Identification of RFLP markers linked with heading date and its heterosis in hexaploid wheat

Recombinant inbred lines (RILs) from a cross between hexaploid wheat (T. aestivum cv. Chinese Spring (CS) and T. spelta (Sp)) were used for RFLP analysis of heading date and heterosis. Fourteen RFLP markers linking with heading date were identified; two were localized on chromosome 1A, one on 2A, three on 2B, one on 2D, four on 5A, two on 7A and one unlinked but reported to be on group 2. All of these markers may be attributable to genes for earliness per se. However, the markers in the chromosomes of 1A and 7A are new to this study. RILs were crossed with (tim)-CS, the alloplasmic CS with T. timopheevi cytoplasm, and the heterosis from earlier-parent and mid-parents were calculated for the F₁s to examine the heterotic effect toward earliness on heading date. Five and two RFLP markers were associated with heterosis from the earlier-parent and mid-parents, respectively. They were distributed on the chromosomes of homoeologous groups 1 and 2. This revised version was published online in July 2006 with corrections to the Cover Date.     

Environmental influences on melatonin secretion in Atlantic cod (Gadus morhua L.) and their relevance to commercial culture

This study investigated the effects of photoperiod and temperature on plasma melatonin secretion in Atlantic cod (Gadus morhua L.). Initial work confirmed the presence of a diel profile of melatonin synthesis, with elevated levels during the dark phase. Unusually for fish, the peak in plasma melatonin occurred towards the end of the dark phase, which is indicative of a type `A' melatonin profile. When exposed to 60 hours of continuous darkness a clear endogenous rhythm of melatonin synthesis was observed, which continued for 4 cycles with a periodicity which, approximated to 24 h. When acclimated to varying temperatures (4, 8, 12 or 16 °C) no variation in melatonin production was seen, however, body size appeared to be an important influence, with the smallest fish exhibiting significantly higher levels of dark phase melatonin. Finally, the application of additional night-time illumination to cod maintained in sea cages i.e. without blackout, did not significantly reduce dark phase plasma melatonin, suggesting that cod are less sensitive to photoperiod manipulation in cages than salmonids.     

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.     

烟蚜茧蜂Aphidius gifuensis滞育诱导研究

研究了不同温度、光周期以及温光组合条件对烟蚜茧蜂滞育诱导的效果。结果表明,僵蚜形成前,各种温度、光周期及温光组合条件均著的作用。僵蚜形成后,低温可大量诱导产生滞育,０℃处理３０ｄ,６０％以上个体进入滞育,而光周期的诱导作用仍不明显。作者认为你温是引起烟蚜茧蜂滞育的主要因素,处理的敏感时期为老熟幼虫－预肾期。滞育虫态为肾。     

甘蔗光周期诱导开花和杂交利用研究

本文报道了１９９８年度云南省甘蔗研究所光周期诱导甘蔗开花及杂交利用结果。本研究以４月１日和６月１日两种起始处理时间,１２ｈ２５ｍｉｎ和１２ｈ１５ｍｉｎ两种固定日长处理,于１０月１日起日递减光３０ｓ至抽穗时止的光周期诱导技术分别对７个难花亲本和７个常用亲本进行了开花诱导。结果表明：在不同的光周期处理下,粤糖５７／４２３、Ｃｏ４１９、闽糖７０／６１１、罗汉蔗等４个难花亲本被诱导开花;７个常用亲本全部孕穗或开花,并提早花期３－４个月。利用诱导开花亲本分别与割手密（Ｓ．ｓｐｏｎｔａｎｅｕｍ）、斑茅（Ｓ．ａｒｕｎｄｉｎａｃｅｕｍ）、滇蔗茅（Ｅ．ｒｏｃｋｉ）、芒（Ｍ．ｓｉｎｅｎｓｉｓ）、河八王（Ｎ．ｐｏｒｐｈｙｒｏｃｏｍａ）等野生种成功地进行杂交或远缘杂交,获得大量实出苗,为野生资源的利用及优良品种的选育奠定了基础。     

