In vitro and in vivo efficacy of lasalocid for treatment of experimental cryptosporidiosis

In vitro viability of purified Cryptosporidium parvum oocysts, exposed for 30, 60, 90 and 120 min to 0.27 mg/ml lasalocid suspension was evaluated by inclusion or exclusion of two fluorogenic vital dyes and an excystation technique. Continuously, preventive and curative efficacies at different doses (9, 6.75, 5.625 and 4.5 mg/kg body weight) and regimens of lasalocid against cryptosporidial infection were evaluated on an experimental neonatal mice model. In vitro assays demonstrated a decrease in the oocyst viability related to an increase in exposure time for exposure to the lasalocid suspension. The infection was eradicated when the suspension was administered with a dose of ≥6.75 mg/kg body weight. No apparent toxic effects were observed.     

白牦牛卵母细胞的采集方法及卵巢贮存条件对其体外成熟的影响

探讨了白牦牛卵母细胞的采集方法以及卵巢保存温度和时间对其体外成熟的影响。结果表明:先抽吸卵泡,每卵巢平均可获可用卵母细胞4.7枚,再切割卵巢,可显著提高可用卵母细胞数9.8枚/卵巢。将屠宰白牦牛卵巢分别置于20~29℃和30~38℃的生理盐水中,6 h内收集卵母细胞,其成熟率、卵裂率分别为65.7%、41.3%和73.3%、45.7%,两者之间的差异均不显著,但均与<20℃组(16.0%、0)差异显著。在30~38℃下,白牦牛卵巢保存时间超过6 h,卵母细胞的成熟率和卵裂率显著下降,卵巢保存时间在2 h以内最好,最晚不超过6 h。     

Voluntary intake of silages in dairy cows depending on chemical composition and in vitro gas production characteristics

A study was conducted to investigate the possibilities to develop models for predicting the relative silage dry matter intake (SDMI) in dairy cows utilising information on chemical composition and in vitro gas production (GP) kinetics of silages. In five experiments, each with an average of 38 lactating dairy cows, SDMI was recorded for 15 grass silages made from primary growth and regrowth swards of timothy (Phleum pratense L.). The silages were characterised by chemical analysis and by utilising an automated in vitro GP recording technique with end point measurements of substrate residues. The silage samples were analysed both as dried and wet samples to evaluate the effects of sample preparation techniques on GP kinetics and their relations to SDMI. Relationships between feed variables and SDMI were investigated utilising simple linear and multiple regression. The wet silage samples had higher cumulative GP and different GP curves compared to the dried samples. The linear relationships between, GP variables, harvest number (first or second cut) of the grass, chemical characteristics of the silages and the relative SDMI show that the GP technique is a powerful tool to detect silage quality. By using the parameters from the dried samples the multiple regression analysis resulted in a relationship, relative SDMI (kg per 100 kg live weight (LW)) per day = 0.071 + 0.0029 × NDFD − 0.266 × C (R² = 0.82, S.D. = 0.06). NDFD is the degradability of the neutral detergent fibre (NDF) (g/kg NDF) and C is the variable that regulates the switching characteristics of the GP profiles. By using the wet silage samples the multiple relationship did not include any GP variable; relative SDMI (kg per 100 kg LW per day) = 1.86 − 0.008 × acetic acid (g/kg DM) + 0.024 × ethanol (g/kg DM) (R² = 0.62, S.D. = 0.08). The results from the regression analysis and the experience of the laborious sample preparation technique for wet samples, give the conclusion that dried silage samples are recommended for determining feed characteristics using the GP technique in intake studies.     

中链脂肪酸对体外发酵甲烷产量的影响

利用人工瘤胃体外产气法研究不同精粗比(0:1和1:1)日粮类型时中链脂肪酸对甲烷产量的影响。结果显示,体外培养24h,添加脂肪酸对甲烷产量的抑制作用不受日粮类型的影响(P>0.05);与不添加酸的对照相比,添加50mg未酯化月桂酸(C12:0)及月桂酸和肉豆蔻酸(C14:0)以3:2的比例组成的混合物(50mg)可分别抑制甲烷产量的22.2%(P<0.01)和11.8%(P<0.05);添加50 mg未酯化C14:0使甲烷产量降低3.4%(P>0.05);不同日粮类型上饲料产气量、瘤胃液pH值和氨氮浓度差异显著(P<0.01)。     

Low temperature storage and in vitro germination of cherimoya (Annona cherimola Mill.) pollen

Due to the protogynous dichogamy of cherimoya and to the absence of proper pollinating vectors, hand-pollination with fresh pollen is a common practice for cherimoya commercial production. In order to optimize the process of hand-pollination, in this work we have studied the conservation of cherimoya pollen at −20, −80 and −196 °C for up to 3 months. In vitro pollen germination of fresh pollen was 57.1% and it was progressively reduced with conservation time at the three temperatures studied reaching a minimum after 3 months of storage of 10.4%, 14.2% and 13.6% at −20, −80 and −196 °C, respectively. Differences in germination among temperatures were only significant during the first 2 weeks of storage. Field pollinations with pollen stored for up to 3 months at the three temperatures show no yield differences compared to pollinations performed with fresh pollen. The results indicate that pollen collected and stored at sub-zero temperatures at the beginning of the cherimoya blooming season can be used along the whole blooming season avoiding the need of collecting fresh pollen daily.     

