Expression of Arabidopsis APETALA1 in tomato reduces its vegetative cycle without affecting plant production

Important agronomic traits such as fruit quality, harvesting efficiency or production largely depend on flowering time. We have analysed the effect of the overexpression of the Arabidopsis APETALA1 MADS-box gene on vegetative and reproductive growth of tomato. Constitutive expression of APETALA1 in tomato plants has major effects on the length of their growth cycle as well as on their growth habit. Transgenic tomato plants initiated flowering after the production of 6 vegetative nodes as compared to 11 nodes for the wild type plants. Most of tomato 35S:AP1 plants also showed determinate growth habit, similar to the phenotype of self pruning tomato mutants, as well as an initial reduction of their axillary growth. Moreover, development and fertility of flowers were not affected in plants expressing AP1. Consequently, fruit formation in transgenic plants grown under greenhouse conditions occurred normally, which permitted a similar fruit yield compared to control plants. Since traits conferred by AP1 expression are dominant, its expression in tomato breeding lines could provide advantages for the development of new hybrid varieties with shorter generation time, determinate growth, and reduced pruning requirements.     

中华真地鳖低龄若虫消化道结构及取食习性

解剖喂食不同饲料中华真地鳖EupolyphagasinensisWalker的低龄若虫 ,结果表明 ,低龄若虫消化道与成虫消化道结构相同 ,具有胃盲囊和马氏管 ;嗉囊、中肠和后肠分别占消化道总长的比率与中龄若虫相同 ,具有消化食物的能力。观察消化道各部分的滞留物变化情况 ,发现 1龄若虫取食了饲养土中的腐殖质和配合饲料 ,表明孵化后的若虫需要喂食以满足营养需要。     

新疆塔里木河下游生态输水与胡杨叶片的生理及形态响应

选择塔里木河下游3个典型断面的15个研究样地,分析和测定了塔里木河下游2000￣2002年生态输水前后不同研究样地的地下水位、地下水含盐量和胡杨(Populus　euphratica　Oliv.)叶片中脯氨酸、可溶性糖、植物内源激素脱落酸和细胞分裂素的含量以及胡杨叶片的形态结构变化,研究了塔里木河下游主要建群种胡杨对生态输水的生理与形态的响应和适应性。结果表明,塔里木河下游胡杨生长已受到不同程度的干旱胁迫;输水后各样地地下水位均有所上升,胡杨对浅层地下水位的变化表现出明显响应,胡杨受到的生理胁迫降低,胡杨叶片角质层厚度、维管束导管官腔直径及管壁厚度皆随地下水位的上升而减少;随着地下水位的上升,地下水含盐量分别提高1.76　￣　2.47倍,输水效果由于盐对植物的生理胁迫作用的增加而有所减弱;在塔里木河下游极端干旱环境下,胡杨林保育恢复的合适地下水位埋深为3.15　￣　4.12　m,地下水含盐量为67.15　￣　72.65　mm。     

长江口两种重要石首鱼类的摄食习性

通过对2006年夏、秋季在长江口及其毗邻海域采集的575尾白姑鱼(Argyrosomus argentatus)和1089尾小黄鱼(Pseudosciaena polyactis)胃含物样品的分析,利用多元统计分析方法,研究了它们的摄食习性以及随栖息地、季节和体长的变化规律。结果表明:该水域的白姑鱼是底栖动物食性,小黄鱼是混合动物食性,甲壳类在它们食物中均占83%以上的比例,2种石首鱼类的食物重叠系数为0.55。由于摄食的优势饵料种类的差异,使这2种石首鱼类之间不存在严重的食物竞争。与20世纪80年代的研究结果相比,两种石首鱼类所摄食的鱼类的比例均有所下降。结果还表明:白姑鱼的摄食习性较为稳定,受栖息环境、季节以及体长变化的影响较小;而小黄鱼随栖息环境、季节以及体长的变化较大,且109mm是其发生食性转换的一个关键的临界体长。     

中国林蛙蝌蚪的食性

本文对河北产中国林蛙蝌蚪的食性进行了系列的试验分析,是对其人工养殖不同发育阶段的饵料配方进行科学探索的一部分。结果表明：不同种类的单一饵料对蝌蚪的生长发育产生不同影响;蝌蚪不同发育时期对饵料趋向性不同;一定比例的人工合成饵料适宜蝌蚪期饲喂。     

北京房山大足鼠耳蝠食鱼性及回声定位信号

大足鼠耳蝠 (Myotisricketti)具有食鱼蝙蝠的形态特征 ,但食鱼习性待考。以北京房山种群为对象 ,夜间在洞口悬挂雾网 ,捕获取食返洞大足鼠耳蝠共 18只 ,胃检发现 7例全为鱼类 (宽鳍 ,鲫鱼和洛氏 ) ,10例以鱼类为主 ,仅 1例全为昆虫。室内实验观察到捕鱼行为 2 5 6次 ,成功率 12 5 %。如此 ,该种具食鱼习性的猜测得到证实。回声定位信号属调频型 ,扫频范围从 6 7 4 0kHz到 2 3 6 3kHz ,主频 (38 2 1± 1 18)kHz ,声信号时程 (2 5 8± 0 34)ms。这些特征具有一定的物种特异性     

