Studies on the potential use of Pasteuria penetrans as a biocontrol agent of root-knot nematodes (Meloidogyne spp.)

Some aspects of the interaction of the bacterial parasite Pasteuria penetrans and the root-knot nematode ( Meloidogyne spp.) were investigated in laboratory and pot experiments. The variable spore attachment on juveniles exposed to water suspensions of the bacterium is probably attributed to differential susceptibility of biotypes within a heterogeneous Meloidogyne population. The relationship between spore concentration and attachment level is not linear over a range of spore dosages, indicating that even at very high spore concentrations the number of spores capable of attachment may not be present in excess and it is difficult to ensure sufficient numbers of spores to ensure infection will attach to all nematodes. Attempts to apply the bacterium in conditions such as might occur in seedbeds did not suppress nematode multiplication after transplanting in nematode-infested soil, indicating that the only effective application method is a thorough spore distribution in the planting sites. Two major constraints were revealed: high levels of spore attachment to juveniles does not always guarantee a significant reduction of egg laying and this is greatly influenced by the Meloidogyne biotype. Furthermore, the cumulative effect of the parasite in reducing Meloidogyne populations over several crop cycles was less than expected as the bacterium reduced intra-specific competition for the food supply and the less damaged root enabled many nematodes to survive.     

Feeding fodder beet (Beta vulgaris L.) with either barley straw or pasture silage to non-lactating dairy cows

AIMS: To determine the suitability of diets containing either approximately 85% fodder beet (Beta vulgaris L.) with barley straw or 65% fodder beet with pasture silage when fed to non-lactating dairy cows, by measuring intakes, digestibility, rumen function including microbial growth, and N excretion.

METHODS: Holstein-Friesian cows fitted with permanent rumen fistulae were fed either 65% fodder beet with pasture silage (Silage; n=8) or 85% fodder beet with barley (Hordeum vulgare L.) straw (Straw; n=8) in an indoor facility over a 9-day period, for measurement of intakes, digestibility, rumen function and urine production. The cows were adapted to the diets over 2 weeks before the indoor measurements. Feed was available for about 6 hours/day, as practiced commercially for wintering non-lactating cows.

RESULTS: Five cows fed the Straw diet had to be removed from the trial because of acute acidosis; four on Day 1 of the measurement period and one on Day 7. One cow allocated to the Silage diet refused to eat fodder beet bulbs and was also removed from the trial. Two cows fed the Silage diet were also treated for acidosis. DM intakes were lower with the Straw than Silage diets (6.4 (SE 0.4) vs. 8.3 (SE 0.5) kg/day) and organic matter (OM) digestibility was lower with the Straw than Silage diets (77 (SE 1) vs. 83 (SE 1) g/100g). The N content of the two diets was 1.14 and 1.75?g/100?g DM and there was a net loss of N by cows fed the Straw diet (?22.7 (SE 7) g/day). Rumen microbial N production was much lower in cows fed the Straw than the Silage diet (6.6 (SE 1.3) vs. 15.8 (SE 0.7) g microbial N/kg digestible OM intake). Concentrations of ammonia in rumen liquid collected on Days 5–6 were below detection limits (<0.1?mmol/L) in 36/48 (75%) samples collected from cows fed the Straw diet and in 27/48 (56%) cows fed the Silage diet. Mean urinary N excretion was lower in cows fed the Straw than the Silage diet (52.0 (SE 5.8) vs. 87.7 (SE 5.9) g/day).

CONCLUSION AND CLINICAL RELEVENCE: An over-wintering diet for dry cows comprising about 65% fodder beet with 35% pasture silage provided adequate nutrition, although there was some risk of acidosis. In contrast, the diet containing about 85% fodder beet with barley straw resulted in lower DM intakes, poor rumen function, negative N balance so that both nutrition and welfare were compromised.     

多年生人工草地矮生嵩草(Kobresia humilis)种群空间格局与种内关联性

植物种群空间分布格局不仅反映植物的空间分布特点,还有助于研究者了解植物利用资源的现状和生存能力。本研究以矮生嵩草(Kobresia humilis)为研究对象,按株丛斑块面积将矮生嵩草分为小斑块级株丛(0～30 cm²)、中斑块级株丛(30～80 cm²)和大斑块级株丛(>80 cm²)3个株丛级,采用点格局分析的g函数统计方法,分析了矮生嵩草各级株丛的空间格局及关联性。结果表明：矮生嵩草种群中小斑块级株丛占比高于中斑块、大斑块级株丛占比,种群中幼苗充足,正处于稳定的增长阶段;矮生嵩草小斑块、中斑块、大斑块级株丛在小尺度范围内表现为聚集分布,随着尺度的增大,所有株丛斑块的聚集程度减弱,逐渐趋向于随机分布;小斑块与中斑块、大斑块的矮生嵩草株丛在小尺度内表现为正关联。斑块聚集分布和相互共存是矮生嵩草的一种生存策略。     

