Viral and bacterial agents associated with experimental transmission of infectious proventriculitis of broiler chickens.

Proventriculitis of broilers can be reproduced by oral inoculation of day-old chicks with a proventricular homogenate from affected 3-wk-old broilers. The objective of the following studies was to isolate from this homogenate viral and bacterial isolates that could produce proventriculitis. A monoclonal antibody to infectious bursal disease virus (IBDV) was used to precipitate virus from the homogenate. A primary chicken digestive tract cell culture system was also used to isolate virus from a 0.2-microm filtrate of the homogenate, and a bacterium was also isolated from the homogenate. In trial 1, day-old birds were orally inoculated with either proventriculus homogenate or monoclonal antibody immunoprecipitated IBDV (MAB-IBDV). At 4, 7, 14, and 21 days postinfection (PI), 12 birds from each treatment group were subjected to necropsy. In trial 2, day-old birds were orally inoculated with either infectious proventriculus homogenate, suspect virus isolated in cell culture and propagated in embryo livers and spleens, or a bacterial isolate. Twelve birds from each treatment were subjected to necropsy at days 7, 14, 21, and 28 PI. In trial 3, treatments were maintained in negative pressure isolation chambers, and an additional treatment included virus plus bacterial isolate. Twenty-four birds from each treatment were subjected to necropsy at day 21 PI. In trial 1, infectious homogenate decreased body weight and relative gizzard weights at 4, 7, 14, and 21 days PI. Proventriculus relative weight was increased at days 7, 14, and 21 PI, and proventriculus lesion scores were increased at days 14 and 21 PI. Bursa/spleen weight ratios were decreased at day 14, and feed conversion was increased at days 4 and 21. The MAB-IBDV treatment decreased proventriculus and gizzard relative weights at day 4 PI, increased proventriculus lesion scores and bursa/spleen weight ratios at day 14, and decreased heterophil/lymphocyte ratios at day 21. In trial 2, all infected birds had significantly higher mean relative proventriculus weights at 21 days PI and had higher 4-wk mean proventriculus scores as compared with both control groups. In trial 3, birds treated with homogenate and birds treated with both suspect virus and the bacterial isolate had significantly higher proventriculus lesion scores; higher relative weights of proventriculus, gizzard, liver, and heart; lower body weights; and lower relative bursa weights compared with the saline control group. These studies suggest that infectious proventriculitis has a complex etiology involving both viral and bacterial infection.     

Correlation between Chemical Structure and Biological Activity of Host-Selective Plant Pathogen Mycotoxins

Toxin, one of the most important factors of plant fungal disease, has attracted much attention of many academicians who have been studying pathogen mycotoxin in deep research. The paper summarized chemical structures of some host-selective plant pathogen mycotoxins discovered in recent years and the correlation between biological activity and chemical structure of toxin.     

Stabilizing Lead-Salt Diode Lasers: Understanding and Controlling Chaotic Frequency Emission

Lead-salt tunable diode lasers (TDLs) are the only devices currently available that can generate tunable monochromatic radiation at arbitrary wavelengths between 3 and 30 micrometers and are particularly useful for high-resolution spectroscopy over a wide range of spectral regimes. Detailed observations of TDLs show that the observed instrumental linewidth is actually a temporal average of many narrow (less than 0.5 megahertz) emission "modes." The time scale characteristic of these "modes," which appear to be of relatively constant intensity, is of the order of a microsecond. The laser's behavior is highly suggestive of a chaotic process, that is, seemingly random excursions of a dynamic variable (frequency) within a bounded range. This report shows experimentally that TDL emissions are indeed chaotic. Furthermore, in a simple and robust fashion, this chaotic behavior has been successfully controlled with the use of recent techniques that take advantage of chaos to produce a narrow band laser output.     

