Molecular characteristics of an immobilization antigen gene of the fish-parasitic protozoan Ichthyophthirius multifiliis strain ARS-6

Ichthyophthirius multifiliis (Ich), a ciliated protozoan parasite of fish, expresses surface antigens (i-antigens), which react with host antibodies that render them immobile. The nucleotide sequence of an i-antigen gene of I. multifiliis strain ARS-6 was deduced. The predicted protein of 47 493 Da is comprised of 460 amino acids (aa's) arranged into five imperfect repeats with periodic cysteine residues with the structure: CX₍₁₉₎₂₀CX₂CX₁₆₋₂₇CX₂CX₂₀₍₂₁₎CX₃. The N-terminal aa's typify a signal peptide motif while a stretch of C-terminal aa's resemble a glycosyl–phosphatidyl–inositol (GPI)-anchor addition site. The degree of deduced i-antigen aa sequence identity of strain ARS-6 (GenBank accession # ACH87654 and # ACH95659) with other I. multifiliis i-antigen sequences present in GenBank ranges from 99% to 36% identity with 52 kDa i-antigens of I. multifiliis strain G5 (accession #s AAK94941 and AAK01661 respectively). Immunoblot analysis of i-antigens following exposure of I. multifiliis theronts to catfish anti- I. multifiliis immune serum did not show any appreciable alteration in i-antigen expression. The mechanism that regulates i-antigen expression in I. multifiliis remains a puzzling question.     

Heparan sulfate is a selective attachment factor for the avian coronavirus infectious bronchitis virus Beaudette

The avian coronavirus infectious bronchitis virus (IBV) strain Beaudette is an embryo-adapted virus that has extended species tropism in cell culture. In order to understand the acquired tropism of the Beaudette strain, we compared the S protein sequences of several IBV strains. The Beaudette strain was found to contain a putative heparan sulfate (HS)-binding site, indicating that the Beaudette virus may use HS as a selective receptor. To ascertain the requirements of cell-surface HS for Beaudette infectivity, we assayed for infectivity in the presence of soluble heparin as a competitor and determined infectivity in mutant cell lines with no HS or glycosaminoglycan expression. Our results indicate that HS plays a role as an attachment factor for IBV, working in concert with other factors like sialic acid to mediate virus binding to cells, and may explain in part the extended tropism of IBV Beaudette.     

Effects of modified-live bovine viral diarrhea virus vaccines containing either type 1 or types 1 and 2 BVDV on heifers and their offspring after challenge with noncytopathic type 2 BVDV during gestation

OBJECTIVE: To compare the efficacy of modified-live virus (MLV) vaccines containing either type 1 bovine viral diarrhea virus (BVDV) or types 1 and 2 BVDV in protecting heifers and their offspring against infection associated with heterologous noncytopathic type 2 BVDV challenge during gestation. DESIGN: Randomized controlled study. ANIMALS: 160 heifers and their offspring. PROCEDURES: After inoculation with a placebo vaccine, 1 or 2 doses of an MLV vaccine containing type 1 BVDV, or 1 dose of an MLV vaccine containing both types 1 and 2 BVDV, heifers were bred naturally and challenge exposed with a type 2 BVDV field isolate between 62 and 104 days of gestation. Pregnancies were monitored; after parturition, virus isolation and immunohistochemical analyses of ear-notch specimens were used to determine whether calves were persistently infected. Blood samples were collected at intervals from heifers for serologic evaluation and virus isolation. RESULTS: Persistent infection was detected in 18 of 19 calves from heifers in the control group and in 6 of 18 calves and 7 of 19 calves from heifers that received 1 or 2 doses of the type 1 BVDV vaccine, respectively. None of the 18 calves from heifers that received the type 1-type 2 BVDV vaccine were persistently infected. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the incidence of persistent BVDV infection among offspring from dams inoculated with 1 dose of the MLV vaccine containing types 1 and 2 BVDV was decreased, compared with 1 or 2 doses of the MLV vaccine containing only type 1 BVDV.     

Ecology and epidemiology of anthrax in cattle and humans in Zambia

Anthrax is endemic in Western and North-western Provinces of Zambia. The disease occurs throughout the year and impacts negatively on the economy of the livestock industry and public health in Zambia. During 1989-1995, there were 1626 suspected cases of anthrax in cattle in Western province and of these 51 were confirmed. There were 220 cases of human anthrax cases in 1990 alone and 248 cases during 1991-1998 with 19.1% and 7.7% case fatality rates, respectively. Interplay of the ecology of affected areas and anthropogenic factors seem to trigger anthrax epidemics. Anthrax has drawn considerable attention in recent years due to its potential use as a biological weapon. In this paper, the history, current status and approaches towards the control of the disease in Zambia are discussed. Quarantine measures restrict trade of livestock and exchange of animals for draught power resulting in poor food security at household levels. Challenges of anthrax control are complex and comprise of socio-political, economical, environmental and cultural factors. Inadequate funding, lack of innovative disease control strategies and lack of cooperation from stakeholders are the major constraints to the control of the disease. It is hoped that the information provided here will stimulate continued awareness for the veterinary and medical authorities to maintain their surveillance and capabilities against the disease. This may lead to a culminating positive impact on livestock and human health in the southern African region.     