Acute oral toxicity of zinc phosphide: an assessment for wild house mice (Mus musculus)

Irregular plagues of house mice, Mus musculus, incur major economic impacts on agricultural production in Australia. The efficacy of zinc phosphide (ZnP), the only registered broadacre control agent for mice, is reported as increasingly variable. Have mice become less sensitive over time or are they taking a sub-lethal dose and developing aversion? In this laboratory study, the sensitivity of mice (wild caught; outbred laboratory strain) was assessed using oral gavage of a range of ZnP concentrations. The estimated LD₅₀ values (72–79 mg ZnP/kg body weight) were similar for each mouse group but are significantly higher than previously reported. The willingness of mice to consume ZnP-coated grains was determined. ZnP-coated grains (50 g ZnP/kg grain) presented in the absence of alternative food were consumed and 94% of wild mice died. Mice provided with alternative food and ZnP-coated wheat grains (either 25 or 50 g ZnP/kg grain) consumed toxic and non-toxic grains, and mortality was lower (33–55%). If a sublethal amount of ZnP-coated grain was consumed, aversion occurred, mostly when alternative food was present. The sensitivity of wild house mice to ZnP in Australia is significantly lower than previously assumed. Under laboratory conditions, ZnP-coated grains coated with a new higher dose (50 g ZnP/kg grain) were readily consumed. Consumption of toxic grain occurred when alternative food was available but was decreased. Our unambiguous findings for house mice indicate a re-assessment of the ZnP loading for baits used for control of many rodents around the world may be warranted.     

Co-inoculation of selected nodule endophytic rhizobacterial strains with Rhizobium tropici promotes plant growth and controls damping off in common bean

Production of common bean(Phaseolus vulgaris)is limited by the occurrence of damping off(rhizoctoniosis),which is caused by the fungus Rhizoctonia solani.However,the co-inoculation of plant growth-promoting rhizobacteria(PGPR)involved in biological control along with diatomic nitrogen(N2)-fixing rhizobia can enhance N nutrition and increase production.In this context,finding microorganisms with synergistic effects that perform these two roles is of fundamental importance to ensure adequate yield levels.The aim of this study was to evaluate the effects of co-inoculation of nodule endophytic strains of the genera Bacillus,Paenibacillus,Burkholderia,and Pseudomonas with Rhizobium tropici CIAT 899,an N2-fixing rhizobial strain,on the biocontrol of damping off and growth promotion in common bean plants.Greenhouse experiments were conducted under axenic conditions using the common bean cultivar Pérola.The first experiment evaluated the potential of the 14 rhizobacterial strains,which were inoculated alone or in combination with CIAT 899,for the control of R.solani.The second experiment evaluated the ability of these 14 rhizobacterial strains to promote plant growth with three manners of N supply:co-inoculation with CIAT 899 at low mineral N supply(5.25 mg N mL^-1),low mineral N supply(5.25 mg N mL^-1),and high mineral N supply(52.5 mg N mL^-1).The use of rhizobacteria combined with rhizobia contributed in a synergistic manner to the promotion of growth and the control of damping off in the common bean.Co-inoculation of the strains UFLA 02-281/03-18(Pseudomonas sp.),UFLA 02-286(Bacillus sp.),and UFLA 04-227(Burkholderia fungorum)together with CIAT 899 effectively controlled damping off.For the common bean,mineral N supply can be replaced by the co-inoculation of CIAT 899 with plant growth-promoting strains UFLA 02-281/02-286/02-290/02-293.Nodule endophytes UFLA02-281/02-286 are promising for co-inoculation with CIAT 899 in the common bean,promoting synergy with rhizobial inoculation and protection against disease.     

噬菌体复合制剂对肉鸡生长性能、免疫功能、肠道形态及肠道菌群的影响

本试验旨在研究噬菌体复合制剂对肉鸡生长性能、免疫功能、肠道形态及肠道菌群的影响。选取14 000只体重（850±45） g的37日龄青脚麻鸡,随机分为2组,分别是对照组（基础饲粮）和试验组（基础饲粮+109PFU/mL的噬菌体复合制剂）,每组7个重复,每个重复1 000只,试验期27 d。结果表明：1）与对照组相比,试验组的料重比下降2.81%(P>0.05)。2）与对照组相比,43日龄时,试验组肉鸡胸腺指数和脾脏指数分别增加16.80%(P<0.05)和7.14%(P>0.05);52日龄时,肉鸡法氏囊指数和胸腺指数分别增加8.55%(P>0.05)和7.37%(P>0.05);61日龄时,肉鸡法氏囊指数增加39.66%(P>0.05);43、52及61日龄时,试验组肉鸡血清免疫球蛋白G(IgG)含量分别增加15.85%(P>0.05)、29.54%(P>0.05)和1.45%(P>0.05)。3）与对照组相比,43、52及61日龄时,试验组肉鸡十二指肠、空肠、回肠绒毛高度/隐窝深度显著提高（P<0.05）。4）在门水平上,...     

