N loss to drain flow and N2O emissions from a corn-soybean rotation with winter rye.

Anthropogenic perturbation of the global nitrogen cycle and its effects on the environment such as hypoxia in coastal regions and increased N2O emissions is of increasing, multi-disciplinary, worldwide concern, and agricultural production is a major contributor. Only limited studies, however, have simultaneously investigated NO3- losses to subsurface drain flow and N2O emissions under corn-soybean production. We used the Root Zone Water Quality Model (RZWQM) to evaluate NO3- losses to drain flow and N2O emissions in a corn-soybean system with a winter rye cover crop (CC) in central Iowa over a nine year period. The observed and simulated average drain flow N concentration reductions from CC were 60% and 54% compared to the no cover crop system (NCC). Average annual April through October cumulative observed and simulated N2O emissions (2004-2010) were 6.7 and 6.0kgN2O-Nha-1yr-1 for NCC, and 6.2 and 7.2kgNha-1 for CC. In contrast to previous research, monthly N2O emissions were generally greatest when N loss to leaching were greatest, mostly because relatively high rainfall occurred during the months fertilizer was applied. N2O emission factors of 0.032 and 0.041 were estimated for NCC and CC using the tested model, which are similar to field results in the region. A local sensitivity analysis suggests that lower soil field capacity affects RZWQM simulations, which includes increased drain flow nitrate concentrations, increased N mineralization, and reduced soil water content. The results suggest that 1) RZWQM is a promising tool to estimate N2O emissions from subsurface drained corn-soybean rotations and to estimate the relative effects of a winter rye cover crop over a nine year period on nitrate loss to drain flow and 2) soil field capacity is an important parameter to model N mineralization and N loss to drain flow.

Structure-function studies of the functional and binding epitope of the human 37 kDa laminin receptor precursor protein.

Expression of the 37 kDa laminin receptor precursor protein (37LRP) correlates directly with increased invasiveness and the metastatic potential of tumors. The 37LRP matures to a 67 kDa protein which facilitates the binding of cancer cells to basement membranes. The palindrome peptide sequence LMWWML, corresponding to the 173-178-residue stretch of the human 37LRP sequence, has been identified as the laminin-1-binding site. Peptides from 37LRP of species that contain this palindrome-bind laminin-1 with high affinity. Nuclear magnetic resonance (NMR) conformational studies have been undertaken on a synthetic 15-residue peptide (KGAHSVGLMWWMLAR) containing the palindrome to establish the structural basis of this activity. To further correlate the structural data with laminin-1-binding function, analogous structural studies were conducted for a similar peptide (RGKHSIGLIWYLLAR) lacking the palindrome, originating from 37LRP sequence of Saccharomyces cerevisiae and exhibiting low laminin-1-binding affinity. Finally, in vitro cell invasion assays were performed to investigate the possibility that the laminin-1-binding affinity of the peptides influences their inhibitory activity.

Development and evaluation of an enzyme-linked immunosorbent assay for bovine antibody (IgG) to Pasteurella haemolytica.

The sensitivity of an indirect enzyme-linked immunosorbent assay (ELISA) for bovine IgG serum antibody to Pasteurella haemolytica was compared with that of an indirect hemagglutination (IHA) test. Pasteurella haemolytica serotypes were grown in a chemically defined cell culture medium, and soluble antigens released into the growth medium were used in the ELISA and IHA test. An ELISA with serotype-1 antigen consistently detected antibody in sera that were positive by IHA test (correlation, 99%). Sera reacting with serotype-1 ELISA antigens also reacted with ELISA antigens prepared from other serotypes. Although ELISA titers averaged 5 log2 units higher than IHA titers, plots of titers determined by the 2 methods were approximately linear. Titer increases detected in paired serum samples by either test were similar. The ELISA was more sensitive than was the IHA in detecting colostral IgG antibody in serum of newborn calves. The ELISA uses a simple, stable antigen preparation and detects antibody to P haemolytica serotypes that commonly infect cattle.

Development and evaluation of an enzyme-linked immunosorbent assay for bovine antibody to Pasteurella haemolytica: constructing an enzyme-linked immunosorbent assay titer.

A 2-stage strategy was developed and evaluated for estimating serum antibody titer by use of ELISA and a series of dilutions. In stage 1, the linear response region and least-square estimate of the assay line slope were established from 9-point dilution assays. Provided that the reading was within the linear response region, this information was used in the stage-2 estimation of titer from a single absorbance reading. Operationally, 2 fixed dilutions were selected, one suitably low and one suitably high, to provide at least one reading within the linear region. The procedure should save considerable time when a large number of assays are to be performed. Stage 1 required approximately twenty 9-point assays, but all subsequent assays required only 2 fixed dilutions.

