Expression of TOLL-like receptors (TLR) by bovine antigen-presenting cells-potential role in pathogen discrimination?

Invading pathogens are controlled by the innate and adaptive arms of the immune system. Adaptive immunity, mediated by B and T lymphocytes, recognises pathogens via high affinity receptors. However, the establishment of a primary adaptive immune response is not rapid enough to eradicate invading microorganisms as it involves cell proliferation, gene activation and protein synthesis. More rapid defence mechanisms are provided by innate immunity, which recognises invading pathogens by germ-line-encoded pattern recognition receptors. Recent evidence shows that this recognition can mainly be attributed to the family of TOLL-like receptors (TLR). Binding of pathogen-associated molecular patterns to TLR induces the production of reactive oxygen and nitrogen intermediates, pro-inflammatory cytokines, and up-regulates expression of co-stimulatory molecules, subsequently initiating the adaptive immunity. In this paper, we will discuss the current knowledge with regards to the TLR, and in particular the bovine family of TLR. In addition, we will show the expression of TLR mRNA in bovine antigen-presenting cell subsets, summarise the discovery and the critical roles of TLR2 in host defence against Mycobacteria, and provide evidence for a mycobacteria species-specific response of bovine macrophages.     

Forage and breed effects on behavior and temperament of pregnant beef heifers

Background

Integration of behavioral observations with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems. Brahman-influenced (BR; n = 64) and Gelbvieh × Angus (GA; n = 64) heifers consumed either toxic endophyte-infected tall fescue (E+) or one of two nontoxic endophyte-infected tall fescue (NT) cultivars during two yr. Heifers were weighed at midpoint and termination of grazing. Grazing behavior (grazing, resting in the shade, lying, or standing without grazing) was recorded (n = 13 visual observations per yr in June and July) for each pasture. During yr 2, exit velocity (EV) and serum prolactin (PRL) were determined.

Results

Grazing behavior was influenced (P < 0.05) by an interaction between fescue cultivar and breed type. Gelbvieh × Angus heifers assigned to E+ pastures had the lowest percentage of animals grazing and the largest percentage of animals resting in the shade. Brahman-influenced heifers had faster EV (P < 0.001) than GA heifers (0.52 vs. 0.74 ± 0.04 s/m, respectively). Body weight (BW) was affected (P < 0.01) by an interaction of tall fescue cultivar and d, and an interaction of tall fescue cultivar and breed type. Heifers grazing NT pastures were heavier (P < 0.01) than heifers grazing E+ pastures at midpoint and termination. Gelbvieh × Angus heifers grazing NT pastures were heavier (P < 0.01) than GA and BR heifers grazing E+ and BR heifers grazing NT pastures. An interaction of forage cultivar and breed type occurred on serum PRL (P < 0.01).

Conclusion

Collectively fescue cultivar, EV, and concentrations of serum PRL were associated with grazing behavior. Heifers grazing NT pastures were observed to be grazing more than heifers assigned to E+ pastures, regardless of breed type, which may have contributed to changes in BW and average daily gain (ADG) in heifers. Integration of behavioral observations along with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems.     

Pattern recognition receptors in companion and farm animals - the key to unlocking the door to animal disease?

The innate immune system is essential for host defence and is responsible for early detection of potentially pathogenic microorganisms. Upon recognition of microbes by innate immune cells, such as macrophages and dendritic cells, diverse signalling pathways are activated that combine to define inflammatory responses that direct sterilisation of the threat and/or orchestrate development of the adaptive immune response. Innate immune signalling must be carefully controlled and regulation comes in part from interactions between activating and inhibiting signalling receptors. In recent years, an increasing number of pattern recognition receptors (PRRs), including C-type lectin receptors and Toll-like receptors (TLRs), has been described that participate in innate recognition of microbes, especially through the so called pathogen-associated molecular patterns (PAMPs). Recent studies demonstrate strong interactions between signalling through these receptors. Whereas useful models to study these receptors in great detail in the murine and human system are now emerging, relatively little is known regarding these receptors in companion and farm animals. In this review, current knowledge regarding these receptors in species of veterinary relevance is summarised.     

Microculture of western white pine (Pinus monticola) by induction of shoots on bud explants from 1- to 7-year-old trees

We developed a protocol for the production of shoots from bud explants from 1- to 7-year-old trees of western white pine (Pinus monticola Dougl.). The best explant was a 2-mm-thick cross-sectional slice of the early winter bud. Genotype of the donor tree was a significant factor affecting shoot production, but more than 80% of the genotypes tested produced shoots. Of the media tested, bud slices from 1- to 3-year-old trees grew best in Litvay's medium containing N(6)-benzyladenine in the range of 1 to 30 micro M, whereas bud slices from older trees grew best in Gupta and Durzan's DCR medium with zeatin riboside. Up to 400 shoots more than 3 mm in height were obtained from 100 bud-slice explants taken from 7-year-old western white pine trees.     

