Innate immunity in Caenorhabditis elegans is regulated by neurons expressing NPR-1/GPCR

A large body of evidence indicates that metazoan innate immunity is regulated by the nervous system, but the mechanisms involved in the process and the biological importance of such control remain unclear. We show that a neural circuit involving npr-1, which encodes a G protein-coupled receptor (GPCR) related to mammalian neuropeptide Y receptors, functions to suppress innate immune responses. The immune inhibitory function requires a guanosine 3',5'-monophosphate-gated ion channel encoded by tax-2 and tax-4 as well as the soluble guanylate cyclase GCY-35. Furthermore, we show that npr-1- and gcy-35-expressing sensory neurons actively suppress immune responses of nonneuronal tissues. A full-genome microarray analysis on animals with altered neural function due to mutation in npr-1 shows an enrichment in genes that are markers of innate immune responses, including those regulated by a conserved PMK-1/p38 mitogen-activated protein kinase signaling pathway. These results present evidence that neurons directly control innate immunity in C. elegans, suggesting that GPCRs may participate in neural circuits that receive inputs from either pathogens or infected sites and integrate them to coordinate appropriate immune responses.     

糖甜菜定域育种初步研究

试验结果表明，甜菜单粒种采种母根主、侧花枝种子的块根产量、含糖率不同。单粒种根头周边芽所形成的花枝种子比根头中央部芽的花枝种子所产生的块根含糖率高0．79-2．45度，表现趋势较一致；但主、侧花枝种子的块根产量高低表现趋势不一致。为提高含糖率，此方法可在甜菜单粒型品系育种中应用。     

Efficiencies of ryegrass and white clover herbage utilization in mixtures continuously grazed by sheep

A method for measuring the growth, senescence and defoliation fluxes in a mixture consisting of alternate rows of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) was used to calculate the actual and potential efficiencies of grass and clover utilization under continuous sheep grazing. White clover contributed relatively more to the growth than to the herbage mass of the mixture and its relative growth rate was usually significantly greater than that of its companion grass. The primary reason for the greater potential efficiency of herbage use of the white clover component was, however, its lower rate of senescence. Greater potential efficiency was not reflected in a greater actual efficiency because the contribution of white clover to the total herbage removed was always smaller than its contribution to the growth flux of the mixture. Despite the commonly assumed sheep preference for white clover, the legume was usually the least defoliated species, presumably because of the lower surface height of white clover compared with grass, which resulted in a lower vertical availability of white clover, thereby restricting its defoliation rate. The positive net herbage accumulation observed with white clover at a constant sward surface height occurred partly through stolon and bud development and partly through the growth of undefoliated leaves from axillary growing points and contributed to a net herbage accumulation per unit dry weight in white clover greater than that in ryegrass. This resulted in an increase in the white clover content of the sward, which was observed independently by destructive measurements.     

Evidence from the use of isozyme markers of competition in swards between short-leaved and long-leaved perennial ryegrass

Intraspecific competition in Lolium perenne was studied using a replacement series of a short-leaved and a long-leaved genotype that was managed under different cutting frequencies and nitrogen supplies. Leaf length, tiller density and yield were recorded 6 months after sowing. Since the two competitors were labelled at the PG1/2 locus, it was possible to identify unambiguously the origin of tillers in the mixtures and to estimate the average length of lamina of each genotype. The difference in leaf length between the two competitors was maintained under particular types of management and generated contrasting competitive abilities leading to evolution of the genotypic composition of the mixtures. Thus, under infrequent cutting, competition for light resulted in the domination of the long-leaved genotype and in a concomitant intragenotypic selection for leaf length. Supplying nitrogen fertilizer emphasized the phenotypic plasticity of the genotypes, particularly of the dominated one. Frequent cutting reduced competition for light and the change towards the short-leaved genotype was far less rapid. The yielding and competitive abilities of ryegrass genotypes and the implications for breeding are briefly discussed.     

A survey of beef cattle farmers in New Zealand,examining management practices of primiparous breeding heifers

AIM: To obtain an estimate of the incidence of assistance at calving in primiparous (first-calving) beef heifers and the prevalence of breeding heifers at 15 months of age in New Zealand in 2006,and to identify factors contributing to farmers' decisions regarding breeding strategies for heifers, using a survey of beef cattle farmers.

METHODS: A questionnaire was sent to farmers listed in a Massey University database and to members of selected breed societies, as well as published in an industry newspaper; 331 valid responses were received. Information was gathered on the age and number of primiparous heifers, number of heifers assisted, and the importance of various reasons for and against breeding heifers at 15 months of age. Respondents were also required to outline the criteria used for selecting bulls to join with heifers, and the strategies used to manage dystocia in primiparous heifers.

RESULTS: Sixty-five (95% CI=58–71)% of respondents had only 2-year-old primiparous heifers in 2006, whilst a further 11 (95% CI=8–16)% had both 2- and 3-year-old primiparous heifers. The mean reported incidence of assisted calving was 7.0 (95% CI=6.4–7.5)% for 2-year-old primiparous heifers and 1.7 (95% CI=1.2–2.2)% for 3-year-old primiparous heifers. The reported incidence of assistance at calving within individual herdsranged from 0 to 100% for 2-year-old heifers. Respondents with bull-breeding herds most commonly observed their primiparous 2-year-old heifers twice daily, whilst respondents with commercial herds most commonly observed them once daily during calving. The most important reason for breeding heifers at 15 months of age was “increased profit”, whereas the most important reason for not breeding them at that age was “concern about rebreeding performance of 2-year-old heifers”. Estimated breeding value (EBV) for birth weight was the factor considered most frequently when selecting bulls to join with maiden heifers; age of bull and body shape of bull were the next most frequently considered factors. Selection of an appropriate bull was the most common strategy used to manage dystocia in 2-year-old beef heifers.

