Neural maps for target range in the auditory cortex of echolocating bats.

Computational brain maps as opposed to maps of receptor surfaces strongly reflect functional neuronal design principles. In echolocating bats, computational maps are established that topographically represent the distance of objects. These target range maps are derived from the temporal delay between emitted call and returning echo and constitute a regular representation of time (chronotopy). Basic features of these maps are innate, and in different bat species the map size and precision varies. An inherent advantage of target range maps is the implementation of mechanisms for lateral inhibition and excitatory feedback. Both can help to focus target ranging depending on the actual echolocation situation. However, these maps are not absolutely necessary for bat echolocation since there are bat species without cortical target-distance maps, which use alternative ensemble computation mechanisms.

Postnatal maturation of primary auditory cortex in the mustached bat, Pteronotus parnellii.

The primary auditory cortex (AI) of adult Pteronotus parnellii features a foveal representation of the second harmonic constant frequency (CF2) echolocation call component. In the corresponding Doppler-shifted constant frequency (DSCF) area, the 61 kHz range is over-represented for extraction of frequency-shift information in CF2 echoes. To assess to which degree AI postnatal maturation depends on active echolocation or/and reflects ongoing cochlear maturation, cortical neurons were recorded in juveniles up to postnatal day P29, before the bats are capable of active foraging. At P1-2, neurons in posterior AI are tuned sensitively to low frequencies (22-45 dB SPL, 28-35 kHz). Within the prospective DSCF area, neurons had insensitive responses (>60 dB SPL) to frequencies <40 kHz and lacked sensitive tuning curve tips. Up to P10, when bats do not yet actively echolocate, tonotopy is further developed and DSCF neurons respond to frequencies of 51-57 kHz with maximum tuning sharpness (Q(10dB)) of 57. Between P11 and 20, the frequency representation in AI includes higher frequencies anterior and dorsal to the DSCF area. More multipeaked neurons (33%) are found than at older age. In the oldest group, DSCF neurons are tuned to frequencies close to 61 kHz with Q(10dB) values < or =212, and threshold sensitivity, tuning sharpness and cortical latencies are adult-like. The data show that basic aspects of cortical tonotopy are established before the bats actively echolocate. Maturation of tonotopy, increase of tuning sharpness, and upward shift in the characteristic frequency of DSCF neurons appear to strongly reflect cochlear maturation.

Specializations for aerial hawking in the echolocation system of Molossus molossus (Molossidae, Chiroptera).

While searching for prey, Molossus molossus broadcasts narrow-band calls of 11.42 ms organized in pairs of pulses that alternate in frequency. The first signal of the pair is at 34.5 kHz, the second at 39.6 kHz. Pairs of calls with changing frequencies were only emitted when the interpulse intervals were below 200 ms. Maximum duty cycles during search phase are close to 20%. Frequency alternation of search calls is interpreted as a mechanism for increasing duty cycle and thus the temporal continuity of scanning, as well as increasing the detection range. A neurophysiological correlate for the processing of search calls was found in the inferior colliculus. 64% of neurons respond to frequencies in the 30- to 40-kHz range and only in this frequency range were closed tuning curves found for levels below 40 dB SPL. In addition, 15% of the neurons have double-tuned frequency-threshold curves with best thresholds at 34 and 39 kHz. Differing from observations in other bats, approach calls of M. molossus are longer and of higher frequencies than search calls. Close to the roost, the call frequency is increased to 45.0-49.8 kHz and, in addition, extremely broadband signals are emitted. This demonstrates high plasticity of call design.

Efficacies of Novel N-Halamine Disinfectants against Salmonella and Pseudomonas Species.

Six novel N-halamine compounds of potential importance as disinfectants to the food-processing industry were tested against Salmonella enteritidis, Salmonella gallinarum, Salmonella typhimurium, and Pseudomonas fluorescens in aqueous solution. Inactivation times for 10-fold reductions were determined as a function of water quality at pH 6.5 and 25 degrees C. Phenol coefficients for the efficacies of the compounds against S. enteritidis have been reported also. When both stability and efficacy data are considered, as well as cost of production, two compounds, 1,3-dichloro-2,2,5,5-tetramethylimidazolidin-4-one and 1-chloro-2,2,5,5-tetramethylimidazolidin-4-one, offer the greatest potential as biocides for the food-processing industry.

Effect of surgical and chemical in ovo bursectomy on lymphocyte density scores and histological evaluations of primary and secondary lymphoid organs in hypertensive and hypotensive turkeys.