The effect of human growth hormone-releasing factor or porcine somatotropin on serum hormones and metabolites, growth performance and carcass traits in swine

Forty barrows (77.9 +/- 5.5 kg BW) were allotted to one of five treatment groups to examine the effects of various doses of human growth hormone-releasing factor (1-44)NH2 (hGRF) or porcine somatotropin (pST) administered twice daily on serum hormones and metabolites, performance and carcass traits. Barrows were injected s.c. with either a placebo, 10 micrograms hGRF.kg BW-1.12 h-1, 20 micrograms hGRF.kg BW-1.12 h-1, 20 micrograms pST.kg BW-1.12 h-1 or 40 micrograms pST.kg BW-1.12 h-1 for a 36-d growth trial. Blood samples were collected from 13 barrows at intervals for 360 min after injection on d 21. Compared with the placebo, 10 micrograms hGRF.kg-1.12 h-1 increased (P less than .01) serum pST and insulin and decreased (P less than .001) urea N. Injecting 20 micrograms hGRF/kg.12 h-1 elevated (P less than .001) serum pST, insulin and insulin-like growth factor-I (IGF-I) but lowered (P less than .001) urea N. Exogenous pST increased (P less than .001) serum pST, insulin, IGF-I and glucose but decreased (P less than .001) urea N. Growth rate tended to increase, and feed intake and feed/gain decreased, in a dose-related manner in response to hGRF. Also, pigs receiving 10 or 20 micrograms hGRF.kg-1.12 h-1 had reduced (P less than .1) backfat and increased (P less than .1) loineye area and percentage lean in the ham compared with pigs receiving the placebo. At equal doses, pST elicited more dramatic improvements in performance and carcass criteria than did hGRF.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of metam sodium on the dissipation and residual biological activity of the herbicides EPTC and pebulate in surface soil under black plastic mulch

Metam sodium is a potential replacement for methyl bromide, which is used to control soil pests. Metam sodium rapidly breaks down in the soil to form methylisothiocyanate (MITC). Dissipation of the herbicides EPTC and pebulate in a silt loam soil under plastic mulch in the absence and presence of metam sodium was examined in field experiments in 1998 and 1999 at Knoxville, Tennessee. EPTC half-life (DT(50)) was 9 d, but when applied in conjunction with metam sodium DT(50) increased to 22 d. Similarly, average pebulate DT(50) was 8 d and increased to 23 d when applied in conjunction with metam sodium. This increase in herbicide DT(50) with the addition of metam sodium is thought to be due to a reduction in soil microorganisms that degrade EPTC and pebulate. EPTC applied with metam sodium injured tomato plants and reduced total crop yield more than EPTC, pebulate, or pebulate with metam sodium. The increased tomato injury may have been related to the greater and prolonged activity of EPTC and slower EPTC dissipation in the presence of metam sodium or MITC.     

Microclimate modifications,growth and yield of intercrops under Hardwickia binata Roxb. based agroforestry system

An experiment was conducted by planting Hardwickia binata Roxb. at 200, 400 and 800 trees ha^???1, intercrops viz., Brassica campestris (mustard) and Glycine max (soybean) were sown from the second year onwards in winter and summer respectively at the National Research Centre for Agroforestry, Jhansi, U.P., India with the objectives of evaluating agrosilvicultural potential of the system and to study the effect of tree densities on ecophysiology of understorey crops. Tree growth was affected by both density and intercrop in the initial years of growth. Photosynthetic photon flux density (PPFD) available to the intercrops reduced with increasing densities. Transpiration rate and stomatal conductance in intercrops decreased due to the presence of trees. No significant changes in leaf temperature were observed till the fifth year of the growing season. Yield was significantly higher in pure crop in comparison with all the densities in mustard. Soybean yield under 200 trees ha^???1 was comparable to that of the pure crop. Trees at the density of 200 trees ha^???1 provided a conducive microenvironment to the intercrops.     

Patterns of stem water potential in field grown potatoes using stem psychrometers

Summary The first large scale outdoor measurements of potato (Solanum tuberosum L.) stem water potential (SWP) usingin situ temperature-corrected stem psychrometers were performed on three cultivars common to Ontario, Canada (Atlantic, Monona and Norchip). Potato plants were examined under three soil water treatments which included rainfed, irrigated and stressed through the use of rain shelters. Cultivar variations in SWP under both irrigated and rainfed conditions were slight (P>0.05), although some significant (P<0.05) differences in mid-day SWP were evident, especially under conditions conducive to high atmospheric water demand. Under these conditions. cv. Atlantic maintained the lowest SWP with cv. Monona highest and cv. Norchip was intermediate. Few differences in pre-dawn SWP were detected between the three cultivars under well watered and rainfed conditions. Under low soil water, significant differences (P<0.05) were observed. The similar trend of Atlantic maintaining the lowest SWP with Monona the highest was consistent.     

Factors and Correlates of Employment Growth in the Canadian Urban System, 1971–1991

The objective of this paper is to examine a number of hypotheses concerning the factors or correlates of employment growth in the Canadian urban system—a set of 152 urban areas having populations of more than ten thousand inhabitants which comprises 77.4 percent of the national population. Do observed patterns of sectoral employment growth obey some sort of underlying logic? More specifically, do the rates of employment growth that are found in individual urban areas vary significantly according to one or more of the following attributes of an urban area: a) the region in which it is located; b) its population size; c) its relative proximity to a major metropolitan area; d) its socioeconomic characteristics? While approaches involving a, e and f yield promising results, it is clear that there are few immutable laws that permit one to predict where employment growth will occur within the urban system. Perhaps the most fundamental characteristic of the analyses conducted involves the instability of the results from one decade to another; one decade’s category of winners is often the other decade’s category of losers.