CONCLUSIONS: The majority of respondents calved their heifers at 2 years of age, and “increased profit” was the primary motivator. Concern about the rebreeding performance of 2-year-old heifers was the most important reason among the remainder of respondents for not breeding heifers at 15 months of age. Dystocia in 2-year-old heifers was “not a problem” or “a minorproblem” in most herds, but there was much variation amongst herds.     

The effect of Johne's vaccination on tuberculin testing in farmed red deer (Cervus elaphus)

AIM: To assess the degree of interference with bovine tuberculin testing in farmed red deer that vaccination of young deer with an oil-adjuvanted vs aqueous formulation of live attenuated Mycobacterium paratuberculosis Strain 316F vaccines would be likely to cause, and to compare immunological responses between vaccine formulations.

METHODS: Five-month-old red deer (n=45) were randomly allocated to three treatment groups of 15 animals, which received either no vaccine, a single 2-ml dose of an oil-adjuvanted formulation or two 2-ml doses, 6 weeks apart, of an aqueous formulation of live attenuated M. paratuberculosis Strain 316F vaccine injected subcutaneously (S/C) in the neck (Control, Oil-adjuvant Ptb, and Aqueous Ptb groups, respectively). Injection-site reactions were described and measured on Weeks 3, 6 and 9. Animals were weighed and lymphocyte transformation tests (LTT) and antibody enzyme-linked immunosorbent assays (ELISA) using avian, bovine and Johnin tuberculin were conducted on blood samples collected at Weeks 0, 6, 12, 15, 24, 27, 36 and 39. A bovine mid-cervical skin test (MCT) was applied at Week 12, and comparative cervical skin tests (CCTs) at Weeks 24 and 36. At Week 42, the animals were slaughtered at a commercial deer slaughter premises and subjected to rigorous meat inspection.

RESULTS: Two animals were eliminated at the start of the trial due to a positive cross-reaction with bovine tuberculin in the initial LTT. Almost all animals reacted to the MCT at Week 12, with mean skin thicknesses of 3.9, 2.9 and 1.0 mm for the Oil- adjuvant Ptb, Aqueous Ptb and Control groups, respectively. When the CCT was conducted at Week 24, 2/15 Oil-adjuvant Ptb, 2/14 Aqueous Ptb and 1/14 Control animals were classified as CCT-positive to bovine tuberculin. By Week 36, all animals were CCT-negative. The Oil-adjuvant Ptb vaccination resulted in high persistent levels of antibody that reacted with bovine tuberculin, compared with negligible levels in the Aqueous Ptb group.

Overall, a single dose of the Oil-adjuvant Ptb vaccine in deer stimulated a vigorous, cross-reactive immune response, evidenced by high LTT, skin-test and antibody reactions to bovine tuberculin, with both cell-mediated and humoral characteristics. By comparison, two doses of the Aqueous Ptb vaccine produced less cross-reactivity and a bias towards a cell-mediated response. The Oil-adjuvant Ptb vaccine resulted in moderate injection- site lesions that were quite persistent, whereas the Aqueous Ptb vaccine resulted in smaller nodules that regressed more quickly.

CONCLUSIONS: Vaccination of farmed deer with an oil-adjuvanted Johne's vaccine has the potential to cause significant interference with routine tuberculin skin testing. The cross-reactivity should decline with time and the CCT should be able to clear MCT-positives, but there is a risk of false-positives to the blood test for tuberculosis (BTB), due to high persistent levels of antibody. The CCT could be used as a primary skin test in vaccinated deer on some farms.

The Aqueous Ptb caused fewer problems with skin testing and produced significantly less bovine antibody than the Oil-adjuvant Ptb, but stimulated persistent cell-mediated immune responses that may provide some protection against Johne's disease.     

Has the introduction of modern rice varieties changed rice genetic diversity in a high-altitude region of Nepal?

We surveyed the uptake of three modern rice varieties by farmers in high-altitude villages in the Kaski district of Nepal and found that their uptake had displaced some traditional landraces in the district. The three varieties, Machhapuchhre-3 (M-3), Machhapuchhre-9 (M-9) and Lumle 2, were developed using client-oriented, participatory plant breeding methods and the first was introduced to farmers in 1996. By 2004 up to 60% of the land area was used to grow these modern varieties. Molecular markers (SSR) were used to assay levels of genetic diversity to test if adoption of modern varieties in the place of landraces had changed genetic diversity. The modern varieties were found to contain diverse alleles with a high proportion from the local parent variety, Chhomrong Dhan. We found a high level of allelic richness in the landraces, and although seven had been dropped in favour of the modern varieties, other diverse landraces were still being cultivated by farmers in the study villages on up to 40% of the rice area. Genetic diversity may be maintained even when landraces are displaced by modern varieties. Using a model we found that the partial replacement of landraces increased genetic diversity if the modern varieties were adopted on up to 65% of the area. Only above these levels did overall diversity decline.     

Survival of scrapie agent after exposure to sodium dodecyl sulphate and heat.

Fifty mg aliquots of macerated mouse-brain infected with the 22A strain of scrapie agent were treated by exposing them without mechanical mixing to (a) distilled water for 2 h, (b) 5% sodium dodecyl sulphate (SDS) for 2 h, (c) autoclaving at 121 degrees C for 15 min in distilled water, (d) autoclaving at 121 degrees C for 15 min in 5% SDS, or (e) boiling in 5% SDS for 15 min. Prior to injection into mice, all samples were washed by a procedure that is described and was shown not to reduce infectivity titres. Although the infectivity titre of the sample that was autoclaved in SDS was reduced considerably, infectivity was present in all of the samples exposed to cold or hot SDS.