The effects of surgical and chemical in ovo bursectomy on the histology of primary and secondary lymphoid organs were studied in hypertensive and hypotensive lines of turkeys. The effects of bursectomy were measured by determining the presence of lymphatic nodules and the presence of lymphocytes in secondary lymphoid organs: spleen, cecal tonsil, Meckel's diverticulum, and Peyer's patches; as well as in the thymus and bursa of Fabricius. No treatment effect on splenic nodule formation occurred, but a significantly lower lymphocyte density score was present in the surgically bursectomized group. Both nodule formation and lymphocyte density scores for the cecal tonsil and Peyer's patches were significantly reduced in the surgically bursectomized and testosterone-treated groups as compared with the control and sham groups. The most consistent depression in lymphatic scores in both the surgically and chemically bursectomized groups occurred in the Peyer's patches followed by cecal tonsils and Meckel's diverticulum. As expected, there were no differences in thymocyte density scores. There was no consistent effect on lymphatic scores due to blood pressure selection; however, the hypertensive line showed significantly lower scores than the hypotensive line in the bursa, cecal tonsils, and Peyer's patches. No differences between the sexes were noted in any organ.

Effect of surgical and chemical in ovo bursectomy on hatchability, mortality rate, and antibody response in hypertensive and hypotensive lines of turkeys.

The effect of in ovo bursectomy on hatchability, mortality rate, and antibody response to keyhole limpet hemocyanin (KLH) was studied in hypertensive and hypotensive lines of turkeys. Experiments were conducted to assess the optimal time to perform surgical in ovo bursectomy in turkey embryos for the lowest mortality rate. Factors such as the ease of operation, hatchability, and least deaths were considered. Surgical bursectomies at 25, 24, 23, and 22 day embryonation resulted in 75, 20, 0, and 10% hatchability, respectively. The surgical procedure performed at 25-day embryonation resulted in superior hatchability and ease of operation, and it was less traumatic as evidenced by fewer deaths. The hatchability of embryos injected with testosterone (TE) at 15 days incubation was 55%. Birds subjected to surgery or chemical treatment had increased mortality rates. Cyclophosphamide (CY) treatment at 1 and 2 days posthatch caused a significant increase in deaths over groups not treated with CY. Both primary and secondary KLH responses were significantly lower in bursectomized and TE-injected groups, than in shamoperated or nonoperated control groups.

Ultrastructure of schizonts and merozoites of Eimeria mitis and E. mivati of the chicken.

Measurements of fourth-generation schizonts and merozoites of Eimeria mitis averaged 10.3 (8.7-12.4) x 7.2 (6.3-8.2) and 5.06 x 1.75 microns, respectively, whereas schizonts and merozoites of E. mivati averaged 8.0 (6.9-9.1) x 6.5 (6.2-6.8) and 5.88 x 0.75 micron, respectively. Schizonts of E. mitis had six or seven merozoites each, whereas schizonts of E. mivati had as many as 20 merozoites. The structural components of the merozoites of both species appeared similar. E. mitis parasites penetrated deeper into the host cells than E. mivati. There was usually only one E. mitis fourth-generation schizont or gamete per host cell and more than one of E. mivati per cell.

Histological evaluation of the vascular system for the severity of atherosclerosis in hyper and hypotensive male and female turkeys: comparison between young and aged turkeys.

Relationships among age, blood pressure, and atherosclerosis were studied in turkeys genetically selected for high and low systolic blood pressure ranging in age from 2 days to 104 weeks. Relationships between sex and atherosclerosis were studied only at 104 weeks of age. Abdominal aortas were examined in all birds in each age group. The left and right internal, external, and common carotid arteries, cranial and caudal thoracic aortas, area of coeliac orifice, sciatic junction, left and right sciatic arteries, left and right coronary arteries, and left and right deep branches of the coronary arteries were examined in the 104-week-old group. Mean abdominal aortic plaque scores for the different age groups increased linearly to the age of 12 weeks; after this time scores reached a plateau. Except for the first and last time period, the hypertensive group of males showed a significantly greater abdominal aortic plaque score than the hypotensive group. The right sciatic artery was the only other blood vessel in the 104-week-old group that had a significantly greater plaque score in the hypertensive line when compared with the hypotensive line. In the 104-week period, only the left and right sciatic arteries showed significantly higher plaque scores in the males than in the females. Also, only the male turkeys showed an increase in plaque scores with a concomitant rise in systolic pressure. In 104-week-old females there was no evidence of intimal change in either the left and right internal carotids, left and right common carotids, cranial thoracic aorta, or the right coronary artery. The hypertensive line had significantly greater blood pressure and greater ventricular weight, length, and sagittal width than the hypotensive line. The 104-week-old turkeys had more lipid staining material within the plaque than the younger birds, and calcification was evident in two of the older turkeys.

