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Effects of infection with a granulosis virus on larval growth, development and ecdysteroid production in the cabbage looper, Trichoplusia ni 总被引:2,自引:0,他引:2
E. M. DOUGHERTY T. J. KELLY R. ROCHFORD J. A. FORNEY J. R. ADAMS 《Physiological Entomology》1987,12(1):23-30
ABSTRACT. Granulosis virus-infected Trichoplusia ni (Hûbner) larvae exhibited an increased larval life span with no supernumerary moult and no pupation. Weight gain was not affected. Insects infected shortly after hatching were slower in reaching the fourth and fifth stadia than were control insects. Haemolymph ecdysteroid titres were lower in virus-infected insects than control insects, but these differences were only significant ( P <0.05) in the fifth stadium. Electron microscopic examination of the pro thoracic glands revealed extensive granulosis virus infection, and glands from virus-infected insects produced no RIA-detectable ecdysteroids in vitro. Injection of 20-OII-ecdysone into virus-infected larvae at various concentrations and times did not induce pupation. 相似文献
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Codon usage in the vertebrate hemoglobins and its implications 总被引:2,自引:0,他引:2
A study of codon usage in vertebrate hemoglobins revealed an evolutionary
trend toward elevated numbers of CpG codon boundary pairs in mammalian
hemoglobin alpha genes. Selection for CpG codon boundaries countering the
generally observed CpG suppression is strongly suggested by these data.
These observations parallel recently published experimental results that
indicate that constitutive expression of the human alpha-globin gene
appears to be determined by regulatory information encoded within the
structural gene. The possibility is raised that, in the absence of
selection, CpG decay can be used to date the evolutionary origin of a
mammalian alpha pseudogene from its active alpha gene.
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URRY RONALD L.; DOUGHERTY KATHRYN A.; FREHN JOHN L.; ELLIS LEGRANDE C. 《Integrative and comparative biology》1976,16(1):79-91
This article reviews those factors other than light that affectthe activity of the pineal gland. Both testosterone and dihydrotestosteronewere shown to have tissue specific inhibitory effects on pinealMAO activity concomitant with an increased activity of the gland.Estradiol stimulated pineal MAO activity and decreased the activityof this gland. This effect also was tissue-specific. Bilateraland unilateral experimental cryptorchidism also decreased pinealMAO activity 3 to 4 weeks after surgery. Acute stresses appearto increase adrenal catecholamine output (epinephrine and norepinephrine)as well as to stimulate local adrenergic pathways, while chronicstress, such as starvation, appears to act through the adrenalcorticosteroids by decreasing pineal MAO activity thereby indirectlyincreasing melatonin synthesis. Thusly, both components of theadrenal gland appear to act in concert to increase effectivelymelatonin synthesis by the pineal gland. Irradiation and histaminehave also been reported to affect pineal functionthelatter specifically inhibits HIOMT activity. These observationsindicate that many factors other than light affect pineal morphologyand melatonin synthesis. The pineal appears to be a true neuroendocrineorgan that is affected by hypophysectomy and is responsive tofeedback and control from other organs within the mammalianorganism. 相似文献
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Repeated measures analysis was used to evaluate the effect of long-term CO2 enhancement on seasonal trends of light-saturated rates of net photosynthesis (Asat) and stomatal conductance to water vapour (gsat) of 9-year-old loblolly pine (Pinus taeda L.) trees grown in a 2 × 2 factorial experimental design of nutrition and water. A significant interaction effect of CO2 and nutrition on mean Asat was observed for juvenile foliage. Also, juvenile foliage exposed to +350 μmol mol?1 CO2 had a higher rate of increase of Asat between late summer and early autumn. This would lead to a greater potential for recharging carbohydrate reserves for winter. Mature foliage was affected by COsat, water and nutrient treatments in two ways. First, Asat was significantly increased as a result of elevated CO2 in January, a period when stomatal conductance was only 47% of the maximum observed rate. Secondly, the rate of increase of Asat from winter to early spring was accelerated as a result of both nutrient + water and + 350 μmol mol?1 CO2 treatments. This accelerated response resulted in a greater potential for photosynthate production during the period when growth initiation occurred. Nutrient, water or carbon dioxide treatments did not significantly alter trends in gsat for mature or juvenile foliage. A significant nutrition × CO2 interaction was observed for the mature foliage, suggesting that gsat increased with increasing CO2 and nutrition. These results may have important consequences for the determination of the water use efficiency of loblolly pine. In spite of low gsat in the winter to early spring period, there was a substantial gain in Asat attributable to elevated CO2 concentrations. 相似文献