Radar soundings of the subsurface of Mars

The martian subsurface has been probed to kilometer depths by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express orbiter. Signals penetrate the polar layered deposits, probably imaging the base of the deposits. Data from the northern lowlands of Chryse Planitia have revealed a shallowly buried quasi-circular structure about 250 kilometers in diameter that is interpreted to be an impact basin. In addition, a planar reflector associated with the basin structure may indicate the presence of a low-loss deposit that is more than 1 kilometer thick.     

酸度对胡敏酸与镉和锌离子络合反应的影响

用离子交换平衡法研究了不同pH下胡敏酸与锌、镉单独及复合存在下形成络合物的稳定性及配位数.结果表明:在Zn2+,Cd2+单独存在时,络合反应的稳定常数及配位数随着pH值的增大而增大;相同pH条件下,Zn2+和胡敏酸络合物的稳定常数及配位数大于Cd2+.在Zn2+,Cd2+复合存在时,pH的变化与胡敏酸络合金属离子的稳定常数及配位数没有明显依存关系;与单独存在时相比,在pH 3.5和pH7.0时,Zn2+,Cd2+和胡敏酸络合物的稳定常数和配位数都减小;而在pH 5.0时,Cd2+和胡敏酸络合物的稳定常数和配位数都增大,Zn2+和胡敏酸络合物的稳定常数和配位数都减小.     

Changes in hematological, blood gas, and serum biochemical variables in broilers during exposure to simulated high altitude.

One-day-old broilers were reared until 35 days of age at both natural low (100 m) and simulated high altitude (2133 m) to assess the incidence and development of ascites syndrome. Clinical measurements were conducted at 7, 14, 21, 28, and 35 days of age. Birds reared at 2133 meters exhibited significantly (P less than or equal to 0.05) reduced body weights at 7 through 28 days of age. Total serum calcium and biochemical enzyme activities were found to be altered at 35 days of age. In addition, the high-altitude group had significantly (P less than or equal to 0.05) higher erythrocyte counts, hematocrits, and hemoglobin at 14, 21, 28, and 35 days of age and higher serum inorganic phosphorus at each weekly sample time than birds at the low altitude. Total mortality was 20.3% at 2133 meters and 4.6% at 100 meters. The incidence of ascites syndrome in the high-altitude group ranged from 16.6% to 61.1% during the 5-week experimental period.     

The effects of water supplementation with vitamin E and sodium salicylate (Uni-Sol) on the resistance of turkeys to Escherichia coli respiratory infection

The objective of this study was to determine the prophylactic efficacy of two commercial products, soluble vitamin E and soluble sodium salicylate (Uni-Sol), in an Escherichia coli respiratory challenge. The drinking water of male turkey poults was nonsupplemented or supplemented with either vitamin E or Uni-Sol or a combination of both at dosages recommended by the manufacturer. There were 110 birds in each of the four treatments, housed in four floor pens per treatment. At 5 wk of age, birds in half of the pens were challenged with an air sac inoculation of approximately 50 colony-forming units of E. coli. Water treatment commenced 5 days before challenge and continued for 2 wk after challenge, when birds were necropsied. All water treatments prevented the decrease in body weight due to E. coli challenge; however, either vitamin E or Uni-Sol alone, but not the combination of the two, decreased body weight in nonchallenged controls. Either vitamin E or Uni-Sol treatment alone, but not the combination of the two, significantly decreased mortality and air sacculitis scores of challenged birds, and all treatments decreased the isolation rates of E. coli from the liver. All treatments protected liver, spleen, and bursa weights (relative to body weight) from the effects of E. coli challenge, and Uni-Sol alone or vitamin E with Uni-Sol protected relative heart weights from the effect of challenge. Uni-Sol treatment alone increased the main effect mean total leukocyte counts and the number and percent of lymphocytes. Uni-Sol in combination with vitamin E increased the number of lymphocytes of challenged birds. Uni-Sol alone decreased the main effect mean heterophil/lymphocyte ratio (H/L) ratio, whereas vitamin E alone increased the H/L ratio of challenged birds. These results indicate that treatment of turkey poults with vitamin E or Uni-Sol prior to and during the stressful events that can lead to colisepticema may decrease disease incidence and mortality.