Rupture pressure of elastic and muscular aortic segments from hypertensive and hypotensive turkeys.

Blood pressures and heart rates were recorded from two groups of turkeys in two trials. In trial one 20 turkeys, 36 weeks of age and in trial two 24 turkeys, 14 weeks of age, were used. Immediately after blood pressures and heart rates had been determined, the turkeys were killed and vascular tissues were excised. Equal numbers from hypertensive and hypotensive lines of turkeys were used in each trial to determine the rupture pressure of both the elastic and muscular segments of the aorta. When values for the two trials were combined, mean hydrostatic pressures of 1478, 1804, and 794 mm Hg respectively were required to rupture the most caudal abdominal aortic segment, the adjacent cranial abdominal segment, and the thoracic aortic segment. There was a significant difference between the two lines for blood pressure in both trials and for heart rate in trial 2. There were no statistically significant correlations between blood pressure, atherosclerotic plaque score and rupture pressure. Birds fed on a diet containing added fat and cholesterol had significantly lower blood pressures than the birds fed on the other two diets. Birds receiving added dietary cholesterol and fat had lower heart rates than birds fed on the diet with added fat only. Lower plaques scores were evident in the caudal abdominal aorta of the birds fed on the control diet compared to birds fed on the other two diets.

Photoinduced buphthalmic avian eyes: II. Continuous darkness.

Chickens raised from 2 to 14 weeks of age in continuous darkness (OL:24D) developed shallow anterior chambers and buphthalmos (megaloglobus). Chickens raised in continuous darkness developed ocular changes similar to that reported in chickens raised in continuous fluorescent and incandescent light and in dim light. Corneal diameters and axial globe lengths were an inconsistent means of documenting ocular enlargement. Iridocorneal angles were narrowed on scanning electron microscopy (SEM). Intraocular pressure (IOP) was not different from control chickens. The chicken is proposed as a model to study ocular development, the effects of lid suture on infants, axial myopia, preglaucomatous changes, and possibly pharmacologic effects of antiglaucoma preparations.

Effects of exercise conditioning on semen characteristics from hyper- and hypotensive lines of turkeys.

Twenty-one male Broad Breasted White turkeys which had been selected for high or low blood pressure were put on an exercise regimen to determine its effect on semen quality. Eleven were from the hypertensive line and 10 from the hypotensive line. Eleven (6 hypertensive and 5 hypotensive) turkeys were placed on an exercise regime of walking (herding) about 1 mile daily for 6 weeks before the experiment began, and then for a further 6 weeks during semen collection. Semen was collected from 11 turkeys on the exercise regime and 10 nonexercised control birds which were kept in their experimental pens during the trial. Both hypertensive and exercised groups showed an improved semen colour score at the first collection period (P less than or equal to 0.09). Only the exercised group showed a significantly (P less than or equal to 0.05) better score than the control group during periods 2 and 3. The hypertensive line showed significantly higher spermatozoa count than the hypotensive line during the first collection period. There was no effect of either exercise or selection for high or low blood pressure on semen volume.

Photoinduced buphthalmic avian eyes. 1. Continuous fluorescent light.

Numerous investigations of light induced avian buphthalmia using incandescent light have not defined an etiology. Chickens raised from 2 weeks of age in continuous fluorescent light developed shallow anterior chambers and buphthalmos within the first month of treatment. Chickens raised in continuous fluorescent light developed ocular enlargement similar to that reported in chickens raised in continuous incandescent light. Corneal diameters and axial globe lengths were an inconsistent means of documenting ocular enlargement. Iridocorneal angles were narrowed on scanning electron microscopy.

Toxic shock-like syndrome in hens and its relationship to shell-less eggs.

Foreign materials were inserted into the hens' uteri and anti-inflammatory and immune suppressant drugs were used to determine possible causes of shell-less eggs. The presence of foreign shell-membranes and tampons in the uteri (shell glands) of hens caused a toxic shock-like syndrome ( TSLS ). Primary clinical signs were high fever, vomiting, diarrhea, and death. The presence of other materials, including inflated rubber balloons, had no adverse affect on the hens. Calcium carbonate deposits occurred on the surface of the balloons but not on other material inserted into the uteri. Injection of anti-inflammatory or immunosuppressive drugs did not increase shell weight in hens laying shell-less eggs. The hens' reproductive system was found to be sensitive in varying degrees to different types of foreign materials; thus, the avian female might serve as an animal model for studying toxic shock syndrome.

Effect of exercise on aortic atherosclerosis and other cardiovascular variables among hyper- and hypotensive turkeys.

