Biological hurdles to the control of TB in cattle: A test of two hypotheses concerning wildlife to explain the failure of control

Since the 1970s the control of bovine tuberculosis (bTB) in cattle, predominantly in the SW of England has proved continually recalcitrant; it is currently increasing at an annual rate of 18%. This deterioration has occurred despite a succession of government schemes involving killing badgers, Meles meles, with the intention of reducing transmission of bTB to cattle. Of various hypotheses proposed to explain this failure of control, some concern agricultural practice, but two concern wildlife. The latter are, first, that wild mammalian species other than badgers are important in the transmission of bTB, and second, that a perturbation effect amongst those badgers surviving a cull countermands the hoped-for reduction of bTB transmission to cattle or even increases it. We review our own studies of these two hypotheses in the context of other findings. We conclude that the other species hypothesis does not provide a general explanation for the failure of bTB control. We also conclude that the perturbation hypothesis is supported by the data and does provide one plausible mechanism to explain why culling badgers has not generally achieved control of bTB in cattle. We have reviewed the relevance of perturbation with respect to three key questions:

(a)

is there evidence of a perturbation effect on badger behavioural ecology?

(b)

is there evidence of a perturbation effect on prevalence of bTB in badgers?

(c)

are any observed effects of a magnitude relevant to bTB control policy?

The results of the Randomised Badger Culling Trial (RBCT) and our own studies indicate that to have any prospect of contributing significantly to controlling bTB in cattle, a badger cull would have to be undertaken over a very large area. Considering the likely very important role of cattle-to-cattle transmission, and the opportunities for solutions in terms of farm management and surveillance, it would be inappropriate (and probably impractical) to undertake such a cull now.     

Lower fumonisin mycotoxin levels in the grain of Bt corn grown in the United States in 2000-2002

Fumonisins were monitored in corn grain collected from Bt hybrids grown in 107 locations across the United States in 2000-2002. Bt corn hybrids contain the Cry1Ab protein from Bacillus thuringiensis that controls European corn borers and other stalk-boring pests. Fumonisin levels were frequently lower in grain from Bt hybrids grown in field trials under conditions of natural (FACT trials) or manual insect infestation (university trials). Over three years of FACT trials, there were 126/210 comparisons when fumonisin levels in grain from control hybrids were >2 ppm, exceeding U.S. FDA guidance levels of 2 ppm for human food. Grain from Bt hybrids was at or below 2 ppm of fumonisins for 58 of the 126 comparisons. The use of Bt hybrids can increase the percentage of corn grain that would be suitable for use in food and feed.     

The composition of grain and forage from glyphosate tolerant wheat MON 71800 is equivalent to that of conventional wheat (Triticum aestivum L.)

Glyphosate tolerant wheat MON 71800, simply referred to as MON 71800, contains a 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) protein from Agrobacterium sp. strain CP4 (CP4 EPSPS) that has a reduced affinity for glyphosate as compared to the endogenous plant EPSPS enzyme. The purpose of this work was to evaluate the compositional equivalence of MON 71800 to its nontransgenic parent as well as to conventional wheat varieties. The compositional assessment evaluated the levels of proximates, amino acids, fatty acids, minerals, vitamins, secondary metabolites, and antinutrients in wheat forage and grain grown during two field seasons across a total of eight sites in the United States and Canada. These data demonstrated that with respect to these important nutritional components, the forage and grain from MON 71800 were equivalent to those of its nontransgenic parent and commercial wheat varieties. These data, together with the previously established safety of the CP4 EPSPS protein, support the conclusion that glyphosate tolerant wheat MON 71800 is as safe and nutritious as commercial wheat varieties.     

Single-chain antigen-binding proteins

Single-chain antigen-binding proteins are novel recombinant polypeptides, composed of an antibody variable light-chain amino acid sequence (VL) tethered to a variable heavy-chain sequence (VH) by a designed peptide that links the carboxyl terminus of the VL sequence to the amino terminus of the VH sequence. These proteins have the same specificities and affinities for their antigens as the monoclonal antibodies whose VL and VH sequences were used to construct the recombinant genes that were expressed in Escherichia coli. Three of these proteins, one derived from the sequence for a monoclonal antibody to growth hormone and two derived from the sequences of two different monoclonal antibodies to fluorescein, were designed, constructed, synthesized, purified, and assayed. These proteins are expected to have significant advantages over monoclonal antibodies in a number of applications.     

Assignment of the gene for myelin proteolipid protein to the X chromosome: implications for X-linked myelin disorders

Several inherited disorders in humans and in rodents result in myelin dysgenesis and a deficiency of the molecular constituents of myelin. A complementary DNA to one of the two major myelin proteins, myelin proteolipid protein (also known as lipophilin), has been used with Southern blot analysis of somatic cell hybrid DNA to map the human proteolipid protein gene to the middle of the long arm of the human X chromosome (bands Xq13-Xq22) and to assign the murine proteolipid protein gene to the mouse X chromosome. Comparison of the gene maps of the human and mouse X chromosomes suggests that myelin proteolipid protein may be involved in X-linked mutations at the mouse jimpy locus and has implications for Pelizaeus-Merzbacher disease, a human inherited X-linked myelin disorder.     

