Validation of endogenous reference genes for expression profiling of RAW264.7 cells infected with Mycobacterium avium subsp. paratuberculosis by quantitative PCR

Reference genes are frequently used to normalize between different biological samples the levels of mRNA measured using quantitative PCR (qPCR). The expression level of many commonly used reference genes has been shown to vary between tissues or cells, or following exposure to various treatments including infection with microbes. The selection of an appropriate reference gene for an individual experiment is therefore a crucial step in the process of accurately determining changes in gene expression. For this purpose, we analyzed the expression of nine commonly used reference genes in a murine macrophage cell line, RAW264.7, for their potential use in the analysis of differential gene expression by quantitative polymerase chain reaction (qPCR) following experimental infection with Mycobacterium avium subsp. paratuberculosis. Only one of nine putative reference genes tested, casc3a, was found to be suitable, and combinations of two or more reference genes were disadvantageous. Based on data from the study, we recommend an approach for selection of reference genes, conducting assays with technical replicates in duplicate rather than triplicate, determining decision-limit quality control criteria for technical replicates and assessing the significance of gene expression fold differences using DeltaDeltaC(t) based on knowledge of the variation in the reference gene.     

浙江南部近海小黄鱼生长、死亡和单位补充量渔获量

浙江南部近海是东海种群小黄鱼(Larimichthys polyactis)的重要繁殖和育肥场所。根据2016年2月、5月、8月和11月采集的2023尾浙江南部近海小黄鱼全长、体长和体重等生物学信息,利用体长频率分布估算小黄鱼种群生长、死亡参数,并利用Beverton-Holt动态综合模型评估探讨单位补充量渔获量在不同自然死亡系数和渔具选择下随捕捞死亡系数的变化趋势。研究结果表明小黄鱼von Bertalanffy生长参数为渐近体长L_∞=22.58 cm,生长速率K=0.78/a,初始年龄t_a=-0.37 a;自然死亡系数M值为1.343,总死亡系数Z值为4.432,捕捞死亡系数F为3.089,开发率E为0.697,表明资源处于过度开发状态;小黄鱼的首次捕捞体长L_(50)=13.11cm,对应首次捕捞平均年龄t_c=0.743 a,小于临界年龄(0.886a)和体重生长的拐点年龄(0.979a),渔业主要捕捞对象为幼鱼和补充群体,无法保证资源的有效补充;根据B-H动态模型,当前的YPR值为15.279 g/ind,若降低捕捞强度到1.685,对应YPR_(max)为17.061 g/ind,与当前产量相比增幅11.66%;若提高开捕体长(13.11cm→16.0cm),YPR_(cur)会出现显著提高(15.279 g/ind→18.766 g/ind),增幅达22.82%,表明提高开捕体长要优于降低捕捞强度。当前东海小黄鱼群系处于小型低龄化和过度开发状态,建议将小黄鱼的开捕体长提高为15 cm,保证小黄鱼的产卵亲体量及资源的可持续发展。     

The sulfur components of Allium species as flavoring matter

Gas chromatographic analysis of the headspace volatiles from various kinds ofAllium (onions) revealed the principal disulfides present as being: di-n-propyl, n-propyl allyl, methyl-n-propyl, methyl allyl, dimethyl and diallyl. These aliphatic disulfides appear to be one of the principal groups of compounds responsible for the aroma and flavor of onions. A procedure for the qualitative and quantitative determination of these compounds is discussed. Comparisons are made between disulfide composition of various species and also between fresh and dehydrated onion samples. The amounts of volatile disulfides lost on dehydration are discussed.     

Prednisolone therapy for atopic dermatitis is less effective in dogs with lower pretreatment serum 25-hydroxyvitamin D concentrations

Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured in 20 dogs with atopic dermatitis prior to treatment with a standard therapeutic dosage of prednisolone (0.93-1.06 mg/kg) every other day for 5 weeks after 7 days of treatment with the same dosage once daily. The severity of their physical signs was scored before and 6 weeks after prednisolone treatment by the canine atopic dermatitis extent and severity index version 3 (CADESI-03) and the Edinburgh Pruritus Scale (EPS). The 20 dogs with atopic dermatitis that were treated with prednisolone did not have significantly lower serum concentrations of 25(OH)D than a group of 36 healthy dogs, and the physical severity of the atopic dermatitis was not correlated to pretreatment serum 25(OH)D concentrations. However, dogs which had a marked improvement of their physical signs, defined by a post-treatment EPS score of 0 and/or an 85% reduction in CADESI-03 score, had significantly higher pretreatment serum 25(OH)D concentrations than dogs with a suboptimal response (P = 0.003 and P = 0.03, respectively). Serum 25(OH)D concentrations were also measured in a previously published cohort of atopic dogs that were treated with ciclosporin. This cohort of dogs was recruited in a similar time frame to the prednisolone-treated dogs, and all samples were handled in the same way. In contrast to the prednisolone-treated dogs, there was no significant difference in 25(OH)D concentrations in dogs that responded optimally to ciclosporin compared with suboptimal responders. Additional studies are required to establish whether vitamin D has a synergistic therapeutic effect with prednisolone in dogs with atopic dermatitis.     

