vectored and killed/recombinant preparations. For all approaches, the challenge is to induce a broad durable immune response against all four serotypes of Dengue virus simultaneously whilst avoiding the possible exacerbation of risk of developing the severe forms of disease through incomplete or modified responses. This review presents the current state of knowledge and discusses the challenges of further clinical development.     

Lymphoid organ and serologic responses of gnotobiotic and conventional chickens to infectious bronchitis virus and mixed infections of Mycoplasma synoviae and Escherichia coli

Lymphoid organ and serologic responses to infectious bronchitis virus (IBV) and mixed infections of Mycoplasma synoviae (MS) and Escherichia coli (EC) were evaluated in gnotobiotic and conventional chickens. Infectious bronchitis virus combined with MS and EC significantly depressed relative thymus weight and body weight in conventional chickens but not in gnotobiotic chickens. Lymphocyte concentration was greater in the thymic cortex of conventional chickens. Foci of lymphocyte infiltration in the liver and bursal-dependent lymphoid follicles of the spleen were larger in the chickens infected with IBV without apparent influence from the indigenous microflora. Infection with IBV enhanced the immune response to MS.     

动物骨骼标本制作与管理

骨骼标本是一种形象的档案,本文介绍了鹿骨骼标本制作的全过程,所需要的材料及药品,从管理上作了阐述。     

大刍草苗期转录组RNA-Seq数据的de novo拼接

采用solexa测序技术,对大刍草苗期全株各组织转录组进行了RNA-Seq测序、de novo拼接和信息比对研究。结果表明:转录组测序共得到了46.4 GB的原始数据,归并整理后获得长76 bp的序列有175 101 250条,经质量控制和de novo拼接后,共获得了58 147条大刍草转录本,其平均长度为1 335 bp。比对分析发现其中94.3%的转录本和玉米B73自交系的cDNA序列有较好的匹配,与水稻匹配的有84.1%,高粱84.6%,短柄草83.9%,共56 036条转录本。     

葡萄黑痘病病原菌生长特性研究

[目的]探索葡萄黑痘病病原菌在不同培养条件下的生长情况,优化其培养条件,以缩短培养该菌纯培养物的周期,提高培养效率.[方法]通过常规培养手段,从患黑痘病黑巴拉多病叶上分离葡萄黑痘病病原菌,PCR扩增该菌ITS片段,经测序后在NCBI比较该片段序列.用同一规格培养皿培养病原菌,每隔7d观察并统计该病原菌在4种不同培养基组分、5个不同温度梯度、4个不同蔗糖浓度梯度、4种光照时间、5个不同pH条件下共计21 d的生长情况.[结果]分离到病原菌并扩增获得其ITS片段,经比对,该片段序列与NCBI已公布葡萄痂囊腔菌序列AY826763的相似度达99.9%,证实所分离病原菌为葡萄痂囊腔菌(Elsinoe ampelina).葡萄痂囊腔菌的生长最适培养基为PSA,其次是YEB;最适培养温度为25℃、最适蔗糖浓度为4.5 g/L、最适pH为8,在最适培养温度、蔗糖浓度和pH下病原菌的生长速度分别为0.07、0.03和0.01 cm/d;光照时间对葡萄痂囊腔菌生长影响不明显.[结论]葡萄痂圆孢菌生长受环境条件影响,通过培养条件优化能显著加快其生长速度,提高培养效率.