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21.
Wilson EO 《Science (New York, N.Y.)》1985,228(4707):1489-1495
Studies on the social insects (ants, bees, wasps, and termites) have focused increasingly on sociogenesis, the process by which colony members undergo changes in caste, behavior, and physical location incident to colonial development. Caste is determined in individuals largely by environmental cues that trigger a sequence of progressive physiological restrictions. Individual determination, which is socially mediated, yields an age-size frequency distribution of the worker population that enhances survival and reproduction of the colony as a whole, typically at the expense of individuals. This "adaptive demography" varies in a predictable manner according to the species and size of the colony. The demography is richly augmented by behavioral pacemaking on the part of certain castes and programmed changes in the physical position of colony members according to age and size. Much of what has been observed in these three colony-level traits (adaptive demography, pacemaking, and positional effects) can be interpreted as the product of ritualization of dominance and other forms of selfish behavior that is still found in the more primitive insect societies. Some of the processes can also be usefully compared with morphogenesis at the levels of cells and tissues.  相似文献   
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A condition resembling chronic malignant catarrhal fever was seen in a 9-month-old pet sika hind (Cervus nippon). From an initial acute depression, pyrexia, and anorexia, the condition progressed to include hypopyon, keratitis, lethargy, loss of condition, sloughing of one hoof and eventually death after seven weeks. There were multiple, 5 to 8mm diameter dark-red nodules throughout the mesenteries and mediastinum, along abdominal organ ligaments, and about the uterus and kidneys. Histopathology showed the nodules to be organising vascular thrombi. Concurrent perivascular mononuclear infiltrations and intravascular thrombi in many tissues confirmed that the condition was malignant catarrhal fever.  相似文献   
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Neurophysiology     
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Six 1-year-old farmed red deer were used to compare physiological and behavioural responses to a range of doses of 5% xylazine with or without the addition of 0.4 mg of fentanyl citrate and 3.2 mg of azaperone per ml. Each deer was randomly assigned to one of six treatments: xylazine alone at 0.4 and 0.6 mg/kg, the xylazinelfentanyl citrate/azaperone combination containing 0.2, 0.4 and 0.6 mg/kg of xylazine, or a sterile water control. Injections were given intramuscularly in the anterior neck, operator blind, on each of 6 sampling days between October and January, such that each deer received all treatments with 9-28 days between each treatment. Measurements included heart rate and respiration rate. A 0-3 scoring system (normal to nil response, respectively) was devised to record sedative responses (body stance, head position, degree of eye closure, palpebral reflex, resistance to movement of the head, response to noise) and analgesic responses to touch and pinching of the ear, and response to a needle prick in the gluteal region. Scores were added to produce a sedation score and analgesia score, respectively, for each treatment. Records were taken immediately prior to injection and thereafter at 5, 14, 25, 35, 60, 90, 120, 150, 180, 210, 240 and 300 minutes. All deer given each dose rate of the xylazine and the xylazine/fentanyl citrate/azaperone combination became recumbent. There was a tendency for the time to recumbency and variation of time to recumbency to be shorter at higher dose rates and with the addition of fentanyl citrate and azaperone to xylazine, particularly with xylazine at 0.4 mg/kg. These trends were not statistically significant (p>0.05). The duration of recumbency was shorter with the low dose of the xylazine/fentanyl trateiazaperone combination (0.2 mg/kg of xylazine) than for the higher doses of xylazine alone or the combination of drugs (p<0.05). There were no significant differences in heart rates or respiration rates between treatments, although all treatments significantly reduced both heart and respiration rates (p<0.01). The sedation scores showed similar peak responses and timing to peak responses (14-25 min) to both drug treatments and all dose rates, but the responses were less persistent for lower doses. The analgesia scores showed a similar pattern, with peak responses 14-35 minutes after administration and more persistence at higher dose rates of both xylazine alone and the xylazine/fentanyl citrate/azaperone combination. This study has shown that most physiological and behavioural responses to a range of doses of xylazine or the xylazine/fentanyl citrate/azaperone combination were statistically similar. However, there was a tendency for recumbency to occur more rapidly and with less variation in timing when the mid-range dose of the drug combination was used, supporting the observation by practitioners that the drug combination results in a more rapid and reliable state of recumbency at a lower dose rate of xylazine.  相似文献   
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Four groups of five Romney lambs were treated by plunge dipping with one of four registered organophosphorus flystrike preventatives. Untreated lambs acted as controls. The sheep were challenged at weekly intervals with larval implants of organophosphate-susceptible and -resistant strains of Lucilia cuprina. All four treatments provided 19-21 weeks protection against susceptible larvae but chlorfenvinphos provided the longest protection (16-17 weeks), followed by propetamphos (15-16 weeks), dichlofenthion (10-13 weeks) and diazinon (9-13 weeks), against the resistant strain.  相似文献   
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Absorption of endotoxin from the gastrointestinal tract was evaluated in hay-fed and lactic acidotic sheep duodenally infused with 10 mg of Escherichia coli endotoxin, and in lactic acidotic sheep not infused. The effect of abomasal fluid on biological activity of endotoxin was also evaluated. Leukopenia was the criterion used for detecting endotoxemia. Absorption of endotoxin from the gastrointestinal tract was not detected in either hay-fed or lactic acidotic sheep. Endotoxin appeared to maintain its activity after incubation with abomasal fluid, and the presence of endogenous endotoxin in abomasal contents was indicated. The results indicate that endotoxin of alimentary origin may not be involved in the lactic acidosis syndrome in ruminants.  相似文献   
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