Migrating songbirds recalibrate their magnetic compass daily from twilight cues

Night migratory songbirds can use stars, sun, geomagnetic field, and polarized light for orientation when tested in captivity. We studied the interaction of magnetic, stellar, and twilight orientation cues in free-flying songbirds. We exposed Catharus thrushes to eastward-turned magnetic fields during the twilight period before takeoff and then followed them for up to 1100 kilometers. Instead of heading north, experimental birds flew westward. On subsequent nights, the same individuals migrated northward again. We suggest that birds orient with a magnetic compass calibrated daily from twilight cues. This could explain how birds cross the magnetic equator and deal with declination.     

紫外线照射对黄曲霉菌产毒影响的研究

分别用照射强度373.8 mW/cm2的总紫外线,强度为60.6 mW/cm2、波长365 nm的UVA和强度7.8 mW/cm2、波长253.7 nm的UVC对黄曲霉进行照射处理,然后在避光和光照培养两种条件下继续培养,研究了不同波长紫外线照射对黄曲霉菌产毒的影响。试验结果表明:在一定条件下,各波长的最佳抑制率分别为:UVA:53%、UVC:91%、总紫外线:100%;而且在紫外照射强度相同的条件下,避光培养表现出的抑制作用强于光下培养,可能与光修复有关。     

Lizard reflectivity change and its effect on light transmission through body wall

Light transmission through the body wall of living, color-labile desert iguanas (Dipsosaurus dorsalis) was measured by spectrophotometry. In the dark phase, the body wall's absorption of ultraviolet light and visible light was approximately twice that of the body wall in the light phase. The shorter wavelengths of ultraviolet could penetrate the body wall in the light phase but not in the dark phase. The intensity and wavelengths of light which could penetrate the body wall without pigments are potentially mutagenic when judged by bacterial standards.     

Photoperiodically significant photoreception in sparrows: is the retina involved?

Blind house sparrows (150 birds) and normal ones (199 birds) were subjected to various photoperiodic treatments consisting of cycles of 12 hours light, 12 hours dark and 16 hours light, 8 hours dark at intensities ranging from 20 to 500 lux. The testicular, response of the blind birds was found to be indistinguishable from the response of normal birds under these conditions. The data show that a functional extraretinal photoreceptor exists in this species which is fully capable of mediating the gonadal response to photoperiodic stimuli.     

Spatial learning as an adaptation in hummingbirds

An ecological approach based on food distribution suggests that humming birds should more easily learn to visit a flower in a new location than to learn to return to a flower in a position just visited, for a food reward. Experimental results support this hypothesis as well as the general view that differences in learning within and among species represent adaptations.     

Disturbance and the dispersal of fleshy fruits

Fruits of Prunus serotina, Phytolacca americana, and Vitis vulpina were placed during separate trials in forest sites that varied in the degree to which the forest canopy was disturbed. Removal rates of fruits were consistently faster in the forest edge and light gap sites than in sites under closed canopy. Rapid removal of fruits from species that ripen fruit in summer and early fall is selectively advantageous to the plants because it minimizes the probability that fruits will be destroyed by invertebrates before dispersal. Disturbances probably play an important role in interactions between temperate fruits and birds and in community organization.     

Role of light in the photoperiodic responses of migratory birds

Light-dark cycles with 12-hour and 16-hour photoperiods are known to be effective in 24-hour cycles in inducing gonadal activity and fat deposition in migratory birds. Twenty-four-hour cycles with 16-hour dark periods are not effective. To test the role of the light periods and the dark periods in a given cycle, slate-colored juncos were subjected to light in cycles which combined stimulatory photoperiods (L) and inhibitory dark periods (D) as follows: 12L-16D; 12L-20D; 16L-16D; 16L-22D; 16L-32D. The results indicate that the photoperiod, not the dark period, determined the response.     

3种扁谷盗对不同波长光趋性研究

【目的】研究锈赤扁谷盗Cryptolestes ferrugineus成虫、土耳其扁谷盗Cryptolestes turcicus和长角扁谷盗Cryptolestes pusillus雌成虫对不同波长光的趋性。【方法】室内应用光行为反应装置测试3种扁谷盗羽化1、11、21和31日龄(雌)成虫对试验波长303、320、330、340、351、368、400、445、460、480、520、525、545、560、575和580 nm的趋光率。【结果】锈赤扁谷盗羽化1、11、21和31日龄成虫趋光率最高的刺激光波长分别为351、351、400、480 nm,对锈赤扁谷盗成虫诱集效果较好的光波长有351、400和445 nm,随着日龄的增加,对锈赤扁谷盗成虫诱集率大于20%的光波数增加;土耳其扁谷盗羽化1、11、21和31日龄趋光率分别为16%~51%、11%~46%、7%~37%和4%~28%,雌成虫趋光率最高的刺激光波长分别为351(368)、368、330和351 nm,对土耳其扁谷盗雌成虫诱集效果较好的光波长有368、351和303 nm;长角扁谷盗羽化1、11、21和31日龄趋光率分别为1.11%~75.56%、18.89%~70.00%、33.33%~62.22%和22.22%~71.11%,雌成虫趋光率最高的刺激光波长分别为575、320、400(445)和320(560)nm,对长角扁谷盗雌成虫诱集效果较好的光波长有320、575和330 nm。【结论】锈赤扁谷盗成虫的趋光性随着日龄的增加而增强,土耳其扁谷盗雌成虫的趋光性随着日龄的增加而下降,长角扁谷盗雌成虫的趋光性随着日龄的增加略为下降。     

