光照和褪黑激素对内蒙古绒山羊氮分配的影响

从氮分配的角度研究了光照和褪黑激素对内蒙古白绒山羊营养分配的影响。结果表明:光照时间和埋植褪黑激素显著影响绒山羊体内氮物质分配,短光照或埋植褪黑激素显著提高绒山羊血液中的褪黑激素水平,并使其他相关激素如催乳素(PRL)、胰岛素(INS)、类胰岛素生长因子-I(IGF-I)、瘦素(LEP)的含量发生显著变化,结果使毛绒氮的沉积增加,体氮的沉积减少。短光照条件下毛绒氮和体氮的沉积分别为33.7%±0.64%和66.3%±0.64%;而长光照条件下则减少毛绒氮的分配量,增加体氮分配量,毛绒氮和体氮的沉积分别为23.6%±0.46%和76.4%±0.46%。短光照和褪黑激素之间有强烈的互作效应,短光照埋植褪黑激素组毛绒氮和体氮的分配比例分别为36.1%±0.79%和63.9%±0.79%。试验期绒山羊的产绒量平均增加(338.83±72)g,比普通绒山羊提高73.86%,新生羊绒的品质符合纺织工业标准的要求。     

温度及光周期对日本食蚧蚜小蜂发育与繁殖的影响

为明确温度、光周期对日本食蚧蚜小蜂Coccophagus japonicus Compere发育与繁殖的影响,在不同温度、光周期条件下观察日本食蚧蚜小蜂的发育历期、出蜂数、雌蜂寿命以及寄生率。结果表明：温度和光周期显著影响日本食蚧蚜小蜂种群增长。在18~30℃之间,日本食蚧蚜小蜂的发育历期及雌蜂寿命均随温度的升高而缩短,18℃时发育历期与雌蜂寿命最长,分别为60.9 d和29.9 d,30℃时发育历期最短,为21.3 d,33℃时雌蜂寿命最短,为8.3 d;18~24℃之间,寄生率及出蜂数随温度的升高而增加,24℃时最高,分别为77.1%和38.7头;24~30℃之间,随温度升高日本食蚜小蜂的寄生率及出蜂数呈下降趋势。在光周期L 8 h∶D 16 h~L 16 h∶D 8 h范围内,当光周期为L 12 h∶D 12 h时,日本食蚧蚜小蜂的发育历期最短,为22.1 d,出蜂数最高,为39.0头;当光周期为L 14 h∶D 10 h时,雌蜂寿命最长,为22.6 d,寄生率最高,为71.1%。表明温度24~27℃、光周期L 12 h∶D 12 h为日本食蚧蚜小蜂种群增长的最适温度和光周期条件。     

光周期与氮肥互作对华农1号青饲玉米碳氮代谢相关酶的影响

于2005年3-7月,采用盆栽试验,设置3个不同光照长度处理和氮素水平,研究了不同光照时数及氮素水平对远缘玉米杂交种华农1号青饲玉米碳氮代谢相关酶活性的影响.结果表明,在苗期,16 h光照处理下植株叶片磷酸烯醇式丙酮酸羧化酶、蔗糖磷酸合成酶、蔗糖合成酶、谷氨酰胺合成酶和硝酸还原酶等酶的活性显著低于13和10 h光照处理;至抽雄期和收获期,13和10 h处理下植株叶片各种酶的活性下降速率较快,而16 h处理下酶活性下降缓慢且显著高于13和10 h处理.在抽雄期或收获期,16 h处理下叶片各种酶的活性均随施氮量的增加而增加,但在13和10 h处理下均有几种酶的活性在高氮素水平下出现下降的趋势.总的看来,在16 h光照处理下,植株苗期碳氮代谢相对较弱,到中后期代谢能力明显提高,且耐高氮能力也较强,收获期植株叶片酶的活性显著高于13和10 h处理.     

温度和光周期对管侧沟茧蜂寄生草地贪夜蛾效果的影响

草地贪夜蛾Spodoptera frugiperda是世界重大农业害虫,前期研究发现管侧沟茧蜂Microplitistuberculfer能够有效控制草地贪夜蛾.为了进一步优化控害效果、评估寄生适应性,本研究比较了温度和光周期对管侧沟茧蜂寄生草地贪夜蛾效果及子代蜂发育的影响.结果表明:在光周期10L∶14D和14L∶1...     

The effect of photoperiod and melatonin on plasma prolactin concentrations in female guanaco (Lama guanicoe) in captivity

The present study examined the effects of different photoperiods and melatonin treatment on plasma prolactin concentrations in guanacos, a South American camelid, in captivity. Fourteen adult female guanacos, not gestating or lactating and isolated from males, were studied. The control group was exposed to natural daylight, during short days (N = 7, 10L:14D) and long days (N = 7, 16L:8D). The treatment group (N = 7, 10L:14D) received melatonin implants every 23 days for 6 weeks during long days. Blood samples were taken at intervals of 1 week for 3 weeks, starting the third week of treatment. Prolactin concentrations were measured using competitive ELISA. Plasma concentrations of prolactin in non-lactating female guanacos have seasonal changes, with a higher concentration (p < .001) in short days (3.50 ± 2.24 ng/ml) than long days (1.10 ± 0.91 ng/ml). Melatonin treatment significantly decreases (p < .05) plasma concentrations of prolactin on the 21st day after the treatment. These findings are the first report of an endogenous circannual rhythm of plasma prolactin concentration and the action of melatonin treatment on prolactin secretion in this wild camelid.     