不同含水率对四倍体刺槐抗弯强度及弹性模量的影响

为研究四倍体刺槐在弯曲负荷作用下破裂或折弯的变化规律,用数理统计的方法在万能力学试验机上对不同含水率的四倍体刺槐枝条的弯曲力学特性进行了研究。结果表明,4种含水率水平下,四倍体刺槐在弯曲载荷作用下的抗弯强度为54.12～94.42 MPa、弹性模量为4.81～9.30GPa。四倍体刺槐枝条的最大载荷在各个含水率水平下均随枝条直径的增大呈线性提高。四倍体刺槐的抗弯强度及弹性模量与含水率水平成一元线性相关关系,随含水率水平的降低四倍体刺槐的抗弯强度及弹性模量呈线性增大。     

我国野生披碱草属牧草居群的穗部形态多样性研究

对采集自我国12个不同分布区的105个野生披碱草属(Elymus)牧草居群的14项穗部形态指标进行研究,结果表明,我国披碱草属牧草种质资源穗部遗传多样性丰富,居群内多样性指数(H′)在0.784～1.652,平均多样性指数为1.396;居群总平均多样性指数为1.936,居群间表型分化系数为27.89%。14项穗部形态性状在居群内多样性、居群总多样性以及变异系数变化不完全一致,居群内H′最高的为旗叶与穗基部长度(1.648),居群总H′最高的为小穗长(2.054),变异系数最大的为第一颖芒长(58.932%),平均变异系数为31.22%,表明穗部形态性状均存在较大的变异,F检验差异极显著。引起居群形态差异的性状与种子产量密切相关,主要包括穗长、穗宽、第一颖芒长、第一外稃长、第一内稃长、第一外稃芒长、每穗轴小花数、第一颖长和第一颖宽。我国野生披碱草属牧草的多样性和分布格局是相关的,我国西北部是野生披碱草属牧草分布中心,也是披碱草属牧草的多样性中心。此外,提出了我国披碱草属牧草保护的策略。     

Immunohistochemical Detection of Mycoplasma agalactiae in Formalin‐Fixed,Paraffin‐Embedded Tissues from Naturally and Experimentally Infected Goats

Samples from the mammary tissue of 14 lactating goats (12 naturally infected and two experimentally infected) were examined for the presence of Mycoplasma agalactiae. A monoclonal antibody (5G12) was applied to formalin‐fixed, paraffin‐wax‐embedded sections and labelled by the avidin–biotin peroxidase complex (ABC) method. Histological examination of tissue sections revealed strong immunoreactivity in all animals included in the study. Mycoplasma agalactiae antigen was mainly detected in the cellular debris at the periphery of purulent exudates present within lactiferous sinuses, and lactiferous and interlobular ducts. In addition, M. agalactiae organisms appeared in the cytoplasm of the epithelium of ducts, and in infiltrating macrophages and neutrophils within the ducts, alveoli, interstitial tissue and regional lymph node sinuses. It is concluded that this monoclonal antibody‐based immunohistochemical technique is an efficient and specific method for the post‐mortem detection of M. agalactiae in cases of clinical mastitis as well as being a useful tool for the study of the route of infection and cellular types involved during mastitis caused by this organism.     

Effect of magnitude and direction of force on laryngeal abduction: Implications for the nerve‐muscle pedicle graft technique

Reasons for performing study: The nerve‐muscle pedicle graft technique is a treatment for recurrent laryngeal neuropathy (RLN), but the optimal placement of the pedicles within the cricoarytenoideus dorsalis (CAD) muscle is unknown. Hypothesis: The magnitude and direction of force placed on the muscular process of the left arytenoid cartilage affects the magnitude of laryngeal abduction. Methods: Five larynges were harvested from cadavers. Using increments of 0.98 N, a dead‐weight force generator applied a force of 0–14.7 N for 1 min each to the left muscular process at 0, 10, 20, 30, 40, 50, 60 and 70° angles. The rima glottis was photographed digitally 1 min after each force had been applied. Distances between biomarkers (Lines 1–4) and right to left angle quotient (RLQ) were used to assess the degree of left arytenoid abduction. Results: Increasing force from 0–14.7 N progressively and significantly increased the length of all lines and RLQ, indicating abduction. Furthermore, there was a significant interaction between force and angles. Applying forces of 7.84 N or greater (Lines 2–4 and RLQ) or 11.76 N or greater (Line 1) at angles 0, 10, 20 and 30° resulted in significantly greater abduction than applying the same forces at 40, 50, 60 and 70°. Angles of 0–30° correspond with the direction of pull exerted by the lateral compartment of the CAD muscle. Conclusion: In RLN, nerve‐muscle pedicle grafts should be placed preferentially in the lateral rather than in the medial compartment of the CAD muscle. Potential relevance: The information presented can be used to assist surgeons in the planning and application of the nerve‐muscle pedicle graft procedure.