Monitoring Cry1Ab susceptibility in Asian corn borer (Lepidoptera: Crambidae) on Bt corn in the Philippines

Between 2002 and 2004, collections of egg masses of Asian corn borer (ACB), Ostrinia furnacalis (Guenée) were made from corn-planting sites on the major Philippine islands of Luzon (Laguna, Pangasinan, Camarines Sur and Isabela provinces) and Mindanao (Bukidnon and South Cotabato provinces). The resulting neonates were bioassayed for susceptibility to Bacillus thuringiensis (Bt) Cry1Ab protein. The median lethal concentrations (LC₅₀s) for the different collections ranged from 0.42 to 2.37 ng/cm². The bioassay results suggest that Philippine corn borer populations were highly susceptible to Cry1Ab protein prior to the widespread deployment of Bt corn. The upper limit of the estimated LC₉₉ (104 ng/cm²) from the pooled bioassay data was selected as a candidate diagnostic concentration and subsequently tested on eleven ACB populations. Results of the validation assays showed that the mortality response of all the tested ACB populations was higher than the expected mortality (99%). Therefore, the concentration of 104 ng/cm² was used to monitor susceptibility in ACB populations in the Philippines. Monitoring of field populations during 2009 in areas where Bt corn had been grown for 3 years found some enhanced survival of neonates at the diagnostic concentration but progeny of the diagnostic-concentration survivors did not survive on Bt corn, indicating that ACB populations in the Philippines remain susceptible to Cry1Ab-containing Bt corn hybrids.     

Cytoplasmic substitution inSolanum. II. Tuber characteristics of reciprocal backcross progeny

Summary Recurrent backcrosses (BC) were used to introduce nuclear factors ofS. tuberosum L. ssp.tuberosum into the cytoplasm of Andean potatoesS. tuberosum ssp.andigena (Juz. and Buk.) Hawkes andS. phureja Juz. and Buk. Each generation BC was produced in reciprocal directions to test the effect of cytoplasmic substitution on yield. This report analyses tuber number, tuber weight, and tuber length of BC₂ and BC₃ substitution into ssp.andigena cytoplasm and BC₂ and BC₂ substitutions intoS. phureja cytoplasm. Direction of cross had no consistent significant effect on yield components of ssp.andigena substitution lines. InS. phureja reciprocal progenies direction of cross was responsible for significant differences of some reciprocal sets. When there were significant differences the higher yield usually occurred when ssp.tuberosum was the pistillate parent, but in some progenies when ssp.tuberosum was the pistillate parent the yield was significantly lower than in the reciprocals. It is suggested that differences between reciprocals resulted from chromosomally encoded gene action, resulting from maternal and/or paternal effects, rather than cytoplasmic factors. Authorized for publication as paper No. 7494 in the Journal Series of The Pennsylvania Agriculture Experiment Station.     

Cytoplasmic substitution inSolanum. I. Seed production,germination, and sterilities of reciprocal backcross generations

Summary Genes ofSolanum tuberosum L. ssp.tuberosum were introduced into cytoplasm ofS. tuberosum ssp.andigena (Juz. & Buk.) Hawkes andS. phureja Juz. & Buk. to reduce cytoplasmic sterilities. Alleles that influenced berry set and seed content produced differences between reciprocal progenies. Their expressions were interpreted in terms of genes of the maternal and/or paternal parents. When the ssp.andigena genotype was introduced from the maternal parent if favoured high berry set and low seed number. Maternal ssp.tuberosum favoured lower berry set and higher seed number. The source ofS. phureja cytoplasm, aS. phureja×S. chacoense F₁, used as maternal parent favoured lower berry and seed set. During successive backcrosses progeny expressions approached those of the recurrent ssp.tuberosum pollen parents. A low level of pollen sterility occurred in BC₂ plants, unrelated to direction of cross or cytoplasmic factors. By BC₄, seed set and fertility were as good as ssp.tuberosum, and recurrent backcrossing could be terminated without loss of seed production or fertility. Pennsylvania Agricultural Experiment Station Journal Series No. 7493.     

Farmer‐led maize biochar trials: Effect on crop yield and soil nutrients under conservation farming

In extensive farmer‐led trials practicing conservation farming (CF) in three regions of Zambia (Mongu: sandy soils; Kaoma: sandy or loamy sand soils; Mkushi: sandy loam or loamy soils), we studied the effects of biochar made of maize cobs (0, 2, and 6 t ha^?1 corresponding to 0, 0.8, and 2.5% per basin) at different fertilizer rates of NPK and urea on crop yield of maize (Zea mays) and groundnuts (Arachis hypogaea). Conservation farming in this case combines minimum tillage (how basins), crop rotation and residue retention. For the first time, the effect of biochar on in situ soil nutrient supply rates [determined by buried Plant Root Simulator (PRS?) exchange resins] was studied, as well as the effects of biochar on elemental composition of maize. Effects of 0–10% (w:w) biochar addition on soil physical and soil chemical properties were determined in the laboratory. At all sites there was a consistent positive response in crop yield upon the addition of biochar. However, due to a great variability between farms there were no significant differences in absolute yields between the treatments. In the sandy soils at Mongu, relative yields (i.e., percentage yield with biochar relative to the same fertilizer rate without biochar) of maize grains and maize stover were significantly increased at recommended fertilizer rates (232 ± 60%) and at half the recommended rate (128 ± 6%), respectively. In addition, biochar significantly increased concentrations of K and P in maize stover. In situ soil nutrient supply rates as measured by PRS?‐probes were highly spatially variable with no consistent effects of the different treatments in the three regions. By contrast, the fraction of plant available water (Vol.‐%) significantly increased upon the addition of biochar in all three soils. The increase caused by 10% biochar addition was of factor 2.5 in Mongu (from 4.5% to 11.2%) and 1.2 in both Kaoma (from 14.7% to 18.2%) and Mkushi (from 18.2% to 22.7%). Cation exchange capacity, pH, and exchangeable K significantly increased upon the addition of 10% (w:w) biochar in all three regions with a subsequent increase in base saturation and decrease of available Al³⁺. Our findings suggest that the addition of biochar in combination with CF might have a positive impact on crop growth and that this positive effect is mainly caused by increases in plant‐available water and decreased available Al.