Two experiments were conducted to determine the effects of physical training on the turkey cardiovascular system. Sexually mature (Experiment 1) and immature (Experiment 2) Large White turkeys were used. Equal numbers of genetically hypertensive and hypotensive birds were used in each experiment. In each experimental group, birds were randomly divided into exercise and control treatments. Assessments were made with regard to training effects and differences associated with genetic blood pressure strain. Exercise had no significant effect on the severity of atherosclerosis or serum lipid levels in either experiment. Significantly greater hematocrits were recorded among birds exercised in Experiment 1; however, hemoglobin concentration did not follow this trend. Exercise was also associated with increased cardiac dimensions (Experiment 1) and increased body weight (Experiment 2). Genetic hypertension was associated with accelerated atherogenesis and higher serum cholesterol levels in immature birds, and in mature birds cardiac enlargement was associated with hypertension. Differences in behavior response to exercise were observed between the two experiments. Sexually mature hypertensive turkeys showed less endurance to the walking regimen than the hypotensive turkeys, but no such differences were observed in immature hypertensive or hypotensive birds.

Noncitrinin toxicity of Penicillium citrinum contaminated corn.

Day-old white Leghorn chicks were fed P. citrinum-contaminated corn at 3.88, 7.75, 31, or 62% levels in the ration for a period of 5 weeks. High treatment levels (31 and 62%) of contaminated corn in the ration caused severe growth depression, high mortality, and significant decreases in feed consumption. Necrosis of periportal and centrilobular hepatocytes, glomerular atrophy and hyperplasia, degeneration and necrosis of tubular cells, lymphoid depletion, suppression of hematopoiesis, necrosis of pancreatic acinar cells, and a cardiac and skeletal myopathy were observed microscopically in chicks fed 31 and 62% contaminated corn in the rations. Low levels of contaminated corn in the ration (3.88 and 7.75%) caused few clinical effects; however, liver and kidney changes were observed microscopically. Ultrastructural observation of affected tissues showed swelling of mitochondria, dilatation of the endoplasmic reticulum, increased numbers of autophagic vacuoles and paramyelin figures, and lipoprotein peroxidation of organelles. The toxin (s) present in the P. citrinum contaminated ration have not been identified.

Localization of herpesvirus of turkeys in blood cells.

The buffy coat pellets of blood clots from Broad Breasted Large White turkeys were processed for electron microscopy. No viruses were found in extracellular spaces nor in the heterophils, eosinophils, or basophils. Enveloped virions, measuring approximately 135 nm in diameter consisting of a core 30 to 35 nm in diameter and a capsid 20 to 30 nm thick were found in cytoplasmic vacuoles in lymphocytes. No developmental stages of virus maturation were observed in the nuclei or cytoplasm of any of the lymphocytes. Virus-like particles were observed in the nuclei and perinuclear zones of many erythrocytes and were approximately 135 nm in diameter but did not possess herpesvirus morphology.

Hemorrhagic syndrome of chicks produced by Penicillium citrinum AUA-532 contaminated corn.

Rations containing 0%, 6.2%, and 62% Penicillium citrinum contaminated corn were fed to White Leghorn chicks for 5 weeks. The 62% ration induced hemorrhaging throughout the digestive tract which resembled the lesions observed in acute cases of the poultry hemorrhagic syndrome. The 6.2% ration caused atrophy of lymphoid tissue, anemia, leucopenia, and fatty bone marrow which resembled the lesions observed in chronic cases of the poultry hemorrhagic syndrome. The syndrome was reproduced in chicks using ethanol and chloroform extracts of the P. citrinum contaminated corn.

A comparison between aortic lumen surfaces of hypertensive and hypotensive turkeys.

Some features of the aortic intima were examined with the scanning electron microscope (SEM) and found to contribute to the etiology of dissecting aneurysm. The endothelium over intimal plaques was not as pendulous as endothelium surrounding plaques. The pendulous appearance of aortic endothelial cells could be associated with the contractile nature of these cells. Some undescribable factor, which has been termed stress or atherosclerosis, seemed to reduce the contractile nature of endothelial cells on the plaque areas. Analyses with SEM revealed a probable cause of a dissecting aneurysm. The effect of pulsating blood pressure on an inelastic endothelium could create a separation between endothelial cells and the fluid pressure of blood could then separate the tissue until the vessel ruptured into the body cavity or back into the aorta. Because all abdominal aortic segments examined had atherosclerosis, it was not possible to show the amount of intimal alteration between normal and atherosclerotic aortas. Each blood pressure line showed a similar change which was 4.52 and 4.95% for the high and low blood pressure lines, respectively. There were no demonstrable correlations in this study between either high or low blood pressure lines of turkeys and atherosclerosis.