Evidence for large upward trends of ultraviolet-B radiation linked to ozone depletion

Spectral measurements of ultraviolet-B radiation made at Toronto since 1989 indicate that the intensity of light at wavelengths near 300 nanometers has increased by 35 percent per year in winter and 7 percent per year in summer. The wavelength dependence of these trends indicates that the increase is caused by the downward trend in total ozone that was measured at Toronto during the same period. The trend at wavelengths between 320 and 325 nanometers is essentially zero.     

单色光间歇性刺激胚蛋对肉仔鸡胸肉生长及肉品质的影响

【目的】采用LED（light emitting diodes）灯作为光源,探讨孵化期间歇性单色光刺激对肉仔鸡出雏后生产性能、胸肉化学成分及肉品质的影响。【方法】1 480枚爱拔益加（AA）鸡商品代受精蛋（蛋重65-70 g,平均重68 g）被随机分配到绿光组（560 nm,490枚）、蓝光组（480 nm,490枚）和黑暗组（对照组,500枚）3种不同处理的孵化器中,采用间歇光照（15 min开灯,15 min关灯）,光照强度为15 lx。肉仔鸡出壳后,从每个处理组各选取120只公雏分配到3个处理中,每个处理6个重复,每个重复20只鸡。自由采食和饮水,统一采用30 lx日光灯补光,光照时间23L﹕1D。【结果】各处理组种蛋孵化率、肉仔鸡初生重及平均采食量均无显著差异（P＞0.05）。与黑暗组和蓝光组相比,胚胎期绿光刺激可显著增加肉仔鸡21和42 d体重（P＜0.05）。42 d时,绿光组肉仔鸡的胸肌重和胸肌率均最高,分别较黑暗组提高了38.3 g和0.67%,较蓝光组提高了44.6 g和0.78%。整个生长期绿光组饲料转化率为1.81,显著优于黑暗组（1.88）和蓝光组（1.92,P＜0.05）。各组肉仔鸡42 d胸肌化学成分无显著差异（P＜0.05）。蓝光组胸肌24 h肉色b*值显著高于黑暗组和绿光组（P=0.05）,而绿光处理组胸肌滴水损失（P=0.10）和蒸煮损失（P=0.07）均较黑暗组和蓝光组有升高的趋势。【结论】孵化期15 lx间歇绿光刺激可促进肉仔鸡肌肉生长,提高胸肌产量并改善饲料转化率,对胸肌化学成分无显著影响（P＞0.05）,但绿光组肉仔鸡胸肌系水力有降低的趋势。     

Roadrunners: activity of captive individuals

Two roadrunners, Geococcyx californianus, readily accepted an activity wheel as an outlet for locomotor activity. The birds were strictly diurnal and tended to be most active per unit of time in the predusk hours. There was less activity on partly overcast days than on clear days. Dim light and darkness were strongly inhibitory, even during daytime hours; bright light was stimulatory, even during nighttime hours. These findings appear to open the way for quantitative comparative studies of the influences of environmental factors on the activity of cursorial birds.     

雏鸡法氏囊病并发鸡白痢沙门氏菌感染的诊断报告

本文对白银市白银区某村雏鸡群中发生的一种急性传染性疾病从流行病学、临诊表现、剖检变化、血清学和细菌学检查以及实验动物感染等方面进行了综合诊断。结果表明,该村雏鸡所发生的疾病系传染性法氏囊病并发鸡白痢沙门氏菌感染所致。     

Effects of different LED light wavelengths on the resistance of tomato against Botrytis cinerea and the corresponding physiological mechanisms

New types of light-emitting diode(LED) sources were applied to irradiate Botrytis cinerea mycelium and tomato leaves that were inoculated with 6.cinerea to assess the effect of different LED light wavelengths on the infection of tomato with6.cinerea,to determine the optimum light wavelengths to control 6.cinerea,and to explore the mechanism of LED influence on the development of gray mold.The results showed that purple light and blue light irradiation significantly inhibited the growth of 6.cinerea mycelium,and the inhibition rates were 22.3 and 15.16%,respectively,and purple light exhibited a better inhibitory effect than blue light.The lesion development of 6.cinerea on tomato leaves was significantly inhibited upon irradiation with red and purple light with inhibition rates of 32.08 and 36.74%,respectively.Irradiation with red light inhibited the oxidative burst of superoxide anion(O_2~-) that was caused by infection with 6.cinerea,and red light regulated the H_2O_2 content in the tomato leaf,which increased and rapidly returned to a lower level.In addition,red light irradiation improved the activity of superoxide dismutase(SOD),catalase(CAT) and peroxidase(POD) in tomato leaves.However,purple light irradiation did not make tomato leaves exhibit this kind of physiological response.Therefore,red light and purple light can suppress gray mold in tomatoes,but the disease suppression mechanisms of these two types of LED light are different.In general,red light suppresses gray mold primarily by regulating the tomato defense mechanism for disease,whereas the suppression of tomato gray mold by purple light can be partially explained by the photo-inhibition of 6.cinerea.     