Pasteurella haemolytica serotype 1 colonization of the nasal passages of virus-infected calves.

Nasal passages of calves with a virus-induced respiratory tract disease became colonized by Pasteurella haemolytica serotype 1 after they were inoculated intranasally with P haemolytica. Inoculation with infectious bovine rhinotracheitis virus caused a more severe clinical illness and resulted in a greater degree of colonization with P haemolytica than developed after inoculation with parainfluenza-3 virus. Nasal passages of parainfluenza-3 virus-inoculated calves were colonized to a greater degree with P haemolytica than were those of healthy, nonstressed calves. Calves were susceptible to P haemolytica colonization during or shortly after virus-induced illness, even though they had been previously exposed to P haemolytica and had serum antibody and nasal secretion antibody to P haemolytica.

Colonization of the nasal passages of calves with Pasteurella haemolytica serotype 1 and regeneration of colonization after experimentally induced viral infection of the respiratory tract.

Healthy nonstressed calves were inoculated intranasally with or subjected to aerosol exposure to Pasteurella haemolytica serotype 1. Only 4 of 28 calves harbored the bacterium in enough numbers to be isolated from the nasal passages for more than 7 days. After apparent clearing from the nasal passages, 8 calves were inoculated intranasally with infectious bovine rhinotracheitis virus; 2 of these calves shed the P haemolytica during clinical illness due to the virus. The remaining 20 calves were aerosol-exposed to parainfluenza-3 virus; 6 of these calves shed P haemolytica during clinical illness due to the parainfluenza-3 virus.

Ovarian hormone effects on activity, glucoregulation and thyroid hormones in the rat.

Ovarian hormonal influences on the range of physiological and behavioral variables which combine to affect overall energy balance are poorly delineated. In the present study 4 groups of virgin, female rats (intact, ovariectomized, ovariectomized with estrogen replacement and ovariectomized with estrogen plus progesterone) were allowed access to running wheels and activity; food intake and weight gain were measured initially under food restricted, then under ad lib conditions. Serum insulin, glucose, thyroxine (T4) and triiodothyronine (T3) were determined on trunk blood samples obtained at the end of the experiment. Ovariectomy resulted in an increased rate of weight gain through reduced activity and T3 but food intake was unchanged. Insulin levels were greatly reduced. Estrogen replacement restored activity to the intact group's level and normalized weight gain. Insulin and T3 were also raised to control levels but T4 was reduced as was serum glucose. Estrogen plus progesterone replacement reduced weight gain markedly and increased T3 with normal T4. Despite the lower body weight this group was hyperglycemic and hyperinsulinemic suggesting insulin resistance. The results have important implications for the glucoregulatory and energy balance perturbations of ovarian hormone fluctuations and focus particularly on progesterone.

Respiratory syncytial virus infection in transported calves.

Nasal swab samples were collected from calves on individual farms in Tennessee and sequentially at an auction barn and at a feedlot to detect respiratory syncytial virus (RSV). In 1976, RSV was isolated from 5 of 225 calves at the auction barn and from 13 of 92 calves examined at the feedlot. Of the 13 isolations, 11 were from calves with acute respiratory tract disease. Most (14/18) calves infected with RSV were also shedding parainfluenza-3 virus in their nasal secretions. Attempts to isolate RSV in the 1977 study were unsuccessful, but there was serologic evidence of RSV infection. Most calves had serum antibody to RSV when examined initially at the farm or at the auction barn. Approximately 46% (46/99) of calves in the 1976 study and 71% (40/56) of calves in the 1977 study had a greater than or equal to 4-fold increase in serum antibody titer to RSV from auction barn to feedlot sample collection.

Enzyme-linked immunosorbent assay for serum antibody to bovine respiratory syncytial virus: comparison with complement-fixation and neutralization tests.

An indirect enzyme-linked immunosorbent assay (ELISA) for the detection of serum antibody to bovine respiratory syncytial virus (BRSV) was developed and compared with complement-fixation (CF) and viral neutralization (VN) tests. Tissue culture-grown viral antigens were used in the tests. Serum samples from various sources were compared, including serum samples from 10 calves which were infected experimentally with BRSV by aerosol exposure. The ELISA compared favorably with the VN test for detecting serologic responses and for detecting passively acquired antibody in young calves. Approximately 98% (109/111) of field serum samples which were positive by the VN test were also positive by ELISA. The ELISA and the CF test both failed to detect early appearing (1 to 4 weeks after exposure) antibody in 2 experimental calves with subclinical infection with BRSV. The CF test appeared to be less specific in that it gave positive reactions with some sera which were negative by both the ELISA and the VN test. The CF test did not detect antibody in 50% of serum samples obtained at the farm from young feeder calves which were positive by both ELISA and the VN test. The ELISA appears to be a sensitive and specific serologic procedure for detecting serum antibody to BRSV and has the advantage of giving test results within several hours, whereas the VN test requires 5 to 6 days for completion.