Early life history of a seahorse, Hippocampus mohnikei, in Tokyo Bay, Japan

The early morphological development, seasonal and spatial occurrence patterns, and food habits of a seahorse, Hippocampus mohnikei, in offshore waters of Tokyo Bay, central Japan, were studied on the basis of 206 juvenile and young specimens (6.0–65.3 mm TL) collected between August 1995 and January 1999. All the specimens were collected within the period from May to January, inclusive, each year. In the least developed specimen (6.0 mm TL), the number of dorsal, anal, and pectoral fin rays had attained the adult complement, whereas the minute caudal fin, consisting of two rays, was present in juveniles of 6.0–26.4 mm TL. Hippocampus mohnikei≧35 mm TL, being larger than settlement size (ca. 30 mm TL), had very low gut fullness index values (GFI = 0, >70% of specimens), whereas those of 15–29 mm TL had higher values (GFI = 2–4, >80% of specimens). In addition, larger individuals selectively fed on larger planktonic animals (species of Brachyura), which occurred naturally at low densities, although smaller food items, such as Oithona davisae and Penilia avirostris, occurred abundantly, being consumed by smaller H. mohnikei individuals (15–34 mm TL). These results indicated that food availability for H. mohnikei in offshore waters of Tokyo Bay is significant for individuals larger than settlement size, because their food preference would shift from smaller food items to larger food items, which would be scarce in their environments. Received: January 12, 2001 / Revised: May 13, 2001 / Accepted: June 14, 2001     

Yield stability of determinate and indeterminate dry bean cultivars

Summary Yield stability of determinate and indeterminate dry bean (Phaseolus vulgaris L.) cultivars was compared using regression of genotypic performance on environmental means. Yields of 28 dry bean cultivars differing in plant growth habit and commercial class designation were obtained from 42 Michigan performance nurseries over the 6 year period 1980 to 1985. The determinate type I large-seeded kidney and cranberry bean cultivars had below-average seed yield and large mean square deviations from regression. Lower yielding determinate small-seeded navy cultivars had low deviation mean square values, while higher yielding determinate navy cultivars had correspondingly higher mean square deviations from regression. Although seed yield of cultivars with an indeterminate growth habit was greater than determinate cultivars, prostrate type III indeterminate cultivars had deviation mean square values equivalent to those of large-seeded determinate cultivars. The erect, short vine type II indeterminate cultivars (architypes) had greater than average seed yields and minimum deviations from regression. Compared with other plant types, the architype group showed a greater yield response to more productive environments, with regression coefficient values significantly greater than unity. These results indicate that the type II growth habit offers the breeder the best opportunity of obtaining greater seed yield without incurring loss of yield stability as occurs with the type I and type III growth habits. Since the dry bean cultivars utilized in this study represent two distinct centers of domestication, the regression analysis suggests that cultivars from the predominant genetic center demonstrate more yield stability. A non-significant rank correlation coefficient between the combined and separate analyses for deviation mean square values of large-seeded cultivars implies that commercial dry bean classes should be compared separately based on center of domestication.Contributions from Michigan Bean Commission, Michigan Bean Shippers Assoc. and Michigan Agric. Exp. Sta., Michigan Agric. Exp. Sta. Journal Article No. 11986     

兰州北山三种蜥蜴春季食性分析

兰州地区密点麻蜥、丽斑麻蜥和草原沙蜥的春季食物均为动物食物。无论在栖息地重叠地区还是非重叠地区,三种蜥蜴的食物种类在种间均无显著差异（Ｆ＝０．８６１,ｄｆＴ＝２,ｄｆＥ＝３６,Ｐ〉０．０５）。种内不同性别和年龄食性无显著差异。     

Influence of supplemental ultraviolet-B on indoleacetic acid and calmodulin in the leaves of rice (Oryza sativa L.)

IR68 and Dular rice cultivars were grown under ambient, 13.0 (simulating 20% ozone depletion) and 19.1 (simulating 40% ozone depletion) kJ m^-2 day^-1 of biologically effective ultraviolet-B (UV-B_BE) for 4 weeks. Plant height and leaf area were significantly reduced by supplemental UV-B_BE radiation. Greater reduction in leaf area than of plant height was observed. A decrease in indole-3-acetic acid (IAA) content and increase in peroxidase and IAA oxidase activities of UV-B treated plants in both cultivars were observed compared with ambient control. Calmodulin content also decreased after plants were treated with high supplemental UV-B for two weeks and medium UV-B treatment for four weeks. The results indicated that peroxidase and IAA oxidase activities in rice leaves were stimulated by supplemental UV-B, resulting in the destruction of IAA which in turn may cause inhibition of rice leaf growth. Although the mechanism is unclear, calmodulin is most likely involved in leaf growth.