苹果果实组织脱落酸结合位点的亚细胞定位

在苹果（ＭａｌｕｓｐｕｍｉｌａＭｉｌ）果实细胞的可溶性组分中存在ＡＢＡ特异结合位点,这些位点能与ＡＢＡ形成稳定的３ＨＡＢＡ蛋白结合复合物,而微粒体部分未表现出３ＨＡＢＡ结合活性。可溶性组分对３ＨＡＢＡ的结合效率与结合稳定性需要活体组织完整细胞的存在。ＡＢＡ共价交联物ＡＢＡＬＹＣＨ,具有与ＡＢＡ相同的抑制红苋菜（ＡｍａｒａｎｔｈｕｓｔｒｉｃｏｌｏｒＬ．）种子萌发的生物活性,能有效地竞争抑制果实组织圆片对３ＨＡＢＡ的结合。通过ＡＢＡＬＹＣＨ对苹果果实组织圆片及果实组织游离细胞的荧光染色表明,未成熟果实的细胞外周被特异性地染色。在ＢＳＡ存在的情况下,ＡＢＡＬＹＣＨ复合物被转运进细胞,形成密集的强烈荧光团。结果表明,ＡＢＡＬＹＣＨ与３ＨＡＢＡ的竞争性结合发生在细胞质膜水平。     

High levels of non-methylesterified pectins and low levels of peripherally located pectins in loosely attached non-embryogenic callus of carrot

Carrot embryogenic callus (EC) forms larger and tighter clusters of cells than does non-embryogenic callus (NC). Morphological and histochemical analyses of EC and NC were made using the electron microscope. The entire cell wall in NC was strongly stained by ruthenium red, which reacts primarily with carboxyl groups of acidic sugars. By contrast, in EC, strong staining by ruthenium red of the entire cell wall, of amorphous structures on the surface of EC and of secretory vesicles was observed only after treatment with NaOH. Scanning electron microscopy revealed the presence of amorphous structures on the entire surface of EC but not of NC. These results suggest the abundance of non-methylesterified pectins and the presence of methylesterified and peripherally located pectins in the cell walls of NC and EC, respectively, as well as the absence, in carrot cultured cells, of any correlation between the calcium bridges of pectins and intercellular attachment. Received: 28 April 1998 / Revision received: 20 September 1998 / Accepted: 27 October 1998     

安徽省和县和巢县古人类地点的铀系法年代测定和研究

用不平衡铀系法测定了安徽省和县和巢县人化石地点哺乳动物骨化石样品的年代。所得封闭样品的年代值分别集中在15—19和16—20万年范围内。但在两个地点均不排除年代值为二十多万年的骨化石样品存在的可能。所有被测样品均检验了对铀的封闭性。     

Replication timing analysis in polyploid cells reveals Rif1 uses multiple mechanisms to promote underreplication in Drosophila

Regulation of DNA replication and copy number is necessary to promote genome stability and maintain cell and tissue function. DNA replication is regulated temporally in a process known as replication timing (RT). Rap1-interacting factor 1 (Rif1) is a key regulator of RT and has a critical function in copy number control in polyploid cells. Previously, we demonstrated that Rif1 functions with SUUR to inhibit replication fork progression and promote underreplication (UR) of specific genomic regions. How Rif1-dependent control of RT factors into its ability to promote UR is unknown. By applying a computational approach to measure RT in Drosophila polyploid cells, we show that SUUR and Rif1 have differential roles in controlling UR and RT. Our findings reveal that Rif1 acts to promote late replication, which is necessary for SUUR-dependent underreplication. Our work provides new insight into the process of UR and its links to RT.     

Vocalizations and other behavioral responses of male cheetahs (Acinonyx jubatus) during experimental separation and reunion trials

In this study we assessed the extent of psychological attachment between male cheetahs living in same sex pairs in zoos by recording the behavior and vocalizations of two male coalitions (siblings and nonsiblings) during four experimental separations and reunions of each coalition. Both coalitions showed higher vocalization rates and walking rates during separations than during reunions, and during separations cheetahs spent less time resting and more time vocalizing, walking, or standing than during baseline observations. Compared to the nonsibling coalition, the sibling coalition showed a significantly higher vocalization rate during separations and more affiliative behavior during reunions. The most common calls emitted during separations were chirps, followed by eeaows and stutters. The chirps showed the highest level of individual distinctiveness. Eeaows comprised a significantly higher percentage of the calls during separations for nonsiblings that for siblings. The only vocalization heard during reunion was the stutter. We hypothesize that chirps emitted during separations communicate desire to reunite, individual identity, and have a structure that facilitates locating the caller. The results of this study suggest that male cheetahs, both sibling and nonsibling, develop strong psychological attachments to each other. The separation of existing coalitions can create stressful conditions for coalition members. We suggest that raising and maintaining coalitions of male cheetahs in coalitions in zoos is a viable husbandry technique. Zoo Biol 17:1–16, 1998. © 1998 Wiley-Liss, Inc.     

洛南盆地1995-1999年野外地点发现的石制品

本文研究了1995-1999年期间在洛南盆地南洛河及其支流两侧阶地发现的50处旷野类型旧石器地点的1751件石制品.这些野外地点分布在第2级阶地者41处,第3级阶地4处,第4级阶地3处,另外还有2处分布于较高的第5级古老的阶地上.石制品的统计分析显示洛南盆地野外地点是以大中型石片和第二次加工修理的大型石片及砾石工具为代表的、两面加工技术发达的旧石器时代早期文化.     

The organization of the muscle system of the causative agent of dicrocoeliosis,Dicrocoelium dendriticum

The musculature of parasitic flatworms plays a central role in locomotory movement, attachment to the host, and in the function of the digestive, reproductive, and excretory systems. We examine for the first time the muscle system of the flatworm Dicrocoelium dendriticum, a causative agent of the parasitic disease dicrocoeliosis, by use of fluorescently labeled phalloidin and confocal laser scanning microscopy. Somatic musculature of D. dendriticum consists of the circular, longitudinal, and diagonal muscles. The distribution of the muscle fibers in the body wall differed among the anterior, middle, and posterior body regions of the worm. The musculature of the attachment organs, the oral and ventral suckers, includes several types of muscles: the external equatorial and meridional muscles, internal circular and semicircular muscles, and radial muscles. Inside of the ventral sucker the diagonally located muscles were revealed and the supplementary u-shaped muscles were found adjoined to the base of the sucker from outside. The musculature of the internal organs composed of the excretory, reproductive, and digestive systems were characterized. Our results increase our knowledge of the morphology of trematodes and the arrangement of their muscle system.     

The Role of Histidine Residues in the Non-Enzyme Covalent Attachment of Glucose and Ascorbic Acid to Protein

Copper ions have been suggested to play a role in the non-covalent glycosylation (glycation) of proteins via transition metal-catalysed oxidations. We have further investigated “autoxidative glycosylation” by comparison of the behaviour of dog and bovine serum albumin with respect to the oxidative reactions of glucose and ascorbate. The proteins possess similar numbers of total amino residues available for glucose attachment but dog serum albumin contains fewer histidine groups and also lacks a high affinity copper-binding site. We find that the higher copper-binding capacity of bovine serum albumin is reflected in a lower rate of ascorbate oxidation as well as less protein oxidative damage than is the case for dog serum albumin. We also observe that modification of bovine serum albumin histidine groups by diethylpyrocarbonate enhances ascorbate-mediated protein fluorophore formation.