RELATION OF PLASTOCHRON TO ANATOMY AND GROWTH IN THE SHOOT APEX OF CHRYSANTHEMUM

The relation between plastochron stage, apical anatomy, and thymidine-C¹⁴ incorporation was studied in the shoot apex of Chrysanthemum morifolium ‘Albatross.’ Apices were sorted into early, middle, and late plastochron stage under a dissecting microscope, fixed, and sectioned longitudinally so that median sections included known sectors of the apical flank. Study of these sections revealed no discernible difference between apices in early, middle, or late plastochron with respect to regularity of cell pattern, presence of a cambium-like zone, appearance of the second tunica layer or staining pattern with pyronin or with toluidine blue. Likewise, apices that had been treated with thymidine-C¹⁴ for 2-4 hr showed no differences between the three stages in number or distribution of labeled cells.     

THE MISSING PETAL CHARACTER IN OENOTHERA AND ITS RELATION TO THE CRUCIATE CHARACTER

Two characters are known in Oenothera which show inconstancy of behavior resulting in phenotypic mosaicism. These are absence of petals mp and cruciate petals cr. The latter character has been studied intensively by Oehlkers and Renner. The former is discussed here for the first time. The missing petal character exhibits mosaicism in essentially all cases. Flowers with four, three, two, one, or no petals may appear on the same plant on the same day. Where petals are present, they occupy normal positions and are usually normal in size and shape; where absent, no primordia are produced. It is suggested that the cr character is not based on a highly mutable locus (Oehlkers) or on one in which gene conversion occurs (Renner), but is the result of a mutant gene at a locus basic to the development of sepals which is. capable, under certain conditions, of functioning not only in the sepals, but also in cells of petal primordia, thereby suppressing genes for petal development. The sepaloid tissue which it produces in the petal is much more complex than, the petaloid tissue which it suppresses. The mp locus is basic to the initiation of petals; mp is a mutant gene with reduced potency. Whether it is able to function depends upon the cellular environment in which it finds itself. In both cases mosaicism is the result, not of frequently recurring alteration in genic structure, but of regulation of gene action based on variations in the cellular milieu.     

冬小麦春化过程中可溶性蛋白质组成的变化与形态发生的关系

冬小麦“农大139”经40天左右的春化处理才能迅速而整齐地抽穗,但经14—21天低温处理,已经具有在夏季抽穗的可能性,虽然抽穗推迟且极不整齐;再将春化时间延长,则抽穗百分比增加,且从播种到抽穗的时间缩短。这表明,春化过程中低温对发育的作用有两种效应:前期低温是诱发生理状态的转变,后期低温则只具有加速发育的作用,两个时期的转变是在春化的中期。蛋白质合成抑制剂乙基硫氨酸和对-氟苯丙氨酸能抑制冬小麦的春化,抑制时期也是在春化过程的中期。不同时间低温处理后冬小麦幼芽中可溶性蛋白质含量及组成发生了变化,春化过程中期(低温处理14天之后)不仅含量比对照增加了一倍,而且有新的蛋白质谱带出现。春麦中无类似现象,未经低温处理的春麦已含有冬麦中新出现的谱带。说明冬小麦春化过程的第14—21天左右是与春化过程有关的蛋白质合成的关键时期,该时期新合成的蛋白质与植株的发育状态之间存在着密切的相关关系。     

REGULATION OF THE HYDROGEN ION CONCENTRATION AND ITS RELATION TO METABOLISM AND RESPIRATION IN THE STARFISH

The normal reaction of the cœlomic fluid in Patiria miniata and Asterias ochraceus is pH 7.6, and of the cæca, 6.7, compared with sea water at 8.3, all without salt error correction. A medium at pH 6.7–7.0 is optimum for the cæca for ciliary survival and digestion of protein, and is maintained by carbon dioxide production. The optimum pH found for carbon dioxide production is a true one for the effect of hydrogen ion concentration on the tissue. It does not represent an elimination gradient for carbon dioxide. Because the normal excised cæca maintain a definite hydrogen ion concentration and change their internal environment toward that as an optimum during life, there exists a regulatory process which is an important vital function.     