Quantum dot/polyvinyl alcohol composite nanofibers membrane as highly sensitive fluorescence quenching-based sensors

Nanofibrous membranes are intensively applied to fabricate advanced intelligent devices like highly sensitive sensors due to their flexibility, high porosity, high surface area and good mechanical and chemical stability. In this work, fluorescent cadmium telluride (CdTe) quantum dots (Q.Ds) were synthesized and then uniformly embedded in poly vinyl alcohol (PVA) nanofibers by electrospinning technique to serve as reversible quenching fluorescence-based sensor to detect the traces of benzene, toluene and xylene vapors selectively at room temperature. Fluorescence analysis suggested that Q.Ds preserve their original fluorescent property in solid nanofiber as if they were in solution. Scanning electron microscopy images showed the uniform diameter of nanofibers. In addition, Fluorescence and transmission electron microscopy (TEM) measurements confirmed the uniform distribution of the Q.Ds into nanofibers structures. The main mechanism of quenching based sensor was designated as electron transfer from thiogalycolic acid (TGA) — capped Q.D surface to target volatile organic compounds (VOC’s) vapors. Fabricated sensor showed selectively sensing upon trace of different target vapors due to the difference in the electronegativity of various VOC’s molecules. For example exposure to more electron withdrawing toluene molecules induces severe quenching effect on fluorescence intensity of Q.D (about 25 %) over xylene exposure. Moreover, it was observed that reducing the diameter of nanofibers enhanced the sensitivity of sensor.     

Fabrication and characterization study of electrospun quantum dot — poly vinyl alcohol composite nanofiber for novel engineering applications

CdTe quantum dot/PVA (poly vinyl alcohol) composite nanofiber was successfully fabricated by eletrospinning process. CdTe quantum dots were uniformly dispersed and stabilized into solid nanofiber structure. Spectrofluorometer analysis revealed whenever Q.D??s enter to the PVA solution, due to the aggregation of Q.D??s red shift happens; however, when blend Q.D-PVA solution changes to nanofiber form via electrospining, this shift phenomenon offsets and original fluorescence properties of Q.D??s does not degraded due to excellent individual dispersion of Q.D in the nanofibers structure. It is also turned out that the proportion of Q.D??s incorporated in the composite solution of electrospining has strong influence on the nanofiber morphology. Addition of Q.D??s to PVA solution causes remarkable changes in the conductivity and solution viscosity, therefore different nanofiber morphologies can be obtained as evidenced by scanning electron microscopy. Furthermore, differential scanning calorimetric (DSC) revealed addition of small amount of Q.D??s to the electrospining solution causes strenuous improvement in crystalinity and heat of nanofiber fusion. Fluorescence and transmission electron microscopy (TEM) measurements confirmed the evenly dispersion of the Q.D??s into nanofibers structures.     

Human-Wildlife Conflict Pattern and Suggested Mitigation Strategy in the Pamirs of Northwestern China

Predation of livestock by wildlife and the retribution responses it elicits can have strong negative impacts on both people and carnivores. A questionnaire survey designed to investigate human-carnivore conflicts was completed by 66 herders from local communities within Taxkorgan Nature Reserve, located in the Pamir and Karkorum mountains of Northwestern China. A total of 127 livestock predation events with associated predator identification were reported and 583 livestock were killed. Wolves (315 livestock) and dholes (129 livestock) were responsible for the largest number of livestock losses. Livestock depredation significantly differed between guarded and unguarded management strategies. Positive relationships between loss and the total amount of the major livestock species, as well as the total loss and total amount of livestock, were detected. Use of guard dogs did not affect the likelihood of carnivore attacks, whereas keeping livestock in pens at night or all day did reduce the number of depredation events. Depredation showed significant seasonal variation (month of occurrence) for large carnivores. Numbers of goat, sheep, and cattle predated also varied by month, but did not for yak because of different husbandry practices. No compensation policy has yet been established in this area, but if it were to be developed in the future, 83% of interviewed herders would require compensation in cash, whereas 14% of herders would prefer replacement livestock. Our study offers suggestions to mitigate livestock depredation in this region of China. To prevent livestock depredations, local herders should mainly prevent wolves and dholes because they cause most livestock killings, and employ guarded grazing practice. Managers could make herders keep a reasonable number of livestock to raise grazing efficiency, introduce suitable sheepdog breeds, and provide essential dog training as useful aids to herders to increase livestock-guarding effectiveness.     

灌溉及株距间的交互作用对甘蔗产量、蔗糖含量的影响(英文)

为研究孟加拉干旱区灌溉方式、株距及其交互作用对甘蔗分蘖数量、可榨甘蔗数量、甘蔗产量以及蔗糖含量的影响 ,在孟加拉第 11农业生态区的洪积平原上进行了为期 3年的栽培试验 .试验株距分别为 30 ,4 5,6 0和 75cm ,试验灌溉方式为天然降雨配合点灌和漫灌 .试验区按裂区试验法进行布置 ,灌溉方式则按小区布设 ,株距试验布置在主试验区 .试验结果表明 ,灌溉方式、栽植株距以及它们之间的交互作用对甘蔗产量、含糖量有显著影响 .就株距而言 ,4 5cm的株距可以获得最高的甘蔗产量(75 81t·hm- 2 ) .同样 ,在雨养、点灌及漫灌三种灌溉方式中 ,漫灌的甘蔗产量最高 (91 2 7t·hm- 2 ) .最好的栽培技术组合为 4 5cm株距配合漫灌 ,甘蔗分蘖数、可榨甘蔗数、甘蔗产量、产糖量以及投入产出比分别高达 2 0 3× 10 3株·hm- 2 ,115 53× 10 3株·hm- 2 ,10 1 6 4t·hm- 2 ,8 45t·hm- 2 和 5 52∶1