Diel Rhythms of Serum Metabolites and Thyroid Hormones in Red Porgy Held in Different Photoperiod Regimes

Diel rhythms in serum glucose, lactate, cholesterol, triglycerides and thyroid hormones were studied in red porgy, Pagrus pagrus, held under different photoperiod regimes (constant darkness – DD, 8L:16D,12L:12D), at a constant temperature (17.1–18.7 °C) and fed with commercial pellets, by means of a self-feeder. A clear diurnal rhythm in feeding activity, regardless of the photoperiod regime was demonstrated. All serum components showed significant diel rhythms, although they were not necessarily consistent or circadian in periodicity. As well as this, differences in the average values among the varying treatments were observed. Fish held under the 12L:12D protocol displayed significantly higher average T₄, T₃ and lactate levels during the day rather than at night. Maximum glucose values occurred 8–12 h after dawn and maximum lactate concentrations at 06:00 or 14:00 h. Diel variations in cholesterol were evident only in the DD group with peak values inversely correlated with the rhythm of food intake. Triglycerides displayed a similar pattern of changes. Significant diel fluctuations in T₄ serum levels were observed only in fish exposed to the 12L:12D protocol, with peak values at dawn. A clear diurnal peak (10:00 h) in T₃ concentrations was observed in fish subjected to the 12L:12D regime, while fish exposed to the 8L:16D protocol showed two peaks: one in the photophase (10:00 h) and another in the scotophase (02:00 h). The light–dark alternation and the general activity rhythm of fish seem to be the main synchronizers of the diel rhythms observed in this study.     

水温和光照对牙鲆亲鱼性腺成熟和产卵的影响

报道了不同水温和光照时间对牙鲆亲鱼性腺成熟和产卵的影响。通过提高水温和延长光照时间,可促使亲鱼提前1～5个月成熟和产卵,并得出促熟培育与光照时间和水温的相关方程式     

饥饿和光照对鳙仔鱼耳石沉积和日轮形成的影响

用同１尾雌鱼催产孵出的鳙鱼仔鱼进行了饥饿、光照对耳石沉积和日轮形成影响的实验研究。结果表明,仔鱼全长生长饥饿组慢于对照组,差异极显,ＤＤ组、ＬＬ组与对照组相接近,无显差异。耳石直径各实验组与对照组无显差异。饥饿组仔鱼在体长生长停止的情况下耳石仍能继续沉积。仔鱼孵出后第２ｄ形成第１轮,之后每天１轮,对照组１６日龄仔鱼耳石上有１５个日轮。饥饿组约９０％的个体烽比对照组少２０％,约１０％的个体耳石     

光敏核不育水稻研究利用中存在的若干问题

概述了近年来我国在光敏核不育水稻的理论与应用方面存在的一些问题,对这些问题作了分析与探讨,认为光敏雄性不育现象是一种复杂的光温、生理、生态现象,其生表达虽然主要受光温的双重影响,但学与多种因素有关,其具体和机理仍不清楚。要达到更好地遗传工具来人人类服务,还需做大量工作。     

Production and testing of plants regenerated from protoplasts of photoperiod sensitive genic male sterile rice (Oryza sativa L.)

Plants were regenerated from protoplasts isolated from embryonic suspension cultures of N5047S, a photoperiod sensitive genic male sterile (PGMS) Japonica rice line. Flow cytometric analyses of nuclear DNA content identified some tetraploid regenerates whose agronomic traits could be distinguished from diploid regenerates. Pollen and female fertility of diploid protoplast-derived clones grown under different light and temperature conditions was compared. A promising PGMS protoplast clone, ZAU11S, was developed from these clones. Its male sterility was confirmed as a photoperiod × temperature interaction type. This revised version was published online in July 2006 with corrections to the Cover Date.