成膜抗蒸腾剂控制小麦叶锈病和白粉病的作用

本试验的各种成膜抗蒸腾剂都有效地控制了小麦叶锈病和白粉病:在旗叶出现后应抗蒸腾乳胶剂便足以抑制小麦叶片上的叶锈病和白粉病;于接种之前,在室内幼苗植株上应用抗蒸腾聚合物可以减轻叶锈病,但接种时用药则无效。     

真菌除草剂——杂草生物防治的进展

一般说来,比较理想的除草剂应该符合生产简便、容易贮藏、廉价高效以及对人和环境安全等要求。显然,某些侵染杂草的病原真菌具备其中的大多势特点。在过去10年中,已就利用植物病原真菌进行生物除草的问题进行了广泛研究。其使用方法主要有经典式和淹没式(inundati-     

Dynamics of the vocal imitation process: how a zebra finch learns its song

Song imitation in birds provides good material for studying the basic biology of vocal learning. Techniques were developed for inducing the rapid onset of song imitation in young zebra finches and for tracking trajectories of vocal change over a 7-week period until a match to a model song was achieved. Exposure to a model song induced the prompt generation of repeated structured sounds (prototypes) followed by a slow transition from repetitive to serial delivery of syllables. Tracking this transition revealed two phenomena: (i) Imitations of dissimilar sounds can emerge from successive renditions of the same prototype, and (ii) developmental trajectories for some sounds followed paths of increasing acoustic mismatch until an abrupt correction occurred by period doubling. These dynamics are likely to reflect underlying neural and articulatory constraints on the production and imitation of sounds.     

Sedative, analgesic, and cardiovascular effects of levomedetomidine alone and in combination with dexmedetomidine in dogs

OBJECTIVE: To determine whether a high dose of levomedetomidine had any pharmacologic activity or would antagonize the sedative and analgesic effects of dexmedetomidine in dogs. ANIMALS: 6 healthy Beagles. PROCEDURE: Each dog received the following treatments on separate days: a low dose of levomedetomidine (10 microg/kg), IV, as a bolus, followed by continuous infusion at a dose of 25 microg/kg/h; a high dose of levomedetomidine (80 microg/kg), IV, as a bolus, followed by continuous infusion at a dose of 200 microg/kg/h; and a dose of isotonic saline (0.9% NaCl) solution, IV, as a bolus, followed by continuous infusion (control). For all 3 treatments, the infusion was continued for 120 minutes. After 60 minutes, a single dose of dexmedetomidine (10 microg/kg) was administered IV. Sedation and analgesia were scored subjectively, and heart rate, blood pressure, respiratory rate, arterial blood gas partial pressures, and rectal temperatures were monitored. RESULTS: Administration of levomedetomidine did not cause any behavioral changes. However, administration of the higher dose of levomedetomidine enhanced the bradycardia and reduced the sedative and analgesic effects associated with administration of dexmedetomidine. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of dexmedetomidine alone may have some cardiovascular benefits over administration of medetomidine, which contains both dexmedetomidine and levomedetomidine. Further studies are needed to confirm the clinical importance of the effects of levomedetomidine in dogs.     

Cutaneous metastases of a mammary carcinoma in a llama

An 8-year-old, female llama was evaluated for nonhealing, ulcerative, cutaneous lesions, which also involved the mammary gland. Biopsies of the lesions distant from and within the mammary gland area revealed an aggressive carcinoma. The tumor was confirmed at necropsy to be a mammary gland adenocarcinoma with cutaneous metastasis.     

Sudden death of a bearded vulture (Gypaetus barbatus) possibly caused by Newcastle disease virus

An adult female bearded vulture (Gypaetus barbatus) in the Tel Aviv University Research Zoo was found dead without previous clinical signs. The predominant pathologic changes were considerable bloody content in the intestines and enlargement of the liver, which had a rubbery consistency with color changes. Microscopic lesions consisted of multifocal histiocytic infiltration in the liver. Newcastle disease virus (NDV) was isolated from a cloacal swab and from the lungs and liver. Intracerebral pathogenicity index of the virus, as estimated in 1-day-old chicks, was repeated three times and had an average value of 1.68, indicating a velogenic strain. Numerous Clostridium septicum bacteria were found on the intestinal surface, but bioassays in which they were orally administered into chickens and mice revealed that, even though they were heavily multiplied in the intestines, they were nonpathogenic. It seems that NDV, documented for the first time in a bearded vulture in Israel, was the likely cause of sudden death.     

Phosphorus bioavailability, growth performance, and nutrient balance in pigs fed high available phosphorus corn and phytase

Three experiments were conducted to evaluate P bioavailability, growth performance, and nutrient balance in pigs fed high available P (HAP) corn with or without phytase. The bioavailability of P in normal and HAP corn relative to monosodiumphosphate (MSP) for pigs was assessed in Exp. 1. In a randomized complete block design, 96 pigs (average initial BW 9.75 kg) were fed eight diets for 28 d. The reference and test diets were formulated by adding P as MSP, HAP, or normal corn at 0, 0.75, or 1.5 g/kg to a corn-starch-soybean meal basal diet (2.5 g/kg P) at the expense of cornstarch. Plasma inorganic P concentration responded linearly (P < 0.05) to supplemental P intake. Estimates of P bioavailability from HAP andnormal corn when plasma P was regressed on supplemental P intake were 46 and 33%, respectively. In Exp. 2 and 3, pigs were fed corn-soybean meal-based diets containing HAP corn or normal corn and 0 or 600 units of phytase per kilogram in a 2 x 2 factorial arrangement (two corn sources and two levels of phytase). In Exp. 2, 48 crossbred pigs (barrow:gilt, 1:1) averaging 9.25 kg were used to evaluate growth performance. There were no detectable interactions between corn source and phytase for any of the performance criteria measured. Pigs receiving normal corn had the lowest (P < 0.05) BW and rate of gain. Feed efficiency was lower (P < 0.05) in pigs fed normal compared with those fed the HAP corn phytase-supplemented diet. In Exp. 3, 24 crossbred barrows averaging 14.0 kg were used to evaluate nutrient digestibility. There were no detectable interactions between corn and phytase for any of the N and Ca balance criteria. Nitrogen and Ca retention were improved in pigs receiving HAP corn with phytase (P < 0.05). Retention and digestibility of P was lowest (P < 0.01) for pigs on normal corn diet without phytase. The percentage of P digested and retained was improved and fecal P excretion lowered (P < 0.05) by feeding HAP corn.The results of this study indicate that the bioavailability and balance of P in HAP corn is superior to that of normal corn. The addition of 600 phytase units (Natuphos 600, BASF) to HAP corn-based diets further improved P digestibility and reduced P excretion in pigs.