梨组织中苹果褪绿叶斑病毒的原位RT-PCR检测

 为了建立梨树苹果褪绿叶斑病毒原位RT-PCR检测技术, 用已知带有苹果褪绿叶斑病毒的库尔勒香梨和无病毒实生苗叶片为材料, 利用D IG标记, 研究了香梨病毒的叶片石蜡切片IS-RT-PCR检测技术。包括AMV逆转录酶、dNTPs、RNasin及互补引物浓度对cDNA合成的影响, 退火温度、Taq DNA聚合酶、Mg²⁺ 、引物浓度及循环次数对原位PCR效果的影响。结果表明: RNasin的用量大于0.2 U·μL^-1时,信号强度随着RNasin量的加大而增强; 只有当dNTPs浓度达1.0 mmol·L^-1时才能生成一定量的cDNA;AMV浓度在0.3～0.5 U·μL^-1均可进行正常的逆转录, 而且在该范围内产物的量随AMV浓度提高而增多; 引物浓度达到0.9μmol·L^-1以上时才能进行有效的逆转录, 并且生成的cDNA的量随引物浓度增大而增加。原位扩增ACLSV的cDNA适合退火温度为56℃。循环20～30次可出现较强的蓝色信号, 引物浓度在0.8～1.2μmol·L^-1时显色较好; Taq酶浓度为20 U·mL^-1以上, 均显示较深的蓝色; Mg^{2 +}浓度为1.5mmol·L^-1就可满足原位PCR所需。获得了苹果褪绿叶斑病毒的原位PCR优化检测体系, 利用建立的优化程序对香梨样品进行了检测验证, 取得了很好效果。     

Genetic analysis of an attenuated <Emphasis Type="Italic">Papaya ringspot virus</Emphasis> strain applied for cross-protection

Papaya ringspot virus (PRSV) HA 5-1, a nitrous acid-induced mild mutant of severe strain HA, widely applied for control of PRSV by cross-protection, was used to study the genetic basis of attenuation. Using infectious clones, a series of recombinants was generated between HA 5-1 and HA and their infectivity was analyzed on the systemic host papaya and the local lesion host Chenopodium quinoa. The recombinants that contained mutations in P1 and HC-Pro genes caused attenuated infection on papaya without conspicuous symptoms, similar to HA 5-1. The recombination and sequence analyses strongly implicated two amino acid changes in the C-terminal region of P1 and two in HC-Pro of HA 5-1 involved in the attenuated infection on papaya. The recombinants that infected C. quinoa plants without local lesions contained the same mutations in the C-terminal region of HC-Pro for attenuated infection on papaya. We conclude that both P1 and HC-Pro bear important pathogenicity determinants for the infection on the systemic host papaya and that the mutations in HC-Pro affecting pathogenicity on papaya are also responsible for the inability to induce hypersensitive reaction on C. quinoa.     

Development of immunocompetence of broiler chickens

Subpopulations of T-cells, B-cells, macrophages and ellipsoid-associated reticular cells (EARC) could be demonstrated by immunohistochemical staining early in the development of chicken spleen. However, the typical structures of the spleen, such as the peri-arteriolar lymphoid sheath (PALS) and the ellipsoids with their surrounding ring of macrophages, were only formed around embryonic day (ED) 20. These structures and especially the B-cell compartment, i.e., the peri-ellipsoid lymphoid sheath (PELS) gradually matured during the first week posthatch.

Therefore, we analysed at what age broiler chickens could generate a humoral response against the thymus-dependent antigen bovine serum albumin (BSA). Chickens were immunised in ovo (ED16 and ED18) and at 1, 7 and 12 days of age and subsequent BSA-specific immunoglobulin (Ig) M and IgG responses were measured up to 10 days postimmunisation (DPI). No major differences were observed in the relative growth rates, while hatchability was only slightly reduced. Only in chicks immunised on 12 days of age, IgM and IgG responses were high with a normal kinetic pattern. In chicks immunised on 7 days of age, responses were just detectable, but they were absent in chicks immunised in ovo and on the day of hatching (Day 1).

In a subsequent experiment, 1-, 7- and 12-day-old chicks were BSA-immunised and Ig responses were measured for a longer period up to the age of 28 days. The IgG response of chicks immunised at 1 day of age was lower and occurred later (from 28 DPI) than the response of chicks immunised at 7 and 14 days of age (from 14 DPI). It was not increased by a booster immunisation on 29 days of age, in contrast to the response of chicks immunised at 7 and 14 days of age. These findings indicate that vaccination at 1 day of age does not activate the B-cell response resulting in antibody production and support the idea that the immune function of the late embryonic and neonatal chickens is not entirely developed due to the incomplete structural organisation of their secondary immune organs.     

丝石竹优良单株快速繁殖的研究

本文报道丝石竹优良单株离体快速繁殖和规模化育苗技术。取其切花后萌芽苗的嫩茎段为外植体，培养在ＯＭ培养基上。在附加６—ＢＡ０．５ｍｇ／Ｌ的ＯＭ培养基上，腋芽的诱导和生长最好；在附加６—ＢＡ４＋ＮＡＡ０．０１的ＯＭ培养基上，芽的增殖效果最佳，增殖倍数为２４．４６；ＯＭＯ（不含任何植物激素的ＯＭ培养基）最利于壮苗；在ＯＭ培养基中附加ＩＢＡ０．１～０．３，不定根诱导和生长效果最佳，生根率达９８．６％。试管苗移入珍珠岩中生长最好，移植成活率为９２％。     

NG在枣试管苗继代培养中的效应

NG是一种非生长激素类的化学药剂。经试验证明:NG是枣组织培养中一种有效的新型生长调节物质。以H培养基为基本培养基,附加70％NG100mg·l~(-1),可显著地提高枣试管继代繁殖材料发芽数,在75～200mg·l~(-1)范围内,随浓度的提高,单芽梢生长量有显著下降的趋势,大于75mg·l~(-1)抑制生根。25mg·l~(-1)、50mg·l~(-1)的NG有利于枣试管继代繁殖材料生根,使芽梢生长粗壮,单株芽梢的总生长量也显著增加,而且用作继代繁殖材料利用率高。