Isolation of bovine syncytial virus from mesenteric lymph nodes of cattle.

Bovine syncytial virus was isolated from mesenteric lymph nodes of young dairy calves, beef cattle, and mature dairy cattle. Isolations were made in cocultures of lymph node specimens and bovine embryonic lung cells or by subpassage of cocultures in which cytopathic effects were not initially detected. The bovine syncytial viral isolates after storage at -65 C for 3 months in either infected cell cultures of supernate fluids from suspensions or sonically treated infected cell monolayers were usually recovered. Bovine syncytial virus also was recovered from cell cultures after storage for 6 months at -25 C.

Local antibody response in avian infectious bronchitis: virus-neutralizing antibody in tracheobronchial secretions.

Specific-pathogen-free chickens were tested for local antibody response after respiratory exposure to live avian infectious bronchitis virus (IBV). Tracheobronchial secretions were obtained after intraocular-intratracheal vaccinations with Holland and Massachusetts 41 strains IBV. Low levels of immunoglobulin (Ig)A and IgG virus-neutralizing antibodies were detected in secretions after each of two vaccinations with a moderate dose (10(4) EID50), neutralizing activity in secretions was found mainly in IgG antibody. Only challenge exposure to Holland IBV resulted in a marked secondary secretion antibody response.

Avian infectious bronchitis in specific-pathogen-free chickens: quantitation of serum immunoglobulins by electroimmunoassay.

Immunoglobulin (Ig) levels in serums of individual 6-week-old specific-pathogen-free (SPF) chickens differed markedly. Quantitation by electroimmunoassay showed that the IgG level was quite low at 6 weeks of age (1.3 +/- 0.67 mg/ml), increased gradually with maturity, and by 16-18 weeks of age was 2.6 +/- 1.5 mg/ml. IgM levels were less variable during the same observation period (6-18 weeks, 2.4 +/- 0.50 to 2.2 +/- 0.86 mg/ml). IgA was high initially and decreased with age (6-18 weeks, 0.74 +/- 0.78 to 0.26 +/- 0.06 mg/ml). Single intratracheal vaccination with a moderate dose of live avian infectious bronchitis virus (IBV) and subsequent challenge-exposure with live virus via the respiratory tract did not markedly affect Ig levels. Birds vaccinated parenterally 2 or 3 times with live or killed IBV vaccines had a marked increase in serum IgG after similar challenge-exposure. IgA and IgM levels in vaccinated SPF birds approximated those in control SPF birds throughout the experimental period.

Differential use of food and water cues in the formation of conditioned aversions by domestic chicks (Gallus gallus).

The differential use of cues in the formation of conditioned aversions to food and water by domestic chicks was examined. Aversions were more readily demonstrated to red food than to red water, and taste was found to be an adequate cue with water but not with food (Experiments 1-5). It is suggested that such asymmetry mitigates the usefulness of the concept of "belongingness" and can more profitably be viewed as a function of the particular response topographies adopted with respect to food and water. The sixth experiment demonstrated that aversions for colored water could be readily demonstrated when the response topography for drinking was manipulated to ensure the utility of visual cues in selecting fluids. These findings are discussed with respect to a general process approach to conditioned aversion learning.

Pathogenic relationships of rotavirus, Escherichia coli, and other agents in mixed infections in calves.

Infection with agents interpreted as causing or contributing to diarrhea (rotavirus, coronavirus, enterotoxigenic Escherichia coli, and cryptosporidia) were demonstrated in 24 of 32 newborn calves that had naturally occurring diarrheal disease. The calves were from 12 herds in Iowa. Infections as well as enteric lesions and hypoglobulinemia occurred more frequently among diarrheal calves than among nondiarrheal calves from these same herds. In most calves, infections were mixed; ie, both viruses, one or both viruses plus cryptosporidia, or rotavirus plus enterotoxigenic E coli.

Fowl cholera; cross-protective turkey antisera and IgG antibodies induced with Pasteurella multocida-infected tissue bacterins.