Designing resistance management programs: How can you choose?

A list of often-discussed resistance management tactics is critically reviewed. Alteration of insecticides across generations, non-persistent formulations, and the use of pesticides conferring only low magnitudes of resistance seem to be among the most promising tactics for general use in resistance management. Justifying the first two choices usually requires little more than data on product persistence in terms of toxic effect on susceptible individuals under field conditions. The last tactic requires additional information on resistance ratios for resistant and susceptible genotypes under field exposure. The efficacy of pesticide mixtures is highly dependent on equal persistence of both compounds used in the mixture. The number of genes involved in resistance and the fitness disadvantages they may confer in the absence of use appear to be of relatively little significance in choosing management tactics.     

Effects of microbial inhibitors on the degradation rates of metamitron,metazachlor and metribuzin in soil

Rates of carbon dioxide evolution and degradation rates of metamitron, metazachlor and metribuzin were measured in two soils in the presence of three microbial inhibitors. The nonselective microbial inhibitor sodium azide reduced both carbon dioxide evolution and the rate of loss of all three herbicides in both soils, although the reduction in degradation rate of metamitron was small. The antibacterial antibiotic novobiocin enhanced carbon dioxide evolution from both soils but had variable effects on the rates of herbicide degradation. It inhibited degradation of metazachlor and metribuzin, and in one of the soils its effects on metazachlor degradation were similar to those of sodium azide. Novobiocin inhibited degradation of metamitron to a small extent in one soil only. The antifungal antibiotic cycloheximide also enhanced carbon dioxide evolution from both soils. In general, its effects on herbicide degradation were similar to those of novobiocin, although the extent of inhibition was usually less pronounced. The results are discussed in terms of the relative involvement of microorganisms in degradation of the three herbicides.     

The physical and chemical properties of the herbicide cinmethylin (SD 95481)

Cinmethylin (SD 95481), is a novel herbicide developed for the selective pre-emergence control of many annual grass weeds in a wide range of temperate and tropical crops. Representing new herbicide chemistry, cinmethylin is in the cineole family. Cinmethylin is a mobile colourless liquid with a boiling point of 313°C under an inert atmosphere at atmospheric pressure. It has a density of 1015 kg m^?3 and a viscosity of 70–90 mPa s, both at 20°C. It is miscible in all proportions with most organic solvents but has a low solubility, 63 mg litre^?1, in water. It has a vapour pressure of 10.2 mPa (20°C) and the vapour pressure/temperature relationship is given by log_e P(Pa)=28.9–9816/T (K). The n-octanol/water partition coefficient is 6850 and soil organic matter/water sorption coefficient (K_om) ranges between 165 and 235 over the three types of soil used in these studies. Cinmethylin is stable in water over the pH range 3–11. Solutions of cinmethylin in water or solvents are reasonably stable to sunlight, though thin films on a quartz surface photooxidise mainly to an ester within 24 h. This rate can be reduced by the addition of photostabilisers or by sorption onto soil surfaces. In an inert atmosphere cinmethylin is stable to high temperatures, though, in air, oxidation occurs at temperatures above 100°C to give the same product as by photodecay.     

The pyrethrins and related compounds. Part XXVIII: Alkenyl- and alkynyl-substituted benzyl esters

Over 100 benzyl esters of pyrethroidal acids were synthesised and tested for insecticidal activity to establish detailed structure–activity relationships in compounds with side-chains similar to those in the natural pyrethrins. Alkenyl, and corresponding alkynyl, side-chains were effective, both at the 3- and 4-positions, as were side-chains with extended substitution in either E or Z forms. A cyano group at the α-position increases activity if the side-chain is at C-3, but lowers it drastically if the substituent is at C-4. Similarly, methyl groups at C-2 and/or C-6 may increase activity whether the unsaturated side-chain is at C-3 or C-4, but only in the absence of an α-cyano group.     

Llaves,voitures, and tope [keys (sp.), cars (fr.), and mud (Swahili)] — the real reasons behind success or failure of field crop protection projects

Crop protection research in the Tropics is always interesting and challenging, and usually professionally rewarding. Once involved, researchers often find it difficult to leave international research settings. However, the wise field scientist, when choosing such a career, will make Barley ’s (3) “The Innocent Anthropologist ” required reading and purchase a very good pair of binoculars and a local bird guide. Even the most resourceful individual is going to have a considerable amount of time to add birds to one ’s life list, improve species distribution maps, or possibly even identify a new species while waiting for the key to be found, the vehicle to show up, or the mud to dry out.