THE AUTODESTRUCTION OF PEPSIN IN RELATION TO ITS IONIZATION

1. Evidence is presented that pepsin is a univalent acid with a value for pK of 6.85 (or a base, with pK 7.39). 2. The autodestruction of the pepsin is shown to be dependent in part upon an instantaneous irreversible change occurring in the ionized form of the enzyme (if it be an acid) or in the unionized form (if it be a base). 3. A further progressive autodestruction of pepsin at any given hydrogen ion concentration and temperature is defined by the mass law equation for a monomolecular reaction 4. The velocity of autodestruction of pepsin is directly proportional to the hydroxyl ion concentration. It is much less in the range of hydroxyl ion concentration from pOH 9.89-7.7, than in the range greater than pOH 7.7. In both of these ranges variations in pK with pOH may be represented by straight lines.     

加压素对记忆的影响及其与海马中去甲肾上腺素和多巴胺的关系

采用海马内注射方法,探讨了精氨酸加压素对大鼠穿梭箱条件回避行为的影响及其与海马中去甲肾上腺素能末梢递质的关系;用高效液相色谱-电化学检测法研究了精氨酸加压素对海马中单胺类递质及其代谢产物含量的影响。结果显示:(1)两侧海马内注射精氨酸加压素(各50pg),可延缓动物条件回避行为的消退;(2)用6-羟多巴胺(各10μg)损毁两侧海马中的去甲肾上腺素能末梢,可阻断精氨酸加压素的促记忆效应;(3)精氨酸加压素可加速海马中去甲肾上腺素和多巴胺的消失。上述结果提示,加压素对记忆的易化作用,至少部分通过海马起作用;海马内的去甲肾上腺素能末梢可能参与加压素对记忆过程的调节;加压素的作用很可能是通过加强脑内去甲肾上腺素的降解代谢来实现的。     

安宁河中游底栖动物群落结构及其与环境因子的关系

为了解安宁河底栖动物群落结构及其影响因素, 分别于丰水期(2015年7、8月)和枯水期(2016年1、2月)开展了安宁河中游干支流底栖动物的2次调查, 并于2015年7月至2016年6月进行安宁河支流的周年调查。共检出底栖动物5门115属122种, 其中水生昆虫居多(109种)。干流丰、枯水期底栖动物的密度和生物量都明显低于支流, 丰水期干支流底栖动物的密度和生物量都明显低于枯水期。安宁河支流全年优势种为四节蜉(Baetis sp.)、蚋(Simulium sp.)、高翔蜉(Epeorus sp.)、花翅蜉(Baetiella sp.)、扁襀(Peltoperlidae spp.)和小蜉(Ephemerella sp.)。安宁河支流底栖动物密度以12月最高, 7月最低; 生物量以1月最高, 7月最低。典范对应分析(CCA)分析结果显示, 影响丰水期安宁河底栖动物分布的关键环境因子为底质类型和海拔, 影响枯水期底栖动物分布的主要环境因子为流速、海拔和水温; 影响安宁河支流底栖动物群落结构周年变化的主要环境因子为水温与电导。研究为高海拔地区河流生物多样性研究和保护提供科学参考。     

ADVENTIVE EMBRYOGENESIS IN CITRUS AND ITS RELATION TO POLLINATION AND FERTILIZATION

Cytological and histological studies of seeds from three facultative apomictic Citrus cultivars show that adventive embryos develop, as a rule, from the first few cell layers of the nucellus adjacent to the embryo sac in the micropylar half and occasionally from the chalazal end. The adventive embryos initiated in nucellar tissue away from the embryo sac and most of those initiated from the chalazal end of the nucellus do not develop beyond the one-celled stage. When two or more embryos are developing in the same seed, the successful development of a given embryo depends on its location in relation to access to nutrients from the endosperm. The presence of a zygote and triploid endosperm in seeds with adventive embryos, the abortion of seed when endosperm degenerates, and the lack of seed set without pollination indicate that pollination and fertilization are essential for in vivo adventive embryogenesis.