Turkey antisera induced with formolized Pasteurella multocida-infected tissues (T antisera) passively cross-immunized 48 of 55 chickens against a challenge dose of P. multocida organisms, from which 0 of 15 controls survived. However, turkey antisera induced with formalin-killed, agar-cultured P. multocida cells (A antisera) passively cross-immunized only 4 of 30 chickens. Cross-immunity refers to protection against a different immunologic type of P. multocida. Quantitative precipitin reactions of the A and T antisera with antigens from agar-cultured cells showed that more antibody was present in the A than in the T antisera. However, antigens extracted from the infected tissues reacted with the T and not with the A antisera in the Ouchterlony procedure, demonstrating qualitative differences between the agar-cultured antigens and those extracted from the infected tissue. The gel precipitins isolated from the A and T antisera were characterized as 7S immunoglobulins, which behaved in immunoelectrophoresis as would be expected for a IgG immunoglobulin. The IgG fraction from the T antiserum passively cross-immunized chickens almost as well as the whole antiserum; hence, the IgG antibody is a major factor in cross-immunity.

Viscerotropic velogenic Newcastle disease in turkeys: immune response following vaccination with either viable B1 strain or inactivated vaccine.

When used as a vaccine, live letogenic B1 Newcastle disease virus (NDV) protects turkeys against challenge-exposure to viscerotropic velogenic NDV (VVNDV). Low-level passively-immune poults were vaccinated one, two, or three times at various intervals and their immunity challenged at various times from 1 to 10 months of age. Newcastle disease virus was isolated readily from either the blood, trachea, or vent of turkeys in all challenge groups (through 5 months of age) on the 3rd to 6th days postchallenge (PC) but after 14 days PC was isolated rarely. Virus was isolated from turkeys that had high titers of serum hemagglutination-inhibition antibodies at the time of challenge. The anamnestic antibody response appeared to be stronger in poults that had low antibody titers prior to challenge-exposure to VVNDV. In a small-scale study with an inactivated VVNDV vaccine, vaccinated poults were protected against challenge with the homologous viscerotropic virus. Parallel control studies on the infectivity of viscerotropic NDV for turkeys indicated that resistance to VVNDV increased with age.

Viscerotropic velogenic Newcastle disease in Turkeys: virus shedding and persistence of infection in susceptible and vaccinated poults.

Susceptible turkeys and turkeys vaccinated with live lentogenic B1 strain Newcastle disease virus (NDV) were inoculated intracularly with viscerotropic velogenic (VV) Fontana strain NDV and studied for virus shedding and persistence of infection. Susceptible poults that survived infection (15%) continued to shed NDV from the intestinal tract up to 46 days postinoculation. Turkeys that were vaccinated with B1 strain NDV did not develop clinical signs when their immunity was challenged with VV Fontana strain virus. Virus was covered up to 53 days postchallenge (PC) from the cloaca of poults that were vaccinated once at 4 days of age and challenged at 1 month of age. Older turkeys that had been vaccinated one to three times did not generally shed virus after 4 days PC. Newcastle disease virus was recovered later in convalescence by the organ-culture method when swabs of trachea and cloaca were negative for virus. Persistent infection was detected as long as 88 days PC in organ cultures of cecal tonsil. Five of seven NDV isolants from organ cultures or from swabs caused fatal disease in chickens.

Viscerotropic velogenic Newcastle disease in turkeys: isolation of Newcastle disease virus from tracheal and cecal tonsil organ cultures.

Tracheal and cecal-tonsil organ cultures were made from vaccinated turkeys that had survived challenge of immunity with viscerotropic velogenic strain of Newcastle disease virus (NDV). Culture fluids were tested to show that latent infections did exist in the vaccinated and challenged turkeys, thus indicating a possible carrier state. NDV was recovered from 6 of 159 turkeys examined. Preliminary tests indicate that 4 isolants are velogenic and 2 are lentogenic.

Viscerotropic velogenic Newcastle disease in turkeys: vaccination against loss of egg production.

Live B1 Newcastle disease virus was administered to young turkeys either intraocularly or by driniking water, or by both methods. Protection against egg production loss was evaluated by challenge-exposure to viscerotropic velogenic Newcastle disease virus in drinking water. During 22 days postchallenge (PC), none of the vaccinated hens had morbidity, whereas 44% of the unvaccinated controls died 6-13 days PC. Percent egg production (PEP) of all groups 1-5 and 6-22 days PC were compared with their levels 1-5 days before challenge. For days 1-5 PC, changes were not significant. For days 6-22 PC, changes for all groups were siginficant lower. The controls had 0 production. Hens vaccinated only at 4 days or at 4 days and again at 4 weeks averaged one-third or less of prechallenge levels but were recovering. Those revaccinated at 4 months maintained 84-91% of their prechallenge levels and were considered satisfactory. Broodiness was a detracting factor in one group of hens vaccinated at 4 days, 4 weeks, and 51/2 months. They averaged two-thirds of prechallenge levels but were in decline.