Behavioral response rates in pigeons: effect of alpha-methyl-m-tyrosine

An intramuscular injection of alpha-methyl-m-tyrosine ( 100 mg/ kg), which differentially depletes serotonin and norepinephrine in both brain and heart, was given to two groups of pigeons trained to peck at a key for food. The first group received an injection 12 hours before the daily session and showed no behavioral effect. Response rates of birds in the second group, which were injected 30 minutes after the start of the daily session, decreased and returned to normal within 9 hours after injection. Preliminary data on brain serotonin of pigeons indicate that the disruption of the behavior follows the same time course as the change in serotonin.     

Robust fitting of fluorescence spectra for pre-symptomatic wheat leaf rust detection with Support Vector Machines

Early recognition of pathogen infection is of great relevance in precision plant protection. Pre-symptomatic disease detection is of particular interest. By use of a laserfluoroscope, UV-light induced fluorescence data were collected from healthy and with leaf rust inoculated wheat leaves of the susceptible cultivar Ritmo 2-4 days after inoculation under controlled conditions. In order to evaluate pathogen impact on fluorescence spectra 215 wavelengths in the range of 370-800 nm were recorded. The medians of fluorescence signatures suggest that inoculated leaves may be separated from healthy ones, but high-frequency oscillations and individual reactions of leaves indicate that separability is difficult to achieve. The misbalance between the high number of measured wavelengths and the low number of training examples induces a high overfitting risk. For a pre-symptomatic pathogen identification a small number of robust features was desired which comprise most of the information relevant for the given classification task. Instead of choosing only the most relevant wavelengths, the coefficients of polynomials fitting the spectra were used for classification. They specify the global curve characteristics. Piecewise fitting by polynomials of fourth order led to high classification accuracy. Support Vector Machines were used for classification. Cross validation demonstrated that the achieved classification accuracy reached 93%. This result could be attained on the second day after inoculation, before any visible symptoms appeared. The described method is of general interest for pre-symptomatic pathogen detection based on fluorescence spectra.     

保定市郊鸟历

历时５年调查研究，共记录了保定西南郊鸟类２０２种，发现时间和居留期间，分别列于１２个月份中，作为此区域的鸟历。经过统计，有夏候鸟５１种，冬候鸟１３种，旅鸟１１９种，留鸟１９种。候鸟中有中日候鸟保护协定（２２７种）中的鸟９０种。有国家级重点保护鸟３０种，河北省级重点保护鸟１１种，３方面重点保护鸟类共１２２种（因有９种鸟为双重保护），占保定市鸟类６０．４％，因而这里分布的鸟类资源有较高的价值。４月中旬至５月中旬为鸟类种数的高峰期，是保护鸟类的重要时期，从区系方面统计，２０２种鸟分属于１７个日、５０个科，为河北省鸟类（４０５种）４９．９％。     

通过LED集鱼灯光效标准确定最佳光色

为了衡量不同波长光源引诱鱼类的效率,建立了集鱼灯光效标准,引入诱鱼光作用有效率概念,它等于光源对鱼眼起刺激作用的能量与光源辐射能量的比值,收集目前海洋捕捞4种经济鱼类的生物学光谱功率值,与不同波长单色LED光谱功率值进行拟合,得到对不同种类鱼类的最佳光谱LED。     

添加嗜酸性乳酸杆菌对肉仔鸡免疫功能影响的研究

本文对肉鸡饲喂嗜酸乳酸杆菌时,鸡的体重及免疫器官及功能的影响进行了研究。结果表明:饲喂嗜酸乳酸杆菌可以提高鸡的体重,增加胸腺、法氏囊、脾脏的重量及淋巴细胞的 E-玫瑰花环率。     

Variation of enhancement of photosynthesis with conditions of algal growth

The Emerson effect was observed as an enhancement of photosynthesis in long-wavelength red light when beams of shorter wavelength were added. Two light beams of wavelengths 650 and 694 mmicro, respectively, when presented together, gave a photosynthetic rate higher than the sum of the rates obtained separately. The amount of enhancement of photosynthesis depends upon the growth conditions of algal cells, and specifically on their phosphate metabolism.     

Pineal function: the biological clock in the sparrow?

The pineal organ of the house sparrow, Passer domesticus, is essential for persistence of the circadian locomotor rhythm in constant conditions. Upon removal of the pineal body, activity becomes arrhythmic. However, pinealectomy does not abolish the rhythm of locomotor activity in birds exposed to light-dark cycles. Pinealectomized birds are entrained by light cycles in much the same manner as are normal birds. Our data demonstrate that the pineal organ is a crucial component of the endogenous time-measuring system of the sparrow.