粳型光敏核不育系与常规粳稻杂交后代育性的遗传分析

在分析粳型光敏核不育系与粳稻品种杂交组合F_3及以后世代部分株系的育性和基因型的基础上,对分离世代各种主基因型的育性及频率分布进行了估计,验证了根据F_1、F_2和BF_1代作出的水稻光敏核不育性及其育性恢复的遗传涉及核内2对独立的主基因的遗传结论。由F_6以上高世代株系中测选出对农垦58s恢复效应有明显差异的两种纯合单显性可育株系,获得了存在两个不同恢复基因的遗传证据。     

早籼型水稻温敏核不育系M103S的选育与光温反应特性

以温敏核不育水稻安农S—1为母本，以常规高产早籼稻品系92153为父本进行杂交，通过低温选择和人工气候箱鉴定，育成了育性转换临界温度23—24℃的早籼型温敏核不育系M103S。光周期长于12．5h，日平均温度高于24℃，可以用于制种，日平均温度低于23℃，可以用于繁殖。光周期长于13．5h，日平均温度高于23℃，可以用于制种。自然条件下不育起点温度为日均温23—24℃，耐低温期为3—4d。敏感期为抽穗前的7—14d。播始历期为53—79d，主茎叶片数10．0—12．6片。从播种到始穗的活动积温和有效积温，分别为1493．8—1766．3℃和733．4—1058．3℃。不育期的株高63．6—77．5cm，平均72．0cm，单株有效穗6．4—12．0个，平均9．3个，穗长20．9—22．7cm，平均21．2cm，每穗颖花数112．1—137．3朵，平均122．3朵。可育期株高65．7cm，单株有效穗7．2个，穗长17．2cm，每穗总粒数114．1粒，结实率47．23％，千粒重31．34g。以M103S为母本，与100多个早籼品种进行测配，杂种表现生育期早、穗大、粒多、千粒重高。     

Effect of allele combinations at Ppd-1 loci on durum wheat grain filling at contrasting latitudes

Flowering time is the most critical developmental stage in wheat, as it determines environmental conditions during grain filling. Thirty-five spring durum genotypes carrying all known allele variants at Ppd-1 loci were evaluated in fully irrigated field experiments for three years at latitudes of 41°N (Spain), 27°N (northern Mexico) and 19°N (southern Mexico). Relationships between weight of central grains of main spikes (W) and thermal time from flowering to maturity were described by a logistic equation. Differences in flowering time between the allele combination causing the earliest (GS100/Ppd-B1a) and the latest (Ppd-A1b/Ppd-B1a) flowering were 7, 20 and 18 days in Spain, northern Mexico and southern Mexico, respectively. Flowering delay drastically reduced the mean grain filling rate (R) and W at all sites. At autumn-sowing sites, an increase of 1°C in mean temperature during the first half of the grain filling period decreased W by 5.2 mg per grain. At these sites, W was strongly dependent on R. At the spring-sowing site (southern Mexico), W depended on both R and grain filling duration. Our results suggest that incorporating the allele combinations GS100/Ppd-B1a and GS105/Ppd-B1a (alleles conferring photoperiod insensitivity) in newly released varieties can reduce the negative effects of climate change on grain filling at the studied latitudes.     

Circadian heart rate changes and light-dependence in the Mediterranean seabream Sparus aurata

Despite the abundant literature on circadian heart rate rhythms in fish, few studies have attempted to elucidate if such pattern is endogenous or if it is modulated by environmental cues. In this study, heart rates were continuously recorded in Sparus aurata acclimated to different light regimes (normal or shifted LD 12:12 cycle and a pulsed 0.75:0.75 LD cycle) to investigate the endogenous nature and the role of light on the circadian pattern of heart rate. Under LD 12:12, the daily pattern of heart rate showed higher values at night and lower rates during the day (average amplitude of the heart rate change of 10.6 ± 5.7 beats min^–1). The circadian pattern was maintained in animals under constant light but the amplitude was decreased (2.4 ± 1.1 beats min^–1). Light masks the expression of the rhythm because under a pulsed LD cycle, heart rate tracks the pulsed LD phases, increasing during the dark phase and decreasing during the light phase. Besides the ultradian pattern imposed, an underlying circadian rhythm was detected, which indicates that the rhythm is endogenous. However, the strong link between heart rate and light obtained under pulsed LD cycles suggest the timing mechanism to be mostly based on external light reception.     

Diurnal variations in hypothalamic monoamine levels in the teleostChanna punctatus (bloch) in response to melatonin under two photothermal conditions

Hypothalamic dopamine (DA), noradrenaline (NA) and 5-hydroxytryptamine (5-HT) levels exhibited marked day-night variations under ambient photoperiod and temperature (12L12D; 17±1°C) with peak values at mid-light phase. The 16L8D; 22±1°C treatment reversed the diurnal rhythm of 5-HT, but not that of DA and NA. However, there was an overall increase in the levels of the catecholamines on exposure to the long photoperiod and high temperature. The administration of melatonin in the fish held on 16L8D; 22±1°C regime restored the 5-HT rhythm to that of the 12L12D; 17±1°C control group, but with elevated mid-photophase value. However, there was no effect of the indole treatment on the 5-HT rhythm under the 12L12D; 17±1°C regime. Melatonin causes a significant reduction of NA level in both the groups, while DA level did not change in either group.